Wafer carrying table

Abstract

An upper base material (20) of a wafer mounting table (10) is provided with a ceramic base material (21) having built-in electrodes (22), 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 material (30) in the vertical direction. The protrusions (38) are provided in a dot shape over 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 threaded hole (24) is provided in the lower surface of the upper base material (20) at a position facing the through-hole (36), and a threaded member (50) is inserted into the through-hole (36) from the lower surface of the lower base material (30) and screwed into the threaded hole (24). The thermally conductive paste (60) is interposed between the side surfaces of the protrusions (38) and the inner peripheral surfaces of the protrusion insertion holes (44) of the fins (40).

Description

Technical Field

[0001] The present invention relates to a wafer placing table. Background Art

[0002] 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 disposed on the surface of the ceramic substrate opposite to the wafer carrier surface. As disclosed in Patent Document 1, for such a wafer carrier, a plurality of through holes are provided in the metal plate, and threaded holes are provided at positions opposite to the through holes in the lower surface of the ceramic substrate, and threaded components are inserted into the through holes from the lower surface of the metal plate and screwed into the threaded holes, thereby fastening the ceramic substrate and the metal plate. A non-adhesive heat conduction sheet (a type of heat sink) is disposed between the ceramic substrate and the metal plate. The heat conduction sheet serves to transfer heat from the ceramic substrate to the metal plate.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2018 / 038044 Pamphlet Summary of the invention

[0006] In Patent Document 1, when manufacturing a wafer stage, the thermally conductive sheet needs to be positioned to avoid the terminal holes, etc., but since there is no means for positioning the thermally conductive sheet, the thermally conductive sheet may deviate from the original position. In addition, the amount of flattening of the thermally conductive sheet (and thus the thermal conductivity) 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 deteriorate.

[0007] The present invention is made to solve such a problem, and its main purpose is to facilitate the positioning of the heat sink when manufacturing a wafer placing table and to improve the thermal uniformity of the wafer.

[0008] [1] The wafer stage of the present invention comprises:

[0009] 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;

[0010] a lower substrate, the lower substrate being arranged on the lower surface side of the upper substrate and having a refrigerant flow path for circulating the refrigerant or a refrigerant flow path groove having a side wall and a bottom constituting the refrigerant flow path;

[0011] a through hole, the through hole penetrating the lower substrate in a vertical direction;

[0012] A plurality of protrusions, the plurality of protrusions are arranged in a dotted manner on the entire upper surface of the lower substrate and abut against the lower surface of the upper substrate; or are arranged in a dotted manner on the entire lower surface of the upper substrate and abut against the upper surface of the lower substrate;

[0013] 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;

[0014] a threaded hole, the threaded hole being disposed at a position on the lower surface of the upper substrate opposite to the through hole;

[0015] a threaded member inserted into the through hole from the lower surface of the lower substrate and threadedly engaged with the threaded hole; and

[0016] A thermally conductive paste is interposed between at least one of a side surface of the protrusion and an inner peripheral surface of the protrusion insertion hole of the heat sink and a top surface of the protrusion and a lower surface of the upper substrate.

[0017] In the wafer carrier, the heat sink has a plurality of protrusion insertion holes for inserting a plurality of protrusions. When manufacturing the wafer carrier, the protrusions arranged in a dotted manner 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. As a result, the heat sink arranged between the upper substrate and the lower substrate is compressed to a thickness that is the same as the height of the protrusion or a thickness that is substantially the same. Therefore, the thermal conductivity of the heat sink does not vary greatly depending on the position. Furthermore, the thermal conductive paste is between 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 at least one of the lower surface of the upper substrate. Therefore, the upper substrate, the heat sink and the lower substrate can be tightly fitted without gaps as much as possible. Therefore, the thermal uniformity of the wafer is improved.

[0018] It should be noted that in this specification, up and down, left and right, front and back, etc. are used to describe 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, but such a situation is also included in the technical scope of the present invention.

[0019] [2] In the above-mentioned wafer stage (the wafer stage described in [1]), the upper substrate may include the ceramic substrate and a supporting 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 threaded hole may be provided on the lower surface of the supporting substrate. Thus, the supporting substrate is made of metal or a metal-ceramic composite material, and thus has excellent thermal conductivity compared to the ceramic substrate. Therefore, the heat of the ceramic substrate can be efficiently transferred to the lower substrate.

[0020] [3] In the above-mentioned wafer carrier (the wafer carrier described in [1] or [2]), the through hole can be provided in a manner that penetrates the protrusion. Thus, 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 can be fully utilized.

[0021] [4] In the above-mentioned wafer placement table (the wafer placement table described in any one of [1] to [3] above), the thermal resistance of the heat sink may be 0.35K·cm 2 As a result, the heat of the upper substrate is rapidly transferred to the lower substrate.

[0022] [5] In the above-mentioned wafer placement table (the wafer placement table described in any one of [1] to [4]), the Young's modulus of the heat sink may be 100 MPa or less. As a result, the tightening force of the screw component is easily and evenly transmitted to the entire surface of the heat sink, so that the heat sink is firmly and tightly attached to the upper substrate and the lower substrate over its entire surface.

[0023] [6] In the above-mentioned wafer placement table (the wafer placement table described in any one of [1] to [5] above), the thermally conductive paste may have a thermal conductivity of 0.5 W / mK or more. This further promotes heat transfer from the upper substrate to the lower substrate.

[0024] [7] In the above-mentioned wafer placement table (the wafer placement table according to any one of the above-mentioned [1] to [6]), the through hole may be arranged so as not to intersect the refrigerant flow path or the refrigerant flow path groove. Thus, the refrigerant does not leak out of the through hole into which the threaded member is inserted.

[0025] [8] In the above-mentioned wafer placement table (the wafer placement table described in any one of [1] to [6] above), the through hole can be arranged to intersect with the refrigerant flow path or the refrigerant flow path groove, and the lower substrate can have a refrigerant leakage prevention component that prevents the refrigerant from leaking from the through hole into which the threaded component is inserted to the lower surface of the lower substrate. As a result, it is not necessary to bypass the threaded component to set the refrigerant flow path, so the design freedom of the refrigerant flow path or the refrigerant flow path groove is improved. In addition, the refrigerant leakage component can prevent the refrigerant from leaking from the through hole into which the threaded component is inserted.

[0026] [9] In the above-mentioned wafer placement table (the wafer placement table according to any one of the above-mentioned [1] to [8]), the lower substrate may be made of a material that is easy to process. This makes it easy to form a refrigerant flow path or a refrigerant flow path groove on the lower substrate, thereby reducing processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a longitudinal cross-sectional view of the wafer stage 10 installed in the chamber 94 .

[0028] Figure 2 It is a top view of the wafer stage 10 .

[0029] Figure 3 This is a cross-sectional view when a cut surface obtained by horizontally cutting the wafer stage 10 by the heat sink 40 is viewed from above.

[0030] Figure 4 It is a manufacturing process diagram of the wafer stage 10 (manufacturing process of the upper substrate 20 ).

[0031] Figure 5 It is a manufacturing process diagram of the wafer stage 10 (manufacturing process of the lower substrate 30 ).

[0032] Figure 6 It is a manufacturing process diagram of the wafer stage 10 (assembly process of the wafer stage 10).

[0033] 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 .

[0034] Figure 8 It is a longitudinal cross-sectional view of the wafer placement table 110 .

[0035] Fig. 9 It is a longitudinal cross-sectional view of the wafer placement table 210 .

[0036] Fig.10 It is a longitudinal cross-sectional view of the wafer placement table 310 . DETAILED DESCRIPTION

[0037] Preferred embodiments of the present invention will be described below 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 top view of the wafer stage 10, Figure 3 This is a cross-sectional view when a cut surface obtained by horizontally cutting the wafer stage 10 by the heat sink 40 is viewed from above.

[0038] The wafer stage 10 is used to perform CVD, etching, etc. on the wafer W using plasma, and is fixed to a mounting plate 96 provided inside a chamber 94 for semiconductor processes. The wafer stage 10 includes an upper substrate 20, a lower substrate 30, a heat sink 40, and a screw member 50.

[0039] 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 to 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, it is preferably 25 mm or less.

[0040] The ceramic substrate 21 has a circular wafer placement surface 21a. The wafer W is placed on the wafer placement 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 wafer adsorption electrode 22 built in on the side close to the wafer placement surface 21a. The wafer adsorption electrode 22 is formed of a material containing W, Mo, WC, MoC, etc., for example. The wafer adsorption electrode 22 is a disk-shaped or mesh-shaped monopolar electrostatic electrode. The layer on the upper side of the wafer adsorption electrode 22 in the ceramic substrate 21 functions as a dielectric layer. The wafer adsorption DC power supply 52 is connected to the wafer adsorption electrode 22 via the 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 .

[0041] The supporting substrate 23 is a circular plate that is slightly larger than the ceramic substrate 21 and is made of a conductive material. Examples of conductive materials include composite materials and metals. Examples of composite materials include composite materials of metals and ceramics. Examples of composite materials of metals and ceramics include metal-matrix composites (MMC) and ceramic-matrix composites (CMC). Specific examples of such composite materials include materials containing Si, SiC and Ti, and materials obtained by impregnating a SiC porous body with Al and / or Si. The material containing Si, SiC and Ti is referred to as SiSiCTi, the material obtained by impregnating a SiC porous body with Al is referred to as AlSiC, and the material obtained by impregnating a SiC porous body with Si is referred to as SiSiC. Examples of metals include Mo and the like. The absolute value of the difference in linear thermal expansion coefficient between the material used in the supporting substrate 23 and the ceramic material used in 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 In consideration of strength, the thickness of the support substrate 23 is preferably 3 mm or more and 6 mm or more; in consideration of cooling efficiency, the thickness of the support substrate 23 is preferably 20 mm or less.

[0042] A plurality of threaded holes 24 are provided on the lower surface of the supporting substrate 23. The threaded holes 24 are provided at positions opposite to the through holes 36 described later. The threaded holes 24 are formed by providing a cylindrical hole on the lower surface of the supporting substrate 23 and directly cutting a thread groove in the cylindrical hole, but are not particularly limited thereto. For example, the threaded hole 24 can be formed by inserting a spiral threaded sleeve into the cylindrical hole, or a terminal with an internal thread (such as a cap nut, etc.) of Patent Document 1 can be inserted into the cylindrical hole and welded. The center interval between two adjacent threaded holes 24 is not particularly limited, and is preferably less than 100 mm, for example.

[0043] 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. The metal bonding layer 25 is formed, for example, by TCB (Thermal Compression Bonding). TCB refers to a well-known method in which a metal bonding material is sandwiched between two components to be bonded, and the two components are bonded under pressure while being heated to a temperature below the solidus temperature of the metal bonding material.

[0044] 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 has a built-in refrigerant flow path 35. The refrigerant flow path 35 is formed in a spiral shape from the inlet 35a to the outlet 35b of the refrigerant flow path 35 in a one-stroke manner in the entire area where the ceramic substrate 21 is arranged. 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 refrigerant cooling device not shown in the figure, and the refrigerant discharged from the outlet 35b is returned to the inlet 35a again and supplied to the refrigerant flow path 35 after the refrigerant cooling device is temperature-adjusted to a specified low temperature. The refrigerant flowing in the refrigerant flow path 35 is preferably a liquid, preferably electrically insulating. As an electrically insulating liquid, for example, a fluorine-based inactive liquid can be cited. The easy-to-process material used in the lower substrate 30 is preferably easier to process than the supporting substrate 23. As an index of processability, for example, the machinability index shown in JIS B 0170 (2020) can be used. As the 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 the easy-to-process material include aluminum, aluminum alloys, stainless steel (SUS material), and the like.

[0045] 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.

[0046] 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 refrigerant flow path 35. The through holes 36 have a large diameter portion 36a that receives the head 50a of the screw member 50, and a small diameter portion 36b that allows the foot 50b of the screw member 50 to pass through but prevents the head 50a from passing through. Figure 3 As shown, on the upper surface of the lower substrate 30, a plurality of protrusions 38 are arranged in a dotted shape 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, for example, preferably 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.

[0047] 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 installed on the wafer stage 10 is greater than the height of the protrusion 38, but the thickness of the heat sink 40 after being installed on the wafer stage 10 is the same or almost 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 compressed in the up-down direction. In this way, the heat sink 40 is firmly in contact with 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 transferred 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. The thermal resistance can be measured, for example, based on ASTM D5470. The heat sink 40 has no adhesiveness or substantially no adhesiveness.

[0048] Specifically, the heat sink 40 is preferably a sheet containing carbon and resin. As carbon, graphite, carbon fiber, carbon nanotube, etc. can be cited; as resin, silicone resin, etc. can be cited. In the case of graphite, it is preferably configured in a manner that the surface direction of graphene constituting graphite is along the up-down direction; in the case of carbon fiber and carbon nanotube, 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. As specific examples of the heat sink 40, EX20000C4S (manufactured by DEXERIALS), GraphitePAD, GraphiteTIM (registered trademark) (all manufactured by Panasonic) and the like can be cited. The Poisson's ratio of the heat sink 40 is preferably 0.4 or less, more preferably 0.3 or less, and further preferably 0.2 or less. The smaller the Poisson's ratio of the heat sink 40, the more evenly the tightening force of the screw component 50 is transmitted to the entire surface of the heat sink 40, and it is difficult to escape in the lateral direction, so the heat sink 40 is firmly adhered to the supporting substrate 23 and the lower substrate 30 on the entire surface. Therefore, the wafer W can be cooled more uniformly. The Shore OO hardness of the heat sink 40 may be 50 or more and 80 or less.

[0049] The thermally conductive paste 60 is 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. In addition, the thermally conductive paste 60 is also interposed 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). The thermally conductive paste 60 can be either electrically insulating or electrically conductive. As the thermally conductive paste 60, a paste with a thermal conductivity of 0.5 W / mK or more is preferred, a paste with a thermal conductivity of 1 W / K or more is more preferred, and a paste with a thermal conductivity of 2 W / K or more is further preferred. As such a paste, for example, Tran-Q clay (thermal conductivity 2.8 W / mK) of NOK, BERGQUIST TLF 6000HG (thermal conductivity 6.0 W / mK) of Henkel, X-23-7921-5 (thermal conductivity 6.0 W / mK) of Shin-Etsu Chemical Co., Ltd., etc. can be cited.

[0050] like Figure 1 As 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 in a manner not to intersect with the refrigerant flow path 35, and is screwed into the threaded hole 24 of the supporting substrate 23. The threaded component 50 is screwed into the threaded 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 upward the stepped surface 36c (the boundary between the large diameter portion 36a and the small diameter portion 36b) of the through hole 36. In addition, the supporting substrate 23 of the upper substrate 20 and the lower substrate 30 are fastened in a state of sandwiching the heat sink 40, and the heat sink 40 is compressed in the up and down direction. The head portion 50a of the threaded component 50 is housed in the large diameter portion 36a in a manner not to be exposed 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.

[0051] 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 covered with an insulating film as needed. As the insulating film, for example, a sprayed film of aluminum oxide or yttrium oxide 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 and down direction between the upper substrate 20 and the lower substrate 30 to exert sealing properties. As a result, the heat sink 40 is protected by the O-ring.

[0052] Next, use Figures 4 to 6 A manufacturing example of the wafer stage 10 will be described. Figures 4 to 6 FIG. 1 is a manufacturing process diagram of the wafer placement table 10. Figure 4 The manufacturing process of the upper substrate 20 is shown. Figure 5 20 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 .

[0053] The upper substrate 20 is manufactured, for example, as follows. First, a ceramic substrate 21 ( Figure 4 (A)). The ceramic substrate 21 has a built-in chip adsorption electrode 22. Next, a hole 21b is formed from the lower surface of the ceramic substrate 21 to the chip adsorption electrode 22 ( Figure 4 (B)), insert the power supply terminal 54 into the hole 21b, and join the power supply terminal 54 and the chip adsorption electrode 22 ( Figure 4 (C)).

[0054] In parallel with this, a disk-shaped supporting substrate 23 ( Figure 4 (D)), a hole 23b is formed in the supporting substrate 23 to penetrate in the vertical direction, and a threaded hole 24 is formed at a predetermined position on the lower surface of the supporting substrate 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, it is preferred that the support substrate 23 is made of SiSiCTi or AlSiC. The reason is that if SiSiCTi or AlSiC is used, the thermal expansion coefficient can be made substantially the same as the thermal expansion coefficient of alumina.

[0055] The support substrate 23 made of SiSiCTi can be produced, for example, as follows. First, silicon carbide, metal Si and metal Ti are mixed to produce a powder mixture. Next, the obtained powder mixture is subjected to single-screw pressure molding to produce 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.

[0056] 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, while the ceramic substrate 21 is placed on the metal bonding material. Thus, a stacked body in which the supporting substrate 23, the metal bonding material and the ceramic substrate 21 are stacked in sequence from the bottom is obtained. The upper substrate 20 ( Figure 4 (F)) The upper substrate 20 is formed by bonding a ceramic substrate 21 to the upper surface of a supporting substrate 23 via a metal bonding layer 25 .

[0057] TCB is performed, for example, as follows. That is, the stack is pressurized and bonded at a temperature below the solidus temperature of the metal bonding material (for example, above the temperature after subtracting 20°C from the solidus temperature and below the solidus temperature), and then returned to room temperature. As a result, the metal bonding material becomes a metal bonding layer (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 using Al-Si-Mg bonding materials for TCB, 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.

[0058] In parallel with the production of the upper substrate 20, the lower substrate 30 is produced using an easily processable material, for example, 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 refrigerant 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 refrigerant 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 ( Figure 5 (D)).

[0059] Then, if Figure 6 As shown in (A), after the thermal conductive paste 60 is applied to the top surface of the protrusion 38, 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 vertical 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 vertical direction at a position opposite to the small diameter portion 36b of the through hole 36 or 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 so 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, a gap is left between the inner peripheral surface of the protrusion insertion hole 44 and the outer peripheral surface of the protrusion 38.

[0060] Next, while inserting the power supply terminal 54 of the upper substrate 20 into the terminal hole 30b, the upper substrate 20 is placed on the heat sink 40 arranged on the upper surface of the lower substrate 30. Next, the screw member 50 is inserted from the lower surface of the lower substrate 30 into each through hole 36 and screwed into the screw hole 24 of the support substrate 23. The screw member 50 is screwed until the protrusion 38 contacts the lower surface of the support substrate 23. As a result, the heat sink 40 is compressed substantially uniformly between the support substrate 23 and the lower substrate 30, and a high thermal conductivity is exhibited. At the same time, the thermal conductive paste 60 applied to the top surface of the protrusion 38 enters the gap between the inner peripheral surface of the protrusion insertion hole 44 and the outer peripheral surface of the protrusion 38. Therefore, compared with the case where a void remains in the gap, the heat transfer from the upper substrate 20 to the lower substrate 30 is promoted. In addition, a part of the thermal conductive paste 60 exists between the top surface of the protrusion 38 and the lower surface of the support substrate 23. There are minute irregularities on the top surface of the protrusion 38, but the irregularities are filled with the thermally conductive paste 60. Therefore, compared with the case where minute irregularities still remain on the top surface of the protrusion 38, heat transfer from the upper substrate 20 to the lower substrate 30 is promoted. Then, an insulating tube 55 ( Figure 6 (C)). In this way, the wafer placement table 10 can be obtained.

[0061] Next, use Figure 1 The use example of the wafer stage 10 is described. First, the wafer stage 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 vertical direction. 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 refrigerant flow path 35, and can be compressed in the vertical direction. Next, the threaded component 70 is screwed into the threaded hole 39 provided on the lower surface of the lower substrate 30 through the threaded insertion hole 97 from the lower surface of the setting plate 96. As a result, the sealing components 82a and 82b are compressed in the vertical direction to exert sealing properties, preventing the refrigerant from leaking outward from the sealing components 82a and 82b.

[0062] A disc-shaped wafer W is placed on the wafer placement surface 21a of the wafer placement table 10 provided on the setting plate 96. In this state, a DC voltage of the wafer adsorption DC power supply 52 is applied to the wafer adsorption electrode 22, so that the wafer W is adsorbed on the wafer placement 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 a reduced pressure atmosphere), and while a process gas is supplied from the shower head 98, an RF voltage from the RF power supply 62 is applied to the lower substrate 30. Thus, plasma is generated between the wafer W and the shower head 98. Then, CVD film formation or etching is performed on the wafer W using this plasma.

[0063] In the wafer stage 10 described above, the heat sink 40 has a plurality of protrusion insertion holes 44 into which the plurality of protrusions 38 are inserted. 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. Thus, the heat sink 40 arranged between the upper substrate 20 and the lower substrate 30 is compressed to have 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 greatly depending on the position. Furthermore, the thermal conductive paste 60 is 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 and between the top surface of the protrusion 38 and the lower surface of the upper substrate 20. Therefore, the upper substrate 20, the heat sink 40, and the lower substrate 30 can be brought into close contact with each other without any gap as much as possible. Therefore, the thermal uniformity of the wafer W is improved.

[0064] The thermally conductive paste 60 used is preferably a paste having a thermal conductivity of 0.5 W / mK or more. This further promotes heat transfer from the upper substrate 20 to the lower substrate 30 .

[0065] 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 bonded to the lower surface of the ceramic substrate 21 via a metal bonding layer 25, and the threaded hole 24 is provided on the lower surface of the support substrate 23. The support substrate 23 is made of metal or a metal-ceramic composite material, and therefore has better thermal conductivity than the ceramic substrate 21. Therefore, the heat of the ceramic substrate 21 can be efficiently transferred to the lower substrate 30.

[0066] Furthermore, at least one of the plurality of protrusions 38 is provided directly above the inlet 35a of the refrigerant flow path 35. The portion directly above the inlet 35a of the refrigerant flow path 35 in the upper substrate 20 is more easily cooled by the refrigerant than other portions, but since the protrusion 38 is provided directly above the inlet 35a of the refrigerant flow path 35, overcooling caused by the refrigerant can be suppressed.

[0067] Furthermore, the through hole 36 of the lower base material 30 is provided so as not to intersect with the refrigerant flow path 35. Therefore, the refrigerant does not leak from the through hole 36 into which the screw member 50 is inserted.

[0068] Furthermore, the lower substrate 30 is made of a material that is easy to process. Thus, the refrigerant 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.

[0069] The thermal resistance of the heat sink 40 is preferably 0.35K·cm 2 / W or less. As a result, 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. As a result, the tightening force of the screw component 50 is easily and evenly transferred to the entire surface of the heat sink 40, so that the heat sink 40 is firmly in close contact with the upper substrate 20 and the lower substrate 30 on its entire surface.

[0070] 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 supporting substrate 23 is small, so that the warping and damage of the upper substrate 20 caused by thermal stress can be suppressed, and the damage of the metal bonding layer 25 bonding the ceramic substrate 21 and the supporting substrate 23 can also be suppressed. In addition, compared with resin, the metal bonding layer 25 makes the heat transfer between the ceramic substrate 21 and the supporting substrate 23 better.

[0071] 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 with the ceramic substrate 21, and has higher toughness than ceramic materials, so it is difficult to break even if thermal stress occurs. In addition, such a composite material has electrical conductivity, so it can also be used as an RF electrode.

[0072] The heat sink 40 is preferably conductive. As a result, the lower substrate 30, the support substrate 23, and the metal bonding layer 25 are at the same potential, 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 also be used to make the lower substrate 30 and the support substrate 23 at the same potential via the screw member 50.

[0073] 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 it falls within the technical scope of the present invention.

[0074] In the above-mentioned embodiment, the through hole 36 penetrating the lower substrate 30 in the up-down 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 in FIG. 1 , the through hole 36 may also be provided to penetrate the protrusion 38. In this case, the thermal conductive paste 60 is 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, 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). As a result, it is not necessary to provide a connecting hole ( ) that communicates with the through hole 36 on the heat sink 40. Figure 6 (A) and (B) holes 46), so the function of the heat sink 40 can be fully exerted. Figure 7 In the embodiment, the same reference numerals are given to the same components as those in the above-mentioned embodiment.

[0075] In the above-mentioned embodiment, the lower substrate 30 has a built-in refrigerant flow path 35, but the present invention is not limited thereto. Figure 8 Like the wafer carrier 110 shown in the figure, the lower substrate 130 has a refrigerant flow path groove 132 opened on the upper surface of the lower substrate 130. In this case, the refrigerant flow path 135 is formed by covering the opening of the refrigerant flow path groove 132 with the heat sink 40. The refrigerant flow path groove 132 constitutes the side wall and the bottom of the refrigerant flow path 135, and the heat sink 40 constitutes the ceiling of the refrigerant flow path 135. Thus, the lower substrate 130 can be formed by processing a circular plate member. It should be noted that in Figure 8 In the embodiment, the same reference numerals are given to the same components as those in the above-mentioned embodiment.

[0076] 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 threaded hole 24 is provided on the lower surface of the support substrate 23, but the present invention is not particularly limited to this. Fig. 9As shown in the wafer placing table 210, the upper substrate 220 is formed only by the ceramic substrate 221. In this case, the screw hole 224 into which the screw member 50 is screwed is provided on the lower surface of the ceramic substrate 221. Fig. 9 In the embodiment, the same reference numerals are given to the same components as those in the above-mentioned embodiment.

[0077] In the above-mentioned embodiment, the through hole 36 of the lower substrate 30 is arranged so as not to intersect with the refrigerant flow path 35, but the present invention is not particularly limited thereto. Fig.10 As shown in the wafer placement table 310, the through hole 336 may be provided to intersect with the refrigerant flow path 35. As in the above-mentioned embodiment, the through hole 336 includes a large diameter portion 336a and a small diameter portion 336b. 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 refrigerant 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. Thus, there is no need to set the refrigerant flow path 35 around the threaded component 50, and thus the design freedom of the refrigerant flow path 35 is improved. In addition, the O-ring 51 prevents the refrigerant 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 in Fig.10 In the embodiment, the same reference numerals are used for the same components as those in the above embodiment. Figure 8 In the embodiment, the through hole 36 may be provided to intersect with the refrigerant flow path groove 132 .

[0078] In the above-mentioned embodiment, the protrusions 38 are provided in a dotted manner on the entire upper surface of the lower substrate 30, but the present invention is not particularly limited thereto. For example, instead of providing the protrusions 38 on the upper surface of the lower substrate 30, the protrusions 38 may be provided in a dotted manner on the entire lower surface of the upper substrate 20 (the lower surface of the supporting substrate 23), 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 have a thickness that is the same as or substantially the same as the height of the protrusions as a whole. Therefore, the thermal conductivity of the heat sink 40 does not vary greatly depending on the position, and the thermal uniformity of the wafer W is improved.

[0079] In the above-mentioned embodiment, the heat sink 40 is exemplified as having conductivity, but the heat sink 40 may also have insulating properties.

[0080] 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 it, or an RF electrode for plasma generation may be further built in on the basis of it. In this case, the high-frequency power supply is not connected to the lower substrate 30, but to the RF electrode. In addition, the ceramic substrate 21 may have a built-in heater electrode (resistive heating element). In this case, the heater power supply is connected to the heater electrode. The ceramic substrate 21 may have a built-in electrode layer, or may have two or more layers.

[0081] In the above-described embodiment, the refrigerant flow path 35 is provided in a spiral shape from the inlet 35a to the outlet 35b, but the shape of the refrigerant flow path 35 is not particularly limited.

[0082] In the above-mentioned embodiment, the ceramic substrate 21 is produced by hot pressing and sintering a ceramic powder molded body. The molded body in this case can be produced by stacking a plurality of strip-shaped molded bodies, by die casting, or by compacting ceramic powder.

[0083] In the above-mentioned 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, in consideration of the material cost, it is preferred to use an easily machinable material such as aluminum or aluminum alloy.

[0084] In the wafer stage 10 of the above-described embodiment, a hole may be provided that penetrates the wafer stage 10 from the lower surface of the lower substrate 30 to the wafer placement surface 21a. Examples of such holes 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 that moves 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 or the lift pin hole penetrates the heat sink 40.

[0085] Industrial Applicability

[0086] The wafer stage of the present invention is used in, for example, a semiconductor manufacturing apparatus.

[0087] Explanation of symbols

[0088] 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 threaded hole; 25 metal bonding layer; 30 lower substrate; 30b terminal hole; 31, 32 circular plate member; 35 refrigerant 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 threaded hole; 40 heat sink; 44 protrusion insertion hole; 46, 47 holes; 50 threaded member; 50a head; 50b foot; 51O ring; 52 DC power supply for chip adsorption; 54 power supply terminal; 55 insulating tube; 60 thermal paste; 62 RF power supply; 64 power supply terminal; 70 threaded component; 80, 82a, 82b sealing components; 94 chamber; 96 setting plate; 97 threaded insertion hole; 98 nozzle; 110 chip carrier; 130 lower substrate; 132 refrigerant flow path groove; 135 refrigerant flow path; 210 chip carrier; 220 upper substrate; 221 ceramic substrate; 224 threaded hole; 310 chip carrier; 336 through hole; 336a large diameter portion; 336b small diameter portion; 336c step surface.

Claims

1. A wafer loading platform, comprising: 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, the lower substrate being arranged on the lower surface side of the upper substrate and having a refrigerant flow path for circulating the refrigerant or a refrigerant flow path groove having a side wall and a bottom constituting the refrigerant flow path; A through hole, the through hole penetrating the lower substrate in the up-down 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 threaded hole, the threaded hole being disposed at a position on the lower surface of the upper substrate opposite to the through hole; a threaded component, the threaded component being inserted into the through hole from the lower surface of the lower substrate and being screwed into the threaded hole; and A thermally conductive paste is interposed between at least one of a side surface of the protrusion and an inner peripheral surface of the protrusion insertion hole of the heat sink and a top surface of the protrusion and a lower surface of the upper substrate.

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 threaded hole is disposed on the lower surface of the supporting substrate.

3. The wafer stage according to claim 1 or 2, wherein: The through hole is provided so as 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 thermally conductive paste is a paste having a thermal conductivity of 0.5 W / mK or more.

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

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

9. 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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