Ceramic base

Abstract

Provided is a ceramic susceptor capable of improving the volume resistivity in a high-temperature region. A ceramic susceptor according to an embodiment of the present invention has 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 from 95.0% by mass to 99.9% by mass (inclusive). The content ratio of the spinel in the substrate mounting plate is 0.1% by mass or more and 1.0% by mass or less in terms of oxides. The aluminum nitride has a polycrystalline structure. The spinel is located at a grain boundary between grains of the aluminum nitride. The spinel has a lattice constant of not less than 1 and not more than 2.

Description

TECHNICAL FIELD The present application relates to a ceramic base. BACKGROUND It is known that, in the production of semiconductor devices such as integrated circuits, a desired thin film is formed on a semiconductor substrate supported by a ceramic base provided with an electric resistance heating body. As such a ceramic base, for example, a base is proposed which is provided with a plate including a sintered body containing: an aluminum nitride phase of 90 wt% or more, magnesium of 0.5 to 3.0 wt% in terms of MgO, and titanium of 0.05 to 0.5 wt% in terms of TiO2(see Patent Literature 1). PRIOR ART DOCUMENTS PATENT LITERATURE Patent Literature 1: Japanese Patent Application Publication No. 2023-047311 SUMMARY In recent years, with the multilayering of semiconductor devices, there are cases where a plurality of thin films are stacked on a semiconductor substrate. In such cases, it is desirable to increase the film formation temperature to thin the plurality of thin films respectively, thereby reducing the total thickness of the stacked structure. However, when such a film formation process is performed using the base described in Patent Literature 1, warping of the semiconductor substrate can occur due to residual stress from the thin films. Therefore, it has been investigated to further impart an electrostatic chuck (ESC) function to the base described in Patent Literature 1 to suppress warping of the semiconductor substrate in the film formation process. However, when an ESC electrode is provided to the base described in Patent Literature 1 to perform a film formation process in a high temperature region of, for example, 600°C or higher, there is a possibility that the volume resistivity of the plate decreases, and current leaks from the ESC electrode to the plate. If current leaks from the ESC electrode to the plate, the electrostatic chuck function with respect to the semiconductor substrate is insufficient, and sometimes the semiconductor substrate cannot be stably supported in the film formation process. The present application has been made in view of the above circumstances, and it is a main object of the present application to provide a ceramic base capable of improving the volume resistivity in a high temperature region.

[0001] A ceramic base according to an embodiment of the present application has a substrate mounting plate. The substrate mounting plate contains 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. A 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 grain boundaries between grains of the aluminum nitride. A lattice constant of the spinel is 8.1 A or more and 8.3 A or less. The above and other The following.

[0002] The ceramic base of the above [1] can further include titanium nitride in the substrate mounting board.

[0003] The ceramic base of the above [2] can have a content ratio of the titanium nitride in the substrate mounting board be 0.01 mass% or more and 1.0 mass% or less in terms of oxide.

[0004] The ceramic base of any one of the above [1] to [3] can have a volume resistivity of the substrate mounting board be 1.0 x 10 9 Ω·cm or more at 600°C.

[0005] The ceramic base of any one of the above [1] to [4] can have a content ratio of α-alumina in the substrate mounting board be 1.0 mass% or less.

[0006] The ceramic base of any one of the above [1] to [5] can further include an internal electrode implanted in the substrate mounting board.

[0007] The ceramic base of the above [6] can further include a resistance heating element in the internal electrode. Effects of Invention According to the embodiment of the present application, a ceramic base having a volume resistivity improved in a high temperature region can be achieved. BRIEF DESCRIPTION OF DRAWINGS Figure 1 is a schematic configuration view of a ceramic base according to an embodiment of the present application. Explanation of Symbols 1… substrate mounting board, 2… internal electrode, 22… resistance heating element, 100… ceramic base. DETAILED DESCRIPTION Hereinafter, embodiments of the present application will be described, but the present application is not limited to these embodiments. In addition, the drawings make the description more explicit, and thus, the width, thickness, shape, etc. of each portion are sometimes schematically shown compared to the embodiments, but this is only an example and does not limit the explanation of the present application. A. Overview of Ceramic Base Figure 1 is a schematic configuration view of a ceramic base according to an embodiment of the present application. The ceramic base 100 includes a substrate mounting board 1. The substrate mounting board 1 can have an arbitrary appropriate shape. The substrate mounting board 1 preferably has a circular plate shape. The thickness of the substrate mounting board 1 is, for example, 5 mm to 50 mm. The substrate mounting board 1 has a mounting surface la capable of mounting a semiconductor substrate 8. Typically, the mounting surface la is one surface in the thickness direction of the substrate mounting board 1. In one embodiment, the substrate carrier 1 contains aluminum nitride (hereinafter, referred to as AlN) and spinel. In other words, the substrate carrier 1 contains an AlN crystal phase and a spinel crystal phase. The content ratio of the AlN in the substrate carrier 1 is 95.0% by mass or more and 99.9% by mass or less. The content ratio of the spinel in the substrate carrier 1 is 0.1% by mass or more and 1.0% by mass or less in terms of oxides. The AlN has a polycrystalline structure. The spinel is located at the grain boundaries between the grains of the AlN. The lattice constant of the spinel is and the above and below. The inventors of the present application have found that the minute amount of spinel present in the substrate carrier 1 having the content ratio of AlN of 95.0% by mass or more has an effect on the volume resistivity of the substrate carrier 1 in a high temperature region (for example, 600°C or more). Therefore, the arrangement and the crystal state of the spinel have been intensively studied, and as a result, it has been found that the volume resistivity of the substrate carrier 1 in a high temperature region can be improved by the presence of the spinel having a specific lattice constant at the grain boundaries between the grains of the AlN. Specifically, the volume resistivity of the substrate carrier 1 in a high temperature region can be improved, and the decrease in the volume resistivity of the substrate carrier 1 in a high temperature region can be significantly suppressed by the presence of the spinel having a lattice constant of and the above and below at the grain boundaries between the grains of the AlN. A-1. Aluminum nitride (AlN) The substrate carrier 1 contains a plurality of AlN grains. Typically, the AlN grains adjacent to each other among the plurality of AlN grains are bonded. The average particle diameter of the plurality of AlN grains is, for example, 1 μm to 5 μm, and preferably 1 μm to 3 μm. The content ratio of the AlN in the substrate carrier 1 is preferably 97.0% by mass or more, and more preferably 98.0% by mass or more. On the other hand, the content ratio of the AlN in the substrate carrier 1 is preferably 99.8% by mass or less, and more preferably 99.5% by mass or less, and further preferably 99.0% by mass or less. If the content ratio of the AlN in the substrate carrier is in such a range, high thermal conductivity, high toughness, and high dielectric withstand voltage can be exhibited. Note that the content ratio of the constituent elements in the substrate carrier is measured in accordance with JIS-K0116, for example, by ICP-AES (inductively coupled plasma atomic emission spectrometry). In addition, the crystal phase in the substrate carrier is measured in accordance with JIS Z2201, JIS K0114, for example, by XRD (X-ray Diffraction). A-2. Spinel Typically, the spinel exists in the grain boundary, or is formed by a reaction of magnesium oxide and aluminum oxide in the grain boundary between the grains of the AlN. The crystal system of the spinel is typically cubic, more specifically face-centered cubic. The lattice constant (lattice constant of the a-axis) of the spinel is preferably More preferably, the lattice constant is Further preferably, the lattice constant is Especially preferably, the lattice constant is In particular, the lattice constant is More particularly, the lattice constant is The above. The lattice constant (lattice constant of the a-axis) of the spinel is preferably More preferably, the lattice constant is The above. If the lattice constant of the spinel is in such a range, the volume resistivity of the substrate carrier in the high temperature region can be further increased, and the decrease in the volume resistivity of the substrate carrier in the high temperature region can be sufficiently suppressed. The content ratio of the spinel in the substrate carrier 1 is preferably 0.2% by mass or more, and further preferably 0.3% by mass or more, in terms of oxides. On the other hand, the content ratio of the spinel in the substrate carrier 1 is preferably 0.9% by mass or less, in terms of oxides. If the content ratio of the spinel in the substrate carrier is in such a range, the volume resistivity of the substrate carrier in the high temperature region can be stably increased. A-3. Titanium nitride (TiN) In one embodiment, the substrate carrier 1 further includes titanium nitride (hereinafter referred to as TiN). In other words, the substrate carrier 1 includes the TiN crystal phase in addition to the AlN crystal phase and the spinel crystal phase. Typically, the TiN exists in the grain boundary between the grains of the AlN. The content ratio of the TiN in the substrate carrier 1 is, for example, 0.01% by mass or more, and preferably 0.3% by mass or more, in terms of oxides. On the other hand, the content ratio of the TiN in the substrate carrier 1 is, for example, 1.0% by mass or less, and preferably 0.8% by mass or less, in terms of oxides. If the content ratio of the TiN in the substrate carrier is in such a range, the formation of a conductive path in the grain boundary layer is suppressed, and thus the decrease in the volume resistivity of the substrate carrier is suppressed, which is preferable. A-4. Other crystal phases The substrate carrier 1 can further include other crystal phases. The other crystal phases are crystal phases other than the AlN crystal phase, the spinel crystal phase, and the TiN crystal phase, and for example, α-alumina can be cited. The content ratio of other crystal phases in the substrate carrier 1 is, for example, 1.0 mass% or less. On the other hand, the lower limit of the content ratio of other crystal phases in the substrate carrier 1 is typically 0 mass%. If the content ratio of other crystal phases in the substrate carrier is in such a range, the decrease in the volume resistivity of the substrate carrier in the high-temperature region can be stably suppressed. A-5. Physical properties of the substrate carrier Such a substrate carrier has a relatively high volume resistivity in the high-temperature region. The volume resistivity of the substrate carrier 1 at 600°C is, for example, 1.0 x 10 9 Ω·cm or more, preferably 1.2 x 10 9 Ω·cm or more, more preferably 2.0 x 10 9 Ω·cm or more, further preferably 5.0 x 10 9 Ω·cm or more, particularly preferably 7.0 x 10 10 Ω·cm or more, particularly preferably 7.0 x 10 10 Ω·cm or more, most preferably 8.0 x 10 10 Ω·cm or more. On the other hand, the volume resistivity of the substrate carrier 1 at 600°C is, for example, 1.0 x 10 12 Ω·cm or less, and is, for example, 1.5 x 10 11 Ω·cm or less. Note that the volume resistivity of the substrate carrier at 600°C is measured, for example, in accordance with JIS C2141-1992. Further, the thermal conductivity of the substrate carrier 1 at 600°C is, for example, 20 W / m·K to 50 W / m·K. Note that the thermal conductivity of the substrate carrier at 600°C is measured, for example, in accordance with the flash method prescribed in JIS R1611:2010. The open porosity of the substrate carrier 1 is, for example, 1.0% or less. Note that the open porosity of the substrate carrier is measured, for example, in accordance with JIS R1634. The relative density of the substrate carrier 1 is, for example, 99.0% or more, preferably 99.5% or more. On the other hand, the upper limit of the relative density of the substrate carrier 1 is typically 100%. Note that the relative density of the substrate carrier is measured, for example, in accordance with JIS R1634. B. Method for manufacturing a substrate carrier Next, a method for manufacturing a substrate carrier according to one embodiment will be described. The manufacturing method of the substrate carrier plate according to one embodiment includes, in this order, a mixing step, a molding step, a pre-burning step, and a firing step. B-1. Mixing Step In the mixing step, at least the AlN raw material and the magnesium oxide raw material (hereinafter referred to as MgO raw material) are mixed, or the AlN raw material and the spinel raw material are mixed, to prepare a mixture. The AlN raw material contains AlN as a main component. The AlN raw material can contain oxygen and carbon in addition to AlN. The amount of oxygen in the AlN raw material is, for example, 0.7 to 0.9 mass%. The amount of carbon in the AlN raw material is, for example, 200 to 400 ppm. The AlN raw material is typically in a powder form. The average particle diameter D50 of the AlN raw material is, for example, 1 μm. The MgO raw material contains MgO as a main component. The MgO raw material is typically in a powder form. The average particle diameter D50 of the MgO raw material is, for example, 0.5 μm. The amount of addition of the MgO raw material is, for example, 0.1 mass part or more, preferably 0.2 mass part or more, and further preferably 0.4 mass part or more, with respect to 100 mass parts of the AlN raw material. On the other hand, the amount of addition of the MgO raw material is, for example, 1.1 mass part or less, preferably 1.0 mass part or less, and more preferably 0.9 mass part or less, with respect to 100 mass parts of the AlN raw material. In the mixing step, a titanium oxide raw material (hereinafter referred to as Ti02raw material) is further mixed in the AlN raw material and the MgO raw material (or the spinel raw material), as necessary. The Ti02raw material contains Ti02as a main component. The Ti02raw material is typically in a powder form. The average particle diameter D50 of the Ti02raw material is, for example, 0.3 μm. The amount of addition of the Ti02raw material is, for example, 0.1 mass part or more, and preferably 0.3 mass part or more, with respect to 100 mass parts of the AlN raw material. On the other hand, the amount of addition of the Ti02raw material is, for example, 1.0 mass part or less, with respect to 100 mass parts of the AlN raw material. In one embodiment, a binder is added to the AlN raw material and the MgO raw material in the mixing step. Examples of the binder include a polyvinyl acetal resin, a cellulose ether resin, a (meth)acrylic resin, and a paraffin wax. Note that the (meth)acrylic resin includes an acrylic resin and / or a methacrylic resin. The binder can be used alone or in combination. Among such binders, the (meth)acrylic resin is preferable. In the mixing step, any appropriate mixing device can be used. As the mixing device, for example, a ball mill, a bead mill, a vibration mill, a roll mixer, a blender, a homogenizer, or the like can be mentioned. Further, the mixing method can be dry mixing or wet mixing. In one embodiment, wet mixing is performed in the mixing step. In the wet mixing, any appropriate solvent can be used. As the solvent, for example, an alcohol such as isopropyl alcohol or ethanol; an aromatic hydrocarbon such as toluene or xylene can be mentioned. The environmental conditions in the mixing step are not particularly limited. Typically, the mixing step is performed at ordinary temperature (23°C) and ordinary pressure (0.1 MPa). The mixing time is arbitrarily and appropriately set. The mixing time is, for example, 1 hour to 24 hours. By the above operation, a mixture containing at least the AlN raw material and the MgO raw material (or the spinel raw material) is prepared. In the case where the mixing step is dry mixing, the mixture has a powder shape; in the case where the mixing step is wet mixing, the mixture has a slurry shape. B-2. Granulation Step In one embodiment, the method for manufacturing a substrate carrier 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. As the granulation method, for example, spray granulation, tumbling granulation, or the like can be mentioned, and spray granulation is preferable. By this, a granulated product of the mixture (hereinafter, referred to as a raw material pellet) is prepared. B-3. Molding Step Next, in the molding step, the mixture (preferably, the raw material pellet) is molded into a desired shape by any appropriate molding method. As the molding method, for example, press molding, casting molding, cold isostatic pressing (CIP) molding, or the like can be mentioned, and press molding is preferable. The pressure in the press molding is, for example, 10 kgf / cm 2 ~ 500 kgf / cm 2 . By this, a molded body having a desired shape is prepared. B-4. Sintering Step Next, in the sintering step, the molded body is sintered, typically, under vacuum or a non-oxidizing atmosphere. More specifically, after being heated from ordinary temperature (23°C) to a prescribed sintering temperature, the sintering temperature is maintained for a prescribed sintering time. Before the sintering step, a debinding step can be provided as necessary. The sintering temperature is, for example, 1600°C to 1900°C, and preferably 1650°C to 1850°C. The firing time is, for example, 0.5 hours to 100 hours. The environmental pressure in the firing step is, for example, 100 kPa to 900 kPa. As the firing method, for example, hot pressing, hot isostatic pressing (HIP) can be given, and preferably, hot pressing can be given. In the hot pressing, typically, the molded body is disposed in a hot pressing mold (for example, a carbon jig), heated to the firing temperature as described above, and pressed at a prescribed pressure. The pressure in the hot pressing is, for example, 5 MPa to 50 MPa. Subsequently, the temperature is decreased from the firing temperature to normal temperature (23°C). The rate of temperature decrease is arbitrarily and appropriately adjusted according to the amount of the MgO raw material added as described above. The rate of temperature decrease is, for example, 250°C / hr or less, preferably 150°C / hr or less, and more preferably 120°C / hr or less. If the rate of temperature decrease is the upper limit or less as such, the lattice constant of the spinel generated in the firing step can be stably adjusted to the range described above. On the other hand, the rate of temperature decrease is, for example, 50°C / hr or more, and preferably 80°C / hr or more. In the firing step as such, the raw materials described above are sintered and reacted to generate a composite sintered body containing AlN and spinel. By the above operation, a substrate carrier plate having a desired shape is prepared. Typically, the substrate carrier plate is composed of the composite sintered body. C. Details of the Ceramic Submount The ceramic submount 100 can be composed only of the substrate carrier plate 1, or can have other components in addition to the substrate carrier plate 1. As shown in FIG. 1, the ceramic submount 100 has the substrate carrier plate 1. Figure 1 As shown in FIG. 1, the ceramic submount 100 has the substrate carrier plate 1. The internal electrode 2 is implanted in the substrate carrier plate 1. As for implanting the internal electrode 2 in the substrate carrier plate 1, for example, in the molding step described above, the mixture is molded in a state where the internal electrode 2 is implanted in a desired position with respect to the mixture, and then, the pre-firing step and the firing step are performed. The internal electrode 2 exists at a position apart from the mounting surface la by a prescribed interval in the thickness direction of the substrate carrier plate 1. The interval between the mounting surface la and the internal electrode 2 in the thickness direction of the substrate carrier plate 1 is, for example, 0.1 mm to 3.0 mm. As the internal electrode 2, for example, an ESC electrode, an RF electrode, and a resistance heating element can be given. In the illustrated example, in the ceramic submount 100, the ESC electrode 21 is provided as the internal electrode 2. In the case where the internal electrode 2 includes the ESC electrode 21, when a voltage is applied to the ESC electrode 21 in a state where the semiconductor substrate 8 is placed on the placement surface la, the ESC electrode 21 has either one of positive and negative charges, and the other one of the positive and negative charges existing in the semiconductor substrate 8 moves to the placement surface la side in the semiconductor substrate 8. Thus, a Coulomb force is generated between the semiconductor substrate 8 and the ESC electrode 21, and the semiconductor substrate 8 is held by the substrate placement plate 1. Although not shown, the ceramic base 100 can include a plurality of ESC electrodes 21. The plurality of ESC electrodes 21 exist separately from each other in a direction orthogonal to the thickness direction of the substrate placement plate 1 in a state of being embedded in the substrate placement plate 1. In the case where the ceramic base 100 includes a plurality of ESC electrodes 21, when a voltage is applied to the plurality of ESC electrodes 21, it is possible to make some of the plurality of ESC electrodes 21 positive and the rest of the plurality of ESC electrodes 21 negative. Thus, it is possible to hold the semiconductor substrate 8 in multiple sections on the substrate placement plate 1. In one embodiment, the internal electrode 2 functions as an RF electrode (i.e., a high-frequency electrode) for plasma processing. In the illustrated example, the ESC electrode 21 also functions as an RF electrode. That is, the ESC electrode 21 preferably functions as an RF / ESC electrode. As plasma processing, for example, film formation processing and etching processing can be given. In the case where such plasma processing is performed on the semiconductor substrate 8 on the placement surface la, an upper electrode is arranged on the side opposite to the RF electrode with respect to the semiconductor substrate 8. If high-frequency power is supplied to the RF electrode in this state, a processing gas is excited to generate plasma in a space between the substrate placement plate 1 and the upper electrode. The semiconductor substrate 8 is subjected to plasma processing by the use of this plasma. The ESC electrode 21 can have any appropriate shape. Typically, the ESC electrode 21 has a plate shape. In one embodiment, the ESC electrode 21 has a shape similar to the outer shape of the substrate placement plate 1 as viewed in the thickness direction of the substrate placement plate 1. In the illustrated example, the center of the ESC electrode 21 and the center of the substrate placement plate 1 substantially coincide as viewed in the thickness direction of the substrate placement plate 1. The thickness of the ESC electrode 21 is, for example, 0.1 mm to 1.0 mm. The ESC electrode 21 is composed of any appropriate conductive material. As the conductive material, typically, a metal having a relatively high melting point can be given. As such a metal, for example, tantalum (Ta), tungsten (W), molybdenum (Mo), platinum (Pt), rhenium (Re), hafnium (Hf), and alloys thereof can be given. Such a metal can be used alone or in combination. In the illustrated example, the first power supply rod 6 is electrically connected to the ESC electrode 21. The voltage (or high-frequency power) described above can be applied to the ESC electrode 21 via the first power supply rod 6. Typically, the first power supply rod 6 is composed of the same metal as the ESC electrode 21. In one embodiment, the ceramic base 100 is provided with a resistance heat generating body 22 as an internal electrode 2. In the illustrated example, the resistance heat generating body 22 is located on the side of the substrate mounting board 1 opposite the mounting surface la with respect to the ESC electrode 21. To implant the resistance heat generating body 22 in the substrate mounting board 1, for example, in the molding process described above, the mixture is molded in a state in which the resistance heat generating body 22 is implanted in the desired position with respect to the mixture, after which the firing process is performed. The resistance heat generating body 22 is configured to generate heat when a voltage is applied. The resistance heat generating body 22 has an arbitrary appropriate shape. As the shape of the resistance heat generating body 22, for example, a coil shape, a zigzag shape, a mesh shape can be cited. In the illustrated example, the resistance heat generating body 22 has a coil shape. The resistance heat generating body 22 can be formed using printing. The resistance heat generating body 22 is composed of an arbitrary appropriate conductive material. As the conductive material, typically, a metal having a relatively high melting point can be cited. As such a conductive material, for example, tantalum (Ta), tungsten (W), molybdenum (Mo), tungsten carbide (WC), titanium nitride (TiN), platinum (Pt), rhenium (Re), hafnium (Hf), and alloys thereof can be cited. Such a conductive material can be used alone or in combination. Among the conductive materials, W, Mo, a W-Mo alloy, WC, and a WC-TiN alloy can be cited as preferable. In the illustrated example, the second power supply rod 7 is electrically connected to the resistance heat generating body 22. The voltage described above can be applied to the resistance heat generating body 22 via the second power supply rod 7. Typically, the second power supply rod 7 is composed of the same conductive material as the resistance heat generating body 22. The ceramic base 100 can further be provided with a ceramic shaft 5. The ceramic shaft 5 is capable of supporting the substrate mounting board 1. The ceramic shaft 5 is connected to the surface of the substrate mounting board 1 on the side opposite the mounting surface la. The ceramic shaft 5 has an arbitrary appropriate shape. In one embodiment, the ceramic shaft 5 has a cylindrical shape extending in the thickness direction of the substrate mounting board 1. In the illustrated example, the axis of the ceramic shaft 5 and the center of the substrate mounting board 1 substantially coincide when viewed in the thickness direction of the substrate mounting board 1. In addition, the first power supply rod 6 passes through the internal space of the ceramic shaft 5 to be connected to the internal electrode 2. In addition, the second power supply rod 7 passes through the internal space of the ceramic shaft 5 to be connected to the resistance heat generating body 22. The ceramic shaft 5 is composed of any appropriate ceramic material. The ceramic shaft 5 is, for example, made of aluminum nitride, and is preferably composed of the same material as the substrate mounting plate 1. Such a ceramic base can be applied to any appropriate industrial product. As the use of the ceramic base, for example, a base, a ceramic heater, an electrostatic chuck, and the like can be cited. In such a ceramic base 100, since the substrate mounting plate 1 contains spinel having a lattice constant in the above range, the volume resistivity of the substrate mounting plate in a high temperature region of, for example, 600°C or higher can be improved. Therefore, in plasma processing such as film formation processing, the current leakage from the internal electrode 2 can be significantly suppressed, and thus the electrostatic chuck function can be sufficiently exhibited with respect to the semiconductor substrate 8. Examples Hereinafter, the present application will be specifically described using examples and comparative examples, but the present application is not limited by these examples. The measuring method of each property is as follows. (1) Measurement of Volume Resistivity of Substrate Mounting Plate The volume resistivity of the substrate mounting plate produced in the examples and comparative examples was measured at 600°C under a vacuum atmosphere in accordance with JIS C2141-1992. More specifically, a test piece having a circular plate shape 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, the guard electrode, and the application electrode were each composed 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 after 1 minute from the voltage application was read. Based on the current value, the volume resistivity was calculated, and the evaluation was performed in accordance with the following criteria. The results are shown in Table 1. O: The volume resistivity of the substrate mounting plate at 600°C was 1 x 10 9 Ω·cm or more X: The volume resistivity of the substrate mounting plate at 600°C was less than 1 x 10 9 Ω·cm (2) Identification of Crystal Phases Contained in Substrate Mounting Plate and Calculation of Contained Proportion of Each Crystal Phase The substrate mounting plate produced in the examples and comparative examples was pulverized using a mortar, and silicon (Si) powder was added as an internal standard sample and mixed. The resulting mixed powder was analyzed using an X-ray diffraction (XRD) device, and the crystal phases of the substrate mounting plate were identified. The results are shown in Table 1. Note that the measurement conditions were set as follows: Cu Kα, 40 kV, 40 mA, 2θ = 20 to 80°, and a tube-enclosed X-ray diffractometer (D8-ADVANCE manufactured by Bruker AXS) was used. The step width of the measurement was set to 0.02°. In addition, the proportions of each crystal phase contained in the substrate carrier plate were calculated using XRD. The results are shown in Table 1. (3) Calculation of the lattice constant of spinel contained in the substrate carrier plate The lattice constant of spinel contained in the substrate carrier plates produced in the examples and comparative examples was calculated using the WPPD method (powder pattern fitting method) using software (TOPAS manufactured by Bruker AXS). The results are shown in Table 1. <<Example 1>> An AlN raw material powder (average particle diameter D50: 1.2 μm, oxygen content: 0.8 mass%), a MgO raw material powder (average particle diameter D50: 0.5 μm), and a TiO2raw material powder (average particle diameter D50: 0.3 μm) were put into a ball mill in the prescription given in Table 1, and further, an acrylic resin (binder) and isopropyl alcohol (IPA) were put into the ball mill, and wet mixing was performed for 2 hours. Next, the obtained slurry was dry granulated using a spray granulation device, and a raw material granule was obtained. The particle diameter of the raw material granule was 80 μm. Next, the raw material granule was subjected to uniaxial press molding, and a molded body having a round plate shape was obtained. The pressure in the uniaxial press molding was 100 kgf / cm 2 . Next, the molded body was subjected to a debinding process and firing using a hot press method. More specifically, the molded body was fired at 1800°C for 2 hours under a nitrogen atmosphere, and was cooled at 100°C / hr. Thus, a substrate carrier plate was obtained. <<Examples 2 to 6, Comparative Examples 1 and 2>> The addition amounts of the AlN raw material powder, the MgO raw material powder, and the TiO2raw material powder were changed to the prescription given in Table 1, the cooling rate was changed as shown in Table 1, and otherwise, a substrate carrier plate was obtained in the same manner as in Example 1. Table 1 [Assessment] As is apparent from Table 1, in a substrate carrier plate in which the proportion of aluminum nitride (AlN) is 95.0% or more, if spinel having a lattice constant of is present at the grain boundaries, the volume resistivity of the substrate carrier plate at 600°C can be improved. Industrial Applicability The ceramic base according to the embodiment of the present application can be used for various industrial products, and in particular, can be preferably used for a ceramic base of a manufacturing apparatus for semiconductor devices.

Claims

1. A ceramic base having a substrate mounting plate containing aluminum nitride and spinel, the ceramic base is characterized in that, the aluminum nitride in the substrate mounting plate has a content ratio of 95.0 mass% or more and 99.9 mass% or less, the spinel in the substrate mounting plate has a content ratio of 0.1 mass% or more and 1.0 mass% or less in terms of oxides, the aluminum nitride has a polycrystalline structure, the spinel is located at grain boundaries between the aluminum nitride, The spinel has a lattice constant of The above and The following.

2. The ceramic base according to claim 1, characterized in that, the substrate mounting plate further contains titanium nitride.

3. The ceramic base according to claim 2, characterized in that, the titanium nitride in the substrate mounting plate has a content ratio of 0.01 mass% or more and 1.0 mass% or less in terms of oxides.

4. The ceramic base according to any one of claims 1 to 3, characterized in that, The substrate has a volume resistivity of 1.0 x 10 9 Ω-cm or more at 600°C.

5. The ceramic base according to any one of claims 1 to 3, characterized in that, the α-alumina in the substrate mounting plate has a content ratio of 1.0 mass% or less.

6. The ceramic base according to any one of claims 1 to 3, characterized in that, the ceramic base further has an internal electrode implanted in the substrate mounting plate.

7. The ceramic base according to claim 6, characterized in that, the internal electrode further has an electric resistance heating element.

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