Gas distribution assembly for semiconductor processing chamber with aluminum nitride layer

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. An aluminum nitride (AlN) containing thermal interface layer is between the back plate and the at least one electrode.

Description

GAS DISTRIBUTION ASSEMBLY FOR SEMICONDUCTOR PROCESSING CHAMBER WITH ALUMINUM NITRIDE LAYER CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority of U.S. Application No.63 / 574,772, filed April 4, 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. An aluminum nitride (AIN) containing thermal interface layer is between the back plate and the at least one electrode.

[0006] In another manifestation, a method for providing an assembly for use in a plasma processing system is provided. A back plate is provided for use in the plasma processing system. An electrode is provided on a first side of the back plate. An AIN containing thermal interface layer is provided between the back plate and the electrode.

[0007] In another manifestation, an assembly for use in a semiconductor processing chamber is provided comprising an aluminum nitride (AIN) containing thermal interface layer.

[0008] These and other features of the present disclosure will be described in more detailbelow in the detailed description and in conjunction with the following figures.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] 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:

[0010] FIG. 1 is a high level flow chart of an embodiment.

[0011] FIG. 2 is a schematic cross-sectional enlarged view of part of a gas distribution plate assembly according to an embodiment.

[0012] FIG. 3 is a schematic view of a plasma processing chamber that may be used in an embodiment.

[0013] 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

[0014] 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.

[0015] In some plasma processing chambers, a gas distribution assembly may comprise an aluminum containing backing plate and a silicon electrode. An anodized coating may be placed on a surface of the aluminum containing backing plate to provide electrical insulation between the aluminum containing backing plate and the silicon electrode. A thermal interface layer made of a material, such as silicone, may be between the anodized coating and the silicon electrode. In some embodiments, the thermal interface layer may be silicone free so that the thermal interface layer is more resistant to hydrogen fluoride (HF) degradation. For example, the silicone free thermal interface layer may comprises at least one of polyisoprene, butyl rubber, chloroprene, ethyl propylene diene, a fluorocarbon-based matrix (e.g., fluoroelastomer (FKM), perfluoroelastomer (FFKM), nitrile butadiene, saturated nitrile, styrene butadiene, polyurethane, an acrylic, or a polyimide. In other examples, any other suitable polymer can be used. Other examples of suitable polymers include natural rubber, polyolefins, epoxy-based matrices (e.g.,with or without additives to enable elastomeric behavior), and derivatives of polymers disclosed herein. It has been found that the anodized coating does not have a sufficient breakdown voltage to prevent arcing on the gas distribution plate. In addition, the difficulty in controlling the thickness of the anodized coating causes a large variation in the capacitance of the gas distribution plate making chamber matching more difficult. Also, the poor thermal conductivity of the anodization layer makes the control of the temperature more difficult.

[0016] According to some embodiments described herein, an aluminum nitride (AIN) containing layer is provided between the aluminum containing backplate and the silicon electrode. The AIN containing layer provides a higher breakdown voltage to prevent arcing and high thermal conductivity to increase heat transfer in order to allow improved cooling and more even temperature distribution.

[0017] To facilitate understanding, FIG. 1 is a high level flow chart of a process used in some embodiments. A thermally and electrically conductive back plate is provided (step 104). FIG. 2 is a schematic cross-sectional view of part of gas distribution assembly 200 provided in some embodiments. In some embodiments, the back plate 204 is a metal containing back plate. In some embodiments, the back plate 204 is aluminum containing, such as being pure aluminum or an aluminum alloy. In some embodiments, the metal back plate 204 is a gas distribution plate. A gas distribution plate is a plate with orifices for providing a gas through the gas distribution assembly 200 to the interior of a plasma processing chamber.

[0018] An aluminum nitride (AIN) containing thermal interface layer 212 is provided on the first side of the back plate 204 (step 108). In some embodiments, the AIN containing thermal interface layer 212 is applied by thermal spraying. In some embodiments, the AIN containing thermal interface layer 212 may be applied by other methods. However, thermal spraying provides a thermal interface layer 212 with a desired thickness. In some embodiments, the AIN containing thermal interface layer 212 has a thickness in the range of 100 microns and 1 mm. If the thermal interface layer 212 is too thick, like being greater than 1 mm, then the thermal interface layer 212 may have excessive stress build up. It has been found that a thermal interface layer 212 with a thickness of 1 mm provides sufficient electrical isolation to prevent breakdown. Thicker thermal interface layers 212 increase the expense of forming such thermal interface layers 212. In some embodiments, the AIN containing thermal interface layer 212 has a thickness in the range of 100 microns and 200 microns. Providing an AIN containing thermal interface layer 212 of such thicknesses provides sufficient electrical insulation while providing desired thermal conductivity. In some embodiments, the AIN containing thermal interface layer212 is at least 40% by weight AIN. In some embodiments, the AIN containing thermal interface layer 212 is at least 50% by weight AIN. In some embodiments, the AIN containing thermal interface layer 212 is at least 80% by weight AIN. In some embodiment, the AIN containing thermal interface layer 212 may contain other ceramic materials such as yttria, alumina, and yttria stabilized zirconia. In some embodiments, the AIN containing thermal interface layer 212 is applied directly on a bare surface of the back plate 204, instead of having an anodized layer between the back plate 204 and the AIN containing thermal interface layer 212. In some embodiments, grit blasting is provided to condition the surface of the back plate 204 before depositing the AIN containing thermal interface layer 212.

[0019] For thermal spraying, a torch is formed by applying an electrical potential between two electrodes, leading to the ionization of an accelerated gas (a plasma). Torches of this type can readily reach temperatures of thousands of degrees Celsius, liquefying high melting point materials such as ceramics. Ceramic particles are injected into the jet, melted, and then accelerated towards the back plate 204 so that the molten or plasticized material coats the surface of the back plate 204 and cools, forming a solid, conformal coating. In some embodiments, the thermal spraying provides a layer with a thickness in the range of 10 pm to more than 1000 pm.

[0020] In some embodiments, the AIN containing thermal interface layer 212 has a breakdown voltage of greater than 50 kilovolts per millimeter (kV / mm). In some embodiments, the ceramic layer has a breakdown voltage of greater than 200 volts. In some embodiments, the ceramic layer has a breakdown voltage of greater than 500 volts.

[0021] In some embodiments, the AIN containing thermal interface layer 212 is sealed (step 112) to provide a sealed AIN containing thermal interface layer 212. In some embodiments, the AIN containing thermal interface layer 212 has a porosity in the range of 1 volume% to 10 volume%. In some embodiments, a sealant, such as a polymeric sealant, like epoxy or phenolic, is used to seal pores in the AIN containing thermal interface layer 212. In some embodiments, the sealant penetrates at least 99% of the thickness of the AIN containing thermal interface layer 212. Such a sealant may help increase thermal conductivity while improving electrical breakdown resistance. In some embodiments, the sealant is cured into the AIN containing thermal interface layer 212. The illustrated AIN containing thermal interface layer 212 illustrates an AIN containing thermal interface layer with sealant baked in. In some embodiments, the AIN containing thermal interface layer 212 is not sealed.

[0022] In some embodiments, the AIN containing thermal interface layer 212 may be machined, such as polished, or have various parts removed to form electrical feedthroughs, or gas passages, or have loose surface features knocked off to prevent particles in the gas stream. If the AIN containing thermal interface layer 212 is polished the polishing provides a surface of the AIN containing thermal interface layer 212 with an Arithmetic Average Roughness (RA) roughness of less than 100 micro inches (2.54 micrometers (pm)), as measured by a profilometer. The reduced roughness improves thermal performance. The use of sealant with fine polishing provides an even smoother finish. The sealing of the pores also helps in maintaining mechanical integrity during the machining / polishing. In some embodiments, the AIN containing thermal interface layer is not machined.

[0023] In some embodiments, a contact layer 208 is placed on a surface of the AIN containing thermal interface layer 212 (step 116). In some embodiments, the contact layer 208 comprises a polymer or silicone with a thermally conductive filler, such as graphite. Graphite filler may increase the electrical conductivity of the contact layer 208 by as much as eight times. In some embodiments, the graphite filler is at least 40 weight% of the contact layer 208. In some embodiments, the graphite filler is 40 to 60 weight% of the contact layer 208. The contact layer 208 may be electrically conductive since the AIN containing thermal interface layer 212 provides sufficient electrical insulation. In some embodiments, when the contact layer 208 is electrically conductive, the contact layer 208 is segmented. In some embodiments, the contact layer 208 has a thickness of between 100 micrometers (microns) to 2 mm. In some embodiments, the contact layer 208 has a thickness of between 100 micrometers (microns) to 200 microns. The electrical insulation is increased by increasing the thickness of the contact layer 208. Increasing the electrical insulation of the contact layer 208 helps to reduce process shift. Having an electrically insulating layer is critical in applications where there is power delivery from the top end and helps prevent plasma lightup inside the gas holes.

[0024] An electrode 216 is provided on the first side of the AIN containing thermal interface layer 212 and / or contact layer 208 (step 124) so that the AIN containing thermal interface layer 212 and / or the contact layer 208 are between the electrode 216 and the back plate 204. In some embodiments, the electrode 216 is a silicon containing electrode, such as a pure silicon electrode. The electrode 216 comprises silicon and is electrically conductive. In some embodiments, the electrode 216 is doped silicon. The contact layer 208 helps to maintain contact between the AIN containing thermal interface layer 212 and the electrode 216 even when theremay be some movement between the electrode 216 and the AIN containing thermal interface layer 212 by bonding the AIN containing thermal interface layer 212 with the electrode 216.

[0025] In some embodiments, the electrode 216 is segmented. In such embodiments, the electrode 216 may have a first segment 216a and a second segment 216b. The first segment 216a may be electrically insulated from the second segment 216b by a quartz insulator ring 213. In some embodiments, the second segment 216b may form a ring around the first segment 216a. In some embodiments, the silicon containing electrode 216 has a plurality of segments forming a plurality of rings.

[0026] In some embodiments, an electrical feedthrough 220, is electrically connected between the electrode 216 and a tuning circuit 224. A gas source 228 is connected to a gas passage 232, forming orifices in the metal back plate 204, by a fluid connector 236.

[0027] Increased thermal conductivity of the AIN containing thermal interface layer 212 improves thermal transfer and allows for faster cooling of the silicon containing electrode 216. In addition, increased thermal conductivity allows for a more uniform temperature across the electrode 216.

[0028] The gas distribution assembly 200 is mounted in a plasma processing chamber (step 128). FIG. 3 is a schematic view of a processing chamber 300 providing a semiconductor processing chamber or plasma processing system, in an embodiment. In one or more embodiments, the processing chamber 300 comprises the gas distribution assembly 200 providing a gas inlet and an electrostatic chuck (ESC) 316, within a processing chamber 304, enclosed by a chamber wall 350. Within the processing chamber 304, a substrate 308 is positioned on top of the ESC 316 so that the ESC 316 is also a substrate support. The ESC 316 may provide a bias from an ESC power source 348. The gas source 228 is connected to the processing chamber 304 through the gas distribution assembly 200. An ESC temperature controller 351 is connected to the ESC 316 and provides temperature control of the ESC 316, allowing for the ESC 316 to be cooled to cryogenic temperatures. A radio frequency (RF) power source 330 provides RF power to the ESC 316. 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 330 and the ESC power source 348 to provide RF power at RF frequencies. A controller 335 is controllably connected to the RF power source 330, the ESC power source 348, an exhaust pump 320, and the gas source 310. A high flow liner 360 is a liner within the processing chamber 304, which confines gas from the gas source and has slots 362. The slots 362 maintain a controlled flow of gas to pass from the gas source 228 to the exhaustpump 320. 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 300 is a CCP (capacitively coupled plasma) reactor.

[0029] The tuning circuit 224 is connected to ground and allows the impedance between the silicon containing electrode 216 (FIG. 2) and ground the be adjusted, so that the silicon containing electrode 216 may have a variable voltage that is a function of the plasma power and the impedance from the tuning circuit 224. In some embodiments, the tuning circuit 224 comprises a variable resistor. In some embodiments, the tuning circuit 224 comprises a variable capacitor. The process chamber 300 is used to process a plurality of semiconductor wafers (step 132).

[0030] The use of a thermal spray coating of an AIN containing thermal interface layer 212 provides a layer with a high breakdown voltage, preventing arcing. In addition, the AIN thermal interface layer having a thickness of greater than 100 microns increases the capacitance of the back plate 204. In addition, AIN thermal interface layer 212 has a high thermal conductivity. The high thermal conductivity increases the cooling of the silicon containing electrode 216. Some embodiments increase thermal conductivity and decrease the thermal impedance while not significantly changing the electrical impedance. AIN has at least two orders of magnitude improved thermal conductivity over alumina. In some embodiments, thermal heat passes from the electrode 216 through the AIN containing thermal interface layer 212 to the back plate 204, 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 216.

[0031] In some embodiments, the AIN thermal interface layer is deposited on the electrode instead of the back plate. In such embodiments, the contact layer may be between the AIN thermal interface layer and the back plate. In various embodiments, the AIN thermal interface layer is deposited so that it will be between the electrode and the back plate. The contact layer is formed between the electrode and the metal back plate. The contact layer is either between the AIN thermal interface layer and the electrode or the AIN thermal interface layer and the back plate.

[0032] In some embodiments, the AIN thermal interface layer may be used on other parts of a plasma processing chamber. For example, the AIN thermal interface layer may be coated on a baseplate of an electrostatic chuck in order to provide both electrical insulation and thermal conductivity. In addition, an AIN thermal interface layer may be used to provide a heat sink and electrical insulation for an RF generator or some other high voltage supply. In someembodiments, the AIN thermal interface layer is deposited by one or more of aerosol deposition, glazing, sintering, and laser assisted deposition.

[0033] 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 removed or 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 an aluminum nitride (AIN) containing thermal interface layer between the back plate and the at least one electrode.

2. The gas distribution assembly, as recited in claim 1, wherein the AIN containing thermal interface layer has a thickness in a range of 100 microns to 1 mm.

3. The gas distribution assembly, as recited in claim 1, wherein the AIN containing thermal interface layer comprises a sealant.

4. The gas distribution assembly, as recited in claim 3, wherein the AIN containing thermal interface layer is porous and the sealant is throughout at least 99% of a thickness of the AIN containing thermal interface layer.

5. The gas distribution assembly, as recited in claim 1, further comprising a contact layer between the back plate and the electrode.

6. The gas distribution assembly, as recited in claim 5, wherein the contact layer comprises a thermally conductive filler in at least one of silicone and a polymer, wherein the filler forms at least 40 weight% of the contact layer.

7. The gas distribution assembly, as recited in claim 1, wherein the at least one electrode comprises a silicon electrode.

8. The gas distribution assembly, as recited in claim 1, where the back plate is at least one of aluminum and aluminum alloy.

9. A method for providing an assembly for use in a plasma processing system, comprising: providing a back plate for use in the plasma processing system; providing an electrode on a first side of the back plate; and providing an AIN containing thermal interface layer between the back plate and the electrode.

10. The method, as recited in claim 9, wherein the AIN containing thermal interface layer has a thickness in a range of 100 microns to 1 mm.

11. The method, as recited in claim 9, wherein the providing the AIN containing thermal interface layer comprises thermal spraying the AIN containing thermal interface layer.

12. The method, as recited in claim 9, wherein the AIN containing thermal interface layer is porous and further comprising sealing the AIN containing thermal interface layer with a sealant to form a sealed AIN containing thermal interface layer.

13. The method, as recited in claim 12, wherein the sealant is throughout at least 99% of a thickness of the AIN containing thermal interface layer.

14. The method, as recited in claim 12, further comprising machining the sealed AIN containing thermal interface layer.

15. The method, as recited in claim 12, further comprising bonding the sealed AIN containing thermal interface layer to either the electrode or the back plate.

16. The method, as recited in claim 9, wherein the back plate is an electrically conductive metal back plate.

17. An assembly for use in a semiconductor processing chamber, comprising an aluminum nitride (AIN) containing thermal interface layer.

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