Ceramic susceptor

Abstract

To provide a ceramic susceptor which can be used in a GHz-band semiconductor manufacturing process, and can reduce stress and strain of the ceramic susceptor, a semiconductor substrate support member, etc., even if large amount of heat is transferred into a substrate.SOLUTION: A ceramic susceptor 100 is provided, comprising a base material 10 which has a mounting surface 18 on which a semiconductor substrate support member is mounted, wherein the base material 10 is formed of a ceramic sintered body consisting principally of SiC, wherein the ceramic sintered compact has a dielectric dissipation factor tanδ of 0.45 or less at 0.2 GHz and a dielectric dissipation factor tanδ of 0.70 or less at 0.5 GHz.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] With the recent trend towards higher power in semiconductor processes, there is an increasing demand for susceptors that support semiconductor substrates. Therefore, the replacement of susceptors that were previously made of Al alloys with SiC ceramics is being considered. This allows the thermal expansion of the base to be kept small compared to that of Al alloy susceptors, even if a large amount of heat flows into the substrate during the process, and therefore reduces stress and distortion with heaters and electrostatic chucks, which are mainly made of sintered ceramics and are fixed onto the susceptor, thereby stabilizing the processing of the substrate.

[0003] Patent Document 1 discloses a technology for controlling the amount of boron nitride in the raw material powder from which a silicon carbide sintered body is produced by sintering, thereby setting the amount of boron nitride in the silicon carbide raw material powder to 1.0% by weight or more, and thereby controlling the dielectric tangent of the sintered body to a low value. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-131298 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when GHz-band ECR plasma or the like is used as a high-density plasma source for such high-power processes, the SiC susceptor itself generates heat because SiC itself is also an electromagnetic wave absorber in the GHz band, and this has an impact on the temperature distribution of the electrostatic chuck, heater, and even the substrate being processed, which cannot be ignored.

[0006] In Patent Document 1, the dielectric loss tangent of the sintered body is measured only at 13.56 MHz, so it is unclear whether it can be used in processes in the GHz band. Therefore, there has been a demand for a ceramic susceptor for a semiconductor substrate support member that can suppress the effect on the temperature distribution even in such a high-power process.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a ceramic susceptor that can be used in semiconductor manufacturing processes in the GHz band and that can reduce stress and distortion between the ceramic susceptor and a semiconductor substrate support member, etc., even if a large amount of heat flows into the substrate. [Means for solving the problem]

[0008] (1) In order to achieve the above object, the present invention provides the following means: That is, a ceramic susceptor according to an application example of the present invention is a ceramic susceptor having a mounting surface for mounting a semiconductor substrate support member thereon, and including a base material formed of a ceramic sintered body containing SiC as a main component, the ceramic sintered body having a dielectric loss tangent tanδ of 0.45 or less at 0.2 GHz and a dielectric loss tangent tanδ of 0.70 or less at 0.5 GHz.

[0009] This makes it possible to improve the dielectric properties of the ceramic susceptor, and to suppress heat generation from the ceramic susceptor itself.

[0010] (2) In the ceramic susceptor of the application example of (1) above, the ceramic sintered body has a volume resistivity of 10 at 20° C. 7 It is characterized by a resistivity of less than Ωcm.

[0011] This makes it possible to suppress an increase in impedance of the ceramic susceptor and reduce the effect on the plasma process, thereby making it possible to further stabilize the temperature distribution of the semiconductor support member and the substrate.

[0012] (3) In the ceramic susceptor according to the application example of (1) or (2) above, the ceramic sintered body has a dielectric tangent tanδ of 0.40 or more at 0.5 GHz and a volume resistivity of 10 or more at 20° C. 5 It is characterized by a resistivity of less than Ωcm.

[0013] This achieves both low tan δ and low volume resistivity, further improving the high frequency characteristics of the ceramic susceptor.

[0014] (4) In the ceramic susceptor according to any one of the application examples of (1) to (3) above, the ceramic sintered body contains Al in an amount of 0.2 mol % or more and 1.1 mol % or less.

[0015] This makes it possible to specifically configure a ceramic susceptor having a dielectric tangent tan δ and volume resistivity within the above ranges.

[0016] (5) In addition, the ceramic susceptor according to any one of the application examples of (1) to (4) above is characterized in that it further comprises a high-frequency electrode embedded in the base material.

[0017] This allows the ceramic susceptor to function as an RF application base that can be used in a high frequency environment.

[0018] (6) In the ceramic susceptor according to any one of the application examples of (1) to (5) above, the substrate is characterized in that a medium flow path is provided therein.

[0019] This allows the ceramic susceptor to have a heating and cooling function by a medium, thereby expanding the functionality of the ceramic susceptor. Effect of the Invention

[0020] According to the ceramic susceptor of the present invention, the dielectric properties of the ceramic susceptor can be improved, and as a result, heat generation from the ceramic susceptor itself can be suppressed. [Brief description of the drawings]

[0021] [Figure 1] 1(a) is a schematic cross-sectional view showing an example of a ceramic susceptor according to an embodiment of the present invention, and FIG. 1(b) is a schematic cross-sectional view showing an example of use of the ceramic susceptor of FIG. [Diagram 2] FIG. 11 is a schematic cross-sectional view showing a modified example of a ceramic susceptor according to an embodiment of the present invention. [Diagram 3] FIG. 11 is a schematic cross-sectional view showing a modified example of a ceramic susceptor according to an embodiment of the present invention. [Figure 4] FIG. 2 is a schematic diagram showing an example of the upper surface of a ceramic susceptor according to an embodiment of the present invention. [Diagram 5] FIG. 11 is a schematic cross-sectional view showing a modified example of a ceramic susceptor according to an embodiment of the present invention. [Figure 6] 10A and 10B are schematic diagrams showing modified examples of the upper surface of the ceramic susceptor according to the embodiment of the present invention. [Figure 7] 3(a) to 3(d) are schematic cross-sectional views each showing one stage of a manufacturing method for a ceramic susceptor. [Figure 8] 3(a) to 3(d) are schematic cross-sectional views each showing one stage of a manufacturing method for a ceramic susceptor. [Figure 9] 2 is a schematic cross-sectional view showing one stage of a method for manufacturing a ceramic susceptor. FIG. [Figure 10] 1 is a table showing the production conditions and the results of various tests of Examples and Comparative Examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Next, an embodiment of the present invention will be described with reference to the drawings. In order to facilitate understanding of the description, the same reference numerals are used for the same components in each drawing, and duplicated descriptions will be omitted. In the configuration diagrams, the size of each component is conceptually shown, and does not necessarily represent the actual dimensional ratio.

[0023] [Embodiment] (Configuration of ceramic susceptor) A ceramic susceptor according to an embodiment of the present invention will be described with reference to Figs. 1(a) and (b). Fig. 1(a) is a schematic cross-sectional view showing an example of a ceramic susceptor according to an embodiment of the present invention. Fig. 1(b) is a schematic cross-sectional view showing an example of use of the ceramic susceptor of Fig. 1(a). A ceramic susceptor 100 according to an embodiment of the present invention includes a base 10 having a mounting surface 18 on which a semiconductor substrate support member is placed. The mounting surface 18 is provided on an upper surface 12 of the base 10. The semiconductor substrate support member is, for example, an electrostatic chuck, a vacuum chuck, a heater, or the like.

[0024] The substrate 10 is formed of a ceramic sintered body mainly composed of SiC. The ceramic sintered body mainly composed of SiC means that the concentration of SiC in the ceramic sintered body is 50 wt% or more. The substrate 10 may have various shapes such as a substantially circular plate, a polygonal plate, or an elliptical plate. The substrate 10 is flat except for through holes formed on the mounting surface 12.

[0025] The ceramic sintered body forming the substrate 10 has a dielectric loss tangent tanδ of 0.45 or less at 0.2 GHz and a dielectric loss tangent tanδ of 0.70 or less at 0.5 GHz. This improves the dielectric characteristics of the ceramic susceptor 100 in the GHz band. As a result, when the ceramic susceptor 100 is used in a process in the GHz band, the absorption of high-frequency power can be suppressed, and thus the heat generation of the ceramic susceptor 100 itself can be suppressed. The dielectric loss tangent tanδ is the ratio ε'' / ε' of the dielectric constant ε' of the real part of the complex dielectric constant ε to the dielectric constant ε'' of the imaginary part of the complex dielectric constant ε. The GHz band refers to a band of 0.1 GHz or more.

[0026] The ceramic sintered body preferably has a dielectric loss tangent tan δ of 0.40 or more at 0.5 GHz, which allows both low tan δ and a low volume resistivity, which will be described later, to be achieved at the same time, thereby further improving the high frequency characteristics of the ceramic susceptor 100.

[0027] The ceramic sintered body preferably has a dielectric loss tangent tan δ of 0.2 or more at 0.2 GHz, and preferably has a dielectric loss tangent tan δ of 0.3 or more and 0.92 or less at 1.0 GHz.

[0028] The volume resistivity of sintered ceramics is 10 at 20°C. 7 It is preferable that the resistance is less than 10 Ωcm at 20°C. 5 It is more preferable that the dielectric constant is smaller than Ωcm. This can suppress the increase in impedance of the ceramic susceptor 100, and reduce the influence on the plasma process. As a result, the temperature distribution of the semiconductor support member and the substrate can be further stabilized. In general, the dielectric tangent tan δ tends to increase as the volume resistivity decreases. Therefore, by setting the volume resistivity in the above range, both low tan δ and low volume resistivity can be achieved, and the high frequency characteristics of the ceramic susceptor can be further improved. The lower limit of the volume resistivity of the ceramic sintered body does not need to be particularly limited, but may be, for example, 0.5 Ωcm or more at 20°C, or 10 Ωcm or more at 20°C.

[0029] The surface resistivity of a sintered ceramic body is 10 at 20°C. 7 It is preferable that the resistance is 10Ω / □ or less at 20℃. 5 It is more preferable that the surface resistivity is Ω / □ or less. Because the high frequency current mainly flows through the surface of the base due to the skin effect, a small surface resistivity can stabilize the plasma process. The lower limit of the surface resistivity of the ceramic sintered body does not need to be particularly limited, but may be, for example, 0.5 Ω / □ or more at 20°C, or 10 Ω / □ or more at 20°C.

[0030] The ceramic sintered body preferably contains Al in an amount of 0.2 mol% or more and 1.1 mol% or less. This makes it possible to specifically configure a ceramic susceptor 100 having a dielectric tangent tanδ, volume resistivity, and surface resistivity in the above ranges. Here, mol% is the number of moles of Al atoms contained in the ceramic sintered body divided by the number of moles of all atoms constituting the ceramic sintered body. The ceramic sintered body preferably contains B in an amount of 0.04 mol% or more and 0.19 mol% or less. These atoms are preferably added in the form of compounds such as Al2O3, AlN, B4C, and BN.

[0031] Fig. 2 is a schematic cross-sectional view showing a modified example of a ceramic susceptor according to an embodiment of the present invention. As shown in Fig. 2, the ceramic susceptor 100 preferably further includes a high-frequency electrode 20 embedded in the base material 10. This allows the ceramic susceptor 100 to function as an RF application base that can be used in a high-frequency environment. The high-frequency electrode 20 is embedded in a shape according to the design of the ceramic susceptor 100. The high-frequency electrode 20 is preferably made of W, Mo, or an alloy mainly composed of these.

[0032] Fig. 3 is a schematic cross-sectional view showing a modified example of a ceramic susceptor according to an embodiment of the present invention. Fig. 4 is a schematic view showing an example of the upper surface of a ceramic susceptor according to an embodiment of the present invention. Fig. 3 shows a cross section taken along line AA in Fig. 4.

[0033] As shown in Figures 3 and 4, the substrate 10 is preferably provided with a media flow path 30 therein. The media flow path 30 is formed, for example, in a tubular shape. The width of the media flow path 30 is preferably 1 mm or more and 60 mm or less. The cross-sectional shape of the media flow path 30 is not limited to a rectangle, and may be any shape that can be manufactured, such as a circle, an ellipse, a semicircle, or a stepped shape.

[0034] It is preferable that the medium flow path 30 is a type that circulates a low-temperature chiller. Therefore, it is preferable that the medium flow path 30 is formed with an inlet for introducing the chiller and an outlet for discharging the chiller.

[0035] When the media flow path 30 is formed in the substrate 10, it is preferable that the substrate 10 is integrally formed of a ceramic sintered body. The substrate 10 is integrally formed of a ceramic sintered body means that the ceramic sintered body forming the ceiling of the media flow path 30 and the ceramic sintered body forming the bottom of the media flow path 30 are directly bonded together using a bonding material containing ceramics or without using a bonding material. This increases the mechanical strength of the substrate 10.

[0036] The medium flow path 30 preferably has a substantially annular shape centered at the center 16 of the substrate 10 when viewed from the top surface 12 of the substrate 10. This allows the temperature distribution in the radial direction of the substrate 10 surface to be adjusted. A substantially annular shape includes a shape in which some of the arcs of the annular shape are not connected as in FIG. 4, and a normal annular shape. The dotted line in FIG. 4 indicates the shape of the medium flow path 30 when the substrate 10 is viewed from the top surface 12. Structures other than the medium flow path 30 that are viewed from the top surface 12 are omitted. These can be designed in a variety of ways to suit the cooling specifications of the substrate 10.

[0037] Fig. 5 is a schematic cross-sectional view showing a modified example of a ceramic susceptor according to an embodiment of the present invention. Fig. 6 is a schematic view showing a modified example of the upper surface of a ceramic susceptor according to an embodiment of the present invention. Fig. 5 shows a cross section taken along line BB in Fig. 6. Note that in Figs. 5 and 6, the high frequency electrode 20 is embedded and a medium flow path 30 is provided. In such a case, it is preferable that the medium flow path 30 is located closer to the lower surface 14 of the base material 10 than the layer in which the high frequency electrode 20 is embedded, in a vertical cross section of the base material 10.

[0038] As shown in FIG. 5 and FIG. 6, the media flow paths 30 are preferably arranged concentrically around the center 16 of the substrate 10 in a shape seen through the substrate 10 from the top surface 12. This allows fine adjustment of the radial temperature distribution on the surface of the substrate 10. The substantially annular media flow paths 30 arranged concentrically may be double as shown in FIG. 5 and FIG. 6, or may be triple or more. The substantially annular media flow paths 30 arranged concentrically may be connected inside the substrate 10 as shown in FIG. 6, or each may have an inlet and an outlet. In addition, the width of the gap between adjacent media flow paths 30 (the width of the substrate 10 present in the gap between adjacent media flow paths 30) is preferably 2 mm or more. In addition, the width of the gap between adjacent media flow paths 30 is preferably 25% or more of the width of the media flow path 30. This allows the strength of the substrate 10 to be maintained even if the media flow path 30 is formed inside the substrate 10.

[0039] The media flow passage 30 may include a linear shape. Also, a substantially annular media flow passage 30 may be combined with a linear media flow passage 30. The substantially annular media flow passage 30 and the linear media flow passage 30 may be connected to each other.

[0040] When the high frequency electrode 20 is embedded in the base material 10, the ceramic susceptor 100 may be provided with terminals 50, 51 and terminal holes 52 as necessary.

[0041] [Method of manufacturing ceramic susceptors] Next, a method for manufacturing a ceramic susceptor according to an embodiment of the present invention will be described. The ceramic susceptor according to an embodiment of the present invention is manufactured, for example, by a molded body hot pressing method described below. The method for manufacturing a ceramic susceptor is not limited to this method, and may be, for example, a powder hot pressing method or a conventional green sheet lamination method. The powder hot pressing method is a method in which ceramic raw material powder and a predetermined heating resistor and electrode are alternately stacked to embed the heating resistor and electrodes inside the ceramic, and then the resulting product is uniaxial hot press sintered.

[0042] The method for manufacturing a ceramic susceptor according to an embodiment of the present invention by hot pressing a molded body includes a ceramic molded body forming step, a ceramic degreased body preparing step, a laminate forming step, a laminate firing step, and a substrate processing step.

[0043] In the ceramic molded body forming process, one or more ceramic molded bodies are formed from ceramic raw material powder mainly composed of, for example, SiC (silicon carbide). Sintering aids may be added as necessary. For example, additives such as sintering aids B4C and C-containing additives, binders, plasticizers, dispersants, etc. are appropriately added to and mixed with SiC ceramic raw material powder to prepare a slurry, and the granulated powder is granulated by a spray drying method or the like. The granulated powder is then pressure-molded to form a plurality of ceramic molded bodies.

[0044] The raw SiC ceramic powder used as the raw material is made from powder produced by the Acheson method or CVD method.

[0045] The ceramic raw material powder is preferably of high purity, preferably 99% or more, more preferably 99.9% or more, and preferably has an average particle size of 0.1 μm to 1.0 μm.

[0046] The mixing method may be either wet or dry, and a mixer such as a ball mill or a vibration mill may be used. As a molding method, a known method such as uniaxial pressing or cold isostatic pressing (CIP) may be used. The method of forming the ceramic molded body is not limited to pressing, and may be, for example, green sheet lamination or casting, and the ceramic molded body can be manufactured by appropriately degreasing or further calcining the material.

[0047] After molding, the ceramic molded body may be machined to adjust the shape of the molded body. When a high-frequency electrode is embedded, grooves may be formed on one or both sides of the ceramic molded body (the joint surface with another ceramic molded body) to match the shapes of the high-frequency electrode, vias, wiring, etc. The machining may be performed after degreasing.

[0048] In the ceramic degreased body preparation step, one or more ceramic molded bodies are degreased at a predetermined temperature or higher for a predetermined time or longer to prepare one or more ceramic degreased bodies.

[0049] The ceramic molded body is heat-treated at a temperature of, for example, 500°C to 900°C to become a ceramic degreased body. The degreasing time is preferably 1 hour to 120 hours. For degreasing, an atmospheric furnace or a nitrogen atmosphere furnace can be used, but an atmospheric furnace is preferred to remove organic components of the binder.

[0050] In the laminate formation step, if necessary, a high frequency electrode, via material, and wiring are prepared, and these are combined with a plurality of ceramic degreased bodies to form a laminate formed in a flat plate shape. Fig. 7(a) to (d) are schematic cross-sectional views each showing one stage of the manufacturing process of a ceramic susceptor. Fig. 7(a) shows a cross-section of a ceramic degreased body 101, the upper surface of which is a mounting surface, a high frequency electrode 20, and a ceramic degreased body 102 in which a recess in which the high frequency electrode 20 is to be placed is formed. Fig. 7(b) shows a single laminate 110 formed by combining the ceramic degreased body 101, the high frequency electrode 20, and the ceramic degreased body 102. In Fig. 7, the laminate 110 is produced using two ceramic degreased bodies, but the number of ceramic degreased bodies may be one or three or more depending on the design of the ceramic susceptor. If the high frequency electrode 20 is not embedded, the laminate formation step may be omitted.

[0051] The high frequency electrode 20, via material, and wiring are formed by foil, thin plate, wire, mesh, or porous body of these materials such as molybdenum or tungsten, or by filling with paste or printing. The high frequency electrode 20 is prepared by processing into a shape according to the design of the ceramic susceptor 100. The shape of the high frequency electrode 20 can be various shapes according to the design. In addition, various materials such as molybdenum and tungsten can be used.

[0052] In the laminate firing step, the laminate 110 thus formed is uniaxially pressurized and fired in the lamination direction to form a substrate. Among the firing conditions, the pressure is preferably 4 MPa or more. The firing temperature is preferably 2000°C or more and 2200°C or less. The firing time is preferably 1 hour or more and 12 hours or less, and more preferably 1 hour or more and 5 hours or less. The firing atmosphere is, for example, a nitrogen or inert gas atmosphere, but may also be a vacuum atmosphere. Also, the inert gas atmosphere may be changed after the vacuum atmosphere. As a result, one or more ceramic degreased bodies are sintered in each laminate to become ceramic sintered bodies, which are integrated to obtain a substrate. FIG. 7(c) shows a cross section of the substrate before substrate processing.

[0053] In the substrate processing step, the outer shape of the substrate is processed. If necessary, terminal holes are drilled at predetermined positions on the underside to connect terminals. The terminals are then connected to the terminal holes using brazing material or the like. Ni or the like can be used for the terminals. Au brazing material or the like can also be used for the brazing material. Figure 7(d) shows a cross section of the substrate with terminals connected.

[0054] A ceramic calcined body preparation step may be provided between the ceramic degreased body preparation step and the laminate formation step. When the ceramic calcined body preparation step is provided, the ceramic degreased body is calcined at a predetermined temperature to prepare a ceramic calcined body. This allows the dimensional accuracy of the ceramic susceptor to be improved. The calcination temperature is preferably 1200°C or higher and 1900°C or lower. The calcination time is preferably 0.5 hours or higher and 12 hours or lower. The calcination atmosphere is preferably a nitrogen or inert gas atmosphere, but may be a vacuum atmosphere or the like. When the calcined body preparation step is provided, mechanical processing may be performed after the calcined body preparation step.

[0055] In this manner, it is possible to manufacture a ceramic susceptor having an electrode embedded therein that can suppress heat generation from the ceramic susceptor itself.

[0056] [Modification of the method for manufacturing a ceramic susceptor] Next, a modified example of the method for manufacturing a ceramic susceptor according to the present invention will be described. The method for manufacturing a ceramic susceptor having a media flow path according to the embodiment of the present invention by a molded body hot pressing method includes a ceramic molded body forming step, a ceramic degreased body fabricating step, a laminate forming step, a laminate firing step, a substrate precursor processing step, a substrate precursor bonding step, and a substrate processing step. The ceramic molded body forming step, the ceramic degreased body fabricating step, and the substrate processing step are the same as those described above, and therefore will not be described.

[0057] In the laminate formation step, if necessary, the high frequency electrode 20, via material, and wiring are prepared, and these are combined with a plurality of ceramic degreased bodies to form one or a plurality of laminates formed in a flat plate shape. Figs. 8(a)-(d) and 9 are schematic cross-sectional views each showing one stage of the manufacturing process of a ceramic susceptor. Fig. 8(a) shows a cross-section of a ceramic degreased body 101, the upper surface of which serves as a mounting surface, a high frequency electrode 20, a ceramic degreased body 102, the lower surface of which serves as a ceiling of a media flow path, and a ceramic degreased body 103, the lower surface of which has a groove 105, which serves as a part of the media flow path. Fig. 8(b) shows a single laminate 110 formed by combining the ceramic degreased body 101, the high frequency electrode 20, and the ceramic degreased body 102. Also, a single laminate 110 is formed only from the ceramic degreased body 103. The laminate 110 may be made of a single ceramic degreased body.

[0058] In the laminate firing step, the formed laminate is uniaxially pressurized and fired in the stacking direction to form one or more substrate precursors. The firing conditions are the same as above. The substrate precursors include, for example, a substrate precursor in which an electrode is embedded, a substrate precursor that serves as a cover for a media flow path, and a substrate precursor in which a part of a media flow path is formed.

[0059] In the substrate precursor processing step, one or more substrate precursors are each subjected to the necessary processing. For example, a groove that will become a media flow path after bonding is formed. FIG. 8(c) shows a cross section of a substrate precursor 122 having a groove 105 that will become a media flow path after bonding. In FIG. 8, the groove 105 is covered with another substrate precursor 121 to form a media flow path, but the media flow path may also be formed by combining grooves formed in two substrate precursors. With this method, media flow paths of various shapes can be formed.

[0060] In the substrate precursor bonding process, multiple substrate precursors are bonded to produce a substrate. The bonding can be performed using either a bonding method that uses a bonding material or a bonding method that does not use a bonding material. Figure 8(d) shows the substrate after bonding.

[0061] First, a bonding method using a bonding material will be described. First, a bonding material is prepared and applied to at least one of the end faces of the substrate precursor on the bonding side. The end face of the substrate precursor on the bonding side is preferably polished to a surface roughness Ra of 1.6 μm or less, more preferably 0.4 μm or less. The thickness of the applied bonding material is preferably 5 μm or more and 30 μm or less.

[0062] Next, a plurality of base precursors are arranged and heated while being pressed in a direction perpendicular to the substrate mounting surface. The pressure applied as a bonding condition is preferably 5 kPa or more. The heating temperature is preferably 1500°C or more and 1800°C or less. The heating time is preferably 0.5 hours or more and 5 hours or less. The heating atmosphere is, for example, a nitrogen or inert gas atmosphere, but may also be a vacuum atmosphere. This allows the plurality of base precursors to be bonded.

[0063] The bonding material may be any material capable of bonding the substrate precursors together. For example, it may be a paste of mixed powder containing at least B4C powder in SiC powder, which is the same main component as the substrate precursor. It may also be a paste containing 90 wt% or more of SiC and, if necessary, containing Si or B to adjust the temperature at which it becomes molten during bonding.

[0064] Next, a bonding method without using a bonding material will be described. First, a plurality of base material precursors are arranged. The end faces of the base material precursors on the bonding side are preferably polished to a surface roughness Ra of 0.1 μm or less. Next, the base material precursors are heated while being pressed in a direction perpendicular to the substrate mounting surface. Among the bonding conditions, the pressure is preferably 1 MPa or more. The heating temperature is preferably 1800° C. or more and 2000° C. or less. The heating time is preferably 0.5 hours or more and 6 hours or less. The heating atmosphere is, for example, a nitrogen or inert gas atmosphere, but may also be a vacuum atmosphere. This allows a plurality of base material precursors to be bonded.

[0065] In the above-mentioned method, the substrate precursor is formed from a ceramic sintered body and bonded to form the substrate, but the substrate precursor may be formed from a ceramic calcined body and bonded and sintered to form the substrate. In addition, when the structure of the media flow path is simple, the substrate can be produced by processing a ceramic degreased body, laminating and sintering it. When the structure of the media flow path is complex, when a flow path communicating with the outside is provided to the media flow path, or when the dimensional accuracy of the media flow path is to be increased, the method of bonding ceramic sintered bodies is preferable.

[0066] In this manner, a ceramic susceptor having embedded electrodes capable of suppressing heat generation from the ceramic susceptor itself and having medium flow paths formed therein can be manufactured.

[0067] [Examples and Comparative Examples] Example 1 Example 1 is an example of a ceramic susceptor. The raw material of the substrate was SiC raw material powder (purity 99.9 wt%, average particle size 0.1 μm) produced by the CVD method. 0.1 wt% of B4C and 0.5 wt% of C were added as sintering aids to the SiC raw material powder, and binders, dispersants, etc. were appropriately added and mixed to produce a slurry, which was then granulated by a spray-drying method.

[0068] Next, the granulated powder was isostatically molded, and after molding, it was processed into a disk-shaped compact with a diameter of 320 mm and a thickness of 10 mm, and a disk-shaped compact with a diameter of 320 mm and a thickness of 20 mm. In addition, a recess with a diameter of 294 mm and a depth of 0.15 mm was formed on one side of the compact with a thickness of 20 mm. W (tungsten) foil with a thickness of 0.1 mm was used as the high-frequency electrode. The high-frequency electrode was shaped so that the outer diameter was within the range of approximately φ300 mm.

[0069] Next, a high-frequency electrode was placed in the recess of the molded body with a thickness of t20 mm, and a laminate was formed by combining with a molded body with a thickness of t10 mm. Next, the laminate was heat-treated in a vacuum atmosphere at 1500°C for 2 hours, and then hot-pressed at a firing atmosphere of N2-added Ar atmosphere (N2 / Ar flow rate ratio = 0.03), firing temperature of 2200°C, and hot-press pressure of 4 MPa. The firing time was 3 hours. After firing, the outer diameter was set to Φ300 mm, the distance (thickness) from the upper surface to the high-frequency electrode was set to 1 mm, and the upper surface was polished to Ra0.2 μm. In addition, a blind hole was formed to the electrode, and a terminal made of Kovar was brazed in a vacuum at 850°C with Bag-8 brazing material. In this way, a ceramic susceptor of Example 1 was produced. In addition, a plate-shaped test sample of Example 1 with a thickness of t10 mm was produced using the same granulated powder under the same firing conditions.

[0070] Example 2 In Example 2, the firing atmosphere was an Ar atmosphere. Otherwise, the ceramic susceptor of Example 2 was produced under the same conditions as those of Example 1. In addition, a plate-shaped test sample of Example 2 having a thickness of t 10 mm was produced using the same granulated powder under the same firing conditions.

[0071] Example 3 In Example 3, the raw material of the substrate was changed to SiC raw material powder (purity 99.9 wt%, average particle size 0.5 μm) that was produced by the Acheson method and refined. The firing temperature was set to 2150° C. Except for that, the ceramic susceptor of Example 3 was produced under the same conditions as Example 1. In addition, a plate-shaped test sample of Example 3 having a thickness of t 10 mm was produced using the same granulated powder under the same firing conditions.

[0072] Comparative Example 1 In Comparative Example 1, Al2O3 was added as an additive to the Al source. Sintering aids and additives were added to the raw material powder in the ratio of 0.1 wt% B4C + 1.0 wt% C + 0.5 wt% Al2O3, and the granulated powder was granulated. The firing temperature was set to 2100°C. A ceramic susceptor of Comparative Example 1 was produced under the same conditions as in Example 3 except for the above. In addition, a plate-shaped test sample of Comparative Example 1 with a thickness of t 10 mm was produced using the same granulated powder and under the same firing conditions.

[0073] Example 4 In Example 4, the sintering aid was 0.2 wt% B4C + 1.0 wt% C, and the granulated powder was granulated. The firing atmosphere was an N2-added Ar atmosphere. Other than that, the ceramic susceptor of Example 4 was produced under the same conditions as Example 3. In addition, a plate-shaped test sample of Example 4 with a thickness of 10 mm was produced using the same granulated powder and under the same firing conditions.

[0074] Example 5 In Example 5, Al2O3 was added as an additive. The sintering aid and additive were added to the raw material powder in an amount of 0.1 wt% B4C + 1.0 wt% C + 0.5 wt% Al2O3, and the granulated powder was granulated. Otherwise, the ceramic susceptor of Example 5 was produced under the same conditions as Example 3. In addition, a plate-shaped test sample of Example 5 with a thickness of t 10 mm was produced using the same granulated powder and under the same firing conditions.

[0075] Example 6 In Example 6, AlN was added as an additive. The sintering aid and additive were added to the raw material powder in an amount of 0.2 wt% B4C + 1.0 wt% C + 0.5 wt% AlN, and the granulated powder was granulated. The firing temperature was set to 2100°C. A ceramic susceptor of Example 6 was produced under the same conditions as Example 3 except for the above. In addition, a plate-shaped test sample of Example 6 having a thickness of 10 mm was produced using the same granulated powder and under the same firing conditions.

[0076] Comparative Example 2 In Comparative Example 2, the firing atmosphere was an N2-added Ar atmosphere. The firing temperature was 2100°C. Other than that, the ceramic susceptor of Comparative Example 2 was produced under the same conditions as in Example 5. In addition, a plate-shaped test sample of Comparative Example 2 having a thickness of 10 mm was produced using the same granulated powder under the same firing conditions.

[0077] Example 7 In Example 7, the firing temperature was set to 2100° C. Except for this, the ceramic susceptor of Example 7 was produced under the same conditions as those of Example 5. In addition, a plate-shaped test sample of Example 7 having a thickness of t 10 mm was produced using the same granulated powder under the same firing conditions.

[0078] Example 8 In Example 8, the sintering aid and additives were added to the raw material powder as 0.3 wt% B4C + 3.0 wt% C + 1.0 wt% AlN in an internal ratio, and the granulated powder was granulated. The firing atmosphere was an N2-added Ar atmosphere. The firing temperature was 2050°C. Other than that, the ceramic susceptor of Example 6 was produced under the same conditions as Example 6. In addition, a plate-shaped test sample of Example 8 having a thickness of t10 mm was produced using the same granulated powder and under the same firing conditions.

[0079] Comparative Example 3 In Comparative Example 3, sintering aids and additives were added to the raw material powder in the ratio of 0.5 wt% B4C + 3.0 wt% C + 2.0 wt% Al2O3, and the granulated powder was granulated. The firing temperature was set to 2050°C. A ceramic susceptor of Comparative Example 3 was produced under the same conditions as in Example 5. A test sample for Comparative Example 3 in the form of a plate having a thickness of 10 mm was also produced using the same granulated powder and under the same firing conditions.

[0080] Example 9 In Example 9, sintering aids and additives were added to the raw material powder as 0.5 wt% B4C + 5.0 wt% C + 2.0 wt% AlN in an internal ratio, and granulated powder was produced. The firing atmosphere was an N2-added Ar atmosphere. The firing temperature was 2050°C. Other than that, the ceramic susceptor of Example 6 was produced under the same conditions as Example 6. Also, a plate-shaped test sample of Example 9 with a thickness of t10 mm was produced using the same granulated powder and under the same firing conditions.

[0081] Example 10 In Example 10, sintering aids and additives were added to the raw material powder in the ratio of 0.5 wt% B4C + 5.0 wt% C + 2.0 wt% Al2O3, and the granulated powder was granulated. The firing temperature was set to 2050°C. A ceramic susceptor of Example 10 was produced under the same conditions as Example 5 except for the above. In addition, a plate-shaped test sample of Example 10 with a thickness of 10 mm was produced using the same granulated powder and under the same firing conditions.

[0082] (Measurement of dielectric tangent tanδ) The dielectric loss tangent tanδ of the test samples of the examples and comparative examples was obtained by measuring and analyzing the impedance by the capacitance method using an impedance analyzer. The test samples of the examples and comparative examples were cut out and processed into a disk shape with a diameter of 15 mm and a thickness of 1 mm. Although this was not performed in the measurement, Au deposition may be performed on both sides of the sample if necessary. The impedance was measured using a measuring instrument (Keysight Technologies Impedance Analyzer E4991B, Test Fixture 16453A), and the dielectric loss tangent tanδ was calculated using the material measurement firmware installed in the measuring instrument. The measurement frequencies were 0.2 GHz, 0.5 GHz, and 1 GHz. The measurement temperature was 20°C (room temperature). The dielectric loss tangent tanδ at a measurement frequency of 1 GHz may be measured by a resonator method, a coaxial waveguide method, a free space method, etc. using a network analyzer or the like.

[0083] (Volume resistivity measurement) The volume resistivity of the test samples of the examples and comparative examples was measured by the three-terminal method (JIS C 2139-3). The test samples of the examples and comparative examples were cut out and processed into disks with a diameter of 60 mm and a thickness of 2 mm. The electrodes were formed by printing Ag paste. Using a measuring device (Advantest R8340 (ultra-high resistance meter)), the volume resistivity was measured 1 minute after the application of a test voltage of 500 VDC. The measurement temperature was 20°C (room temperature).

[0084] (Measurement of surface resistivity) The surface resistivity of the test samples of the examples and comparative examples was measured according to the same regulations (JIS C 2139-3) as for the measurement of volume resistivity after changing the electrode configuration and the voltage application method for surface resistivity measurement.

[0085] (Component analysis after firing) The test samples of the examples and comparative examples were subjected to trace element analysis by GDMS, and the molar concentration of Al relative to the entire ceramic sintered body was calculated.

[0086] FIG. 10 is a table showing the manufacturing conditions and the results of various tests for the examples and comparative examples. It can be assumed that the SiC structure is composed of a low-resistance intragranular structure and a surrounding space-depleted layer with high resistance (two-layer capacitor model). If so assumed, the relaxation time τ of the dielectric is said to be proportional to (intragranular resistance) × (capacitance of the space-depleted layer). The resistance in the grains is affected by (carrier concentration) × (mobility). Therefore, it is presumed that the ceramic sintered body forming the ceramic susceptor of the present invention has a smaller relaxation time τ and a corresponding smaller dielectric tangent tanδ as a result of the intragranular resistance being reduced by the elements constituting the additives diffusing into the grains and increasing the carrier concentration.

[0087] In the examples and comparative examples, it was found that the higher the sintering temperature, the smaller the dielectric tangent tanδ. Although the details are unclear, it is presumed that as the sintering temperature increases, the particle size increases, and the capacitance component of the two-layer capacitor model decreases relatively, resulting in a smaller τ and a lower tanδ. On the other hand, the appropriate sintering temperature is also related to the amount of sintering aids and additives added to the raw powder, so the higher the temperature, the better.

[0088] The particle size of the SiC powder produced by the Acheson method is larger than that of the SiC powder produced by the CVD method. If the sintering conditions are the same, this tendency is maintained to a certain extent even after sintering. Therefore, when the raw material produced by the CVD method is used, the particle size is small and the capacitance within the grains in the two-layer capacitor model is large, which is presumed to result in a large τ and a high tan δ. In addition, the raw material powder produced by the CVD method is finer, and a relatively fine structure remains after sintering, and many grain boundaries are formed. Therefore, it is presumed that the volume resistivity is higher. Furthermore, it is presumed that the raw material powder produced by the Acheson method may contain a relatively large amount of impurities, which is also the reason why the volume resistivity is relatively higher when the SiC powder produced by the CVD method is used as the raw material.

[0089] From the examples and comparative examples, the volume resistivity was lower as the amount of boron (B) or aluminum (Al) added increased. Therefore, it was found that to reduce the resistivity, it is better to add a certain amount of boron or aluminum. This is presumably due to the formation of an acceptor level in the SiC band, which is related to the solid solution of boron or aluminum in the SiC lattice. In addition, an increase in the volume resistivity was observed by sintering in an Ar atmosphere containing N2. This is presumably due to the influence of N penetrating into the SiC lattice. The aluminum content of the ceramic sintered bodies of Examples 5 to 10 was 0.2 mol% at minimum and 1.01 mol% at maximum.

[0090] Considering all of these, it is presumed that the ceramic susceptor of Comparative Example 1 had a large dielectric tangent tanδ because the firing temperature was low relative to the amount of sintering aids and additives added to the raw material powder. Also, it is presumed that the ceramic susceptor of Comparative Example 2 had a large dielectric tangent tanδ because the firing atmosphere was an N2-added Ar atmosphere. Also, it is presumed that the ceramic susceptor of Comparative Example 3 had a large dielectric tangent tanδ because the firing temperature was low relative to the amount of sintering aids and additives added to the raw material powder.

[0091] From the above, it was confirmed that the ceramic susceptor of the present invention can be used in high-output processes in the GHz band.

[0092] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications and equivalents are included within the spirit and scope of the present invention. In addition, the structure, shape, number, position, size, etc. of the components shown in each drawing are for convenience of explanation and may be changed as appropriate. [Explanation of symbols]

[0093] 10 Base material 12 Top side 14 Bottom side 16 center 18 Placement surface 20 High frequency electrodes 30 Media flow path 50, 51 terminals 52 Terminal hole 100 Ceramic susceptor 101, 102, 103 Ceramic degreased body 105 Groove 110 Laminate 121, 122 Base material precursor

Claims

1. A ceramic susceptor, The semiconductor substrate supporting member is provided with a base material having a mounting surface on which the semiconductor substrate supporting member is mounted, the base material being made of a ceramic sintered body mainly composed of SiC, The ceramic sintered body has a dielectric loss tangent tanδ of 0.45 or less at 0.2 GHz, A ceramic susceptor having a dielectric loss tangent tan δ of 0.70 or less at 0.5 GHz.

2. The ceramic sintered body has a volume resistivity of 10 at 20° C. ７ 2. The ceramic susceptor according to claim 1, characterized in that the resistivity is less than Ωcm.

3. The ceramic sintered body has a dielectric loss tangent tanδ of 0.40 or more at 0.5 GHz, The volume resistivity at 20°C is 10 ５ 3. The ceramic susceptor according to claim 2, characterized in that the resistivity is less than Ωcm.

4. 4. The ceramic susceptor according to claim 1, wherein the ceramic sintered body contains Al in an amount of 0.2 mol % or more and 1.1 mol % or less.

5. 4. The ceramic susceptor according to claim 1, further comprising a high-frequency electrode embedded in the base material.

6. 4. The ceramic susceptor according to claim 1, wherein the base material is provided with a medium flow passage therein.

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