Wafer placement table

Abstract

A wafer placement stage 10 comprises a ceramic base member 20, a cooling base member 30, and a plurality of holes (for example, a gas hole 44 and a lift pin hole 48). The ceramic base member 20 has a wafer placement surface 22a on an upper surface thereof on which a wafer can be placed, and contains a wafer pickup electrode 26. The cooling base member 30 is bonded to the lower surface of the ceramic base member 20, and includes a wide-area refrigerant flow path 32. The gas hole 44 and the terminal hole 51 penetrate through the cooling base member 30 in an up-down direction. Hole refrigerant flow paths 36 to which a refrigerant is supplied independently of the wide-area refrigerant flow path 32 are formed in regions around the holes.

Description

[Technical field]

[0001] The present invention relates to a wafer stage. [Background technology]

[0002] Conventionally, a wafer mounting table is known that includes a ceramic substrate having a wafer mounting surface and an electrode built therein, a cooling substrate having a coolant flow path, and a bonding layer that bonds the ceramic substrate and the cooling substrate. For example, Patent Documents 1 and 2 disclose that such a wafer mounting table uses a cooling substrate made of a metal matrix composite material having a linear thermal expansion coefficient similar to that of the ceramic substrate. They also disclose that the wafer mounting table is provided with a terminal hole through which a power supply terminal for supplying power to the electrode is inserted, a gas hole through which He gas is supplied to the back surface of the wafer, and a lift pin hole through which a lift pin for lifting the wafer from the wafer mounting surface is inserted. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5666748 [Patent Document 2] Patent No. 5666749 Summary of the Invention [Problem to be solved by the invention]

[0004] However, since the heat dissipation capacity is poor around the terminal holes, gas holes, and lift pin holes, the wafer may become hot spots directly above such holes, where the temperature is higher than other areas. Also, there may be other areas with poor heat dissipation capacity besides the holes, and hot spots may occur directly above such areas.

[0005] The present invention has been made to solve such problems, and has as its main object to suppress the occurrence of hot spots on a wafer. [Means for solving the problem]

[0006] [1] The wafer mounting table of the present invention comprises: a ceramic substrate having a wafer mounting surface on an upper surface thereof and incorporating an electrode; a cooling substrate bonded to a lower surface of the ceramic substrate and configured to cool the ceramic substrate; Equipped with The cooling substrate has, as a refrigerant flow path, a wide area refrigerant flow path formed over the entire area corresponding to the wafer mounting surface, and a local refrigerant flow path formed in a specific local area and to which refrigerant is supplied independently of the wide area refrigerant flow path.

[0007] This wafer mounting table is provided with a wide-area refrigerant flow path formed over the entire area corresponding to the wafer mounting surface, and a local refrigerant flow path formed in a predetermined local area to which the refrigerant is supplied independently of the wide-area refrigerant flow path. The predetermined local area is an area that is likely to become a hot spot, for example, a peripheral area of ​​a terminal hole, a gas hole, or a lift pin hole. The diameter of the local area may be, for example, 1 / 5 or less of the diameter of the wafer mounting surface, or 1 / 10 or less. In addition, the center of the local area may be shifted from the center of the wafer mounting surface. In the present invention, a local refrigerant flow path is provided to supply the refrigerant to the local area independently of the wide-area refrigerant flow path, so that the local area can be cooled in a focused manner. Therefore, the occurrence of hot spots on the wafer can be suppressed.

[0008] In this specification, "upper" and "lower" do not represent absolute positional relationships, but rather represent relative positional relationships. Therefore, depending on the orientation of the wafer stage, "upper" and "lower" can become "left" and "right," "front" and "rear," or "lower" and "upper."

[0009] [2] In the wafer stage of the present invention (the wafer stage described in [1] above), the local refrigerant flow path may be supplied with a refrigerant having a lower temperature than that supplied to the wide area refrigerant flow path, thereby facilitating heat removal from the local area by the low-temperature refrigerant.

[0010] [3] In the wafer stage of the present invention (the wafer stage described in [1] or [2] above), the local coolant flow path may be supplied with the coolant at a higher flow rate than the wide area coolant flow path, thereby facilitating heat removal from the local area by the coolant at a higher flow rate.

[0011] [4] In the wafer mounting table of the present invention (the wafer mounting table according to any one of [1] to [3] above), the volume ratio of the refrigerant flow passage in the local region of the cooling base material may be greater than the volume ratio of the refrigerant flow passage in a region outside the local region. In this way, the refrigerant flow passages are densely arranged in the local region, and heat removal from the local region is promoted. In addition to the case where only the local refrigerant flow passage is formed in the local region, not only the local refrigerant flow passage but also the wide-area refrigerant flow passage may be formed. In this case, the volume ratio of the refrigerant flow passage in the local region may be the total volume ratio of the local refrigerant flow passage and the wide-area refrigerant flow passage in the local region. On the other hand, since the local refrigerant flow passage is not formed in the region outside the local region, the volume ratio of the refrigerant flow passage in the region outside the local region may be the volume ratio of the wide-area refrigerant flow passage in the region outside the local region.

[0012] [5] In the wafer mounting table of the present invention (the wafer mounting table described in any one of [1] to [4] above), the local refrigerant flow path may be provided with a heat exchange promotion structure that promotes heat exchange between the refrigerant flowing through the local refrigerant flow path and the wafer mounted on the wafer mounting surface. In this manner, the heat exchange promotion structure improves the heat transfer coefficient in the local refrigerant flow path, and promotes heat removal from a local region. The heat exchange promotion structure may be a fin provided on the inner surface of the local refrigerant flow path, or may be a narrow portion where the flow path narrows midway through the local refrigerant flow path.

[0013] [6] In the wafer stage of the present invention (the wafer stage according to any one of [1] to [5] above), the local coolant flow path may be supplied with a coolant having a higher thermal conductivity than the wide area coolant flow path. In this way, the coolant having a higher thermal conductivity promotes heat removal from the local area.

[0014] [7] In the wafer stage of the present invention (the wafer stage according to any one of [1] to [6] above), the local coolant flow path may be supplied with a coolant having a larger specific heat than the wide area coolant flow path. This suppresses a temperature rise of the coolant, facilitating heat removal from the local area.

[0015] [8] In the wafer mounting table of the present invention (the wafer mounting table according to any one of [1] to [7] above), the wide area refrigerant flow path and the local refrigerant flow path may be formed on the same plane parallel to the wafer mounting surface. This makes it easier to form both flow paths than forming them in multiple stages, one above the other below the plane parallel to the wafer mounting surface.

[0016] [9] In the wafer mounting table of the present invention (the wafer mounting table described in any one of [1] to [8] above), the wide area refrigerant flow path and the local refrigerant flow path may be formed in multiple stages, one above the other below a plane parallel to the wafer mounting surface. This allows greater freedom in the arrangement of both flow paths than if they were formed on the same plane. When formed in multiple stages, the local refrigerant flow path may be formed above the wide area refrigerant flow path.

[0017]

[10] The wafer stage of the present invention (the wafer stage according to any one of [1] to [9] above) may include a plurality of holes penetrating the cooling base in the vertical direction, and the local region may be a peripheral region of at least one of the plurality of holes. Generally, the region directly above such a hole on the wafer is prone to becoming a hot spot. Therefore, it is highly meaningful to apply the present invention.

[0018]

[11] The wafer mounting table of the present invention (the wafer mounting table according to any one of [1] to

[10] ) includes a plurality of holes penetrating the cooling base in the vertical direction, and the local region is a peripheral region of at least one of the plurality of holes, and the hole may be at least one of a power supply member insertion hole provided in the wafer mounting table from the electrode downward and through which a power supply member for supplying power to the electrode is inserted, a lift pin hole penetrating the wafer mounting table in the vertical direction and through which a lift pin is inserted, a gas hole penetrating the wafer mounting surface in the vertical direction and supplying gas to the wafer mounting surface, and a temperature measurement hole penetrating the cooling base in the vertical direction and through which a temperature measurement member is inserted. In general, the areas directly above the power supply member insertion hole, lift pin hole, gas hole, and temperature measurement hole in the wafer are prone to become hot spots. Therefore, it is highly significant to apply the present invention. [Brief description of the drawings]

[0019] [Figure 1] FIG. 2 is a vertical cross-sectional view of the wafer mounting table 10 installed in the chamber 94. [Diagram 2] FIG. [Diagram 3] 3 is a cross-sectional view of the wafer mounting table 10 taken along a horizontal plane passing through the wide area coolant flow path 32 and the hole coolant flow path 36. FIG. [Figure 4] FIG. 4 is an enlarged cross-sectional view showing a vertical cross section around a lift pin hole 44. [Diagram 5] 5A to 5C are diagrams showing the manufacturing process of the wafer mounting table 10. [Figure 6] 13 is an enlarged cross-sectional view showing a vertical cross section of another example of the hole coolant flow passage 36. FIG. [Figure 7] 13 is an enlarged horizontal cross-sectional view of another example of the hole coolant flow passage 36. FIG. [Figure 8] 13 is an enlarged cross-sectional view showing a vertical cross section of another example of the hole coolant flow passage 36. FIG. [Figure 9] FIG. 4 is a horizontal cross-sectional view showing another example of the wafer mounting table 10. [Figure 10] 13 is an enlarged horizontal cross-sectional view of another example of the hole coolant flow passage 36. FIG. [Figure 11] FIG. 4 is a vertical cross-sectional view showing another example of the wafer mounting table 10. [Figure 12]12 is a cross-sectional view of the wafer mounting table 10 of FIG. 11 taken along a horizontal plane passing through the wide-area refrigerant flow path 32. FIG. [Figure 13] 12 is a cross-sectional view of the wafer mounting table 10 of FIG. 11 cut along a horizontal plane passing through a hole coolant flow path 36. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] A preferred embodiment of the present invention will be described below with reference to the drawings. In the embodiment, the predetermined local region is at least one peripheral region of holes penetrating the cooling substrate in the vertical direction, and the local refrigerant flow path is a hole refrigerant flow path provided in the peripheral region of the hole. Fig. 1 is a vertical cross-sectional view of the wafer mounting table 10 installed in the chamber 94 (a cross-sectional view when cut along a plane including the central axis of the wafer mounting table 10), Fig. 2 is a plan view of the wafer mounting table 10, Fig. 3 is a cross-sectional view when the wafer mounting table 10 is cut along a horizontal plane passing through the wide-area refrigerant flow path 32 and the hole refrigerant flow path 36, and Fig. 4 is an enlarged cross-sectional view showing a vertical cross-section around the lift pin hole 44.

[0021] The wafer mounting table 10 is used for performing CVD, etching, and the like on a wafer W using plasma, and is fixed to a mounting plate 96 provided inside a semiconductor process chamber 94. The wafer mounting table 10 includes a ceramic base 20, a cooling base 30, and a metal bonding layer 40.

[0022] The ceramic base 20 has a central portion 22 having a circular wafer mounting surface 22a, and an outer peripheral portion 24 having an annular focus ring mounting surface 24a on the outer periphery of the central portion 22. Hereinafter, the focus ring may be abbreviated as "FR." A wafer W is mounted on the wafer mounting surface 22a, and a focus ring 78 is mounted on the FR mounting surface 24a. The ceramic base 20 is made of a ceramic material such as alumina or aluminum nitride. The FR mounting surface 24a is one step lower than the wafer mounting surface 22a.

[0023] The center portion 22 of the ceramic base material 20 incorporates a wafer adsorption electrode 26 on the side close to the wafer mounting surface 22a. The wafer adsorption electrode 26 is formed of a material containing, for example, W, Mo, WC, MoC, etc. The wafer adsorption electrode 26 is a disk-shaped or mesh-shaped monopolar electrostatic adsorption electrode. The layer of the ceramic base material 20 above the wafer adsorption electrode 26 functions as a dielectric layer. A wafer adsorption DC power source 52 is connected to the wafer adsorption electrode 26 via a power supply terminal 54 (corresponding to the power supply member of the present invention). The power supply terminal 54 is inserted into a terminal hole 51 provided between the lower surface of the wafer adsorption electrode 26 and the lower surface of the cooling base material 30 of the wafer mounting table 10. The power supply terminal 54 is provided so as to pass through an insulating tube 55 arranged in a through hole of the terminal hole 51 that vertically penetrates the cooling base material 30 and the metal bonding layer 40, and reach the wafer adsorption electrode 26 from the lower surface of the ceramic base material 20. A low pass filter (LPF) 53 is provided between the wafer attracting DC power supply 52 and the wafer attracting electrode .

[0024] As shown in FIG. 2, a seal band 22b is formed along the outer edge of the wafer mounting surface 22a, and a plurality of small protrusions 22c are formed on the entire surface. The seal band 22b and the plurality of small protrusions 22c are formed on a reference surface 22d of the wafer mounting surface 22a. In this embodiment, the small protrusions 22c are flat cylindrical protrusions. The top surface of the seal band 22b and the top surfaces of the plurality of small protrusions 22c are located on the same plane. The heights of the seal band 22b and the small protrusions 22c (i.e., the distances from the reference surface 22d to these top surfaces) are several μm to several tens of μm. The wafer W is mounted on the wafer mounting surface 22a in a state of contact with the top surface of the seal band 22b and the top surfaces of the plurality of small protrusions 22c.

[0025] The cooling substrate 30 is a disk member made of a metal matrix composite material (also called metal matrix composite (MMC)). The cooling substrate 30 cools the ceramic substrate 20, and has refrigerant flow paths (wide-area refrigerant flow paths 32 and hole-use refrigerant flow paths 36) through which a refrigerant can circulate inside. The wide-area refrigerant flow paths 32 are connected to a wide-area refrigerant supply device 33, and a refrigerant is supplied from the wide-area refrigerant supply device 33. The hole-use refrigerant flow paths 36 are connected to a hole-use refrigerant supply device 37, and a refrigerant is supplied from the hole-use refrigerant supply device 37 independently of the wide-area refrigerant flow paths 32. The wide-area refrigerant supply device 33 may be configured to adjust the temperature of the refrigerant discharged from the wide-area refrigerant flow paths 32 and then supply it to the refrigerant flow paths 32 again. The same applies to the hole-use refrigerant supply device 37. The refrigerant flowing through the wide-area refrigerant flow paths 32 and the hole-use refrigerant flow paths 36 is preferably a liquid, and is preferably electrically insulating. Examples of electrically insulating liquids include fluorine-based inert liquids. Examples of MMC include materials containing Si, SiC, and Ti, and materials in which a porous SiC body is impregnated with Al and / or Si. The material containing Si, SiC, and Ti is called SiSiCTi, the material in which a porous SiC body is impregnated with Al is called AlSiC, and the material in which a porous SiC body is impregnated with Si is called SiSiC. When the ceramic base material 20 is an alumina base material, the MMC used for the cooling base material 30 is preferably AlSiC or SiSiCTi, which have a thermal expansion coefficient close to that of alumina. The cooling base material 30 is connected to an RF power source 62 via a power supply terminal 64. A high-pass filter (HPF) 63 is disposed between the cooling base material 30 and the RF power source 62. The cooling base material 30 has a flange portion 34 on the lower surface side, which is used to clamp the wafer stage 10 to a mounting plate 96.

[0026] The metal bonding layer 40 bonds the lower surface of the ceramic base material 20 and the upper surface of the cooling base material 30. The metal bonding layer 40 may be, for example, a layer formed of solder or a metal brazing material. The metal bonding layer 40 is formed, for example, by TCB (thermal compression bonding). TCB refers to a known method in which a metal bonding material is sandwiched between two members to be bonded, and the two members are pressure-bonded while being heated to a temperature equal to or lower than the solidus temperature of the metal bonding material.

[0027] The side surface of the outer periphery 24 of the ceramic substrate 20, the outer periphery of the metal bonding layer 40, and the side surface of the cooling substrate 30 are covered with an insulating film 42. The insulating film 42 may be, for example, a thermally sprayed film of alumina, yttria, or the like.

[0028] The wafer mounting table 10 has a plurality of holes penetrating the wafer mounting table 10 in the vertical direction. As shown in FIG. 2, these holes include a plurality of gas holes 44 opening in the reference surface 22d of the wafer mounting surface 22a and lift pin holes 48 for inserting lift pins 49 for moving the wafer W up and down with respect to the wafer mounting surface 22a. A plurality of gas holes 44 are provided at appropriate positions on the reference surface 22d when the wafer mounting surface 22a is viewed from above. A thermally conductive gas such as He gas is supplied to the gas holes 44 from an external gas supply source 46 (see FIG. 1). When the thermally conductive gas is supplied to the gas holes 44 with the wafer W mounted on the wafer mounting surface 22a, the space surrounded by the wafer W, the seal band 22b, the small protrusions 22c, and the reference surface 22d is filled with the thermally conductive gas. The thermally conductive gas has a higher thermal conductivity than a vacuum, and therefore plays a role in improving the thermal conduction between the wafer W and the ceramic base material 20. A plurality of lift pin holes 48 are provided at equal intervals along concentric circles of the wafer mounting surface 22a when the wafer mounting surface 22a is viewed in plan view. In this embodiment, three gas holes 44 and three lift pin holes 48 are provided alternately at equal intervals along concentric circles of the wafer mounting surface 22a when the wafer mounting surface 22a is viewed in plan view.

[0029] The wide-area refrigerant flow passage 32 and the hole refrigerant flow passage 36 provided inside the cooling substrate 30 are formed on the same plane parallel to the wafer mounting surface 22a of the cooling substrate 30. That is, they are formed at a position where both the wide-area refrigerant flow passage 32 and the hole refrigerant flow passage 36 appear in any cross section of the cooling substrate 30 cut by a plane parallel to the wafer mounting surface 22a. As shown in FIG. 3, the wide-area refrigerant flow passage 32 is formed in a single stroke from the inlet 32p to the outlet 32q over the entire area of ​​the cooling substrate 30 corresponding to the wafer mounting surface 22a when the cross section cut by a horizontal plane passing through the wide-area refrigerant flow passage 32 and the hole refrigerant flow passage 36 is viewed from above. In this embodiment, the wide-area refrigerant flow passage 32 is formed in a spiral shape. The wide-area refrigerant supply device 33 is connected to the inlet 32p and the outlet 32q of the wide-area refrigerant flow passage 32. The hole coolant flow passages 36 are formed in an annular shape in the peripheral area (area surrounded by a two-dot chain line in Figs. 2 and 3) of each gas hole 44 and each lift pin hole 48 so as to surround the entire circumference of each hole. Each hole coolant flow passage 36 branches at an inlet 36p and merges at an outlet 36q on the opposite side of the ring. All the hole coolant flow passages 36 are connected in series via a connecting flow passage 38, and auxiliary flow passages 39 are connected to both ends. The hole coolant flow passages 36, the connecting flow passage 38, and the auxiliary flow passage 39 are formed in a C-shape as a whole. The hole coolant supply device 37 is connected to an inlet 39p provided in the upstream auxiliary flow passage 39 and an outlet 39q provided in the downstream auxiliary flow passage 39, and is connected to all the hole coolant flow passages 36 via the auxiliary flow passage 39 and the connecting flow passage 38.

[0030] The wafer mounting table 10 is attached to a mounting plate 96 provided inside a chamber 94 by using a clamp member 70. The clamp member 70 is an annular member having a cross section in a substantially inverted L-shape, and has an inner peripheral step surface 70a. The wafer mounting table 10 and the mounting plate 96 are integrated by the clamp member 70. With the inner peripheral step surface 70a of the clamp member 70 placed on the flange portion 34 of the cooling substrate 30 of the wafer mounting table 10, a bolt 72 is inserted from the upper surface of the clamp member 70 and screwed into a screw hole provided on the upper surface of the mounting plate 96. The bolt 72 is attached to a plurality of locations (e.g., 8 locations or 12 locations) that are provided at equal intervals along the circumferential direction of the clamp member 70. The clamp member 70 and the bolt 72 may be made of an insulating material or a conductive material (metal, etc.).

[0031] Next, a manufacturing example of the wafer mounting table 10 will be described with reference to FIG. 5. FIG. 5 is a manufacturing process diagram of the wafer mounting table 10. First, a disk-shaped ceramic sintered body 120, which is the base of the ceramic base material 20, is manufactured by hot-pressing and sintering a ceramic powder compact (FIG. 5A). The ceramic sintered body 120 has a built-in wafer adsorption electrode 26. Next, a terminal hole upper portion 151a is formed between the lower surface of the ceramic sintered body 120 and the wafer adsorption electrode 26, and a gas hole upper portion 144a and a lift pin hole upper portion 148a that penetrate the ceramic sintered body 120 in the vertical direction are opened at predetermined positions (FIG. 5B). Then, a power supply terminal 54 is inserted into the terminal hole upper portion 151a to join the power supply terminal 54 and the wafer adsorption electrode 26 (FIG. 5C).

[0032] In parallel with this, two MMC disk members 131 and 136 are fabricated (FIG. 5D). Then, a plurality of holes penetrating in the vertical direction are drilled in both MMC disk members 131 and 136 (FIG. 5E). Specifically, a terminal hole intermediate portion 151b, a gas hole intermediate portion 144b, and a lift pin hole intermediate portion 148b are drilled in the upper MMC disk member 131. Also, a terminal hole lower portion 151c, a gas hole lower portion 144c, and a lift pin hole lower portion 148c are drilled in the lower MMC disk member 136. Also, a groove 132 that will eventually become the wide area refrigerant flow path 32, a groove 137 that will become the hole refrigerant flow path 36, a groove (not shown) that will become the connection flow path 38, and a groove (not shown) that will become the auxiliary flow path 39 are formed on the lower surface of the upper MMC disk member 131 (FIG. 5E). When the ceramic sintered body 120 is made of alumina, the MMC disk members 131, 136 are preferably made of SiSiCTi or AlSiC, because the thermal expansion coefficient of alumina is approximately the same as that of SiSiCTi or AlSiC.

[0033] The SiSiCTi disk member can be manufactured, 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 uniaxially pressed to produce a disk-shaped compact, which is then hot-press sintered in an inert atmosphere to obtain the SiSiCTi disk member.

[0034] Next, a metal bonding material is placed between the lower surface of the upper MMC disk member 131 and the upper surface of the lower MMC disk member 136, and a metal bonding material is placed on the upper surface of the upper MMC disk member 131. Each metal bonding material has a through hole at a position opposite to each hole. Then, the power supply terminal 54 of the ceramic sintered body 120 is inserted into the terminal hole intermediate part 151b and the terminal hole lower part 151c, and the ceramic sintered body 120 is placed on the metal bonding material placed on the upper surface of the upper MMC disk member 131. As a result, a laminate is obtained in which the lower MMC disk member 136, the metal bonding material, the upper MMC disk member 131, the metal bonding material, and the ceramic sintered body 120 are laminated in this order from below. The laminate is heated and pressurized (TCB) to obtain the bonded body 110 (FIG. 5F). The bonded body 110 is a ceramic sintered body 120 bonded to the upper surface of the MMC block 130, which is the base of the cooling base material 30, via the metal bonding layer 40. The MMC block 130 is formed by bonding an upper MMC disk member 131 and a lower MMC disk member 136 via a metal bonding layer 135. The MMC block 130 has a wide area refrigerant flow path 32, a hole refrigerant flow path 36, a connecting flow path 38 (not shown), an auxiliary flow path 39 (not shown), a terminal hole 51, a gas hole 44, and a lift pin hole 48. The terminal hole 51 is a hole in which a terminal hole upper portion 151a, a terminal hole intermediate portion 151b, and a terminal hole lower portion 151c are connected, and the gas hole 44 is a hole in which a gas hole upper portion 144a, a gas hole intermediate portion 144b, and a gas hole lower portion 144c are connected. The lift pin hole 48 is a hole in which a lift pin hole upper portion 148a, a lift pin hole intermediate portion 148b, and a lift pin hole lower portion 148c are connected.

[0035] For example, TCB is performed as follows. That is, the laminate is pressed and bonded at a temperature equal to or lower than the solidus temperature of the metal bonding material (for example, a temperature equal to or higher than the solidus temperature minus 20°C and equal to or lower than the solidus temperature), and then returned to room temperature. This causes the metal bonding material to become a metal bonding layer. As the metal bonding material, an Al-Mg based bonding material or an Al-Si-Mg based bonding material can be used. For example, when TCB is performed using an Al-Si-Mg based bonding material, the laminate is pressed in a heated state under a vacuum atmosphere. It is preferable to use a metal bonding material with a thickness of about 100 μm.

[0036] Next, the outer periphery of the ceramic sintered body 120 is cut to form a step, thereby forming the ceramic substrate 20 having the central portion 22 and the outer periphery 24. The outer periphery of the MMC block 130 is cut to form a step, thereby forming the cooling substrate 30 having the flange portion 34. An insulating tube 55 is disposed in the terminal hole 51, through which the power supply terminal 54 is inserted, from the lower surface of the ceramic substrate 20 to the lower surface of the cooling substrate 30. Furthermore, the insulating film 42 is formed by thermally spraying the side surface of the outer periphery 24 of the ceramic substrate 20, the periphery of the metal bonding layer 40, and the side surface of the cooling substrate 30 with ceramic powder (FIG. 5G). The seal band 22b and the small protrusions 22c are formed by, for example, blasting. In this manner, the wafer mounting table 10 is obtained.

[0037] Although the cooling substrate 30 in FIG. 1 is shown as an integral component, it may have a structure in which two components are joined by a metal joining layer as shown in FIG. 5G, or a structure in which three or more components are joined by a metal joining layer.

[0038] Next, an example of use of the wafer stage 10 will be described with reference to Fig. 1. As described above, the wafer stage 10 is fixed to the mounting plate 96 of the chamber 94 by the clamp members 70. A shower head 98 is disposed on the ceiling surface of the chamber 94, which ejects process gas into the chamber 94 from a number of gas injection holes.

[0039] A focus ring 78 is placed on the FR mounting surface 24a of the wafer mounting table 10, and a disk-shaped wafer W is placed on the wafer mounting surface 22a. The focus ring 78 has a step along the inner circumference of the upper end so as not to interfere with the wafer W. In this state, a DC voltage from the wafer suction DC power supply 52 is applied to the wafer suction electrode 26 to suction the wafer W onto the wafer mounting surface 22a. Then, the interior of the chamber 94 is set to a predetermined vacuum atmosphere (or reduced pressure atmosphere), and an RF voltage from the RF power supply 62 is applied to the cooling substrate 30 while a process gas is supplied from the shower head 98. Then, plasma is generated between the wafer W and the shower head 98. Then, the plasma is used to perform CVD film formation or etching on the wafer W. The focus ring 78 is also worn out as the wafer W is plasma-processed, but since the focus ring 78 is thicker than the wafer W, the focus ring 78 is replaced after processing a plurality of wafers W.

[0040] When the wafer W is processed with high-power plasma, it is necessary to efficiently cool the wafer W. In the wafer mounting table 10, a metal bonding layer 40 with high thermal conductivity is used as a bonding layer between the ceramic base material 20 and the cooling base material 30, instead of a resin layer with low thermal conductivity. Therefore, the ability to draw heat from the wafer W (heat extraction ability) is high. In addition, since the thermal expansion difference between the ceramic base material 20 and the cooling base material 30 is small, even if the stress relaxation of the metal bonding layer 40 is low, problems are unlikely to occur. Furthermore, the hole coolant flow passage 36 to which the coolant is supplied independently of the wide-area coolant flow passage 32 is formed in the peripheral area of ​​each gas hole 44 and each lift pin hole 48, so that the periphery of the hole coolant flow passage 36 can be cooled by temperature control independent of the periphery of the wide-area coolant flow passage 32.

[0041] In the wafer mounting table 10 of the present embodiment described above, the hole coolant flow passage 36 is provided in the peripheral region of at least one of the holes (three gas holes 44 and three lift pin holes 48 in the present embodiment) that penetrates the cooling substrate 30 in the vertical direction, to which the coolant is supplied independently of the wide-area coolant flow passage 32. Generally, the area directly above such a hole in the wafer W is likely to become a hot spot, but in the present embodiment, the hole coolant flow passage 36 is formed in the peripheral region of the hole, and the area can be cooled by temperature control independent of the area outside the peripheral region of the hole, so that this area can be cooled in a focused manner. For example, if the hole coolant flow passage 36 is supplied with a coolant that is lower in temperature than the wide-area coolant flow passage 32 (for example, 10° C. or more lower in temperature than the wide-area coolant flow passage 32), the low-temperature coolant promotes the removal of heat from the peripheral region of the hole. Also, if the hole coolant flow passage 36 is supplied with a coolant at a higher flow rate than the wide-area coolant flow passage 32, the temperature rise of the coolant is small, and the removal of heat from the peripheral region of the hole is promoted. Moreover, if the hole coolant flow passage 36 is supplied with a coolant having a higher flow rate than the wide area coolant flow passage 32, the high flow rate coolant promotes heat removal from the area around the hole. If the hole coolant flow passage 36 is supplied with a coolant having a higher thermal conductivity than the wide area coolant flow passage 32, the high thermal conductivity coolant promotes heat removal from the area around the hole. If the hole coolant flow passage 36 is supplied with a coolant having a higher specific heat than the wide area coolant flow passage 32, the temperature rise of the coolant is small, and heat removal from the area around the hole is promoted. If the hole coolant flow passage 36 is supplied with a coolant having a lower viscosity than the wide area coolant flow passage 32, the coolant is more likely to become turbulent, and heat removal from the area around the hole is promoted. Therefore, it is possible to suppress the occurrence of hot spots on the wafer W. Furthermore, if the volume ratio of the refrigerant flow path in the peripheral region of the hole (hole refrigerant flow path 36) is made larger than the volume ratio of the refrigerant flow path in the region outside the peripheral region of the hole (wide-area refrigerant flow path 32), the refrigerant flow paths are arranged at high density in the peripheral region of the hole, thereby promoting heat removal in the peripheral region of the hole.

[0042] Furthermore, since the wide area refrigerant flow path 32 and the hole refrigerant flow path 36 are formed on the same plane parallel to the wafer mounting surface 22a, it is possible to form both flow paths more simply by forming the grooves 132 and 137 together in one MMC disk member 131 as shown in Figure 5E, rather than forming them in multiple stages, one on the upper side and the other on the lower side, with a plane parallel to the wafer mounting surface 22a in between.

[0043] It goes without saying that the present invention is not limited to the above-described embodiment, and can be embodied in various forms within the technical scope of the present invention.

[0044] In the above-described embodiment, the hole refrigerant passage 36 may have a heat exchange promotion structure. For example, as shown in the enlarged cross-sectional view of FIG. 6, fins 36a may be provided as a heat exchange promotion structure on the inner surface of the hole refrigerant passage 36 in the peripheral region of the gas hole 44. The refrigerant flowing through the hole refrigerant passage 36 provided with the fins 36a is more likely to become turbulent than when the fins 36a are not provided. Therefore, heat removal from the peripheral region of the gas hole 44 is promoted. The number and length of the fins 36a may be appropriately set according to the desired amount of heat removal. A similar structure may be adopted for the hole refrigerant passage 36 passing through the peripheral region of the lift pin hole 48. Alternatively, as shown in the enlarged cross-sectional view of FIG. 7, a narrow portion 36b in which the passage is narrowed may be provided as a heat exchange promotion structure in the middle of the hole refrigerant passage 36 in the peripheral region of the gas hole 44. The refrigerant flowing through the hole refrigerant passage 36 provided with the narrow portion 36b is more likely to become turbulent because the flow rate becomes faster at the narrow portion 36b. Therefore, the heat removal from the peripheral area of ​​the gas hole 44 is promoted. The hole coolant flow passage 36 passing through the peripheral area of ​​the lift pin hole 48 may have a similar structure. In addition, the wall surface (which may be the side surface or the upper and lower surfaces) of the hole coolant flow passage 36 may have a rougher surface than the wide area coolant flow passage 32 or may have irregularities as a heat exchange promotion structure. The coolant flowing through the hole coolant flow passage 36 having a rough surface or an irregular wall surface is more likely to become turbulent than when the wall surface is smooth. Therefore, the heat removal from the peripheral area of ​​the hole is promoted. In addition, the hole coolant flow passage 36 may be made to meander to serve as a heat exchange promotion structure. By making the hole coolant flow passage 36 meander, the flow is more likely to become turbulent. Therefore, the heat removal from the peripheral area of ​​the hole is promoted.

[0045] In the above-described embodiment, as shown in the enlarged cross-sectional view of FIG. 8, the distance d1 from the wafer W to the ceiling surface of the hole coolant flow passage 36 in the peripheral region of the gas hole 44 may be shorter than the distance d2 from the wafer W to the ceiling surface of the wide-area coolant flow passage 32. In this way, the coolant flowing through the hole coolant flow passage 36 has a smaller thermal resistance between the coolant and the wafer W than the coolant flowing through the wide-area coolant flow passage 32. This promotes heat removal from the peripheral region of the gas hole 44. Note that, in FIG. 8, the vertical length of the hole coolant flow passage 36 is longer than the wide-area coolant flow passage 32, but it may be the same length as the wide-area coolant flow passage 32. A similar structure may be adopted for the peripheral region of the lift pin hole 48.

[0046] In the above-mentioned embodiment, all of the plurality of hole refrigerant flow paths 36 are connected by the connecting flow paths 38, but all or some of them may not be connected by the connecting flow paths 38. For example, as shown in FIG. 9, all of the plurality of hole refrigerant flow paths 36 may be independent, and the connecting flow paths 38 may not be used. In this case, a refrigerant supply device may be connected individually to each of the hole refrigerant flow paths 36. In addition, in this case, an auxiliary flow path 39 may be connected to at least one of the upstream side (inlet 36p) and downstream side (outlet 36q) of each hole refrigerant flow path 36. Alternatively, the plurality of hole refrigerant flow paths 36 may be divided into a plurality of groups, and only the hole refrigerant flow paths 36 in a group including two or more hole refrigerant flow paths 36 may be connected by the connecting flow path 38. In this case, a refrigerant supply device may be connected individually to each group, and the auxiliary flow path 39 may be connected to at least one of the upstream side and downstream side of each group. In the above-mentioned embodiment, at least one of the auxiliary flow paths 39 may be omitted.

[0047] In the above embodiment, the hole coolant flow passage 36 in the peripheral region of the gas hole 44 is formed in an annular shape so as to surround the entire circumference of the gas hole 44, branched at the inlet 36p, and joined at the outlet 36q on the opposite side of the ring, but the shape and the arrangement of the inlet and outlet are not particularly limited as long as it is formed in the peripheral region of the gas hole 44. For example, as shown in FIG. 10, it may be formed in a C-shape so as to surround the periphery of the gas hole 44. In FIG. 10, it is formed without branching from the inlet 36p at one end of the C-shape to the outlet 36q at the other end. In addition, the hole coolant flow passage 36 in the peripheral region of the gas hole 44 may be formed in an annular shape, the arrangement of the inlet 36p and the outlet 36q may be the same as in FIG. 10, and it may be formed without branching from the inlet 36p to the outlet 36q. In addition, the hole coolant flow passage 36 in the peripheral region of the gas hole 44 may be formed in a spiral shape so as to surround the periphery of the gas hole 44. The hole coolant flow passage 36 in the peripheral region of the gas hole 44 may be formed so as to surround more than half the circumference of the hole. The surrounding area of ​​the lift pin hole 48 may also have a similar structure.

[0048] In the above embodiment, the wide-area refrigerant flow passage 32 and the hole refrigerant flow passage 36 are formed on the same plane, but they may be formed in multiple stages, one on the upper side and the other on the lower side, sandwiching a plane parallel to the wafer mounting surface 22a. For example, as shown in FIG. 11, the hole refrigerant flow passage 36 may be formed in multiple stages (two stages in FIG. 11) so that the hole refrigerant flow passage 36 is on the upper side and the wide-area refrigerant flow passage 32 is on the lower side. In this way, the degree of freedom in the arrangement of both flow passages can be increased compared to forming both flow passages on the same plane. For example, the wide-area refrigerant flow passage 32 can also be arranged in the peripheral area of ​​the hole to further promote heat removal from the peripheral area of ​​the hole. In addition, since the hole refrigerant flow passage 36 is arranged on the upper side, as explained in FIG. 8, the distance d1 from the wafer W to the ceiling surface of the hole refrigerant flow passage 36 is shorter than the distance d2 from the wafer W to the ceiling surface of the wide-area refrigerant flow passage 32, and therefore heat removal from the peripheral area of ​​the hole is promoted. In the wafer mounting table 10 of FIG. 11, the wide-area refrigerant flow passage 32 is formed in a single stroke from the inlet 32p to the outlet 32q over the entire area of ​​the cooling substrate 30 corresponding to the wafer mounting surface 22a when a cross section cut along a horizontal plane passing through the wide-area refrigerant flow passage 32 is viewed from above, as shown in FIG. 12. Here, the wide-area refrigerant flow passage 32 is also arranged in the peripheral area of ​​the gas hole 44 and the peripheral area of ​​the lift pin hole 48. In the wafer mounting table 10 of FIG. 11, the hole refrigerant flow passage 36 is formed in a shape when a cross section cut along a horizontal plane passing through the hole refrigerant flow passage 36 is viewed from above, as shown in FIG. 13, which is the same shape as the cross section of the hole refrigerant flow passage 36 of the above-mentioned embodiment when viewed from above in FIG. 3. In this way, if the wide-area refrigerant flow passage 32 is also arranged in the peripheral area of ​​the gas hole 44 and the peripheral area of ​​the lift pin hole 48, the volume ratio of the refrigerant flow passage in the peripheral area of ​​the hole can be increased by the amount of the wide-area refrigerant flow passage 32 arranged in the peripheral area of ​​the hole. In this case, it is preferable that the volume ratio of the coolant flow passage in the area around the hole is greater than the volume ratio of the coolant flow passage in the area outside the area around the hole, which further promotes heat removal from the area around the hole.

[0049] In the above-described embodiment, the hole coolant flow passage 36 is provided in the peripheral areas of all the gas holes 44 and all the lift pin holes 48, but is not particularly limited to this. For example, the hole coolant flow passage 36 may be provided in the peripheral areas of some of these holes (for example, areas that are particularly likely to become hot spots). Alternatively or in addition to these, the hole coolant flow passage may be provided in the peripheral areas of holes that penetrate the cooling substrate 30 in the vertical direction, such as the terminal hole 51 and the temperature measurement hole (not shown). The temperature measurement hole is a hole through which a temperature measurement member such as a thermocouple is inserted. Note that the hole coolant flow passage in the peripheral area of ​​the terminal hole 51 and the hole coolant flow passage in the peripheral area of ​​the temperature measurement hole may adopt each aspect described for the hole coolant flow passage 36.

[0050] In the above-described embodiment, the hole coolant passage 36 is provided in the peripheral region of the hole penetrating the cooling substrate in the vertical direction, such as the gas hole 44 and the lift pin hole 48, but the present invention is not limited to this, and a local coolant passage may be provided in a predetermined local region that is likely to become a hot spot. For example, a local coolant passage may be provided in a region where the heat extraction capacity tends to be locally inferior to the surrounding area, such as near the coolant outlet where the coolant temperature is high. Also, a local coolant passage may be provided in a region where the heat extraction capacity tends to be locally inferior to the surrounding area due to a difference in structure or material from the surrounding area.

[0051] In the above-described embodiment, the cooling substrate 30 is made of MMC, but is not limited thereto. The cooling substrate 30 may be made of metal (e.g., aluminum, titanium, molybdenum, tungsten, and alloys thereof). The cooling substrate 30 may also be made of ceramic matrix composite material (CMC). Both MMC and CMC are composite materials of metal and ceramic. Examples of CMC include materials containing Si, SiC, and Ti, and materials in which a porous SiC body is impregnated with Al and / or Si.

[0052] In the above-described embodiment, the ceramic base material 20 and the cooling base material 30 are bonded to each other via the metal bonding layer 40, which has a high thermal conductivity and is highly effective in the present invention, but is not limited thereto. For example, a resin bonding layer may be used instead of the metal bonding layer 40.

[0053] In the above embodiment, the wide-area refrigerant flow passage 32 has a spiral shape in plan view, but is not limited thereto. For example, the wide-area refrigerant flow passage 32 may have a zigzag shape in plan view. Specifically, an inlet and an outlet may be provided at two points near the outer periphery that are point-symmetrical with respect to the center of the cooling substrate 30 in plan view, and the wide-area refrigerant flow passage 32 may be formed so that the inlet and outlet are zigzag in a single stroke.

[0054] In the above-described embodiment, the wafer attracting electrode 26 is built into the central portion 22 of the ceramic base material 20, but instead of or in addition to this, an RF electrode for generating plasma or a heater electrode (resistance heating element) may be built in. Also, a focus ring (FR) attracting electrode, an RF electrode, or a heater electrode may be built in the outer circumferential portion 24 of the ceramic base material 20.

[0055] In the above-described embodiment, the ceramic sintered body 120 in FIG. 5A was produced by hot-press sintering a ceramic powder compact. However, the compact may be produced by stacking a plurality of tape compacts, by a mold casting method, or by compressing ceramic powder.

[0056] This application claims priority from Japanese Patent Application No. 2022-30790, filed on March 1, 2022, the entire contents of which are incorporated herein by reference. [Industrial Applicability]

[0057] The wafer stage of the present invention is used in, for example, a semiconductor manufacturing device. [Explanation of symbols]

[0058] 10 wafer mounting table, 20 ceramic substrate, 22 center portion, 22a wafer mounting surface, 22b seal band, 22c small protrusion, 22d reference surface, 24 outer periphery, 24a focus ring mounting surface, 26 wafer suction electrode, 30 cooling substrate, 32 wide area coolant flow path, 32p inlet, 32q outlet, 33 wide area coolant supply device, 34 flange portion, 36 hole coolant flow path, 36a fin, 36b narrow portion, 36p inlet, 36q outlet, 37 hole coolant supply device, 38 connection flow path, 39 auxiliary flow path, 39p inlet, 39q outlet, 40 metal bonding layer, 42 insulating film, 44 gas hole, 46 gas supply source, 48 lift pin hole, 51 terminal hole, 52 wafer suction DC power source, 53 low pass filter (LPF), 54 power supply terminal, 55 insulating tube, 62 RF power supply, 63 high pass filter (HPF), 64 power supply terminal, 70 clamp member, 70a inner peripheral step surface, 72 bolt, 78 focus ring, 94 chamber, 96 mounting plate, 98 shower head, 110 bonded body, 120 ceramic sintered body, 130 MMC block, 131 MMC disk member, 132 groove, 135 metal bonding layer, 136 MMC disk member, 137 groove, 144a gas hole upper portion, 144b gas hole middle portion, 144c gas hole lower portion, 148a lift pin hole upper portion, 148b lift pin hole middle portion, 148c lift pin hole lower portion, 151a terminal hole upper portion, 151b terminal hole middle portion, 151c terminal hole lower portion, d1, d2 distance, W wafer.

Claims

1. a ceramic substrate having a wafer mounting surface on an upper surface thereof and incorporating an electrode; a cooling substrate bonded to a lower surface of the ceramic substrate and configured to cool the ceramic substrate; Equipped with the cooling base material has, as coolant flow paths, a wide-area coolant flow path formed over an entire area corresponding to the wafer mounting surface, and a local coolant flow path formed in a predetermined local area, to which a coolant is supplied independently of the wide-area coolant flow path; The local refrigerant flow path is supplied with the refrigerant having a lower temperature than the wide area refrigerant flow path. Wafer placement stage.

2. a ceramic substrate having a wafer mounting surface on an upper surface thereof and incorporating an electrode; a cooling substrate bonded to a lower surface of the ceramic substrate and configured to cool the ceramic substrate; Equipped with the cooling base material has, as coolant flow paths, a wide-area coolant flow path formed over an entire area corresponding to the wafer mounting surface, and a local coolant flow path formed in a predetermined local area, to which a coolant is supplied independently of the wide-area coolant flow path; The refrigerant is supplied to the local refrigerant flow path at a higher flow rate than the wide area refrigerant flow path. Wafer placement stage.

3. a ceramic substrate having a wafer mounting surface on an upper surface thereof and incorporating an electrode; a cooling substrate bonded to a lower surface of the ceramic substrate and configured to cool the ceramic substrate; Equipped with the cooling base material has, as coolant flow paths, a wide-area coolant flow path formed over an entire area corresponding to the wafer mounting surface, and a local coolant flow path formed in a predetermined local area, to which a coolant is supplied independently of the wide-area coolant flow path; In the cooling material, a volume ratio of the coolant flow path in the local region is greater than a volume ratio of the coolant flow path in a region outside the local region. Wafer placement stage.

4. a ceramic substrate having a wafer mounting surface on an upper surface thereof and incorporating an electrode; a cooling substrate bonded to a lower surface of the ceramic substrate and configured to cool the ceramic substrate; Equipped with the cooling base material has, as coolant flow paths, a wide-area coolant flow path formed over an entire area corresponding to the wafer mounting surface, and a local coolant flow path formed in a predetermined local area, to which a coolant is supplied independently of the wide-area coolant flow path; The local refrigerant flow path is supplied with the refrigerant having a higher thermal conductivity than the wide area refrigerant flow path. Wafer placement stage.

5. a ceramic substrate having a wafer mounting surface on an upper surface thereof and incorporating an electrode; a cooling substrate bonded to a lower surface of the ceramic substrate and configured to cool the ceramic substrate; Equipped with the cooling base material has, as coolant flow paths, a wide-area coolant flow path formed over an entire area corresponding to the wafer mounting surface, and a local coolant flow path formed in a predetermined local area, to which a coolant is supplied independently of the wide-area coolant flow path; The local refrigerant flow path is supplied with the refrigerant having a larger specific heat than the wide area refrigerant flow path. Wafer placement stage.

6. the local refrigerant flow path is provided with a heat exchange promotion structure that promotes heat exchange between the refrigerant flowing through the local refrigerant flow path and the wafer placed on the wafer placement surface. The wafer mounting table according to any one of claims 1 to 5.

7. the wide area refrigerant flow path and the local refrigerant flow path are formed on the same plane parallel to the wafer mounting surface; The wafer mounting table according to any one of claims 1 to 5.

8. the wide area refrigerant flow path and the local refrigerant flow path are formed in multiple stages, one on the upper side and the other on the lower side, with a plane parallel to the wafer mounting surface in between; The wafer mounting table according to any one of claims 1 to 5.

9. A plurality of holes are provided through the cooling substrate in the vertical direction, The local region is a peripheral region of at least one hole among the plurality of holes. The wafer mounting table according to any one of claims 1 to 5.

10. A plurality of holes are provided through the cooling substrate in the vertical direction, the local region is a peripheral region of at least one hole among the plurality of holes, The hole is at least one of a power supply member insertion hole that is provided in the wafer mounting table from the electrode downward and through which a power supply member that supplies power to the electrode is inserted, a lift pin hole that penetrates the wafer mounting table in the vertical direction and through which a lift pin is inserted, a gas hole that penetrates the wafer mounting surface in the vertical direction and supplies gas to the wafer mounting surface, and a temperature measurement hole that penetrates the cooling substrate in the vertical direction and through which a temperature measurement member is inserted. The wafer mounting table according to any one of claims 1 to 5.

11. a ceramic substrate having a wafer mounting surface on an upper surface thereof and incorporating an electrode; a cooling substrate bonded to a lower surface of the ceramic substrate and configured to cool the ceramic substrate; Equipped with the cooling base material has, as coolant flow paths, a wide-area coolant flow path formed over an entire area corresponding to the wafer mounting surface, and a local coolant flow path formed in a predetermined local area, to which a coolant is supplied independently of the wide-area coolant flow path; A plurality of holes are provided through the cooling substrate in the vertical direction, the local region is a peripheral region of at least one hole among the plurality of holes, The local refrigerant flow path includes a plurality of hole refrigerant flow paths provided in a peripheral region of the hole, and the plurality of hole refrigerant flow paths are provided independently without being connected to each other. Wafer placement stage.

12. a ceramic substrate having a wafer mounting surface on an upper surface thereof and incorporating an electrode; a cooling substrate bonded to a lower surface of the ceramic substrate and configured to cool the ceramic substrate; A wafer mounting table comprising: the cooling base material has, as coolant flow paths, a wide-area coolant flow path formed over an entire area corresponding to the wafer mounting surface, and a local coolant flow path formed in a predetermined local area, to which a coolant is supplied independently of the wide-area coolant flow path; A plurality of holes are provided through the cooling substrate in the vertical direction, the local region is a peripheral region of at least one hole among the plurality of holes, the holes include lift pin holes penetrating the wafer mounting table in the vertical direction and through which lift pins are inserted, and gas holes penetrating the wafer mounting surface in the vertical direction and through which gas is supplied to the wafer mounting surface; and the local refrigerant flow paths are formed in peripheral areas of each of the lift pin holes and each of the gas holes, and the hole refrigerant flow paths are all connected in series via a connection flow path. Wafer placement stage.

13. a ceramic substrate having a wafer mounting surface on an upper surface thereof and incorporating an electrode; a cooling substrate bonded to a lower surface of the ceramic substrate and configured to cool the ceramic substrate; Equipped with the cooling base material has, as coolant flow paths, a wide-area coolant flow path formed over an entire area corresponding to the wafer mounting surface, and a local coolant flow path formed in a predetermined local area, to which a coolant is supplied independently of the wide-area coolant flow path; the wide area refrigerant flow path and the local refrigerant flow path are formed on the same plane parallel to the wafer mounting surface, The wide-area refrigerant flow path is formed in a spiral shape, and the local refrigerant flow path is formed in a region on the outer circumferential side of an innermost flow path of the wide-area refrigerant flow path and on the inner circumferential side of an outermost flow path of the wide-area refrigerant flow path. Wafer placement stage.

14. a ceramic substrate having a wafer mounting surface on an upper surface thereof and incorporating an electrode; a cooling substrate bonded to a lower surface of the ceramic substrate and configured to cool the ceramic substrate; Equipped with the cooling base material has, as coolant flow paths, a wide-area coolant flow path formed over an entire area corresponding to the wafer mounting surface, and a local coolant flow path formed in a predetermined local area, to which a coolant is supplied independently of the wide-area coolant flow path; the wide area refrigerant flow path and the local refrigerant flow path are formed on the same plane parallel to the wafer mounting surface, the wide-area refrigerant flow path is formed in a spiral shape, and the local refrigerant flow path is formed in a region on the outer circumferential side of an innermost flow path of the wide-area refrigerant flow path and on the inner circumferential side of an outermost flow path of the wide-area refrigerant flow path, The local refrigerant flow path is provided in a plurality of parts, and the plurality of local refrigerant flow paths are connected in series via a connecting flow path to form a C-shape as a whole. Wafer placement stage.

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