Wafer mounting table

Abstract

To improve the soaking property of a wafer.SOLUTION: A coolant passage 32 of a wafer mounting table includes a first gradually changing section 34 starting from an inlet 32a, and a second gradually changing section 36 provided on the downstream side of the first gradually changing section 34. The first gradually changing section 34 is provided such that the cross-sectional area of the refrigerant flow passage 32 gradually decreases from the starting point 34a of the first gradually changing section 34 in the refrigerant flow direction. The second gradually changing section 36 is provided such that, after the cross-sectional area of the refrigerant passage 32 is once expanded from the cross-sectional area of the refrigerant passage 32 at the end point 36a of the first gradually changing section 34 in the first expanded section 35 provided immediately before the start point 34b of the second gradually changing section 36, the cross-sectional area of the refrigerant passage 32 gradually decreases from the start point 36a of the second gradually changing section 36 in the flow direction of the refrigerant.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Semiconductor manufacturing equipment employs wafer mounting tables such as ceramic heaters for heating wafers and electrostatic chucks for attracting and holding wafers. Patent Document 1 discloses a wafer mounting table of this type that includes a ceramic plate having a wafer mounting surface on its upper surface and a built-in electrode, and a cooling plate attached to the lower surface of the ceramic plate. A refrigerant flow path is provided inside the cooling plate. The refrigerant flow path is spirally shaped from the inlet to the outlet in a plan view. The cross-sectional area of ​​the refrigerant flow path gradually narrows from the inlet to the outlet. The temperature of the refrigerant increases from the inlet to the outlet of the refrigerant flow path, but the flow velocity of the refrigerant increases from the inlet to the outlet of the refrigerant flow path. This improves the uniform temperature of the wafer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-28961 A (Fig. 5, Fig. 8) Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a configuration in which the cross-sectional area of ​​the coolant flow path gradually narrows from the inlet to the outlet of the coolant flow path, it is sometimes not possible to sufficiently improve the temperature uniformity of the wafer.

[0005] The present invention has been made to solve such problems, and its main object is to improve the temperature uniformity of the wafer. [Means for solving the problem]

[0006] [1] The wafer mounting table of the present invention comprises: a ceramic plate having a wafer mounting surface on its upper surface and incorporating an electrode; a cooling plate provided on the lower surface of the ceramic plate; a refrigerant flow path provided inside the cooling plate, the refrigerant flow path having an inlet provided on one of an outer periphery side and a center side of the cooling plate and an outlet provided on the other of the outer periphery side and the center side of the cooling plate, the refrigerant flow path being spirally formed from the inlet to the outlet in a plan view; A wafer mounting table comprising: the refrigerant flow path has a first gradual change section that starts from the inlet and a second gradual change section that is provided downstream of the first gradual change section, The first gradual change section is provided such that a cross-sectional area of ​​the refrigerant flow path gradually decreases as the refrigerant progresses from a starting point of the first gradual change section in a flow direction of the refrigerant, The second gradual change section is configured such that, in a first expansion section provided immediately before the starting point of the second gradual change section, a cross-sectional area of ​​the refrigerant flow path is once expanded from a cross-sectional area of ​​the refrigerant flow path at an end point of the first gradual change section, and then the cross-sectional area of ​​the refrigerant flow path gradually decreases as the refrigerant progresses from the starting point of the second gradual change section in a flow direction of the refrigerant. It is something.

[0007] In this wafer mounting table, the first gradual change section is configured so that the cross-sectional area of ​​the refrigerant flow path gradually decreases (in other words, the refrigerant velocity gradually increases) as the refrigerant progresses from the starting point of the first gradual change section in the direction of refrigerant flow. In the first gradual change section of the refrigerant flow path, the temperature of the refrigerant decreases upstream and increases downstream, and the flow velocity of the refrigerant decreases upstream and increases downstream (in other words, the heat exchange efficiency (cooling efficiency) of the refrigerant decreases upstream and increases downstream). This reduces the difference in heat removal capacity between the upstream and downstream sections of the first gradual change section. Meanwhile, the second gradual change section is configured so that the cross-sectional area of ​​the refrigerant flow path is expanded from the cross-sectional area of ​​the refrigerant flow path at the end point of the first gradual change section in the first expansion section immediately before the starting point of the second gradual change section. Then, the cross-sectional area of ​​the refrigerant flow path gradually decreases as the refrigerant progresses in the direction of refrigerant flow. For the same reasons as in the first gradual change section, the difference in heat removal capacity between the upstream and downstream sections of the second gradual change section is also reduced. In particular, in the second gradual change section, the cross-sectional area of ​​the refrigerant flow path is temporarily expanded immediately before the starting point of the second gradual change section, so that the difference in cross-sectional area between the upstream and downstream of the second gradual change section can be increased while suppressing pressure loss of the refrigerant flowing through the second gradual change section, thereby improving the temperature uniformity of the wafer.

[0008] [2] In the wafer stage of the present invention (the wafer stage described in [1] above), the length of the first expansion section may be shorter than the length of the first gradual change section. In this way, the first gradual change section can be lengthened.

[0009] [3] In the wafer mounting table of the present invention (the wafer mounting table described in [1] or [2] above), the end point of the first gradual change section may be located near a point that is one revolution along the refrigerant flow path from the start point of the first gradual change section. This makes it possible to make the amount of heat removed by the refrigerant approximately uniform over approximately one revolution of the refrigerant flow path in which the first gradual change section is located.

[0010] The term "near the point where one revolution has been made" may be a point where one revolution has been made, a point where 0.8 to 1 revolution has been made, or a point where 1 to 1.2 revolutions have been made.

[0011] [4] In the wafer stage of the present invention (the wafer stage described in any one of [1] to [3] above), the end point of the first gradual change section may coincide with the start point of the first expansion section. This allows for immediate transition to the first expansion section after the end of the first gradual change section.

[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 first expansion section may be a non-arc (e.g., linear) section provided midway along the circumferential portion of the spiral-shaped coolant flow path. In this case, the flow velocity distribution of the coolant changes in the non-arc section provided midway along the circumferential portion, and the cross-sectional area of ​​the coolant flow path can be expanded by utilizing this section in a relatively short distance.

[0013] [6] In the wafer mounting table of the present invention (the wafer mounting table described in any one of [1] to [5] above), the distance between the ceiling surface of the refrigerant channel and the wafer mounting surface may be constant from the inlet to the outlet of the refrigerant channel, and the cross-sectional area of ​​the refrigerant channel may be changed by changing the width while keeping the cross-sectional height of the refrigerant channel constant. In this way, the cross-sectional area of ​​the refrigerant channel can be changed by changing the width of the refrigerant channel while keeping the distance between the ceiling surface of the refrigerant channel and the wafer mounting surface constant and keeping the cross-sectional height of the refrigerant channel constant, making it possible to manufacture the wafer mounting table of the present invention relatively easily.

[0014] [7] In the wafer mounting table of the present invention (the wafer mounting table described in any one of [1] to [6] above), the refrigerant flow path may have a third gradually changing section downstream of the second gradually changing section, and the third gradually changing section may be configured such that, in a second expansion section provided immediately before the start point of the third gradually changing section, the cross-sectional area of ​​the refrigerant flow path is once expanded from the cross-sectional area of ​​the refrigerant flow path at the end point of the second gradually changing section, and then the cross-sectional area of ​​the refrigerant flow path gradually decreases as the refrigerant flow progresses from the start point of the third gradually changing section in the flow direction of the refrigerant. In this way, by further providing a third gradually changing section, the temperature uniformity of the wafer can be further improved. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a cross-sectional view showing a schematic configuration of the wafer mounting table 10. [Figure 2] FIG. [Figure 3] 4A to 4C are diagrams showing the manufacturing process of the cooling plate 30. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] Fig. 1 is a cross-sectional view showing a schematic configuration of the wafer mounting table 10 of this embodiment (a cross-sectional view of the wafer mounting table 10 cut along a plane including the central axis of the wafer mounting table 10), and Fig. 2 is a plan view of the refrigerant flow path 32 (a cross-sectional view of the cooling plate 30 cut along a horizontal plane passing through the refrigerant flow path 32 and viewed from above). Note that in the following description, the terms up and down, left and right, and front and back may be used, but these terms merely refer to relative positional relationships.

[0017] The wafer mounting table 10 is an example of a semiconductor manufacturing equipment component used to process a wafer W. As shown in FIG. 1, the wafer mounting table 10 includes a ceramic plate 20, a cooling plate 30, and a bonding layer 40.

[0018] The ceramic plate 20 is a stepped circular plate member having a wafer mounting surface 20a on its upper surface. For example, the diameter of the upper part of the ceramic plate 20 is 300 mm, the diameter of the lower part is 340 mm, and the diameter of the wafer W is approximately 300 mm. The ceramic plate 20 is made of a ceramic-containing material. The ceramic-containing material is a material whose main component is ceramic, and may contain, in addition to ceramic, components derived from sintering aids (e.g., rare earth elements, etc.) and unavoidable components. The main component means that the proportion of the total is 50 mass% or more. Examples of ceramics include alumina and aluminum nitride.

[0019] An electrostatic electrode 22 is embedded in the upper part of the ceramic plate 20. The electrostatic electrode 22 is formed of a material containing a metal such as W, Mo, WC, or MoC. The metal used for the electrostatic electrode 22 preferably has a thermal expansion coefficient close to that of the ceramic plate 20. To make the thermal expansion coefficient of the electrostatic electrode 22 close to that of the ceramic plate 20, the electrostatic electrode 22 may contain the ceramic contained in the ceramic plate 20. The electrostatic electrode 22 is a disk-shaped or mesh-shaped unipolar electrostatic electrode. The layer of the ceramic plate 20 above the electrostatic electrode 22 functions as a dielectric layer. Although not shown, a DC power supply for electrostatic attraction is connected to the electrostatic electrode 22 via a power supply member.

[0020] The cooling plate 30 is a circular plate member having a coolant flow passage 32 through which a coolant can circulate. The diameter of the cooling plate 30 is the same as the diameter of the lower portion of the ceramic plate 20. The coolant flowing through the coolant flow passage 32 is preferably a liquid, preferably electrically insulating. Examples of electrically insulating liquids include fluorine-based inert liquids. The cooling plate 30 is made of a conductive material containing, for example, a metal. Examples of conductive materials include metals and composite materials. Examples of metals include Al, Ti, Mo, and alloys thereof. Examples of composite materials include metal matrix composites (MMCs) and ceramic matrix composites (CMCs). Specific examples of such composite materials include materials containing Si, SiC, and Ti, and materials in which porous SiC is impregnated with Al and / or Si. A material containing Si, SiC, and Ti is called SiSiCTi, a material in which a porous SiC body is impregnated with Al is called AlSiC, and a material in which a porous SiC body is impregnated with Si is called SiSiC. It is preferable to select a material for the cooling plate 30 that has a thermal expansion coefficient close to that of the material for the ceramic plate 20. The cooling plate 30 is also used as an RF electrode.

[0021] As shown in FIG. 2, the refrigerant flow path 32 is provided so as to spread over the entire surface of the ceramic plate 20 in a plan view. The refrigerant flow path 32 is formed in a spiral shape from an inlet 32a provided on the outer periphery of the cooling plate 30 to an outlet 32b provided on the center side of the cooling plate 30. In this embodiment, the refrigerant flow path 32 is based on multiple (six in this case) concentric flow paths of different diameters, and is formed in a spiral shape by connecting adjacent outer and inner circles with linear flow paths. The inlet 32a is provided on the outer periphery of the cooling plate 30 so that one end of the refrigerant flow path 32 opens to the underside of the cooling plate 30. The outlet 32b is provided on the center side of the cooling plate 30 so that the other end of the refrigerant flow path 32 opens to the underside of the cooling plate 30. The inlet 32a and the outlet 32b are connected to a refrigerant circulation pump (not shown) that adjusts the temperature of the refrigerant. The refrigerant flow path 32 has a first gradual change section 34, a second gradual change section 36, and a third gradual change section 38.

[0022] The first gradual change section 34 is an arc portion (indicated by an arc-shaped solid arrow in FIG. 2 ) at the outermost periphery of the spiral-shaped refrigerant flow path 32. The first gradual change section 34 is a section that extends approximately one revolution from a starting point 34a (inlet 32a) along the refrigerant flow direction to an end point 34b. The end point 34b of the first gradual change section 34 is located near a point that has been completed one revolution along the refrigerant flow path 32 from the starting point 34a of the first gradual change section 34 (e.g., a point that has been completed 0.8 to 1 revolution). The first gradual change section 34 is configured such that the cross-sectional area of ​​the refrigerant flow path 32 gradually decreases as the refrigerant flow progresses from the starting point 34a in the refrigerant flow direction. The cross-sectional area of ​​the refrigerant flow path 32 is the area of ​​a cross section obtained by cutting the refrigerant flow path 32 in a direction perpendicular to the upper surface of the cooling plate 30 and perpendicular to the refrigerant flow (the same applies below). In this embodiment, the cross section of the refrigerant flow path 32 is rectangular. The distance between the ceiling surface of the refrigerant flow path 32 and the wafer mounting surface 20a is constant from the inlet 32a to the outlet 32b of the refrigerant flow path 32. The cross-sectional area of ​​the refrigerant flow path 32 is changed by changing the width while keeping the height of the cross section of the refrigerant flow path 32 constant. For example, the width of the first gradually changing section 34 is 8 mm at the starting point 34a, and gradually decreases from there in the direction of the refrigerant flow, reaching 6 mm at the end point 34b.

[0023] The second gradual change section 36 is the second arc portion (indicated by the arc-shaped solid arrow in FIG. 2 ) counting from the outermost periphery of the spiral-shaped refrigerant flow path 32. The second gradual change section 36 is a section that extends approximately one revolution from a starting point 36a to an end point 36b along the refrigerant flow direction. The end point 36b of the second gradual change section 36 is located near a point that has been completed one revolution along the refrigerant flow path 32 from the starting point 36a of the second gradual change section 36 (e.g., a point that has been completed 0.8 to 1 revolution). A first expansion section 35 is located immediately before the starting point 36a of the second gradual change section 36. The first expansion section 35 is located between the end point 34b of the first gradual change section 34 and the starting point 36a of the second gradual change section 36. The length of the first expansion section 35 is shorter than the lengths of the first gradual change section 34 and the second gradual change section 36. The first expansion section 35 is located in a linear portion of the refrigerant flow path 32 where the arc changes from the outermost circular arc to the second arc counting from the outermost circular arc (indicated by a straight dotted arrow in FIG. 2). In the first expansion section 35, the cross-sectional area of ​​the refrigerant flow path 32 expands from an end point 34b of the first gradual change section 34 toward a start point 36a of the second gradual change section 36. Specifically, in the first expansion section 35, the cross-sectional height of the refrigerant flow path 32 is constant, and the width of the refrigerant flow path 32 at the end point 34b of the first gradual change section 34 gradually expands toward the start point 36a of the second gradual change section 36. For example, the width of the refrigerant flow path 32 at the end point 34b of the first gradual change section 34 is 6 mm, and gradually expands from there, to a width of 8 mm at the start point 36a of the second gradual change section 36.

[0024] In the second gradually changing section 36, the cross-sectional area of ​​the refrigerant flow path 32 gradually decreases as the refrigerant progresses from the starting point 36a in the direction of the refrigerant flow. Again, the cross-sectional area of ​​the refrigerant flow path 32 is changed by changing the width while keeping the height of the cross section of the refrigerant flow path 32 constant. For example, the width of the second gradually changing section 36 is 8 mm at the starting point 36a, and gradually decreases as the refrigerant progresses in the direction of the refrigerant flow, reaching 6 mm at the end point 36b.

[0025] The third gradual change section 38 is the third arc portion (indicated by the arc-shaped solid arrow in FIG. 2 ) counting from the outermost periphery of the spiral-shaped refrigerant flow path 32. The third gradual change section 38 is a section that extends approximately one revolution from a starting point 38a to an end point 38b along the refrigerant flow direction. The end point 38b of the third gradual change section 38 is located near a point that has been completed one revolution along the refrigerant flow path 32 from the starting point 38a of the third gradual change section 38 (e.g., a point that has been completed 0.8 to 1 revolution). The second expansion section 37 is located immediately before the starting point 38a of the third gradual change section 38. The second expansion section 37 is located between the end point 36b of the second gradual change section 36 and the starting point 38a of the third gradual change section 38. The length of the second expansion section 37 is shorter than the lengths of the second gradual change section 36 and the third gradual change section 38. The second expansion section 37 is located in a linear portion of the refrigerant flow path 32 where the second arc counting from the outermost periphery switches to the third arc counting from the outermost periphery (indicated by a linear dotted arrow in FIG. 2). In the second expansion section 37, the cross-sectional area of ​​the refrigerant flow path 32 expands from the end point 36b of the second gradual change section 36 toward the start point 38a of the third gradual change section 38. Specifically, in the second expansion section 37, the width of the refrigerant flow path 32 at the end point 36b of the second gradual change section 36 gradually expands toward the start point 38a of the third gradual change section 38. For example, the width of the refrigerant flow path 32 at the end point 36b of the second gradual change section 36 is 6 mm, and gradually expands from there, to a width of 8 mm at the start point 38a of the third gradual change section 38.

[0026] In the third gradual change section 38, the cross-sectional area of ​​the refrigerant flow path 32 gradually decreases as the refrigerant flows from the starting point 38a in the refrigerant flow direction. Again, the cross-sectional area of ​​the refrigerant flow path 32 is changed by changing the width while keeping the height of the cross-section of the refrigerant flow path 32 constant. For example, the width of the third gradual change section 38 is 8 mm at the starting point 38a, and gradually decreases from there in the refrigerant flow direction, reaching 6 mm at the end point 38b. The cross-sectional area of ​​the refrigerant flow path 32 from the end point 38b of the third gradual change section 38 to the outlet 32b of the refrigerant flow path 32 is constant (the height and width of the cross-section are constant).

[0027] The bonding layer 40 bonds the lower surface of the ceramic plate 20 to the upper surface of the cooling plate 30. The bonding layer 40 may be, for example, a metallic bonding layer formed of solder or a metal brazing material. The metallic bonding layer may be formed, for example, by TCB (thermal compression bonding). TCB is a known method in which a metallic bonding material is sandwiched between two members to be joined and the two members are pressure-bonded while heated to a temperature below the solidus temperature of the metallic bonding material. An organic adhesive layer may be used as the bonding layer 40 instead of the metallic bonding layer.

[0028] Next, an example of how the wafer mounting table 10 is used will be described. First, the wafer mounting table 10 is installed in a vacuum chamber (not shown), and a wafer W is placed on the wafer mounting surface 20a of the wafer mounting table 10. Then, a voltage is applied to the electrostatic electrode 22 from a DC power supply (not shown). This causes the wafer W to be attracted and fixed to the wafer mounting surface 20a. The vacuum chamber is then set to a vacuum or reduced-pressure atmosphere, and the wafer W is processed in the vacuum chamber. For example, when processing the wafer W with plasma, an upper electrode equipped with a showerhead is placed on the ceiling of the vacuum chamber, and a reactive gas is supplied from the showerhead into the space between the wafer W and the upper electrode while a high-frequency voltage is applied between the upper electrode and the cooling plate 30 to generate plasma. After processing of the wafer W is completed, the voltage application to the electrostatic electrode 22 is released. This causes the wafer W to be released from its attraction and fixed to the wafer mounting surface 20a.

[0029] When the temperature of the wafer W needs to be lowered while the wafer mounting table 10 is in use, a coolant is circulated through the coolant flow path 32. The coolant moves from the inlet 32a to the outlet 32b of the coolant flow path 32 while removing heat from the wafer W. Therefore, the temperature of the coolant is lowest at the inlet 32a of the coolant flow path 32 and highest at the outlet 32b.

[0030] In the first gradual change section 34 of the refrigerant flow path 32, the temperature of the refrigerant is lowest at the starting point 34a and highest at the end point 34b, but the flow velocity of the refrigerant is lowest at the starting point 34a and highest at the end point 34b. As a result, in the first gradual change section 34, the difference in the heat removal capacity of the refrigerant between the starting point 34a and the end point 34b is small.

[0031] In the second gradual change section 36 of the refrigerant flow path 32, the cross-sectional area of ​​the refrigerant flow path 32 is expanded in the first expansion section 35 from the cross-sectional area of ​​the refrigerant flow path 32 at the end point 34b of the first gradual change section 34, and then the cross-sectional area of ​​the refrigerant flow path 32 gradually decreases as the refrigerant flows from the start point 36a of the second gradual change section 36 in the direction of the refrigerant flow. In the second gradual change section 36, the refrigerant temperature is lowest at the start point 36a and highest at the end point 36b, but the refrigerant flow velocity is lowest at the start point 36a and highest at the end point 36b. As a result, the difference in the heat removal capacity of the refrigerant between the start point 36a and the end point 36b in the second gradual change section 36 is small.

[0032] In the third gradual change section 38 of the refrigerant flow path 32, the cross-sectional area of ​​the refrigerant flow path 32 is expanded in the second expansion section 37 from the cross-sectional area of ​​the refrigerant flow path 32 at the end point 36b of the second gradual change section 36, and then the cross-sectional area of ​​the refrigerant flow path 32 gradually decreases as the refrigerant progresses from the start point 38a of the third gradual change section 38 in the direction of refrigerant flow. In the third gradual change section 38, the refrigerant temperature is lowest at the start point 38a and highest at the end point 38b, but the refrigerant flow velocity is lowest at the start point 38a and highest at the end point 38b. As a result, the difference in the heat removal capacity of the refrigerant between the start point 38a and the end point 38b in the third gradual change section 38 is small.

[0033] Here, as an example, an example was adopted in which the refrigerant flow path 32 of the wafer mounting table 10 was provided with a first gradually changing section 34 (cross-sectional height of 15 mm (constant) and width gradually changing from 8 mm to 6 mm), a first expanding section 35 (cross-sectional height of 15 mm (constant) and width expanding from 6 mm to 8 mm), a second gradually changing section 36 (cross-sectional height of 15 mm (constant) and width gradually changing from 8 mm to 6 mm), a second expanding section 37 (cross-sectional height of 15 mm (constant) and width expanding from 6 mm to 8 mm), and a third gradually changing section 38 (cross-sectional height of 15 mm (constant) and width gradually changing from 8 mm to 6 mm). The section from the end point of the third gradually changing section 38 to the outlet 32b had a cross-sectional height of 15 mm (constant) and width of 6 mm (constant). On the other hand, as a comparative example, an example was adopted in which the cross-sectional height from the inlet 32a to the outlet 32b of the coolant flow path 32 of the wafer mounting table 10 was 15 mm (constant) and the width was 6 mm (constant). In each of the example and the comparative example, the heat input to the wafer mounting surface 20a was 50,000 W / cm 2 Then, the temperature distribution on the wafer mounting surface 20a was investigated when a steady state was reached under the condition that a constant supply of -10°C refrigerant was supplied to the refrigerant flow path 32. As a result, the temperature difference ΔT (difference between the maximum temperature and the minimum temperature) on the wafer mounting surface 20a was 5°C in the comparative example, while it was 1°C in the example. From these results, it was found that the example could improve the temperature uniformity of the wafer compared to the comparative example.

[0034] Next, a manufacturing example of the wafer mounting table 10 will be described. Since manufacturing examples of the ceramic plate 20 are known, a manufacturing example of the cooling plate 30 will be described here. FIG. 3 is a manufacturing process diagram of the cooling plate 30.

[0035] First, an upper disc member 30A and a lower disc member 30B made of a conductive material are fabricated ( FIG. 3A ). Then, one hole is formed vertically through the outer periphery and one hole is formed centrally of the lower disc member 30B, and a refrigerant channel groove 32X is formed on the underside of the upper disc member 30A ( FIG. 3B ). The hole on the outer periphery of the lower disc member 30B becomes the inlet 32a of the refrigerant channel 32, and the hole on the central side becomes the outlet 32b of the refrigerant channel 32. The refrigerant channel groove 32X formed in the upper disc member 30A has the same shape as the refrigerant channel 32 in a plan view, and the depth of the refrigerant channel groove 32X is the same throughout the entire refrigerant channel groove 32X. In other words, the refrigerant channel groove 32X has a constant depth but a width that varies depending on the position. Therefore, the refrigerant channel groove 32X can be formed relatively easily compared to forming a groove whose depth varies depending on the position.

[0036] Next, a metal bonding material 30C is placed between the upper surface of the lower circular plate member 30B and the lower surface of the upper circular plate member 30A to obtain a laminated body 50 (FIG. 3C). At this time, the outer peripheral end of the refrigerant flow channel groove 32X is aligned with the inlet 32a of the refrigerant flow channel 32, and the central end of the refrigerant flow channel groove 32X is aligned with the outlet 32b of the refrigerant flow channel 32. Furthermore, through-holes are provided in the metal bonding material 30C at positions opposite the inlet 32a and outlet 32b, penetrating the material in the vertical direction. The laminated body 50 is then heated while being compressed from above and below, thereby bonding the lower circular plate member 30B and the upper circular plate member 30A together to form a cooling plate 30 (FIG. 3D). The refrigerant flow channel grooves 32X become the refrigerant flow channels 32.

[0037] In the wafer mounting table 10 of the present embodiment described above, the first gradual change section 34 is configured so that the cross-sectional area of ​​the refrigerant flow path 32 gradually decreases as the refrigerant progresses from the starting point 34a of the first gradual change section 34 in the refrigerant flow direction. In the first gradual change section 34, the refrigerant temperature decreases upstream and increases downstream, and the refrigerant flow velocity decreases upstream and increases downstream. This reduces the difference in heat removal capacity between the upstream and downstream sections of the first gradual change section 34. Meanwhile, the second gradual change section 36 is configured so that the cross-sectional area of ​​the refrigerant flow path 32 is expanded from the cross-sectional area of ​​the refrigerant flow path 32 at the end point 34b of the first gradual change section 34 in the first expansion section 35 located immediately before the starting point 36a of the second gradual change section 36, and then the cross-sectional area of ​​the refrigerant flow path 32 gradually decreases as the refrigerant progresses in the refrigerant flow direction from the starting point 36a of the second gradual change section 36. The difference in heat removal capacity of the refrigerant also becomes smaller between the upstream and downstream in the second gradual change section 36 for the same reason as in the first gradual change section 34. In particular, in the second gradual change section 36, the cross-sectional area of ​​the refrigerant flow path 32 is temporarily expanded immediately before the starting point 36a of the second gradual change section 36, so that the difference in cross-sectional area between the upstream and downstream in the second gradual change section 36 can be increased while suppressing pressure loss of the refrigerant flowing through the second gradual change section 36. Therefore, the temperature uniformity of the wafer W can be improved.

[0038] Furthermore, the length of the first expansion section 35 is shorter than the length of the first gradual change section 34. Therefore, the first gradual change section 34 can be made longer. Similarly, the length of the second expansion section 37 is shorter than the length of the second gradual change section 36. Therefore, the second gradual change section 36 can be made longer.

[0039] Furthermore, the end point 34b of the first gradual change section 34 is located near a point that is one revolution along the refrigerant flow path 32 from the start point 34a of the first gradual change section 34. Therefore, the amount of heat released by the refrigerant in approximately one revolution of the refrigerant flow path 32 in which the first gradual change section 34 is located can be made approximately uniform. Similarly, the end point 36b of the second gradual change section 36 is located near a point that is one revolution along the refrigerant flow path 32 from the start point 36a of the second gradual change section 36. Therefore, the amount of heat released by the refrigerant in approximately one revolution of the refrigerant flow path 32 in which the second gradual change section 36 is located can be made approximately uniform.

[0040] Furthermore, the end point 34b of the first gradual change section 34 coincides with the start point of the first expansion section 35. Therefore, after the first gradual change section 34 ends, it is possible to immediately transition to the first expansion section 35. Similarly, the end point 36b of the second gradual change section 36 coincides with the start point of the second expansion section 37. Therefore, after the second gradual change section 36 ends, it is possible to immediately transition to the second expansion section 37.

[0041] The first expansion section 35 is a non-arcuate (linear in this case) section provided midway along the circumferential portion of the spiral refrigerant flow path 32. The flow velocity distribution of the refrigerant changes in the non-arcuate section provided midway along the circumferential portion of the refrigerant flow path 32, and so the cross-sectional area of ​​the refrigerant flow path 32 can be expanded over a relatively short distance by utilizing this section. The same applies to the second expansion section 37.

[0042] Furthermore, the distance between the ceiling surface of the coolant flow path 32 and the wafer mounting surface 20a is constant from the inlet 32a to the outlet 32b of the coolant flow path 32, and the cross-sectional area of ​​the coolant flow path 32 is changed by changing the width while keeping the height of the cross-section of the coolant flow path 32 constant. Therefore, the wafer mounting table 10 can be manufactured relatively easily.

[0043] In addition, the refrigerant flow path 32 has a third gradual change section 38 downstream of the second gradual change section 36. The third gradual change section 38 is configured so that the cross-sectional area of ​​the refrigerant flow path 32 is expanded from the cross-sectional area of ​​the refrigerant flow path 32 at the end point 36b of the second gradual change section 36 in a second expansion section 37 provided immediately before the start point 38a of the third gradual change section 38, and then the cross-sectional area of ​​the refrigerant flow path 32 gradually decreases as the refrigerant flow progresses from the start point 38a of the third gradual change section 38 in the refrigerant flow direction. In this way, the provision of the third gradual change section 38 can further improve the temperature uniformity of the wafer W. The end point 38b of the third gradual change section 38 is provided near a point located one full circuit along the refrigerant flow path 32 from the start point 38a of the third gradual change section 38. Therefore, the amount of heat removed by the refrigerant in approximately one circuit of the refrigerant flow path 32 in which the third gradual change section 38 is provided can be generally uniform.

[0044] It goes without saying that the present invention is not limited to the above-described embodiment, and can be embodied in various forms as long as they fall within the technical scope of the present invention.

[0045] For example, in the above-described embodiment, the lengths of the first gradual change section 34, the second gradual change section 36, and the third gradual change section 38 are each set to approximately the length of one circumference of the refrigerant flow path 32, but this is not particularly limited to this, and the configurations of Figures 4 and 5 may also be adopted.

[0046] 4, a first gradual change section 134, a first constant section 144, a first expansion section 135, a second gradual change section 136, a second constant section 146, a second expansion section 137, and a third gradual change section 138 are provided from an inlet 132a to an outlet 132b. An end point 134b of the first gradual change section 134 is provided near a point 1 / 2 to 3 / 4 of the way around the refrigerant flow path 132 from a start point 134a of the first gradual change section 134 (the inlet 132a of the refrigerant flow path 132). The first gradual change section 134 has the same configuration as the first gradual change section 34 except for its length. A first expansion section 135, which has the same length and configuration as the first expansion section 35, is provided downstream of the first gradual change section 134 and is located at the same position as the first expansion section 35. A first unchanging section 144 is provided between the end point 134b of the first gradual-change section 134 and the start point of the first expansion section 135. In the first unchanging section 144, the cross-sectional area of ​​the refrigerant flow path 132 is constant from the start point 144a to the end point 144b (here, the height and width of the cross section of the refrigerant flow path 132 are constant). The end point 136b of the second gradual-change section 136 is provided near a point 1 / 2 to 3 / 4 of the way around the refrigerant flow path 132 from the start point 136a of the second gradual-change section 136. The second gradual-change section 136 has the same configuration as the second gradual-change section 36 except for its length. A second expansion section 137, which has the same length and configuration as the second expansion section 37, is provided downstream of the second gradual-change section 136 and at the same position as the second expansion section 37. A second unchanging section 146 is provided between the end point 136b of the second gradual-change section 136 and the start point of the second expansion section 137. In the second constant section 146, the cross-sectional area of ​​the refrigerant flow path 132 is constant from the starting point 146a to the end point 146b (here, the height and width of the cross-section of the refrigerant flow path 132 are constant). The end point 138b of the third gradually changing section 138 is located near a point 1 / 2 to 3 / 4 of the way around the refrigerant flow path 132 from the starting point 138a of the third gradually changing section 138. The third gradually changing section 138 has the same configuration as the third gradually changing section 38 except for its length. The cross-sectional area of ​​the refrigerant flow path 132 is constant (the height and width of the cross-section are constant) from the end point 138b of the third gradually changing section 138 to the outlet 132b of the refrigerant flow path 132. Even when the configuration of FIG. 4 is adopted, substantially the same effects as those of the above-described embodiment can be obtained. However, in the above-described embodiment, the first and second constant sections 144, 146 of FIG. 4 are not present, which makes it easier to further improve the thermal uniformity of the wafer W.

[0047] 5, a first gradual change section 234, a first expansion section 235, and a second gradual change section 236 are provided from an inlet 232a to an outlet 232b. An end point 234b of the first gradual change section 234 is provided near a point two turns (e.g., 1.8 to 2.2 turns) along the refrigerant flow path 232 from a start point 234a of the first gradual change section 234 (the inlet 232a of the refrigerant flow path 232). The second gradual change section 234 has the same configuration as the first gradual change section 34 except for its length. A first expansion section 235, which has the same length and configuration as the second expansion section 37, is provided downstream of the first gradual change section 234 at the same position as the second expansion section 37. The start point of the first expansion section 235 coincides with the end point 234b of the first gradual change section 234, and the end point of the second expansion section 235 coincides with a start point 236a of the second gradual change section 236. An end point 236b of the second gradual change section 236 is located near a point (e.g., 0.8 to 1.2 times) from a start point 236a of the second gradual change section 236 along the refrigerant flow path 132. The second gradual change section 236 has the same configuration as the third gradual change section 38. The cross-sectional area of ​​the refrigerant flow path 232 from the end point 236b of the second gradual change section 236 to the outlet 232b of the refrigerant flow path 232 is constant (the height and width of the cross section are constant). Even when the configuration of FIG. 5 is adopted, substantially the same effects as those of the above-described embodiment can be obtained. However, in the above-described embodiment, the first gradual change section 34, the first expansion section 35, and the second gradual change section 36 are provided in the portion where the first gradual change section 234 of FIG. 5 is provided, which makes it easier to further improve the temperature uniformity of the wafer W.

[0048] In the above-described embodiment, the first expansion section 35 and the second expansion section 37 are linear sections provided midway along the circumference of the spiral refrigerant flow path 32. However, this is not particularly limited, and the configuration shown in Fig. 6 may also be employed. In Fig. 6, a spiral refrigerant flow path 332 is employed that does not have linear sections, and a first arc-shaped gradual-change section 334, a first arc-shaped expansion section 335, a second arc-shaped gradual-change section 336, a second arc-shaped expansion section 337, and a third arc-shaped gradual-change section 338 are provided successively from the inlet 332a to the outlet 332b. The first to third gradual-change sections 334, 336, and 338 are generally the same as the first to third gradual-change sections 34, 36, and 38. The first and second expansion sections 335, 337 are arc-shaped sections provided in the spiral-shaped refrigerant flow path 332. Therefore, unlike the linear first and second expansion sections 35, 37, the refrigerant flow velocity distribution is substantially constant. Therefore, in the first and second expansion sections 335, 337, the cross-sectional area of ​​the refrigerant flow path 332 is expanded by a relatively long distance (for example, approximately twice the distance of the first and second expansion sections 35, 37). As an example, the first and second expansion sections 35, 37 may be set to within 50 mm (for example, 10 mm to 50 mm), and the first and second expansion sections 335, 337 may be set to a distance within 100 mm that is longer than the first and second expansion sections 35, 37. Even when the configuration of FIG. 6 is adopted, substantially the same effects as those of the above-described embodiment can be obtained. However, in the above-described embodiment, the first and second expansion sections 35, 37 can be made shorter than the first and second expansion sections 335, 337, and therefore the first to third gradual change sections 34, 36, 38 can be set longer, which makes it easier to further improve the temperature uniformity of the wafer W.

[0049] In the above-described embodiment, the coolant flow path 32 is provided with the second expansion section 37 and the third gradual change section 38, but it is not necessary to provide the second expansion section 37 and the third gradual change section 38. Even in this case, the coolant flow path 32 includes the first gradual change section 34, the first expansion section 35, and the second gradual change section 36, and therefore the temperature uniformity of the wafer W is improved compared to when these sections are not provided (when the cross-sectional area of ​​the coolant flow path 32 is constant from the inlet 32a to the outlet 32b).

[0050] In the above-described embodiment, the cross-sectional height of the refrigerant flow path 32 is constant throughout the entire refrigerant flow path 32. However, the cross-sectional height of the refrigerant flow path 32 may be varied in a portion of the refrigerant flow path 32. The location where the cross-sectional height of the refrigerant flow path 32 is varied may be around the inlet 32a of the refrigerant flow path 32, or may be a portion of the refrigerant flow path 32 that bypasses the power supply member connected to the electrostatic electrode 22. The location where the cross-sectional height of the refrigerant flow path 32 is varied may be a portion of the first gradually changing section 34, a portion of the second gradually changing section 36, a portion of the third gradually changing section 38, a portion of the first expanding section 35, or a portion of the second expanding section 36. This also applies to the refrigerant flow path 132 in FIG. 4, the refrigerant flow path 232 in FIG. 5, and the refrigerant flow path 332 in FIG. 6. In FIG. 4, the location where the cross-sectional height of the refrigerant flow path 132 is varied may be a portion of the first unchanged section 144 or a portion of the second unchanged section 146.

[0051] In the above-described embodiment, one or more pairs of an expansion section and a gradual change section may be provided downstream of the third gradual change section 38.

[0052] In the above-described embodiment, the wafer mounting table 10 may have at least one of a heater electrode and an RF electrode (plasma generation electrode) embedded in the ceramic plate 20 instead of or in addition to the electrostatic electrode 22.

[0053] In the above-described embodiment, the inlets 32a of the refrigerant flow paths 32 are provided on the outer periphery of the cooling plate 30, and the outlets 32b of the refrigerant flow paths 32 are provided on the center side of the cooling plate 30, but this is not particularly limited. For example, the inlets 32a of the refrigerant flow paths 32 may be provided on the center side of the cooling plate 30, and the outlets 32b of the refrigerant flow paths 32 may be provided on the outer periphery of the cooling plate 30.

[0054] In the above-described embodiment, the cross-sectional width is gradually changed from 8 mm to 6 mm in each of the first gradually changing section 34, the second gradually changing section 36, and the third gradually changing section 38, but is not particularly limited to this. For example, the range of change in the cross-sectional width may be different in the first gradually changing section 34, the second gradually changing section 36, and the third gradually changing section 38. For example, the cross-sectional width may be gradually changed from 8 mm to 6 mm in the first gradually changing section 34, and from 9 mm to 7 mm (or from 7 mm to 5 mm) in the second and third gradually changing sections 36, 38. [Industrial Applicability]

[0055] The present invention can be used in semiconductor manufacturing equipment. [Explanation of symbols]

[0056] 10 wafer mounting table, 20 ceramic plate, 20a wafer mounting surface, 22 electrostatic electrode, 30 cooling plate, 30A upper disc member, 30B lower disc member, 30C metal bonding material, 32 coolant flow path, 32a inlet, 32b outlet, 32X coolant flow path groove, 34 first gradually changing section, 34a starting point, 34b ending point, 35 first expansion section, 36 second gradually changing section, 36a starting point, 36b ending point, 37 second expansion section, 38 third gradually changing section, 38a starting point, 38b ending point, 40 bonding layer, 50 laminate, 132 coolant flow path, 132a inlet, 132b outlet, 134 first gradually changing section, 134a starting point, 134b ending point, 135 first expansion section, 136 Second gradually changing section, 136a starting point, 136b ending point, 137 Second expansion section, 138 Third gradually changing section, 138a starting point, 138b ending point, 144 First constant section, 144a starting point, 144b ending point, 146 Second constant section, 146a starting point, 146b ending point, 232 Refrigerant flow path, 232a inlet, 232b outlet, 234 First gradually changing section, 234a starting point, 234b ending point, 235 First expansion section, 236 Second gradually changing section, 236a starting point, 236b ending point, 332 Refrigerant flow path, 332a inlet, 332b outlet, 334 First gradually changing section, 335 First expansion section, 336 Second gradually changing section, 337 Second expansion section, 338 The third gradually changing section.

Claims

1. a ceramic plate having a wafer mounting surface on its upper surface and incorporating an electrode; a cooling plate provided on the lower surface of the ceramic plate; a refrigerant flow path provided inside the cooling plate, the refrigerant flow path having an inlet provided on one of an outer periphery side and a center side of the cooling plate and an outlet provided on the other of the outer periphery side and the center side of the cooling plate, the refrigerant flow path being spirally formed from the inlet to the outlet in a plan view; A wafer mounting table comprising: the refrigerant flow path has a first gradual change section that starts from the inlet and a second gradual change section that is provided downstream of the first gradual change section, The first gradual change section is provided such that a cross-sectional area of ​​the refrigerant flow path gradually decreases from a starting point of the first gradual change section to a flow direction of the refrigerant, The second gradual change section is configured such that, in a first expansion section provided immediately before a starting point of the second gradual change section, a cross-sectional area of ​​the refrigerant flow path is once expanded from a cross-sectional area of ​​the refrigerant flow path at an end point of the first gradual change section, and then the cross-sectional area of ​​the refrigerant flow path gradually decreases as the refrigerant progresses from the starting point of the second gradual change section in a flow direction of the refrigerant. Wafer stage.

2. The length of the first expansion section is shorter than the length of the first gradual change section. The wafer stage according to claim 1 .

3. an end point of the first gradual change section is provided near a point that is one circuit along the refrigerant flow path from a start point of the first gradual change section; The wafer stage according to claim 1 or 2.

4. An end point of the first gradually changing section coincides with a start point of the first expansion section. The wafer stage according to claim 1 or 2.

5. The first expansion section is a non-arcuate section provided midway along the circumferential portion of the spiral refrigerant flow path. The wafer stage according to claim 1 or 2.

6. a distance between a ceiling surface of the coolant flow path and the wafer placement surface is constant from the inlet to the outlet of the coolant flow path, and a cross-sectional area of ​​the coolant flow path is changed by changing a width while keeping a height of the cross-section of the coolant flow path constant. The wafer stage according to claim 1 or 2.

7. the refrigerant flow path has a third gradual change section downstream of the second gradual change section, The third gradual change section is configured such that, in a second expansion section provided immediately before the starting point of the third gradual change section, a cross-sectional area of ​​the refrigerant flow path is once expanded from a cross-sectional area of ​​the refrigerant flow path at an end point of the second gradual change section, and then the cross-sectional area of ​​the refrigerant flow path gradually decreases as the refrigerant progresses from the starting point of the third gradual change section in a flow direction of the refrigerant. The wafer stage according to claim 1 or 2.

Images