Ceramic Heater

Abstract

A highly reliable ceramic heater having multiple heating zones is provided, which can be efficiently manufactured by simultaneously joining multiple terminal wires to multiple connection points while easily ensuring insulation between them. The ceramic heater comprises a ceramic plate in which multiple heater electrodes are embedded, a cylindrical ceramic shaft having an internal space, multiple connection points formed in the region of the ceramic plate facing the internal space and configured to be connectable to each of the multiple heater electrodes, and a multi-terminal integrated structure disposed in the internal space and connected to the multiple connection points, the multi-terminal integrated structure including a fixed plate having a distance of 0 to 50 mm from the ceramic plate, multiple terminal rods fixed and integrated to the fixed plate so as to penetrate the fixed plate in the thickness direction, with one end of each rod brazed to the multiple connection points, and multiple cables, each covered with a heat-resistant insulating material, connected to the other end of the multiple terminal rods.

Description

[Technical field]

[0001] The present invention relates to a ceramic heater, and more particularly to a ceramic heater having multiple heating zones. [Background technology]

[0002] In a film forming apparatus for a semiconductor manufacturing process, a ceramic heater is used as a support stage for uniformly controlling the temperature of a wafer. A widely used ceramic heater includes a ceramic plate on which the wafer is placed and a cylindrical ceramic shaft attached to the ceramic plate.

[0003] Among ceramic heaters having a ceramic shaft, those equipped with a number of terminal rods that pass through the internal space of the ceramic shaft and connect to electrodes in a ceramic plate are known. For example, Patent Document 1 (Japanese Patent No. 6816004) discloses a wafer chuck assembly that includes a pack including an electrically insulating material in which a heater element and a number of electrodes are embedded, a shaft including a number of connectors for the heater element and the electrodes, and a base including an electrically insulating terminal block through which the number of connectors pass. The terminal block serves to align the number of connectors, and is arranged so that the distal ends of each of the connectors are fitted to corresponding sockets in the pack.

[0004] Meanwhile, a ceramic heater with multiple heating zones has been proposed. For example, Patent Document 2 (JP Patent Publication 2022-122675 A) discloses a ceramic heater having an inner circumferential resistance heating element embedded in an inner circumferential region of a ceramic base and an outer circumferential resistance heating element embedded in an outer circumferential region of the ceramic base. An outer circumferential power supply terminal that supplies power to the outer circumferential resistance heating element is provided in the central region of the ceramic base, while a metal mesh jumper that connects the outer circumferential resistance heating element and the outer circumferential power supply terminal is embedded in the ceramic base. The jumper is composed of a mesh electrode obtained by dividing a metal mesh disk on the jumper embedding surface into multiple parts. The inner circumferential region is a circular region concentric with the ceramic base, and the outer circumferential region is an annular region outside the circular region. The outer circumferential resistance heating element is provided in each of the divided regions obtained by dividing the annular region into multiple parts, or one is provided in the annular region. The jumpers are provided so as to form pairs with each of the outer circumferential resistance heating elements. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6816004 [Patent Document 2] Patent Publication No. 2022-122675 Summary of the Invention

[0006] In a ceramic heater having a plurality of heating zones as disclosed in Patent Document 2 (i.e., a multi-zone heater), a plurality of heater electrodes are embedded in a ceramic plate. For this reason, it is required to connect a terminal rod to each of the plurality of heater electrodes. For example, in the case of a ceramic heater 110 having ten heating zones Z1 to Z10 as shown in Figs. 22 and 23, ten pairs of terminal rods 124 (i.e., twenty terminal rods 124) are connected directly or via lead wires 115 to ten heater electrodes 114 corresponding to the respective heating zones in the ceramic plate 112 to enable power supply to the ten zones. In this case, twenty terminal rods 124 are passed through the internal space S of the ceramic shaft 116 to connect to the heater electrode 114. In this way, when a large number of terminal rods 124 passing through the ceramic shaft 116 are connected to the heater electrode 114, the terminal rods 124 must be joined individually to the heater electrode 114 or the lead wire 115, and the joining work becomes extremely cumbersome. In particular, when the number of terminal rods 124 is increased, it is necessary to reduce the diameter of the terminal rods 124 to reduce the cross-sectional area each terminal rod occupies in the ceramic shaft 116, but in that case, the joint strength is reduced due to the reduction in the joint area of ​​the terminal rods 124. Even in this situation, it is necessary to ensure insulation between the terminal rods 124 while arranging the many terminal rods 124 in the ceramic shaft 116, and the structure for insulating the terminal rods 124 from each other becomes complicated. Therefore, a configuration is desired that can efficiently join a large number of terminal wirings (e.g., terminal rods 124) to a large number of connecting portions 118 (corresponding to the large number of heater electrodes 114) while easily ensuring insulation between them.

[0007] The inventors have now discovered that by connecting a specified multi-terminal integrated structure by soldering to a plurality of connection parts corresponding to a plurality of heater electrodes embedded in a ceramic plate, it is possible to simultaneously join a plurality of terminal wirings to a plurality of connection parts while easily ensuring insulation between them.

[0008] Therefore, an object of the present invention is to provide a highly reliable ceramic heater having multiple heating zones that can be efficiently manufactured by simultaneously joining multiple terminal wirings to multiple connection portions while easily ensuring insulation between them.

[0009] According to the present invention, the following aspects are provided. [Aspect 1] a ceramic plate having a first surface for supporting a wafer and a second surface opposite to the first surface, and having a plurality of heater electrodes embedded therein in an arrangement providing a plurality of heating zones; a cylindrical ceramic shaft attached to the second surface of the ceramic plate and having an interior space; a plurality of connection portions formed in an area of ​​the ceramic plate facing the internal space and configured to be connectable to each of the plurality of heater electrodes; a multi-terminal integrated structure disposed in the internal space and connected to the plurality of connection portions; A ceramic heater comprising: The multi-terminal integral structure is a fixing plate disposed in contact with or near the second surface of the ceramic plate and spaced from the second surface by a distance of 0 to 50 mm; a plurality of terminal rods fixed and integrated with the fixing plate so as to penetrate the fixing plate in a thickness direction, and one end of each of the terminal rods being soldered to the connecting portions; a plurality of cables, each covered with a heat-resistant insulating material, connected directly or indirectly to the other ends of the plurality of terminal rods; Including, a ceramic heater. [Aspect 2] Each of the plurality of connection portions is a hole formed in a second surface of the ceramic plate; an exposed portion that is a part of the heater electrode or a part of a lead wire from the heater electrode and is exposed in the hole; and the terminal rod is soldered to the exposed portion. [Aspect 3] 3. The ceramic heater according to claim 2, wherein an end of the terminal rod is inserted into the hole, and a side surface of the end and an inner wall of the hole are also soldered to each other. [Aspect 4] 4. The ceramic heater according to aspect 2 or 3, wherein the depths of the holes are different from one another in all or some of the plurality of connecting portions. [Aspect 5] The ceramic heater according to any one of aspects 1 to 4, wherein the fixing plate is joined to the second surface of the ceramic plate, and / or a side end surface of the fixing plate is joined to an inner wall of the ceramic shaft. [Aspect 6] The ceramic heater according to any one of aspects 1 to 5, wherein the second surface of the ceramic plate has a recess into which at least a portion of the fixing plate can be fitted, and an upper surface and / or a side end surface of the fixing plate are joined to the recess. [Aspect 7] The ceramic heater according to any one of aspects 1 to 6, wherein a gap exists between the second surface of the ceramic plate and the fixed plate. [Aspect 8] The ceramic heater according to any one of aspects 1 to 7, wherein a gap exists between the side end surface of the fixing plate and the inner wall of the ceramic shaft. [Aspect 9] A ceramic heater according to any one of aspects 1 to 7, wherein no gap exists between the side end surface of the fixing plate and the inner wall of the ceramic shaft. [Aspect 10] The ceramic heater according to any one of aspects 1 to 9, wherein a diameter of the terminal rod connected to one of the heater electrodes is different from a diameter of the terminal rod connected to another of the heater electrodes, and / or a number of the terminal rods connected to one of the heater electrodes is different from the number of the terminal rods connected to the other of the heater electrodes, so as to allow different amounts of current depending on the heater electrodes. [Aspect 11] 11. The ceramic heater according to any one of aspects 1 to 10, wherein the fixing plate is disk-shaped or annular. [Aspect 12] A ceramic heater according to any one of aspects 1 to 11, wherein the fixing plate is composed of a set of multiple fixing plate pieces each having a shape obtained by dividing a circular fixing plate, thereby causing the multi-terminal integral structure to be composed of a set of multiple multi-terminal integral structure parts. [Aspect 13] 13. The ceramic heater according to any one of aspects 1 to 12, wherein the cable is curved. [Aspect 14] 14. The ceramic heater according to any one of aspects 1 to 13, wherein the multi-terminal integrated structure further includes a bare metal wire that is not covered with a heat-resistant insulating material and is interposed between the terminal rod and the cable, and the bare metal wire is surrounded by an insulating protective material having a lower thermal conductivity than the metal wire. [Aspect 15] 15. The ceramic heater according to any one of aspects 1 to 14, further comprising a heat insulating member between the ceramic plate and the fixed plate and / or on the side of the fixed plate opposite to the ceramic plate. [Aspect 16] 16. The ceramic heater according to any one of aspects 1 to 15, wherein the cable extends beyond a lower end of the ceramic shaft. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic top view showing one embodiment of a ceramic heater according to the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing the ceramic heater shown in FIG. [Diagram 3] 1A to 1C are schematic cross-sectional views for explaining the production of a ceramic heater using a multi-terminal integrated structure. [Figure 4] FIG. 2 is a schematic cross-sectional view showing an embodiment in which an upper surface of a fixing plate is joined to a ceramic plate. [Diagram 5] FIG. 11 is a schematic cross-sectional view showing another embodiment in which the upper surface of the fixing plate is joined to a ceramic plate. [Figure 6]FIG. 13 is a schematic cross-sectional view showing one embodiment of an arrangement in which a side surface of a fixed plate is joined to a ceramic shaft. [Figure 7] FIG. 13 is a schematic cross-sectional view showing one embodiment of an arrangement in which a side surface of a fixed plate is joined to a ceramic plate. [Figure 8] FIG. 11 is a schematic cross-sectional view showing another embodiment in which the side surface of the fixed plate is joined to the ceramic shaft. [Figure 9] FIG. 2 is a schematic cross-sectional view showing one embodiment of an arrangement in which the upper surface and side surface of a fixed plate are bonded to a ceramic plate and a ceramic shaft, respectively. [Figure 10] FIG. 13 is a schematic cross-sectional view showing one embodiment of an arrangement in which the upper surface and side surfaces of a fixing plate are joined to a ceramic plate. [Figure 11] FIG. 2 is a schematic plan view showing one embodiment of a multi-terminal integrated structure. [Figure 12] FIG. 11 is a schematic plan view showing another embodiment of a multi-terminal integrated structure. [Figure 13] FIG. 2 is a schematic plan view showing one embodiment of a multi-terminal integrated structure divided into linear portions; [Figure 14] 13 is a schematic plan view showing another embodiment of a multi-terminal integrated structure divided linearly. FIG. [Figure 15] 13 is a schematic plan view showing another embodiment of a multi-terminal integrated structure divided linearly. FIG. [Figure 16] FIG. 2 is a schematic plan view showing one embodiment of a multi-terminal integrated structure divided radially. [Figure 17] 13 is a schematic plan view showing another embodiment of a multi-terminal integrated structure divided radially. FIG. [Figure 18] 13 is a schematic plan view showing another embodiment of a multi-terminal integrated structure divided radially. FIG. [Figure 19] FIG. 1 is a schematic cross-sectional view showing one embodiment of a ceramic heater, particularly a multi-terminal integrated structure. [Figure 20] FIG. 11 is a schematic cross-sectional view showing another embodiment of a ceramic heater, particularly a multi-terminal integrated structure. [Figure 21] FIG. 11 is a schematic cross-sectional view showing another embodiment of a ceramic heater, particularly a multi-terminal integrated structure. [Figure 22] FIG. 1 is a schematic top view showing one embodiment of a ceramic heater according to the prior art. [Figure 23] FIG. 23 is a schematic cross-sectional view showing the ceramic heater shown in FIG. 22. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The ceramic heater according to the present invention is a ceramic platform for supporting a wafer in a semiconductor manufacturing device. Typically, the ceramic heater according to the present invention can be a ceramic heater for a semiconductor film forming device. Typical examples of the film forming device include a CVD (chemical vapor deposition) device (e.g., a thermal CVD device, a plasma CVD device, a photo CVD device, and an MOCVD device) and a PVD (physical vapor deposition) device.

[0012] 1 and 2 show one embodiment of a ceramic heater. The ceramic heater 10 shown in FIGS. 1 and 2 includes a ceramic plate 12, a cylindrical ceramic shaft 16, a plurality of connection parts 18, and a multi-terminal integral structure 20. The ceramic plate 12 has a first surface 12a for mounting a wafer (not shown) thereon, and a second surface 12b opposite to the first surface 12a. A plurality of heater electrodes 14 are embedded in the ceramic plate 12 in an arrangement that provides a plurality of heating zones Z1 to Z10. A ceramic shaft 16 is attached to the second surface 12b of the ceramic plate 12. The ceramic shaft 16 is cylindrical, and therefore has an internal space S. A plurality of connection parts 18 are formed in an area of ​​the ceramic plate 12 facing the internal space S, and these connection parts 18 are configured to be connectable to each of the plurality of heater electrodes 14. The multi-terminal integral structure 20 is disposed in the internal space S and is connected to the plurality of connection parts 18. The multi-terminal integrated structure 20 includes a fixed plate 22, a plurality of terminal rods 24, and a plurality of cables 26. The fixed plate 22 is disposed in contact with or in the vicinity of the second surface 12b of the ceramic plate 12. The distance between the fixed plate 22 and the second surface 12b is 0 to 50 mm. The plurality of terminal rods 24 are fixed and integrated with the fixed plate 22 so as to penetrate the fixed plate 22 in the thickness direction, and one end 24a of each of the terminal rods 24 is brazed (using a brazing material 28) to each of the plurality of connection parts 18. The other end 24b of each of the plurality of terminal rods 24 is directly or indirectly connected to a plurality of cables 26, and each of these cables 26 is covered with a heat-resistant insulating material. In this way, by connecting the multi-terminal integrated structure 20 to the plurality of connection parts 18 corresponding to the plurality of heater electrodes 14 embedded in the ceramic plate 12 by brazing, it is possible to simultaneously join a plurality of terminal wirings (for example, the terminal rods 24 and the cables 26) to a plurality of connection parts 18 while easily ensuring insulation therebetween. That is, according to this configuration, it is possible to provide a highly reliable ceramic heater 10 having a plurality of heating zones Z1 to Z10, which can be efficiently manufactured by simultaneously joining a plurality of terminal wirings to a plurality of connection portions 18 while easily ensuring insulation between them.

[0013] That is, as described above, in the conventional ceramic heater 110 having a plurality of heating zones Z1 to Z10 as shown in Figs. 22 and 23, when a large number of terminal rods 124 passing through the ceramic shaft 116 are to be connected to the heater electrode 114, the terminal rods 124 must be joined individually to the heater electrode 114 or the lead wire 115, making the joining operation extremely cumbersome. In particular, when increasing the number of terminal rods 124, it is necessary to reduce the diameter of the terminal rods 124 to reduce the cross-sectional area each terminal rod occupies in the ceramic shaft 116, but in that case, the joining area of ​​the terminal rods 124 is reduced, resulting in a decrease in the joining strength. Even in this situation, it is necessary to ensure insulation between the terminal rods 124 while arranging a large number of terminal rods 124 in the ceramic shaft 116, and the structure for insulating the terminal rods 124 from each other becomes complicated. On the other hand, a structure in which multiple terminal rods are pressed against the connection part from below by a spring or the like can also be considered. However, in an operating environment exceeding 500°C, the spring characteristics deteriorate and the pressing surface changes, making it difficult to maintain the desired performance.

[0014] In contrast, in the manufacture of the ceramic heater 10 of the present invention, as conceptually shown in FIG. 3, a simple method is used in which the multi-terminal integrated structure 20 is disposed in contact with or near the ceramic plate 12 and connected to the multiple connection parts 18 by brazing (using a brazing material 28), and the multiple terminal wires (e.g., terminal rods 24 and cables 26) can be simultaneously joined to the multiple connection parts 18 while easily ensuring insulation between them. That is, the multi-terminal integrated structure 20 has a configuration in which the multiple terminal rods 24 are fixed and integrated to the fixed plate 22, and the cables 26 connected to the ends of the terminal rods 24 are covered with a heat-resistant insulating material, so that the multi-terminal integrated structure 20 itself can sufficiently ensure insulation between the terminal wires in advance. This makes it possible to avoid a complicated operation for ensuring insulation when connecting the terminal rods 24 to the connection parts 18. Furthermore, by using the multi-terminal integrated structure 20, it is not necessary to connect the terminal rods 24 to the connection parts 18 one by one, and the multiple terminal rods 24 can be simultaneously joined to the multiple connection parts 18. Furthermore, even if the bonding area decreases as the number of terminal rods 24 increases, sufficient bonding strength can be ensured throughout the multi-terminal integrated structure 20, eliminating the need for strong solder bonding as was previously required and making it possible to use small-diameter terminals with a diameter of 2.0 mm or less. In this way, the ceramic heater 10 of the present invention has a configuration that allows it to be efficiently manufactured while ensuring sufficient insulation between the terminal wirings and sufficient bonding strength of the terminals, and as a result, the ceramic heater 10 can be provided as a highly reliable multi-zone heater.

[0015] The ceramic plate 12 is a ceramic plate in which a plurality of heater electrodes 14 are embedded in an arrangement that provides a plurality of heating zones Z1 to Z10. The number of heating zones Z is not particularly limited, but is preferably 8 to 150, and more preferably 10 to 50. Such a ceramic plate 12 may have a similar configuration to a ceramic plate employed in a known multi-zone heater (see, for example, Patent Document 2).

[0016] The main portion of the ceramic plate 12 other than the internal electrodes such as the heater electrode 14 and wiring such as the lead wires 15 (i.e., the ceramic base) is preferably made of aluminum nitride from the viewpoints of excellent thermal conductivity, high electrical insulation, and thermal expansion characteristics similar to those of silicon.

[0017] The preferred shape of the ceramic plate 12 is a disk shape. However, the planar shape of the disk-shaped ceramic plate 12 does not need to be a perfect circle, and may be an incomplete circle with a part missing, such as an orientation flat. The size of the ceramic plate 12 may be appropriately determined according to the diameter of the wafer to be used, and is not particularly limited, but when it is a circle, the diameter is typically 150 to 450 mm, for example, about 300 mm.

[0018] The heater electrode 14 is not particularly limited, and may be, for example, a conductive coil wired in a single stroke across the entire surface of the ceramic plate 12. Terminal rods 24 are connected to both ends of the heater electrode 14 for power supply, and the terminal rods 24 are connected to a heater power supply (not shown) via a cable 26 (or a metal wire 34 and a cable 26). When power is supplied from the heater power supply, the heater electrode 14 generates heat and heats the wafer placed on the first surface 12a. The heater electrode 14 is not limited to a coil, and may be, for example, a ribbon (a long, thin plate) or a mesh.

[0019] An internal electrode other than the heater electrode 14 may be embedded in the ceramic plate 12. Examples of such internal electrodes include an ESC electrode and an RF electrode. The ESC electrode is an abbreviation of an electrostatic chuck (ESC) electrode, and is also called an electrostatic electrode. The ESC electrode is preferably a circular thin-layer electrode having a diameter slightly smaller than that of the ceramic plate 12, and may be, for example, a mesh-like electrode formed by weaving thin metal wires into a net shape into a sheet shape. The ESC electrode may be used as a plasma electrode. That is, by applying a high frequency to the ESC electrode, the ESC electrode can also be used as a plasma electrode, and film formation can also be performed by a plasma CVD process. An ESC rod is preferably connected to the ESC electrode for power supply, and the ESC rod is preferably connected to an external power source (not shown) via the internal space S of the ceramic shaft 16. The multi-terminal integrated structure 20 may further include a terminal rod for the ESC rod. When a voltage is applied from an external power source, the ESC electrode chucks a wafer placed on the first surface 12a. The chucking force at this time is set to a value when the volume resistivity of aluminum nitride that may constitute the main part of the ceramic plate 12 is 1×10 8 ~1×10 13 is the Johnsen-Rahbek force because Ωcm.

[0020] The ceramic shaft 16 is a cylindrical shaft attached to the second surface 12b of the ceramic plate 12, and may have the same configuration as a ceramic shaft used in a known ceramic heater. The ceramic shaft 16 has an internal space S for accommodating the terminal rod 24. The ceramic shaft 16 is preferably made of the same ceramic material as the ceramic plate 12. Therefore, the ceramic shaft 16 is preferably made of aluminum nitride. The upper end surface of the ceramic shaft 16 is preferably joined to the second surface 12b of the ceramic plate 12 by solid-state bonding or diffusion bonding. The outer diameter of the ceramic shaft 16 is not particularly limited and is, for example, about 40 mm. The inner diameter of the ceramic shaft 16 (diameter of the internal space S) is also not particularly limited and is, for example, about 36 mm.

[0021] The multiple connection parts 18 are formed in an area facing the internal space S of the ceramic plate 12 and are configured to be connectable to each of the multiple heater electrodes 14. The connection parts 18 are not particularly limited as long as they are configured to allow power to be supplied to the heater electrode 14 by soldering the upper end of the terminal rod 24. Preferably, each of the multiple connection parts 18 has a hole formed in the second surface 12b of the ceramic plate 12, and the terminal rod 24 is soldered to a part of the heater electrode 14 exposed in the hole or a part of the lead wire 15 from the heater electrode 14 (i.e., an exposed part). This hole may include not only a hole formed in the ceramic plate 12 but also a recess of the heater electrode 14 and / or the lead wire 15 formed in communication with the hole. In this case, it is preferable that the end of the terminal rod 24 is inserted into the hole and the side surface of the end is also soldered to the inner wall of the hole, in that strength can be improved by side surface joining.

[0022] The depth of the holes may differ from one another in all or part of the multiple connection portions 18. For example, when the heights of the heater electrodes 14 or the lead wires 15 differ depending on the corresponding heating zones as shown in Fig. 2, the depth of the holes can be formed to match the respective heights, so that the heater electrodes 14 or the lead wires 15 can be appropriately exposed in the holes, and soldering to the connection portions 18 of the terminal rods 24 can be reliably performed.

[0023] The multi-terminal integrated structure 20 is disposed in the internal space S and is connected to the multiple connection portions 18. As shown in Figures 2 and 3, the multi-terminal integrated structure 20 includes a fixed plate 22, multiple terminal rods 24, and multiple cables 26.

[0024] The fixing plate 22 is a plate for fixing and integrating the multiple terminal rods 24 in a mutually insulated state. By fixing and integrating the multiple terminal rods 24 to the fixing plate 22, the strength of the fixing plate 22 can be ensured, and therefore the multi-terminal integrated structure 20 as a whole can ensure high strength that cannot be obtained by the terminal rods 24 alone. The fixing plate 22 is preferably made of a heat-resistant insulating material, and more preferably one with low thermal conductivity. Examples of such heat-resistant insulating materials include heat-resistant resins such as polyether ether ketone (PEEK), and ceramics such as alumina, aluminum nitride, silicon carbide, titania, and zirconia. In particular, a heat-resistant insulating material having a thermal expansion coefficient equal to or about 50% higher than that of the ceramic plate 12 is preferable, and an example of such a material is AlN-Al2O3.

[0025] The fixing plate 22 is disposed in contact with or near the second surface 12b of the ceramic plate 12. The distance between the fixing plate 22 and the second surface 12b is 0 to 50 mm, and preferably 0 to 30 mm. By disposing the fixing plate 22 in contact with or near 12b in this manner, the multiple terminal rods 24 can be easily joined simultaneously to the connection parts 18 by brazing. For example, the extension parts of the terminal rods 24 extending from the fixing plate 22 toward the second surface 12b are short, so that positional deviation due to bending of the terminal rods 24 (which may occur when the extension parts of the terminal rods 24 are long) is less likely to occur, and the work of simultaneously joining the multiple terminal rods 24 to the multiple connection parts 18 is easier.

[0026] The fixing plate 22 is preferably bonded to the ceramic plate 12 and / or the ceramic shaft 16. That is, the fixing of the multi-terminal integrated structure 20 to the ceramic plate 12 can be realized by soldering the terminal rod 24 to the connection portion 18, but in order to fix more firmly and securely, it is preferable to bond the fixing plate 22 to the ceramic plate 12 and / or the ceramic shaft 16 using a bonding means such as an adhesive 30 (e.g., ceramic bond).

[0027] The fixing plate 22 can be bonded to various positions of the ceramic plate 12 and / or the ceramic shaft 16. FIGS. 4 to 10 conceptually show various positional relationships between the fixing plate 22, the ceramic plate 12, and the ceramic shaft 16, with other components (terminal rod 24, cable 26, etc.) omitted. In these figures, the portion indicated as adhesive 30 is the bonded portion, and other portions may not be bonded. As shown in FIGS. 4, 5, 9, and 10, the fixing plate 22 may be bonded to the second surface 12b of the ceramic plate 12 (or a recess 32 provided in the second surface 12b), or as shown in FIGS. 6, 8, and 9, the side end surface of the fixing plate 22 may be bonded to the inner wall of the ceramic shaft 16. Alternatively, as shown in FIGS. 5, 7, and 10, the second surface 12b of the ceramic plate 12 may have a recess 32 into which at least a part of the fixing plate 22 can be fitted, and the upper surface and / or the side end surface of the fixing plate 22 may be bonded to the recess 32.

[0028] 4 and 5 show embodiments in which the upper surface of the fixing plate 22 is joined to the ceramic plate 12 by a joining means such as an adhesive 30. In the embodiment shown in Fig. 4, the fixing plate 22 is joined only to the second surface 12b of the ceramic plate 12 by the adhesive 30. In the embodiment shown in Fig. 5, the fixing plate 22 is joined only to the recess 32 of the ceramic plate 12 by the adhesive 30. In either embodiment, it is sufficient that the fixing plate 22 is joined to the ceramic plate 12 only at its upper surface, and the side end surfaces of the fixing plate 22 do not need to be joined to the ceramic plate 12 and the ceramic shaft 16.

[0029] In the embodiment shown in Figs. 4 and 5, a gap exists between the side end face of the fixing plate 22 and the inner wall of the ceramic shaft 16, and in the embodiment shown in Fig. 5, a gap also exists between the side end face of the fixing plate 22 and the inner wall of the recess 32 of the ceramic plate 12. The presence of a gap in the lateral direction of the fixing plate 22 allows the gap to function as a buffer space for alleviating lateral stress. That is, when members with different thermal expansion coefficients are brought into contact with each other in the lateral direction, these members expand at different rates during operation of the device at high temperatures, resulting in lateral compressive stress at the joint. However, according to this embodiment, the presence of a gap in the lateral direction of the fixing plate 22 makes it possible to prevent members with different thermal expansion coefficients from coming into contact with each other in the lateral direction, thereby preventing the generation of such lateral compressive stress. Even if members with different expansion coefficients come into contact with each other in the lateral direction, the stress is absorbed or alleviated by the gap as a buffer space, so that the lateral compressive stress can be reduced.

[0030] 6 to 8 show an embodiment in which the side end surface of the fixing plate 22 is joined to the ceramic shaft 16 or the ceramic plate 12 by a joining means such as an adhesive 30. In the embodiment shown in FIG. 6, the fixing plate 22 is joined only to the inner wall of the ceramic shaft 16 by the adhesive 30. In the embodiment shown in FIG. 7, the side end surface of the fixing plate 22 is joined only to a recess 32 provided in the second surface 12b of the ceramic plate 12 by the adhesive 30. In either embodiment, the fixing plate 22 only needs to be joined to the ceramic shaft 16 or the ceramic plate 12 at its side end surface, and the upper surface of the fixing plate 22 does not need to be joined to the ceramic plate 12 and the ceramic shaft 16. Therefore, as in the embodiment shown in FIG. 8, the side end surface of the fixing plate 22 may be joined to the ceramic shaft 16 with a gap provided between the ceramic plate 12 and the fixing plate 22. In this embodiment, a cutout portion may be provided in the ceramic shaft 16, and the side end portion of the fixing plate 22 may be supported by this cutout portion.

[0031] 6 to 8, a gap can be provided between the fixing plate 22 and the ceramic shaft 16, or between the side end face of the fixing plate 22 and the inner wall of the recess 32 of the ceramic plate 12. That is, by only partially bonding the fixing plate 22 and the ceramic shaft 16 with the adhesive 30, a gap can be provided at the non-bonded portion between the fixing plate 22 and the ceramic shaft 16. Similarly, by only partially bonding the side end face of the fixing plate 22 and the inner wall of the recess 32 with the adhesive 30, a gap can be provided at the non-bonded portion between the side end face of the fixing plate 22 and the inner wall of the recess 32. Then, such a gap can be made to function as a buffer space for mitigating lateral stress as described above. That is, by providing a gap between the fixing plate 22 and the ceramic shaft 16 and / or the recess 32, it is possible to prevent members having different thermal expansion coefficients from expanding in the lateral direction and coming into contact with each other during operation of the device at high temperatures, and to prevent such lateral compressive stress from occurring. Furthermore, even if members having different expansion coefficients come into contact with each other in the lateral direction, the stress is absorbed or alleviated in the gap acting as the buffer space, so that the compressive stress in the lateral direction can be reduced.

[0032] In addition, when a gap is provided between the ceramic plate 12 and the fixed plate 22 as shown in FIG. 8, the gap can function as an insulating space, and the thermal insulation of the multi-terminal integrated structure 20 can be improved. Furthermore, the improved thermal insulation can adjust the amount of expansion and contraction of members with different expansion coefficients, and the horizontal stress can be reduced. That is, even if the thermal expansion coefficient of the fixed plate 22 is larger than that of the ceramic plate 12, the temperature of the fixed plate 22 can be lowered due to the improved thermal insulation, and the stress due to the difference in the thermal expansion coefficients of both members can be reduced. Furthermore, the gap can also function as a buffer space for alleviating vertical stress. That is, by providing a gap between the fixed plate 22 and the ceramic plate 12, it is possible to prevent members with different thermal expansion coefficients from expanding and contacting each other in the vertical direction during operation of the device at high temperatures, and to prevent such vertical compressive stress from occurring. Furthermore, even if members with different expansion coefficients come into contact in the vertical direction, the stress is absorbed or alleviated by the gap as a buffer space, and the vertical compressive stress can be reduced.

[0033] 9 and 10 show an embodiment in which the upper surface and side end surfaces of the fixing plate 22 are bonded to the ceramic shaft 16 or the ceramic plate 12. In the embodiment shown in FIG. 9, the upper surface and side end surfaces of the fixing plate 22 are bonded to the second surface 12b of the ceramic plate 12 and the inner wall of the ceramic shaft 16, respectively, by a bonding means such as an adhesive 30. In the embodiment shown in FIG. 10, the upper surface and side end surfaces of the fixing plate 22 are bonded to the recess 32 of the ceramic plate 12 by the adhesive 30. It is not necessary for the entire upper surface and side end surfaces of the fixing plate 22 to be bonded to the ceramic plate 12 or the ceramic shaft 16, and there may be some parts that are not bonded. In the embodiment shown in FIG. 9 and 10, bonding can be performed over a wider area, so that the adhesive strength can be improved. In addition, the diameter of the terminal rod 24 can be further reduced accordingly.

[0034] As described above, a gap may exist between the second surface 12b of the ceramic plate 12 and the fixed plate 22 (see FIG. 8). Also, a gap may exist between the side end surface of the fixed plate 22 and the inner wall of the ceramic shaft 16 (see FIGS. 4, 5, 7, and 10), or no gap may exist between the side end surface of the fixed plate 22 and the inner wall of the ceramic shaft 16 (see FIGS. 6, 8, and 9). The advantages of each aspect are as described above.

[0035] The fixing plate 22 or the multi-terminal integrated structure 20 is not particularly limited in shape as long as it can be accommodated in the internal space S of the ceramic shaft 16, but it is preferable that the fixing plate 22 or the multi-terminal integrated structure 20 is disk-shaped as shown in Fig. 11 or annular as shown in Fig. 12. These shapes are suitable for the cylindrical ceramic shaft 16, and the internal space S of the ceramic shaft 16 can be efficiently utilized to fix many terminal rods 24.

[0036] In another preferred embodiment of the present invention, the fixing plate 22 may be configured as a set of a plurality of fixing plate pieces 22a each having a shape obtained by dividing the disk-shaped fixing plate 22 as shown in Figs. 13 to 18, and the multi-terminal integral structure 20 may be configured as a set of a plurality of multi-terminal integral structure parts 20a. According to this embodiment, the terminal joining operation of the multi-terminal integral structure 20 can be performed by dividing each of the divided multi-terminal integral structure parts 20a, so that the terminal joining operation can be simplified. In this case, the fixing plate 22 and the multi-terminal integral structure 20 may be linearly divided into two equal parts as shown in Fig. 13, or may be linearly divided at an arbitrary position (not limited to being divided into two equal parts) as shown in Fig. 14. Also, as shown in Fig. 15, the fixing plate 22 and the multi-terminal integral structure 20 may be linearly divided into three or more parts at an arbitrary position. Alternatively, the fixing plate 22 and the multi-terminal integral structure 20 may be radially divided into four equal parts as shown in Fig. 16, or may be radially divided at an arbitrary ratio as shown in Figs. 17 and 18. The number of fixing plate pieces 22a constituting the fixing plate 22 (ie, the number of multi-terminal integrated structure parts 20a constituting the multi-terminal integrated structure 20) is not particularly limited, but is preferably 2-8, and more preferably 2-4.

[0037] The terminal rods 24 are fixed and integrated with the fixed plate 22 so as to penetrate the fixed plate 22 in the thickness direction. One end of each of the terminal rods 24 is soldered to each of the connection parts 18, while the other end of each of the terminal rods 24 is directly or indirectly connected to a cable 26 (described later) and can be connected to a heater power source (not shown) via the cable 26 (or the metal wire 34 and the cable 26). With this configuration, a power supply path to the heater electrode 14 is secured. The terminal rods 24 are not particularly limited as long as they are conductive members, and may be made of metals such as molybdenum and nickel, but are preferably made of molybdenum in terms of thermal expansion coefficient. The diameter of the terminal rods 24 is not particularly limited, but is preferably 0.5 to 5 mm, and more preferably 1 to 3 mm. Within these ranges, the joint strength between the terminal rods 24 and the connection parts 18 can be sufficiently secured even when the number of the terminal rods 24 is increased. The number of terminal rods 24 is not particularly limited, but is preferably 16 to 300, and more preferably 20 to 100, from the viewpoint of use as a multi-zone heater.

[0038] In order to allow different amounts of current depending on the heater electrodes 14, the diameter of the terminal rod 24 connected to one of the heater electrodes 14 may be different from the diameter of the terminal rod 24 connected to the other heater electrodes 14. In addition, in order to allow different amounts of current depending on the heater electrodes 14, the number of terminal rods 24 connected to one of the heater electrodes 14 may be different from the number of terminal rods 24 connected to the other heater electrodes 14. Since the ceramic heater 10 of the present invention is provided with a plurality of heating zones Z1 to Z10, the amount of current to be supplied to the heater electrodes 14 can be changed depending on the heating zone, thereby providing a desirable heater function as a multi-zone heater. For example, the heater electrodes 14 corresponding to the heating zones Z1 to Z10 may include a main heater electrode and a sub-heater electrode, and a larger current may be supplied to the main heater electrode than to the sub-heater electrode.

[0039] As described above, the multiple cables 26 are connected directly or indirectly (through other members such as metal wires 34 described later) to the other ends of the multiple terminal rods 24. Each of the cables 26 is covered with a heat-resistant insulating material. This ensures that the terminal wires are insulated from each other, facilitating assembly of the ceramic heater 10 (particularly, connection to the connection portion 18 of the multi-terminal integrated structure 20). In addition, the cable 26 covered with a heat-resistant insulating material has heat resistance (e.g., the ability to withstand a high temperature of 500°C) that can withstand being placed near the ceramic plate 12 that is heated to a high temperature (e.g., 600°C or higher). Examples of heat-resistant insulating materials used to cover the cable 26 include silica glass, mica, and high heat-resistant resins (e.g., polytetrafluoroethylene (PTFE)). The core portion of the cable 26 other than the covered portion is preferably a metal wire. The metal wire is not particularly limited as long as it is a conductive member, and may be any metal that is generally used as a cable material. The cable 26 may be a metal wire covered with an insulating tube made of a heat-resistant insulating material.

[0040] Incidentally, the ceramic heater 10 of the present invention, by including the multi-terminal integral structure 20, can desirably control the heat dissipation and heat insulation in the ceramic shaft 16. That is, from the viewpoint of fully exerting the heating function of the heater electrode 14, it is desirable not to cool the fixed plate 22 and the terminal rod 24 extending from it toward the connection part 18, whereas it is desirable to cool the cable 26 arranged below the fixed plate 22 from the viewpoint of protecting the device components. In this way, it is preferable that the multi-terminal integral structure 20 is configured so that the heat dissipation and heat insulation in the ceramic shaft 16 can be desirably controlled. Various preferable embodiments suitable for such heat dissipation and heat insulation are shown in Figures 19 to 21.

[0041] According to a preferred embodiment of the present invention, the cable 26 is curved as shown in Fig. 19 (and Fig. 2). By curving the cable 26 inside the ceramic shaft 16, the length of the cable 26 can be made longer than the length of the ceramic shaft 16. As a result, the surface area of ​​the cable 26 inside the ceramic shaft 16 is increased, and heat dissipation into the ceramic shaft 16 can be promoted. In this way, heat conduction to the device component 40 located at the lower end or below of the ceramic shaft 16 can be suppressed, and the risk of damage to the device component 40 due to thermal deterioration can be reduced.

[0042] According to another preferred embodiment of the present invention, as shown in FIG. 20, the multi-terminal integrated structure 20 further includes a bare metal wire 34 that is not covered with a heat-resistant insulating material and is interposed between the terminal rod 24 and the cable 26. The bare metal wire 34 is surrounded by an insulating protective material 36 that has a lower thermal conductivity than the metal wire 34. In this way, by providing the bare metal wire 34 and the insulating protective material 36 in the internal space S of the ceramic shaft 16, heat dissipation from the bare metal wire 34 to the internal space S of the ceramic shaft 16 can be promoted. That is, the metal wire 34 with high thermal conductivity is exposed, which promotes heat dissipation, while the metal wire 34 is surrounded by the insulating protective material 36, which ensures insulation between the metal wires 34. According to this embodiment, it is possible to suppress heat conduction to the device components located at the lower end or below of the ceramic shaft 16, and to reduce the risk of damage to the device components 40 due to thermal deterioration. From the viewpoint of promoting heat dissipation, it is preferable that the thermal conductivity of the metal wire 34 is higher than that of the insulating protective material 36. The metal wire 34 is not particularly limited as long as it is a conductive member, and may be a metal that is generally used as a cable material. The insulating protective material 36 is not particularly limited as long as it is a material that can insulate the metal wires 34 from each other, and preferred examples include aluminum nitride and alumina. From the viewpoint of promoting heat dissipation of the metal wire 34, it is preferable that the insulating protective material 36 is configured in a tubular shape so as to provide a space for heat dissipation around the metal wire 34.

[0043] According to yet another preferred embodiment of the present invention, as shown in FIG. 21, a heat insulating member 38 may be further provided between the ceramic plate 12 and the fixed plate 22 and / or on the side of the fixed plate 22 opposite to the ceramic plate 12. That is, in FIG. 21, the heat insulating member 38 is provided between the ceramic plate 12 and the fixed plate 22, but the heat insulating member 38 may be provided on the side of the fixed plate 22 opposite to the ceramic plate 12 as depicted by the dotted line in the figure. In this case, it is preferable that the heat insulating member 38 is provided at or near the lower end of the terminal rod 24 extending downward from the fixed plate 22 (for example, so that the lower end of the terminal rod 24 is hidden). Alternatively, the heat insulating member 38 may be provided on both sides of the fixed plate 22. By providing the heat insulating member 38 on the upper side, lower side, or both sides of the fixed plate 22, the heat conduction from the fixed plate 22 downward can be suppressed. According to this embodiment, by suppressing the heat conduction to the cable 26, the heat conduction to the device component 40 located at the lower end or below of the ceramic shaft 16 can be suppressed, and the risk of damage to the device component 40 due to thermal deterioration can be reduced. The heat insulating member 38 may be previously bonded to the terminal rod 24, in which case it becomes easier to assemble the heat insulating member 38 and the terminal rod 24. The heat insulating member 38 is not particularly limited as long as it is a plate-like member having heat resistance, heat insulation, and electrical insulation properties, but preferred examples include zirconia or alumina.

[0044] 19 to 21, it is preferable that the cable 26 extends beyond the lower end of the ceramic shaft 16. This can further enhance the heat dissipation effect of the cable 26 located below the fixing plate 22, and can more effectively reduce the risk of damage to the device components 40 due to thermal deterioration.

[0045] 19 to 21, it is possible to cool the cable 26 arranged below the fixing plate 22 while avoiding cooling the fixing plate 22 and the terminal rod 24 extending therefrom toward the connection portion 18. However, in order to be able to handle even higher temperatures, a cooling means for cooling the multi-terminal integrated structure 20 or the fixing plate 22 may be provided in the ceramic shaft 16.

Claims

1. a ceramic plate having a first surface for supporting a wafer and a second surface opposite to the first surface, and having a plurality of heater electrodes embedded therein in an arrangement providing a plurality of heating zones; a cylindrical ceramic shaft attached to the second surface of the ceramic plate and having an interior space; a plurality of connection portions formed in an area of ​​the ceramic plate facing the internal space and configured to be connectable to each of the plurality of heater electrodes; a multi-terminal integrated structure disposed in the internal space and connected to the plurality of connection portions; A ceramic heater comprising: The multi-terminal integral structure is a fixing plate disposed in contact with or adjacent to the second surface of the ceramic plate and spaced from the second surface by a distance of 0 to 50 mm; a plurality of terminal rods fixed and integrated with the fixing plate so as to penetrate the fixing plate in a thickness direction, and one end of each of the terminal rods being soldered to the connecting portions; a plurality of cables, each covered with a heat-resistant insulating material, connected directly or indirectly to the other ends of the plurality of terminal rods; Including, Each of the plurality of connection portions is a hole formed in a second surface of the ceramic plate; an exposed portion that is a part of the heater electrode or a part of a lead wire from the heater electrode and is exposed in the hole; The terminal rod is soldered to the exposed portion, an end of the terminal rod is inserted into the hole, and a side surface of the end is soldered to an inner wall of the hole;

2. The ceramic heater according to claim 1 , wherein the depths of the holes are different from one another in all or some of the plurality of connecting portions.

3. 3. The ceramic heater according to claim 1, wherein the fixing plate is bonded to the second surface of the ceramic plate, and / or a side end surface of the fixing plate is bonded to an inner wall of the ceramic shaft.

4. 3. The ceramic heater according to claim 1, wherein the second surface of the ceramic plate has a recess into which at least a portion of the fixing plate can be fitted, and an upper surface and / or a side end surface of the fixing plate are joined to the recess.

5. The ceramic heater according to any one of claims 1 to 3, wherein a gap exists between the second surface of the ceramic plate and the fixed plate.

6. 3. The ceramic heater according to claim 1, wherein a gap exists between a side end surface of the fixing plate and an inner wall of the ceramic shaft.

7. 3. The ceramic heater according to claim 1, wherein no gap exists between a side end surface of said fixing plate and an inner wall of said ceramic shaft.

8. 3. The ceramic heater of claim 1, wherein a diameter of the terminal rod connected to one of the heater electrodes is different from a diameter of the terminal rod connected to another of the heater electrodes, and / or a number of the terminal rods connected to one of the heater electrodes is different from a number of the terminal rods connected to the other of the heater electrodes, so as to allow different amounts of current depending on the heater electrodes.

9. 3. The ceramic heater according to claim 1, wherein the fixing plate is in the shape of a disk or annular ring.

10. 3. The ceramic heater according to claim 1 or 2, wherein the fixing plate is composed of a set of multiple fixing plate pieces each having a shape obtained by dividing a circular fixing plate, whereby the multi-terminal integral structure is composed of a set of multiple multi-terminal integral structure parts.

11. The ceramic heater according to claim 1 or 2, wherein the cable is curved.

12. 3. The ceramic heater according to claim 1, wherein the multi-terminal integral structure further comprises a bare metal wire that is not covered with a heat-resistant insulating material and is interposed between the terminal rod and the cable, and the bare metal wire is surrounded by an insulating protective material having a lower thermal conductivity than the metal wire.

13. 3. The ceramic heater according to claim 1, further comprising a heat insulating member between said ceramic plate and said fixed plate and / or on a side of said fixed plate opposite to said ceramic plate.

14. 3. The ceramic heater of claim 1 or 2, wherein the cable extends beyond a lower end of the ceramic shaft.

Images