US20050133166A1 - Tuned potential pedestal for mask etch processing apparatus - Google Patents

Abstract

The present invention generally provides an improved pedestal for supporting a substrate. The pedestal has greatest application during a plasma etching process, such as for a quartz photomask, or “reticle.” The pedestal defines a body, and a substrate support base along an upper surface of the body. The substrate support base has an outer edge, and an intermediate substrate support ridge for receiving and supporting the substrate. At least a portion of the substrate support base outside of the intermediate substrate support ridge is fabricated from a dielectric material. The purpose is to couple greater RF power through the reticle in order to enhance the plasma etching process.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• The present application claims priority to previously filed provisional patent application Ser. No. 60/531,062, filed Dec. 19, 2003, entitled “Tuned Potential Pedestal for Mask Etch Processing Apparatus.” The provisional application is incorporated herein by referenced in its entirety.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention generally relates to the fabrication of integrated circuits. More specifically, the invention relates to an apparatus for manufacturing a photomask, or “reticle,” useful in manufacturing semiconductors.
• 2. Description of the Related Art
• Integrated circuits (IC) are manufactured by forming discrete semiconductor devices on a surface of a semiconductor substrate. An example of such a substrate is a silicon (Si) or silicon dioxide (SiO₂) wafer. To interconnect the devices on the substrate, a multi-level network of interconnect structures is formed. Material is deposited on the substrate in layers and selectively removed in a series of controlled steps.
• Increasing circuit densities have placed additional demands on processes used to fabricate semiconductor devices. For example, as circuit densities increase, the widths of vias, contacts and other features, as well as the dielectric materials between them, decrease to sub-micron dimensions. However, the thickness of the dielectric layers remains substantially constant, with the result that the aspect ratios for the features, i.e., their height divided by width, increases. Reliable formation of high aspect ratio features is important to the success of sub-micron technology and to the continued effort to increase circuit density and the quality of individual substrates and die.
• Reliable formation of high aspect ratio features with desired critical dimensions requires precise patterning and subsequent etching of the substrate. A technique commonly used to form precise patterns on substrates is photolithography. The technique generally involves the direction of light energy through a lens, or “reticle” and onto the substrate. In conventional photolithographic processes, a photoresist material is first applied on a substrate layer to be etched. In the context of optical resists, the resist material is sensitive to light energy, such as ultraviolet or laser sources. The resist material defines a polymer that is tuned to respond to the specific wavelength of light used, and to different exposing sources.
• After the resist is deposited onto the substrate, the light source is actuated to emit ultraviolet (UV) light or low X-ray light, for example, directed at the resist-covered substrate. The selected light source chemically alters the composition of the photoresist material. However, the photoresist layer is only selectively exposed. In this respect, a photomask, or “reticle,” is positioned between the light source and the substrate being processed. The photomask is patterned to contain the desired configuration of features for the substrate. The patterned photomask causes the light energy to strike the resist material in accordance with the pattern.
• Photolithographic reticles are fabricated from an optically transparent material, such as quartz (i.e., silicon dioxide, SiO₂). The reticle includes a pattern of opaque material that inhibits the light from exposing portions of the substrate in accordance with the desired pattern. A thin opaque layer of metal, typically chromium, is disposed on the surface of the reticle. This light-shielding layer is patterned to correspond to the features to be transferred to the substrate, such as transistors or polygates. The metallic material is patterned using conventional laser or electron beam patterning equipment to define the critical dimensions to be transferred to the metal layer. The metal layer is then etched to remove the metal material not protected by the patterned resist, thereby exposing the underlying quartz material and forming a patterned photomask layer. Photomask layers thus allow light to pass therethrough in a precise pattern onto the substrate surface.
• In photolithography, the exposed material may either be a positive resist or a negative resist. In a positive resist, the exposed resist material on the substrate is removed, while in a negative resist, the unexposed portions are removed. Removal is typically by a chemical process to expose an underlying substrate material. The exposed underlying substrate material may then be etched to form patterned features in the substrate surface while the retained resist material remains as a protective coating for the unexposed underlying substrate material. In this manner, contacts, vias, or interconnects may be formed by exposing the resist to a pattern of light through a photolithographic reticle having a photomask layer disposed thereon.
• In an iterative convergence, the method for fabricating a patterned reticle itself involves a deposition and subsequent etching process. In this respect, a metal layer is first deposited on a top surface of a glass reticle. Thereafter, selected portions of the metal layer are removed through etching. Various types of etching processes are used for etching the metal layer from a reticle. One such etching method is known as plasma etching. In order to perform plasma etching, a glass reticle is first placed within a process chamber. More specifically, the glass reticle is placed on a pedestal. In a plasma etching process, the pedestal serves as a cathode. To this end, the metallic pedestal is given RF power. Power applied to the pedestal creates a substrate bias in the form of a negative voltage on the upper surface of the reticle. This negative voltage is used to attract ions from a plasma formed above the reticle in the chamber. The plasma is formed by the application of power to one or more inductive coils at the top of the chamber. The inductive coils generate and sustain the plasma above the pedestal and reticle. Thus, a voltage drop is induced across the pedestal that draws ions to the upper surface of the reticle, thereby etching a metallic layer.
• Because the reticle is formed from a material having a low dielectric constant, e.g., glass or quartz, the amount of RF power that is coupled through the reticle is low. This inhibits the gas plasma in reacting with the reticle surface. This limitation is compounded by a gap typically existing between the reticle and the supporting pedestal therebelow. In addition, when the surface area of the pedestal is large compared to the reticle area, the RF power may preferentially couple to other regions of the pedestal, producing a loss of RF power. Further, it has been observed that the use of a pedestal cover, e.g., cover ring and capture ring, fabricated from a dielectric material is inadequate to lessen the power coupled through the region of the pedestal that is not immediately below the reticle.
• Therefore, there is a need for a plasma etching apparatus that aids in the chemical reaction between a gas plasma and a reticle. In addition, there is a need for a pedestal fabricated from a material that does not contribute to the power loss across the reticle during a plasma etching procedure.
SUMMARY OF THE INVENTION
• The present invention generally provides an improved pedestal for supporting a substrate and related substrate support hardware. The pedestal has greatest application during a plasma etching process, such as for a quartz photomask, or “reticle.”
• The pedestal defines a body, and a base along on an upper surface of the body. The body receives an RF power during substrate processing. The substrate support base has an outer edge, and an intermediate substrate support ridge for receiving and supporting the substrate. At least a portion of the substrate support base outside of the intermediate substrate support ridge is fabricated from a dielectric material, or material having a lower dielectric constant than the remaining support base. An example is quartz. Quartz has a lower dielectric constant than the materials typically used for fabricating the pedestal body or cover, e.g., alumina. The placement of quartz allows greater RF power to be coupled through the reticle, thereby enhancing the plasma etching process. It also provides greater control over the relative amount of RF power coupled through the reticle.
• In one aspect, a layer of dielectric material is placed along the top of the support base of the pedestal body. In another embodiment, the entire cross-sectional thickness of the support base that encompasses the supporting ridge is fabricated from a dielectric material. In one embodiment, a separate substrate support assembly is disposed on the base to facilitate the transfer of the substrate onto and off of the pedestal, with the substrate support assembly being fabricated from a dielectric material.
BRIEF DESCRIPTION OF THE DRAWINGS
• So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are, therefore, not to be considered limiting of its scope.
• FIG. 1 is a cross-sectional view of a plasma etching chamber as might contain the pedestal of the present invention. The chamber shown inFIG. 1 is exemplary.
• FIG. 2 presents an exploded perspective view of the substrate support member ofFIG. 1.
• FIG. 3 shows a perspective cutaway view of one embodiment of a pedestal of the present invention.
• FIG. 4 provides a cross-sectional schematic view of a pedestal of the present invention. A portion fabricated from a dielectric material is shown.
• FIG. 5 presents a cross-sectional schematic view of a pedestal of the present invention, in an alternate embodiment. A portion fabricated from a dielectric material is again shown.
DETAILED DESCRIPTION OF THE INVENTION
• Aspects of the invention will be described below in reference to an inductively coupled plasma etch chamber. Suitable inductively coupled plasma etch chambers include the Decoupled Plasma Source (DPS™) chamber available from Applied Materials, Inc., of Santa Clara, Calif., or the ETEC Tetra™ photomask etch chamber available from ETEC of Hayward, Calif. A two-coil chamber, such as the Tetra II™ decoupled plasma source chamber available from Applied Materials, Inc. may also be employed. Other process chambers may be used including, for example, capacitively coupled parallel plate chambers and magnetically enhanced ion etch chambers, as well as inductively coupled plasma etch chambers of different designs. Although the processes are advantageously performed with the DPS™ processing chamber, the description in conjunction with the DPS™ processing chamber is illustrative and should not be construed or interpreted to limit the scope of aspects of the invention.
• In order to perform plasma etching, a substrate, e.g., a glass reticle, is placed within a processing chamber. An example of such a chamber is schematically shown inFIG. 1. Theprocess chamber100 ofFIG. 1 has asubstrate support member200 disposed therein, and asubstrate handler blade300 positioned adjacent thereto.Substrates222 are shown positioned on both thesubstrate support member200 and thehandler blade300.
• Theprocessing chamber100 is configured to receive asubstrate222, such as a glass reticle to be processed through plasma etching. Thesubstrate222 enters and exits thechamber100 through agate161. Thegate161 serves as a port, and also isolates thechamber100 environment during reticle processing. Thesubstrate222 is transported via a substrate cassette, using thesubstrate handling blade300. Thesubstrate handling blade300 transfers thesubstrate222 between a separate transfer chamber (not shown) and various processing chambers. In this respect, it is understood that the reticle fabrication process involves multiple steps, and that different steps are typically conducted in different chambers that mechanically cooperate with thesubstrate handling blade300. An example of such a processing system is a Centura™ processing system available from Applied Materials, Inc. of Santa Clara, Calif.
• Theprocess chamber100 generally includes acylindrical side wall162. Theside wall162 helps define the chamber body, and also supports thegate161. Thechamber100 is also defined by achamber bottom167, and an energy transparent ceiling orlid163. Aninductive coil176 is disposed around at least a portion of thelid163. Thechamber body162 andchamber bottom167 of thechamber100 can be made from a metal, such as anodized aluminum. Thelid163 is fabricated from an energy transparent material such as a ceramic or other dielectric material.
• As mentioned above, thechamber100 holds asubstrate support member200. Thesupport member200 supports thesubstrate222 during processing. Aplasma zone164 is defined by theprocess chamber100 above an upper surface of thesubstrate support member200. During processing, process gases are introduced into theplasma etch chamber100 through agas distributor172. Thegas distributor172 is peripherally disposed about thesubstrate support member200. Thegas distributor172 is shown illustratively, and may be disposed in other configurations, such as disposed at the top oflid163. Process gases and etchant byproducts may be exhausted from theprocess chamber100 through an exhaust system (not shown). Anoptional cooling line184 is provided in thepedestal200. for controlling the pressure in theplasma etch chamber100. An endpoint measurement device may optionally be included to determine the endpoint of a process performed in thechamber100.
• With respect to thesubstrate support member200 itself, thesupport member200 defines a pedestal for thesubstrate222 during processing. Thesupport member200 first comprises abody206. Thebody206 has an upper surface that defines a substrate support base210 (seen inFIG. 2). In one arrangement, thesubstrate support base210 is a separate piece mounted on an upper surface of thebody206. An optionalsubstrate supporting assembly215 is preferably provided over the base210 to aid in transporting thesubstrate222 into and out of thechamber100. Thesubstrate supporting assembly215 is shown in detail inFIG. 2. Only thecapture ring216 of the supportingassembly215 is seen inFIG. 1.
• Referring back toFIG. 1, thebody206 of thesubstrate support member200 is mounted on a bulk head assembly, or shaft,102. In the embodiment shown, thebody206 is stationary in thechamber100; however, in an alternative embodiment, the body206 (or a portion of the body206) may be moveable within thechamber100. In one arrangement, thebody206 of thesubstrate support member200 is mounted on astainless steel base104. Thebase104 is typically disposed on the bottom of the processing chamber (not shown inFIG. 2), with thebulk head assembly102 mounted through the bottom of theprocessing chamber100 and coupled to thebody206. Thesubstrate support member200 is adapted to maintain vacuum isolation between the interior of thechamber100 and the outside environment. Power, electrical controls, and backpressure gases may be provided to thesubstrate support member200 via theshaft102.
• FIG. 2 presents an exploded perspective view of one embodiment of asubstrate support member200. FromFIG. 2, thebody206 andsupport base210 are more clearly seen. It can also be seen that acathode112 is disposed in thesupport base210. Thecathode112 may optionally vertically extend above the surface of thebody206. Thecathode112 is electrically coupled to anelectrode power supply178 to generate a capacitive electric field in theplasma etch chamber100. Typically an RF voltage is applied to thecathode112 while thechamber body162 is electrically grounded. Power applied to thepedestal200 creates a substrate bias in the form of a negative voltage on the upper surface of thesubstrate222. This negative voltage is used to attract ions from the plasma formed in thechamber100 to the upper surface of thesubstrate222. The capacitive electric field forms a bias which accelerates inductively formed plasma species toward thesubstrate222 to provide a more vertically oriented anisotropic etching of thesubstrate222.
• Channels211 (three are shown) are also disposed through thebody206, and house internally movable lift pins214 therein. As will be discussed further below, the lift pins214 engage the lower surface of acapture ring220 to move thecapture ring220 vertically within thechamber100 relative to thecover ring216. Thebody206 may comprise a temperature controlled base adapted to regulate the temperature of thesubstrate support assembly215, and thus, asubstrate222 disposed thereon. Thebody206 can be made of a material inert to the process formed in the processing chamber including, for example, aluminum oxide, or aluminum, andsubstrate support assembly215 components can be made of aluminum or aluminum oxide. Thebody206 may include fluid channels, heating elements, e.g., resistive heating elements or other temperature control members.
• In the support member arrangement ofFIG. 2, thesubstrate support member200 includes a separatesubstrate supporting assembly215. Thesubstrate supporting assembly215 generally includes acover ring216 and acapture ring220.
• Referring first to thecover ring216, thecover ring216 is preferably a circular ring having anupper surface219 and support shoulders218. The substrate supports218 define shoulders for receiving a substrate (not shown). In one arrangement, the substrate supports218 define opposing raisedsurfaces221,223 that each includes an inner sloped surface for receiving a substrate. Acentral opening225 is formed in theupper surface219 of thecover ring216. The two raisedsurfaces221,223 are generally disposed on opposing sides of thecentral opening225. The first raisedsurface221 defines an essentially linear raised surface extending along the length of one side of thecentral opening225. The second raisedsurface223 defines an arcuate raisedsurface221 having anouter diameter224 and aninner diameter226. Theouter diameter224 generally matches the radius of thecover ring216, while theinner diameter226 conforms to the geometry of thecentral bore225 along one or more sides of thebore225. Theupper surface219 and the raisedsurfaces221,223 may be monolithic or may be made of separate components connected together.
• Thecapture ring220 defines an arcuate base plate having aninner diameter207 and anouter diameter202. Acentral bore206 is formed within theinner diameter207 of thecapture ring220. Thediameters207,202 of thecapture ring220 are not continuous, but retain an opening that serves as part of thebore206. As with thecover ring216, thecapture ring220 includes substrate supports204,205. The substrate supports204,205 generally follow theinner diameter207 of thecapture ring220. In the arrangement ofFIG. 2, thesupports204,205 define shoulders disposed along theinner perimeter207. The substrate supports204,205 and thebase plate202 form a substrate receiving area. Theshoulders204,205 and thebase plate202 are adapted to mate with the substrate supports218 on thecover ring216. When thecapture ring220 is rested upon thecover ring216, the substrate supports205 for thecapture ring220 are co-planar with the substrate supports218 for the cover ring. Thecapture ring220 is dimensioned to rest on thecover ring216 without covering the two raisedsurfaces221,222 on thecover ring216. Together, the substrate supports205,218 may then seamlessly receive a substrate (not shown).
• Thecapture ring220 moves vertically above thecover ring216. In operation, the lift pins214 move thecapture ring220 vertically above thecover ring216 during substrate transfer, and then lower thecapture ring220 onto thecover ring216 for substrate processing. The use of lift pins in the semiconductor fabrication business is known, and those of ordinary skill in the art will understand from this disclosure how the lift pins may be fabricated.
• Channels217 are formed through thecover ring216 to enable the lift pins214 disposed through thebody206 to move therethrough and lift thecapture ring220 vertically. The vertical movement imparted by the lift pins214 is used to lift thecapture ring220 to effectuate substrate transfer between thesubstrate handler blade300 and thecapture ring220. The lift pins214 move thecapture ring220 vertically above thecover ring216 during substrate transfer, and then lower thecapture ring220 onto thecover ring216 for substrate processing.
• To begin processing, the reticle222 (or other substrate) is positioned on the surface of thepedestal200. Etch gases are then introduced into thechamber100. To this end, a process gas source supplies gas, such as an oxygen based gas, through agas input line172. In the arrangement ofFIG. 1, theinput line172 feeds gas into the side of thelid163. However, gas may also be introduced through nozzles (not shown) in the top of thelid163. Chamber pressure is controlled by a closed-loop pressure control system (not shown).
• As gas is injected into thechamber100, a gas plasma is created. Plasma is formed by the application of power to one or moreinductive coils176 at the top of thelid163. In thechamber100 ofFIG. 1, twoRF coils176 are used, with one being an outer coil and one being an inner coil. Apower supply177 and matching network is used to apply power to theinductive coils176. Theinductive coils176 generate and sustain the plasma above thepedestal200 andsubstrate222. In one arrangement, approximately 125 Watts is applied to thecoils176 at a frequency of about 13.56 MHz, to produce and maintain an oxygen-comprising plasma over the surface of thereticle222. In one arrangement for a dual coil system, approximately 400 Watts is applied to thecoils176 at a frequency of about 13.56 MHz, to produce and maintain a chlo7rine-and-oxygen-comprising plasma over the surface of thereticle222. For a single coil system, the coils may provide a DC bias of about 340 to 410 Volts on the reticle surface.
• FIG. 3 shows a perspective cutaway view of one embodiment of apedestal300 of the present invention. Thepedestal300 is configured to receive and support a substrate in a plasma etching chamber. Preferably, the substrate is a photolithographic reticle, and the chamber is a plasma etching chamber, such as the chamber shown inFIG. 1, and discussed above.
• The pedestal first comprises abody306. In the arrangement ofFIG. 3, thebody306 is a generally cylindrical object, though other shapes may be employed. Thebody306 includes anupper surface310 that serves as a substrate support base. In the arrangement shown inFIG. 3, thesupport base310 has a radialouter diameter324. The base310 also has anintermediate shoulder326 that forms a four-sided support ridge325. Thesupport ridge325 serves to support the reticle above thepedestal300 during processing. Thesupport ridge325 is preferably fabricated from a metallic material. The term “support ridge” means any raised surface feature of any height or shape along thesupport base310 that contacts and supports asubstrate222 during processing.
• Thesupport base310 is typically configured to receive a cover (not shown) to further support a reticle during processing. The cover may be configured to operate as thesubstrate support assembly215 described above.
• In thenovel pedestal300 of the present invention, at least a portion of thebody306 is fabricated from a dielectric material. In the cutaway view ofFIG. 3, the dielectric material portion of thebody306 is shown at318.Dielectric material318 is selectively used in theupper surface310 so as to define a dielectric ring generally about the perimeter of thebody306. Thedielectric material318 is placed outside of the contact point, e.g.,support ridge326, for thereticle222 on thepedestal300. Thedielectric material portion318 of thebody306 may comprise two or more separate components (not shown) joined together to form thedielectric portion318 of thebody306. The two or more dielectric members may be fabricated from materials having different dielectric properties. The benefit of using material of different dielectric properties is to control the relative amount of RF power coupled through the reticle, as the thickness and dielectric property of the reticle substrate, e.g., quartz, is fixed.
• Thedielectric material portion318 of thebody306 may be of different thicknesses. This is demonstrated in the schematic embodiments shown inFIGS. 4 and 5.FIG. 4 provides a cross-sectional view of apedestal300′ of the present invention. Thepedestal300′ is shown schematically. Likewise,FIG. 5 presents a cross-sectional view of apedestal300′ of the present invention, in an alternate embodiment. Thepedestal300″ is again shown schematically. In each view, areticle222 is shown being supported on therespective pedestal300′,300″. Further, in each view acover315 is provided. Thecover315 may be configured in accordance with thecover215 shown in the exploded view ofFIG. 2. Thecover315 is preferably fabricated from a dielectric material. The use of different dielectric material thickness is to adjust or control the relative RF power coupled to the reticle. One benefit of using a dielectric material is it enables the use of two control knobs, that is knobs for dielectric constant and thickness. This, in turn, enables the operator to change the relative amounts of RF that goes into the reticle versus the RF power that goes to the pedestal area surrounding the reticle. The dielectric thickness and type may be such that the relative amount is the same for uniform power distribution, or different if needed for compensating for the etch process.
• Dielectric material is shown at318 in bothFIG. 4 and inFIG. 5. InFIG. 4, thedielectric material318 resides along the top of theupper support base306. InFIG. 5, thedielectric material318 defines substantially the entire thickness of theupper support base306. In either instance, thedielectric material318 is preferably placed outside of the contact point for thereticle222 on thepedestal300.
• As can be seen, thepedestals300,300′,300″ place dielectric material along a periphery of the uppersubstrate support body306. Thedielectric material318 may be polymeric or ceramic. An example of a polymeric material is Ardel™ polyarylate material manufactured by Amoco polymers. Another example is Vespel™ polyimide from DuPont. Still another example is a plastic material sold under the trade name Ultem™. Yet another example is a synthetic rubber material. An example of a suitable ceramic material is aluminum oxide. Another example of an acceptable dielectric material is quartz. The selected use ofdielectric material318 has the effect of changing the amount of RF power coupling into the reticle during a plasma etching procedure. In this respect, during a plasma etching procedure, thebody306 receives power, such as an RF power. By using dielectric material on the periphery of the body, the potential drop across the pedestal is changed to have a value less than the region where the reticle rests, i.e., inside of thesubstrate support ridge326. The portion of thepedestal300 within thesubstrate support ridge326 remains metallic in order to efficiently conduct waste heat away from thereticle222.
• While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims (19)

1. A pedestal for supporting a substrate in a plasma etching chamber, comprising:

a body, the body being configured to receive an RF power; and

a substrate support base along an upper surface of the body, the substrate support base having an outer edge, and an intermediate substrate support ridge for receiving and supporting the substrate;

and wherein at least a portion of the substrate support base outside of the intermediate substrate support ridge is fabricated from a dielectric material.

2. The pedestal ofclaim 1, wherein the portion of the substrate support base within the substrate support ridge is fabricated from a metallic material.

3. The pedestal ofclaim 2, wherein the portion of the substrate support base fabricated from a dielectric material is formed by placing a layer of dielectric material along a top surface of the substrate support base outside of the substrate support ridge in order to form a dielectric ring.

4. The pedestal ofclaim 3, wherein the substrate support ridge is fabricated from a metallic material.

5. The pedestal ofclaim 3, wherein the dielectric material is fabricated from materials selected from the group consisting of a polymeric material, a ceramic material, and combinations thereof.

6. The pedestal ofclaim 2, wherein the portion of the substrate support base fabricated from a dielectric material defines substantially the entire thickness of the substrate support base outside of the substrate support ridge.

7. The pedestal ofclaim 6, wherein the substrate support ridge is fabricated from a metallic material.

8. The pedestal ofclaim 6, wherein the dielectric material is fabricated from materials selected from the group consisting of a polymeric material, a ceramic material, and combinations thereof.

9. The pedestal ofclaim 1, further comprising a cover configured to be received on the substrate support base.

10. A pedestal for supporting a reticle in a plasma etching chamber, comprising:

a body, the body being configured to receive an RF power;

a reticle support base along an upper surface of the body, the reticle support base having an outer edge, and an intermediate reticle support ridge for receiving and supporting the reticle;

and wherein at least a portion of the reticle support base outside of the intermediate substrate support ridge is fabricated from a dielectric material.

11. The pedestal ofclaim 10, wherein:

the portion of the reticle support base within the reticle support ridge is fabricated from a metallic material;

the reticle support ridge is fabricated from a metallic material; and

12. The pedestal ofclaim 10, wherein the dielectric material is fabricated from at least one of a polymeric material and a ceramic material.

13. The pedestal ofclaim 12, wherein the portion of the reticle support base fabricated from a dielectric material is formed by placing a layer of dielectric material along a top surface of the reticle support base outside of the reticle support ridge in order to form a dielectric ring.

14. The pedestal ofclaim 12, wherein the portion of the reticle support base fabricated from a dielectric material defines substantially the entire thickness of the reticle support base outside of the reticle support ridge

15. A plasma etching chamber having a pedestal therein for supporting a reticle, comprising:

a chamber body defining a base wall, a side wall and a dome;

a gate along the side wall for permitting a reticle to be moved into the plasma etching chamber; and

a reticle support member for supporting a reticle within the plasma etching chamber during processing, the reticle support member comprising:

a body, the body being configured to receive an RF power;

a reticle support base along an upper surface of the body, the reticle support base having an outer edge, and an intermediate reticle support ridge for receiving and supporting the reticle;

and wherein at least a portion of the reticle support base outside of the intermediate substrate support ridge is fabricated from a dielectric material.

16. The chamber ofclaim 15, wherein:

the portion of the reticle support base within the reticle support ridge is fabricated from a metallic material;

the reticle support ridge is fabricated from a metallic material; and

17. The chamber ofclaim 16, wherein the dielectric material is fabricated from at least one of a polymeric material and a ceramic material.

18. The chamber ofclaim 17, wherein the portion of the reticle support base fabricated from a dielectric material is formed by placing a layer of dielectric material along a top surface of the reticle support base outside of the reticle support ridge in order to form a dielectric ring.

19. The chamber ofclaim 17, wherein the portion of the reticle support base fabricated from a dielectric material defines substantially the entire thickness of the reticle support base outside of the reticle support ridge

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