Wafer holder

Abstract

To provide a wafer holder capable of quickly and uniformly cooling a heater. [Solution] The wafer holder includes a heater having an upper surface on which a wafer is placed and a lower surface opposite the upper surface, a cooling plate arranged below the heater and capable of being raised and lowered to move toward and away from the lower surface, and a restricting member that partially contacts at least one of the lower surface of the heater and the upper surface of the cooling plate to restrict contact between the lower surface of the heater and the upper surface of the cooling plate. The thermal conductivity of the restricting member is lower than that of the cooling plate.

Description

[Technical Field]

[0001] TECHNICAL FIELD The present disclosure relates to a wafer holder. [Background technology]

[0002] Patent Document 1 discloses a heater module that includes a heater unit on which a wafer is placed, a block unit that is provided below the heater unit so that it can be raised and lowered, and a chamber bottom unit that cools the block unit by contacting the lowered block unit. In this heater module, the lowered block unit is cooled by contacting the water-cooled chamber bottom, and the cooled block unit rises and contacts the underside of the heater unit, thereby cooling the heater unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-184550 Summary of the Invention [Problem to be solved by the invention]

[0004] It is desirable to cool the heater quickly and uniformly.

[0005] An object of the present disclosure is to provide a wafer holder that can quickly and uniformly cool a heater. [Means for solving the problem]

[0006] The wafer holder of the present disclosure includes a heater having an upper surface on which a wafer is placed and a lower surface opposite to the upper surface, a cooling plate having an upper surface that is vertically movable below the heater and moves toward and away from the lower surface, and a restricting member that partially contacts at least one of the lower surface of the heater and the upper surface of the cooling plate to restrict contact between the lower surface of the heater and the upper surface of the cooling plate. The thermal conductivity of the restricting member is lower than that of the cooling plate. [Effects of the Invention]

[0007] The wafer holder of the present disclosure can cool the heater quickly and uniformly. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic vertical cross-sectional view showing a state during cooling in a first example of a wafer holder according to the first embodiment. [Figure 2] FIG. 2 is a schematic vertical cross-sectional view showing a state during heating in a first example of the wafer holder according to the first embodiment. [Figure 3] FIG. 3 is a schematic top view showing a cooling plate provided on the wafer holder of the first embodiment. [Figure 4] FIG. 4 is an enlarged view of area A in FIG. [Figure 5] FIG. 5 is a schematic vertical cross-sectional view showing a state in which the cooling plate of the first example of the wafer holder according to the first embodiment is deformed. [Figure 6] FIG. 6 is a schematic vertical cross-sectional view showing a state during cooling in a second example of the wafer holder according to the first embodiment. [Figure 7] FIG. 7 is a schematic vertical cross-sectional view showing a cooling plate and a regulating member provided on the wafer holder of the second embodiment. [Figure 8] FIG. 8 is a schematic vertical cross-sectional view showing a cooling plate and a regulating member provided on a wafer holder according to the third embodiment. [Figure 9] FIG. 9 is a schematic vertical cross-sectional view showing the state of the wafer holder of the fourth embodiment during cooling. [Figure 10] FIG. 10 is a schematic top view showing a cooling plate provided on the wafer holder of the fourth embodiment. [Figure 11] FIG. 11 is a schematic vertical cross-sectional view showing a state in which the cooling plate of the wafer holder of the fourth embodiment is deformed. [Figure 12] FIG. 12 is a schematic vertical cross-sectional view showing the state of the wafer holder of the fifth embodiment during cooling. [Figure 13] FIG. 13 is a schematic vertical cross-sectional view showing a state in which the cooling plate of the wafer holder of the fifth embodiment is deformed. [Figure 14] FIG. 14 is a schematic vertical cross-sectional view showing the state of the wafer holder of the sixth embodiment during cooling. DETAILED DESCRIPTION OF THE INVENTION

[0009] <<Description of Embodiments of the Present Disclosure>> First, embodiments of the present disclosure will be listed and described.

[0010] (1) A wafer holder according to one aspect of the present disclosure includes a heater having an upper surface on which a wafer is placed and a lower surface opposite the upper surface, a cooling plate having an upper surface that is vertically movable below the heater and moves toward and away from the lower surface, and a restricting member that partially contacts at least one of the lower surface of the heater and the upper surface of the cooling plate to restrict contact between the lower surface of the heater and the upper surface of the cooling plate. The restricting member has a thermal conductivity lower than that of the cooling plate.

[0011] Without a regulating member, the underside of the heater and the upper surface of the cooling plate come into direct contact. In this case, if the underside of the heater and the upper surface of the cooling plate are in uniform contact, the heater will be cooled quickly and uniformly. However, when the regulating member is not present and the cooling plate is raised and lowered, the underside and upper surfaces of the heater may not be in uniform contact due to a slight tilt between them. That is, a portion of the upper surface of the cooling plate may come into contact with the underside of the heater, while the remaining portion of the upper surface of the cooling plate may not come into contact with the underside of the heater. In this case, the difference in cooling rate between the contacting and non-contacting areas becomes large, resulting in a large temperature distribution in the heater. Therefore, although the heater is cooled quickly, it is not cooled uniformly.

[0012] In contrast, the wafer holder of (1) uses a restricting member to prevent contact between the bottom surface of the heater and the top surface of the cooling plate. Because the thermal conductivity of the restricting member is lower than that of the cooling plate, even if there are contact and non-contact areas between the bottom surface of the heater or the top surface of the cooling plate and the restricting member, the temperature distribution of the heater can be reduced while minimizing the decrease in the cooling rate of the heater. Therefore, the wafer holder of (1) can cool the heater quickly and uniformly.

[0013] (2) In the wafer holder of (1) above, the regulating member may regulate the minimum distance between the lower surface of the heater and the upper surface of the cooling plate to 0.05 mm or more and 1.0 mm or less.

[0014] The heat from the heater causes the upper surface of the cooling plate to become hotter than the lower surface, resulting in a temperature difference between the upper and lower surfaces. This temperature difference causes the center of the upper surface of the cooling plate to deform so that it becomes convex upward. If the minimum distance is 0.05 mm or more, even if the cooling plate deforms as described above, the restricting member can easily prevent contact between the lower surface of the heater and the upper surface of the cooling plate. If the minimum distance is 1.0 mm or less, the cooling rate of the heater can be set to the desired rate.

[0015] (3) In the wafer holder of (1) or (2), the ratio of the contact area between the lower surface of the heater and the regulating member may be 5.0% or less of the area of ​​the lower surface of the heater.

[0016] If the above ratio is 5.0% or less, it is easy to maintain the distance between the lower surface of the heater and the upper surface of the cooling plate so that the distance satisfies the desired cooling rate of the heater.

[0017] (4) In any one of the wafer holders (1) to (3) above, the regulating member may have an upward protrusion that protrudes from the upper surface of the cooling plate toward the heater.

[0018] The wafer holder of (4) above makes it easy to prevent contact between the lower surface of the heater and the upper surface of the cooling plate.

[0019] (5) In the wafer holder of (4) above, the upward protrusion may be provided at the center of the upper surface of the cooling plate.

[0020] The wafer holder of (5) above can easily prevent contact between the lower surface of the heater and the upper surface of the cooling plate even if the cooling plate is deformed as described above.

[0021] (6) In the wafer holder of (4) or (5), the upper surface of the cooling plate may have an inner peripheral recess disposed inside the outer peripheral edge of the cooling plate. The restricting member has a pin member disposed in the inner peripheral recess. The pin member has the upward protrusion.

[0022] The wafer holder of (6) above makes it easy to prevent contact between the lower surface of the heater and the upper surface of the cooling plate.

[0023] (7) In the wafer holder of (4) or (5), the regulating member may have a sheet member provided on the upper surface of the cooling plate, the sheet member having the upward protrusion.

[0024] The wafer holder of (7) above makes it easy to prevent contact between the lower surface of the heater and the upper surface of the cooling plate.

[0025] (8) In the wafer holder of (4) or (5) above, the regulating member may have the upward protrusion provided on the upper surface of the cooling plate.

[0026] The wafer holder of (8) above makes it easy to prevent contact between the lower surface of the heater and the upper surface of the cooling plate.

[0027] (9) In the wafer holder of (4) or (5) above, the upward protrusions may include a plurality of first upward protrusions evenly arranged on the circumference of a first circle centered on the center of the enveloping circle of the cooling plate, and a plurality of second upward protrusions evenly arranged on the circumference of a second circle concentric with the first circle and having a radius larger than that of the first circle.

[0028] The wafer holder of (9) above makes it easy to uniformly arrange the contact points between the lower surface of the heater and the regulating member, and therefore makes it easy to reduce the temperature distribution of the heater.

[0029] (10) In the wafer holder of (9) above, the height of each of the second upward protrusions may be greater than the height of each of the first upward protrusions.

[0030] In the wafer holder of (10) above, before the cooling plate is deformed, the multiple first upward protrusions do not contact the lower surface of the heater, and the multiple second upward protrusions contact the lower surface of the heater. In the wafer holder of (10) above, after the cooling plate is deformed, the multiple first upward protrusions and the multiple second upward protrusions are likely to contact the lower surface of the heater. Therefore, the wafer holder of (10) above is likely to prevent contact between the lower surface of the heater and the upper surface of the cooling plate, both before and after the cooling plate is deformed.

[0031] (11) In the wafer holder of any one of (4) to (10) above, the regulating member may have a support piece that supports the outer periphery of the lower surface of the heater.

[0032] The wafer holder of (11) above makes it easy to uniformly arrange the contact points between the lower surface of the heater and the regulating member, and therefore makes it easy to reduce the temperature distribution of the heater.

[0033] (12) In the wafer holder of (11), the upper surface of the cooling plate may have a peripheral recess provided on the outer periphery of the cooling plate, and the lower surface of the support piece may be provided so as to contact the bottom surface of the peripheral recess.

[0034] The wafer holder of (12) above makes it easy to uniformly arrange the contact points between the lower surface of the heater and the regulating member, and therefore makes it easy to reduce the temperature distribution of the heater.

[0035] (13) In the wafer support table of (12) above, when the lower surface of the support piece and the bottom surface of the outer peripheral recess are in contact with each other, the length of the gap between the lower surface of the heater and the upper surface of the cooling plate may be longer than the length of the upward protrusion from the upper surface of the cooling plate.

[0036] In the wafer holder of (13) above, before the cooling plate is deformed, the upward protrusions do not come into contact with the underside of the heater, and the support pieces prevent contact between the underside of the heater and the upper surface of the cooling plate. In the wafer holder of (13) above, after the cooling plate is deformed, the upward protrusions as well as the support pieces easily prevent contact between the underside of the heater and the upper surface of the cooling plate. Therefore, the wafer holder of (13) above easily prevents contact between the underside of the heater and the upper surface of the cooling plate, both before and after the cooling plate is deformed.

[0037] (14) In any one of the wafer holders (1) to (13) above, the coefficient of dynamic friction of the regulating member with respect to the heater may be 0.5 or less.

[0038] The wafer holder of (15) above can be used for a long period of time because the regulating members are less likely to wear due to contact between the heater or cooling plate and the regulating members.

[0039] (15) In the wafer holder of (1) or (2) above, the regulating member may have a downward protrusion that protrudes from the lower surface of the heater toward the cooling plate.

[0040] The wafer holder (15) above makes it easy to prevent contact between the lower surface of the heater and the upper surface of the cooling plate.

[0041] Details of the embodiments of the present disclosure Hereinafter, an embodiment of the wafer holder of the present disclosure will be described with reference to the drawings. The shapes, sizes, and positional relationships shown in each drawing are depicted for the purpose of clarifying the description and do not necessarily represent the actual shapes, sizes, and positional relationships. The same reference numerals in the drawings indicate the same items.

[0042] [Embodiment 1] <Wafer holder> 1 to 6, a wafer holder 1 of the first embodiment will be described. As shown in FIG. 1, the wafer holder 1 of the first embodiment includes a heater 2 and a cooling plate 3. The heater 2 heats the wafer 100. The cooling plate 3 cools the heater 2, thereby cooling the wafer 100. The cooling plate 3 is disposed below the heater 2 so as to be able to move up and down. One of the features of the wafer holder 1 of the first embodiment is that it includes a restricting member 4 that restricts contact between the lower surface 22 of the heater 2 and the upper surface 31 of the cooling plate 3.

[0043] <Heater> The heater 2 heats the wafer 100 to a predetermined temperature. The wafer 100 is, for example, a silicon or compound semiconductor wafer. The heater 2 has an upper surface 21 on which the wafer 100 is placed and a lower surface 22 opposite the upper surface 21. The heater 2 in this example has a circular shape when viewed from above. The diameter of the heater 2 is slightly larger than the wafer 100. The diameter of the heater 2 is designed to match the size of the wafer 100.

[0044] The material of the heater 2 is, for example, ceramics or a ceramic composite. The ceramic is, for example, aluminum nitride, silicon nitride, silicon carbide, or aluminum oxide. The ceramic composite is a composite of ceramic and metal. The ceramic composite is, for example, a silicon-silicon carbide composite, an aluminum-silicon carbide composite, or an aluminum-silicon-silicon carbide composite.

[0045] The heater 2 has a heating element (not shown). The heating element is arranged inside the heater 2 in a plane parallel to the upper surface 21. The heating element is a heat source that heats the wafer 100 placed on the upper surface 21. The material of the heating element is not particularly limited as long as it can heat the wafer 100 to the desired temperature. The heating element is a known metal suitable for resistance heating. The metal is, for example, one selected from the group consisting of stainless steel, nickel, nickel alloy, silver, silver alloy, tungsten, tungsten alloy, molybdenum, molybdenum alloy, chromium, and chromium alloy. The nickel alloy is, for example, nichrome.

[0046] Unlike the cooling plate 3, the heater 2 is supported by a support member 5 so as not to rise or fall. In this example, the support member 5 has multiple support pieces 51 and multiple legs 52. Each support piece 51 supports the heater 2 from its outer peripheral surface to its underside 22. The multiple support pieces 51 may or may not be evenly spaced around the outer peripheral circle of the heater 2. Evenly spaced support pieces 51 around the outer peripheral circle of the heater 2 make it easier to support the heater 2 than when they are not evenly spaced. Each support piece 51 in this example has an L-shaped cross section. Each support piece 51 has an outer peripheral support portion 511 that supports the outer peripheral surface of the heater 2 and a lower support portion 512 that supports the underside 22 of the heater 2. In this example, there are three support pieces 51. The three support pieces 51 in this example are evenly spaced around the outer peripheral circle of the heater 2. The support pieces 51 are arranged in an equilateral triangle shape at 120° intervals around the outer peripheral circle. In this example, the diameter of the inscribed circle inscribed in all of the lower support portions 512 is larger than the outer diameter of the cooling plate 3. This inscribed circle is a circle that is in contact with the point of each outer peripheral support portion 511 closest to the center of the lower surface 22. The outer diameter of the cooling plate 3 is the diameter of a circle that passes through the point farthest from the center a (FIG. 3) of the cooling plate 3. Each leg 52 connects each support piece 51 to the pedestal 9 on which the wafer holder 1 is placed. There are three legs 52, the same number as the support pieces 51. The material of the support member 5 in this example is ceramic or a ceramic composite, as described in the section on the material of the heater 2. The material of the support member 5 may be the same as or different from the material of the heater 2.

[0047] <Cooling plate> The cooling plate 3 cools the heater 2, thereby cooling the wafer 100. The cooling plate 3 is disposed below the heater 2. The cooling plate 3 can be raised and lowered by an elevation mechanism 8. The elevation mechanism 8 is not particularly limited, and a known pressure mechanism or screw mechanism can be used. The upper surface 31 of the cooling plate 3 rises as shown in FIG. 1 to approach the lower surface 22 during cooling, and descends as shown in FIG. 2 to move away from the lower surface 22 during heating.

[0048] The cooling plate 3 of this example has a circular shape when viewed from above, as shown in Fig. 3. The outer diameter of the cooling plate 3 of this example is smaller than the diameter of the inscribed circle of the lower support portion 512 described above. In other words, even when the cooling plate 3 of this example is raised, the upper surface 31 of the cooling plate 3 and the support piece 51 do not come into contact with each other. Therefore, when the cooling plate 3 is raised, the restricting member 4 described below comes into contact with the lower surface 22 of the heater 2.

[0049] The thickness of the cooling plate 3 is, for example, 15 mm or more and 30 mm or less. The thickness of the cooling plate 3 is the dimension of the cooling plate 3 along a direction perpendicular to the upper surface 31. If the thickness of the cooling plate 3 is 15 mm or more, it is easy to ensure the rigidity of the cooling plate 3. If the thickness of the cooling plate 3 is 30 mm or less, it is possible to make the wafer holder 1 compact. Furthermore, the thinner the cooling plate 3, the smaller the heat capacity of the cooling plate 3 tends to be. Therefore, the cooling plate 3 tends to cool more quickly. The thickness of the cooling plate 3 may be 15 mm or more and 20 mm or less, or 16 mm or more and 18 mm or less.

[0050] The cooling plate 3 is made of a material that has high thermal conductivity and high rigidity. The material of the heater 2 is, for example, a metal, a ceramic, or a ceramic composite. The metal is, for example, copper, a copper alloy, aluminum, or an aluminum alloy. The ceramic is, for example, aluminum nitride, silicon nitride, silicon carbide, or aluminum oxide. The ceramic composite is a composite of ceramic and a metal. The ceramic composite is, for example, a silicon-silicon carbide composite, an aluminum-silicon carbide composite, or an aluminum-silicon-silicon carbide composite.

[0051] The thermal conductivity of the cooling plate 3 is, for example, 100 W / m·K or more. The thermal conductivity of the cooling plate 3 may be 200 W / m·K or more, 300 W / m·K or more, or 400 W / m·K or more. These thermal conductivities are values ​​at 20°C. The thermal conductivity of copper is approximately 400 W / m·K, and the thermal conductivity of aluminum is approximately 230 W / m·K. The thermal conductivity of silicon carbide is approximately 200 W / m·K, and the thermal conductivity of aluminum nitride is approximately 150 W / m·K. The thermal conductivity of a silicon-silicon carbide composite (Si-SiC) is approximately 170 W / m·K.

[0052] The upper surface 31 of the cooling plate 3 in this example has a plurality of inner peripheral recesses 33 arranged more inward than the outer peripheral edge of the cooling plate 3. The outer peripheral edge is a region that is 0.9 to 1.0 times the radius of the upper surface 31. Each inner peripheral recess 33 opens to the upper surface 31. A pin member 41, which will be described later, is disposed in each inner peripheral recess 33. The plurality of inner peripheral recesses 33 has a recess provided in the center of the upper surface 31 of the cooling plate 3. The center is a region that is 0.5 times or less the radius of the upper surface 31. The cooling plate 3 in this example has a plurality of first inner peripheral recesses 331 and a plurality of second inner peripheral recesses 332.

[0053] In this example, as shown in FIG. 3 , the first inner peripheral recesses 331 are evenly arranged around the first circle C1, and the second inner peripheral recesses 332 are evenly arranged around the second circle C2. The first circle C1 and the second circle C2 are circles centered on the center a of the envelope circle of the upper surface 31. The first circle C1 and the second circle C2 have different radii. The radius of the second circle C2 is larger than the radius of the first circle C1. The radius of the first circle C1 is 0.1 to 0.5 times the radius of the upper surface 31. That is, the first inner peripheral recesses 331 are provided in the center of the upper surface 31 of the cooling plate 3. The heat from the heater 2 makes the upper surface 31 of the cooling plate 3 hotter than the lower surface 32, resulting in a temperature difference between the upper surface 31 and the lower surface 32. This temperature difference causes the center of the upper surface 31 of the cooling plate 3 to deform so as to become convex upward, as shown in FIG. 5 . If the radius of the first circle C1 is 0.1 to 0.5 times the radius of the upper surface 31, even if the cooling plate 3 is deformed as described above, the upward protrusions 414 of the pin members 41 disposed in each first inner peripheral recess 331 can easily prevent contact between the lower surface 22 of the heater 2 and the upper surface 31 of the cooling plate 3. The radius of the second circle C2 is 0.3 to 1.0 times the radius of the upper surface 31. If the radius of the second circle C2 is 0.3 to 1.0 times the radius of the upper surface 31, the contact points between the lower surface 22 of the heater 2 and the upward protrusions 414 of the pin members 41 can be uniformly arranged, making it easy to reduce the temperature distribution of the heater 2. Unlike this example, the multiple first inner peripheral recesses 331 do not have to be uniformly arranged around the first circle C1, and the multiple second inner peripheral recesses 332 do not have to be uniformly arranged around the second circle C2.

[0054] The number of first inner circumferential recesses 331 and the number of second inner circumferential recesses 332 are not particularly limited and can be selected appropriately. The number of first inner circumferential recesses 331 and the number of second inner circumferential recesses 332 may be the same or different. In this example, the number of first inner circumferential recesses 331 is three, and the number of second inner circumferential recesses 332 is three. The inner circumferential recesses 33 are arranged in an equilateral triangular shape at 120° intervals on each circumference. In this example, the first inner circumferential recesses 331 and the second inner circumferential recesses 332 are arranged on the same straight line in the radial direction. Unlike this example, the first inner circumferential recesses 331 and the second inner circumferential recesses 332 may be arranged on different straight lines in the radial direction. Unlike this example, the cooling plate 3 may have a plurality of first inner peripheral recesses 331 but not a plurality of second inner peripheral recesses 332, or may have a plurality of third inner peripheral recesses (not shown) in addition to a plurality of first inner peripheral recesses 331 and a plurality of second inner peripheral recesses 332.

[0055] As shown in FIG. 1, the cooling plate 3 has a refrigerant flow path 35 through which a refrigerant flows. The refrigerant flow path 35 may be arranged in any manner as long as it can cool the entire cooling plate 3. In this example, the refrigerant flow path 35 is formed by piping arranged on the lower surface 32 of the cooling plate 3. Unlike this example, the refrigerant flow path 35 may be formed by piping arranged inside the cooling plate 3, or may be formed by grooves provided inside the cooling plate 3. The refrigerant may be supplied to the refrigerant flow path 35 in any manner. Although not shown, the refrigerant is circulated by a pump through a tank that stores the refrigerant, a cooler that cools the refrigerant, the refrigerant flow path 35, and the tank, in that order.

[0056] Although not shown, the cooling plate 3 may be provided with through holes or grooves required for accommodating a temperature sensor, a lead wire for the heater 2, a member for lifting and lowering the wafer, and the like.

[0057] <Regulating member> The restricting member 4 restricts contact between the lower surface 22 of the heater 2 and the upper surface 31 of the cooling plate 3 by partially contacting at least one of the lower surface 22 of the heater 2 and the upper surface 31 of the cooling plate 3. The thermal conductivity of the restricting member 4 is lower than that of the cooling plate 3.

[0058] Unlike this example, if the regulating member 4 is not present, the lower surface 22 of the heater 2 and the upper surface 31 of the cooling plate 3 come into direct contact. In this case, if the lower surface 22 of the heater 2 and the upper surface 31 of the cooling plate 3 come into uniform contact, the heater 2 will be cooled quickly and uniformly. However, when the regulating member 4 is not present and the cooling plate 3 is raised or lowered, the lower surface 22 of the heater 2 and the upper surface 31 of the cooling plate 3 may not come into uniform contact. That is, a portion of the upper surface 31 of the cooling plate 3 may come into contact with the lower surface 22 of the heater 2, while the remaining portion of the upper surface 31 of the cooling plate 3 may not come into contact with the lower surface 22 of the heater 2. In this case, the difference in cooling rate between the contacting and non-contacting portions becomes large, resulting in a large temperature distribution in the heater 2. Therefore, the heater 2 is cooled quickly but not uniformly. In contrast, in this example, the regulating member 4 prevents contact between the lower surface 22 of the heater 2 and the upper surface 31 of the cooling plate 3. Since the thermal conductivity of the restricting member 4 is lower than that of the cooling plate 3, even if there are contact areas and non-contact areas between the lower surface 22 of the heater 2 or the upper surface 31 of the cooling plate 3 and the restricting member 4, it is possible to reduce the temperature distribution of the heater 2 while minimizing the decrease in the cooling rate of the heater 2. Therefore, in this example, the heater 2 is cooled quickly and uniformly.

[0059] In this example, the restricting members 4 are evenly arranged on the circumference of a circle centered on the center of the envelope circle of the heater 2, between the lower surface 22 of the heater 2 and the upper surface 31 of the cooling plate 3. This makes it easy to evenly arrange the contact points between the lower surface 22 of the heater 2 and the restricting members 4, making it easy to reduce the temperature distribution of the heater 2. Unlike this example, the restricting members 4 do not have to be evenly arranged on the circumference of the circle.

[0060] As shown in FIG. 4, the restricting member 4 is configured to set the minimum distance between the lower surface 22 of the heater 2 and the upper surface 31 of the cooling plate 3 to, for example, 0.05 mm or more and 1.0 mm or less. If the minimum distance is 0.05 mm or more, the restricting member 4 can easily prevent contact between the lower surface 22 of the heater 2 and the upper surface 31 of the cooling plate 3 even if the cooling plate 3 is deformed as shown in FIG. 5. If the minimum distance is 1.0 mm or less, the cooling rate of the heater 2 can be set to a desired rate. The minimum distance may be 0.05 mm or more and 0.3 mm or less, or 0.1 mm or more and 0.3 mm or less.

[0061] When the regulating member 4 and the lower surface 22 of the heater 2 are in contact with each other, the contact area between the regulating member 4 and the lower surface 22 of the heater 2 is, for example, 5.0% or less of the area of ​​the lower surface 22 of the heater 2. If the regulating member 4 has multiple upward protrusions 414 as described below, the contact area is the total contact area between all of the upward protrusions 414 and the lower surface 22. The area of ​​the lower surface 22 is the entire area of ​​the lower surface 22, including the areas of the lower surface 22 that are in contact with all of the lower support portions 512. If the ratio is 5.0% or less, it is easy to maintain the distance between the lower surface 22 of the heater 2 and the upper surface 31 of the cooling plate 3 so that the desired cooling rate of the heater 2 is achieved. The ratio is greater than 0%. The ratio may be 3.0% or less, or 0.1% or less.

[0062] The restricting members 4 of this example are pin members 41 arranged in each of the inner peripheral recesses 33 of the cooling plate 3. The restricting members 4 of this example have first pin members 411 arranged in each of the first inner peripheral recesses 331 and second pin members 412 arranged in each of the second inner peripheral recesses 332. The first pin members 411 of this example are evenly arranged around the circumference of the first circle C1. The second pin members 412 of this example are evenly arranged around the circumference of the second circle C2. Unlike this example, the first pin members 411 may not be evenly arranged around the circumference of the first circle C1, and the second pin members 412 may not be evenly arranged around the circumference of the second circle C2.

[0063] Each pin member 41 in this example has a base 413 and an upward protrusion 414. The bases 413 and the upward protrusions 414 are integral parts made of the same material. That is, the bases 413 and the upward protrusions 414 are continuous, integral parts. Each base 413 is fixed inside the corresponding inner circumferential recess 33. The means for fixing each base 413 to each inner circumferential recess 33 is not particularly limited. For example, each base 413 may be fixed to each inner circumferential recess 33 by press-fitting or by adhesive. Each upward protrusion 414 protrudes upward from the corresponding base 413.

[0064] 1, the length of projection of each upward protrusion 414 from the upper surface 31 is uniform. In this case, before the cooling plate 3 is deformed as shown in Fig. 1, both the upward protrusion 414 of the first pin member 411 and the upward protrusion 414 of the second pin member 412 contact the lower surface 22 of the heater 2. After the cooling plate 3 is deformed as shown in Fig. 5, the upward protrusion 414 of the first pin member 411 contacts the lower surface 22 of the heater 2, but the upward protrusion 414 of the second pin member 412 does not contact the lower surface 22 of the heater 2.

[0065] 6, the protruding length of the upward protruding portions 414 of the second pin members 412 may be longer than the protruding length of the upward protruding portions 414 of the first pin members 411. When the protruding length of the protruding portions of the second pin members 412 is longer than the protruding length of the protruding portions of the first pin members 411, before the cooling plate 3 is deformed as shown in FIG. 6, the upward protruding portions 414 of the first pin members 411 do not contact the lower surface 22 of the heater 2, but the upward protruding portions 414 of the second pin members 412 contact the lower surface 22 of the heater 2. Although not shown in the drawings, after the cooling plate 3 is deformed as shown in FIG. 6, both the upward protruding portions 414 of the first pin members 411 and the upward protruding portions 414 of the second pin members 412 contact the lower surface 22 of the heater 2.

[0066] The upper and lower limit values ​​of the protrusion length and the reasons for specifying the upper and lower limit values ​​are the same as the upper and lower limit values ​​of the minimum distance and the reasons for specifying the upper and lower limit values. Note that, unlike this example, when the protrusion length of the upward protrusion 414 of the second pin member 412 is longer than the protrusion length of the upward protrusion 414 of the first pin member 411, the protrusion length of the upward protrusion 414 in the second inner circumferential recess 332 may be 0.05 mm or more and 1.0 mm or less.

[0067] The thermal conductivity of the pin members 41 is lower than that of the cooling plate 3. When the thermal conductivity of the pin members 41 is lower than that of the cooling plate 3, it is easier to reduce the temperature distribution of the heater 2. The lower the thermal conductivity of the pin members 41, the easier it is to reduce the temperature distribution of the heater 2. The thermal conductivity of the pin members 41 is, for example, 1 / 20 or less than that of the cooling plate 3. When the thermal conductivity of the pin members 41 is 1 / 20 or less than that of the cooling plate 3, it is easier to reduce the temperature distribution of the heater 2. The thermal conductivity of the pin members 41 is, for example, 15.0 W / m·K or less. When the thermal conductivity of the pin members 41 is 15.0 W / m·K or less, it is easier to reduce the temperature distribution of the heater 2. The thermal conductivity of the pin members 41 may be 10.0 W / m·K or less, or 5.0 W / m·K or less. The thermal conductivity of the pin member 41 is 0.1 W / m·K or more. That is, the thermal conductivity of the pin member 41 may be 0.1 W / m·K or more and 15.0 W / m·K or less, 0.1 W / m·K or more and 10.0 W / m·K or less, or 0.3 W / m·K or more and 5.0 W / m·K or less.

[0068] The lower the dynamic friction coefficient of the upward protrusion 414 with respect to the underside 22 of the heater 2, the less likely the upward protrusion 414 will wear due to contact between the upward protrusion 414 and the underside 22 of the heater 2, and the longer the upward protrusion 414 can be used. The dynamic friction coefficient is, for example, 0.5 or less. A dynamic friction coefficient of 0.5 or less makes it easier to reduce wear of the upward protrusion 414. The dynamic friction coefficient may be 0.3 or less, or 0.2 or less. The lower the hardness of the upward protrusion 414, the less likely the upward protrusion 414 will be damaged due to contact between the upward protrusion 414 and the underside 22 of the heater 2.

[0069] The pin member 41 may be made of, for example, polyimide (PI) resin, polyether ether ketone (PEEK) resin, tetrafluoroethylene (PTFE) resin, or tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA) resin. The thermal conductivity of PI resin is typically 0.3 W / m·K. The thermal conductivity of PEEK resin is typically 0.2 W / m·K to 0.9 W / m·K. The thermal conductivity of PTFE resin is typically 0.23 W / m·K, and the thermal conductivity of PFA resin is typically 0.19 W / m·K. These thermal conductivities are measured at 20°C.

[0070] [Embodiment 2] <Wafer holder> A wafer holder of embodiment 2 will be described with reference to FIG. 7. The wafer holder of embodiment 2 differs from wafer holder 1 of embodiment 1 in that restraining members 4 are sheet members 42 rather than pin members 41. The following description will focus on the differences from embodiment 1. Description of configurations and effects similar to those of embodiment 1 may be omitted. These points also apply to embodiments 3 and 4, which will be described later. FIG. 7 shows only the cooling plate 3 and restraining members 4 of the wafer holder. This also applies to FIG. 8, which will be referred to in embodiment 3.

[0071] <Cooling plate> Unlike the first embodiment, the upper surface 31 of the cooling plate 3 of this example does not have the inner peripheral recess 33. The upper surface 31 of the cooling plate 3 is flat.

[0072] <Regulating member> The sheet member 42 is disposed on the flat upper surface 31 of the cooling plate 3. The sheet member 42 of this example has a flat base 421 and a plurality of upward protrusions 422 that protrude upward from the upper surface of the base 421. The base 421 covers the entire upper surface 31 of the cooling plate 3. The plurality of upward protrusions 422 of this example include a plurality of first upward protrusions 423 that are evenly arranged around the circumference of the first circle C1 on the base 421, and a plurality of second upward protrusions 424 that are evenly arranged around the circumference of the second circle C2 on the base 421.

[0073] In this example, the height of each upward protrusion 422 is uniform. The height of the upward protrusion 422 is the length from the upper surface of the base 421 to the upper end of the upward protrusion 422. Unlike this example, the height of the second upward protrusion 424 may be higher than the height of the first upward protrusion 423. The upper and lower limit values ​​of the height and the reasons for specifying the upper and lower limit values ​​are the same as the upper and lower limit values ​​of the minimum distance and the reasons for specifying the upper and lower limit values. Note that, unlike this example, if the height of the second upward protrusion 424 is higher than the height of the first upward protrusion 423, the height of the second upward protrusion 424 may be 0.05 mm or more and 1.0 mm or less.

[0074] The thermal conductivity and dynamic friction coefficient of the sheet member 42 are similar to those of the pin member 41. The material of the sheet member 42 is the resin described in the section regarding the material of the pin member 41. The material of the sheet member 42 may be the same as or different from the material of the pin member 41.

[0075] [Embodiment 3] <Wafer holder> The wafer holder of embodiment 3 will be described with reference to Fig. 8. The wafer holder of embodiment 3 differs from wafer holder 1 of embodiment 1 in that upward protrusion 43 is provided on upper surface 31 of cooling plate 3.

[0076] <Cooling plate> Unlike the first embodiment, the upper surface 31 of the cooling plate 3 of this example does not have the inner peripheral recess 33. The upper surface 31 of the cooling plate 3 is flat.

[0077] <Regulating member> There are a plurality of upward protrusions 43. In this example, the plurality of upward protrusions 43 includes a plurality of first upward protrusions 431 that are evenly arranged on the circumference of the first circle C1 and a plurality of second upward protrusions 432 that are evenly arranged on the circumference of the second circle C2. Unlike this example, the plurality of first upward protrusions 431 may not be evenly arranged on the circumference of the first circle C1, and the plurality of second upward protrusions 432 may not be evenly arranged on the circumference of the second circle C2.

[0078] In this example, the height of each upward protrusion 43 is uniform. The height of each upward protrusion 43 is the length from the upper surface 31 of the cooling plate 3 to the upper end of each upward protrusion 43. Unlike this example, the height of the second upward protrusion 432 may be higher than the height of the first upward protrusion 431. The upper and lower limit values ​​of the height and the reasons for specifying the upper and lower limit values ​​are the same as the upper and lower limit values ​​of the minimum distance and the reasons for specifying the upper and lower limit values. Note that, unlike this example, if the height of the second upward protrusion 432 is higher than the height of the first upward protrusion 431, the height of the second upward protrusion 432 may be 0.05 mm or more and 1.0 mm or less.

[0079] The thermal conductivity and dynamic friction coefficient of the upward protrusion 43 are similar to those of the pin member 41. The material of the upward protrusion 43 is the resin described in the section regarding the material of the pin member 41. The material of the upward protrusion 43 may be the same as or different from the material of the pin member 41.

[0080] [Embodiment 4] <Wafer holder> 9 to 11, wafer holder 1 of embodiment 4 will be described. Wafer holder 1 of embodiment 4 differs from wafer holder 1 of embodiment 1 in that restricting members 4 are composed of pin members 41 and lower support portions 512.

[0081] <Cooling plate> As shown in Fig. 9, the upper surface 31 of the cooling plate 3 has a plurality of outer peripheral recesses 34 in addition to the above-mentioned plurality of inner peripheral recesses 33. A lower support portion 512 of a support piece 51 is disposed in each outer peripheral recess 34. Each outer peripheral recess 34 opens to the upper surface 31. In this example, the plurality of outer peripheral recesses 34 are evenly arranged on the outer peripheral edge of the upper surface 31, as shown in Fig. 10. Unlike this example, the plurality of outer peripheral recesses 34 do not have to be evenly arranged on the outer peripheral edge of the upper surface 31.

[0082] <Regulating member> As shown in FIG. 9 , the restricting member 4 has the pin members 41 described in the first embodiment and the lower support portions 512 of the plurality of support pieces 51. In this embodiment, the diameter of the inscribed circle inscribed in all of the lower support portions 512 is smaller than the outer diameter of the cooling plate 3. That is, the length from the outer peripheral support portion 511 toward the center of each lower support portion 512 in this embodiment is longer than the length from the outer peripheral support portion 511 toward the center of the lower support portion 512 in the first embodiment. When the cooling plate 3 is raised, the bottom surface of the outer peripheral recess 34 of the cooling plate 3 comes into contact with the lower support portion 512. This contact restricts contact between the lower surface 22 of the heater 2 and the upper surface 31 of the cooling plate 3.

[0083] In this example, when the lower support portion 512 is in contact with the bottom of the outer peripheral recess 34, the length of the lower support portion 512 from the lower surface 22 of the heater 2 to the upper surface 31 of the cooling plate 3 is longer than the protruding length of the upward protrusion 414 of the pin member 41. In this example, as shown in FIG. 9 , the lower support portion 512 is in contact with the bottom of the outer peripheral recess 34, and before the cooling plate 3 is deformed as described above, neither the upward protrusion 414 of the first pin member 411 nor the upward protrusion 414 of the second pin member 412 is in contact with the lower surface 22 of the heater 2. As shown in FIG. 11 , when the lower support portion 512 is in contact with the bottom of the outer peripheral recess 34, after the cooling plate 3 is deformed as described above, the upward protrusion 414 of the first pin member 411 is in contact with the lower surface 22 of the heater 2, but the upward protrusion 414 of the second pin member 412 is not in contact with the lower surface 22 of the heater 2.

[0084] The upper and lower limit values ​​of the length of the lower support portion 512 from the lower surface 22 of the heater 2 to the upper surface 31 of the cooling plate 3, and the reasons for specifying these limits, are the same as the upper and lower limit values ​​of the minimum distance, and the reasons for specifying these limits. The protruding length of the upward protruding portion 414 of the first pin member 411 is set to a length that allows the upward protruding portion 414 of the first pin member 411 to contact the lower surface 22 of the heater 2 after the above-mentioned deformation of the cooling plate 3, as shown in Fig. 11. The protruding length of the upward protruding portion 414 of the second pin member 412 is set to a length that allows the upward protruding portion 414 of the second pin member 412 not to contact the lower surface 22 of the heater 2 after the above-mentioned deformation of the cooling plate 3, as shown in Fig. 11.

[0085] Unlike this example, the length from the lower surface 22 of the heater 2 to the upper surface 31 of the cooling plate 3 at the lower support portion 512 may be the same as the protruding length of the upward protruding portion 414 of the second pin member 412, and the protruding length of the upward protruding portion 414 of the second pin member 412 may be longer than the protruding length of the upward protruding portion 414 of the first pin member 411. Unlike this example, the length from the lower surface 22 of the heater 2 to the upper surface 31 of the cooling plate 3 at the lower support portion 512 may be the same as the protruding lengths of the upward protruding portions 414 of the first pin member 411 and the second pin member 412.

[0086] The thermal conductivity of the support piece 51 in this example is the same as the thermal conductivity of the pin member 41. That is, the thermal conductivity of the support piece 51 is, for example, 1 / 20 or less of the thermal conductivity of the cooling plate 3. The kinetic friction coefficient of the support piece 51 in this example is the same as the kinetic friction coefficient of the pin member 41. The material of the support piece 51 in this example is the resin described in the section regarding the material of the pin member 41. The material of the support piece 51 may be the same as or different from the material of the pin member 41.

[0087] [Embodiment 5] <Wafer holder> 12 and 13, a wafer holder 1 according to a fifth embodiment will be described. Wafer holder 1 according to the fifth embodiment differs from the wafer holders according to the first to fourth embodiments in that restricting member 4 is provided on lower surface 22 of heater 2. The following description will focus on the differences from the first to third embodiments. Descriptions of configurations and effects similar to those of the first to fourth embodiments may be omitted.

[0088] <Cooling plate> Unlike the first embodiment, the upper surface 31 of the cooling plate 3 of this example does not have the inner peripheral recess 33. The upper surface 31 of the cooling plate 3 is flat.

[0089] <Regulating member> The restricting member 4 is composed of a plurality of downward protrusions 44. In this example, the plurality of downward protrusions 44 include a plurality of first downward protrusions 441 that are evenly arranged around the circumference of the first circle C1 on the lower surface 22 of the heater 2, and a plurality of second downward protrusions 442 that are evenly arranged around the circumference of the second circle C2 on the lower surface 22 of the heater 2.

[0090] In this example, the height of each downward protrusion 44 is uniform. The height of the downward protrusion 44 is the length from the lower surface 22 of the heater 2 to the lower end of the downward protrusion 44. In this case, as shown in Fig. 12, before the cooling plate 3 is deformed as described above, both the first downward protrusion 441 and the second downward protrusion 442 are in contact with the upper surface 31 of the cooling plate 3. After the cooling plate 3 is deformed as shown in Fig. 13, the first downward protrusion 441 is in contact with the upper surface 31 of the cooling plate 3, but the second downward protrusion 442 is not in contact with the upper surface 31 of the cooling plate 3.

[0091] Unlike this example, the height of the second downward protrusion 442 may be greater than the height of the first downward protrusion 441. When the height of the second downward protrusion 442 is greater than the height of the first downward protrusion 441, before the above-described deformation of the cooling plate 3, the first downward protrusion 441 does not contact the upper surface 31 of the cooling plate 3, but the second downward protrusion 442 contacts the upper surface 31 of the cooling plate 3. After the above-described deformation of the cooling plate 3, both the first downward protrusion 441 and the second downward protrusion 442 contact the upper surface 31 of the cooling plate 3.

[0092] The upper and lower limit values ​​of the height and the reasons for specifying the upper and lower limit values ​​are the same as the upper and lower limit values ​​of the minimum distance and the reasons for specifying the upper and lower limit values. Note that, unlike this example, when the height of second downward protrusion 442 is higher than the height of first downward protrusion 441, the height of second downward protrusion 442 should be 0.05 mm or more and 1.0 mm or less.

[0093] The thermal conductivity and dynamic friction coefficient of the downward protrusion 44 are similar to those of the pin member 41. The material of the downward protrusion 44 is the resin described in the section regarding the material of the pin member 41. The material of the downward protrusion 44 may be the same as or different from the material of the pin member 41.

[0094] [Embodiment 6] <Wafer holder> Wafer holder 1 of embodiment 6 will be described with reference to Figure 14. Wafer holder 1 of embodiment 6 differs from wafer holder 1 of embodiment 5 in that restricting member 4 is composed of downward protrusion 44 and downward support portion 512. The following description will focus on the differences from embodiment 5. Description of configurations and effects similar to those of embodiment 5 may be omitted.

[0095] <Cooling plate> The upper surface 31 of the cooling plate 3 has a plurality of peripheral recesses 34 as described in the fourth embodiment.

[0096] <Regulating member> The restricting member 4 has the plurality of downward protrusions 44 described in the fifth embodiment and the downward support portions 512 of the plurality of support pieces 51 described in the fourth embodiment. In this example, when the downward support portions 512 are in contact with the bottom of the outer peripheral recess 34, the length of the downward support portions 512 from the upper surface 31 of the cooling plate 3 to the lower surface 22 of the heater 2 is longer than the height of the downward protrusions 44. In this example, the downward support portions 512 are in contact with the bottom of the outer peripheral recess 34, and before the cooling plate 3 is deformed as described above, neither the first downward protrusions 441 nor the second downward protrusions 442 are in contact with the upper surface 31 of the cooling plate 3. When the downward support portions 512 are in contact with the bottom of the outer peripheral recess 34, and after the cooling plate 3 is deformed as described above, the first downward protrusions 441 are in contact with the upper surface 31 of the cooling plate 3, but the second downward protrusions 442 are not in contact with the upper surface 31 of the cooling plate 3.

[0097] The upper and lower limit values ​​of the length of the lower support portion 512 from the upper surface 31 of the cooling plate 3 to the lower surface 22 of the heater 2 and the reasons for specifying the upper and lower limit values ​​are the same as the upper and lower limit values ​​of the minimum distance and the reasons for specifying the upper and lower limit values ​​described above. The height of the first downward protrusion 441 is set to a length that allows the first downward protrusion 441 to contact the upper surface 31 of the cooling plate 3 after the above-mentioned deformation of the cooling plate 3.

[0098] Unlike this example, the length from the lower surface 22 of the heater 2 to the upper surface 31 of the cooling plate 3 at the lower support portion 512 may be the same as the height of the second downward protrusion 442, and the height of the second downward protrusion 442 may be higher than the height of the first downward protrusion 441. Unlike this example, the length from the lower surface 22 of the heater 2 to the upper surface 31 of the cooling plate 3 at the lower support portion 512 may be the same as the heights of the first downward protrusion 441 and the second downward protrusion 442.

[0099] [Test Example 1] In Test Example 1, samples were prepared in which regulating members of various thicknesses were placed between the lower surface of the heater and the upper surface of the cooling plate, and the cooling rate and temperature uniformity of the heater were examined.

[0100] <Sample No. 1-Sample No. 8> The heater for each sample was disk-shaped. The heater was 3 mm thick and 330 mm in diameter. The heater's thermal conductivity was 150 W / m·K. The cooling plate for each sample was disk-shaped. The top surface of the cooling plate was flat. The cooling plate was 8 mm thick and 330 mm in diameter. The cooling plate's thermal conductivity was 200 W / m·K. The thermal conductivity of the regulating member for each sample was 0.3 W / m·K. Three regulating members were evenly spaced around the outer edge of the top surface of the cooling plate. The length of the regulating members along the radial direction of the cooling plate was 150 mm. The thicknesses of the regulating members for Samples No. 1 to No. 8 were 0.045 mm, 0.05 mm, 0.1 mm, 0.2 mm, 0.25 mm, 0.5 mm, 1.0 mm, and 1.5 mm, respectively. That is, in each of Samples No. 1 to No. 8, the distance between the lower surface of the heater and the upper surface of the cooling plate when the regulating member is in contact with the lower surface of the heater is 0.045 mm, 0.05 mm, 0.1 mm, 0.2 mm, 0.25 mm, 0.5 mm, 1.0 mm, or 1.5 mm.

[0101] After the heater's top surface was heated to 250°C, a cooling plate heated to 20°C was brought close to the heater's bottom surface, and the regulating member was placed in contact with the heater's bottom surface. The time required for the heater's top surface temperature to cool from 250°C to 150°C was measured, and the cooling rate and temperature distribution on the heater's top surface were calculated. The heater's top surface temperature was measured using nine resistance thermometers. A heater top surface temperature of 250°C refers to the lowest temperature measured by the nine resistance thermometers, and a heater top surface temperature of 150°C refers to the highest temperature measured by the nine resistance thermometers. The temperature distribution is the difference between the highest and lowest temperatures measured by the nine resistance thermometers when the heater's top surface temperature reached 150°C. The results are shown in Table 1.

[0102] [Table 1]

[0103] From Table 1, it was found that the cooling rate of the heater can be made 10°C / min or more even if a restricting member with a thickness of 1.0 mm or less is placed between the bottom surface of the heater and the top surface of the cooling plate. It was also found that the average temperature difference of the heater can be made 10°C or less by making the distance between the bottom surface of the heater and the top surface of the cooling plate 0.05 mm or more.

[0104] [Test Example 2] In Test Example 2, models were designed in which restricting members with various contact areas were placed between the bottom surface of the heater and the top surface of the cooling plate, and the uniform heating performance of the heater was investigated by simulation.

[0105] <Model No.1-Model No.7> In each model, as in the third embodiment described with reference to FIG. 8, the regulating member 4 includes three first upward protrusions 431 evenly spaced on a first circle C1 (FIG. 3) on the upper surface 31 of the cooling plate 3, and three second upward protrusions 432 evenly spaced on a second circle C2 (FIG. 3). The height of each upward protrusion 43 was 0.25 mm. That is, in each model, the distance between the lower surface 22 of the heater 2 and the upper surface 31 of the cooling plate 3 when the regulating member 4 was in contact with the lower surface 22 of the heater 2 was 0.25 mm. The thermal conductivity of the cooling plate 3 was 200 W / m·K. The thermal conductivity of the regulating member 4 was 1.0 W / m·K. The contact area between the lower surface 22 of the heater 2 and the regulating member 4 in each model was 10%, 7.0%, 5.0%, 1.0%, 0.1%, 0.01%, or 0.00%.

[0106] In each model, the temperature of the upper surface 21 of the heater 2 was raised to 250°C, and then the cooling plate 3, whose temperature had been set to 20°C, was brought close to the lower surface 22 of the heater 2. In Models 1 to 6, each of the upper protrusions 43 was brought into contact with the lower surface 22 of the heater 2. In Model 7, each of the upper protrusions 43 was brought close to the lower surface 22 of the heater 2 without touching it. 90 seconds after this contact or close proximity, the temperature difference between the maximum and minimum temperatures was determined at 80 measurement points equally spaced radially from the center to the outer periphery of the upper surface 21 of the heater 2. The temperature differences are shown in Table 2.

[0107] [Table 2]

[0108] From Table 2, it was found that if the contact area between the lower surface of the heater and the regulating member is set to 5.0% or less, the average temperature difference of the heater can be set to 10°C or less.

[0109] The present invention is not limited to the configurations shown in the embodiments, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0110] 1 Wafer holder 2 heaters 21 Top side 22 Bottom side 3 Cooling Plate 31 Top side 32 Bottom surface 33 Inner recess 331 First inner recess 332 Second inner recess 34 Outer periphery recess 35 refrigerant flow path 4. Regulatory components 41 Pin member 411 First pin member 412 Second pin member 413 Base 414 Upper protrusion 42 Sheet material 421 Base 422 Upper protrusion 423 First upward protrusion 424 Second upward protrusion 43 Upper protrusion 431 First upward protrusion 432 Second upward protrusion 44 Downward protrusion 441 First downward protrusion 442 Second downward protrusion 5 Support member 51 Support piece 511 Periphery support part 512 Lower support part 52 Legs 8 Lifting mechanism 9 Base 100 wafers Area A a center C1 1st Circle C2 Second Circle

Claims

1. a heater having an upper surface on which a wafer is placed and a lower surface opposite to the upper surface; a cooling plate that is arranged below the heater so as to be able to move up and down and has an upper surface that moves close to and away from the lower surface; a restricting member that restricts contact between the lower surface of the heater and the upper surface of the cooling plate by partially contacting at least one of the lower surface of the heater and the upper surface of the cooling plate, the thermal conductivity of the regulating member is lower than the thermal conductivity of the cooling plate; the regulating member regulates the minimum distance between the lower surface of the heater and the upper surface of the cooling plate to 0.05 mm or more and 1.0 mm or less; a ratio of a contact area between the lower surface of the heater and the regulating member to an area of ​​the lower surface of the heater is 5.0% or less; Wafer holder.

2. 2. The wafer holder according to claim 1, wherein said regulating member has an upward protruding portion that protrudes from said upper surface of said cooling plate toward said heater.

3. 3. The wafer holder according to claim 2, wherein said upward protrusion is provided at a center of said upper surface of said cooling plate.

4. the upper surface of the cooling plate has an inner peripheral recess that is located inside an outer peripheral edge of the cooling plate; the restricting member has a pin member disposed in the inner peripheral recess, 4. The wafer holder according to claim 2, wherein said pin members have said upward protrusions.

5. the restricting member has a sheet member provided on the upper surface of the cooling plate, 4. The wafer holder according to claim 2, wherein the sheet member has the upward protrusion.

6. 4. The wafer holder according to claim 2, wherein said regulating member has said upward protrusion provided on said upper surface of said cooling plate.

7. The upward protrusion is a plurality of first upward protrusions evenly arranged on the circumference of a first circle whose center is the center of the envelope circle of the cooling plate; 4. The wafer holder according to claim 2, further comprising: a plurality of second upward protrusions evenly arranged on the circumference of a second circle that is concentric with the first circle and has a radius larger than that of the first circle.

8. 8. The wafer holder according to claim 7, wherein the height of each of the plurality of second upward protrusions is greater than the height of each of the plurality of first upward protrusions.

9. 4. The wafer holder according to claim 2, wherein said regulating member has a support piece for supporting an outer peripheral edge portion of said lower surface of said heater.

10. the upper surface of the cooling plate has a peripheral recess provided on the peripheral edge of the cooling plate; The support base according to claim 9 , wherein a lower surface of the support piece is provided so as to come into contact with a bottom surface of the outer peripheral recess.

11. 11. The wafer support table according to claim 10, wherein when the lower surface of the support piece and the bottom surface of the outer peripheral recess are in contact with each other, a length of a gap between the lower surface of the heater and the upper surface of the cooling plate is longer than a length of protrusion of the upward protrusion from the upper surface of the cooling plate.

12. 4. The wafer holder according to claim 1, wherein the coefficient of dynamic friction of said regulating member with respect to said heater is 0.5 or less.

13. 2. The wafer holder according to claim 1, wherein said regulating member has a downward protruding portion that protrudes from said lower surface of said heater toward said cooling plate.

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