Ceramic base comprising a core / shell structure material as a coating layer

Abstract

Specifically, a ceramic substrate comprising a core / shell structure material as a coating layer is disclosed. The core / shell structure material, containing various physical properties such as plasma resistance and durability, and comprising materials similar to or identical to the substrate, is coated onto a sintered ceramic substrate exhibiting excellent volume resistivity at high temperatures and excellent thermal conductivity at room temperature. This improves plasma resistance, durability, particle resistance, volume resistivity, and thermal conductivity. The ceramic substrate comprises a ceramic plate layer; and a coating layer located on the ceramic plate layer and formed by sintering the core / shell structure material. The ceramic plate layer comprises alumina (Al₂O₃) and aluminum nitride (AlN) but not a second phase of aluminum oxynitride (AlON). The coating layer has a structure in which the granular phase constituting the shell forms a continuous phase along the particle boundaries of the core granular phase.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application No. 10-2024-0084433, filed on June 27, 2024, the entire contents of which are incorporated herein by reference as a part of this specification.

[0002] This invention relates to a ceramic substrate comprising a core / shell structure material as a coating layer, and more specifically, to a ceramic substrate comprising a core / shell structure material as a coating layer, which is coated with a ceramic sintered substrate having excellent volume resistivity at high temperatures and excellent thermal conductivity at room temperature by coating a core / shell structure material having various physical properties such as plasma resistance and durability and being similar to or the same as the substrate with a core / shell structure material having excellent volume resistivity at high temperatures and excellent thermal conductivity at room temperature, thereby having improved volume resistivity and thermal conductivity, as well as plasma resistance, durability and particle resistance. Background Technology

[0003] As semiconductor processes have recently evolved towards miniaturization and high integration to improve yield, and towards larger diameter devices, the use of high-power plasma and processing in harsh, high-temperature environments has become inevitable. Vacuum plasma equipment utilizing high-temperature plasma is widely used in processes for etching semiconductor devices or achieving other ultra-fine shapes. This vacuum plasma equipment includes plasma-enhanced chemical vapor deposition (PECVD) equipment, which uses plasma to form deposited films on substrates via chemical vapor deposition; sputtering equipment, which forms deposited films physically; and dry etching equipment, which etches substrates or materials coated on substrates into specific patterns.

[0004] The high-temperature plasma generated within a vacuum plasma apparatus inevitably damages the cavity and components housed within it. Furthermore, certain elements and contaminants are likely to be generated from the surfaces of the cavity and its components, potentially contaminating the interior. In particular, plasma etching equipment injects reactive gases such as F and Cl into a plasma atmosphere, exposing the inner walls of the cavity and its components to a highly corrosive environment. Typically, this corrosion primarily causes chemical and physical damage to the cavity and its components, secondarily generating contaminants and particles, which increases the defect rate and reduces the quality of products produced through processes within the cavity.

[0005] Furthermore, when the cavity and its internal components are damaged, additional costs arise because some of the damaged equipment needs to be replaced, cleaned, or repaired, necessitating production line shutdowns and increasing the processing time required to manufacture the product. Therefore, metal substrates installed inside existing cavities are being replaced by ceramic substrates, with examples including sintered aluminum nitride (AlN) or sintered alumina (Al2O3) exhibiting excellent thermal conductivity. These ceramic substrates are primarily used in heaters and electrostatic chucks in semiconductor manufacturing processes.

[0006] Aluminum nitride is stable at high temperatures and possesses excellent electrical insulation and thermal conductivity. Furthermore, because aluminum nitride has a similar coefficient of thermal expansion to silicon, it is primarily used in semiconductor manufacturing equipment requiring high electrical resistance at high temperatures. Alumina is also a high-temperature stable material and exhibits superior electrical insulation and higher hardness than aluminum nitride.

[0007] However, these recent ceramic substrates fail to meet the ceramic properties required to withstand harsher high-temperature processing environments, such as volume resistivity and thermal conductivity. Aluminum nitride exhibits a rapid decrease in volume resistivity at 500°C, leading to leakage current. Furthermore, alumina has very low thermal conductivity at room temperature, ranging from 20 to 30 W / m·K. This low thermal conductivity at room temperature can lead to problems such as increased temperature uniformity deviations and reduced yield. Moreover, large temperature uniformity deviations in thermal conductivity can shorten product lifespan due to thermal stress and thermal shock.

[0008] Furthermore, even when using ceramic components such as sintered aluminum nitride or sintered alumina, the problem of reduced corrosion resistance due to plasma persists, as does the generation of contaminant particles from the component surface due to halogen gases (F, Cl, Br, I, etc.). Therefore, industry has attempted to improve plasma corrosion resistance by coating the surface of ceramic components with plasma-resistant fluorine-based materials such as YOF, AlF, LaF, and YF3 or yttrium oxide (Y2O3) using methods such as plasma spraying, aerosol deposition, PVD, or CVD. However, in this case, the relative density is low, causing the coating to peel off from the substrate or form pores within the coating. This not only reduces plasma corrosion resistance but also leads to powder loss from the coating, resulting in fine particles and increased processing costs.

[0009] To address these issues, research is underway on the use of yttrium aluminum garnet (YAG, Y3Al5O3). 12Various attempts have been made to develop yttrium aluminum garnet (YAG) as a coating material. As a compound of yttrium oxide and aluminum oxide, YAG is a ceramic material with high thermal stability, creep resistance, optical properties, and plasma resistance. However, developing these coating materials alone presents problems such as the formation of pores or cracks at the interface between the substrate and the coating. This is because the differences in physical and thermal properties between the substrate and the coating material make it difficult to form a dense bond, leading to coating peeling or damage.

[0010] Therefore, there is a need to develop a new type of ceramic component that exhibits excellent volume resistivity and thermal conductivity in recent semiconductor processes using high-temperature environments and high-power plasmas. This component can be coated in the following manner: a plasma-resistant component is coated on the surface of the ceramic component, so that the coating does not peel off from the substrate and does not generate fine particles, and the substrate and coating are tightly bonded together, thus exhibiting excellent plasma resistance and durability. Summary of the Invention

[0011] Technical issues

[0012] Therefore, the object of the present invention is to provide a ceramic substrate that has improved volume resistivity and thermal conductivity, as well as plasma resistance, durability and particle resistance, by coating a ceramic sintered substrate with a core / shell structure material containing a material that has various physical properties such as plasma resistance and durability and is similar to or the same as the substrate.

[0013] Technical solution

[0014] To achieve the above objectives, the present invention provides a ceramic substrate comprising: a ceramic plate layer; and a coating layer located on the ceramic plate layer and formed by sintering a core / shell structure material, wherein the ceramic plate layer comprises alumina (Al2O3) and aluminum nitride (AlN) and does not contain a second phase of aluminum oxynitride (AlON), and the coating layer has a structure in which the granular phase constituting the shell forms a continuous phase along the particle boundaries of the core granular phase.

[0015] Beneficial effects

[0016] According to the present invention, a ceramic substrate comprising a core / shell structure material as a coating layer is coated with a ceramic sintered substrate having excellent volume resistivity at high temperatures and excellent thermal conductivity at room temperature by coating a core / shell structure material having various physical properties such as plasma resistance and durability and being similar to or the same as the substrate. This improves volume resistivity and thermal conductivity, as well as plasma resistance, durability and particle resistance. Attached Figure Description

[0017] Figure 1 This is a cross-sectional view of the core / shell structured material particles contained in the ceramic base of the present invention.

[0018] Figure 2 This is a schematic cross-sectional view showing the internal structure of the coating layer formed by sintering the core / shell structure material contained in the ceramic substrate of the present invention.

[0019] Figure 3 This is an XRD pattern showing the changes in the physical properties of the ceramic substrate with sintering temperature.

[0020] Figure 4 This is a graph showing the correlation between alumina content and sintering temperature.

[0021] Figure 5 This is an XRD pattern of the coating layer of a ceramic substrate according to one embodiment of the present invention.

[0022] Figure 6 This is the XRD pattern of a conventional ceramic substrate.

[0023] Figure 7 This is an image of the coating layer of a ceramic substrate according to an embodiment of the present invention, as observed using a transmission electron microscope (TEM).

[0024] Figure 8 This is an image of a cross-section of a ceramic base according to an embodiment of the present invention, as observed using a scanning electron microscope (SEM).

[0025] Figure 9 This is a cross-sectional image of the coating layer of a ceramic substrate according to an embodiment of the present invention, as observed using a scanning electron microscope (SEM).

[0026] Figure 10 This is an image of a cross-section of a conventional ceramic substrate as observed using a scanning electron microscope (SEM).

[0027] Figure 11 This is a cross-sectional image of the surface where the ceramic plate layer and the core / shell coating layer of a ceramic substrate of one embodiment of the present invention are bonded, as observed using a scanning electron microscope (SEM, 800x magnification).

[0028] Figure 12 This is a cross-sectional image of the surface where the ceramic plate layer and the core / shell coating layer of a ceramic substrate of one embodiment of the present invention are bonded, as observed using a scanning electron microscope (SEM, 2,000x magnification). Detailed Implementation

[0029] The present invention will now be described in detail.

[0030] The ceramic base of the present invention comprises a ceramic plate layer and a coating layer located on the ceramic plate layer and formed by sintering a core / shell structure material, wherein the ceramic plate layer comprises alumina (Al2O3) and aluminum nitride (AlN) and does not contain a second phase of aluminum oxynitride phase (AlON phase), and the coating layer has a structure in which the granular phase constituting the shell forms a continuous phase along the particle boundary of the core granular phase.

[0031] In addition, a separate coating layer containing the same or different components as the coating layer may be additionally located on top of the coating layer.

[0032] As semiconductor processes become increasingly miniaturized and highly integrated, the use of high-power plasma is inevitable. Therefore, vacuum plasma equipment utilizing high-temperature plasma is widely used for etching semiconductor devices or achieving other ultra-fine shapes. Consequently, the industry is replacing existing metal substrates with ceramic substrates made of sintered aluminum nitride (AlN) or sintered alumina (Al2O3), which possess excellent resistance to plasma corrosion. In particular, recently, to achieve process miniaturization and increase equipment diameter to improve semiconductor process yield, semiconductor manufacturing processes are being carried out in harsher environments, such as 600 to 700°C. Furthermore, to withstand such environments, ceramic substrates must meet ceramic properties such as a volume resistivity of 1.0E+10 to 1.0E+13 Ω·cm at 500°C and a thermal conductivity of 30 to 60 W / m·K or higher at room temperature.

[0033] However, in the case of aluminum nitride, the volume resistivity decreases rapidly at 500°C, which tends to generate leakage current. Furthermore, in the case of alumina, there is a problem with very low thermal conductivity at room temperature, at the level of 20 to 30 W / m·K. A thermal conductivity of only 20 to 30 W / m·K at room temperature can lead to problems such as increased temperature uniformity deviations and reduced yield. In addition, when the temperature uniformity deviation of thermal conductivity is large, thermal stress and thermal shock may shorten the product's lifespan. Therefore, as a substrate that can be used at temperatures above 500°C, the applicant has essentially provided a ceramic plate that exhibits high volume resistivity even at temperatures above 500°C, thereby preventing leakage current, and also has a higher room temperature thermal conductivity than usual, which solves the aforementioned problems.

[0034] The ceramic plate layer included in the ceramic base of the present invention serves as the substrate of the ceramic base. The ceramic plate is a sintered body containing alumina (Al2O3) and aluminum nitride (AlN) as the main phases. Alumina not only has excellent electrical insulation and high hardness, but is also stable at high temperatures. Aluminum nitride is stable at high temperatures and has excellent electrical insulation and thermal conductivity.

[0035] In particular, the present invention is characterized by solving the problems that occur when alumina and aluminum nitride are used alone, and the problems that occur when alumina and aluminum nitride are not mixed in the optimal ratio, by mixing alumina and aluminum nitride in an optimal ratio. Specifically, by mixing alumina and aluminum nitride in the optimal ratio as in the present invention, the physical properties of the ceramic substrate can be improved as much as possible by achieving a state in which the alumina phase and aluminum nitride phase are uniformly mixed and distributed without changing the crystal phase, for example, without the formation of a second phase of AlON phase. Furthermore, by performing the sintering process at an optimal temperature (below 1,650°C, preferably above 1,300°C and below 1,650°C) in the process of preparing the ceramic plate layer, the formation of the second phase can be prevented more thoroughly. Therefore, the ceramic plate layer satisfies the ceramic properties of 1.0E+10 to 1.0E+13 Ω·cm at 500°C and 30 to 60 W / m·K at room temperature.

[0036] The ceramic plate layer contains more than 68% by weight and less than 99.8% by weight, preferably 70 to 95% by weight, more preferably 70 to 80% by weight, and most preferably 73 to 77% by weight of alumina. Furthermore, the ceramic plate layer contains more than 0.2% by weight and less than 32% by weight, preferably 5 to 30% by weight, more preferably 20 to 30% by weight, and most preferably 23 to 27% by weight of aluminum nitride. When the content ranges of alumina and aluminum nitride are not met, the volume resistivity at 500°C or the thermal conductivity at room temperature will not meet the requirements, thus failing to satisfy the ceramic properties that the ceramic plate layer should have a volume resistivity of 1.0E+10 to 1.0E+13 Ω·cm at 500°C and a thermal conductivity of 30 to 60 W / m·K at room temperature.

[0037] Preferably, the alumina and aluminum nitride have a purity of 99% or higher and their particles have a nanoscale size, and preferably, both are used in powder form.

[0038] More specifically, the size of the alumina particles can range from nanometers to micrometers. For example, the alumina particles can be obtained by mixing alumina particles with a size of 3 to 5 μm and alumina particles with a size of about 50 nm in a weight ratio of about 7:3 and then pulverizing the mixture by a ball milling process. However, the particle size and mixing ratio can vary widely, and the ball milling process can be excluded; therefore, the present invention is not limited to the above examples.

[0039] Furthermore, the average particle size (D50) of the aluminum nitride particles can be 0.5 to 1.5 μm, preferably 0.8 to 1.3 μm, and more preferably 0.9 to 1.2 μm. When the average particle size (D50) of the aluminum nitride particles is less than 0.5 μm, the reaction temperature may decrease, which may lead to the formation of a second phase by reacting with alumina at low temperatures. Furthermore, when the average particle size (D50) of the aluminum nitride particles exceeds 1.5 μm, a dense / close-packed structure with alumina may not be formed, which may lead to a decrease in density during the final sintering process. Moreover, in this invention, it is preferable to exclude aluminum nitride particles with nanoscale dimensions as much as possible.

[0040] Furthermore, the ceramic plate layer can be further incorporated with dopants as needed. Dopants can be used to further improve the thermal conductivity of the ceramic plate layer.

[0041] For example, when a conventional sintered body is applied to a substrate and a semiconductor ceramic heater or electrostatic chuck is used at temperatures above 500°C, the substrate may be damaged by thermal shock due to rapid temperature changes in the heating element. However, to improve the thermal shock resistance of the substrate, dopants are mixed and applied to the heater or electrostatic chuck, thereby effectively transferring heat from the heating element and preventing the substrate from being damaged by thermal shock. Examples of such dopants include one or more of magnesium oxide (MgO), yttrium oxide (Y₂O₃), graphene, and rare earth composite oxides.

[0042] When the ceramic plate layer contains dopants, the dopant content can be 0.05 to 2 parts by weight, preferably 0.1 to 1 part by weight, and more preferably 0.2 to 0.8 parts by weight, based on the total weight of 100 parts by weight of alumina and aluminum nitride. When the dopant content is less than 0.05 parts by weight or not present at all based on the total weight of 100 parts by weight of alumina and aluminum nitride, the previously existing problems may remain unchanged, or the effects obtainable by using dopants may be significantly reduced, thus the degree of improvement in thermal conductivity may be minimized, and incomplete sintering problems may also occur. Furthermore, when the dopant content exceeds 2 parts by weight based on the total weight of 100 parts by weight of alumina and aluminum nitride, the dispersion effect may decrease, the thermal conductivity may decrease, and the sintering density may tend to decrease. In addition, due to the influence of dopants, the color of the product may darken, or the color of the dopant may be expressed as is. Furthermore, preferably, all dopants used in this invention have a purity of 99% or higher. Furthermore, preferably, the content of each dopant is 0.05 to 0.5 parts by weight.

[0043] Magnesium oxide can be included as one of the dopants to improve the thermal conductivity and volume resistivity of the ceramic substrate. Magnesium oxide can induce the formation of the MgAl₂O₄ or MgAlON phases by sintering with alumina and / or aluminum nitride. However, when the MgAl₂O₄ or MgAlON phases are formed in excess, the density may decrease, which can actually reduce the thermal conductivity. Therefore, even when using the same composition, it is necessary to control the content of the components. For example, in this invention, based on the total weight of the ceramic substrate, the content of at least one of the MgAl₂O₄ and MgAlON phases included in the final ceramic substrate can be less than 1% by weight, preferably less than 0.8% by weight, more preferably less than 0.6% by weight. Furthermore, there is no particular limitation on the particle size of the magnesium oxide, but nano-sized particles that may exhibit relatively weak effects are preferably excluded.

[0044] Yttrium oxide (Y₂O₃) may be included to improve the thermal conductivity of the ceramic plate layer. The purity of the yttrium oxide is preferably 99% or higher, and the yttrium oxide particles are preferably nano-sized in terms of improving physical properties through densification. Furthermore, the yttrium oxide is preferably used in powder form. More specifically, the average particle size (D₅₀) of the yttrium oxide particles can be 50 to 150 nm, preferably 70 to 120 nm, and more preferably 90 to 100 nm. When the average particle size (D₅₀) of the yttrium oxide particles is less than 50 nm, even when included in trace amounts, there is a concern that the sintered body may have the color (yellow, etc.) of the yttrium oxide particles due to the characteristics of nano-sized yttrium oxide powder. Furthermore, when the average particle size (D₅₀) of the yttrium oxide particles exceeds 150 nm, an incompletely sintered body may be formed during sintering, which may lead to a decrease in thermal conductivity due to reduced density. In particular, this problem may be more pronounced when the average particle size (D50) of yttrium oxide particles is at the micrometer level.

[0045] Graphene may also be included to improve the thermal conductivity of the ceramic substrate. The graphene preferably has a purity of 99% or higher, the graphene particles are nanoscale, and this graphene is preferably used in powder form (graphene nanopowder, GNP). More specifically, the average particle size (D50) of the graphene particles can be 0.1 to 1.5 nm, preferably 0.3 to 1 nm, and more preferably 0.5 to 0.8 nm. When the average particle size (D50) of the graphene particles is less than 0.1 nm, the size of the graphene particles may be insufficient to act as a bridge between the graphene particles, thus the improvement in thermal conductivity may be minimized or nonexistent. Furthermore, when the average particle size (D50) of the graphene particles exceeds 1.5 nm, the graphene particles may entangle with each other and may not be well dispersed, which may lead to a decrease in thermal conductivity due to reduced density.

[0046] Finally, the rare earth composite oxide comprises two or more rare earth metals selected from the group consisting of scandium (Sc), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). The purity of the rare earth composite oxide containing these rare earth metals is preferably 99% or higher. The rare earth composite oxide is preferably in the form of a powder, and there are no particular limitations on the size of the powder particles.

[0047] Rare earth composite oxides can further improve the thermal conductivity of ceramic substrates. Furthermore, by using rare earth composite oxides, the time required for desorption can be reduced. Rare earth composite oxides can contain two or more rare earth metals as described above, and preferably contain two to five different rare earth metals.

[0048] Examples of rare earth composite oxides containing 2 to 5 different rare earth metals include: composite oxides containing two different rare earth metals, such as europium-gadolinium composite oxide (EuGdOx), samarium-gadolinium composite oxide (SmGdOx), cerium-europium composite oxide (CeEuOx), samarium-cerium composite oxide (SmCeOx), gadolinium-samarium composite oxide (GdSmOx), and lanthanum-cerium composite oxide (LaCeOx); composite oxides containing three different rare earth metals, such as samarium-cerium-europium composite oxide (SmCeEuOx), gadolinium-cerium-lanthanum composite oxide (GdSmOx), and lanthanum-cerium composite oxide (GdSmOx). The oxides include: (GdCeLaOx) and europium-gadolinium-samarium composite oxides (EuGdSmOx); composite oxides containing four different rare earth metals, such as samarium-cerium-gadolinium-europium composite oxides (SmCeGdEuOx) and gadolinium-samarium-europium-lanthanum composite oxides (GdSmEuLaOx); and composite oxides containing five different rare earth metals, such as samarium-cerium-europium-gadolinium-lanthanum composite oxides (SmCeEuGdLaOx); in addition, any other oxides may be used without particular restrictions, as long as they contain two to five different rare earth metals (oxides).

[0049] Rare earth composite oxides containing 2 to 5 different rare earth metals can contain different types of rare earth metals in various mixing ratios. For example, rare earth composite oxides containing 2 to 5 different rare earth metals can contain two rare earth metals (oxides) in a weight ratio of 2.5 to 3.5:1, three rare earth metals (oxides) in a weight ratio of 1 to 3.5:0.5 to 2.5:1, four rare earth metals (oxides) in a weight ratio of 1.5 to 3.5:0.5 to 2.5:1, or five rare earth metals (oxides) in a weight ratio of 1 to 3:0.5 to 1.5:0.5 to 1.5:1 to 2:1, etc., thereby maximizing the effect of the target rare earth composite oxide and allowing for appropriate combination of rare earth metals (oxides). For example, the weight ratio of each rare earth metal (oxide) in SmCeEuOx can be 2:1:1, the weight ratio of GdCeLaOx can be 3:2:1, the weight ratio of EuGdSmOx can be 1.5:1.5:1, the weight ratio of SmCeGdEuOx can be 2:1:1.5:1, the weight ratio of GdSmEuLaOx can be 3:2:2:1, and the weight ratio of SmCeEuGdLaOx can be 2:1:1:1.5:1.

[0050] In rare earth composite oxides, one rare earth metal can be dissolved in another (or any) rare earth metal oxide. This alters the crystal structure of the rare earth metal oxide, resulting in a rare earth composite oxide with increased oxygen lattice defects compared to a single rare earth metal oxide. In this way, the rare earth composite oxide with increased oxygen lattice defects exhibits improved interfacial reactivity, thus enabling it to react effectively with interfacial or lattice oxygen within the ceramic substrate.

[0051] Furthermore, examples of rare earth metal oxides containing one rare earth metal include scandium oxide (Sc2O3), lanthanum oxide (La2O3), cerium oxide (CeO2), and praseodymium oxide (Pr6O3). 11 The rare earth metals include neodymium oxide (Nd₂O₃), promethium oxide (Pm₂O₃), samarium oxide (Sm₂O₃), europium oxide (Eu₂O₃), gadolinium oxide (Gd₂O₃), terbium oxide (Tb₄O₇), dysprosium oxide (Dy₂O₃), holmium oxide (Ho₂O₃), erbium oxide (Er₂O₃), thulium oxide (Tm₂O₃), ytterbium oxide (Yb₂O₃), and lutetium oxide (Lu₂O₃), but the present invention does not include rare earth metal oxides containing only one rare earth metal as dopants.

[0052] Furthermore, although the dopant is described above as comprising at least one of magnesium oxide, yttrium oxide, graphene, and other rare earth metal oxides other than yttrium oxide, preferably, the present invention substantially comprises magnesium oxide as a dopant. Moreover, it is preferable to use magnesium oxide and graphene together as a dopant. Furthermore, it is more preferable to use magnesium oxide, graphene, and yttrium oxide together as a dopant. Most preferably, it is preferable to use magnesium oxide, graphene, yttrium oxide, and a rare earth composite oxide together as a dopant.

[0053] When magnesium oxide and graphene are used together as dopants, the content of magnesium oxide can be 0.05 to 0.5 parts by weight and the content of graphene can be 0.05 to 0.5 parts by weight, based on the total weight of 100 parts by weight of aluminum oxide and aluminum nitride.

[0054] Furthermore, when magnesium oxide, graphene, and yttrium oxide are used together as dopants, the content of magnesium oxide can be 0.05 to 0.5 parts by weight, the content of graphene can be 0.05 to 0.5 parts by weight, and the content of yttrium oxide can be 0.05 to 0.5 parts by weight, based on the total weight of 100 parts by weight of aluminum oxide and aluminum nitride.

[0055] Furthermore, when magnesium oxide, graphene, yttrium oxide, and rare earth composite oxide are used together as dopants, the content of magnesium oxide can be 0.05 to 0.5 parts by weight, the content of graphene can be 0.05 to 0.5 parts by weight, the content of yttrium oxide can be 0.05 to 0.5 parts by weight, and the content of rare earth composite oxide can be 0.05 to 0.5 parts by weight, based on the total weight of 100 parts by weight of aluminum oxide and aluminum nitride.

[0056] The coating layer formed on the ceramic plate layer of the ceramic base of the present invention will be described in detail below.

[0057] Hereinafter, the term "yttrium-aluminum oxide" should be understood to refer to at least one of the crystalline phase forms of yttrium-aluminum oxide, including Y3Al5O 12 Yttrium aluminum garnet (hereinafter abbreviated as YAG), YAlO3 (Yttrium aluminum perovskite (hereinafter abbreviated as YAP), Y4Al2O9 (Yttrium aluminum monoclinic crystal (hereinafter abbreviated as YAM)) and combinations thereof. The terms "YAG" and "YAG phase" are used interchangeably in this invention.

[0058] As used herein, the term “alumina” should be understood to include aluminum oxides including Al2O3, the term “yttrium oxide” should be understood to include yttrium oxides including Y2O3, and the term “spinel” should be understood to include magnesium aluminate spinel including MgAl2O4.

[0059] It should also be noted that the terms "core" and "core particle" are used interchangeably in this invention, as are the terms "shell" and "shell particle".

[0060] The coating layer formed on the ceramic plate is located on the ceramic plate and is formed by sintering the core / shell structure material.

[0061] Furthermore, the coating formed by sintering the core / shell structure material meets the high volume resistivity and thermal conductivity required by electrostatic chucks or ceramic heaters, and also has high strength / hardness and density as well as excellent plasma resistance.

[0062] Ceramic substrates with this coating formed on ceramic plates have low levels of metal and particulate contamination, minimizing particulate generation even when exposed to extreme conditions such as high temperatures and high-energy plasmas during semiconductor manufacturing processes.

[0063] Figure 1 This is a cross-sectional view of the core / shell structured material particles contained in the ceramic substrate of the present invention. More specifically, as shown... Figure 1 As shown, the core / shell structure material includes a core containing an aluminum compound and a shell surrounding the core and coated on the core surface.

[0064] The core comprises a ceramic material having high volume resistivity and thermal conductivity, and preferably comprises at least one of aluminum oxide and aluminum nitride (AlN) in the form of aluminum compounds, with the aluminum oxide preferably being alumina (Al₂O₃). Furthermore, the core may also comprise various ceramic materials having high volume resistivity and thermal conductivity and used in conventional electrostatic chucks and ceramic heaters. However, it is more preferable that the core comprises only an aluminum compound. Moreover, the aluminum compound is preferably contained in the core in powder form; therefore, the core may be in the form of particles.

[0065] The shell coated on the core surface contains a mixture of metals or ceramics with excellent plasma resistance.

[0066] Plasma-resistant metal or ceramic compounds can be selected from one of the following groups: yttrium aluminum garnet (Y3Al5O4) 12 The group consisting of yttrium-aluminum oxides, yttrium oxides, magnesium oxides, yttrium oxide-aluminum-silica (or yttrium aluminosilicate, Y2O3-Al2O3-SiO2, YAS), magnesium silicate (Mg2SiO4), and mullite (3Al2O3·2SiO2), with yttrium-aluminum garnet (YAG, Y3Al5O3) being preferred. 12 Yttrium oxide (Y2O3) or magnesium oxide are used as plasma-resistant metal or ceramic compounds.

[0067] Furthermore, preferably, the plasma-resistant metal or ceramic compound is contained in the shell in powder form, so the shell can be in the form of particles.

[0068] Therefore, the core / shell structure material can be, for example, in the form of yttrium-aluminum oxide shell particles, yttrium oxide shell particles, or magnesium oxide shell particles coated on the surface of alumina core particles or aluminum nitride core particles.

[0069] Meanwhile, YAG shell particles can be formed by directly coating commercially available YAG powder onto the surface of the core particles, or by coating the surface of the core particles with YAG powder prepared by reacting and sintering a mixture of yttrium oxide (e.g., Y2O3) and aluminum oxide (e.g., Al2O3) powders.

[0070] However, preferably, by heat-treating and ball-milling the powder coated with yttrium oxide on the surface of alumina core particles or aluminum nitride core particles, all or at least a portion of the yttrium oxide is converted into the YAG phase through the reaction between alumina or aluminum nitride and yttrium oxide, so that the converted YAG phase surrounds the surface of alumina core particles or aluminum nitride core particles.

[0071] In other words, preferably, by forming a yttrium oxide coating layer on the surface of aluminum nitride core particles or aluminum oxide core particles, and performing heat treatment and ball milling, the yttrium oxide coated on the surface of the core particles can react with the aluminum nitride or aluminum oxide in the coating layer and be converted into the YAG phase, thereby forming an aluminum nitride-YAG core / shell structure material or an aluminum oxide-YAG core / shell structure material.

[0072] In this case, preferably, the content ratio of alumina to yttrium oxide or the content ratio of aluminum nitride to yttrium oxide is appropriately adjusted so that the yttrium oxide coated on the surface of the alumina core particles or aluminum nitride core particles in order to form a YAG shell is completely converted into the YAG phase by reacting with alumina or aluminum nitride. At the same time, the remaining amount of alumina or aluminum nitride inside the shell that has been converted into the YAG phase can form a core.

[0073] Preferably, the content ratio of alumina to yttrium oxide or aluminum nitride to yttrium oxide in the core / shell structure material is adjusted according to the content of the YAG shell, so that all yttrium oxide can be converted into the YAG phase through the reaction of alumina or aluminum nitride with yttrium oxide to form a YAG shell. In this case, the content of alumina core particles or aluminum nitride core particles is preferably 50 to 85% by weight relative to the total weight of the core / shell structure material, and the content of YAG shell particles is preferably 15 to 50% by weight.

[0074] When the YAG shell particle content is less than 15% by weight, the hardness and density of the coating prepared by sintering the core / shell structure material decrease, making it difficult to ensure sufficient plasma resistance. Furthermore, when the YAG shell particle content exceeds 50% by weight, the volume resistivity and thermal conductivity of the ceramic substrate resulting from the coating decrease, making it difficult to apply this material to electrostatic chucks or ceramic heaters.

[0075] Meanwhile, when the core / shell structure material is alumina core particles or aluminum nitride core particles coated with yttrium oxide shell particles, the content of alumina core particles or aluminum nitride core particles is preferably 70% to 90% by weight, and the content of yttrium oxide shell particles is preferably 10% to 30% by weight.

[0076] Even in this case, during the sintering process, the yttrium oxide shell particles are transformed into the YAG phase through the reaction sintering of alumina core particles or aluminum nitride core particles with the yttrium oxide shell particles. In this case, the content of alumina core particles or aluminum nitride core particles is preferably 50% to 85% by weight relative to the total weight of the coating layer, and the content of YAG is preferably 15% to 50% by weight.

[0077] Here, the thickness ratio of the core and shell can be appropriately adjusted to achieve a composition that satisfies the range of contents of alumina or aluminum nitride as the core component and YAG or yttrium oxide as the shell component in the core / shell structure material.

[0078] More specifically, when the core particle radius is R1 and the shell thickness (i.e., the distance from the outermost surface of the core to the outermost surface of the shell) is R2, if the core / shell structure material is composed of aluminum nitride-YAG or aluminum oxide-YAG, the R1 / R2 value is preferably set to 4 to 25. Furthermore, when the core / shell structure material is composed of aluminum nitride-yttrium oxide or aluminum oxide-yttrium oxide, the R1 / R2 value is preferably set to 9 to 42.

[0079] Furthermore, when the core / shell structure material is alumina core particles or aluminum nitride core particles coated with magnesium oxide shell particles, the content of alumina core particles or aluminum nitride core particles is preferably 97.2% to 85% by weight, and the content of magnesium oxide particles is preferably 2.8% to 15% by weight.

[0080] Furthermore, during the sintering process, the magnesium oxide shell particles are transformed into magnesium aluminate spinel (MgAl2O4, hereinafter referred to as "spinel") phase through reaction sintering with alumina core particles or aluminum nitride core particles. In this case, the content of alumina or aluminum nitride relative to the total weight of the coating layer is preferably 50% to 90% by weight, and the content of spinel is preferably 10% to 50% by weight.

[0081] Here, the content of alumina core particles or aluminum nitride core particles and magnesium oxide shell particles can be controlled by adjusting the thickness ratio of alumina core particles or aluminum nitride core particles to magnesium oxide shell particles.

[0082] More specifically, when the particle radius of the core is R1 and the thickness of the shell (i.e., the distance from the outermost surface of the core to the outermost surface of the shell) is R2, if the core / shell structure material is composed of aluminum nitride-magnesium oxide or aluminum oxide-magnesium oxide structure, the R1 / R2 value is preferably 16 to 114.

[0083] Additionally, the shell may contain at least one element selected from the group consisting of yttrium oxide-aluminum oxide-silicon dioxide (Y2O3-Al2O3-SiO2, YAS), carbon (C), boron nitride (BN), silicon carbide (SiC), scandium (Sc), and niobium (Nb).

[0084] The coating layer formed by sintering the core / shell structure material and located on the ceramic plate will be described in more detail below. Figure 2 This is a schematic cross-sectional view showing the internal structure of the coating layer formed by sintering the core / shell structure material contained in the ceramic substrate of the present invention.

[0085] The coating layer is formed by sintering the aforementioned core / shell structure material, and has a structure in which the granular phase constituting the shell forms a continuous phase along the particle boundaries of the core granular phase. Here, the term "continuous phase" refers to an aggregate (bond) of individual shell granular phases surrounding multiple core granular phases. Therefore, as... Figure 2 As shown, the overall appearance of the coating layer has the form of multiple core-particle phases partially located within a continuous phase composed of a shell.

[0086] The coating layer located on the ceramic plate is formed by mixing aluminum nitride or alumina material with high volume resistivity and thermal conductivity with YAG or spinel material with excellent plasma resistance, and sintering with a core / shell structure material, so that the aluminum nitride or alumina phase is surrounded by YAG or spinel phase and is not exposed to plasma.

[0087] That is, the coating layer can be formed by sintering the above-mentioned aluminum nitride-YAG core / shell structure material or aluminum oxide-YAG core / shell structure material, or by sintering the above-mentioned aluminum nitride-yttrium oxide core / shell structure material, aluminum oxide-yttrium oxide core / shell structure material, aluminum nitride-magnesium oxide core / shell structure material or aluminum oxide-magnesium oxide core / shell structure material.

[0088] When sintering aluminum nitride-YAG core / shell structured materials or alumina-YAG core / shell structured materials, such as Figure 2As shown, the YAG phase constituting the shell forms a continuous YAG phase along the particle boundaries of the aluminum nitride or aluminum oxide phase constituting the core.

[0089] That is, aluminum nitride or aluminum oxide particles are sintered while being surrounded by a continuous YAG phase, preventing them from being exposed on the surface of the coating.

[0090] Therefore, due to the aforementioned internal crystal structure, even when the coating is exposed to plasma, the exposure of aluminum nitride or aluminum oxide particles to plasma can be minimized, and only the YAG phase, which has relatively low chemical activity and excellent resistance to chemical corrosion, is exposed to plasma, thereby improving the plasma resistance of the coating to a level comparable to or similar to that of bulk YAG sintered bodies.

[0091] Furthermore, due to the aluminum nitride or alumina phase surrounded by a continuous YAG phase within the coating layer, the physical properties of the coating layer can be maintained at a level comparable to or similar to those of conventional bulk aluminum nitride or alumina sintered bodies, even in terms of volume resistivity and thermal conductivity.

[0092] Furthermore, as can be seen from the above description, since the coating layer has similar physical properties to the ceramic plate layer, it can bond with the ceramic plate layer with high strength, thereby significantly reducing coating peeling and particle generation compared with conventional materials.

[0093] Meanwhile, when a coating layer is formed by sintering aluminum nitride-yttrium oxide core / shell structure material or aluminum oxide-yttrium oxide core / shell structure material, during the sintering process, all or at least a portion of the yttrium oxide is converted into the YAG phase through the reaction sintering of the yttrium oxide constituting the shell with the aluminum nitride or aluminum oxide constituting the core.

[0094] In this case, similar to the sintering of the aluminum nitride-YAG core / shell structured materials or alumina-YAG core / shell structured materials mentioned above, the YAG phase reacts with yttrium oxide and forms a continuous YAG phase along the particle boundaries of the remaining aluminum nitride or alumina phase.

[0095] Therefore, even when a coating is formed by sintering an aluminum nitride-yttrium oxide core / shell material or an aluminum oxide-yttrium oxide core / shell material, it still has the same internal crystal structure as a coating formed by sintering an aluminum nitride-YAG core / shell material or an aluminum oxide-YAG core / shell material, thus ensuring excellent plasma resistance properties and even maintaining the high volume resistivity and thermal conductivity required by conventional electrostatic chucks or ceramic heaters.

[0096] Furthermore, when a coating layer is formed by sintering an aluminum nitride-magnesium oxide core / shell structure material or an aluminum oxide-magnesium oxide core / shell structure material, during the sintering process, all or at least a portion of the magnesium oxide is transformed into a spinel phase through the reaction of the magnesium oxide constituting the shell with the aluminum nitride or aluminum oxide constituting the core. At this time, the transformed spinel phase reacts with the magnesium oxide and forms a continuous spinel phase along the particle boundaries of the remaining aluminum nitride or aluminum oxide phase.

[0097] Therefore, even in the case of coatings formed by sintering aluminum nitride-magnesium oxide core / shell materials or alumina-magnesium oxide core / shell materials, the aluminum nitride or alumina particles are surrounded by a spinel phase continuously formed along their particle boundaries, thereby minimizing plasma exposure. Furthermore, since only the relatively chemically inactive and chemically resistant spinel phase is exposed to the plasma, not only are excellent plasma resistance properties ensured, but the high volume resistivity and thermal conductivity required by conventional electrostatic chucks or ceramic heaters can also be maintained.

[0098] In the coating layer formed in this manner, the content of alumina or aluminum nitride present in the alumina-YAG core / shell coating layer or the aluminum nitride-YAG core / shell coating layer is preferably from 50% to 85% by weight, and the content of YAG is preferably from 15% to 50% by weight. Furthermore, the content of alumina or aluminum nitride in the alumina-spinel core / shell coating layer or the aluminum nitride-spinel core / shell coating layer is preferably from 50% to 90% by weight, and the content of spinel is preferably from 10% to 50% by weight.

[0099] When the content of alumina or aluminum nitride deviates from the above-mentioned range and is less than 50% by weight, the volume resistivity and thermal conductivity of the ceramic substrate will decrease due to the coating layer, hindering its application as an electrostatic chuck or ceramic heater. Furthermore, the bonding strength with the ceramic plate layer may also weaken. Additionally, when the content of alumina or aluminum nitride exceeds the upper limit of the above range, the content of YAG or spinel phase in the coating layer will be lower, leading to deterioration in plasma resistance.

[0100] Furthermore, when the content of YAG or spinel is below the lower limit of the aforementioned range, it is difficult to expect plasma resistance properties comparable to or similar to those of bulk YAG or yttrium oxide sintered bodies. Additionally, when the content of YAG or spinel exceeds 50% by weight, the volume resistivity and thermal conductivity may decrease, making it difficult to apply to electrostatic chucks or ceramic heaters. Moreover, the bonding strength with the ceramic substrate may also weaken.

[0101] Here, the sintering performed when forming the coating layer is a method of forming bulk material from powder using heat, pressure and / or energy, which can be accomplished by various sintering methods commonly used for sintering ceramic materials, and preferably by hot pressing.

[0102] In particular, when using aluminum nitride-yttrium oxide core / shell materials or aluminum oxide-yttrium oxide core / shell materials to form a coating layer, the reaction sintering between aluminum nitride-yttrium oxide or aluminum oxide-yttrium oxide cannot proceed smoothly in conventional pressureless sintering, which may result in the problem of almost no YAG phase formation. Therefore, hot pressing sintering process is preferred for preparation.

[0103] In one of the above embodiments, a coating layer with excellent plasma resistance, high volume resistivity, and high thermal conductivity is described, which is obtained by sintering a core / shell structure material to form a continuous YAG or spinel phase along the particle boundaries of the aluminum nitride or aluminum oxide phase constituting the core.

[0104] However, the present invention is not limited thereto, and in addition to YAG or spinel, at the particle boundaries of the aluminum nitride or aluminum oxide phase, at least one of the following may be provided: yttrium oxide-alumina-silica (YAS or yttrium aluminosilicate, Y2O3-Al2O3-SiO2), carbon (C), boron nitride (BN), silicon carbide (SiC), scandium (Sc) and niobium (Nb).

[0105] These additional components, along with the YAG or spinel phase, are uniformly dispersed and distributed within the coating layer along the particle boundaries of the aluminum nitride or alumina phase, thereby further improving the thermal conductivity, mechanical strength, hardness, and density of the coating layer. As a result, the overall physical properties of the ceramic substrate prepared using this coating layer are further enhanced.

[0106] In addition, additional components can be included in the process of forming the shell of the core / shell structure material, or can be added to the coating layer by mixing and sintering together with the core / shell structure material during the process of preparing the coating layer by sintering the core / shell structure material.

[0107] Therefore, the additional components, together with the shell components, form a continuous and uniform dispersion along the particle boundaries of the aluminum nitride and aluminum oxide phases that constitute the core, thereby enhancing the overall physical properties of the coating, such as thermal conductivity, mechanical strength and hardness, and density.

[0108] As described above, the present invention provides a coating layer that uses a core / shell structured material to form a continuous YAG or spinel phase along the particle boundaries of the alumina or aluminum nitride phase, thereby exhibiting excellent plasma resistance and durability.

[0109] In addition, the core / shell structure material and the coatings used thereon have high strength / hardness and density, which can minimize corrosion and erosion properties as well as particulate and / or metal contamination in the extreme environments of semiconductor processing.

[0110] In particular, the coating layer possesses the high volume resistivity and thermal conductivity required for the fabrication of electrostatic chucks or ceramic heaters, along with the aforementioned excellent plasma resistance and durability, and also exhibits physical properties similar to those of the ceramic plate layer. This results in the fabrication of a high-performance ceramic substrate that can reduce peeling and particle generation on the coating layer by ensuring excellent bonding strength when formed on the ceramic plate layer.

[0111] Furthermore, the coating utilizes core / shell structured ceramic materials, thereby reducing the content of expensive yttrium oxide, thus offering the advantage of lower manufacturing costs compared to conventional methods.

[0112] Here, a method for preparing coatings using core / shell structured materials will be described.

[0113] First, the method for preparing core / shell structured materials includes the following steps: mixing and reacting an aluminum compound with a plasma-resistant metal or ceramic compound, and may also include ultrasonic treatment during the mixing and reaction process.

[0114] Ultrasonic treatment aims to improve the dispersibility of mixtures, reactants, or reaction products, thereby promoting uniform particle distribution. There are no specific restrictions on the timing or frequency of ultrasonic treatment, such as after the addition of all raw materials or after the addition of only one raw material.

[0115] Binding agents such as urea (CO(NH2)2) can be added separately before, after, or during the addition of raw materials. Stirring can also be performed while adding raw materials. Furthermore, the reaction between raw materials can be carried out in the presence of deionized water (triple-distilled water).

[0116] For example, an aluminum compound can be supplied to a reactor at approximately 90°C in the presence of deionized water (triple-distilled water), stirred, and then sonicated at approximately 60°C for approximately 15 minutes. In this case, an additional stirring step of approximately 15 minutes can be performed to reheat to approximately 90°C. Next, after adding a binder to the reactor, sonication is performed at approximately 60°C for approximately 15 minutes after approximately 2 minutes, and a stirring step of approximately 15 minutes can be performed to reheat to approximately 90°C. Furthermore, one or more of the above steps can be repeated 2 to 6 times, preferably 3 to 5 times. Subsequently, another raw material (plasma-resistant metal or ceramic compound) is added to the reactor, and then sonication is performed at approximately 60°C for approximately 15 minutes after approximately 2 minutes, and a stirring step of approximately 15 minutes can be performed to reheat to approximately 90°C. Finally, core / shell structured materials can be synthesized by performing additional stirring steps for several minutes to several hours.

[0117] Simultaneously, a washing process using deionized water (triple-distilled water) and alcohols can be performed to remove unreacted residual binders and other impurities, and this washing process can be repeated multiple times.

[0118] Furthermore, by drying the synthesized core / shell structured material at a temperature of about 70 to 90°C for 1 to 48 hours, preferably 12 to 36 hours, a core / shell structured material with higher purity can be obtained.

[0119] Finally, the core / shell structured material prepared as described above can be pulverized using a ball mill or sintered by hot pressing to prepare a coating layer with a structure in which the shell particle phase forms a continuous phase along the particle boundary of the core particle phase.

[0120] Here, a brief description will be given of the yttrium-aluminum garnet (Y3Al5O4) contained in the shell. 12 Conventional methods for preparing YAG include sol-gel combustion, hydrothermal synthesis, and coprecipitation.

[0121] First, the sol-gel combustion method is a way to prepare "high-purity powders with uniform composition and fine particles." However, since most of the nanoparticles produced have an amorphous phase, a heat treatment process is required to crystallize them. Typically, temperatures above 800°C require a certain amount of time to form a crystalline phase, which increases the particle size and manufacturing costs.

[0122] Hydrothermal synthesis can prepare "crystalline powders and powders with spherical shapes and small particle sizes" at relatively low temperatures (200°C, 168 hours). However, the synthesis process involves interactions between the powder and water, making it difficult to synthesize composite oxides with a uniform composition. Furthermore, the process requires a significant amount of time.

[0123] Coprecipitation is a method for simultaneously precipitating various different ions from aqueous or non-aqueous solutions. In the preparation of YAG, the powdered raw materials exist in their individual ionic forms, thus enabling uniform dispersion. However, the precipitation process may be incomplete due to insufficient coprecipitation or dispersion of impurities.

[0124] Therefore, in order to synthesize YAG core / shell structures, high-purity particles should be prepared, which requires a highly uniform composition.

[0125] Therefore, the applicant applied a method based on coprecipitation but with added ultrasonic treatment to improve the dispersibility of mixtures, reactants or reaction products, thereby inducing a uniform particle distribution.

[0126] Meanwhile, by forming a reaction layer at the interface between the ceramic plate and the coating layer through reaction sintering, the stress caused by the differences in physical properties such as microstructure and coefficient of thermal expansion between the ceramic plate and the coating layer is reduced, thereby further stabilizing the coating layer interface.

[0127] Typically, yttrium oxide or Y-type compounds are coated onto AlN or Al2O3 ceramic plates. However, after coating, stress caused by differences in physical properties at the interface, such as microstructure and coefficient of thermal expansion, leads to delamination. This delamination phenomenon is particularly pronounced in high-temperature environments above 500°C.

[0128] However, the applicant used a hot-pressing sintering process (formed by sintering core / shell structure materials) to form a coating layer on a ceramic plate containing AlN and Al2O3. Specifically, by making the core component within the coating layer similar to or identical to the components constituting the ceramic plate layer, differences in physical properties such as the coefficient of thermal expansion were minimized, enabling dense bonding. As a result, compared to conventional methods, the degree of coating peeling and particle formation was significantly reduced, achieving improved densification, hardness, and density.

[0129] Furthermore, as described above, the coating layer has a structure in which the shell-particle phase forms a continuous phase along the particle boundary of the core-particle phase. In this case, a key feature of the present invention is, for example, yttrium-aluminum garnet (Y3Al5O4). 12 Materials that form a continuous phase, such as YAG, exhibit their own plasma resistance properties independently of the influence of the core composition.

[0130] Furthermore, by using the above-mentioned sintering method to form the coating layer, a reaction layer can be generated at the interface between the ceramic plate layer and the coating layer through reaction sintering.

[0131] This reactive layer is produced by reactive sintering using high temperature and high pressure energy. It stabilizes the microstructure of the interface between the ceramic plate and the coating layer and alleviates the stress caused by the differences in physical properties such as the coefficient of thermal expansion between the different materials constituting the ceramic plate and the coating layer. As a result, the coating layer remains stable and does not peel off even in high temperature environments above 500°C.

[0132] For example, when a continuous phase of yttrium-aluminum garnet (YAG, Y3Al5O) is formed on a ceramic plate... 12 When a coating layer of yttrium oxide (Y2O3) is applied, yttrium-aluminum garnet (YAG, Y3Al5O3) can be further formed at the interface between the ceramic plate and the coating layer through the reaction sintering of the yttrium component contained in the coating layer with the aluminum or alumina component present in the ceramic plate. 12 ) Reaction layer.

[0133] As another example, when a "coating layer with a continuous phase of magnesium oxide" is formed on a ceramic plate, a magnesium aluminate spinel (MgAl2O4) reaction layer can be further formed at the interface between the ceramic plate and the coating layer by reacting and sintering the magnesium component contained in the coating layer with the aluminum or alumina component present in the ceramic plate layer.

[0134] Next, the method for preparing the ceramic base of the present invention will be described.

[0135] The method for preparing a ceramic substrate includes the following steps: 1) preparing a ceramic plate layer; and 2) forming a coating layer on the ceramic plate layer.

[0136] In addition, the ceramic plate layer can be prepared by the following steps: a) mixing alumina (Al2O3), aluminum nitride (AlN), alcohol compounds and binder; b) drying the mixture to prepare a powder with the alcohol compound component removed; c) compressing and molding the dried powder to prepare a preform processed into a predetermined shape; d) degreasing the obtained preform to remove the binder component; and e) sintering and polishing the degreased preform.

[0137] In addition, if necessary, a dopant may be added and mixed in step a), and examples of such dopant may include at least one of magnesium oxide (MgO), yttrium oxide (Y2O3), graphene, and rare earth composite oxides.

[0138] The alcohol compounds used in step a) are used to suitably mix the raw materials and may include, for example, alcohol compounds having 1 to 5 carbon atoms, specifically ethanol, methanol, and isopropanol. Similarly, the binders used in step a) are intended to enhance the bonding strength of the raw materials, and examples may include polyvinyl alcohol (PVA) and polyvinyl butyral (PVB).

[0139] Step b) is to dry the powder mixture from step a) to remove the alcohol components, and the drying can be carried out using methods known in the art, such as spray drying or vacuum drying, and the drying time can vary depending on the physical properties of the desired ceramic substrate.

[0140] Step c) involves compressing and molding the dried powder to prepare a preform processed into a predetermined shape. Compression molding is the first molding (i.e., first molding) process used to control the dried powder in step b) to the desired size and shape, and examples of this may include press molding. In this case, cold isostatic pressing (CIP) may be performed additionally if necessary to prepare a product with more precise specifications. Press molding is preferably performed at room temperature and in a normal atmosphere, but is not limited thereto. The molding atmosphere should not affect the molding of the mixture. Furthermore, after the molding process in step c), the preform may be prepared by processing using green finishing methods (also known as "green finishing" performed before sintering).

[0141] Step d) is a step of degreasing the obtained preform to remove the adhesive component. The degreasing process removes adhesive and oily contaminants and can be carried out at a temperature of 350°C to 600°C for up to 60 hours.

[0142] Step e) involves sintering (second forming) and polishing the degreased preform to prepare a ceramic substrate. Sintering is a second forming (i.e., second molding) process used to further improve the volume resistivity of the ceramic substrate, and is preferably performed using a hot pressing sintering process. Furthermore, when the degreased preform is sintered at temperatures above 1,650°C, alumina and aluminum nitride react to form the AlON phase, which leads to a decrease in thermal conductivity. Therefore, the sintering in step e) should be performed at a temperature below 1,650°C, preferably at a temperature above 1,300°C and below 1,650°C.

[0143] Next, in order to form a coating layer on the prepared ceramic plate, the following steps are required: a) mixing and reacting an aluminum compound with a plasma-resistant metal or ceramic compound to prepare a core / shell structure material; b) dispersing the prepared core / shell structure material in a solvent to prepare a coating solution; c) spraying the prepared coating solution onto the ceramic plate; and d) drying the sprayed coating solution and then hot-pressing it to form a coating layer.

[0144] Step a) may also include an ultrasonic treatment step during mixing and reaction. Furthermore, the details of the raw materials in step a) and the specific methods for preparing the core / shell structured material are as described above.

[0145] The solvent in step b) can be a conventional organic solvent, such as an alcohol compound.

[0146] There are no particular restrictions on the spraying in step c), as any known spraying method for forming a coating can be applied, such as air spraying.

[0147] The drying in step d) can be carried out for 10 minutes at room temperature, for example, but is not limited to this, and can vary depending on the amount of coating or other factors.

[0148] The hot pressing in step d) can be carried out for 1 to 24 hours, for example, at a temperature of 1,300 to 1,650°C and a pressure of 100 to 200 bar, but is not limited thereto, and can be appropriately modified depending on the circumstances.

[0149] Additionally, after preparing the core / shell structure material in step a) and before hot pressing in step d), a process of pulverizing the core / shell structure material using a planetary ball mill for 2 hours can be added.

[0150] When a coating layer (formed by sintering the core / shell structure material) is provided on a ceramic plate containing AlN and Al2O3 using the above process, the core and ceramic plate components are in partial direct contact to form a sintered structure, thereby minimizing differences in physical properties such as the coefficient of thermal expansion and thus achieving a dense bond.

[0151] Compared to conventional coatings, this significantly reduces coating peeling and particle generation, resulting in improved densification, hardness, and density.

[0152] Furthermore, the shell of the continuous phase formed along the particle boundaries of the core-particle phase exhibits its own plasma resistance properties independently of the influence exerted by the core component. The mechanism by which each component of the coating (core and shell) plays its own independent role is a unique feature of this invention that has not been previously observed.

[0153] The ceramic substrate of the present invention, prepared using the above-described method, can be applied to various devices or components used in semiconductor manufacturing processes, and is preferably used as a material for heaters or electrostatic chucks used in semiconductor manufacturing processes. However, its application is not particularly limited, as it can also be used in fields utilizing ceramic materials in high-temperature plasma environments.

[0154] The present invention will now be described in more detail through specific embodiments. These embodiments are intended to illustrate the invention and not to limit it.

[0155] [Preparation Examples 1-7] Preparation and Physical Property Evaluation of Ceramic Plates

[0156] To determine the optimal mixing ratio of alumina and aluminum nitride, the raw materials were mixed according to the ratios shown in Table 1 below. Additionally, trace amounts of ethanol and polyvinyl butyral (binder) were mixed and dried. Next, the dried mixture was pressed and processed to prepare a preform. Subsequently, the preform was degreased at 500°C for 30 hours, and then sintered and polished in a high-temperature pressure sintering furnace (250 bar pressure, 1,630°C) to prepare a ceramic plate.

[0157] The volume resistivity and thermal conductivity of the prepared ceramic plates were then measured. Specifically, a voltage of 500 V / mm was applied to each prepared ceramic plate, and the current was measured after 1 minute (under vacuum and at room temperature) to calculate the volume resistivity. Additionally, samples were prepared according to ASTM C0408-88R11 using a NETZSCH LFA 467 instrument, and the thermal conductivity was calculated at room temperature. The results are shown in Table 2 below.

[0158] [Table 1]

[0159] [Table 2]

[0160] Al2O3 and AlN are measured in weight percent.

[0161] As shown in Tables 1 and 2 above, the ratio of aluminum nitride phases also varies with the ratio of aluminum nitride added, resulting in different volume resistivity at high temperature and thermal conductivity at room temperature.

[0162] More specifically, it was confirmed that the physical properties varied with the aluminum nitride addition ratio, and XRD results showed that no AlON phase was formed in any of the final products of Preparation Examples 1 to 7. Preparation Examples 3 to 5 exhibited satisfactory volume resistivity and thermal conductivity, and Preparation Example 5, which mixed alumina and aluminum nitride at a weight ratio of 75:25, showed the best overall performance.

[0163] This indicates that when the aluminum nitride content is too low, the Al2O3 phase forms as the main phase, resulting in almost no improvement in thermal conductivity. However, when the aluminum nitride content is too high, the proportion of the AlN phase increases, which improves thermal conductivity but reduces volume resistivity and hardness.

[0164] [Preparation Examples 5-1 to 5-5] Evaluation of the physical properties of ceramic plates based on sintering temperature

[0165] Based on the best overall results obtained in Preparation Example 5, which mixed alumina and aluminum nitride in a weight ratio of 75:25, as shown in Table 3 below, ceramic plates were prepared by simply setting different sintering temperatures (the preparation method was the same as in Example 1, except for the composition and sintering temperature).

[0166] The volume resistivity and thermal conductivity of the prepared ceramic plates were then measured. Specifically, a voltage of 500 V / mm was applied to the ceramic plate, and the current was measured after 1 minute (under vacuum and at room temperature) to calculate the volume resistivity. Additionally, samples were prepared using a NETZSCH LFA 467 apparatus according to ASTM C0408-88R11, and the thermal conductivity was then measured at room temperature to calculate the thermal conductivity. The results are shown in Table 4 below.

[0167] [Table 3]

[0168] [Table 4]

[0169] Al2O3, AlN, and AlON (unit: weight %)

[0170] Alumina reacts with aluminum nitride at temperatures above a predetermined temperature to form the AlON phase. Although the AlON phase has high electrical insulation properties, its low thermal conductivity significantly affects its physical properties depending on whether the AlON phase is formed. Figure 3 This is an XRD pattern showing the physical properties of the ceramic substrate according to the sintering temperature, and Figure 4 This is a graph showing the correlation between alumina content and sintering temperature. (Refer to...) Figure 3 and Figure 4 At a sintering temperature of 1,500°C, insufficiency occurred, making it impossible to measure volume resistivity, and resulting in very low thermal conductivity and density. XRD analysis showed that an AlON phase was generated at sintering temperatures above 1,650°C. With increasing AlON content, volume resistivity increased, but thermal conductivity decreased rapidly. Therefore, it can be seen that sintering in this invention is preferably performed at temperatures below 1,650°C.

[0171] [Preparation Examples 8-19, Comparative Preparation Examples 8-19] Preparation of Ceramic Plates

[0172] Based on the experimental results of Preparation Examples 5-3 above, the raw materials were mixed according to the composition in Table 5 below. Additionally, trace amounts of ethanol and polyvinyl butyral (binder) were mixed and dried. Next, the dried mixture was pressed and processed to prepare a preform. Subsequently, the preform was degreased at 500°C for 30 hours, and then sintered in a high-temperature pressure sintering furnace (250 bar pressure, 1,630°C) and polished to prepare a ceramic plate.

[0173] [Table 5] Dopant unit: weight % [Experimental Example 1] Evaluation of Volume Resistivity and Thermal Conductivity of Ceramic Plates A voltage of 500 V / mm was applied to each ceramic plate prepared by Preparation Examples 8 to 19 and Comparative Preparation Examples 8 to 19, and the current was measured after 1 minute (measured under vacuum and at room temperature) to calculate the volume resistivity. The results are shown in Table 6 below.

[0174] In addition, samples were prepared from the ceramic plates described in Preparation Examples 8 to 19 and Comparative Preparation Examples 8 to 19 according to ASTM C0408-88R11 using a NETZSCH LFA 467 apparatus, and the thermal conductivity was then measured at room temperature to calculate the thermal conductivity. The results are also shown in Table 6 below.

[0175] Furthermore, the density values ​​of each ceramic plate prepared by the above preparation examples 8 to 19 and comparative preparation examples 8 to 19 were calculated using the Archimedes method, and the results are also shown in Table 6 below.

[0176] [Table 6]

[0177] As shown in Table 6 above, as the measurement results of the volume resistivity and thermal conductivity of each ceramic plate prepared in Preparation Examples 8 to 19 and Comparative Preparation Examples 8 to 19, all ceramic plates in Preparation Examples 8 to 19 meet the volume resistivity (1.0E+10Ω·cm to 1.0E+13Ω·cm) required for next-generation semiconductor manufacturing processes at 500°C.

[0178] Furthermore, regarding thermal conductivity, by comparing preparation examples 8 to 10 with comparative preparation examples 8 to 10, preparation examples 11 to 13 with comparative preparation examples 11 to 13, preparation examples 14 to 16 with comparative preparation examples 14 to 16, and preparation examples 17 to 19 with comparative preparation examples 17 to 19, it can be confirmed that preparation examples 8 to 19, with each dopant amounting to 0.05 to 0.5% by weight, exhibit superior performance compared to or even better than that of comparative preparation examples 8 to 19, where the amount of any one dopant exceeds 0.05 to 0.5% by weight.

[0179] Meanwhile, when GNP (graphene nanoparticles) is added as a dopant in addition to MgO, the effect is minimal when the amount of GNP is less than 0.05 wt%, while the thermal conductivity can be improved when the amount of GNP is between 0.05 and 0.5 wt%. Furthermore, when the amount of GNP exceeds 0.5 wt%, the volume resistivity, density, and hardness tend to decrease rapidly.

[0180] Furthermore, even when nano-sized yttrium oxide (Y₂O₃) is added as a dopant in addition to MgO and GNP, sinterability is enhanced at 0.05 to 0.5 wt%, resulting in increased volume resistivity and thermal conductivity. However, when the amount of yttrium oxide exceeds 0.5 wt%, a large amount of second phases such as YAP, YAM, and YAG are formed due to the reaction with alumina, leading to a decrease in thermal conductivity.

[0181] Furthermore, even when rare earth composite oxides were added as dopants in addition to MgO, GNP, and nano Y2O3, it was confirmed that using 0.05 to 0.5 wt% not only increased volume resistivity and thermal conductivity, but also increased density and hardness. On the other hand, when the amount of rare earth composite oxides exceeded 0.5 wt%, both volume resistivity and thermal conductivity tended to decrease rapidly.

[0182] Furthermore, Preparation Example 9 was compared with Comparative Preparation Example 9. Preparation Example 9 used 0.5 wt% MgO, while Comparative Preparation Example 9 used 1 wt% MgO. Therefore, although the difference in content was not significant, the thermal conductivity decreased rapidly as the MgO content increased from 0.5 wt% to 1 wt%. This is because when the MgO content exceeds 0.5 wt%, more than 0.6 wt% of the MgAl₂O₄ or MgAlON phase is generated in the final product, increasing its fraction. These results can be confirmed in Table 7 below.

[0183] [Table 7] Dopant unit: weight % [Example 1] Preparation of ceramic substrate First, alumina was supplied to a reactor at 90°C in the presence of deionized water (triple-distilled water). After 2 minutes, it was sonicated at 60°C for 15 minutes, followed by stirring for 15 minutes until the temperature was raised back to 90°C. Next, urea (CO(NH2)2) was added to the reactor as a binder. After 2 minutes, it was sonicated at 60°C for 15 minutes, followed by stirring for 15 minutes until the temperature was raised back to 90°C. This process was repeated a total of 4 times. Subsequently, another feedstock, yttrium oxide, was added to the reactor. After 2 minutes, it was sonicated at 60°C for 15 minutes, followed by stirring for 15 minutes until the temperature was raised back to 90°C. A stirring process of approximately 3 hours was then performed to synthesize the core / shell structured material. To remove unreacted residual binder and other impurities, four washing processes were performed using deionized water and ethanol. To improve the purity of the synthesized core / shell structured material, it was dried in an oven at 80°C for 24 hours.

[0184] Simultaneously, alumina and yttrium oxide, used for synthesizing core / shell structure materials, are added to the reactor in a weight ratio of 70:30, and the amount of binder is 800 parts by weight based on 100 parts by weight of added yttrium oxide (i.e., when binder is added once, 200 parts by weight are used based on 100 parts by weight of added yttrium oxide).

[0185] Subsequently, the core / shell structure material prepared as described above was pulverized for 2 hours using a planetary ball mill and dispersed in ethanol to prepare a coating solution. The solution was then sprayed onto the ceramic plate prepared in Preparation Example 18 using an air sprayer.

[0186] Finally, the ceramic plate coated with the coating solution was hot-pressed and sintered at 1,570°C for 4 hours (the composition of the coating after sintering is 75.81 wt% alumina / 24.19 wt% YAG) to prepare a ceramic substrate with a coating on the ceramic plate, wherein the shell (YAG) particle phase forms a continuous phase along the particle boundary of the core (alumina) particle phase.

[0187] [Comparative Example 1] Preparation of Conventional Ceramic Substrates

[0188] According to conventional methods, a ceramic substrate is prepared by molding and sintering alumina (starting composition: 100 wt% alumina, sintered composition: 100 wt% alumina).

[0189] [Comparative Example 2] Preparation of Conventional Ceramic Substrates

[0190] According to conventional methods, by analyzing yttrium-aluminum garnet (Y3Al5O) 12 The ceramic substrate was prepared by molding and sintering YAG (starting composition: 100 wt% YAG, sintered composition: 100 wt% YAG).

[0191] [Comparative Example 3] Preparation of Conventional Ceramic Substrates

[0192] According to conventional methods, a ceramic substrate (starting composition: 100 wt% yttrium oxide, sintered composition: 100 wt% yttrium oxide) is prepared by molding and sintering yttrium oxide.

[0193] [Comparative Example 4] Preparation of Conventional Ceramic Substrates

[0194] A ceramic substrate containing YAG and alumina as independent phases was prepared by mechanically mixing 60 wt% alumina and 40 wt% yttrium oxide using conventional methods and then sintering the mixture (starting composition: 60 wt% alumina / 40 wt% yttrium oxide, sintered composition: 30.2 wt% alumina / 69.8 wt% YAG).

[0195] [Comparative Example 5] Preparation of Conventional Ceramic Substrates

[0196] A ceramic substrate containing YAG and alumina as independent phases was prepared by mechanically mixing 70 wt% alumina and 30 wt% yttrium oxide using conventional methods and then sintering the mixture (starting composition: 70 wt% alumina / 30 wt% yttrium oxide, sintered composition: 49.06 wt% alumina / 50.94 wt% YAG).

[0197] Figure 5 This is an XRD pattern of the coating layer of a ceramic substrate according to one embodiment of the present invention (specifically, corresponding to the ceramic substrate prepared in Example 1), and Figure 6 The image shows the XRD pattern of a conventional ceramic substrate (specifically, the ceramic substrate prepared in Comparative Example 5). The results calculated using the peak value at a specific 2θ angle also confirm that the composition is identical to the composition after sintering.

[0198] [Comparative Example 6] Preparation of Conventional Ceramic Substrates

[0199] According to conventional methods, a ceramic substrate containing YAG and alumina as independent phases was prepared by mechanically mixing 80 wt% alumina and 20 wt% yttrium oxide and then sintering the mixture (starting composition: 80 wt% alumina / 20 wt% yttrium oxide, sintered composition: 64.91 wt% alumina / 35.09 wt% YAG).

[0200] [Comparative Example 7] Preparation of Conventional Ceramic Substrates

[0201] According to conventional methods, a ceramic substrate containing YAG and alumina as independent phases was prepared by mechanically mixing 90 wt% alumina and 10 wt% yttrium oxide and then sintering (starting composition: 90 wt% alumina / 10 wt% yttrium oxide, sintered composition: 82.24 wt% alumina / 17.76 wt% YAG).

[0202] [Experimental Example 2] Structural Evaluation of Ceramic Base

[0203] As shown in Table 8 below, the ceramic substrate prepared in Example 1 and Comparative Examples 1 to 7 has a structure in which the YAG phase forms a continuous phase along the particle boundaries of the alumina particle phase and is densely bonded to the ceramic plate. On the other hand, it was confirmed that Comparative Examples 1 to 3 consist of only a single phase, and Comparative Examples 4 to 7 consist of two phases, but they are independent of each other.

[0204] [Table 8]

[0205] Figure 7 This is an image of the coating layer of a ceramic substrate according to an embodiment of the present invention, observed using a transmission electron microscope (TEM). Figure 7 A, Figure 7 B), Figure 8 This is an image of a cross-section of a ceramic substrate according to one embodiment of the present invention, as observed using a scanning electron microscope (SEM). Figure 9 This is a cross-sectional image of the coating layer of a ceramic substrate according to an embodiment of the present invention, observed using a scanning electron microscope (SEM). Figure 10 This is an image of a cross-section of a conventional ceramic substrate as observed using a scanning electron microscope.

[0206] More specifically, observations using transmission electron microscopy of the ceramic substrate prepared in Example 1 showed that, as Figure 7 As shown in Figures A and 7B, there is a significant difference in light and dark areas between the interior and exterior of the coating. Furthermore, component analysis confirms that alumina is located on the interior and YAG on the exterior.

[0207] Next, the scanning electron microscope (SEM) observation results of the cross-sections of the ceramic substrate and coating prepared in Example 1 are shown. Figure 8 B is Figure 8 (A magnified view of a portion of the "core-shell coating" in section A) confirms that... Figure 8 As shown in B and 9, the YAG particle phase forms a continuous phase along the particle boundaries of the alumina particle phase.

[0208] On the other hand, in the case of the ceramic substrate prepared in Comparative Example 5, such as Figure 10As shown, it was confirmed that although alumina and YAG particulate phases were identified, they consist of independent phases.

[0209] (For the remaining comparative examples 4, 6, and 7, it was confirmed that the sintered body contained alumina and YAG particle phases, and that the alumina and YAG particle phases were composed of independent phases.)

[0210] [Experimental Example 3] Evaluation of the physical properties of ceramic base

[0211] A voltage of 500 V / mm was applied to each of the ceramic substrates prepared in Example 1 and Comparative Examples 1 to 7 above. After 1 minute, the current was measured (in a vacuum atmosphere and at room temperature) to calculate the volume resistivity, and the results are shown in Table 9 below.

[0212] Furthermore, for each ceramic substrate prepared in Example 1 and Comparative Examples 1 to 7 above, specimens were prepared according to ASTM C0408-88R11 using a NETZSCH LFA 467 apparatus, and then the thermal conductivity was measured at room temperature. The results are also shown in Table 9 below.

[0213] In addition, the density values ​​of each ceramic substrate prepared in Example 1 and Comparative Examples 1 to 7 were calculated using the Archimedes method, and the results are shown in Table 9 below.

[0214] Furthermore, the etching rate (plasma resistance test) of each ceramic substrate prepared in Example 1 and Comparative Examples 1 to 7 was measured, and the results are shown in Table 9 below. The etching rate was measured using a DektakXT Stylus Profiler (manufacturer: Bruker).

[0215] In addition, the hardness of each ceramic substrate prepared in Example 1 and Comparative Examples 1 to 7 was measured, and the results are shown in Table 9 below. The hardness was measured using a micro Vickers hardness tester (HM-210A, Mitutoyo), and the microhardness scale was set to HV0.5.

[0216] [Table 9]

[0217] As shown in Table 9 above, the volume resistivity and thermal conductivity of the ceramic substrates prepared in Examples 1 and Comparative Examples 1 to 7 meet the required levels for both electrostatic chucks and ceramic heaters in terms of volume resistivity and thermal conductivity.

[0218] Meanwhile, the ceramic substrate of the above embodiment 1 exhibits hardness and density sufficient to prevent or minimize corrosion and erosion properties, as well as particulate and / or metal contamination, in the extreme environment of semiconductor processing.

[0219] Most importantly, the ceramic substrate of Example 1 exhibits an etching rate of only 2.33 nm / min, which minimizes the amount of etching byproducts and particulate contamination even in harsh plasma environments such as high temperature and high energy plasma. Therefore, it is confirmed that the ceramic substrate of Example 1 can minimize yield loss in semiconductor devices.

[0220] Meanwhile, the ceramic substrate of Comparative Example 3 also exhibited an etching rate of only 2.11 nm / min, but in particular, the other physical properties of the ceramic substrate (i.e., volume resistivity, thermal conductivity and hardness) were very low, making it unsuitable as a ceramic substrate for semiconductor manufacturing devices.

[0221] Furthermore, it can be seen that by mixing and sintering alumina and yttrium oxide to prepare ceramic substrates containing the YAG phase, simple mechanical mixing and sintering alone cannot achieve the superior plasma resistance and other physical properties beyond the standard.

[0222] Based on the above, the ceramic base of the present invention meets the requirements of electrostatic chucks and ceramic heaters in all major physical properties (volume resistivity, thermal conductivity, density, etching rate, and hardness).

[0223] [Experimental Example 4] Coating Peeling Test of Ceramic Substrate

[0224] To observe coating peeling at high temperatures, the ceramic substrate prepared in Example 1 was heat-treated at 500°C (actual operating temperature), and the cross-section of the bonding surface between the ceramic plate and the core / shell coating was observed using a scanning electron microscope (SEM). Figure 11 and 12 The text shows ( ) Figure 11 800x magnification Figure 12 (Magnification: 2,000x)

[0225] As described above, the ceramic substrate prepared in Example 1 was heat-treated at 500°C, and the cross-section of the surface where the ceramic plate layer and the core / shell coating layer were bonded was observed using a scanning electron microscope. Figure 11 and 12 As shown, even at high temperatures, the bonding surface between the ceramic plate and the core / shell coating maintains a dense and stable bonding structure, thus confirming that the bonding strength between the ceramic plate and the core / shell coating remains unchanged even at high temperatures.

[0226] Therefore, it can be seen that the ceramic substrate of the present invention can improve plasma resistance and particle resistance without coating peeling even in high-temperature environments such as 500°C used in actual semiconductor manufacturing processes.

[0227] As described above, the invention has been described in detail with reference to specific components, limited embodiments, and accompanying drawings. However, these details are provided only to aid in a more comprehensive understanding of the invention. The invention is not limited to the described embodiments, and those skilled in the art can make various modifications and variations without departing from the essential characteristics of the invention. Therefore, the spirit of the invention should not be limited to the described embodiments, and all technical ideas equivalent to or related to the following claims should be interpreted as being included within the scope of the invention.

Claims

1. A ceramic base comprising: Ceramic slabs; and A coating layer located on the ceramic plate layer and formed by sintering the core / shell structure material. in, The ceramic plate layer comprises alumina (Al2O3) and aluminum nitride (AlN) but does not contain a second phase of aluminum oxynitride (AlON). The coating layer has a structure in which the granular phase constituting the shell forms a continuous phase along the particle boundaries of the core granular phase.

2. The ceramic base as described in claim 1, wherein, The core particle phase comprises at least one of aluminum nitride and aluminum oxide.

3. The ceramic base as described in claim 1, wherein, The continuous phase comprises a plasma-resistant metallic or ceramic compound selected from the group consisting of: yttrium aluminum garnet (Y3Al5O4). 12 The group consists of yttrium-aluminum oxides, yttrium oxides, magnesium oxides, yttrium oxide-aluminum-silica (Y2O3-Al2O3-SiO2, YAS), magnesium silicate (Mg2SiO4), and mullite (3Al2O3·2SiO2), which are composed of yttrium-aluminum perovskite (YAlO3, YAP) and yttrium-aluminum monoclinic crystals (Y4Al2O9, YAM).

4. The ceramic base as described in claim 2, wherein, The continuous phase is selected from yttrium-aluminum garnet (YAG, Y3Al5O). 12 The group consists of yttrium oxide (Y2O3) and magnesium oxide.

5. The ceramic base as described in claim 4, wherein, The coating layer has yttrium-aluminum garnet (Y3Al5O) 12 The structure of a continuous phase is formed along the particle boundaries of the aluminum nitride or aluminum oxide phase contained in the core particle phase (YAG) or magnesium aluminate spinel (MgAl2O4).

6. The ceramic base as described in claim 5, wherein, The content of aluminum nitride or aluminum oxide in the core particle phase is 50% to 85% by weight relative to the total weight of the coating layer, and the content of yttrium aluminum garnet forming the continuous phase is 15% to 50% by weight.

7. The ceramic base as described in claim 5, wherein, The content of aluminum nitride or aluminum oxide in the core particle phase is 50% to 90% by weight relative to the total weight of the coating layer, and the content of magnesium aluminate spinel forming the continuous phase is 10% to 50% by weight.

8. The ceramic base as described in claim 5, wherein, At the particle boundaries between the aluminum nitride or aluminum oxide phases contained in the core particle phase, at least one element selected from the group consisting of yttrium oxide-aluminum oxide-silicon dioxide (Y2O3-Al2O3-SiO2, YAS), carbon, boron nitride, silicon carbide, scandium, and niobium is also provided.

9. The ceramic base as described in claim 1, wherein, The coating layer is formed on the ceramic plate by hot pressing.

10. The ceramic base as claimed in claim 4, wherein, At the particle boundary between the ceramic plate layer and the coating layer, a reaction layer formed by reaction sintering is also formed.

11. The ceramic base as claimed in claim 10, wherein, The continuous phase is yttrium aluminum garnet (YAG, Y3Al5O). 12 Yttrium oxide (Y₂O₃) or yttrium oxide (Y₂O₃) is also formed at the particle boundaries between the ceramic plate layer and the coating layer. 12 ) Reaction layer.

12. The ceramic base as claimed in claim 10, wherein, The continuous phase is magnesium oxide, and a magnesium aluminate spinel (MgAl2O4) reaction layer is formed at the particle boundary between the ceramic plate and the coating layer.

13. The ceramic base as claimed in claim 1, wherein, The ceramic substrate has a volume resistivity of 1.0E+10 to 1.0E+13 Ω·cm at 500°C and a thermal conductivity of 30 to 60 W / m·K at room temperature.

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