JP2023073194A - Wafer mount table - Google Patents

Abstract

To fasten a wafer mount table including a fragile cooling base material onto an installation board without a trouble.SOLUTION: A wafer mount table 10 includes an alumina base material 20, a cooling base material 30, and an extendable female screw member 38. The alumina base material 20 includes a wafer mount surface 22a on an upper surface thereof, and incorporates an electrode 26. The cooling base material 30 is bonded to a lower surface of the alumina base material 20 and has a coolant passage 32 formed internally. The female screw member 38 is housed in a housing hole 36 that opens at a lower surface of the cooling base material 30 in a state in which the axial rotation is restricted and in a state of being engaged with an engagement part of the housing hole 36. The female screw member 38 can be screwed with a male screw of a bolt 98 inserted from a lower surface side of the cooling base material 30.SELECTED DRAWING: Figure 1

Description

The present invention relates to a wafer mounting table.

2. Description of the Related Art Conventionally, there has been known a wafer mounting table in which a ceramic base material containing electrodes and a cooling base material having coolant flow paths formed therein are bonded via an adhesive. Patent Literature 1 describes an example in which such a wafer mounting table is placed on a mounting plate and fixed with screws. Specifically, a female screw hole is provided on the lower surface of the cooling base material, and a male screw of a bolt inserted from below into a screw insertion hole vertically penetrating the installation plate is screwed into the female screw hole. .

JP 2014-150104 A

However, when a female screw hole is provided in the lower surface of the cooling base material and a male thread of a bolt inserted through the installation plate is screwed, no problem occurs if the material of the cooling base material is a ductile material (for example, aluminum). Problems arise with brittle materials (eg metal matrix composites). Specifically, since the female screw hole of the cooling substrate is locally pulled downward with a large force by the bolt, there is a risk of cracking if the material is not ductile.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and its main object is to enable a wafer mounting table provided with a fragile cooling base material to be fastened to a mounting plate without hindrance.

[1] The wafer mounting table of the present invention is
an alumina base material having a wafer mounting surface on its upper surface and containing an electrode;
a brittle cooling substrate bonded to the lower surface of the alumina substrate;
A ductile coupling member having a male screw portion or a female screw portion, which is accommodated in a storage hole opening to the lower surface of the cooling base material in a state in which rotation of the shaft is restricted and in a state in which the engaging portion of the storage hole is engaged. and,
is provided.

In this wafer mounting table, the coupling member having the male or female screw portion is engaged with the engaging portion of the housing hole in a state where the shaft rotation is restricted in the housing hole opened to the lower surface of the cooling base. is stored in Since the coupling member is restricted in its axial rotation, it can be screwed into a coupled member having a female screw portion or a male screw portion arranged on the lower surface side of the cooling base material. Further, even if the connecting member is pulled toward the mounting plate by the member to be connected provided on the mounting plate in a state of being engaged with the engaging portion of the housing hole, the connecting member has ductility and is therefore not easily broken. Therefore, the wafer mounting table having the brittle cooling base material can be fastened to the mounting plate without any trouble.

In this specification, the present invention may be described using terms such as up and down, left and right, front and back, but up and down, left and right, and front and back are merely relative positional relationships. Therefore, when the orientation of the wafer table is changed, up and down may become left and right, or left and right may become up and down. Such cases are also included in the technical scope of the present invention.

[2] In the wafer mounting table described above (the wafer mounting table described in [1] above), the connecting member has the female screw portion and is a male screw of a bolt inserted from the lower surface side of the cooling base. It may be a member that can be screwed together.

[3] In the wafer mounting table described above (the wafer mounting table described in [1] or [2] above), the cooling base may be made of a composite material of metal and ceramic or an alumina material. Since composite materials of metal and ceramics and alumina materials are brittle materials, the application of the present invention is highly significant. For example, when using a composite material of metal and ceramic, it is preferable to use a composite material having a thermal expansion coefficient equivalent to that of alumina.

[4] In the wafer mounting table described above (the wafer mounting table according to any one of [1] to [3]), the engaging portion is a step portion or an inclined portion provided on the inner peripheral surface of the storage hole. The coupling member may have an engaged portion that engages with the engaging portion to prevent the coupling member from falling out of the housing hole. In this way, the engaging portion and the engaged portion can be produced relatively easily. For example, if the engaging portion is a stepped portion, the coupling member may be provided with an engaged portion that is caught by the stepped portion. Further, when the engaging portion is an inclined portion, the coupling member may be provided with an inclined surface corresponding to the inclined portion as the engaged portion.

[5] In the above-described wafer mounting table (the wafer mounting table according to any one of [1] to [4]), when the coupling member tries to rotate, it hits the wall of the housing hole and is restricted from rotating. It may be In this way, axial rotation of the coupling member can be restricted with a relatively simple configuration.

[6] In the wafer mounting table described above (the wafer mounting table according to any one of [1] to [5] above), the cooling base material has a coolant channel therein, and the storage hole is , and may be provided in a region of the cooling substrate that is lower than the bottom surface of the coolant channel. In this way, the accommodation hole does not interfere with the coolant flow path, so that the freedom of design of the coolant flow path is not compromised.

[7] In the wafer mounting table described above (the wafer mounting table according to any one of [1] to [6]), the connecting member is not bonded to the cooling base material in the storage hole and is free. It may be stored in any condition. This saves time and effort because it is only necessary to insert the connecting member into the housing hole.

[8] In the wafer mounting table described above (the wafer mounting table according to any one of [1] to [7] above), the bonding member includes a stress buffering member having a Young's modulus lower than that of the bonding member. It may be engaged with the engaging portion. With this configuration, even if the connecting member is pulled toward the mounting plate by the member to be connected provided on the mounting plate, the stress buffering member intervenes between the connecting member and the engaging portion, so that the stress is relieved. Easy to disperse.

[9] In the wafer mounting table described above (the wafer mounting table according to any one of [1] to [8]), a gap between the coupling member and the housing hole may be filled with a filler. . By doing so, the heat conduction is better than when the gap between the coupling member and the housing hole is a space. Therefore, the uniformity of the temperature of the wafer is improved.

[10] In the wafer mounting table described above (the wafer mounting table according to any one of [1] to [9]), the storage hole includes a first storage portion for storing the coupling member, and a second storage portion provided so as to reach the lower surface of the cooling base material, and the engaging portion is located at the joint between the first storage portion and the second storage portion. It may be a stepped surface provided.

[11] In the wafer mounting table described above (the wafer mounting table described in [10] above), the first storage part may open to the upper surface of the cooling base, and the ceramic base and the cooling The opening surface may be covered with a bonding layer that bonds to the substrate. In this way, the first storage portion can be manufactured relatively easily compared to the case where the first storage portion is built inside the cooling base material. In such a structure, since it is necessary to provide a coolant channel (or coolant channel groove) avoiding the storage hole, the temperature uniformity tends to deteriorate in the vicinity of the wafer directly above the storage hole. In order to suppress such a decrease in heat uniformity, it is preferable to fill the gap between the connecting member and the housing hole with a filler. By doing so, the heat conduction around the housing hole is improved, so that the deterioration of the heat uniformity can be suppressed.

[12] In the wafer mounting table described above (the wafer mounting table according to [10] or [11]), the width of the annular region where the step surface and the coupling member are in direct or indirect contact is 3 mm or more. is preferred. If the width of such an annular region is 3 mm or more, even if the coupling member is pulled toward the installation plate by a member to be coupled provided on the installation plate, the step surface and the coupling member are in direct or indirect contact. Since the annular area is wide, the stress is easily distributed.

FIG. 4 is a longitudinal sectional view of the wafer mounting table 10 installed in the chamber 94; FIG. 2 is a plan view of the wafer mounting table 10; FIG. 3 is an enlarged cross-sectional view showing the surroundings of a housing hole 36 and a female screw member 38; FIG. 4 is a top cross-sectional view of a cross section of the cooling base material 30 cut horizontally along the ceiling surface of the housing hole 36; FIG. 3 is an enlarged cross-sectional view showing a coolant supply path 321 and a coolant discharge path 322; 4A to 4C are manufacturing process diagrams of the wafer mounting table 10; FIG. 11 is an enlarged cross-sectional view showing another example of the housing hole 36 and the female screw member 38; FIG. 11 is an enlarged cross-sectional view showing another example of the housing hole 36 and the female screw member 38; FIG. 4 is an enlarged cross-sectional view when a male screw member 80 is employed as a coupling member; FIG. 4 is a vertical cross-sectional view of a wafer mounting table 510 installed in the chamber 94; FIG. 4 is an enlarged cross-sectional view showing the surroundings of a housing hole 536 and a female screw member 538; 4A to 4C are manufacturing process diagrams of the wafer mounting table 510. FIG. Sectional drawing for size description of the storage hole 536 and the internal thread member 538. FIG. FIG. 10 is an explanatory view when a triangular prism-shaped nut is adopted as the female screw member 538; FIG. 5 is a longitudinal sectional view of another example of the wafer table 510;

[First Embodiment]
Preferred embodiments of the invention are described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of the wafer mounting table 10 installed in the chamber 94 (a sectional view taken along a plane including the central axis of the wafer mounting table 10), FIG. 2 is a plan view of the wafer mounting table 10, and FIG. 4 is an enlarged cross-sectional view showing the surroundings of the storage hole 36 and the female screw member 38, and FIG.

The wafer mounting table 10 is used to perform CVD, etching, etc. on the wafer W using plasma, and is fixed to a mounting plate 96 provided inside a chamber 94 for semiconductor processing. The wafer mounting table 10 includes an alumina substrate 20 , a cooling substrate 30 and a metal bonding layer 40 .

The alumina base material 20 has an outer peripheral portion 24 having an annular focus ring mounting surface 24a on the outer periphery of a central portion 22 having a circular wafer mounting surface 22a. Hereinafter, the focus ring may be abbreviated as "FR". A wafer W is mounted on the wafer mounting surface 22a, and a focus ring 78 is mounted on the FR mounting surface 24a. The FR mounting surface 24a is one step lower than the wafer mounting surface 22a.

The central portion 22 of the alumina base material 20 incorporates a wafer chucking electrode 26 on the side closer to the wafer mounting surface 22a. The wafer chucking electrode 26 is made of a material containing W, Mo, WC, MoC, or the like, for example. The wafer chucking electrode 26 is a disc-shaped or mesh-shaped unipolar electrostatic chucking electrode. A layer of the alumina base material 20 above the wafer chucking electrode 26 functions as a dielectric layer. A wafer chucking DC power source 52 is connected to the wafer chucking electrode 26 via a power supply terminal 54 . The power supply terminal 54 passes through an insulating tube 55 arranged in a through-hole vertically penetrating the cooling base material 30 and the metal bonding layer 40, and extends from the lower surface of the alumina base material 20 to the wafer adsorption electrode 26. is provided. A low-pass filter (LPF) 53 is provided between the DC power supply 52 for wafer attraction and the electrode 26 for wafer attraction.

The cooling base material 30 is a disk member. As a material for the cooling base material 30, a composite material of metal and ceramic is preferable. Such composites include metal matrix composites (also called metal matrix composites (MMC)) and ceramic matrix composites (also called ceramic matrix composites (CMC)). Such composite materials are a type of brittle material. The cooling base material 30 has coolant channels 32 in which coolant can circulate. The coolant channel 32 is connected to a coolant supply channel and a coolant discharge channel (not shown), and the coolant discharged from the coolant discharge channel is returned to the coolant supply channel after its temperature is adjusted. The coolant flowing through the coolant channel 32 is preferably liquid and preferably electrically insulating. Examples of electrically insulating liquids include fluorine-based inert liquids. Composite materials of metal and ceramic include materials containing Si, SiC and Ti, materials in which SiC porous bodies are impregnated with Al and/or Si, and composite materials of Al ₂ O ₃ and TiC. A material containing Si, SiC and Ti is referred to as SiSiCTi, a material obtained by impregnating a porous SiC body with Al is referred to as AlSiC, and a material obtained by impregnating a porous SiC body with Si is referred to as SiSiC. As the composite material used for the cooling base material 30, AlSiC, SiSiCTi, etc., having a coefficient of thermal expansion close to that of alumina are preferable. Cooling substrate 30 is connected to RF power supply 62 via power supply terminal 64 . A high pass filter (HPF) 63 is arranged between the cooling substrate 30 and the RF power supply 62 . The cooling base material 30 has a flange portion 34 on the lower surface side thereof, which is used for clamping the wafer mounting table 10 to the mounting plate 96 .

A plurality of housing holes 36 are provided in the cooling base material 30, and female screw members 38 (coupling members) are housed in the housing holes 36. As shown in FIG. A plurality of storage holes 36 are provided in a region of the cooling substrate 30 that is lower than the bottom surface 32 a of the coolant channel 32 . A plurality of housing holes 36 (for example, 6 or 8) are provided at regular intervals along a concentric circle (for example, a circle of 1/2 or 1/3 the diameter of the wafer W) of the cooling substrate 30 . That is, the plurality of storage holes 36 are provided in an area near the center of the wafer mounting table 10, as shown in FIG. The storage holes 36 are opened in the lower surface of the cooling base material 30, as shown in FIG. The storage hole 36 includes a first storage portion 36a, a second storage portion 36b, and a stepped portion 36c. The first storage portion 36 a is a rectangular parallelepiped space provided above the storage hole 36 . The second storage portion 36 b is a cylindrical space provided below the storage hole 36 . The stepped portion 36c is a joint portion between the first storage portion 36a and the second storage portion 36b. A female screw member 38 is accommodated in the accommodation hole 36 . The female screw member 38 has a rectangular parallelepiped head portion 38a and a cylindrical portion 38b provided on the lower surface of the head portion 38a, and the inner peripheral surface of the cylindrical portion 38b is threaded. A head portion 38 a of the female screw member 38 is housed in a first housing portion 36 a of the housing hole 36 . Since the lower surface of the head portion 38 a of the female screw member 38 is engaged with the stepped portion 36 c of the housing hole 36 , the female screw member 38 does not fall out of the housing hole 36 . The cylindrical portion 38b of the female screw member 38 is housed in the second housing portion 36b of the housing hole 36. As shown in FIG. When the female screw member 38 tries to rotate about its axis, as shown in FIG. 4, the head portion 38a hits the side wall of the first housing portion 36a and its rotation is restricted. The female screw member 38 is made of a ductile material (eg Ti, Mo, W, etc.).

The metal bonding layer 40 bonds the lower surface of the alumina base 20 and the upper surface of the cooling base 30 . The metal bonding layer 40 may be, for example, a layer made of solder or brazing metal. The metal bonding layer 40 is formed by TCB (Thermal Compression Bonding), for example. TCB is a known method in which a metal bonding material is sandwiched between two members to be bonded, and the two members are pressure-bonded while being heated to a temperature below the solidus temperature of the metal bonding material.

The side surface of the outer peripheral portion 24 of the alumina base material 20 , the outer periphery of the metal bonding layer 40 and the side surface of the cooling base material 30 are covered with an insulating film 42 . As the insulating film 42, for example, a sprayed film such as alumina or yttria can be used.

Such a wafer mounting table 10 is mounted via a seal ring 76 on a mounting plate 96 provided inside the chamber 94 . The seal ring 76 is made of metal or resin, and has an outer diameter slightly smaller than the outer diameter of the cooling base material 30 . The outer peripheral area of the wafer mounting table 10 is attached to the installation plate 96 using the clamp members 70 . The clamp member 70 is an annular member having a substantially inverted L-shaped cross section, and has an inner peripheral stepped surface 70a. With the inner peripheral stepped surface 70a of the clamp member 70 placed on the flange portion 34 of the cooling substrate 30 of the wafer mounting table 10, a bolt 72 is inserted from the upper surface of the clamp member 70 and provided on the upper surface of the installation plate 96. is screwed into a threaded hole. The bolts 72 are attached at a plurality of locations (for example, 8 or 12 locations) provided at equal intervals along the circumferential direction of the clamp member 70 . The clamp member 70 and the bolt 72 may be made of an insulating material, or may be made of a conductive material (such as metal). Also, the central region of the wafer mounting table 10 is attached to the installation plate 96 using bolts 98 (bonded members). As shown in FIG. 3, the leg portion of the bolt 98 is provided with a male thread 98a. The bolt 98 is inserted from the lower surface of the installation plate 96 through a through hole 97 provided in the installation plate 96 at a position facing the storage hole 36 , and the male screw 98 a is screwed into the female screw member 38 in the storage hole 36 . be. The through hole 97 has a small diameter at the top and a large diameter at the bottom, and has a stepped portion 97a between the top and bottom. The head of the bolt 98 is hooked on the stepped portion 97 a of the through hole 97 . Since the female screw member 38 is housed in the first housing portion 36 a of the housing hole 36 with its axial rotation restricted, the bolt 98 can be screwed into the female screw member 38 . When the bolt 98 is screwed into the female screw member 38 , the female screw member 38 is pulled toward the mounting plate 96 with the head portion 38 a engaged with the stepped portion 36 c of the housing hole 36 .

When the wafer mounting table 10 is used, the wafer mounting surface 22a side of the alumina substrate 20 is in a vacuum state, and the lower surface side of the cooling substrate 30 is in the air. Further, when the wafer W is processed with high-power plasma, the temperature on the wafer mounting surface 22a side of the alumina base material 20 is high, and the temperature on the lower surface side of the alumina base material 20 is low due to cooling. The table 10 tends to be convex upward. However, in this embodiment, since the central region of the wafer mounting table 10 is fixed by the bolts 98, it is possible to prevent the wafer mounting table 10 from protruding upward. Further, even if a seal ring (not shown) is arranged between the central region of the lower surface of the cooling base material 30 and the upper surface of the mounting plate 96, the central region of the wafer mounting table 10 is fixed by the bolts 98. The seal ring remains firmly crushed.

For example, as shown in FIG. 5, the coolant supply path 321 consists of a first supply path 32p passing through the installation plate 96 and a coolant supply seal ring 32q disposed between the installation plate 96 and the cooling substrate 30. and a second supply path 32r extending from the lower surface of the cooling base material 30 to the coolant flow path 32. As shown in FIG. The coolant discharge path 322 consists of a first discharge path 32s extending from the coolant flow path 32 to the lower surface of the cooling base material 30, and the inside of a coolant discharge seal ring 32t disposed between the cooling base material 30 and the installation plate 96. , and a second discharge passage 32u that passes through the installation plate 96 and reaches the lower surface of the installation plate 96. As shown in FIG. In this case, the female screw member 38 in the housing hole 36 and the bolt 98 are screwed together to fix the central region of the wafer mounting table 10, so that these seal rings 32q and 32t are firmly crushed. maintained in condition. Therefore, the seal rings 32q, 32t can sufficiently ensure sealing performance.

Next, an example of manufacturing the wafer mounting table 10 will be described with reference to FIG. 6A and 6B are manufacturing process diagrams of the wafer mounting table 10. FIG. First, a disc-shaped alumina sintered body 120, which is the source of the alumina base material 20, is produced by hot-press firing a molded body of alumina powder (FIG. 6A). The alumina sintered body 120 incorporates the wafer adsorption electrode 26 . Next, a hole 27 is formed from the lower surface of the alumina sintered body 120 to the wafer adsorption electrode 26 (FIG. 6B), and the power supply terminal 54 is inserted into the hole 27 to join the power supply terminal 54 and the wafer adsorption electrode 26 together. (Fig. 6C).

In parallel, three MMC disk members 131, 133, 135 are fabricated (FIG. 6D). A groove 132 is formed on the lower surface of the upper MMC disk member 131, and a stepped hole 136 is formed on the lower MMC disk member 135, which will eventually become the storage hole 36. Furthermore, through holes are formed in the three MMC disk members 131, 133, and 135 so as to extend vertically (FIG. 6E). These through holes eventually become holes through which the power supply terminals 54 are inserted. When the alumina sintered body 120 is made of alumina, the MMC disk members 131, 133, 135 are preferably made of SiSiCTi or AlSiC. This is because the thermal expansion coefficient of alumina is approximately the same as that of SiSiCTi and AlSiC.

A disk member made of SiSiCTi can be produced, for example, as follows. First, silicon carbide, metal Si, and metal Ti are mixed to prepare a powder mixture. Next, the obtained powder mixture is uniaxially pressed to form a disk-shaped molded body, and the molded body is hot-press sintered in an inert atmosphere to obtain a disk member made of SiSiCTi. .

Next, the female screw member 38 is accommodated in the stepped hole 136 of the MMC disk member 135 on the lower side. Then, a metal bonding material is placed between the lower surface of the upper MMC disk member 131 and the upper surface of the middle MMC disk member 133, and the lower surface of the middle MMC disk member 133 and the lower MMC disk member are arranged. 135 and the upper surface of the MMC disk member 131, and further arranges the metal bonding material on the upper surface of the MMC disk member 131 on the upper side. Each metal bonding material is provided with a through hole at a position through which the power supply terminal 54 is inserted. Next, the power supply terminal 54 of the alumina sintered body 120 is inserted into the through holes of the MMC disc members 131, 133, and 135, and the alumina sintered body 120 is arranged on the upper surface of the MMC disc member 131 on the upper side. Place it on the material. As a result, a laminate is obtained in which the MMC disk member 135, the metal bonding material, the MMC disk member 133, the metal bonding material, the MMC disk member 131, the metal bonding material, and the alumina sintered body 120 are laminated in order from the bottom. By applying pressure while heating this laminate (TCB), a joined body 110 is obtained (FIG. 6F). The joined body 110 is formed by joining an alumina sintered body 120 to the upper surface of an MMC block 130 that is the base of the cooling base material 30 via a metal joining layer 40 . In the MMC block 130, an upper MMC disk member 131 and a middle MMC disk member 133 are joined via a metal bonding layer, and the middle MMC disk member 133 and the lower MMC disk member 135 are joined together. are bonded via a metal bonding layer. The MMC block 130 has a coolant channel 32 and a storage hole 36 inside. A female screw member 38 is accommodated in the accommodation hole 36 .

TCB is performed, for example, as follows. That is, the laminate is pressurized and bonded at a temperature below the solidus temperature of the metal bonding material (for example, the temperature obtained by subtracting 20° C. from the solidus temperature and below the solidus temperature), and then returned to room temperature. As a result, the metal bonding material becomes a metal bonding layer. As the metal bonding material at this time, an Al--Mg system bonding material or an Al--Si--Mg system bonding material can be used. For example, when TCB is performed using an Al-Si-Mg-based bonding material, the laminated body is pressed while being heated in a vacuum atmosphere. It is preferable to use a metal bonding material having a thickness of about 100 μm.

Subsequently, the alumina base material 20 having the central portion 22 and the outer peripheral portion 24 is formed by cutting the outer periphery of the alumina sintered body 120 to form a step. Further, by cutting the outer periphery of the MMC block 130 to form a step, the cooling base 30 having the flange portion 34 is provided. Also, the insulating tube 55 is arranged in the insertion hole of the power supply terminal 54 provided in the MMC block 130 and the metal bonding layer 40 . Further, the insulating film 42 is formed by thermally spraying the side surface of the outer peripheral portion 24 of the alumina base material 20, the periphery of the metal bonding layer 40, and the side surface of the cooling base material 30 using alumina powder (FIG. 6G). Thus, the wafer mounting table 10 is obtained.

Although the cooling base material 30 in FIG. 1 is described as a single piece, it may have a structure in which three members are joined with a metal bonding layer as shown in FIG. A structure in which members are bonded by a metal bonding layer may be used.

Next, a usage example of the wafer mounting table 10 will be described with reference to FIG. On the installation plate 96 of the chamber 94, the outer peripheral region of the wafer mounting table 10 is fixed by the clamp members 70 and the central region of the wafer mounting table 10 is fixed by the bolts 98, as described above. A shower head 95 is arranged on the ceiling surface of the chamber 94 to discharge the process gas into the chamber 94 from a large number of gas injection holes. The installation plate 96 is made of an insulating material such as alumina.

A focus ring 78 is mounted on the FR mounting surface 24a of the wafer mounting table 10, and a disk-shaped wafer W is mounted on the wafer mounting surface 22a. The focus ring 78 has a step along the inner circumference of the upper end so as not to interfere with the wafer W. As shown in FIG. In this state, the DC voltage of the wafer chucking DC power supply 52 is applied to the wafer chucking electrode 26 to chuck the wafer W onto the wafer mounting surface 22a. Then, the inside of the chamber 94 is set to a predetermined vacuum atmosphere (or reduced pressure atmosphere), and the RF voltage from the RF power supply 62 is applied to the cooling substrate 30 while supplying the process gas from the shower head 95 . Plasma is then generated between the wafer W and the shower head 95 . Using the plasma, the wafer W is subjected to CVD film formation or etching. The focus ring 78 is also worn out as the wafer W is processed with plasma. However, since the focus ring 78 is thicker than the wafer W, the replacement of the focus ring 78 is performed after a plurality of wafers W are processed. will be

When processing the wafer W with high-power plasma, it is necessary to cool the wafer W efficiently. In the wafer mounting table 10 , the metal bonding layer 40 with high thermal conductivity is used as the bonding layer between the alumina base material 20 and the cooling base material 30 instead of the resin layer with low thermal conductivity. Therefore, the ability to remove heat from the wafer W (heat removal ability) is high. In addition, since the difference in thermal expansion between the alumina base material 20 and the cooling base material 30 is small, even if the stress relaxation property of the metal bonding layer 40 is low, troubles are unlikely to occur.

In the wafer mounting table 10 described above, the female threaded member 38 is placed in the storage hole 36 opening in the lower surface of the cooling substrate 30 so as to prevent it from falling out of the storage hole 36 in a state where its axial rotation is restricted. It is housed in a state of being engaged with the stepped portion 36c (engagement portion). Since the axial rotation of the female screw member 38 is restricted, the male screw 98 a of the bolt 98 inserted from the lower surface side of the cooling base material 30 can be screwed into the female screw member 38 . Further, even if the female screw member 38 is pulled toward the installation plate 96 by the bolt 98 inserted through the installation plate 96 in a state of being engaged with the stepped portion 36c of the housing hole 36, the female screw member 38 has ductility. Hard to break. Therefore, the wafer mounting table 10 having the brittle cooling base material 30 can be fastened to the mounting plate 96 without any trouble.

Also, the cooling base material 30 is made of MMC. Since MMC is a brittle material, it is highly significant to apply the present invention.

Further, the housing hole 36 has a stepped portion 36c as an engaging portion, and the female screw member 38 has a head portion 38a as an engaged portion. Therefore, the engaging portion and the engaged portion can be produced relatively easily.

Furthermore, when the female screw member 38 attempts to rotate about its axis, it abuts against the side wall of the first storage portion 36a of the storage hole 36 and is restricted from rotating about its axis. Therefore, axial rotation of the female screw member 38 can be restricted with a relatively simple configuration.

The storage hole 36 is provided in a region of the cooling substrate 30 that is lower than the bottom surface 32 a of the coolant channel 32 . Therefore, the accommodation hole 36 does not interfere with the coolant flow path 32 . Therefore, the degree of freedom in designing the coolant channel 32 is not impaired.

Moreover, the female screw member 38 is housed in a free state without being joined to the cooling base material 30 in the housing hole 36 . When the wafer mounting table 10 is manufactured, it is only necessary to put the female screw member 38 into the housing hole 36, which saves time and effort.

It goes without saying that the present invention is not limited to the above-described embodiments, and can be implemented in various forms as long as they fall within the technical scope of the present invention.

In the above-described first embodiment, the storage holes 36 are provided in the regions of the cooling base material 30 lower than the bottom surfaces 32a of the coolant channels 32, but the present invention is not limited to this. For example, as shown in FIG. 7, the ceiling surface 36d of the housing hole 36 may be provided so as to be higher than the bottom surface 32a of the coolant channel 32. As shown in FIG. In FIG. 7, the same symbols are attached to the same components as in the first embodiment described above. In FIG. 7, the first storage portion 36a of the storage hole 36 has the same size as in the first embodiment described above, but the vertical length of the second storage portion 36b is longer than in the first embodiment described above. Moreover, although the head portion 38a of the female screw member 38 has the same size as that of the above-described first embodiment, the vertical length of the cylindrical portion 38b is longer than that of the above-described first embodiment. Even in this way, substantially the same effects as those of the above-described first embodiment can be obtained. However, the degree of freedom in designing the coolant flow path 32 is restricted compared to the above-described first embodiment.

In the first embodiment described above, the stepped portion 36c is provided on the inner peripheral surface of the housing hole 36, but the present invention is not limited to this. For example, as shown in FIG. 8, the side faces of the head portion 38a of the female screw member 38 facing each other may be inclined surfaces 38c, and the inner peripheral surface of the housing hole 36 may be provided with an inclined portion 36e that coincides with the inclined surfaces 38c. good. In this case, since the inclined surface 38c of the female screw member 38 engages with the inclined portion 36e of the housing hole 36, the female screw member 38 does not fall out of the housing hole 36. When the bolt 98 is screwed into the female threaded member 38 , the female threaded member 38 is pulled toward the mounting plate 96 while the inclined surface 38 c is engaged with the inclined portion 36 e of the housing hole 36 .

In the above-described first embodiment, the shape of the head portion 38a of the female screw member 38 is rectangular in plan view, but the shape is not particularly limited to this. For example, the head 38a may have a polygonal shape such as a triangle or a pentagon, a plus (+) shape, or an elliptical shape in plan view. The shape of the first storage portion 36a of the storage hole 36 may be such that the head portion 38a contacts the side wall when the female screw member 38 is about to rotate. This point also applies to a female screw member 538 of a second embodiment, which will be described later.

In the first embodiment described above, the female threaded member 38 is employed as the coupling member and the bolt 98 is employed as the member to be coupled. However, as shown in FIG. A nut 82 may be employed as the member. In FIG. 9, the same symbols are attached to the same components as in the first embodiment described above. The male threaded member 80 is made of a ductile material. The male screw member 80 has a head portion 80a having the same shape as the head portion 38a, a foot portion 80b provided at the center of the back surface of the head portion 80a, and a male screw portion 80c provided at the tip of the foot portion 80b. The head 80a is housed in the first housing hole 36a of the housing hole 36. As shown in FIG. The leg portion 80b is inserted through the second housing hole 36b and the through hole 97 of the installation plate 96 . The male screw portion 80 c is screwed onto the nut 82 . The nut 82 is hooked on the stepped portion 97 a of the through hole 97 . Since the lower surface of the head portion 80 a of the male screw member 80 is engaged with the stepped portion 36 c of the housing hole 36 , the male screw member 80 does not fall out of the housing hole 36 . When the male threaded member 80 tries to rotate about its axis, the head 80a hits the side wall of the first housing portion 36a and its rotation is restricted. Therefore, the nut 82 can be screwed onto the male threaded portion 80 c of the male threaded member 80 . When the nut 82 is screwed onto the male threaded portion 80c of the male threaded member 80, the male threaded member 80 is pulled toward the installation plate 96 with the head portion 80a engaged with the stepped portion 36c of the housing hole 36. Become. Even when the configuration of FIG. 9 is adopted, the same effects as those of the above-described first embodiment can be obtained. Also in the second embodiment, which will be described later, a male threaded member may be employed as the coupling member instead of the female threaded member 538, and a nut may be employed as the coupled member instead of the bolt 98. FIG.

In the above-described first embodiment, a hole may be provided through the wafer mounting table 10 so as to reach the wafer mounting surface 22a from the lower surface of the cooling substrate 30. FIG. Such holes include a gas supply hole for supplying a heat-conducting gas (eg, He gas) to the rear surface of the wafer W, a lift pin hole for inserting a lift pin for moving the wafer W up and down with respect to the wafer mounting surface 22a, and the like. are mentioned. The heat transfer gas is supplied to a space formed by the wafer W and a large number of small projections (not shown) provided on the wafer mounting surface 22a (supporting the wafer W). Three lift pin holes are provided when the wafer W is supported by, for example, three lift pins. Between the lower surface of the cooling base material 30 and the upper surface of the installation plate 96, a resin or metal seal ring (for example, an O-ring) is arranged at a position facing the hole. Since the central region of wafer platform 10 is fixed by bolts 98, these seal rings are maintained in a firmly crushed state. Therefore, these seal rings can ensure sufficient sealing performance. This point also applies to a second embodiment, which will be described later.

In the first embodiment described above, the cooling base material 30 is made of MMC, but it may be made of a brittle material other than MMC (for example, an alumina material). This point also applies to the cooling base material 530 of the second embodiment, which will be described later.

In the above-described first embodiment, the wafer adsorption electrode 26 is built in the central portion 22 of the alumina base material 20, but instead of or in addition to this, an RF electrode for plasma generation may be built in, or a heater An electrode (resistive heating element) may be incorporated. In addition, a focus ring (FR) adsorption electrode, an RF electrode, and a heater electrode may be built in the peripheral portion 24 of the alumina base material 20 . This point also applies to a second embodiment, which will be described later.

In the above-described first embodiment, the alumina sintered body 120 in FIG. 6A was produced by hot-press firing a compact of alumina powder, but the compact at that time was produced by laminating a plurality of tape compacts. It may be produced by a mold casting method, or may be produced by compacting alumina powder. This point also applies to a second embodiment, which will be described later.

In the above-described first embodiment, the alumina base material 20 and the cooling base material 30 are bonded with the metal bonding layer 40, but instead of the metal bonding layer 40, a resin bonding layer may be used. This point also applies to a second embodiment, which will be described later.

In the first embodiment described above, the gap between the female screw member 38 and the first storage portion 36a of the storage hole 36 may be filled with a filler. By doing so, the heat conduction is better than when the gap is a space. Therefore, the temperature uniformity of the wafer W is improved. Examples of fillers include adhesive resins, non-adhesive resins, and thermally conductive powders (such as metal powders) added to these resins. The female screw member 38 is preferably provided with a through hole (a through hole extending from the inner space of the cylindrical portion 38b to the top surface of the head portion 38a) penetrating the female screw member 38 in the vertical direction. 6F, the fluid filler can be easily injected into the gap between the female screw member 38 and the first storage portion 36a of the storage hole 36 through the through hole.

[Second embodiment]
FIG. 10 is a longitudinal sectional view of the wafer mounting table 510 installed in the chamber 94 (sectional view taken along a plane including the central axis of the wafer mounting table 510), and FIG. is an enlarged cross-sectional view showing the.

The wafer mounting table 510 is also used to perform CVD, etching, etc. on the wafer W using plasma, and is fixed to a mounting plate 96 provided inside the semiconductor process chamber 94 . Since the chamber 94 has already been described in the first embodiment, the same components are denoted by the same reference numerals, and the description thereof will be omitted. The wafer mounting table 510 includes an alumina substrate 20 , a cooling substrate 530 and a metal bonding layer 540 .

Since the alumina base material 20 has already been described in the first embodiment, the same components are denoted by the same reference numerals, and the description thereof is omitted.

The cooling base material 530 is a disk member and is made of the same material as the cooling base material 30 . Here, the cooling base material 530 is a disk member made of MMC. The cooling substrate 530 has coolant flow channels 582 . The coolant channel groove 582 is formed in a unicursal manner from one end to the other end, and is provided in the cooling base material 530 so as to open to the lower surface of the cooling base material 530 . The coolant channel groove 582 forms the coolant channel 532 by closing the opening with the upper surface of the installation plate 96 of the chamber 94 . Therefore, the coolant channel groove 582 forms the side wall and the ceiling surface of the coolant channel 532 . The coolant channel 532 is also connected to a coolant supply channel and a coolant discharge channel (not shown) in the same manner as the coolant channel 32 of the first embodiment described above, and the coolant discharged from the coolant discharge channel is again cooled after being temperature-controlled. returned to the coolant supply path. The thickness of the cooling substrate 530 above the coolant channel grooves 582 is preferably 5 mm or less, more preferably 3 mm or less. In addition, the upper corner of the coolant channel groove 582 (the corner where the side wall and the ceiling surface intersect) is preferably an R surface, and the radius of curvature of the R surface is preferably 0.5 to 2 mm, for example. . Cooling substrate 530 is connected to RF power supply 62 via power supply terminal 64 . An HPF 63 is positioned between the cooling substrate 530 and the RF power supply 62 . Cooling substrate 530 has a flange portion 534 that is used to clamp to mounting plate 96 .

A plurality of housing holes 536 are provided in the cooling base material 530, and female screw members 538 (coupling members) are housed in the housing holes 536. As shown in FIG. A plurality of storage holes 536 are provided at regular intervals along the concentric circles of the cooling substrate 530, like the storage holes 36 of the first embodiment. As shown in FIG. 11, the storage hole 536 includes a first storage portion 536a, a second storage portion 536b, and a stepped portion 536c. The first storage portion 536 a is a space provided above the storage hole 536 and opens to the upper surface of the cooling base material 530 . The opening surface (upper surface) of the first storage portion 536 a is covered with a metal bonding layer 540 . The second storage portion 536b is a passage narrower than the first storage portion 536a so as to reach the lower surface of the cooling base material 530 from the first storage portion 536a. The stepped portion 536c is a stepped surface provided at the joint between the first storage portion 536a and the second storage portion 536b. A female screw member 538 is housed in the first housing portion 536a. The female screw member 538 is a rectangular parallelepiped (rectangular in plan view) nut having a screw hole (female screw) in the center. The first storage portion 536a is also a rectangular parallelepiped (substantially rectangular in plan view) space, and stores the female screw member 538 with play. A gap between the female screw member 538 and the first storage portion 536a is filled with a filler 539. As shown in FIG. Specifically, a gap surrounded by the top and side surfaces of the female screw member 538, the inner peripheral surface of the first storage portion 536a, and the metal bonding layer 540 is filled with the filler 539. As shown in FIG. Examples of the filler 539 include adhesive resins, non-adhesive resins, and thermally conductive powders (metal powders, etc.) added to these resins. The thermal conductivity of the filler 539 is preferably 1×10 ⁻⁴ W/mm·K or more, more preferably 1×10 ⁻³ W/mm·K or more, and more preferably 1×10 ⁻² W/mm·K or more. More preferred. The thermal conductivity of filler 539 can be adjusted, for example, by the amount of thermally conductive powder added to the resin. The width d of the gap between the female screw member 538 and the first storage portion 536a is preferably 0.2 mm or more, considering that the fluid uncured filler is injected into this gap. The stepped portion 536 c is arranged below the ceiling surface of the coolant channel groove 582 . The female screw member 538 is engaged with the stepped portion 536 c of the housing hole 536 . When the female screw member 538 tries to rotate about its axis, it abuts against the side wall of the first housing portion 536a and its rotation is restricted. In this embodiment, since the filling material 539 is present, the axial rotation of the female screw member 538 is also restricted by the filling material 539 . Female threaded member 538 is formed of a ductile material (eg, Ti, Mo, W, etc.).

The metal bonding layer 540 bonds the bottom surface of the alumina substrate 20 and the top surface of the cooling substrate 530 . Since the metal bonding layer 540 is the same as the metal bonding layer 40 of the first embodiment, its description is omitted.

The side surface of the outer peripheral portion 24 of the alumina base material 20 , the outer periphery of the metal bonding layer 540 and the side surface of the cooling base material 530 are covered with an insulating film 542 . As the insulating film 542, for example, a sprayed film such as alumina or yttria can be used.

The wafer mounting table 510 is mounted on a mounting plate 96 provided inside the chamber 94 via a large-diameter seal ring 576 and small-diameter seal rings 577 to 579 . The seal rings 576-579 are made of metal or resin. The seal ring 576 is positioned slightly inside the outer edge of the cooling substrate 530 to prevent coolant from leaking outside the seal ring 576 . A seal ring 577 is arranged to surround the foot of the bolt 98 to prevent coolant from entering inside the seal ring 577 . A seal ring 578 is arranged at the opening edge of the insulating tube 55 to prevent coolant from entering inside the seal ring 578 . The seal ring 579 is arranged to surround the power supply terminal 64 and prevents the refrigerant from entering inside the seal ring 579 .

A flange portion 534 provided on the outer circumference of the cooling base material 530 is attached to the installation plate 96 using the clamp members 70 and bolts 72 . Since the clamping member 70, the bolt 72 and the clamping method have already been explained in the first embodiment, the explanation thereof will be omitted. Also, the central region of the cooling substrate 530 is attached to the mounting plate 96 using bolts 98 (bonded members). As shown in FIG. 11, the leg portion of the bolt 98 is provided with a male screw 98a. The bolt 98 is inserted from the lower surface of the installation plate 96 through a through hole 97 provided in the installation plate 96 at a position facing the housing hole 536, and the male screw 98a is screwed into the female screw member 538 in the first housing portion 536a. combined. The through hole 97 has a small diameter at the top and a large diameter at the bottom, and has a stepped portion 97a between the top and bottom. The head of the bolt 98 is hooked on the stepped portion 97 a of the through hole 97 . Since the female screw member 538 is housed in the first storage portion 536 a with its axial rotation restricted, the bolt 98 can be screwed into the female screw member 538 . When the bolt 98 is screwed into the female threaded member 538 , the female threaded member 538 is pulled toward the mounting plate 96 while being engaged with the stepped portion 536 c of the housing hole 536 .

In this embodiment, since the central region of wafer mounting table 510 is fixed by bolts 98, wafer mounting table 510 can be prevented from protruding upward, and seal rings 576-578 can be firmly secured. and can be maintained in a crushed state.

The supply and discharge of the coolant to and from the coolant channel 582 is performed by adopting a structure similar to that shown in FIG. 5 described in the first embodiment.

Next, an example of manufacturing the wafer mounting table 10 will be described with reference to FIG. 12A and 12B are manufacturing process diagrams of the wafer mounting table 510. FIG. First, similarly to the first embodiment, an alumina sintered body 120 having a power supply terminal 54 is produced (FIGS. 12A to 12C).

In parallel with this, the MMC disk member 630 is manufactured (FIG. 12D), the cooling medium flow channel groove 582 is formed in the lower surface of the MMC disk member 630, and a storage hole vertically penetrating the MMC disk member 630 is formed. 536 (the first storage portion 536a, the second storage portion 536b, and the stepped portion 536c) and a through hole for inserting the power supply terminal 54 are formed (FIG. 12E). In this case, the MMC disk member 630 is preferably made of SiSiCTi or AlSiC. This is because the thermal expansion coefficient of alumina is approximately the same as that of SiSiCTi and AlSiC.

Next, after housing the female screw member 538 in the first housing portion 536 a , a metal bonding material is arranged on the upper surface of the MMC disk member 630 . A through hole for inserting the power supply terminal 54 is provided in the metal bonding material. Next, the alumina sintered body 120 is placed on the metal bonding material while inserting the power supply terminals 54 of the alumina sintered body 120 into the through holes of the metal bonding material and the through holes of the MMC disk member 630 . As a result, a laminate is obtained in which the MMC disk member 630, the metal bonding material, and the alumina sintered body 120 are laminated in this order from the bottom. By applying pressure while heating this laminate (TCB), a joined body 610 is obtained (FIG. 12F). A bonded body 610 is obtained by bonding an alumina sintered body 120 and an MMC disc member 630 with a metal bonding layer 540 . A female screw member 538 is accommodated in the first accommodation portion 536a of the joined body 610 . Since the metal bonding material and TCB have already been described in the first embodiment, the description thereof will be omitted here.

Subsequently, an uncured filler having fluidity is injected into the gap between the female screw member 538 and the first storage portion 536a through the screw holes of the second storage portion 536b and the female screw member 538. FIG. This gap is preferably 0.2 mm or more in consideration of ease of injection of the uncured filler. A filler 539 is obtained by curing the injected uncured filler. Subsequently, the alumina base material 20 having the central portion 22 and the outer peripheral portion 24 is formed by cutting the outer periphery of the alumina sintered body 120 to form a step. Further, by cutting the outer periphery of the MMC disk member 630 to form a step, the cooling base member 530 having the flange portion 534 is provided. Also, the insulating tube 55 is arranged in the insertion hole of the power supply terminal 54 . Further, the side surface of the outer peripheral portion 24 of the alumina base material 20, the periphery of the metal bonding layer 540, and the side surface of the cooling base material 530 are thermally sprayed using alumina powder to form an insulating film 542 (FIG. 12G). Thus, the wafer mounting table 510 is obtained.

Since the usage example of the wafer mounting table 510 is the same as the usage example of the wafer mounting table 10 of the first embodiment described above, the description thereof will be omitted.

In the wafer mounting table 510 described above, the female screw member 538 is placed in the housing hole 536 in such a manner that its axial rotation is restricted in the housing hole 536 that opens to the lower surface of the cooling base 530 and that it does not fall out of the housing hole 536 . It is housed in a state of being engaged with the stepped portion 536c (engagement portion). Since the axial rotation of the female screw member 538 is restricted, the male screw 98 a of the bolt 98 inserted from the lower surface side of the cooling base material 530 can be screwed into the female screw member 538 . Further, even if the female screw member 538 is pulled toward the installation plate 96 by the bolt 98 inserted through the installation plate 96 in a state of being engaged with the stepped portion 536c of the housing hole 536, the female screw member 538 has ductility. Hard to break. Therefore, the wafer mounting table 510 having the fragile cooling base material 530 can be fastened to the mounting plate 96 without any trouble.

Also, the cooling base material 530 is made of MMC. Since MMC is a brittle material, it is highly significant to apply the present invention.

Further, the housing hole 536 has a stepped portion 536c as an engaging portion, and the bottom surface of the female screw member 538 functions as an engaged portion. Therefore, the engaging portion and the engaged portion can be produced relatively easily.

Furthermore, when the female screw member 538 attempts to rotate about its axis, it abuts against the side wall of the first storage portion 536a of the storage hole 536 and is restricted from rotating about its axis. Therefore, axial rotation of the female screw member 538 can be restricted with a relatively simple configuration. In addition, the axial rotation of the female screw member 538 is also restricted by the filler 539 .

Further, the first storage portion 536a opens to the upper surface of the cooling base material 530, and the opening surface is covered with the metal bonding layer 540. As shown in FIG. Therefore, the first storage portion 536a can be manufactured relatively easily compared to the case where the first storage portion 36a is built inside the cooling base material 30 as in the first embodiment. In such a structure, since it is necessary to provide the coolant channel 532 (coolant channel groove 582) while avoiding the storage hole 536, the temperature uniformity of the wafer W is likely to deteriorate in the vicinity directly above the storage hole 536. FIG. A filler 539 is filled in the gap between the female screw member 538 and the first housing portion 536a of the housing hole 536 in order to suppress such deterioration in the uniformity of heat. As a result, the heat conduction around the storage hole 536 is improved, so that the deterioration of the heat uniformity can be suppressed.

It goes without saying that the present invention is not limited to the above-described embodiments, and can be implemented in various forms as long as they fall within the technical scope of the present invention.

In the above-described second embodiment, as shown in FIG. 13, the female screw member 538 is engaged with the stepped portion 536c of the housing hole 536 via the stress buffering member 537 having a Young's modulus lower than that of the female screw member 538. may For example, the female screw member 538 may be made of Ti alloy and the stress buffer member 537 may be made of pure Al. In this way, even if the female screw member 538 is pulled toward the installation plate 96 by the bolt 98 provided on the installation plate 96, the stress buffering member 537 is interposed between the female screw member 538 and the stepped portion 536c. stress is easily distributed. In order to reduce the stress in the first storage portion 536a, firstly, the width w of the annular region where the stepped portion 536c and the female screw member 538 indirectly contact is preferably 3 mm or more, more preferably 5 mm or more. Second, the inner diameter x of the screw hole of the female screw member 538 is preferably 10 mm or less, more preferably 7 mm or less. Third, when the corner between the bottom surface and the side surface of the first housing portion 536a is defined as an R surface (a rounded surface), the radius of curvature r is preferably 0.3 mm or more, and preferably 0.5 mm or more. is more preferred. 1st to 3rd indicate the order of stress reduction effect, and the first condition has the highest stress reduction effect. Moreover, the corner between the bottom surface and the side surface of the female screw member 538 is preferably an R surface or a C surface. The thickness t from the stepped portion 536c to the lower surface of the cooling substrate 530 is preferably 3 mm or more and 10 mm or less. These numerical ranges are the same in the case without the stress buffering member 537 and in the first embodiment.

In the above-described second embodiment, the coolant channel groove 582 is provided on the lower surface of the cooling base material 530, and the installation plate 96 (lower base material) is arranged below the cooling base material 530 to be installed on the lower surface of the cooling base material 530. Although the seal ring that liquid-tightly closes the coolant channel groove 582 is arranged between the plate 96 and the plate 96, it is not particularly limited to this. For example, the coolant channel groove is provided on the upper surface of the mounting plate instead of the lower surface of the cooling base material, and a seal ring is arranged between the lower surface of the cooling base material and the mounting plate to liquid-tightly close the coolant channel groove. good too. The cooling base material is brittle MMC, alumina, or the like, and the cooling base material is provided with a first housing.

In the above-described second embodiment, as shown in FIG. 14A, a nut having a triangular prism shape (triangular in plan view) and having a screw hole in the center may be used as the female screw member 538 . In that case, a storage hole 536 may be formed as shown in FIG. 14B. FIG. 14B is a partially enlarged view of the periphery of the storage hole 536 when viewed from below the cooling base material 530. FIG. In FIG. 14B, the second storage portion 536b is a triangular hole in plan view through which the female screw member 538 can pass, and the first storage portion 536a is a space (in plan view) through which the female screw member 538 can rotate by a predetermined angle. is a composite figure of a triangle and a circle). The state immediately after the female screw member 538 is inserted into the second storage portion 536b and stored in the first storage portion 536a is shown by a two-dot chain line, and the female screw member 538 stored in the first storage portion 536a is shown at a predetermined angle. The one-dot chain line shows a state in which the axis rotates in the direction of the arrow. At this time, the step portion 536 c is a portion inside the outer edge of the first storage portion 536 a and outside the opening edge of the second storage portion 536 b , and this portion engages with the female screw member 538 . According to such a structure, after joining the alumina base material 20 and the cooling base material 530, the female screw member 538 can be accommodated in the first accommodating portion 536a. For example, first, the alumina base material 20 and the cooling base material 530 are bonded by the metal bonding layer 540 without accommodating the female screw member 538 in the first accommodating portion 536a. Next, the fluid uncured filling material is injected into the first storage portion 536a so that the lower surface of the cooling base material 30 faces upward. Next, the female screw member 538 is stored from the second storage portion 536b into the first storage portion 536a, and then the female screw member 538 is axially rotated by a predetermined angle. As a result, the uncured filling material is evenly filled between the female screw member 538 and the first storage portion 536a. After that, the uncured filler material is cured to form the filler material 539 . Note that such a structure can be applied not only to a triangular prism-shaped nut but also to a polygonal prism-shaped (square prism, hexagonal prism, etc.) nut.

Instead of the female screw member 538 of the second embodiment described above, the female screw member 38 (FIGS. 3, 7 or 8) of the first embodiment may be adopted. In that case, the female screw member 38 is preferably provided with a through hole (a through hole extending from the inner space of the cylindrical portion 38b to the top surface of the head portion 38a) penetrating the female screw member 38 in the vertical direction. This is because the gap between the head portion 38a and the first storage portion of the storage hole can be easily filled with a fluid uncured filler by using the through hole.

In the above-described second embodiment, as shown in FIG. 15, instead of providing the coolant channel groove 582 (coolant channel 532) in the cooling substrate 530, the coolant channel groove 91 is provided on the upper surface of the installation plate 96, The coolant channel 92 may be formed by closing the upper opening of the coolant channel groove 91 with the cooling substrate 530 . In FIG. 15, the same symbols are attached to the same components as in the second embodiment described above. Also in the first embodiment, instead of providing the coolant flow path 32 in the cooling base material 30, a coolant flow path groove is provided on the upper surface of the installation plate 96 as shown in FIG. The coolant flow path may be formed by blocking with the base material 30 .

10 wafer mounting table, 20 alumina substrate, 22 central portion, 22a wafer mounting surface, 24 outer peripheral portion, 24a focus ring mounting surface, 26 wafer adsorption electrode, 27 hole, 30 cooling substrate, 32 coolant channel, 32a bottom surface 32p first supply passage 32q refrigerant supply seal ring 32r second supply passage 32s first discharge passage 32t refrigerant discharge seal ring 32u second discharge passage 34 flange portion 36 storage hole 36a First storage portion 36b Second storage portion 36c Stepped portion 36d Ceiling surface 36e Inclined portion 38 Female screw member 38a Head 38b Cylindrical portion 38c Inclined surface 40 Metal bonding layer 42 Insulating film 52 DC power supply for wafer adsorption, 53 low-pass filter, 54 power supply terminal, 55 insulating tube, 62 RF power supply, 63 high-pass filter, 64 power supply terminal, 70 clamp member, 70a inner peripheral step surface, 72 bolt, 76 seal ring, 78 focus ring , 80 male screw member, 80a head, 80b foot, 80c male screw, 82 nut, 91 coolant channel groove, 92 coolant channel, 94 chamber, 95 shower head, 96 installation plate, 97 through hole, 97a step Part, 98 bolt, 98a male screw, 110 joined body, 120 alumina sintered body, 130 MMC block, 131, 133, 135 MMC disk member, 132 groove, 136 stepped hole, 321 coolant supply path, 322 coolant discharge path, 510 wafer mounting table, 530 cooling substrate, 532 coolant channel, 534 flange portion, 536 storage hole, 536 storage portion, 536a first storage portion, 536b second storage portion, 536c stepped portion, 537 stress buffer member, 538 female screw member, 539 filler, 540 metal bonding layer, 542 insulating film, 576 to 579 seal ring, 582 refrigerant channel groove, 610 joined body, 630 MMC disk member, W wafer.

Claims (12)

an alumina base material having a wafer mounting surface on its upper surface and containing an electrode;
a brittle cooling substrate bonded to the lower surface of the alumina substrate;
A ductile coupling member having a male screw portion or a female screw portion, which is accommodated in a storage hole opening to the lower surface of the cooling base material in a state in which rotation of the shaft is restricted and in a state in which the engaging portion of the storage hole is engaged. and,
A wafer mounting table. The coupling member has the female screw portion and is a member that can be screwed with a male screw of a bolt that is inserted from the lower surface side of the cooling base material.
The wafer mounting table according to claim 1. The cooling base is made of a composite material of metal and ceramic or an alumina material,
The wafer mounting table according to claim 1 or 2. The engaging portion is a stepped portion or an inclined portion provided on the inner peripheral surface of the housing hole,
The coupling member has an engaged portion that engages with the engaging portion to prevent the coupling member from falling out of the housing hole.
The wafer mounting table according to claim 1 or 2. When the coupling member is about to rotate, it hits the wall of the housing hole and is restricted from rotating.
The wafer mounting table according to claim 1 or 2. The cooling base material has a coolant channel inside,
The storage hole is provided in a region of the cooling substrate that is lower than the bottom surface of the coolant channel,
The wafer mounting table according to claim 1 or 2. The connecting member is housed in a free state without being joined to the cooling base material in the housing hole,
The wafer mounting table according to claim 1 or 2. The coupling member is engaged with the engaging portion via a stress buffering member having a Young's modulus lower than that of the coupling member.
The wafer mounting table according to claim 1 or 2. a gap between the coupling member and the housing hole is filled with a filler;
The wafer mounting table according to claim 1 or 2. The storage hole includes a first storage portion that stores the coupling member, and a second storage portion that extends from the first storage portion to the lower surface of the cooling substrate,
The engaging portion is a stepped surface provided at the joint between the first storage portion and the second storage portion,
The wafer mounting table according to claim 1 or 2. The first storage part opens to the upper surface of the cooling base material, and the opening surface is covered with a bonding layer that bonds the ceramic base material and the cooling base material.
The wafer mounting table according to claim 10. The width of the annular region where the step surface and the coupling member are in direct or indirect contact is 3 mm or more.
The wafer mounting table according to claim 10.

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