Joint structure

Abstract

To make it difficult for a connection member to come off from a ceramic member.SOLUTION: A wafer mounting table 10 includes a ceramic member 12 having a wafer mounting surface 12a, an RF electrode 14 embedded in the ceramic member 12 and shaped along the wafer mounting surface 12a, a metal connection member 16 buried so as to reach the RF electrode 14 from the surface of the ceramic member 12 opposite to the wafer mounting surface 12a, and a metal external current-carrying member 18 that is bonded to the surface of the connection member 16 that is exposed to the outside through a bonding layer 20. The surface of the connection member 16 has an arithmetic mean roughness Ra of 6 to 16 μm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a bonded structure. [Background technology]

[0002] Conventionally, a bonded structure has been known that includes a ceramic member, an electrode embedded in the ceramic member, a connecting member embedded in the ceramic member so as to reach the electrode, and an external current-carrying member bonded to the connecting member via a bonding layer. For example, Patent Document 1 discloses a ceramic heater 610 shown in FIG. 6. The ceramic heater 610 includes a ceramic member 612 having a heater element 614 embedded therein. A cylindrical hole 612c with a bottom is formed in a surface 612b of the ceramic member 612 opposite a wafer-mounting surface 612a of the ceramic member 612. A cylindrical connecting member 616 is embedded in the ceramic member 612 so as to extend from the bottom of the hole 612c to the heater element 614. An external current-carrying member 618 is bonded to the exposed surface of the connecting member 616 via a bonding layer 620. The ceramic heater 610 is used for performing CVD film formation or etching on a wafer using plasma. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2015 / 198892 Brochure Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the ceramic heater 610, if the connecting member 616 repeatedly undergoes thermal expansion due to an increase in plasma power or heater power, causing an overload on the external current-carrying member 618, there is a problem in that the external current-carrying member 618, together with the connecting member 616, comes off from the ceramic member 612.

[0005] The present invention has been made to solve such problems, and a main object of the present invention is to make it difficult for a connecting member to come off from a ceramic member. [Means for solving the problem]

[0006] The bonded structure of the present invention is a ceramic member having a wafer mounting surface; a buried electrode that is buried in the ceramic member and has a shape that conforms to the wafer mounting surface; a metal connection member embedded in the ceramic member so as to extend from a surface of the ceramic member opposite the wafer mounting surface to the embedded electrode; an external current-carrying member made of metal and bonded to an externally exposed surface of the connection member via a bonding layer; Equipped with The connecting member has a surface with an arithmetic mean roughness Ra of 6 to 16 μm. It is something.

[0007] In this bonded structure, the connecting member has a surface arithmetic mean roughness Ra of 6 to 16 μm. Therefore, even if an overload occurs in the external current-carrying member, the anchor effect makes it difficult for the external current-carrying member and the connecting member to come off from the ceramic member.

[0008] In the bonded structure of the present invention, the particles constituting the connecting member may have an average particle size of 4 to 8 μm. This allows for a better anchoring effect than when the average particle size is less than 4 μm. Here, the average particle size of the particles constituting the connecting member does not refer to the average particle size of the raw material powder used to produce the connecting member, but refers to the average particle size of the particles constituting the connecting member itself.

[0009] In the bonded structure of the present invention, the connecting member may be made of a porous metal having a porosity of 5 to 20%. This allows a connecting member having an arithmetic mean roughness Ra of 6 to 16 μm to be produced relatively easily. Such a connecting member is produced by powder metallurgy using a metal powder having an average particle size of 4 to 8 μm, for example.

[0010] In the bonded structure of the present invention, the ceramic member is Nitriding The ceramic member may be made of aluminum, and the connecting member may be made of Mo, W, or a Mo-W alloy. This makes it difficult for cracks to occur in the ceramic member because the difference in thermal expansion coefficient between the ceramic member and the connecting member is small.

[0011] In the bonded structure of the present invention, the external current-carrying member may have a tensile load resistance of 120 kgf or more. A large load is often applied to the external current-carrying member during the manufacture or use of the bonded structure, and therefore it is highly significant that the external current-carrying member has a tensile load resistance of 120 kgf or more. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a cross-sectional view of a main part of the wafer mounting table 10. [Figure 2] FIG. [Figure 3] Enlarged view of part A in Figure 1. [Figure 4] 5A to 5C are diagrams showing the manufacturing process of the connection member 16. [Figure 5] Manufacturing process diagram of wafer mounting table 10 [Figure 6] FIG. 6 is a cross-sectional view of a main part of a ceramic heater 610. DETAILED DESCRIPTION OF THE INVENTION

[0013] Next, a wafer mounting table 10, which is a preferred embodiment of the bonded structure of the present invention, will be described below. Fig. 1 is a cross-sectional view of a main part of the wafer mounting table 10, Fig. 2 is a perspective view of a connecting member 16, and Fig. 3 is an enlarged view of part A in Fig. 1. In this specification, the symbol "to" indicating a range of values ​​is used to mean that the values ​​before and after it are included as the lower and upper limits.

[0014] The wafer stage 10 (corresponding to the bonded structure of the present invention) is used to place a wafer on which etching, CVD, or the like is to be performed using plasma, and is installed in a vacuum chamber (not shown). The wafer stage 10 includes a ceramic member 12, an RF electrode (corresponding to the buried electrode of the present invention) 14, a connecting member 16, an external current-carrying member 18, and a guide member 22.

[0015] The ceramic member 12 is formed in a disk shape, with one surface serving as a wafer mounting surface 12a on which a wafer is placed. Although the wafer mounting surface 12a is shown facing downwards in FIG. 1, when the wafer mounting table 10 is actually used, the wafer mounting surface 12a should be facing upwards. A preferable material for the ceramic member 12 is, for example, aluminum nitride. A cylindrical hole 12c with a bottom is formed in a surface 12b of the ceramic member 12 opposite the wafer mounting surface 12a. The ceramic member 12 may have a diameter of 150 to 500 mm and a thickness of 0.5 to 30 mm, for example. The hole 12c may have a diameter of 5 to 15 mm and a depth of 5 to 25 mm, for example.

[0016] The RF electrode 14 is an electrode embedded in the ceramic member 12 and is a member shaped to fit the wafer mounting surface 12a, in this case a circular metal mesh. The RF electrode 14 is preferably made of, for example, tungsten, molybdenum, tantalum, platinum, or an alloy thereof. The metal mesh may have, for example, a wire diameter of 0.1 to 1.0 mm and 10 to 100 wires per inch. Alternatively, the RF electrode 14 may be formed by printing.

[0017] The connecting member 16 is a metal member embedded in the ceramic member 12 so as to extend from the bottom of the hole 12c to the RF electrode 14. The connecting member 16 is a cylindrical member having a first surface 16a, a second surface 16b, and a third surface 16c. The first surface 16a is the surface on the RF electrode 14 side and is a circular surface. The second surface 16b is the surface on the bonding layer 20 side and is a circular surface with the same shape as the first surface 16a. The second surface 16b is exposed to the hole 12c and is flush with the bottom surface of the hole 12c. The third surface 16c is a side surface of the cylinder. The connecting member 16 is made of a metallic porous material. Examples of the metal that can be used include Mo, W, and a Mo-W alloy.

[0018] The diameter L of the first surface 16a and the second surface 16b of the connecting member 16 is preferably 1 to 5 mm, and more preferably 2.5 to 3.5 mm. The height H of the connecting member 16 is preferably 1 to 5 mm, and more preferably 1 to 2 mm. The arithmetic mean roughness Ra of the first surface 16a, the second surface 16b, and the third surface 16c is preferably 6 to 16 μm. The average particle size of the metal particles constituting the connecting member 16 is preferably 4 to 8 μm. The porosity of the metal porous material constituting the connecting member 16 is preferably 5 to 20%.

[0019] The external current-carrying member 18 includes a first portion 18a joined to the connecting member 16 via a bonding layer 20, and a second portion 18b joined to the surface of the first portion 18a opposite the bonding surface of the connecting member 16 via an intermediate bonding portion 18c. The second portion 18b is made of a highly oxidation-resistant metal, taking into account its use in plasma or corrosive gas atmospheres. However, because highly oxidation-resistant metals generally have a large thermal expansion coefficient, directly bonding the second portion 18b to the connecting member 16 reduces the bonding strength due to the difference in thermal expansion between the two. Therefore, the second portion 18b is bonded to the connecting member 16 via the first portion 18a, which is made of a metal with a thermal expansion coefficient close to that of the connecting member 16. Preferred materials for the second portion 18b include pure nickel, nickel-based heat-resistant alloys, gold, platinum, silver, and alloys thereof. Preferred materials for the first portion 18a include molybdenum, tungsten, molybdenum-tungsten alloys, tungsten-copper-nickel alloys, and Kovar. The bonding layer 20 is formed by a brazing material. formation The brazing material is preferably a metal brazing material, such as an Au-Ni brazing material, an Al brazing material, or an Ag brazing material. The bonding layer 20 bonds the second surface 16b of the connection member 16 to the end face of the first portion 18a. The intermediate bonding portion 18c of the external current-carrying member 18 bonds the first portion 18a to the second portion 18b, and also fills the gap between the inner peripheral surface of the guide member 22 and the entire or part of the outer peripheral surface of the first portion 18a. Filled with The inner peripheral surface of the guide member 22 is connected to a part of the outer peripheral surface of the second portion 18b. Therefore, the first portion 18a is isolated from the surrounding atmosphere by the intermediate bonding portion 18c. The intermediate bonding portion 18c may also be made of the same material as the bonding layer 20. The first portion 18a may have a diameter of 3 to 6 mm and a height of 2 to 5 mm, and the second portion 18b may have a diameter of 3 to 6 mm and an optional height.

[0020] The guide member 22 is a cylindrical member that surrounds at least the periphery of the first part 18a of the external power supply member 18, and is formed of a material having higher oxidation resistance than the first part 18a. The inner diameter of this guide member 22 is larger than the outer diameters of the first part 18a and the second part 18b (excluding the flange), the outer diameter is smaller than the diameter of the hole 12c, and the height is higher than the height of the first part 18a. The end face of the guide member 22 that faces the bottom surface of the hole 12c is joined to the connection member 16, the external power supply member 18, and the ceramic member 12 via the joining layer 20. As the material of the guide member 22, those exemplified as the material of the second part 18b of the external power supply member 18 can be used. Note that, as shown in FIG. 1, the end face of the guide member 22 may be joined to the bottom surface of hole 12c via the joining layer 20, or hole may be separated from the bottom surface of 12c.

[0021] Next, a method for manufacturing the wafer mounting table 10 will be described using FIGS. 4 and 5. First, the connection member 16 is prepared. The connection member 16 is manufactured by, for example, powder metallurgy as follows. That is, the metal powder 97 and the resin powder 98 are mixed. Thereby, the mixture 96 is obtained (FIG. 4A). Next, the mixture 96 is filled into a mold and compression molded. Thereby, the molded body 86 is obtained (FIG. 4B). Next, the molded body 86 is heated at 400 to 500 ° C. for about 1 hour to burn and remove the resin contained in the molded body 86. Then, the shape molded body 86 is heated at 1300 to 1800 ° C. for about 1 hour to sinter the metal powder 97. Thereby, the connection member 16 formed of a metal porous material is obtained (FIG. 4C). Here, by appropriately changing the average particle diameter, pressure, temperature during heating, and heating time of the metal powder 97, a connection member 16 having a desired arithmetic mean roughness Ra, average particle diameter, and porosity can be obtained. Note that the average particle diameter of the particles constituting the connection member 16 is substantially the same as the average particle diameter of the metal powder 97.

[0022] Next, the ceramic raw material powder is press-molded into a disk to produce a compact 62 (FIG. 5A). An RF electrode 14 made of a circular metal mesh and a connecting member 16 are embedded in this compact 62. This compact 62 is fired in a hot press furnace, an atmospheric pressure furnace, or the like, whereby the compact 62 is sintered to form a ceramic member 12 (FIG. 5B). The obtained ceramic member 12 is then machined to a predetermined size.

[0023] Next, the surface 12b of the ceramic member 12 opposite to the wafer mounting surface 12a is ground to form a cylindrical hole 12c with a bottom (FIG. 5C). At this time, the second surface 16b of the connection member 16 is exposed in the hole 12c, and the processing is performed so that the bottom surface of the hole 12c and the second surface 16b of the connection member 16 are flush with each other.

[0024] Next, a brazing material 72 that will become the bonding layer 20 is laid on the bottom surface of the hole 12c, and the first portion 18a of the external current-carrying member 18, a brazing material 78c that will become the intermediate bonding portion 18c, the guide member 22, and the second portion 18b of the external current-carrying member 18 are stacked on top of it in this order to obtain a stacked body (FIG. 5D). This stacked body is heated under non-oxidizing conditions to melt the brazing materials 72 and 78c and then solidify them, thereby obtaining the wafer mounting table 10 shown in FIG. 1. Non-oxidizing conditions refer to a vacuum or a non-oxidizing atmosphere (e.g., an inert atmosphere such as an argon atmosphere or a nitrogen atmosphere).

[0025] In the wafer mounting table 10 described above, the connecting member 16 has a surface arithmetic mean roughness Ra of 6 to 16 μm. Therefore, even if an overload occurs to the external current-carrying member 18, the external current-carrying member 18, together with the connecting member 16, is less likely to come off from the ceramic member 12 due to the anchor effect.

[0026] Furthermore, in the wafer mounting table 10, the average particle size of the particles constituting the connecting member 16 is preferably 4 to 8 μm, which provides a better anchoring effect than when the average particle size is less than 4 μm.

[0027] Furthermore, in the wafer mounting table 10, the connecting member 16 is preferably made of a porous metal body with a porosity of 5 to 20%, which makes it possible to relatively easily produce a connecting member 16 with a surface arithmetic mean roughness Ra of 6 to 16 μm.

[0028] Furthermore, in the wafer mounting table 10, the ceramic member 12 is Nitriding The ceramic member 12 is made of aluminum, and the connecting member 16 is made of Mo, W, or a Mo-W alloy. This makes it difficult for cracks to occur in the ceramic member 12. This is because the difference in thermal expansion coefficient between the ceramic member 12 and the connecting member 16 is small.

[0029] It goes without saying that the present invention is not limited to the above-described embodiment and can be embodied in various forms as long as they fall within the technical scope of the present invention. The present invention is suitable for a structure having a connecting member 16 that is provided between an electrode embedded in the ceramic member 12 and an external current-carrying member 18 and is embedded in the ceramic member 12.

[0030] For example, in the above-described embodiment, the connecting member 16 is made of a metallic porous material, but is not limited to this. In the above-described embodiment, the connecting member 16 may be made of a dense metallic material.

[0031] In the above-described embodiment, the connecting member 16 may have a corner portion between the first surface 16a and the third surface 16c, the corner portion having a predetermined radius of curvature R. This can prevent cracks from occurring in the ceramic member 12 around the corner portion. In this case, the radius of curvature R is preferably 0.3 to 1.5 mm.

[0032] In the above-described embodiment, the RF electrode 14 is embedded in the ceramic member 12. However, instead of or in addition to the RF electrode 14, an electrostatic electrode may be embedded, a heater element may be embedded, or both an electrostatic electrode and a heater element may be embedded.

[0033] A cylindrical shaft made of the same material as the ceramic member 12 may be integrated with the ceramic member 12 on the surface 12b opposite the wafer mounting surface 12a of the wafer mounting table 10 in the above-described embodiment. In this case, the external current-carrying member 18 and the like are disposed inside the hollow shaft. To manufacture the shaft, for example, ceramic raw material powder is molded using a mold by CIP, sintered at a predetermined temperature in an atmospheric pressure furnace, and then machined to have predetermined dimensions after sintering. To integrate the shaft and the ceramic member 12, for example, the end face of the shaft may be butted against the surface 12b of the ceramic member 12, and the two may be joined and integrated by heating to a predetermined temperature.

[0034] In the above-described embodiment, the flange of the second part 18b of the external current-carrying member 18 and the end face of the guide member 22 are not joined together, but the gap between the two may be filled with a joining layer (for example, made of the same material as the joining layer 20) and the two may be joined together via this joining layer. [Example]

[0035] Examples of the present invention will be described below. Of the following Experimental Examples 1 to 9, Experimental Examples 1 to 5 correspond to Examples of the present invention, and Experimental Examples 6 to 9 correspond to Comparative Examples. Note that the following Examples do not limit the present invention in any way.

[0036] [Experimental Example 1] 1. Preparation of connecting member 16 (1) Preparation of the connecting member 16 The connecting member 16 was produced according to the manufacturing procedure of Fig. 4. That is, 91 mass % of Mo powder having an average particle size of 4 µm as the metal powder 97 and 9 mass % of the resin powder 98 were mixed. thing 96 was prepared. thing 96 is filled into a mold and pressure-molded to form a cylindrical shape. shape The body 86 was produced. shape Body 86 was heated at 500°C for 1 hour to form shapeThe resin contained in body 86 was burned and removed. Then, compact 86 was heated at 1800°C for 1 hour to sinter metal powder 97, thereby obtaining cylindrical connecting member 16. The size of the obtained connecting member 16 was 3 mm in diameter at the top and bottom, and 1.5 mm in height.

[0037] (2) Measurement of the arithmetic mean roughness Ra of the surface The value measured using an optical interferometer according to a method in accordance with JIS B 0601:2013 was taken as the arithmetic mean roughness Ra of the surfaces (first surface 16a, second surface 16b, and third surface 16c) of connecting member 16. As a result, the arithmetic mean roughness Ra of the surfaces was 6 μm.

[0038] (3) Measurement of average particle size The average particle size of the particles constituting the connecting member 16 was measured as follows. That is, first, the connecting member 16 was cut, and an SEM image (magnification 3000 times) of the cut surface was obtained. Then, a straight line was drawn on the image, and the lengths of the line segments crossing 40 particles were measured, and the average length of these was calculated. The average particle size As a result, the average particle size of the particles constituting the connection member 16 was 4 μm.

[0039] (4) Porosity measurement The porosity of the connecting member 16 was measured as follows. First, a cut surface of the connecting member 16 was filled with resin and polished to prepare a sample for observation. Next, an SEM image (1000x magnification) of the cut surface was taken. Next, the obtained image was analyzed, and a threshold was determined using discriminant analysis (Otsu's binarization) from the brightness distribution of the brightness data of the pixels in the image. Then, based on the determined threshold, each pixel in the image was binarized into an object portion and a pore portion, and the area of ​​the object portion and the area of ​​the pore portion were calculated. Then, the ratio of the area of ​​the pore portion to the total area (the total area of ​​the object portion and the pore portion) was calculated as the porosity. As a result, the porosity of the connecting member 16 was 5%.

[0040] 2. Fabrication of the wafer mounting table (1) Preparation of the molded body 62 Three wafer support table 10 samples were manufactured according to the manufacturing procedure shown in Figure 5. First, the RF electrode 14 and the connecting member 16 were embedded in a powder mixture of aluminum nitride powder and a sintering aid, and then a compact 62 was manufactured by uniaxially pressing. A molybdenum wire mesh was used as the RF electrode 14. This wire mesh was made by weaving molybdenum wires with a diameter of 0.12 mm at a density of 50 wires per inch.

[0041] (2) Firing Next, this molded body 62 was placed in a mold, sealed in carbon foil, and fired by a hot press method to obtain the ceramic member 12. After firing, the ceramic member 12 was processed to have a diameter of 200 mm and a thickness of 8 mm.

[0042] (3) Formation of hole 12c Next, a cylindrical hole 12c with a bottom was formed by a machining center on the surface 12b of the ceramic member 12 opposite to the wafer mounting surface 12a. The hole 12c had a diameter of 9 mm (opening diameter 12 mm) and a depth of 4.5 mm. 16 The second surface 16b of the hole 12c is exposed to the hole 12c, and the bottom surface of the hole 12c and the connecting member 16 The first surface 16b was machined so as to be flush with the first surface 16a.

[0043] (4) Joining of external current-carrying member 18 Next, a brazing material 72 made of Au-Ni was laid on the bottom surface of the hole 12c, and the first portion 18a of the external current-carrying member 18, the brazing material 78c made of Au-Ni, the guide member 22 made of nickel (purity 99% or higher), and the second portion 18b of the external current-carrying member 18 were stacked on top of it in this order to obtain a stack. The first portion 18a was made of Kovar and had a diameter of 4 mm and a height of 3 mm, and the second portion 18b was made of nickel (purity 99% or higher) and had a diameter of 4 mm (flange diameter 8 mm) and a height of 60 mm. This stack was heated at 960 to 1100°C for 10 minutes in an inert atmosphere to obtain the wafer mounting table 10 shown in FIG. 1.

[0044] [Experimental Examples 2-9] In Experimental Examples 2 to 9, three wafer mounting tables 10 were fabricated in each case in the same manner as in Experimental Example 1, except that connecting members 16 were prepared so that the arithmetic mean surface roughness Ra, average particle size, and porosity were the values ​​shown in Table 1.

[0045] [Table 1]

[0046] [Evaluation of wafer mounting table] (1) Whether or not there was any damage during manufacturing The wafer mounting tables 10 fabricated in Experimental Examples 1 to 9 were checked for damage during manufacturing. Three wafer mounting tables 10 for each Experimental Example were checked for damage during manufacturing. Specifically, immediately after the ceramic members 12 were manufactured by sintering the compacts 62, it was checked for cracks in the ceramic members 12, and those that had cracks were determined to have been damaged during manufacturing.

[0047] (2) Tensile load resistance The tensile load resistance of the wafer mounting tables 10 fabricated in Experimental Examples 1 to 9 was confirmed. The tensile load resistance of three wafer mounting tables 10 was confirmed for each Experimental Example. The tensile load resistance was confirmed as follows. Specifically, a male thread was formed at the free end of the external current-carrying member 18, and the female thread of a cylindrical connecting jig was screwed onto the male thread. The jig was then left at 700°C in an oxygen atmosphere for 800 hours. The wafer mounting surface 12a of the ceramic member 12 was then fixed to the workpiece mounting surface. In this state, the connecting jig was pulled using a tensile tester while applying a vertical load varying from 1 to 120 kgf. The tensile load resistance of a case in which the connecting member 16 did not come off the ceramic member 12 even when pulled with a load of 120 kgf was defined as 120 kgf or more. The tensile load resistance of a case in which the connecting member 16, together with the external current-carrying member 18, came off the ceramic member 12 was defined as the tensile load at which the connecting member 16 came off the ceramic member 12.

[0048] (3) Judgment Using the method described above, we checked for damage during manufacturing and the tensile load resistance. Products with no damage during manufacturing and a tensile load resistance of 120 kgf or more were judged as OK. On the other hand, products with damage during manufacturing or a tensile load resistance of less than 120 kgf were judged as NG.

[0049] In Experimental Examples 1 to 5 (three units per experiment), in which the arithmetic mean roughness Ra of the surface of the connecting member 16 was 6 to 16 μm, none of the units suffered breakage during manufacturing and had a tensile load resistance of 120 kgf or more. In Experimental Examples 1 to 5, the average particle size of the particles constituting the connecting member 16 was 4 to 8 μm.

[0050] On the other hand, in Experimental Examples 6 to 8, in which the arithmetic mean roughness Ra of the surface was less than 6 μm, there was no breakage during manufacturing, but the tensile load resistance was less than 120 kgf. In Experimental Examples 6 to 8, the average particle size of the particles constituting the bonding members 16 was 3 μm, and the porosity of the connecting members 16 was less than 5%. Furthermore, in Experimental Example 9, in which the arithmetic mean roughness Ra of the surface was greater than 16 μm, there was breakage during manufacturing, and the tensile load resistance was less than 120 kgf. In Experimental Example 9, the average particle size of the particles constituting the bonding members 16 was 10 μm, and the porosity of the connecting members 16 was 24%. Note that in Experimental Example 6, the tensile load resistance was expressed as a predetermined numerical range using "to" because the tensile load resistance varied among the three wafer mounting tables produced in Experimental Example 6. The same applies to Experimental Examples 7 to 9. [Explanation of symbols]

[0051] 10 wafer mounting table, 12 ceramic member, 12a wafer mounting surface, 12b surface, 12c hole, 14 RF electrode, 16 connecting member, 16a first surface, 16b second surface , th3 surface, 16c third surface, 18 external current-carrying member, 18a first part, 18b second part, 18c intermediate bonding portion, 20 bonding layer, 22 guide member, 62 molded body, 72 brazing material, 78c brazing material, 86 molded body, 96 mixture, 97 metal powder, 98 resin powder, 610 ceramic heater, 612 ceramic member, 612a wafer mounting surface, 612b surface, 612c hole, 614 heater element, 616 connecting member, 618 external current-carrying member, 620 bonding layer.

Claims

1. a ceramic member having a wafer mounting surface; a buried electrode that is buried in the ceramic member and has a shape that conforms to the wafer mounting surface; a metal connection member embedded in the ceramic member so as to extend from a surface of the ceramic member opposite the wafer mounting surface to the embedded electrode; an external current-carrying member made of metal and bonded to an externally exposed surface of the connection member via a bonding layer; Equipped with the connecting member is made of a porous metal body having a surface arithmetic mean roughness Ra of 6 to 16 μm and a porosity of 5 to 20%, The connecting member is a member having a first surface which is a circular surface on one side of the buried electrode, a second surface which is a circular surface on the other side of the bonding layer, and a third surface which is a side surface, and has a corner portion with a predetermined radius of curvature between the first surface and the third surface. bonded structure.

2. The average particle size of the particles constituting the connecting member is 4 to 8 μm. The bonded structure according to claim 1 .

3. the ceramic member is made of aluminum nitride, The connecting member is made of Mo, W or a Mo-W alloy. The bonded structure according to claim 1 or 2.

4. The tensile load resistance of the external current-carrying member is 120 kgf or more. The bonded structure according to any one of claims 1 to 3.

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