Wafer carrying table

Abstract

An upper base material (20) of a wafer mounting table (10) is provided with a ceramic base material (21) in which an electrode (22) is built, and the upper surface of the ceramic base material (21) is provided with a wafer mounting surface (21a). The lower base material (30) is disposed on the lower surface side of the upper base material (20), and is provided with a refrigerant flow path (35). The through hole 36 passes through the lower base 30 in the vertical direction. The protrusions (38) are provided in a dot shape on the entire upper surface of the lower base material (30) and come into contact with the lower surface of the upper base material (20). The fins (40) have protrusion insertion holes (44) into which the protrusions (38) are inserted, and are disposed in a compressed state between the upper base material (20) and the lower base material (30). A screw hole (24) is provided in the lower surface of the upper base material (20) at a position facing the through hole (36), and a screw member (50) is inserted into the through hole (36) from the lower surface of the lower base material (30) and screwed into the screw hole (24).

Description

Technical Field The present invention relates to a wafer loading platform. Background Art In the past, there is known a wafer carrier, which includes: a ceramic substrate having a wafer carrier surface and having electrodes built therein; and a metal plate, which is arranged on the surface of the ceramic substrate opposite to the wafer carrier surface. Patent document 1 discloses: on the basis of the above-mentioned wafer carrier, a plurality of through holes are provided in the metal plate, and screw holes are provided at positions opposite to each through hole on the lower surface of the ceramic substrate, and screw components are inserted into each through hole from the lower surface of the metal plate and screwed into the screw holes, so that the ceramic substrate and the metal plate are fastened. A non-adhesive heat conduction sheet (a type of heat sink) is arranged between the ceramic substrate and the metal plate. The heat conduction sheet plays a role in transferring the heat of the ceramic substrate to the metal plate. Prior art literature Patent Literature Patent Document 1: International Publication No. 2018 / 038044 Pamphlet Summary of the invention In Patent Document 1, when manufacturing a wafer stage, the heat-conducting sheet needs to be positioned to avoid the terminal holes, etc., and since there is no mechanism for positioning the heat-conducting sheet, the heat-conducting sheet may deviate from its original position. In addition, the compression amount (or even the thermal conductivity) of the heat-conducting sheet depends on the tightening conditions of each screw component, so if there is a deviation in the tightening conditions of each screw component, the thermal uniformity of the wafer may sometimes deteriorate. The present invention has been made to solve the above-mentioned problems, and its main object is to facilitate the positioning of a heat sink when manufacturing a wafer placing table and to improve the thermal uniformity of the wafer.

[0001] The wafer loading platform of the present invention comprises: An upper substrate, the upper substrate comprising a ceramic substrate having electrodes built therein, and a wafer placement surface on an upper surface of the ceramic substrate; a lower substrate, which is arranged on the lower surface side of the upper substrate and has a refrigerant flow path for circulating the refrigerant or a refrigerant flow path groove constituting the side wall and the bottom of the refrigerant flow path; a through hole, the through hole penetrating the lower substrate in a vertical direction; a plurality of protrusions, the plurality of protrusions being arranged in a dotted pattern on the entire upper surface of the lower substrate and abutting against the lower surface of the upper substrate, or being arranged in a dotted pattern on the entire lower surface of the upper substrate and abutting against the upper surface of the lower substrate; a heat sink having a protrusion insertion hole into which the protrusion is inserted and arranged in a compressed state between the upper substrate and the lower substrate; a screw hole provided at a position on the lower surface of the upper substrate opposite to the through hole; and A screw component is inserted into the through hole from the lower surface of the lower substrate and screwed into the screw hole. In the wafer carrier, the heat sink has a plurality of protrusion insertion holes for inserting the plurality of protrusions. When manufacturing the wafer carrier, the protrusions that are arranged in a dot shape on the entire upper surface of the lower substrate or the entire lower surface of the upper substrate are inserted into the protrusion insertion holes of the heat sink, so that the heat sink is easily positioned. In addition, the threaded component is screwed in until the interval between the upper substrate and the lower substrate is consistent with the height of the protrusion. Accordingly, the heat sink arranged between the upper substrate and the lower substrate is compressed to a thickness that is the same as or approximately the same as the height of the protrusion as a whole. Therefore, the thermal conductivity of the heat sink does not change significantly depending on the position. Therefore, the thermal uniformity of the wafer is improved. It should be noted that in this specification, up and down, left and right, front and back, etc. are sometimes used to explain the present invention, but up and down, left and right, front and back are only relative positional relationships. Therefore, when the orientation of the wafer stage is changed, up and down may become left and right or left and right may become up and down, and such a situation is also included in the technical scope of the present invention.

[0002] In the wafer stage (wafer stage described in [1]), the upper substrate may include: the ceramic substrate and a support substrate made of metal or a metal-ceramic composite material bonded to the lower surface of the ceramic substrate via a metal bonding layer, and the screw hole may be provided on the lower surface of the support substrate. Accordingly, since the support substrate is made of metal or a metal-ceramic composite material, it has excellent thermal conductivity compared to the ceramic substrate. Therefore, the heat of the ceramic substrate can be efficiently transferred to the lower substrate.

[0003] In the wafer stage (the wafer stage described in [1] or [2]), the through hole can be provided to penetrate the protrusion. Accordingly, it is not necessary to provide a connecting hole connected to the through hole in the heat sink, so that the function of the heat sink is fully utilized.

[0004] In the wafer placement table (the wafer placement table described in any one of [1] to [3]), the heat sink may have a thermal resistance of 0.35 K·cm 2 / W or less. Accordingly, the heat of the upper substrate is quickly transferred to the lower substrate.

[0005] In the wafer stage (the wafer stage described in any one of [1] to [4]), the heat sink may have a Young's modulus of 100 MPa or less. This allows the tightening force of the screw member to be easily transmitted evenly over the entire surface of the heat sink, so that the heat sink is firmly adhered to the upper substrate and the lower substrate over its entire surface.

[0006] In the wafer placement table (the wafer placement table described in any one of [1] to [5]), the through hole may be arranged so as not to intersect the coolant flow path or the coolant flow path groove. Thus, the coolant does not leak from the through hole into which the threaded member is inserted.

[0007] In the above-mentioned wafer carrier (the wafer carrier described in any one of [1] to [5] above), the through hole can be arranged to intersect with the coolant flow path or the coolant flow path groove, and the lower substrate can have a coolant leakage prevention component, which prevents the coolant from leaking from the through hole into which the threaded component is inserted to the lower surface of the lower substrate. Accordingly, it is not necessary to bypass the threaded component to set the coolant flow path, and thus the design freedom of the coolant flow path or the coolant flow path groove is improved. In addition, the coolant leakage component is used to prevent the coolant from leaking from the through hole into which the threaded component is inserted.

[0008] In the wafer placement table (the wafer placement table described in any one of [1] to [7]), the lower substrate may be made of an easily machinable material. Thus, a coolant flow path or a coolant flow path groove can be easily formed in the lower substrate, thereby reducing the processing cost.

[0009] In the wafer placement table (the wafer placement table described in any one of [1] to [8]), a heat conductive paste may be sandwiched between at least one of the side surface of the protrusion and the inner peripheral surface of the protrusion insertion hole of the heat sink and between the top surface of the protrusion and the lower surface of the upper substrate. Thus, heat conduction from the upper substrate to the lower substrate is promoted. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 It is a longitudinal cross-sectional view of the wafer stage 10 installed in the chamber 94 . Figure 2 It is a plan view of the wafer stage 10 . Figure 3 This is a cross-sectional view when a cut plane obtained by horizontally cutting the wafer stage 10 at the heat sink 40 is viewed from above. Figure 4 It is a manufacturing process diagram of the wafer stage 10 (manufacturing process of the upper substrate 20 ). Figure 5 It is a manufacturing process diagram of the wafer stage 10 (manufacturing process of the lower substrate 30 ). Figure 6 It is a manufacturing process diagram of the wafer stage 10 (assembly process of the wafer stage 10). Figure 7 This is a partially enlarged cross-sectional view of another example in which the through hole 36 is provided so as to penetrate the protrusion 38 . Figure 8 It is a longitudinal cross-sectional view of the wafer placement table 110 . Fig. 9 It is a longitudinal cross-sectional view of the wafer placement table 210 . Fig.10 It is a longitudinal cross-sectional view of the wafer placement table 310 . Fig.11 It is a manufacturing process diagram of the wafer placement table 410. DETAILED DESCRIPTION Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 1 is a longitudinal cross-sectional view of the wafer stage 10 provided in the chamber 94 (a cross-sectional view when cut along a plane including the central axis of the wafer stage 10). Figure 2 is a plan view of the wafer stage 10, Figure 3 This is a cross-sectional view when a cut plane obtained by horizontally cutting the wafer stage 10 at the heat sink 40 is viewed from above. The wafer stage 10 is a component used to perform CVD, etching, etc. on the wafer W using plasma, and is fixed to a setting plate 96 provided inside a chamber 94 for semiconductor processes. The wafer stage 10 includes an upper substrate 20, a lower substrate 30, a heat sink 40, and a screw member 50. The upper substrate 20 includes: a ceramic substrate 21; a support substrate 23 disposed on the lower side of the ceramic substrate 21; and a metal bonding layer 25 bonding the ceramic substrate 21 and the support substrate 23. In consideration of strength, the thickness of the upper substrate 20 is preferably 8 mm or more and 10 mm or more; in consideration of cooling efficiency, the thickness is preferably 25 mm or less. The ceramic substrate 21 has a circular wafer loading surface 21a. A wafer W is loaded on the wafer loading surface 21a. The ceramic substrate 21 is formed of a ceramic material represented by aluminum oxide, aluminum nitride, etc. The ceramic substrate 21 has a built-in wafer adsorption electrode 22 on the side close to the wafer loading surface 21a. The wafer adsorption electrode 22 is formed of a material containing, for example, W, Mo, WC, MoC, etc. The wafer adsorption electrode 22 is a disk-shaped or mesh-shaped monopolar electrostatic electrode. The layer of the ceramic substrate 21 that is higher than the wafer adsorption electrode 22 functions as a dielectric layer. The wafer adsorption DC power supply 52 is connected to the wafer adsorption electrode 22 via a power supply terminal 54. The power supply terminal 54 is configured to reach the wafer adsorption electrode 22 from the lower surface of the ceramic substrate 21 through an insulating tube 55 arranged in a hole that penetrates the lower substrate 30, the support substrate 23, and the metal bonding layer 25 in the up-down direction. A low-pass filter (LPF) 57 is provided between the wafer adsorption DC power supply 52 and the wafer adsorption electrode 22 . The supporting substrate 23 is a circular plate that is one size larger than the ceramic substrate 21 and is made of a conductive material. As conductive materials, for example, composite materials, metals, etc. can be cited. As composite materials, composite materials of metals and ceramics can be cited. As composite materials of metals and ceramics, metal matrix composites (MMC), ceramic matrix composites (CMC), etc. can be cited. Specific examples of the above composite materials include materials containing Si, SiC and Ti, materials obtained by impregnating Al and / or Si into a SiC porous body, etc. The material containing Si, SiC and Ti is called SiSiCTi, the material obtained by impregnating Al into a SiC porous body is called AlSiC, and the material obtained by impregnating Si into a SiC porous body is called SiSiC. As metals, Mo and the like can be cited. The absolute value of the difference in linear thermal expansion coefficient between the material used for the supporting substrate 23 and the ceramic material used for the ceramic substrate 21 at 40 to 400°C is preferably 1.5×10 -6 / K or less, more preferably 1.0×10 -6 / K or less, more preferably 0.5×10 -6 Considering the strength, the thickness of the support substrate 23 is preferably 3 mm or more and 6 mm or more; considering the cooling efficiency, the thickness is preferably 20 mm or less. A plurality of screw holes 24 are provided on the lower surface of the support substrate 23. The screw holes 24 are provided at positions opposite to the through holes 36 described later. The screw holes 24 are formed by providing a cylindrical hole on the lower surface of the support substrate 23 and directly providing a thread groove in the cylindrical hole, but are not particularly limited thereto. For example, a spiral screw sleeve can be inserted into a cylindrical hole to form the screw hole 24, or a terminal with an internal thread (such as a bag nut, etc.) of Patent Document 1 can be inserted into a cylindrical hole and brazed to form the screw hole 24. The center interval between two adjacent screw holes 24 is not particularly limited, and is preferably, for example, less than 100 mm. The metal bonding layer 25 bonds the lower surface of the ceramic substrate 21 and the upper surface of the support substrate 23. The metal bonding layer 25 may be, for example, a layer formed of solder or metal brazing material. For example, the metal bonding layer 25 is formed by TCB (Thermal compression bonding). TCB refers to a well-known method of sandwiching a metal bonding material between two components to be bonded, and bonding the two components under pressure while heating them to a temperature below the solidus temperature of the metal bonding material. The lower substrate 30 is a disc member made of a material that is easy to process. In the present embodiment, the outer diameter of the lower substrate 30 is the same as the outer diameter of the supporting substrate 23. The lower substrate 30 is built with a coolant flow path 35. The coolant flow path 35 is formed into a vortex shape from the inlet 35a to the outlet 35b of the coolant flow path 35 in a one-stroke manner in the entire area where the ceramic substrate 21 is configured. The inlet 35a is arranged on the outer peripheral side of the wafer carrier 10, and the outlet 35b is arranged on the central side of the wafer carrier 10. The inlet 35a and the outlet 35b are connected to a coolant cooling device not shown in the figure, and the coolant discharged from the outlet 35b is adjusted to a specified low temperature in the coolant cooling device, and then returns to the inlet 35a again and is supplied to the coolant flow path 35. The coolant circulating in the coolant flow path 35 is preferably a liquid, and preferably electrically insulating. As an electrically insulating liquid, for example, a fluorine-based inactive liquid can be cited. The easy-to-process material used for the lower substrate 30 is preferably a material that is easier to process than the supporting substrate 23. As an index of processability, for example, the machinability index given in JIS B 0170 (2020) can be used. As an easy-to-process material, a material with a machinability index of 40 or more is preferred, a material with a machinability index of 100 or more is more preferred, and a material with a machinability index of 140 or more is further preferred. Examples of easy-to-process materials include aluminum, aluminum alloys, stainless steel (SUS materials), and the like. The lower substrate 30 is connected to the RF power supply 62 via the power supply terminal 64. Therefore, the lower substrate 30 also functions as a high frequency (RF) electrode for plasma generation. A high pass filter (HPF) 63 is disposed between the lower substrate 30 and the RF power supply 62. The lower substrate 30 has a plurality of through holes 36. The through holes 36 are holes for inserting the screw member 50, and penetrate the lower substrate 30 in the vertical direction without intersecting the coolant flow path 35. The through holes 36 have a large diameter portion 36a for accommodating the head 50a of the screw member 50, and a small diameter portion 36b for the foot 50b of the screw member 50 to pass through but the head 50a cannot pass through. Figure 3 As shown, a plurality of protrusions 38 are arranged in a dotted shape on the upper surface of the lower substrate 30 as a whole. At least one of the plurality of protrusions 38 is arranged directly above the inlet 35a of the refrigerant flow path 35. The protrusion 38 can be, for example, a flat cylindrical protrusion. The top surface of the protrusion 38 abuts against the lower surface of the upper substrate 20 (i.e., the lower surface of the supporting substrate 23). The height of the protrusion 38 is preferably, for example, not less than 0.05 mm and not more than 1 mm, and more preferably not less than 0.1 mm and not more than 0.5 mm. The protrusions 38 are preferably arranged not in a straight line in the radial direction of the upper surface of the lower substrate 30. The heat sink 40 is arranged between the lower surface of the upper substrate 20 and the upper surface of the lower substrate 30. The heat sink 40 has a protrusion insertion hole 44 at a position opposite to each of the plurality of protrusions 38. The protrusion insertion hole 44 is a hole that penetrates the heat sink 40 in the up-down direction. The protrusion 38 is inserted into the protrusion insertion hole 44. The thickness of the heat sink 40 before being assembled on the wafer stage 10 is greater than the height of the protrusion 38, but the thickness of the heat sink 40 after being assembled on the wafer stage 10 is the same or substantially the same as the height of the protrusion 38. Therefore, the heat sink 40 is sandwiched between the upper substrate 20 and the lower substrate 30 and is compressed in the up-down direction. Accordingly, the heat sink 40 is firmly adhered to the lower surface of the upper substrate 20 and the upper surface of the lower substrate 30, so that the heat of the upper substrate 20 is quickly conducted to the lower substrate 30. The heat sink 40 preferably has electrical conductivity. The thermal resistance of the heat sink 40 is preferably 0.35K·cm 2 / W or less, more preferably 0.1K·cm 2 / W or less. The Young's modulus of the heat sink 40 is preferably 100 MPa or less, more preferably 20 MPa or less, and further preferably 5 MPa or less. For example, the thermal resistance can be measured according to ASTM D5470. The heat sink 40 has no or almost no adhesiveness. Specifically, the heat sink 40 is preferably a sheet containing carbon and resin. Examples of carbon include graphite, carbon fiber, carbon nanotubes, etc.; examples of resin include silicone resins, etc. In the case of graphite, it is preferably configured in a manner that the surface direction of graphene constituting the graphite is along the up-down direction; in the case of carbon fiber and carbon nanotubes, it is preferably configured in a manner that the axial direction is along the up-down direction. As a material for the heat sink 40, for example, a thermal interface material (TIM) can be used. Specific examples of the heat sink 40 include EX20000C4S (manufactured by Dexerials), GraphitePAD, GraphiteTIM (registered trademark) (all manufactured by Panasonic), etc. The Poisson's ratio of the heat sink 40 is preferably less than 0.4, more preferably less than 0.3, and further preferably less than 0.2. The smaller the Poisson's ratio of the heat sink 40 is, the more evenly the fastening force of the screw member 50 is transmitted over the entire surface of the heat sink 40, and the less likely it is to escape in the lateral direction. Therefore, the heat sink 40 is firmly attached to the support substrate 23 and the lower substrate 30 over its entire surface. Therefore, the wafer W can be cooled more uniformly. The Shore hardness (ShoreOO) of the heat sink 40 can be 50 or more and 80 or less. like Figure 1As shown in the enlarged view of , the threaded component 50 has a head portion 50a with a large diameter and a foot portion 50b with a small diameter. The threaded component 50 is inserted from the lower surface of the lower substrate 30 into the through hole 36 which is arranged not to intersect with the refrigerant flow path 35, and is screwed into the screw hole 24 of the supporting substrate 23. The threaded component 50 is screwed into the screw hole 24 until the top surface of the protrusion 38 of the lower substrate 30 contacts the lower surface of the upper substrate 20. As a result, the head portion 50a of the threaded component 50 presses the step surface 36c (the boundary between the large diameter portion 36a and the small diameter portion 36b) of the through hole 36 upward. In addition, the supporting substrate 23 of the upper substrate 20 and the lower substrate 30 are fastened in a state where the heat sink 40 is sandwiched therebetween, and the heat sink 40 is compressed in the up and down directions. The head portion 50a of the threaded component 50 is housed in the large diameter portion 36a in a manner that does not protrude downward from the lower surface of the lower substrate 30. In the present embodiment, as Figure 3 As shown, the threaded member 50 is arranged along a plurality of (here, three) circles ( Figure 3 The material of the screw member 50 is preferably a material with good electrical and thermal conductivity, such as stainless steel. It should be noted that the side (peripheral surface) of the metal bonding layer 25, the upper surface and side of the supporting substrate 23, and the side of the lower substrate 30 can be coated with an insulating film as needed. As the insulating film, for example, a sprayed film of aluminum oxide, yttrium trioxide, etc. can be cited. In addition, a metal or resin O-ring can be arranged in a manner surrounding the periphery of the heat sink 40. The O-ring is compressed in the up-down direction between the upper substrate 20 and the lower substrate 30, thereby exerting sealing properties. Accordingly, the heat sink 40 is protected by the O-ring. Next, use Figures 4 to 6 , a manufacturing example of the wafer placement table 10 is described. Figures 4 to 6 FIG. 1 is a manufacturing process diagram of the wafer placement table 10. Figure 4 2 shows the manufacturing process of the upper substrate 20. Figure 5 2 shows the manufacturing process of the lower substrate 30. Figure 6 The following is a diagram showing the assembly process of the wafer stage 10 . For example, the upper substrate 20 is manufactured as follows. First, a molded body of ceramic powder is hot-pressed and fired to manufacture a ceramic substrate 21 ( Figure 4 (A)). The ceramic substrate 21 has a wafer adsorption electrode 22 built therein. Next, a hole 21b is provided from the lower surface of the ceramic substrate 21 to the wafer adsorption electrode 22 ( Figure 4 (B)), the power supply terminal 54 is inserted into the hole 21b, and the power supply terminal 54 and the chip adsorption electrode 22 are joined ( Figure 4 (C)). At the same time, a disc-shaped supporting substrate 23 ( Figure 4(D)), a hole 23b is formed in the support base 23 to penetrate in the vertical direction, and a screw hole 24 is formed at a predetermined position on the lower surface of the support base 23 ( Figure 4 (E)). The hole 23b of the support substrate 23 is formed at a position that can communicate with the hole 21b of the ceramic substrate 21. When the ceramic substrate 21 is made of alumina, the support substrate 23 is preferably made of SiSiCTi or AlSiC. This is because: if it is SiSiCTi or AlSiC, the thermal expansion coefficient can be made substantially the same as the thermal expansion coefficient of alumina. For example, the support substrate 23 made of SiSiCTi can be made as follows. First, silicon carbide, metal Si and metal Ti are mixed to make a powder mixture. Next, the obtained powder mixture is molded by uniaxial pressure molding to make a disk-shaped molded body, and the molded body is hot-pressed and sintered in an inert atmosphere to obtain the support substrate 23 made of SiSiCTi. Next, a circular metal bonding material is arranged on the upper surface of the supporting substrate 23. A hole connected to the hole 23b of the supporting substrate 23 is pre-set in the metal bonding material. Then, the power supply terminal 54 of the ceramic substrate 21 is inserted into the hole of the metal bonding material and the hole 23b of the supporting substrate 23, and the ceramic substrate 21 is placed on the metal bonding material. Thus, a stacked body is obtained in which the supporting substrate 23, the metal bonding material and the ceramic substrate 21 are stacked in this order starting from the bottom. The stacked body is heated and pressurized (TCB) to obtain the upper substrate 20 ( Figure 4 (F) The upper substrate 20 is obtained by bonding a ceramic substrate 21 to the upper surface of a support substrate 23 via a metal bonding layer 25 . For example, TCB is performed as follows. That is, the stack is pressurized and bonded at a temperature below the solidus temperature of the metal bonding material (for example, a temperature above the solidus temperature minus 20°C and below the solidus temperature), and then returned to room temperature. Accordingly, the metal bonding material becomes a metal bonding layer (or a conductive bonding layer). As the metal bonding material at this time, Al-Mg bonding materials and Al-Si-Mg bonding materials can be used. For example, in the case of TCB using Al-Si-Mg bonding materials, the stack is pressurized in a heated state under a vacuum atmosphere. The metal bonding material preferably uses a material with a thickness of about 100 μm. In addition, at the same time as the upper substrate 20 is manufactured, the lower substrate 30 is manufactured using, for example, an easily machinable material as follows. First, two disk-shaped disk members 31 and 32 ( Figure 5(A)). The disk members 31 and 32 are preferably made of aluminum, aluminum alloy or stainless steel. Next, a groove 35c (which will eventually become the coolant flow path 35) is formed on the lower surface of the upper disk member 31. Figure 5 (B)). Then, the lower surface of the upper disk member 31 and the upper surface of the lower disk member 32 are bonded together using a bonding material (such as brazing material, etc.) not shown in the figure, thereby manufacturing the lower substrate 30 ( Figure 5 (C)). Then, an inlet 35a and an outlet 35b are formed to penetrate from the lower surface of the lower substrate 30 to the bottom surface of the coolant flow path 35 in the vertical direction, and a terminal hole 30b is formed to penetrate the lower substrate 30 in the vertical direction. In addition, a through hole 36 having a large diameter portion 36a and a small diameter portion 36b is formed at a predetermined position of the lower substrate 30, and a plurality of protrusions 38 are formed on the entire upper surface of the lower substrate 30 ( Figure 5 (D)). Next, if Figure 6 (A) and Figure 6 As shown in (B), a heat sink 40 is arranged on the upper surface of the lower substrate 30. The heat sink 40 is a circular sheet having the same diameter as the lower substrate 30. The heat sink 40 has a protrusion insertion hole 44 that penetrates the heat sink 40 in the up-down direction at a position opposite to the plurality of protrusions 38, and has holes 46 and 47 that penetrate the heat sink 40 in the up-down direction at a position opposite to the small diameter portion 36b of the through hole 36 and a position opposite to the terminal hole 30b. By inserting the protrusion 38 into the protrusion insertion hole 44, the heat sink 40 is positioned in such a manner that the hole 46 is opposite to the small diameter portion 36b and the hole 47 is opposite to the terminal hole 30b. In this state, the thickness of the heat sink 40 is greater than the height of the protrusion 38. In addition, there is a gap between the inner peripheral surface of the protrusion insertion hole 44 and the outer peripheral surface of the protrusion 38. Next, the power supply terminal 54 of the upper substrate 20 is inserted into the terminal hole 30b, and the upper substrate 20 is placed on the heat sink 40 arranged on the upper surface of the lower substrate 30. Next, the screw component 50 is inserted into each through hole 36 from the lower surface of the lower substrate 30 and screwed into the screw hole 24 of the support substrate 23. The screw component 50 is screwed in until the protrusion 38 contacts the lower surface of the support substrate 23. Accordingly, the heat sink 40 is compressed roughly evenly between the support substrate 23 and the lower substrate 30, and exhibits high thermal conductivity. After that, an insulating tube 55 ( Figure 6 (C)). Thus, the wafer placement table 10 can be obtained. Next, use Figure 1, an example of using the wafer carrier 10 is described. First, the wafer carrier 10 is set on the setting plate 96 of the chamber 94. Specifically, first, the sealing components 80, 82a, and 82b are arranged between the upper surface of the setting plate 96 and the lower surface of the lower substrate 30. The sealing component 80 is a metal or resin ring whose outer diameter is slightly smaller than the diameter of the lower substrate 30, and can be compressed in the up and down directions. The sealing components 82a and 82b are metal or resin rings arranged along the opening edges of the inlet 35a and the outlet 35b of the coolant flow path 35, and can be compressed in the up and down directions. Next, the threaded component 70 is screwed into the screw hole 39 provided on the lower surface of the lower substrate 30 through the screw insertion hole 97 from the lower surface of the setting plate 96. Accordingly, the sealing components 82a and 82b are compressed in the up and down directions, exerting sealing properties, thereby preventing the coolant from leaking out of the sealing components 82a and 82b to the outside. A disc-shaped wafer W is placed on the wafer placing surface 21a of the wafer placing table 10 provided on the setting plate 96. In this state, a DC voltage of a DC power supply 52 for wafer adsorption is applied to the wafer adsorption electrode 22, so that the wafer W is adsorbed on the wafer placing surface 21a. In addition, a temperature-regulated refrigerant is supplied to the inlet 35a of the refrigerant flow path 35, and the refrigerant is discharged from the outlet 35b. Then, the interior of the chamber 94 is set to a predetermined vacuum atmosphere (or reduced pressure atmosphere), and while a process gas is supplied from the nozzle 98, an RF voltage from an RF power supply 62 is applied to the lower substrate 30. Thus, plasma is generated between the wafer W and the nozzle 98. Then, the wafer W is subjected to CVD film formation or etching using the plasma. In the wafer stage 10 described above, the heat sink 40 has a plurality of protrusion insertion holes 44 for inserting the plurality of protrusions 38. When manufacturing the wafer stage 10, the protrusions 38 provided in a dotted manner on the entire upper surface of the lower substrate 30 are inserted into the protrusion insertion holes 44 of the heat sink 40, so that the heat sink 40 is easily positioned. In addition, the screw member 50 is screwed in until the interval between the upper substrate 20 and the lower substrate 30 is consistent with the height of the protrusion 38. Accordingly, the heat sink 40 arranged between the upper substrate 20 and the lower substrate 30 is compressed to a thickness that is the same as or substantially the same as the height of the protrusion 38 as a whole. Therefore, the thermal conductivity of the heat sink 40 does not vary significantly depending on the position. Therefore, the thermal uniformity of the wafer W is improved. In addition, the upper substrate 20 includes a ceramic substrate 21 and a support substrate 23 made of metal or a metal-ceramic composite material joined to the lower surface of the ceramic substrate 21 via a metal joining layer 25, and the screw hole 24 is provided on the lower surface of the support substrate 23. Since the support substrate 23 is made of metal or a metal-ceramic composite material, it has better thermal conductivity than the ceramic substrate 21. Therefore, the heat of the ceramic substrate 21 can be efficiently conducted to the lower substrate 30. Furthermore, at least one of the plurality of protrusions 38 is disposed directly above the inlet 35a of the coolant flow path 35. In the upper substrate 20, the portion directly above the inlet 35a of the coolant flow path 35 is more easily cooled by the coolant than other portions, and since the protrusion 38 is disposed directly above the inlet 35a of the coolant flow path 35, overcooling caused by the coolant can be suppressed. Furthermore, the through-hole 36 of the lower base member 30 is provided so as not to intersect with the coolant flow path 35. Therefore, the coolant does not leak from the through-hole 36 into which the screw member 50 is inserted. Furthermore, the lower substrate 30 is made of a material that is easy to process. As a result, the coolant flow path 35 and the protrusion 38 can be easily formed on the lower substrate 30, thereby reducing the processing cost. In addition, compared with the case where the lower substrate 30 is formed of a composite material of metal and ceramic (such as MMC, CMC), the material cost can be suppressed to a lower level. The thermal resistance of the heat sink 40 is preferably 0.35K·cm 2 / W or less. Accordingly, the heat of the upper substrate is quickly transferred to the lower substrate. The Young's modulus of the heat sink 40 is preferably 100 MPa or less. Accordingly, the tightening force of the screw component 50 is easily transmitted evenly over the entire surface of the heat sink 40, so that the heat sink 40 is firmly and tightly attached to the upper substrate 20 and the lower substrate 30 with its entire surface. The absolute value of the difference in linear thermal expansion coefficient between the support substrate 23 and the ceramic substrate 21 at 40 to 400° C. is preferably 1.5×10 -6 / K or less. As a result, the thermal expansion difference between the ceramic substrate 21 and the support substrate 23 is small, so that the warping and damage of the upper substrate 20 caused by thermal stress can be suppressed, and the metal bonding layer 25 bonding the ceramic substrate 21 and the support substrate 23 can also be suppressed from being damaged. In addition, the metal bonding layer 25 makes the thermal conduction between the ceramic substrate 21 and the support substrate 23 better than that of the resin. The support substrate 23 is preferably made of a composite material of metal and ceramic. The composite material of metal and ceramic can reduce the absolute value of the difference in linear thermal expansion coefficient between the composite material and the ceramic substrate 21, and has higher toughness than ceramic materials, so it is not easy to break even if thermal stress occurs. In addition, since the composite material has conductivity, it can also be used as an RF electrode. The heat sink 40 is preferably conductive. As a result, the potential of the lower substrate 30 is the same as that of the support substrate 23 and the metal bonding layer 25, so that the support substrate 23 and the metal bonding layer 25 can be used as RF electrodes, and plasma can be easily generated above the wafer W. It should be noted that a conductive screw member 50 can be used to make the lower substrate 30 and the support substrate 23 have the same potential via the screw member 50. It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be implemented in various forms as long as they fall within the technical scope of the present invention. In the above-mentioned embodiment, the through hole 36 penetrating the lower substrate 30 in the vertical direction is provided as the protrusion 38 which does not penetrate the lower substrate 30, but it is not particularly limited to this. Figure 7 As shown, the through hole 36 can be set to pass through the protrusion 38. Accordingly, it is not necessary to connect the connecting hole ( Figure 6 The holes 46 of (A) and (B) are provided in the heat sink 40, so that the function of the heat sink 40 is fully exerted. Figure 7 In the present invention, the same components as those in the above-described embodiment are denoted by the same reference numerals. In the above-mentioned embodiment, the lower substrate 30 has a built-in cooling medium passage 35, but the present invention is not limited thereto. Figure 8 Like the wafer carrier 110 shown in the figure, the lower substrate 130 may have a coolant flow path groove 132 which is open on the upper surface of the lower substrate 130. In this case, the coolant flow path 135 is formed by covering the opening of the coolant flow path groove 132 with the heat sink 40. The coolant flow path groove 132 constitutes the side wall and the bottom of the coolant flow path 135, and the heat sink 40 constitutes the top of the coolant flow path 135. Accordingly, a circular plate member can be processed to form the lower substrate 130. It should be noted that Figure 8 In the present invention, the same components as those in the above-described embodiment are denoted by the same reference numerals. In the above-mentioned embodiment, the upper substrate 20 includes a ceramic substrate 21 and a support substrate 23 bonded to the lower surface of the ceramic substrate 21 via a metal bonding layer 25, and the screw hole 24 is provided on the lower surface of the support substrate 23, but the present invention is not particularly limited thereto. Fig. 9 As shown in the wafer placing table 210, the upper substrate 220 may be formed only by the ceramic substrate 221. In this case, the screw hole 224 for the screw member 50 to be screwed into is provided on the lower surface of the ceramic substrate 221. Fig. 9 In the present invention, the same components as those in the above-described embodiment are denoted by the same reference numerals. In the above-mentioned embodiment, the through hole 36 of the lower substrate 30 is arranged so as not to intersect with the coolant flow path 35, but the present invention is not particularly limited to this. Fig.10As shown in the wafer placement table 310, the through hole 336 can be arranged to intersect with the coolant flow path 35. The through hole 336 has a large diameter portion 336a and a small diameter portion 336b in the same manner as the above-mentioned embodiment. An O-ring 51 made of resin or metal is arranged on the step surface 336c of the through hole 336 (the boundary between the large diameter portion 336a and the small diameter portion 336b). The O-ring 51 is a coolant leakage component, and is compressed in the up and down directions by the step surface 336c of the through hole 336 and the head 50a of the threaded component 50. Accordingly, it is not necessary to bypass the threaded component 50 to set the coolant flow path 35, and therefore, the design freedom of the coolant flow path 35 is improved. In addition, the O-ring 51 is used to prevent the coolant from leaking from the through hole 336 into which the threaded component 50 is inserted to the lower surface of the lower substrate 30. It should be noted that Fig.10 In the embodiment, the same components as those in the above embodiment are denoted by the same reference numerals. Figure 8 In the embodiment, the through hole 36 may be arranged to intersect with the coolant flow path groove 132 . In the above-mentioned embodiment, nothing is filled between the side surface of the protrusion 38 and the inner peripheral surface of the protrusion insertion hole 44 of the heat sink 40, and between the top surface of the protrusion 38 and the lower surface of the upper substrate 20 (the lower surface of the supporting substrate 23), but the present invention is not particularly limited to this. Fig.11 (C) As in the wafer placing table 410, the heat conductive paste 60 can be interposed between the side surface of the protrusion 38 and the inner peripheral surface of the protrusion insertion hole 44 of the heat sink 40, or between the top surface of the protrusion 38 and the lower surface of the upper substrate 20 (the lower surface of the supporting substrate 23). It should be noted that Fig.11 In the embodiment, the same reference numerals are used for the same components as those in the above-mentioned embodiment. Fig.11 As shown in (A), after applying the thermal conductive paste 60 on the top surface of the protrusion 38, Fig.11As shown in (B), the heat sink 40 is arranged on the upper surface of the lower substrate 30. In this state, there is a gap between the inner circumference of the protrusion insertion hole 44 and the outer circumference of the protrusion 38. Next, the power supply terminal 54 of the upper substrate 20 is inserted into the terminal hole 30b, and the upper substrate 20 is placed on the heat sink 40 arranged on the upper surface of the lower substrate 30. Next, the screw component 50 is inserted into each through hole 36 from the lower surface of the lower substrate 30 and screwed into the screw hole 24 of the supporting substrate 23. The screw component 50 is screwed in until the protrusion 38 contacts the lower surface of the supporting substrate 23. According to this, the heat sink 40 is compressed roughly evenly between the supporting substrate 23 and the lower substrate 30, and a high thermal conductivity performance is exerted. At the same time, the thermal conductive paste 60 applied on the top surface of the protrusion 38 enters the gap between the inner circumference of the protrusion insertion hole 44 and the outer circumference of the protrusion 38. Therefore, compared with the case where a void remains in the gap, heat conduction from the upper substrate 20 to the lower substrate 30 is promoted. In addition, a portion of the heat conductive paste 60 remains between the top surface of the protrusion 38 and the supporting substrate 23. Although there are minute irregularities on the top surface of the protrusion 38, the irregularities are filled with the heat conductive paste 60. Therefore, compared with the case where minute irregularities remain directly on the top surface of the protrusion 38, heat conduction from the upper substrate 20 to the lower substrate 30 is promoted. As the heat conductive paste 60, a paste having a thermal conductivity of 0.5 W / mK or more is preferred, a paste having a thermal conductivity of 1 W / K or more is more preferred, and a paste having a thermal conductivity of 2 W / K or more is further preferred. Examples of the paste include Tran-Q clay (thermal conductivity: 2.8 W / mK) from NOK, BERGQUIST TLF 6000HG (thermal conductivity: 6.0 W / mK) from Henkel, and X-23-7921-5 (thermal conductivity: 6.0 W / mK) from Shin-Etsu Chemical. In the above-mentioned embodiment, the protrusions 38 are provided in the form of dots on the entire upper surface of the lower substrate 30, but the present invention is not particularly limited thereto. For example, the protrusions 38 may be provided in the form of dots on the entire lower surface of the upper substrate 20 (the lower surface of the supporting substrate 23) instead of being provided on the upper surface of the lower substrate 30, and the top surface of the protrusions abuts against the upper surface of the lower substrate 30. In this case, the heat sink 40 disposed between the upper substrate 20 and the lower substrate 30 is compressed to a thickness that is the same as or substantially the same as the height of the protrusions. Therefore, the thermal conductivity of the heat sink 40 does not change significantly due to the position, and the thermal uniformity of the wafer W is improved. In the above-mentioned embodiment, the heat sink 40 is exemplified as a heat sink having conductivity, but the heat sink 40 may be an insulating heat sink. In the above-mentioned embodiment, the electrode 22 for wafer adsorption is built into the ceramic substrate 21, but an RF electrode for plasma generation may be built in instead of or in addition to it. In this case, the high-frequency power supply is connected to the RF electrode instead of the lower substrate 30. In addition, the ceramic substrate 21 may have a heater electrode (resistive heating element) built in. In this case, the heater power supply is connected to the heater electrode. The ceramic substrate 21 may have one layer of electrodes built in, or may have two or more layers of electrodes built in. In the above-described embodiment, the coolant flow path 35 is provided in a spiral shape from the inlet 35 a to the outlet 35 b , but the shape of the coolant flow path 35 is not particularly limited. In the above-mentioned embodiment, the ceramic substrate 21 is produced by hot pressing and sintering a ceramic powder molded body. However, the molded body in this case may be produced by stacking multiple pieces of cast-molded bodies, by die casting, or by compacting ceramic powder. In the above embodiment, the lower substrate 30 is made of an easily machinable material, but the present invention is not particularly limited thereto. For example, the lower substrate 30 may be made of a composite material of metal and ceramic. However, if material cost is taken into consideration, it is preferred to use an easily machinable material such as aluminum or aluminum alloy. In the wafer stage 10 of the above-described embodiment, a hole penetrating the wafer stage 10 may be provided from the lower surface of the lower substrate 30 to the wafer placement surface 21a. Examples of the hole include a gas supply hole for supplying a heat-conducting gas (e.g., He gas) to the back surface of the wafer W, and a lift pin hole for inserting a lift pin for moving the wafer W up and down relative to the wafer placement surface 21a. It is preferable to arrange a resin or metal O-ring at a portion where the gas supply hole and the lift pin hole penetrate the heat sink 40. Industrial Applicability The wafer stage of the present invention is used in, for example, a semiconductor manufacturing apparatus. Explanation of symbols 10 wafer placing table, 20 upper substrate, 21 ceramic substrate, 21a wafer placing surface, 21b hole, 22 wafer adsorption electrode, 23 supporting substrate, 23b hole, 24 screw hole, 25 metal bonding layer, 30 lower substrate, 30b terminal hole, 31, 32 circular plate member, 35 coolant flow path, 35a inlet, 35b outlet, 35c groove, 36 through hole, 36a large diameter portion, 36b small diameter portion, 36c step surface, 38 protrusion, 39 screw hole, 40 heat sink, 44 protrusion insertion hole, 46, 47 holes, 50 threaded member, 50a head, 50b foot, 51 O-ring, 52 DC power supply for chip adsorption, 54 power supply terminal, 55 insulating tube, 60 heat conduction paste, 62 RF power supply, 64 power supply terminal, 70 threaded component, 80, 82a, 82b sealing components, 94 chamber, 96 setting plate, 97 screw insertion hole, 98 nozzle, 110 chip loading platform, 130 lower substrate, 132 refrigerant flow path groove, 135 refrigerant flow path, 210 chip loading platform, 220 upper substrate, 221 ceramic substrate, 224 screw hole, 310 chip loading platform, 336 through hole, 336a large diameter portion, 336b small diameter portion, 336c step surface, 410 chip loading platform.

Claims

1. A wafer loading platform, wherein: have: An upper substrate, the upper substrate comprising a ceramic substrate having electrodes built therein, and a wafer placement surface on an upper surface of the ceramic substrate; a lower substrate, which is arranged on the lower surface side of the upper substrate and has a refrigerant flow path for circulating the refrigerant or a refrigerant flow path groove constituting the side wall and the bottom of the refrigerant flow path; a through hole, the through hole penetrating the lower substrate in a vertical direction; a plurality of protrusions, the plurality of protrusions being arranged in a dotted pattern on the entire upper surface of the lower substrate and abutting against the lower surface of the upper substrate, or being arranged in a dotted pattern on the entire lower surface of the upper substrate and abutting against the upper surface of the lower substrate; a heat sink having a protrusion insertion hole into which the protrusion is inserted and arranged in a compressed state between the upper substrate and the lower substrate; a screw hole provided at a position on the lower surface of the upper substrate opposite to the through hole; and A screw component is inserted into the through hole from the lower surface of the lower substrate and screwed into the screw hole.

2. The wafer stage according to claim 1, wherein: The upper substrate includes: the ceramic substrate and a supporting substrate made of metal or metal-ceramic composite material bonded to the lower surface of the ceramic substrate via a metal bonding layer. The screw holes are arranged on the lower surface of the supporting substrate.

3. The wafer stage according to claim 1 or 2, wherein: The through hole is provided to penetrate the protrusion.

4. The wafer stage according to claim 1 or 2, wherein: The thermal resistance of the heat sink is 0.35K·cm 2 / W or less.

5. The wafer stage according to claim 1 or 2, wherein: The heat sink has a Young's modulus of 100 MPa or less.

6. The wafer stage according to claim 1 or 2, wherein: The through hole is provided so as not to intersect the coolant flow path or the coolant flow path groove.

7. The wafer stage according to claim 1 or 2, wherein: The through hole is arranged to intersect with the coolant flow path or the coolant flow path groove, The lower base has a coolant leakage preventing member that prevents the coolant from leaking from the through hole into which the screw member is inserted to the lower surface of the lower base.

8. The wafer stage according to claim 1 or 2, wherein: The lower substrate is made of a material that is easy to process.

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