WO2022055813A1

WO2022055813A1 - Spinel coating for plasma processing chamber components

Info

Publication number: WO2022055813A1
Application number: PCT/US2021/049089
Authority: WO
Inventors: John Daugherty; David Joseph WETZEL; Lin Xu; Eric A. Pape; Robin Koshy; Douglas DETERT; Satish Srinivasan
Original assignee: Lam Research Corporation
Priority date: 2020-09-10
Filing date: 2021-09-03
Publication date: 2022-03-17
Also published as: TW202230437A

Abstract

A component for use in a plasma processing chamber system is provided. A component body has a plasma facing surface. A coating is over at least the plasma facing surface, wherein the coating comprises spinel, wherein the spinel consisting essential of MgAl2O4.

Description

SPINEL COATING FOR PLASMA PROCESSING CHAMBER COMPONENTS CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority of U.S. Application No. 63/076,772, filed September 10, 2020, which is incorporated herein by reference for all purposes.

BACKGROUND

[0002] The background description provided here is for the purpose of generally presenting the context of the disclosure. The information 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.

[0003] 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.

[0004] During semiconductor wafer processing, plasma processing chambers are used to process semiconductor devices. Plasma processing chambers are subjected to plasmas. The plasmas may degrade the component. Coatings may be placed over plasma facing surfaces of components of plasma processing chambers to protect the surfaces.

[0005] Some of the coatings may be applied using a plasma spray. One type of coating that may be used is aluminum oxide or alumina (AI2O3). It has been found that alumina does not provide enough etch resistance. Another type of coating that might be used is yttrium oxide or yttria (Y2O3). It has been found that high purity yttria coatings are expensive to manufacture due to material cost and/or processing costs. Although yttria is more sputter resistant than alumina, yttria is more susceptible to spontaneous fluorination reaction or conversion process than alumina. This fluorine reaction or conversion process may be undesirable and lead to deleterious behavior.

SUMMARY

[0006] To achieve the foregoing and in accordance with the purpose of the present disclosure, a component for use in a plasma processing chamber system is provided. A component body has a plasma facing surface. A coating is over at least the plasma facing surface, wherein the coating comprises spinel, wherein the spinel consisting essential of MgAUCU.

[0007] In another manifestation, a method for forming a coating over a plasma facing surface of a component body of a component for use in a plasma processing chamber system is provided. A coating comprising spinel is deposited over at least the plasma facing surface of the component body, wherein the spinel consists essential of MgAUCU. [0008] 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

[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] FIGS. 2A-B are schematic views of a component processed according to an embodiment.

[0012] FIG. 3 is a detailed flow chart of a process of coating a surface in an embodiment.

[0013] FIG. 4 is a detailed flow chart of a process of coating a surface in another embodiment.

[0014] FIG. 5 is a schematic view of a plasma processing chamber that may be used in an embodiment.

DETAILED DESCRIPTION

[0015] 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.

[0016] In the manufacturing of semiconductor devices, a plasma processing chamber may be used. The plasma processing chamber may have various components that are exposed to plasma during plasma processing. Such components may be aluminum to provide electrical and thermal characteristics that are useful in maintaining the plasma. Aluminum also allows a reduction in weight and cost. Other components may have a dielectric body. Such components may be made of alumina. Ceramic alumina may be used for items such as dielectric inductive power windows or gas injectors.

[0017] Such components may be chemically etched by fluorine containing plasma, oxygen containing plasma, or chlorine containing plasma. In addition, the components may be chemically converted or reacted, resulting in surface or bulk changes in plasma exposed areas of the component. The erosion from sputtering may change the shape of the component disrupting the uniformity of the plasma process or may generate particles that become contaminants. A coating may be placed on a plasma facing surface of the aluminum to provide protection from erosion.

[0018] Alumina is used as a protective coating. Alumina has some plasma etch resistance. More etch-resistant coatings would provide additional protection to such plasma chamber components. Coatings such as yttria and yttrium aluminum oxide are also used as coatings in some plasma processing chambers. Yttria is more resistant to sputtering than alumina. However, such yttria coatings do not meet the particle requirements at next-generation nodes. Instead, when exposed to fluorine containing plasma, fluorine is absorbed into the yttria coating, so that the yttria coating is fluorinated converting yttria (Y2O3) into YF₃ or various forms of Y_xO_yF_z compounds that may be stable or metastable. These compounds create lattice and crystal defects with various intrinsic property defects, resulting in particles that dislodge from the yttria coating and become contaminants. The particles make it more difficult to meet requirements for reduced contaminants. In addition, due to the preferred fluorine conversion reaction of yttria, as an example, some thermal spray yttria coatings may take an undesirably long period of time to reach a chemical steady state when exposed to a fluorine containing plasma environment.

[0019] Various embodiments provide a coating of spinel consisting essentially of MgAhC . Such a coating provides a high resistance to fluorine containing plasma, oxygen containing plasma, and sputtering. To facilitate understanding, FIG. 1 is a high level flow chart of a process used in an embodiment. A component body is provided (step 104). FIG. 2A is a schematic cross-sectional view of part of a component body 204 of a component 200 that is used in an embodiment. In this example, the component 200 is a ceramic alumina dielectric inductive power window. The component body 204 has a surface 208. In this embodiment, the surface 208 is a plasma facing surface. A plasma facing surface is a surface that will face towards a plasma when the component body 204 is used in a plasma processing chamber. In this embodiment, a layer 210 is formed over the plasma facing surface. In some embodiments, one or more layers may be over the plasma facing surface. In other embodiments, there is not any layer over the plasma facing surface.

[0020] Next, the surface 208 and the layer 210 are coated by spraying a surface 208 and layer 210 of the component body 204 with spray comprising spinel consisting essential of MgAhO^ FIG. 3 is a more detailed flow chart of a method of depositing a coating in an embodiment. A cubic spinel structure is formed (step 304). In this embodiment, a powder mixture of magnesium oxide (MgO) powder and aluminum oxide (AI2O3) powder is formed into a shape and sintered to form a structure comprising spinel consisting essentially of MgAhO^ The spinel consisting essentially of MgA^C means that the spinel does not include another type of spinel such as (Mg,Fe)(Al,Cr)2O4. The spinel crystallizes in a cubic crystal system, where the unit cell has the shape of a cube. The structure may be monocrystalline or polycrystalline.

[0021] The structure is granulated (step 308). A machine may be used to crush the structure into a powder. The powder is a spinel powder. The powder has particle sizes between 1 micron (pm) to 150 pm for atmospheric plasma spraying (APS) and 30 nanometers (nm) to 5 mm for suspension plasma spraying.

[0022] The particles of granulated cubic structure spinel are sprayed over at least the plasma facing surface 208 of the component body 204 (step 312). The spinel may be sprayed over other surfaces of the component body 204. In this embodiment, the granulated particles are thermal sprayed on at least the plasma facing surface 208 and the layer 210. In this embodiment, the thermal spray is an atmospheric plasma spray.

[0023] Atmospheric plasma spraying is a type of thermal spraying in which a plasma plume is formed by applying an electrical potential between two electrodes, leading to ionization of an accelerated gas (a plasma). Plasma plumes of this type can readily provide temperatures of thousands of degrees Celsius, liquefying high melting point materials such as ceramics. A carrier gas is pushed through an arc cavity and out through a nozzle. In the cavity, a cathode and anode comprise parts of the arc cavity. The cathode and anode are maintained at a large DC bias voltage, until the carrier gas begins to ionize, forming the plasma. The hot, ionized gas is then pushed out through the nozzle forming the plasma plume. Into the chamber near the nozzle is injected fluidized granulated particles of spinel. The granulated particles of spinel are heated by the hot, ionized gas in the plasma plume such that the temperature exceeds the melting temperature of the granulated particles of spinel. The jet of plasma and particles of spinel is then aimed at the layer 210 and surface 208 of the component body 204. The particles of spinel impact the layer 210, and are flatten and cooled to form a coating. These processes are distinct from vapor deposition processes that use vaporized material instead of molten material. FIG. 2B is a schematic cross-sectional view of the component body 204 after the surface 208 and layer 210 are coated by spraying the layer 210 of the component body 204 with spray formed from a thermal spray of the granulated spinel forming a coating. The coating 212 is over the surface 208.

[0024] In this embodiment, the coating 212 has a thickness of 3 pm to 1000 pm applied by an atmospheric plasma spraying. More specifically, the coating has a thickness of 50 pm to 125 pm. In other embodiments, a coating applied by suspension plasma spraying has a thickness of 3 |im to 100 |im. More specifically, the coating has a thickness of between 5 |im to 50 |im. The coating has a porosity of no more than 20%. More specifically, the coating has a porosity of no more than 8%. More specifically, the coating has a porosity of between 0.5% to 4%. In the specification and claims, porosity is measured according to the standard test method of ASTM E2109-01(2014).

[0025] In an embodiment, the coating 212 consists essentially of a multicrystalline cubic structure spinel and at least one of amorphous magnesium aluminum oxide, aluminum oxide, and magnesium oxide. For example, such a coating 212 may comprise at least 60% by weight amorphous magnesium aluminum oxide. In an embodiment, the coating 212 may be a single crystal. In the specification and claims, crystalline may be either a single crystal or multicrystalline. In an embodiment, the coating 212 is at least 50% by weight crystalline cubic structure spinel. Such an embodiment may further comprise at least one of yttria, aluminum oxide, magnesium oxide, and amorphous magnesium aluminum oxide. In another embodiment, the coating 212 is at least 90% by weight crystalline cubic structure spinel. In such an embodiment, the coating 212 may also have small amounts of MgO and/or AI2O3. In an embodiment, the coating 212 is pure crystalline cubic structure spinel.

[0026] In this embodiment, the component body 204 is of a dielectric material of alumina. In other embodiments, the component body 204 is of an electrically conductive metal, such as aluminum. The aluminum component body may be of an aluminum alloy, such as aluminum 6061. Such an aluminum alloy is at least 95% pure aluminum. In some embodiments, the layer 210 may be one or more layers of an anodization layer or other layers. In other embodiments, there is not any layer and the coating 212 is directly on the surface 208.

[0027] The component body 204 is mounted in a plasma processing chamber (step 112). In this example, the component body 204 is mounted in the plasma processing chamber as a dielectric inductive power window. The plasma processing chamber is used to process a substrate (step 116), where a plasma is created within the chamber to process a substrate, such as etching the substrate, and the coating 212 is exposed to the plasma. The coating 212 provides increased etch resistance to protect the surface 208 of the component body 204.

[0028] In other embodiments, other types of thermal spraying processes may be used. For example, the thermal spraying may be at least one of a suspension plasma spraying, a vacuum plasma spray, a high velocity oxygen fuel spray, and an atmospheric plasma spraying.

[0029] Other embodiments may use other methods for depositing a coating on the plasma facing surface 208 (step 108). FIG. 4 is a more detailed flow chart of a method of depositing a coating in another embodiment. In this embodiment, a powder mixture comprising MgO powder and AI2O3 powder is provided. The powder mixture is thermal sprayed onto the plasma facing surface 208 to form a coating 212. In this embodiment, the component body 204 is aluminum and forms part of a liner. In this embodiment, the thermal spraying is by suspension plasma spraying. Suspension plasma spraying is a type of thermal spraying in which a plasma plume is formed by applying an electrical potential between two electrodes, leading to ionization of an accelerated gas (a plasma). Plasma plumes of this type can readily provide temperatures of thousands of degrees Celsius, liquifying high melting point materials such as ceramics. A liquid suspension of solid particles to be deposited in a liquid medium is fed to the plasma plume. The plasma plume melts the solid particles of the desired material. A carrier gas is pushed through an arc cavity and out through a nozzle. In the cavity, a cathode and anode comprise parts of the arc cavity and are maintained at a large direct current (DC) bias voltage, until the carrier gas begins to ionize, forming the plasma. The hot, ionized gas is then pushed out through the nozzle, forming the plasma plume. Fluidized ceramic particles, less than 10 microns in size, are injected into the chamber near the nozzle. These particles are heated by the hot, ionized gas in the plasma plume such that they exceed the melting temperature of the ceramic. The jet of plasma and melted ceramic are then aimed at the component body 204. The particles impact the component body 204 and are flattened and cooled to form a coating.

[0030] It has been found that a correct ratio range of MgO powder to AI2O3 powder in the powder mixture under the proper thermal spraying conditions will cause the deposited coating to form crystalline spinel of magnesium aluminum oxide. In some embodiments, the ratio of MgO powder to AI2O3 powder is in the range between 1:2 and 2:1. Particle size may be important in forming crystalline spinel. In various embodiments, the particle size is in the range of 10 pm to 50 pm, with D10/D90 at about +/-60% of average. In addition, it is important that the particle size of the MgO powder be approximately equal to the particle size of the AI2O3 powder. In some embodiments, the ratio of the particle sizes of the MgO powder to the particle sizes of the AI2O3 powder is in the range of 3:2 to 2:3. The melting points of MgO and AI2O3 are sufficiently close to allow the formation of crystalline spinel. To prevent oxidation, argon (Ar) shielding may be used to reduce oxidation.

[0031] Other embodiments may use other compounds to provide magnesium, aluminum, and oxygen used to form the coating 212. Other embodiments may use other methods for depositing the coating. For example, aerosol deposition, chemical vapor deposition, sintering, and physical vapor deposition may be used for depositing the coating. The coating may be deposited by atomic layer deposition. However, atomic layer deposition may deposit too slowly and also might not be able to deposit the desired crystalline coating.

[0032] FIG. 5 schematically illustrates an example of a plasma processing chamber system 500 that may be used in an embodiment. The plasma processing chamber system 500 includes a plasma reactor 502 having a plasma processing confinement chamber 504 therein. A plasma power supply 506, tuned by a plasma matching network 508, supplies power to a transformer coupled plasma (TCP) coil 510 located near a dielectric inductive power window 512 to create a plasma 514 in the plasma processing confinement chamber 504 by providing an inductively coupled power. A pinnacle 572 extends from a chamber wall 576 of the plasma processing confinement chamber 504 to the dielectric inductive power window 512 forming a pinnacle ring. The pinnacle 572 is angled with respect to the chamber wall 576 and the dielectric inductive power window 512, such that the interior angle between the pinnacle 572 and the chamber wall 576 and the interior angle between the pinnacle 572 and the dielectric inductive power window 512 are each greater than 90° and less than 180°. The pinnacle 572 provides an angled ring near the top of the plasma processing confinement chamber 504, as shown. The TCP coil (upper power source) 510 may be configured to produce a uniform diffusion profile within the plasma processing confinement chamber 504. For example, the TCP coil 510 may be configured to generate a toroidal power distribution in the plasma 514. The dielectric inductive power window 512 is provided to separate the TCP coil 510 from the plasma processing confinement chamber 504 while allowing energy to pass from the TCP coil 510 to the plasma processing confinement chamber 504. A wafer bias voltage power supply 516 tuned by a bias matching network 518 provides power to an electrode 520 to set the bias voltage on the substrate 566. The substrate 566 is supported by the electrode 520. A controller 524 controls the plasma power supply 506 and the wafer bias voltage power supply 516.

[0033] The plasma power supply 506 and the wafer bias voltage power supply 516 may be configured to operate at specific radio frequencies such as, for example, 13.56 megahertz (MHz), 27 MHz, 2 MHz, 60 MHz, 400 kilohertz (kHz), 2.54 gigahertz (GHz), or combinations thereof. Plasma power supply 506 and wafer bias voltage power supply 516 may be appropriately sized to supply a range of powers in order to achieve the desired process performance. For example, in one embodiment, the plasma power supply 506 may supply the power in a range of 50 to 5000 Watts, and the wafer bias voltage power supply 516 may supply a bias voltage of in a range of 20 to 2000 volts (V). In addition, the TCP coil 510 and/or the electrode 520 may be comprised of two or more sub-coils or sub-electrodes. The sub-coils or sub-electrodes may be powered by a single power supply or powered by multiple power supplies.

[0034] As shown in FIG. 5, the plasma processing chamber system 500 further includes a gas source/gas supply mechanism 530. The gas source 530 is in fluid connection with plasma processing confinement chamber 504 through a gas inlet, such as a gas injector 540. The gas injector 540 may be located in any advantageous location in the plasma processing confinement chamber 504 and may take any form for injecting gas. Preferably, however, the gas inlet may be configured to produce a “tunable” gas injection profile. The tunable gas injection profile allows independent adjustment of the respective flow of the gases to multiple zones in the plasma process confinement chamber 504. More preferably, the gas injector is mounted to the dielectric inductive power window 512. The gas injector may be mounted on, mounted in, or form part of the power window. The process gases and by-products are removed from the plasma process confinement chamber 504 via a pressure control valve 542 and a pump 544. The pressure control valve 542 and pump 544 also serve to maintain a particular pressure within the plasma processing confinement chamber 504. The pressure control valve 542 can maintain a pressure of less than 1 torr during processing. An edge ring 560 is placed around the substrate 566. The gas source/gas supply mechanism 530 is controlled by the controller 524. A Kiyo by Lam Research Corp, of Fremont, CA, may be used to practice an embodiment.

[0035] In various embodiments, the component may be other parts of a plasma processing chamber, such as confinement rings, edge rings, the electrostatic chuck, a gas injector, ground rings, chamber liners, such as the pinnacle 572, door liners, windows, walls, or other components. In some embodiments, a baseplate of an electrostatic chuck has a coating with a thickness of 50 m to 125 pm. Other components have a coating with a thickness of 3 pm to 1000 pm. In some embodiments, the coating has a thickness of 25 pm to 300 pm. In other embodiments, the coating has a thickness of 50 pm to 100 pm. Other components of other types of plasma processing chambers may be used. For example, plasma exclusion rings on a bevel etch chamber may be coated in an embodiment. In another example, a showerhead of a dielectric processing chamber may be coated. In some embodiments, the chamber may have a dome shape, where the coating coats the dome. In some embodiments one or more, but not all surfaces of a component body 204 are coated.

[0036] In some embodiments, after a coating is deposited, the coating is machined, ground, and/or polished. In an example, the component may have a surface with a complex shape. Because the surface has a complex shape, the thickness of the coating may be nonuniform. Machining, grinding, and/or polishing may be used to provide a more uniform thickness. The uniform thickness may improve process uniformity, control coating stresses to prevent mechanical coating failure, and ensure that the part is able to fit with adjacent components. In an embodiment, a coating with a thickness of about 1500 pm thick was deposited. Machining and grinding reduce the thickness of the coating to a uniform thickness of less than 1000 pm. Polishing using a very fine grit high-hardness abrasive either embedded in a polishing pad or in a slurry may be used to reduce the roughness of the coating so that the plasma facing surface of the chamber has a uniform roughness. In some embodiments, the roughness is less than 5 pm Ra. Such a roughness may be achieved by spraying or with basic machining and/or grinding. In some embodiments, the roughness is less than 1.5 pm Ra. In some embodiments, the roughness of between 0.5 pm and 1.5 pm Ra. In some embodiments, the roughness of between 0.02 m and 0.5 pm Ra.

[0037] While this disclosure has been described in terms of several preferred embodiments, there are alterations, permutations, modifications, and various substitute equivalents, which 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, 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

CLAIMS What is claimed is:

1. A component for use in a plasma processing chamber system, comprising: a component body with a plasma facing surface; and a coating over at least the plasma facing surface, wherein the coating comprises spinel, wherein the spinel consisting essential of MgAl₂O4.

2. The component, as recited in claim 1, wherein the coating consists essentially of crystalline cubic structure spinel and at least one of magnesium aluminum oxide, aluminum oxide, and magnesium oxide.

3. The component, as recited in claim 2, wherein the coating is at least 50% by weight crystalline cubic structure spinel.

4. The component, as recited in claim 3, wherein the coating further comprises at least one of yttria, magnesium oxide, and amorphous magnesium aluminum oxide and alumina.

5. The component, as recited in claim 2, wherein the coating is at least 90% by weight crystalline cubic structure spinel.

6. The component, as recited in claim 1, wherein the component body is of an electrically conductive metal.

7. The component, as recited in claim 1, wherein the coating has a thickness in a range of 3 m to 1000 p.m.

8. The component, as recited in claim 1, wherein the component body forms at least part of at least one of a door liner, a liner, a pinnacle, a power window, a showerhead, a gas injector, wall, dome, and an electrostatic chuck.

9. The component, as recited in claim 1, wherein the coating has a porosity of no more than 20%.

10. The component, as recited in claim 1, wherein the coating has a porosity of between 0.5% and 4% inclusive.

11. The component, as recited in claim 1, further comprising one or more layers between the component body and the coating.

12. A method for forming a coating over a plasma facing surface of a component body of a component for use in a plasma processing chamber system, wherein the method comprises depositing a coating comprising spinel over at least the plasma facing surface of the component body, wherein the spinel consists essential of MgALC .

13. The method, as recited in claim 12, wherein the depositing the coating comprises: forming a mixture of MgO powder and AI2O3 powder into a structure of cubic structure spinel; granulating the cubic structure spinel; and thermal spraying the granulated cubic structure spinel over the plasma facing surface of the component.

14. The method, as recited in claim 12, wherein the coating is at least 50% by weight of spinel.

15. The method, as recited in claim 12, wherein the coating has a thickness in a range of 3 m to 1000 |im.

16. The method, as recited in claim 12, wherein the depositing the coating comprises: providing a powder mixture comprising MgO powder and AI2O3 powder; and thermal spraying the powder mixture on the plasma facing surface of the component forming a cubic structure spinel.

17. The method, as recited in claim 16, wherein the coating is at least 50% by weight of spinel.

18. The method, as recited in claim 12, wherein the depositing the coating is at least one of thermal spraying, atomic layer deposition, sintering, and aerosol deposition.

19. The method, as recited in claim 12, wherein the depositing the coating is at least one of a suspension plasma spraying, vacuum plasma spray, a high velocity oxygen fuel spray, and an atmospheric plasma spraying.

20. The method, as recited in claim 19, wherein the depositing the coating is at least one of a suspension plasma spraying, a high velocity oxygen fuel coating, and an atmospheric plasma spraying uses a spinel powder.

21. The method, as recited in claim 12, wherein the component body forms part of at least one of a liner, a pinnacle, a gas injector, a power window, an electrode, a showerhead, and an electrostatic chuck.

22. A product made by the method as recited in claim 12.