US20020192370A1 - Deposition reactor having vaporizing, mixing and cleaning capabilities - Google Patents

Abstract

An integrated deposition system is provided which is capable of vaporizing low vapor pressure liquid precursors and delivering this vapor into a processing region for use in the fabrication of advanced integrated circuits. The integrated deposition system is made up of a heated exhaust system, a remote plasma generator, a processing chamber and a liquid delivery system which together provide a commercially viable and production worthy system for depositing high capacity dielectric materials from low vapor pressure precursors, anneal those films while also providing commercially viable in-situ cleaning capability.

Description

BACKGROUND OF THE INVENTION
• 1. Field of the Invention[0001]
• This invention relates to an apparatus and process for the vaporization of liquid precursors and the controlled delivery of those precursors to form films on suitable substrates. More particularly, this invention relates to an apparatus and a method for the deposition of a high dielectric constant film, such as Tantalum Oxide (Ta[0002]₂O₅), on a silicon wafer to make integrated circuits useful in the manufacture of advanced dynamic random access memory (DRAM) modules and other semiconductor devices.
BACKGROUND OF THE INVENTION
• The desire for greater capacity integrated circuits (ICs) on smaller sized devices has increased interest in replacing today's 64 megabit DRAM with memory devices in the range of 256 megabit, 1 gigabit and higher. This need for increased capacity on the same or smaller substrate footprint device makes it necessary to replace conventional dielectric films previously used in stacked capacitor formation, such as silicon dioxide (SiO[0003]₂), with dielectric films having higher dielectric constants. Capacitors containing high-dielectric constant materials, such as Ta₂O₅, usually have much larger capacitance densities than standard SiO₂—Si₃N₄—SiO₂stack capacitors making them the materials of choice in IC fabrication. High dielectric constant films are desirable because they provide higher capacitance which enables closer spacing of devices without electrical interference which can increase transistor density. One material of increasing interest for stack capacitor fabrication is Tantalum Oxide which has a relative dielectric constant more than six times that of SiO₂.
• One common method of forming Tantalum oxide film is to vaporize a liquid Tantalum precursor and then deliver the Tantalum vapor to a deposition chamber. Such vapor delivery methods face numerous challenges because of the low vapor pressure of typical Tantalum precursors such as (Ta (OC2H[0004]₅)₅) or TAETO and Tantalum Tetraethoxide Dimethylaminoethoxide (Ta (OEt)₄(OCH₂CH₂N(Me)₂) or TAT-DMAE, both of which are liquid at room temperature and pressure. FIG. 1 graphically illustrates the large variation between the vapor pressure of Tantalum precursors and other representative prior-art precursors for other semiconductor related processes. For example, at 100° C. and 1 atm TAT-DMAE has about 0.3 Torr vapor pressure while TAETO has about 0.03 Torr vapor pressure. The vapor pressures for Tantalum precursors are remarkably lower than those precursors typically used in prior art vapor delivery systems which are intended to vaporize precursors having much higher vapor pressures. Again referring to FIG. 1, at 100° C. and 1 atm, TEOS, (Tetra Ethyl OrthoSilicate) which is commonly used in chemical vapor deposition processes to form SiO₂films and is the subject of several prior art vapor delivery systems, has a vapor pressure of almost 100 Torr. As a result of this vast difference in vapor pressure, prior art vapor delivery systems did not encounter nor provide solutions to many of the challenges resulting from the use of very low vapor pressure precursors such as TAETO and TAT-DMAE.
• Prior art vapor delivery systems commonly involved the use of an integrated liquid flow controller and vaporizer without a positive liquid shut-off valve. Such a configuration, when used with low vapor pressure Tantalum precursors, can lead to problems stabilizing the Tantalum vapor output and difficulty achieving the constant, repeatable Tantalum vapor output desirous in semiconductor device fabrication. Previous delivery systems, based upon experience with TEOS and other relatively high vapor pressure materials, allow for the flow controller and vaporizer to be separated by considerable distance or attach no significance to the distance between vaporizer and liquid flow meter. Positioning the vaporizer and flow meter according to prior art systems fail to adequately control Tantalum precursor vapor. Previous delivery systems are intended for use with higher vapor pressure precursors whose residuals can be adequately removed by applying low pressure or “pumping-down” the lines while flowing an inert gas like nitrogen. Purging techniques such as these fail with Tantalum systems because the low vapor pressure residual tantalum vapor creates a need to introduce a solvent, such as isopropyl alcohol, ethanol, hexane, or methanol into both the vaporization system and supply lines to remove residual Tantalum precursor vapor.[0005]
• Previous vapor delivery systems avoided precursor vapor condensation by heating the delivery lines usually by resorting to a flexible resistive heater which is wrapped around and held in direct contact with the line, and then insulated. Since such systems typically operated with precursor materials having a wide temperature range within which the precursor remains vaporous, the requirement to sample the temperature of any section of the heated line was low and typically a single thermocouple would be used to represent the temperature of piping sections as long as four to six feet. Since the object of large scale temperature control systems, such as wrapped lines and jacket-type heaters used in prior art systems, is to heat and monitor an average temperature of a large section of piping, such systems lack the ability to specifically control a single, smaller section of the vapor piping and generally have very low efficiency when higher line temperatures are desired. Vaporized Tantalum delivery systems maintain the Tantalum vapor above the vaporization temperature but below the decomposition temperature for a given Tantalum precursor. Once formed, the vaporous Tantalum must be maintained at elevated temperatures between about 130° C. and 190° C. for TAT-DMAE and between about 150° C. and 220° C. for TAETO. Because of the relatively high temperatures needed and the narrow temperature band available to low vapor pressure precursors such as TAT-DMAE and TAETO, Tantalum and other low vapor pressure liquid delivery systems would benefit from vapor delivery line temperature controls and methods which can achieve and efficiently provide the higher temperatures and greater temperature control needed for Tantalum vapor delivery. Additionally, finer temperature controls are desirous since the useable temperature range of vaporized low pressure liquids is smaller than prior art liquids. Because higher temperature vapor delivery is needed, Tantalum delivery systems would benefit from designs which minimize the length of heated vapor delivery lines. Minimizing the length of lines requiring heating not only reduces the overall system complexity but also decreases the footprint or overall size of the system.[0006]
• Current methods of Tantalum Oxide deposition use reaction rate limited chemical vapor deposition techniques. In reaction rate limited deposition processes, the deposition rate achieved under these conditions is largely influenced by the temperature of the reaction environment. Existing chemical vapor deposition reactors do not sufficiently address the thermal losses between the substrate onto which the Tantalum film is to be formed and internal chamber components such as the gas distribution showerhead. Such thermal losses and the resultant non-uniform thickness of deposited Tantalum illustrate the barriers to commercially viable Tantalum oxide film formation techniques. However, with commercially viable Tantalum deposition rates also comes the need for a viable, in-situ cleaning process which can remove Tantalum deposition formed on internal chamber components without harm to these components.[0007]
• There is a need for a Tantalum deposition apparatus which can deliver vaporized, measured Tantalum precursors which have been adequately mixed with process gases to a reaction chamber which provides a controlled deposition environment which overcomes the shortcoming of the previous systems. Additionally, there is also a need for a deposition apparatus capable of in-situ cleaning.[0008]
SUMMARY OF THE INVENTION
• In one aspect of the present invention, a deposition apparatus is provided for depositing tantalum oxides and other materials especially those with low vapor pressure liquid precursors which are provided as liquid to a vaporizer to be converted into the vapor phase. The vapor is then transported from the vaporizer into a substrate processing region via temperature controlled conduits where the temperature within the conduits allows neither condensation nor decomposition of the vaporized precursor. Separate thermocouple, heater, controller units control the temperature conduits so as to maintain a temperature within the conduit above the condensation temperature but below the decomposition temperature of a given precursor vapor or, more particularly, between about 130° C. and 190° C. for a Tantalum precursor such as TAT-DMAE or between about 150° C. and 220° C. for a Tantalum precursor such as TAETO. Additionally, the temperature controlled conduits could provide a temperature gradient along the vapor flow path between the vaporizer and the processing region. Other precursor source materials and dopants, alone or in combination, are also contemplated.[0009]
• In another aspect of the present invention, a resistive heater is embedded in the lid of the processing chamber which provides for elevated temperatures within the gas box formed between the lid and the showerhead gas distribution plate.[0010]
• In another aspect of the showerhead gas distribution plate of the present invention, the specific shape and spacing of the apertures which allow gas to enter into the processing region of the processing chamber present an angled lower surface towards a substrate within the processing region. The spacing and specific shape of the apertures allow more incident energy from the substrate to be absorbed into instead of reflected off the showerhead or where the emissivity of the showerhead is increased by the angled lower surface. Another feature of the present invention is modifying the surface of the showerhead lower surface which faces a substrate in the processing region. The modification results in a surface which has a high emissivity relative to the emissivity changes which result from film accumulation on the surface of the showerhead as well as other factors. Each of these features alone or in combination helps minimize substrate heat losses which contribute to temperature nonuniformities. The net effect of the aperture hole shapes, spacing and high emissivity modification or coating is that most of the radiation emitted from the substrate surface is absorbed by the showerhead.[0011]
• In another aspect of the present invention, a deposition system is provided for depositing tantalum oxides and other materials, especially those with low vapor pressures alone or in combination with a variety of processing gases or dopants. The deposition system is comprised of a heated exhaust system, a liquid delivery system, a remote plasma generator, and a processing chamber. In operation, the deposition system provides a method and apparatus capable of the controlled delivery of a variety of vaporized, low vapor pressure liquid precursors and activated species into a substrate processing region for cleaning, deposition or other operations.[0012]
BRIEF DESCRIPTION OF THE FIGURES
• FIG. 1 is a graph of Vapor Pressure (Torr) vs. Temperature (° C.) of various compositions;[0013]
• FIG. 2 is a perspective view of the processing system of the present invention;[0014]
• FIG. 3 is a perspective view of four representative processing systems of the present invention mounted on a typical central wafer handling system;[0015]
• FIG. 4 is a cross sectional view of a processing chamber of the present invention;[0016]
• FIG. 5 is a top view of the lid of the present invention;[0017]
• FIG. 6 is a top view of a[0018]showerhead having apertures249;
• FIG. 7 is a sectional view of[0019]apertures249;
• FIG. 8 is a top view of a[0020]showerhead having apertures238;
• FIG. 9 is a sectional view of[0021]apertures238;
• FIG. 10 is a plan view of the spacing between aperture outlets;[0022]
• FIG. 11 is a table listing the representative distribution of[0023]apertures238;
• FIG. 12 is a table listing the representative distribution of[0024]apertures249;
• FIG. 13 is a sectional view of reflected and absorbed radiation within apertures of the present invention;[0025]
• FIG. 14 is a sectional view of gas delivery lines within a heated gas feed through assembly of the present invention;[0026]
• FIG. 15 is a perspective view of an embodiment of the exhaust system and remote plasma generator of the present invention;[0027]
• FIG. 16 is a schematic view of a typical remote plasma generator;[0028]
• FIG. 17 is a perspective view of the vapor delivery system of the present invention;[0029]
• FIG. 18 is a schematic drawing of a representative liquid mass flow controller of the present invention;[0030]
• FIG. 19 is a schematic drawing of a representative liquid delivery system having one vaporizer;[0031]
• FIG. 20 is a schematic drawing of a representative liquid delivery system having two vaporizers;[0032]
• FIG. 21 is a table summarizing Liquid Alignment Configurations of the vapor delivery system.[0033]
DETAILED DESCRIPTION OF THE INVENTION
• The present invention is directed to a novel liquid delivery system, chemical vapor deposition (CVD) chamber, exhaust system and remote plasma generator which together comprise a unique system especially useful in depositing thin metal-oxide films as well as other films requiring vaporization of low volatility precursor liquids. The system also provides for an in-situ cleaning process for the removal of metal-oxide films deposited on interior surfaces of a deposition chamber. The system also has application in the use of fabricating metal-oxide dielectrics useful in making ultra large scale integration (ULSI) DRAM and other advanced feature electronic devices which require the deposition of high dielectric constant materials. In general, devices that can be made with the system of the present invention are those devices characterized by having one or more layers of insulating, dielectric or electrode material on a suitable substrate such as silicon. One skilled in the art will appreciate the ability to use alternative configuration and process details to the disclosed specifics without departing from the scope of the present invention. In other instances, well known semiconductor processing equipment and methodology have not been described in order not to unnecessarily obscure the present invention.[0034]
• FIG. 2 is a perspective view of the[0035]processing system100 showing the relative positions of the main components of the present invention.System100 contains aprocessing chamber200, aheated exhaust system300, aremote plasma generator400 and avapor delivery system500. Also shown in FIG. 2 is a centralsubstrate transfer chamber110 representative of a cluster tool embodiment of the processing system of the present invention.Processing chamber200 is comprised oflid205 andchamber body210 and is attached tocentral transfer chamber110. Gases supplied vialiquid delivery system500 are provided into a processing region202 (not shown) withinchamber200 via temperature controlled conduits formed withininlet block272, mixingblock266 andcentral block262.Cartridge style heaters264 are integrally formed into each block and, in conjunction with individual thermocouples and controllers, maintain temperature set points within the conduits. For clarity, individual thermocouples and controllers have been omitted. Not visible in FIG. 2 but an aspect of the present invention is embeddedlid heater235 located integral tolid205 beneathheater backing plate234.
• [0036]Chamber200 processing by-products are exhausted viaheated exhaust system300 which is coupled tochamber200 viaexhaust port305. Also shown areisolation valve310,throttle valve315, chamber by-pass320,cold trap325 and coldtrap isolation valve330. For clarity, specific embodiments ofvacuum pump335 and wafer fabrication plantexhaust treatment systems340 are not shown. In order to provide a clearer representation of the interrelationship between and relative placement of each of the components ofheated exhaust system300, the jacket type heaters, thermocouples and controllers used to maintain setpoint temperatures inexhaust port305,isolation valve310,throttle valve315, chamber by-pass320, and by-pass line322 have been omitted.
• Activated species are generated by[0037]remote plasma generator400 and provided to a processing region withinchamber200 via conduits within activatedspecies inlet block420, activated species block270 andcentral block262. Other components ofremote plasma generator400 such asmagnetron402,auto tuner controller410, andauto tuner408 are visible in FIG. 2.
• One of the main components of[0038]liquid delivery system500 isliquid flow meter510 andvaporizer520. Three-way inlet valve588 allows eitherprecursor503 or solvent591 intovapor delivery system500.Heat exchangers530 and582 preheat carrier gases and process gases respectively. Heated carrier gases travel via a carriergas supply line532 tovaporizer520 in order to facilitate more complete vaporization withinvaporizer520 as well as carry vaporized liquids tochamber200. After vaporization invaporizer520, chamber by-pass valve545 allows vapor to be ported either toprocessing region202 inchamber200 viaoutlet582 or toexhaust system300 viaoutlet555 which is coupled to heated by-pass line322. A jacket style heater, thermocouple and controller which maintain the temperature of chamber by-pass valve545 and vaporizedprecursor line560 as well as the jacket style heater, thermocouple and controller which maintain the temperature of by-pass line322 have been omitted so as not to obscure the components ofliquid delivery system500 and their relationship tochamber200 andheated exhaust system300.
• The size and dimensions of the various components and the placement of these components in relation to each other are determined by the size of the substrate on which the processes of the present invention are being performed. A preferred embodiment of the invention will be described herein with reference to a[0039]processing system100 adapted to process a circular substrate, such as a silicon wafer, having a 200 mm diameter. Although described in reference to a single substrate, one of ordinary skill in the art of semiconductor processing will appreciate that the methods and various embodiments of the present invention are adaptable to the processing of multiple substrates within asingle chamber200.
• Turning now to FIG. 3, which is a perspective view of a plurality of[0040]processing systems100 arranged in a cluster tool arrangement around centralsubstrate transfer chamber110 and supported by commonmainframe support structure105. The Centura® mainframe system, manufactured by Applied Materials, Inc. of Santa Clara, Calif., is representative of one such cluster tool arrangement. This arrangement allows multiple chambers, shown here comprising fourprocessing systems100 of the present invention, to share acommon vacuum transfer110. One advantage of such an arrangement is that the central substrate transfer also has attached to it a loadlock or loadlocks which hold a plurality of substrates for processing in chambers attached to thecentral substrate transfer110. Although FIG. 3 illustrates fouridentical processing systems100, another advantage of the cluster tool arrangement is the ability to place a variety of chamber types onto a singlecentral substrate transfer110. In such an arrangement, a substrate may move between chambers arranged aroundcentral substrate transfer110 without exposure to an air or oxygen ambient. Not shown in FIG. 3, but a feature of thedeposition system100 of the present invention, either one or a plurality ofdeposition systems100 may be arranged in communication withcentral substrate transfer110 with a variety of predetermined chamber types such that a substrate could be loaded into the loadlock attached acentral substrate transfer110, sequence through the various chambers and as a result of the sequencing form predetermined and desirous films on a substrate processed in this manner. It is anticipated thatdeposition system100, in conjunction with other chamber types, would be capable of forming complete portions of an IC. Specifically anticipated is the selection of chamber types, sequencing and liquid delivery configurations which would result in the formation of a representative stack capacitor having polysilicon bottom and top electrodes separated by silicon nitride and titanium nitride barrier layers which are separated by a tantalum oxide dielectric layer. Other layers and structures are also anticipated and are intended to be included within the capabilities of the methods and apparatus described herein. It is also specifically anticipated that asingle deposition system100 would alone have the processing capability of forming complete portions of an IC.
• [0041]Chamber200 is shown withprotective cover203 in place. Cover203 enclosesheated chamber lid205 and temperature controlled conduit blocks272,266 and262. Cover203 is maintained at a relatively safe temperature so as to prevent burn injuries from contact with the heated components oflid205.
• [0042]Remote plasma generator400 is also shown in an alternative embodiment in which the generator is supported from the top ofmainframe105 instead of from below as shown in FIG. 2. So as not to obstruct the view of an alternative embodiment ofremote plasma generator400,heated exhaust system300 is not shown. Such a support arrangement ofremote plasma generator400 provides easier accessibility and maintenance of other components ofdeposition system100 as well as contributing to the reduction of the overall footprint ofdeposition system100. The embodiment of the plurality ofprocessing systems100 of FIG. 3 further illustrate the compact design features ofsystem100 of the present invention.
• The Deposition Chamber[0043]
• FIG. 4 is a cross sectional view of[0044]chamber assembly200 ofprocessing system100 of FIG. 2.Chamber body210 andheated chamber lid205, which is hingedly connected tochamber body210, together with o-ring245 form a temperature and pressure controlled environment orprocessing region202 which enables deposition processes and other operations to be performed withinprocessing region202.Chamber body210 andlid205 are preferably made of a rigid material such as aluminum, various nickel alloys or other materials having good thermal conductivity. O-ring245 could be formed from Chemraz, Kalrez, Viton or other suitable sealing material.
• When[0045]lid205 is closed as shown in FIG. 4, anannular processing region202 is formed which is bounded byshowerhead240,substrate support250 and the walls ofchamber body210. Substrate support250 (shown in the raised position for processing) extends through the bottom ofchamber body210. Imbedded withinsubstrate support250 is a resistive heater which receives power via resistive heating elementelectrical connector257. A thermocouple in thermal contact withsubstrate support250 senses the temperature ofsubstrate support250 and is part of a closed loop control circuit which allows precise temperature control ofheated substrate support250.Substrate support250 andsubstrate201 are parallel toshowerhead240.Substrate201 is supported by the upper surface ofsupport250 and is heated by the resistive heaters withinsubstrate support250 to processing temperatures of, for example, between about 400° C. and 500° C. for Tantalum films formed using the methods and apparatus of the present invention.
• Processing[0046]chamber200 is coupled tocentral transfer chamber110 viaopening214. Aslit valve215seals processing region202 fromcentral transfer chamber110.Substrate support250 may also move vertically into alignment withopening214 which, when slitvalve215 is open, allows substrates to move between theprocessing region202 and centralsubstrate transfer chamber110.Substrate201 can be a substrate used in the manufacture of semiconductor products such as silicon substrates and gallium arsenide substrates and can be other substrates used for other purposes such as substrates used in the production of flat panel displays.
• [0047]Pumping passage203 andoutlet port260 formed withinchamber body210 for removing by products of processing operations conducted withinprocessing region202.Outlet port260 provides fluid communication between components ofheated exhaust system300 andprocessing region202.
• Turning now to gas delivery features of[0048]chamber200, both process gas/precursor mixture fromliquid delivery system500, viaconduit273, and activated species from remoteplasma generator system400, viaconduit271, flow throughcentral conduit231 to bore through230 formed inlid205. From there, gases and activated species flow throughblocker plate237 andshowerhead240 intoprocessing region202. A feature ofshowerhead240 of the present invention is the plurality ofapertures249, oralternative aperture embodiment238, which are not indicated in FIG. 4 so as not to unnecessarily obscure understanding specific details and features ofchamber200 andheated lid205.
• Process gas and vaporized precursors and mixtures thereof are provided to central bore through[0049]230 via temperature controlled conduits formed integral to heated feed throughassembly220. Heated feed throughassembly220 is comprised ofcentral block262, mixed deposition gas feed throughblock266 and inlet and mixingblock272. Although the embodiment represented inchamber200 of FIG. 4 indicates a heated feed throughassembly220 comprising threeseparate blocks262,266 and272, one of ordinary skill will appreciate that the blocks can be combined such as replacing inlet and mixingblock272 and feed throughblock266 with a single block without departing from the spirit of the present invention. Additionally, a plurality ofcartridge heaters264 are disposed internal to each of the aforementioned blocks and proximate to theconduits231,273,278,265, and276 which maintain a setpoint in each conduit utilizing separate controllers and thermocouples for the heater of a particular conduit. For clarity, the separate thermocouples and controllers have been omitted.
• [0050]Lid205 is also provided with acooling channel244 which circulates cooling water within that portion oflid205 in proximity to o-ring245.Cooling channel244 allowslid205 to maintain the temperatures preferred for advantageous heating ofshowerhead240 while protecting o-ring245 from the high temperatures which degrade the sealing qualities of o-ring245 thereby making o-ring245 more susceptible to attack by the reactive species generated and supplied toprocessing region202 byremote plasma generator400.
• Another feature of[0051]processing chamber200 of the present invention also shown in FIG. 4 is embeddedresistive heater235 withinlid205. This feature ofchamber assembly200 provides elevated temperatures inlid205 in proximity to central bore through230 and the area between the lower surface of thelid205 and showerheadupper surface263. The region betweenlid205 and showerheadupper surface263 is referred to as the “gas box”. Formed within the top surface oflid205 is an annular groove shaped according to the size and shape of imbeddedheater235 in order to increase surface contact and heat transfer betweenresistive heater235 andlid205. Withoutheater235, coolingchannel244 could continuously remove heat fromlid205. As a result, coolingchannel244 also affects the temperature of portions oflid205 in contact with precursor vapor, such as the area surrounding central bore through230 and the gas box. Whilecooler lid205 temperatures improve conditions for o-ring245,cooler lid205 temperatures could result in undesired condensation of precursor vapor. Thus, it is to be appreciated thatresistive heater235 is positioned to heat those portions oflid205 in contact with the vaporized precursor flow such as the gas box and the area surrounding central bore through230. As shown in FIG. 4, for example,heater235 is located between coolingchannel244 and central bore through230 while also positioned to provide heating to the lid surface adjacent toblocker plate237.
• Referring now to FIG. 5 which is a top view of[0052]lid205, the relationship of embeddedheater235 to other components mounted onlid205 can be better appreciated. Embeddedheater235 is indicated in phantom and is located beneath backingplate234. Backingplate234 andfasteners243 help increase the surface area contact between embeddedheater235 andlid205 thereby improving the efficiency of heat transfer betweenheater235 andlid205.Lid205 also has an embeddedthermocouple204 for monitoring the temperature withinlid205 in proximity toheater235.Thermocouple204 is part of a feedback control circuit which monitors and controls the power supplied toheater235 to obtain a set point temperature withinlid205. Precise temperature control is desired inlid205, as in all components in contact with vaporized precursor, in order to provide conditions which neither condense nor decompose low vapor pressure precursors such as TAT-DMAE and TAETO.
• For a representative 200 mm embodiment of[0053]chamber200 shown in FIG. 4,heater235 could have a 650 W output rating and is commercially available from a variety of commercial sources such as Watlow, Inc. of Richmond, Ill. Temperature setpoints between about 80° C. and 180° C. are readily obtained inlid205 utilizing aheater235 rated at about 650 Watts. It will be appreciate that various heater ratings, set-points and configurations could be utilized to obtain a wide range of temperature set-points depending upon the decomposition and condensation temperatures and other characteristics of the precursor material used. Although imbeddedheater235 is represented by a single, continuous, circular element, one of ordinary skill will appreciate that alternative embodiments wherein a plurality of continuous or discontinuous embeddedheaters235 are arranged withinlid205 to provide additional heat or greater temperature control withinlid205 are within the scope of the present invention.
• Referring again to FIG. 4,[0054]heated lid205 provides support forshowerhead240 andblocker plate237. As such,showerhead240 is attached tolid205 via a plurality of evenly spacedfasteners242 andblocker plate237 is attached tolid205 by a plurality of evenly spacedfasteners217.Fasteners217 and242 are formed from a rigid material such as aluminum, varieties of nickel alloys and other materials having good thermal conductivity.Fasteners242 and217 provide clamping force which increases the contact area betweenheated lid205 and the and thegas distribution components237 and240.Fasteners242 and217 have been advantageously placed to provide clamping force to increase contact betweenheated lid205 andshowerhead240 in the case offasteners242 andheated lid205 andblocker plate237 in the case offasteners217. Increased contact area produces greater heat transfer betweenheated lid205 andblocker plate237 andshowerhead240.
• Turning now to FIGS. 6, 7,[0055]8,9 and13, the reduced reflection and increased absorption features ofshowerhead240 ofprocessing chamber200 the present invention can be better appreciated. FIGS. 6 and 8 illustrate a plan views of showerheadlower surface284 as viewed from asubstrate201 positioned onsubstrate support250. Viewed fromsubstrate20 land looking towardslid205 as in FIGS. 6 and 8 evenly spacedfasteners242 are visible on the periphery of showerheadlower surface284.Showerhead240 also comprises a plurality of apertures249 (FIG. 6 ) and238 (FIG. 8 ) which allow gases and activated species to enterprocessing region202.
• Referring now to FIG. 7 the specific details and unique geometry of an[0056]aperture249 can be better understood. FIG. 7 is a sectional view of an embodiment of a plurality ofrepresentative apertures249 which is indicated as view L-L on FIG. 5.Aperture249 includes anupper region291, aconical region290 and alower region248. A plurality ofapertures249 are distributed acrossshowerhead240 thereby allowing gases to flow fromblocker plate237 throughaperture249 tosubstrate201. Gas fromblocker plate237 flows onto showerheadupper surface263 and intoinlets291 ofapertures249.Inlet291 is axially symmetric toaperture centerline267 and could be cylindrically shaped with adiameter247 of 0.028 inches.Inlet291 is bounded by showerheadupper surface263 and inletparallel walls269. Gas flows out ofinlet291 and into lowerconical region290 which is defined bydivergent walls255 which are axially symmetric toaperture centerline267. For example, lowerconic region290 has anupstream diameter256 measured betweenwalls255 which is smaller than a downstream lowerconic region diameter258. Extendingdivergent walls255 to intersect atvertex259, as indicated by dashedlines296, angle β is formed. Angle β is axially symmetric toaperture centerline267 such thatvertex259 is on and bisected byaperture centerline267. Angle β is measured betweendivergent walls255 andvertex259. Thus, the angled surfaces ofdivergent walls255 are presented tosubstrate201.
• From lower[0057]conic region290 gas flows intooutlet248 which hasparallel walls281, adiameter288 and is axially symmetric aboutcenterline267.Parallel walls281 have alength283 measured between the intersection ofdivergent walls255 andparallel walls281 and showerheadlower surface284. Gas flowing out ofoutlet248 flows towardssubstrate201 withinprocessing region202.
• The geometry and other specific aspects of[0058]aperture249 are more clearly understood by describing the ratios between various aperture components. For example,inlet diameter247 is less thanoutlet diameter288 orinlet diameter247 could be about one-third ofoutlet diameter288 such as when arepresentative aperture249 has aninlet diameter247 of 0.028 inches and anoutlet diameter288 of 0.086 inches.
• Another aspect of[0059]aperture249 is the ratio betweenlength283 of outletparallel walls281 andoutlet diameter288 wherelength283 is greater thandiameter288 or wherelength283 is about 2.5times outlet diameter288. For example, arepresentative aperture249 could have anoutlet diameter288 of about 0.086 inches and alength283 of about 0.221 inches. Another aspect ofaperture249 is thatlength283 ofparallel walls281 is greater than the length ofdivergent walls255 or whereparallel walls281 are about 5.5 times as long asdivergent walls255. For example, thelength283 is about 0.221 inches and the length ofdivergent walls255 is about 0.041 inches which results in a ratio of thelength283 ofparallel walls281 to the length ofdivergent walls255 of about 5.39. Utilizing the ratios above, representative dimensions for each of a plurality ofapertures249 in arepresentative showerhead240 fabricated from aluminum having a thickness of about 0.5 inches are: aninlet diameter247 of about 0.028 inches; with inletparallel walls269 of about 0.25 inches; anoutlet diameter288 of about 0.086 inches with outletparallel walls length283 of about 0.221 inches.
• Referring now to FIG. 9 the specific details and unique geometry of an alternative aperture embodiment,[0060]aperture238, can be better understood. FIG. 9 is a sectional view of an embodiment of a singlealternative aperture238 indicated by view D-D on FIG. 8. A plurality ofapertures238, likeaperture249, are distributed acrossshowerhead240 thereby allowing gases to flow fromblocker plate237 throughaperture238 tosubstrate201.Aperture238 includes anupper region291, an upperconical region289, acentral region246, a lowerconical region290 and alower region248. Gas fromblocker plate237 flows onto showerheadupper surface263 and intoinlet291.Inlet291 is axially symmetric toaperture centerline267 and could be cylindrically shaped with adiameter247 of 0.110 inches.Inlet291 is bounded by showerheadupper surface263 and inletparallel walls269. Gas flows throughinlet291 into upperconic region289 which is bounded by convergingwalls251. Upperconic region289 is axially symmetric toaperture centerline267 and has a decreasing downstream diameter such that an upper conic regionupstream diameter252 is greater than an upper conic regiondownstream diameter253. Convergingwalls251, if extended to an intersection point as indicated by dashedlines295, would intersect atvertex254 forming an angle a. Angle a is axially symmetric toaperture centerline267 such thatvertex254 is onaperture centerline267 and angle a is bisected byaperture centerline267. Angle α, measured betweenconvergent walls251 andvertex254, is between about 25° and about 45°.
• From upper[0061]conic region289, gas flows into acentral conduit246 which is axially symmetric toaperture centerline267.Central conduit246 could be cylindrically shaped with adiameter287 of about 0.028 inches.Central conduit246 acts as a coupling conduit joining the upperconic region289 and the lowerconic region290 thus allowing gas flow frominlet291 tooutlet248. Gas flows fromcentral conduit246 into lowerconical region290 which is defined bydivergent walls255 and is axially symmetric toaperture centerline267. For example, lowerconic region290 has anupstream diameter256 betweenwalls255 which is smaller than a downstream lowerconic region diameter258.Divergent walls255, if extended to an intersection point as indicated by dashedlines296, would intersect atvertex259 forming an angle β. Angle β is axially symmetric toaperture centerline267 such thatvertex259 is on and bisected byaperture centerline267. Angle β is measured betweendivergent walls255 andvertex259. The angled surfaces withinshowerhead240 formed bydivergent walls255 are presented tosubstrate201.
• Gas flows from lower[0062]conic region290 intooutlet248 which is axially symmetric aboutcenterline267.Outlet248 could be cylindrically shaped havingparallel walls281 and adiameter288.Parallel walls281 have alength283 measured between the intersection ofdivergent walls255 andparallel walls281 and showerheadlower surface284. Gas flowing out ofoutlet248 flows towardssubstrate201 withinprocessing region202.
• The geometry and other specific aspects of[0063]aperture238 are more clearly understood by describing the ratios between various aperture components. One aspect ofaperture238 is thatinlet diameter247 is less thanoutlet diameter288 orinlet diameter247 is about one-half ofoutlet diameter288. Arepresentative aperture238 could have aninlet diameter247 of 0.110 inches and anoutlet diameter288 of 0.213 inches. Another aspect ofaperture238 is the ratio between theinlet247 andoutlet288 diameters and thecentral region diameter287 wherecentral region diameter287 is less than bothinlet diameter247 andoutlet diameter288.Central region diameter287 is about 0.25 ofinlet diameter247 and about 0.13 ofoutlet diameter288. For example, arepresentative aperture238 could have aninlet diameter247 of 0.110 inches, anoutlet diameter288 of 0.213 inches and a central region diameter of about 0.028 inches.
• Another aspect of[0064]aperture238 is the ratio betweenlength283 of outletparallel walls281 andoutlet diameter288 wherelength283 is less thandiameter288. For example,length283 is about three quarters or about 0.7633 ofdiameter288, as in anoutlet248 having alength283 of 0.1569 inches and adiameter288 of 0.213 inches. Another aspect ofaperture238 is that thelength283 ofparallel walls281 is greater than the length ofdivergent walls255 or whereparallel walls281 are about 1.5 times as long asdivergent walls255. For example, for theaperture238 dimensions detailed above, thelength283 is about 0.1569 inches and the length ofdivergent walls255 is about 0.1021 inches which results in a ratio of thelength283 ofparallel walls281 to the length ofdivergent walls255 of about 1.53. Given the above ratios, dimensions for each of a plurality ofrepresentative apertures238 in analuminum showerhead240 having a thickness of about 0.4 inches are: aninlet diameter247 of about 0.110 inches; a centralcylindrical region diameter287 of about 0.028 inches withparallel walls286 of about 0.080 inches; and anoutlet diameter288 of about 0.213 inches with outletparallel walls281length283 of about 0.1569 inches anddivergent walls255 of about 0.1021 inches. Although described as circular, the general shape ofinlet291,central conduit246 andoutlet248 of anaperture238 as well as theinlet291 andoutlet248 of anapparatus249 may also have various other shapes such as heptagonal, octagonal or other higher order polygons without departing from the scope of the present invention. It is to be appreciated that the above cited specific details with respect toaperture238 and249 are only representative embodiments of the unique aperture geometry of the present invention.
• As mentioned above, in reaction rate limited processes, such as the deposition of tantalum pentaoxide or other transition metal dielectrics, one key factor for controlling deposition rate is the temperature of[0065]substrate201. Thus, temperature variations which influencesubstrate201 should be minimized to assist in obtaining more uniform deposition rates. One source of temperature variation occurs when radiant energy fromsubstrate201 andheated substrate support250 reflects offshowerhead240 back tosubstrate201. This redirected reflected energy is uncontrolled and asymmetric resulting in temperature variations within asingle substrate201 and in consecutively processedsubstrates201. Showerheadlower surface284 anddivergent walls255 ofapertures249 and238 are reflected surfaces for radiant energy fromsubstrate201 andheated substrate support250. Advantageously selecting the aperture geometry presented tosubstrate201 is one method of increasing the emissivity ofshowerhead240.
• Two features of[0066]apertures238 and249 of the present invention which increase the emissivity ofshowerhead240 are spacing261 between apertures and the advantageous geometry ofaperture outlets248. The advantageous geometry ofoutlet248 is discussed in detail below with respect to FIG. 13. Turning now to FIGS. 6 and 8 a plurality ofapertures249, shown in FIG. 6, andapertures238, shown in FIG. 8, are evenly distributed acrossshowerhead240 resulting in a pattern ofoutlets248 in showerheadlower surface284. FIG. 10, which is an enlarged view E indicated on FIG. 8, represents the spatial relationship betweenadjacent outlets248 regardless of aperture type.Outlets248 are spaced across showerheadlower surface284 such that the flat, reflective space betweenadjacent outlets248 is minimized. The spacing betweenoutlets248, spacing261, which represents the width of the flat reflective space betweenoutlets248 should be as small as possible. Another method of spacingoutlets248 acrossshowerhead240lower surface284 is to separateadjacent aperture centerlines267 by someconstant distance285.Constant spacing distance285 is selected based onoutlet diameter248 and desiredspacing261. For example, anaperture238 having anoutlet diameter248 of 0.213 inches and a desiredspacing261 of 0.005 inches would have a centerline spacing285 of 0.218 inches. In another example, anaperture238 having anoutlet diameter248 of 0.086 inches and a desiredspacing261 of 0.012 inches would have a centerline spacing285 of 0.098 inches.
• As the number of apertures increases, spacing[0067]261 decreases for a givensize showerhead240. This not only reduces the reflective surface betweenoutlets248 but also increases the amount of angled reflective surface created bydivergent walls255 of each aperture. In one respect, the distribution ofapertures249 and238 can be viewed as replacing the flat, highly reflective surface betweenoutlets248 oflower showerhead surface284 withdivergent walls255. Distributingapertures249 and238 by minimizing outlet spacing261 increases the number and density ofapertures249 and238 which correspondingly increases the number and density ofdivergent walls255 presented tosubstrate201. As the amount of divergent wall surface area increases, the probability that incident radiation ontoshowerhead240 will be reflected and absorbed intoshowerhead240 also increases.
• Referring now to FIG. 11, a representative distribution of[0068]apertures238 for ashowerhead240 sized to process 200 mm substrates can be better appreciated. FIG. 11 is a table listingrepresentative aperture238 locations using a coordinate system having X and Y axes similar to the system shown in FIG. 7 with an origin in the center ofshowerhead240. FIG. 11 indicates ordinate and abscissa values for afirst aperture238 in a row ofapertures238 which form a representative distribution ofapertures238 having a minimizedflat surface261 between eachaperture238. Using FIG. 11 as a guide for the placement of eachaperture238 results in the distribution of about1574apertures238 acrossshowerhead240. This distribution pattern is similar to the pattern ofoutlets248 illustrated in FIG. 8. Referring now to FIG. 12, a distribution pattern for a plurality ofapertures249 can be better appreciated. FIG. 12 is a table listingrepresentative aperture249 locations using a coordinate system having X and Y axes similar to the system shown in FIG. 6 with an origin in the center ofshowerhead240 used for processing 200mm diameter substrates201. FIG. 12 indicates ordinate and abscissa values for afirst aperture249 in a row ofapertures249 which form a representative distribution ofapertures249 having a minimizedflat surface261 between eachaperture249. Using FIG. 12 as a guide for the placement of eachaperture249 results in the distribution of about6165apertures249 acrossshowerhead240. This distribution pattern is similar to the pattern ofoutlets248 illustrated in FIG. 6.
• Turning now to FIG. 13, the novel reflective and absorptive characteristics of[0069]apertures238 and249 of the present invention can be better appreciated. Although FIG. 13 is a sectional view of an aperture according toaperture249, the aspects of the present invention which follow also apply toaperture embodiment238 as well as to other specific aperture embodiments made according to the present invention. In this aspect of the present invention, the specific geometric arrangement betweendivergent walls255, angle β,parallel walls281 andoutlet diameter288 is selected in order to increase the emissivity ofshowerhead240. More specifically, by advantageously selecting an angle β, for example,outlet diameter288 and length ofparallel walls281 can be selected such that radiation reflected offdivergent walls255 is absorbed intoshowerhead240. The reflected radiation could then, for example, be absorbed intoshowerhead240 through single reflections or multiple reflections withwalls281 or other aperture surfaces withinshowerhead240.
• The minimized spacing between adjacent outlets feature aspect of[0070]showerhead240 of the present invention is also illustrated in FIG. 13.Radiation222 represents that radiation normal to showerheadlower surface284. Whennormal radiation222 intersects the generally flat, highlyreflective surface284, the result is normal reflectedradiation223. It will be appreciated therefore, that asaperture spacing261 decreases, morenormal radiation222 will be incident ontodivergent walls255 and the highly absorptive geometry ofapertures238 orapertures249.
• In another aspect of the present invention, the relationship between[0071]divergent walls255 andoutlet walls281 is utilized to facilitate absorption of reflected radiation intoshowerhead240.Divergent walls255 and the angle β between them provide a reflective surface torepresentative incident radiation206 and208. For example,incident radiation208 intersectsdivergent wall255. A portion ofradiation208 will be absorbed bywall255 and a portion will be reflected asradiation209. Because of the angled presentation ofdivergent wall255, reflectedradiation209 intersectswall269. A portion ofradiation209 is absorbed in the first intersection and a portion is reflected. This process of absorption and reflection continues as reflectedradiation209 is reflected and absorbed bywalls269. In another example,incident radiation206 intersectsdivergent wall255 and a portion ofradiation206 is absorbed bywall255. A portion ofradiation206 is reflected bywall255 forming reflectedradiation207. As a result of the selection of angle β, reflectedradiation207 crosseslower region248 and intersects an adjacentdivergent wall255. In the second intersection, a portion ofradiation207 is absorbed bywall255 and a portion is reflected. FIG. 13 illustrates an aperture configuration whereradiation206—i.e. radiation reflected intolower region248—is absorbed intowalls281. It is to be appreciated that angle β,length283 anddiameter288 could be selected such that radiation reflected into thelower region248 would have multiple refection and absorption reactions withwalls281 and255. By advantageously selecting the outlet diameter, angle β, and the length ofwalls281, apertures according to the present invention will first reflect radiation usingdivergent walls255 then absorb radiation viaparallel walls281 thereby reducing reflective radiation produced byshowerhead240. In order to absorb reflected radiant energy, such as reflectedenergy207,walls281 are generally between about 1.5 and 5.5 times the length ofdivergent walls255 for a given angle β. For arepresentative aperture249 located within ashowerhead240 having a thickness of about 0.5 inches and an angle β of about 90°,divergent walls255 are about 0.04,1 inches whilewalls281 are about 0.221 inches. In arepresentative aperture248 located within ashowerhead240 having a thickness of about 0.4 inches and an angle β of about 130°,divergent walls255 are about 0.1021 inches whilewalls281 are about 0.1569 inches. One of ordinary skill in the art will appreciate that numerous showerhead thicknesses,outlet diameters288, lengths ofwalls281 and angles β may be combined to provide a varieties of aperture geometry capable of absorbing incident radiation according to the methods of the present invention.
• In another aspect of the present invention, the emissivity (ε) of the surface of[0072]showerhead240 is intended to be as high as possible in order to approximate the emissivity of a black body. An object of the present invention is to provideshowerhead240 emissivity in the range of about 0.6 to about 0.9. Those of ordinary skill in the art will appreciate that a variety of surface finishing techniques, such as anodization, oxidation, ceramic coating or bead blasting may be employed to obtain the desired emissivity. Film accumulation onshowerhead240 occurs during sequential deposition processes withinprocessing region240. A showerhead with film deposits absorbs more incident radiation than a showerhead without those accumulations. The resulting absorption variation and temperature difference film accumulation causes is a source of thickness uniformity variation between consecutively processed wafers. For purposes of illustration, suppose the resulting accumulation of film causes an average emissivity change (ε_ch) of 0.05 inshowerhead240. For reaction rate limited processes—which rely on temperature—such a seemingly minor variation in emissivity can result in wafer-to-wafer temperature variations which can in turn result in deposition rate and thickness non-uniformities between wafers processed in the same chamber. For example, a showerhead having a unpolished metal surface may have an emissivity (ε_um) of about 0.4. As a result of processing several wafers, ε_umcould have been increased by ε_chor 0.05 to 0.45 representing a 12.5% change in emissivity. Even if oxidized metals with an emissivity (ε_om) of about 0.45 are used, the emissivity change resulting from the same amount of film deposition—an 0.05 increase in emissivity—results in an emissivity change of 11.1%. Not until highly oxidized metals (ε≈0.7) or even anodized surfaces (ε≈0.9) are employed does the impact of representative emissivity change ε_chproduce emissivity variation below 10%. Utilizing ashowerhead240 with a higher initial emissivity reduces the impact of later emissivity varying events such as the accumulation of film onshowerhead240. An object of the present invention is to increase the absorptive characteristics or emissivity ofshowerhead240 such that the emissivity variation induced by film accumulation is reduced or, in other words, the emissivity ofshowerhead240 is sufficiently high that it could be said to be invariant. For example, ashowerhead240 having an emissivity above about 0.6 or a sufficiently high emissivity such as between 0.7 and 0.9 which changes by less than 10% after repeated exposure to processing environments like those found inprocessing region202.
• Another object of the present invention is to reduce the temperature variations from one[0073]substrate201 to another in a continuously running reactor as in, for example, reactors utilized in reaction rate limited processes such as the deposition of tantalum pentaoxide. Either of the emissivity increasing methods described above (i.e., modification of showerhead surface or selecting highly absorptive aperture geometry) can be employed alone or in combination to increase the emissivity ofshowerhead240 and thereby reduce temperature variations. First, reflective surfaces onlower showerhead surface284 have been minimized by adjusting the spacing261 betweenoutlets248. Minimizing the spacing261 betweenoutlets248 effectively substitutes thedivergent walls255 ofapertures238 and249 in the place of flat, highly reflective surfaces. Second, thedivergent walls255 and shape of lowerconic region290 in conjunction withparallel walls281 of each of the plurality ofapertures238, or alternatively249, result in reflective radiation patterns which will likely be absorbed byshowerhead240 instead of reflected back tosubstrate201. Third, the emissivity of thematerial forming showerhead240 has been modified resulting in a is sufficiently high emissivity such that emissivity varying events, such as the accumulation of deposits during substrate processing, result in an over all emissivity change of less than 10%. The showerhead emissivity could be said to be invariant since emissivity change as a result of wafer processing operations withinprocessing region202 is slight or less than 10% of total emissivity. As a result, sequentially processed wafers are exposed to a more similar processing environment since the emissivity of a showerhead of the present invention is nearly constant or invariant between consecutive wafers.
• The elevated temperature of[0074]showerhead240 which results from increased absorption of radiation provides several advantages tochamber200. As mentioned above, the elevated temperature achieved inshowerhead240 can reduce or completely prevent undesirous vapor condensation which may likely occur or occur at a greater rate at lower showerhead temperatures. Another advantage is that as the temperature ofshowerhead240 increases, the temperature difference betweenshowerhead240 andsubstrate201 decreases. As the temperature difference decreases, the rate of heat transfer between the substrate and the showerhead also decreases. Controlling or minimizing heat losses fromsubstrate201 is critically important in reaction rate limited processes, such as the formation of Tantalum oxide which is an object ofprocessing system100 of the present invention. The rate of heat loss fromsubstrate201 impacts the deposition temperature which is one influential factor for controlling deposition rate and thickness uniformity of films formed onsubstrate201. Therefore, decreasing the rate of heat transfer fromsubstrate201 to showerhead240 reduces a source of deposition rate and thickness variation.
• Referring now to FIG. 14 which is a cross section of[0075]chamber200 and schematic portions ofvapor delivery system500, specific aspects of the temperature controlled conduits feature ofchamber200 of the present invention can more fully appreciated. Also shown is one feature of the vapor delivery system of the present invention illustrating the continuous, independent temperature controlled conduits which couple the outlet ofvaporizer520 withprocessing region202. Given the low vapor pressure of the Tantalum precursor, another feature of the vapor delivery system is the shortened vapor flow path fromvaporizer520 toprocessing region202. By shortening the precursor vapor flow path, pumping losses, friction losses and other fluid dynamic inefficiencies associated with the length of the pumping conduit as well as the inherent difficulties of pumping low vapor pressure gases can be reduced. The reduction of the above fluid losses is beneficial to the effective vaporization and delivery of low vapor pressure precursors according to the present invention. As a result of minimizing the precursor flow path, the vapor delivery system of the present invention is able to attain more stable and repeatable vapor flow rates for low vapor pressure precursors.
• Inlet and mixing[0076]block272, mixed deposition gas feed throughblock266 andcentral mixing block262 , collectively referred to as heated gas feed through220, are formed from rigid materials such as aluminum, varieties of nickel alloys or other materials having good thermal conductivity. The various conduits formed within heated gas feed throughassembly220 couple the outlets of heated chamber feed through225 and process gas feed through227 and lid borethroughs226 and228 to central chamber bore through230.
• Inlet and mixing[0077]block272 attaches tolid205 forming a sealed, continuous flow path between precursor lid bore-through226 andprecursor inlet conduit265 and between process gas lid bore-through228 and processgas inlet conduit276. Typically o-rings formed of Chemraz ® or Kalrez ® are used at lid bore-throughoutlets226 and228 to provide a seal at the mating surfaces betweenlid205 and inlet and mixingblock272. Mixingmanifold278 merges the process gas and precursor vapor flows into a single gas flow and begins the process of mixing precursor and process gas or gases into a homogeneous mixture for delivery intoprocessing region202. The length of conduit from the point within mixingmanifold278 where the precursor vapor stream and the process gas stream mix is sufficiently long such that the resulting mixed gas stream is homogeneously mixed upon arrival inprocessing region202. Although specific lengths to achieve homogeneous mixing will vary depending on a variety of factors such as the diameter of the conduit and gas flow rates and temperatures, a representative length from mixingmanifold278 toprocessing region202 would be about 12 inches for a 0.5 inch inner diameter mixeddeposition gas conduit273,central conduit231 and bore through230 of FIG. 14. In an alternative example, the length of conduit which could also result in homogeneous mixing of precursor vapor and process gases from mixingmanifold278 through mixeddeposition gas conduit273 andcentral conduit231, both having inner diameters of 0.5 inches, is about 10 inches.
• Inlet and mixing[0078]block272 attaches to mixed deposition gas feed-throughblock266 such that the outlet of mixingmanifold278 is coupled to mixeddeposition gas conduit273 formed within mixed deposition feed-throughblock266. Typically the mating surface surrounding the conduit outlet ofconduit278 and the inlet of mixeddeposition gas conduit273 is similarly sealed with an o-ring formed of Kalrez ® or Chemraz®. Mixed deposition gas feed-throughblock266 attaches to mixing block262 and similarly forms an o-ring sealed conduit between mixeddeposition gas conduit273 and central gas feed-throughconduit231. Mixingblock262 is attached toheated lid205 forming an o-ring sealed conduit between central gas feed-throughconduit231 and central lid bore-through230. In order to more clearly describe the unique temperature controlled conduits feature ofchamber220 of the present invention,inlet mixing block272 and mixed deposition gas feed throughblock266 are described and discussed as separate pieces. However, one of ordinary skill in the art will appreciate that a single workpiece could be utilized having the described dimensions and characteristics of bothinlet mixing block272 and mixed gas feed through266 without departing from the scope of the present invention.
• The temperature of each of the conduits formed internal to heated manifold[0079]220 (265,276,278,273 and231) are controlled by a plurality ofindependent heaters264,thermocouple274 andcontroller277 units. One unit controls the temperature ofconduits265,276 and278 within inlet and mixingblock272; another controls the temperature ofconduit273 within feed throughblock266; and another controls the temperature ofconduit231 withincentral block262. In each block, a plurality of cartridge or fire-rod type heaters264 are advantageously arranged integral to the given block in proximity to the conduit or conduits within a given block. Multiple heaters provide the most efficient heating of the particular conduit or conduits within a given block as the heaters can be located based upon the size, shape, composition and thermal conductivity of the particular block as well as the particular geometry of the conduits. For the representative system illustrated in FIG. 14,cartridge heaters264 are about 0.25 inches in diameter, cylindrical in shape, have various lengths, output power capacities and are available commercially from Watlow Inc. of Richmond,111. under the brand name “Firerod”.
• The set-point temperature is maintained within a given conduit by inputting a desired temperature set-point into the[0080]controller277 for the particular conduit.Controller277 could be a PID type controller similar to Model 965 which is also commercially available from Watlow, Inc.Thermocouples274 are embedded within gas feed throughassembly220 in proximity to each conduit such that the temperature registered by eachthermocouple274 is approximately the same as the temperature within the gas conduit by which the thermocouple is installed. The position ofthermocouple274 relative to a given gas conduit varies depending upon a number of factors such as the thermal conductivity of the material used to fabricate the given block and the type ofthermocouple274 used. The signal fromthermocouple274 is sent tocontroller277 which compares the temperature fromthermocouple274 to the input temperature set-point. Based on the result of comparing the temperature fromthermocouple274 to the input temperature set-point,controller277 will either increase, decrease or maintain power supplied tocartridge heaters264. One advantage of utilizing a plurality ofindependent thermocouples274 is that the specific conditions of a given conduit block are taken into account depending upon its location relative to other heat sources such asheated lid205, heat loses and geometry.
• For example, inlet and mixing feed through[0081]block272 is in direct contact withheated lid205 and, unless the temperatures between them exactly match, will either gain energy from or lose energy tolid205. The effect of heat transfer betweenlid205 and mixing feed throughblock272 on the temperature ofconduits265,276 and278 withinblock272 will be reflected in the temperature detected by athermocouple274 located withinblock272. As a result, thecontroller277 associated withblock272 can increase or decrease the power output ofheaters264 embedded withinblock272 in proximity toconduits265,276 and278 to compensate for heat transfer betweenblock272 andlid205. In much the same way, energy transfer between mixingblock262 andlid205 is compensated for by the thermocouple, heater, controller unit associated withblock262. Similarly, heat losses of mixed deposition gas feed throughblock266 which are different from heat transfer ofblocks272 and262 since it has a higher potential for heat loss because it is not in direct contact withheated lid205 and has a larger surface area exposed to the ambient conditions (about 70 degrees Fahrenheit) within the wafer fabrication facility whenprotective cover203 is removed. However, whenprotective cover203 is in place as illustrated in FIG. 2,temperatures surrounding manifold220 are increased to about 70 to 80 degrees Celsius. Thus, the heater, thermocouple, controller unit dedicated to mixed deposition gas feed-throughblock266 is utilized to compensate for the particular heat transfer characteristics of that block.
• More generally, an aspect of the present invention is a method to provide a predetermined temperature set-point within a conduit by the selection, placement and use of a controller, heater and thermocouple control unit which utilizes the method and apparatus described above. Another feature of the multiple, independent cartridge heater, thermocouple and controller units of the present invention is that a uniform conduit temperature throughout[0082]heated gas manifold220 can be achieved. Because of their independence, each controller is able to efficiently maintain set points irrespective of conditions in surrounding blocks while taking into account the specific heat losses and conditions surrounding each block, the specific outer shapes of each block and the geometry of the conduits formed within each block. In another aspect of the present invention, the temperature set point of each conduit could be set and maintained to induce a negative temperature gradient where the temperature ofblock262 is less thanblock266 which is less than the temperature ofblock272. Alternatively, a positive temperature gradient could be induced where the temperature inblock272 is less than the temperature inblock266 which is also less than the temperature ofblock262.
• In a specific embodiment of the apparatus of[0083]chamber200 of the present invention, mixed deposition and feed-throughblock266 is an aluminum rectangle with the following dimensions: about 5 inches long, about 1.5 inches wide and about 0.75 inches high. For the aluminum mixed deposition feed throughblock266 described above, arepresentative cartridge heater264 could be cylindrically shaped, 0.25 inches in diameter, 5.5 inches long with a power output capacity of 500 Watts. In an embodiment of the method and apparatus of the present invention, asingle cartridge heater264 or a plurality ofheaters264 of a selected power output capacity of about 500 Watts could be employed within mixed deposition feed throughblock266 such that the temperature within mixeddeposition gas conduit273 remains above the vaporization temperature and below the decomposition temperature of the carrier gas/precursor vapor/process gas mixture flowing withinconduit273. In a specific embodiment where mixed deposition gas feed throughblock266 is as described above, athermocouple274 could be placed between about 0.125 inches to 0.5 inches away from mixeddeposition gas conduit273. In an embodiment of the present invention where the carrier gas/precursor vapor/process gas mixture withinconduit273 is comprised of a Tantalum precursor such as TAT-DMAE, a process gas such as oxygen, and a carrier gas such as nitrogen,conduit273 temperatures between about 130° C. and 160° C. would prevent both condensation and decomposition of the tantalum/oxygen/nitrogen mixture. Thus, using the TAT-DMAE example above, a typical set-point temperature could be about 150° C. or between about 130° C. and 160° C. Representative set-points for an embodiment of the present invention employing TAETO could be about 170° C. or between about 150° C. and 180° C.
• A further aspect of the temperature controlled conduits of[0084]chamber200 of the present invention provides temperature controlled delivery of vaporized precursor fromvaporizer520 to lid bore through230. Vaporized precursor exitsvaporizer520 viavaporizer outlet540 and entersvaporizer outlet line542 which is coupled toprecursor inlet544 of chamber by-pass valve545. When three-way valve545 is aligned to chamber, precursor vapor exits threeway valve545 viachamber outlet550 flowing then to precursorchamber supply line560 which is coupled to precursor feed through225. A jacket type temperature controlledconduit292 is created between the outlet ofvaporizer520 and the inlet to precursor feed through225 and encompassesconduits542 and560 and threeway valve545. A jacket type control unit comprises a jacket or wrapstyle heater275, acontroller277 and athermocouple274 is utilized to maintain a temperature set-point in theabove components542,560 and545. From temperature controlled precursor feed through225, precursor vapor flows through lid bore through226 intoprecursor inlet conduit265 of inlet and mixingblock272. Fromprecursor inlet265, the precursor vapor flows into mixingmanifold278 where it mixes with process and ballast gases supplied viaprocess inlet conduit276.
• The temperature of precursor vapor within[0085]conduit225 is maintained by the temperature controlled chamber feed through219 which includes a plurality ofcartridge type heaters264, athermocouple274 and acontroller277. Another feature of temperature controlled precursor feed through219 is thermal choke orair gap212 which insulates thermal influences ofchamber body210 from the components of temperature controlled precursor feed through219. Thus, by utilizing the plurality of heater, controllers and thermocouples described above and the features ofheated lid205,chamber200 andliquid delivery system500 provide a temperature controlled flow path for vaporized low vapor pressure precursors from origin invaporizer520 to use inprocessing region202.
• Process[0086]gas heat exchanger582 provides temperature control to process gas and ballast gases for use inchamber200. Processgas heat exchanger582 is located proximate tochamber body210 and, more specifically, to process gas chamber feed through227 such that the gas temperature exitingheat exchanger582 is approximately the same as the gas temperature entering feed through227. From process gas feed through227, temperature controlled process and ballast gases pass through lid bore through228 and enterprocess gas inlet276 of inlet and mixingblock272.
• Another aspect of the present invention is the use of process[0087]gas heat exchanger582 to heat process and ballast gases above the temperature of the vaporized precursor gas stream. As a result, when the heated process gas stream and the vaporized precursor gas stream intersect and mix within mixingconduit278 the risk of condensation of the vaporized precursor is virtually eliminated. For example, the temperature set-point of process gas heat exchanger could be about 5-10° C. above the temperature set-point ofvaporizer520. In much the same way, the temperature of process gas and ballast gas can be controlled to remain below a set-point where, upon mixing with the precursor vapor stream, decomposition of the precursor occurs. Alternatively, a set-point could be utilized which results in process gas temperatures at least as high as the merging precursor gas stream.
• Utilizing the above described independent thermocouple, controller, heater sets which are part of[0088]processing system200 andvapor delivery system500, a series of temperature controlled conduits is provided which can deliver vaporized low vapor pressure precursors from the outlet ofvaporizer520 toprocessing region202. Although temperature controlled conduits based on heater type are described—cartridge heater temperature controlledconduits293 and jacket or wrap style heater type temperature controlledconduits275—their description is not intended to be limiting as one of ordinary skill in the art will appreciate that a variety of heater types, thermocouples and controllers could be utilized without departing from the scope of the present invention. The independent temperature controlled conduits feature of the present invention provides more precise means of temperature control than previously available but also allows for vaporized liquid delivery under a variety of thermal conditions which exist as a result of the environment to which each conduit is exposed. For example, each temperature controlled conduit could be set to maintain a set-point 2-3° C. hotter than the previous conduit so that a slightly positive thermal gradient is maintained between thevaporizer520 and outlet ofcentral conduit231 intoprocessing region202 or, more generally, an overall ΔT could be maintained between the vaporizer outlet temperature and the temperature incentral conduit231 or a ΔT of about 20-25° C.
• Another aspect of the thermally controlled conduits of[0089]processing chamber200 andvapor delivery system500 of the present invention is that the conduits used downstream ofvaporizer520 in the precursor flow path, as shown in FIG. 14 betweenvaporizer520 and central lid bore through205, have progressively larger diameters which result in increasing cross-sectional flow areas resulting in an expanded gas flow volume within these conduits. The volume expansion and corresponding pressure drop within the precursor delivery conduits further help maintain conduit conditions which neither condense nor decompose the vaporized precursor. Another aspect of the independent temperature controlled conduits ofchamber200 is that temperature changes within a specific conduit associated with the volume expansion can be compensated for by the independent heater, controller and thermocouple of that particular conduit. For example, representative inner diameters for the chamber illustrated in FIG. 14, are avaporizer outlet542 with an inner diameter of 0.18 inches, aprecursor supply line560, chamber feed through225 andinlet265 with inner diameters of 0.40 inches and a mixeddeposition gas conduit278 andcentral conduit231 with inner diameters of about 0.5 inches. Another aspect of the present invention is that the cross sectional area of downstream of the intersection of the precursor gas flow and the process gas flow is larger than the sum of the merging gas flows. This relationship ensures that the downstream volume is larger thereby providing the increasing flow volume/decreasing precursor pressure feature discussed above. Additionally, the diameter of mixeddeposition precursor conduit273 is also greater than eitherprecursor inlet265 orprocess gas inlet276.
• The increased volume and correspondingly decreased pressure achieved by advantageously selecting the diameter of conduits downstream of[0090]vaporizer520 such as542,560,225,226,265,278,273 and231 in conjunction with the temperature control provided by the thermocouple, heater and controller sets described above provide a controlled temperature and pressure regime betweenvaporizer520 andprocessing region202 such that very low vapor pressure precursors, such as and including Tantalum precursors like TAETO, TAT-DMAE or other similarly low vapor pressure precursors, dopants or other processing materials may be delivered toprocessing area202 without undesired condensation or decomposition.
• The Remote Plasma Generator[0091]
• Another aspect of the[0092]processing apparatus100 of the present invention isremote plasma apparatus400 shown FIG. 15 in relation to centralsubstrate transfer chamber110 andchamber200 and components ofheated exhaust system300.Remote plasma apparatus400 creates a plasma outside of or remote toprocessing region202 for cleaning, deposition, annealing or other processes withinprocessing region202. One advantage of aremote plasma generator400 is that the generated plasma or activated species created byremote plasma generator400 may be used for cleaning or process applications within the processing region without subjecting internal chamber components such assubstrate support250 orshower head240 to plasma attack which usually results when conventional RF energy is applied withinprocess region202 to create a plasma. Several components ofremote plasma apparatus400 are visible in FIG. 15 such asmagnetron402,auto tuner controller410,isolator404,auto tuner408,adapter tube418 and adapter tubeheat insulation disc424.
• Turning now to FIG. 16 which is a schematic illustration of[0093]Remote Plasma System400, the components and operation ofremote plasma apparatus400 can be better appreciated.Magnetron assembly402 houses the magnetron tube, which produces the microwave energy. The magnetron tube consists of a hot filament cylindrical cathode surrounded by an anode with a vane array. This anode/cathode assembly produces a strong magnetic field when it is supplied with DC power from a power supply. Electrons coming into contact with this magnetic field follow a circular path as they travel between the anode and the cathode. This circular motion induces voltage resonance, or microwaves, between the anode vanes. An antenna channels the microwaves frommagnetron402 toisolator404 andwave guide406.Isolator404 absorbs and dissipates reflected power to prevent damage tomagnetron402.Wave guide406 channels microwaves fromisolator404 intoauto tuner408.
• [0094]Auto tuner408 matches the impedance ofmagnetron402 andmicrowave cavity416 to achieve the maximum degree of reflected power by adjusting the vertical position of three tuning stubs located insidewave guide406.Auto tuner408 also supplies a feedback signal to the magnetron power supply in order to continuously match the actual forward power to the setpoint.Auto tuner controller410 controls the position of the tuning stubs withinwave guide406 to minimize reflected power.Auto tuner controller410 also displays the position of the stubs as well as forward and reflected power readings.
• [0095]Microwave applicator cavity416 is where gas or gases supplied viagas supply inlet412 are ionized. Gas supplied viagas supply inlet412 enters a water cooled quartz or sapphire tube withinmicrowave applicator416, is subjected to microwaves and ionizes producing activated species which can then be used in cleaning and processing operations withinprocessing region202. One such cleaning gas is NF3 which can be used to supply activated fluorine for cleaningprocessing region202 when asubstrate201 is not present inprocessing region202. Activated species can also be used to anneal or otherwise process semiconductor or other materials present on asubstrate201 positioned withinprocessing region202. Anoptical plasma sensor414 detects the existence of plasma withincavity416. Activated species generated withinmicrowave applicator cavity416 are supplied to activated species chamber feed through229 viaadapter tube418.Adapter tube418 is insulated from the elevated temperature ofchamber body210 by adaptertube isolation disc424.
• From activated species chamber feed through[0096]229, the activated species pass through lid bore-through221 and enter activatedspecies inlet block420 which, together with activated species block270, provide an o-ring sealed, air tight conduit i.e., activatedspecies conduit271, between lid bore-through221 and central gas feed-through231 withincentral mixing block262.
• Heated Exhaust System[0097]
• Referring again to FIG. 15, the components and features of[0098]heated exhaust system300 ofprocessing system100 can be better appreciated. The components ofheated exhaust system300 are collectively referred to as a foreline are in communication with a vacuum pump355 (not shown) and wafer fabrication facility exhaust systems340 (not shown) to provide for reduced pressure processing operations withinprocessing region202. Exhaust from processing and cleaning operations conducted withinprocessing region202 are exhausted viachamber exhaust port305. When closed,isolation valve310 shuts offchamber assembly200 from down stream vacuum pump systems. During normal operation,isolation valve310 is open andthrottle valve315 opens and closes to regulate pressure withinprocessing region202. By-pass inlet320 receives precursor vapor/carrier gas mixture from chamber by-pass valve outlet555 when chamber by-pass valve545 is positioned to flow precursor vapor/carrier gas mixture to temperature controlled by-pass line322 . Exhaust systemcomponents exhaust port305,isolation valve310,throttle valve315 and by-pass320 and by-pass line322 are temperature controlled to prevent unreacted precursor condensation.Cold trap325 and remaining downstream exhaust system components are maintained at or below 75 degrees Fahrenheit. As a result, any unreacted vapor remaining in the exhaust stream from processingregion202 or vapor from chamber by-pass valve545 will remain gaseous in the temperature controlled or heated portion ofexhaust system300 and then condense withincold trap325 thus preventing damage to the vacuum pumps or accumulation and resulting line blockages within exhaust system piping. Additionally, collection of unreacted vapor withincold trap325 also minimizes the exposure of maintenance personnel to potentially hazardous chemicals.Cold trap325 is equipped with anisolation valve330 for separatingcold trap325 from vacuum pumping systems to allow for routine maintenance or cleaning.
• In order not to unnecessarily obstruct a clear illustration of the relationships between the various components of[0099]exhaust system300 and the other components ofprocessing system100, the independent thermocouple, controller,heater275 utilized as part of the temperature controlled feature ofexhaust system300 is not shown in FIG. 15. Turning briefly to FIG. 18 which is a representative schematic embodiment ofprocessing system100 of the present invention, the temperature controlled conduits feature ofexhaust system300 can be better appreciated. A jacket style heater, thermocouple andcontroller275 could be utilized to measure and maintain a set point temperature inexhaust port305,isolation valve310,throttle valve315 andchamber bypass line320 thereby creating a jacket heater controlledconduit292 in the exhaust components upstream ofcold trap325. A separate thermocouple, controller andheater275 operates on by-pass line322 between chamber by-pass545 and exhaust by-pass320. As a result, chamber by-pass line322 becomes a jacket style heater temperature controlledconduit292 between chamber by-pass545 and exhaust by-pass320.
• Vapor Delivery System[0100]
• Turning now to FIG. 17, the compact design feature of[0101]vapor delivery system500 of the present invention can be better appreciated.Vapor delivery system500 provides a method and an apparatus for supplying controlled, repeatable, vaporization of low vapor pressure precursors for film deposition on asubstrate201 located withinprocessing region202. One method provides for the direct injection of vaporized TAETO and TAT-DMAE. One of ordinary skill will appreciate the specific features detailed below which separately and when combined allowvapor delivery system500 to vaporize and precisely control the delivery of liquid precursors including those precursors having vapor pressures significantly lower than precursors utilized in prior art vapor delivery systems or, specifically, precursors having vapor pressures below about 10 Torr at1 latm and 100° C. (FIG. 1).
• The various components of[0102]vapor delivery system500 are placed in close proximity tochamber200 in order to minimize the length of temperature controlled vapor passageways between the outlet ofvaporizer520 andprocessing region202. Even though practice in the semiconductor processing arts is to place vapor systems remotely from processing chambers to either ensure serviceability or reduce the amount of cleanroom space occupied by a processing system,vapor delivery system500 of the present invention utilizes an innovative compact design which allows all system components—less bulk liquid precursor, carrier gas and process gas supplies—to be located directly adjacent tochamber200 in close proximity to precursor and process gaschamber feed throughs225 and227.
• A low vapor pressure liquid precursor, such as TAT-DMAE or TAETO, can be stored in[0103]bulk storage container503 located remotely or onmainframe support105 in proximity to processingchamber200. Liquid precursor stored intank503 is maintained under pressure of an inert gas such as Helium at about 15 to 60 psig. The gas pressure withintank503 provides sufficient pressure on the liquid precursor such that liquid precursor flows to other vapor delivery system components thus removing the need for a pump to deliver the liquid precursor. The outlet ofdelivery tank503 is provided with a shut-off valve507 (not shown) to isolatebulk tank503 for maintenance or replenishment of the liquid precursor. As a result of the pressure head ontank503, liquid precursor fromtank503 is provided toliquid supply line508 and theprecursor inlet509 of precursor/solvent inlet valve588. When aligned for liquid precursor, precursor/solvent valve588 provides liquid precursor to precursor/solvent outlet594 and into precursor/solvent supply line592 to liquidflow meter inlet505.Liquid flow meter510 measures precursor flow rate and provides via liquidflow meter outlet511 liquid precursor tovaporizer supply line513 and then tovaporizer inlet515.Vaporizer520 in conjunction with a heated carrier gas (described below) converts the liquid precursor into precursor vapor.
• A carrier gas, such as nitrogen or helium, is supplied into carrier gas[0104]heat exchanger inlet525 at a pressure of about 15 psi. Carriergas heat exchanger530 is a gas to resistive heater type heat exchanger like Model HX-01 commercially available from Lintec. Carriergas heat exchanger530 preheats the carrier gas to a temperature such that the heated carrier gasstream entering vaporizer520 does not interfere with the efficient vaporization of the precursor liquid undergoing vaporization withinvaporizer520. Heated carrier gas is provided tovaporizer520 via carriergas supply line532 and carrier gas inlet tovaporizer535. The heated carrier gas should not be heated uncontrollably since a carrier gas heated above the decomposition temperature of the precursor undergoing vaporization could result in precursor decomposition withinvaporizer520. Thus, carriergas heat exchanger530 should heat the carrier gas into a temperature range bounded by, at the lower limit, the condensation temperature of the precursor and, at the upper limit, the decomposition temperature of the precursor. For a tantalum precursor such as TAT-DMAE for example, a representative vaporization temperature is about 130° C. and a decomposition temperature is about 190° C. A typical carrier gas such as nitrogen could be provided to avaporizer520, which is vaporizing a tantalum precursor such as TAT-DMAE, at about between 200 and 2000 standard cubic centimeters per minute (sccm) and a temperature of about between 130° C. and 160° C. These conditions result in a vaporized precursor flow rate in the range of about 10-50 milligrams per minute. Carrier gas temperature can also be such that the temperature of the carriergas entering vaporizer520 is at least as high if not higher than the vaporization temperature of the precursor being vaporized invaporizer520. Of particular concern is the prevention of precursor vapor condensation within the small diameter conduits which exist withinvaporizer520. As such, carrier gas temperatures below vaporization conditions withinvaporizer520 could sufficiently cool the vaporized precursor, result in condensation and should therefore be avoided.
• Referring now to FIG. 18, which schematically represents the operation of[0105]liquid flow meter510 in conjunction withvaporizer520, which are referred to collectively as liquidmass flow controller528. Liquid precursor entersliquid flow meter510 which generates measuredflow rate signal512. A typical flow rate signal is measured in milligrams per minute or mg/min. A representative flow rate for a TAT-DMAE precursor is 35 mg/min. for a representative Ta₂O₅film produced utilizing the method and apparatus of the present invention. The now measured precursor flow exits liquidflow meter outlet511 intovaporizer supply line513 and then intovaporizer inlet515.Vaporizer supply line513 is typically 0.125 inch outer diameter stainless steel piping. Another aspect of liquidmass flow meter528 is that the length ofvaporizer supply line513 is minimized to attain controllable low vapor pressure precursor output fromvaporizer520. Minimizing the distance betweenliquid flow meter510 andvaporizer520 adds to the number ofvapor delivery system500 components placed in proximity toprocessing system100 as well as increases the density of equipment mounted onmainframe105. However,vapor delivery system500, along with theremote plasma system400 andheated exhaust system300 have been designed to minimize interference between the subsystems ofprocessing system100 while achieving the compact design desired in cluster tool wafer processing systems. Although remote placement ofliquid flow meter510 further away fromvaporizer520 would reduce the amount of vapor delivery components in proximity toprocessing system100, more effective liquid metering and control is achieved by minimizing the distance between the liquidflow meter outlet511 andvaporizer inlet515.Vaporizer inlet515 to liquidflow meter outlet511 spacing of about 6 inches or between about 4 inches and 15 inches leads to more effective metering and controlled vaporization of low vapor pressure precursors such as TAETO, TAT-DMAE or other liquid precursors having a vapor pressure of below about 10 Torr at 100° C. and 1 atm.
• Another feature of a the liquid[0106]mass flow controller528 of the present invention is positive shut-offvalve522. Located withinvaporizer520 betweenvaporizer inlet515 andmetering valve524, positive shut-offvalve522 provides the capability to cut-off liquid flow before the vaporization point withinvaporizer520.Metering valve524 can provide a shut-off capability when in a ‘closed’ or zero set-point condition. However, positive shut-offvalve522 provides added assurance that no liquid will continue to flow throughvaporizer520 when liquidmass flow controller528 is in a ‘closed’ or zero set-point condition. The position of positive shut-offvalve522 relative tometering valve524 is such that there is a minimal volume of liquid which could remain in the line between shut-offvalve522 andmetering valve524. Arepresentative vaporizer520 suitable for vaporization of low vapor pressure liquids could position positive shut-offvalve522 about one inch or less frommetering valve524. Thus, utilizing a 0.125 inch diameter line between shut-offvalve522 and metering valve524 a minimal liquid volume of about 0.012 cubic inches of precursor is created. By reducing the volume between these components the amount of precursor which could vaporize after positive shut-offvalve522 is closed is minimized. Thus, positive shut-offvalve522 provides redundancy to the shut-off capabilities ofmetering valve524 as well as provides a minimal volume of liquid which could still be vaporized even if liquidmass flow controller528 is in a open or 100% flow set-point condition and positive shut-offvalve522 is closed.
• Referring now to FIG. 17, vaporized precursor flows from[0107]vaporizer outlet540 intovaporizer outlet line542 intovapor inlet544 of temperature controlled by-pass valve545. When aligned to “chamber” position, by-pass valve545 supplies vapor tochamber outlet550 and then into temperature controlled vaporizedprecursor supply line560. A feature of thevapor delivery system500, but omitted for clarity, is the thermocouple, controller, jacketstyle heater system275 which maintains a temperature set-point withinvaporizer outlet line542, chamber by-pass valve545 and vaporizedprecursor supply line560. The internal piping of chamber by-pass valve545 allows vaporized precursor/heated carrier gas mixture to be sent toprocessing region202 via outlet tochamber550.
• Additionally or alternatively, while stabilizing vapor flow or conducting cleaning operations within[0108]processing region202, chamber by-pass valve545 could direct the vaporized precursor/heated carrier gas mixture to heated by-pass line320 of heated exhaust system300 (described above) via outlet to by-pass555. One advantage of chamber by-pass valve545 of the present invention is that once liquidmass flow controller528 attains a desired set-point vapor flow rate the vaporized precursor/heated carrier gas mixture can either be directed to the chamber for deposition or to the foreline by-pass inlet320 for disposal. Independent of operations withinprocessing region202, liquidmass flow controller528 continues to produce a stable, consistent vapor flow rate. Thus, chamber by-pass valve545 used in conjunction with liquidmass flow controller528 provides the repeatable, stable vapor flow rates toconsecutive substrates201 withinprocessing region202. Such repeatable, stable vapor flow rates are necessary for the deposition of transition metal dielectric materials such as tantalum oxide for use in high capacity ICs such as stacked capacitors.
• [0109]Vaporizer outlet line542 andprecursor supply line560 are standard piping which could be made of stainless steel. Vaporizedprecursor supply line560 should be as short as possible to minimize the length of travel of vaporized precursor within the system or between about 4 to 6 inches.Precursor supply line560 is in communication withchamber outlet550 and precursor chamber heated feed-through225. In order to prevent condensation of the vaporized precursor within the vaporized precursor/heated carrier gas mixture, heatedprecursor supply line560 andvaporizer outlet line544, like all precursor supply conduits downstream ofvaporizer520, have an inner diameter which is greater than the inner diameter of the liquid supply line intovaporizer520. Typically, the vaporizer liquid supply line is made of stainless steel with about a 0.125 inch inner diameter while the conduits downstream ofvaporizer520 could have a larger diameter or an outer diameter of about 0.5 inches or an inside diameter of about 0.4 inches. Larger diameter conduits downstream ofvaporizer520 exposes the vaporized precursor/heated carrier gas mixture to an expansion volume and corresponding reduction in pressure which helps maintain the vaporized low vapor pressure precursor within an operational temperature region above the precursor condensation temperature and below its decomposition temperature for the conditions within the vapor supply conduits. Since vaporizedprecursor supply line560 andvaporizer outlet542 are heated by a thermocouple, controller,jacket style heater275, temperatures within vaporizedprecursor supply line560 andvaporizer outlet542 are maintained above the condensation temperature and below the decomposition temperature of the vaporized precursor or between about 100° C. and 190° C.
• [0110]Vapor delivery system500 also has a temperature controlled process gas feature. Processgas heat exchanger582 which is similar to carriergas heat exchanger530 described above receives process gas fromprocess gas supply580. Suitable process gases depend on the desired film deposition. Typically, oxygen (O₂) and nitrous oxide (N₂O) are suitable for oxidation processes and ammonia (NH₄) is suitable for nitride processes. Additionally, nitrogen (N₂) could be added to the process gas flow as a ballast gas. The term process gas stream used below refers to all gas flows out ofheat exchanger582 and is intended to include process gas, ballast gases or other gases described below. Process gases and ballast gases can be preheated by processgas heat exchanger582 so that the resulting process gas stream is maintained above the temperature of the adjacent vaporized precursor gas stream. Maintaining the process gas stream temperature above about 10°-15° C. above the temperature of the vaporized precursor gas stream assists in the prevention of inadvertent condensation of the precursor vapor when the gas streams intersect and begin to mix within mixingconduit278. Similarly,heat exchanger582 can also ensure process gas stream temperatures are maintained below the decomposition temperature of the precursor gas stream so that inadvertent decomposition of the precursor vapor stream does not occur when the gas streams mix within mixingconduit278.
• Thus, a temperature controlled gas stream exits process[0111]gas heat exchanger582 viaoutlet584 and enters processgas supply line586. From processgas supply line586 the process gas stream flows through process gas chamber feed-through227 which in flows into heated processgas inlet conduit276. Processgas inlet conduit276 flows into and mixes with vaporized precursor flow stream inheated mixing manifold278. Processgas heat exchanger582 heats the process gas to a sufficient temperature such that when the process gas mixes with the vaporized precursor in mixingconduit278 the precursor vapor neither decomposes nor condenses.
• Another feature of[0112]vapor delivery system500 is the ability to provide a solvent flush capability to those conduits which come into contact with the vaporized low vapor pressure precursors. Such solvent operations further the operability of the method and apparatus of the present invention to vaporize low vapor pressure liquids such as TAETO and TAT-DMAE. A solvent such as anhydrous isopropyl alcohol, methanol, hexane, ethanol, or other suitable solvent is supplied into precursor/solvent three-way valve588 viasolvent inlet590. From bulksolvent supply591 solvent is introduced into thevapor delivery system500, via 3-way valve588 and follows the same flow path as a vaporized precursor through the various components ofvapor delivery system500 and, depending upon chamber by-pass valve545 alignment, tochamber200 orexhaust system300 via by-pass line322. As the solvent flows through the various conduits which are exposed to liquid precursor such as the conduits of and within liquidmass flow controller528, the solvent mixes with precursor liquid and purges the line of residual precursor which then allows exposure of the components to air for maintenance or component change. Without the solvent flush capability and as a result of the low vapor pressure of typical precursors vaporized using the methods and apparatus of the present invention, residual precursor vapors within conduits exposed to the low vapor pressure precursor would not be sufficiently evacuated nor achieve reduced pressures in a timely—commercially viable—manner simply utilizing only pumping systems355 ofexhaust system300. Additionally, the solvent flush feature can be utilized to remove precursor vapor from process conduits and components to prevent risk of exposure to potentially hazardous materials during maintenance as well as prevent the undesired reaction of precursor vapor with air, water vapor or other materials.
• CVD Deposition System Operation[0113]
• Referring now to FIGS. 19 and 20, an integrated method of operating[0114]CVD deposition system100 and the use and interoperability of dopant, second dielectric or second precursor materials within the various embodiments of the present invention can be better understood. FIG. 19 schematically represents a system configuration when a single vaporizer and process heat exchanger are utilized to provide process gas/precursor vapor mixtures to temperature controlledconduits292 and293 andprocessing region202. FIG. 20 is similar to FIG. 19 with the addition of asecond vaporizer520,bulk supply504 and by-pass valve570. Under the representative configuration of FIG. 20,processing system100 of the present invention is further enabled to not only provide, mix, and deposit films from a single precursor (FIG. 19) but also, by modifying the liquid source contained inbulk supply204, films containing a second precursor, a dopant or a metal.
• [0115]Deposition system100 as embodied in FIG. 20 operates similarly to previous descriptions ofprocessing system100 with the addition of anadditional bulk supply504 which could be under a pressure head as withbulk supply tank503.Bulk supply504 is coupled to and supplies processing fluids to asecond vaporizer520 which operates similarly to thefirst vaporizer520 as embodied in FIG. 19 and described above. The vaporized precursor stream created by thesecond vaporizer520 is provided to a chamber by-pass valve570 which can align—viaoutlet571—the vaporized gas stream tochamber200 via processgas supply line586. Alternatively, by-pass valve570 can align the vaporized precursor stream toexhaust system300 viaoutlet572. In the embodiment of FIG. 20,bulk supply504 could contain a wide variety of fluid processing source materials such as dopants, precursor materials, metals, or other materials with a sufficiently high vapor pressure that vaporization may occur without a carrier gas, heated carrier gas or will remain vaporized without temperature controlled conduits described above in relation to the low vapor pressure precursor utilized and described above. Therefore, what is not shown, but an object of the present invention is modification of thesecond vaporizer520 and other components of FIG. 20 to include a carrier gas or heated carrier gas used in conjunction withsecond vaporizer520 and the use of the temperature control methods described above to provide temperature controlled conduits from the outlet of thesecond vaporizer520 to three-way valve570 and including processgas supply line586 in order that low vapor pressure precursors could also be provided to and effectively utilized bysecond vaporizer520 of FIG. 20.
• Another object of the[0116]vapor delivery system500 present invention is the deposition of a variety of films onsubstrates201 withinprocess area202 by advantageously selecting precursors bulk supplies504 and503, process gases, process gases or ballast gases forgas source580 and by selective positioning of by-pass valves570 and545. One advantage of the 2 vaporizer—2 by-pass configuration of FIG. 20 is that each vaporizer may be in operation and producing stable, repeatable flow which, by aligning the appropriate by-pass570 or545, could easily be ported to processregion202 orexhaust system300. Some of the possible combinations mentioned above are detailed in FIG. 21.
• Referring now to FIG. 21, several representative vapor combinations utilizing the configuration of FIG. 20 can be appreciated. FIG. 21 provides[0117]10 liquid alignment configurations which refer to the specific positions of chamber by-pass valves545 and570, the contents ofbulk sources503 and504,process gas source580 and the resultant vapor mixture delivered toprocessing area202. The Liquid Alignment Configurations listed in FIG. 21 can be categorized into three broad mixture groups: tantalum oxide mixtures, dielectric mixtures and electrode mixtures.
• Liquid Alignment Configurations 1-4 are directed towards tantalum containing mixtures. Since only a[0118]single bulk source503 andvaporizer520 is utilized,configuration 1 could be embodied by either FIG. 19 or on FIG. 20 where chamber by-pass valve570 is aligned to by-pass outlet572. Whether FIG. 19 or20 is used,bulk source503 contains a tantalum containing precursor such as TAT-DMAE or TAETO which is vaporized and provided to chamber by-pass545. Chamber by-pass545 is aligned to chamber oroutlet550 so the vaporized Tantalum flows through chamber by-pass outlet550. through temperature controlledconduits275,219 and293 into mixingmanifold278. At the same time,process gas supply580 provides an oxygen containing process gas togas heat exchanger582 which heats the gas to a setpoint and provides the gas to processgas supply line586. From processgas supply line586, the process gas flows throughconduit227 and temperature controlledconduit276 into mixingmanifold278 where the process gas and tantalum vapor flows converge, mix and form a homogenous mixture before arriving inprocessing region202. The vapor mixture described above is suitable for deposition of tantalum oxides. Inliquid alignment configurations 2, 3 and 4, the tantalum precursor is vaporized and the oxygen containing process gas is heated as described above. Additionally,bulk source504 contains and is utilized to provide material which is vaporized insecond vaporizer520. The vapor stream produced bysecond vaporizer520 is provided via chamber by-pass outlet tochamber571 to processgas supply line586.
• A heater, controller, thermocouple temperature control system, similar to that utilized with the vaporized precursor stream produced by the[0119]first vaporizer520, could also be utilized with the conduits which carry vaporized precursor stream provided bysecond vaporizer520 to processgas supply line586 in order to prevent inadvertent condensation or decomposition of the vaporized precursor gas stream. FIG. 20 embodies asecond bulk supply504 with a material which can produce a stable output fromsecond vaporizer520 without requiring a carrier gas, heated carrier gas or temperature controlled conduit for the successful use of the second vapor stream.
• In[0120]liquid alignment configuration 2,bulk source504 contains an aluminum precursor and chamber by-pass570 is aligned tooutlet571. One representative aluminum precursor is aluminum nitrate dissolved in etoxide, ethynol, acilic acids or other suitable solution. One of ordinary skill will appreciate that a wide variety of liquid aluminum precursors could be utilized in the aforementioned apparatus of the present invention. As a result of this configuration, the vaporized aluminum precursor flow will merge and mix with the oxygen containing process gas inprocess supply line586. The process gas/aluminum precursor mixture then flows throughconduit227 into temperature controlledconduits276 and then into mixingmanifold278 where the process gas/aluminum vapor stream mixes with tantalum vapor gas stream. Homogenous process gas/precursor mixtures can be obtained inprocessing area202 by advantageously selecting the position of mixing manifold orpoint278 relative toprocessing region202 so that sufficient mixing occurs between mixing manifold278 and asubstrate201 located withinprocessing area202. Similarly, a titanium containing bulk supply504 (Liquid Alignment Configuration 3) or a dopant containing bulk supply504 (Liquid Alignment Configuration 4) could be utilized resulting in vapor mixtures withinprocess region202 which form titanium doped tantalum oxide or, more generally, a doped tantalum oxide. One representative titanium precursor is titanium tetratusisoprepoxide, referred to as TiPT. Those of ordinary skill will appreciate that a wide variety of titanium precursors may be efficiently utilized inprocessing system100 via thevapor delivery system500 described above.
• [0121]Liquid Alignment Configurations 5, 6 and 7 are directed towards the use of the second bulk source to provide a dielectric material intoprocessing chamber200. In these three configurations, the firstbulk delivery source503 is not listed since even if thefirst vaporizer520 associated withbulk supply503 were in operation the vapor stream produced byfirst vaporizer520 is aligned via chamber by-pass outlet555 toexhaust system300.Liquid Alignment Configuration 5 utilizes abulk supply504 containing an aluminum liquid source which after vaporization is provided to processgas supply line586 via chamber by-pass outlet571 is open. The vaporized aluminum precursor then mixes with an oxygen containing process gas fromsupply580 which has been preheated byheat exchanger582. The process gas and aluminum vapor mix while flowing towardsprocessing region202 resulting in a homogenous mixture suitable for aluminum oxides deposition onsubstrates201 located withinprocessing region202. Similarly, a titanium containing source or, generally, a dielectric precursor material may be placed in bulk source504 (Liquid Alignment Configurations 6 and 7) which would then result, respectfully, in mixtures and deposition withinprocessing region202 of titanium oxides or dielectric oxides.
• [0122]Liquid Alignment Configurations 8, 9 and 10 provide configurations which result in a variety of nitrides or electrode materials inprocessing region202. InLiquid Alignment Configurations 8, 9, and 10, theprocess gas source580 contains nitrogen, for example ammonia (NH₃), andbulk source504 contains aluminum, titanium or other electrode material precursor. Utilizing thesecond vaporizer520 associated withbulk supply504, deposition mixtures which result in aluminum based compounds (configuration 8), titanium nitrides (configuration 9) and generally nitrides suitable for forming electrodes (configuration 10) are provided toprocessing region202.
• As a result of the numerous liquid alignment configurations enabled by the vapor delivery system embodied in FIG. 20, multiple film layers can be deposited on a substrate within[0123]processing region202 by advantageously selecting precursor materials for bulk supplies503 and504 and providing both oxygen and nitrogen containing gases viaprocess gas source580. For example, avapor delivery system500 having abulk source503 containing tantalum, abulk source504 containing aluminum and aprocess gas source580 containing both oxygen and nitrogen, with both the first andsecond vaporizers520 in operation can form films such as tantalum oxides (Liquid Alignment Configuration 1) aluminum doped tantalum oxides (Liquid Alignment Configuration 2), aluminum oxides (Liquid Alignment Configuration 5) and aluminum nitrides (Liquid Alignment Configuration 8) can be formed withinprocessing region202.
• In another representative example, a[0124]vapor delivery system500 which has abulk source503 containing tantalum, abulk source504 containing titanium and aprocess gas source580 containing both oxygen and nitrogen, with both the first andsecond vaporizers520 in operation can form films such as tantalum oxides (Liquid Alignment Configuration 1), titanium doped tantalum oxides (Liquid Alignment Configuration 3), titanium oxides (Liquid Alignment Configuration 6) and titanium nitrides (Liquid Alignment Configuration 9) can be formed withinprocessing region202.
• In another example, a[0125]vapor delivery system500 could have a bulkprocess gas supply580 containing nitrogen, oxygen and other processing gases and both chamber by-pass545 and580 are aligned such thatoutlets555 and572 are open and no vaporized precursor reachesprocessing region202. Such a configuration would allow only process gases intoprocessing region202 or, if the flow of all process gas were stopped, only activated species fromremote plasma system400 would be provided toprocessing region202. Utilizing this configuration enables a variety of thermal and activated processes to occur withinprocessing region202 such as thermal or activated anneals, oxidation as well as utilizing remotely activated species fromremote plasma system400 to cleanprocessing area202.
• While specific embodiments of the invention have been shown and described, further modifications and improvements will occur to those skilled in the art. It is desired that be understood, therefore, that the invention is not limited to the particular form shown and it is intended in the appended claims which follow to cover all modifications which do not depart from the spirit and scope of the invention.[0126]

Claims (45)

Thus, we claim,

1. An apparatus for dispersing gases within a processing chamber, said apparatus comprising:

(a) an upper surface having a circular opening coupled to a cylindrically shaped first conduit;

(b) a lower surface having a circular opening coupled to a cylindrically shaped second conduit; and

(c) a conically shaped coupling conduit in communication with said first and second conduits.

2. An apparatus according toclaim 1 wherein said conically shaped coupling region has diverging walls.

3. An apparatus according toclaim 1 wherein said conically shaped coupling region and said second cylindrically shaped conduit are axially symmetric to a common centerline.

4. An apparatus for distributing gases within a processing chamber, said apparatus comprising:

(a) an inlet comprising a first cylindrical region having a first diameter;

(b) an outlet comprising a second cylindrical region having a second diameter and walls having a first length; and

(c) a conical region in communication with said first and second cylindrical regions said conical region further comprising walls having a second length wherein said walls form an angle.

5. An apparatus according toclaim 4 wherein said second diameter is greater than said first diameter.

6. An apparatus according toclaim 4 wherein said angle formed within said conical region is between about 20 degrees and 90 degrees.

7. An apparatus according toclaim 4 wherein said first length is greater than said second length.

8. A method for absorbing radiation within a gas distribution plate said method comprising the steps of:

(a) placing a substrate in a processing apparatus having a gas distribution plate wherein said gas distribution plate includes a plurality of gas inlets having a first and second cylindrical region and a conical region;

(b) generating radiation from said substrate wherein said radiation is incident to said gas distribution plate; and

(c) absorbing a portion of said incident radiation in said conical region.

9. A method according toclaim 8 wherein a portion of said incident radiation is reflected off said conical region and absorbed in said first cylindrical region.

10. A method according toclaim 8 wherein a portion of said incident radiation is reflected off said conical region and absorbed in said second cylindrical region.

11. A method of flowing gas through a gas distribution plate, said method comprising the steps of:

(a) flowing a gas through a first cylindrical region having a first diameter;

(b) flowing said gas through a conical region;

(c) flowing said gas through a second cylindrical region having a second diameter;

12. The method according toclaim 11 wherein said second diameter is greater than said first diameter.

13. An apparatus for fabricating semiconductor devices said apparatus defining an evacuable chamber comprising:

(a) a substrate support having a heated formed therein;

(b) a lid having a heater formed therein;

(c) walls; and

(d) a gas distribution plate coupled to said lid.

14. An apparatus according toclaim 13 wherein said heater formed internal to said substrate support is a resistive heater.

15. An apparatus according toclaim 13 wherein said heater formed internal to said lid is a resistive heater.

16. An apparatus according toclaim 13 wherein said gas distribution plate coupled to said lid forms a gas box between said lid and said gas distribution plate.

17. An apparatus according toclaim 16 wherein said heater formed internal to said lid heats that portion of said lid adjacent to said gas box.

18. An apparatus for processing substrates, said apparatus comprising:

(a) a processing chamber said chamber having:

(i) a lid;

(ii) walls;

(iii) a heated substrate support; and

(b) a showerhead gas distribution plate, said showerhead gas distribution plate having a surface wherein said surface of said showerhead gas distribution plate faces said substrate support and wherein said showerhead gas distribution plate is coupled to said lid and said surface modified to increase the emissivity of the showerhead surface.

19. An apparatus according toclaim 18 wherein said showerhead surface facing said substrate support is anodized.

20. An apparatus according toclaim 18 wherein said showerhead surface facing said substrate support is coated with a ceramic.

21. An apparatus according toclaim 18 wherein said showerhead surface facing said substrate support is coated with an oxide.

22. An apparatus according toclaim 18 wherein said showerhead surface facing said substrate support is bead blasted.

23. An apparatus according toclaim 18 wherein said showerhead surface facing said substrate has an emissivity between about 0.5 and 0.9.

24. An apparatus according toclaim 18 wherein said gas distribution plate includes a plurality of gas inlets having a first cylindrical region forming an inlet, a second cylindrical region forming an outlet and a conical region coupling said inlet to said outlet.

25. An apparatus according toclaim 24 wherein the diameter of an outlet is large relative to the distance between adjacent outlets thereby minimizing the reflective surface between adjacent outlets.

26. An apparatus for vaporizing and delivering low vapor pressure precursors to a processing chamber, said apparatus comprising:

(a) a vaporizer,

(b) a first conduit,

(c) a second conduit,

(d) a third conduit; and

(e) a processing chamber,

wherein said first conduit is coupled to said vaporizer and said second conduit and said first conduit further includes a first thermocouple, a first controller and a first heater wherein said first thermocouple measures the temperature of said first conduit which is provided to said first controller which adjusts the output of said first heater to maintain said first conduit at a set-point temperature, and

wherein said second conduit is coupled to said first conduit and said third conduit and said second conduit further includes a second thermocouple, a second controller and a second heater wherein said second thermocouple measures the temperature of said second conduit which is provided to said second controller which adjusts the output of said second heater to maintain said second conduit at a set-point temperature, and

wherein said third conduit is coupled to said second conduit and said processing chamber and said third conduit further includes a third thermocouple, a third controller and a third heater wherein said third thermocouple measures the temperature of said third conduit which is provided to said third controller which adjusts the output of said third heater to maintain said third conduit at a set-point temperature.

27. An apparatus according toclaim 26 wherein the diameter of said first conduit is less than the diameter of said second conduit.

28. An apparatus according toclaim 26 wherein the diameter of said second conduit is less than the diameter of said third conduit.

29. An apparatus according toclaim 26 wherein at least one conduit and its associated heater and thermocouple are disposed internal to the same structure.

30. An apparatus for controlling the temperature of a conduit which delivers vaporized liquid to a processing chamber, said apparatus comprising:

(a) a conduit formed in a rigid thermally conductive medium wherein said conduit is in communication with a vaporizing means and a processing chamber;

(b) a heater disposed internal to said medium and thermally coupled to said conduit;

(c) a thermocouple disposed internal to said medium wherein said thermocouple is thermally coupled to said conduit and produces an output representing the temperature of said conduit; and

(d) a controller coupled to said thermocouple and said heater, wherein said controller processes said thermocouple output and adjusts said heater output to maintain said conduit at a set-point temperature.

31. A method of delivering vaporized low vapor pressure precursors to a processing chamber, said method comprising the steps of:

(a) forming a vaporized precursor gas stream by vaporizing a low vapor pressure precursor;

(b) providing said vaporized precursor gas stream to a first conduit while independently controlling the temperature of said first conduit;

(c) providing said vaporized precursor gas stream to a second conduit while independently controlling the temperature of said second conduit;

(d) providing said vaporized precursor gas stream to a third conduit while independently controlling the temperature of said third conduit; and

(e) providing said vaporized precursor gas stream to a processing chamber.

32. The method according toclaim 31 wherein the temperature of said first conduit is lower than the temperature of said second conduit and said third conduit.

33. The method according toclaim 31 wherein the temperature of said first and said second conduits is lower than the temperature of said third conduit.

34. The method according toclaim 31 wherein the cross-sectional flow area of each successive conduit is greater than the cross-sectional flow area of the immediately preceding conduit.

35. A method of delivering vaporized low vapor pressure precursors to a processing chamber, said method comprising the steps of:

(a) forming a vaporized precursor gas stream by vaporizing a low vapor pressure precursor;

(b) providing said vaporized precursor gas stream to a first conduit having a cross sectional flow area while independently controlling the temperature of said first conduit;

(c) providing said vaporized precursor gas stream to a second conduit having an increased cross sectional flow area while independently controlling the temperature of said second conduit;

(d) providing said vaporized precursor gas stream to a third conduit having an increased cross sectional flow area while independently controlling the temperature of said third conduit; and

(e) providing said vaporized precursor gas stream to a processing chamber.

36. A method of delivering vaporized precursor to a processing chamber, said method comprising the steps of:

(a) forming a vaporized precursor gas stream by vaporizing a liquid precursor;

(b) maintaining said vaporized precursor gas stream at a first temperature;

(c) providing a process gas stream at a second temperature; and

(d) mixing said vaporized precursor gas stream and said process gas stream while maintaining said second temperature at least as high as said first temperature.

37. A method of incrementally heating a gas flow, said method comprising the steps of:

(a) flowing a gas in a first conduit while maintaining said first conduit at a temperature;

(b) flowing said gas from said first conduit into a second conduit while maintaining said second conduit at a temperature above said temperature of said first conduit;

(c) flowing said gas from said second conduit into a third conduit while maintaining said third conduit at a temperature above the temperature of said second conduit; and

wherein, the temperature of said first, second and third conduits is less than the decomposition temperature of said gas.

38. A method according toclaim 37 wherein the temperature of said first, second and third conduits is above the condensation temperature of said gas.

39. A method of delivering vaporized low vapor pressure precursors to a processing chamber, said method comprising the steps of:

(a) forming a vaporized precursor gas stream by vaporizing a low vapor pressure precursor;

(b) providing said vaporized precursor gas stream to a first conduit having a cross sectional flow area while independently controlling the temperature of said first conduit;

(c) providing said vaporized precursor gas stream to a second conduit having an cross sectional flow area greater than said cross sectional flow area of said first conduit while independently controlling the temperature of said second conduit;

(d) providing a process gas stream into said second conduit wherein said vaporized precursor gas stream and said process gas stream merge forming a mixed gas stream;

(e) flowing said mixed gas stream for a distance within said second conduit wherein said vaporized precursor gas stream and said process gas stream are homogeneously mixed; and

(f) flowing said homogeneously mixed vaporized precursor gas stream and process gas stream to a processing chamber.

40. An apparatus for processing semiconductor substrates, said apparatus comprising:

(a) a processing chamber comprising:

(i) a resistively heated substrate support disposed internal to said chamber;

(ii) a heated lid forming the top of said chamber; and

(iii) a showerhead gas distribution plate coupled to said lid of said chamber wherein said gas distribution plate further comprises a plurality of apertures; and

(b) a fluid delivery system, said system comprising:

(i) a vaporizer;

(ii) a first conduit having a first diameter and maintained at a first temperature wherein said first conduit is in communication with said vaporizer and said second conduit;

(iii) a second conduit having a second diameter and maintained at a second temperature wherein said second conduit in communication with said first conduit and said third conduit; and

(iv) a third conduit having a third diameter and maintained at a third temperature wherein said third conduit in communication with said second conduit and said processing chamber; and

(c) an exhaust system comprising:

(i) a first conduit in communication with said processing chamber wherein said first conduit is maintained at a first temperature;

(ii) a second conduit in communication with said first conduit wherein said second conduit is maintained at a second temperature; and

(d) a remote plasma generator coupled to said processing chamber.

41. An apparatus according toclaim 40 wherein said fluid delivery system third diameter is greater than each of said first and second fluid delivery system diameters.

42. An apparatus according toclaim 40 wherein fluid delivery system second diameter is greater than said fluid delivery system first diameter.

43. An apparatus according toclaim 40 wherein said second conduit temperature of said liquid delivery system is about the same or greater than said first conduit temperature of said liquid delivery system.

44. An apparatus according toclaim 40 wherein said third conduit temperature of said liquid delivery system is about the same or greater than said first conduit temperature and said second conduit temperature of said liquid delivery system.

45. An apparatus according toclaim 40 wherein said gas distribution plate apertures further comprise first and second cylindrical regions and a conical region.

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