Method for manufacturing ceramic sintered body, method for manufacturing electrode-embedded member, and electrode-embedded member

Abstract

To provide a method for manufacturing a ceramic sintered body including a via which can cope with larger current, a method for manufacturing an electrode embedding member, and the electrode embedding member.SOLUTION: A method for manufacturing a ceramic sintered body 100 including a via 130 includes the steps of: preparing a porous body 110 formed from a material containing tungsten and molybdenum or at least one of these and turning into the via due to sintering; preparing a flat-plate-like ceramic compact 120 and providing a hole 125 in which the porous body 110 is arranged in the ceramic compact 120; arranging the porous body 110 in the hole 125; and burning the ceramic compact 120 in which the porous body 110 is arranged. The porous body 110 is burnt simultaneously with the ceramic compact 120, and turns into the via 130 embedded into the ceramic sintered body.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a ceramic sintered body having a via, a method for manufacturing an electrode-embedding member, and an electrode-embedding member. [Background technology]

[0002] When manufacturing an electrode-embedded member as a semiconductor manufacturing device member, vias (electrical connection members) are formed to connect the internal electrodes embedded in the ceramic to terminals or to each other.

[0003] Patent Document 1 discloses a method for forming a connecting member by pressurizing a powder material containing a plurality of metal particles in order to suppress cracks in the base material of an electrode-embedded member. metal molded body a ceramic body fabrication step of fabricating a ceramic body in which an internal electrode and a metal molded body are embedded; and a substrate fabrication step of fabricating a substrate in which a connecting member is embedded and which has a space inside which no metal is present by firing the ceramic body in which the internal electrode and the metal molded body are embedded.

[0004] Patent Document 2 discloses a wafer support member in which one main surface of a plate-like ceramic body serves as a mounting surface on which a wafer is placed, at least one internal electrode is provided in the plate-like ceramic body, and a power supply terminal electrically connected to the internal electrode is provided on a surface of the plate-like ceramic body other than the mounting surface, and the thickness of the internal electrode around the connecting portion where the power supply terminal and the internal electrode are electrically connected is made thicker than the thickness of the other internal electrodes, in order to prevent abnormal heating due to an increase in current density on the surface of the electrostatic attraction electrode around the connecting portion where the power supply terminal and the internal electrode are electrically connected.

[0005] Patent Document 3 discloses a ceramic joining structure in which a part of the metal member is exposed on the joining surface that comes into contact with the joining layer of the ceramic member to form an exposed metal portion, so as to prevent erosion of the embedded member or poor insulation even when exposed to air or the like during long-term operation in a high-temperature region, and the ceramic member and the exposed metal portion are each joined to a metal joining member via a joining layer along this joining surface, and the main component of the joining layer is one or more metals selected from the group consisting of gold, platinum, and palladium. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-208006 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-277335 [Patent Document 3] Japanese Patent Application Publication No. 11-12053 Summary of the Invention [Problem to be solved by the invention]

[0007] In order to accommodate the increasing currents required for heaters and electrostatic chucks in recent semiconductor manufacturing processes, it is necessary to suppress local heat generation in vias. To achieve this, it is desirable for the vias to be large in diameter and as dense as possible, but Patent Document 1 does not take into consideration the densification of connection members, and Patent Document 3 does not consider the increase in the diameter of terminals.

[0008] In addition, in the green sheet lamination method described in Patent Document 2, via holes are formed by filling holes drilled in sheets by screen printing with a paste of tungsten or molybdenum. However, because the paste contains a large amount of organic binders and solvent components to form the paste, shrinkage occurs on the surface during the drying process before firing, as shown in Figure 1. This causes the paste surface to become concave relative to the ceramic surface, resulting in poor electrical conductivity when the sheets are laminated. This problem is particularly likely to occur when the ceramic green sheets are thick or the via diameter is large. Furthermore, when a ceramic compact formed by pressing ceramic powder is used, it is even more difficult to form vias by injecting paste into holes in the ceramic compact.

[0009] Another approach has been to create vias by using tungsten (W) or molybdenum (Mo) as metal pellets instead of paste, embedding them in a ceramic compact together with the electrodes, and firing them simultaneously. However, when large pellets are embedded in a ceramic compact and fired simultaneously, stress is generated due to the difference in the firing shrinkage rate between the ceramic and the W or Mo, and cracks often occur near the boundary between the two after firing. For this reason, it was not possible to increase the size of the W or Mo pellets. This limited their applicability in applications where the pellets themselves were used as vias and large currents were required to flow through them.

[0010] The present invention has been made in consideration of the above circumstances, and aims to provide a method for manufacturing a ceramic sintered body having vias that can accommodate large currents, a method for manufacturing an electrode-embedded member, and an electrode-embedded member. [Means for solving the problem]

[0011] (1) In order to achieve the above object, the present invention Reference aspects related toThe method for manufacturing a ceramic sintered body is a method for manufacturing a ceramic sintered body having a via, and includes the steps of: preparing a porous body formed of tungsten, molybdenum, or a material containing at least one of them, which will become the via upon sintering; preparing a flat ceramic molded body and providing a hole in the ceramic molded body in which the porous body will be placed; placing the porous body in the hole; and firing the ceramic molded body with the porous body placed in it, wherein the porous body is fired simultaneously with the ceramic molded body to become the via embedded in the ceramic sintered body.

[0012] In this way, by using a porous metal body and firing it simultaneously with a ceramic molded body, it is possible to form a metallic via inside the ceramic sintered body even if the shrinkage rate of the ceramic and the shrinkage rate of the porous body are different. This makes it possible to reduce the occurrence of cracks in the ceramic sintered body due to the difference in shrinkage rate caused by the dense metal body being too large when vias are formed using a dense metal body, and to reduce poor contact of the via caused by the dense metal body being too small.

[0013] (2) Also, a ceramic sintered body according to a reference embodiment of the present invention Manufacturing method In the method, the porous body is arranged in the hole portion without any gaps, and the step of firing the ceramic molded body is characterized in that the porous body is fired by uniaxial hot press firing, in which pressure is applied in the height direction of the porous body.

[0014] This allows the holes to be formed with approximately the same shape and size as the bottom surface of the porous body, since shrinkage occurs only in the pressure direction during uniaxial hot press sintering. The size of the porous body also requires consideration of shrinkage only in the height direction, making dimensional design easier. Furthermore, cracks in the ceramic sintered body and poor contact of vias can be more reliably reduced.

[0015] (3) Also, the present invention Reference aspects related toIn the method for manufacturing a ceramic sintered body, the porous body is formed into a cylindrical shape with a maximum diameter of 1.0 mm or more and a height of 1.0 mm or more after the step of firing the ceramic molded body.

[0016] This allows for larger currents to be passed through larger via geometries.

[0017] (4) The present invention Reference aspects related to a method for manufacturing an electrode-embedded member having a via, the method comprising the steps of: preparing a porous body formed of tungsten, molybdenum, or a material containing at least one of them, which will become the via upon firing; preparing a flat first ceramic body and providing a hole in the first ceramic body in which the porous body will be placed; placing the porous body in the hole; preparing an internal electrode and placing the internal electrode on the upper surface of the ceramic body so as to overlap the hole; placing a second ceramic body on the upper surface of the first ceramic body in which the internal electrode and the porous body are placed; and firing the first and second ceramic bodies, wherein the porous body is fired simultaneously with the first and second ceramic bodies, and becomes the via that is embedded in the sintered ceramic body and electrically connected to the internal electrode.

[0018] This makes it possible to form an electrode-embedding member that is less likely to cause cracks in the ceramic sintered body or poor contact between the vias and the internal electrodes.

[0019] (5) The present invention Reference aspects related toThe method for manufacturing an electrode-embedded member further includes the steps of preparing a second internal electrode and arranging the second internal electrode on the underside of the first ceramic molding so as to overlap the hole portion, and arranging a third ceramic molding on the underside of the first ceramic molding on which the second internal electrode and the porous body are arranged, wherein the hole portion penetrates the first ceramic molding, and the porous body is fired simultaneously with the first, second, and third ceramic moldings, embedded in the ceramic sintered body, and becomes the via that electrically connects the internal electrode and the second internal electrode.

[0020] This ensures conductivity between the internal electrodes formed on different layers, and as a result, it is possible to minimize the number of holes formed from the outside of the electrode-embedded member and pass current through the internal electrodes.In addition, by using one of the electrodes as a conductive wiring electrode, it is possible to easily supply power to the heating resistors arranged in the outer peripheral region, making it easy to configure a multi-zone heater, etc.

[0021] (6) The electrode-embedded member of the present invention comprises a base body formed of a ceramic sintered body, a plurality of internal electrodes embedded in a plurality of layers inside the base body, and vias embedded inside the base body and electrically connecting at least two of the plurality of internal electrodes, the vias being formed of tungsten, molybdenum, or a material containing at least one of them, and the relative density of the vias is 88 % or more and 92% or less, and the vias are formed in a columnar shape with a maximum diameter of 1.0 mm or more and a height of 1.0 mm or more.

[0022] This ensures electrical conductivity between the internal electrodes formed on different layers, allowing current to flow through the internal electrodes with as few holes as possible formed from the outside of the electrode-embedding member, making it possible to configure, for example, a multi-zone heater. [Effects of the Invention]

[0023] According to the present invention, a method for manufacturing a ceramic sintered body having a via, a method for manufacturing an electrode-embedded member, and an electrode-embedded member can be provided, which can accommodate large currents. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a cross-sectional view showing a defect of the prior art. [Figure 2] 3A to 3C are cross-sectional views showing an example of a manufacturing process for the ceramic sintered body having vias according to the first embodiment. [Figure 3] 3A to 3C are cross-sectional views showing an example of a manufacturing process for the ceramic sintered body having vias according to the first embodiment. [Figure 4] 10(a) and 10(b) are top and bottom perspective views showing examples of heaters according to the second and third embodiments, respectively. [Figure 5] 10A and 10B are top and bottom perspective views showing examples of electrostatic chucks according to second and third embodiments, respectively. [Figure 6] 5A to 5C are cross-sectional views showing an example of a manufacturing process for the heater of the second embodiment. [Figure 7] FIG. 4 is a cross-sectional view showing an example of a heater according to a second embodiment. [Figure 8] 10A to 10C are cross-sectional views showing a modified example of the manufacturing process of the heater of the second embodiment. [Figure 9] FIG. 10 is a cross-sectional view showing a modified example of the heater of the second embodiment. [Figure 10] 10A to 10C are cross-sectional views showing an example of a manufacturing process for the heater of the third embodiment. [Figure 11] FIG. 10 is a cross-sectional view showing an example of a heater according to a third embodiment. [Figure 12] FIG. 10 is a cross-sectional view showing a modified example of the heater of the third embodiment. [Figure 13] FIG. 10 is a cross-sectional view showing an example of an electrode-embedding member according to a third embodiment. [Figure 14] FIG. 10 is a cross-sectional view showing a modified example of the electrode-embedding member of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] Next, an embodiment of the present invention will be described with reference to the drawings. To facilitate understanding of the description, the same reference numerals are used to designate the same components in the drawings, and duplicated descriptions will be omitted. Note that in the configuration diagrams, the size of each component is shown conceptually and does not necessarily represent the actual dimensional ratio.

[0026] [First embodiment] [Method for manufacturing sintered ceramics] A method for manufacturing a ceramic sintered body according to this embodiment will be described. Figures 2 and 3 are cross-sectional views showing an example of a manufacturing process for a ceramic sintered body 100 having a via according to the first embodiment. Figure 2 shows a manufacturing method using uniaxial hot pressing. Figure 3 shows a first embodiment manufacturing method using atmospheric firing.

[0027] First, a porous body 110 is prepared, which is made of tungsten (W), molybdenum (Mo), or a material containing at least one of these, and which will become vias upon sintering. The relative density of the porous body 110 is preferably 40% to 90%, more preferably 60% to 80%. A porous body with a relative density of less than 40% is difficult to manufacture and is likely to have a shrinkage rate greater than that of the ceramic compact 120 when fired, making it difficult to adjust the size of the porous body 110 and the holes 125 (described below). A porous body with a relative density greater than 90% is likely to have a shrinkage rate significantly smaller than that of the ceramic compact 120 when fired, making it difficult to adjust the size of the porous body 110 and the holes 125 (described below). The difference between the maximum shrinkage rate of the porous body 110 during firing and the shrinkage rate of the ceramic molded body 120 during firing is preferably 0 to 50 points, more preferably 10 to 30 points.

[0028] The relative density and size of the porous body 110 are preferably determined based on the shrinkage rate when the ceramic molded body 120 is fired and the target relative density of the vias 130 after sintering the porous body 110. Furthermore, the porous body 110 is preferably formed into a cylindrical shape with a maximum diameter of 1.0 mm or more and a height of 1.0 mm or more after firing the ceramic molded body 120. A maximum diameter of less than 1.0 mm makes it difficult to manufacture the porous body 110. Furthermore, the maximum diameter of the porous body 110 after firing is more preferably 1.5 mm or more, and the height is more preferably 3.0 mm or more. This allows a larger current to pass through the large vias 130 between different layers separated in the thickness direction of the ceramic sintered body 100 having the vias. There is no need to set upper limits on the maximum diameter and height of the porous body 110 after firing. However, considering the size required for use as a via, the maximum diameter and height can be set to, for example, 10 mm or less and 20 mm or less. Furthermore, the porous body 110 may have a columnar shape other than a cylindrical shape.

[0029] Any method may be used to produce the porous body 110. For example, the porous body 110 can be produced by uniaxial press molding a powder raw material in which a binder is added to metal particles. Note that, in order to remove the binder, a degreasing step may be performed in which the pressure-molded porous body 110 is degreased in an air atmosphere or a nitrogen atmosphere at a temperature range of 200°C to 600°C. Alternatively, the pressure-molded or degreased porous body 110 may be calcined in a nitrogen, argon, or vacuum atmosphere furnace at a temperature of, for example, 1000°C to 1800°C, to form the porous body 110 as a calcined body. Furthermore, the outer diameter and thickness of the porous body 110 may be adjusted by grinding or polishing.

[0030] Next, a flat ceramic molded body 120 is prepared. Existing methods can be used to manufacture the ceramic molded body 120. The material can also be selected appropriately depending on the intended use of the ceramic sintered body 140 to be manufactured. For example, raw material powders such as Al2O3, AlN, Si3N4, and SiC are granulated to form a granulated powder. Sintering aids, binders, etc. may be added. The obtained granulated powder is then used to manufacture a ceramic molded body 120 of a predetermined shape. A degreasing process may be performed in which the ceramic molded body 120 is degreased at a predetermined temperature or higher for a predetermined time or longer. An atmospheric furnace or a nitrogen atmosphere furnace may be used for degreasing.

[0031] Next, a hole 125 in which the porous body 110 is to be placed is provided in the ceramic molded body 120. The hole 125 is preferably made to a size that allows the porous body 110, i.e., the via 130, to adhere to the hole 125 after firing and reduces the stress therebetween, depending on the shrinkage rate of the ceramic molded body 120, the shrinkage rate of the porous body 110, the firing method, the firing conditions, etc.

[0032] Next, the porous body 110 is placed in the hole 125. Then, the ceramic molded body 120 with the porous body 110 placed therein is fired. The sintering conditions may be the same as those for producing a normal ceramic sintered body, and for example, firing can be performed by holding the body at a temperature of 1400°C or higher and 2200°C or lower for 0.1 hours to 10 hours. Normal pressure firing or uniaxial hot press firing can be used for firing. The relative density of the porous body 110 after sintering, i.e., the vias 130, is preferably higher than the relative density of the porous body 110. Furthermore, the relative density of the vias 130 is preferably higher than 80%, more preferably 90% or higher, and even more preferably 95% or higher.

[0033] In the case of uniaxial hot-press sintering, it is preferable that the porous body 110 is arranged without gaps in the holes 125. That is, when the shrinkage rate of the porous body 110 is smaller than that of the ceramic molded body 120 and the porous body 110 is sintered by uniaxial hot-press sintering, it is preferable that the size of the surface perpendicular to the axial direction (pressure direction) of the holes 125 is approximately the same as the size of the surface perpendicular to the axial direction of the porous body 110, and the axial size of the holes 125 is larger than the axial size of the porous body 110, as shown in FIG.

[0034] Since uniaxial hot press firing shrinks only in the pressure direction, the shape and size of the surface perpendicular to the axial direction of the hole 125 can be made substantially identical to the bottom surface of the porous body 110, and the size of the porous body 110 only needs to be considered in terms of shrinkage in the axial direction, making dimensional design easier. Furthermore, the occurrence of cracks in the ceramic sintered body 100 having vias and poor contact of the vias can be more reliably reduced.

[0035] On the other hand, in the case of atmospheric firing, it is preferable to arrange the porous body 110 and the hole 125 with an overall gap therebetween. That is, when the shrinkage rate of the porous body 110 is smaller than that of the ceramic compact 120 and the porous body 110 is fired by atmospheric firing, it is preferable to make the overall size of the hole 125 larger than the size of the porous body 110, as shown in Fig. 3. This is because, in the case of atmospheric firing, both the porous body 110 and the ceramic compact 120 shrink overall.

[0036] Therefore, uniaxial hot press firing is preferred, which allows for easy size adjustment of the porous body 110 and the holes 125. In FIGS. 2 and 3 , the vias 130 penetrate the ceramic sintered body 140, and the upper and lower surfaces of the vias 130 are exposed to the upper and lower surfaces of the via-containing ceramic sintered body 100. However, one or both surfaces of the vias 130 may be covered by the ceramic sintered body 140. In this case, the covered surfaces are preferably electrically connected to a conductive member (not shown) embedded in the via-containing ceramic sintered body 100, or to a terminal hole that exposes a portion of the via 130 for external electrical connection. Although terminals are not shown in FIGS. 2 and 3 , the number of terminals connected to the via-containing ceramic sintered body 100, i.e., the number of terminal connection positions, may be two or more.

[0037] The porous body 110 is fired simultaneously with the ceramic compact 120 to form the vias 130 embedded in the ceramic sintered body 140 .

[0038] In this way, a ceramic sintered body 100 having vias can be manufactured. In the method for manufacturing a ceramic sintered body of the present invention, a porous metal body is used and fired simultaneously with a ceramic molded body, so that a metallic via can be formed inside the ceramic sintered body even if the shrinkage rate of the ceramic and the shrinkage rate of the porous body are different. This reduces the occurrence of cracks in the ceramic sintered body due to the difference in shrinkage rate caused by the dense metal body being too large when vias are formed using a dense metal body, and the poor contact of the via caused by the dense metal body being too small.

[0039] [Second embodiment] [Method for manufacturing electrode-embedded members] A method for manufacturing an electrode-embedded member according to this embodiment will be described. The basic manufacturing method is the same as that for manufacturing the via-containing ceramic sintered body 100 of the first embodiment. The manufacturing method for the electrode-embedded member according to this embodiment and the third embodiment will be described using the manufacturing method for the heater with a shaft shown in FIG. 4 as an example. However, the manufacturing method for the electrode-embedded member of the present invention can be applied to the manufacturing of an electrostatic chuck shown in FIG. 5 and various other electrode-embedded members with vias used for other purposes, and the shape is not limited to that shown. FIGS. 4(a) and 4(b) are top and bottom perspective views, respectively, of an example heater according to the second and third embodiments. Also, FIGS. 5(a) and 5(b) are top and bottom perspective views, respectively, of an example electrostatic chuck according to the second and third embodiments.

[0040] Fig. 6 is a cross-sectional view showing an example of a manufacturing process for the heater of this embodiment. Fig. 7 is a cross-sectional view showing an example of the heater of this embodiment. First, a porous body 110 is prepared, which is made of tungsten (W), molybdenum (Mo), or a material containing at least one of these, and which will become vias 130 by sintering. The relative density of the porous body 110, the size range after sintering, the manufacturing method, etc. are the same as those in the first embodiment.

[0041] Next, a flat-plate-shaped first ceramic compact 121 is prepared. Next, a hole 125 in which the porous body 110 is to be disposed is provided in the first ceramic compact 121. In the first embodiment, the hole 125 penetrates the ceramic compact 120. However, in this embodiment, it is sufficient that the porous body 110 disposed in the hole 125 contacts the internal electrode 150 disposed on the upper surface of the first ceramic compact 121. Therefore, the hole 125 may be provided so as to penetrate the first ceramic compact 121, or may not penetrate the first ceramic compact 121. FIG. 6 shows an example in which the hole 125 does not penetrate the first ceramic compact 121. When the hole 125 is provided so as not to penetrate, a terminal hole 127 may be provided that reaches the via 130 from the lower surface after firing. The hole 125 is preferably made to a size that allows the porous body 110 after firing, i.e., the via 130, to adhere to the hole 125 after firing and reduces the stress therebetween, depending on the shrinkage rate of the first ceramic compact 121 and the shrinkage rate of the porous body 110. Next, the porous body 110 is placed in the hole 125.

[0042] Next, the internal electrode 150 is prepared and placed on the upper surface of the first ceramic compact 121 so as to overlap the hole 125. The internal electrode 150 can be shaped in various ways depending on the application, such as a mesh or foil. The material can also be made of various materials depending on the application, such as molybdenum or tungsten. The prepared internal electrode 150 is placed so as to overlap the hole 125 so as to ensure contact with the porous body 110 placed in the hole 125 after firing. At this time, a groove or the like matching the shape of the internal electrode 150 may be formed on the upper surface of the first ceramic compact 121.

[0043] Next, the second ceramic molded body 122 is prepared and placed on the upper surface of the first ceramic molded body 121 on which the internal electrode 150 and the porous body 110 are arranged. The second ceramic molded body 122 serves as a protective layer that covers the internal electrode 150 and the via 130. The second ceramic molded body 122 is preferably in the shape of a flat plate.

[0044] The first and second ceramic molded bodies 121, 122 may be manufactured by an existing method, as described above. Various materials may also be used depending on the application. The second ceramic molded body 122 may be formed as a molded body and then placed on the top surface of the first ceramic molded body 121, or the second ceramic molded body 122 may be formed by filling the top surface of the first ceramic molded body 121 with an appropriate amount of granulated ceramic powder and then subjecting it to a pressure treatment.

[0045] The first and second ceramic molded bodies 121, 122 are fired to form an integrated ceramic sintered body 140 in which the internal electrode 150 and the via 130 are embedded. Furthermore, the porous body 110 is fired simultaneously with the first and second ceramic molded bodies 121, 122 to form the via 130 embedded in the ceramic sintered body 140 and electrically connected to the internal electrode 150. The via 130 is then electrically connected to the terminal 180. The number of terminals 180, i.e., the number of terminal connection positions in the electrode-embedding member 200, may be three or more.

[0046] When the electrode-embedded member 200 is used as a heater, it may be joined to a shaft 170 after firing. This makes it possible to make a heater with a shaft. The shaft 170 is preferably formed in a columnar shape such as a cylinder. Furthermore, the shaft 170 is preferably formed of a ceramic sintered body made of the same main component as the main component of the ceramic sintered body 140 of the electrode-embedded member 200.

[0047] (Variation) FIG. 8 is a cross-sectional view showing a modified example of the manufacturing process of the heater of the second embodiment using a third ceramic molded body and a connecting member (pellet). FIG. 9 is a cross-sectional view showing a modified example of the heater of the second embodiment using a third ceramic molded body and a pellet. In the step of providing the hole 125, the hole 125 may be provided so as to penetrate the first ceramic molded body 121, and a third ceramic molded body 123 having a pellet 160 disposed at the position of the hole 125 of the first ceramic molded body 121 may be disposed on the underside of the first ceramic molded body 121. Alternatively, a metal pellet 160 may be disposed on the bottom surface of the hole 125, separate from the porous body 110.

[0048] In these cases, electrical connection from the outside can be made through the pellet 160 rather than directly to the via 130. The pellet 160 may also be inserted between the internal electrode 150 and the porous body 110. In this case, a groove for accommodating the pellet 160 can be formed on the upper surface of the first ceramic compact 121. The pellet 160 preferably has a maximum diameter of 5 mm to 12 mm and a thickness of 0.1 mm to 0.5 mm. The pellet 160 can be made of tungsten, molybdenum, or the like. The pellet 160 is a dense bulk body, not a porous body. The pellet 160 is sufficiently thin so that it does not cause cracks in the ceramic sintered body 140 during firing or when the electrode-embedded member 200 is used.

[0049] In this manner, an electrode-embedding member 200 having an internal electrode 150 and a via 130 can be manufactured. The method for manufacturing an electrode-embedding member of the present invention can form an electrode-embedding member that is less likely to cause cracks in the ceramic sintered body or poor contact between the via and the internal electrode. Furthermore, the method for manufacturing an electrode-embedding member of the present invention can manufacture an electrode-embedding member in which even large-diameter vias are completely embedded in the ceramic sintered body, making it possible to accommodate large currents.

[0050] [Third embodiment] [Method for manufacturing electrode-embedded members] A method for manufacturing an electrode-embedded member according to this embodiment will now be described. The basic manufacturing method is the same as that for manufacturing the electrode-embedded member 200 of the second embodiment. FIG. 10 is a cross-sectional view showing an example of the manufacturing process for a heater according to this embodiment. FIG. 11 is a cross-sectional view showing an example of a heater according to this embodiment. First, a porous body 110 is prepared, which is made of tungsten (W), molybdenum (Mo), or a material containing at least one of these, and which will become a via 130 by sintering. The relative density of the porous body 110, the size range after sintering, the manufacturing method, etc. are the same as those of the first embodiment.

[0051] Next, a flat-plate-shaped first ceramic compact 121 is prepared. Next, a hole 125 in which the porous body 110 is to be placed is provided in the first ceramic compact 121. At this time, in the second embodiment, the hole 125 does not need to penetrate the first ceramic compact 121. However, in this embodiment, the hole 125 is provided to penetrate the first ceramic compact 121 so that the porous body 110 placed in the hole 125 comes into contact with the second internal electrode 152 placed on the underside of the first ceramic compact 121 after firing. Next, the porous body 110 is placed in the hole 125.

[0052] Next, the internal electrode 150 is prepared and placed on the upper surface of the first ceramic molded body 121 so as to overlap the hole 125. The shape and material of the internal electrode 150 are the same as those in the second embodiment. The prepared internal electrode 150 is placed so as to overlap the hole 125 so as to ensure contact with the porous body 110 placed in the hole 125 after firing. At this time, a groove or the like matching the shape of the internal electrode 150 may be formed on the upper surface of the first ceramic molded body 121.

[0053] Next, a second ceramic compact 122 is prepared and placed on the top surface of the first ceramic compact 121 on which the internal electrode 150 and the porous body 110 are placed. The second ceramic compact 122 serves as a protective layer that covers the internal electrode 150 and the via 130. The second ceramic compact 122 is preferably in the shape of a flat plate. The second ceramic compact 122 may be formed as a compact and then placed on the top surface of the first ceramic compact 121, or may be formed by filling the top surface of the first ceramic compact 121 with an appropriate amount of granulated ceramic powder and subjecting it to a pressure treatment.

[0054] Next, a second internal electrode 152 is prepared and placed on the lower surface of the first ceramic molded body 121 so as to overlap the hole 125. In this embodiment, the internal electrode 150 and the second internal electrode 152 may be made of the same material or different materials and shapes depending on the application. One of the internal electrodes may be used as a routing electrode for electrically connecting the via 130 to the terminal 180. The prepared second internal electrode 152 is placed so as to overlap the hole 125 so as to ensure contact with the porous body 110 placed in the hole 125 after firing. At this time, a groove or the like matching the shape of the second internal electrode 152 may be formed on the lower surface of the first ceramic molded body 121 or on the upper surface of a third ceramic molded body 123 (described later).

[0055] Next, a third ceramic molded body 123 is prepared and placed on the lower surface of the first ceramic molded body 121 on which the second internal electrode 152 and the porous body 110 are placed. The third ceramic molded body 123 serves as a protective layer that covers the second internal electrode 152 and the via 130. The third ceramic molded body 123 is preferably in the shape of a flat plate.

[0056] As with the above, the first, second, and third ceramic bodies 121, 122, and 123 may be made by the same existing method. Also, various materials may be used depending on the application.

[0057] The first, second, and third ceramic molded bodies 121, 122, and 123 are integrated by firing to form a ceramic sintered body 140 in which two layers of internal electrodes 150 and 152 and vias 130 are embedded. The porous body 110 is simultaneously fired with the first, second, and third ceramic molded bodies 121, 122, and 123 to form the ceramic sintered body 140 and the vias 130 that electrically connect the internal electrode 150 and the second internal electrode 152. This ensures electrical conductivity between the internal electrodes formed in different layers spaced apart in the thickness direction of the electrode-embedding member. As a result, current can be passed through the internal electrodes with minimal holes formed from the outside of the electrode-embedding member, enabling the construction of, for example, a multi-zone heater. The internal electrode 150 and the second internal electrode 152 are electrically connected to terminals 180. The number of terminals 180, i.e., the number of terminal connection positions in the electrode-embedding member 200, may be three or more.

[0058] Furthermore, as in the second embodiment, when the electrode-embedded member 200 is used as a heater, it may be joined to a shaft 170 after firing. This makes it possible to make a heater with a shaft. The shape, material, etc. of the shaft 170 are the same as in the second embodiment.

[0059] Furthermore, when connecting the second internal electrode 152 and the terminal 180, a metal pellet 160 may be placed at the terminal connection position on the upper surface of the third ceramic molded body 123. In this case, a recess for placing the pellet 160 may be provided on the upper surface of the third ceramic molded body 123. The pellet 160 may also be placed between the internal electrode 150 or the second internal electrode 152 and the porous body 110. The material, size, etc. of the pellet 160 are the same as those in the second embodiment.

[0060] In this way, it is possible to manufacture an electrode-embedding member 200 having a plurality of internal electrodes 150, 152 and vias 130. The method for manufacturing an electrode-embedding member of the present invention can manufacture an electrode-embedding member configured so that even large-diameter vias are completely embedded in the ceramic sintered compact without causing defects such as cracks in the ceramic sintered compact, and can accommodate large currents.

[0061] (Variation) Fig. 12 is a cross-sectional view showing a modified example of the heater of the third embodiment. As shown in Fig. 12, the position of the via 130 can be set to a position that is unrelated to the position of the terminal 180. This allows the electrode-embedding member 200 to have a variety of configurations, widening the range of applications.

[0062] [Configuration of electrode embedding material] Next, an electrode-embedded member 200 according to this embodiment will be described. Fig. 13 is a cross-sectional view showing an example of the electrode-embedded member 200 according to this embodiment. Fig. 14 is a cross-sectional view showing a modified example of the electrode-embedded member 200 according to this embodiment. The only difference between Figs. 13 and 14 is the position of the via 130. The electrode-embedded member 200 includes a base 190, a plurality of internal electrodes 150, 152, and the via 130.

[0063] The base 190 is formed of a sintered ceramic body. Various materials can be used for the base 190 depending on the application. For example, Al2O3, AlN, Si3N4, SiC, etc. can be used. The shape of the base 190 can be various depending on the application, such as an electrostatic chuck or a heater.

[0064] The internal electrodes 150, 152 are embedded in multiple layers within the base 190. The multiple layers refer to surfaces within the base 190 that are substantially parallel to the wafer-mounting surface 192 of the base 190. The internal electrodes 150, 152 may have any number of layers. FIG. 13 shows an example having two layers of internal electrodes 150, 152. The internal electrodes 150, 152 may have various shapes, such as mesh or foil, depending on the application. Furthermore, the internal electrodes 150, 152 may be made of various materials, such as molybdenum or tungsten, depending on the application. The internal electrodes 150, 152 may be made of the same material or different materials depending on the application. Furthermore, the internal electrodes 150 or 152 may serve as conductive wiring electrodes for electrically connecting the via 130 to the terminal 180.

[0065] The vias 130 are embedded inside the base 190 and electrically connect the internal electrodes 150, 152. This ensures conductivity between the internal electrodes 150, 152 formed on different layers. As a result, current can be passed through the internal electrodes 150, 152 with as few holes formed from the outside of the electrode-embedding member 200 as possible, making it possible to configure, for example, a multi-zone heater. Note that the number of terminals 180, i.e., the number of terminal connection positions in the electrode-embedding member 200, may be three or more.

[0066] The vias 130 are formed from tungsten, molybdenum, or a material containing at least one of these. The vias 130 are formed in a columnar shape with a maximum diameter of 1.0 mm or more and a height of 1.0 mm or more. The maximum diameter of the vias 130 is preferably 1.5 mm or more, and the height is more preferably 3.0 mm or more. This allows a larger current to pass through the large vias 130 between different layers separated by a distance in the thickness direction of the electrode-embedded member, even in the outer periphery of the base 190 (e.g., the outer region of the shaft, if present). There is no particular upper limit to the maximum diameter and height of the vias 130. However, taking into consideration the size required for use as a via, the maximum diameter and height can be set to, for example, 15 mm or less and 30 mm or less. The relative density of the vias 130 is preferably greater than 80%, more preferably 90% or more, and even more preferably 95% or more. The porous body 110 is preferably cylindrical.

[0067] When there is one via 130, it is preferable that the via 130 is embedded inside the base 190 and has no portion exposed from the base 190. When there are multiple vias 130, it is preferable that at least one of them is embedded inside the base 190 and has no portion exposed from the base 190.

[0068] A metal pellet 160 may be disposed at a terminal connection position for connecting a terminal 180 for electrical connection to the outside of the electrode-embedding member 200 or between the internal electrode 150 and the via 130. The material, size, etc. of the pellet 160 are the same as those described above.

[0069] The electrode-embedding member 200 of the present invention can be configured in such a way that it has been difficult to achieve so far, and as a result, it is possible to pass a larger current through a large via hole than before, which makes it possible to apply it to a variety of uses.

[0070] [Example] Example 1 According to the manufacturing method of the second embodiment, a heater for heating wafers used in semiconductor manufacturing equipment was manufactured by hot pressing. First, a raw material powder mainly composed of AlN to which an organic binder was added was press-molded to produce a first ceramic molded body with a diameter of 300 mm and a thickness of 10 mm, a second ceramic molded body with a diameter of 300 mm and a thickness of 10 mm, and a third ceramic molded body with a diameter of 300 mm and a thickness of 10 mm. Next, a degreasing process was performed in an atmosphere of 500°C or higher in air.

[0071] Next, a 2mm diameter through-hole (hole portion) for forming a via was drilled in the first ceramic compact. A porous body was also prepared. In the case of uniaxial hot press sintering, the volume (i.e., thickness) of the AlN ceramic compact after sintering is reduced to approximately 60%, resulting in a hole size of approximately 2mm diameter x 6mm in the first ceramic compact after sintering. Therefore, for example, if a porous body with a relative density of 75% is used and a via with a height of 6mm is to be formed after sintering, taking into account a maximum reduction of approximately 25% in height, a cylindrical porous body with a diameter of 2mm and a height of 6mm to 8mm can be used. This ensures that the dimensions of the hole after shrinkage in the sintered ceramic body after sintering are approximately the same as the dimensions of the porous body after sintering shrinkage, and a via with a size of approximately 2mm diameter x 6mm is formed in the sintered ceramic body. This results in no cracks around the via, and the porous body is sufficiently densified as close to the upper limit of the range, resulting in a via with sufficiently low electrical resistance. In this example, a porous body having a relative density of 75%, a diameter of 2 mm, and a height of 7.2 mm was prepared, and the prepared porous body was inserted into the hole.

[0072] Next, an internal electrode was prepared. The internal electrode was a heater electrode made by cutting a Mo mesh into a predetermined shape. A groove in which the internal electrode was to be placed was machined in the first ceramic compact. The prepared internal electrode was then placed in the groove of the first ceramic compact, with the porous body inserted into the hole, to form the first layer.

[0073] Next, a W pellet was prepared. The W pellet had dimensions of Φ5 mm and a thickness of 0.5 mm. A groove for placing the W pellet was formed on the top surface of the third ceramic compact, between the via and the terminal. The W pellet was then placed in the groove of the third ceramic compact to form the third layer. Here, the W pellet was made of bulk tungsten and served as a pad to which the terminal was brazed after firing. This allowed for an electrical connection between the terminal and the heater electrode (internal electrode) via the pellet and the via.

[0074] The third layer thus prepared was placed under the first layer, and a second ceramic compact was placed on top of the first layer as the second layer. The resulting ceramic compact was then uniaxially hot-pressed and sintered in a nitrogen atmosphere at 1800°C or higher and 1 MPa or higher to form an integrated structure. The embedded W pellets were then exposed from the sintered ceramic compact by processing. A shaft was then attached to the bottom of the heater. Finally, a 4mm diameter Ni terminal was brazed to the exposed pellet, completing the heater with a shaft according to Example 1.

[0075] Example 2 A heater was produced under the same conditions as in Example 1, except that the diameter of the through-hole for forming a via provided in the first ceramic molded body and the relative density of the porous body were changed. That is, a heater was produced using a cylindrical porous body with a diameter of 1.5 mm and a height of 7.8 mm, using a through-hole (hole portion) for forming a via and a porous body with a relative density of 65%.

[0076] Example 3 A heater was fabricated under the same conditions as in Example 1, except that the diameter of the through hole for forming a via provided in the first ceramic molded body, and the material and relative density of the porous body were changed. That is, a heater was fabricated using a cylindrical porous body with a diameter of 1.5 mm and a height of 6.8 mm, which had a diameter of 1.5 mm for forming a via, and was made of Mo and had a relative density of 80%.

[0077] (Functional evaluation) A current of 20 A was passed through the heater electrodes of the heaters fabricated in Examples 1 to 3, and the heater surface temperature was observed with an infrared camera. As a result of the observation, it was confirmed that no hot spots occurred even directly above the vias in any of Examples 1 to 3, and that localized heat generation in the vias was suppressed.

[0078] (Cross-section observation) After the functional evaluation, the ceramic sintered body and vias of the heaters of Examples 1 to 3 were cut and the cross sections were observed. In all of Examples 1 to 3, no cracks occurred in the ceramic sintered body or the vias at the boundary between the ceramic sintered body and the via. Furthermore, the structure of the vias was sufficiently densified compared to the structure of the porous body embedded in the ceramic molded body.

[0079] (Relative via density measurement) The relative density of the vias was measured by image processing a cross-sectional SEM photograph of the vias (magnification 2000x) to calculate the area ratio of the pores, and then calculating the relative density as 100% per pore. As a result, the relative density of the vias in Example 1 was 90%, in Example 2 it was 88%, and in Example 3 it was 92%. Commercially available software such as Image-Pro can be used for image processing.

[0080] From the above, it was confirmed that the electrode-embedded member of the present invention can handle large currents, and that the manufacturing method of the present invention can manufacture such an electrode-embedded member.

[0081] The present invention is not limited to the above-described embodiments, and various modifications and equivalents are included within the spirit and scope of the present invention. Furthermore, the structure, shape, number, position, size, etc. of the components shown in each drawing are for the convenience of explanation and may be changed as appropriate. [Explanation of symbols]

[0082] 100 Ceramic sintered body with vias 110 Porous materials 120 Ceramic molding 121 First ceramic molded body 122 Second ceramic molding 123 The third ceramic molding 125 Hole 127 Terminal hole 130 Beer 140 Sintered ceramics 150 Internal electrode 152 Second internal electrode 160 pellets 170 shaft 180 terminals 190 Base 192 wafer placement surface 200 Electrode embedding member

Claims

1. a base body formed of a ceramic sintered body; a plurality of internal electrodes embedded in a plurality of layers inside the substrate; a via embedded in the base and electrically connecting at least two of the plurality of internal electrodes, the via is formed of tungsten, molybdenum, or a material containing at least one of them; the relative density of the vias is 88% or more and 92% or less; The electrode-embedding member is characterized in that the via is formed in a columnar shape with a maximum diameter of 1.0 mm or more and a height of 1.0 mm or more.

2. An electrode-embedded member as described in Claim 1, characterized in that the via is formed in a columnar shape with a maximum diameter of 1.5 mm or more and a height of 3.0 mm or more.

Images