Wafer support body and method for manufacturing wafer support body

Abstract

A wafer support body 10 is provided with: a substrate 16 that comprises a ceramic sintered compact; and a conducting member 18 that encapsulates at least part of the substrate. The substrate 16 contains at least 96% by mass of aluminum oxide, contains 0.47–1.83% by mass of zirconium as the zirconium oxide equivalent, and contains 0–0.48% by mass of yttrium or ytterbium as the yttrium oxide or ytterbium oxide equivalent.

Description

Wafer support and method for manufacturing the wafer support

[0001] The present invention relates to a support for a wafer.

[0002] Conventionally, electrostatic chucks have been used in various semiconductor processes to hold semiconductor wafers and control their temperature. The materials used for electrostatic chucks vary depending on the environment in which they are used and the required properties, but for example, electrostatic chucks made of ceramics mainly composed of alumina are known in terms of plasma resistance, high voltage resistance, high strength, and high dielectric constant (see, for example, Patent Document 1).

[0003] Japanese Patent Publication No. 2008-227420

[0004] In recent years, processes for forming multilayer memory elements such as 3D-NAND on wafers have been developed, but these processes result in greater wafer warping than conventional methods. Therefore, electrostatic chucks that generate sufficient suction force to securely hold warped wafers are necessary. Furthermore, depending on the manufacturing process, high-pressure helium gas may be supplied to the back surface of the wafer to ensure uniform heat distribution across the entire wafer, requiring electrostatic chucks that generate sufficient suction force to prevent the wafer from floating due to the gas.

[0005] This invention has been made in view of these circumstances, and its objective is to provide a new wafer support capable of achieving a desired adsorption force.

[0006] To solve the above problems, a wafer support according to one embodiment of the present invention comprises a substrate made of a ceramic sintered body and a conductive member that is at least partially embedded in the substrate. The substrate contains 96% by mass or more of aluminum oxide, 0.47 to 1.83% by mass of zirconium in terms of zirconium oxide, and 0 to 0.48% by mass of yttrium or ytterbium in terms of yttrium oxide or ytterbium oxide.

[0007] According to this embodiment, the inclusion of zirconium oxide, yttrium oxide, or ytterbium oxide is expected to increase the dielectric constant and improve adsorption capacity.

[0008] The base material may further contain at least one of the following: (1) magnesium in the form of 0.29 to 0.73% by mass, (2) calcium in the form of 0.1 to 0.2% by mass, or (3) silicon in the form of 0 to 0.15% by mass, (3) silicon in the form of silicon oxide. This enables low-temperature sintering and allows for densification while suppressing the grain growth of aluminum oxide.

[0009] The DC dielectric breakdown voltage of the ceramic sintered body may be 100 kV / mm or higher. This allows for an increase in the voltage applied to the conductive member, thereby improving the adsorption force.

[0010] The porosity of the ceramic sintered body obtained by the mercury intrusion method may be 1.0% or less. This makes the ceramic sintered body denser and improves the dielectric breakdown voltage.

[0011] The average particle size D50 of the ceramic sintered body may be 0.7 to 1.5 μm. This allows for the creation of a dense ceramic sintered body.

[0012] The bending strength of the ceramic sintered body may be 600 MPa or higher. This makes it less likely for deformation or breakage to occur even when the dielectric layer is made thinner to improve the adsorption force.

[0013] The relative permittivity of the ceramic sintered body may be 10.0 or higher. This can improve the adsorption force.

[0014] The wafer may further include a metal plate on which the substrate is mounted. The metal plate may have channels formed therein for the flow of a cooling substance. This allows it to be used in vacuum processes where uniform temperature across the entire wafer surface is required, such as dry etching.

[0015] The system may further include a gas supply path for supplying gas between the substrate and the wafer mounted on the substrate. This allows the back side of the wafer to be cooled with gas.

[0016] Another aspect of the present invention is a method for manufacturing a wafer support. This manufacturing method includes the steps of: preparing a raw material powder containing 96% by mass or more of aluminum oxide, 0.47 to 1.83% by mass of zirconium oxide, and 0 to 0.48% by mass of yttrium oxide or ytterbium oxide; arranging the raw material powder in a space of a predetermined shape; and firing the raw material powder by pressurizing the space in the range of 20 to 50 MPa and heating it in the range of 1350 to 1650°C.

[0017] According to this embodiment, a wafer support capable of achieving the desired adsorption force can be manufactured.

[0018] Furthermore, any combination of the above components, and any conversion of the expression of the present invention between methods, apparatus, systems, etc., are also valid embodiments of the present invention. In addition, combinations of the above-mentioned elements as appropriate may also be included within the scope of the invention for which patent protection is sought in this patent application.

[0019] According to the present invention, a desired adsorption force can be achieved.

[0020] This is a schematic cross-sectional view of an electrostatic chuck placed in an etching chamber. This is a perspective view of the electrostatic chuck according to this embodiment. This is a flowchart for explaining the method of manufacturing a wafer support according to this embodiment. Figure 4(a) is a graph showing the relationship between the zirconium oxide content and the dielectric breakdown voltage, Figure 4(b) is a graph showing the relationship between the ytterbium oxide content and the dielectric breakdown voltage, and Figure 4(c) is a graph showing the relationship between the magnesium oxide content and the dielectric breakdown voltage. Figure 5(a) is a graph showing the relationship between the calcium oxide content and the dielectric breakdown voltage, and Figure 5(b) is a graph showing the relationship between the silicon oxide content and the dielectric breakdown voltage.

[0021] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference numerals, and redundant explanations will be omitted as appropriate.

[0022] (Wafer Support) First, the general configuration of the wafer support will be described. The wafer support only needs to be able to support a semiconductor substrate such as a silicon wafer, and may be equipped with an adsorption mechanism and a temperature control mechanism. The wafer support also functions as an electrostatic chuck that generates an adsorption force on the mounted wafer.

[0023] In the following, we will describe an example where the wafer support is an electrostatic chuck equipped with a cooling mechanism. Figure 1 is a schematic cross-sectional view of an electrostatic chuck placed in an etching chamber. Figure 2 is a perspective view of the electrostatic chuck according to this embodiment.

[0024] The etching apparatus 100, including the chamber 12 shown in Figure 1, is a semiconductor manufacturing apparatus for etching the surface of a wafer W, such as silicon, which is a semiconductor substrate, with plasma P. A wafer support 10, which functions as an electrostatic chuck, is used to support the wafer W within the chamber 12. An upper electrode 14 for generating plasma P is also provided inside the chamber 12.

[0025] The wafer support 10 comprises a base material 16 made of a ceramic sintered body and a conductive member 18 in which at least a portion is embedded within the base material 16. The wafer W is mounted on the mounting surface 16a, which is the surface of the base material 16. The conductive member 18 functions as an electrostatic chuck electrode to which a voltage V is applied that generates an adsorption force for fixing the wafer W to the mounting surface 16a. In the wafer support 10 according to this embodiment, the conductive member 18 is embedded in the base material 16, which is a sintered body. Therefore, the conductive member 18 needs to be placed inside the raw material powder during the firing stage, and it is preferable that it be a high-melting-point metal that does not melt at the firing temperature. For example, as the material of the conductive member, high-melting-point metals such as molybdenum, tungsten, and tantalum, or alloys containing two or more of them, are preferred.

[0026] Furthermore, the wafer support 10 has a gas supply passage 20 that extends from the mounting surface 16a exposed to the chamber side, through the interior of the substrate 16, to an external gas supply source (not shown). The gas supply passage 20 is for supplying gas G between the mounting surface 16a and the wafer W to cool the wafer W, which is adsorbed onto the mounting surface 16a, from the back side. This cools the wafer W, which has been heated by plasma or the like, and reduces the unevenness of the temperature distribution of the wafer W. For example, helium, which is an inert gas, is used as the gas G.

[0027] The substrate 16 is mounted on the metal plate 24 via an adhesive layer 22. The metal plate 24 is made of a metallic material such as aluminum or titanium, and has internal channels 26 through which water H, a cooling substance, flows. This allows it to be used in vacuum processes where uniform temperature across the entire wafer surface is required, such as dry etching.

[0028] (Components of the base material) The base material 16 according to this embodiment contains aluminum oxide as its main component. The base material 16 also contains zirconium oxide, yttrium oxide, ytterbium oxide, magnesium oxide, calcium oxide, and silicon oxide as other additive components. The main component of the base material 16 is aluminum oxide (alumina: Al ２ O ３ The reason for using the following is explained below. In this embodiment, the wafer support 10 utilizes dielectric polarization to generate the adsorption force, and the dielectric part functions as an electrostatic chuck. The adsorption force F is expressed by equation (1). F = (1 / 2) × ε ０ ×ε ｒ ２ × (V / d) ２ ...Equation (1) ε ０ : Permittivity of vacuum ε ｒ : Relative permittivity of the dielectric layer V: Applied voltage d: Thickness of the dielectric layer

[0029] From Equation (1), in order to sufficiently adsorb the wafer W, it is necessary to apply a high voltage to the dielectric. That is, the higher the applied voltage V, the greater the adsorption force F. Therefore, it is desirable that the base material used for the wafer support 10 satisfies the following conditions (a) to (d). (a) High resistivity: It should have a high resistivity for the adsorption force (Coulomb force) to be stably exhibited. (b) Plasma resistance: It should be difficult to be corroded by plasma. (c) High voltage resistance: It should be able to withstand the application of a high voltage. (d) Heat resistance: It should be able to withstand the plasma heat generated during the etching of the wafer.

[0030] Aluminum oxide satisfies the above-mentioned conditions (a) to (d). In addition, the fact that aluminum oxide satisfies the following conditions (e) to (g) is also one of the reasons why aluminum oxide is used as the dielectric layer. (e) High coefficient of thermal expansion: In the wafer support according to the present embodiment, the metal plate and the base material (dielectric layer) are adhered, and among ceramics, aluminum oxide with a high coefficient of thermal expansion has a small difference from the coefficient of thermal expansion of the metal plate. (f) High strength: Since the dielectric layer is designed to be thin in order to obtain a sufficient adsorption force (to reduce d in Equation (1)), it should have a strength that does not break even when thin. (g) High dielectric constant: The dielectric constant is relatively high at about 10 (in Equation (1), ε ｒ becomes large), and a relatively strong adsorption force can be obtained.

[0031] In recent years, in order to adsorb wafers with large warpage and to supply high-pressure gas to the back surface of the wafer to ensure temperature uniformity across the entire wafer, a larger adsorption force than before has been required. Therefore, in order to increase the adsorption force, from Equation (1), it is necessary to thin the dielectric plate (reduce d) and increase the applied voltage to a high voltage (increase V). However, in the conventional electrostatic chuck made of aluminum oxide, the following technical problems have occurred. (i) Decrease in mechanical strength and breakage due to thinning. (ii) Insufficient voltage resistance of the dielectric due to an increase in the applied voltage.

[0032] (Improvement of breakdown voltage) Since breakdown occurs from the pore positions, it is necessary to reduce the pores and fire densely. Also, to improve the breakdown voltage, it is necessary to reduce the particle size. This is because, to make it difficult for current to flow, it is sufficient to increase the length of the grain boundaries through which carriers pass between the electrodes, which can be achieved by reducing the particle size. Also, by reducing the particle size, the pores existing at the grain boundary triple points can be made smaller, and breakdown starting from the pore positions becomes less likely to occur.

[0033] (Improvement of strength) To be of high strength, it is necessary to reduce the pores and fire densely. Since strength decreases with grain growth, it is necessary to reduce the particle size to improve the strength.

[0034] The inventors considered the characteristics (a) to (g) of aluminum oxide and the problems (i) and (ii) arising from the increasing adsorption force required for electrostatic chucks in recent years, and studied additives other than aluminum oxide, their contents, and manufacturing methods.

[0035] (1) First, for improving the withstand voltage and strength, zirconium oxide (ZrO ２ ) having an effect of suppressing grain growth of aluminum oxide was selected as an additive. Also, yttrium oxide (Y ２ O ３ ) and ytterbium oxide (Yb ２ O ３ ) having a similar grain growth suppressing effect were added. Aluminum oxide, yttrium oxide, and ytterbium oxide can improve the relative permittivity ε ｒ and increase the adsorption force by adding them to aluminum oxide. Therefore, an electrostatic chuck mainly composed of aluminum oxide containing these additives can obtain a similar adsorption force even when the applied voltage is lowered or the thickness of the dielectric layer is increased, compared with an electrostatic chuck made of aluminum oxide not containing these additives. As a result, the withstand voltage and strength can be improved.

[0036] (2) Next, in order to further suppress grain growth to improve the breakdown voltage and strength, it is desirable to sinter at a low temperature. However, the aforementioned aluminum oxide, yttrium oxide, and ytterbium oxide have the function of inhibiting the sintering of aluminum oxide, making it difficult to achieve densification. Therefore, in order to enable low-temperature sintering of aluminum oxide, magnesium oxide (MgO), calcium oxide (CaO), and silicon oxide (SiO ２ ) were added.

[0037] (3) Furthermore, in order to further suppress grain growth to improve the breakdown voltage and strength, it is necessary to suppress the maximum temperature during firing. Therefore, in the manufacture of the wafer support, firing by hot pressing was carried out.

[0038] By adopting the means (1) to (3) above, the inventors have conceived that a wafer support with a breakdown voltage of 100 kV / mm or more, a flexural strength of 600 MPa or more, and a relative permittivity of 10.0 or more can be realized.

[0039] (Manufacturing method of wafer support) FIG. 3 is a flowchart for explaining the manufacturing method of the wafer support according to the present embodiment. First, according to a predetermined blending amount, a main raw material powder that becomes a ceramic component such as aluminum oxide, zirconium oxide, yttrium oxide, and ytterbium oxide, and a sintering aid powder such as magnesium oxide, calcium oxide, and silicon oxide are mixed to prepare a raw material powder (S10). The blending amount of aluminum oxide, which is the main component, is adjusted so as to be contained in the base material at 96% by mass or more. The aluminum oxide used in the present embodiment is α-aluminum oxide with a purity of 99.99% or more and an average particle size of about 0.4 μm.

[0040] To the main component, aluminum oxide, zirconium oxide, yttrium oxide, ytterbium oxide, magnesium oxide, calcium oxide, silicon oxide, etc., are added in predetermined proportions and mixed (S12). This mixing is carried out, for example, by wet mixing for 16 hours using a pot mill with a nylon pot and alumina balls. As a solvent, for example, ethanol with a concentration of about 0.75 kg / L (in the range of 0.1 to 1.0 kg / L) is used. Water or isopropyl alcohol (IPA) may be used instead of ethanol.

[0041] Next, the solvent is removed using an evaporator and the mixture is granulated. To further remove the solvent completely, the mixed raw materials are dried on a hot plate at 230°C (S14). Alternatively, the granulation may be performed using a spray dryer. The dried raw material powder is filled into a graphite mold and uniaxially pressed (S16). In this state, it is heated to 1400°C, held at a pressure of 30 MPa for 2 hours, and fired to produce a sintered body (S18).

[0042] Furthermore, a portion of the raw material powder or molded body may be replaced with a sintered body. In order to provide the electrodes of the electrostatic chuck inside the sintered body, when filling the hot press apparatus with raw material powder, molded body, or sintered body, a component or material that will become a conductor after firing (e.g., metal plate, metal foil, conductive paste, coil, mesh, etc.) should be placed (embedded) in the predetermined position. The shape of the conductor is not particularly limited. This firing can be carried out, for example, using a hot press apparatus. Hot pressing is carried out in a non-oxidizing (inert) atmosphere, such as nitrogen or argon, but it may also be carried out in pressurized nitrogen. The hot pressing temperature is, for example, in the range of 1350 to 1650°C. If the temperature is too low, sintering will be insufficient and densification will not occur, and if it is too high, grain growth will occur and the withstand voltage will decrease. The applied pressure is appropriate in the range of 20 to 50 MPa. The duration of hot pressing depends on the temperature and dimensions, but is usually about 1 to 4 hours. Subsequently, the sintered body is processed into the desired shape (S20), and the wafer support is manufactured.

[0043] Various characteristics of each sample produced by the above method (Examples 1 to 14 and Comparative Examples 1 to 16, described later) are measured and evaluated.

[0044] (Dielectric Breakdown Voltage Measurement) Based on JIS C2110-1, 10.1 (Short-Time Test), a DC voltage is applied to the sample in insulating oil. The voltage boosting rate is 1000 V / s. A plate-shaped sample with a thickness of 300 μm ± 50 μm is used for the measurement. The electrodes are as specified in JIS C2110-1, 5.2.1.3 (Spherical-Plate Electrode), with the upper electrode being a φ20 mm spherical shape and the lower electrode being a φ25 mm plate shape. The dielectric breakdown voltage is defined as the applied voltage at which dielectric breakdown occurs divided by the thickness of the sample.

[0045] (Bending strength) Based on JIS R1601 3.1 (three-point bending strength), the measurement is performed with an external support distance of 30 mm and a sample size of 37 × 3 × 4 mm.

[0046] (Relative Permittivity) The complex relative permittivity will be measured using the high-frequency I-V method. The measurement frequency will be 50 MHz.

[0047] (Porosity) Porosity is calculated based on JIS R 1655 (mercury intrusion method).

[0048] (Impure Metal Element Analysis) Quantitative analysis is performed by ICP-AES (Inductively Coupled Plasma Emission Spectroscopy). The content of constituent elements in the ceramic sintered body in terms of oxides may be calculated as follows: First, the constituent elements of the ceramic sintered body are qualitatively analyzed using an X-ray fluorescence analyzer (XRF) or an energy-dispersive analyzer (EDS) attached to a scanning electron microscope (SEM). Next, each element detected by this qualitative analysis is quantitatively analyzed using an ICP emission spectrometer. Then, the content of each element measured by this quantitative analysis is converted to oxides. (Particle Size Measurement) The fracture surface of the sample is photographed with a scanning electron microscope, and the particle size is calculated using the (linear) intercept method. A coefficient of 1.5 is used.

[0049] [Examples] Next, the characteristics of the wafer supports in each example and comparative example will be described. The content of ceramic components and sintering aid components in each example and comparative example is shown in Table 1. The samples in each example contain 96% by mass or more of aluminum oxide. The measurement results of each characteristic are also shown in Table 1. Note that when preparing each sample, the raw material for zirconium oxide mixed is not 100% pure zirconium oxide, but 97 mol% (94.64 wt%) ZrO ２ and 3 mol% (5.64 wt%) Y ２ O ３ This is yttria-stabilized zirconia (3Y-PSZ), which is a mixture of these materials. Therefore, even without adding yttrium oxide to the raw materials alone, trace amounts of yttrium oxide will be present as an additive in all samples.

[0050] Figure 4(a) is a graph showing the relationship between zirconium oxide content and dielectric breakdown voltage, Figure 4(b) is a graph showing the relationship between ytterbium oxide content and dielectric breakdown voltage, and Figure 4(c) is a graph showing the relationship between magnesium oxide content and dielectric breakdown voltage. Figure 5(a) is a graph showing the relationship between calcium oxide content and dielectric breakdown voltage, and Figure 5(b) is a graph showing the relationship between silicon oxide content and dielectric breakdown voltage.

[0051] In the graph in Figure 4(a), the dielectric breakdown voltage values ​​for each sample—Comparative Example 16, Example 11, Example 1, Example 5, Comparative Example 15, Comparative Example 14, and Comparative Example 13—are plotted from lowest to highest zirconium oxide content. From the results shown in Figure 4(a), samples with a zirconium content in the range of 0.47 to 1.83% by mass (in terms of zirconium oxide) satisfy the dielectric breakdown voltage requirement of 100 kV / mm or higher.

[0052] In the graph in Figure 4(b), the dielectric breakdown voltage values ​​for each sample from Example 13, Example 11, Example 1, and Example 5 are plotted in descending order of ytterbium oxide content. From the results shown in Figure 4(b), samples with a ytterbium content in the range of 0 to 0.48% by mass (in terms of ytterbium oxide) satisfy the dielectric breakdown voltage requirement of 100 kV / mm or higher.

[0053] The graph in Figure 4(c) plots the dielectric breakdown voltage values ​​for each sample, from lowest to highest magnesium oxide content: Comparative Example 5, Comparative Example 4, Comparative Example 3, Example 7, Example 9, Example 1, Example 6, and Comparative Example 2. From the results shown in Figure 4(c), samples with a magnesium content in the range of 0.29 to 0.73 mass% in terms of magnesium oxide satisfy the dielectric breakdown voltage requirement of 100 kV / mm or higher.

[0054] In the graph in Figure 5(a), the dielectric breakdown voltage values ​​for each sample—Comparative Example 8, Example 1, Example 4, and Comparative Example 6—are plotted from lowest to highest calcium oxide content. From the results shown in Figure 5(a), samples with a calcium content in the range of 0.10 to 0.20 mass% in terms of calcium oxide satisfy the dielectric breakdown voltage requirement of 100 kV / mm or higher.

[0055] In the graph in Figure 5(b), the dielectric breakdown voltage values ​​for each sample—Example 3, Example 1, Comparative Example 10, and Comparative Example 9—are plotted from lowest to highest silicon oxide content. From the results shown in Figure 5(b), samples with a silicon content in the range of 0 to 0.15 mass% in terms of silicon oxide satisfy the dielectric breakdown voltage requirement of 100 kV / mm or higher.

[0056] Thus, if the substrate contains 96% by mass or more of aluminum oxide, 0.47 to 1.83% by mass of zirconium in terms of zirconium oxide, and 0 to 0.48% by mass of yttrium or ytterbium in terms of yttrium oxide or ytterbium oxide, the dielectric breakdown voltage will be 100 kV / mm or more, the voltage applied to the conductive member can be increased, and the adsorption force can be improved.

[0057] Furthermore, as shown in each example, the substrate further contains at least one of the following: (1) magnesium in the form of 0.29 to 0.73% by mass, (2) calcium in the form of 0.1 to 0.2% by mass, or (3) silicon in the form of 0 to 0.15% by mass, (3) silicon in the form of silicon oxide. This enables low-temperature sintering and allows for densification while suppressing the grain growth of aluminum oxide.

[0058] Furthermore, in each of the samples from Examples 1 to 5 and Examples 11 to 13, the porosity obtained by the mercury intrusion method is 1.0% or less. This results in a denser ceramic sintered body, which improves the dielectric breakdown voltage.

[0059] Furthermore, in the samples of each example, the average particle size D50 of the ceramic sintered body is 0.7 to 1.5 μm, preferably in the range of 0.8 to 1.3 μm. This makes it possible to achieve a dense ceramic sintered body.

[0060] Furthermore, in each of the samples in Examples 1 to 8 and Examples 11 to 14, the bending strength of the ceramic sintered body is 600 MPa or higher. This makes deformation and breakage less likely to occur even when the dielectric layer is made thinner to improve the adsorption force.

[0061] Furthermore, in each of the samples in Examples 1 to 5 and Examples 11 to 13, the relative permittivity of the ceramic sintered body is 10.0 or higher. This improves the adsorption force.

[0062] The mass percentages of each additive shown in Table 1 represent the ideal content calculated from the amount of each additive used during mixing. On the other hand, when the additives in each sample prepared as a ceramic sintered body were analyzed by ICP-AES (inductively coupled plasma atomic emission spectroscopy), the content of all additives except aluminum oxide decreased. The rate of decrease in content varied depending on the sample and amount of additive, but was at most about 20%. Therefore, the lower limit of the preferred content range for each additive (excluding aluminum oxide) contained in the substrate may be about 20% lower than the range mentioned above when analyzed by ICP-AES.

[0063] Next, an example of a method for manufacturing a wafer support according to this embodiment is shown. This manufacturing method includes the steps of: preparing a raw material powder containing 96% by mass or more of aluminum oxide, 0.47 to 1.83% by mass of zirconium oxide, and 0 to 0.48% by mass of yttrium oxide or ytterbium oxide; arranging the raw material powder in a space of a predetermined shape; and firing the raw material powder by pressurizing the space in the range of 20 to 50 MPa and heating it in the range of 1350 to 1650°C. This makes it possible to manufacture a wafer support capable of achieving a desired adsorption force.

[0064] Although the present invention has been described above with reference to the embodiments and examples described above, the present invention is not limited to the embodiments described above, and the present invention also includes combinations and substitutions of the configurations of the embodiments as appropriate. Furthermore, it is possible to appropriately rearrange the combinations and order of processes in the embodiments or to make various design changes and other modifications to the embodiments based on the knowledge of those skilled in the art, and such modified embodiments may also be included in the scope of the present invention.

[0065] 10 wafer support, 12 chamber, 14 upper electrode, 16 substrate, 16a mounting surface, 18 conductive member, 20 gas supply path, 22 adhesive layer, 24 metal plate, 26 flow path, 100 etching apparatus.

Claims

1. A wafer support comprising a substrate made of a ceramic sintered body and a conductive member in which at least a portion is embedded within the substrate, wherein the substrate contains 96% by mass or more of aluminum oxide, 0.47 to 1.83% by mass of zirconium in terms of zirconium oxide, and 0 to 0.48% by mass of yttrium or ytterbium in terms of yttrium oxide or ytterbium oxide.

2. The wafer support according to claim 1, characterized in that the substrate further contains at least one of the following: (1) magnesium in an amount equivalent to magnesium oxide of 0.29 to 0.73% by mass, (2) calcium in an amount equivalent to calcium oxide of 0.1 to 0.2% by mass, or (3) silicon in an amount equivalent to silicon oxide of 0 to 0.15% by mass.

3. The wafer support according to claim 1 or 2, characterized in that the DC dielectric breakdown voltage of the ceramic sintered body is 100 kV / mm or more.

4. The wafer support according to claim 1 or 2, characterized in that the porosity of the ceramic sintered body obtained by the mercury intrusion method is 1.0% or less.

5. The wafer support according to claim 1 or 2, characterized in that the average particle size of the ceramic sintered body is 0.7 to 1.5 μm.

6. The wafer support according to claim 1 or 2, characterized in that the bending strength of the ceramic sintered body is 600 MPa or more.

7. The wafer support according to claim 1 or 2, characterized in that the relative permittivity of the ceramic sintered body is 10.0 or more.

8. The wafer support according to claim 1 or 2, further comprising a metal plate on which the substrate is mounted, wherein the metal plate has a channel formed therein for the flow of a cooling substance.

9. The wafer support according to claim 1 or 2, further comprising a gas supply path for supplying gas between the substrate and the wafer mounted on the substrate.

10. A method for manufacturing a wafer support, comprising the steps of: preparing a raw material powder containing 96% by mass or more of aluminum oxide, 0.47 to 1.83% by mass of zirconium oxide, and 0 to 0.48% by mass of yttrium oxide or ytterbium oxide; arranging the raw material powder in a space of a predetermined shape; and firing the raw material powder by pressurizing the space in the range of 20 to 50 MPa and heating it in the range of 1350 to 1650°C.

Images