Joint protection for electrostatic chucks in plasma processing chambers - Patents.com

Abstract

An electrostatic chuck system for use in a plasma processing chamber is provided. A conductive base plate is provided. A bonding portion of a bonding material is bonded to a surface of the base plate at a first surface thereof. A ceramic plate is bonded to a second surface of the bonding portion. A protective strip surrounds the bonding portion and extends between the conductive base plate and the ceramic plate. The protective strip includes at least one of an anodized strip, a ceramic tape strip, and a coated aluminum strip.

Description

[Background technology]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority to U.S. Application No. 63 / 399,148, filed August 18, 2022, which is incorporated by reference for all purposes.

[0002] The present disclosure relates to components of plasma processing chambers used in semiconductor processing. In particular, the present disclosure relates to electrostatic chucks used in plasma processing chambers.

[0003] In plasma processing chambers, electrostatic chucks are used to support substrates being processed. The electrostatic chucks may be exposed to different temperatures and various plasma processes. Some electrostatic chucks provide a ceramic plate bonded to a metal base plate. The bonding material bonds the ceramic plate to the metal base plate and is flexible enough to accommodate the different thermal expansion coefficients of the ceramic plate and the metal base plate. The bonding material may provide electrical and thermal conductivity between the ceramic plate and the metal base plate. Portions of the bonding material may be exposed to radicals during plasma processing. The radicals may degrade and / or corrode the bonding material. Periodic replacement of the bonding material increases downtime and ownership costs.

[0004] The Background Art provided herein is intended to present the contents of the present disclosure generally. Information provided in this Background Art section, and in aspects of the description that are not prior art at the time of filing, is not admitted expressly or impliedly as prior art to the present disclosure. Summary of the Invention

[0005] To carry out the foregoing and in accordance with the objectives of the present disclosure, an electrostatic chuck system for use in a plasma processing chamber is provided. An electrically conductive base plate is provided. A bonding portion of a bonding material is bonded to a surface of the base plate at a first surface of the bonding portion. A ceramic plate is bonded to a second surface of the bonding portion. A protective strip surrounds the bonding portion and extends between the electrically conductive base plate and the ceramic plate. The protective strip includes at least one of an anodized strip, a ceramic tape strip, and a coated aluminum strip.

[0006] In another embodiment, a method for providing an electrostatic chuck system is provided. A conductive base plate is provided. The conductive base plate is bonded to a ceramic plate using a bonding material to form a joint. A protective strip is disposed around the periphery of the joint and extends between the conductive plate and the ceramic plate, and includes at least one of an anodized strip, a ceramic tape strip, and a coated aluminum strip.

[0007] These and other features of the present disclosure are described in more detail below in the detailed description taken in conjunction with the following figures. [Brief explanation of the drawings]

[0008] Embodiments of the disclosure are illustrated by way of example, and not limitation, in the figures of the accompanying drawings, in which like reference numerals refer to similar elements and in which:

[0009] [Figure 1] 1 is a high-level flowchart of a process that may be used in some embodiments.

[0010] [Figure 2A] 1 is a schematic cross-sectional view of an electrostatic chuck system used in some embodiments. [Figure 2B] 1 is a schematic cross-sectional view of an electrostatic chuck system used in some embodiments. [Figure 2C] 1 is a schematic cross-sectional view of an electrostatic chuck system used in some embodiments. [Figure 2D] 1 is a schematic cross-sectional view of an electrostatic chuck system used in some embodiments. [Figure 2E] 1 is a schematic cross-sectional view of an electrostatic chuck system used in some embodiments.

[0011] [Figure 3] FIG. 2 is a top view of a protective strip used in some embodiments.

[0012] [Figure 4] FIG. 1 is a schematic layout diagram of an etching reactor that may be used in some embodiments.

[0013] [Figure 5] 1 is a schematic cross-sectional view of an electrostatic chuck system used in some embodiments.

[0014] [Figure 6] 1 is a schematic cross-sectional view of an edge seal used in some embodiments.

[0015] [Figure 7] 1 is a schematic cross-sectional view of an edge seal used in some embodiments.

[0016] [Figure 8A] FIG. 10 is a partial cross-sectional view of a base plate joined to a ceramic plate by a ring-encircled joint comprising a split anodized ring encased in a polymer coating.

[0017] [Figure 8B] 1 is a cross-sectional view of a segment of a split anodized ring encased in a polymer coating. DETAILED DESCRIPTION OF THE INVENTION

[0018] Embodiments will now be described in detail with reference to some embodiments thereof as illustrated in the accompanying drawings. In the following description, specific details are set forth to provide a thorough understanding of the present disclosure. However, the present disclosure may be practiced without some or all of these specific details and includes modifications that may be made according to knowledge commonly known within the art. Well-known process steps and / or structures have not been described in detail to avoid unnecessarily obscuring the present disclosure.

[0019] Certain electrostatic chuck (ESC) systems may require bonding a ceramic material to a metal heat sink (cooling) base plate. In some ESC systems, the ceramic plate is bonded to the metal base plate with a bonding material. The bonding material is flexible enough to accommodate the different thermal expansion coefficients of the ceramic plate and metal base plate over a wide temperature range. The bonding material may provide electrical and thermal conductivity between the ceramic plate and metal base plate. The bonding material may corrode when exposed to plasma. Corrosion of the bonding material causes thermal non-uniformities between the ceramic plate and the substrate, resulting in process non-uniformities. Replacing and / or preparing the bonding material increases chamber downtime and cost of ownership. An O-ring may be installed in advance to protect the bonding material. Although the O-ring reduces the bonding material's exposure to radicals during plasma processing, the bonding material may still be exposed to radicals. Additionally, the O-ring may deteriorate, increasing the bonding material's exposure to radicals. Replacing the deteriorated O-ring and bonding material increases downtime and cost of ownership.

[0020] FIG. 1 is a high-level flowchart of a process used in some embodiments for ease of understanding. An electrically conductive base plate of an electrostatic chuck (ESC) system is provided. FIG. 2A shows a partial cross-sectional view of the base plate 208. In some embodiments, the base plate 208 is made of metal. In some embodiments, the base plate 208 may include channels 209 for gas or liquid flow. These channels may be formed, for example, with compound distribution channels, to cool or heat the base plate 208. In some embodiments, the base plate 208 is formed of aluminum alloy (Al) and / or aluminum silicon carbide (Al-SiC).

[0021] Grooves 212 are formed in base plate 208. In some embodiments, grooves 212 are formed after base plate 208 is provided. In some embodiments, grooves 212 are formed when base plate 208 is formed. In some embodiments, grooves are not used, and therefore in those embodiments, grooves 212 are not formed.

[0022] The conductive base plate is bonded to the ceramic plate using a bonding material to form a joint (step 112) to form the ESC system. Figure 2B shows a partial cross-sectional view of base plate 208 bonded to ceramic plate 216 by bonding material joint 220 to form ESC system 200. In some embodiments, ceramic plate 216 comprises aluminum oxide or aluminum nitride. In some embodiments, joint 220 comprises silicone.

[0023] An elastic band is placed around joint 220 (step 116). Figure 2C shows a partial cross-sectional view of elastic band 224 placed around joint 220. In some embodiments, joint 220 comprises silicone. In some embodiments, elastic band 224 is an O-ring. In some embodiments, elastic band 224 is stretched to be placed around joint 220. Elastic band 224 then contracts to provide an interference fit around joint 220. Some embodiments may not use elastic band 224.

[0024] In some embodiments, elastic band 224 comprises a silicone rubber containing a conductive filler that has thermal and / or electrical conductivity. In some embodiments, joint 220 may also contain a conductive filler. If elastic band 224 and joint 220 have equal thermal and electrical conductivity, thermal and electric fields may pass uniformly through both elastic band 224 and joint 220, resulting in uniform heat and / or charge distribution across the substrate. As a result, the substrate may be processed more uniformly.

[0025] In some embodiments, the elastic band 224 may comprise at least one of silicone rubber, fluoroelastomer (FKM), perfluoroelastomer (FFKM, PFA), and fluorosilicone (FVMQ, FMQ, FPM, FSI). In some embodiments, the elastic band can be stretched to at least 25% of its original length. Thus, the ring-shaped elastic band can have a breaking elongation of at least 100%. Breaking elongation is a technical term defined as the ratio of the increased length at break divided by the original length, and is expressed as a percentage.

[0026] In some embodiments, a conductive filler may be mixed with the silicone rubber gel. In some embodiments, the conductive filler may be one or more of metal particles (e.g., copper, aluminum, or silver), carbon structures (e.g., graphene, nanoparticles, and nanotubes), and semiconductor materials (e.g., silicon or doped silicon).

[0027] A protective strip is applied around elastic band 224 and joint 220 (step 120). FIG. 2D shows a partial cross-sectional view of protective strip 228 applied around elastic band 224, which is applied around joint 220. FIG. 3 shows a top view of protective strip 228. In some embodiments, protective strip 228 includes at least one of an anodized strip, a ceramic tape strip, and a coated aluminum strip. In some embodiments, the anodized strip includes an aluminum strip with an anodized surface (anodized aluminum strip), such as aluminum ring 304 with an anodized outer surface 308. In some embodiments, the ceramic tape includes a ceramic strip. Ceramic tape is a general term for a flexible ceramic strip. In some embodiments, the ceramic tape includes an adhesive. In some embodiments, the ceramic tape does not include an adhesive. In some embodiments, the aluminum strip includes aluminum or an aluminum alloy coated with a plasma-resistant coating of at least one of alumina, yttria, and other ceramics. The coating may be applied before or after the aluminum strip is applied. In some embodiments, protective strip 228 has slits 312 that allow it to expand to fit around elastic band 224 and joint 220 and to provide a tight seal between protective strip 228, elastic band 224, and joint 220 over a wide range of temperatures. In some embodiments, slits 312 cut protective strip 228 into a cut ring. In some embodiments, aluminum ring 304 comprises aluminum mesh or an aluminum alloy mesh to form an anodized aluminum mesh or a coated aluminum mesh. In some embodiments, protective strip 228 comprises a ceramic mesh.

[0028] A ceramic spray coating is applied over the protective strip 228. FIG. 2E shows a partial cross-sectional view of the protective strip 228 after the ceramic coating has been applied to the outer surface of the protective strip 228. In some embodiments, the elastic band 224, the protective strip 228, and the ceramic coating 232 form an edge seal 240. In some embodiments, the ceramic spray coating is applied using plasma spraying, such as air plasma spraying. Air plasma spraying is a type of thermal spraying method in which a torch is formed by applying an electric potential between two electrodes, resulting in the ionization (plasma) of an accelerating gas. This type of torch can easily reach temperatures of several thousand degrees Celsius and can liquefy high-melting-point materials, such as ceramics. Ceramic particles are injected into a nozzle, melted, and accelerated toward the protective strip 228, causing the melt or plastic to coat the surface of the component and cool to form a solid, conformal coating. In some embodiments, the thermal spraying provides a layer thickness ranging from 10 μm to over 1000 μm. Various embodiments may use various thermal spray processes (e.g., at least one of a wire arc spray, air plasma spray, atmospheric plasma spray, suspension plasma spray, low pressure plasma spray, and very low pressure plasma spray). Other thermal spray processes may be cold spray, kinetic energy spray, and aerosol deposition. In some embodiments, the ceramic coating 232 is applied in-situ onto the protective strip 228 while the protective strip 228 is in place surrounding the joint 220.

[0029] The ESC system 200 is used to plasma process a substrate (step 128). FIG. 4 is a schematic diagram of an etch reactor incorporating the ESC system 200 shown in FIG. 2E. According to some embodiments, the etch reactor includes a plasma processing chamber system 400 having a gas distribution plate 406 providing gas inlets and the ESC system 200 within a processing chamber 408 surrounded by chamber walls 410. Within the processing chamber 408, a substrate 414 is positioned above the ESC system 200. The ESC system 200 includes a ceramic plate 216 bonded to a base plate 208 by a bond 220. An edge ring 411 surrounds the ESC system 200. An ESC temperature controller 450 is connected to a chiller 418. In some embodiments, the chiller 418 provides coolant to the flow passages 209 in the base plate 208 of the ESC system 200. Various embodiments may be used in a plasma processing chamber system 400 in which the ESC system 200 can operate in a temperature range where it can be cooled to temperatures below -40°C and heated to temperatures above 200°C.

[0030] In some embodiments, a radio frequency (RF) source 430 provides RF power to the lower electrode. In some embodiments, the lower electrode is a fixture plate 420 below the base plate 208 and is separated from the base plate 208 by an attached O-ring 424. In some embodiments, a 400 kilohertz (kHz) and 60 megahertz (MHz) power supply constitutes the RF source 430. In some embodiments, the upper electrode, which is the gas distribution plate 406, is grounded. In some embodiments, one generator is provided for each frequency. In other embodiments, other arrangements of RF sources and electrodes may be used. In some embodiments, a controller 435 is controllably connected to the RF source 430, the exhaust pump 428, and the gas source 432. An example of such a plasma processing chamber system 400 is the Flex® Etch system manufactured by Lam Research Corporation of Fremont, California. The processing chamber 408 may be a CCP (capacitively coupled plasma) reactor or an ICP (inductively coupled plasma) reactor. The processing chamber 408 may be a dielectric etch chamber or a conductive etch chamber. In some embodiments, the plasma processing chamber system 400 may be used for various plasma processes such as etching, deposition, and cleaning.

[0031] 5 shows a partial cross-sectional view of an ESC system 500 provided in another embodiment. In some embodiments, the ESC system 500 includes a base plate 208 having flow channels 209 for gas or liquid flow joined to a ceramic plate 216 by a joint 220. A protective strip 528 surrounds the joint 220. A ceramic coating 532 is applied to the protective strip 528. In some embodiments, no elastic band is used. In some embodiments, an edge seal 540 is formed by the protective strip 528 and the ceramic coating 532.

[0032] FIG. 6 is an enlarged cross-sectional view of elastic band 624, protective strip 628, and ceramic coating 632 used in some embodiments. Protective strip 628 has a C-shaped cross-section to provide a strong bond to elastic band 624. In some embodiments, edge seal 640 is formed by elastic band 624, protective strip 628, and ceramic coating 632. FIG. 7 is an enlarged cross-sectional view of protective strip 728 and ceramic coating 732 used in some embodiments. Surface 736 of protective strip 728 is grit blasted to roughen surface 736 before ceramic coating 732 is applied to surface 736 of protective strip 728. Roughened surface 736 provides a stronger bond between ceramic coating 732 and protective strip 728. In some embodiments, edge seal 740 is formed by protective strip 728 and ceramic coating 732.

[0033] In some embodiments, the ceramic coating may be at least one of alumina, yttria, and yttrium aluminum oxide (e.g., yttrium aluminum garnet (YAG)). In some embodiments, the protective strip comprises anodized aluminum mesh. In some embodiments, the anodized aluminum mesh is type III hard anodized. The type III anodizing process (also called hard anodizing or hardcoat anodizing) is an anodizing process in which aluminum is exposed to a sulfuric acid bath at a temperature of 0-3°C and high voltage (up to 100V) to form an oxide or "anodized" layer. In some embodiments, the base plate 208 is part of the pedestal.

[0034] Some embodiments using elastic band 224, protective strip 228, and ceramic coating 232 have been found to be more resistant to plasma erosion, thermal cycling degradation, and cracking than embodiments using elastic bands alone. Resistance to plasma erosion and cracking depends on the Tg (glass transition temperature) and stress corrosion cracking of the elastic band. Tg (glass transition temperature) is the temperature at which a polymer material becomes brittle. Some embodiments using elastic band 224, protective strip 228, and ceramic coating 232 have also been found to provide improved material integrity at the micro / nano level, providing uniform plasma resistance, manufacturing tolerances and variations, and hermeticity, compared to embodiments using elastic bands alone. Some embodiments using protective strip 528 and ceramic coating 532 have been found to be more resistant to plasma erosion and cracking than some embodiments using elastic band 224, protective strip 228, and ceramic coating 232. Additionally, some embodiments using the protective strip 528 and ceramic coating 532 have been found to provide improved material integrity at the micro / nano level over some embodiments using the elastic band 224, protective strip 228, and ceramic coating 232, providing uniform plasma resistance, manufacturing tolerances and variations, installation variability, and hermeticity.

[0035] FIG. 8A shows a partial cross-sectional view of a base plate 808 joined to a ceramic plate 816 by a joint 820 surrounded by a ring including a split ring 828 encased in a polymer coating 832. The protective strip comprises split ring 828. FIG. 8B shows a cross-sectional view of segments 828a, 828b, and 828c of split ring 828 encased in polymer coating 832. In some embodiments, polymer coating 832 provides a resilient coating. In some embodiments, polymer coating 832 is C-shaped, surrounding split ring 828, such that the length of polymer coating 832 forms a ring with joint 820 inside the ring formed by polymer coating 832. Groove 812 in base plate 808 is angled to facilitate placement of anodized ring 828 and polymer coating 832 in groove 812. The use of segmented anodized rings 828a, 828b, and 828c and polymer coating 832 provides a resilient ring that can be placed around joint 820. The ends of segments 828a, 828b, and 828c of segmented anodized ring 828 are beveled to reduce or eliminate radial line of sight. In some embodiments, ceramic plate 816 is polished where it contacts polymer coating 832. The polished surface provides an improved plasma seal between ceramic plate 816 and polymer coating 832. In some embodiments, the protective strip can be a single slit piece or two or more segments. In some embodiments, the ceramic coating is applied to the outside of the ring formed by polymer coating 832. Joint 820 is inside the ring formed by polymer coating 832.

[0036] In some embodiments, the edge seal has a lifespan equal to the lifespan of the ESC system. In some embodiments, the lifespan of the ESC system is at least 5000 RF hours. In contrast, elastic bands alone provide sufficient protection for the joint for 500-1500 RF hours. Because the elastic bands not only have a short lifespan but also do not provide sufficient protection, the joint is exposed to more plasma with the elastic band alone than with some embodiments. The extended protection provided by some embodiments reduces downtime and cost of ownership. Furthermore, because the joint's lifespan is extended to approximately the lifespan of the ESC system, the joint is considered a non-consumable item. Furthermore, reduced joint degradation improves process uniformity. Some embodiments provide joint protection over a temperature range of -80 to 80°C. The cut ring formed by the protective strip 528 provides sufficient elasticity to provide protection over a temperature range. The use of a cut ring or split ring allows the protective strip 528 to be made of a protective strip material that is easy to break (e.g., has a breaking elongation of less than 1%) and allows the protective strip to be wrapped around the joint. As a result, protective strip 528 does not form a complete ring that stretches when installed. In contrast, elastic band 224 is made of a material with a breaking elongation greater than 50%. Grooves used in some embodiments interrupt the plasma path to the joint, further reducing plasma erosion of the joint and further extending the life of the joint. In some embodiments, the joint forms an intricate pattern to facilitate various functions, such as cooling the ceramic plate. In some embodiments, the joint is formed using a deposition process that does not allow an edge seal to be installed until the joint is formed. In some embodiments, the material used to form joint 820 may be placed around protective strip 528 to hold it in place.

[0037] While this disclosure has been described in terms of several preferred embodiments, there are alterations, permutations, and various substitute equivalents that fall within the scope of this disclosure. There are many alternative ways of implementing the methods and apparatuses disclosed herein. Therefore, it is intended that the appended claims be construed to include all such alterations, permutations, and various substitute equivalents that fall within the true spirit and scope of the present disclosure. As used herein, the phrase "A, B, or C" should be construed to mean a logic using a non-exclusive logical "OR" ("A OR B OR C"), and not to mean "only one of A and B and C." Each step in a process may be optional and not required. Different embodiments may omit one or more steps or provide steps in a different order. Also, various embodiments may provide different steps simultaneously rather than sequentially.

Claims

1. 1. An electrostatic chuck system for use in a plasma processing chamber, comprising: A conductive base plate; a joint of a joining material, the joint being joined to the surface of the base plate at a first surface of the joint; a ceramic plate bonded to a second surface of the joint; a protective strip surrounding the joint and extending between the conductive base plate and the ceramic plate, the protective strip comprising at least one of an anodized strip, a ceramic tape strip, and a coated aluminum strip; An electrostatic chuck system comprising:

2. 10. The electrostatic chuck system of claim 1, further comprising: an electrostatic chuck system including a ceramic coating on an exterior of the protective strip, the protective strip and the ceramic coating forming an edge seal of the joint;

3. 3. The electrostatic chuck system of claim 2, further comprising: an elastic band between the joint and the protective strip, the elastic band being part of the edge seal;

4. 3. The electrostatic chuck system of claim 2, The electrostatic chuck system, wherein the ceramic coating comprises at least one of alumina, yttria, and yttrium aluminum oxide.

5. 5. The electrostatic chuck system of claim 4, The electrostatic chuck system, wherein the ceramic coating is a ceramic thermal spray coating.

6. 10. The electrostatic chuck system of claim 1, The electrostatic chuck system, wherein the protective strip is an anodized aluminum strip.

7. 10. The electrostatic chuck system of claim 1, further comprising: An electrostatic chuck system comprising: a groove in the conductive base plate; and a portion of the protective strip fitting into the groove.

8. 10. The electrostatic chuck system of claim 1, the protective strip is at least one of anodized aluminum mesh, coated aluminum mesh, and ceramic mesh.

9. 10. The electrostatic chuck system of claim 1, The electrostatic chuck system, wherein the protective strip is a cutting ring or a split ring.

10. 10. The electrostatic chuck system of claim 1, further comprising: The electrostatic chuck system includes a resilient coating on the protective strip.

11. 1. A method for providing an electrostatic chuck system, comprising: providing a conductive base plate; bonding the conductive base plate to a ceramic plate using a bonding material to form a bond; placing a protective strip around the periphery of the joint, the protective strip extending between the conductive base plate and the ceramic plate and including at least one of an anodized strip, a ceramic tape strip, and a coated aluminum strip; A method comprising:

12. 12. The method of claim 11 further comprising: applying a ceramic coating over the protective strip.

13. 13. The method of claim 12, further comprising: The method includes placing an elastic band around the joint before placing the protective strip around the joint.

14. 13. The method of claim 12, The method wherein the step of applying the ceramic coating is plasma spraying of the ceramic coating.

15. 13. The method of claim 12, The method, wherein the ceramic coating comprises at least one of alumina, yttria, and yttrium aluminum oxide.

16. 12. The method of claim 11, The method wherein the protective strip is an anodized aluminum strip.

17. 12. The method of claim 11 further comprising: The method includes forming a groove in the conductive base plate, a portion of the protective strip fitting into the groove.

18. 12. The method of claim 11, The method, wherein the protective strip is at least one of anodized aluminum mesh, ceramic mesh, and coated aluminum mesh.

19. 12. The method of claim 11, The method wherein the protective strip is a cut ring or a split ring.

20. 12. The method of claim 11 further comprising: providing an elastic coating on said protective strip.

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