An assembly for a semiconductor processing chamber with an aluminum nitride containing gasket

Abstract

A gas distribution assembly for use in a semiconductor processing chamber with an interior is provided. A back plate has a first side facing toward the interior of the semiconductor processing chamber and a second side away from the interior of the semiconductor processing chamber. At least one electrode is on the first side of the back plate. A gasket is between the back plate and the at least one electrode. The gasket comprises an aluminum nitride (AlN) containing core, a first contact layer on a first side of the AlN containing core, and a second contact layer on a second side of the AlN containing core opposite from the first side of the AlN containing core.

Description

AN ASSEMBLY FOR A SEMICONDUCTOR PROCESSING CHAMBER WITH AN ALUMINUM NITRIDE CONTAINING GASKET CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority of U.S. Application No. 63 / 650,676, filed May 22, 2024, which is incorporated herein by reference for all purposes.BACKGROUND

[0002] The present disclosure generally relates to the manufacturing of semiconductor devices. More specifically, the disclosure relates to plasma chamber components used in manufacturing semiconductor devices.

[0003] During semiconductor wafer processing, plasma processing chambers are used to process semiconductor devices. Plasma processing chambers are subjected to plasmas and voltages that may degrade components in the plasma processing chambers. Some plasma processing chambers use gas distribution assemblies to provide an electrode for plasma generation and also provide gas to the plasma processing chambers.

[0004] The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.SUMMARY

[0005] To achieve the foregoing and in accordance with the purpose of the present disclosure, a gas distribution assembly for use in a semiconductor processing chamber with an interior is provided. A back plate has a first side facing toward the interior of the semiconductor processing chamber and a second side away from the interior of the semiconductor processing chamber. At least one electrode is on the first side of the back plate. A gasket is between the back plate and the at least one electrode. The gasket comprises an aluminum nitride (AIN) containing core, a first contact layer on a first side of the AIN containing core, and a second contact layer on a second side of the AIN containing core opposite from the first side of the AIN containing core.

[0006] In another manifestation, a method for providing a gas distribution assembly for use in a plasma processing system is provided. A back plate is provided for use in the plasma processing system. At least one electrode is provided on a first side of the back plate. A gasket is provided between the back plate and the at least one electrode. The gasket is provided bysintering an aluminum nitride (AIN) containing powder to form an AIN containing foil, depositing a first contact layer on a first side of the AIN containing foil, and depositing a second contact layer on a second side of the AIN containing foil.

[0007] In another manifestation, an electrostatic chuck assembly is provided. An electrostatic chuck baseplate and an edge ring are provided. A gasket is provided between the electrostatic chuck baseplate and the edge ring. The gasket comprises an aluminum nitride (AIN) containing core, a first contact layer on a first side of the AIN containing core, and a second contact layer on a second side of the AIN containing core opposite from the first side of the AIN containing core.

[0008] In another manifestation, a gasket configured to be used in for use in a semiconductor processing chamber is provided. An aluminum nitride (AIN) containing core has a first contact layer on a first side of the AIN containing core. A second contact layer is on a second side of the AIN containing core opposite from the first side of the AIN containing core.

[0009] These and other features of the present disclosure will be described in more detail below in the detailed description and in conjunction with the following figures.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:

[0011] FIG. 1 is a high level flow chart of an embodiment.

[0012] FIG. 2A-C are schematic cross-sectional views of a gasket formed in some embodiments.

[0013] FIGS. 3A-B are schematic cross-sectional views of a gas distribution assembly used in some embodiments.

[0014] FIG. 4 is a schematic view of a plasma processing chamber that may be used in an embodiment.

[0015] FIGS. 5A-B are schematic cross-sectional views of an electrostatic chuck assembly and gasket used in some embodiments.

[0016] In the drawings, like reference numerals are sometimes used to designate like structural elements. It should also be appreciated that the depictions in the figures are diagrammatic and not to scale.DETAILED DESCRIPTION

[0017] The present disclosure will now be described in detail with reference to a few preferred embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent, however, to one skilled in the art, that the present disclosure may be practiced without some or all of these specific details. In other instances, well-known process steps and / or structures have not been described in detail in order to not unnecessarily obscure the present disclosure.

[0018] In some plasma processing chambers, a gas distribution assembly may comprise an aluminum containing backing plate and a silicon electrode. A gasket comprising an aluminum nitride (AIN) containing core, a first contact layer on a first side of the AIN containing core, and a second contact layer on a second side of the AIN containing core opposite from the first side of the AIN containing core is provided between the aluminum containing backplate and the silicon electrode. The AIN containing core provides a higher breakdown voltage to prevent arcing, high thermal conductivity to increase heat transfer in order to allow improved cooling, more even temperature distribution, and impedance for advanced impedance control.

[0019] To facilitate understanding, FIG. 1 is a high level flow chart of a process used in some embodiments. An AIN containing foil is provided (step 104). In some embodiments, the AIN containing foil is provided by sintering an AIN containing powder to form a sintered AIN foil. In some embodiments, the sintering process uses tape casting. FIG. 2A is a schematic cross- sectional view of part of an AIN containing foil 200 provided in some embodiments. In some embodiments, the AIN containing foil 200 has a thickness in the range of 50 pm (microns or micrometers) to 2 mm (millimeter) and a tolerance in the range of ±25 pm. In some embodiments, the AIN containing foil 200 has a thickness in the range of 100 pm to 1 mm and a tolerance in the range of ±25 pm. In some embodiments, the AIN containing foil 200 is at least 90 weight % of AIN. In some embodiments, the AIN containing foil 200 may further comprise yttria (Y2O3) that may be used as a sintering aid. In some embodiments, the thickness of the AIN containing foil 200 may be used to tune electrical impedance. Therefore, some embodiments provide improved advanced impedance control, while providing improved and more uniform thermal conductivity. The advanced impedance control allows different electrode elements to be tuned to ground to allow the current in each electrode element to be different while isolating every electrode element from ground. Some embodiments provide plasma uniformitymodulation using independent upper electrode segments, such as four inner electrode segments and one outer electrode segment, with adjustable impedance to ground. The adjustable impedance results in different current / voltage in each segment and therefore modulation of local plasma density. Even though the AIN containing foil 200 provides a desired thickness, the AIN containing foil 200 provides high thermal conductivity since AIN has a high thermal conductivity. Another advantage of the AIN containing foil is that AIN is erosion resistant to gases normally used in semiconductor processing.

[0020] A first contact layer is deposited on a first side of the AIN containing foil (step 108). A second contact layer is deposited on a second side of the AIN containing foil (step 112). In some embodiments, the first contact layer and second contact layer are deposited by lamination. FIG. 2B is a schematic cross-sectional view of part of the AIN containing foil 200 after the first contact layer 204 and the second contact layer 208 have been added to form a gasket 212, in some embodiments. In some embodiments, the first contact layer 204 and the second contact layer 208 each have a thickness in the range of 50 pm to 1000 pm and a tolerance of ±25 pm. In some embodiments, the first contact layer 204 and the second contact layer 208 each have a thickness in the range of 100 pm to 500 pm and a tolerance of ±25 pm. In some embodiments, the first contact layer 204 and the second contact layer 208 each comprise an elastomer or fluoroelastomer material. In some embodiments, the elastomer or fluoroelastomer material comprises a polymer, such as at least one of silicone, polyurethane, epoxy resin, polyimide, and fluoropolymer. In some embodiments, the first contact layer 204 and the second contact layer 208 further comprise a thermally conductive filler. In some embodiments, the thermally conductive filler is electrically conductive. In some embodiments, the electrically conductive filler comprises at least one of graphite and oriented carbon fiber. In some embodiments, electrically insulative thermal conductive filler may comprise at least one of aluminum oxide, and boron nitride. In some embodiments, the thermal conductive filler is 20 to 80 vol%. In some embodiments, at least one adhesive layer 214 is between the AIN containing foil 200 and at least one of the first contact layer 204 and the second contact layer 208. In some embodiments, the adhesive comprises at least one of acrylic based, butyl based, urethane based, silicone based, and polyimide based adhesive. In some embodiments, the adhesive forms a layer that has a thickness of less than 20 pm. In some embodiments, the adhesive forms a layer that has a thickness of less than 10 pm. The adhesive layer is kept thin, so it does not impact the thermal impedance of the entire stack. Some embodiments do not have an adhesive layer 214 since the first contact layer 204 and second contact layer 208 are able to bond to the AINcontaining foil 200 without the need to apply an additional adhesive. In some embodiments, the first contact layer 204 and the second contact layer 208 comprise an epoxy based thermoset adhesive sheet that becomes sticky under pressure, such as under a pressure of greater than 5 megapascals (MPa) at a temperature of greater than 150° C. In some embodiments, the first contact layer 204 and the second contact layer 208 comprise an epoxy based thermoset adhesive sheet that becomes sticky under pressure, such as under a pressure of greater than 10 megapascals (MPa) at a temperature of greater than 180° C. The resulting first contact layer 204 and the second contact layer 208 can be laminated to the sides of the AIN containing foil 200 without any additional adhesive. The first contact layer 204 and the second contact layer 208 may further comprise a thermally conductive filler to provide a thermal conductivity of 10 Watts (W) / meter-Kelvin (mK) and therefore help in reducing the overall thermal impedance of the stack.

[0021] In some embodiments, the gasket is optionally further machined (step 116). In some embodiments, the further machining may comprise cutting the gasket holes and other critical features in the gasket. In some embodiments, a die cut, waterjet, or a laser cutter is used to drill holes. FIG. 2C is a schematic cross-sectional view of the gasket 212 after holes 216a, and 216b have been drilled in the gasket. In some embodiments, the gasket holes have a cross- sectional area that is at least 5% larger than associate holes in the electrode. At least one of the holes 216a may be used to provide a gas passage through the gasket 212. At least one of the holes 216b may be used to provide an electrical passage through the gasket 212. In some embodiments, the gasket is machined in a green state before sintering or machined after sintering.

[0022] The gasket 212 is placed between a back plate of a gas distribution assembly and an electrode. FIG. 3A is a cross-sectional schematic view of part of a gas distribution assembly 300, comprising a back plate 304 and an electrode 316 with the gasket 212 between the back plate 304 and the electrode 316, used in some embodiments. In some embodiments, the back plate 304 is a metal baseplate. The gasket 212 is on a first side of the back plate 304, where the first side of the back plate 304 faces the interior of a plasma processing chamber. The second side of the back plate 304 is opposite the first side of the back plate 304. In some embodiments, the electrode 316 is a silicon containing electrode, such as a pure silicon electrode. The electrode 316 comprises silicon and is electrically conductive. In some embodiments, the electrode 316 is doped silicon. The gasket 212 helps to maintain thermal contact between the back plate 304 andthe electrode 316 even when there may be some movement between the electrode 316 and the back plate 304.

[0023] In some embodiments, an electrical feedthrough 320 passes through a hole 216b providing an electrical passage and is electrically connected between the electrode 316 and a tuning circuit 324. In some embodiments, a gas source 328 is connected by a fluid connector 336 to orifices 332 in the metal gas distribution back plate 304. The orifices provide gas through the gas passage holes 216a to a plasma chamber through the electrode 316. In some embodiments, the gasket 212 has the same length and width as the electrode 316 and / or the back plate 304. In some embodiments, the gasket 212 may be smaller than the electrode 316, where more than one gasket is used.

[0024] The increased thermal conductivity of the AIN containing foil 200 and the thermally conductive filler provided in the first contact layer 204 and the second contact layer 208 improved thermal transfer between the electrode 316 and the back plate 304, allowing for faster cooling of the electrode 216. In addition, increased thermal conductivity allows for a more uniform temperature across the electrode 316. In addition, forming the first contact layer 204 and the second contact layer 208 from an elastomer or fluoroelastomer, such as at least one of a fluoropolymer, epoxy, polyimide, silicone, and polyurethane increases the adhesion of the first contact layer 204 and the second contact layer 208 with the AIN containing foil 200, resulting in improved thermal transfer. In some embodiments, polyurethane, epoxy, acrylic, and fluoroelastomers (FKM / FFKM) are more erosion resistant to gases used in plasma processing, such as hydrogen fluoride (HF), than silicone. As a result, some embodiments use a silicone free first contact layer 204 and second contact layer 208, instead being made of a polyurethanes - based, epoxy-based, acrylic-based, or fluoroelastomer-based material.

[0025] FIG. 3B is a schematic cross-sectional view of a gas distribution assembly 300 used in some embodiments. In some embodiments, a cooling plate 340 including cooling channels 344 is arranged adjacent to a heating plate 348 including one or more resistive heaters 352. Thermal interface layers 356 are arranged between the cooling plate 340 and the heating plate 348 and between the heating plate 348 and a gas distribution back plate 304. The gas distribution back plate 304 may include one or more gas orifices 332, shown in FIG. 3A. The gasket 212 is between the gas distribution back plate 304 and the electrode 316.

[0026] The gas distribution assembly 300 is mounted in a plasma processing chamber(step 128). FIG. 4 is a schematic view of a processing chamber 400 providing a semiconductor processing chamber or plasma processing system, in an embodiment. In some embodiments, theprocessing chamber 400 comprises the gas distribution assembly 300 and an electrostatic chuck (ESC) 416, within a processing chamber 404, enclosed by a chamber wall 450. Within the processing chamber 404, a substrate 408 is positioned on top of the ESC 416 so that the ESC 416 is also a substrate support. An edge ring 418 surrounds the substrate 408. The ESC 416 may provide a bias from an ESC power source 448. The gas source 328 is connected to the processing chamber 404 through the gas distribution assembly 300. An ESC temperature controller 451 is connected to the ESC 416 and provides temperature control of the ESC 416, allowing for the ESC 416 to be cooled to cryogenic temperatures. A radio frequency (RF) power source 430 provides RF power to the ESC 416. In a preferred embodiment, 400 kilohertz (kHz), 13.56 megahertz (MHz), 1 MHz, 2 MHz, 60 MHz, and / or optionally, 27 MHz power sources make up the RF power source 430 and the ESC power source 448 to provide RF power at RF frequencies. A controller 435 is controllably connected to the RF power source 430, the ESC power source 448, an exhaust pump 420, and the gas source 410. A high flow liner 460 is a liner within the processing chamber 404, which confines gas from the gas source and has slots 462. The slots 462 maintain a controlled flow of gas to pass from the gas source 328 to the exhaust pump 420. An example of such a processing chamber is the Flex® etch system manufactured by Lam Research Corporation of Fremont, CA. In some embodiments, the process chamber 400 is a CCP (capacitively coupled plasma) reactor.

[0027] The tuning circuit 324 is connected to ground and allows the impedance between the silicon containing electrode 316 (FIG. 3) and ground the be adjusted, so that the silicon containing electrode 316 may have a variable voltage that is a function of the plasma power and the impedance from the tuning circuit 324. In some embodiments, the tuning circuit 324 comprises a variable resistor. In some embodiments, the tuning circuit 324 comprises a variable capacitor. The process chamber 400 is used to process a plurality of semiconductor wafers (step 132).

[0028] The use of an AIN containing foil 200 within a gasket 212 provides a high breakdown voltage, preventing arcing. In addition, the AIN containing foil 200 having a thickness of less than 1 mm increases the capacitance of the gas distribution back plate 304. The thinner the AIN containing foil 200 the greater the resulting capacitance. Therefore, the thickness of the AIN containing foil 200 can be used to provide a desired capacitance of the gasket 212. In addition, the AIN containing foil 200 has a high thermal conductivity. The high thermal conductivity increases the cooling of the electrode 316. Some embodiments increase thermal conductivity and decrease the thermal impedance while not significantly changing theelectrical impedance. AIN has at least two orders of magnitude improved thermal conductivity over alumina. In some embodiments, thermal heat passes from the electrode 316 through the gasket 212 to the back plate 304, and then to a heat sink or cooling system. The improved thermal conductivity allows for a more uniform temperature across different parts or segments of the electrode 316.

[0029] In some embodiments, the gasket may be used on other parts of a plasma processing chamber 400. For example, the gasket may be placed between the ESC 416, comprising an ESC baseplate, and the edge ring 418. FIG. 5 A is an enlarged cross-sectional schematic view of part of electrostatic chuck assembly 560 comprising an ESC 416, an edge ring 418, and a gasket 512 in between the ESC 416 and the edge ring 418. The ESC 416 comprises an ESC baseplate 502 and a ceramic plate 503. The gasket 512 comprises an AIN containing foil 500, a first contact layer 504, and a second contact layer 508. FIG. 5B is a top view of a gasket 512 that would be used in the processing chamber 400, shown in FIG. 4, in some embodiments. The first contact layer 504 is on top of the gasket 512.

[0030] In some embodiments, at least one of the first contact layer 504 and the second contact layer 508 may be electrically conductive, since the AIN containing foil 500 provides sufficient electrical resistance preventing breakdown. The gasket 512 allows the edge ring 418 to be electrically isolated and decoupled from the ESC baseplate 502. In some embodiments, the AIN containing foil 500 has a thickness in the range of 100 pm to 1 mm. In some embodiments, the AIN containing foil has a greater thickness than the thickness of the AIN containing foil 200, since the purpose of the gasket 512 for the ESC 416 is used to provide a high impedance between the ESC baseplate 502 and the edge ring 418 while providing high thermal conductivity.

[0031] While this disclosure has been described in terms of several preferred embodiments, there are alterations, modifications, permutations, and various substitute equivalents, that fall within the scope of this disclosure. It should also be noted that there are many alternative ways of implementing the methods and apparatuses of the present disclosure. It is therefore intended that the following appended claims be interpreted as including all such alterations, modifications, permutations, and various substitute equivalents as 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 logical (“A OR B OR C”), using a non-exclusive logical “OR,” and should not be construed to mean ‘only one of A or B or C. Each step within a process may be an optional step and is not required. Different embodiments may have one or more steps removedor may provide steps in a different order. In addition, various embodiments may provide different steps simultaneously instead of sequentially.

Claims

CLAIMSWhat is claimed is:

1. A gas distribution assembly for use in a semiconductor processing chamber with an interior, comprising: a back plate with a first side facing toward the interior of the semiconductor processing chamber and a second side away from the interior of the semiconductor processing chamber; at least one electrode on the first side of the back plate; and a gasket between the back plate and the at least one electrode, the gasket comprising: an aluminum nitride (AIN) containing core; a first contact layer on a first side of the AIN containing core; and a second contact layer on a second side of the AIN containing core opposite from the first side of the AIN containing core.

2. The gas distribution assembly, as recited in claim 1, wherein the AIN containing core comprises a sintered AIN foil.

3. The gas distribution assembly, as recited in claim 1, wherein the AIN containing core is at least 90 weight % of AIN.

4. The gas distribution assembly, as recited in claim 1, wherein the first contact layer and the second contact layer comprise a polymer comprising at least one of silicone, epoxy resin, polyimide, fluoropolymer, and polyurethane.

5. The gas distribution assembly, as recited in claim 4, wherein at least one of the first contact layer and the second contact layer further comprises a thermally conductive filler.

6. The gas distribution assembly, as recited in claim 5, wherein the thermally conductive filler is electrically conductive.

7. The gas distribution assembly, as recited in claim 5, wherein the thermally conductive filler comprises at least one of graphite, aluminum oxide, oriented carbon fiber, and boron nitride.

8. The gas distribution assembly, as recited in claim 1, further comprising an adhesive between the AIN containing core and at least one of the first contact layer and second contact layer for bonding the AIN containing core to the at least one of the first contact layer and the second contact layer.

9. A gasket configured to be used in a gas distribution assembly according to claim 1 comprising: an aluminum nitride (AIN) containing core; a first contact layer on a first side of the AIN containing core; and a second contact layer on a second side of the AIN containing core opposite from the first side of the AIN containing core.

10. A method for providing a gas distribution assembly for use in a plasma processing system, providing back plate for use in the plasma processing system; providing at least one electrode on a first side of the back plate; and providing a gasket between the back plate and the at least one electrode, wherein the providing a gasket, comprises: sintering an aluminum nitride (AIN) containing powder to form an AIN containing foil; depositing a first contact layer on a first side of the AIN containing foil; and depositing a second contact layer on a second side of the AIN containing foil.

11. The method, as recited in claim 10, wherein the providing the gasket further comprises machining the gasket.

12. The method, as recited in claim 10, wherein the AIN containing foil is at least 90 weight % of AIN.

13. The method, as recited in claim 10, wherein the first contact layer and the second contact layer comprise a polymer comprising at least one of silicone, epoxy, polyimide, fluoropolymer, and polyurethane.

14. The method, as recited in claim 13, wherein at least one of the first contact layer and the second contact layer further comprises a thermally conductive filler.

15. The method, as recited in claim 10, further comprising an adhesive between the AIN containing foil and at least one of the first contact layer and second contact layer for bonding the AIN containing foil to the at least one of the first contact layer and the second contact layer.

16. An electrostatic chuck assembly, comprising: an electrostatic chuck baseplate; an edge ring; and a gasket between the electrostatic chuck baseplate and the edge ring, the gasket comprising:an aluminum nitride (AIN) containing core; a first contact layer on a first side of the AIN containing core; and a second contact layer on a second side of the AIN containing core opposite from the first side of the AIN containing core.

17. The electrostatic chuck assembly, as recited in claim 16, wherein the AIN containing core comprises a sintered AIN foil.

18. The electrostatic chuck assembly, as recited in claim 16, wherein the AIN containing core is at least 90 weight % of AIN.

19. The electrostatic chuck assembly, as recited in claim 16, wherein the first contact layer and the second contact layer comprise a polymer comprising at least one of silicone, epoxy, polyimide, fluoropolymer, and polyurethane.

20. The electrostatic chuck assembly, as recited in claim 19, wherein at least one of the first contact layer and the second contact layer further comprises a thermally conductive filler.

21. The electrostatic chuck assembly, as recited in claim 20, wherein the thermally conductive filler is electrically conductive.

22. The electrostatic chuck assembly, as recited in claim 20, wherein the thermally conductive filler comprises at least one of graphite, aluminum oxide, oriented carbon fiber, and boron nitride.

23. The electrostatic chuck assembly, as recited in claim 16, further comprising an adhesive between the AIN containing core and at least one of the first contact layer and second contact layer for bonding the AIN containing core to the at least one of the first contact layer and the second contact layer.

24. A gasket configured to be used in a electrostatic chuck according to claim 16 comprising: an aluminum nitride (AIN) containing core; a first contact layer on a first side of the AIN containing core; and a second contact layer on a second side of the AIN containing core opposite from the first side of the AIN containing core.

25. A gasket configured to be used in for use in a semiconductor processing chamber, comprising: an aluminum nitride (AIN) containing core; a first contact layer on a first side of the AIN containing core; and a second contact layer on a second side of the AIN containing core opposite fromthe first side of the AIN containing core.

26. The gasket, as recited in claim 25, wherein the AIN containing core comprises a sintered AIN foil.

27. The gasket, as recited in claim 25, wherein the AIN containing core is at least 90 weight % of AIN.

28. The gasket, as recited in claim 25, wherein the first contact layer and the second contact layer comprise a polymer comprising at least one of silicone, epoxy resin, polyimide, fluoropolymer, and polyurethane.

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