Multilayer sintered ceramic body and manufacturing method

Abstract

A multi-layer sintered ceramic body comprising at least one first layer (100) comprising polycrystalline YAG, the at least one first layer (100) having at least one surface, and at least one second layer (102) comprising magnesium aluminate spinel, at least one surface of the at least one first layer (100) comprising pores having a maximum size of 0.1-5 pm as measured by SEM, and each of the at least one first layer (100) and the at least one second layer (102) having a maximum size of 0-0.6×10 -6 A multi-layer sintered ceramic body is disclosed having different coefficients of thermal expansion (GTE) per degree C. Methods of making are also disclosed.

Description

[Technical Field]

[0001] The present invention relates to corrosion-resistant multilayer sintered ceramics and components formed therefrom, methods for making the ceramics, and their use in semiconductor plasma processing chambers. [Background technology]

[0002] Semiconductor processing requires the use of halogen-based gases in combination with high electric and magnetic fields to create a plasma environment. This plasma environment is created in a vacuum chamber to etch or deposit materials on a semiconductor substrate. These vacuum chambers include components such as a disk or window, a liner, an injector, a ring, and a cylinder. During semiconductor plasma processing, the substrate is typically supported within the vacuum chamber by a substrate holder, as disclosed in U.S. Pat. Nos. 5,262,029 and 5,838,529. Process gases for creating the plasma processing environment can be supplied to the chamber by various gas delivery systems. Some processes involve the use of radio frequency (RF) fields, where the process gas is introduced into the processing chamber, while the RF field is applied to the process gas to generate a plasma of the process gas. The ceramic materials used to form these components, particularly for RF applications, have a 1×10 -3A dielectric loss tangent on the order of 0.1 mm or less is required. Dielectric losses higher than this can cause overheating and hot spots within the components during use, leading to process variations and yield loss. The use of components made from high-purity starting powders and manufacturing processes that preserve initial purity provides sintered ceramics that meet these low-loss requirements. The harsh plasma processing environment necessitates the use of highly corrosion- and erosion-resistant materials for chamber components. These components are formed from materials that provide resistance to corrosion and erosion in plasma environments, as described, for example, in U.S. Pat. Nos. 5,798,016, 5,911,852, 6,123,791, and 6,352,611. Furthermore, plasma processing chambers are designed to include components such as disks, rings, and cylinders that confine the plasma over the wafer being processed. However, these components used in plasma processing chambers are continually attacked by the plasma, eventually resulting in corrosion, erosion, or the accumulation of contaminants and polymer buildup. Plasma etching and deposition conditions cause erosion and roughening of the surfaces of chamber parts exposed to the plasma. This erosion contributes to wafer-level contamination through the release of particles from the component surfaces into the chamber, resulting in yield loss of semiconductor devices.

[0003] To address this, chamber components often have surface layers that resist corrosion and erosion when exposed to process gases. Surface layers are formed on bases or substrates that may have excellent mechanical, electrical, or other desirable properties. For example, corrosion-resistant films or coatings of yttrium oxide or yttrium aluminum garnet are known to be deposited on bases or substrates made of different materials, such as alumina, which are cheaper and stronger than most corrosion-resistant materials. Such films or coatings have been produced by several methods. Vapor deposition has been used to deposit corrosion-resistant films on substrates, but vapor deposition is limited to relatively thin layers due to internal film stresses, and small pores often exist in thin films. These internal film stresses cause poor interlayer adhesion, typically resulting in delamination at the interface between the corrosion-resistant film and the substrate, making these layers prone to cracking and peeling, thereby leading to undesirable particulate contamination. Corrosion-resistant coatings or films produced by aerosol or plasma spray techniques typically exhibit high levels of porosity, ranging from 3% to approximately 50%, and correspondingly low densities. Furthermore, these films produced by aerosol or spray methods exhibit poor interfacial adhesion between the substrate material and the corrosion resistant layer, resulting in spalling and flaking and subsequent chamber contamination.

[0004] Commercially available methods for film deposition onto sintered substrates limit film thickness to less than about 0.45 mm. Such films often have pores due to non-uniformities in the base substrate, and the presence of pores and limited film thickness makes the film surface layer prone to cracking and exposes the base substrate to corrosive process gases and particle generation during processing.

[0005] Other approaches to forming corrosion-resistant, high-strength sintered bodies and / or components include stacking precast films, applying pressure to the films to form a laminate, and then co-sintering the laminate. These methods typically use pressureless sintering, and the flatness of the sintered laminate depends on closely matching the sintering rates of each film. For example, if the sintering rate of the top film is faster than that of the bottom film, the sintered ceramic laminate will have a concave curvature; if the sintering rate of the bottom film is faster than that of the top film, the sintered ceramic laminate will have a convex curvature (both configured with the top film facing up). Variations in sintering rates can create residual stresses in the sintered laminate, making it more susceptible to fracture and cracking, especially at larger dimensions. Therefore, materials selected for co-sintering are limited to those with the same or very similar sintering profiles of time, temperature, and duration, as known to those skilled in the art. Furthermore, these sintered laminates often exhibit poor interfacial adhesion between layers, which, combined with low density, results in peeling and spalling of the top layer, making them prone to fracture, delamination and cracking. Summary of the Invention [Problem to be solved by the invention]

[0006] As the dimensions of semiconductor substrates increase, corrosion-resistant, high-strength sintered ceramic bodies are needed to enable large-scale semiconductor device manufacturing, especially those with large dimensions (greater than 100 mm, e.g., 100 mm to 625 mm).

[0007] As a result, there is a need in the art for multilayer sintered ceramic bodies for use in plasma processing chambers that have the combined properties of corrosion and erosion resistance, high adhesion between layers, low dielectric loss tangent, high thermal conductivity, and high mechanical strength.

[0008] To meet these and other needs, and with that objective in mind, the present disclosure provides embodiments of multilayer sintered ceramic bodies and methods for preparing large multilayer sintered ceramic bodies having improved mechanical, electrical, and thermal properties and handling capabilities.

[0009] Described herein are sintered ceramic bodies, also referred to herein as multilayer sintered ceramic bodies, and methods of making them. These ceramic bodies offer high corrosion resistance to chlorine- and fluorine-based process gases, low dielectric loss tangent (tan δ), high thermal conductivity, and high mechanical strength, making them desirable for use as components in semiconductor plasma processing chambers that utilize halogen-based process gases. The ceramic bodies are particularly suitable for use as large chamber components, measuring 100 mm or greater.

[0010] Embodiment 1. A multilayer sintered ceramic body, comprising: at least one first layer comprising polycrystalline YAG, the at least one first layer having at least one surface; and at least one second layer comprising magnesium aluminate spinel, wherein at least one surface of the at least one first layer comprises pores having a maximum size of 0.1 to 5 μm as measured by SEM, and wherein each of the at least one first layer and the at least one second layer has a pore size of 0 to 0.6×10 as measured according to ASTM E228-17 over a temperature range of 25 to 1400°C. -6 A multilayer sintered ceramic body, wherein at least one first layer and at least one second layer have different coefficients of thermal expansion (CTE) / °C, the CTEs of which are used to calculate the difference being each measured over the same temperature range, and the at least one second layer comprises 0.1 to 1.0 volume percent zirconia.

[0011] Embodiment 2. The multilayer sintered ceramic body of embodiment 1, wherein the multilayer sintered ceramic body has a maximum dimension of 100 mm to 625 mm.

[0012] Embodiment 3. The multilayer sintered ceramic body of embodiment 1 or 2, wherein the pores have a maximum size of 0.1 to 2 μm as measured by SEM.

[0013] Embodiment 4. The multilayer sintered ceramic body of any one of embodiments 1 to 3, wherein the pores have a maximum size of 0.1 to 1 μm as measured by SEM.

[0014] Embodiment 5. The pores are about 2 to about 600 μm as measured using SEM and image processing methods. 2 / mm 2 5. The multilayer sintered ceramic body of any one of embodiments 1 to 4, characterized by a cumulative pore size distribution of:

[0015] Embodiment 6. The pore distribution is about 2 to about 300 μm as measured by SEM. 2 / mm 2 6. The multilayer sintered ceramic body of embodiment 5, wherein

[0016] Embodiment 7. A multilayer sintered ceramic body according to any one of embodiments 1 to 6, wherein at least one surface has a porosity of 0.0005 to 1% by percentage of the total area of ​​the at least one surface, as measured by SEM.

[0017] Embodiment 8. The multilayer sintered ceramic body of embodiment 7, wherein the porosity by percentage of the total area of ​​at least one surface is 0.005 to 2%.

[0018] Embodiment 9. A multilayer sintered ceramic body according to any one of embodiments 1 to 8, wherein the relative density of the at least one first layer and the relative density of the at least one second layer is 99 to 100%.

[0019] Embodiment 10. The multi-layer sintered ceramic body of embodiment 9, wherein the relative density varies by 5% or less across the largest dimension of the multi-layer sintered body.

[0020] Embodiment 11. The multilayer sintered ceramic body of embodiment 10, wherein the relative density varies by no more than 3% across its largest dimension.

[0021] Embodiment 12. The multilayer sintered ceramic body of embodiment 11, wherein the relative density varies by 1% or less across its largest dimension.

[0022] Embodiment 13. A multilayer sintered ceramic body according to any one of embodiments 10 to 12, having a maximum dimension of 400 to 625 mm.

[0023] Embodiment 14. A multilayer sintered ceramic body according to any one of embodiments 1 to 13, wherein the difference in coefficient of thermal expansion (CTE) between the at least one first layer and the at least one second layer is 0 to 0.3 × 10-6 / °C.

[0024] Embodiment 15. A multilayer sintered ceramic body according to any one of embodiments 1 to 14, wherein the absolute value of the difference in coefficient of thermal expansion (CTE) between the at least one first layer and the at least one second layer is maintained throughout the temperature range from ambient temperature to about 1700°C.

[0025] Embodiment 16. The multilayer sintered ceramic body of any one of embodiments 1 to 15, wherein at least one second layer is composed of 0.1 to 1.0 volume percent zirconia.

[0026] Embodiment 17. The multilayer sintered ceramic body of embodiment 1, wherein the at least one second layer comprises 0.5 volume percent zirconia.

[0027] Embodiment 18. A multilayer sintered ceramic body according to any one of embodiments 1 to 17, wherein at least one first layer comprises YAG in an amount of 98 to 99.3 volume % as measured using XRD, SEM and image processing methods, with the remainder comprising at least one crystalline phase selected from the group consisting of aluminum oxide, yttrium oxide, YAM and YAP, and combinations thereof.

[0028] Embodiment 19. A multilayer sintered ceramic body according to any one of embodiments 1 to 18, wherein the at least one first layer has a total impurity content of less than 25 ppm by weight of the at least one first layer as measured by ICPMS.

[0029] Embodiment 20. The multilayer sintered ceramic body of any one of embodiments 1 to 19, wherein at least one first layer does not contain a dopant.

[0030] Embodiment 21. A multilayer sintered ceramic body according to any one of embodiments 1 to 20, wherein at least one first layer does not contain a sintering aid.

[0031] Embodiment 22. The multilayer sintered ceramic body of any one of embodiments 1 to 21, wherein the at least one first layer comprises silica in an amount of 14 to 25 ppm based on the weight of the at least one first layer, as measured by ICPMS.

[0032] Embodiment 23. A multilayer sintered ceramic body according to any one of embodiments 1 to 22, wherein at least one first layer has an Sa of 0.0005 to 1 um, as measured according to ISO standard 25178-2-2012.

[0033] Embodiment 24. The multilayer sintered ceramic body of embodiment 26, wherein Sa is 0.001 to 0.020 μm as measured in accordance with ISO standard 25178-2-2012.

[0034] Embodiment 25. A multilayer sintered ceramic body according to any one of embodiments 1 to 24, wherein at least one first layer has an Sz of 0.3 to 3 um as measured according to ISO standard 25178-2-2012.

[0035] Embodiment 26. The multilayer sintered ceramic body of any one of embodiments 1 to 25, wherein the at least one second layer has a density of 3.47 to 3.58 g / cc as measured in accordance with ASTM B962-17.

[0036] Embodiment 27. A multilayer sintered ceramic body according to any one of embodiments 1 to 26, wherein the at least one second layer has a total impurity content of 10 to 80 ppm based on the mass of the at least one second layer, as measured using an ICPMS method.

[0037] Embodiment 28. A multilayer sintered ceramic body according to any one of embodiments 1 to 27, having an interface defined by at least one first layer and a second layer, the interface having an average interface line, and the distance from the interface to the average interface line varies in an amount of 10 to 100 um as measured by SEM.

[0038] Embodiment 29. A multilayer sintered ceramic body according to embodiment 34, wherein the interface defined by at least one first layer and second layer has a tortuosity of 1 to 3 as measured by SEM.

[0039] Embodiment 30. A multilayer sintered ceramic body described in any one of embodiments 1 to 29, wherein at least one first layer has a thickness d1, at least one second layer has a thickness d2, and the thickness of the at least one second layer is 80% to 98% of the total thickness of the at least one first layer and second layer.

[0040] Embodiment 31. A multilayer sintered ceramic body according to any one of embodiments 1 to 30, wherein at least one first layer has an L* value of less than 90 as measured on the plasma-facing surface of the at least one first layer.

[0041] Embodiment 32. A method for making a multilayer sintered ceramic body, comprising: a) combining yttria powder and alumina powder to form a first powder mixture; b) combining magnesium oxide powder, aluminum oxide powder, and zirconium oxide powder to form a second powder mixture; c) sintering the first sintered powder mixture and the second sintered powder mixture by applying heat to raise the temperature of the powder mixture to a sintering temperature and maintaining the sintering temperature to form the first powder mixture and the second powder mixture; d) separately disposing the first sintered powder mixture and the second sintered powder mixture in a volume defined by a toolset of a sintering apparatus to form at least one layer of the first sintered powder mixture and at least one layer of the second sintered powder mixture, and creating a vacuum condition in the volume; and e) sintering the first sintered powder mixture while heating to the sintering temperature. and f) applying pressure to the layers of the mixture and the second fired powder mixture and sintering to form a multilayer sintered ceramic body, wherein at least one layer of the sintered first powder mixture forms at least one first layer and at least one layer of the second fired powder mixture forms at least one second layer after sintering; and f) reducing the temperature of the multilayer sintered ceramic body, wherein the at least one first layer comprises polycrystalline YAG, the at least one first layer has at least one surface, and the at least one second layer comprises magnesium aluminate spinel, and the at least one surface of the at least one first layer comprises pores, the pores having a maximum size of 0.1 to 5 μm as measured using SEM and image processing methods, and each of the at least one first layer and the at least one second layer has a pore size of 0 to 0.6×10 as measured according to ASTM E228-17 over a temperature range of 25 to 1400°C. -6 % zirconia / °C.

[0042] Embodiment 33. The method of embodiment 32, further comprising: g) optionally annealing the multi-layer sintered ceramic body by applying heat to increase the temperature of the multi-layer sintered ceramic body to reach an annealing temperature at which annealing is performed; and h) reducing the temperature of the annealed multi-layer sintered ceramic body.

[0043] Embodiment 34. The method of embodiment 32 or 33, wherein the tool set includes a graphite die having a volume, an inner wall, a first opening, and a second opening, and a first punch and a second punch operably connected to the die, each of the first punch and the second punch having an outer wall defining a diameter smaller than the diameter of the inner wall of the die, thereby forming a gap between each of the first punch and the second punch and the inner wall of the die when at least one of the first punch and the second punch moves within the volume of the die.

[0044] Embodiment 35. The method of embodiment 34, wherein the gap is a distance of 10 to 100 μm between the inner wall of the die and the outer wall of each of the first punch and the second punch.

[0045] Embodiment 36. The method of any one of embodiments 32 to 435, wherein at least one second layer comprises 0.5% by volume zirconia.

[0046] Embodiment 37. The method of any one of embodiments 32 to 36, wherein the sintering temperature is 1000 to 1300°C.

[0047] Embodiment 38. The method of any one of embodiments 32 to 37, wherein a pressure of 5 to 59 MPa is applied to the calcined powder mixture while heating to the sintering temperature.

[0048] Embodiment 39. The method of embodiment 38, wherein the pressure is 5 to 40 MPa.

[0049] Embodiment 40. The method of embodiment 39, wherein the pressure is 5 to 20 MPa.

[0050] Embodiment 41. The method of any one of embodiments 32-40, wherein the first calcined powder mixture and the second calcined powder mixture have a combined total impurity content of 100 ppm or less as measured by ICPMS.

[0051] Embodiment 42. The method of any one of embodiments 32-41, wherein the second calcined powder mixture comprises zirconia in an amount by weight of 0.1-1.0 volume percent.

[0052] Embodiment 43. The method of any one of embodiments 32-42, wherein the first powder mixture and the second powder mixture are crystalline as determined by X-ray diffraction.

[0053] Embodiment 44. The first calcined powder mixture and the second calcined powder mixture each have a mass of 1 m 2 as measured in accordance with ASTM C1274. 2 / g~about 10m 2 44. The method of any one of embodiments 32 to 43, having a specific surface area (SSA) of 1 / g.

[0054] Embodiment 45.i) The method of any one of embodiments 32 to 44, further comprising machining the multilayer sintered ceramic body to form a multilayer sintered ceramic component in the shape of a dielectric window, RF window, focus ring, process ring, deposition ring, nozzle or gas injector, showerhead, gas distribution plate, etch chamber liner, plasma source adapter, gas inlet adapter, diffuser, electrostatic wafer chuck (ESC), chuck, puck, ion suppressor element, faceplate, isolator, spacer, and / or guard ring in a plasma processing chamber.

[0055] Embodiment 46. A multilayer sintered ceramic body made by the process of any one of embodiments 32-45.

[0056] Embodiment 47. The multilayer sintered ceramic body of embodiment 46 having a maximum dimension of 100 to about 625 mm.

[0057] Embodiment 48. The multilayer sintered ceramic body of embodiment 47 having a maximum dimension of 400 to about 625 mm.

[0058] The embodiments of the present invention may be used alone or in combination with each other. [Brief explanation of the drawings]

[0059] The present disclosure is best understood from the following detailed description when read in connection with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to scale. Conversely, the dimensions of the various features have been arbitrarily increased or reduced for clarity. The drawings include the following figures:

[0060] [Figure 1] In FIG. 1, a) shows an SEM micrograph of an interface 104 of a multilayer sintered ceramic body at 5000x magnification, and b) shows a measurement of the tortuosity (T) of the nonlinear interface 104 according to an embodiment disclosed herein. [Figure 2] FIG. 2 shows an exemplary schematic diagram of a multi-layer sintered ceramic body according to embodiments disclosed herein. [Figure 3] FIG. 3 shows the binary phase diagram of yttrium oxide / aluminum oxide. [Figure 4] In FIG. 4, FIG. 8 shows the X-ray diffraction results of at least one first layer 100 including YAG according to embodiments disclosed herein. [Figure 5] In FIG. 5, a) shows an SEM micrograph of the surface of at least one first layer comprising polycrystalline YAG using backscattering detection (BSD) and b) shows an SEM image from the same area of ​​the surface after thresholding to reveal the porosity and alumina phase according to an embodiment corresponding to Example 2 disclosed herein. [Figure 6]In Figure 6, a) shows a topographical SEM micrograph (using a topographical imaging method) of the surface of at least one first layer comprising YAG of Figure 6, and b) shows a topographical SEM image from the same region of the surface after thresholding to reveal the porosity and alumina phase according to an embodiment corresponding to Example 2 disclosed herein. [Figure 7] FIG. 7 shows the pore area versus pore size of a single multi-layer sintered ceramic body including at least one first layer 100 containing YAG. [Figure 8] FIG. 8 shows the cumulative pore area versus pore size for a multi-layer sintered ceramic body including at least one first layer 100 comprising YAG. [Figure 9] In Figure 9, a) shows an SEM micrograph of the surface of at least one layer of a multilayer sintered ceramic body containing YAG, and b) shows the total % of surface area containing porosity within the seven images of Figures 7 and 8. [Figure 10] In FIG. 10, a) shows a schematic diagram of a multilayer sintered ceramic body 98, and b) shows a nonlinear interface 104 according to an embodiment disclosed herein. [Figure 11] In FIG. 11, a) shows the tortuosity (T) and b) shows the mean interface line (IL) that characterizes the nonlinear interface 104 according to embodiments disclosed herein. [Figure 12] FIG. 12 is an XRD pattern of an exemplary layer of a sintered body including a cubic spinel phase according to one embodiment. [Figure 13] FIG. 13 is a 5000x SEM micrograph showing the polished surfaces of the five samples of Example 4. [Figure 14] FIG. 14 is an SEM micrograph at 5000x magnification of a layer of magnesium aluminate spinel produced according to Example 5. [Figure 15] FIG. 15 is an SEM micrograph at 5000x magnification of a layer of YAG made according to Example 5. [Figure 16] FIG. 16 shows the difference in CTE between YAG and spinel over the temperature range of 200-1400°C. DETAILED DESCRIPTION OF THE INVENTION

[0061] The following detailed description assumes that the present disclosure is practiced in an apparatus such as an etch chamber or deposition chamber required as part of the fabrication of devices on a semiconductor substrate. However, the present disclosure is not limited thereto. Workpieces can be of various shapes, sizes, and materials. In addition to semiconductor wafer processing, other workpieces that can utilize the present invention include various articles such as inorganic circuit boards with fine feature sizes, magnetic recording media, magnetic recording sensors, mirrors, optical elements, micromechanical devices, and the like.

[0062] Definitions - As used herein, the term "alumina" is understood to be aluminum oxide, Al2O3, and "magnesia" is understood to be magnesium oxide, MgO.

[0063] As used herein, the terms "semiconductor wafer," "wafer," "substrate," and "wafer substrate" are used interchangeably. Wafers or substrates used in the semiconductor device industry typically have diameters of 200 mm, or 300 mm, or 450 mm.

[0064] As used herein, the term "sintered ceramic body" is synonymous with "multilayer sintered ceramic body," "corrosion-resistant sintered ceramic," "corrosion-resistant body," "sintered ceramic," "multilayer monolithic body," and similar terms, and refers to a single, monolithic sintered ceramic article formed from co-compressing two or more powder mixtures by applying pressure and heat to form a single, dense, multilayer sintered ceramic body. The single multilayer sintered ceramic body can be machined into a single multilayer sintered ceramic component useful as a chamber component in plasma processing applications. Thus, the multilayer sintered ceramic bodies disclosed herein are not formed by laminating preformed layers together; i.e., the multilayer sintered ceramic bodies disclosed herein are not laminates.

[0065] "Unitary" or "integral" means a single piece or component that is complete in itself without additional pieces, i.e., the component is one monolithic piece formed with another component as a unit.

[0066] As used herein, the term "substantially" is a descriptive term indicating approximation, meaning "to a great extent" or "to the majority, but not all, of what is specified," and is intended to avoid precise numerical boundaries for specified parameters.

[0067] As used herein, the term "sintered ceramic component" or "multilayer sintered ceramic component" refers to a sintered ceramic body, a multilayer sintered ceramic body, or a corrosion-resistant ceramic after a machining process that forms the ceramic into the specific shape of a desired component for use in a semiconductor processing chamber disclosed herein.

[0068] As used herein, the term "powder mixture" refers to two or more starting powders mixed together prior to the sintering process, whereby a sintered ceramic body is formed after the sintering step. A powder mixture that has been subjected to firing as disclosed herein is referred to herein as a "fired powder mixture."

[0069] As used herein, the term "nanopowder" is intended to encompass powders having an average or d50 particle size of about 100 nm or less.

[0070] The term "annealing" as applied to ceramic heat treatment is understood herein to mean a heat treatment that may be performed in air on the disclosed sintered ceramic bodies to relieve stress and / or normalize stoichiometry.

[0071] As used herein, the term "tool set" may include at least one die and at least two punches. When fully assembled, the toolset defines a volume for placing a fired powder mixture, as disclosed.

[0072] As used herein, a "solid solution" is defined as a mixture of different elements that share the same crystal lattice structure. The mixture within the lattice may be substitutional, where atoms from one starting crystal substitute for atoms from another starting crystal, or interstitial, where atoms occupy normally vacant positions in the lattice.

[0073] As used herein, the term "nano powder" refers to a powder containing 20m 2 / g.

[0074] As used herein, the term "phase" is understood to mean a distinct crystalline region, portion, or layer of a sintered ceramic body having a particular crystal structure.

[0075] As used herein, the term "layer" is understood to mean a thickness of material, typically one of several. The material may be, for example, a ceramic powder or a sintered region or portion.

[0076] As used herein, "ambient temperature" refers to a temperature range of about 22°C to 25°C.

[0077] As used herein, the term "purity" refers to the absence of various contaminants in a) the starting materials from which the powder mixture may be formed, b) the processed powder mixture (or fired powder mixture), and c) the sintered ceramic body or component disclosed herein. Higher purities (approaching 100%) refer to materials that are essentially free of, or have very low amounts of, contaminants or impurities, and that substantially comprise the material composition present in the starting powders disclosed.

[0078] As used herein, the term "impurities" refers to compounds / contaminants present in the powders or sintered ceramics other than the intended compounds themselves (magnesia, alumina, yttria, and zirconia starting powders, powder mixtures, and ceramics formed therefrom). Impurities may be present in the starting powders, powder mixtures, processed powder mixtures, and sintered ceramic bodies. ICPMS techniques were used to determine the impurity content of the powders, powder mixtures, and first and second layers of the sintered bodies disclosed herein.

[0079] As used herein, the term "dopant" refers to a substance added to a bulk material to impart desired properties to the ceramic material (e.g., to alter electrical properties). Typically, dopants, when used, are present in low concentrations, i.e., >0.002% to <0.05% by weight.

[0080] Impurities differ from dopants in that dopants, as defined herein, are compounds that are intentionally added to the starting powder or powder mixture to achieve particular electrical, mechanical, optical, or other properties, such as modifying grain size in the sintered ceramic body. As used herein, the term "dopant" does not include Hf and Y, which are present in the zirconium oxide starting material, to the extent that they may remain in the sintered ceramic body.

[0081] As used herein, the term "sintering aid" refers to compounds such as silica (SiO), lithium (LiO), lithium fluoride (LiF), magnesia (MgO), and / or calcia (CaO) that increase densification during the sintering process, thereby reducing porosity. Hf and Y, to the extent present in the starting powder and remaining in the sintered ceramic, do not constitute sintering aids, impurities, or dopants as defined herein.

[0082] As used herein, the terms "substantially," "approximately," and "about" are used in connection with numbers and therefore allow for a variance of plus or minus 10%.

[0083] As used herein, the term "coefficient of thermal expansion (CTE)" is measured in accordance with ASTM E228-17 over a temperature range of 25-200°C to 25-1400°C, preferably 25-1200°C, more preferably 25-1000°C, more preferably 25-800°C, more preferably 25-600°C, more preferably 25-400°C, and more preferably 25-200°C. CTE describes how an object's size changes with temperature. Specifically, it measures the rate of size change per degree of temperature change at a constant pressure. To determine the coefficient at a temperature, the volume of a material is measured at a reference temperature, and the volume of the material is measured at the temperature at which the CTE is to be determined. The fractional change is then determined based on the difference in volume and temperature.

[0084] All CTE values ​​in this disclosure were made in accordance with ASTM E228-17. In particular, the reference temperature used was ambient temperature, specifically 25°C. Thus, when a CTE at a given temperature (i.e., 200°C) is disclosed, the CTE has been determined by comparing the volume (or linear expansion of an isotropic material) at that temperature to the volume (or linear expansion of an isotropic material) at ambient temperature, specifically 25°C. In any case of conflict regarding CTE, ASTM E228-17 is always the controlling disclosure. In the disclosed examples, CTE was measured using a vertical dilatometer, specifically the L75 model available from Linseis Messgeräte GmbH (Selb, Germany).

[0085] During semiconductor device processing, corrosion-resistant chamber components are used in etch and / or deposition plasma processing chambers and are exposed to harsh corrosive environments that cause particle release into the chamber, resulting in yield loss due to wafer-level contamination. The multilayer sintered ceramic bodies disclosed herein and related components manufactured therefrom provide improved plasma resistance and enhanced mechanical strength for use in semiconductor processing chambers due to certain material properties and characteristics described below.

[0086] Corrosion-resistant ceramics, particularly multilayer sintered ceramic bodies having two or more layers for use in semiconductor reactor chambers, and their fabrication are described herein. Semiconductor etch and deposition reactors require reactor components with surfaces that are highly resistant to corrosion and erosion by the oxygen- and halogen-containing plasmas required for processing. Additionally, chamber components, especially large components, must have sufficient mechanical strength for ease of handling and use. The multilayer sintered ceramic bodies disclosed herein include at least one first layer comprising polycrystalline YAG, the at least one first layer having at least one surface, and the at least one second layer comprising magnesium aluminate spinel (MgAl2O4), the at least one surface of the at least one first layer comprising pores having a maximum size of 0.1 to 5 μm as measured by SEM, and each of the at least one first layer and the at least one second layer having a maximum size of 0 to 0.6 × 10 as measured in accordance with ASTM E228-17. -6 / °C different coefficients of thermal expansion (CTE). YAG material has excellent corrosion and erosion resistance, while magnesium aluminate spinel has excellent thermal and dielectric properties and is easily machinable. Use of this material results in semiconductor plasma processing chamber components with surfaces that offer improved plasma resistance over other materials, for example, when subjected to halogen-based plasma etching and deposition conditions.

[0087] The sintered ceramic bodies disclosed herein can include at least one first layer and at least one second layer having a major dimension. The maximum extension of the at least one first layer and at least one second layer can range from about 100 mm to about 625 mm, including 122 mm, 222 mm, 322 mm, and 522 mm. The maximum extension of the at least one first layer and at least one second layer can further vary from 100 mm to about 625 mm, preferably 100 mm to 622 mm, preferably 200 mm to about 625 mm, preferably 300 mm to about 625 mm, preferably 400 mm to about 625 mm, preferably 500 mm to about 625 mm, preferably 300 mm to 622 mm, preferably 400 mm to 622 mm, and preferably 500 mm to 622 mm.

[0088] At least one of the first layer and the second layer has a molecular weight of 0 to 0.5 × 10 -6 / °C, preferably 0 to 0.45 × 10 -6 / °C, preferably 0 to 0.4 × 10 -6 , preferably 0 to 0.35 × 10 -6 / °C, preferably 0 to 0.3 × 10 -6 / °C, preferably 0 to 0.25 × 10 -6 / °C, preferably 0 to 0.2 × 10 -6 / °C, preferably 0 to 0.15 × 10 -6 / °C, preferably 0 to 0.1 × 10 -6 / °C, preferably 0 to 0.08 × 10 -6 / °C, preferably 0 to 0.06 × 10 -6 / °C, preferably 0 to 0.04 × 10 -6 / °C, preferably 0 to 0.02 × 10 -6 Preferably 0 to 0.01 × 10 -6 The absolute value of the difference in CTE in terms of °C / °C.

[0089] The CTE of at least the first layer and the second layer is measured according to ASTM E228-17 over a temperature range of 25 to 1700°C, or over a temperature range of 200 to 1400°C.

[0090] The CTEs of the at least one first layer and the at least one second layer used to calculate each difference are each measured over the same temperature range. The difference in the CTEs of the at least one first layer and the at least one second layer is measured over the same temperature range.

[0091] The at least one first layer and the at least one second layer of the sintered ceramic bodies disclosed herein can have respective CTEs that have the same or substantially the same absolute value of the aforementioned CTE over the entire temperature range from ambient temperature to about 1700°C, or over the temperature range from 200 to 1400°C.

[0092] On a percentage basis, the combination of at least one first layer and at least one second layer may have CTE values ​​(over the temperature ranges disclosed herein) that match each other by no more than 4%, preferably no more than 3.5%, preferably no more than 3%, preferably no more than 2.5%, preferably no more than 2%, preferably no more than 1.5%, preferably no more than 1%, preferably no more than 0.5% of the at least one first layer and the at least one second layer (as measured relative to the at least one first layer).

[0093] The sintered ceramic body disclosed herein includes an interface layer or interface between at least one first layer and at least one second layer. The interface layer typically has a tortuosity and a nonlinear interface between the at least one first layer and the at least one second layer, typically tortuous. The tortuosity, using the calculations disclosed herein, can be 1.2 to 2.2, particularly 1.4 to 2.0. The measurement for determining the tortuosity is described below and is based on the increase in interface length relative to the linear distance of the interface layer. Accordingly, the present disclosure provides a multilayer sintered ceramic body having an interface defined by at least one second layer and at least one first layer, wherein the interface length increases by 20 to 70%, preferably 20 to 60%, preferably 20 to 40%, preferably 30 to 80%, preferably 40 to 80%, and preferably 50 to 70%.

[0094] Correspondingly, the at least one second layer and the at least one first layer may contact each other at an interface having an interfacial area commensurate with the largest dimension of the multilayer sintered ceramic body along the interface layer.

[0095] In the case of a single multilayer sintered body having a maximum dimension of 100 to about 625 mm, taking into account the above-mentioned bending degree of at least 1.2, at least one second layer and at least one first layer have a bending length of at least 113 cm. 2 , preferably at least 452 cm 2 , preferably at least 1,018 cm 2 , preferably at least 1,810 cm 2 They contact each other at a nonlinear interface with an area of

[0096] In the case of a single multilayer sintered body having a maximum dimension of 100 to about 625 mm, taking into account the above-mentioned bending degree of at least 1.4, at least one second layer and at least one first layer have a length of at least 153 cm. 2 , preferably at least 616 cm 2 , preferably at least 1,386 cm 2 , preferably at least 2,464 cm 2 They contact each other at a nonlinear interface with an area of

[0097] In the case of a single multilayer sintered body having a maximum dimension of 100 to about 625 mm, taking into account the above-mentioned bending degree of up to 2.2, at least one second layer and at least one first layer have a maximum bending length of 15,085 cm 2 , preferably up to 14,850 cm 2 , preferably up to 14,128 cm 2 , preferably up to 9,802 cm 2 , preferably up to 6,083 cm 2 , preferably up to 3,421 cm 2 , preferably up to 1,520 cm 2 They contact each other at a nonlinear interface with an area of

[0098] In the case of a single multilayer sintered body having a maximum dimension of 100 to about 625 mm, taking into account the above-mentioned bending degree of up to 2.0, at least one second layer and at least one first layer have a maximum bending length of 12,468 cm 2 , preferably up to 12,272 cm 2 , preferably up to 11,676 cm 2 , preferably up to 7,852 cm 2 , preferably up to 5,028 cm 2 , preferably up to 2,828 cm 2 , preferably up to 1,256 cm 2 They contact each other at a nonlinear interface with an area of

[0099] In the case of a single multilayer sintered body having a maximum dimension of 100 to about 625 mm, taking into account the above-mentioned bending degree of at least 1.2, at least one second layer and at least one first layer have a maximum dimension of 113 to about 4,488 cm 2 , preferably 113 to about 4,418 cm 2 , preferably 113 to 4,204 cm 2 , preferably 113 to 2,827 cm 2 , preferably 113 to 1,918 cm 2 , preferably 113 to 1,018 cm 2 , preferably 113 to 452 cm 2 , preferably 452 to about 4,488 cm 2 , preferably 452 to about 4,418 cm 2 , preferably 452 to 4,203 cm 2 , preferably 452 to 2,827 cm 2 , preferably 452 to 1,810 cm 2 , preferably 1,018 to about 4,418 cm 2 , preferably 1,810 to 4,376 cm 2 They contact each other at a nonlinear interface with an area of

[0100] In the case of a single multilayer sintered body having a maximum dimension of 100 to about 625 mm, taking into account the above-mentioned bending degree of at least 1.4, at least one second layer and at least one first layer have a maximum dimension of 153 to about 6,110 cm 2, preferably 153 to about 6,013 cm 2 , preferably 153 to 5,722 cm 2 , preferably 153 to 3,847 cm 2 , preferably 153 to 2,464 cm 2 , preferably 153 to 1,386 cm 2 , preferably 153 to 616 cm 2 , preferably 616 to about 6,110 cm 2 , preferably 616 to about 6,013 cm 2 , preferably 616 to 5,722 cm 2 , preferably 616 to 3,847 cm 2 , preferably 616 to 2,464 cm 2 , preferably 1,386 to about 6,013 cm 2 , preferably 2,464 to 5,957 cm 2 They contact each other at a nonlinear interface with an area of

[0101] In the case of a single multilayer sintered body having a maximum dimension of 100 to about 625 mm considering the above maximum bending strength of 2.2, at least one second layer and at least one first layer have a bending strength of 378 to about 15,085 cm 2 , preferably 378 to about 14,850 cm 2 , preferably 378 to 14,128 cm 2 , preferably 378 to 9,502 cm 2 , preferably 378 to 6,083 cm 2 , preferably 378 to 3,421 cm 2 , preferably 378 to 1,520 cm 2 , preferably 1,520 to about 15,085 cm 2 , preferably 1,520 to about 14,850 cm 2 , preferably 1,520 to 14,128 cm 2 , preferably 1,520 to 9,502 cm 2 , preferably 1,1520 to 6,083 cm 2 , preferably 3,421 to about 14,850 cm 2 , preferably 6,083 to 14,710 cm 2 They contact each other at a nonlinear interface with an area of

[0102] In the case of a single multilayer sintered body having a maximum dimension of 100 to about 625 mm, taking into account the above-mentioned bending degree of up to 2.0, at least one second layer and at least one first layer have a bending length of 312 to about 12,468 cm 2 , preferably 312 to about 12,272 cm 2 , preferably 312 to 11,676 cm 2 , preferably 312 to 7,852 cm 2 , preferably 312 to 5,028 cm 2 , preferably 312 to 2,828 cm 2 , preferably 312 to 1,256 cm 2 , preferably 1,256 to about 12,468 cm 2 , preferably 1,256 to about 12,272 cm 2 , preferably 1,256 to 11,676 cm 2 , preferably 1,256 to 7,652 cm 2 , preferably 1,256 to 5,028 cm 2 , preferably 2,828 to about 12,272 cm 2 , preferably 5,028 to 7,294 cm 2 They contact each other at a nonlinear interface with an area of

[0103] The width d of said interface layer is shown in FIG. 1b) and is further explained below.

[0104] The width d of the interface layer shown in FIG. 1b) is usually 1 to 200 μm, particularly 5 to 100 μm, more specifically 10 to 50 μm, and even more specifically 20 to 30 μm.

[0105] The volume of the first layer over said width d of the interface layer has pores with a maximum size of less than 5 μm, in particular less than 3 μm, in particular less than 1 μm.

[0106] The volume of the first layer across the width of said interface layer in particular has only pores with a maximum size of less than 5 μm, in particular less than 3 μm, in particular less than 1 μm.

[0107] The volume of at least the first layer within the width d disclosed herein has a structure in which less than 0.2%, more preferably less than 0.15%, and most preferably less than 0.1% of the volume is occupied by the above-mentioned pores.

[0108] The volume of the second layer across the width of said interface layer has pores with a maximum size of less than 5 μm, in particular less than 3 μm, in particular less than 1 μm.

[0109] The volume of the second layer across the width of said interface layer in particular has only pores with a maximum size of less than 5 μm, in particular less than 3 μm, in particular less than 1 μm.

[0110] The volume of at least the second layer within the width d disclosed herein has a structure in which less than 0.2%, more preferably less than 0.15%, and most preferably less than 0.1% of the volume is occupied by the pores described above.

[0111] At least one first layer of the present disclosure exhibits very small pore sizes in the same range or the same as at least one second layer.

[0112] The pore size in the volume of the at least one first layer and at least one second layer was measured throughout the sample using SEM images obtained from a Phenom XL scanning electron microscope at 1000x and 5000x magnification. The images were imported into ImageJ software for analysis. ImageJ, developed at the National Institutes of Health (NIH), is a Java-based, public domain image processing and analysis program for image processing of scientific multidimensional images. The use of semi-automated and automated image analysis methods to measure grain size is described in ASTM standard E1382. Images measuring 53.7 μm × 53.7 μm were analyzed to determine the pore size present throughout the referenced volume.

[0113] The at least one first layer preferably has an average density of 98.5% or greater or 99.5% or greater, with a density variation of 5% or less, preferably 4% or less, preferably 3% or less, preferably 2% or less, and preferably 1% or less across its greatest dimension, whereby the greatest dimension can be, for example, about 625 mm or less, 622 mm or less, 610 mm or less, preferably 575 mm or less, preferably 525 mm or less, preferably 100-625 mm, preferably 100-622 mm, preferably 100-575 mm, preferably 200-625 mm, preferably 200-510 mm, preferably 400-625 mm, or preferably 500-625 mm. This density of the at least one first layer can also be achieved across the width d of the interface layer described above.

[0114] The at least one second layer disclosed herein preferably has a relative density of, for example, 98-100%, 99-100%, or even 99.5-100%, where the term "relative density" refers to the percentage difference between the measured density and the theoretical density.

[0115] The at least one first layer preferably has a porosity in percent of total area in the amount of 0.0005-2%, preferably 0.0005-1%, preferably 0.0005-0.5%, preferably 0.0005-0.05%, preferably 0.0005-0.03%, preferably 0.0005-0.005%, preferably 0.0005-0.003%, preferably 0.0005-0.001%, preferably 0.005-2%, preferably 0.05-2%, preferably 0.5-2%, preferably 0.005-2%, preferably 0.005-1%, preferably 0.05-2%, preferably 0.05-1%, preferably 0.5-2%.

[0116] The at least one second layer preferably has a volume porosity in the sintered ceramic body in an amount of 0.1-2%, preferably 0.1-1.5%, preferably 0.1-1%, preferably 0.1-0.5%.

[0117] The above-mentioned density and porosity of the at least one first and second layer are realized in particular in their volume surrounding the interface layer in the above-mentioned width d.

[0118] The combination of the feature of the CTE difference between the at least one first layer and the at least one second layer and the feature of the high density of the at least one first layer and the at least one second layer surrounding the interface layer in the above-mentioned width d provides a beneficial effect on the stability of the formed unit against peeling and spalling of the top layer.

[0119] The combination of the CTE difference feature between the at least one first layer and the at least one second layer and the high density feature of the at least one first layer and the at least one second layer surrounding the interface layer in the width d provides a beneficial effect of avoiding breakage, delamination, and cracking.

[0120] Nonetheless, the CTE differential characteristics and maximum pore size by volume are expected to provide improved adhesion between at least the first layer and at least the second layer.

[0121] Referring to the embodiment of Figure 2, disclosed is a multilayer sintered ceramic body 98 having at least one first layer 100 with a plasma-facing surface 106 that provides resistance to the corrosive and erosive effects of halogen-based plasmas and ion bombardment, a controlled porosity distribution with small pore sizes, high purity, high density, and low surface roughness. Preferably, the at least one first layer 100 has a coefficient of thermal expansion (CTE) that is the same or substantially the same as that of the at least one second layer 102. Additionally, the multilayer sintered ceramic body 98 of the present disclosure includes a nonlinear interface 104 defined by the at least one first layer 100 and the at least one second layer 102, whereby the nonlinear interface can provide improved adhesion between the layers.

[0122] The at least one second layer 102 comprises magnesium aluminate spinel (MgAl2O4). The at least one second layer 102 exhibits high mechanical strength, enhanced stiffness, high thermal conductivity, low dielectric loss, and a coefficient of thermal expansion (CTE) that is the same or substantially the same as that of the at least one first layer 100. The at least one first and second layers having CTE values ​​within the ranges disclosed herein provide for the preparation of multilayer sintered components with large dimensions (100 mm to about 625 mm, including 122 mm, 222 mm, 322 mm, and 522 mm). Additionally, methods for preparing such corrosion-resistant multilayer sintered ceramics and their use in plasma processing chambers are disclosed.

[0123] In some embodiments (not shown in FIG. 2 ), a third layer may be present opposite the at least one first layer 100, and may comprise any ceramic material whose CTE closely matches that of layers 100 and 102 as disclosed herein. By way of example, if present, the third layer may comprise at least one material selected from the group consisting of YAG, alumina, and zirconia. Preferably, the absolute value of the difference in CTE modulus between any of the at least one first layer, second layer, and third layer is between 0 and 0.75×10, as measured according to ASTM E228-17. -6 / ℃.

[0124] In one embodiment, disclosed herein is a multi-layer sintered ceramic body comprising at least one first layer comprising polycrystalline YAG, wherein the absolute value of the difference in coefficient of thermal expansion (CTE) between the at least one first layer and the at least one second layer is 0-0.6×10 / °C (measured in accordance with ASTM E228-17), and the at least one first layer and the at least one second layer form a single multi-layer sintered ceramic body.

[0125] According to one embodiment, a multilayer single-sintered ceramic body may be formed from at least one first layer and a second layer having an absolute value of the difference in CTE in an amount of 0 to 0.5×10 / °C, preferably 0 to 0.45×10 / °C, preferably 0 to 0.4×10 / °C, preferably 0 to 0.35×10 / °C, preferably 0 to 0.3×10 / °C, preferably 0 to 0.25×10 / °C, preferably 0 to 0.2×10 / °C, preferably 0 to 0.15×10 / °C, preferably 0 to 0.1×10 / °C, preferably 0 to 0.08×10 / °C, preferably 0 to 0.06×10 / °C, preferably 0 to 0.04×10 / °C, preferably 0 to 0.02×10 / °C, preferably 0 to 0.01×10 / °C. When the CTE between the at least one first layer 100 and the at least one second layer 102 varies within these ranges, more specifically, when the CTE between the at least one first layer 100 and the at least one second layer 102 varies over a temperature range of 25 to 1700°C or a temperature range of 200 to 1400°C as measured in accordance with ASTM E228-171, a single multilayer sintered ceramic body, particularly one with large dimensions (>100 mm to approximately 625 mm), can be formed with high strength and high adhesion between layers. Due to the isotropic properties of the ceramic materials comprising the at least one first layer and the at least one second layer disclosed herein, the term "coefficient of thermal expansion (CTE)" as used herein can interchangeably refer to either linear or volumetric CTE. Preferably, the difference in CTE between the at least one first layer 100 and the at least one second layer 102 is minimized to reduce interfacial stress between the layers. A difference in CTE between the at least one first layer 100 and the at least one second layer 102 greater than those disclosed herein may lead to fracture and / or cracking.

[0126] With further reference to FIG. 2 , multilayer sintered ceramic body 98 includes at least one first layer 100 having a thickness d1, and at least one second layer 102 having a thickness d2. In a preferred embodiment, d2 may comprise approximately 75% to 98% of the thickness (d1 + d2). Stresses resulting from CTE mismatch can affect the mechanical strength and integrity of the multilayer sintered ceramic body. Thus, if the absolute difference in CTE between at least one first layer 100 and at least one second layer 102 of the sintered ceramic body is too large, at least one layer of the multilayer sintered ceramic body may crack and / or break during the steps of the methods disclosed herein. This CTE difference is significant across all process temperatures, particularly at high temperatures such as those experienced during sintering, annealing, and cooling, and can result in significant interfacial stresses between the layers of the sintered body during cooling. As a result, to form a multilayer, single-sintered ceramic body with high mechanical strength, high interlayer adhesion strength, and sufficient handleability (no cracks or breakage), the CTE difference between at least one first layer 100 and at least one second layer 102 of the multilayer, sintered ceramic body is preferably within the disclosed range, and more preferably is as closely matched as possible. In a preferred embodiment, at least one first layer and at least one second layer can have respective CTEs in accordance with the disclosed method, with the absolute value of the CTE being the same or substantially the same, over a temperature range of ambient temperature (or about 200°C as disclosed in the figures) to about 1700°C (or at least 1400°C as shown in the figures). As used herein, the term "CTE match" refers to a CTE within the preferred disclosed range (0 to about 0.6×10 -6This term refers to a combination of at least one first layer 100 and at least one second layer 102 that differ in CTE by a factor of 1 / °C. In one embodiment, the at least one first layer 100 comprises polycrystalline YAG, whereby the at least one first layer 100 is CTE-matched to the at least one second layer 102 (which comprises magnesium aluminate spinel) to form a single multilayer sintered ceramic body. On a percentage basis, the combination of the at least one first layer 100 and the at least one second layer 102 may have CTE values ​​(over the temperature ranges disclosed herein) that match each other by a percentage of the at least one first layer 100 and the at least one second layer 102 (as measured relative to the at least one first layer 100) of 4% or less, preferably 3.5% or less, preferably 3% or less, preferably 2.5% or less, preferably 2% or less, preferably 1.5% or less, preferably 1% or less, and preferably 0.5% or less.

[0127] In addition to CTE matching, the multilayer sintered ceramic body preferably has high thermal conductivity for use as a component in a semiconductor plasma processing chamber. The at least one second layer 102 containing magnesium aluminate spinel significantly influences the properties of the single multilayer sintered body. High thermal conductivity of the at least one second layer 102 is an important material property for effectively dissipating heat and thereby avoiding localized overheating within the at least one second layer during use. This localized overheating could result in cracking or fracture of the single multilayer sintered body.

[0128] Additionally, the use of compounds known to form glass (such as magnesia, silica, and calcia) as sintering aids in the at least one second layer 102 can result in a low thermal conductivity glass phase present between the grains, thus adversely affecting thermal conductivity. As a result, in some embodiments, the at least one second layer 102 preferably comprises magnesia and / or calcia in the range of about 2-100 ppm, preferably about 2-75 ppm, preferably about 2-50 ppm, preferably about 2-25 ppm, preferably about 2-20 ppm, preferably about 2-10 ppm, and preferably about 8 ppm, by weight of the second layer, as measured using ICPMS techniques. In further embodiments, the at least one second layer 102 may comprise silica in an amount between about 14 ppm and 100 ppm, preferably between about 14 ppm and about 75 ppm, more preferably between about 14 ppm and about 50 ppm, preferably between about 14 ppm and about 30 ppm, preferably about 14 ppm (as measured using ICPMS), based on the weight of the at least one second layer 102. A second layer 102 comprising a sintering aid within the disclosed ranges can provide a multilayer sintered ceramic body that is free or substantially free of glass phase, providing high thermal conductivity in the multilayer sintered ceramic body.

[0129] Thermal conductivities were calculated from thermal diffusivity measurements performed in accordance with ASTM E1461-1. In an embodiment, the at least one second layer 102 containing about 16% by volume zirconia was calculated to have a thermal conductivity of about 25 W / mK at ambient temperature and about 14 W / mK at 200°C. When the at least one second layer 102 is used as a plasma-facing layer in a plasma processing chamber, the at least one second layer 102 preferably contains zirconia in an amount of about 10 to about 25% by volume, relative to the volume of the at least one second layer 102, to provide sufficient thermal conductivity for use, for example, as a dielectric or RF window or lid and other components in the plasma processing chamber disclosed herein that require high thermal conductivity. However, if the at least one second layer is a support layer for the spinel and faces away from the plasma in the plasma processing chamber to support the YAG layer facing the plasma, the at least one second layer 102 preferably contains zirconia in a volumetric amount of about 0.1 to about 1% relative to the volume of the at least one second layer 102. As described below, this is to reduce grain growth of the spinel during sintering without substantially affecting the CTE of the spinel. Embodiments described herein that use YAG as the plasma-facing layer may contain a minimal amount of zirconia, but it is so small that it has only a negligible effect on the CTE of the YAG. Thus, the spinel and YAG have CTEs close to each other, as shown in FIG. 16.

[0130] Low dielectric loss is preferred, especially in RF applications, to further prevent localized hot spots and overheating during use. Dielectric loss can be affected by material properties such as grain size and the presence of impurities, sintering aids, and / or dopants. The presence of impurities and / or sintering aids and / or dopants, particularly silica, in the at least one second layer 102 can result in higher dielectric loss. The use of high purity / low impurity content starting powders and methods that maintain purity results in at least one second layer 102 with high overall purity and correspondingly low overall impurity content. Thus, in embodiments, the disclosed at least one second layer 102 may have a total impurity content, as measured using ICPMS, of 5-200 ppm, preferably 5-150 ppm, preferably less than 100 ppm, preferably less than 50 ppm, preferably less than 25 ppm, preferably less than 15 ppm, preferably 10-100 ppm, preferably 10-80 ppm, preferably 10-60 ppm, preferably 10-40 ppm, preferably 20-80 ppm, preferably 30-60 ppm, based on the weight of the at least one second layer. In embodiments, the at least one second layer 102 is formed from a calcined powder mixture comprising silica in an amount of about 14-100 ppm, preferably about 14-75 ppm, preferably about 14-50 ppm, preferably about 14-25 ppm, preferably about 14 ppm, based on the total weight of the calcined powder mixture. In embodiments, the at least one second layer 102 may include magnesia (MgO) in an amount of about 2 to 100 ppm, preferably about 2 to 75 ppm, preferably about 2 to 50 ppm, preferably about 2 to 25 ppm, preferably about 2 to 20 ppm, preferably about 2 to 10 ppm, preferably about 8 ppm, based on the weight of the at least one second layer 102, as measured using ICPMS methods.

[0131] The total impurity content of the at least one second layer 102 containing calcia, silica, and magnesia in the amounts disclosed herein is less than 0.7×10 at a frequency of 1 MHz at ambient temperature as measured according to ASTM D150, as listed in Table 3. -4The at least one second layer 102 has a dielectric loss of less than 100 ppm. In embodiments, the at least one second layer 102 is free or substantially free of the dopants and / or sintering aids disclosed herein. The term "free," as used herein with respect to the levels of dopants, sintering aids, and other compounds, indicates that they are present in an amount of about 2 ppm or less as determined by the ICPMS method disclosed herein. The at least one second layer 102 disclosed herein provides a low dielectric loss suitable for use as a chamber component, particularly as a component for use in a high frequency RF plasma processing chamber.

[0132] Plasma processing chambers for semiconductor device fabrication are being designed to accommodate substrates with ever-increasing diameters, requiring chamber components with correspondingly large dimensions. These chamber components fabricated from the multilayer sintered ceramic bodies disclosed herein can have maximum dimensions of, for example, 100 to about 625 mm, preferably 100 to 622 mm, preferably 200 to about 625 mm, preferably 300 to about 625 mm, preferably 400 to about 625 mm, preferably 500 to about 625 mm, preferably 300 to 622 mm, preferably 400 to 622 mm, or preferably 500 to 622 mm. Many materials that offer resistance to corrosion and erosion are known to be difficult to sinter, resulting in low density and correspondingly low sintered strength, which can fracture or crack. This makes fabricating large monolithic solid body components from these corrosion-resistant materials difficult, and in many cases, impractical. Therefore, to enable the fabrication of large chamber components, a high-strength material (compatible with the corrosion-resistant materials disclosed herein) is needed to form the at least one second layer 102. The at least one second layer 102 provides the mechanical strength and rigidity to the single multilayer corrosion-resistant sintered body disclosed herein. The at least one second layer 102 may be sintered to a very high density, and in embodiments, may be sintered to a sufficiently high density body that provides the mechanical strength and rigidity necessary to fabricate large-sized multilayer sintered bodies, e.g., having a maximum dimension of 100 to about 625 mm, preferably 100 to 622 mm, preferably 200 to about 625 mm, preferably 300 to about 625 mm, preferably 400 to about 625 mm, preferably 500 to about 625 mm, preferably 300 to 622 mm, preferably 400 to 622 mm, preferably 500 to 622 mm.

[0133] During use in semiconductor reactors under vacuum conditions, corrosion-resistant multilayer components fabricated from the multilayer sintered ceramic bodies disclosed herein may be subjected to bending stresses spanning component dimensions exceeding 500 mm. High strength and increased stiffness / Young's modulus properties may be necessary for materials for use in the components disclosed herein to be applied to large-scale etching and / or deposition chambers. The bending strength of 98% dense aluminum oxide is reported to be approximately 375 MPa, and the stiffness (elastic modulus / Young's modulus) is reported to be approximately 350 GPa (Coorstek Advanced Alumina data sheet, available online). The at least one second layer 102 disclosed herein can provide a mechanical strength and stiffness / Young's modulus that approximately equals or exceeds that of alumina, while providing the required CTE matching the at least one first layer 100. The use of at least one second layer 102 disclosed herein can significantly improve the bending strength and stiffness of a single multi-layer component fabricated from the multi-layer sintered ceramic body, enabling the fabrication of large (>100-625 mm size) components with both high strength, stiffness, and resistance to halogen-based corrosion and erosion required for use in semiconductor plasma processing chambers.

[0134] 0.6 x 10 over the temperature range from ambient to sintering and annealing temperatures -6 / °C or less, preferably 0.55 × 10 -6 / °C or less, preferably 0.5 × 10 -6 By selecting materials for the at least one first layer 100 and the at least one second layer 102 having an absolute value of the difference in CTE of the layers of 0.1 / °C or less and within the ranges disclosed herein, a single multi-layer sintered ceramic body 98 can be formed having the high strength and stiffness, corrosion resistance, and favorable dielectric and thermal properties disclosed herein.

[0135] To provide corrosion and erosion resistance suitable for use as a component in a plasma processing chamber, it may be desirable to fabricate a polycrystalline single-layer ceramic body having at least one first layer 100 containing highly phase-pure polycrystalline YAG (>90% by volume). However, forming substantially phase-pure YAG may require careful compositional and processing control to maintain stoichiometry and thus form a sintered ceramic body containing phase-pure YAG (with a composition of 37.5 + / - 0.1 mol% yttrium oxide and 62.5 + / - 0.1 mol% aluminum oxide). In many cases, other crystalline phases, such as alumina, yttria, YAP (YAlO3; yttrium aluminum perovskite phase), and YAM (YAlO9; yttrium aluminum monoclinic phase), and combinations thereof, may also be present. For reference, Figure 3 shows a binary phase diagram for yttrium oxide / aluminum oxide. The horizontal axis corresponds to the mixture ratio (mol%) of yttria and alumina, and the vertical axis is temperature (°C). The left side of the horizontal axis corresponds to 100% alumina, and the right side corresponds to 100% yttria. The phase diagram in Figure 3 shows the regions where the yttrium aluminum oxide phases of YAG, YAP, and YAM form, as well as the molar composition and temperature conditions required to produce these forms.

[0136] Crystalline phase and image-based porosity measurements of at least one first layer 100 comprising YAG in a multilayer ceramic sintered body according to one embodiment disclosed herein were performed using a combination of X-ray diffraction (XRD), SEM imaging, and the use of image processing software (ImageJ). XRD was performed using a PANanlytical Aeris model XRD, which is capable of crystalline phase identification down to approximately + / - 5% by volume. Figure 4 shows X-ray diffraction results confirming the formation of highly phase-pure polycrystalline YAG comprising at least one first layer 100 according to this embodiment. No other phases were identified within the detection limits of XRD. YAG exists as a linear compound according to known phase diagrams; therefore, the formation of phase-pure YAG poses challenges and requires careful compositional and process control. Such phase-pure YAG is disclosed in International Patent Application No. PCT / US20 / 60918, filed November 17, 2020, which is incorporated herein by reference. The YAG-containing at least one first layer 100 according to this embodiment may, in some embodiments, contain excess alumina and / or excess yttria, may be substantially free of dopants, or may contain no dopants, and / or may be substantially free of sintering aids or may contain no sintering aids disclosed herein. In other embodiments, the YAG-containing first layer may contain sintering aids and / or dopants in the amounts disclosed herein. In embodiments, the polycrystalline YAG first layer 100 may be substantially free of dopants, or may contain no dopants, and may contain sintering aids in the amounts disclosed herein. XRD of the at least one first layer 100 of the multilayer ceramic sintered bodies disclosed herein may measure a phase purity of about 95% by volume or less. Thus, the at least one first layer 100 of a single multilayer sintered ceramic body may contain at least about 95% by volume of YAG phase according to this embodiment, as shown in the XRD results in FIG. 4.

[0137] To determine the phase purity with greater precision, for example, up to about 99.8% by volume, SEM images were taken using backscattering detection (BSD) techniques known to those skilled in the art. Using BSD, the YAG phase appears gray, the aluminum oxide phase appears black, and the yttrium oxide phase appears white, and porosity, if present, also appears black. For the polycrystalline YAG sintered ceramic body according to Example 2, images were taken at 5000x magnification using BSD to identify the YAG, alumina, and yttria phases, as well as any porosity present, as shown in FIG. 6a).

[0138] To distinguish between black regions containing alumina and black regions containing porosity, the BSD image was processed with black and white thresholds using ImageJ processing software to highlight black regions in the BSD image that may contain either porosity or alumina, as shown in the same region in Figure 6b. ImageJ, developed at the National Institutes of Health (NIH), is a Java-based, public-domain image processing and analysis program for image processing of scientific multidimensional images. The BSD detector used for the measurements disclosed herein has the additional capability of measuring topographic features, thereby highlighting any variations in surface topography, such as surface porosity. Using the topography mode of the BSD detector, a topographic image was taken at 5000x magnification across the surface of the same region of the polycrystalline YAG sintered ceramic body according to Example 2 as shown in Figure 5a. The topographic image is shown in Figure 6a. After thresholding the topographic image in ImageJ, the region containing surface porosity was highlighted, as shown in Figure 6b. The area containing surface porosity in the topography image of FIG. 6b) was then subtracted from the area containing alumina and / or porosity in the BSD image of FIG. 6a) to obtain the area % and, therefore, volume % containing alumina phase in the polycrystalline YAG sintered ceramic body according to Example 2. The combination of these analytical tools, multiple SEM imaging modes and ImageJ analysis, can provide a determination of phase purity with a confidence level of about + / - 0.1 vol%. Using the disclosed method, the polycrystalline YAG sintered ceramic body according to Example 7 was determined to contain about 0.1 to about 0.2 vol% alumina phase, about 0.1 to about 0.2 vol% porosity, and about 99.6 to about 99.8 vol% YAG phase. Taking into account measurement variability, the polycrystalline YAG-sintered ceramic body can include a YAG phase in an amount of 99.4 to 99.8 volume percent, and can further include porosity in an amount of 0.1 to 0.3 volume percent, and aluminum oxide in an amount of 0.1 to about 0.3 volume percent.

[0139] Thus, a multilayer sintered ceramic body having at least one first layer 100 each containing YAG phase in an amount of 90-99.9 volume %, preferably 90-99.8 volume %, preferably 90-99.7 volume %, preferably 90-99.6 volume %, preferably 93-99.8 volume %, preferably 93-99.7 volume %, preferably 93-99.6 volume % of the at least one first layer 100 can be formed using the materials and methods disclosed herein.

[0140] To meet the corrosion and erosion resistance requirements for use as a component in a semiconductor processing chamber, a multilayer sintered ceramic body including at least one first layer 100 with low porosity across its surface 106 and / or within the layer 100 is preferred. Porosity can serve as an initiation site for corrosion and erosion, and therefore, minimal to no porosity, pores, or voids are preferred within the at least one first layer 100 of the multilayer sintered body and / or on the surface 106 of the first layer 100. The at least one first layer disclosed herein can have very small pores both on the surface and throughout. Thus, preferably, the at least one first layer 100 comprising polycrystalline YAG produced according to the processes disclosed herein is a monolithic layer with pores uniformly distributed throughout. In other words, the pores, voids, or porosity measured on the surface 106 can represent the pores, voids, or porosity within the bulk of the at least one first layer 100.

[0141] Porosity was measured using the method disclosed below.

[0142] Porosity measurement

[0143] The level of porosity was measured across the sample surface using SEM images acquired at 5000x magnification from a Phenom XL scanning electron microscope. Images were imported into ImageJ software for analysis. ImageJ, developed at the National Institutes of Health (NIH), is a Java-based, public domain image processing and analysis program for the processing of scientific multidimensional images.

[0144] Using the ImageJ software method disclosed herein, the pore size and total area including porosity was measured across seven SEM images. 2 Images were taken at 5000x magnification, each with a total area of ​​approximately 53.7 μm × 53.7 μm, corresponding to a single image measurement area of ​​10 μm.

[0145] To evaluate the grain size of the at least one first layer 100 containing polycrystalline YAG, linear intercept grain size measurements were performed according to the Heyn Linear Intercept Procedure described in ASTM Standard E112-2010, "Standard Test Method for Determining Average Grain Size." Grain size measurements (as described in Table 1 below) were performed, measuring an average grain size of 1.1 to 6.3 μm over 25 replicates. Maximum and minimum grain sizes of 2 to 7.7 μm were also measured on the surface 106 of the at least one first layer 100 containing YAG. A single multilayer sintered ceramic body can have, for example, a surface 106 having a maximum grain size of about 8 μm or less, preferably a maximum grain size of 6 μm or less. In an embodiment, the single multi-layer sintered ceramic body may have a surface 106 having an average grain size of 0.4 to 6.5 μm, preferably 0.4 to 5 μm, preferably 0.4 to 3 μm, preferably 0.8 to 6.5 μm, preferably 0.8 to 5 μm, preferably 0.8 to 3 μm, preferably 1 to 7 μm, preferably 1 to 6.5 μm. [Table 1]

[0146] FIG. 7 shows the results of the porosity measured on the surface 106 of the at least one first layer 100 containing YAG, with the total pore area (um) plotted on the vertical axis. 2 ) where the horizontal axis represents the pore size in micrometers. Measurements were taken over seven images taken at 5000x magnification, with each image measuring approximately 2885 μm 2 The total area including porosity in any one of the seven images was approximately 0.015 to approximately 0.3 μm. 2 , preferably about 0.015 to about 0.2 μm 2 , preferably about 0.015 to about 0.15 μm 2 The maximum pore size on the surface 106 of the at least one first layer 100 containing YAG of 0.7 μm or less was measured, and the maximum area containing porosity was measured as approximately 0.3 μm. 2 It was found that: Across the seven images analyzed in the polycrystalline YAG of at least one first layer 100, no pores with a pore size greater than 0.7 μm were measured.

[0147] Figure 8 shows the 2 μm over unit area 2 The cumulative fractional area with unit porosity (cumulative pore area) is shown, and the cumulative pore area (μm) for a given pore size for the seven images referenced in Figure 7. 2 / mm 2 Porosity is measured within each image (μm) using SEM images and the ImageJ image processing method disclosed herein. 2 units), measured total image area (mm 2 ) to calculate the cumulative pore area. At least one first layer 100 comprising YAG as disclosed herein has a cumulative pore area of ​​about 2 to about 800 μm as measured using SEM and image processing methods as disclosed herein. 2 / mm 2 , preferably about 2 to about 600 μm 2 / mm 2 , preferably about 2 to about 400 μm2 / mm 2 , preferably about 2 to about 300 μm 2 / mm 2 The image includes a cumulative pore area of ​​100 μm. Across seven images analyzed in a YAG of at least one first layer 100 of a multilayer sintered ceramic body, no pores with a pore size greater than 0.6 μm were measured. Thus, across seven images, each approximately 54 μm by 54 μm in area, the multilayer sintered ceramic body disclosed herein has at least one first layer 100 with a surface 106 that includes very low (<0.1 area%) porosity corresponding to an area percentage of pores less than 1 μm in size, thus providing a corrosion- and erosion-resistant surface for the multilayer sintered ceramic body for use in a plasma processing chamber.

[0148] FIG. 9a) shows a 5000x SEM image of the surface 106 of at least one first layer 100 comprising a polycrystalline YAG phase, showing a dense sintered microstructure after a thermal etching process. Very fine-scale porosity with almost no pores is evident on the surface 106 of the at least one first layer 100 of YAG. A nearly fully dense microstructure is shown, with minimal porosity and pore sizes of about 1 μm or less. A multilayer sintered ceramic body according to one embodiment includes at least one first layer 100 comprising polycrystalline YAG having a surface 106 comprising pores, the pores having a pore size of about 5 μm or less, and a submicron-scale pore size of about 0.1 to about 5 μm, preferably about 0.1 to about 4 μm, preferably about 0.1 to about 3 μm, preferably about 0.1 to about 2 μm, and preferably about 0.1 to about 1 μm. According to one embodiment disclosed herein, at least one first layer 100 comprising YAG of a multilayer sintered ceramic body 98 formed from the materials and processes may contain pores having a maximum size of 0.1-5 μm, preferably 0.1-4 μm, preferably 0.1-3 μm, preferably 0.1-2 μm, and 0.1-1 μm, as measured using SEM and image processing methods disclosed herein. Approximately 22 pores were counted over a surface area of ​​54 μm x 54 μm.

[0149] FIG. 9b) shows the sum of the total surface area including pores or porosity (% of surface area) for each of the seven SEM images measured for FIG. 8 on the vertical axis, while the horizontal axis represents the corresponding pore size for a given % pore area in microns. Within a given image, the total area including porosity and the total image measured area were used to calculate the % pore area. As shown in FIG. 9, the measurements across the seven SEM images correspond to at least one first layer 100 having a surface 106 including YAG, where YAG is present in an amount of 0.0005-2%, preferably 0.0005-1%, preferably 0.0005-0.5%, preferably 0.0005-0.05%, and preferably 0.0005-0.05%, as measured from the SEM images and using the ImageJ software and methods disclosed herein. 0.03%, preferably 0.0005-0.005%, preferably 0.0005-0.003%, preferably 0.0005-0.001%, preferably 0.005-2%, preferably 0.05-2%, preferably 0.5-2%, preferably 0.005-2%, preferably 0.005-1%, preferably 0.05-2%, preferably 0.05-1%, preferably 0.5-2%. Thus, over an area of ​​approximately 54 um x 54 um each, the multilayer sintered ceramic bodies disclosed herein include a surface 106 that includes a very low (<1% by total area) percentage porosity, thus providing a corrosion- and erosion-resistant surface for the multilayer sintered ceramic body 98 for use in a plasma processing chamber.

[0150] Density measurements of multilayer bodies containing multiple phases have proven difficult due to differences in the intrinsic densities of the phases. Density measurements were performed on multilayer sintered ceramic body samples by sectioning a sample through the full thickness of the multilayer sintered body into its respective layers and performing separate density measurements on each layer. Measurements were performed according to the Archimedes immersion method of ASTM B962-17, and a density of approximately 4.57 g / cc was measured for at least one first layer 100 of YAG. The reported density value is an average over five measurements. A commercially available single crystal sample of bulk YAG was measured for density using the method disclosed herein. An Archimedes density of 4.56 g / cc was obtained over five measurements, and this value is the theoretical density of YAG used herein. Thus, at least one first layer 100 of the multilayer sintered ceramic body containing YAG according to embodiment B has a density of 99 to 100%, preferably 99.5 to 100%, preferably 99.7 to 100%, preferably about 100% of the theoretical density of YAG.

[0151] The relative density (RD) of a given material is defined as the ratio of the measured density of the sample to the reported theoretical density of the same material, as shown in the following equation: Volume porosity (Vp) is calculated from the density measurements as follows:

number

[0152] These density, purity, and porosity levels can provide improved resistance to the effects of erosion and corrosion resulting from plasma etching and deposition processes. The disclosed methods and materials are particularly useful for preparing sintered ceramic bodies with large dimensions, e.g., maximum dimensions of 200-625 mm. The high density and resulting high mechanical strength of the sintered ceramic bodies also provide improved handleability, especially in large dimensions. Successful fabrication of sintered yttrium aluminum oxide bodies or multilayer bodies comprising sintered yttrium aluminum oxide, particularly bodies formed from phase-pure YAG in the ranges disclosed herein across their longest dimension (approximately 200-625 mm), can be enabled by controlling the variation in density across at least one longest dimension. Average densities of 98.5% or greater and 99.5% or greater can be achieved with a density variation of 5% or less, preferably 4% or less, preferably 3% or less, preferably 2% or less, and preferably 1% or less across the largest dimension, whereby the largest dimension can be, for example, about 625 mm or less, 622 mm or less, 610 mm or less, preferably 575 mm or less, preferably 525 mm or less, preferably 100-625 mm, preferably 100-622 mm, preferably 100-575 mm, preferably 200-625 mm, preferably 200-510 mm, preferably 400-625 mm, preferably 500-625 mm. Reducing density variation can improve handleability and reduce stress throughout the ceramic sintered body. This combination of fine grain size, uniformity, and high density provides a high-strength sintered YAG-containing layer for large-sized multilayer sintered ceramic bodies suitable for machinability, handling, and use as components in semiconductor processing chambers. Density measurements can be made in accordance with ASTM B962-17 across the largest dimension of the sintered body.

[0153] The high-density polycrystalline YAG-containing at least one first layer can enable a high hardness value for the plasma-facing at least one first layer, which can provide resistance to the erosive effects of ion bombardment used during typical plasma processes. Erosion or spalling can result from ion bombardment of component or layer surfaces due to the use of inert plasma gases such as Ar. These materials with high hardness values ​​may be preferred for use as materials for components due to their improved hardness values, which provide greater resistance to ion bombardment and resulting erosion. Therefore, Vickers hardness measurements were performed on the at least one polycrystalline YAG-containing first layer 100 in accordance with ASTM Standard C1327, "Standard Test Method for Vickers Indentation Hardness of Advanced Ceramics." The testing equipment used for all hardness measurements was a Wilson Micro Hardness Tester Model VH1202. Hardness values ​​of at least 1200 HV, preferably at least 1400 HV, preferably at least 1800 HV, preferably at least 2000 HV, 1300-1600 HV, 1300-1500 HV, 1300-1450 HV, 1300-1400 HV, 1400-1600 HV, 1450-1600 HV, and 1450-1550 HV have been measured for at least one first layer 100 of a multilayer sintered ceramic body 98 disclosed herein. Measurements were made using the Vickers hardness method known in the art and converted to SI units of GPa. Hardness values ​​of 12.75 to 15.69 GPa, 12.75 to 14.71 GPa, 12.75 to 14.22 GPa, 12.75 to 13.73 GPa, 13.73 to 15.69 GPa, 14.22 to 15.69 GPa, preferably 14.22 to 15.20 GPa were measured.

[0154] The surface roughness of at least one first layer can affect performance in semiconductor processing chambers. Surface roughness measurements were performed using a Keyence 3D laser scanning confocal digital microscope, model VK-X250X, under Class 1 cleanroom environmental conditions. The microscope was mounted on a TMC Tabletop CSP benchtop passive vibration isolation platform with a natural frequency of 2.8 Hz. This non-contact system uses a laser beam and an optical sensor to analyze the surface based on the intensity of the reflected light. Surface roughness characteristics Sa and Sz are well-known parameters in the underlying technical field and are described, for example, in ISO Standard 25178-2-2012. Section 4.17 of the ISO standard describes surface roughness Sa, Section 4.1.6 describes Sz, and Section 4.3.2 describes Sdr. ISO 25178 Surface Texture (Areal Roughness Measurement) is an international standard related to the analysis of surface roughness, and this microscope complies with it. Sa is the average roughness value calculated over a user-defined area (arithmetic mean height of the scale-limited surface) of the surface of the multilayer sintered ceramic body. Sz represents the maximum peak-to-valley distance (maximum height of the scale-limited surface, peak-to-valley) over a user-defined area of ​​the surface of the multilayer sintered ceramic body. Sdr is a calculated numerical value defined as the "Developed Interfacial Area Ratio," which is a proportional representation of the increase in actual surface area relative to a perfectly flat surface. A flat surface is assigned an Sdr of 0, and the value increases with the slope of the surface. A larger numerical value corresponds to a larger increase in surface area. This allows for a numerical comparison of the extent of surface area increase of the sample. It represents the additional surface area resulting from texture or surface features compared to a flat area.

[0155] Detailed images of the sample were captured using a laser scan of the sample surface at 50x magnification using a confocal microscope. The parameters Sa (arithmetic mean height), Sz (maximum height), Ra (line roughness), and Sdr (interfacial development area) were measured in selected areas of the polished surface of at least one layer 100 of a multilayer sintered ceramic body. Roughness was obtained from profiles of seven segmented blocks. The measurement sampling length, lambda chi (λ), was adjusted to limit line readings to measurements from five of the seven central blocks, in accordance with ISO standard 4288: Geometrical Product Specifications (GPS)—Surface texture: Profile method—Rules and procedures for the assessment of surface texture. Surface areas were selected within the polished surface of the sample for measurement. Regions were selected to be most representative of a typical sample surface and used to calculate Ra, Sz, and Sdr.

[0156] According to one embodiment, wherein the at least one first layer comprises YAG, the surface roughness measurement is performed in accordance with ISO standard 25178-2-2012 and is within the range of 0.0005 to 2 μm, preferably 0.0005 to 1.5 μm, preferably 0.0005 to 1 μm, preferably 0.0005 to 0.75 μm, preferably 0.0005 to 0.5 μm, preferably 0.0005 to 0.25 μm, preferably 0.0005 to 0.125 μm across the surface. Sa values ​​of 0.0005-0.075 μm, preferably 0.0005-0.050 μm, preferably 0.0005-0.025 μm, preferably 0.0005-0.020 μm, preferably 0.0005-0.015 μm, preferably 0.0005-0.010 μm, preferably 0.001-0.030 μm, preferably 0.001-0.020 μm, preferably 0.001-0.010 μm have been measured. Table 1 below lists Sa, Sz, and Sdr values ​​for at least one first layer 100 including a surface 106 comprising YAG according to embodiments disclosed herein.

[0157] [Table 2]

[0158] Thus, the at least one first layer 100 comprising YAG of the multilayer sintered ceramic body according to one disclosed embodiment has a thickness of 0.0005 to 2 μm, preferably 0.0005 to 1.5 μm, preferably 0.0005 to 1 μm, preferably 0.0005 to 0.75 μm, preferably 0.0005 to 0.5 μm, preferably 0.0005 to 0.25 μm, preferably 0.0005 to 0.125 μm, as measured according to ISO Standard 25178-2-2012. , may have a surface 106 having a surface roughness Sa of preferably 0.0005 to 0.075 μm, preferably 0.0005 to 0.050 μm, preferably 0.0005 to 0.025 μm, preferably 0.0005 to 0.020 μm, preferably 0.0005 to 0.015 μm, preferably 0.0005 to 0.010 μm, preferably 0.001 to 0.030 μm, preferably 0.001 to 0.020 μm, preferably 0.001 to 0.010 μm.

[0159] According to Table 1, the at least one first layer 100 comprising YAG of a multilayer sintered ceramic body according to one embodiment may have a surface 106 with a peak-to-valley Sz of 0.3 to 5 μm, preferably 0.3 to 4 μm, preferably 0.3 to 3 μm, preferably 0.3 to 2 μm, preferably 0.3 to 1 μm, preferably 0.65 to 5 μm, preferably 1 to 5 μm, preferably 2 to 5 μm, preferably 0.35 to 3 μm, preferably 0.5 to 1 μm, as measured according to ISO Standard 25178-2-2012.

[0160] According to Table 1, the at least one first layer 100 comprising YAG of the multilayer sintered ceramic body according to the disclosed embodiment has a thermal conductivity of 5×10 s, as measured according to ISO standard 25178-2-2012. -5 ~550×10 -5 , preferably 30 x 10 -5 ~400×10 -5 , preferably 30 x 10 -5 ~200×10 -5 , preferably 40 x 10-5 ~100×10 -5 The surface 106 may have a developed interfacial area Sdr of

[0161] color

[0162] Referring again to Figure 2, another advantage of the sintered ceramic bodies disclosed herein is the color of the surface 106. As used herein, "color" is determined using the 1976 CIELAB color space, which reduces color to a lightness / darkness variable, L* (absolute black is 0 and perfect white is 100), and other parameters, a* and b*, that describe the hue of an object. Typically, an object having an L* greater than 65 and absolute values ​​of a* and b* less than 5 is considered "white."

[0163] The presence of certain elements or contaminants on the plasma-facing surface and in the at least one first layer may be undesirable for use in a plasma processing reactor chamber. Exposure to these contaminants during semiconductor processing can, for example, cause chamber contamination. These contaminants typically appear as dark spots or regions. For example, transition metal elements such as Fe, Co, Cr, V, Zn, Mn, Ni, and Cu are undesirable due to their diffusion in silicon, as they are likely to alter electrical properties. Oxides such as oxides of Li, Na, and K also readily diffuse into silicon and can affect performance at the device level. Therefore, easy detection of contaminants is desirable, and therefore, a lighter component color is preferred, as spots are more clearly visible. Therefore, to enable easy detection of contaminants, a plasma-facing surface with a high L* value, preferably at least one first layer with a white surface, is advantageous so that dark spots are easily visible and unacceptable parts or components can be discarded before use.

[0164] However, ceramics with L* values ​​of 90 or greater typically indicate materials with significant porosity. Porosity in the at least one first layer is undesirable for plasma processing applications because it can serve as initiation sites for corrosion and erosion by the halogen-based plasma used in the processing, leading to the subsequent release of contaminant particles into the reactor chamber.

[0165] Furthermore, surfaces with an L* value of 90 or greater, as disclosed in U.S. Patent Application Publication No. 2017 / 0250057, can interfere with endpoint signal detection in plasma etching processes. Interference with endpoint signal detection can lead to erroneous readings of the etching process status and potentially result in defective products. Therefore, a lower L* value, and therefore a darker surface for the plasma-facing surface, is preferred to overcome endpoint signal detection interference and prevent particle emissions into the chamber.

[0166] On the other hand, a component surface that is too dark makes it difficult to easily detect dark spots because the brightness or color of the dark spots and the component surface are similar enough that the spots are not easily visible to the eye, which makes it difficult to sort out unacceptable parts or components.

[0167] The plasma-facing surface 106 of embodiments of the multilayer sintered ceramic body of the present disclosure exhibits an L* value, measured on the plasma-facing surface of at least one first layer, of less than 90, preferably less than 82, preferably between 65 and 82, preferably between 70 and 82, and more preferably between 75 and 80. In other embodiments, the plasma-facing surface 106 of embodiments of the multilayer sintered ceramic body of the present disclosure exhibits an L* value, measured on the plasma-facing surface of at least one first layer, of 65-90, preferably between 65 and 89, preferably between 70 and 82, preferably between 65 and 82, preferably between 70 and 82, and more preferably between 75 and 80.

[0168] At least one first layer 100 having a plasma-facing surface 106 with an L* value within the above interval combines two effects: it is easy to detect dark spots or contaminants on the plasma-facing surface and in the at least one first layer of the sintered body or component manufactured therefrom; and it is possible to accurately detect the endpoint signal of the etching process while minimizing particle emissions into the chamber.

[0169] In one embodiment, components made from the multi-layer sintered ceramic bodies of the present invention, such as windows, disks, and showerheads, are characterized as having at least one first layer having an L* of 65 to 85, as disclosed herein. In another embodiment, components made from the multi-layer sintered ceramic bodies of the present invention, such as windows, disks, and showerheads, are characterized as having at least one first layer having an L* of 65 to 82, as disclosed herein. In another embodiment, components made from the multi-layer sintered ceramic bodies of the present invention, such as windows, disks, and showerheads, are characterized as having at least one first layer having an L* of 65 to 75, as disclosed herein.

[0170] Uniformity and brightness may be assessed visually by eye or measured using commercially available equipment, such as, as one non-limiting example, the FRU WR-18 colorimeter, which uses the CIELAB L*a*b* scale. CIELAB L*a*b* values ​​are also referred to interchangeably herein as CIE Lab values ​​or L*, a*, b* values. The "L*" value indicates the lightness-to-darkness ratio, or in other words, the shade. The "a*" and "b*" values ​​generally relate to hue. The "a*" value refers to the red-green coordinate in a particular transformed color space and is commonly used as the "a*" difference between a specimen and a standard reference color. If "a*" is positive, there is more red than green. If "a*" is negative, there is more green than red. The a* value is typically used with b* as part of chromaticity or chromatic color difference. The "b*" value refers to the yellow-blue coordinate in a particular color space and is commonly used as the difference in "b*" between a test sample and a standard reference color, usually used in conjunction with "a*" or as part of the chromaticity difference. Generally, if "b*" is positive, there is more yellow than blue. If "b*" is negative, there is more blue than yellow.

[0171] Etching Procedure:

[0172] To evaluate performance in halogen-based plasma applications, etching was performed on sintered ceramic bodies prepared according to embodiments including at least one first layer 100 of YAG, as described below.

[0173] To evaluate the etching performance, polished ceramic samples with a surface containing a first layer of YAG measuring 6 mm × 6 mm × 2 mm were mounted on a c-plane sapphire wafer using a silicone-based heat sink compound. Areas of each section were blocked from exposure to the etching process by bonding a 5 mm × 5 mm square piece of sapphire ceramic to the sample surface.

[0174] The dry etching process was performed using industry-standard equipment, a Plasma-Therm Versaline DESC PDC Deep Silicon Etch. Etching was completed using a two-step process for a total duration of six hours. The etching method was performed using a pressure of 10 millitorr, a bias of 600 volts, and an ICP power of 2000 watts. The etching method was performed using a first etching step with a CF4 flow rate of 90 standard cubic centimeters per minute (sccm), an oxygen flow rate of 30 standard cubic centimeters per minute (sccm), and an argon flow rate of 20 standard cubic centimeters per minute (sccm), and a second etching step with an oxygen flow rate of 100 standard cubic centimeters per minute (sccm) and an argon flow rate of 20 standard cubic centimeters per minute (sccm). The first and second etching steps were repeated for 300 seconds each for a total duration of six hours. The etching conditions used herein to evaluate sample performance were selected to subject the disclosed materials to extreme etching conditions in order to differentiate performance. Once the etching procedure was completed, the surface roughness parameters Sa, Sz, and Sdr were measured using the methods disclosed herein. Table 2 lists the results after etching (using the two-step process as disclosed herein) for various samples having at least one first layer comprising YAG.

[0175] [Table 3]

[0176] At least one exemplary first layer 100 comprising YAG was fabricated using excess alumina (Samples 311 and 322), zirconia doping (Sample 298), stoichiometric YAG (Samples 454 and 223), and reduced relative density (RD), Sample 454-1. As set forth in Table 2, the process conditions (Process) are listed as the temperature T (°C), pressure P (MPa), and time t (min) used to fabricate each of the respective samples according to the methods disclosed herein. Annealing was performed in air at 1400°C for 8 hours.

[0177] In one embodiment, the present disclosure relates to a multilayer sintered ceramic body and / or component made therefrom having at least one first layer 100 comprising YAG, which, prior to the etching or deposition process, provides an arithmetic mean height Sa, surface roughness in the unetched areas according to Section 4.1.7 of ISO Standard 25178-2-2012 of less than 15 nm, more preferably less than 13 nm, more preferably less than 10 nm, more preferably less than 8 nm, more preferably less than 5 nm, and has a surface that does not exceed a specified value.

[0178] In one embodiment, the present disclosure relates to a multilayer sintered ceramic body and / or component made therefrom having at least one first layer 100 comprising YAG, which provides a maximum height Sz of less than 5.0 μm, more preferably less than 4.0 μm, most preferably less than 3.5 μm, more preferably less than 2.5 μm, more preferably less than 2 μm, more preferably less than 1.5 μm, prior to the etching or deposition process, according to ISO standard 25178-2-2012, and has a surface not exceeding a specified value.

[0179] In one embodiment, the present disclosure provides a multilayer sintered ceramic body and / or component made therefrom having at least one first layer 100 comprising YAG, the first layer 100 being 1500×10 sintered according to Section 4.1.7 of ISO Standard 25178-2-2012 prior to the etching or deposition process. -5 less than 1200 × 10 -5 less than 1000×10 -5 less than 800 × 10 -5 less than 600 × 10 -5 less than 400 × 10 -5 The present invention relates to a multilayer sintered ceramic body and / or a component made therefrom, having a surface that provides a developed interfacial area Sdr of less than 1000 nm and a surface roughness that does not exceed a specified value.

[0180] In one embodiment, the present disclosure relates to a multilayer sintered ceramic body and / or component made therefrom having at least one first layer comprising YAG, which, after an etching or deposition process disclosed herein, provides an arithmetic mean height Sa, surface roughness, according to Section 4.1.7 of ISO Standard 25178-2-2012, of less than 25 nm, more preferably less than 20 nm, more preferably less than 18 nm, more preferably less than 16 nm, more preferably less than 14 nm, more preferably less than 12 nm, and has a surface that does not exceed a specified value.

[0181] In one embodiment, the present disclosure relates to a multilayer sintered ceramic body and / or component made therefrom having at least one first layer comprising YAG, which, after an etching or deposition process as disclosed herein, provides a maximum height Sz, a surface roughness according to Section 4.1.7 of ISO Standard 25178-2-2012 of less than 4.8 μm, more preferably less than 3.8 μm, most preferably less than 3.2 μm, more preferably less than 2.5 μm, more preferably less than 2 μm, more preferably less than 1.5 μm, and has a surface not exceeding a specified value.

[0182] In one embodiment, the present disclosure provides a multilayer sintered ceramic body and / or component made therefrom having at least one first layer comprising YAG, the body having a porosity of 3000×10 sintered ceramic particles per Section 4.1.7 of ISO Standard 25178-2-2012 after an etching or deposition process disclosed herein. -5 less than 2500 × 10 -5 less than 2000 × 10 -5 less than 1500 × 10 -5 less than 1000×10 -5The present invention relates to a multilayer sintered ceramic body and / or components made therefrom that provides a developed interfacial area (Sdr), a surface roughness, and a surface that does not exceed a specified value, preferably less than 800×10. The use of the multilayer sintered ceramic body described above, according to one embodiment, provides a significant corrosion- and erosion-resistant material that allows for continuous, long-term use as a component in etching and deposition processes. The corrosion- and erosion-resistant material minimizes particle generation due to the improved surface properties disclosed herein, providing improved performance during use and reduced contamination of semiconductor substrates during processing.

[0183] The starting powders, powder mixtures, and fired powder mixtures used to fabricate the at least one first layer 100 have very high purity and can provide corrosion and erosion resistance that enables their use as components in semiconductor etching and deposition applications. This high purity provides a chemically inert surface (the term inert, as used herein, is intended to mean chemically inert), which can prevent the surface of the at least one first layer 100 from being roughened by halogen-based gas species that would otherwise chemically attack and etch materials made from less pure powders and powder mixtures, or be eroded by ion bombardment. Impurities and contaminants within the at least one first layer 100 can serve as initiation sites for corrosion and erosion, and therefore high purity (and corresponding low impurity content, expressed in ppm of contaminants) is preferred within the at least one first layer 100 of a multilayer, corrosion-resistant, sintered ceramic body. Table 5 lists the impurities of an exemplary fired powder mixture, according to an embodiment, that is sintered to form the at least one first layer 100 comprising substantially phase-pure polycrystalline YAG.

[0184] According to the disclosure herein, a multilayer sintered ceramic body having at least one first layer comprising an yttrium aluminum garnet (YAG) phase in an amount greater than 90% by volume can be formed by in situ reaction sintering during the sintering process due to the combined properties of particle size distribution, purity, and / or surface area of ​​the sintered powder mixture disclosed herein. In embodiments, the sintered powder mixture comprises crystalline powders of yttria and alumina. In certain embodiments, it may be preferred that, in addition to the crystalline powders of yttria and alumina, the sintered powder mixture comprises less than 10% by volume of YAG, preferably less than 8% by volume of YAG, and preferably less than 5% by volume of YAG. In other embodiments, disclosed herein are sintered powder mixtures that are free or substantially free of YAG phase (including crystalline powders of yttria and alumina). In other embodiments, the sintered powder mixture comprises 2 m 2 In other embodiments, the fired powder mixture preferably has a specific surface area of ​​greater than about 2 m / g to form a sintered ceramic body comprising YAG by the in situ reactive phase sintering process disclosed herein. 2Preferably, the powder does not contain a YAG phase having a specific surface area of ​​1 / g or greater. All purity measurements disclosed herein were measured above the reporting limit for a particular element and were performed using an Agilent 7900ICP-MS Model G8403. The liquid sample is introduced into the ICP-MS as a fine aerosol, which is ionized in a plasma discharge and then separated using a quadrupole mass analyzer known to those skilled in the art. The detection limit using the ICP-MS method disclosed herein to identify the presence of lighter elements is higher than the reporting limit for heavier elements. In other words, heavier elements, such as Sc and above, are detected with a higher precision, e.g., as low as 0.06 ppm, than lighter elements, such as Li to Al (which are detected with a lower precision, e.g., as low as 0.7 ppm). Thus, the impurity content of powders containing lighter elements, such as Li to Al, can be determined to be about 0.7 ppm or greater, and the impurity content of heavier elements, from Sc (scandium) to U (uranium), can be determined to be about 0.06 ppm or greater. Using the ICPMS method disclosed herein, silica can be detected in amounts as low as about 14 ppm, while K (potassium) and Ca (calcium) can be identified in amounts of 1.4 ppm or higher. Iron can be detected with precision in amounts as low as 0.14 ppm or higher. The total impurity content disclosed herein does not include silica.

[0185] The at least one first layer 100 comprising a YAG crystalline phase may have a total impurity content, measured using ICPMS techniques, of less than 100 ppm, preferably less than 75 ppm, preferably less than 50 ppm, preferably less than 25 ppm, preferably less than 15 ppm, preferably less than 10 ppm, preferably less than 8 ppm, preferably less than 5 ppm, preferably between 5 and 30 ppm, preferably between 5 and 20 ppm, based on the total mass of the at least one first layer comprising a YAG crystalline phase. The total impurity content disclosed herein does not include Si in the form of silica.

[0186] The detection limits using the ICP-MS methods disclosed herein to identify the presence of lighter elements are higher than the reporting limits for heavier elements. In other words, heavier elements, such as Sc and above, are detected with higher precision, e.g., as low as 0.06 ppm, than lighter elements, such as Li to Al (which are detected with precision as low as 0.7 ppm). Thus, the impurity content of powders containing lighter elements, such as Li to Al, can be determined to about 0.7 ppm or higher, and the impurity content of heavier elements, from Sc (scandium) to U (uranium), can be determined to about 0.06 ppm or higher. Using the ICP-MS methods disclosed herein, silica can be detected in amounts as low as about 14 ppm, while K (potassium) and Ca (calcium) can be identified in amounts of 1.4 ppm or higher. Iron can be detected with precision as low as 0.14 ppm.

[0187] Sintering aids such as SiO2, MgO, CaO, Li2O, and LiF are known to promote densification, and LiF in particular is known to be used to promote grain growth and thereby increase the grain size of YAG and spinel. However, these sintering aids may reduce corrosion resistance, strength, and performance in etching and deposition applications. Therefore, in embodiments, at least one first layer 100 of the multilayer sintered ceramic body disclosed herein may be formed from at least one calcined powder mixture having a calcia, magnesia, lithia, and / or lithium fluoride content of about 2 ppm each, based on the total mass of the powder mixture. The high-purity calcined powder mixture (which is then sintered using the methods disclosed herein) is thereby transferred to the multilayer sintered ceramic body after sintering. In the embodiments detailed above, for example, the multi-layer sintered ceramic body may have at least one first layer 100 comprising at least one crystalline phase of a ceramic material selected from the group consisting of YAG, magnesium aluminate spinel, yttria, and zirconia, and each of the at least one first layer 100 comprises silica in an amount of 14 to 100 ppm, preferably 14 to 75 ppm, preferably 14 to 50 ppm, preferably 14 to 25 ppm, preferably 14 to 20 ppm, and preferably about 14 ppm, based on the mass of the at least one first layer 100. In another embodiment, each of the at least one first layer 100 may include magnesia, lithia / lithium fluoride, and / or calcia in an amount of about 2 to 100 ppm, preferably about 2 to 75 ppm, preferably about 2 to 50 ppm, preferably about 2 to 25 ppm, preferably about 2 to 20 ppm, preferably about 2 to 10 ppm each, based on the weight of the at least one first layer 100. To enhance strength and provide chemical inertness in the at least one first layer 100 including YAG, magnesium aluminate spinel, and zirconia and alumina, each of the at least one first layer 100 preferably does not include more than about 2 ppm of Li or LiF, each, based on the weight of the at least one first layer 100.Thus, in a further embodiment, each of the at least one first layer 100 may contain lithium fluoride, calcia, and / or magnesia in an amount of about 2 to 100 ppm, preferably about 2 to 75 ppm, preferably about 2 to 50 ppm, preferably about 2 to 25 ppm, preferably about 2 to 20 ppm, each based on the weight of the at least one first layer 100.

[0188] In a preferred embodiment, the at least one first layer comprising YAG may each have a purity of 99.99% or greater, preferably 99.995% or greater, relative to a material having 100% purity as measured using the ICPMS method disclosed herein.

[0189] In an embodiment, the at least one first layer comprising polycrystalline YAG each comprises Si in the form of silica in an amount of 14 to 100 ppm, preferably 14 to 75 ppm, preferably 14 to 50 ppm, preferably 14 to 25 ppm, preferably 14 to 20 ppm, preferably about 14 ppm, relative to the total mass of the at least one first layer.

[0190] In embodiments of the multilayer sintered ceramic body disclosed herein, at least one first layer 100 comprising polycrystalline YAG can be prepared using optional dopants, for example, rare earth oxides selected from the group consisting of Sc, La, Er, Ce, Cr, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb, and Lu, and oxides and combinations thereof, in an amount of 0.002 wt. % or more, preferably 0.0035 wt. % or more, preferably 0.005 wt. % or more, preferably 0.0075 wt. % or more, which can be added to the starting powder or powder mixture in step a), as detailed below.

[0191] In some embodiments, the at least one first layer 100 comprising polycrystalline YAG is preferably free or substantially free of dopants, particularly for semiconductor chamber applications requiring chemical inertness and resistance to corrosion and erosion combined with high strength.

[0192] According to one embodiment, excess yttria and / or alumina in the YAG layer 100, to the extent that it may remain in the at least one first layer, is not considered a dopant or sintering aid. The high purity and corresponding low impurities of the disclosed at least one first layer may enable reduced particle generation and corrosion and erosion required for use in semiconductor reactors. For example, purity of 99.995% or greater, preferably 99.999% or greater, preferably 99.9995% or greater, and preferably about 99.9999% may be measured for the at least one first layer 100 comprising YAG.

[0193] However, these corrosion- and erosion-resistant materials present challenges for sintering to the high densities required for semiconductor etch and deposition chamber applications, and therefore typically require pressure-assisted sintering, and in some embodiments pressure and current-assisted sintering.

[0194] Multilayer sintered bodies, as known to those skilled in the art, are often formed from precast layers or tapes that are stacked and co-sintered, or stacked or deposited on a sintering substrate and sintered. However, these multilayer laminates often delaminate at the interfaces between the layers due to poor interfacial bonding between the layers, resulting in spalling and particle shedding during use in semiconductor reactors. Typically, these laminates have interfaces that are linear and therefore do not offer the benefits of the interlocking, nonlinear interfaces 104 with improved adhesive strength and bonding that are characteristic of the single multilayer sintered ceramic bodies disclosed herein.

[0195] Disclosed herein is a multilayer sintered ceramic body including at least one first layer 100 and at least one second layer 102, which are continuous and bounded by a nonlinear interface 104, as shown in the schematic diagram of FIG. 10b. As shown, the interface 104, which is nonlinear (as described in more detail herein), can provide improved adhesion between the at least one first layer 100 and the at least one second layer 102. This improved adhesion can be achieved by several factors, including an increased interfacial length and associated increased interfacial area, tortuosity (T), the arithmetic mean of the interface (the distance of the interface from the mean interface line), nonlinearity, and an interlocking effect provided by the morphology of the interface 104. 1a) and 1b) show SEM images characterizing the interface 104 between at least one first layer 100 and at least one second layer 102. As shown in the exemplary image of FIG. 1b), the linear length (L) between the edges is approximately 54 μm, and the interface length or curvature (C) measured along the interface 104 is approximately 90 μm. The tortuosity according to FIG. 1b) using calculations disclosed herein is 1.7. Measurements were made across nine SEM images using ImageJ software analysis as disclosed herein. An average interface length of approximately 90 μm was measured, indicating an approximately 66% increase in interface length (C) relative to the linear distance (L). Accordingly, disclosed herein is a multilayer sintered ceramic body having an interface 104 defined by at least one second layer and at least one first layer, wherein the interface length increases by 20-70%, preferably 20-60%, preferably 20-40%, preferably 30-80%, preferably 40-80%, preferably 50-70%. Correspondingly, the at least one second layer 102 and the at least one first layer 100 may contact each other at an interface whose interface area corresponds to the largest dimension of the multilayer sintered ceramic body. For a single multilayer sintered body having a largest dimension of 100 to about 625 mm, the at least one second layer 102 and the at least one first layer 100 may contact each other at an interface whose interface area corresponds to about 3,117 cm2, preferably about 3,068 cm2. 2 Below 2,919 cm, preferably 2 Preferably 78 to about 3,117 cm2 , preferably 78 to about 3,068 cm 2 , preferably 78 to 2,919 cm 2 , preferably 78 to 1,963 cm 2 , preferably 78 to 1,257 cm 2 , preferably 78 to 707 cm 2 , preferably 78 to 314 cm 2 , preferably 314 to about 3,117 cm 2 , preferably 314 to about 3,068 cm², preferably 314 to 2,919 cm² 2 , preferably 314 to 1,963 cm 2 , preferably 314 to 1,257 cm 2 , preferably 707 to about 3,068 cm 2 , preferably 1257 to 3,039 cm 2 The first and second layers 100 and 102 contact each other at a nonlinear interface 104 having an area of ​​approximately 100 mm. In embodiments, the first and second layers are in direct contact to form the nonlinear interface 104, and therefore, it is preferred that at least one of the first and second layers be adjacent layers. In other embodiments, circuitry, heating elements, RF coils / antennas, etc. may be disposed between the first and second layers as required by the particular component application; regardless of these features, the first and second layers may be adjacent or substantially adjacent. This increased interfacial length and area enhances adhesion at the nonlinear interface 104 between the at least one first layer 100 and the at least one second layer 102.

[0196] FIG. 11a) shows an SEM micrograph at 500x of an interface 104 of a multilayer sintered ceramic body, where the interface defined by at least one second layer 102 and at least one first layer 100 is an irregular, nonlinear boundary, which, in embodiments, may include a retrograde angle. In some embodiments, such as shown in FIG. 11a), the interface may include at least one dovetail structure and / or at least a portion of a dovetail structure. In other embodiments, at least a portion of the interface may include a trapezoidal shape. Tortuosity (T), as disclosed herein, is mathematically defined as the ratio of the length of the curve, C, to the linear distance, L, between its ends: T=C / L. The image in FIG. 11a) was measured to have a tortuosity of 2.7. The nonlinear interfaces 104 disclosed herein can have a tortuosity T of greater than 1 to about 1.5, preferably greater than 1 to about 2.0, preferably greater than 1 to about 2.5, preferably greater than 1 to about 3.0, preferably greater than 1.1 to about 3.0, as measured using SEM and image processing methods (measurements within ImageJ software) disclosed herein. A straight interface (typical of laminates and structures using pre-sintered bodies to which layers are applied) has a tortuosity of about 1. The increased tortuosity of the interfaces 104 of the multilayer bodies disclosed herein provides an interlocking effect between the layers, thereby increasing the bond strength such that an inseparable, single, multilayer ceramic sintered body is formed.

[0197] FIG. 11b shows the interface line (IL) of the interface 104 calculated from SEM and image processing methods. As shown, an exemplary SEM image showing the nonlinear interface 104 was imported into ImageJ software, and the x / y coordinates corresponding to points along the interface were used to obtain a linear equation for the interface line (IL) as shown in FIG. 11b. The interface 104 was characterized by its distance from the interface line (IL). The distance (D) of the interface 104 from the interface line (IL) varied by an amount of 10-100 μm, preferably 20-100 μm, preferably 30-100 μm, preferably 40-100 μm, 50-100 μm, and preferably 25-85 μm, as measured using SEM and image processing. An increase in the distance (D) from the interface line (IL) may contribute to improved adhesion and interlocking effects of the multilayer sintered ceramic bodies disclosed herein.

[0198] These reverse or retrograde angles, properties, and structures may provide an anchoring effect, thereby increasing the interfacial and tensile strength and bonding across the interface 104 defined by the at least one second layer 102 and the at least one first layer 100.

[0199] The at least one second layer 102 comprises magnesium aluminate spinel of composition MgAlO having 90-100% by volume of a cubic crystal structure and a density of 3.471-3.579 g / cc. Sintered at least one second layer 102 comprising cubic spinel, particularly magnesia alumina spinel, is isotropic in that material properties do not vary based on crystal plane or direction; therefore, the cubic spinel morphology is preferred for its consistent material properties and predictable performance in many applications. In an embodiment, the at least one second layer 102 comprises 95-100% by volume, preferably 98-100% by volume, preferably 99-100% by volume, and more preferably 100% by volume of magnesium aluminate spinel MgAlO.

[0200] Additionally, the at least one second layer 102 comprising magnesium aluminate spinel has sufficient bending strength and stiffness for handling at large (100-600 mm) dimensions. Significant stresses can be exerted on the components during use, and to an even greater extent given the large body dimensions, necessitating the selection of high strength materials.

[0201] The at least one second layer 102 containing magnesium aluminate spinel has a high density, which provides high bending or mechanical strength and improves handling and performance when used in many structural applications. Density measurements were performed using the Archimedes water immersion method, which is known in the art. According to L. Ping et al., "Magnesium aluminate (MgAl2O4) spinel produced via self-heat-sustained (SHS) technique," Materials Research Bulletin 36 (2001), the theoretical density of magnesium aluminate spinel is 3.579 g / cc. The ceramic sintered body disclosed herein may have a density of, for example, 3.471 to 3.579 g / cc, preferably 3.489 to 3.579 g / cc, preferably 3.506 to 3.579 g / cc, preferably 3.542 to 3.579 g / cc, and preferably 3.560 to 3.579 g / cc. These values ​​correspond to percent theoretical density of 97-100%, 97.5-100%, further 98-100%, further 99-100%, and further 99.5-100%, which may provide enhanced mechanical strength, improved resistance to the effects of chemical erosion and corrosion, among other beneficial properties.

[0202] In addition to high mechanical strength, the at least one second layer 102 comprising magnesium aluminate spinel has a high hardness value, which enables the ability to form fine features in the ceramic sintered body when machined to a specific shape without chipping, spalling, or damaging the surface of the sintered body. For example, magnesium aluminate spinel can be machined to form intricate features with fine geometries, such as on the order of about 75 μm or less, in less time. For example, compared to a zirconia-toughened alumina second layer, a magnesium aluminate spinel second layer can be machined in approximately 50% less time. The hardness of the at least one second layer 102 comprising magnesium aluminate spinel was measured in accordance with ASTM C1327 using a 0.025 kgf load cell. An average hardness of 15.06 GPa was measured over eight repeats. The hardness of the spinel sintered body is preferably 13.5 GPa to 16.5 GPa, preferably 13.5 GPa to 16 GPa, preferably 13.5 GPa to 15.5 GPa, preferably 14 GPa to 16.5 GPa, preferably 15 GPa to 16.5 GPa, preferably 14 GPa to 16 GPa.

[0203] In an embodiment, the at least one second later 102 comprising magnesium aluminate spinel has a purity of 99.99% or greater, preferably 99.995% or greater, preferably 99.999% or greater, as measured using ICPMS techniques.

[0204] The at least one second layer 102 may be stabilized by the addition of 0.1% to 1% by volume of zirconia. The addition of small amounts of zirconia limits grain growth and improves the mechanical strength of the layer. Only small amounts of zirconia are added so as not to significantly affect the CTE of the at least second layer 102.

[0205] In a preferred embodiment, the at least one second layer comprising magnesium aluminate spinel does not contain CaO.

[0206] To provide high mechanical strength and rigidity, the thickness d2 of the at least one second layer 102 shown in FIG. 2 is preferably greater than the thickness d1 of the at least one first layer 100. The thickness d1 of the at least one first layer 100 may be 0.5 to 5 mm, preferably 0.5 to 4 mm, preferably 0.5 to 3 mm, preferably 0.5 to 2 mm, preferably 0.6 to 5 mm, preferably 0.6 to 3 mm, preferably 1 to 5 mm, preferably 1 to 4 mm, preferably 1 to 3 mm, preferably 2 to 4 mm, or preferably 2 to 3 mm. The multilayer sintered ceramic body 98 disclosed herein may have a total thickness (d1 + d2) of about 10 to about 40 mm, preferably about 10 to about 35 mm, preferably about 10 to about 33 mm, preferably about 10 to about 30 mm, preferably about 10 to about 25 mm, or preferably about 10 to about 20 mm. In certain embodiments, it may be desirable to minimize the thickness of at least one first layer 100, and therefore the multilayer sintered ceramic body 98 may be machined as needed after sintering and / or after annealing to reduce the thickness d1 of the layer 100 and modify the electrical, thermal, or other properties of the multilayer sintered body 98 or a component formed therefrom.

[0207] The pressure-assisted (and in preferred embodiments, pressure- and current-assisted, such as SPS) sintering process disclosed herein provides for the preparation of a single, multilayer sintered ceramic body from at least two layers of a sintered powder mixture disposed within a tool set (powder compact) without the use of dopants and / or sintering aids. The single, multilayer sintered body 98 is formed from layers of the sintered powder mixture, which are then formed into at least one first layer 100 and at least one second layer 102 of the sintered body, respectively, in an in-situ sintering process (without forming a film, tape, or green body, as is common in the art). The pressure-assisted method produces a dense, single, multilayer sintered ceramic body without the need to adapt the sintering rate of pressureless methods known to those skilled in the art. The absolute value of the CTE difference between at least one first layer 100 and at least one second layer 102 of the sintered body is preferably within the ranges disclosed herein to avoid cracking and fracture resulting from a CTE mismatch outside the disclosed ranges (which may be experienced during sintering and other thermal excursions, such as annealing).

[0208] The corrosion-resistant multilayer sintered ceramic bodies described above can be fabricated into large corrosion-resistant multilayer sintered components for plasma etch chambers, with the components having dimensions ranging from 100 mm to 625 mm for the maximum dimension of the multilayer sintered body. The large component dimensions described herein may be further enabled by the increased interface length and interlocking effect of the nonlinear interface 104 between the at least one first layer 100 and the at least one second layer 102.

[0209] Preparation method The preparation of multilayer sintered ceramic bodies may be achieved through the use of pressure-assisted sintering, such as spark plasma sintering (SPS) or direct current sintering (DCS), also known as field-assisted sintering technology (FAST). These DC sintering-assisted and related techniques use direct current to heat an electrically conductive die configuration or tool set, thereby heating the material to be sintered. This heating regime allows for very high heating and cooling rates to be applied, enhancing densification mechanisms over diffusion mechanisms that promote grain growth, facilitating the preparation of ceramic sintered bodies with very fine grain sizes and transferring the intrinsic properties of the original powder to their near- or fully dense products. The pressure- and current-assisted methods disclosed herein utilize continuous, preferably non-pulsed, direct current to heat the tool sets disclosed herein.

[0210] The above-described properties of the corrosion-resistant multilayer sintered ceramic body according to one embodiment are achieved, in part, by matching the purity and specific surface area (SSA) of the first and second powder mixtures, the pressure on the first and second powder mixtures, the temperature of the first and second powder mixtures, the duration of sintering of the first and second powder mixtures, the temperature of the multilayer sintered ceramic body during the optional annealing step, and the duration of the annealing step.

[0211] 1. A method for making a multi-layer sintered ceramic body, comprising: a) combining yttria powder and alumina powder to form a first powder mixture; b) combining magnesium oxide powder and aluminum oxide powder to form a second powder mixture; c) sintering the first sintered powder mixture and the second sintered powder mixture by applying heat to raise the temperature of the powder mixtures to a sintering temperature and maintaining the sintering temperature to form the first and second powder mixtures; d) separately disposing the first sintered powder mixture and the second sintered powder mixture in a volume defined by a toolset of a sintering apparatus to form at least one layer of the first sintered powder mixture and at least one layer of the second sintered powder mixture and creating a vacuum condition in the volume; and e) sintering the first sintered powder mixture while heating to the sintering temperature. and f) applying pressure to layers of the composite and the second fired powder mixture and sintering to form a multilayer sintered ceramic body, wherein at least one layer of the sintered first powder mixture forms at least one first layer and at least one layer of the second fired powder mixture forms at least one second layer after sintering; and f) reducing the temperature of the multilayer sintered ceramic body, wherein the at least one first layer comprises polycrystalline YAG, the at least one first layer has at least one surface, and the at least one second layer comprises magnesium aluminate spinel, the at least one surface of the at least one first layer comprises pores, the pores having a maximum size of 0.1 to 5 μm as measured using SEM and image processing methods, and each of the at least one first layer and the at least one second layer has a pore size of 0 to 0.6×10 as measured in accordance with ASTM E228-17. -6 / °C different coefficients of thermal expansion (CTE).

[0212] The following additional steps are optional: g) annealing the multilayer sintered ceramic body by applying heat to increase the temperature of the multilayer sintered ceramic body to reach an annealing temperature at which annealing will occur; h) decreasing the temperature of the annealed multilayer sintered ceramic body; and i) machining the multilayer sintered ceramic body or the annealed multilayer sintered ceramic body to form a multilayer sintered ceramic component in the shape of a dielectric window, RF window, focus ring, process ring, deposition ring, nozzle or gas injector, showerhead, gas distribution plate, etch chamber liner, plasma source adapter, gas inlet adapter, diffuser, electrostatic wafer chuck (ESC), chuck, puck, ion suppressor element, faceplate, isolator, spacer, and / or guard ring in a plasma processing chamber.

[0213] Step a) of the method disclosed herein involves combining yttria powder and alumina powder to form a first powder mixture. The starting powder materials, including the first powder mixture, are combined and mixed in proportions such that, after sintering, the at least one first powder mixture forms at least one first layer including a polycrystalline phase containing YAG. As detailed above, up to 1% by volume of zirconia may also be added to the first powder mixture. The powders selected to form the at least one first powder mixture are preferably commercially available powders with high purity (>99.99%). However, other oxide powders, such as those produced by chemical synthesis processes and related methods, may also be used. In a preferred embodiment, the first powder mixture includes yttria and alumina.

[0214] The particle sizes of the starting powders, powder mixtures, and calcined powder mixtures can be measured using a Horiba Model LA-960 laser scattering particle size distribution analyzer, which is capable of measuring particle sizes from 10 nm to 5 mm. The specific surface area (SSA) of the starting powders, powder mixtures, and calcined powder mixtures ranges from 0.01 to 2000 m for most samples. 2Purity can be measured using a Horiba BET Surface Area Analyzer Model SA-9601, which can measure specific surface areas of 100% or less with an accuracy of 10% or better across the range of 100% / g. The purity of the starting powders, powder mixtures, and calcined powder mixtures can be measured using ICP-MS measurements using an Agilent 7900 ICP-MS Model G8403, which can analyze lighter elements (such as Sc and lower atomic numbers) down to about 1.4 ppm and heavier elements (such as atomic numbers greater than Sc) down to about 0.14 ppm. Purity is reported herein as a percentage of 100% purity, which represents a material containing only the intended components, free of impurities, dopants, sintering aids, etc. Impurity content is reported herein in ppm relative to the total mass of the material being evaluated. Silica is not disclosed in the purity and impurity reports and can be measured in amounts of about 14 ppm or greater using the ICP-MS method disclosed herein.

[0215] The d10 particle size of the yttrium oxide powder used as a starting material according to an embodiment of the present invention is preferably 1-6 μm, preferably 1-5 μm, preferably 1-4 μm, preferably 2-6 μm, preferably 3-6 μm, preferably 4-6 μm, preferably 2-4 μm.

[0216] The d50 particle size of the yttrium oxide powder used as a starting material according to embodiments of the present invention is preferably 3-9 μm, preferably 3-8.5 μm, preferably 3-8 μm, preferably 3-7 μm, preferably 4-9 μm, preferably 5-9 μm, preferably 6-9 μm, preferably 4-8 μm. The yttria powder disclosed herein may have an average particle size of about 5-9 μm.

[0217] The d90 particle size of the yttrium oxide powder used as starting material according to an embodiment of the present invention is preferably 6-16 μm, preferably 6-15 μm, preferably 6-14 μm, preferably 6.5-16 μm, preferably 7-16 μm, preferably 7.5-16 μm, preferably 7.5-14 μm.

[0218] Yttrium oxide powder is typically 2-10 m 2 / g, preferably 2 to 8 m 2 / g, preferably 2 to 6 m 2 / g, preferably 3 to 10 m 2 / g, preferably 4 to 10 m 2 / g, preferably 6 to 10 m 2 / g, preferably 2 to 4 m 2 / g specific surface area (SSA).

[0219] The purity of the yttrium oxide starting material is preferably greater than 99.99%, preferably greater than 99.995%, more preferably greater than 99.999%, more preferably greater than 99.9995%, more preferably greater than about 99.9999%, which corresponds to an impurity level of 100 ppm or less, preferably 50 ppm or less, preferably 25 ppm or less, preferably 10 ppm or less, more preferably about 1 ppm, preferably 1-100 ppm, preferably 1-50 ppm, preferably 1-25 ppm, preferably 1-10 ppm, preferably 1-5 ppm.

[0220] As known in the art, the d50 particle size is defined as the median particle size and represents the value above which half of the particle size distribution lies and half below which point. Similarly, 90% of the distribution lies below the d90 and 10% of the distribution lies below the d10.

[0221] The yttria and alumina starting powders disclosed herein are preferably crystalline, thereby possessing long-range crystallographic order. 2 Starting powders with high surface areas, such as those greater than about 18 m / g, present handling challenges when loading the powder mixtures disclosed herein into a tool set, and also make it difficult to achieve uniform dispersion and intimate mixing during the powder combining / mixing process. Thus, in embodiments, the powder mixtures and / or calcined powder mixtures disclosed herein are free or substantially free of nanopowder and have a surface area of ​​about 18 m / g or greater. 2 It is preferred that the specific surface area (SSA) is 0.1 / g or less.

[0222] Approximately 1 m 2 Starting powders with specific surface areas less than 1 to 18 m / g may suffer from agglomeration, require higher energy and longer mixing times for mixing, and may reduce the sintering activation energy, thus producing sintered ceramic bodies with lower densities and higher porosity. Preferred for use in the disclosed method are powders with specific surface areas between 1 and 18 m / g. 2 / g, preferably 2 to 15m 2 / g, preferably 3 to 12 m 2 / g of SSA.

[0223] Combining the alumina and yttria powders with the magnesia and alumina to produce at least the first and second powder mixtures (according to either or both of steps a) and b) can be carried out using powder preparation techniques such as wet or dry ball (axial rotation) milling, wet or dry tumble (end-to-end or vertical) mixing, jet milling, and combinations thereof. The use of these powder combination methods provides a high-energy process that breaks down particulates and agglomerates.

[0224] Using dry conditions, the starting powders can be ball milled or end-over-end / tumbling mixed using high-purity (>99.9%) alumina media to maintain the purity of the starting powders during mixing. In other embodiments, zirconia media can be used to break down hard agglomerates. High-purity alumina media has been tested using the ICPMS method disclosed herein and found to have a purity of approximately 99.9-99.99%. The use of zirconia media can result in trace amounts of zirconia, such as less than 100 ppm, in the multilayer sintered ceramic body. The media used to perform dry ball milling can have a size ranging from, for example, 5-15 mm in diameter and are added at a loading of about 50-100% by powder weight. The media used to perform dry tumbling mixing can include, but is not limited to, at least one media element of large size (approximately 20-40 mm in diameter). Dry ball milling and / or dry tumbling mixing can be carried out for a period of 12 to 48 hours, preferably 16 to 48 hours, preferably 16 to 24 hours, preferably 18 to 22 hours. The dry ball milling or tumbling milling process (axial rotation) may use an RPM (revolutions per minute) of 50 to 250 RPM, preferably 75 to 200 RPM, preferably 75 to 150 RPM, preferably 100 to 125 RPM, each in a vessel having a diameter of about 200 mm. The RPM may vary depending on the size of the vessel selected for use; for example, a diameter greater than 200 mm may have a correspondingly lower RPM, as known to those skilled in the art. Dry end-over-end / tumbling mixing can be carried out at 10 to 30 rpm, preferably about 20 RPM. After dry ball milling and / or end-over-end / tumbling milling / mixing, the powder mixture may be sieved and blended as needed using any number of meshes, which may have openings of, for example, 45-400 um, without limitation as to repetition or sequence, as known to those skilled in the art.

[0225] Wet ball milling or wet end-over-end / tumbling mixing can be performed by suspending the starting powder in various solvents, such as ethanol, methanol, and other alcohols, to form a slurry. The slurry in either process can be formed during milling or mixing with a powder loading of 25-75% by powder weight, preferably 40-75% by powder weight, and preferably 50-75% by powder weight. Wet ball milling or wet end-over-end / tumbling mixing can improve powder dispersion due to increased mobility, resulting in a fine-scale, uniform mixture prior to heat treatment or calcination. In embodiments, a dispersant can be added to the slurry as needed, using any number of commercially available dispersants, such as polymethyl methacrylate (PMMA) and polyvinylpyrrolidone (PVP), as well as others known to those skilled in the art. The dispersant can be added as needed in an amount of 0.05-0.2% by powder weight, preferably 0.05-0.1% by powder weight. Media loading for either wet ball or wet tumbling / end-over-end mixing can vary from 30-100% by powder weight, preferably 30-75% by powder weight, and preferably 30-60% by powder weight. Wet ball milling or tumbling mixing can be performed for a duration of 8-48 hours, preferably 12-48 hours, preferably 16-48 hours, preferably 8-36 hours, preferably 8-24 hours, preferably 16-24 hours, and preferably 12-24 hours. Ball milling can use RPMs (revolutions per minute) of 50-250 RPM, preferably 75-200 RPM, preferably 75-150 RPM, and preferably 100-125 RPM, each with a vessel diameter of approximately 200 mm. RPMs can vary depending on the size of the vessel selected for use; for example, vessels larger than 200 mm in diameter can have correspondingly lower RPMs, as known to those skilled in the art. Wet end-over-end / tumbling (or vertical) mixing can be performed at 10-30 rpm, preferably about 20 RPM.After wet ball milling and / or wet end-over-end / tumbling mixing, the powder mixture may be sieved and blended as needed using any number of meshes, which may have openings of, for example, 45-400 um, without limitation as to repetition or sequence, as known to those skilled in the art.

[0226] Jet milling processes, known to those skilled in the art, can also be used to thoroughly mix powders to form powders, powder mixtures, or calcined powder mixtures with narrow particle size distributions. Jet milling uses high-velocity jets of either inert gas or air to collide particles of the starting powder and / or powder mixture and / or calcined powder mixture without the use of milling or mixing media, thus preserving the initial purity of the milled powder. The chamber can be designed to preferentially reduce the size of larger particles, providing a narrow particle size distribution in the final powder, powder mixture, or calcined powder mixture. Once the powder reaches a predetermined particle size, determined by the machine settings prior to processing, it exits the jet milling chamber, completing the process. The starting powders, powder mixtures, and / or calcined powder mixtures disclosed herein, whether alone or in combination with any or all of the disclosed powder milling / mixing processes, may be subjected to jet milling at a pressure of approximately 100 psi. After jet milling, the powder or powder mixture may be blended and optionally sieved using any number of meshes, which may have openings of, for example, 45-400 μm, without any limitation as to repetition or order, as known to those skilled in the art.

[0227] Additional powder preparation procedures such as attrition milling, high shear mixing, planetary milling, and other known procedures can also be applied. The powder preparation techniques described above can be used alone, in any combination thereof, or for two or more powder mixtures that are subsequently sintered to form a single multi-layer sintered ceramic body.

[0228] If a wet mixing or milling process is used, the slurry can be dried by rotary evaporation, for example, at a temperature of about 40°C to 90°C for 1 to 4 hours, depending on the volume of the slurry to be dried, as known to those skilled in the art. In other embodiments, the slurry can be dried using spray drying techniques known to those skilled in the art. After drying, the powder mixture can be sieved as needed, for example, using a mesh with openings of 45 to 400 μm, without limitation in terms of repetition or order, and blended. The aforementioned powder preparation techniques can be used alone or in any combination thereof.

[0229] After drying, the specific surface area of ​​the powder mixture of step a) is 2 to 18 m 2 / g, preferably 2 to 17m2 / g, 2 to 14m 2 / g, preferably 2 to 12 m 2 / g, 2-10m 2 / g, preferably 4 to 17 m 2 / g, 6-17m 2 / g, preferably 8 to 17 m 2 / g, preferably 10 to 17 m 2 / g, 4-12m 2 / g, preferably 4 to 10 m 2 / g, preferably 5 to 8 m 2 / g.

[0230] The purity of the powder mixture can be maintained from the purity of the starting materials after mixing / milling by using high purity milling media, such as aluminum oxide media having a purity of 99.99% or greater. In embodiments, the use of zirconium oxide milling media may be preferred, and zirconium oxide can be introduced to the extent that it remains in at least one of the first and second layers of the multi-layer sintered ceramic body in an amount of 15-100 ppm, 15-75 ppm, preferably 15-60 ppm, and preferably 20-30 ppm.

[0231] Step b) of the method disclosed herein comprises combining magnesium oxide powder and aluminum oxide powder to form a second powder mixture. The starting powder materials comprising the second powder mixture comprising magnesium oxide and aluminum oxide for forming at least one second layer are preferably commercially available powders of high purity.

[0232] Step b) provides for the preparation of a ceramic sintered form or component comprising a sintered spinel layer having a cubic crystalline phase of composition MgAl2O4.

[0233] The average or d50 particle size of magnesium oxide powders used as starting material according to embodiments of the present invention is typically 1.5-5.5 μm, 2-5.5 μm, 2.5-5.5 μm, 3-5.5 μm, 1.5-5 μm, 1.5-4.5 μm, more preferably 2-4.5 μm.

[0234] The d90 particle size of the magnesium oxide powder used as starting material according to an embodiment of the present invention is 4-9 μm, preferably 5-9 μm, preferably 6-9 μm, preferably 4-8 μm, preferably 4-7 μm, more preferably 5-7.5 μm.

[0235] The aluminum oxide powder used as starting material according to one embodiment has an average or d50 particle size of 0.75 to 7 μm, preferably 0.75 to 6.5 μm, preferably 0.75 to 6 μm, preferably 1 to 7 μm, preferably 1.5 to 7 μm, preferably 2 to 7 μm, more preferably 2 to 6 μm. The aluminum oxide powder typically has an average particle size of 4 to 18 μm. 2 / g, preferably 4 to 15 m 2 / g, preferably 4 to 12 m 2 / g, preferably 4 to 10 m 2 / g, preferably 6 to 18 m 2 / g, preferably 6 to 15 m 2 / g, preferably 6 to 12 m 2 / g, preferably 6 to 10 m 2 / g, preferably 6 to 8 m 2 / g specific surface area (SSA). The purity of the aluminum oxide starting material is typically greater than 99.99%, preferably greater than 99.995%, preferably greater than 99.9975%, preferably greater than 99.999%, preferably greater than 99.9995%, preferably greater than 99.9999%. Correspondingly, the impurity content of the alumina powder can be 100 ppm or less, preferably 50 ppm or less, preferably 25 ppm or less, preferably 10 ppm or less, preferably 5 ppm or less, more preferably 1 ppm or less.

[0236] The d10 particle size of the aluminum oxide powder used as starting material according to one embodiment of the present invention is preferably 0.1-0.5 μm, preferably 0.1-0.4 μm, preferably 0.1-0.3 μm, preferably 0.2-0.5 μm, preferably 0.3-0.5 μm, preferably 0.4-0.5 μm, preferably 0.1-0.2 μm.

[0237] The d50 particle size of the aluminum oxide powder used as starting material according to one embodiment is typically 2 to 8 μm, preferably 2 to 7 μm, preferably 2 to 6 μm, preferably 3 to 8 μm, preferably 4 to 8 μm, preferably 5 to 8 μm, more preferably 2.5 to 5 μm.

[0238] The d90 particle size of the aluminum oxide powder used as starting material according to one embodiment of the present invention is preferably 15-40 μm, preferably 15-30 μm, preferably 15-25 μm, preferably 20-40 μm, preferably 30-40 μm, preferably 20-30 μm.

[0239] Aluminum oxide powder is typically 4 to 18 m 2 / g, preferably 4 to 14 m 2 / g, preferably 4 to 10m2 / g, preferably 4 to 6m2 / g, preferably 6 to 18m 2 / g, preferably 6 to 14 m 2 / g, preferably 8 to 18 m 2 / g, preferably 10 to 18 m 2 / g, preferably 8 to 10 m2 / g, preferably 6 to 10 m 2 / g specific surface area.

[0240] The purity of the aluminum oxide starting material is typically greater than 99.99%, preferably greater than 99.995%, preferably greater than 99.999%, preferably greater than 99.9995%, as measured using ICPMS techniques. Correspondingly, the impurity content of the alumina powder can be 100 ppm or less, preferably 50 ppm or less, preferably 25 ppm or less, preferably 10 ppm or less, more preferably 5 ppm or less.

[0241] The zirconium oxide powder, when used at up to 1% by volume, may have a particle size distribution with a d10 of 0.08-0.20 μm, a d50 of 0.3-0.7 μm, and a d90 of 0.9-5 μm. The zirconium oxide powder used as a starting material for a mixture according to one embodiment of the present invention may have an average particle size of 0.3-1 μm.

[0242] Zirconia powder is typically 1-16m 2 / g, preferably 2 to 12 m 2 / g, more preferably 5 to 9 m 2 The zirconia powder starting material typically has a specific surface area of ​​1000 nm / g, and the purity of the zirconia powder starting material is typically greater than 99.5%, preferably greater than 99.8%, preferably greater than 99.9%, and preferably greater than 99.99%. This corresponds to a total impurity content of 5000 ppm or less, preferably 2000 ppm or less, preferably 1000 ppm or less, and preferably 100 ppm or less. The zirconia used herein may contain small amounts of Hf or other stabilizers, about 2-5 mol%, as is common in many commercially available zirconia powders.

[0243] Combining the alumina powder and magnesia powder to form the second powder mixture can be carried out according to the materials and methods disclosed in step a).

[0244] Step c) of the method disclosed herein includes calcining the first and second powder mixtures by applying heat to raise the temperature of the powder mixtures to a calcination temperature and maintaining the calcination temperature to form a first calcined powder mixture and a second calcined powder mixture. This step can be performed to remove moisture and ensure a uniform surface condition of the powder mixtures before sintering. The calcination by the heat treatment step can be performed at a temperature of 600°C to 1200°C, preferably 600°C to 1100°C, preferably 600°C to 1000°C, preferably 600°C to 900°C, preferably 700°C to 1100°C, preferably 800°C to 1100°C, preferably 800°C to 1000°C, or preferably 850°C to 950°C. Calcination can be performed in an oxygen-containing environment for 4 to 12 hours, preferably 4 to 10 hours, preferably 4 to 8 hours, preferably 6 to 12 hours, preferably 4 to 6 hours. After calcination, the powder mixture may be sieved and / or tumbled and / or blended according to known methods to form at least a first calcined powder mixture and a second calcined powder mixture. Calcination may or may not result in a reduction in specific surface area.

[0245] The first calcined powder mixture and the second calcined powder mixture may have a d10 particle size of 0.1 to 4 μm, preferably 0.2 to 4 μm, preferably 0.3 to 4 μm, preferably 0.4 to 4 μm, preferably 0.1 to 3 μm, preferably 0.1 to 2 μm, preferably 0.1 to 3 μm, preferably 0.1 to 2 μm, preferably 0.1 to 1 μm.

[0246] The first calcined powder mixture and the second calcined powder mixture may have a d50 particle size of 3 to 50 μm, preferably 3 to 40 μm, preferably 3 to 30 μm, preferably 3 to 20 μm, preferably 3 to 10 μm, preferably 5 to 50 μm, preferably 10 to 50 μm, preferably 20 to 50 μm, preferably 30 to 50 μm, preferably 3 to 8 μm, preferably 5 to 10 μm, preferably 6 to 15 μm.

[0247] The first calcined powder mixture and the second calcined powder mixture may have a d90 particle size of 10 to 350 μm, preferably 10 to 300 μm, preferably 10 to 250 μm, preferably 10 to 200 μm, preferably 10 to 175 μm, preferably 10 to 150 μm, preferably 10 to 100 μm, preferably 10 to 75 μm, preferably 10 to 50 μm, preferably 10 to 40 μm, preferably 10 to 25 μm, preferably 20 to 350 μm, preferably 40 to 350 μm, preferably 60 to 350 μm, preferably 100 to 350 μm, preferably 150 to 350 μm, preferably 200 to 350 μm, preferably 12 to 330 μm, preferably 100 to 330 μm, preferably 100 to 250 μm.

[0248] In certain embodiments, the higher temperature firing conditions disclosed herein can result in the formation of crystalline phases and agglomeration of the fired powder mixture, thus resulting in greater variability in the overall particle size distribution, particularly larger d50 and d90 particle sizes. In other embodiments, the lower temperature firing conditions disclosed herein may not affect the particle size distribution of the fired powder mixture compared to the starting material, such that the particle size distribution is within the same range as or similar to the starting powder material. Lot-to-lot variation and management of heat transfer during firing can also contribute to the particle size distribution. Thus, a wide range of particle size distributions, particularly the d50 and d90 particle sizes of the powder mixture, can result from the firing conditions disclosed herein.

[0249] The first calcined powder mixture and the second calcined powder mixture each have a mass of about 1 m as measured in accordance with ASTM C1274. 2 / g ~ approx. 18m 2 / g, preferably about 1 m 2 / g ~ approx. 14m 2 / g, preferably about 1 m 2 / g~about 10m 2 / g, preferably about 1 m 2 / g~about 8m 2 / g, preferably about 2m 2 / g ~ approx. 18m 2 / g, preferably about 2m 2 / g ~ approx. 14m 2 / g, preferably about 2m 2 / g~about 10m 2 / g, preferably about 3m 2 / g ~ approx. 9m 2 / g, preferably about 3m 2 / g~about 6m 2 / g specific surface area (SSA).

[0250] The second powder mixture after firing is, in particular, 3 to 9 m 2 / g, 3-8m 2 / g, preferably 3 to 7 m 2 / g, preferably 3 to 6 m 2 / g, preferably 4 to 9 m 2 / g, preferably 5 to 9 m 2 / g, preferably 6 to 9 m 2 / g, preferably 4 to 7 m 2 / g。 After calcination, the powder mixture can be sieved, tumbled, blended, and combinations thereof according to known methods. Table 3 shows the properties of an exemplary calcined powder mixture 309. [Table 4]

[0251] The first calcined powder mixture may have a total impurity content of 5 to 200 ppm, preferably 5 to 150 ppm, preferably less than 100 ppm, preferably less than 50 ppm, preferably less than 25 ppm, preferably less than 15 ppm, preferably 10 to 100 ppm, preferably 10 to 80 ppm, preferably 10 to 60 ppm, preferably 10 to 40 ppm, preferably 20 to 80 ppm, preferably 30 to 60 ppm, based on the mass of the first calcined powder mixture.

[0252] Table 4 shows the ICPMS purity results of exemplary precursor powder mixtures before being formed into at least one second layer (i.e., magnesium aluminate spinel layer). [Table 5] *N / A represents elements present in the starting powders that form the powder mixture.

[0253] Table 5 shows the ICPMS purity results for the exemplary precursor powder mixture 10 before being formed into at least one first layer (ie, a polycrystalline YAG layer). [Table 6] *N / A represents elements present in the starting powders that form the powder mixture.

[0254] For each of Tables 4-5, N / D indicates that the element was detected below the reporting limit of ICPMS. The reported purity is the average of five powder mix lots after sintering.

[0255] The first calcined powder mixture and the second calcined powder mixture may each have a total impurity content of 5 to 200 ppm, preferably 5 to 150 ppm, preferably less than 100 ppm, preferably less than 75 ppm, preferably less than 50 ppm, preferably less than 25 ppm, preferably less than 15 ppm, preferably less than 10 ppm, preferably less than 8 ppm, preferably less than 5 ppm, preferably 5 to 50 ppm, preferably 5 to 30 ppm, preferably 3 to 20 ppm.

[0256] Step d) of the method disclosed herein includes separately disposing the first and second sintered powder mixtures in a volume defined by a sintering apparatus tool set to form at least one layer of the first and at least one layer of the second sintered powder mixture and creating a vacuum condition within the volume. The spark plasma sintering (SPS) apparatus used in the process disclosed herein includes at least one graphite die, typically a cylindrical graphite die. In the graphite die, the first and second sintered powder mixtures are separately disposed between two graphite punches to form at least two separate layers.

[0257] In a preferred embodiment, the SPS tool includes a die having a sidewall including an inner wall and an outer wall, the inner wall having a diameter defining an interior volume capable of receiving at least one ceramic powder, and an upper punch and a lower punch operably coupled to the die, each having an outer wall defining a diameter smaller than the diameter of the inner wall of the die, thereby defining a gap between each of the upper punch and the inner wall of the die when at least one of the upper punch and the lower punch moves within the interior volume of the die, the gap having a width of 10 μm to 100 μm. Preferably, the die and punches are made of graphite. Such an SPS tool is disclosed in U.S. Provisional Patent Application No. 63 / 087,204, filed October 3, 2020, which is incorporated herein by reference.

[0258] In embodiments, two or more sintered powder mixtures can be placed in a graphite die. A vacuum, known to those skilled in the art, is established within the powder between the punches surrounded by the die. Typical vacuum conditions include 10 -2 ~10 -3The pressure may be as low as 1000 torr. A vacuum is applied primarily to remove air to protect the graphite from burning and to remove most of the air from the powder mixture. The order of powder mixture placement can be reversed or repeated as needed to achieve the desired structure of the multilayer sintered ceramic body and the components formed therefrom. In embodiments, layers of the first and second sintered powder mixtures are adjacent when placed within the graphite die during sintering, and are then sintered to form first and second adjacent layers, thereby forming the interface 104 of the multilayer sintered ceramic body. Placing at least one first and at least one second sintered powder mixture within the volume defined by the tool set typically results in intermixing of the first and second sintered powder mixtures, thereby creating the aforementioned tortuosity of the nonlinear interface characteristic of the multilayer sintered bodies produced by the methods disclosed herein. This nonlinear interface can provide an interlocking effect and improved adhesion significantly different from that of laminates and sintered bodies formed from at least one laminate or pre-sintered body having a substantially linear (or one-dimensional) interface between at least one first layer and a second layer, and therefore the multilayer sintered ceramic bodies disclosed herein are not laminates or pre-sintered bodies. At least the first and second sintered powder mixtures can be loaded directly into a sintering machine tool set and sintered without pre-sintering steps such as the use of binders, dispersants, etc., which can contribute to contamination.

[0259] The disclosed process utilizes commercially available starting powders with micron-sized average particle size distributions or those prepared from chemical synthesis techniques without the need to form or machine green bodies prior to sintering.

[0260] The high density and low porosity associated with the multilayer sintered ceramic bodies resulting from the disclosed processes and powder materials are achieved without the use of binders or sintering aids in the initial powder. Other sintering techniques require the use of sintering aids to reduce sintering temperatures, which can adversely affect etch performance and densification. Polymer binders are also often used to form the aforementioned green bodies, which can contribute to residual porosity and lower density upon burnout. Binders or sintering aids are not required in the fabrication of the sintered corrosion-resistant ceramic bodies disclosed herein or the multiphase sintered components formed therefrom.

[0261] Step e) of the method disclosed herein includes applying pressure to the layers of the first and second calcined powder mixture while heating to a sintering temperature to sinter and form a multi-layer sintered ceramic body, wherein at least one layer of the first calcined powder mixture forms at least one first layer and at least one layer of the second calcined powder mixture forms at least one second layer after sintering; and f) reducing the temperature of the multi-layer sintered ceramic body, wherein pressure is applied axially to the calcined powder mixture disposed between graphite punches after at least the first and second calcined powder mixtures are disposed within a die. The pressure increases until it reaches 5 MPa to 100 MPa, preferably 5 MPa to 60 MPa, preferably 5 MPa to 40 MPa, preferably 5 MPa to 20 MPa, preferably 10 MPa to 60 MPa, preferably 10 MPa to 40 MPa, preferably 10 MPa to 30 MPa, preferably 10 MPa to 20 MPa, preferably 15 MPa to 60 MPa, preferably 15 MPa to 40 MPa, preferably 15 MPa to 30 MPa, preferably 20 MPa to 40 MPa, preferably 15 MPa to 20 MPa.

[0262] By applying heat to the powder mixture prepared in the die, a sintering temperature of 1000-1700°C, preferably 1200-1700°C, preferably 1400-1700°C, preferably 1500-1700°C, preferably 1600-1700°C, preferably 1200-1600°C, preferably 1200-1400°C, preferably 1400-1600°C, preferably 1500-1600°C is facilitated. Sintering can typically be achieved in a time period of 0.5 to 180 minutes, preferably 0.5 to 120 minutes, preferably 0.5 to 100 minutes, preferably 0.5 to 80 minutes, preferably 0.5 to 60 minutes, preferably 0.5 to 40 minutes, preferably 0.5 to 20 minutes, preferably 0.5 to 10 minutes, preferably 0.5 to 5 minutes, preferably 5 to 120 minutes, preferably 10 to 120 minutes, preferably 20 to 120 minutes, preferably 40 to 120 minutes, preferably 60 to 120 minutes, preferably 80 to 100 minutes, preferably 100 to 120 minutes, preferably 30 to 60 minutes, or preferably 15 to 45 minutes. In certain embodiments, sintering can be achieved without an isothermal hold time, and once the sintering temperature is reached, the cooling rate disclosed herein is initiated. According to process step f), the sintered ceramic body is passively cooled by removal of the heat source. Natural or forced convection can be used until a temperature is reached that facilitates the optional annealing process.

[0263] In a preferred embodiment, the powder mixture is heated directly by the punch and die of the sintering apparatus. The die and punch may be constructed of a conductive material such as graphite to facilitate resistive / Joule heating. Sintering apparatus and procedures are disclosed in U.S. Patent Application Publication No. 2010 / 0156008 A1, which is incorporated herein by reference.

[0264] Sintering the powder layers under pressure forms a co-compressed single multilayer body. According to the disclosed method, at least one layer of a first sintered powder mixture and at least one layer of a second sintered powder mixture are simultaneously formed in situ into at least one first layer and at least one second layer of a multilayer sintered ceramic body during step e) of the method. This single-step simultaneous sintering of at least one first sintered powder mixture and at least one second sintered powder mixture into at least one layer and at least one second layer can provide improved adhesion, high mechanical strength, and improved flatness of the multilayer sintered ceramic body. The matching of the CTEs of the at least one first layer and at least one second layer, particularly over the sintering temperature range disclosed herein, prevents stress generation due to CTE mismatch at the interface between the at least one second layer and the at least one first layer upon cooling after sintering, thereby enabling the formation of large-sized multilayer sintered ceramic bodies with high interfacial strength and adhesion. One layer contains polycrystalline YAG, and the other layer contains magnesium aluminate spinel (also polycrystalline). As can be seen in Figure 16, the YAG and spinel have closely matched CTEs over a wide temperature range.

[0265] During sintering, a volume reduction typically occurs, so that the sintered ceramic body may have a volume that is about one-third the volume of the starting powder mixture when placed in the sintering machine toolset.

[0266] The temperature of the sintering machine according to the present disclosure is usually measured in the graphite die of the machine, preferably as close as possible to the powder mixture being processed, so that the temperature indicated is actually realized in the powder mixture being sintered.

[0267] The order of application of pressure and temperature may be varied as disclosed herein. In one embodiment, the indicated pressure may be applied, followed by heat to achieve the desired sintering temperature. In another embodiment, heat may be applied to achieve the desired sintering temperature, followed by the indicated pressure. In a further embodiment, the temperature and pressure may be applied simultaneously to the powder mixture to be sintered and ramped up until the indicated values ​​are reached.

[0268] The disclosed method may include a pre-sintering step with a specific heating ramp of 1-100°C / min, preferably 2-50°C / min, more preferably 5-10°C / min, until a specific pre-sintering time is reached.

[0269] The disclosed method may include a pre-sintering step with a specific pressure gradient of 0.50 MPa / min to 30 MPa / min, preferably 0.75 MPa / min to 10 MPa / min, more preferably 1 to 5 MPa / min, until a specific pre-sintering time is reached.

[0270] The methods disclosed herein may include a pre-sintering step having the specific heating gradients described above and the specific pressure gradients described above.

[0271] In the pre-sintering step, the temperature and pressure are maintained for a period of 10 minutes to 360 minutes.

[0272] Induction or radiant heating methods can also be used to heat the sintering apparatus and indirectly heat the powder in the toolset.

[0273] Step g) of the method disclosed herein includes optionally annealing the multi-layer sintered ceramic body (or a component formed therefrom) by applying heat to raise the temperature of the multi-layer sintered ceramic body to an annealing temperature at which annealing is performed, and step h) lowering the temperature of the annealed multi-layer sintered ceramic body. In some embodiments, the method disclosed herein may further include an optional annealing step. In the optional annealing step according to embodiments of the present disclosure, the multi-layer sintered ceramic body may be removed from the sintering apparatus and subjected to an annealing procedure by annealing in a furnace at a temperature of about 900 to about 1800°C, preferably about 1250 to about 1700°C, more preferably about 1300 to about 1650°C, and more preferably about 1400 to about 1600°C.

[0274] In an embodiment, the optional annealing of the multilayer sintered ceramic body may be carried out at a heating and / or cooling rate of 0.5°C / min to 50°C / min, preferably 0.5°C / min to 25°C / min, more preferably 0.5°C / min to 10°C / min, more preferably 0.5°C / min to 5°C / min, more preferably 1°C / min to 50°C / min, more preferably 3°C / min to 50°C / min, more preferably 5°C / min to 50°C / min, more preferably 25°C / min to 50°C / min, preferably 1°C / min to 10°C / min, preferably 2°C / min to 10°C / min, preferably 2°C / min to 5°C / min.

[0275] The duration of the optional annealing step may be from 1 to 24 hours, preferably from 1 to 18 hours, preferably from 1 to 16 hours, preferably from 1 to 8 hours, preferably from 4 to 24 hours, preferably from 8 to 24 hours, preferably from 12 to 24 hours, preferably from 4 to 12 hours, preferably from 6 to 10 hours.

[0276] In one embodiment, annealing according to the present disclosure may be performed in a sintering apparatus after the sintering process. The optional annealing process may be performed under oxidizing conditions. Annealing results in improved chemical and physical properties of the multilayer sintered ceramic body or components produced therefrom through the reduction of oxygen vacancies for stoichiometric correction and stress reduction in the sintered body or component. The optional process step of annealing the sintered corrosion-resistant component is performed in an oxidizing atmosphere, whereby the annealing process may provide increased albedo, improved mechanical handling, and reduced porosity.

[0277] In some embodiments, the annealing step may be performed by conventional methods used for annealing glasses, ceramics, and metals, and the degree of refinement may be selected by the annealing temperature and the duration for which the annealing is performed. In other embodiments, annealing may not be performed on the sintered ceramic body.

[0278] After the optional process step of annealing the multilayer sintered ceramic body has been performed, the temperature of the sintered, and optionally annealed, multilayer sintered ceramic body is reduced to ambient temperature by removing the heat source to the sintered ceramic body or a component made therefrom in accordance with step h). The sintered and annealed multilayer sintered ceramic body or a component made therefrom is then removed from the furnace if the annealing step is performed outside the sintering apparatus, or removed from the tool set if the annealing is performed within the sintering apparatus.

[0279] Disclosed herein are improved multilayer sintered ceramic bodies and methods for making the same, particularly those of large body size for use in plasma etch chambers. The disclosed multilayer sintered ceramic bodies can have sizes ranging from 100 mm to about 625 mm along their longest extension.

[0280] The processes disclosed herein provide improved control over maximum pore size, higher density, particularly within at least one first layer, improved adhesion between layers of the multilayer component, improved mechanical strength and therefore handleability of the multilayer sintered ceramic body, and reduced oxygen vacancies within the lattice of the multilayer sintered ceramic body.

[0281] The aforementioned properties of the multilayer sintered ceramic body according to one embodiment are achieved by, among other things, matching the purity of the first powder and the second powder, the pressure applied to the first powder and the second powder, the temperature during heating for sintering the first powder and the second powder, the duration of sintering, the temperature of the sintered components during the optional annealing step, the environment during the optional annealing step, and the duration of the optional annealing step.

[0282] The disclosed process steps may have different orders and repetitions than those disclosed, and may not be performed in a particular order or with a particular number of repetitions. Furthermore, it is understood that additional powders other than those disclosed may be used. The use of high-purity rare earth elements or compounds as starting materials, free of sintering aids and having a purity of 99.9% to 99.9999%, preferably 99.99% to 99.9999%, more preferably 99.9995% to 99.9999%, enables the production of the high-purity sintered multilayer corrosion-resistant bodies disclosed herein, which provide improved plasma resistance and are particularly suitable for use as multilayer corrosion-resistant components in devices involving plasma processing, such as semiconductor manufacturing equipment. Furthermore, the processes disclosed herein do not require the formation of a green or sintered body prior to the sintering step to bond the at least one second layer 102 and the at least one first layer 100 of corrosion resistance. The multilayer corrosion-resistant sintered bodies disclosed herein are formed directly from powders that are sintered in a single process step without the use of green bodies, polymer binders, or sintering aids.

[0283] The pressure and current-assisted process according to embodiments disclosed herein is suitable for use in preparing large, multilayer sintered ceramic bodies. The disclosed process provides rapid powder consolidation and densification, maintaining a maximum grain size of about 10 μm or less in the sintered ceramic body and achieving high density and low porosity within at least one first phase and at least one second phase across the largest dimension. Reducing density variation, along with CTE matching between at least one first layer and at least one second layer within the ranges disclosed herein, can improve handleability and reduce overall stress in the sintered ceramic body. This combination of fine grain size, uniform and high density, and CTE matching provides large-sized, high-strength, multilayer sintered ceramic bodies suitable for machinability, handling, and use as components in semiconductor processing chambers.

[0284] Multilayer sintered ceramic components prepared by spark plasma sintering are proposed for use in plasma etch and deposition processing chambers. Examples of chamber components that may include the multilayer components disclosed herein include substrate support assemblies, such as wafer chucks or wafer packs, electrostatic chucks (ESCs), rings (e.g., process kit rings or single rings), chamber walls, bases, gas distribution plates, showerheads, liners, liner kits, shields, plasma screens, flow balancers, cooling bases, chamber viewports, windows, RF windows, dielectric windows, chamber lids, gas injectors, isolators, plasma adapters, diffusers, gas mixing manifolds, gas boxes, ion confining elements, and the like.

[0285] The methods and compositions disclosed herein are further illustrated by reference to the following examples, but it should be understood that they are not to be construed as limiting. [Example]

[0286] The following examples are included to demonstrate the general nature of the disclosure and are intended to illustrate, but not limit, the disclosure.

[0287] Multilayer sintered ceramic bodies according to the present disclosure and components that can be produced therefrom are disclosed below. The measurements disclosed in the Examples section are performed according to the procedures described herein.

[0288] Multilayer sintered ceramic bodies according to embodiments disclosed herein are formed in a single sintering step from a fired powder mixture without forming pre-sintered, cast or green bodies, or tapes, films or laminates.

[0289] The SPS tool used in each of the following examples included a die including a sidewall including an inner wall and an outer wall, the inner wall having a diameter defining an interior volume capable of receiving at least one ceramic powder, and an upper punch and a lower punch operably coupled to the die, each of the upper punch and the lower punch having an outer wall defining a diameter smaller than the diameter of the inner wall of the die, thereby defining a gap between each of the upper punch and the lower punch and the inner wall of the die when at least one of the upper punch and the lower punch moves within the interior volume of the die, the gap could be 10 μm to 100 μm wide.

[0290] The particle sizes of the starting powders, powder mixtures, and calcined powder mixtures were measured using a Horiba Model LA-960 laser scattering particle size distribution analyzer, which is capable of measuring particle sizes from 10 nm to 5 mm. The specific surface areas of the starting powders, powder mixtures, and calcined powder mixtures ranged from 0.01 to 2000 m for most samples. 2 Specific surface area (SSA) measurements were performed in accordance with ASTM C1274 using a Horiba BET Surface Area Analyzer model SA-9601, which is capable of measuring specific surface areas of 10% or better over a range of 10% / g.

[0291] Example 1: Multilayer sintered ceramic body comprising YAG as the first layer and magnesium aluminate spinel as the second layer (prophetic)

[0292] A multi-layer sintered ceramic body was formed from a first powder mixture and a second powder mixture. The first powder mixture included alumina and yttria combined in a ratio to form a first layer 100 comprising YAG as disclosed herein. The second powder mixture included magnesia and alumina in a ratio to form a second layer comprising magnesium aluminate spinel.

[0293] The first powder mixture is 5.5 to 9 m 2 alumina powder having a specific surface area (SSA) of 1.75 to 3.5 m / g, a d10 particle size of 0.05 to 1 μm, a d50 particle size of 2 to 6 μm, and a d90 particle size of 15 to 30 μm; 2 The alumina powders included yttria powders having a specific surface area of ​​0.1 μm / g, a d10 particle size of 2-4 μm, a d50 particle size of 5-9 μm, and a d90 particle size of 10-14 μm. The average impurity content of the alumina powders was approximately 6 ppm measured across three powder lots, corresponding to a purity of approximately 99.9994% for 100% pure alumina. The average impurity content of the yttria powders was approximately 17 ppm measured across five powder lots, corresponding to a purity of approximately 99.9983% for 100% pure yttria powder. The reporting limits for detecting the presence of lighter elements using ICPMS disclosed herein are higher than the reporting limits for heavier elements. In other words, heavier elements, e.g., elements with atomic numbers Sc and above, are detected with greater precision (e.g., precision of 1 ppm or less) than lighter elements, e.g., Li to Ca (detected with a precision of approximately 2 ppm or less). The use of ICPMS to detect lighter elements such as Li, Ca, and Mg can be done with a confidence of about 2 ppm or better. Li, Ca, and Mg are not detected in yttria and alumina powders using ICPMS known to those skilled in the art, and therefore the yttria and alumina powders contain about 2 ppm or less of Li, Ca, and Mg in the form of lithium fluoride, calcia, and magnesia. Si is not detected in yttria and alumina powders using ICPMS known to those skilled in the art, and therefore the yttria and alumina powders contain about 14 ppm or less of Si in the form of silica.

[0294] Yttria powder and alumina powder were combined in a ratio that would form at least one first layer containing YAG (yttrium aluminum oxide, garnet phase) after sintering. Combining the alumina powder and yttria powder to form the first powder mixture was performed using wet ball milling, as known to those skilled in the art. High-purity (>99.9%) alumina media was used at a loading of about 55% to about 65% by powder weight. A slurry was formed with about 35% to about 45% ethanol by slurry weight. The slurry was milled at about 150 RPM for about 15 hours, followed by drying, tumbling, and sieving according to methods known to those skilled in the art to form the first powder mixture. The first powder mixture was calcined at 850°C for 6 hours. The calcined first powder mixture contained 3-5 ml of ethanol. 2 The first calcined powder mixture had a specific surface area of ​​0.1 μm / g and a d50 particle size of 3-12 μm. The first calcined powder mixture had about 8 ppm total impurities (measured using ICPMS), including about 1 ppm or less Mg in the form of magnesia MgO, about 0.5 ppm or less Li, and about 5 ppm or less sodium. Si was not detected in the first calcined powder mixture using the ICPMS method disclosed herein, and therefore, within the accuracy of the ICPMS method, the first calcined powder mixture contains about 14 ppm or less Si in the form of silica. The first calcined powder mixture (batch processed to form YAG after sintering) can be sieved, tumbled, blended, etc., as known to those skilled in the art.

[0295] The second powder mixture contained magnesia powder and alumina powder as follows: 99.9994% total purity, corresponding to 6 ppm total impurities, 4-6 ppm 2 Magnesia powder with a surface area of ​​1 / g and an average or d50 particle size of 3-4 μm, a total purity of 99.9995%, corresponding to 5 ppm total impurities, and a solubility of 6-8 m 2The powder was combined with alumina powder having a surface area of ​​1 / g and an average or d50 particle size of 2.5 to 4.5 μm. The powders were weighed in relative amounts to produce a powder mixture in a molar ratio that would form a spinel, MgAl2O4, with a cubic crystal structure upon sintering. The powders were mixed with equal weights of high-purity (99.99%) alumina media and ethanol to form a slurry. Ball milling was performed at 150 rpm for a duration of 12 hours, and the slurry was dried using a rotary evaporator. The powder mixture was calcined at 850 °C for 4 hours in an oxygen-containing environment. The calcined powder mixture can be sieved after calcination, if desired, using methods known in the art. Within the detection limits of X-ray diffraction measurements, the calcined powder mixture showed the presence of magnesium oxide and aluminum oxide, as shown in Figure 12. The properties of the calcined powder mixture are listed in Table 3.

[0296] The first and second sintered powder mixtures are separately placed within a volume defined by a toolset of a sintering apparatus disclosed herein to form at least one first layer of the first sintered powder mixture and at least one second layer of the second sintered powder mixture, and the first and second sintered powder mixtures are placed within the volume. -2 ~10 -3 A vacuum condition of 1000 Torr was created. Disposing the at least one first sintered powder mixture and the at least one second sintered powder mixture within the volume defined by the toolset typically results in intermixing of the first sintered powder mixture with the second sintered powder mixture, thereby creating a nonlinear interface between the at least one first layer and the second layer after sintering.

[0297] The layers of the fired powder mixture were co-compressed by applying a pressure of 15 MPa to the layers of the first fired powder mixture and the second fired powder mixture while heating them to a sintering temperature of 1600°C for 60 minutes to form a single multi-layered sintered ceramic body having a maximum dimension of 572 mm.

[0298] The density of an exemplary magnesium aluminate spinel sintered body (prepared under similar temperature, pressure, and duration conditions as disclosed herein) was measured separately, and the density (using the Archimedes water immersion method) was determined to be 3.47 g / cc, or 97% of theoretical density. The density of an exemplary YAG sintered body (prepared under similar temperature, pressure, and duration conditions as disclosed herein) was measured separately, and the density was determined to be 4.55 g / cc, corresponding to more than 99% of the theoretical density of YAG. (A commercially available single crystal sample of bulk YAG was measured to have an Archimedes density of 4.56 g / cc over five measurements, and this value is considered the theoretical density of YAG as used herein.) The two measurements are within the measurement variance of the Archimedes density measurements disclosed herein; therefore, polycrystalline YAG including at least one first layer may have a density of approximately 100% of theoretical.

[0299] Example 2: At least one first layer comprising polycrystalline YAG

[0300] Approximately 1~2m 2 Yttria powder (purity of approximately 99.9992% for 100% pure yttria) having a specific surface area of ​​1 / g, a d10 particle size of 3.5-6.5 μm, a d50 particle size of 7.5-10.5 μm, and a d90 particle size of 15-20 μm, and a 5-7 m 2Alumina powders (approximately 99.9998% purity for 100% pure alumina) having a specific surface area of ​​0.1 / g, a d10 particle size of 1-3 μm, a d50 particle size of 3.5-6.5 μm, and a d90 particle size of 50-70 μm were combined in a molar ratio to form a first powder mixture that, after sintering, forms at least one first layer containing a cubic yttrium aluminum garnet (YAG) phase. High-purity alumina media (≥99.9% as determined by ICPMS) was added at a loading of approximately 100% by powder weight, and ethanol was added at approximately 40% by combined ethanol and powder weight to form a slurry. Ball milling was performed using a horizontal rotation action at 150 rpm for 20 hours, after which the ethanol was extracted from the powder mixture using rotary evaporation according to known methods. Upon calcination at 1050 °C for 6 hours in air, the calcined powder mixture had a 2-4 m 2 The powders, powder mixtures, and / or calcined powder mixtures were measured to have a specific surface area of ​​0.1 μm / g, a d10 particle size of 1-4 μm, a d50 particle size of 3.5-6.5 μm, and a d90 particle size of 75-95 μm. The powders, powder mixtures, and / or calcined powder mixtures may be sieved, for example, using openings of 45-400 μm, and calcined, blended, and / or milled in various process steps according to methods known to those skilled in the art. Purity was measured using the ICPMS method disclosed herein, and a total impurity content of the calcined powder mixture was measured to be approximately 5 ppm based on the total mass of oxides calculated from all constituents, corresponding to a purity of 99.9995%. The purity limits and impurity content of the yttria and alumina starting powders and the calcined powder mixtures disclosed herein do not include Si. The detection limit using the ICPMS method for measuring purity as disclosed herein for Si is about 14 ppm, and therefore the starting powder and calcined powder mixtures of yttria and alumina may contain Si in the form of silica at detectable levels of about 14 ppm or less.

[0301] The fired powder mixture is placed in a volume defined by the tool set of the sintering apparatus disclosed herein, and -2 ~10 -3 A vacuum condition of 1000 volts was created within the volume.

[0302] Under a pressure of 5 MPa, the sintered powder mixture within the volume was heated from ambient temperature to 800°C at approximately 10°C / min. The pressure was then increased at a rate of approximately 0.4 to approximately 0.6 MPa / min, and the temperature ramp continued as previously disclosed to reach sintering conditions of 1500°C and 20 MPa for 30 minutes to form polycrystalline YAG ceramic bodies. Some of the polycrystalline YAG ceramic bodies were sintered according to the same conditions and then annealed in air at 1400°C for 8 hours in a furnace. Density measurements were performed on the as-sintered and annealed polycrystalline YAG ceramic bodies according to ASTM B962-17. Densities of 4.547 g / cc and 4.542 g / cc were averaged over five measurements for the as-sintered and annealed YAG ceramic body samples, respectively. This corresponds to 99.81% and 99.70% of the theoretical density for YAG, corresponding to volumetric porosities of 0.19% and 0.30%, respectively, as calculated from the density measurements disclosed herein.

[0303] Measurement of the crystalline phase purity of the polycrystalline YAG sintered ceramic body was performed using a combination of XRD, SEM imaging, and the use of image processing software, as disclosed herein. XRD was performed using a PANanlytical Aeris model XRD, which is capable of identifying crystalline phases down to approximately + / - 5% by volume. Therefore, the polycrystalline YAG sintered ceramic body according to this example was determined to contain up to approximately 95% YAG by volume using XRD. To determine phase purity with greater precision, for example, up to approximately 99.8%, SEM images were taken using backscatter detection (BSD) techniques known to those skilled in the art. Using BSD, the YAG phase appears gray, varying somewhat depending on the grain orientation, the aluminum oxide phase appears black, the yttrium oxide phase appears white, and porosity, if present, also appears black. Images were taken at 5000x magnification using BSD techniques known to those skilled in the art to identify the YAG, alumina, and yttria phases, as well as any porosity present, as shown in FIG. 5a), which corresponds to the polycrystalline YAG sintered ceramic body. To distinguish between black regions containing alumina and black regions containing porosity, the BSD image was processed with black and white thresholds using ImageJ processing software to highlight areas that may contain either porosity or alumina, as shown in the same region in Figure 5b. The BSD detector used for the measurements disclosed herein has the additional ability to measure topographic features, thereby highlighting any variations in surface topography, such as porosity. Using the topography mode of the BSD detector, the surface of the same region of the ceramic sintered body of the polycrystalline YAG ceramic body in Figure 5a was photographed at 5000x magnification, and the resulting topography image is shown in Figure 6a. Areas containing porosity were highlighted after thresholding in ImageJ, as shown in Figure 6b. The area containing porosity in the topography image in Figure 6b was then subtracted from the area containing alumina and / or porosity in the BSD image in Figure 5b to obtain the area % and therefore volume % containing alumina in the sintered ceramic body corresponding to the polycrystalline YAG ceramic body. The combination of these analytical tools and methods can provide a determination of phase purity to about + / - 0.1% by volume.Using the disclosed methods of Archimedes density measurement, XRD, SEM imaging, and image analysis software, a polycrystalline YAG-sintered ceramic body according to this example can contain approximately 0.2 vol.% alumina phase, approximately 0.19 vol.% porosity, and approximately 99.6 vol.% YAG phase. A polycrystalline YAG-sintered ceramic body according to this example can include a monolithic body made according to the processes disclosed herein and, therefore, can contain YAG phase, aluminum oxide phase, and volumetric porosity distributed on the surface and throughout the body. In other words, the structure measured on the surface represents the structure within the volume of the bulk sintered ceramic body. Thus, polycrystalline YAG-sintered ceramic bodies can be formed using the materials and methods disclosed herein, each containing an amount of YAG phase of 90-99.8 vol.%, preferably 90-99.6 vol.%, preferably 90-99.4 vol.%, preferably 95-99.8 vol.%, preferably 95-99.6 vol.%, and preferably 95-99.4 vol.%. Taking into account measurement variability, polycrystalline YAG-sintered ceramic bodies containing the amounts of YAG phase specified herein may further include porosity in an amount of 0.1 to 0.3 volume percent, and aluminum oxide in an amount of 0.1 to about 0.3 volume percent.

[0304] The formation and characteristics of the polycrystalline YAG sintered ceramic body according to this embodiment (particularly the high phase purity of the YAG, low porosity, and residual alumina, to the extent that it remains in the sintered ceramic body, as disclosed) are in accordance with the formation and characteristics of at least one first layer of a single multi-layer sintered ceramic body comprising YAG, as disclosed herein. Thus, the at least one first layer of a single multi-layer sintered ceramic body can comprise about 99.4-99.8% polycrystalline YAG by volume, further comprising 0.1-0.3% porosity by volume, and 0.1 to about 0.3% aluminum oxide by volume.

[0305] Example 3: Comparative study

[0306] Five 6-inch disk examples were prepared for evaluation. The first three were magnesium aluminate spinel, the fourth was magnesium aluminate spinel + 1% zirconia by volume, and the final example was magnesium aluminate spinel + 1% yttrium by volume. All starting powders were of high purity. A summary of the materials and conditions is as follows: Sample: 119U21C 6-inch disc Powder (Firing: 3C / min to 800C, hold for 6 hours) Powder composition: Alumina and magnesia (D50-0.5um, SSA-8.5m 2 / g) 4 L Nalgene container, 1000 g Al2O3 10 mm media, 286 g MgO, 717 g Al2O3, 1 L EtOH. Milled at 200 rpm for 16 hours. Sieved to -40 mesh. Powder mass: 400g (before SPS) Target temperature 1650℃ Target pressure: 15MPa Residence: 60 minutes Young's modulus (Pa): 2.43726E+11 Poisson's ratio: 0.274 Density:NA Vickers: 1323.3 CTE: 50~1500(1E-6 / ℃): NA Sample 187U21C 6-inch disc Powder: (Baking: 3°C / min ~ 800°C for 6 hours) (approx. 10 m 2 / g) Powder composition: Alumina / Magnesia (D50-0.5um, SSA-8.5m 2 / g) 4 L Nalgene container, 1.1 kg of 10 mm Al2O3 media, 315 g MgO, 794 g Al2O3, 1.3 L EtOH. Mill at 200 rpm for 15 hours. Sieve to -40 mesh. Powder mass: 500g Target temperature 1650℃ Target pressure: 15MPa Residence: 60 minutes Young's modulus (Pa): 2.68087E+11 Poisson's ratio: 0.283 Density: 3.573g / cc Vickers: 1467.2 CTE:50-1500(1E-6 / ℃):9.7437 Sample 190U21C 6-inch disc Powder: (calcined at 3°C / min to 800°C for 6 hours) Powder composition: Magnesia; Alumina (high purity) 4 L Nalgene, 1.1 kg 10 mm Al2O3 media, 315 g MgO, 790 g Al2O3, 1.3 L EtOH. Mill at 200 rpm for 15 hours. Sieve to -40 mesh. Powder mass: 500g Target temperature 1650℃ Target pressure: 15MPa Residence: 60 minutes Young's modulus (Pa): 2.72584E+11 Poisson's ratio: 0.283 Density: 3.572g / cc Vickers: 1481.9 CTE:50-1500(1E-6 / ℃):9.6665 Sample 195U21C (magnesium aluminate spinel with 1 vol% ZrO2 additive) 6-inch disc Powder: (Firing 3°C / min to 800°C; holding for 6 hours) Powder composition: alumina, magnesia, yttria-stabilized zirconia 4 L Nalgene bottle, 1 kg of 10 mm Al2O3 milling media, 286 g MgO, 717 g Al2O3, 14.0 g ZrO2, 1.3 L EtOH. Milled at 200 rpm for 16 hours. Sieved to -40 mesh. Powder mass: 500g Target temperature 1650℃ Target pressure: 15MPa Residence: 60 minutes Young's modulus (Pa): 3.12928E+11 Poisson's ratio: 0.283 Density: 3.594g / cc Vickers: 1493.6 CTE:50-1500(1E-6 / ℃):9.6348 Sample 204U21C (Sasol+Y) (magnesia aluminate spinel with 1% Y2O3 by volume) 6-inch disc Powder: (Firing 3°C / min to 800°C. Hold for 6 hours) Powder composition: alumina, magnesia, yttrium oxide 4 L Nalgene, 1.0 kg 10 mm Al2O3 media, 719 g Al2O3, 286 g MgO, 11.5 g Y2O3, 1.3 L EtOH (reused). Powder mass: 500g Target temperature 1650℃ Target pressure: 15MPa Residence: 60 minutes Young's modulus (Pa): 3.15392E+11 Poisson's ratio: 0.283 Density: 3.596g / cc Vickers: 1547.7 CTE: 50~1500(1E-6 / ℃): NA

[0307] The first three examples (119U21C, 187U21C, and 190U21C) had grains that were too large and / or exhibited too much porosity. Sample 195U21C (1% stabilized zirconia) exhibited smaller grains and acceptable levels of porosity; therefore, the zirconia appeared to limit grain growth by pinning the grains. Sample 204U21C (1% yttria) had grains that were too large. Surprisingly, the yttrium did not appear to be uniformly distributed, resulting in areas of oversized grains. This can be seen at 5000x magnification in Figure 13.

[0308] Example 4: Multilayer sintered body - YAG on magnesium aluminate spinel

[0309] A 22.5 inch disk of YAG on spinel containing 0.5% by volume zirconia was prepared according to the following conditions. Sample 250F21M YAG 5G jug, 10kg of 10mm Al2O3 media, 4745.45g Al2O3, 6265.56g yttria, 8L EtOH, 20 hours end-over-end milling. Following calcination (1050°C for 6 hours) and sieving through a 40 mesh sieve. Spinel + 0.5% by volume Zr Alumina (high purity) Magnesium oxide (D50-0.5um, SSA-8.5m 2 / g) Yttria-stabilized zirconia Milling vessel: 5-gallon jug, 6 kg of 10 mm Al2O3 media, 5.390 kg Al2O3, 2.147 kg MgO, 59.8 g ZrO2, 11 L EtOH. Bucket tumbling: 20 hours. Slurry sieve: 325 mesh. Rotary evaporator temperature: 60-75°C. Rotary evaporator time: 120 minutes. Oven drying temperature: 120°C. Oven drying time: 480 minutes. 80-mesh pre-calcined sieve. Calcination is carried out at 600°C for 6 hours (calcination gradient 3°C / min). Powder mass before SPS: 4.57 kg / 23.8 kg Target temperature: 1625℃ Target pressure: 15MPa Residence: 120 minutes After polishing: YAG layer thickness: 3.5mm Spinel layer thickness: 26.0 mm

[0310] Referring to Figure 14 (spinel layer) and Figure 15 (YAG layer), the samples had good grain size, but the porosity in both layers was too high. This is likely due to the target temperature being set too low for the larger disk size (6 inch vs. 22.5 inch). The optimal target temperature for disks 22.5 inch and larger is about 1700°C with a 120 minute dwell. Alternatively, at 1625°C, a longer dwell time (i.e., 5 hours) may be sufficient.

[0311] Later, another sample 217U21C of magnesium aluminate spinel was prepared with the same composition (containing 0.5 volume percent zirconia) as the spinel in multilayer sample 250U21M. Flexural strength tests were performed using a Mark-10 7i ESM 1500S model (four-point test), and the results are listed in Table 6. [Table 7]

[0312] The strength of magnesium aluminate spinel (containing 0.5% zirconia by volume) shows that while it is not as strong as expected with a layer of zirconia-toughened alumina (ZTA), magnesium aluminate spinel still has sufficient strength (approximately 60-65% of ZTA; compare the strength data disclosed in paragraph

[0146] ). The advantage is that spinel is easier to machine, reducing machining time by approximately 50%. More specifically, when magnesium aluminate spinel is used as a support layer, it constitutes the majority of the ceramic body's thickness (spinel support layers are 7-8 times thicker than YAG layers). The machining time savings for large disks (over 22.5 inches) can be as much as 14 hours.

[0313] Based on the previous example, the magnesium aluminate spinel preferably contains some zirconia, at least 0.1% by volume, and more preferably at least 0.5% by volume. Zirconia reduces grain growth in the spinel during sintering. However, too much zirconia is undesirable because it affects the resulting CTE to the extent that it no longer closely matches that of the YAG, as shown in FIG. 16. This CTE mismatch can lead to stress buildup during sintering and cooling of the ceramic body, especially for larger sized bodies, such as disks with diameters of at least 6 inches. Therefore, when the spinel serves as a support layer for the YAG, it is preferable to limit the amount of zirconia in the spinel to 1.0% by volume. Specifically, the support layer is the surface that does not face the plasma in the reaction chamber.

[0314] The support layer of the multilayer sintered ceramic body disclosed herein should be strong enough, with a reasonable safety margin, to prevent any components (e.g., window, lid) made therefrom from imploding when a vacuum is applied to the reaction chamber.

[0315] Although illustrated and described above with reference to certain specific embodiments (and examples), the present disclosure is nevertheless not intended to be limited to the details shown. Rather, various modifications in details may be made within the scope and range of equivalents of the claims without departing from the spirit of the present disclosure. For example, all broad ranges described herein are expressly intended to include within their scope all narrower ranges that are included in the broad ranges.

Claims

1. A multilayer sintered ceramic body, at least one first layer comprising polycrystalline YAG, the at least one first layer having at least one surface; at least one second layer comprising magnesium aluminate spinel; Including, the at least one surface of the at least one first layer comprises pores having a maximum size of 0.1 to 5 μm as measured by SEM; Each of the at least one first layer and the at least one second layer has a thermal conductivity of 0 to 0.6×10 measured in accordance with ASTM E228-17 over a temperature range of 25 to 1400° C. －６ % zirconia.

2. 10. The multilayer sintered ceramic body of claim 1, wherein the multilayer sintered ceramic body has a maximum dimension of 100 mm to 625 mm.

3. 10. The multilayer sintered ceramic body of claim 1, wherein the pores have a maximum size of 0.1 to 2 μm as measured by SEM.

4. 4. The multilayer sintered ceramic body of claim 3, wherein the pores have a maximum size of 0.1 to 1 μm as measured by SEM.

5. 10. The multi-layer sintered ceramic body of claim 1, wherein the magnesium aluminate spinel of the at least one second layer comprises 0.5 volume percent zirconia.

6. 1. A method for producing a multilayer sintered ceramic body, comprising: a. combining yttria powder and alumina powder to form a first powder mixture; b. combining magnesium oxide powder, aluminum oxide powder, and zirconium oxide powder to form a second powder mixture; c. firing the first powder mixture and the second powder mixture by applying heat to raise the temperature of the powder mixture to a firing temperature and maintaining the firing temperature to form a first fired powder mixture and a second fired powder mixture; d. Separately disposing the first and second fired powder mixtures into a volume defined by a sintering machine toolset to form at least one layer of the first fired powder mixture and at least one layer of the second fired powder mixture, and creating a vacuum condition within the volume; e. applying pressure to the layers of the first and second fired powder mixtures while heating to a sintering temperature to sinter to form the multi-layer sintered ceramic body, wherein after sintering, the at least one layer of the first fired powder mixture forms at least one first layer and the at least one layer of the second fired powder mixture forms at least one second layer; f) reducing the temperature of the multilayer sintered ceramic body; Including, the at least one first layer comprises polycrystalline YAG, the at least one first layer has at least one surface, and the at least one second layer comprises magnesium aluminate spinel, the at least one surface of the at least one first layer comprises pores, the pores having a maximum size of 0.1 to 5 μm as measured using SEM and image processing methods, and each of the at least one first layer and the at least one second layer has a pore size of 0 to 0.6×10 as measured according to ASTM E228-17 over a temperature range of 25 to 1400° C. －６ / °C, wherein the CTEs of the at least one first layer and second layer used to calculate each difference are each measured over the same temperature range, and the at least one second layer comprises cubic magnesium aluminate spinel (MgAl 2 O 4 ) in an amount of 95 to 100 volume %, and the magnesium aluminate spinel of the at least one second layer comprises 0.1 to 1.0 volume % zirconia.

7. g. Annealing the multi-layer sintered ceramic body by applying heat to raise the temperature of the multi-layer sintered ceramic body to an annealing temperature; h) reducing the temperature of the annealed multi-layer sintered ceramic body; The method of claim 6 further comprising:

8. 7. The method of claim 6, wherein the toolset includes a graphite die having a volume, an inner wall, a first opening, and a second opening, and a first punch and a second punch operatively coupled to the die, each of the first punch and the second punch having an outer wall defining a diameter smaller than a diameter of the inner wall of the die, thereby forming a gap between each of the first punch and the second punch and the inner wall of the die when at least one of the first punch and the second punch moves within the volume of the die.

9. 9. The method of claim 8, wherein the gap is a distance of 10 to 100 μm between the inner wall of the die and the outer wall of each of the first punch and the second punch.

10. 7. The method of claim 6, wherein the magnesium aluminate spinel of the at least one second layer comprises 0.5 volume percent zirconia.

Images