Ceramic susceptor and manufacturing method of ceramic susceptor

Abstract

To provide a technique for ensuring a flow velocity and a flow rate of a liquid flowing through a flow path, and for suppressing stress concentration at corners of the flow path.SOLUTION: A thickness of a wall 115 defining a side wall surface 112b of a flow path 112 formed inside a SiC composite 110 is smaller in a central portion between the two end portions in a vertical direction than in both end portions in the vertical direction. In addition, in a cross section perpendicular to a longitudinal direction of the flow path 112, an angle between a top wall surface 112a and a side wall surface 112b of the flow path 112 is greater than 90°, and the top wall surface 112a and the side wall surface 112b of the flow path 112 are formed by gently curved surfaces.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a ceramic susceptor and a method for manufacturing a ceramic susceptor. [Background technology]

[0002] Patent Document 1 discloses an electrostatic chuck as an example of a ceramic susceptor having a wafer mounting surface for holding a substrate such as a wafer. The electrostatic chuck described in Patent Document 1 is manufactured by stacking and firing a plurality of green sheets, including a green sheet having holes that form flow paths. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-96336 Summary of the Invention [Problem to be solved by the invention]

[0004] When stacking the green sheets, a compressive force is applied to the green sheets in the thickness direction. Because the green sheets have high plasticity, the application of the compressive force causes the green sheets to deform, bulging convexly toward the inside of the grooves. As a result, the cross section of the flow path formed inside is deformed so that all sides of the flow path are concave toward the inside of the flow path. This makes it difficult to obtain a sufficient cross-sectional area of the flow path, making it difficult to ensure the flow velocity and volume of the liquid flowing through the flow path. Furthermore, at the corners of the flow path, the upper wall surface that defines the upper surface of the flow path and the side wall surface that defines the side surface intersect at an acute angle. This results in stress concentration at the corners of the flow path.

[0005] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a technology for ensuring the flow velocity and volume of liquid flowing through a flow path while suppressing stress concentration at the corners of the flow path. [Means for solving the problem]

[0006] According to an aspect of the present invention, a ceramic sintered body is provided which has an upper surface and a lower surface facing the upper surface in a vertical direction, and has a flow path formed therein extending in a longitudinal direction perpendicular to the vertical direction, a thickness of a side wall defining a side wall surface of the flow path in a width direction perpendicular to the vertical direction and the longitudinal direction is smaller at a central portion between both end portions of the side wall in the vertical direction than at both end portions of the side wall in the vertical direction; With respect to a cross section perpendicular to the longitudinal direction of the flow channel, A ceramic susceptor is provided, characterized in that the angle formed between the upper wall surface and the side wall surface of the flow path is greater than 90°, or the upper wall surface and the side wall surface of the flow path are formed by gently curved surfaces. [Effects of the Invention]

[0007] According to the configuration of the present invention, the thickness of the sidewall defining the sidewall surface of the flow channel in the width direction (the direction perpendicular to the vertical and longitudinal directions) is smaller at the central portion between the vertical end portions of the sidewall than at the vertical end portions of the sidewall. In other words, the width length of the flow channel at the vertical center portion is smaller than the length of the flow channel at the vertical end portions. This contributes to ensuring the flow velocity and flow rate of the liquid flowing through the flow channel and reducing pressure loss throughout the flow channel. Furthermore, in a cross section perpendicular to the longitudinal direction of the flow channel, the angle between the top wall surface and the side wall surface of the flow channel is greater than 90°, or the top wall surface and the side wall surface of the flow channel are formed by a gently curved surface. This contributes to reducing stress concentration at the corners of the flow channel. This contributes to ensuring the flow velocity and flow rate of the liquid flowing, particularly through the corners of the flow channel, and reducing pressure loss throughout the flow channel. Furthermore, since heat transfer by the medium at the corners of the flow path is sufficiently achieved, it is expected that the temperature distribution on the wafer-mounting surface immediately above the side wall surface of the ceramic susceptor will be more uniform. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a ceramic susceptor 100. As shown in FIG. [Figure 2] FIG. 2 is a schematic explanatory diagram of the ceramic susceptor 100. As shown in FIG. [Figure 3] FIG. 3 is a flowchart showing a method for manufacturing the SiC composite material 110. [Figure 4] 10(a) to 10(d) are diagrams showing the flow of another method for producing the SiC composite material 110. FIG. [Figure 5] (a) is an explanatory diagram for explaining the joining of a calcined body of a lower plate 130 having a groove 124 with a rectangular cross section formed on its upper surface 131 with a calcined body of an upper plate 120, (b) is an explanatory diagram for explaining the joining of a calcined body of a lower plate 130 having a groove 124 formed on its upper surface 131 with a calcined body of an upper plate 120 having a groove 124 formed on its lower surface 122, and (c) is an explanatory diagram for explaining the cross section of a flow path 112 formed inside a SiC composite material 110. [Figure 6] FIG. 6 is an explanatory diagram illustrating an SiC composite material 910 produced by stacking three layers of green sheets and firing them. [Figure 7] FIG. 7 is an explanatory diagram for explaining the thickness of the wall 115 and the longitudinal direction of the flow channel 112. As shown in FIG. [Figure 8] 1(a) is an explanatory diagram for explaining a flow channel 112 having an octagonal cross section, and FIG. 1(b) is an explanatory diagram for explaining a flow channel 112 having a hexagonal cross section. DETAILED DESCRIPTION OF THE INVENTION

[0009] <Ceramic susceptor 100> The ceramic susceptor 100 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. The ceramic susceptor 100 according to the present embodiment is used, for example, as a stage for holding a semiconductor wafer such as a silicon wafer (hereinafter simply referred to as wafer 10) inside a semiconductor manufacturing apparatus. In that case, an electrostatic chuck or a heater plate is disposed on the ceramic susceptor 100. Further, as will be described later, an electrode 140 (see FIG. 2) may be embedded in the ceramic susceptor 100 itself. In that case, it can also be used as a heater for heating the wafer 10. In the following description, the vertical direction 5 is defined based on the state in which the ceramic susceptor 100 is installed so as to be usable (the state in FIG. 1). As shown in FIG. 1, the ceramic susceptor 100 according to the present embodiment includes a plate-shaped SiC composite material 110 having a flow path 112 (see FIG. 2) formed therein, and an electrode 140 (see FIG. 2). The SiC composite material 110 is an example of the ceramic sintered body of the present invention.

[0010] <SiC composite material 110> The SiC composite material 110 is formed of SiC ceramics containing SiC and has a circular plate shape. In the present embodiment, the SiC composite material 110 is a ceramic sintered body containing SiC and has a thermal conductivity of 75 W / (m·K) or more. Since SiC ceramics have high resistance to water, water can be flowed as a cooling fluid through the flow path 112 formed inside. Water has high thermal conductivity and is suitable when absorbing a large amount of heat. The ceramic sintered body containing SiC may contain, in addition to SiC, sintering aids such as B4C, C, and Y2O3, and may further contain metal borides, metal carbides, metal nitrides, etc. to form a SiC composite material. For example, as the metal boride, borides of metals in Groups 4 to 6 of the periodic table can be used. Although there is no particular limitation on the size of the SiC composite material 110, it can be set to a diameter of 150 mm or more and a thickness of 20 mm to 50 mm from the use as a substrate holding member for a semiconductor manufacturing apparatus.

[0011] As shown in FIG. 2, a hollow flow path 112 is formed inside the SiC composite material 110. As will be described later, the SiC composite material 110 is formed by bonding an upper plate 120 and a lower plate 130 (see FIG. 2) together. Note that in FIGS. 1 and 2, for convenience of explanation, the boundary between the upper plate 120 and the lower plate 130 is illustrated by a solid line. By forming a groove 124 on at least one of the lower surface 122 (the surface facing the lower plate 130) of the upper plate 120 and the upper surface 131 (the surface facing the upper plate 120) of the lower plate 130, and then bonding the upper plate 120 and the lower plate 130 in an overlapping state, the hollow flow path 112 can be formed inside the SiC composite material 110. Note that the planar shape of the flow path 112 can be any shape. For example, the flow path 112 may have a substantially spiral shape when viewed from above. The cross-sectional shape of the flow path 112 will be described later. In order to ensure a sufficient flow rate and volume of the cooling fluid, the height (length in the vertical direction) and width (length in the direction perpendicular to the vertical direction in a vertical plane) of the flow channel 112 are preferably 2 mm or more, and more preferably 10 mm or more. In order to reduce the flow channel resistance of the flow channel 112, the center line average roughness Ra of the inner surface of the flow channel 112 is preferably 0.8 μm or less, more preferably 0.4 μm or less, and even more preferably 0.2 μm or less. As will be described later, in this embodiment, the grooves 124 are formed by machining (grinding) the calcined body or sintered body, so that the center line average roughness Ra can be easily adjusted.

[0012] <Electrode 140> As shown in FIG. 2, an electrode 140 is embedded in the upper plate 120 at a position 0.05 mm or more below the upper surface 121. As shown in FIG. 2, the electrode 140 is a metal mesh or foil cut into a strip shape. The outer diameter of the electrode 140 is slightly smaller than that of the upper plate 120, and the electrode 140 is not exposed from the side of the upper plate 120. A terminal portion 141 to be connected to a power supply line (not shown) is provided approximately in the center of the electrode 140. The electrode 140 is formed of a heat-resistant metal (high-melting point metal) such as a mesh or foil woven with wires of tungsten (W), molybdenum (Mo), molybdenum and / or an alloy containing tungsten. The purity of the tungsten and molybdenum is preferably 99% or more. The thickness of the electrode 140 is 0.15 mm or less. From the viewpoint of increasing the resistance value of the electrode 140 and reducing current consumption, it is preferable that the wire diameter be 0.1 mm or less and the thickness of the electrode 140 be 0.1 mm or less. Furthermore, the width of the strip-shaped electrode 140 is preferably 2.5 mm to 20 mm, more preferably 5 mm to 15 mm. In this embodiment, the electrode 140 is cut into the shape shown in FIG. 2 , but the shape of the electrode 140 is not limited thereto and can be modified as appropriate. In addition to or instead of the electrode 140, an electrostatic attraction electrode or a plasma electrode for generating plasma above the SiC composite material 110 may be embedded inside the upper plate 120. Furthermore, the electrode 140 does not necessarily have to be embedded in the upper plate 120. For example, the electrode 140 may be embedded in the lower plate 130. Alternatively, the electrode 140 may be embedded in both the upper plate 120 and the lower plate 130.

[0013] <Method for manufacturing ceramic susceptor 100> Next, we will explain a method for manufacturing the ceramic susceptor 100. The method for manufacturing the ceramic susceptor 100 includes producing an upper plate 120 and a lower plate 130 each containing SiC as a component, and joining the upper plate 120 and the lower plate 130 together.

[0014] A method for producing the upper plate 120 and the lower plate 130 will be described with reference to FIG. 3. First, 4 wt % or less of sintering aids (B4C, C) are added to the SiC raw material powder as needed. Metal boride can also be added to the SiC raw material powder. Next, a PVA (polyvinyl alcohol) binder is added to the SiC raw material powder, and the mixture is mixed in ethanol, dried, and then granulated to produce granulated powder Q containing SiC as a component (S101). When producing the granulated powder Q, the sintering aid addition rate can be the same for the granulated powder Q for producing the upper plate 120 and the granulated powder Q for producing the lower plate 130, but can also be different.

[0015] Next, the granulated powder Q is filled into a rubber mold and isostatically pressurized (CIP) using water pressure to produce a CIP molded body that will become the upper plate 120 and a CIP molded body that will become the lower plate 130 (S102). For example, CIP molding can be performed at a pressure of 130 MPa. Next, the CIP molded body is degreased to remove the binder. The degreased CIP molded body is then heat-treated in a vacuum atmosphere at a temperature of 1500°C for two hours, and then fired in an Ar atmosphere at a temperature of 2000°C or higher for three hours at atmospheric pressure (S103). Alternatively, the CIP molded body may be placed in a carbon mold with a floor 601 (see FIG. 4) and hot-press fired while pressed with a punch 602. For example, hot-press firing can be performed in an Ar atmosphere at a temperature of 2000°C or higher for three hours (S103). Note that the firing time is not necessarily limited to three hours. The firing time is preferably from 0.1 to 10 hours, and more preferably from 1 to 5 hours.

[0016] Next, the sintered body is subjected to external shaping (S104) to produce the upper plate 120 and the lower plate 130. At this time, grooves 124 (see FIG. 2), which will later become the flow paths 112, are formed in the upper surface 131 of the lower plate 130 and / or the lower surface 122 of the upper plate 120. Note that the grooves 124 do not necessarily have to be formed in the sintered body. Before sintering the CIP molded body, the CIP molded body can be calcined at a temperature lower than the sintering temperature (for example, a temperature 500°C to 100°C lower than the sintering temperature) to produce a calcined body, and the grooves 124 can be formed in the calcined body. Alternatively, the grooves 124 can be formed in the CIP molded body, and after calcining the CIP molded body with the grooves 124 formed therein, additional processing can be performed on the calcined body so that the grooves 124 have the desired dimensions.

[0017] When the electrode 140 is embedded in the upper plate 120, two CIP molded bodies that will become the upper plates 120 are produced, and fired bodies (or calcined bodies) of the two upper plates 120 are produced. Then, a recess (not shown) for embedding the electrode 140 is formed in at least one of the fired bodies (or calcined bodies) of the two upper plates 120. Then, by stacking the two upper plates 120 with the electrode 140 placed in the recess, it is possible to produce the upper plate 120 with the electrode 140 embedded therein.

[0018] In the above description, CIP molded bodies of the upper plate 120 and the lower plate 130 were fabricated and then fired. The present invention is not necessarily limited to fabricating CIP molded bodies. For example, the upper plate 120 and the lower plate 130 can be fabricated using the method described below. As shown in FIG. 4(a), granulated powder P primarily composed of SiC powder is placed in a carbon mold with a floor 601 and pre-pressed with a punch 602. It is preferable that the granulated powder P contains a sintering aid. Next, as shown in FIG. 4(b), an electrode 140 cut to a predetermined shape is placed on the pre-pressed granulated powder P. The electrode 140 is placed parallel to a plane perpendicular to the pressure direction (the bottom surface of the mold with a floor 601). At this time, a W pellet or a Mo pellet may be embedded at the position of the terminal 141 (see FIG. 2) of the electrode 140.

[0019] As shown in FIG. 4(c), granulated powder P is further poured into bed-type mold 601 so as to cover electrode 140, and is pressed and molded with punch 602. Next, as shown in FIG. 4(d), granulated powder P with electrode 140 embedded therein is fired in a pressed state. The pressure applied during firing is preferably 1 MPa or more. Also, firing is preferably performed at a temperature of 1800°C or more. The external processing after firing is the same as described above, and therefore will not be described here. Note that, as in the above description, a calcined body can be produced and the above-described external processing can be performed on the calcined body.

[0020] Next, a method for bonding the upper plate 120 and the lower plate 130 will be described. The upper plate 120 and the lower plate 130 can be bonded by diffusion bonding at a temperature of 1500°C or higher and a pressure of 1 MPa or higher. In this case, it is not necessary to interpose a bonding material between the upper plate 120 and the lower plate 130. The absence of a bonding material means that no bonding layer is visible under an optical microscope (magnification of approximately 500x). Therefore, the upper plate 120 and the lower plate 130 can be bonded in a state of direct contact. When bonding the upper plate 120 and the lower plate 130 by diffusion bonding, the centerline average roughness Ra of the bonding surfaces before bonding is preferably 0.2 μm or less, and more preferably 0.1 μm or less. The above bonding method can be applied to bonding calcined bodies in addition to bonding sintered bodies. In this case, the bonding temperature is higher than the calcination temperature and equivalent to the firing temperature, and bonding and firing are performed simultaneously.

[0021] The upper plate 120 and the lower plate 130 can be joined by hard brazing. A hard brazing material is a brazing material having a melting point (including liquidus temperature and glass transition temperature) of 450°C or higher. By heating the upper plate 120 and the lower plate 130 with the hard brazing material interposed between them to a temperature of 450°C or higher, the upper plate 120 and the lower plate 130 can be joined by the fluidized or molten hard brazing material. At this time, the heat joining is performed under a load of 0.001 MPa or higher. The atmosphere can be appropriately selected from air, inert gas, and vacuum. Examples of hard brazing materials that can be used include silver brazing (BAg-8, melting point 780°C), aluminum brazing (A4047, eutectic point 577°C), gold brazing (BAu-4, liquidus temperature 950°C), and nickel brazing (BNi-2, liquidus temperature 1000°C). These brazing filler metals may contain active metals such as Ti, Hf, and Zr. Metal foils such as Al foils can also be used as brazing filler metals. When joining the upper plate 120 and the lower plate 130 by brazing, it is preferable that the center line average roughness Ra of the joining surfaces before joining be 1.6 μm or less.

[0022] The upper plate 120 and the lower plate 130 can be joined by soft soldering. Soft solder is a brazing material having a melting point (including liquidus temperature and glass transition temperature) below 450°C. By heating the upper plate 120 and the lower plate 130 with the soft solder material interposed between them to a temperature below 450°C, the upper plate 120 and the lower plate 130 can be joined by the fluidized or molten soft solder material. At this time, the heat joining is performed under a load of 0.001 MPa or more. The atmosphere can be selected from air, inert gas, and vacuum. Examples of the soft solder material that can be used include In, Sn, Pb, and alloys (solder) thereof. When joining the upper plate 120 and the lower plate 130 by soft soldering, it is preferable that the centerline average roughness Ra of the joining surfaces before joining be 1.6 μm or less.

[0023] The method for joining the upper plate 120 and the lower plate 130 is not limited to the above-mentioned diffusion bonding, hard solder bonding, and soft solder bonding, but known anodic bonding or the like can also be used.

[0024] Next, a cross section of the flow path 112 formed in the SiC composite 110 of the ceramic susceptor 100 manufactured by the above-described manufacturing method will be described. In the following description, the cross-sectional shape of the flow path 112 will be considered when a calcined body of the lower plate 130 having grooves 124 with rectangular cross sections formed on its upper surface 131 and a calcined body of the upper plate 120 are joined together to form an integrated body, as shown in Fig. 5(a). Note that the same applies to the case where a calcined body of the lower plate 130 having grooves 124 formed on its upper surface 131 and a calcined body of the upper plate 120 having grooves 124 formed on its lower surface 122 are joined together to form an integrated body, or when fired bodies are joined instead of calcined bodies, as shown in Fig. 5(b), and therefore a description thereof will be omitted.

[0025] As shown in FIG. 5(c), the cross section of the flow channel 112 formed inside the SiC composite 110 has a shape that is recessed toward the inside of the flow channel 112 on both sides in the vertical direction and bulges toward the outside of the flow channel 112 on both sides in the width direction of the flow channel 112, which is perpendicular to the vertical direction. In other words, the thickness of the wall 115 between two adjacent flow channels 112 in the width direction is not constant in the vertical direction, and the wall 115 has a narrow portion that is smallest at approximately the center in the vertical direction. In this specification, the thickness of the wall 115 at a certain position is defined as follows. As shown in FIG. 7, when a center line 115C of the wall 115 is defined, a perpendicular line N is drawn from this position to the center line 115C of the wall 115. In this case, the length of the portion of the perpendicular line N that overlaps with the wall 115 is defined as the thickness of the wall 115 at that position.

[0026] As shown in Figure 5(c), the upper wall surface 112a that defines the upper surface of the flow path 112 and the side wall surface 112b that defines the side surface are formed by a gently curved surface, or the angle formed by the upper wall surface 112a that defines the upper surface of the flow path 112 and the side wall surface 112b that defines the side surface is greater than 90°.

[0027] As described above, even when grooves 124 having a rectangular cross section are formed, the cross section of the flow channel 112 formed inside the SiC composite material 110 has a shape that is concave toward the inside of the flow channel 112 on both sides in the vertical direction and bulges toward the outside of the flow channel 112 on both sides in the width direction of the flow channel 112, which is perpendicular to the vertical direction. This deformation of the cross-sectional shape of the flow channel 112 is thought to be caused by a pressing force in the thickness direction (vertical direction) when the upper plate 120 and the lower plate 130, which are made of calcined or sintered bodies, are joined. Therefore, the degree of deformation (amount of deformation) of the cross-sectional shape of the flow channel 112 is affected by the rigidity of the upper plate 120 and the lower plate 130 at the time of joining. When the calcined body of the upper plate 120 and the calcined body of the lower plate 130 are joined, the deflection (straightness) per 10 mm of the length of each side of the flow channel 112 is 0.05 mm to 1.0 mm. Furthermore, when the fired body of the upper plate 120 and the fired body of the lower plate 130 are joined together, the deflection (straightness) per 10 mm length of each side of the flow channel 112 is also 0.05 mm to 1.0 mm.

[0028] In contrast, consider a conventional method for producing a SiC composite material 910 by stacking three layers of ceramic green sheets (hereinafter simply referred to as green sheets) and firing them (see FIG. 6). For example, a through groove 924 serving as a flow path 912 can be formed in the center green sheet of the three green sheets, and two green sheets are stacked from above and below to close the through groove 924, thereby producing a SiC composite material 910 having the flow path 912 formed therein. When three green sheets are stacked, the cross section of the flow path 912 formed inside the SiC composite material 910 by the through groove 924 is significantly deformed when a compressive force is applied to the green sheets in the thickness direction (vertical direction). This is because the green sheets have low rigidity. When fired as is, the cross section of the flow path 912 formed inside the SiC composite material 910 is deformed so that it is recessed toward the inside of the flow path 912 on both sides in the vertical direction and also recessed toward the inside of the flow path 912 on both sides in the width direction of the flow path 912, which is perpendicular to the vertical direction. In this case, the thickness (widthwise length) of the wall 915 between two adjacent channels 912 in the widthwise direction is greatest at approximately the center in the vertical direction. In this respect, it differs significantly from the cross section of the channel 112 formed inside the SiC composite 110 according to this embodiment. Furthermore, the upper wall surface 912a defining the upper surface of the channel 912 and the side wall surface 912b defining the side surface intersect at an acute angle and do not form a smoothly connected curved surface. In this respect, it also differs significantly from the cross section of the channel 112 formed inside the SiC composite 110 according to this embodiment. Furthermore, the rigidity of the green sheets is significantly lower than the rigidity of the calcined body and the sintered body. Therefore, the pressure applied when laminating the green sheets causes the cross section of the channel 912 to deform more significantly than when joining calcined bodies or sintered bodies. Therefore, the deflection (straightness) per 10 mm of each side of the channel 912 is greater than 1.0 mm.

[0029] Next, we will consider the relationship between the parallel distance d (see FIG. 5(c)) between the upper surface 121 of the upper plate 120 and the upper wall surface 112a of the flow channel 112 and the straightness of the upper side of the cross section of the flow channel 112. The smaller the parallel distance d (mm), the greater the deflection (straightness) per 10 mm of the length of the upper side of the cross section of the flow channel 112. In particular, if the parallel distance d (mm) is less than 3 mm, the strength of the portion of the upper plate 120 covering the flow channel 112 will be insufficient, increasing the risk of breakage, which is unsuitable. Therefore, it is preferable that the parallel distance d (mm) is 3 mm or more. According to the inventors' findings, when the parallel distance d (mm) is d 3 It was also found that when the parallel distance d (mm) exceeds 10 mm, deformation of the cross section of the flow channel 112 into a shape that is recessed toward the inside of the flow channel 112 on both sides in the vertical direction and bulged toward the outside of the flow channel 112 on both sides in the width direction of the flow channel 112, which is perpendicular to the vertical direction, is unlikely to occur.

[0030] <Effects of the embodiment> In the above embodiment, the ceramic susceptor 100 includes a plate-shaped SiC composite 110 containing SiC as a component. A flow path 112 is formed inside the SiC composite 110, extending longitudinally in a plane perpendicular to the vertical direction. Here, if the flow path 112 is curved rather than linear, the longitudinal direction of the flow path 112 at a certain position is defined as a tangential direction to a center line 112C (see FIG. 7 ) of the flow path 112 at that position. The thickness of a wall 115 defining a sidewall surface 112b of the flow path 112 formed inside the SiC composite 110 is smaller in a central portion between the vertical end portions than in both vertical end portions. Furthermore, in a cross section perpendicular to the longitudinal direction of the flow path 112, the angle between the top wall surface 112a and the sidewall surface 112b of the flow path 112 is greater than 90°, and the top wall surface 112a and the sidewall surface 112b of the flow path 112 are formed as gently curved surfaces.

[0031] According to the above configuration, the thickness of the wall 115 is smaller in the vertical center portion than at both ends in the vertical direction. Therefore, the width (length perpendicular to the vertical and longitudinal directions) of the flow path 112 in the vertical center portion is smaller than the width at both ends in the vertical direction. This contributes to ensuring the flow velocity and flow rate of the liquid flowing through the flow path 112 and reducing the pressure loss throughout the flow path. Furthermore, in a cross section perpendicular to the longitudinal direction of the flow path 112, the angle between the top wall surface 112a and the side wall surface 112b of the flow path 112 is greater than 90°, and the top wall surface 112a and the side wall surface 112b of the flow path 112 are formed as gently curved surfaces. This contributes to reducing stress concentration at the corners of the flow path 112. Furthermore, the flow velocity and flow rate of the liquid flowing through the flow path 112 are ensured and reducing the pressure loss throughout the flow path.

[0032] In the above embodiment, the straightness of the side wall surface 112b of the flow channel 112 per 10 mm in the vertical direction in the cross section of the flow channel 112 is 0.05 mm or more and 1.0 mm or less. Also, in the above embodiment, the straightness of the top wall surface 112a of the flow channel 112 per 10 mm in the width direction in the cross section of the flow channel 112 is 0.05 mm or more and 1.0 mm or less. Limiting the deformation amount of the flow channel 112 within this range ensures the flow velocity and flow rate of the liquid flowing through the flow channel 112, and contributes to reducing the pressure loss throughout the flow channel.

[0033] In the above embodiment, the parallel distance d between the upper surface 121 of the upper plate 120 and the upper wall surface 112a of the flow path 112 can be set to 3 mm or more. This makes it possible to prevent the portion of the upper plate 120 covering the flow path 112 from becoming weak and increasing the risk of breakage.

[0034] In the above embodiment, the SiC composite 110 is a ceramic sintered body containing SiC. As described above, when a SiC composite is formed by stacking and firing green sheets, a pressure is applied to the green sheets in the thickness direction (vertical direction) when stacking the green sheets, which causes significant deformation of the cross section of the flow path formed inside after firing. However, in the above embodiment, grooves that become the flow path are formed in the calcined body or sintered body, and then the calcined body or sintered body is bonded. This makes it possible to easily form hollow flow paths with minimal deformation of the cross section of the flow path even inside a ceramic sintered body containing SiC.

[0035] <Modification form> The above-described embodiments and examples are merely illustrative and may be modified as appropriate. For example, the shape and dimensions of the SiC composite 110 are not limited to those of the above-described embodiments and examples and may be modified as appropriate.

[0036] In the above embodiment, the ceramic susceptor 100 includes the SiC composite material 110 formed of SiC ceramics containing SiC as the ceramic sintered body. However, the ceramic sintered body does not necessarily have to be formed of SiC ceramics containing SiC. For example, the ceramic sintered body may be formed of ceramics containing AlN and Al2O3.

[0037] In the above embodiment, the angle formed between the top wall surface 112a and the side wall surface 112b of the flow channel 112 is greater than 90°, and the top wall surface 112a and the side wall surface 112b of the flow channel 112 are formed as gently curved surfaces. However, as long as the angle formed between the top wall surface 112a and the side wall surface 112b of the flow channel 112 is greater than 90°, the top wall surface 112a and the side wall surface 112b of the flow channel 112 do not necessarily have to be formed as gently curved surfaces. Furthermore, as long as the top wall surface 112a and the side wall surface 112b of the flow channel 112 are formed as gently curved surfaces, the angle formed between the top wall surface 112a and the side wall surface 112b of the flow channel 112 does not necessarily have to be greater than 90°.

[0038] In the above embodiment, the cross-sectional shape of the grooves 124 formed in the calcined body or the fired body is rectangular. However, the present disclosure is not limited to such an embodiment. The cross-sectional shape of the grooves 124 can be polygonal so that the cross-section of the flow channels 112 is polygonal. For example, as shown in FIG. 8( a), the grooves 124 can be formed with an octagonal cross-section so that the cross-section of the flow channels 112 is octagonal. Alternatively, as shown in FIG. 8( b), the grooves 124 can be formed with a hexagonal cross-section so that the cross-section of the flow channels 112 is hexagonal. In either case, the thickness of the wall 115 between two adjacent flow channels 112 in the width direction is not constant in the vertical direction, and the wall 115 has a narrow portion that is narrowest approximately at the center in the vertical direction. As a result, when grooves 124 are formed in both the upper plate 120 and the lower plate 130 and the upper plate 120 and the lower plate 130 are joined together, the upper plate 120 and the lower plate 130 can be joined at the narrow portion of the wall 115, thereby increasing the joining stress during joining. Also, in both cases of Figures 8(a) and 8(b), the angle formed by the upper wall surface 112a that defines the upper surface of the flow channel 112 and the side wall surface 112b that defines the side surface is greater than 90°. This makes it possible to suppress stress concentration at the corners of the flow channel 112. The cross section of the flow channel 112 may be a polygon with irregular sides.

[0039] Although the present invention has been described above using embodiments and modifications thereof, the technical scope of the present invention is not limited to the scope of the above description. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0040] The order of execution of each process in the manufacturing method shown in the specification and drawings is not particularly specified, and the processes may be executed in any order unless the output of a previous process is used in a subsequent process. For convenience, even if a description is made using "first," "next," etc., it does not mean that the processes must be executed in this order. [Explanation of symbols]

[0041] 100 Ceramic susceptor 110 SiC composite 120 Upper Plate 130 Lower plate 140 electrodes

Claims

1. a ceramic sintered body having an upper surface and a lower surface facing the upper surface in a vertical direction, and having a flow path formed therein extending in a longitudinal direction perpendicular to the vertical direction; a thickness of a side wall defining a side wall surface of the flow path in a width direction perpendicular to the vertical direction and the longitudinal direction is smaller at a central portion between both end portions of the side wall in the vertical direction than at both end portions of the side wall in the vertical direction; With respect to a cross section perpendicular to the longitudinal direction of the flow channel, A ceramic susceptor characterized in that the angle formed between the upper wall surface and the side wall surface of the flow path is greater than 90°, or the upper wall surface and the side wall surface of the flow path are formed by gently curved surfaces.

2. 2. The ceramic susceptor according to claim 1, wherein the straightness of the side wall surface of the flow path per 10 mm in the vertical direction in the cross section is 0.05 mm or more and 1.0 mm or less.

3. 2. The ceramic susceptor according to claim 1, wherein the straightness of the upper wall surface of the flow path per 10 mm in the width direction in the cross section is 0.05 mm or more and 1.0 mm or less.

4. 2. The ceramic susceptor according to claim 1, wherein the vertical distance between the upper surface of the ceramic sintered body and the upper wall surface of the flow channel is 3.0 mm or more.

5. 5. The ceramic susceptor according to claim 1, wherein the ceramic sintered body is a sintered body of ceramic containing SiC.

6. forming a groove in at least one of the plurality of ceramic calcined bodies or at least one of the plurality of ceramic sintered bodies; stacking the plurality of ceramic calcined bodies or the plurality of ceramic sintered bodies so as to cover the groove, and bonding them by applying pressure in the stacking direction, thereby forming a ceramic laminate having a flow path formed therein, the side wall surface of which is defined by a side wall having a narrowest portion that is thinner in thickness at a central portion between the two end portions in the vertical direction than at both end portions in the stacking direction.

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