Wafer mounting stage

Abstract

To increase plasma density in a region right above a ceramic base material.SOLUTION: A wafer mounting table 10 comprises: a ceramic base material 20 which has a wafer mounting surface 22a on its upper surface and is internally provided with an electrode 26; a conductive base material 30, provided on a lower surface side of the ceramic base material 20, which is also used as a plasma generating electrode and has the diameter equal to that of the ceramic base material 20; a support base material 40, provided on a lower surface side of the conductive base material 30, which has a diameter greater than that of the conductive base material 30 and is electrically insulated from the conductive base material 30; and a fitting flange 42 which is a portion, of the support base material 40, protruding further outward in the radial direction than the conductive base material 30.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wafer mounting table.

Background Art

[0002] Conventionally, as a wafer mounting table, there is known one including a ceramic base material having a wafer mounting surface and incorporating electrodes, and a conductive cooling base material provided on the lower surface side of the ceramic base material. For example, Patent Document 1 discloses a wafer mounting table of this type provided with a cooling base material having a diameter larger than that of the ceramic base material. In the description of the usage example of the wafer mounting table, it is described that a high-frequency voltage may be applied to the cooling base material when generating plasma.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since the cooling base material has a larger diameter than the ceramic base material, plasma is generated not only in the region overlapping the wafer in plan view but also in the region protruding from the wafer. The plasma generated in the region protruding from the wafer is wasted because it is not used for wafer processing. Therefore, there is a problem that the plasma density in the region directly above the ceramic base material (the plasma generation region in design) decreases.

[0005] The present invention has been made to solve such problems, and the main object is to increase the plasma density in the region directly above the ceramic base material.

Means for Solving the Problems

[0006] [1] The wafer mounting table of the present invention is A ceramic substrate having a wafer mounting surface on its upper surface and containing electrodes, A conductive substrate having the same diameter as the ceramic substrate is provided on the lower side of the ceramic substrate, has a refrigerant flow path or refrigerant flow path groove, and also serves as a plasma generating electrode, A support substrate is provided on the lower side of the conductive substrate, has a larger diameter than the conductive substrate, and is electrically insulated from the conductive substrate, The mounting flange is a portion of the support base material that protrudes radially outward from the conductive base material, It is something that is provided.

[0007] In the wafer mounting stage of the present invention, the portion of the support substrate that extends radially outward from the conductive substrate is used as a mounting flange, but the support substrate is electrically insulated from the conductive substrate. Therefore, the mounting flange does not function as a plasma generation electrode, and plasma generation in the region directly above the mounting flange is suppressed. As a result, the plasma density in the region directly above the ceramic substrate can be increased.

[0008] 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, if the orientation of the wafer mounting stage is changed, up and down may become left and right, or left and right may become up and down, but such cases are also included within the technical scope of the present invention.

[0009] [2] In the wafer mounting stage described above (the wafer mounting stage described in [1] above), the support substrate may be made of an insulating material. In this way, the support substrate can be electrically insulated from the conductive substrate relatively easily.

[0010] [3] In the wafer mounting stage described above (the wafer mounting stage described in [2] above), the first bonding layer that bonds the ceramic substrate and the conductive substrate and the second bonding layer that bonds the conductive substrate and the support substrate may both be metal bonding layers. In this case, the bonding of the ceramic substrate and the conductive substrate and the bonding of the conductive substrate and the support substrate can be performed in the same process, thereby reducing manufacturing costs.

[0011] [4] In the wafer mounting stand described above (the wafer mounting stand described in [2] or [3] above), the conductive substrate may have the refrigerant flow channel groove, and the refrigerant flow channel groove may have an opening on the surface of the conductive substrate facing the support substrate. In this case, the material on the lower side of the refrigerant flow channel is not required compared to the case in which the conductive substrate has a refrigerant flow channel, and thus the manufacturing cost can be reduced.

[0012] [5] In the wafer mounting stage described above (the wafer mounting stage described in [1] above), the support substrate may be made of metal, and an insulating layer may be provided between the support substrate and the conductive substrate. In this way, even if the support substrate is made of metal, the support substrate and the conductive substrate can be electrically insulated.

[0013] [6] In the wafer mounting stand described above (the wafer mounting stand described in [5] above), screw holes may be provided on the lower surface of the support substrate. Since the support substrate is made of metal, that is, a ductile material, screw holes can be provided on the lower surface of the support substrate. On the other hand, if the support substrate is made of a brittle material (for example, ceramic or a composite material of metal and ceramic), it is difficult to provide screw holes in the support substrate. [Brief explanation of the drawing]

[0014] [Figure 1] A longitudinal cross-sectional view of the wafer mounting platform 10 installed in chamber 94. [Figure 2] Plan view of wafer mounting platform 10. [Figure 3] Manufacturing process diagram for wafer mounting platform 10. [Figure 4] Vertical cross-sectional view of the wafer stage 210 installed in the chamber 94. [Figure 5] Manufacturing process diagram of the wafer stage 210. [Figure 6] Vertical cross-sectional view of another example of the wafer stage 10.

Mode for Carrying Out the Invention

[0015] [First Embodiment] The first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical cross-sectional view of the wafer stage 10 installed in the chamber 94 (a cross-sectional view when cut along a plane including the central axis of the wafer stage 10), and FIG. 2 is a plan view of the wafer stage 10.

[0016] The wafer stage 10 is used for performing CVD, etching, etc. on the wafer W using plasma, and is fixed to the installation plate 96 provided inside the chamber 94 for semiconductor processes. The wafer stage 10 includes a ceramic substrate 20, a conductive substrate 30, and a support substrate 40.

[0017] The ceramic substrate 20 is a disc having a circular wafer placement surface 22a on its upper surface. The wafer W is placed on the wafer placement surface 22a. The ceramic substrate 20 is formed of a ceramic material typified by alumina, aluminum nitride, etc.

[0018] The ceramic substrate 20 incorporates an electrode 26 for wafer adsorption on the side closer to the wafer placement surface 22a. The electrode 26 for wafer adsorption is formed of a material containing, for example, W, Mo, WC, MoC, etc. The electrode 26 for wafer adsorption is a single-pole type electrostatic adsorption electrode in a disc shape or a mesh shape. The layer above the electrode 26 for wafer adsorption in the ceramic substrate 20 functions as a dielectric layer. A DC power supply 52 for wafer adsorption is connected to the electrode 26 for wafer adsorption via a power supply terminal 54. The power supply terminal 54 passes through an insulating tube 55 disposed in a through-hole that vertically penetrates the conductive substrate 30, the support substrate 40, the first bonding layer 46, and the second bonding layer 48, and is provided so as to reach the electrode 26 for wafer adsorption from the lower surface of the ceramic substrate 20. A low-pass filter (LPF) 53 is provided between the DC power supply 52 for wafer adsorption and the electrode 26 for wafer adsorption.

[0019] The conductive substrate 30 is a disc having the same diameter as the ceramic substrate 20 and is provided on the lower surface side of the ceramic substrate 20. The conductive substrate 30 is used as a cooling substrate for cooling the ceramic substrate 20 and has good thermal conductivity. Inside the conductive substrate 30, a refrigerant flow path 32 through which a refrigerant circulates is formed. The refrigerant flow path 32 is formed in one stroke from one end (inlet) to the other end (outlet) over the entire conductive substrate 30 in a plan view. A supply port and a recovery port of an external refrigerant device (not shown) are respectively connected to one end and the other end of the refrigerant flow path 32. The refrigerant supplied from the supply port of the external refrigerant device to one end of the refrigerant flow path 32 returns from the other end of the refrigerant flow path 32 to the recovery port of the external refrigerant device after passing through the refrigerant flow path 32, and after being temperature-adjusted, is supplied again from the supply port to one end of the refrigerant flow path 32. The refrigerant flowing through the refrigerant flow path 32 is preferably a liquid and preferably has electrical insulation properties. Examples of the electrically insulating liquid include fluorine-based inert liquids.

[0020] The material of the conductive substrate 30 can be, for example, a metal material or a composite material of metal and ceramic. Examples of metallic materials include Al, Ti, Mo, or alloys thereof. Examples of composite materials of metal and ceramic include metal matrix composite materials (MMC) and ceramic matrix composite materials (CMC). Specific examples of such composite materials include materials containing Si, SiC, and Ti (also called SiSiCTi), materials in which Al and / or Si are impregnated into a porous SiC body, and composite materials of Al2O3 and TiC. It is preferable to select a material for the conductive substrate 30 that has a similar coefficient of thermal expansion to the material of the ceramic substrate 20. The conductive substrate 30 also serves as a plasma generation electrode and is connected to the RF power supply 62 via a power supply terminal 64. The power supply terminal 64 is provided so as to reach the lower surface of the conductive substrate 30 by passing through an insulating tube 65 located in a through-hole that penetrates the support substrate 40 and the second bonding layer 48. The power supply terminal 64 is provided in the chamber 94 and is biased from bottom to top by a spring (not shown). Therefore, the upper end of the power supply terminal 64 is in elastic contact with the lower surface of the conductive substrate 30. In the first embodiment, the insulating tube 65 may be omitted. A high-pass filter (HPF) 63 is placed between the conductive substrate 30 and the RF power supply 62.

[0021] The support base material 40 is a disc with a larger diameter than the conductive base material 30 and is provided on the lower side of the conductive base material 30. The support base material 40 has a central portion 41 with the same diameter as the conductive base material 30 and a mounting flange 42 which is a portion that extends radially outward from the conductive base material 30. The support base material 40 is made of an insulating material. Therefore, the support base material 40 is electrically insulated from the conductive base material 30. Examples of insulating materials include ceramic materials such as alumina and aluminum nitride. It is preferable to select a material for the support base material 40 that has a similar coefficient of thermal expansion to the conductive base material 30, that is, a similar coefficient of thermal expansion to the material of the ceramic base material 20.

[0022] The ceramic substrate 20 and the conductive substrate 30 are joined via a first bonding layer 46. The conductive substrate 30 and the support substrate 40 are joined via a second bonding layer 48. Both the first bonding layer 46 and the second bonding layer 48 are metal bonding layers. The metal bonding layers may be layers formed of, for example, solder or metal brazing material. The metal bonding layers are formed by, for example, TCB (Thermal Compression Bonding). TCB is a known method in which a metal bonding material is sandwiched between two members to be joined, and the two members are pressurized and bonded together while heated to a temperature below the solidus temperature of the metal bonding material.

[0023] The sides of the ceramic substrate 20, the outer periphery of the first bonding layer 46, the sides of the conductive substrate 30, the outer periphery of the second bonding layer 48, and the upper and side surfaces of the mounting flange 42 of the support substrate 40 are covered with an insulating film 50. Examples of insulating films 50 include thermal spray coatings of alumina and yttria. In the first embodiment, some or all of the insulating film 50 provided on the sides of the ceramic substrate 20 and the upper and side surfaces of the mounting flange 42 may be omitted.

[0024] The wafer mounting base 10 is attached to a mounting plate 96 provided inside the chamber 94 using clamp members 70. A seal ring 78 is placed between the wafer mounting base 10 and the mounting plate 96. The seal ring 78 is made of metal or resin and is positioned slightly inside the outer edge of the support base material 40. The clamp member 70 is an annular member with a roughly inverted L-shaped cross-section and has an inner circumferential stepped surface 70a. The wafer mounting base 10 and the mounting plate 96 are integrated by the clamp member 70. With the inner circumferential stepped surface 70a of the clamp member 70 placed on the mounting flange 42 of the wafer mounting base 10, bolts 72 are inserted from the upper surface of the clamp member 70 and screwed into screw holes provided on the upper surface of the mounting plate 96. The bolts 72 are attached to multiple locations (for example, 8 or 12 locations) that are provided at equal intervals along the circumference of the clamp member 70. The clamp member 70 and the bolt 72 may be made of an insulating material or a conductive material (such as metal). Preferably, the bolt 72 is made of a ductile material (for example, Ti, Mo, W, etc.).

[0025] Next, an example of the manufacturing of the wafer mounting stage 10 will be explained using Figure 3. Figure 3 is a manufacturing process diagram of the wafer mounting stage 10. Here, we will illustrate the case in which the conductive substrate 30 is made of MMC and the support substrate 40 is made of ceramic. First, a ceramic substrate 20 containing the wafer adsorption electrode 26 is prepared (Figure 3A). For example, a molded body of ceramic powder containing the wafer adsorption electrode 26 is made, and the ceramic substrate 20 is obtained by hot-press firing of the molded body. Next, a hole 27 is made from the bottom surface of the ceramic substrate 20 to the wafer adsorption electrode 26 (Figure 3B), and a power supply terminal 54 is inserted into the hole 27 to join the power supply terminal 54 and the wafer adsorption electrode 26 (Figure 3C).

[0026] In parallel with this, two MMC disc members 131 and 136 are fabricated (Figure 3D), and a groove 132, which will ultimately become the refrigerant flow path 32, is formed on the lower surface of the upper MMC disc member 131, and through holes 134 and 138 that penetrate vertically are formed in both MMC disc members 131 and 136 (Figure 3E). If the ceramic substrate 20 is made of alumina, it is preferable that the MMC disc members 131 and 136 be made of SiSiCTi or AlSiC. This is because the thermal expansion coefficient of alumina is approximately the same as that of SiSiCTi or AlSiC.

[0027] A disc-shaped member made of SiSiCTi can be manufactured, for example, as follows: First, a powder mixture is prepared by mixing silicon carbide, metallic Si, and metallic Ti. Next, a disc-shaped molded body is formed from the obtained powder mixture by uniaxial pressure molding, and this molded body is hot-press sintered in an inert atmosphere to obtain a disc-shaped member made of SiSiCTi.

[0028] Furthermore, in parallel with these steps, a support base 40 made of ceramic material is prepared (Figure 3F). For example, a molded body of ceramic powder is made, and the support base 40 is obtained by hot-press firing the molded body. If the ceramic base 20 is made of alumina, it is preferable that the support base 40 is also made of alumina. From the viewpoint of cost reduction, the alumina of the support base 40 may be of lower purity than the alumina of the ceramic base 20. Next, through holes 43 and 45 are formed that penetrate the support base 40 in the vertical direction (Figure 3G).

[0029] Next, a metal fastening material is placed between the lower surface of the lower MMC disc member 136 and the upper surface of the support base material 40. The metal fastening material has through holes communicating with through holes 43 and 45. In addition, a metal fastening material is placed between the lower surface of the upper MMC disc member 131 and the upper surface of the lower MMC disc member 136, and a metal fastening material is placed on the upper surface of the upper MMC disc member 131. Each metal fastening material has through holes communicating with through holes 134 and 138. The power supply terminals 54 of the ceramic base material 20 are inserted into the through holes 134 and 138 of the MMC disc members 131 and 136 and the through hole 43 of the support base material 40, and the ceramic base material 20 is placed on top of the metal fastening material placed on the upper surface of the upper MMC disc member 131. This results in a laminate in which the support base material 40, metal bonding material, lower MMC disc member 136, metal bonding material, upper MMC disc member 131, metal bonding material, and ceramic base material 20 are stacked in this order from bottom to top. By heating and pressurizing this laminate (TCB), a bonded body 110 is obtained (Figure 3H). In the bonded body 110, a conductive base material 30 is bonded to the upper surface of the support base material 40 via a second bonding layer 48, which is a metal bonding layer, and a ceramic base material 20 is bonded to the upper surface of the conductive base material 30 via a first bonding layer 46, which is a metal bonding layer. The conductive base material 30 is formed by bonding the upper MMC disc member 131 and the lower MMC disc member 136 via a metal bonding layer 135. The conductive base material 30 has a coolant flow path 32 inside.

[0030] TCB (Temperature-Correcting Bonding) is performed, for example, as follows: The laminate is pressed and bonded at a temperature below the solidus temperature of the metal bonding material (for example, between 20°C below the solidus temperature and the solidus temperature), and then returned to room temperature. This causes the metal bonding material to become a metal bonding layer. As the metal bonding material, Al-Mg-based bonding materials or Al-Si-Mg-based bonding materials can be used. For example, when performing TCB using an Al-Si-Mg-based bonding material, the laminate is pressed while heated in a vacuum atmosphere. It is preferable to use a metal bonding material with a thickness of around 100 μm.

[0031] Next, insulating tubes 55 for inserting power supply terminals 54 are placed in the through holes 134, 138, 43 and the holes in the metal bonding material. In addition, insulating tubes 65 for inserting power supply terminals 64 are placed in the through hole 45 and the holes in the metal bonding material. Furthermore, an insulating film 50 is formed by thermal spraying ceramic powder onto the sides of the ceramic substrate 20, the periphery of the first bonding layer 46, the sides of the conductive substrate 30, the periphery of the second bonding layer 48, and the upper and side surfaces of the mounting flange 42 of the support substrate 40 (Figure 3I). This gives rise to the wafer mounting stage 10.

[0032] Although the conductive substrate 30 in Figure 1 is described as a single unit, it may also be a structure in which two members are joined by a metal bonding layer, as shown in Figure 3I, or a structure in which three or more members are joined by a metal bonding layer.

[0033] Next, an example of the use of the wafer mounting stand 10 will be explained with reference to Figure 1. As described above, the wafer mounting stand 10 is fixed to the mounting plate 96 of the chamber 94 by a clamp member 70. A shower head 98 is positioned on the ceiling surface of the chamber 94 to release process gas into the chamber 94 from numerous gas injection holes.

[0034] A disc-shaped wafer W is placed on the wafer mounting surface 22a of the wafer mounting table 10. In this state, a DC voltage from the wafer adsorption DC power supply 52 is applied to the wafer adsorption electrode 26 to adsorb 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 while supplying process gas from the shower head 98, an RF voltage from the RF power supply 62 is applied to the conductive substrate 30. Plasma is then generated between the wafer W and the shower head 98. This plasma is then used to perform CVD film deposition or etching on the wafer W.

[0035] When processing wafers W with high-power plasma, it is necessary to cool the wafers W efficiently. In the wafer mounting stage 10, a metal bonding layer with high thermal conductivity is used as the first bonding layer 46 between the ceramic substrate 20 and the conductive substrate 30, rather than a resin layer with low thermal conductivity. Therefore, it has a high ability to draw heat away from the wafers W (heat dissipation capacity). In addition, because the difference in thermal expansion between the ceramic substrate 20 and the conductive substrate 30 is small, problems are less likely to occur even if the stress relaxation properties of the first bonding layer 46 are low.

[0036] In the wafer mounting stage 10 described above, the portion of the support base material 40 that extends radially outward from the conductive base material 30 is used as a mounting flange 42. However, since the support base material 40 is made of an insulating material, it is electrically insulated from the conductive base material 30. Therefore, the mounting flange 42 does not function as a plasma generation electrode, and plasma generation in the region directly above the mounting flange 42 is suppressed. As a result, the plasma density in the region directly above the ceramic base material 20 can be increased.

[0037] Furthermore, since the support substrate 40 is made of an insulating material, the support substrate 40 can be electrically insulated from the conductive substrate 30 relatively easily.

[0038] Furthermore, since both the first bonding layer 46 and the second bonding layer 48 are metal bonding layers, the bonding of the ceramic substrate 20 to the conductive substrate 30 and the bonding of the conductive substrate 30 to the support substrate 40 can be performed in the same process. This reduces manufacturing costs.

[0039] [Second Embodiment] A second embodiment of the present invention will be described below with reference to the drawings. Figure 4 is a longitudinal cross-sectional view (a cross-sectional view taken when cut by a plane including the central axis of the wafer mounting stage 210) of a wafer mounting stage 210 installed in a chamber 94. The wafer mounting stage 210 is used to perform CVD, etching, etc. on a wafer W using plasma, and is fixed to a mounting plate 96 provided inside the semiconductor process chamber 94. The wafer mounting stage 210 comprises a ceramic substrate 20, a conductive substrate 30, and a support substrate 240. In the second embodiment, components similar to those in the first embodiment are denoted by the same reference numerals and their description is omitted.

[0040] The support base material 240 is a disc with a larger diameter than the conductive base material 30 and is provided on the lower surface of the conductive base material 30. The support base material 240 has a central portion 241 with the same diameter as the conductive base material 30 and a mounting flange 242 which is a portion that extends radially outward from the conductive base material 30. The support base material 240 is made of a metallic material. Examples of metallic materials include Al, Ti, Mo, or alloys thereof. Multiple screw holes 244 are provided on the lower surface of the support base material 240. Multiple screw holes 244 are provided in the central portion 241 of the support base material 240 at roughly equal intervals (for example, 6 or 8) so as to substantially follow the concentric circles of the support base material 240 (for example, circles with a diameter of 1 / 2 or 1 / 3 of the wafer W). The multiple screw holes 244 have internal threads cut into their inner circumferential surfaces and open to the lower surface of the support base material 240. Multiple through holes 246 are provided in the mounting flange 242 of the support base material 240. Multiple through holes 246 are provided at roughly equal intervals (for example, 8 or 12) so as to be almost concentric with the support base material 240. The multiple through holes 246 penetrate the mounting flange 242 in the vertical direction and open on the upper and lower surfaces of the mounting flange 242.

[0041] A second bonding layer 248, which is an insulating layer, is provided between the conductive substrate 30 and the support substrate 240. This second bonding layer 248 electrically insulates the support substrate 240 from the conductive substrate 30. This second bonding layer 248 is a layer formed from an adhesive sheet made of an insulating resin such as silicone resin, acrylic resin, polyimide resin, or epoxy resin, and is a circular layer with the same diameter as the bottom surface of the conductive substrate 30. The second bonding layer 248 may be a single-layer structure or a multi-layer structure. The second bonding layer 248 may be a sheet with acrylic resin layers on both sides of a polypropylene core, a sheet with silicone resin layers on both sides of a polyimide core, or a sheet made of epoxy resin alone.

[0042] These wafer mounting tables 210 are attached to a mounting plate 96 provided inside the chamber 94 using bolts 274 and 276. A seal ring 278 is placed between the wafer mounting table 210 and the mounting plate 96. The seal ring 278 is made of metal or resin and is positioned slightly inside the outer edge of the central part 241 of the support base material 240. The bolts 274 have male threads on the outer circumference of their feet and are inserted from the bottom surface of the mounting plate 96 into through holes provided in the mounting plate 96 opposite to the screw holes 244, and are screwed into the screw holes 244 of the support base material 240. The bolts 276 have male threads on the outer circumference of their feet and are inserted from the top surface of the mounting flange 242 into through holes 246 provided in the mounting flange 242, and are screwed into the screw holes provided in the mounting plate 96 opposite to the through holes 246. This screw hole has an internal thread on its inner surface and opens onto the upper surface of the mounting plate 96. Bolts 274 and 276 may be made of an insulating material or a conductive material (such as metal). Preferably, bolts 274 and 276 are made of a ductile material (such as Ti, Mo, or W).

[0043] Next, an example of the manufacturing of the wafer mounting table 210 will be explained using Figure 5. Figure 5 is a manufacturing process diagram showing the manufacturing process of the wafer mounting table 210. Here, we will illustrate the case where the conductive substrate 30 is made of MMC and the support substrate 240 is made of metal. When manufacturing this wafer mounting table 210, first, the same process as in Figures 3A to E is performed (Figures 5A to E). In parallel with this, a support substrate 240 made of metal material is prepared (Figure 5F), and through holes 243 and 245 that penetrate the support substrate 240 in the vertical direction, screw holes 244 provided on the lower surface of the support substrate 240, and through holes 246 that penetrate the outer circumference of the support substrate 240 in the vertical direction are formed (Figure 5G).

[0044] Next, a metal bonding material is placed between the lower surface of the upper MMC disc member 131 and the upper surface of the lower MMC disc member 136, and a metal bonding material is also placed on the upper surface of the upper MMC disc member 131. Each metal bonding material is provided with through holes that communicate with through holes 134 and 138. The power supply terminals 54 of the ceramic substrate 20 are inserted into the through holes 134 and 138 of the MMC disc members 131 and 136, and the ceramic substrate 20 is placed on top of the metal bonding material placed on the upper surface of the upper MMC disc member 131. This results in a laminate in which the lower MMC disc member 136 and the metal bonding material, the upper MMC disc member 131 and the metal bonding material, and the ceramic substrate 20 are stacked in this order from bottom to top. By heating and pressurizing this laminate (TCB), a bonded body 305 is obtained (Figure 5H). The bonded body 305 is formed by bonding a ceramic substrate 20 to the upper surface of a conductive substrate 30 via a first bonding layer 46, which is a metal bonding layer.

[0045] Next, an adhesive sheet, which will become the second bonding layer 248, is placed on the upper surface of the support base material 240. The adhesive sheet is provided with through holes that communicate with through holes 134, 138, and 243, and a through hole that communicates with through hole 245. The power supply terminal 54 of the bonded body 305 is inserted into the through hole 243 of the support base material 240, and the bonded body 305 is placed on the adhesive sheet placed on the upper surface of the support base material 240. This results in a laminate in which the support base material 240, adhesive sheet, and bonded body 305 are stacked in this order from bottom to top. This laminate is heated and pressurized by a vacuum press to harden the adhesive sheet, and the bonded body 305 and the support base material 240 are joined by the second bonding layer 248, which is an insulating layer, to obtain the bonded body 310 (Figure 5I).

[0046] Next, insulating tubes 55 for inserting power supply terminals 54 are placed in through holes 134, 138, 243 and in holes in the metal bonding material and adhesive sheet. In addition, insulating tubes 65 for inserting power supply terminals 64 are placed in through hole 245 and in holes in the adhesive sheet. Furthermore, insulating film 50 is formed by thermal spraying ceramic powder onto the side surface of the ceramic substrate 20, the periphery of the first bonding layer 46, the side surface of the conductive substrate 30, the periphery of the second bonding layer 248, and the upper and side surfaces of the mounting flange 242 of the support substrate 240 (Figure 5J). This gives rise to the wafer mounting table 210. In the second embodiment, some or all of the insulating film 50 provided on the side surface of the ceramic substrate 20 and the periphery of the second bonding layer 248 may be omitted. The timing of forming the insulating film 50 may be before forming the bonded body 310; for example, the insulating film 50 may be formed on the bonded body 305 and the support substrate 240 respectively before joining them together.

[0047] This wafer mounting platform 210 can be used in the same way as the wafer mounting platform 10.

[0048] In the wafer mounting stage 210 described above, the portion of the support base material 240 that extends radially outward from the conductive base material 30 is used as a mounting flange 242. However, since the support base material 240 is bonded to the conductive base material 30 via a second bonding layer 248, which is an insulating layer, it is electrically insulated from the conductive base material 30. Therefore, the mounting flange 242 does not function as a plasma generation electrode, and plasma generation in the region directly above the mounting flange 242 is suppressed. As a result, the plasma density in the region directly above the ceramic base material 20 can be increased.

[0049] Furthermore, since a second bonding layer 248, which is an insulating layer, is provided between the support base material 240 and the conductive base material 30, the support base material 240 and the conductive base material 30 can be electrically insulated even if the support base material 240 is made of metal. Also, since the support base material 240 is made of metal, i.e., a ductile material, screw holes 244 can be provided on the lower surface of the support base material 240. Because screw holes 244 can be provided on the lower surface of the support base material 240, the wafer mounting table 210 can also be attached to the mounting plate 96 at the central part 241 of the support base material 240.

[0050] It goes without saying that the present invention is not limited in any way to the embodiments described above, and can be implemented in various forms as long as they fall within the technical scope of the present invention.

[0051] For example, in the first and second embodiments described above, the conductive substrate 30 has a refrigerant flow path 32 inside, but it is not limited to this. For example, as shown in Figure 6, the conductive substrate 30 may have a refrigerant flow path groove 34 on its lower surface, and the lower opening of the refrigerant flow path groove 34 may be closed by a second bonding layer 48 arranged on the lower side of the conductive substrate 30 to form a refrigerant flow path 32. In this case, the material on the lower side of the refrigerant flow path 32 (MMC disc member 136) is not required compared to the case in which the conductive substrate 30 has a refrigerant flow path 32 inside, and thus the manufacturing cost can be reduced. In Figure 6, the same reference numerals are used for the same components as in the embodiments described above. Also, for example, the conductive substrate 30 may have a refrigerant flow path groove on its upper surface, or it may not have a refrigerant flow path or a refrigerant flow path groove.

[0052] In the first and second embodiments described above, holes may be provided that penetrate the wafer mounting bases 10 and 210 from the lower surface of the conductive substrate 30 to the wafer mounting surface 22a. Examples of such holes include gas supply holes for supplying a thermal conductive gas (e.g., He gas) to the back surface of the wafer W, and lift pin holes for inserting lift pins to move the wafer W up and down relative to the wafer mounting surface 22a. The thermal conductive gas is supplied to the space formed by the wafer W and a number of small protrusions (not shown) provided on the wafer mounting surface 22a (which support the wafer W). If the wafer W is supported by, for example, three lift pins, three lift pin holes are provided. Between the lower surface of the support substrates 40 and 240 and the upper surface of the mounting plate 96, resin or metal sealing rings (e.g., O-rings) may be placed at positions opposite to these holes.

[0053] In the first and second embodiments described above, the wafer adsorption electrode 26 is embedded in the ceramic substrate 20, but a heater electrode (resistive heating element) may be embedded instead or in addition to the electrode. In this case, a heater power supply is connected to the heater electrode. The ceramic substrate 20 may have one layer of electrodes embedded, or it may have two or more layers embedded with gaps in between.

[0054] In the first and second embodiments described above, the ceramic substrate 20 and the conductive substrate 30 were joined by a first bonding layer 46 which is a metal bonding layer, but the first bonding layer 46 may be a resin bonding layer.

[0055] In the first embodiment described above, the second bonding layer 48 was a metal bonding layer, but the second bonding layer 48 may also be a resin bonding layer.

[0056] In the first embodiment described above, the upper end of the power supply terminal 64 is in contact with the lower surface of the conductive substrate 30. However, if the second bonding layer 48 is a metal bonding layer, the upper end of the power supply terminal 64 may be in contact with the lower surface of the second bonding layer 48. In that case, the through hole for inserting the power supply terminal 64 (a through hole communicating with the through hole 45) in the second bonding layer 48 or the metal bonding material from which it is based can be omitted.

[0057] In the second embodiment described above, the support base material 240 is provided with screw holes 244 and through holes 246, but one or both of these may be omitted. Alternatively, instead of providing through holes 246, the mounting flange 242 may be attached to the mounting plate 96 using a clamp member 70, as in the first embodiment. Furthermore, the screw holes 244 may be formed on the lower surface of the mounting flange 242 instead of the lower surface of the central portion 241.

[0058] In the first and second embodiments described above, the ceramic substrate 20 was manufactured by hot-press firing a molded body of ceramic powder. However, the molded body may be manufactured by stacking multiple tape molded bodies, by a mold-casting method, or by compressing ceramic powder. The same applies to the support substrate 40 in the first embodiment. [Explanation of Symbols]

[0059] 10 Wafer mounting stage, 20 Ceramic substrate, 22a Wafer mounting surface, 26 Wafer adsorption electrode, 27 Hole, 30 Conductive substrate, 32 Coolant flow path, 40 Support substrate, 41 Central part, 42 Mounting flange, 43 Through hole, 45 Through hole, 46 First bonding layer, 48 Second bonding layer, 50 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, 65 Insulating tube, 70 Clamp member, 70a Inner circumferential step surface, 72 Bolt, 94 Chamber, 96 Mounting plate, 98 Shower head, 110 Bonding body, 131,136 MMC disc member, 132 Groove, 134,138 Through hole, 135 Metal bonding layer, 210 Wafer mounting base, 240 support base, 241 central section, 242 mounting flange, 243 through hole, 244 screw hole, 245 through hole, 246 through hole, 248 second bonding layer, 274 bolt, 276 bolt, 278 seal ring, 305 bonded body, 310 bonded body.

Claims

1. a ceramic substrate having a wafer mounting surface on its upper surface and incorporating an electrode; a conductive substrate provided on the lower surface side of the ceramic substrate, having a coolant flow path or a coolant flow path groove, and also serving as a plasma generating electrode, the conductive substrate having the same diameter as the ceramic substrate; a support substrate provided on a lower surface side of the conductive substrate, the support substrate having a larger diameter than the conductive substrate and being electrically insulated from the conductive substrate; a mounting flange that is a portion of the support substrate that protrudes radially outward from the conductive substrate; A wafer mounting table comprising:

2. The supporting substrate is formed of an insulating material. The wafer stage according to claim 1 .

3. a first bonding layer bonding the ceramic substrate and the conductive substrate and a second bonding layer bonding the conductive substrate and the support substrate are both metal bonding layers; The wafer stage according to claim 2 .

4. the conductive substrate has the coolant flow channel; the coolant flow channel has an opening on a surface of the conductive base material facing the support base material. The wafer stage according to claim 2 or 3.

5. the supporting substrate is formed of a metal, and an insulating layer is provided between the supporting substrate and the conductive substrate; The wafer stage according to claim 1 .

6. A screw hole is provided on the lower surface of the support substrate. The wafer stage according to claim 5 .

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