Ceramic susceptor and method of manufacturing same

Abstract

Provided is a ceramic susceptor in which a terminal rod has been brazed with high joint strength, and in which the risk of cracking or breakage is reduced. This ceramic susceptor is provided with a ceramic plate having a first surface and a second surface, an internal electrode embedded into the plate, a bulk electrode embedded in the plate so as to connect to the internal electrode, a terminal hole provided so as to reach from the second surface of the plate to the bulk electrode, a metal-containing member embedded in the periphery of the terminal hole in the plate, and a terminal rod that is inserted into the terminal hole and has one end connected to the internal electrode via the bulk electrode. The bulk electrode is exposed at the bottom of the terminal hole, and a metal constituting the metal-containing member is exposed at a side surface of the terminal hole or the like. The terminal rod is brazed to the exposed portion of the bulk electrode, and the terminal rod is brazed to the exposed metal portion of the metal-containing member. Between brazed parts formed at the exposed metal portion, there is an unjoined part at which no brazing with the terminal rod has been formed.

Description

Ceramic susceptor and manufacturing method thereof

[0001] The present disclosure relates to a ceramic susceptor and a method for manufacturing the same.

[0002] Susceptors are used to support wafers in film deposition and etching equipment used in semiconductor manufacturing processes. A widely used susceptor includes a ceramic plate on which the wafer is placed and a cylindrical ceramic shaft attached to the ceramic plate. The ceramic plate typically has a ceramic base made of aluminum nitride (AlN) or other material with excellent heat and corrosion resistance, with internal electrodes embedded therein, such as heater electrodes, RF electrodes, and electrostatic chuck (ESC) electrodes. A terminal rod is connected to the internal electrode, which then passes through the ceramic shaft and is connected to an external electrode.

[0003] In a shaft-equipped ceramic susceptor, soldering is generally used to connect a terminal rod to an internal electrode embedded in a ceramic plate. A typical terminal joining structure is shown in Figure 5. As shown in Figure 5, in this typical terminal joining structure, the end face of a terminal rod 122 inserted into a terminal hole 118 is soldered to a connecting member 116 connected to an internal electrode 114 embedded in a ceramic plate 112, thereby connecting the terminal rod 122 and the internal electrode 114 via the connecting member 116 at a solder joint B.

[0004] Patent Document 1 (JP 2022-111734 A) discloses a wafer mounting table including a first ceramic base, a second ceramic base, a metal bonding layer bonding the first ceramic base and the second ceramic base, a connecting member embedded in the second ceramic base with its upper base in contact with the metal bonding layer, and a power supply terminal electrically connected to the lower base of the connecting member, wherein the connecting member has a portion whose cross-sectional area increases from the upper base side toward the lower base side when the connecting member is cut along a plane parallel to the upper base.

[0005] Japanese Patent Application Laid-Open No. 2022-111734

[0006] In order to improve the bonding strength between the internal electrode and the terminal rod in a ceramic susceptor, it is possible to form a brazing joint B that extends not only to the bottom surface of the terminal hole 118 but also to its side surface, as shown in FIG. 6 . To enable brazing that extends to the side surface of the terminal hole 118, it is desirable to enlarge the embedded metal connecting member 116 as shown in FIG. 6 to form a large-diameter electrode, thereby exposing the connecting member 116 to the side surface of the terminal hole 118. This is because brazing is a method of chemically bonding metals and is not suitable for bonding metals to ceramics. However, in this case, there is a risk of cracking due to residual stress generated during susceptor manufacturing (especially during ceramic firing). Furthermore, even if cracking does not occur, if the side surface of the terminal hole is firmly brazed, there is a risk of damage due to stress generated by differences in thermal expansion during use in semiconductor manufacturing processes (e.g., involving temperature fluctuations between room temperature and 600°C). As a result, in many cases, brazing is performed only on the bottom surface of the terminal hole to the terminal rod. However, it is difficult to achieve high bonding strength with bottom bonding alone, and an improvement in the terminal bonding structure is desired.

[0007] The inventors have now discovered that by not only soldering the bottom surface of the terminal rod to the bulk electrode placed at the bottom of the terminal hole, but also soldering the side surface of the terminal rod in a manner that leaves an unjoined portion at the exposed metal portion of the metal-containing member placed on the side surface of the terminal hole, it is possible to solder the terminal rod with high joint strength while reducing the risk of cracking or breakage.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide or manufacture a ceramic susceptor to which a terminal rod is brazed with high bonding strength while reducing the risk of cracking or breakage.

[0009] According to the present disclosure, the following aspects are provided: [Aspect 1] A ceramic susceptor comprising: a ceramic plate having a first surface on which a wafer is placed and a second surface opposite to the first surface, an internal electrode embedded in the ceramic plate, a bulk electrode embedded in the ceramic plate and connected to the internal electrode, a terminal hole provided from the second surface of the ceramic plate to reach the bulk electrode, a metal-containing member embedded in the ceramic plate around the terminal hole, and a terminal rod inserted in the terminal hole, one end of which is connected to the internal electrode via the bulk electrode and the other end of which extends from the second surface to the outside of the ceramic plate, wherein the bulk electrode is exposed at a bottom of the terminal hole, and a metal constituting the metal-containing member is exposed at a side surface of the terminal hole or at a side and bottom surface of the terminal hole, A ceramic susceptor, wherein the terminal rod is brazed to the exposed portion of the bulk electrode and the terminal rod is brazed to the exposed metal portion of the metal-containing member, and an unjoined portion where no brazing to the terminal rod is formed exists between the brazed joints formed on the exposed metal portions. [Aspect 2] The ceramic susceptor according to Aspect 1, wherein the unjoined portion functions as a stress buffer layer. [Aspect 3] The ceramic susceptor according to Aspect 1 or 2, wherein the metal-containing member comprises at least one material selected from the group consisting of a porous metal member and a metal-ceramic composite material. [Aspect 4] The ceramic susceptor according to any one of Aspects 1 to 3, wherein the metal-containing member comprises a porous metal member. [Aspect 5] The method according to Aspect 4, wherein the porous metal member is a cylindrical porous metal member composed of a stack of multiple porous sheet materials having circular openings, or one or more porous sheet materials wound into a cylindrical shape. [Aspect 6] The ceramic susceptor according to Aspect 5, wherein the porous sheet material is at least one material selected from the group consisting of a metal mesh, a punched metal, and an expanded metal. [Aspect 7] The bulk electrode and the metal constituting the metal-containing member each have a melting point of 5.0 × 10 in the range from room temperature to 800°C. －６ ~9.0 x 10 －６The ceramic susceptor according to any one of Aspects 1 to 6, wherein the bulk electrode and the metal-containing member each comprise at least one selected from the group consisting of Mo, W, and Nb. [Aspect 8] The ceramic susceptor according to any one of Aspects 1 to 7, wherein a side surface of the terminal hole includes a conductive region where the metal-containing member is exposed, and a proportion of an area of ​​the conductive region where the metal constituting the metal-containing member is exposed is 30 to 80%. [Aspect 10] A method for manufacturing a ceramic susceptor, comprising the steps of: arranging an internal electrode on a ceramic powder compact; arranging a bulk electrode on the internal electrode; arranging a metal-containing member on the bulk electrode; burying the internal electrode, the bulk electrode, and the metal-containing member arranged on the ceramic powder compact with ceramic powder to form an electrode-embedded body; press-molding the electrode-embedded body to form an electrode-embedded press-molded body; sintering the electrode-embedded press-molded body to form an electrode-embedded ceramic sintered plate; and forming a terminal hole in the electrode-embedded ceramic sintered plate, exposing the bulk electrode at the bottom of the terminal hole and exposing metal constituting the metal-containing member on a side surface of the terminal hole or on the side and bottom surfaces of the terminal hole. A method for manufacturing a ceramic susceptor, comprising the steps of: inserting a terminal rod into the terminal hole to braze the terminal rod to the exposed portion of the bulk electrode and brazing the terminal rod to the exposed metal portion of the metal-containing member, wherein an unjoined portion not brazed to the terminal rod is formed between the brazed joints applied to the exposed metal portions. [Aspect 11] The method according to Aspect 10, wherein the metal-containing member comprises at least one material selected from the group consisting of a porous metal member and a metal-ceramic composite material. [Aspect 12] The method according to Aspect 10 or 11, wherein the metal-containing member comprises a porous metal member. [Aspect 13] The method according to Aspect 12, wherein the porous metal member is a stack of multiple porous sheet materials having circular openings, or a cylindrical porous metal member composed of one or more porous sheet materials wound into a cylindrical shape.[Aspect 14] The method according to Aspect 13, wherein the ceramic powder is also filled into the hollow portion of the cylindrical porous metal member in the step of embedding the internal electrode, the bulk electrode, and the porous metal member with the ceramic powder. [Aspect 15] The method according to Aspect 12, wherein the porous metal member is a laminate of a plurality of porous sheet materials. [Aspect 16] The method according to any one of Aspects 13 to 15, wherein the porous sheet material is at least one selected from the group consisting of a metal mesh, a punched metal, and an expanded metal.

[0010] Fig. 1 is a schematic cross-sectional view showing an example of a terminal bonding structure in a ceramic susceptor according to the present invention. Fig. 2 is a schematic perspective view showing an example of a metal-containing member shown in Fig. 1. Fig. 3 is a schematic top view showing steps (a) to (d) for manufacturing the terminal bonding structure shown in Fig. 1. Fig. 4 is a schematic cross-sectional view of the cross-sectional structure in step (c) shown in Fig. 3 together with the exposed portion inside the hole. Fig. 5 is a schematic cross-sectional view showing a general terminal bonding structure according to the prior art. Fig. 6 is a schematic cross-sectional view showing another terminal bonding structure according to the prior art.

[0011] Ceramic Susceptor The ceramic susceptor according to the present invention is a ceramic platform for supporting a wafer in a semiconductor manufacturing apparatus. For example, the ceramic susceptor according to the present invention may be a ceramic heater for a semiconductor film formation apparatus or an electrostatic chuck for a semiconductor etching apparatus. Typical examples of film formation apparatuses include CVD (chemical vapor deposition) apparatuses (e.g., thermal CVD apparatuses, plasma CVD apparatuses, photo CVD apparatuses, and MOCVD apparatuses) and PVD (physical vapor deposition) apparatuses.

[0012] FIG. 1 shows one embodiment of a ceramic susceptor according to the present invention. Note that FIG. 1 illustrates an enlarged terminal bonding structure for ease of understanding the present invention. The ceramic susceptor 10 shown in FIG. 1 includes a ceramic plate 12, an internal electrode 14, a bulk electrode 16, a terminal hole 18, a metal-containing member 20, and a terminal rod 22. The ceramic plate 12 has a first surface 12a on which a wafer (not shown) is mounted and a second surface 12b opposite the first surface 12a. The internal electrode 14 is embedded within the ceramic plate 12. The bulk electrode 16 is embedded within the ceramic plate 12 and connected to the internal electrode 14. The terminal hole 18 is provided from the second surface 12b of the ceramic plate 12 to reach the bulk electrode 16. The metal-containing member 20 is embedded within the ceramic plate 12 around the terminal hole 18. A terminal rod 22 is inserted into the terminal hole 18. One end of the terminal rod 22 is connected to the internal electrode 14 via the bulk electrode 16, and the other end of the terminal rod 22 extends from the second surface 12b to the outside of the ceramic plate 12. The bulk electrode 16 is exposed at the bottom of the terminal hole 18, and the metal constituting the metal-containing member 20 is exposed on the side surface of the terminal hole 18 or on the side and bottom surfaces of the terminal hole 18. Note that, in this specification, "exposed" on the side surface or bottom surface of the terminal hole 18 means constituting a part of the side surface or bottom surface of the terminal hole 18, regardless of whether the terminal rod 22 is brazed to the exposed portion (i.e., even if the exposed portion is brazed to the terminal hole 18, the exposed portion is considered to be an exposed portion of the terminal hole 18 itself). The terminal rod 22 is brazed to the exposed portion of the bulk electrode 16. The terminal rod 22 is brazed to the exposed metal portion of the metal-containing member 20, and unjoined portions U, where no brazed joint to the terminal rod 22 is formed, exist between the brazed joints B formed on the exposed metal portions. In this way, not only is the bottom surface of the terminal rod 22 soldered to the bulk electrode 16 placed at the bottom of the terminal hole 18, but the side of the terminal rod 22 is also soldered to the exposed metal portion of the metal-containing member 20 placed on the side of the terminal hole 18, leaving an unjoined portion U, thereby making it possible to solder the terminal rod with high joint strength while reducing the risk of cracking or breakage.That is, it is possible to provide a ceramic susceptor 10 in which the terminal rods are brazed with high bonding strength while reducing the risk of cracking or breakage.

[0013] As mentioned above, to improve the bond strength between the internal electrode and the terminal rod, it is conceivable to enlarge the embedded metal connection member 116 as shown in FIG. 6 to form a large-diameter electrode, thereby exposing the connection member 116 to the side of the terminal hole 118. However, in this case, there is a risk of cracking due to residual stress generated during susceptor manufacturing (especially during ceramic firing). Even if cracking does not occur, if the side of the terminal hole is firmly soldered, there is a risk of damage due to stress generated by thermal expansion differences during use in semiconductor manufacturing processes (e.g., involving temperature fluctuations between room temperature and 600°C). For example, when soldering the side of the terminal hole, cracks can occur due to the thermal expansion differences between the metal terminal and the ceramic as the temperature increases or decreases during soldering (e.g., between room temperature and 800°C). Furthermore, large-diameter electrodes experience increased stress due to the thermal expansion differences between the large-diameter electrode and the ceramic as the temperature increases or decreases during ceramic firing (e.g., between room temperature and 1800°C), which can lead to cracking or damage. These problems are successfully solved by the present invention. Specifically, the bottom surface of the terminal rod 22 is brazed to the bulk electrode 16 located at the bottom of the terminal hole 18. In addition, a metal-containing member 20 is placed around the periphery of the terminal hole 18, the metal constituting the metal-containing member 20 is exposed on the side surface of the terminal hole 18, and the side surface of the terminal rod 22 is brazed to this exposed metal portion, leaving an unbonded portion U. By brazing the terminal rod 22 to the terminal hole 18 and its constituent members not only on the bottom surface but also on the side surface, a sufficient bonding area is ensured, thereby ensuring high bonding strength for the terminal rod 22.

[0014] Even so, the side of the terminal hole 18 is brazed to the side of the terminal rod 22, leaving an unjoined portion U at the exposed metal portion of the metal-containing member 20. The unjoined portion U is a portion where a brazing bond, which chemically bonds metals, is not established. In other words, brazing is a technique for chemically bonding metals using a brazing material. Therefore, while a brazing bond (chemical bond) is established between the exposed metal portion and the metal terminal rod 22, a brazing bond is not established between the exposed ceramic portion and the metal terminal rod 22, resulting in an unjoined portion U. This is because the wettability of the brazing material to the ceramic material is very poor. In this sense, a state in which the brazing material simply contacts the exposed ceramic portion is not considered to be a brazing bond as referred to in this specification. Because the unjoined portion U exists on the side of the terminal hole 18, the unjoined portion U functions as a stress buffer layer, thereby reducing the risk of cracking and breakage. In other words, because the unjoined portion U is not bonded to the terminal rod 22 and the metal-containing member 20, it can absorb displacement caused by differences in thermal expansion coefficients that occur during manufacturing and use. Furthermore, since the purpose of the brazing on the side surface of the terminal rod 22 is to maintain strength and electrical properties are not required, oxidation of the electrode portion (metal-containing member 20) on the side surface during use in the atmosphere does not affect quality. This is because it is sufficient if the brazing on the bottom surface of the terminal rod 22 ensures electrical properties. Therefore, the brazing on the side surface of the terminal rod 22 can also serve as a sacrificial material that protects the electrical functional layer (bulk electrode 16, etc.) on the bottom surface of the terminal hole 18 from oxidation.

[0015] In the ceramic plate 12, the main portion (i.e., the ceramic substrate) other than the embedded members such as the internal electrodes 14, the bulk electrodes 16, and the metal-containing members 20 preferably contains aluminum nitride or aluminum oxide, more preferably aluminum nitride, from the viewpoints of excellent thermal conductivity, high electrical insulation, and thermal expansion characteristics similar to those of silicon.

[0016] The ceramic plate 12 is disk-shaped. However, the planar shape of the disk-shaped ceramic plate 12 does not need to be a perfect circle; for example, it may be an incomplete circle with a portion missing, such as an orientation flat. The size of the ceramic plate 12 is not particularly limited and can be determined appropriately depending on the diameter of the wafer to be used. However, when the ceramic plate 12 is circular, the diameter is typically 150 to 450 mm, and particularly for 300 mm silicon wafers, the diameter is typically 320 to 380 mm. The thickness of the ceramic plate 12 is typically 10 to 25 mm.

[0017] The internal electrode 14 is an electrode embedded in the ceramic plate 12. A typical internal electrode 14 includes at least one selected from the group consisting of a heater electrode, an RF electrode, and an ESC electrode. The heater electrode is not particularly limited, but may be, for example, a conductive coil wired in a single stroke across the entire surface of the ceramic plate 12. Terminal rods 22 are connected to both ends of the heater electrode for power supply, and the terminal rods 22 may be connected to a heater power supply (not shown). When power is supplied from the heater power supply, the heater electrode generates heat and heats a wafer placed on the first surface 12a of the ceramic plate 12. The heater electrode is not limited to a coil and may be, for example, a ribbon (a thin, elongated plate), a mesh, or a print. The RF electrode enables film deposition by a plasma CVD process when high frequency is applied. The ESC electrode is an abbreviation for an electrostatic chuck (ESC) electrode and is also called an electrostatic electrode. The ESC electrode is preferably a circular thin-layer electrode slightly smaller in diameter than the ceramic plate 12, and may be, for example, a mesh electrode formed by weaving thin metal wires into a sheet. The ESC electrode may also be used as a plasma electrode. That is, by applying high frequency to the ESC electrode, the ESC electrode can also be used as an RF electrode, allowing for film formation using a plasma CVD process. A terminal rod 22 is connected to the ESC electrode for power supply, and the terminal rod 22 may be connected to an external power supply (not shown). When a voltage is applied from the external power supply, the ESC electrode chucks a wafer placed on the surface of the ceramic plate 12 by the Johnsen-Rahbek force.

[0018] The bulk electrode 16 is an electrode that is embedded in the ceramic plate 12 and connected to the internal electrode 14. It is exposed at the bottom of the terminal hole 18, allowing the terminal rod 22 to be soldered to the exposed portion. Therefore, the bulk electrode 16 is a bulk metal electrode that functions as a terminal for connecting the terminal rod 22 to the internal electrode 14. Since it is desirable to ensure good electrical conductivity at the bottom surface of the terminal rod 22, a bulk metal electrode is used as a buried terminal. Typically, the bulk electrode 16 can be a spherical or cylindrical metal tablet. The bulk electrode 16 preferably contains at least one element selected from the group consisting of Mo, W, and Nb. The bulk electrode 16 has a thermal conductivity of 5.0 × 10 Ω / cm 2 or more at temperatures ranging from room temperature to 800°C. －６ ~9.0 x 10 －６ From the viewpoint of reducing residual stress, it is preferable that the material be made of a material having a linear expansion coefficient of 1 / K.

[0019] The terminal hole 18 is a hole provided so as to extend from the second surface 12b of the ceramic plate 12 to the bulk electrode 16. Therefore, the terminal hole 18 may be a vertical hole provided in the thickness direction of the ceramic plate 12. Therefore, the diameter of the terminal hole 18 is not particularly limited, but is typically 2 to 10 mm, and more typically 4 to 7 mm.

[0020] The metal-containing member 20 is embedded around the terminal hole 18 in the ceramic plate 12, and is provided so that the metal constituting the metal-containing member 20 is exposed on the side and, if desired, the bottom of the terminal hole 18. A preferred shape of the metal-containing member 20 is a cylinder having a central opening 20a for the terminal hole 18, as shown in FIG. 2 . A terminal rod 22 is brazed to the exposed metal portion, while an unjoined portion U is formed in the portion that cannot be brazed. Therefore, the metal-containing member 20 may be any member that can provide an exposed metal portion that can be brazed and a portion that will result in an unjoined portion U that cannot be brazed (e.g., an exposed ceramic portion or a void) on the side of the terminal hole 18. The metal-containing member 20 preferably includes at least one material selected from the group consisting of a porous metal member and a metal-ceramic composite material, and more preferably includes a porous metal member.

[0021] The pores of the porous metal member are preferably filled with ceramic, although some voids may remain. In either case, the portions corresponding to the pores of the porous metal member may result in unjoined portions U that cannot be soldered. The porous metal member has the advantage of easily absorbing and reducing residual stress, even when the diameter of the metal-containing member 20 is increased to increase the joining area. From this perspective, the porous metal member is preferably composed of a porous metal sheet material. Examples of porous sheet materials include metal mesh, punched metal, expanded metal, and combinations thereof. A preferred porous metal member is a cylindrical porous metal member having a central opening 20a for the terminal hole 18, as shown in FIG. 2. The cylindrical porous metal member is preferably composed of a laminate of multiple porous sheet materials with circular openings, or one or more porous sheet materials rolled into a cylindrical shape. The use of a cylindrical porous metal member has the advantage of reducing residual stress because a large amount of ceramic is embedded in the center (hollow portion) of the cylindrical porous metal member during manufacturing. However, it is also possible to use a porous metal member that is not cylindrical during manufacturing, and then form the openings 20a in a drilling process after firing, thereby finally giving it the shape of a cylindrical porous metal member.

[0022] The metal ceramic composite material may be a material in which metal is partially present as a result of firing a mixture of ceramic powder and metal powder. In this case, too, the exposed portion originating from the ceramic powder can result in an unjoined portion U that cannot be brazed.

[0023] The metal-containing member 20 preferably contains at least one selected from the group consisting of Mo, W, and Nb. That is, the metal portion of the porous metal member or the metal ceramic composite material is preferably composed of at least one selected from the group consisting of Mo, W, and Nb. The metal constituting the metal-containing member 20 has a melting point of 5.0 × 10 in the range from room temperature to 800 °C. －６ ~9.0 x 10 －６ From the viewpoint of reducing residual stress, it is preferable that the material be made of a material having a linear expansion coefficient of 1 / K.

[0024] The side surface of the terminal hole 18 includes a conductive region where the metal-containing member 20 is exposed, and the proportion of the area of ​​the conductive region where the metal constituting the metal-containing member is exposed is preferably 30 to 80%, more preferably 50 to 70%. Here, the conductive region refers to the exposed region of the metal-containing member 20 as a whole, and includes not only the region of the exposed metal part but also the region of the part that results in the unbonded portion U (for example, the exposed ceramic part or the void).

[0025] The terminal rod 22 is inserted into the terminal hole 18, one end is connected to the internal electrode 14 via the bulk electrode 16, and the other end extends from the second surface 12b to the outside of the ceramic plate 12. The metal constituting the terminal rod 22 is not particularly limited, but preferred examples include Ni, W, Mo, and a joint structure of Ni and W, and Ni is more preferred.

[0026] Optionally, a ceramic shaft (not shown) may be attached to the second surface 12b of the ceramic plate 12. The ceramic shaft is a cylindrical member with an internal space and may have a configuration similar to that of ceramic shafts used in known ceramic susceptors or ceramic heaters. The internal space is configured to allow the terminal rod 22 to pass therethrough. The ceramic shaft is preferably made of the same ceramic material as the ceramic plate 12. Therefore, the ceramic shaft preferably contains aluminum nitride or aluminum oxide, more preferably aluminum nitride. The upper end surface of the ceramic shaft 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 is not particularly limited, but is preferably 40 to 60 mm. The inner diameter of the ceramic shaft (the diameter of the internal space) is also not particularly limited, but is preferably 33 to 55 mm.

[0027] Manufacturing Method The ceramic susceptor 10 of the present disclosure may be obtained by any manufacturing method, but a preferred manufacturing method will be described below. Figure 3 shows the flow of the manufacturing process for the ceramic susceptor 10.

[0028] (1) Arrangement of Various Materials As shown in FIG. 3( a), a ceramic compact 30 is prepared. The ceramic compact 30 preferably contains aluminum nitride powder or aluminum oxide powder, more preferably aluminum nitride powder. The ceramic compact 30 is preferably in a sheet form. An internal electrode 14 is arranged on the ceramic compact 30. The internal electrode 14 may be a heater electrode, an RF electrode, or an ESC electrode. The arrangement method of the internal electrode 14 may be appropriately selected depending on the shape of the internal electrode 14. For example, in the case of a mesh-shaped internal electrode 14 as shown in FIG. 3, the mesh-shaped internal electrode 14 may be placed on the ceramic compact 30. Next, a bulk electrode 16 is arranged on the internal electrode 14. The bulk electrode 16 may be a spherical or cylindrical metal tablet.

[0029] Next, a metal-containing member 20 is placed on the bulk electrode 16. The metal-containing member 20 preferably includes at least one material selected from the group consisting of a porous metal member and a metal-ceramic composite material, and more preferably includes a porous metal member. The porous metal member is preferably composed of a porous metal sheet material. Examples of porous sheet materials include metal mesh, punched metal, expanded metal, and combinations thereof. At this stage, the metal-containing member 20 may not have openings 20a, as shown in FIG. 3(a). In this case, the porous metal member is preferably a laminate of multiple porous sheet materials. Alternatively, the metal-containing member 20 may already have openings 20a, as shown in FIG. 2. In this case, the porous metal member is preferably a laminate of multiple porous sheet materials having circular openings, or a cylindrical porous metal member composed of one or more porous sheet materials rolled into a cylindrical shape. A laminate of multiple porous sheet materials having circular openings can be easily produced by cutting porous sheet materials into ring shapes and stacking them.

[0030] In this way, the internal electrode 14, the bulk electrode 16, and the metal-containing member 20 arranged on the ceramic powder compact 30 are embedded in ceramic powder 32 to form an embedded electrode body. The ceramic powder 32 also preferably contains aluminum nitride powder or aluminum oxide powder, more preferably aluminum nitride powder. When the metal-containing member 20 is a porous metal member, the pores of the porous metal member are also preferably filled with the ceramic powder 32. Furthermore, when the porous metal member is a cylindrical porous metal member, the hollow portion of the cylindrical porous metal member is also preferably filled with the ceramic powder 32. In this case, since a large amount of ceramic is embedded in the center (hollow portion) of the cylindrical porous metal member, there is an advantage in that residual stress is reduced.

[0031] (2) Press Molding and Sintering As shown in Fig. 3(b), the embedded electrode body is press molded to form an embedded electrode press molded body 34. Then, the embedded electrode press molded body 34 is fired to form an embedded electrode ceramic sintered plate 36. The press molding and firing may be performed simultaneously in one step, or may be performed in separate steps. The procedures and conditions for the press molding and firing may be appropriately determined based on known methods and are not particularly limited.

[0032] (3) Hole Formation As shown in FIGS. 3(c) and 4, a terminal hole 18 is formed in the electrode-embedded ceramic sintered plate 36, so that the bulk electrode 16 is exposed at the bottom of the terminal hole 18, and the metal constituting the metal-containing member 20 is exposed on the side surface and, if desired, the bottom surface of the terminal hole 18 (see FIG. 4).

[0033] (4) Brazing As shown in Fig. 3(d) , a terminal rod 22 is inserted into the terminal hole 18, and the terminal rod 22 is brazed to the exposed portion of the bulk electrode 16 and also to the exposed metal portion of the metal-containing member 20. At this time, an unjoined portion U that is not brazed to the terminal rod 22 is formed between the brazed joints B applied to the exposed metal portions. As described above, brazing is a technique for joining metals to each other with a brazing material, so a brazed joint (chemical bond) is established between the exposed metal portion and the metal terminal rod 22, but no brazed joint is achieved between the exposed ceramic portion and the metal terminal rod 22, resulting in an unjoined portion U. In this manner, the ceramic susceptor 10 is obtained.

Claims

1. A ceramic susceptor comprising: a ceramic plate having a first surface for mounting a wafer and a second surface facing the first surface; an internal electrode embedded in the ceramic plate; a bulk electrode embedded in the ceramic plate and connected to the internal electrode; a terminal hole provided so as to reach the bulk electrode from the second surface of the ceramic plate; a metal-containing member embedded around the terminal hole in the ceramic plate; and a terminal rod inserted into the terminal hole, having one end connected to the internal electrode via the bulk electrode and the other end extending outside the ceramic plate from the second surface, wherein the bulk electrode is exposed at the bottom of the terminal hole, and a metal constituting the metal-containing member is exposed on a side surface or a side surface and a bottom surface of the terminal hole, the terminal rod is brazed to the exposed portion of the bulk electrode, and the terminal rod is brazed to the metal-exposed portion of the metal-containing member, and there is an unjoined portion where no brazing joint with the terminal rod is formed between the brazing joints formed on the metal-exposed portions.

2. The ceramic susceptor according to claim 1, wherein the unjoined portion functions as a stress buffer layer.

3. The ceramic susceptor according to claim 1 or 2, wherein the metal-containing member includes at least one selected from the group consisting of a porous metal member and a metal-ceramic composite material.

4. The ceramic susceptor according to claim 1 or 2, wherein the metal-containing member includes a porous metal member.

5. The ceramic susceptor according to claim 4, wherein the porous metal member is a cylindrical porous metal member composed of a laminate of a plurality of porous sheet materials having circular openings or one or more porous sheet materials wound in a cylindrical shape.

6. The ceramic susceptor according to claim 5, wherein the porous sheet material is at least one selected from the group consisting of a metal mesh, a punched metal, and an expanded metal.

7. Each of the bulk electrode and the metal constituting the metal-containing member has a linear expansion coefficient of 5.0×10 －６ to 9.0×10 －６ / K within the range from room temperature to 800°C, and the ceramic susceptor according to claim 1 or 2 is composed of such a material.

8. The ceramic susceptor according to claim 1 or 2, wherein each of the bulk electrode and the metal-containing member includes at least one selected from the group consisting of Mo, W, and Nb.

9. The side surface of the terminal hole includes a conductive region where the metal-containing member is exposed, and the ratio of the area where the metal constituting the metal-containing member is exposed in the conductive region is 30 to 80%. The ceramic susceptor according to claim 1 or 2.

10. A method for manufacturing a ceramic susceptor, comprising: a step of disposing an internal electrode on a ceramic green compact; a step of disposing a bulk electrode on the internal electrode; a step of disposing a metal-containing member on the bulk electrode; a step of embedding the internal electrode, the bulk electrode, and the metal-containing member disposed on the ceramic green compact with ceramic powder to form an electrode-embedded body; a step of press-molding the electrode-embedded body to form a press-molded electrode-embedded body; a step of firing the press-molded electrode-embedded body to form an electrode-embedded ceramic sintered plate; a step of forming a terminal hole in the electrode-embedded ceramic sintered plate to expose the bulk electrode at the bottom of the terminal hole, and exposing the metal constituting the metal-containing member on the side surface or the side surface and the bottom surface of the terminal hole; and a step of inserting a terminal rod into the terminal hole, brazing the terminal rod to the exposed portion of the bulk electrode, and brazing the terminal rod to the metal-exposed portion of the metal-containing member. At this time, an unjoined portion that is not brazed to the terminal rod is formed between the brazed joints applied to the metal-exposed portion. A method for manufacturing a ceramic susceptor.

11. The method according to claim 10, wherein the metal-containing member includes at least one selected from the group consisting of a porous metal member and a metal-ceramic composite material.

12. The method according to claim 10, wherein the metal-containing member includes a porous metal member.

13. The method according to claim 12, wherein the porous metal member is a cylindrical porous metal member composed of a laminate of a plurality of porous sheet materials having circular openings or one or more porous sheet materials wound in a cylindrical shape.

14. The method according to claim 13, wherein in the step of embedding the internal electrode, the bulk electrode, and the porous metal member with the ceramic powder, the hollow portion of the cylindrical porous metal member is also filled with the ceramic powder.

15. The method according to claim 12, wherein the porous metal member is a laminate of a plurality of porous sheet materials.

16. The method according to any one of claims 13 to 15, wherein the porous sheet material is at least one selected from the group consisting of a metal mesh, a punched metal, and an expanded metal.

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