Heater with shaft

Abstract

To provide a technology that suppresses deterioration in airtightness inside a shaft in a shaft-equipped heater.SOLUTION: A shaft-equipped heater includes: a substantially flat plate member having a planar first main surface and a planar second main surface that is a back surface of the first surface; and a substantially cylindrical shaft joined to a second main surface side of the plate member via a joint. One of the plate member and the shaft includes a convex portion that protrudes from the second main surface of the plate member, and the other includes a concave portion that faces the convex portion. The convex portion and the concave portion are joined, and at least a portion of each joint surface of the convex portion and the concave portion is inclined with respect to the second main surface.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a heater with a shaft.

Background Art

[0002] Conventionally, in semiconductor manufacturing equipment, an apparatus (for example, an electrostatic chuck, a heater, etc.) in which a plate-like member on which a semiconductor wafer is placed and a support member that supports the plate-like member are joined has been used (for example, see Patent Documents 1 to 3, etc.).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a heater with a shaft to which a shaft serving as a support member is joined, a metal terminal for supplying power to a heating element or the like may be disposed inside the shaft. When such a heater with a shaft is used in a semiconductor manufacturing apparatus, if the joinability between the plate-like member and the shaft is not sufficient, or if a crack occurs in the joined portion and the airtightness of the shaft is not sufficient, for example, a halogen-based gas used in the semiconductor manufacturing process may enter the shaft and corrode the metal terminal.

[0005] In Patent Document 2, a technique is proposed in which the outer side of a circular recess provided on the back surface of a plate is made into a joining region with a shaft, and the region for performing surface processing for joining is narrowed to reduce the work load. According to this technique, the joining area between the plate and the shaft is reduced, and there is a concern that the airtightness inside the shaft may decrease.

[0006] In Patent Document 3, a technique has been proposed to suppress the concentration of local thermal stress and prevent the occurrence of cracks or the like by shifting the radial center of the plate and the radial center of the shaft to relieve stress concentration. In this technique, there is a problem that the left-right symmetry of the product itself is impaired and it is difficult to ensure uniform heat distribution.

[0007] In Patent Document 1, a technique has been proposed to enable stable holding of a wafer by forming depressions of about 40 to 60 μm both in the outer shape and the internal electrodes. According to this technique, due to the concave shape of the mounting surface, the contact between the wafer and the mounting surface is not constant, and there is a problem with uniform heat distribution.

[0008] The present invention has been made to solve the above-described problems, and an object thereof is to provide a technique for suppressing a decrease in airtightness inside a shaft in a heater with a shaft.

Means for Solving the Problems

[0009] (1) According to one aspect of the present invention, there is provided a heater with a shaft including a substantially flat plate-shaped member having a planar first main surface and a planar second main surface which is the back surface of the first surface, and a substantially cylindrical shaft joined to the second main surface side of the plate-shaped member via a joining portion. In this heater with a shaft, either one of the plate-shaped member and the shaft has a convex portion protruding with respect to the second main surface of the plate-shaped member, and the other has a concave portion facing the convex portion, the convex portion and the concave portion are joined, and at least a part of the joining surface between the convex portion and the concave portion is inclined with respect to the second main surface.

[0010] According to this configuration, the plate-shaped member and the shaft each have a convex portion or a concave portion that protrudes with respect to the second main surface of the plate-shaped member, and at least a part of the joint surface between the convex portion and the concave portion is inclined with respect to the second main surface. Therefore, compared with the case where the plate-shaped member and the shaft do not have a convex portion or a concave portion, or the case where the joint surface between the convex portion and the concave portion is parallel or perpendicular to the second main surface, the area of the joint surface becomes larger. Therefore, the joint reliability between the plate-shaped member and the shaft can be improved.

[0011] (2) The heater with a shaft according to the above aspect, wherein at least one of the material of the plate-shaped member and the material of the shaft and the material of the joint portion have different coefficients of thermal expansion, and the joint portion is in a cross section including the central axis of the shaft, from at least one of the outer peripheral surface and the inner peripheral surface of the shaft, within a range of 1 mm in the direction along the second main surface, may have a gap.

[0012] When the temperature changes during the use of the heater with a shaft, stress may be generated in the joint portion according to the difference in the coefficient of thermal expansion. According to this aspect, since the joint portion has a gap, the amount of the joint portion is reduced compared with the case where there is no gap, and the stress can be reduced. Further, in the joint portion, a gap is formed in the vicinity of the outer peripheral surface or the inner peripheral surface of the shaft where stress concentration is likely to occur, and the stress at that location can be relieved. Therefore, peeling and crack generation in the joint portion can be suppressed, and a decrease in airtightness inside the shaft can be suppressed.

[0013] (3) The heater with a shaft according to the above aspect, wherein the gap in the joint portion may be a discontinuous substantially annular shape concentric with the shaft. By doing so, since the gap does not communicate the inside and the outside of the shaft, a decrease in airtightness inside the shaft can be suppressed.

[0014] (4) A heater with a shaft according to the above-described embodiment, wherein at least one of the material of the plate-like member and the material of the shaft has a different coefficient of thermal expansion from the material of the joint portion, and the joint portion has an average thickness within a range of 1 mm in the direction along the second main surface from at least one of the outer peripheral surface and the inner peripheral surface of the shaft in a cross section including the central axis of the shaft may be thicker than the average thickness of the remaining portion. The greater the amount of the joint portion, the greater the stress associated with the thermal expansion difference. If the amount of the joint portion is too small, the joint property may not be sufficient. On the other hand, according to this embodiment, by increasing the thickness of the joint portion in the vicinity of at least one of the outer peripheral surface and the inner peripheral surface of the shaft to improve the joint property and reducing the thickness of the other portions to reduce the stress, it is possible to suppress a decrease in airtightness within the shaft.

[0015] Note that the present invention can be realized in various aspects, for example, in the form of a semiconductor manufacturing apparatus including a heater with a shaft, a product including a heater with a shaft, a manufacturing method of a heater with a shaft, and the like.

Brief Description of Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0017] <First Embodiment> FIG. 1 is an explanatory diagram showing a schematic configuration of a ceramic heater 1 according to the first embodiment. FIG. 2 is an explanatory diagram schematically showing an XZ cross-sectional configuration of the ceramic heater 1. In the figure, for specifying directions, XYZ axes orthogonal to each other are shown. In FIG. 2, the positive Y-axis direction is the direction toward the back side of the paper surface. In this specification, for convenience, the positive Z-axis direction is referred to as the upward direction, and the negative Z-axis direction is referred to as the downward direction, but the ceramic heater 1 may actually be installed in a direction different from such an orientation.

[0018] The ceramic heater 1 is a device that heats an object (for example, a wafer W) to a predetermined processing temperature while holding it, and is provided in, for example, a thin film forming device (for example, a CVD (Chemical Vapor Deposition) device, a PVD (Physical Vapor Deposition) device, an ALD (Atomic Layer Deposition) device, a sputtering device, an etching device (for example, a plasma etching device), etc.) used in a semiconductor manufacturing process. In other embodiments, the ceramic heater 1 may be configured as a shower head (shower plate) provided in, for example, a microwave-excited plasma device or the like.

[0019] The ceramic heater 1 is a heater with a shaft, which includes a plate-like member 10 on which a heating object is placed, and a substantially hollow cylindrical shaft 20 joined to the plate-like member 10 via a joint portion 30 (FIG. 2).

[0020] The plate-shaped member 10 is a plate-shaped member having a substantially circular planar first main surface 11 and a planar second main surface 12 which is the back surface of the first main surface 11. As shown in FIG. 2, the plate-shaped member 10 is provided with a concave portion 16 recessed with respect to the second main surface 12 on the second main surface 12 side. In the present embodiment, the concave portion 16 is formed in a bowl shape, and the cross-sectional shape (FIG. 2) is substantially semi-elliptical (a curve convex in the positive Z-axis direction). The joint surface S16 with the convex portion 26 (described later) of the concave portion 16 is inclined with respect to the second main surface 12 as shown in the drawing.

[0021] In the present embodiment, the plate-shaped member 10 is mainly composed of ceramic. In the present embodiment, a ceramic mainly composed of aluminum nitride is used, but the main component of the ceramic is not limited to aluminum nitride, and for example, alumina or the like may be used as the main component. The diameter of the plate-shaped member 10 is, for example, about 100 mm to 500 mm, and the thickness of the plate-shaped member 10 is, for example, about 3 mm to 20 mm. In the present embodiment, the main component means the most abundant composition. The plate-shaped member 10 may have a structure in which a plurality of ceramic plates are laminated, or may be a single plate.

[0022] Inside the plate-shaped member 10, a heater 50 (FIG. 2), which is a linear resistance heating element formed of a conductive material (for example, a material mainly composed of tungsten, molybdenum, etc.), is disposed. The heater 50 is connected to an external power source (not shown) via a power supply terminal 40 disposed inside the shaft 20, and generates heat when energized. The heater 50 is formed to have substantially the same size as the first main surface 11 so that the heat generated by energization can be evenly transmitted to the wafer W placed on the first main surface 11. Since the first main surface 11 of the plate-shaped member 10 is planar, the contact with the wafer W is constant, and uniform heat distribution can be ensured.

[0023] The shaft 20 is a substantially hollow cylindrical member extending in the Z-axis direction and has a through hole along the Z-axis direction. The shaft 20 is joined to the plate-like member 10 such that the central axis LO is along the Z-axis direction, coincides with the central axis of the plate-like member 10, and is substantially perpendicular to the second main surface 12 of the plate-like member 10. Since the shaft 20 is joined to the plate-like member 10 in this way, the ceramic heater 1 is symmetric about the left and right and the heat uniformity can be ensured.

[0024] The shaft 20 has a cylindrical portion 20t and a flange portion 20f provided at one end of the cylindrical portion 20t. The planar shape (XY plane) of the cylindrical portion 20t is an annular shape (doughnut shape), the outer diameter is, for example, about 30 mm to 90 mm, and the inner diameter is, for example, about 10 mm to 60 mm. The planar shape (XY plane) of the flange portion 20f is an annular shape (doughnut shape) concentric with the cylindrical portion 20t, the outer diameter is larger than that of the cylindrical portion 20t, for example, about 40 mm to 100 mm, and the inner diameter coincides with that of the cylindrical portion 20t. The outer peripheral surface 22 of the shaft 20 is composed of the outer peripheral surface 22t of the cylindrical portion 20t and the outer peripheral surface 22f of the flange portion 20f. As described above, a pair of power supply terminals 40 are accommodated in the through hole of the cylindrical portion 20t. The cross-sectional ( XY cross-section) shape of the shaft 20 is not limited to a substantially circular annular shape and may be a substantially elliptical annular shape.

[0025] The shaft 20 has a convex portion 26 that faces the concave portion 16 of the plate-like member 10 and protrudes with respect to the second main surface 12 of the plate-like member 10. The shape of the convex portion 26 corresponds to the concave portion 16 of the plate-like member 10. That is, the joint surface S26 of the convex portion 26 with the concave portion 16 is inclined with respect to the second main surface 12 as shown in the figure. The convex portion 26 protrudes most (has a large protrusion amount) with respect to the second main surface 12 on the inner peripheral surface 24 of the shaft 20. The plate-like member 10 and the shaft 20 are joined by joining the concave portion 16 of the plate-like member 10 and the convex portion 26 of the shaft 20 via a joint portion 30. By cutting the ceramic heater 1 in a plane including the central axis LO of the shaft 20 and observing it with, for example, a SEM (scanning electron microscope), the cross-sectional shapes of the concave portion 16, the convex portion 26, and the joint portion 30 can be visually recognized.

[0026] The shaft 20 is made mainly of ceramic, like the plate-like member 10. In this embodiment, like the plate-like member 10, a ceramic mainly composed of aluminum nitride is used. However, the main component of the ceramic is not limited to aluminum nitride. For example, alumina or the like may be used as the main component, or a ceramic different from the plate-like member 10 may be used.

[0027] FIG. 3 is an explanatory diagram of a method for measuring the amount of deformation of the concave portion. In FIG. 3, the vicinity of the concave portion 16 in the cross section shown in FIG. 2 is enlarged and shown. First, as shown in FIG. 3, cut along a cross section including the central axis LO of the shaft 20 and perform cross-sectional polishing so that the bonding interface can be seen. Next, plot the coordinate positions (C1 and C2 in the figure) of the ends of the joint, and obtain the equation of the straight line LF connecting C1 and C2. Then, for the portion corresponding to the left side of the convex portion 26 in FIG. 3, measure the coordinates of five or more points at equal intervals. In FIG. 3, only two points are shown for convenience of the drawing. Similarly, measure the coordinates of five or more points for the portion corresponding to the right side of the convex portion 26 in FIG. 3. Then, obtain the distance between the straight line and the point, and use that distance as the amount of deformation. In the plate-like member 10, although the second main surface 12 is a plane, there are some irregularities. The amount of deformation of the concave portion 16 of the plate-like member 10 is clearly larger than the irregularities of the deformation amount of the second main surface 12, and it is recessed with respect to the second main surface 12 to the extent that it can be distinguished from the irregularities of the second main surface 12. In this embodiment, the maximum value of the amount of deformation of the concave portion 16 is 5 μm or more.

[0028] FIG. 4 is an explanatory diagram schematically showing the cross-sectional configuration of the joint portion 30. In FIG. 4, the P portion shown in FIG. 2 is enlarged and shown. FIG. 5 is an explanatory diagram schematically showing the planar configuration of the joint portion 30. In FIG. 5, the positive direction of the Z axis is the direction toward the front side of the paper surface. The cross section shown in FIG. 4 corresponds to the A-A cross section shown in FIG. 5.

[0029] As described above, the joint portion 30 joins the concave portion 16 of the plate-like member 10 and the convex portion 26 of the shaft 20. In the present embodiment, the joint portion 30 is formed of, for example, a ceramic adhesive mainly composed of alumina (Al2O3). In the present embodiment, the plate-like member 10 and the shaft 20 are mainly composed of a ceramic mainly composed of aluminum nitride, and the joint portion 30 is mainly composed of a ceramic mainly composed of alumina, and they have different coefficients of thermal expansion from each other.

[0030] The line L1 shown in FIGS. 4 and 5 indicates the outer peripheral surface 22 of the shaft 20 (specifically, the outer peripheral surface 22f of the flange portion 20f), and the line L2 indicates a position 1 mm in the direction along the second main surface 12 of the plate-like member 10 from the outer peripheral surface 22 of the shaft 20. That is, the distance D in the direction along the second main surface 12 between the line L1 and the line L2 is 1 mm. As shown in the drawing, the joint portion 30 has voids P1 and P2. Since the joint portion 30 has the voids P1 and P2, the amount of the joint portion 30 is reduced as compared with the case where there are no voids, and the stress generated in the joint portion 30 based on the difference in the coefficient of thermal expansion can be reduced.

[0031] The voids P1 and P2 are each a discontinuous substantially annular shape concentric with the shaft 20. That is, even if the joint portion 30 has voids, the internal space of the shaft 20 and the external space of the shaft 20 are not connected by the voids, so the airtightness inside the shaft 20 can be ensured.

[0032] The void P1 is within a range of 1 mm in the direction along the second main surface 12 from the outer peripheral surface 22 of the shaft 20. Therefore, the stress in the vicinity of the outer peripheral surface 22 of the shaft where stress concentration is likely to occur can be released, and peeling and crack generation in the joint portion 30 can be suppressed. The void P2 is inside the void P1 and is between the inner peripheral surface 24 of the shaft 20 and the void P1.

[0033] As shown in FIG. 4, in a cross section including the central axis LO of the shaft 20, the average thickness within a range of 1 mm in the direction from the outer peripheral surface 22 of the shaft 20 along the second main surface 12 of the plate-like member 10 is thicker than the average thickness of the remaining portion. Therefore, the joint property in the vicinity of the outer peripheral surface 22 of the shaft 20 can be improved, and by making other portions thinner to reduce stress, a decrease in airtightness within the shaft 20 can be suppressed. The thickness of the joint portion 30 uses the average value measured at a plurality of locations at equal intervals using the same cross section as the measurement method of the deformation amount of the concave portion described above.

[0034] FIG. 6 is an explanatory diagram of a method for forming the concave portion 16 and the convex portion 26. As shown in FIG. 6(A), a first plate-like member 10p that becomes the plate-like member 10 and a first shaft 20p that becomes the shaft 20 are prepared. The first plate-like member 10p has a first concave portion 16p that becomes the concave portion 16 formed on the second main surface 12 side. The first shaft 20p has a first flange portion 20fp with a flat end surface. As will be described later, the shaft 20 is formed by deforming the end portion of the first flange portion 20fp. A ceramic adhesive 30p that becomes the joint portion 30 is applied to the end surface of the first shaft 20p, and the first shaft 20p is placed on the first plate-like member 10p so that the first flange portion 20fp is placed on the first concave portion 16p of the first plate-like member 10p.

[0035] Then, the first plate-like member 10p and the first shaft 20p are heated to a high temperature (for example, about 1400 to 1700 ° C.), and the cylindrical portion 20t of the first shaft 20p is pressurized from 0.1 MPa to 20 MPa (in the figure, the force F is indicated by a white arrow). Due to heat and pressure, the first plate-like member 10p, the first shaft 20p, and the ceramic adhesive 30p deform with each other to fill the gaps, so the joint surface shape is curved. Thereafter, by processing the first main surface 11p of the first plate-like member 10p to be flat, a flat first main surface 11 is formed, and a shape deformed only inside can be left (FIG. 6(B)). The manufacturing method of the ceramic heater 1 of the present embodiment includes the above steps.

[0036] Thus, by manufacturing the ceramic heater 1 in which the cylindrical portion 20t of the first shaft 20p is pressed and the plate-like member 10 and the shaft 20 are joined, an annular gap P1 interrupted in the range of 1 mm from the outer peripheral surface 22 can be formed at the joint portion 30. Further, the average thickness in the range of 1 mm from the outer peripheral surface 22 at the joint portion 30 can be made thicker than the average thickness of the remaining portion.

[0037] As described above, according to the ceramic heater 1 of the present embodiment, the plate-like member 10 has the concave portion 16, the shaft 20 has the convex portion 26 facing the concave portion 16, and the joint surfaces S16 and S26 between the convex portion 26 and the concave portion 16 are inclined with respect to the second main surface 12. Therefore, the area of the joint surface becomes wider as compared with the case where the plate-like member and the shaft do not include convex or concave portions, or the case where the joint surface between the convex portion and the concave portion is parallel or perpendicular to the second main surface. Therefore, the joint reliability between the plate-like member 10 and the shaft 20 can be improved.

[0038] In the ceramic heater 1, the first main surface 11 which is the mounting surface of the wafer W is planar. Therefore, the uniformity of heat transfer to the wafer W can be improved as compared with the case where the mounting surface of the wafer W is curved. Further, the uniformity of heat radiation to the chamber can be improved.

[0039] The ceramic heater 1 has gaps P1 and P2. When stress is generated at the joint portion 30 according to the difference in the coefficient of thermal expansion between the plate-like member 10 and the joint portion 30 or the shaft 20 and the joint portion 30 along with the temperature change during the use of the ceramic heater 1. According to the ceramic heater 1 of the present embodiment, since the joint portion 30 has the gaps P1 and P2, the amount of the joint portion 30 is reduced as compared with the case where there are no gaps, and the stress can be reduced.

[0040] In the ceramic heater 1, in a cross-section including the central axis LO of the shaft 20, the joint portion 30 has a gap P1 within a range of 1 mm in the direction along the second main surface 12 from the outer peripheral surface 22 of the shaft 20. As described above, with the temperature change during the use of the ceramic heater 1, stress may be generated in the joint portion 30 according to the difference in the coefficient of thermal expansion between the plate-like member 10 and the joint portion 30, or between the shaft 20 and the joint portion 30. In the present embodiment, in the joint portion 30, a gap P1 is formed in the vicinity of the outer peripheral surface 22 of the shaft 20 where stress concentration is likely to occur, and the stress at this location can be released. Therefore, peeling and crack generation in the joint portion 30 can be suppressed, and a decrease in the airtightness within the shaft 20 can be suppressed.

[0041] In the ceramic heater 1, the gaps P1 and P2 in the joint portion 30 are discontinuous annular shapes concentric with the shaft 20. Since the gaps P1 and P2 do not communicate the inside and outside of the shaft 20, a decrease in the airtightness within the shaft 20 can be suppressed.

[0042] The amount of the joint portion joining the plate-like member 10 and the shaft 20 is such that the greater the amount, the greater the stress associated with the difference in thermal expansion, and if it is too small, the joinability is insufficient. In the ceramic heater 1 of the present embodiment, in a cross-section including the central axis LO of the shaft 20, the average thickness within a range of 1 mm in the direction along the second main surface 12 from the outer peripheral surface 22 of the shaft 20 in the joint portion 30 is made thicker than the average thickness of the remaining portion. That is, by increasing the thickness of the joint portion 30 in the vicinity of the outer peripheral surface 22 of the shaft 20 to improve the joinability and making other portions thinner to reduce stress, a decrease in the airtightness within the shaft 20 can be suppressed.

[0043] Since the main component of the ceramic heater 1 of the present embodiment is ceramic, when used in a semiconductor manufacturing apparatus, it exhibits excellent durability in a corrosive gas or plasma environment.

[0044] <Second Embodiment> FIG. 7 is an explanatory diagram schematically showing a cross-sectional configuration of a joint portion 30A of the ceramic heater 1A according to the second embodiment. FIG. 8 is an explanatory diagram schematically showing a planar configuration of the joint portion 30A. In FIG. 8, the positive Z-axis direction is the direction toward the front side of the paper surface. The cross-section shown in FIG. 7 corresponds to the B-B cross-section shown in FIG. 8. FIG. 7 corresponds to FIG. 4 of the first embodiment, and FIG. 8 corresponds to FIG. 5. The difference between the ceramic heater 1A of the second embodiment and the ceramic heater 1 of the first embodiment is mainly the configuration of the joint portion 30A. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and the previous description is referred to.

[0045] The line L3 shown in FIGS. 7 and 8 indicates the inner peripheral surface 24 of the shaft 20A, and the line L4 indicates a position 1 mm in the direction along the second main surface 12 of the plate member 10A from the inner peripheral surface 24 of the shaft 20A. That is, the distance D in the direction along the second main surface 12 between the line L3 and the line L4 is 1 mm. As shown in the drawing, the joint portion 30A has voids P3 and P4. The voids P3 and P4 are each a discontinuous substantially annular shape concentric with the shaft 20A (FIG. 8). The void P3 is within a range of 1 mm in the direction along the second main surface 12 from the inner peripheral surface 24 of the shaft 20A (FIG. 7). The void P4 is outside the void P3 and is between the outer peripheral surface 22A of the shaft 20A and the void P3.

[0046] As shown in FIG. 7, in a cross-section including the central axis LO of the shaft 20A, the average thickness within a range of 1 mm in the direction along the second main surface 12 of the plate member 10A from the inner peripheral surface 24 of the shaft 20A in the joint portion 30A is thicker than the average thickness of the remaining portion. That is, in the ceramic heater 1A of the second embodiment, the shapes of the concave portion 16A, the convex portion 26A, and the joint portion 30A are different from those of the ceramic heater 1 of the first embodiment.

[0047] FIG. 9 is an explanatory view of a method for forming the concave portion 16A and the convex portion 26A. The difference between the method for forming the concave portion 16A and the convex portion 26A in the present embodiment and that in the first embodiment lies in the position where pressing is performed (FIG. 9(A)). As shown in FIG. 9(A), a first plate-like member 10p that becomes the plate-like member 10A and a first shaft 20p that becomes the shaft 20A are prepared. The first plate-like member 10p and the first shaft 20p are the same as those in the first embodiment. As will be described later, the end portion of the first flange portion 20fp is deformed to form the shaft 20A. A ceramic adhesive 30p that becomes the joint portion 30A is applied to the end face of the first shaft 20p, and the first shaft 20p is placed on the first plate-like member 10p so that the first flange portion 20fp is placed on the first concave portion 16p of the first plate-like member 10p.

[0048] Then, the first plate-like member 10p and the first shaft 20p are heated to a high temperature (for example, about 1400 to 1700 ° C), and the first flange portion 20fp of the first shaft 20p is pressed to 0.1 MPa to 20 MPa (in the figure, the force F is indicated by a white arrow). Due to heat and pressure, the first plate-like member 10p, the first shaft 20p, and the ceramic adhesive 30p deform with each other to fill the gap, so the joint surface shape is curved. Then, by processing the first main surface 11p of the first plate-like member 10p to be flat, the flat first main surface 11 is formed, and the shape deformed only inside can be left (FIG. 9(B)). The manufacturing method of the ceramic heater 1A in the present embodiment includes the above steps.

[0049] In this way, by manufacturing the ceramic heater 1A in which the plate-like member 10 and the shaft 20 are joined by pressing the first flange portion 20fp of the first shaft 20p, an annular gap P3 interrupted in the range of 1 mm from the inner peripheral surface 24 can be formed at the joint portion 30A. Also, the average thickness in the range of 1 mm from the inner peripheral surface 24 at the joint portion 30A can be made thicker than the average thickness of the remaining portion.

[0050] As described above, in the second embodiment, although the same first plate-like member 10p and the first shaft 20p as in the first embodiment are joined by the ceramic adhesive 30p, since the pressing locations are different, the shapes of the concave portion 16A, the convex portion 26A, and the joint portion 30A are different from those in the first embodiment, and the arrangement of the voids in the joint portion 30A is also different from that in the first embodiment.

[0051] As described above, in the ceramic heater 1A of the present embodiment, in the cross-section including the central axis LO of the shaft 20A, the joint portion 30A has a void P3 within a range of 1 mm in the direction along the second main surface 12 from the inner peripheral surface 24 of the shaft 20A. As the temperature changes during the use of the ceramic heater 1A, stress may occur in the joint portion 30A according to the difference in the coefficient of thermal expansion between the plate-like member 10A and the joint portion 30A, or between the shaft 20A and the joint portion 30A. According to the ceramic heater 1A of the present embodiment, since the joint portion 30A has the voids P3 and P4, the amount of the joint portion 30A is reduced compared to the case where there are no voids, and the stress can be reduced. Also, in the joint portion 30, the void P3 is formed near the inner peripheral surface 24 of the shaft 20A where stress concentration is likely to occur, and the stress at that location can be released. Therefore, the peeling and cracking of the joint portion 30A can be suppressed, and the decrease in airtightness within the shaft 20A can be suppressed.

[0052] The amount of the joint portion joining the plate-like member 10A and the shaft 20A is such that the greater the amount, the greater the stress due to the difference in thermal expansion, and if it is too small, the joinability is not sufficient. In the ceramic heater 1A of the present embodiment, in the cross-section including the central axis LO of the shaft 20A, the average thickness of the joint portion 30A within a range of 1 mm in the direction along the second main surface 12 from the inner peripheral surface 24 of the shaft 20A is made thicker than the average thickness of the remaining portion. That is, by thickening the thickness of the joint portion 30A near the inner peripheral surface 24 of the shaft 20A to improve the joinability and making the other portions thinner to reduce the stress, the decrease in airtightness within the shaft 20A can be suppressed.

[0053] <Third Embodiment> FIG. 10 is an explanatory diagram schematically showing a cross-sectional configuration of the ceramic heater 1B according to the third embodiment. FIG. 10 corresponds to FIG. 2 of the first embodiment. The difference between the ceramic heater 1B of the third embodiment and the ceramic heater 1 of the first embodiment is mainly that the plate-like member 10B includes a convex portion 18 and the shaft 20B includes a concave portion 28.

[0054] As shown in FIG. 10, the plate-like member 10B includes a convex portion 18 that protrudes with respect to the second main surface 12 on the second main surface 12 side. In the present embodiment, the surface of the convex portion 18 (that is, the joint surface S18) is formed in a bowl shape. The joint surface S18 of the convex portion 18 with the concave portion 28 (described later) is inclined with respect to the second main surface 12 as shown in the drawing.

[0055] The shaft 20B faces the convex portion 18 of the plate-like member 10 and has a concave portion 28 that is recessed with respect to the second main surface 12 of the plate-like member 10B. The shape of the concave portion 28 corresponds to the convex portion 18 of the plate-like member 10B. That is, the joint surface S28 of the concave portion 28 with the convex portion 18 is inclined with respect to the second main surface 12 as shown in the drawing. The plate-like member 10B and the shaft 20B are joined by joining the convex portion 18 of the plate-like member 10B and the concave portion 28 of the shaft 20B via a joint portion 30B.

[0056] Even in this way, similar to the ceramic heater 1 of the above embodiment, the joining reliability between the plate-like member 10B and the shaft 20B can be improved.

[0057] <Fourth Embodiment> FIG. 11 is an explanatory diagram schematically showing a cross-sectional configuration of the ceramic heater 1C according to the fourth embodiment. FIG. 11 corresponds to FIG. 2 of the first embodiment. The differences between the ceramic heater 1C of the fourth embodiment and the ceramic heater 1 of the first embodiment are mainly that the shaft 20C does not include a flange portion and the shapes of the concave portion 16C and the convex portion 26C.

[0058] The plate-shaped member 10C of the present embodiment, similar to the plate-shaped member 10 of the first embodiment, includes a concave portion 16C recessed with respect to the second main surface 12 on the second main surface 12 side. In the present embodiment, unlike the first embodiment, the cross-sectional shape of the concave portion 16C is substantially trapezoidal (FIG. 11). The joint surface S16C with the convex portion 26C (described later) of the concave portion 16C is inclined with respect to the second main surface 12, similar to the first embodiment. However, while the joint surface S16 is curved in the first embodiment, the joint surface S16C of the present embodiment is planar (the cross-sectional shape is linear).

[0059] As described above, the shaft 20C of the present embodiment does not have a flange portion. In the present embodiment, at the end of the hollow cylindrical shaft 20C, there is a convex portion 26C that faces the concave portion 16C of the plate-shaped member 10C and protrudes with respect to the second main surface 12 of the plate-shaped member 10C. The shape of the convex portion 26C corresponds to the concave portion 16C of the plate-shaped member 10C. That is, the joint surface S26C of the convex portion 26C with the concave portion 16C is inclined with respect to the second main surface 12 as shown in the figure. The plate-shaped member 10C and the shaft 20C are joined by joining the concave portion 16C of the plate-shaped member 10C and the convex portion 26C of the shaft 20C via a joint portion 30C.

[0060] Even in this way, similar to the ceramic heater 1 of the above embodiment, the joining reliability between the plate-shaped member 10C and the shaft 20C can be improved.

[0061] <Modification Example of the Present Embodiment> The present invention is not limited to the above-described embodiments, and can be implemented in various aspects without departing from the gist thereof. For example, the following modifications are possible.

[0062] · In the above embodiment, an example is shown in which all of the joint surfaces between the convex and concave portions are inclined with respect to the second main surface, respectively. However, a part of the joint surface between the convex and concave portions may be inclined with respect to the second main surface. Even in this way, the alignment between the plate-shaped member and the shaft can be improved.

[0063] ·In the above-described embodiment, an example in which all of the plate-like member, the shaft, and the joint portion are mainly made of ceramic was shown, but the main component of each member is not limited to the above-described embodiment. For example, the plate-like member and the shaft may be formed mainly of a metal such as aluminum. Further, for example, the joint portion 30 may be formed mainly of a high heat-resistant resin. The plate-like member and the shaft may be formed of different materials.

[0064] ·The coefficient of thermal expansion of the material of the plate-like member and the shaft and the material of the joint portion may be the same.

[0065] ·In the above-described embodiment, an example in which the joint portion has voids was shown, but the joint portion may not have voids. However, having voids is preferable because the stress can be reduced and the stress can be released.

[0066] ·The position of the voids in the joint portion is not limited to the above-described embodiment. For example, it may be formed at a position along the outer peripheral surface or the inner peripheral surface of the shaft. Further, it may be formed dispersedly over the entire joint portion.

[0067] ·The shape of the voids in the joint portion is not limited to the above-described embodiment. However, it is preferable that the outer peripheral surface and the inner peripheral surface of the shaft are not connected so that a decrease in airtightness can be suppressed.

[0068] ·The thickness of the joint portion is not limited to the above-described embodiment. For example, it may be a constant thickness over the entire joint portion. Further, the average thickness in the vicinity of the outer peripheral surface and the inner peripheral surface of the shaft may be thicker than the average thickness of the remaining portion.

[0069] ·The method of forming the concave and convex portions respectively provided on the plate-like member and the shaft is not limited to the above-described embodiment. For example, a shaft having a convex portion formed at an end may be overlapped on a flat surface of the plate-like member that does not have a concave portion, and heated and pressurized to form it. Further, a curved plate-like jig may be laid under the plate-like member that does not have concave and convex portions, and the shaft may be pressed (together with heating) to form concave and convex portions. Further, the plate-like member and the shaft on which the concave and convex portions are formed in advance may be joined.

[0070] As described above, the present invention has been described based on the embodiments and modified examples. However, the embodiments of the above-described aspects are for facilitating the understanding of the present invention and do not limit the present invention. The present invention can be changed and improved without departing from the spirit and scope of the claims, and equivalents thereof are included in the present invention. Further, if the technical features are not described as essential in this specification, they can be deleted as appropriate.

Explanation of Reference Numerals

[0071] 1, 1A, 1B, 1C... ceramic heaters 10, 10A, 10B, 10C... plate-like members 10p... first plate-like member 11... first main surface 11p... first main surface 12... second main surface 16, 16A, 16C... concave portions 16p... first concave portion 18... convex portion 20, 20A, 20B, 20C... shafts 20f... flange portion 20fp... first flange portion 20p... first shaft 20t... cylindrical portion 22, 22A, 22f, 22t... outer peripheral surfaces 24... inner peripheral surface 26, 26A, 26C... convex portions 28... concave portion 30, 30A, 30B, 30C... joint portions 30p... ceramic adhesive 40…Power supply terminal 50…Heater LO…Central axis P1, P2, P3, P4…Gap S16, S16C, S18, S26, S26C, S28…Joint surface W…Wafer

Claims

1. A heater with a shaft, comprising a substantially flat plate-like member having a planar first main surface and a planar second main surface which is the back surface of the first main surface, and a substantially cylindrical shaft joined to the second main surface side of the plate-like member via a joint portion. Either the plate-like member or the shaft has a convex portion protruding with respect to the second main surface of the plate-like member, and the other has a concave portion facing the convex portion, and the convex portion and the concave portion are joined. At least a part of each of the joining surfaces of the convex portion and the concave portion is inclined with respect to the second main surface. At least one of the material of the plate-like member and the material of the shaft has a different coefficient of thermal expansion from the material of the joint portion. The joint portion is In a cross-section including the central axis of the shaft, the average thickness within a range of 1 mm in the direction along the second main surface from at least one of the outer peripheral surface and the inner peripheral surface of the shaft is thicker than the average thickness of the remaining portion, which is characterized. Heater with a shaft.

2. The heater with a shaft according to Claim 1, wherein The joint portion is In a cross-section including the central axis of the shaft, it has a gap within a range of 1 mm in the direction along the second main surface from at least one of the outer peripheral surface and the inner peripheral surface of the shaft, which is characterized. Heater with a shaft.

3. The heater with a shaft according to Claim 2, wherein The gap of the joint portion is a discontinuous substantially annular shape concentric with the shaft, which is characterized. Heater with a shaft.

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