Ceramic heater

Abstract

To provide a ceramic heater that contributes to improving the temperature uniformity of a wafer to be heated.SOLUTION: A ceramic heater 100 includes a ceramic base material 110, and a heater portions of an inner heater electrode 120 and an outer heater electrode 122 embedded in the ceramic base material 110. In a thermocouple 171 in which temperature measuring contacts 171a are arranged at positions A and C, the temperature measuring contacts 171a do not overlap the heater portions of the inner heater electrode 120 and the outer heater electrode 122 in the vertical direction.SELECTED DRAWING: Figure 2

Description

Technical Field

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[0001] The present invention relates to a ceramic heater for heating a substrate such as a silicon wafer.

Background Art

[0002] The ceramic heater described in Patent Document 1 includes a disk-shaped ceramic substrate (ceramic base body), a heating element (heating resistor) embedded in the ceramic substrate, and a thermocouple. ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​of Of these, the temperature-sensing portion of at least one of the temperature-sensing bodies is positioned so as not to overlap with the plurality of heating elements in the vertical direction. Occasionally, The plurality of heating elements each have an outer heating element embedded in the outer peripheral portion of the ceramic substrate and an inner heating element embedded inside the outer heating element. Furthermore, it is provided with a conductive portion that is located at the same height as the outer heating element in the vertical direction, connected to the outer heating element, and overlapping with the inner heating element in the vertical direction, The temperature-measuring portion of the at least one of the temperature-measuring bodies is positioned so as not to overlap with the conductive portion. A ceramic heater is provided. [Effects of the Invention]

[0007] In the above embodiment, the temperature sensing unit can control the temperature of the ceramic substrate using a temperature sensing element positioned so as not to overlap with the multiple heating elements in the vertical direction. This can contribute to improving the uniformity of the temperature of a wafer to be heated, such as a silicon wafer used for temperature evaluation. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a perspective view of the ceramic heater 100. [Figure 2] Figure 2 is a schematic diagram of the ceramic heater 100. [Figure 3] (a) is a schematic diagram of the inner heater electrode 120, (b) is a schematic diagram of the outer heater electrode 122, and (c) is a schematic diagram of the electrostatic adsorption electrode 124. [Figure 4] Figure 4 is an explanatory diagram illustrating the shape of shaft 130. [Figure 5] Figures (a) to (e) show the flow of the manufacturing method for the ceramic substrate 110. [Figure 6] Figure 6 is a table summarizing the results of Examples 1 to 15. [Figure 7] Figure 7 is an explanatory diagram illustrating the ceramic heater 100 of Example 1. [Figure 8] Figure 8 is an explanatory diagram illustrating the ceramic heater 100 of Example 3. [Figure 9]FIG. 9 is an explanatory diagram for explaining the opening 120h of the inner heater electrode 120 of the ceramic heater 100 of Example 12. [Figure 10] FIG. 10 is an explanatory diagram for explaining the curved portion C1 of the TC wiring hole 170 of the ceramic heater 100 of Example 13. [Figure 11] FIG. 11 is an explanatory diagram for explaining the curved portion C2 of the TC wiring hole 170 of the ceramic heater 100 of Example 14. [Figure 12] FIG. 12 is an explanatory diagram for explaining the ceramic heater 100 of Example 15. [Figure 13] FIG. 13 is an explanatory diagram for explaining the ceramic heater 100 in which the outer heater electrode 122 is disposed above the inner heater electrode 120.

MODE FOR CARRYING OUT THE INVENTION

[0009] <Ceramic heater 100> The ceramic heater 100 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. The ceramic heater 100 according to the present embodiment is a ceramic heater used for heating a semiconductor wafer such as a silicon wafer (hereinafter simply referred to as a wafer 10). In the following description, the vertical direction 5 is defined based on the state in which the ceramic heater 100 is installed so as to be usable (the state in FIG. 1). As shown in FIG. 1, the ceramic heater 100 according to the present embodiment includes a ceramic base material 110, electrodes (inner heater electrode 120, outer heater electrode 1 / 22, electrostatic adsorption electrode 124 (see FIG. 2)), a shaft 130, power supply lines 140 and 142 (see FIG. 2), and a thermocouple 171 which is a temperature measuring body (see FIG. 2).

[0010] The ceramic substrate 110 is a circular, plate-shaped component with a diameter of 12 inches (approximately 300 mm), and the wafer 10 to be heated is placed on top of the ceramic substrate 110. In Figure 1, the wafer 10 and the ceramic substrate 110 are shown separated for clarity. As shown in Figure 1, the upper surface 111 of the ceramic substrate 110 is provided with an annular protrusion 152 (hereinafter simply referred to as the annular protrusion 152) and a plurality of protrusions 156. In Figure 1, the number of the plurality of protrusions 156 is reduced for clarity. Also, as shown in Figure 2, a first gas channel 164, which will be described later, is formed inside the ceramic substrate 110. The ceramic substrate 110 can be formed from, for example, a ceramic sintered body of aluminum nitride, silicon carbide, alumina, silicon nitride, etc.

[0011] As shown in Figures 1 and 2, the annular projection 152 is an annular projection located on the outer periphery (outer edge) of the upper surface 111 of the ceramic substrate 110, and protrudes upward from the upper surface 111. As shown in Figure 2, when the wafer 10 is placed on the ceramic substrate 110, the upper surface 152a of the annular projection 152 abuts against the lower surface of the wafer 10. In other words, when the wafer 10 is placed on the ceramic substrate 110, the annular projection 152 is positioned to overlap with the wafer 10 in the vertical direction 5. On the upper surface 111 of the ceramic substrate 110, inside the annular projection 152, there are multiple projections 156. All of the multiple projections 156 have a cylindrical shape. As shown in Figure 2, one of the multiple projections 156 is located approximately in the center of the upper surface 111. The remaining projections 156 are arranged on the circumference of four concentric circles arranged at equal intervals. Furthermore, the protrusions 156 are arranged at equal intervals along the circumference of each concentric circle. The concentric circles, positions, and / or number of protrusions 156 are set as appropriate according to the application, function, and purpose.

[0012] The height of the annular convex portion 152 can be in the range of 5 μm to 2 mm. Similarly, the height of the plurality of convex portions 156 can also be in the range of 5 μm to 2 mm. In the present embodiment, the height of the annular convex portion 152 is the same as the height of the plurality of convex portions 156. In other words, the upper surface 152a of the annular convex portion 152 and the upper surfaces 156a of the plurality of convex portions 156 are flush. In the present specification, the height of the annular convex portion 152 and the height of the plurality of convex portions 156 are defined as the vertical length from the upper surface 111 of the ceramic substrate 110. When the upper surface 111 of the ceramic substrate 110 is not flat, for example, has a step, it is defined as the vertical length from the highest position among the upper surfaces 111 of the ceramic substrate 110.

[0013] The width of the upper surface 152a of the annular convex portion 152 is preferably a constant width and can be 0.1 mm to 10 mm. The surface roughness Ra of the upper surface 152a of the annular convex portion 152 can be 1.6 μm or less. Similarly, the surface roughness Ra of the upper surfaces 156a of the plurality of convex portions 156 can be 1.6 μm or less. The surface roughness Ra of the upper surface 152a of the annular convex portion 152 and the upper surfaces of the plurality of convex portions 156 is preferably 0.4 μm or less, more preferably 0.2 μm or less, and even more preferably 0.1 μm or less.

[0014] The upper surfaces 156a of the plurality of convex portions 156 are preferably circular with a diameter of 0.1 mm to 5 mm. Also, the spacing distance between the respective convex portions of the plurality of convex portions 156 can be in the range of 1.5 mm to 30 mm. [[ID=⑨]] [[ID=⑩]]

[0015] [[ID=⑪]] As described above, on the upper surface 111 of the ceramic substrate 110, the multiple protrusions 156 are arranged on the circumference of four concentric circles. As shown in Figure 2, an opening 164a of the first gas channel 164 is formed between the innermost concentric circle on the upper surface 111 where the multiple protrusions 156 are arranged and the second concentric circle from the inside. The first gas channel 164 is a gas channel with an opening 164a and is formed inside the ceramic substrate 110. The first gas channel 164 extends downward from the opening 164a. As shown in Figure 2, the lower end of the first gas channel 164 is joined to the upper end of the second gas channel 168 formed inside the shaft 130.

[0016] The first gas channel 164 can be used as a channel for supplying gas to the space (gap) defined by the upper surface 111 of the ceramic substrate 110 and the lower surface of the wafer 10. For example, it can supply heat transfer gas for heat transfer between the wafer 10 and the ceramic substrate 110. As the heat transfer gas, for example, an inert gas such as helium or argon, or nitrogen gas can be used. The heat transfer gas is supplied through the first gas channel 164 at a pressure set within the range of 100 Pa to 40000 Pa. In addition, if process gas enters the gap inside the annular protrusion 152 from the gap between the upper surface 152a of the annular protrusion 152 and the lower surface of the wafer 10, the gas can be exhausted through the first gas channel 164. In this case, the differential pressure between the pressure outside the gap and the pressure inside the gap can be adjusted by adjusting the exhaust pressure. This makes it possible to adsorb the wafer 10 toward the upper surface of the ceramic substrate 110.

[0017] <Inner heater electrode 120 and outer heater electrode 122> As shown in Figure 2, an inner heater electrode 120, an outer heater electrode 122, and an electrostatic adsorption electrode 124 are embedded inside the ceramic substrate 110. In this specification, the inner heater electrode 120 and the outer heater electrode 122 may be collectively referred to simply as heater electrodes. The inner heater electrode 120, the outer heater electrode 122, and the electrostatic adsorption electrode 124 may be collectively referred to simply as electrodes.

[0018] As shown in Figure 2, the inner heater electrode 120 is located above the outer heater electrode 122. The inner heater electrode 120 is formed by cutting a heat-resistant metal (a high melting point metal with a melting point of 2000°C or higher), such as a mesh or foil made of tungsten (W), molybdenum (Mo), or an alloy containing molybdenum and / or tungsten, into a strip as shown in Figure 3(a). Similarly, the outer heater electrode 122 is formed by cutting a metal mesh or foil into the shape shown in Figure 3(b). As shown in Figure 3(b), the outer heater electrode 122 has a substantially annular heater portion 122a and a conductive portion 122b located inside the heater portion 122a. The conductive portion 122b has less resistance than the heater portion 122a and does not contribute much to heating. The conductive portion 122b has a semi-circular shape that is substantially concentric with the inner heater electrode 120. In a top view, the conductive portion 122b and the inner heater electrode 120 are arranged to almost overlap, with the heater portion 122a surrounding them. The inner heater electrode 120 and the heater portion 122a of the outer heater electrode 122 are examples of multiple heating elements of the present invention. The inner heater electrode 120 is an example of an inner heating element of the present invention, and the heater portion 122a of the outer heater electrode 122 is an example of an outer heating element of the present invention.

[0019] In this embodiment, the outer diameter of the heater portion 122a of the outer heater electrode 122 is 298 mm, and the outer heater electrode 122 is not exposed from the side surface of the ceramic substrate 110. A terminal portion 121 for connection to the power supply line 140 (see Figure 2) is provided approximately in the center of the inner heater electrode 120. A terminal portion 123 for connection to the power supply line 141 (see Figure 2) is provided approximately in the center of the conductive portion 122b of the outer heater electrode 122. In addition, a relief is formed approximately in the center of the conductive portion 122b of the outer heater electrode 122 for passing a power supply line (not shown) connected to the electrostatic adsorption electrode 124.

[0020] As described above, the inner heater electrode 120 and the outer heater electrode 122 are formed from a heat-resistant metal (high melting point metal) such as a mesh or foil woven from wires of tungsten (W), molybdenum (Mo), or an alloy containing molybdenum and / or tungsten. The purity of the tungsten and molybdenum is preferably 99% or higher. The thickness of the inner heater electrode 120 and the outer heater electrode 122 is 0.15 mm or less. From the viewpoint of increasing the resistance value of the heater portion 122a of the inner heater electrode 120 and the outer heater electrode 122, it is preferable to make the wire diameter of the mesh 0.1 mm or less, or the thickness of the foil 0.1 mm or less. Furthermore, the width of the strip-cut inner heater electrode 120 and the width of the heater portion 122a of the outer heater electrode 122 is preferably 2.5 mm to 20 mm, and more preferably 5 mm to 15 mm. In this embodiment, the inner heater electrode 120 and the outer heater electrode 122 are cut into the shapes shown in Figures 3(a) and (b). However, the shapes of the inner heater electrode 120 and the outer heater electrode 122 are not limited to these and can be changed as appropriate.

[0021] <Electrostatic adsorption electrode 124> As shown in Figure 2, an electrostatic adsorption electrode 124 is embedded inside the ceramic substrate 110, above the inner heater electrode 120 and the outer heater electrode 122. As shown in Figure 3(c), the electrostatic adsorption electrode 124 consists of two semicircular electrodes 124a and 124b arranged facing each other with a predetermined distance (5 mm) between them, and has an overall approximately circular shape. The outer diameter of the electrostatic adsorption electrode 124 is 294 mm. Terminal portions 125, connected to a power supply line (not shown), are provided approximately in the center of electrodes 124a and 124b of the electrostatic adsorption electrode 124.

[0022] <Shaft 130 and connecting protrusion 114> As shown in Figures 1 and 2, a shaft 130 is connected to the lower surface 113 of the ceramic substrate 110. The shaft 130 has a hollow, substantially cylindrical cylindrical portion 131 and a large-diameter portion 132 (see Figure 1) located below the cylindrical portion 131. The large-diameter portion 132 has a larger diameter than the cylindrical portion 131. In the following description, the longitudinal direction of the cylindrical portion 131 is defined as the longitudinal direction 6 of the shaft 130. As shown in Figure 1, in the operating state of the ceramic heater 100, the longitudinal direction 6 of the shaft 130 is parallel to the vertical direction 5.

[0023] The lower surface 113 of the ceramic substrate 110 may be a flat surface, but as shown in Figure 2, a protrusion 114 for joining with the shaft 130 (hereinafter referred to as the joining protrusion 114) may be provided. The shape of the joining protrusion 114 is preferably the same as the shape of the upper surface of the shaft 130 to be joined, and the diameter of the joining protrusion 114 is preferably 100 mm or less. The height of the joining protrusion 114 (height from the lower surface 113) may be 0.2 mm or more, and preferably 5 mm or more. There is no particular upper limit on the height, but considering the ease of manufacturing, the height of the joining protrusion 114 is preferably 20 mm or less. In addition, the lower surface of the joining protrusion 114 is preferably parallel to the lower surface 113 of the ceramic substrate 100. The surface roughness Ra of the lower surface of the joining protrusion 114 may be 1.6 μm or less. Furthermore, the surface roughness Ra of the lower surface of the bonding protrusion 114 is preferably 0.4 μm or less, and more preferably 0.2 μm or less.

[0024] The upper surface of the cylindrical portion 131 is fixed to the lower surface 113 of the ceramic base material 110 (or the lower surface of the joining projection 114 if one is provided). The shaft 130 may be formed from a ceramic sintered body such as aluminum nitride, silicon carbide, alumina, or silicon nitride, similar to the ceramic base material 110. Alternatively, to improve heat insulation, it may be formed from a material with lower thermal conductivity than the ceramic base material 110. As shown in Figure 4, an enlarged diameter portion 133 similar to the large diameter portion 132 provided below the cylindrical portion 131 may be provided on the upper surface of the cylindrical portion 131. For example, the outer diameter of the large diameter portion 132 can be made the same as the outer diameter of the joining projection 114.

[0025] As shown in Figure 2, the shaft 130 has a hollow cylindrical shape, and a through hole extending in the longitudinal direction 6 (see Figure 1) is formed inside it (the region inside the inner diameter). A power supply line 140 for supplying power to the inner heater electrode 120 and a power supply line 142 for supplying power to the outer heater electrode 122 are arranged in the hollow portion (through hole) of the shaft 130. Although not shown, another power supply line connected to the terminal portion 125 (see Figure 3(c)) of the electrostatic adsorption electrode 124 is also arranged in the hollow portion (through hole) of the shaft 130. The upper end of the power supply line 140 is electrically connected to the terminal portion 121 (see Figure 3(a)) located in the center of the inner heater electrode 120. Similarly, the upper end of the power supply line 142 is electrically connected to the terminal portion 123 (see Figure 3(b)) located in the center of the outer heater electrode 122. The power supply lines 140 and 142 are connected to a heater power supply (not shown), respectively. This allows power to be supplied individually to the inner heater electrode 120 and the outer heater electrode 122 via the power supply lines 140 and 142.

[0026] Furthermore, as shown in Figure 2, a second gas passage 168 extending in the vertical direction 5 is formed in the cylindrical portion 131 of the shaft 130. As described above, the upper end of the second gas passage 168 is connected to the lower end of the first gas passage 164. In addition, a portion of a TC wiring hole 170 for inserting a thermocouple 171 is formed in the cylindrical portion 131 of the shaft 130.

[0027] <Thermocouple 171> As shown in Figure 2, a TC wiring hole 170 (see Figure 5(e)) for inserting a thermocouple 171 is formed in the cylindrical portion 131 of the shaft 130 and the ceramic substrate 110, and the thermocouple 171 is inserted along the TC wiring hole 170. A temperature sensing junction 171a is provided at the tip of the thermocouple 171. In this embodiment, a SUS sheathed thermocouple with a diameter of 1.6 mm is used as the thermocouple 171, and the diameter of the TC wiring hole 170 is 3 mm. The thermocouple 171 is an example of the temperature sensing element of the present invention, and the temperature sensing junction 171a is an example of the temperature sensing part of the present invention. Two thermocouples 171 are shown in Figure 2, but in this embodiment, three thermocouples 171 are provided in the ceramic substrate 110. The thermometer junction 171a of the thermocouple 171 can be positioned at any appropriate location, but in this embodiment, the TC wiring hole is formed so that the thermometer junction 171a is positioned at positions A to C shown in Figure 3(a). Positions A and C are positions that do not overlap with the inner heater electrode 120 in the vertical direction 5, and position B is a position that overlaps with the inner heater electrode 120 in the vertical direction 5. Here, as shown in Figure 3(a), the inner heater electrode 120 forms a substantially circular gap GP1 in the center, a linear gap GP2 extending radially through gap GP1, and three arc-shaped gaps GP3 to GP5 concentrically surrounding gap GP1. Position A corresponds to the position where the linear gap GP2 and the arc-shaped gap GP5 intersect, and position C corresponds to the position where the linear gap GP2 and the arc-shaped gap GP4 intersect.

[0028] <Manufacturing method for ceramic heater 100> A method for manufacturing the ceramic heater 100 will be described below. In the following explanation, the case in which the ceramic base material 110 and shaft 130 are formed from aluminum nitride will be used as an example.

[0029] First, the method for manufacturing the ceramic substrate 110 will be described. As shown in Figure 5(a), a binder is added to granulated powder P mainly composed of aluminum nitride (AlN) powder, and then CIP molding is performed to process it into a disc shape to produce multiple aluminum nitride molded bodies 510. Preferably, the granulated powder P contains 5 wt% or less of a sintering aid (for example, Y2O3). Next, as shown in Figure 5(b), the molded bodies 510 are degreased to remove the binder.

[0030] As shown in Figure 5(c), recesses 511 for embedding the inner heater electrode 120, outer heater electrode 122, and electrostatic adsorption electrode 124, and recesses 512 which become part of the TC wiring hole are formed in the degreased molded body 510. Recesses 511 and 512 may be formed in the molded body 510 in advance.

[0031] An inner heater electrode 120, an outer heater electrode 122, and an electrostatic adsorption electrode 124 are placed in the recess 511 of the molded body 510, and another molded body 510 is stacked on top. Here, pellets made of tungsten, molybdenum, or an alloy containing at least one of these may be embedded in positions that overlap with terminals 121 and 123 (see Figures 3(a) and (b)). If pellets are embedded, a paste of high-melting-point metal powder such as tungsten or molybdenum may be applied between the inner heater electrode 120 and the pellet, and between the outer heater electrode 122 and the pellet, if necessary. This can improve the adhesion between the electrodes and the pellets.

[0032] As shown in Figure 5(d), a stack of molded bodies 510 are fired (uniaxial hot press firing) while pressed together to produce a fired body. The pressure applied during firing is preferably 1 MPa or more. Furthermore, it is preferable to fire at a temperature of 1800°C or higher.

[0033] As shown in Figure 5(e), blind holes are drilled up to the inner heater electrode 120 and the outer heater electrode 122 to form the terminal portions 121 and 123. If pellets are embedded, blind holes only need to be drilled up to the pellets. Blind holes are also drilled to form the TC wiring holes 170. Furthermore, through holes are formed to become part of the first gas flow path 164. This makes it possible to manufacture a ceramic substrate 110 with the first gas flow path 164 formed inside. In this case, predetermined reliefs are provided on the electrodes in advance so that the electrodes are not exposed from the first gas flow path 164.

[0034] The upper surface 111 of the ceramic substrate 110 formed in this manner is ground and lapped (mirror polished). Furthermore, sandblasting is performed on the upper surface 111 to form a plurality of protrusions 156 and an annular protrusion 152 on the upper surface 111. At this time, the annular protrusion 152 and the plurality of protrusions 156 are processed to be the same height. Although sandblasting is preferred as the processing method for forming the plurality of protrusions 156 and the annular protrusion 152, other processing methods can also be used. The lower surface 113 of the ceramic substrate 110 may be provided with a joining protrusion 114 that protrudes from the lower surface 113.

[0035] Next, the manufacturing method of the shaft 130 and the method of joining the shaft 130 to the ceramic substrate 110 will be described. First, granulated aluminum nitride powder P with several wt% binder added is molded under hydrostatic pressure (approximately 1 MPa) to process the molded body into a predetermined shape. At this time, a through hole that will become the second gas passage 168 is formed in the molded body. The outer diameter of the shaft 130 is approximately 30 mm to 100 mm. A flange portion 133 having a diameter larger than the outer diameter of the cylindrical portion 131 may be provided at the end face of the cylindrical portion 131 of the shaft 130 (see Figure 4). The length of the cylindrical portion 131 can be, for example, 50 mm to 500 mm. After processing the molded body into a predetermined shape, the molded body is fired in a nitrogen atmosphere. For example, it is fired at a temperature of 1900°C for 2 hours. Then, the shaft 130 is formed by processing the sintered body into a predetermined shape after firing. The upper surface of the cylindrical portion 131 and the lower surface 113 of the ceramic substrate 110 can be fixed by diffusion bonding at a temperature of 1600°C or higher and a uniaxial pressure of 1 MPa or higher. In this case, the surface roughness Ra of the lower surface 113 of the ceramic substrate 110 is preferably 0.4 μm or less, and more preferably 0.2 μm or less. Alternatively, the upper surface of the cylindrical portion 131 and the lower surface 113 of the ceramic substrate 110 can also be bonded using a bonding agent. As a bonding agent, for example, an AlN bonding paste with 10 wt% Y2O3 added can be used. For example, the above AlN bonding paste can be applied to the interface between the upper surface of the cylindrical portion 131 and the lower surface 113 of the ceramic substrate 110 to a thickness of 15 μm, and the bonding can be achieved by heating at a temperature of 1700°C for 1 hour while applying a force of 5 kPa in a direction perpendicular to the upper surface 111 (the longitudinal direction of the shaft 130 6). Alternatively, the upper surface of the cylindrical portion 131 and the lower surface 113 of the ceramic base material 110 can be fixed together by screwing, brazing, or the like. [Examples]

[0036] The present invention will be further described below using Examples 1 to 15. However, the present invention is not limited to the examples described below. Figure 6 shows a table summarizing the comparative examples and the results of Examples 1 to 15 shown below.

[0037] [Example 1] The ceramic heater 100 of Example 1 will now be described. In Example 1, a ceramic substrate 110 with a diameter of 310 mm was fabricated using the above-described method, with aluminum nitride (AlN) to which 5 wt% of a sintering aid (Y2O3) had been added as the raw material. As shown in Figure 7, the thickness D0 of the ceramic substrate 110 is 25 mm. For the inner heater electrode 120, a molybdenum mesh (wire diameter 0.1 mm, mesh size #50, plain weave) was cut into the shape shown in Figure 3(a) and fabricated. Similarly, for the outer heater electrode 122, the same molybdenum mesh was cut into the shape shown in Figure 3(b) and fabricated. Furthermore, an electrostatic adsorption electrode 124 in the shape shown in Figure 3(c) was fabricated, and these electrodes were embedded in the ceramic substrate 110. The vertical distance D2 (see Figure 7) from the top surface 111 of the ceramic substrate 110 to the inner heater electrode 120 is 8 mm. Furthermore, in Example 1, the ratio of the distance D2 to the thickness D0 of the ceramic substrate 110 (D2 / D0) is 0.32.

[0038] Furthermore, three thermocouples 171 are embedded in the ceramic substrate 110. The temperature sensing junctions 171a at the tips of the three thermocouples 171 are positioned at positions A to C shown in Figure 3(a). The vertical distance D1 (see Figure 7) from the upper surface 111 of the ceramic substrate 110 to the temperature sensing junctions 171 is 4 mm. As shown in Figure 7, the portion of the TC wiring hole 170 in which the thermocouples 171 are positioned, extending radially perpendicular to the vertical direction 5, is located above the inner heater electrode 120 in the vertical direction 5.

[0039] The diameter of the opening 164a of the first gas flow path 164 is 3 mm. The center of the opening 164a is located 30 mm from the center of the ceramic substrate 110.

[0040] A ceramic heater 100 of this shape was installed in the process chamber. Argon gas was supplied into the process chamber as the process gas at a pressure of 26600 Pa (200 Torr). Furthermore, the argon gas was adjusted to a pressure of 6650 Pa (50 Torr) through the first gas flow path 164.

[0041] The temperature of the ceramic heater 100 was then evaluated using the following procedure. First, a silicon wafer for temperature evaluation was placed on the ceramic substrate 110, and an external power supply (not shown) was connected to the inner heater electrode 120 and outer heater electrode 122 of the ceramic heater 100. Process gas and heat transfer gas were introduced at the above pressure, and the output power of the external power supply was adjusted so that the temperature of the ceramic substrate 110 was approximately 500°C in a steady state. In Example 1, the temperature of the ceramic substrate 110 was controlled using thermocouple 171, of the three thermocouples 171, with the temperature sensing junction 171a positioned at position A (see Figure 3(a)).

[0042] After the ceramic substrate 110 reached a steady temperature, the temperature distribution of the silicon wafer used for temperature evaluation was measured using an infrared camera. For measuring the temperature distribution of the silicon wafer used for temperature evaluation, the measurement area was defined as a 30mm diameter region centered on the position on the top surface of the silicon wafer used for temperature evaluation, corresponding to position A where the temperature sensing junction 171a used for temperature control of the ceramic substrate 110 was located. The difference between the highest and lowest temperatures within the measurement area was defined as the temperature difference Δ. A smaller temperature difference Δ allows for more uniform heating of the silicon wafer used for temperature evaluation, unaffected by the heater electrode pattern. The silicon wafer used for temperature evaluation was a 300mm diameter silicon wafer with a 30μm thick blackbody film coated on its top surface. A blackbody film is a film with an emissivity (radiative efficiency) of 90% or more, and can be formed, for example, by coating with a blackbody paint primarily composed of carbon nanotubes.

[0043] As described above, in Example 1, the temperature of the ceramic substrate 110 was adjusted using a thermocouple 171 with a temperature sensing junction 171a positioned at position A (see Figure 3(a)). In Example 1, the temperature difference Δ in the measurement area corresponding to position A of the silicon wafer for temperature evaluation was 1.1°C.

[0044] [Example 2] In Example 2, the temperature of the ceramic substrate 110 was adjusted using a thermocouple 171 with a temperature sensing junction 171a positioned at position C (see Figure 3(a)). Except for this point, Example 2 was the same as Example 1. In Example 2, the temperature difference Δ in the measurement area corresponding to position C of the silicon wafer for temperature evaluation was 0.9°C.

[0045] [Comparative Example] In the comparative example, the temperature of the ceramic substrate 110 was adjusted using a thermocouple 171 with a temperature sensing junction 171a positioned at position B (see Figure 3(a)). In other words, the temperature of the ceramic substrate 110 was adjusted using a thermocouple 171 with a temperature sensing junction 171a positioned in the vertical direction 5, overlapping with the inner heater electrode 120. Except for this point, the comparative example was the same as in Example 1. In the comparative example, the temperature difference Δ in the measurement area corresponding to position B of the silicon wafer for temperature evaluation was 2.6°C.

[0046] [Example 3] In Example 3, as shown in Figure 8, the portion of the TC wiring hole 170 in which the thermocouple 171 is placed that extends radially perpendicular to the vertical direction 5 is located below the outer heater electrode 122 in the vertical direction 5. Except for this point, Example 3 is the same as Example 1. In Example 3, the temperature difference Δ in the measurement area corresponding to position A of the silicon wafer for temperature evaluation was 1.2°C.

[0047] [Example 4] In Example 4, as in Example 3, the portion of the TC wiring hole 170 in which the thermocouple 171 is placed that extends radially perpendicular to the vertical direction 5 is located below the outer heater electrode 122 in the vertical direction 5 (see Figure 8). Furthermore, in Example 4, the temperature of the ceramic substrate 110 was adjusted using a thermocouple 171 with a temperature sensing junction 171a placed at position C (see Figure 3(a)). Except for these points, Example 4 is the same as Example 1. In Example 4, the temperature difference Δ in the measurement area corresponding to position C of the silicon wafer for temperature evaluation was 1.0°C.

[0048] [Example 5] In Examples 5 to 11, similar to Example 1, the portion of the TC wiring hole 170 in which the thermocouple 171 is placed that extends radially perpendicular to the vertical direction 5 is located above the inner heater electrode 120 in the vertical direction 5 (see Figure 7). In Examples 5 to 11, the temperature of the ceramic substrate 110 was adjusted using a thermocouple 171 with a temperature sensing junction 171a placed at position A (see Figure 3(a)). In Example 5, the distance D1 in the vertical direction 5 from the upper surface 111 of the ceramic substrate 110 to the temperature sensing junction 171 (see Figure 7) was set to 1 mm. Except for this point, Example 5 is the same as Example 1. In Example 5, the temperature difference Δ in the measurement area corresponding to position A of the silicon wafer for temperature evaluation was 1.4°C.

[0049] [Example 6] In Example 6, the vertical distance D1 (see Figure 7) from the upper surface 111 of the ceramic substrate 110 to the temperature sensing junction 171 was set to 2 mm. Except for this point, Example 6 is the same as Example 1. In Example 6, the temperature difference Δ in the measurement area corresponding to position A of the silicon wafer for temperature evaluation was 1.3°C.

[0050] [Example 7] In Example 7, the vertical distance D1 (see Figure 7) from the upper surface 111 of the ceramic substrate 110 to the temperature sensing junction 171 was set to 3 mm. Except for this point, Example 7 is the same as Example 1. In Example 7, the temperature difference Δ in the measurement area corresponding to position A of the silicon wafer for temperature evaluation was 1.2°C.

[0051] [Example 8] In Example 8, the vertical distance D1 (see Figure 7) from the upper surface 111 of the ceramic substrate 110 to the temperature sensing junction 171 was set to 6 mm. Except for this point, Example 8 was the same as Example 1. In Example 8, the temperature difference Δ in the measurement area corresponding to position A of the silicon wafer for temperature evaluation was 0.9°C.

[0052] [Example 9] In Example 9, the vertical distance D2 (see Figure 7) from the top surface 111 of the ceramic substrate 110 to the inner heater electrode 120 was set to 5 mm, and the vertical distance D1 (see Figure 7) from the top surface 111 of the ceramic substrate 110 to the temperature sensing junction 171 was set to 2 mm. The ratio of the distance D2 to the thickness D0 of the ceramic substrate 110 (D2 / D0) is 0.2. Except for these points, Example 9 is the same as Example 1. In Example 9, the temperature difference Δ in the measurement area corresponding to position A of the silicon wafer for temperature evaluation was 1.6°C.

[0053] [Example 10] In Example 10, the vertical distance D2 (see Figure 7) from the top surface 111 of the ceramic substrate 110 to the inner heater electrode 120 was set to 12 mm, and the vertical distance D1 (see Figure 7) from the top surface 111 of the ceramic substrate 110 to the temperature sensing junction 171 was set to 6 mm. The ratio of the distance D2 to the thickness D0 of the ceramic substrate 110 (D2 / D0) is 0.48. Except for these points, Example 10 is the same as Example 1. In Example 10, the temperature difference Δ in the measurement area corresponding to position A of the silicon wafer for temperature evaluation was 0.7°C.

[0054] [Example 11] In Example 11, the vertical distance D2 (see Figure 7) from the top surface 111 of the ceramic substrate 110 to the inner heater electrode 120 was set to 12 mm, and the vertical distance D1 (see Figure 7) from the top surface 111 of the ceramic substrate 110 to the temperature sensing junction 171 was set to 3 mm. The ratio of the distance D2 to the thickness D0 of the ceramic substrate 110 (D2 / D0) is 0.48. Except for these points, Example 11 is the same as Example 1. In Example 11, the temperature difference Δ in the measurement area corresponding to position A of the silicon wafer for temperature evaluation was 0.9°C.

[0055] [Example 12] In Example 12, similar to Example 1, the portion of the TC wiring hole 170 in which the thermocouple 171 is placed that extends radially perpendicular to the vertical direction 5 is located above the inner heater electrode 120 in the vertical direction 5 (see Figure 7). In Example 12, the temperature of the ceramic substrate 110 was adjusted using a thermocouple 171 with a temperature sensing junction 171a placed at position B (see Figure 3(a)). However, to prevent the temperature sensing junction 171a and the inner heater electrode 120 from overlapping in the vertical direction 5, an opening 120h was formed in the inner heater electrode 120 at a position overlapping with the temperature sensing junction 171a, as shown in Figure 9. As a result, the temperature sensing junction 171a placed at position B (see Figure 3(a)) does not overlap with the inner heater electrode 120 in the vertical direction 5. Except for these points, Example 12 is the same as Example 1. In Example 12, the temperature difference Δ in the measurement area corresponding to position B of the silicon wafer used for temperature evaluation was 1.2°C.

[0056] [Example 13] In Example 13, similar to Example 1, the portion of the TC wiring hole 170 in which the thermocouple 171 is placed that extends radially perpendicular to the vertical direction 5 is located above the inner heater electrode 120 in the vertical direction 5 (see Figure 7). In Example 13, the portion of the TC wiring hole 170 in which the thermocouple 171 is placed that extends radially perpendicular to the vertical direction 5 has a curved portion C1 in a plane (horizontal plane) parallel to the upper surface 111 and lower surface 113 of the ceramic substrate 110, as shown in Figure 10. Except for this point, Example 13 is the same as Example 1. In Example 13, the temperature difference Δ in the measurement area corresponding to position A of the silicon wafer for temperature evaluation was 1.1°C.

[0057] [Example 14] In Example 14, similar to Example 3, the portion of the TC wiring hole 170 in which the thermocouple 171 is placed that extends radially perpendicular to the vertical direction 5 is located below the outer heater electrode 122 in the vertical direction 5 (see Figure 11). Furthermore, as shown in Figure 11, the portion of the TC wiring hole 170 in which the thermocouple 171 is placed that extends radially perpendicular to the vertical direction 5 is not parallel to the upper surface 111 and lower surface 113 of the ceramic substrate 110. In Example 14, the portion of the TC wiring hole 170 in which the thermocouple 171 is placed that extends radially perpendicular to the vertical direction 5 is not parallel to the upper surface 111 and lower surface 113 of the ceramic substrate 110, as shown in Figure 11, and has a curved portion C2 in a plane parallel to the vertical direction 5. Except for this point, Example 14 is the same as Example 1. In Example 14, the temperature difference Δ in the measurement area corresponding to position A of the silicon wafer for temperature evaluation was 1.1°C.

[0058] [Example 15] In Example 15, similar to Example 1, the portion of the TC wiring hole 170 in which the thermocouple 171 is placed that extends radially perpendicular to the vertical direction 5 is located above the inner heater electrode 120 in the vertical direction 5 (see Figure 12). However, as shown in Figure 12, compared to Example 1 (Figure 7), the inner heater electrode 120 and the outer heater electrode 122 are embedded at a position further away from the upper surface 111 of the ceramic substrate 110. Specifically, in Example 15, the vertical distance D2 (see Figure 7) from the upper surface 111 of the ceramic substrate 110 to the inner heater electrode 120 is 16 mm. The ratio of the distance D2 to the thickness D0 of the ceramic substrate 110 (D2 / D0) is 0.64. Except for this point, Example 15 is the same as Example 1. In Example 15, the temperature difference Δ in the measurement area corresponding to position A of the silicon wafer for temperature evaluation was 0.4°C.

[0059] <Effects of the Embodiment> In the above embodiments and examples 1 to 15, the ceramic heater 100 comprises a ceramic substrate 110 and a plurality of heating elements (inner heater electrode 120 and heater portion 122a of outer heater electrode 122) embedded in the ceramic substrate 110. The ceramic substrate 110 is provided with a plurality of thermocouples 171, each with an embedded temperature sensing junction 171a. Of the plurality of thermocouples 171, at least one thermocouple 171 (for example, a thermocouple 171 whose temperature sensing junction 171a is located at positions A and C (see Figure 3(a))) has a temperature sensing junction 171a that does not overlap vertically with the heater portion 122a of the inner heater electrode 120 and outer heater electrode 122. In other words, the temperature sensing junction 171a overlaps with the ceramic sintered body located between the heater electrodes 122 in the ceramic substrate 110.

[0060] For example, as shown in positions A and C above, the temperature sensing junction 171a of the thermocouple 171 can be positioned in a location that overlaps vertically with the intersection region where multiple gaps (GP1 to GP5) formed by the heater electrode intersect (see Examples 1 to 11 and 13 to 15). Also, as shown in Example 12, the temperature sensing junction 171a of the thermocouple 171 can be positioned in a location that overlaps vertically with an opening provided in the heater electrode.

[0061] As described above, in the comparative example, the temperature of the ceramic substrate 110 was controlled using a thermocouple 171 positioned so that the temperature sensing junction 171a overlapped vertically with the inner heater electrode 120. In this case, the temperature difference Δ within the measurement area, as defined above, was a relatively large value (2.6°C). In contrast, in Examples 1 to 15, the temperature of the ceramic substrate 110 was controlled using a thermocouple 171a positioned so that the temperature sensing junction 171a did not overlap vertically with the inner heater electrode 120 and the heater portion 122a of the outer heater electrode 122. In this case, the temperature difference Δ within the measurement area could be kept within 1.6°C. From this, it was found that controlling the temperature of the ceramic substrate 110 using a thermocouple 171a positioned so that the temperature sensing junction 171a does not overlap vertically with the inner heater electrode 120 and the heater portion 122a of the outer heater electrode 122 contributes to improving the uniformity of the temperature of a wafer to be heated, such as a silicon wafer for temperature evaluation.

[0062] In this embodiment, the vertical distance D1 from the upper surface 111 of the ceramic substrate 110 to the temperature sensing junction 171 can be set to 1 mm ≤ D1 ≤ 4 mm. Generally, the temperature of the upper surface of the silicon wafer used for temperature measurement, as measured by an infrared camera, is slightly lower than the temperature measured by the thermocouple 171 embedded in the ceramic substrate 110. By setting the vertical distance D1 from the upper surface 111 of the ceramic substrate 110 to the temperature sensing junction 171 to 1 mm ≤ D1 ≤ 4 mm, the temperature measured by the thermocouple 171 embedded in the ceramic substrate 110 can be brought closer to the temperature of the upper surface of the silicon wafer used for temperature measurement, as measured by an infrared camera.

[0063] In this embodiment, the ratio D2 / D0 of the vertical distance D2 from the top surface 111 of the ceramic substrate 110 to the inner heater electrode 120 to the thickness D0 of the ceramic substrate 110 can be set to D2 / D0 ≤ 0.4. Furthermore, the vertical distance D1 from the top surface 111 of the ceramic substrate 110 to the temperature sensing junction 171 and the vertical distance D2 from the top surface 111 of the ceramic substrate 110 to the inner heater electrode 120 can be set to 1 mm ≤ D1 ≤ D2. As will be described later, the outer heater electrode 122 can also be positioned above the inner heater electrode 120 (see Figure 13). In this case, the ratio D2 / D0 of the vertical distance D2 from the top surface 111 of the ceramic substrate 110 to the outer heater electrode 122 to the thickness D0 of the ceramic substrate 110 can be set to D2 / D0 ≤ 0.4. Furthermore, the vertical distance D1 from the upper surface 111 of the ceramic substrate 110 to the temperature sensing junction 171 and the vertical distance D2 from the upper surface 111 of the ceramic substrate 110 to the outer heater electrode 122 can be set to 1 mm ≤ D1 ≤ D2.

[0064] By positioning the embedded heater electrode closer to the upper surface 111 of the ceramic substrate 110, temperature controllability for the wafer to be heated can be improved. Therefore, it is preferable to make the ratio D2 / D0 of the vertical distance D2 from the upper surface 111 of the ceramic substrate 110 to the heater electrode to a small value. The vertical distance D1 from the upper surface 111 of the ceramic substrate 110 to the temperature sensing junction 171 and the vertical distance D2 from the upper surface 111 of the ceramic substrate 110 to the heater electrode are set to 1 mm ≤ D1 ≤ D2. This allows the temperature sensing junction 171 to be positioned above the heater electrode. Furthermore, a sufficient gap can be secured between the temperature sensing junction 171 and the upper surface 111 of the ceramic substrate 110 for positioning, for example, an RF electrode.

[0065] In the above embodiment, the ratio D2 / D0 of the distance D2 from the upper surface 111 of the ceramic substrate 110 to the heater electrode in the vertical direction to the thickness D0 of the ceramic substrate 110 can be set to 0.5 ≤ D2 / D0 ≤ 0.9. By moving the position where the heater electrode is embedded away from the upper surface 111 of the ceramic substrate 110, a sufficient area can be secured inside the ceramic substrate 110 for forming the TC wiring hole 170 for arranging the thermocouple 171.

[0066] In the above embodiment, the thermocouple 171 is wired in a region inside the outer diameter of the shaft 130. Specifically, a portion of the TC wiring hole 170 for inserting the thermocouple 171 is formed in the cylindrical portion 131 of the shaft 130. Since the shaft 130 is provided in the ceramic heater 100, the thermal insulation between the member connected to the shaft 130 and the ceramic substrate 110 can be improved, and the uniform heating of the wafer to be heated can be improved. Furthermore, since the TC wiring hole 170 can be provided inside the shaft 130, the wiring of the thermocouple 171 becomes easier.

[0067] In this embodiment, as in Example 13, the portion of the TC wiring hole 170 in which the thermocouple 171 is placed that extends radially perpendicular to the vertical direction 5 may have a curved portion in the horizontal plane. Alternatively, as in Example 14, the portion of the TC wiring hole 170 in which the thermocouple 171 is placed that extends radially perpendicular to the vertical direction 5 may have a curved portion in a plane parallel to the vertical direction. In either case, when the thermocouple 171 is inserted into the TC wiring groove 170, the thermocouple 171 elastically deforms by bending upon contact with the wall surface of the TC wiring groove 170. As a result, the temperature sensing junction 171a at the tip of the thermocouple 171 is pressed against the end of the TC wiring groove 170, thereby improving the temperature sensing accuracy of the temperature sensing junction 171a. Note that the curved portion formed in the TC wiring hole 170 does not necessarily have to be curved; for example, it may be bent. The same effect can be achieved in this case as well.

[0068] <Change form> The embodiments described above are merely illustrative and can be modified as appropriate. For example, the thermocouple 171 is not limited to a SUS sheathed thermocouple, and any suitable thermocouple can be used. Furthermore, the thermometer is not limited to a thermocouple. For example, any thermometer can be used, such as a platinum resistance thermometer or an optical thermometer. The shape and cross-sectional shape of the TC wiring hole 170 can also be modified as appropriate to suit the thermometer. The shape and dimensions of the ceramic substrate 110 and shaft 130 are not limited to those of the embodiments described above and can be modified as appropriate. The height, width, and other dimensions of the annular protrusion 152, the vertical cross-sectional shape, and the surface roughness Ra of the upper surface can be modified as appropriate. The height of the multiple protrusions 156, the shape of the upper surface 156a, and the surface roughness Ra of the upper surface 156a can be modified as appropriate. The arrangement of the multiple protrusions 156 can also be modified as appropriate.

[0069] In the above embodiment, molybdenum, tungsten, or an alloy containing molybdenum and / or tungsten was used as the heater electrode, but the present invention is not limited to such embodiments. For example, metals or alloys other than molybdenum and tungsten can also be used. Furthermore, the shape (pattern) and arrangement of the heater electrodes can be changed as appropriate. For example, as shown in Figure 13, the outer heater electrode 122 can be placed above the inner heater electrode 120. In this case, the distance between the heater portion 122a of the outer heater electrode 122 that heats the outer periphery of the wafer to be heated and the wafer to be heated can be reduced, making it easier to adjust the temperature of the outer periphery of the wafer to be heated.

[0070] In the above embodiment, the ceramic heater 100 was equipped with a shaft 130, but the present invention is not limited to such an embodiment, and the ceramic heater 100 does not necessarily have to be equipped with a shaft 130. Furthermore, even if the ceramic heater 100 is equipped with a shaft 130, a second gas passage 168 extending in the vertical direction 5 is not required to be formed in the cylindrical portion 131 of the shaft 130. For example, instead of the second gas passage 168, a separate gas pipe can be provided in the hollow region of the cylindrical portion 131 (the region where the power supply line 140 is provided). Similarly, it is not necessarily required to provide a TC wiring hole 170 for arranging the thermocouple 171 inside the cylinder of the cylindrical portion 131, and for example, the thermocouple 171 can be wired in the hollow region of the cylindrical portion 131.

[0071] Although embodiments and modified versions of the invention have been described above, the technical scope of the present invention is not limited to the scope described above. It will be obvious to those skilled in the art that various modifications or improvements can be made to the above embodiments. It is also clear from the claims that such modified or improved forms may be included in the technical scope of the present invention.

[0072] The order in which each process in the manufacturing method shown in the specification and drawings is executed is not specifically defined, and unless the output of a previous process is used in a later process, the processes can be executed in any order. Even if phrases such as "first," and "next," are used for convenience, this does not mean that the processes must be performed in that order.

[0073] <Note> The present invention may include the following embodiments [1] to

[10] . [1] A ceramic substrate having an upper surface and a lower surface facing the upper surface in the vertical direction, Multiple heating elements embedded in the aforementioned ceramic substrate, The temperature sensing unit comprises a plurality of temperature sensing elements embedded in the ceramic substrate, A ceramic heater characterized in that, of the plurality of temperature-sensing elements, the temperature-sensing portion of at least one of the temperature-sensing elements is positioned so as not to overlap with the plurality of heating elements in the vertical direction. [2] The vertical distance D1 between the upper surface of the ceramic substrate and the temperature measuring portion of the at least one temperature measuring body is 1mm ≤ D1 ≤ 4mm The ceramic heater described in [1]. [3] The thickness D0 of the ceramic substrate in the vertical direction, The aforementioned distance D1 and, The vertical distance D2 between the upper surface of the ceramic substrate and at least one of the heating elements is D2 / D0 ≤ 0.4 and 1mm ≤ D1 ≤ D2 A ceramic heater as described in [1] or [2]. [4] The thickness D0 of the ceramic substrate in the vertical direction, The vertical distance D2 between the upper surface of the ceramic substrate and at least one of the heating elements is 0.5 ≤ D2 / D0 ≤ 0.9 A ceramic heater as described in [1] or [2]. [5] The plurality of heating elements are arranged to form a plurality of gaps, The ceramic heater according to any one of [1] to [4], wherein the temperature-measuring portion of at least one temperature-measuring body is arranged to overlap in the vertical direction with the intersection region where the plurality of gaps intersect. [6] Of the plurality of heating elements, at least one heating element has an opening formed therein. The ceramic heater according to any one of [1] to [5], wherein the temperature-measuring portion of at least one temperature-measuring body is arranged to overlap the opening in the vertical direction. [7] Furthermore, the ceramic substrate is provided with a shaft joined to the lower surface thereof, The ceramic heater according to any one of [1] to [6], wherein the plurality of temperature-sensing elements are wired in a region inside the outer diameter of the shaft. [8] Multiple wiring holes are formed inside the ceramic substrate, in which the multiple temperature measuring bodies are arranged. A ceramic heater according to any one of [1] to [7], wherein, among the plurality of wiring holes, the wiring hole in which at least one temperature measuring body is arranged has a first curved portion that extends in a curved or bent shape in a horizontal direction perpendicular to the vertical direction. [9] The ceramic substrate has multiple wiring holes in which the multiple temperature measuring bodies are arranged, A ceramic heater according to any one of [1] to [8], wherein, among the plurality of wiring holes, the wiring hole in which at least one temperature sensor is placed has a second curved portion that extends in a curved or bent shape in the vertical direction.

[10] The plurality of heating elements each have an outer heating element embedded in the outer peripheral portion of the ceramic substrate and an inner heating element embedded inside the outer heating element and below the outer heating element. A ceramic heater according to any one of [1] to [9], wherein the vertical distance between the temperature sensing portion of the at least one temperature sensing body and the outer heating element is smaller than the vertical distance between the temperature sensing portion of the at least one temperature sensing body and the inner heating element. [Explanation of Symbols]

[0074] 100 Ceramic Heaters 110 Ceramic substrate 120 Inner heater electrode 122 Outer heater electrode 130 shaft 140, 142 feeder line 152 Annular protrusion 156 Multiple protrusions

Claims

1. A ceramic substrate having an upper surface and a lower surface facing the upper surface in the vertical direction, Multiple heating elements embedded in the aforementioned ceramic substrate, The temperature sensing unit comprises a plurality of temperature sensing elements embedded in the ceramic substrate, Of the plurality of temperature measuring elements, the temperature measuring portion of at least one of the temperature measuring elements is positioned so as not to overlap with the plurality of heating elements in the vertical direction. The plurality of heating elements each have an outer heating element embedded in the outer peripheral portion of the ceramic substrate and an inner heating element embedded inside the outer heating element. Furthermore, it is provided with a conductive portion that is located at the same height as the outer heating element in the vertical direction, connected to the outer heating element, and overlapping with the inner heating element in the vertical direction, A ceramic heater characterized in that the temperature-measuring portion of at least one of the temperature-measuring bodies is positioned so as not to overlap with the conductive portion.

2. The vertical distance D1 between the upper surface of the ceramic substrate and the temperature-measuring portion of the at least one temperature-measuring body is 1 mm ≤ D1 ≤ 4 mm The ceramic heater according to claim 1.

3. The thickness D0 of the ceramic substrate in the vertical direction, The aforementioned distance D1 and, The vertical distance D2 between the upper surface of the ceramic substrate and at least one of the heating elements is D2 / D0 ≤ 0.4, and 1 mm ≤ D1 ≤ D2 The ceramic heater according to claim 2.

4. The thickness D0 of the ceramic substrate in the vertical direction, The vertical distance D2 between the upper surface of the ceramic substrate and at least one of the heating elements is 0.5 ≤ D2 / D0 ≤ 0.9 The ceramic heater according to claim 2.

5. The plurality of heating elements are arranged to form a plurality of gaps, The ceramic heater according to any one of claims 1 to 4, wherein the temperature-measuring portion of the at least one temperature-measuring body is arranged to overlap in the vertical direction with the intersection region where the plurality of gaps intersect.

6. A ceramic substrate having an upper surface and a lower surface facing the upper surface in the vertical direction, Multiple heating elements embedded in the aforementioned ceramic substrate, The temperature sensing unit comprises a plurality of temperature sensing elements embedded in the ceramic substrate, Of the plurality of temperature measuring elements, the temperature measuring portion of at least one of the temperature measuring elements is positioned so as not to overlap with the plurality of heating elements in the vertical direction. Of the plurality of heating elements, at least one heating element has an opening formed therein. A ceramic heater characterized in that the temperature-measuring portion of at least one temperature-measuring body is arranged to overlap with the opening in the vertical direction.

7. Furthermore, the ceramic substrate is provided with a shaft joined to the lower surface thereof. The ceramic heater according to any one of claims 1 to 4, wherein the plurality of temperature measuring elements are wired in a region inside the outer diameter of the shaft.

8. Multiple wiring holes are formed inside the ceramic substrate, in which the multiple temperature-sensing elements are arranged. The ceramic heater according to any one of claims 1 to 4, wherein, among the plurality of wiring holes, the wiring hole in which at least one temperature measuring body is arranged has a first curved portion that extends in a curved or bent shape in a horizontal direction perpendicular to the vertical direction.

9. Multiple wiring holes are formed inside the ceramic substrate, in which the multiple temperature-sensing elements are arranged. The ceramic heater according to any one of claims 1 to 4, wherein, among the plurality of wiring holes, the wiring hole in which at least one temperature measuring body is arranged has a second curved portion that extends in a curved or bent shape in the vertical direction.

10. The inner heating element is embedded below the outer heating element, The ceramic heater according to any one of claims 1 to 4, wherein the vertical distance between the temperature sensing portion of the at least one temperature sensing body and the outer heating element is smaller than the vertical distance between the temperature sensing portion of the at least one temperature sensing body and the inner heating element.

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