Ceramic susceptor

Abstract

To provide a ceramic susceptor capable of improving volume resistivity in a high temperature range.SOLUTION: A ceramic susceptor according to an embodiment of the present invention includes a substrate mounting plate. The substrate mounting plate includes aluminum nitride and spinel. The content ratio of the aluminum nitride in the substrate mounting plate is 95.0 mass% or more and 99.9 mass% or less. The content ratio of the spinel in the substrate mounting plate is 0.1 mass% or more and 1.0 mass% or less in terms of oxide. The aluminum nitride has a polycrystalline structure. The spinel is located at a grain boundary between crystal grains of the aluminum nitride. The lattice constant of the spinel is 8.040 Å or more and 8.110 Å or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a ceramic susceptor. [Background technology]

[0002] In the manufacture of semiconductor devices such as integrated circuits, it is known to deposit a desired thin film on a semiconductor substrate supported by a ceramic susceptor that includes a resistive heating element. As such a ceramic susceptor, for example, a susceptor has been proposed that includes a plate containing a sintered body containing 90 wt% or more of an aluminum nitride phase, 0.5 to 3.0 wt% of magnesium in terms of MgO, and 0.05 to 0.5 wt% of titanium in terms of TiO2 (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-047311 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, semiconductor devices have become increasingly multilayered, and multiple thin films are sometimes stacked on a semiconductor substrate. In such cases, it is desirable to increase the film formation temperature to thin each of the multiple thin films and thereby reduce the total thickness of the stacked structure. However, when such a film formation process is performed using the susceptor described in Patent Document 1, residual stress from the thin film may cause warping of the semiconductor substrate. Therefore, studies are being conducted to further provide the susceptor described in Patent Document 1 with an electrostatic chuck (ESC; Electric Static Chuck) function to suppress warping of the semiconductor substrate during the film formation process. However, when the susceptor described in Patent Document 1 is provided with ESC electrodes and a film formation step is performed in a high temperature range of, for example, 600° C. or higher, the volume resistivity of the plate decreases, and there is a risk that a current leaks from the ESC electrodes to the plate. When a current leaks from the ESC electrodes to the plate, the electrostatic chucking function for the semiconductor substrate becomes insufficient, and the semiconductor substrate may not be stably supported in the film formation step. A primary object of the present invention is to provide a ceramic susceptor that can improve volume resistivity in a high temperature range. [Means for solving the problem]

[0005] [1] A ceramic susceptor according to an embodiment of the present invention has a substrate mounting plate. The substrate mounting plate contains aluminum nitride and a spinel. The aluminum nitride content in the substrate mounting plate is 95.0 mass % or more and 99.9 mass % or less. The spinel content in the substrate mounting plate is 0.1 mass % or more and 1.0 mass % or less, calculated as oxide. The aluminum nitride has a polycrystalline structure. The spinel is located at the grain boundaries between the aluminum nitride crystal grains. The lattice constant of the spinel is 8.040 Å or more and 8.110 Å or less. [2] In the ceramic susceptor described in [1] above, the substrate mounting plate may further contain titanium nitride. [3] In the ceramic susceptor described in [2] above, the content of titanium nitride in the substrate mounting plate may be 0.01% by mass or more and 1.0% by mass or less in terms of oxide. [4] In the ceramic susceptor according to any one of [1] to [3] above, the volume resistivity of the substrate mounting plate at 600°C is 1.0 × 10 9 It may be Ω·cm or more. [5] In the ceramic susceptor according to any one of [1] to [4] above, the content of α-aluminum oxide in the substrate mounting plate may be 1.0 mass % or less. [6] The ceramic susceptor according to any one of [1] to [5] above may further include an internal electrode embedded in the substrate mounting plate. [7] In the ceramic susceptor described in [6] above, the internal electrode may further include a resistance heating element. [Effects of the Invention]

[0006] According to an embodiment of the present invention, a ceramic susceptor having improved volume resistivity in a high temperature range can be realized. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a ceramic susceptor according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments. In addition, in order to clarify the explanation, the width, thickness, shape, etc. of each part may be shown schematically in the drawings compared to the embodiments, but this is merely an example and does not limit the interpretation of the present invention.

[0009] A. Overview of ceramic susceptors FIG. 1 is a schematic diagram of a ceramic susceptor according to one embodiment of the present invention. The ceramic susceptor 100 includes a substrate mounting plate 1. The substrate mounting plate 1 can have any appropriate shape. The substrate mounting plate 1 preferably has a disk shape. The thickness of the substrate mounting plate 1 is, for example, 5 mm to 50 mm. The substrate mounting plate 1 has a mounting surface 1a on which a semiconductor substrate 8 can be placed. The mounting surface 1a is typically one surface of the substrate mounting plate 1 in the thickness direction.

[0010] In one embodiment, the substrate mounting plate 1 contains aluminum nitride (hereinafter referred to as AlN) and spinel. In other words, the substrate mounting plate 1 contains an AlN crystal phase and a spinel crystal phase. The AlN content in the substrate mounting plate 1 is 95.0 mass % or more and 99.9 mass % or less. The spinel content in the substrate mounting plate 1 is 0.1 mass % or more and 1.0 mass % or less, calculated as oxide. The AlN has a polycrystalline structure. The spinel is located at the grain boundaries between the AlN crystal grains. The lattice constant of the spinel is 8.040 Å or more and 8.110 Å or less. The present inventors discovered that a small amount of spinel present in a substrate mounting plate with an AlN content of 95.0 mass % or more affects the volume resistivity of the substrate mounting plate at high temperatures (for example, 600°C or higher). As a result of extensive research into the arrangement and crystalline state of the spinel, they discovered that the volume resistivity of the substrate mounting plate at high temperatures can be improved by having a spinel with a specific lattice constant present at the grain boundaries between AlN crystal grains. Specifically, by having a spinel having a lattice constant of 8.040 Å or more and 8.110 Å or less present at the grain boundaries between AlN crystal grains, it is possible to improve the volume resistivity of the substrate mounting plate in the high temperature range and to significantly suppress the decrease in volume resistivity of the substrate mounting plate in the high temperature range.

[0011] A-1. Aluminum nitride (AlN) The substrate mounting plate 1 contains a plurality of AlN crystal grains. Among the plurality of AlN crystal grains, adjacent AlN crystal grains are typically bonded together. The average grain size of the plurality of AlN crystal grains is, for example, 1 μm to 5 μm, and preferably 1 μm to 3 μm.

[0012] The AlN content in the substrate mounting plate 1 is preferably 97.0 mass % or more, and more preferably 98.0 mass % or more. On the other hand, the AlN content in the substrate mounting plate 1 is preferably 99.8 mass % or less, more preferably 99.5 mass % or less, and even more preferably 99.0 mass % or less. When the content of AlN in the substrate mounting plate is within this range, high thermal conductivity, high toughness, and high dielectric strength can be achieved. The content ratio of the composition elements in the substrate mounting plate is measured, for example, by ICP-AES (inductively coupled plasma atomic emission spectroscopy) in accordance with JIS K0116. The crystalline phase in the substrate mounting plate is measured, for example, by XRD (X-ray diffraction) in accordance with JIS Z2201 and JIS K0114.

[0013] A-2. Spinel Spinel typically exists at grain boundaries or is formed by the reaction of magnesium oxide and aluminum oxide at the grain boundaries between AlN crystal grains. The crystal system of spinel is typically a cubic system, more specifically a face-centered cubic system. The lattice constant (a-axis lattice constant) of the spinel is preferably 8.050 Å or more, more preferably 8.060 Å or more, even more preferably 8.063 Å or more, particularly preferably 8.064 Å or more, particularly preferably 8.070 Å or more, and even more particularly preferably 8.075 Å or more. On the other hand, the lattice constant of the spinel (lattice constant of the a-axis) is preferably 8.100 Å or less, and more preferably 8.090 Å or less. When the lattice constant of the spinel is in this range, the volume resistivity of the substrate mounting plate in the high temperature range can be further improved, and a decrease in the volume resistivity of the substrate mounting plate in the high temperature range can be sufficiently suppressed.

[0014] The spinel content in the substrate mounting plate 1 is preferably 0.2 mass % or more, and more preferably 0.3 mass % or more, calculated as oxide. On the other hand, the spinel content in the substrate mounting plate 1 is preferably 0.9 mass % or less, calculated as oxide. When the spinel content in the substrate mounting plate is within this range, the volume resistivity of the substrate mounting plate in the high temperature range can be stably improved.

[0015] A-3. Titanium nitride (TiN) In one embodiment, the substrate mounting plate 1 further contains titanium nitride (hereinafter referred to as TiN). In other words, the substrate mounting plate 1 contains a TiN crystalline phase in addition to the AlN crystalline phase and the spinel crystalline phase. TiN is typically present at the grain boundaries between AlN crystal grains.

[0016] The TiN content in the substrate mounting plate 1 is, in terms of oxide, for example, 0.01 mass % or more, and preferably 0.3 mass % or more. On the other hand, the TiN content in the substrate mounting plate 1 is, in terms of oxide, for example, 1.0 mass % or less, and preferably 0.8 mass % or less. When the content of TiN in the substrate mounting plate is within this range, the formation of conductive paths in the grain boundary layer is suppressed, and a decrease in the volume resistivity of the substrate mounting plate is suppressed, which is preferable.

[0017] A-4. Other crystalline phases The substrate mounting plate 1 may further contain other crystalline phases, which are crystalline phases other than the AlN crystalline phase, the spinel crystalline phase, and the TiN crystalline phase, and examples thereof include α-aluminum oxide (α-alumina). The content of other crystalline phases in the substrate mounting plate 1 is, for example, 1.0 mass % or less. On the other hand, the lower limit of the content of other crystalline phases in the substrate mounting plate 1 is typically 0 mass %. When the content ratio of the other crystalline phase in the substrate mounting plate is within this range, a decrease in the volume resistivity of the substrate mounting plate in a high temperature range can be stably suppressed.

[0018] A-5. Physical properties of the substrate mounting plate Such a substrate mounting plate has a relatively high volume resistivity in a high temperature range. The volume resistivity of the substrate mounting plate 1 at 600°C is, for example, 1.0×10 9 Ω·cm or more, preferably 1.2×10 9 Ω·cm or more, preferably 2.0×10 9 Ω·cm or more, more preferably 5.0×10 9Ω·cm or more, particularly preferably 1.0×10 10 Ω·cm or more, particularly preferably 7.0×10 10 Ω·cm or more, most preferably 8.0×10 10 Ω·cm or more. On the other hand, the volume resistivity of the substrate mounting plate 1 at 600°C is, for example, 1.0×10 12 Ω·cm or less, e.g., 1.5×10 11 Ω·cm or less. The volume resistivity of the substrate mounting plate at 600° C. is measured in accordance with, for example, JIS C2141-1992.

[0019] The thermal conductivity of the substrate mounting plate 1 at 600° C. is, for example, 20 W / m·K to 50 W / m·K. The thermal conductivity of the substrate mounting plate at 600° C. is measured in accordance with the flash method specified in JIS R1611:2010, for example.

[0020] The open porosity of the substrate mounting plate 1 is, for example, 1.0% or less. The open porosity of the substrate mounting plate is measured in accordance with, for example, JIS R1634.

[0021] The relative density of the substrate mounting plate 1 is, for example, 99.0% or more, and preferably 99.5% or more. On the other hand, the upper limit of the relative density of the substrate mounting plate 1 is typically 100%. The relative density of the substrate mounting plate is measured, for example, in accordance with JIS R1634.

[0022] B. Manufacturing method of substrate mounting plate Next, a method for manufacturing a substrate mounting plate according to one embodiment will be described. A method for manufacturing a substrate mounting plate according to one embodiment includes a mixing step, a molding step, a calcining step, and a firing step, in this order.

[0023] B-1.Mixing process In the mixing step, at least an AlN raw material and a magnesium oxide raw material (hereinafter referred to as an MgO raw material) are mixed together, or an AlN raw material and a spinel raw material are mixed together to prepare a mixture.

[0024] The AlN raw material contains AlN as a main component, and may contain oxygen and carbon in addition to AlN. The amount of oxygen in the AlN raw material is, for example, 0.7 mass % to 0.9 mass % The amount of carbon in the AlN raw material is, for example, 200 ppm to 400 ppm. The AlN raw material is typically in powder form, and the average particle size D50 of the AlN raw material is, for example, 1 μm.

[0025] The MgO raw material contains MgO as a main component. The MgO raw material is typically in a powder form. The average particle size D50 of the MgO raw material is, for example, 0.5 μm.

[0026] The amount of MgO raw material added is, for example, 0.1 part by mass or more, preferably 0.2 part by mass or more, and more preferably 0.4 part by mass or more, relative to 100 parts by mass of AlN raw material. On the other hand, the amount of MgO raw material added is, for example, 1.1 parts by mass or less, preferably 1.0 part by mass or less, and more preferably 0.9 part by mass or less, relative to 100 parts by mass of AlN raw material.

[0027] In the mixing step, if necessary, a titanium oxide raw material (hereinafter referred to as a TiO2 raw material) is further mixed with the AlN raw material and the MgO raw material (or the spinel raw material). The TiO2 raw material contains TiO2 as a main component. The TiO2 raw material is typically in a powder form. The average particle size D50 of the TiO2 raw material is, for example, 0.3 μm.

[0028] The amount of TiO2 raw material added is, for example, 0.1 part by mass or more, preferably 0.3 part by mass or more, relative to 100 parts by mass of AlN raw material, while the amount of TiO2 raw material added is, for example, 1.0 part by mass or less, relative to 100 parts by mass of AlN raw material.

[0029] In one embodiment, in the mixing step, a binder is added to the AlN raw material and the MgO raw material. Examples of binders include polyvinyl acetal resins, cellulose ether resins, (meth)acrylic resins, and paraffin wax. The term "(meth)acrylic resin" includes acrylic resins and / or methacrylic resins. Binders may be used alone or in combination. Of these binders, (meth)acrylic resins are preferred.

[0030] In the mixing step, any suitable mixing device can be used, such as a ball mill, a bead mill, a vibration mill, a rocking mixer, a blender, a homogenizer, or the like.

[0031] The mixing method may be dry mixing or wet mixing. In one embodiment, wet mixing is performed in the mixing step. In wet mixing, any suitable solvent is used. Examples of the solvent include alcohols such as isopropyl alcohol and ethanol; and aromatic hydrocarbons such as toluene and xylene.

[0032] The environmental conditions in the mixing step are not particularly limited, and the mixing step is typically carried out at room temperature (23°C) and atmospheric pressure (0.1 MPa). The mixing time can be set arbitrarily and appropriately, for example, from 1 hour to 24 hours.

[0033] In this way, a mixture containing at least the AlN raw material and the MgO raw material (or the spinel raw material) is prepared. If the mixing step is dry mixing, the mixture is in a powder state, and if the mixing step is wet mixing, the mixture is in a slurry state.

[0034] B-2. Granulation process In one embodiment, the method for manufacturing a substrate mounting plate includes a granulation step after the mixing step and before the molding step. In the granulation step, the mixture obtained in the mixing step is granulated by any appropriate granulation method, such as spray granulation or tumble granulation, preferably spray granulation. This prepares a granulated mixture (hereinafter referred to as raw material granules).

[0035] B-3. ​​Molding process Next, in the molding step, the mixture (preferably raw material granules) is molded into a desired shape by any appropriate molding method. Examples of the molding method include press molding, sheet molding, and cold isostatic pressing (CIP) molding, and press molding is preferred. The pressure in press molding is, for example, 10 kgf / cm. 2 ~500kgf / cm 2 is. In this way, a molded body having a desired shape is prepared.

[0036] B-4. Firing process In the subsequent firing step, the compact is typically fired in a vacuum or a non-oxidizing atmosphere. More specifically, the temperature is raised from room temperature (23°C) to a predetermined firing temperature, and then the firing temperature is maintained for a predetermined firing time. A degreasing step may be performed before the firing step, if necessary.

[0037] The firing temperature is, for example, 1600°C to 1900°C, and preferably 1650°C to 1850°C. The firing time is, for example, 0.5 to 100 hours. The environmental pressure in the firing step is, for example, 100 kPa to 900 kPa.

[0038] Examples of the firing method include hot pressing and hot isostatic pressing (HIP), with hot pressing being preferred. In the hot press, typically, the compact is placed in a hot press die (for example, a carbon jig), heated to the firing temperature as described above, and pressed at a predetermined pressure, for example, 5 MPa to 50 MPa.

[0039] The temperature is then lowered from the firing temperature to room temperature (23°C). The temperature lowering rate is adjusted arbitrarily and appropriately depending on the amount of MgO raw material added. The temperature lowering rate is, for example, 250°C / hr or less, preferably 150°C / hr or less, and more preferably 120°C / hr or less. When the temperature lowering rate is below this upper limit, the lattice constant of the spinel produced in the firing step can be stably adjusted to fall within the above-mentioned range. On the other hand, the temperature decreasing rate is, for example, 50°C / hr or more, preferably 80°C / hr or more. In such a firing step, the above-mentioned raw materials are sintered and react with each other to produce a composite sintered body containing AlN and spinel. In this way, a substrate mounting plate having a desired shape is prepared. The substrate mounting plate is typically made of a composite sintered body.

[0040] C. Ceramic susceptor details The ceramic susceptor 100 may be composed of only the substrate mounting plate 1, or may further include other members in addition to the substrate mounting plate 1.

[0041] As shown in FIG. 1, the ceramic susceptor further includes an internal electrode 2 in addition to the substrate-mounting plate 1 described above.

[0042] The internal electrodes 2 are embedded in the substrate mounting plate 1. To embed the internal electrodes 2 in the substrate mounting plate 1, for example, in the above-described molding step, the mixture is molded in a state in which the internal electrodes 2 are embedded in the mixture at desired positions, and then a calcination step and a firing step are carried out.

[0043] The internal electrode 2 is located in the thickness direction of the substrate mounting plate 1 at a predetermined distance from the mounting surface 1a. In the thickness direction of the substrate mounting plate 1, the distance between the mounting surface 1a and the internal electrode 2 is, for example, 0.1 mm to 3.0 mm.

[0044] Examples of the internal electrode 2 include an ESC electrode, an RF electrode, and a resistance heating element.

[0045] In the illustrated example, the ceramic susceptor 100 includes ESC electrodes 21 as the internal electrodes 2. In a case where the internal electrode 2 includes the ESC electrodes 21, when a voltage is applied to the ESC electrodes 21 with the semiconductor substrate 8 placed on the mounting surface 1a, the ESC electrodes 21 are charged with either positive or negative charges, and the other of the positive and negative charges present in the semiconductor substrate 8 moves toward the mounting surface 1a in the semiconductor substrate 8. As a result, a Coulomb force is generated between the semiconductor substrate 8 and the ESC electrodes 21, and the semiconductor substrate 8 is chucked to the substrate mounting plate 1.

[0046] Although not shown, the ceramic susceptor 100 may include a plurality of ESC electrodes 21. The plurality of ESC electrodes 21 are embedded in the substrate mounting plate 1 and are positioned apart from each other in a plane direction orthogonal to the thickness direction of the substrate mounting plate 1. In the case where the ceramic susceptor 100 includes the plurality of ESC electrodes 21, when voltages are applied to the plurality of ESC electrodes 21, some of the plurality of ESC electrodes 21 can be positively charged and the remaining parts of the plurality of ESC electrodes 21 can be negatively charged. Therefore, the semiconductor substrate 8 can be chucked to the substrate mounting plate 1 in multiple zones.

[0047] In one embodiment, the internal electrode 2 functions as an RF electrode (i.e., a radio frequency electrode) for plasma processing. In the illustrated example, the ESC electrodes 21 further function as RF electrodes. That is, the ESC electrodes 21 preferably function as RF / ESC electrodes. Examples of the plasma processing include a film formation process and an etching process. When such plasma processing is performed on the semiconductor substrate 8 on the mounting surface 1a, an upper electrode is disposed on the opposite side of the RF electrode with respect to the semiconductor substrate 8. When high-frequency power is supplied to the RF electrode in this state, the processing gas is excited in the space between the substrate mounting plate 1 and the upper electrode, and plasma can be generated. The semiconductor substrate 8 is subjected to plasma processing by the plasma.

[0048] The ESC electrodes 21 may have any appropriate shape. The ESC electrodes 21 typically have a plate shape. In one embodiment, the ESC electrodes 21 have a shape similar to the outer shape of the substrate mounting plate 1 when viewed in the thickness direction of the substrate mounting plate 1. In the illustrated example, the centers of the ESC electrodes 21 and the center of the substrate mounting plate 1 substantially coincide with each other when viewed in the thickness direction of the substrate mounting plate 1. The thickness of the ESC electrode 21 is, for example, 0.1 mm to 1.0 mm.

[0049] The ESC electrodes 21 are made of any suitable conductive material. A typical conductive material is a metal having a relatively high melting point. Examples of such metals include tantalum (Ta), tungsten (W), molybdenum (Mo), platinum (Pt), rhenium (Re), hafnium (Hf), and alloys thereof. These metals may be used alone or in combination.

[0050] In the illustrated example, the first power feed rods 6 are electrically connected to the ESC electrodes 21. The above-described voltage (or high-frequency power) can be applied to the ESC electrodes 21 via the first power feed rods 6. The first power feed rods 6 are typically made of the same metal as the ESC electrodes 21.

[0051] In one embodiment, the ceramic susceptor 100 further includes a resistance heating element 22 as the internal electrode 2 . In the illustrated example, the resistance heating element 22 is located on the opposite side of the ESC electrodes 21 to the mounting surface 1a of the substrate mounting plate 1. To embed the resistance heating element 22 in the substrate mounting plate 1, for example, in the molding step described above, the mixture is molded with the resistance heating element 22 embedded in the mixture at the desired position, and then a firing step is carried out.

[0052] The resistance heating element 22 is configured to generate heat when a voltage is applied thereto. The resistance heating element 22 may have any suitable shape. Examples of the shape of the resistance heating element 22 include a coil shape, a zigzag shape, and a mesh shape. In the illustrated example, the resistance heating element 22 has a coil shape. The resistance heating element 22 may be formed by printing.

[0053] The resistance heating element 22 is made of any suitable conductive material. A typical conductive material is a metal having a relatively high melting point. Examples of such metals include tantalum (Ta), tungsten (W), molybdenum (Mo), tungsten carbide (WC), titanium nitride (TiN), platinum (Pt), rhenium (Re), hafnium (Hf), and alloys thereof. These conductive materials may be used alone or in combination. Among the conductive materials, W, Mo, W—Mo alloy, WC, and WC—TiN alloy are preferable.

[0054] In the illustrated example, the resistance heating element 22 is electrically connected to the second power feed rod 7. The above-mentioned voltage can be applied to the resistance heating element 22 via the second power feed rod 7. The second power feed rod 7 is typically made of the same conductive material as the resistance heating element 22.

[0055] The ceramic susceptor 100 may further include a ceramic shaft 5. The ceramic shaft 5 is capable of supporting the substrate mounting plate 1. The ceramic shaft 5 is connected to the surface of the substrate mounting plate 1 opposite to the mounting surface 1a.

[0056] The ceramic shaft 5 has any appropriate shape. In one embodiment, the ceramic shaft 5 has a cylindrical shape extending in the thickness direction of the substrate mounting plate 1. In the illustrated example, the axis of the ceramic shaft 5 and the center of the substrate mounting plate 1 substantially coincide with each other when viewed in the thickness direction of the substrate mounting plate 1. The first power feed rod 6 passes through the internal space of the ceramic shaft 5 and is connected to the internal electrode 2. The second power feed rod 7 passes through the internal space of the ceramic shaft 5 and is connected to the resistance heating element 22. The ceramic shaft 5 is made of any appropriate ceramic material, for example, aluminum nitride, and is preferably made of the same material as the substrate mounting plate 1.

[0057] Such ceramic susceptors can be used in any suitable industrial product, such as a susceptor, a ceramic heater, or an electrostatic chuck. In such a ceramic susceptor 100, the lattice constant of the spinel contained in the substrate mounting plate 1 is within the above-mentioned range, and therefore the volume resistivity of the substrate mounting plate can be improved at high temperatures, for example, at or above 600° C. Therefore, in plasma processing such as film formation processing, current leakage from the internal electrode 2 can be significantly suppressed, and the electrostatic chuck function for the semiconductor substrate 8 can be fully exerted. [Example]

[0058] The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these examples. The methods for measuring each property are as follows.

[0059] (1) Measurement of the volume resistivity of the substrate mounting plate The volume resistivity at 600°C of the substrate mounting plates manufactured in the examples and comparative examples was measured in a vacuum atmosphere in accordance with JIS C2141-1992. More specifically, a disk-shaped test piece was prepared from the substrate mounting plate. The diameter of the test piece was 50 mm, and the thickness of the test piece was 1 mm. Next, a main electrode and a guard electrode were provided on the upper surface of the test piece, and an application electrode was provided on the lower surface of the test piece. The main electrode, guard electrode, and application electrode were each made of silver (Ag). The diameter of the main electrode was 20 mm. The inner diameter of the guard electrode was 30 mm, and the outer diameter of the guard electrode was 40 mm. The diameter of the application electrode was 45 mm. Next, a voltage of 500 V / mm was applied to the test piece, and the current value was read one minute after the voltage application. The volume resistivity was calculated from the current value and evaluated according to the following criteria. The results are shown in Table 1. ○: The volume resistivity of the substrate mounting plate at 600°C is 1×10 9 Ω cm or more ×: The volume resistivity of the substrate mounting plate at 600°C is 1×10 9 Less than Ω cm

[0060] (2) Identification of the crystalline phases contained in the substrate mounting plate and calculation of the content ratio of each crystalline phase The substrate mounting plates manufactured in the examples and comparative examples were ground in a mortar, and then silicon (Si) powder, an internal standard sample, was added and mixed. The resulting mixed powder was analyzed using an X-ray diffraction (XRD) device to identify the crystalline phase of the substrate mounting plate. The results are shown in Table 1. The measurement conditions were CuKα, 40 kV, 40 mA, 2θ = 20 to 80°, and a sealed tube X-ray diffractometer (D8-ADVANCE, manufactured by Bruker AXS) was used. The measurement step width was 0.02°. The content of each crystal phase in the substrate mounting plate was calculated by XRD. The results are shown in Table 1.

[0061] (3) Calculation of the lattice constant of the spinel contained in the substrate mounting plate The lattice constant of the spinel contained in the substrate mounting plates manufactured in the examples and comparative examples was calculated by the WPPD method (powder pattern fitting method) using software (TOPAS manufactured by Bruker AXS). The results are shown in Table 1.

[0062] <<Example 1>> AlN raw material powder (average particle size D50: 1.2 μm, oxygen content: 0.8 mass%), MgO raw material powder (average particle size D50: 0.5 μm), and TiO raw material powder (average particle size D50: 0.3 μm) were charged into a ball mill according to the formulation shown in Table 1, and then acrylic resin (binder) and isopropyl alcohol (IPA) were added to the ball mill and wet-mixed for 2 hours. The resulting slurry was then dried and granulated using a spray granulator to obtain raw granules with a particle size of 80 μm. The raw material granules were then subjected to uniaxial pressing to obtain a disk-shaped compact. The pressure in the uniaxial pressing was 100 kgf / cm. 2 It was. The compact was then degreased and sintered by hot pressing. More specifically, the compact was sintered in a nitrogen atmosphere at 1800°C for 2 hours and cooled at a rate of 100°C / hr to obtain a substrate mounting plate.

[0063] <<Examples 2 to 6, Comparative Examples 1 and 2>> A substrate mounting plate was obtained in the same manner as in Example 1, except that the amounts of AlN raw material powder, MgO raw material powder, and TiO2 raw material powder added were changed to the formulations shown in Table 1, and the temperature drop rate was changed to the formulations shown in Table 1.

[0064] [Table 1]

[0065] [evaluation] As is clear from Table 1, in a substrate mounting plate having an aluminum nitride (AlN) content of 95.0% or more, when spinel having a lattice constant of 8.060 Å to 8.100 Å is present at the grain boundaries, the volume resistivity of the substrate mounting plate at 600°C can be improved. [Industrial Applicability]

[0066] The ceramic susceptor according to the embodiment of the present invention can be used in various industrial products, and can be particularly suitably used as a ceramic susceptor provided in semiconductor device manufacturing equipment. [Explanation of symbols]

[0067] 1. Substrate mounting plate 2 Internal electrode 22 Resistive heating element 100 Ceramic susceptor

Claims

1. A ceramic susceptor having a substrate mounting plate including aluminum nitride and spinel, a content ratio of the aluminum nitride in the substrate mounting plate is 95.0 mass % or more and 99.9 mass % or less, the content of the spinel in the substrate mounting plate is 0.1 mass % or more and 1.0 mass % or less in terms of oxide; The aluminum nitride has a polycrystalline structure, the spinel is located at grain boundaries between crystal grains of the aluminum nitride, The ceramic susceptor, wherein the lattice constant of the spinel is 8.040 Å or more and 8.110 Å or less.

2. The ceramic susceptor of claim 1 , wherein the substrate mounting plate further comprises titanium nitride.

3. 3. The ceramic susceptor according to claim 2, wherein the content of said titanium nitride in said substrate mounting plate is 0.01 mass % or more and 1.0 mass % or less in terms of oxide.

4. The volume resistivity of the substrate mounting plate at 600°C is 1.0 × 10 ９ The ceramic susceptor according to claim 1 , wherein the resistivity is Ω·cm or more.

5. 4. The ceramic susceptor according to claim 1, wherein the content of α-aluminum oxide in the substrate mounting plate is 1.0 mass % or less.

6. The ceramic susceptor according to claim 1 , further comprising an internal electrode embedded in the substrate mounting plate.

7. The ceramic susceptor of claim 6 , wherein the internal electrode further comprises a resistive heating element.

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