A kind of hybrid bonded methodTechnical field
The present invention relates to ic manufacturing technology fields, and in particular to a kind of hybrid bonded method.
Background technique
As ic manufacturing technology enters 45nm and following technology generation, in order to overcome brought by feature size downsizingTechnical problem, industry have generallyd use some new technologies, such as strained silicon engineering, high dielectric constant/metal gates, multiple exposureLight technology etc., and enter 16nm technology node, traditional two-dimentional cmos device has also turned to three-dimensional FinFET.TheseThe high investment of cutting edge technology and high risk keep numerous middle-size and small-size Integrated circuit manufacturers outside of the door, in order to seek life, thoseThe manufacturers being eliminated can only find another way, and a field technology revolution is being fermented.Three dimensional integrated circuits have been acknowledged asGeneration semiconductor technology, it is advantageous that high-performance, low-power consumption, small physical size, high integration density.How to realize verticalDirectly interconnection is the key that three-dimensionally integrated, and core technology is exactly to stack bonding (Stacked Bonding) and through silicon via (TSV).
There are three types of the manufacturing methods for stacking bonding, i.e., chip chamber bonding, chip are bonded between wafer bonding, silicon wafer.Wherein,Chip-chip bonding is to use most methods at present, and be packaged manufacturer for mass production, although chip-chip bondingYield it is high, but scribing and test need to take a lot of time and resource, the manufacturing cost of this method are very high.Chip-silicon waferBonding techniques first can carry out scribing, detection, the chip picked out to the silicon wafer of the relatively low product of yield, then be bonded to yield compared withOn the silicon wafer of high product, a part of processing step is reduced with this, opposite save the cost, this is the WeiLai Technology trend for encapsulating factory.Silicon wafer-wafer bonding is then suitable for integrated, silicon wafer-wafer bonding maximization production efficiency, letter between the similar product of high yieldChange process flow, minimize cost, but if the yield of silicon wafer is not high or unstable, qualified chip (KGD) quantity will be byLimitation, and then silicon wafer-wafer bonding qualification rate is influenced, this is the main direction of chip manufacturer, can give full play of technologyThe production capacity that generation falls behind.Consider from following mass production application, silicon wafer-wafer bonding and chip-wafer bonding technology will becomeThree-dimensionally integrated mainstream solution.
Silicon wafer-wafer bonding needs to realize the physical bond between silicon wafer using silicon wafer grade bonding techniques, or even directly obtainsObtain the electrical connection between silicon wafer.Silicon wafer grade bonding techniques in three-dimensionally integrated include that bonding is bonded, metal is diffusion interlinked, congruent melting keyIt closes, silicon substrate Direct Bonding and hybrid bonded etc., wherein hybrid bonded is emerging technology and most potential high yield, Gao KeBy the bonding techniques of property.Hybrid bonded (Hybrid bonding) combines metal-metal bonding and dielectric-dielectric bonding, InWhile obtaining vertical metal interconnection, the Physical Mechanical between 3D stacked chips is enhanced using the booster action of medium bondingEnergy.It is carried out simultaneously due to being electrically interconnected with micropore media filler, hybrid bonded technology is effectively simplified 3D process flow, and avoidsCharacteristic size reduces the filling technique challenge of bring medium micropore, can be applied to bonding technology between highdensity silicon wafer.
Between silicon wafer demanding for integration density for bonding technology, it is contemplated that heat budget problem, it is hybrid bonded to adoptThe low-temperature bonding technique of the biggish medium activation of difficulty is integrated to realize with technique, and uses SiO2、Si3N4Equal inorganic mediums are madeFor bonding material.Conventional metal interconnecting layer technique is completed in copper postchannel process, eventually stops at most upper one layer of copper interconnection layerCu CMP process, exposure copper and SiO2Then medium is activated surface dielectric by plasma surface activation technology, when twoWhen piece silicon wafer contacts with each other, stronger physical bond, i.e. cryogenic media bonding technology just occur at normal temperature for surface dielectric, thenCu-Cu is bonded together by a step high-temperature annealing process and forms electrical connection, the common key of metal and medium is obtained with thisIt closes.
But the requirement of the mass of medium on cryogenic media bonding technology para-linkage surface is very high, and in Cu CMP process, siliconMedium flatness in piece is very good, especially medium (such as SiO2、Si3N4) surface roughness requirements control within 0.5nm,Ideal medium bonding effect could be obtained, this brings severe challenge to Cu CMP process.In addition, what Cu CMP process occurredThe defects of scuffing, lapping liquid remain problem can all bring fatal empty problem to medium bonding technology, and then it is good to influence productRate.
Summary of the invention
In order to overcome the above problems, the present invention is intended to provide a kind of low temperature and the hybrid bonded technique of high temperature.
In order to achieve the above object, the present invention provides a kind of hybrid bonded techniques, comprising:
Step 01: a substrate is provided, then using postchannel process formed in the substrate metal contact hole and metal contact hole itBetween dielectric layer；
Step 02: the dielectric layer of etching removal setting thickness makes the surface of metal contact hole be higher by dielectric layer surface；
Step 03: one layer of organic dielectric layer is deposited on the substrate for completing step 02；Wherein, described in organic dielectric layer coveringMetal contact hole；
Step 04: whole removal organic dielectric layer is until expose metal contact hole surface downwards；
Step 05: will be according to the side and the lining with organic dielectric layer of another substrate of step 01~04 preparationThe side with organic dielectric layer at bottom carries out alignment bonding, wherein metal contact hole surface in another substrate with shouldMetal contact hole surface in substrate aligns bonding, the organic media layer surface in another substrate with it is organic in the substrateDielectric layer surface aligns bonding.
Preferably, in the step 02, the setting is with a thickness of the 20%~50% of dielectric layer overall thickness.
Preferably, the step 03 further include: under inert gas atmosphere, anneal to substrate.
Preferably, in the step 04, using chemical mechanical milling tech or using dry etch process come whole downwardsRemoval organic dielectric layer is until expose metal contact hole surface.
Preferably, lapping liquid used by the chemical mechanical milling tech in step 04 is that incorporation granular mass percentage isThe lapping liquid of 1-13%.
Preferably, the dry etch process of step 04 includes the first etch stages and the second etch stages；First etching rankSection, the organic dielectric layer of first thickness is etched away downwards using the first etch rate；Second etch stages, using the second etching speedRate exposes metal contact hole surface after etching away the organic dielectric layer of second thickness downwards；Wherein, the first etch rate is greater thanSecond etch rate, first thickness are greater than second thickness.
Preferably, in the first stage, using containing O2Etching gas, gas flow be 500~1000sccm, radio-frequency powerFor 200~400W；Second stage uses flow for the C of 30~80sccm4F8, flow be 20~60sccm CO, flow 800The mixed gas of the Ar of~1600sccm, radio-frequency power are the radio-frequency power of 100~300W.
Preferably, between the step 04 and the step 05 further include: removal metal contact hole surface is damagedLayers of copper or etch residue.
Preferably, using the metal layer being damaged on chemical mechanical milling tech removal metal contact hole surface, alternatively, adoptingWith the etch residue on wet-etching technology removal metal contact hole surface.
Preferably, thermocompression bonding technique is used in the step 05, used temperature is 300~350 DEG CDEG C, used pressure is 0.5~3MPa, and used heating time is 1.5~3 hours.
Compared with prior art, a kind of hybrid bonded method of the invention uses etching technics and removes certain thickness JieMatter layer re-forms one layer of organic dielectric layer, and integrally removal organic dielectric layer surface certain thickness until expose metallic pattern,And then obtain new bonding surface.The bonding technology temperature and metal approach of the organic dielectric layer, bond strength and SiO2、Si3N4Equal inorganic mediums are close, do not need complicated plasma-activated technology and harsh surface roughness requirements, and have at high temperatureThere is certain flowability, possess very big bonding technology window, advantageously reduces technique and integrate difficulty, improve product yield.
Detailed description of the invention
Fig. 1 is the flow diagram of the hybrid bonded method of a preferred embodiment of the invention
Fig. 2~6 are each step schematic diagram of the hybrid bonded method of a preferred embodiment of the invention
Specific embodiment
To keep the contents of the present invention more clear and easy to understand, below in conjunction with Figure of description, the contents of the present invention are made into oneWalk explanation.Certainly the invention is not limited to the specific embodiment, general replacement known to those skilled in the artIt is included within the scope of protection of the present invention.
Below in conjunction with attached drawing 1~6 and specific embodiment, invention is further described in detail.It should be noted that attached drawingIt is all made of very simplified form, using non-accurate ratio, and only to facilitate, clearly reach aid illustration the present embodimentPurpose.
Referring to Fig. 1, the hybrid bonded technique of one of the present embodiment includes:
Step 01: referring to Fig. 2, providing a substrate 00, then metal contact hole being formed in substrate 00 using postchannel processDielectric layer 01 between 02 and metal contact hole 02；
Specifically, substrate 00 here can use silicon substrate；The material that metal contact hole 02 uses can be copper, step01 can specifically include: provide a silicon substrate 00, first in 00 surface metallization medium layer 01 of silicon substrate, dielectric layer 02 here is madeFor inter-metal medium, it can be pure silicon dioxide, doping silicon dioxide or Low-k medium, can be selected according to different technologies requirementThe medium of suitable k value is selected, and using PECVD technique come metallization medium layer.Then fixed on 01 surface of dielectric layer using photoetching processJustice goes out the graphics field of metal contact hole 02, can be required here according to different integration densities to select suitable photoetching process, such asIn 65nm and following technology generation, must just use 193nm photoetching technique.And contact hole is obtained using etching technics, it generally first adopts hereMedium is carved layer eating away with dry etch process, then removal of residue and photoresist are gone using wet clean process.Then PVD is usedTechnique successively deposits barrier layer and seed layer, and general here first to deposit one layer of very thin Ta (N) barrier layer, redeposited one layer continuousCopper seed layer.ECP process filling copper is used again, contact hole is filled up into copper here, and provides sufficiently thick copper come after guaranteeingContinuous CMP process window.Finally the metallic copper on surface is all ground off using the copper CMP technique of standard, obtains the copper of planarization01 surface of surface and dielectric layer, here it is not strictly necessary that the surface roughness of dielectric layer 01.
Step 02: referring to Fig. 3, the dielectric layer 01 of etching removal setting thickness, is higher by the surface of metal contact hole 0201 surface of dielectric layer；
Specifically, only needing to remove the dielectric layer 01 on a part of surface layer here, but the etch amount of metal contact hole 02 is wantedIt is considerably less, the selective etch of dielectric layer 01 is first carried out using dry etch process, then using wet clean process removal etchingResidue.Since the etch resistant of the copper and tantalum nitrogen barrier layer that deposit in metal contact hole 02 is very capable, and copper reactant is difficult toVolatilization, dry etch process are easier to realize that the etching selection ratio of dielectric layer 01 and copper is greater than 50:1.Dry etch process is passed throughThe C of 40-100sccm4F8, 30-80sccm CO, 800-1600sccm Ar, control process pressure in 50-150mTorr, radio frequencyPower is 200-500W.Wet clean process for removing etch residue, but the etching extent of copper is answered it is as small as possible, using markQuasi- BEOL cleaning process uses the etching of the ST250 cleaning solution removal silicon chip surface of ATMI company under 30~40 DEG C of temperature controlsResidue, preferably 35 DEG C.It is explicitly defined in addition, not made here to 01 etch amount of dielectric layer, 01 etch amount of dielectric layerIt should be determined by the product in different technologies generation, it is known that characteristic size constantly reduces as technology node advances, copper-connection workThe dielectric thickness of skill is also constantly being reduced.For carrying out the metal contact hole 02 of hybrid bonded technique, preferable implementation of the inventionIn case, the etch amount (set etch thicknesses) of dielectric layer 01 is controlled between the 20%-50% of 01 thickness of dielectric layer.
Step 03: referring to Fig. 4, depositing organic dielectric layer 03 on the substrate 00 for completing step 02；
Specifically, organic dielectric layer 03 here should have close to SiO2、Si3N4The bond strength of equal inorganic mediums, and afterThe continuous bonding technology temperature used must not be higher than 400 DEG C, and the organic polymers such as benzocyclobutene BCB, polyimides PI may be selectedMaterial as organic dielectric layer.By taking benzocyclobutene (BCB) as an example, BCB be it is a kind of mixed in high molecular material it is a certain amount ofSilicon powder and the polymer that is formed, physical characteristic and inorganic medium are close, the thermal stability that has had, mechanical stability and resistAcid/base corrosivity, all fine with the matching degree and adhesive force of Si sill, BCB bond strength meets lining up to 20MPa or moreThe requirement of bonding techniques between bottom has certain fluidity, can have in addition, BCB will become glassy state under 300 DEG C of temperatures aboveFilling pore is imitated, bonding effect between ideal silicon wafer is obtained.Here it is possible to which BCB is flatly sunk using traditional spin coating proceedingThen under inert gas atmosphere product, anneals to BCB in surface of silicon, such as carry out 200~300 under n 2 atmosphereDEG C be preferably 250 DEG C at carry out annealing 20~30 minutes, solidify BCB organic media, and has obtained adhesion and physics spyProperty.As shown in figure 4, organic dielectric layer 03 covers metal contact hole 02, and metal contact hole is higher by the top of organic dielectric layer 03The certain height in 02 top.
Step 04: referring to Fig. 5, whole removal organic dielectric layer 03 is until expose 02 surface of metal contact hole downwards；
Specifically, between step 04 and step 05 further include: the metal layer being damaged on removal 02 surface of metal contact holeOr etch residue.Organic dielectric layer 03 will be removed below and removes the metal layer being damaged or the quarter on 02 surface of metal contact holeThe process of erosion residue comes together to be described in detail.
Here it is possible to remove organic dielectric layer 03 using chemical mechanical milling tech, used lapping liquid is incorporationHydrogen peroxide, and/or the lapping liquid that incorporation granular mass percentage is 1-13%；Firstly, selection chemical mechanical grinding (CMP) techniqueOrganic dielectric layer 03 is ground, until exposing 02 surface of metal contact hole, the higher incorporation hydrogen peroxide of granule content can be usedMedium milling liquid is ground off the organic dielectric layer 03 on surface by the collective effect of oxidation organic dielectric layer 03 and physical grinding,CMP process has planarization capability, can efficiently control the flatness of bonding surface, further, CMP process can also be in exposureThe layers of copper being damaged on a part of surface layer is ground off while metal contact hole 02 out, is repaired in step S02 with this to copper surfaceEtching injury or reactant residual, these are all conducive to the bonding technology between subsequent silicon substrate.
Further, it is also possible to be connect come whole removal organic dielectric layer 03 downwards until exposing metal using dry etch process02 surface of contact hole；Then using the etch residue on wet-etching technology removal 02 surface of metal contact hole.Due to organic mediaLayer 03 has certain mobility at high temperature, can effective filling pore, thus, it is only required to metal contact hole 02 is exposed,It is not strictly necessary that the flatness and roughness on 03 surface of organic dielectric layer.
Specifically, dry etch process includes the first etch stages and the second etch stages.
In the first etch stages, the organic dielectric layer 03 of first thickness is etched away downwards using the first etch rate；SecondEtch stages expose metal contact hole 02 after etching away the organic dielectric layer 03 of second thickness downwards using the second etch rateSurface；The metal surface of metal contact hole 02 is oxidized in order to prevent, so, the first etch rate of use is greater than the second etchingRate, first thickness are greater than second thickness.Specifically, in the first stage, using containing O2Etching gas quickly by organic mediaLayer 03 is whole to be etched down to close to 02 surface of metal contact hole, using containing O2Gas flow is 500~1000sccm, radio frequency functionRate is 200~400W.Then, in second stage, use flow for the C of 30~80sccm4F8, flow be 20~60sccm CO,Flow is the mixed gas of the Ar of 800~1600sccm, and radio-frequency power is the radio-frequency power of 100~300W.
After dry etch process, etch residue, etching temperature can be removed using copper-connection wet-etching technologyIt is 30~40 DEG C, for example, by using ST250 cleaning solution.
Step 05: referring to Fig. 6, by organic dielectric layer is had according to step 01~04 preparation another substrate 00'The side of 03' carries out alignment with the side with organic dielectric layer 03 of the substrate 00 and is bonded, wherein another substrateThe surface metal contact hole 02' in 00' is aligned with 02 surface of metal contact hole in the substrate 00 to be bonded, another substrateThe surface organic dielectric layer 03' in 00' is aligned with 03 surface of organic dielectric layer in the substrate 00 to be bonded.
Specifically, using thermocompression bonding technique, used temperature is 300~350 DEG C, used pressure is 0.5~3MPa, used heating time are 1.5~3 hours.Preferably, temperature used by high annealing is 340 DEG C, it is usedPressure is 1.2MPa, and used heating time is 2 hours.
Although the present invention is disclosed as above with preferred embodiment, right embodiment is illustrated only for the purposes of explanation, andIt is non-to limit the present invention, those skilled in the art can make without departing from the spirit and scope of the present invention it is several moreDynamic and retouching, the protection scope that the present invention is advocated should be subject to claims.