Ceramic heater and method for manufacturing a ceramic heater

Abstract

Provided is a ceramic heater that can improve heat uniformity of a plate and suppress crushing of a thermocouple passage, cracking of the plate, or the like when joining the plate and a shaft. The ceramic heater comprises: a sheet-like plate that has a first main surface on which a wafer is placed and a second main surface positioned at a distance from the first main surface in the thickness direction and that incorporates a resistance heating element which generates heat by energization; a cylindrical shaft that supports the plate on the second main surface; and a sheet-like auxiliary member that is joined to the plate. The plate has formed therein a groove that is recessed in a direction from the second main surface toward the first main surface and extends from a starting end positioned inside the shaft to a terminal end positioned outside the shaft. The auxiliary member includes a lid part which extends along an outside portion positioned outside the shaft in the groove and covers the outside portion, and a connection part which is sandwiched between the plate and the shaft and to which a tip part of the shaft is joined.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a ceramic heater and a method for manufacturing a ceramic heater. This application claims priority based on Japanese Patent Application No. 2024-137019 filed on August 16, 2024, and incorporates all contents described in said Japanese Patent Application by reference. BACKGROUND ART

[0002] For example, in semiconductor manufacturing equipment, ceramic heaters are used to heat wafers when performing processes such as chemical vapor deposition (CVD) and etching on the wafers. As shown in FIG. 41, a ceramic heater 100 includes a plate-shaped plate 101 and a cylindrical shaft 102. The plate 101 has a first main surface 103 and a second main surface 104 that are spaced apart in the thickness direction. A wafer is placed on the first main surface 103, and the shaft 102 is bonded to the second main surface 104.

[0003] The plate 101 incorporates a resistance heating element 105 formed of, for example, a coil containing molybdenum as a main component, and the entire plate 101 is heated by the resistance heating element 105. In order to confirm whether the entire plate 101 has a uniform temperature, a first thermocouple for detecting the temperature near the outer periphery and a second thermocouple for detecting the temperature near the center are attached to the plate 101.

[0004] Inside the plate 101, a cavity 106 serving as a thermocouple passage is formed to extend from the center of the plate 101 toward the outer periphery. Further, an opening 107 for inserting the first thermocouple is formed in the second main surface 104 of the plate 101 so as to communicate with the cavity 106. The first thermocouple is passed through the opening 107 into the cavity 106 in the plate 101, and the temperature near the outer periphery of the plate 101 is detected when the tip portion of the first thermocouple is positioned near the outer periphery of the plate 101.

[0005] As shown in Figure 42, conventional ceramic heaters are manufactured by bringing a shaft 102 into contact with the second main surface 104 of a plate 101 and joining them while heating and pressurizing them. A flux 108 is interposed between the plate 101 and the shaft 102. When a load is applied to the plate 101, which has a cavity 106 and an opening 107 formed therein, by the shaft 102, the portion 109 located above the cavity 106 in the plate 101 is prone to bending, which can cause the cavity 106 to be crushed by the portion 109. Alternatively, the portion 109 may cause a crack or fissure in the plate 101.

[0006] In contrast, Patent Document 1 focuses on the fact that the above-mentioned problem can occur due to high pressure applied when joining the plate and shaft. By interposing an intermediate ring made of aluminum nitride that does not contain yttria between the aluminum nitride plate and shaft, which are made of aluminum nitride containing yttria, it is possible to join the plate and shaft with low pressure. As a result, Patent Document 1 suppresses the occurrence of the above-mentioned problem.

[0007] Patent Document 2 describes a method for providing thermocouple passages in a plate without forming a cavity in the plate. Specifically, a slide groove is formed on the second main surface of the plate, extending from the center of the plate toward the outer circumference, and a guide groove is formed at the bottom of the slide groove as a thermocouple passage. A lid is slidably attached to the slide groove, and the lid covers the guide groove, thereby creating a closed space that is isolated from the outside. A first thermocouple is inserted into this guide groove, and the tip of the first thermocouple is positioned near the outer circumference of the plate, allowing the temperature near the outer circumference of the plate to be detected by the first thermocouple. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2023-030646 [Patent Document 2] Japanese Patent Publication No. 2012-028332 [Overview of the project] [Problems that the invention aims to solve]

[0009] Patent Document 1 enables the joining of plates and shafts with low applied pressure. However, in Patent Document 1, thermocouple passages are provided in the plate by forming cavities in the plate. Providing thermocouple passages in the plate without forming cavities in the plate would suppress the crushing of the thermocouple passages during the joining of the plate and shaft, and also suppress the occurrence of cracks or fissures in the plate. Therefore, in this respect, the technology described in Patent Document 1 has room for improvement.

[0010] Patent Document 2 describes a design in which thermocouple passages are provided in the plate without forming cavities in the plate. However, in Patent Document 2, since the shaft, made of a material with high thermal conductivity, is directly joined to the plate, heat easily transfers from the plate to the shaft. As heat is released from the plate to the shaft, temperature unevenness occurs in the plate, affecting the uniformity of the plate's heating. Specifically, the ceramic heater is installed in the vacuum chamber of a semiconductor manufacturing apparatus, and the inside of the vacuum chamber becomes hot when performing processes such as chemical vapor deposition (CVD) and etching on wafers. The shaft is fixed to a support member via an O-ring at the end opposite to the end joined to the plate. However, in the high-temperature environment of the vacuum chamber, the sealing performance of the O-ring decreases, so the O-ring is cooled to maintain its sealing performance. If the shaft has good thermal conductivity, heat from the plate easily transfers to the shaft, affecting the uniformity of the plate's heating. Furthermore, in Patent Document 2, in addition to the lid, a tube made of multiple connected pipes is attached to the plate, resulting in a large number of components attached to the plate and poor symmetry. Therefore, temperature unevenness easily occurs in the plate, which also affects the uniformity of the plate's heating. Therefore, the technology described in Patent Document 2 has room for improvement in terms of improving the uniformity of the plate's heat distribution.

[0011] Therefore, one of the objectives of this disclosure is to provide a ceramic heater and a method for manufacturing a ceramic heater that can suppress the collapse of thermocouple passages or cracking of plates when joining plates and shafts, and can improve the uniform heating of plates. [Means for solving the problem]

[0012] A ceramic heater according to this disclosure comprises a plate-shaped plate having a first main surface on which a wafer is placed and a second main surface positioned spaced apart in the thickness direction from the first main surface, and containing a resistance heating element that generates heat when energized; a cylindrical shaft having a first opening and a second opening located at both ends in the axial direction, and supporting the plate on the second main surface; and a plate-shaped auxiliary member joined to the plate. The plate has a groove formed therein that is recessed from the second main surface toward the first main surface and extends from a starting end located inside the shaft to a terminal end located outside the shaft. The auxiliary member includes a lid portion that extends along the outer portion which is located outside the shaft in the groove formed in the plate and covers the outer portion, and a connecting portion which is sandwiched between the plate and the shaft and has a tip portion which surrounds the first opening on the shaft joined to it.

[0013] A method for manufacturing a ceramic heater according to the present disclosure includes the steps of: forming a groove in a plate-shaped plate containing a resistance heating element that generates heat when an electric current is applied, the groove being recessed from the second main surface toward the first main surface and extending from the center of the second main surface toward the outer circumference of the second main surface, of which the first and second main surfaces are spaced apart in the thickness direction; installing a plate-shaped auxiliary member including a lid and an annular connecting portion on the plate such that the outer portion of the second main surface, which is the part closer to the outer circumference in the groove, is covered by the lid extending along the outer portion, and the inner portion of the second main surface, which is the part closer to the center in the groove, is located inside the connecting portion; installing a cylindrical shaft on the auxiliary member such that the tip portion, which is the region surrounding the first opening of the first and second openings located at both ends in the axial direction, abuts against the connecting portion; and simultaneously joining the shaft and the connecting portion of the auxiliary member, as well as the connecting portion of the auxiliary member and the plate, while applying pressure to the shaft, and joining the lid portion of the auxiliary member and the plate while applying a load to the lid portion of the auxiliary member with a pressing member. [Effects of the Invention]

[0014] According to this disclosure, it is possible to provide a ceramic heater that can suppress the collapse of grooves that serve as thermocouple passages or cracking of the plate when the plate and shaft are joined, and that can improve the uniform heating of the plate. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a perspective view of a ceramic heater according to Embodiment 1. [Figure 2] Figure 2 is an exploded perspective view of a ceramic heater according to Embodiment 1. [Figure 3] Figure 3 is a plan view of the ceramic heater according to Embodiment 1. [Figure 4] Figure 4 is a bottom view of the ceramic heater according to Embodiment 1. [Figure 5] Figure 5 is a front view of the ceramic heater according to Embodiment 1. [Figure 6]Fig. 6 is a rear view of the ceramic heater according to Embodiment 1. [Figure 7] Fig. 7 is a right side view of the ceramic heater according to Embodiment 1. [Figure 8] Fig. 8 is a left side view of the ceramic heater according to Embodiment 1. [Figure 9] Fig. 9 is an enlarged cross-sectional view showing a part of the ceramic heater according to Embodiment 1, which is cut along a vertical plane including the line A-A in Fig. 4. [Figure 10] Fig. 10 is a schematic cross-sectional view showing a configuration where the ceramic heater according to Embodiment 1 is used in a semiconductor manufacturing apparatus. [Figure 11] Fig. 11 is a bottom view of the plate. [Figure 12] Fig. 12 is a plan view of the auxiliary member. [Figure 13] Fig. 13 is a side view of the auxiliary member. [Figure 14] Fig. 14 is a cross-sectional view showing a part of the manufacturing process of the ceramic heater according to Embodiment 1. [Figure 15] Fig. 15 is an exploded perspective view of the ceramic heater according to Embodiment 2. [Figure 16] Fig. 16 is a plan view of the ceramic heater according to Embodiment 2. [Figure 17] Fig. 17 is a bottom view of the ceramic heater according to Embodiment 2. [Figure 18] Fig. 18 is a front view of the ceramic heater according to Embodiment 2. [Figure 19] Fig. 19 is a rear view of the ceramic heater according to Embodiment 2. [Figure 20] Fig. 20 is a right side view of the ceramic heater according to Embodiment 2. [Figure 21] Fig. 21 is a left side view of the ceramic heater according to Embodiment 2. [Figure 22] Fig. 22 is an enlarged cross-sectional view showing a part of the ceramic heater according to Embodiment 2, which is cut along a vertical plane including the line A-A in Fig. 17. [Figure 23]Figure 23 is an exploded perspective view of a ceramic heater according to Embodiment 3. [Figure 24] Figure 24 is a plan view of a ceramic heater according to Embodiment 3. [Figure 25] Figure 25 is a bottom view of the ceramic heater according to Embodiment 3. [Figure 26] Figure 26 is a front view of a ceramic heater according to Embodiment 3. [Figure 27] Figure 27 is a rear view of the ceramic heater according to Embodiment 3. [Figure 28] Figure 28 is a right side view of a ceramic heater according to Embodiment 3. [Figure 29] Figure 29 is a left side view of a ceramic heater according to Embodiment 3. [Figure 30] Figure 30 is an enlarged cross-sectional view showing a portion of the ceramic heater according to Embodiment 3 when it is cut through a vertical plane including line AA in Figure 25. [Figure 31] Figure 31 is an enlarged cross-sectional view showing a portion of the ceramic heater according to Embodiment 3 when it is cut through a vertical plane including line BB in Figure 25. [Figure 32] Figure 32 is a bottom view of a plate, which is a component of the ceramic heater according to Embodiment 3. [Figure 33] Figure 33 is a plan view of an auxiliary member of a modified example. [Figure 34] Figure 34 is a bottom view of the auxiliary member of the modified example. [Figure 35] Figure 35 is a side view of the auxiliary member of the modified example. [Figure 36] Figure 36(A) is a cross-sectional view of the modified auxiliary member, cut through a vertical plane containing line AA in Figure 33. Figure 36(B) is a cross-sectional view of the modified auxiliary member, cut through a vertical plane containing line BB in Figure 33. [Figure 37] Figure 37 is an enlarged cross-sectional view showing a portion of a ceramic heater according to Embodiment 3 using an auxiliary member of a modified example. [Figure 38]Figure 38 is an enlarged cross-sectional view showing a portion of a ceramic heater according to Embodiment 3 using an auxiliary member of a modified example. [Figure 39] Figure 39 is a cross-sectional view showing an enlarged portion of a modified ceramic heater. [Figure 40] Figure 40 is a cross-sectional view showing an enlarged portion of a modified ceramic heater. [Figure 41] Figure 41 is a cross-sectional view of a conventional ceramic heater. [Figure 42] Figure 42 is a cross-sectional view showing a portion of the manufacturing process of a conventional ceramic heater. [Modes for carrying out the invention]

[0016] [Description of Embodiments in this Disclosure] First, embodiments of ceramic heaters and methods for manufacturing ceramic heaters according to this disclosure will be listed and described.

[0017] A ceramic heater according to a first aspect of the present disclosure comprises a plate-shaped plate having a first main surface on which a wafer is placed and a second main surface positioned at a distance from the first main surface in the thickness direction, and having a built-in resistance heating element that generates heat when an electric current is applied; a cylindrical shaft having a first opening and a second opening located at both ends in the axial direction, and supporting the plate on the second main surface; and a plate-shaped auxiliary member joined to the plate. The plate has a groove formed therein that is recessed from the second main surface toward the first main surface and extends from a starting end located inside the shaft to a terminal end located outside the shaft. The auxiliary member includes a lid portion that extends along the outer portion which is the part of the groove formed in the plate that is located outside the shaft and covers the outer portion, and a connecting portion which is sandwiched between the plate and the shaft, and to which a tip portion which is the part of the shaft that surrounds the first opening is joined.

[0018] In the ceramic heater according to the first embodiment, no cavity is formed in the plate to serve as a thermocouple passage for inserting a thermocouple inside the plate. Instead, a groove is formed that recesses from the second main surface of the plate toward the first main surface. The outer portion of the groove is covered by the lid portion of an auxiliary member joined to the plate, thereby isolating the internal space from the external space. The inner portion of the groove is surrounded by the connecting portion of an auxiliary member joined to the plate, and the shaft is joined to the connecting portion of the auxiliary member, thereby isolating the internal space from the external space. As a result, the thermocouple inserted inside the groove is isolated from the external space, and according to the ceramic heater according to the first embodiment, the temperature near the outer circumference of the plate can be accurately detected by the thermocouple.

[0019] Furthermore, in the ceramic heater according to the first embodiment, even when a load is applied to the auxiliary member and the plate when joining the auxiliary member and the shaft to the plate, it is unlikely that a portion of the auxiliary member and the plate will bend. Therefore, according to the ceramic heater according to the first embodiment, crushing of the groove that serves as the thermocouple passage or cracking of the plate is suppressed when joining the plate and the shaft.

[0020] Furthermore, in the ceramic heater according to the first embodiment, the shaft is joined to the connecting portion of the auxiliary member, and the connecting portion is joined to the plate, so the shaft is indirectly joined to the plate with the connecting portion in between. In this way, by interposing the auxiliary member between the plate and the shaft, the number of bonding interfaces between the plate and the shaft is increased compared to the case where the shaft is directly joined to the plate. Since bonding interfaces can be an obstacle to heat conduction, the increase in bonding interfaces reduces heat dissipation from the plate to the shaft. Therefore, according to the ceramic heater according to the first embodiment, temperature unevenness of the plate can be suppressed and the uniformity of the plate can be improved. Moreover, according to the ceramic heater according to the first embodiment, since there are few members attached to the plate, only the auxiliary member, temperature unevenness of the plate can be suppressed and the uniformity of the plate can be improved.

[0021] As a ceramic heater according to a second aspect of the present disclosure, the ceramic heater according to the first aspect described above has a recess formed in the plate that is recessed from the second main surface toward the first main surface, into which an auxiliary member is fitted, and at least a portion of the groove in the plate may be formed so as to be recessed toward the first main surface at the bottom surface of the recess. With such a configuration, the ceramic heater according to the second aspect facilitates the positioning of the auxiliary member relative to the plate, and consequently, facilitates the positioning of the shaft relative to the plate.

[0022] As a ceramic heater according to a third aspect of this disclosure, the ceramic heater according to the second aspect described above may be configured such that a gap is formed in at least a portion between the side surface of the auxiliary member and the side surface of the recess of the plate. By having such a configuration, the ceramic heater according to the third aspect can suppress lateral heat conduction between the plate and the auxiliary member. As a result, heat from the plate is less likely to transfer to the shaft via the auxiliary member, and the uniformity of the first main surface on which the wafer is placed can be improved.

[0023] As a ceramic heater according to the fourth aspect of this disclosure, the ceramic heater according to the second or third aspect described above has a connecting portion that is annular in shape to which the tip of the shaft abuts, a recess in the plate includes a first recess into which the lid portion is fitted, and a second recess into which the connecting portion is fitted and which is connected to the first recess, the second recess being formed annularly such that it has an inner surface facing the inner surface of the connecting portion, and a groove in the plate includes a first groove formed on the bottom surface of the first recess and the bottom surface of the second recess of the plate so as to be recessed toward the first main surface, and a second groove formed on the second main surface of the plate on the inside of the shaft so as to be recessed toward the first main surface, the first groove and the second groove may be configured to communicate with each other. By having such a configuration, the ceramic heater according to the fourth aspect can reduce the volume of the auxiliary member, and the proportion of the auxiliary member to the entire plate including the auxiliary member is reduced.

[0024] As a ceramic heater according to the fifth aspect of this disclosure, the ceramic heater according to the fourth aspect described above may be configured such that a gap is formed in at least a portion between the inner circumferential surface of the connecting portion of the auxiliary member and the inner circumferential surface of the second recess of the plate. By having such a configuration, the ceramic heater according to the fifth aspect can suppress lateral heat conduction between the plate and the auxiliary member. As a result, heat from the plate is less likely to transfer to the shaft via the auxiliary member, and the uniformity of the heat on the first main surface on which the wafer is placed can be improved.

[0025] As a ceramic heater according to the sixth aspect of this disclosure, the ceramic heater according to the second or third aspect described above has a connecting portion that is annular in shape to which the tip of the shaft abuts, and the recess of the plate includes a first recess into which the lid portion is fitted, and a second recess into which the connecting portion is fitted and which is connected to the first recess, wherein the second recess is formed to have a flat bottom surface to which the connecting portion abuts and an outer peripheral surface facing the outer peripheral surface of the connecting portion, and a space exists inside the connecting portion on the flat bottom surface, and the groove of the plate may be formed to be recessed toward the first main surface on the bottom surface of the first recess and the bottom surface of the second recess of the plate. By having such a configuration, the ceramic heater according to the sixth aspect can suppress lateral heat conduction between the plate and the auxiliary member, and can also suppress the transfer of heat from the plate to the auxiliary member by thermal radiation. As a result, the transfer of heat from the plate to the shaft via the auxiliary member is effectively suppressed, and the uniformity of the heat on the first main surface on which the wafer is placed can be improved.

[0026] As a ceramic heater according to the seventh aspect of this disclosure, the ceramic heater according to any one of the first to sixth aspects described above may be configured such that at least one of the lid portion and the connecting portion of the auxiliary member has a tapered shape on the first surface side that contacts the plate. By having such a configuration, the ceramic heater according to the seventh aspect can suppress vertical heat conduction between the plate and the auxiliary member. As a result, heat from the plate is less likely to transfer to the shaft via the auxiliary member, and the uniformity of the heat on the first main surface on which the wafer is placed can be improved.

[0027] As a ceramic heater according to the eighth aspect of this disclosure, the ceramic heater according to the seventh aspect described above may be configured such that at least a portion of the inner circumferential surface of the connecting portion on the first surface side is a first inclined surface that slopes toward the outer circumferential surface of the connecting portion. With such a configuration, the ceramic heater according to the eighth aspect can distribute the stress generated in the connecting portion when the connecting portion of the auxiliary member is pressed and joined to the plate during the manufacturing of the ceramic heater, thereby reducing the risk of damage to the connecting portion.

[0028] As a ceramic heater according to the ninth aspect of this disclosure, the ceramic heater according to the eighth aspect described above may be configured such that at least a portion of the outer circumferential surface of the connecting portion on the first surface side is a second inclined surface that inclins toward the inner circumferential surface of the connecting portion, and the first inclined surface is inclined over a longer distance than the second inclined surface. With such a configuration, the ceramic heater according to the ninth aspect can better distribute the stress generated in the connecting portion when the connecting portion of the auxiliary member is pressed and joined to the plate during the manufacturing of the ceramic heater, thereby effectively reducing the risk of damage to the connecting portion.

[0029] As a ceramic heater according to the tenth aspect of this disclosure, a ceramic heater according to any one of the third to ninth aspects described above may be configured such that at least one of the gaps formed between the side surface of the auxiliary member and the side surface of the recess of the plate, and the gap formed between the inner circumferential surface of the connecting portion and the inner circumferential surface of the second recess of the plate, is filled with a filler. By having such a configuration, the ceramic heater according to the tenth aspect can reduce the risk of unwanted materials such as processing debris and dust accumulating in the gaps of the ceramic heater. This eliminates concerns that unwanted materials may scatter onto the wafer and adversely affect the wafer processing when performing processes such as chemical vapor deposition (CVD) and etching on a wafer in a semiconductor manufacturing apparatus. It also eliminates concerns that gases used in wafer processing may enter the gaps and cause corrosion at the joint surface between the auxiliary member and the plate.

[0030] As a ceramic heater according to the eleventh aspect of this disclosure, a ceramic heater according to any one of the first to tenth aspects described above may be configured such that the plate and shaft are mainly composed of aluminum nitride, and the auxiliary member is mainly composed of aluminum nitride and does not contain yttria. The plate, shaft and auxiliary member are integrated by diffusion bonding using a flux containing rare earth components, for example, but because the auxiliary member does not contain yttria, the diffusion of the rare earth components of the flux is promoted near the bonding interface between the auxiliary member and the plate and the bonding interface between the auxiliary member and the shaft when bonding the plate and the auxiliary member, and when bonding the shaft and the auxiliary member. As a result, according to the ceramic heater of the eleventh aspect, bonding of the plate and the auxiliary member, and bonding of the shaft and the auxiliary member can be performed at low temperature and low load.

[0031] A method for manufacturing a ceramic heater according to a first aspect of the present disclosure comprises the steps of: forming a groove in a plate-shaped plate containing a resistance heating element that generates heat when an electric current is applied, the groove being recessed from the second main surface toward the first main surface and extending from the center of the second main surface toward the outer circumference of the second main surface, of which the first and second main surfaces are spaced apart in the thickness direction; installing a plate-shaped auxiliary member including a lid and an annular connecting portion on the plate such that the outer portion of the second main surface, which is the part closer to the outer circumference in the groove, is covered by the lid extending along the outer portion, and the inner portion of the second main surface, which is the part closer to the center in the groove, is located inside the connecting portion; installing a cylindrical shaft on the auxiliary member such that the tip portion, which is the region surrounding the first opening of the first and second openings located at both ends in the axial direction, abuts against the connecting portion; and simultaneously joining the shaft and the connecting portion of the auxiliary member, as well as the connecting portion of the auxiliary member and the plate, while applying pressure to the shaft, and joining the lid portion of the auxiliary member and the plate while applying a load to the lid portion of the auxiliary member with a pressing member.

[0032] In the ceramic heater manufacturing method according to the first embodiment, the connecting portion of the auxiliary member is pressed against the plate by the tip of the shaft, and at the same time, the lid portion of the auxiliary member is pressed against the plate by the pressing member, thereby joining the plate, auxiliary member and shaft with a single press. Therefore, according to the ceramic heater manufacturing method according to the first embodiment, the plate, auxiliary member and shaft can be easily integrated, and the manufacturing cost of the ceramic heater can be reduced.

[0033] Furthermore, the joining of the plate, auxiliary member, and shaft is performed under heated conditions, but the resistance heating element embedded in the plate, which is mainly composed of molybdenum, changes in electrical resistance due to carbonization when heated. Therefore, in order to uniformly heat the plate with the resistance heating element, it is desirable to suppress the change in the electrical resistance of the resistance heating element, and by joining the plate, auxiliary member, and shaft with a single press, as in the manufacturing method of the ceramic heater according to the first embodiment, variations in the electrical resistance of the resistance heating element can be suppressed. Thus, the manufacturing method of the ceramic heater according to the first embodiment can improve the uniformity of heating of the plate.

[0034] Furthermore, in the manufacturing method of the ceramic heater according to the first embodiment, no cavity is formed in the plate to serve as a thermocouple passage for inserting a thermocouple inside the plate. Instead, a groove is formed that is recessed from the second main surface of the plate toward the first main surface. Therefore, even when a load is applied to the auxiliary member and the plate when joining the auxiliary member and the shaft to the plate, it is unlikely that a portion of the auxiliary member and the plate will bend. Thus, according to the manufacturing method of the ceramic heater according to the first embodiment, it is possible to suppress the crushing of the groove that serves as the thermocouple passage or the cracking of the plate when joining the plate and the shaft.

[0035] Ceramic heater according to a second aspect of this disclosure Manufacturing method In the first embodiment described above, the method for manufacturing a ceramic heater may be configured such that at least a portion of the first surface on the inner circumferential surface of the connecting portion that contacts the plate is inclined toward the outer circumferential surface of the connecting portion. In the second embodiment, by having such a configuration, the stress generated in the connecting portion when the connecting portion of the auxiliary member is pressed and joined to the plate during the manufacturing of the ceramic heater can be distributed, thereby reducing the risk of damage to the connecting portion.

[0036] [Details of the embodiments of this disclosure] Next, embodiments of a ceramic heater according to this disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts will be given the same reference numerals, and their descriptions will not be repeated.

[0037] <Embodiment 1> Figure 1 is a perspective view of the ceramic heater 1 according to Embodiment 1, and Figure 2 is an exploded perspective view of the ceramic heater 1 according to Embodiment 1. Figures 3 to 8 are a plan view, bottom view, front view, rear view, right side view, and left side view of the ceramic heater 1 according to Embodiment 1, respectively. Note that the rear view, right side view, and left side view are represented identically to the front view. Figure 9 is an enlarged cross-sectional view showing a portion of the ceramic heater 1 according to Embodiment 1 when cut by a vertical plane including line AA in Figure 4. Figure 10 is a cross-sectional view showing a schematic configuration of the ceramic heater 1 according to Embodiment 1 when used in a semiconductor manufacturing apparatus. Figure 11 is a bottom view of a plate, which is a component of the ceramic heater 1 according to Embodiment 1. Figures 12 and 13 are a plan view and a front view of an auxiliary member, which is a component of the ceramic heater 1 according to Embodiment 1.

[0038] The ceramic heater 1 is installed in a vacuum chamber, for example, in semiconductor manufacturing equipment, when performing chemical vapor deposition (CVD), etching, or other processes on a wafer, and is used to heat the wafer to a desired temperature. The vacuum chamber is maintained in a vacuum or reduced-pressure atmosphere, and processes such as forming thin films on the wafer using plasma or etching are performed inside the vacuum chamber.

[0039] Referring to Figure 2, the ceramic heater 1 comprises a plate-shaped plate 2, a cylindrical shaft 3, and a plate-shaped auxiliary member 4. Auxiliary member 4 The plate 2, shaft 3, and auxiliary member 4 are integrated by, for example, diffusion bonding, and by, for example, diffusion bonding, the shaft 3 and auxiliary member 4 are also joined together.

[0040] (Description of the plate) Referring to Figures 1 to 8, the plate 2 is formed in a plate shape having a pair of main surfaces, a first main surface 20 and a second main surface 21, which are spaced apart in the thickness direction. The first main surface 20 constitutes the surface on which the wafer is placed. The plate 2 can be made up of, for example, a circular disc in plan view. The size of the plate 2 is, for example, a diameter of about 300 mm to 330 mm and a thickness of about 20 mm. In this disclosure, "plan view" refers to a view from a direction perpendicular to the first main surface 20 or the second main surface 21.

[0041] Referring to Figure 9, the plate 2 incorporates a resistive heating element 5 that generates heat when an electric current is applied. The resistive heating element 5 can be made of a coil mainly composed of molybdenum, tungsten, etc. The resistive heating element 5 is embedded in almost the entire area between the first main surface 20 and the second main surface 21 of the plate 2, along a plane parallel to the first main surface 20 and the second main surface 21. As a result, the entire plate 2 is heated by the resistive heating element 5, and the wafer placed on the first main surface 20 is heated. The resistive heating element 5 can be made up of, for example, a first resistive heating element located in a region closer to the center of the plate 2 and a second resistive heating element located in a region closer to the outer periphery of the plate 2. In this case, as shown in Figure 10, the plate 2 is fitted with a pair of metal first power supply rods 17 connected to a pair of terminals 12 at both ends of the first resistive heating element, and a pair of metal second power supply rods 18 connected to a pair of terminals 13 at both ends of the second resistive heating element.

[0042] Referring to Figures 2, 4, 9, and 11, the plate 2 has a recess 22 into which the auxiliary member 4 is fitted. The recess 22 is formed in the second main surface 21 of the plate 2 so as to be recessed in the direction from the second main surface 21 toward the first main surface 20. The recess 22 includes a first recess 23 into which the lid portion 40 of the auxiliary member 4 is fitted, and a second recess 24 into which the connecting portion 41 of the auxiliary member 4 is fitted. The first recess 23 and the second recess 24 are connected.

[0043] The shape of the second recess 24 in plan view is annular, matching the shape of the connecting portion 41 of the auxiliary member 4, and in this embodiment, it is circular. The second recess 24 is formed to include an annular bottom surface 242 that abuts against the annular connecting portion 41, an outer surface 240 that faces the outer surface 410 of the connecting portion 41, and an inner surface 241 that faces the inner surface 411 of the connecting portion 41. In plan view, the center of the second recess 24 coincides with the center of the second main surface 21, and the second recess 24 is formed on the second main surface 21 so as to be concentric with the second main surface 21. In the center of the plate 2 on the side of the second main surface 21, a flat cylindrical projection 25 is provided, surrounded by the second recess 24, due to the formation of the second recess 24.

[0044] The first recess 23 is formed on the second main surface 21 so as to extend linearly from the second recess 24 toward the outer circumference of the second main surface 21. Of the two ends of the first recess 23, the starting end 230 and the ending end 231, the starting end 230 connects to the second recess 24, and the ending end 231 is located in front of the outer circumference of the second main surface 21.

[0045] Referring to Figures 2, 9, and 11, a groove 26 is formed in the plate 2 as a thermocouple passage through which the thermocouple passes. The groove 26 is formed in the plate 2 so as to be recessed from the second main surface 21 toward the first main surface 20. The groove 26 extends on the second main surface 21 side of the plate 2 from the region inside the shaft 3 toward the region outside the shaft 3 toward the outer circumference of the second main surface 21. That is, of the two ends of the groove 26, the starting end 260 and the ending end 261, the starting end 260 is located inside the shaft 3. The ending end 261 is located outside the shaft 3 and is located in front of the ending end 231 of the first recess 23. In this embodiment, the groove 26 extends to just before the outer circumference of the second main surface 21, and the ending end 261 of the groove 26 is located just before the outer circumference of the second main surface 21. However, the end 261 of the groove 26 may be located away from the outer circumference of the second main surface 21, as long as it is located outside the shaft 3. The position of the end 231 of the first recess 23 is changed according to the position of the end 261 of the groove 26.

[0046] In this embodiment, the groove 26 includes a first groove portion 27 formed in the bottom surface 220 of the recess 22 (the bottom surface 233 of the first recess 23 and the bottom surface 242 of the second recess 24) so ​​as to be recessed toward the first main surface 20, and a second groove portion 28 formed in the second main surface 21 of the plate 2 (the surface of the projection 25) so as to be recessed toward the first main surface 20. The second groove portion 28 is in communication with the first groove portion 27. As shown in Figure 11, the first groove portion 27 constitutes an outer portion 262, which is the part of the groove 26 closer to the outer circumference of the second main surface 21 and located outside the shaft 3, and an inner portion 263, which is the part of the groove 26 closer to the center of the second main surface 21 and located inside the shaft 3. The second groove portion 28 constitutes the remainder of the inner portion 263 of the groove 26. The thermocouple is inserted through the second groove 28 of the groove 26, and then passed through the first groove 27, thereby being inserted to near the outer circumference of the plate 2.

[0047] Referring to Figure 10, the plate 2 is fitted with a first thermocouple 14 for detecting the temperature near the outer periphery of the plate 2 and a second thermocouple 15 for detecting the temperature near the center of the plate 2, in order to confirm that the entire plate 2 is heated uniformly by the resistance heating element 5. The first thermocouple 14 is constructed, for example, using a sheathed thermocouple. The first thermocouple 14 is passed through the groove 26 of the plate 2 so that the temperature-sensing tip of the first thermocouple 14 is positioned near the outer periphery of the plate 2. As a result, the temperature near the outer periphery of the plate 2 is detected by the first thermocouple 14. The second thermocouple 15 is inserted into a recess 29 formed in the inner region of the shaft 3 on the second main surface 21 of the plate 2 so that the temperature-sensing tip of the second thermocouple 15 is positioned near the center of the plate 2. As a result, the temperature near the center of the plate 2 is detected by the second thermocouple 15.

[0048] Referring to Figure 10, the plate 2 may incorporate electrodes 6, mainly composed of molybdenum, tungsten, etc., such as electrostatic electrodes for wafer adsorption and RF electrodes for plasma generation. In this case, a third metal power supply rod 19 connected to the terminals 16 of the electrodes 6 is attached to the plate 2.

[0049] (Description of the shaft) Referring to Figures 2 and 4 through 8, the shaft 3 is formed in a cylindrical shape having a pair of openings, a first opening 30 and a second opening 31, located at both ends in the axial direction. The shaft 3 supports the plate 2 on the side of the second main surface 21 (the surface opposite to the first main surface 20 on which the wafer is placed). The shaft 3 can be made, for example, a cylinder with a circular cross-section when cut by a plane perpendicular to the axial direction. The diameter of the shaft 3 is smaller than the diameter of the plate 2.

[0050] In the shaft 3, the tip portion 32, which surrounds the first opening 30, and the base portion 33, which surrounds the second opening 31, can be formed, for example, by flanges. The tip portion 32 of the shaft 3 is joined to the plate 2 via an auxiliary member 4 interposed between the plate 2 and the shaft 3. The base portion 33 of the shaft 3 is connected to the support base 7 via an O-ring 8, as shown in Figure 10. As a result, the internal space of the shaft 3 is isolated from the external space, which is the space inside the vacuum chamber of the semiconductor manufacturing apparatus.

[0051] Referring to Figure 10, the shaft 3 houses a first power supply rod 17 and a second power supply rod 18 connected to the resistance heating element 5, a third power supply rod 19 connected to the electrode 6, as well as a first thermocouple 14 and a second thermocouple 15. This isolates these power supply rods and thermocouples from the external space, which is the vacuum chamber of the semiconductor manufacturing apparatus, preventing them from being exposed to plasma or the like. The first thermocouple 14 is not particularly limited, but it is preferable to pass it through the groove 26 of the plate 2 via the inside of a cylindrical thermocouple guide. The thermocouple guide includes a straight section extending axially (vertically) inside the shaft 3 and a curved section that changes the direction in which the thermocouple guide extends from vertical to horizontal. The thermocouple guide is positioned such that the curved section is inserted into the second groove of the groove 26, and the exit of the curved section faces the entrance of the first groove 27 of the groove 26. This allows the first thermocouple 14 to be smoothly inserted into the groove 26 of the plate 2 using the thermocouple guide.

[0052] Referring to Figures 2 and 4 through 8, the shaft portion of the shaft 3 between the tip portion 32 and the base portion 33 may have a shape in which the inner diameter and outer diameter do not change along the axial direction. Alternatively, the shaft portion of the shaft 3 may have a shape that includes a small diameter portion 34 near the base portion 33 and a large diameter portion 35 near the tip portion 32, which has a larger inner diameter and outer diameter than the small diameter portion 34.

[0053] (Explanation of auxiliary components) Referring to Figures 2, 4, 9, 12, and 13, the auxiliary member 4 is formed in a plate shape (including a rod shape) with, for example, a lid portion 40 having a thickness of 1.0 mm to 7.5 mm and a connecting portion 41 having a thickness of 4.0 mm to 10.5 mm. The auxiliary member 4 is joined to the plate 2. The auxiliary member 4 includes the lid portion 40 and the connecting portion 41. The auxiliary member 4 is interposed between the plate 2 and the shaft 3, with the connecting portion 41 sandwiched between the plate 2 and the shaft 3, and the tip portion 32 of the shaft 3 is joined to the connecting portion 41.

[0054] The cover portion 40 extends along the outer portion 262, which is the part of the groove 26 formed in the plate 2 that is located outside the shaft 3. The cover portion 40 is joined to the plate 2 so as to cover the outer portion 262 of the groove 26. The cover portion 40 can be made of, for example, an elongated flat plate that extends in a straight line and whose length is sufficiently greater than its width. The width of the cover portion 40 is greater than the width of the groove 26. The length of the cover portion 40 is greater than the length of the outer portion 262 of the groove 26. Because the outer portion 262 of the groove 26 is covered by the cover portion 40, and the inner portion 263 of the plate 2 near the center of the groove 26 is located inside the shaft 3, the internal space of the groove 26 is isolated from the external space, which is the space inside the vacuum chamber of the semiconductor manufacturing apparatus. As a result, the temperature near the outer circumference of the plate 2 can be accurately detected by the first thermocouple 14.

[0055] The connecting portion 41 is joined to the plate 2, and the tip portion 32 of the shaft 3 is also joined to it, thereby connecting the plate 2 and the shaft 3 and integrating them. The shape and size of the outer circumference of the connecting portion 41 in plan view are not particularly limited, but it is preferable that they match the shape and size of the outer circumference of the tip portion 32 of the shaft 3 that is joined to the connecting portion 41. In this embodiment, the shape of the connecting portion 41 in plan view is annular to match the shape of the tip portion 32 of the shaft 3, and the shape and size of the inner circumference of the connecting portion 41 in plan view are not particularly limited, but it is preferable that they match the shape and size of the inner circumference of the tip portion 32 of the shaft 3. The connecting portion 41 can be made of an annular ring plate to match the shape of the tip portion 32 of the shaft 3, for example. As a result, the tip portion 32 of the shaft 3 comes into contact with the connecting portion 41. Referring to Figure 10, the connecting portion 41 of the auxiliary member 4 is sandwiched between the plate 2 and the tip portion 32 of the shaft 3. In this state, the tip portion 32 of the shaft 3 is pressed against the plate 2, thereby joining the tip portion 32 of the shaft 3 and the connecting portion 41, and simultaneously joining the connecting portion 41 and the plate 2. Because the tip portion 32 of the shaft 3 is in contact with the connecting portion 41, the tip portion 32 of the shaft 3 of Connecting part 41 to The joints can be joined uniformly, and the connecting portion 41 can be joined uniformly to the plate 2.

[0056] Referring to Figures 2, 4, and 9, in this embodiment, the auxiliary member 4 is fitted into a recess 22 formed in the plate 2. The lid portion 40 of the auxiliary member 4 is fitted into the first recess 23 of the recess 22, and the connecting portion 41 of the auxiliary member 4 is fitted into the second recess 24 of the recess 22. This facilitates the positioning of the auxiliary member 4 relative to the plate 2, and consequently, the positioning of the shaft 3 relative to the plate 2. The surface of the lid portion 40 is not particularly limited, but it is preferably flush with the second main surface 21 of the plate 2. The surface of the connecting portion 41 may protrude from the second main surface 21 of the plate 2, or it may be flush with the second main surface 21 of the plate 2.

[0057] Note that the surface of the lid portion 40 refers to the second surface 402 on the opposite side of the first surface 401 that abuts against the plate 2 on the lid portion 40. The surface of the connecting portion 41 refers to the first surface on the connecting portion 41 that abuts against the plate 2. 412 This refers to the second surface 413, which is the opposite surface and abuts against the tip 32 of the shaft 3. The cover portion 40 includes a first surface 401 and a second surface 402 that are spaced apart in the thickness direction, and a side surface 400 that is between the first surface 401 and the second surface 402. The connecting portion 41 includes a first surface 412 and a second surface 413 that are spaced apart in the thickness direction, an outer side surface 410 that is between the first surface 412 and the second surface 413 and is the outer peripheral surface of the connecting portion 41, and an inner side surface 411 that is between the first surface 412 and the second surface 413 and is radially inward from the outer side surface 410 and is the inner peripheral surface of the connecting portion 41.

[0058] The width of the lid portion 40 is not particularly limited, but is preferably smaller than the width of the first recess 23. The length of the lid portion 40 is not particularly limited, but is preferably smaller than the length of the first recess 23. The outer diameter of the connecting portion 41 is not particularly limited, but is preferably smaller than the outer diameter of the second recess 24. As a result, a gap G is formed between the side surface of the auxiliary member 4 and the side surface of the recess 22. The side surface of the auxiliary member 4 refers to the side surface 400 of the lid portion 40 (excluding the second surface 402, which is the front surface of the lid portion 40, and the first surface 401, which is the back surface), and the outer side surface 410, which is the outer peripheral surface of the connecting portion 41. The side surface of the recess 22 refers to the side surface 232 of the first recess 23 (excluding the bottom surface 220), and the outer side surface 240, which is the outer peripheral surface of the second recess 24.

[0059] Furthermore, the inner diameter of the connecting portion 41 is not particularly limited, but it is preferable that it be larger than the inner diameter of the second recess 24 (the diameter of the projection 25). This creates a gap G between the inner circumferential surface 411 of the connecting portion 41 and the inner circumferential surface of the recess 22. The inner circumferential surface of the recess 22 refers to the inner side surface (circumferential surface of the projection 25) 241, which is the inner circumferential surface of the second recess 24.

[0060] These gaps G are, for example, 300 μm to 700 μm. By forming gaps G between the side surface of the auxiliary member 4 and the side surface of the recess 22, and between the inner circumferential surface 411 of the connecting portion 41 and the inner circumferential surface 241 of the recess 22, lateral heat conduction between the plate 2 and the auxiliary member 4 can be suppressed. As a result, heat from the plate 2 is less likely to transfer to the shaft 3 via the auxiliary member 4, and the uniformity of the heat on the first main surface 20 on which the wafer is placed can be improved.

[0061] The gap G may be formed only in a portion between the side surface of the auxiliary member 4 and the side surface of the recess 22, and between the inner circumferential surface 411 of the connecting portion 41 and the inner circumferential surface 241 of the recess 22. However, it is preferable for the gap G to be formed around the entire circumference, as this can better suppress lateral heat conduction between the plate 2 and the auxiliary member 4. The presence of the gap G makes it possible to distinguish between the plate 2 and the auxiliary member 4.

[0062] (Explanation of the material of the ceramic heater) The plate 2, shaft 3, and auxiliary member 4 that constitute the ceramic heater 1 are made of sintered ceramics such as aluminum nitride, aluminum oxide, silicon carbide, and silicon nitride. Among these, it is preferable that each component 2-4 of the ceramic heater 1 has aluminum nitride as its main component, as it has high thermal conductivity. This improves the thermal conductivity of the plate 2. The main component refers to each component 2-4 of the ceramic heater 1 containing 95% by mass or more, preferably 99% by mass or more, of aluminum nitride.

[0063] Plate 2 and shaft 3 are not particularly limited, but they mainly consist of aluminum nitride and may also contain oxides of rare earth elements (hereinafter referred to as "rare earth oxides"), alkaline earth elements, or transition metal elements. Examples of rare earth oxides include yttria (yttrium oxide), cerium oxide, and samarium oxide, with yttria being preferred. Examples of alkaline earth element oxides include magnesia (magnesium oxide), and examples of transition metal element oxides include titania (titanium oxide). Here, the thermal conductivity of aluminum nitride is improved by the addition of yttria. Therefore, by including yttria in plate 2, which mainly consists of aluminum nitride, the thermal conductivity of plate 2 can be improved. The yttria content in plate 2 and shaft 3 is not particularly limited, but it is preferably 0.05% by mass or more. Plate 2 and shaft 3, for example, are gray in color because they mainly consist of aluminum nitride and contain yttria.

[0064] The auxiliary member 4 is not particularly limited, but it is preferable that it mainly consists of aluminum nitride and does not contain rare earth oxides such as yttria. Here, "does not contain rare earth oxides" means that the content of rare earth oxides in the auxiliary member 4 is below the detection limit, and does not exclude the possibility that the auxiliary member 4 contains trace amounts of rare earth oxides. "Below the detection limit" means, for example, that the content of rare earth oxides in the auxiliary member 4 is 5 ppm by mass or less when measured by inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0065] The auxiliary member 4 may contain an oxide of at least one of an alkaline earth element oxide and an oxide of a transition metal element. Magnesia can be an example of an alkaline earth element oxide, and titania can be an example of a transition metal element oxide. The content of the oxide in the auxiliary member 4 is, for example, 0.1% by mass or more and 3.0% by mass or less. The auxiliary member 4, for example, having aluminum nitride as its main component and not containing yttria, exhibits a gray color with a different shade than when yttria is contained. Alternatively, the auxiliary member 4, for example, having aluminum nitride as its main component, not containing yttria, and containing magnesia and titania, exhibits a dark gray color. Thus, the auxiliary member 4 has a difference in appearance in terms of color shade compared to the plate 2 and shaft 3 which contain yttria. Therefore, the plate 2 and shaft 3 and the auxiliary member 4 can be distinguished by the difference in color shade.

[0066] The plate 2, shaft 3, and auxiliary member 4 are integrated by diffusion bonding using a flux P, as shown in Figure 14. The flux P can be exemplified by a paste containing calcia, alumina, and yttria. Because the auxiliary member 4 does not contain rare earth oxides such as yttria, the diffusion of the rare earth components of the flux P is promoted near the bonding interface between the auxiliary member 4 and plate 2, and between the auxiliary member 4 and shaft 3, during the bonding of the plate 2 and auxiliary member 4, and the bonding of the shaft 3 and auxiliary member 4. This allows the bonding of the plate 2 and auxiliary member 4, and the bonding of the shaft 3 and auxiliary member 4, to be performed at low temperatures and with low loads.

[0067] Furthermore, although the auxiliary member 4, which does not contain yttria, has inferior thermal conductivity compared to the plate 2, which contains yttria, the auxiliary member 4 is attached to only a portion of the second main surface 21 of the plate 2. Therefore, compared to the case where the auxiliary member 4 is attached to the entire second main surface 21 of the plate 2, the time required to bring the temperature of the entire plate 2, including the auxiliary member 4, to a uniform temperature is shortened. In the semiconductor manufacturing process, it is necessary to raise or lower the temperature of the plate 2 to set the target temperature, but by being able to quickly bring the temperature of the plate 2 to the target temperature, semiconductors manufacturing The device will operate more stably.

[0068] (Explanation of the manufacturing method for ceramic heaters) Next, an outline of the manufacturing method of the ceramic heater 1 according to this embodiment will be described with reference to Figure 14. First, the plate 2, shaft 3, and auxiliary member 4 are manufactured. The plate 2, shaft 3, and auxiliary member 4 are obtained, for example, by manufacturing a ceramic molded body using the mold casting method and then firing the ceramic molded body. Here, the "mold casting method" refers to a method of obtaining a molded body by injecting a ceramic slurry containing ceramic raw material powder and a molding agent into a mold, and then causing a chemical reaction of the molding agent within the mold to mold the ceramic slurry. The connecting portion 41 of the auxiliary member 4 may be fired after being formed into a ring plate, or it may be fired after being formed into a disc, and then the center of the disc may be hollowed out by machining to form a ring plate.

[0069] Then, after forming a recess 22 on the second main surface 21 of plate 2, a groove 26 is formed. The recess 22 and groove 26 can be formed, for example, by cutting or blasting.

[0070] Then, the plate 2 is placed on the workbench with the second main surface 21 facing upwards. After that, the flux P is applied to the bottom surface 220 of the recess 22 in this embodiment, which is the portion of the plate 2 on the second main surface 21 side where the auxiliary member 4 is to be installed.

[0071] Then, the auxiliary member 4 is fitted into the recess 22 of the plate 2, thereby installing the auxiliary member 4 on the plate 2. At this time, the cover portion 40 of the auxiliary member 4 covers the outer portion 262 of the second main surface 21 closer to the outer circumference in the groove 26 formed in the plate 2, and the inner portion 263 of the second main surface 21 closer to the center in the groove 26 is positioned inside the connecting portion 41.

[0072] Next, the flux P is applied to the second surface 413, which is the surface of the connecting portion 41 of the auxiliary member 4. After that, the shaft 3 is placed on top of the auxiliary member 4 with the tip 32 facing downwards so that the connecting portion 41 is covered by the tip 32.

[0073] Finally, for example, under a nitrogen atmosphere and at a temperature of approximately 1600°C to 1700°C, 10 kg / cm³ of material is applied to shaft 3 from above. 2 More than 40kg / cm 2 The connecting portion 41 of the shaft 3 and the auxiliary member 4, as well as the connecting portion 41 of the auxiliary member 4 and the plate 2, are joined simultaneously while applying a load of the following magnitude. At the same time, the lid portion 40 of the auxiliary member 4 and the plate 2 are joined together by applying a load of the same surface pressure from above to the lid portion 40 of the auxiliary member 4 using the pressing member 9. As a result, the plate 2, shaft 3, and auxiliary member 4 are integrated, and the ceramic heater 1 is manufactured.

[0074] Furthermore, for the ceramic heater 1, through holes are formed in the second main surface 21 of the plate 2 at positions corresponding to terminals 12, 13, and 16. This exposes terminals 12, 13, and 16, allowing the corresponding power supply rods 17, 18, and 19 to be connected to each terminal 12, 13, and 16. Additionally, a recess 29 is formed in the second main surface 21 of the plate 2 into which the second thermocouple 15 can be inserted.

[0075] Thus, in the manufacturing method of the ceramic heater 1 of this embodiment, the tip 32 of the shaft 3 presses the connecting portion 41 of the auxiliary member 4 against the plate 2, and at the same time, the pressing member 9 presses the lid portion 40 of the auxiliary member 4 against the plate 2, thereby joining the plate 2, auxiliary member 4, and shaft 3 together with a single press. Therefore, according to the manufacturing method of the ceramic heater 1 of this embodiment, the plate 2, auxiliary member 4, and shaft 3 can be easily integrated, and the manufacturing cost of the ceramic heater 1 can be reduced.

[0076] Furthermore, the joining of the plate 2, auxiliary member 4, and shaft 3 is performed under heated conditions, but the resistance heating element 5 embedded in the plate 2 is mainly composed of molybdenum, for example, so when heated, its electrical resistance changes due to carbonization, etc. Therefore, in order to uniformly heat the plate 2 with the resistance heating element 5, it is desirable to suppress the change in the electrical resistance of the resistance heating element 5, and by joining the plate 2, auxiliary member 4, and shaft 3 with a single press, as in the manufacturing method of the ceramic heater 1 of this embodiment, variations in the electrical resistance of the resistance heating element 5 can be suppressed. Thus, according to the manufacturing method of the ceramic heater 1 of this embodiment, the uniformity of heating of the plate 2 can be improved.

[0077] (Explanation of the function and effects of ceramic heaters) In the ceramic heater 1 according to Embodiment 1, no cavity is formed in the plate 2 to serve as a thermocouple passage for inserting the first thermocouple 14. Instead, a groove 26 is formed in the plate 2 that recesses from the second main surface 21 toward the first main surface 20. The outer portion 262 of the groove 26 is covered by the lid portion 40 of the auxiliary member 4 joined to the plate 2, thereby isolating the internal space from the external space. The inner portion 263 of the groove 26 is surrounded by the connecting portion 41 of the auxiliary member 4 joined to the plate 2, and the shaft 3 is joined to the connecting portion 41 of the auxiliary member 4, thereby isolating the internal space from the external space. As a result, the first thermocouple 14 inserted into the groove 26 is isolated from the external space, and the temperature near the outer circumference of the plate 2 can be accurately detected by the first thermocouple 14.

[0078] Furthermore, in the ceramic heater 1 according to Embodiment 1, even when a load is applied to the auxiliary member 4 and the plate 2 when joining the auxiliary member 4 and the shaft 3 to the plate 2, it is unlikely that the auxiliary member 4 and the plate 2 will bend in any part. Therefore, when joining the plate 2 and the shaft 3, crushing of the groove 26 which serves as the thermocouple passage or cracking of the plate 2 is suppressed.

[0079] Furthermore, in the ceramic heater 1 according to Embodiment 1, the shaft 3 is joined to the connecting portion 41 of the auxiliary member 4, and the connecting portion 41 is joined to the plate 2, so the shaft 3 is indirectly joined to the plate 2 with the connecting portion 41 in between. In this way, by interposing the auxiliary member 4 between the plate 2 and the shaft 3, the number of joining interfaces between the plate 2 and the shaft 3 is increased compared to the case where the shaft 3 is directly joined to the plate 2. Since joining interfaces can be an obstacle to heat conduction, the increase in joining interfaces reduces heat dissipation from the plate 2 to the shaft 3. Therefore, temperature unevenness in the plate 2 can be suppressed, and the uniformity of the plate 2 can be improved. Moreover, since there are only a few members attached to the plate 2, such as the auxiliary member 4, temperature unevenness in the plate 2 can be suppressed, and the uniformity of the plate 2 can be improved.

[0080] <Embodiment 2> Next, the ceramic heater 10 according to Embodiment 2 will be described. The ceramic heater 10 according to Embodiment 2 basically has the same structure as the ceramic heater 1 according to Embodiment 1 and provides the same effects. However, Embodiment 2 In this embodiment, the method of attaching the auxiliary member 4 to the plate 2 differs from that of Embodiment 1. The differences from Embodiment 1 will be mainly described below.

[0081] Figure 15 is an exploded perspective view of the ceramic heater 10 according to Embodiment 2. Figures 16 to 21 are a top view, bottom view, front view, rear view, right side view, and left side view of the ceramic heater 10 according to Embodiment 2, respectively. Figure 22 is an enlarged cross-sectional view showing a portion of the ceramic heater 10 according to Embodiment 2 when it is cut by a vertical plane including line AA in Figure 17.

[0082] In the ceramic heater 1 according to Embodiment 1 described above, a recess 22 is formed in the plate 2, and the auxiliary member 4 is joined to the plate 2 with the auxiliary member 4 fitted into the recess 22. In contrast, in the ceramic heater 10 according to Embodiment 2, no recess 22 is formed in the plate 2, and the auxiliary member 4 is joined to the plate 2 with the auxiliary member 4 placed on the second main surface 21.

[0083] The groove 26 is formed in the second main surface 21 of the plate 2 so as to be recessed toward the first main surface 20. The groove 26 extends from the region inside the shaft 3 to the region outside the shaft 3, just before the outer circumference of the second main surface 21, on the second main surface 21 of the plate 2. That is, of the two ends of the groove 26, the starting end 260 and the ending end 261, the starting end 260 is located inside the shaft 3. The ending end 261 is located outside the shaft 3, just before the outer circumference of the second main surface 21. The first thermocouple 14 is inserted into the groove 26 from the inner portion 263 located inside the shaft 3, and then passed through the outer portion 262 located outside the shaft 3, thereby being inserted to near the outer circumference of the plate 2. In this embodiment, the groove 26 extends to just before the outer circumference of the second main surface 21, and the end 261 of the groove 26 is located just before the outer circumference of the second main surface 21. However, the end 261 of the groove 26 may be located away from the outer circumference of the second main surface 21, as long as it is located outside the shaft 3.

[0084] The auxiliary member 4 is joined to the second main surface 21 of the plate 2 such that the outer portion 262 of the groove 26 is covered by the cover portion 40, and the inner portion 263 of the groove 26 is located inside the connecting portion 41. The tip portion 32 of the shaft 3 is then joined to the connecting portion 41 of the auxiliary member 4, Plate 2 The auxiliary member 4 and the shaft 3 are integrated into one unit.

[0085] <Embodiment 3> Next, the ceramic heater 11 according to Embodiment 3 will be described. The ceramic heater 11 according to Embodiment 3 basically has the same structure as the ceramic heater 1 according to Embodiment 1 and provides the same effects. However, in Embodiment 3, the shape of the recess 22 formed in the plate 2 for fitting the auxiliary member 4 is different from that of Embodiment 1. The differences from Embodiment 1 will be mainly described below.

[0086] Figures 23 to 29 are exploded perspective views, plan views, bottom views, front views, rear views, right side views, and left side views of the ceramic heater 11 according to Embodiment 3, respectively. Figures 30 and 31 are enlarged cross-sectional views showing a portion of the ceramic heater 11 according to Embodiment 3. Figure 32 is a bottom view of the plate 2, which is a component of the ceramic heater 11 according to Embodiment 3.

[0087] In the ceramic heater 1 according to Embodiment 1 described above, an annular second recess 24 is formed in the plate 2, and the annular connecting portion 41 of the auxiliary member 4 is fitted into the second recess 24 such that a projection 25 is fitted inside it. In contrast, in the ceramic heater 11 according to Embodiment 3, the second recess 24 formed in the plate 2 so as to be continuous with the first recess 23 has a shallow bowl shape and appears to be formed by hollowing out a solid thin plate from the second main surface 21 side of the plate 2. In this embodiment, the shape of the second recess 24 in plan view is circular to match the outer shape of the connecting portion 41 of the auxiliary member 4, and the second recess 24 appears to be formed by hollowing out a thin circular disc from the second main surface 21 side of the plate 2. The second recess 24 is formed to include a flat circular bottom surface 242 against which the annular connecting portion 41 abuts, and an outer peripheral surface 240 facing the outer peripheral surface 410 of the connecting portion 41. In a plan view, the center of the second recess 24 coincides with the center of the second main surface 21, and the second recess 24 is formed in the plate 2 so as to be concentric with the second main surface 21.

[0088] Referring to Figure 31, the corner between the outer surface 240 and the bottom surface 242 in the second recess 24 may be chamfered. The chamfering may be C-chamfering or R-chamfering. C-chamfering means that the corner between the outer surface 240 and the bottom surface 242 is beveled at a predetermined angle (e.g., 45°). R-chamfering means that the corner between the outer surface 240 and the bottom surface 242 is rounded and smooth. Note that the rounding that is inevitably formed at the corner between the outer surface 240 and the bottom surface 242 when forming the second recess 24 in the plate 2 does not constitute chamfering. By chamfering the corner between the outer surface 240 and the bottom surface 242 in the second recess 24, when the connecting portion 41 of the auxiliary member 4 is pressed and joined to the plate 2 during the manufacturing of the ceramic heater 10, the stress generated in the second recess 24 of the plate 2 can be suppressed from concentrating at the corner between the outer surface 240 and the bottom surface 242. Therefore, the risk of damage to the second recess 24 can be reduced.

[0089] Referring to Figure 30, the corner between the side surface 232 and the bottom surface 233 of the first recess 23 may also be chamfered in the same way as the second recess 24. This prevents the stress generated in the first recess 23 of the plate 2 from concentrating at the corner between the side surface 232 and the bottom surface 233 when the lid portion 40 of the auxiliary member 4 is pressed and joined to the plate 2 during the manufacturing of the ceramic heater 10. Thus, the risk of damage to the first recess 23 can be reduced.

[0090] Referring to Figures 30 and 31, in the ceramic heater 11 according to Embodiment 3, when the connecting portion 41 of the auxiliary member 4 is fitted into the second recess 24, the bottom surface 242 of the second recess 24 is exposed on the inside of the connecting portion 41. On the second main surface 21 side of the plate 2, there is no projection 25 on the inside of the connecting portion 41, and a space S surrounded by the connecting portion 41 exists on the bottom surface 242 of the second recess 24.

[0091] Referring to Figure 23, the groove 26 is formed in the bottom surface 220 of the recess 22 of the plate 2 (the bottom surface 233 of the first recess 23 and the bottom surface 242 of the second recess 24) so ​​as to be recessed toward the first main surface 20. The groove 26 extends on the second main surface 21 side of the plate 2 from the area inside the shaft 3 to the area outside the shaft 3, just before the outer circumference of the second main surface 21. That is, of the two ends of the groove 26, the starting end 260 and the ending end 261, the starting end 260 is located inside the shaft 3. The ending end 261 is located outside the shaft 3, just before the outer circumference of the second main surface 21. The first thermocouple 14 is inserted into the groove 26 from the inner portion 263 located inside the shaft 3, and then passed through the outer portion 262 located outside the shaft 3, thereby being inserted to near the outer circumference of the plate 2. In this embodiment, the groove 26 extends to just before the outer circumference of the second main surface 21, and the end 261 of the groove 26 is located just before the outer circumference of the second main surface 21. However, the end 261 of the groove 26 may be located away from the outer circumference of the second main surface 21, as long as it is located outside the shaft 3.

[0092] Referring to Figure 30, the auxiliary member 4 is fitted into a recess 22 formed in the plate 2, similar to Embodiment 1, and is joined to the plate 2 in the recess 22. The second surface 402, which is the surface of the lid portion 40, is not particularly limited, but it is preferably flush with the second main surface 21 of the plate 2. The second surface 413, which is the surface of the connecting portion 41, may protrude from the second main surface 21 of the plate 2, or it may be flush with the second main surface 21 of the plate 2. Then, the tip portion 32 of the shaft 3 is joined to the connecting portion 41 of the auxiliary member 4, Plate 2 The auxiliary member 4 and the shaft 3 are integrated into one unit.

[0093] In the ceramic heater 11 according to Embodiment 3, the auxiliary member 4 is fitted into the recess 22, which facilitates the positioning of the auxiliary member 4 relative to the plate 2, and consequently, facilitates the positioning of the shaft 3 relative to the plate 2.

[0094] Furthermore, referring to Figures 30 and 31, regarding the connecting portion 41 of the auxiliary member 4 fitted into the recess 22 of the plate 2, there is a space S inside the connecting portion 41 where the protrusion 25 of the plate 2 does not exist. Therefore, it is possible to prevent heat from being transferred from the plate 2 to the auxiliary member 4 by thermal radiation from the protrusion 25. Referring to Figure 9, in the ceramic heater 1 according to Embodiment 1, in order to suppress heat transfer from the plate 2 to the auxiliary member 4, a gap G is formed between the inner circumferential surface 411 of the connecting portion 41 and the inner circumferential surface 241 of the second recess 24 (circumferential surface of the protrusion 25), thereby suppressing lateral heat conduction in which heat from the plate 2 is directly transferred from the plate 2 to the auxiliary member 4. In the ceramic heater 11 according to Embodiment 3, since there is no protrusion 25 inside the connecting portion 41 and a space S larger than the gap G is formed, lateral heat conduction does not occur where heat from the plate 2 is directly transferred from the plate 2 to the auxiliary member 4 via the protrusion 25, and heat from the plate 2 is not transferred from the plate 2 to the auxiliary member 4 by thermal radiation from the protrusion 25. Therefore, the transfer of heat from the plate 2 to the shaft 3 via the auxiliary member 4 is effectively suppressed. Thus, the uniformity of the heat on the first main surface 20 on which the wafer is placed on the plate 2 can be improved. Furthermore, because there is no protrusion 25 on the plate 2, the time required to raise the plate 2 to the desired temperature is shortened.

[0095] Furthermore, referring to Figures 30 and 31, since there is no projection 25 of plate 2 inside the connecting portion 41, when the connecting portion 41 is pressed and joined to plate 2 during the manufacturing of the ceramic heater 10, the stress generated in the second recess 24 of plate 2 does not concentrate at the corner between the inner circumferential surface 241 (circumferential surface of projection 25) and the bottom surface 242, as in the ceramic heater 1 according to Embodiment 1 shown in Figure 9. Therefore, the risk of damage to the second recess 24 can be reduced.

[0096] <Other variation 1> In the ceramic heater 1 according to Embodiment 1 described above, similar to Embodiment 3, the corner between the side surface 232 and the bottom surface 233 of the first recess 23, and the corner between the outer peripheral surface 240 and the bottom surface 242 of the second recess 24 may be chamfered. Similarly, the corner between the inner peripheral surface 241 and the bottom surface 242 of the second recess 24 may also be chamfered. This reduces the risk of damage to the first recess 23 and the second recess 24 of the plate 2 during the manufacturing of the ceramic heater 10.

[0097] <Other variations 2> In the ceramic heater 1 according to Embodiment 1 described above, the surface of the projection 25 surrounded by the second recess 24 is located at the same height as the second main surface 21 of the plate 2, but may be located lower than the second main surface 21 of the plate 2 on the first main surface 20 side, and a space surrounded by the inner circumferential surface 411 of the connecting portion 41 may be formed on the surface of the projection 25. According to this modification, the transfer of heat from the plate 2 to the auxiliary member 4 by thermal radiation from the projection 25 can be suppressed. As a result, the transfer of heat from the plate 2 to the shaft 3 via the auxiliary member 4 is well suppressed, and the uniformity of the heat on the first main surface 20 on which the wafer is placed on the plate 2 can be improved.

[0098] <Other variations 3> In the ceramic heaters 1, 10, and 11 according to embodiments 1, 2, and 3 described above, the lid portion 40 and connecting portion 41 of the auxiliary member 4 may have tapered portions on the first surfaces 401 and 412 that contact the plate 2. Figure 33 is a plan view of the modified auxiliary member 4. Figure 34 is a bottom view of the modified auxiliary member 4. Figure 35 is a side view of the modified auxiliary member 4. Figures 36(A) and (B) are cross-sectional views of the modified auxiliary member 4. Figures 37 and 38 are enlarged cross-sectional views showing a portion of the ceramic heater 11 according to embodiment 3 equipped with the modified auxiliary member 4.

[0099] For example, referring to Figure 36(A), in the lid portion 40 of the auxiliary member 4, at least one of the pair of opposing side surfaces 400 of the lid portion 40 is inclined inward to form an inclined surface 403 on the side of the first surface 401, thereby tapering at least a portion of the lid portion 40 on the side of the first surface 401. The side surface 400 of the lid portion 40 may be inclined over its entire length from the end on the side of the second surface 402 to the end on the side of the first surface 401, but in this case, the corner between the side surface 400 and the second surface 402 that does not contact the plate 2 becomes sharp and acute, resulting in a shape that is prone to damage such as chipping of the corners of the lid portion 40. For this reason, it is preferable that only a portion of the side surface 400 of the lid portion 40 on the side of the first surface 401 is an inclined surface 403. The width d1 of the first surface 401 is preferably 15 mm or more in order to strengthen the joint between the lid portion 40 and the plate 2.

[0100] Furthermore, although at least a portion of the lid portion 40 on the side of the first surface 401 is tapered by chamfering the corner between the first surface 401 and the side surface 400 with a C-chamfer, it may also be tapered by chamfering the corner between the first surface 401 and the side surface 400 with an R-chamfer. In other words, the side surface 400 of the lid portion 40 does not necessarily have to be inclined in a straight line, but may be inclined in a curved line.

[0101] For example, referring to Figure 36(B), in the connecting portion 41 of the auxiliary member 4, by inclining a portion of the inner circumferential surface 411 of the connecting portion 411 toward the first surface 412 side outward, that is, toward the outer circumferential surface 410 of the connecting portion 41, a first inclined surface 414 can be formed, thereby making at least a portion of the connecting portion 41 toward the first surface 412 side tapered. Alternatively, in addition to the above, by inclining a portion of the outer circumferential surface 410 of the connecting portion 411 toward the first surface 412 side inward, that is, toward the inner circumferential surface 411 of the connecting portion 41, a second inclined surface 415 can be formed, thereby making at least a portion of the connecting portion 41 toward the first surface 412 side tapered. The outer circumferential surface 410 and inner circumferential surface 411 of the connecting portion 41 may be inclined over their entire length from the end on the second surface 413 side to the end on the first surface 412 side. However, in this case, the corners between the outer circumferential surface 410 and the second surface 413 that do not contact the plate 2 become sharply pointed, resulting in a shape that is prone to damage such as chipping of the corners of the connecting portion 41. For this reason, it is preferable that only a portion of the outer circumferential surface 410 and inner circumferential surface 411 of the connecting portion 41 on the first surface 412 side be inclined surfaces 414 and 415. The width d2 of the first surface 412 is preferably 5 mm or more in order to strengthen the joint between the connecting portion 41 and the plate 2.

[0102] If the area of ​​the first surfaces 401 and 412 that contact the plate 2 on the lid portion 40 and connecting portion 41 of the auxiliary member 4 is small, vertical heat conduction, where heat from the plate 2 is directly transferred from the plate 2 to the auxiliary member 4, is suppressed. As a result, heat from the plate 2 is less likely to transfer to the shaft 3 via the auxiliary member 4, and the uniformity of heat on the first main surface 20 of the plate 2 on which the wafer is placed can be improved.

[0103] Furthermore, while at least a portion of the connecting portion 41 on the first surface 412 side is tapered by chamfering the corners between the first surface 412 and the inner circumferential surface 411, and between the first surface 412 and the outer circumferential surface 410, it may also be tapered by chamfering the corners between the first surface 412 and the inner circumferential surface 411, and between the first surface 412 and the outer circumferential surface 410 with a rounded edge. In other words, the inner circumferential surface 411 and the outer circumferential surface 410 of the connecting portion 41 do not necessarily need to be inclined in a straight line, but may be inclined in a curved manner.

[0104] Because the corner between the first surface 401 and the side surface 400 of the lid portion 40 is chamfered, and the corner between the first surface 412 and the inner circumferential surface 411, and the corner between the first surface 412 and the outer circumferential surface 410 of the connecting portion 41 are chamfered, when the lid portion 40 and the connecting portion 41 of the auxiliary member 4 are pressed and joined to the plate 2 during the manufacturing of the ceramic heater 10, it is possible to suppress the concentration of stress on the lid portion 40 and the connecting portion 41 at the aforementioned corners. Therefore, the risk of damage to the lid portion 40 and the connecting portion 41 of the auxiliary member 4 can be reduced.

[0105] From the viewpoint of suppressing stress concentration at such corners, it is preferable that the corners of both of the opposing pair of side surfaces 400 of the lid portion 40 between them and the first surface 401 are chamfered. Also, it is preferable that the corners of both the outer surface 410 and the inner surface 411 of the connecting portion 41 between them and the first surface 412 are chamfered.

[0106] Furthermore, from the viewpoint of effectively suppressing stress concentration at the aforementioned corners, it is preferable that the inclined surfaces 403, 414, and 415 formed by the chamfering are inclined over a long distance. Here, when we say that the inclined surfaces 403, 414, and 415 are inclined over a long distance, in the case of the lid portion 40, referring to Figure 36(A), it means that the distance w1 over which the inclined surface 403 is inclined is long. Specifically, the distance w1 is the distance over which the inclined surface 403 extends inward from the side surface 400 due to the inclination, that is, the distance from the side surface 400 side of the inclined surface 403 andThis refers to the distance along the horizontal direction between the inclined surface 403 and the end on the first surface 401 side. Note that the distance along the horizontal direction refers to the distance along the direction parallel to the first surface 401 in the cross-section of the lid portion 40, and the distance along the width direction in the plane of the lid portion 40.

[0107] In the connecting portion 41, referring to Figure 36(B), the distance w2 over which the first inclined surface 414 is inclined and the distance w3 over which the second inclined surface 415 is inclined are long. Specifically, the distance w2 is the distance over which the first inclined surface 414 is inclined away from the inner circumferential surface 411. outside Distance w3 is the distance that the second inclined surface 415 extends inward from the outer surface 410 due to the inclination, that is, the horizontal distance between the end of the first inclined surface 414 on the inner circumferential surface 411 side and the end of the first inclined surface 414 on the first surface 412 side.

[0108] The distances w1, w2, and w3 over which the inclined surfaces 403, 414, and 415 are tilted can be increased by increasing the tilt angle of the inclined surfaces 403, 414, and 415, or by increasing the height of the inclined surfaces 403, 414, and 415 (the vertical distance between the ends of the inclined surfaces 403, 414, and 415).

[0109] Furthermore, with respect to the connecting portion 41, it is preferable that the first inclined surface 414 is inclined over a longer distance than the second inclined surface 415, that is, the distance w2 over which the first inclined surface 414 is inclined is longer than the distance w3 over which the second inclined surface 415 is inclined, as shown in Figure 36(B). Specifically, if the inclination angle of the first inclined surface 414, that is, the angle at which the first inclined surface 414 is inclined with respect to the direction parallel to the first surface 412 in the cross-section of the connecting portion 41, and the inclination angle of the second inclined surface 415, that is, the angle at which the second inclined surface 415 is inclined with respect to the direction parallel to the first surface 412 in the cross-section of the connecting portion 41, are the same, it is preferable to make the height of the first inclined surface 414, that is, the vertical distance between the end of the first inclined surface 414 on the inner circumferential surface 411 side and the end of the first inclined surface 414 on the first surface 412 side, longer than the height of the second inclined surface 415, that is, the vertical distance between the end of the second inclined surface 415 on the outer circumferential surface 410 side and the end of the second inclined surface 415 on the first surface 412 side. In the connecting portion 41, if the distance w3 over which the second inclined surface 415 inclins is increased, the corner between the outer peripheral surface 410 and the second surface 413 tends to become an acute angle that is prone to damage. By making the distance w2 over which the first inclined surface 414 inclins longer than the distance w3 over which the second inclined surface 415 inclins, the connecting portion 41 can be made into a shape where the corner between the outer peripheral surface 410 and the second surface 413 does not become an acute angle, while ensuring the width d2 of the first surface 412 and making the inclined surfaces 414 and 415, which are effective in suppressing stress concentration, as large as possible.

[0110] <Other variations 4> In the ceramic heaters 1 and 11 according to the embodiments 1 and 3 described above, a gap G is formed between the side surface of the auxiliary member 4 fitted into the recess 22 of the plate 2 (the side surface 400 of the lid portion 40 and the outer peripheral surface 410 of the connecting portion 41) and the side surface of the recess 22 (the side surface 232 of the first recess 23 and the outer peripheral surface 240 of the second recess 24), but this gap G may be filled. Also, in the ceramic heater 1 according to embodiment 1 described above, a gap G is formed between the inner peripheral surface 411 of the connecting portion 41 and the inner peripheral surface 241 of the second recess 24, but this gap G may be filled.

[0111] Figures 39 and 40 are enlarged cross-sectional views showing a portion of a ceramic heater 11 according to Embodiment 3, in which the gap G is filled with a filler material 50. The filler material 50 can be ceramics, resin, or the like. For example, the gap G is filled with the filler material 50 by filling the gap G with ceramic powder of the same material as the plate 2 and firing it. Alternatively, the gap G is filled with the filler material 50 by filling the gap G with a liquid thermosetting resin such as epoxy resin or silicone resin and curing it. The resin may be a composite resin containing fillers such as ceramics or metal.

[0112] If the gap G is filled with the filler material 50, the risk of unwanted materials such as processing debris and dust accumulating in the gap G in the manufactured ceramic heaters 1 and 10 can be reduced. For example, when performing chemical vapor deposition (CVD) or etching on a wafer in semiconductor manufacturing equipment, if unwanted materials accumulate in the gap G of the ceramic heaters 1 and 10, there is a concern that the unwanted materials may scatter onto the wafer during processing, adversely affecting the wafer processing. Also, if the gas used in wafer processing enters the gap G and corrosion occurs at the joint surface between the auxiliary member 4 and the plate 2, there is a concern that the joint strength of the auxiliary member 4 and the plate 2 will decrease. If the gap G is filled with the filler material 50, the above concerns can be eliminated. Whether to fill the gap G with the filler material 50 or leave the gap G as is without filling it with the filler material 50 can be appropriately selected by considering the advantages of each.

[0113] <Other variations 5> In the ceramic heater 1 and 10 according to the embodiments 1 and 2 described above, the connecting portion 41 of the auxiliary member 4 is an annular ring plate, but it may also be a solid disc. In this case, the connecting portion 41 has a through hole that communicates with a groove 26 formed in the plate 2. As a result, the first thermocouple 14 is inserted through the through hole in the connecting portion 41 and then passed through the groove 26 in the plate 2, thereby being inserted to near the outer circumference of the plate 2. Note that if the connecting portion 41 of the auxiliary member 4 is an annular ring plate, the volume of the auxiliary member 4 can be reduced, and the proportion of the auxiliary member 4 to the entire plate 2 including the auxiliary member 4 is reduced. Note that in the ceramic heater 11 according to embodiment 3, the connecting portion 41 of the auxiliary member 4 may also be a solid disc.

[0114] <Other variations 6> In the ceramic heater 1 and 10 according to the embodiments 1 and 2 described above, there is one groove 26 formed in the plate 2, and the auxiliary member 4 includes one cover portion 40 accordingly. However, the number of grooves 26 formed in the plate 2 is not limited to one, and the auxiliary member 4 may include multiple cover portions 40 depending on the number of grooves 26. In this case, the multiple cover portions 40 may extend in different directions from different locations on a single connecting portion 41. Similarly, in the ceramic heater 11 according to embodiment 3, the number of grooves 26 formed in the plate 2 is not limited to one, and the auxiliary member 4 may include multiple cover portions 40 depending on the number of grooves 26.

[0115] The embodiments disclosed herein should be understood to be illustrative in all respects and not restrictive in any way. The scope of the invention is defined not by the foregoing description but by the claims, and all modifications within the meaning and scope equivalent to the claims are intended. [Explanation of Symbols]

[0116] 1 Ceramic heater according to Embodiment 1, 2 Plate, 3 Shaft, 4 Auxiliary member, 5 Resistive heating element, 6 Electrode, 7 Support base, 8 O-ring, 9 Pressing member, 10 Ceramic heater according to Embodiment 2, 11 Ceramic heater according to Embodiment 3, 12 Terminal, 13 Terminal, 14 First thermocouple, 15 Second thermocouple, 16 Terminal, 17 First power supply rod, 18 Second power supply rod, 19 Third power supply rod, 20 First main surface, 21 Second main surface, 22 Recess, 23 First recess, 24 Second recess, 25 Projection, 26 Groove, 27 First groove, 28 Second groove, 29 Recess, 30 First opening, 31 Second opening, 32 Tip of shaft, 33 Base of shaft, 34 Small diameter part of shaft, 35 Large diameter part of shaft, 40 Cover, 41 50 Connecting part, 220 Filler, 220 Bottom surface of recess, 230 Start of first recess, 231 End of first recess, 232 Side surface of first recess, 233 Bottom surface of first recess, 240 Outer side surface (outer peripheral surface) of second recess, 241 Inner side surface (inner peripheral surface) of second recess, 242 Bottom surface of second recess, 260 Start of groove, 261 End of groove, 262 Outer part of groove, 263 Inner part of groove, 400 Side surface of lid, 401 First surface of lid, 402 Second surface of lid, 403 Inclined surface of lid, 410 Outer side surface (outer peripheral surface) of connecting part, 411 Inner side surface (inner peripheral surface) of connecting part, 412 First surface of connecting part, 413 Second surface of connecting part, 414 First inclined surface, 415 Second inclined surface, G Gap, d1 The width of the first surface of the lid, d2 the width of the ring on the first surface of the connecting part, and w1 the inclined surface. Slope w2 is the distance the first inclined surface slopes, and w3 is the distance the second inclined surface slopes.

Claims

1. A plate-shaped plate having a first main surface on which a wafer is placed and a second main surface positioned at a distance in the thickness direction from the first main surface, and having a built-in resistance heating element that generates heat when an electric current is applied, A cylindrical shaft having a first opening and a second opening located at both ends in the axial direction, and supporting the plate on the second main surface, A plate-shaped auxiliary member joined to the aforementioned plate, Equipped with, The plate has a groove formed therein that is recessed from the second main surface toward the first main surface and extends from a starting end located inside the shaft to a terminal end located outside the shaft. The aforementioned auxiliary member is A cover portion extends along the outer portion, which is the part of the groove located outside the shaft, and covers the outer portion, An annular connecting portion sandwiched between the plate and the shaft, and to which the tip portion of the shaft that surrounds the first opening is joined, Includes, The plate has a recess formed therein, which is indented from the second main surface toward the first main surface and into which the auxiliary member is fitted. The recess includes a first recess into which the lid portion is fitted, and a second recess into which the connecting portion is fitted and which is connected to the first recess, The second recess is formed in an annular shape and has an inner surface facing the inner surface of the connecting portion. The groove is A first groove is formed on the bottom surface of the first recess and the bottom surface of the second recess so as to be recessed toward the first main surface, A second groove is formed on the inner side of the shaft, on the second main surface of the plate, so as to be recessed toward the first main surface, and communicating with the first groove; Includes, In the connecting portion of the auxiliary member, at least a portion of the first surface that abuts the plate is tapered. At least a portion of the inner circumferential surface of the connecting portion on the side of the first surface is a first inclined surface that slopes toward the outer circumferential surface of the connecting portion. At least a portion of the outer circumferential surface of the connecting portion on the side of the first surface is a second inclined surface that slopes toward the inner circumferential surface of the connecting portion. A ceramic heater in which the first inclined surface is inclined over a longer distance than the second inclined surface.

2. A plate-shaped plate having a first main surface on which a wafer is placed and a second main surface positioned at a distance in the thickness direction from the first main surface, and having a built-in resistance heating element that generates heat when an electric current is applied, A cylindrical shaft having a first opening and a second opening located at both ends in the axial direction, and supporting the plate on the second main surface, A plate-shaped auxiliary member joined to the aforementioned plate, Equipped with, The plate has a groove formed therein that is recessed from the second main surface toward the first main surface and extends from a starting end located inside the shaft to a terminal end located outside the shaft. The aforementioned auxiliary member is A cover portion extends along the outer portion, which is the part of the groove located outside the shaft, and covers the outer portion, An annular connecting portion sandwiched between the plate and the shaft, and to which the tip portion of the shaft that surrounds the first opening is joined, Includes, The plate has a recess formed therein, which is indented from the second main surface toward the first main surface and into which the auxiliary member is fitted. The recess includes a first recess into which the lid portion is fitted, and a second recess into which the connecting portion is fitted and which is connected to the first recess, The second recess is formed in an annular shape and has an inner surface facing the inner surface of the connecting portion. The groove is A first groove is formed on the bottom surface of the first recess and the bottom surface of the second recess so as to be recessed toward the first main surface, A second groove is formed on the inner side of the shaft, on the second main surface of the plate, so as to be recessed toward the first main surface, and communicating with the first groove; Includes, A gap is formed in at least a portion between the side surface of the auxiliary member and the side surface of the recess, and in at least one of at least a portion between the inner circumferential surface of the connecting portion and the inner circumferential surface of the second recess. The aforementioned gap is filled with a filler material. A ceramic heater in which the filler material is resin or ceramic.

3. The ceramic heater according to claim 1, wherein a gap is formed in at least a portion between the side surface of the auxiliary member and the side surface of the recess.

4. The ceramic heater according to claim 1, wherein a gap is formed in at least a portion between the inner surface of the connecting portion and the inner surface of the second recess.

5. A plate-shaped plate having a first main surface on which a wafer is placed and a second main surface positioned at a distance from the first main surface in the thickness direction, and having a built-in resistance heating element that generates heat when an electric current is applied, A cylindrical shaft having a first opening and a second opening located at both ends in the axial direction, and supporting the plate on the second main surface, A plate-shaped auxiliary member joined to the aforementioned plate, Equipped with, The plate has a groove formed therein that is recessed from the second main surface toward the first main surface and extends from a starting end located inside the shaft to a terminal end located outside the shaft. The aforementioned auxiliary member is A cover portion extends along the outer portion, which is the part of the groove located outside the shaft, and covers the outer portion, An annular connecting portion sandwiched between the plate and the shaft, and to which the tip portion of the shaft that surrounds the first opening is joined, Includes, The plate has a recess formed therein, which is indented from the second main surface toward the first main surface and into which the auxiliary member is fitted. The recess includes a first recess into which the lid portion is fitted, and a second recess into which the connecting portion is fitted and which is connected to the first recess, The second recess is formed to have a flat bottom surface against which the connecting portion abuts and an outer surface facing the outer surface of the connecting portion, and a space exists inside the connecting portion on the flat bottom surface. A ceramic heater in which the grooves are formed on the bottom surface of the first recess and the bottom surface of the second recess so as to be recessed toward the first main surface.

6. The ceramic heater according to claim 2 or claim 5, wherein at least one of the lid portion and the connecting portion of the auxiliary member has a tapered shape on the first surface side that contacts the plate.

7. The ceramic heater according to claim 6, wherein at least a portion of the inner circumferential surface of the connecting portion on the side of the first surface is a first inclined surface that slopes toward the outer circumferential surface of the connecting portion.

8. At least a portion of the outer circumferential surface of the connecting portion on the side of the first surface is a second inclined surface that slopes toward the inner circumferential surface of the connecting portion. The ceramic heater according to claim 7, wherein the first inclined surface is inclined over a longer distance than the second inclined surface.

9. The ceramic heater according to claim 3 or claim 4, wherein the gap is filled with a filler material.

10. The plate and the shaft are mainly composed of aluminum nitride. The ceramic heater according to any one of claims 1 to 5, wherein the auxiliary member mainly consists of aluminum nitride and does not contain yttria.

11. A plate-shaped plate, mainly composed of aluminum nitride and containing a resistive heating element that generates heat when an electric current is applied, has a first main surface and a second main surface, which are spaced apart in the thickness direction. The plate has a groove that is recessed from the second main surface toward the first main surface and extends from the center of the second main surface toward the outer circumference of the second main surface. A step of installing a plate-shaped auxiliary member, which includes a lid portion and an annular connecting portion and is mainly composed of aluminum nitride and does not contain yttria, onto the plate via a flux containing rare earth components, such that the outer portion of the second main surface in the groove is covered by the lid portion extending along the outer portion, and the inner portion of the second main surface in the groove is located inside the connecting portion. A step of installing a cylindrical shaft, mainly composed of aluminum nitride, onto the auxiliary member via the flux such that the tip portion, which is the region surrounding the first opening of the two openings located at both ends in the axial direction, abuts against the connecting portion, The process of applying pressure to the shaft while simultaneously joining the connecting portion of the shaft and the auxiliary member, and the connecting portion of the auxiliary member and the plate, and applying a load to the lid portion of the auxiliary member with a pressing member while joining the lid portion of the auxiliary member and the plate, A method for manufacturing a ceramic heater equipped with [the necessary components].

12. The method for manufacturing a ceramic heater according to claim 11, wherein at least a portion of the inner circumferential surface of the connecting portion on the side of the first surface that abuts the plate is inclined toward the outer circumferential surface of the connecting portion.

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