Wafer holder

Abstract

To provide a wafer holding body having both rigidity, which makes the wafer holding body hard to be bent, and heat uniformity even in a configuration internally comprising a cooling mechanism.SOLUTION: The present invention relates to a wafer holding body comprising a first plate, a second plate and a heater and defining a top face of the first plate as a mounting surface of a wafer. In the wafer holding body, the first plate includes a disk-shaped body part internally comprising a flow passage of a coolant, and a leg part protruding from a bottom face of the body part. The heater is provided at a position in contact with the bottom face or inside of the first plate, and the second plate is provided so as to be in contact with a lower side end face of the leg part. An interval between an upper end face of the flow passage and the top face is equal to or more than 2 mm and equal to or less than 45 mm, an interval between a lower end face of the flow passage and the bottom face is equal to or more than 2 mm and equal to or less than 33 mm, and an interval between the top face and the lower side end face is equal to or more than 16 mm and equal to or less than 80 mm.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a wafer holder.

Background Art

[0002] There is known a wafer holder that performs inspections and the like while controlling the temperature of a semiconductor wafer by heating or cooling the wafer placed on the upper surface, such as a wafer prober. Patent Document 1 discloses a configuration in which a high thermal conductivity material is attached to the back side of a chuck top for the purpose of providing a wafer holder for a wafer prober that is excellent in the uniformity of temperature distribution in a wide temperature range without impairing the high rigidity of the chuck top. Patent Document 2 discloses a configuration of a wafer holder for a wafer prober including a chuck top and a heating element, and having a cooling mechanism in which a fluid flows through a gap formed between the support and the heating element. Patent Document 3 discloses a substrate mounting table in which a refrigerant flow path is provided inside a chuck top.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a wafer holder, for example, in a wafer prober, a large force may be applied to the entire wafer or a part of the wafer by the pressing of the probe during inspection. The wafer holder needs to have rigidity such that it does not bend under such a force. If the wafer holder bends, a gap may be generated between the wafer and the wafer, which may adversely affect the temperature uniformity within the wafer surface. Furthermore, depending on the applied force, it may lead to damage of the wafer holder itself. Means for increasing the rigidity of the entire wafer holder as in Patent Document 1 can be considered. However, in a configuration such as that in Patent Document 3 where a flow path is provided inside the chuck top itself, it is difficult to ensure the overall rigidity because the thickness of the chuck top is partially different. One of the objects of the present disclosure is to provide a wafer holder that has a hard-to-bend rigidity and a heat uniformity even in a configuration provided with a cooling mechanism inside.

Means for Solving the Problems

[0005] The wafer holder of the present disclosure is a wafer holder including a first plate, a second plate, and a heater, with the upper surface of the first plate serving as the placement surface for the wafer, wherein the first plate includes a disk-shaped main body portion having a refrigerant flow path inside and a leg portion protruding from the lower surface of the main body portion, the heater is provided at a position in contact with the lower surface or inside the first plate, the second plate is provided so as to be in contact with the lower end surface of the leg portion, the distance between the upper end surface of the flow path and the upper surface is 2 mm or more and 45 mm or less, the distance between the lower end surface of the flow path and the lower surface is 2 mm or more and 33 mm or less, the distance between the upper surface and the lower end surface is 16 mm or more and 80 mm or less.

Advantages of the Invention

[0006] According to the wafer holder of the present disclosure, even in a configuration provided with a cooling mechanism inside, it can have a hard-to-bend rigidity and a heat uniformity.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 4D

Figure 4E

Figure 4F

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Figure 9

Figure 10

Mode for Carrying Out the Invention

[0008] [Description of Embodiments of the Present Disclosure] Hereinafter, embodiments of the present disclosure will be listed and described.

[0009] (1) The wafer holder of the present disclosure includes a first plate, a second plate, and a heater, and is a wafer holder having the upper surface of the first plate as a wafer placement surface, the first plate includes a disk-shaped main body portion having a refrigerant flow path inside and a leg portion protruding from the lower surface of the main body portion, the heater is provided at a position in contact with the lower surface or inside the first plate, the second plate is provided so as to be in contact with the lower end surface of the leg portion, the distance between the upper end surface of the flow path and the upper surface is 2 mm or more and 45 mm or less, the distance between the lower end surface of the flow path and the lower surface is 2 mm or more and 33 mm or less, the distance between the upper surface and the lower end surface is 16 mm or more and 80 mm or less.

[0010] By providing the leg portion on the first plate, the wafer holder of the present disclosure can have both rigidity that is difficult to bend and heat uniformity even when a cooling mechanism is provided inside the first plate. Here, the distance between surfaces is the surface-to-surface distance in the direction perpendicular to the placement surface, and is defined in the same manner in the present disclosure.

[0011] (2) The distance between the upper end surface of the flow path and the upper surface may be 2 mm or more and 10 mm or less, and the distance between the lower end surface of the flow path and the lower surface may be 2 mm or more and 10 mm or less.

[0012] According to the above configuration, even when the distance between the flow path and the upper surface or the lower surface is close and the thickness of the first plate is thin, it is possible to have both rigidity that is difficult to bend and heat uniformity.

[0013] (3) The ratio of the area of the leg portion to the total area of the lower surface on the lower surface may be 5% or more and 50% or less.

[0014] When the ratio of the leg portions on the lower surface of the first plate is within the above range, heat transfer between the first plate and the second plate does not become excessively large, and the heat uniformity of the first plate can be further enhanced.

[0015] (4) In a plan view of the first plate, the leg portions may have a plurality of straight portions extending radially from the center of the first plate.

[0016] By making the leg portions have the above configuration, it becomes easy to suppress the deflection of the first plate.

[0017] (5) In a plan view of the first plate, the leg portions may have arc portions concentric with the center of the first plate.

[0018] By providing the leg portions having the above configuration, it becomes easy to suppress the deflection of the first plate. By having the leg portions have both a plurality of straight portions extending radially and arc portions concentric therewith, a first plate having higher rigidity and being less likely to deflect can be obtained.

[0019] (6) In a cross-section of the first plate perpendicular to the upper surface and passing through the center of the first plate, the flow path is configured such that the cooling capacity of the outer peripheral portion of the first plate is higher than the cooling capacity of the central portion of the first plate, the central portion is a circular region with a circle having a radius of 90% of the radius of the wafer as the outer edge, centered on the center of the wafer placed on the upper surface, the outer peripheral portion may be an annular region with a concentric circle having a radius of 99% of the radius of the first plate as the outer edge, with the outer edge as the inner peripheral edge.

[0020] In a configuration having a refrigerant flow path inside the main body of the first plate, the outer peripheral portion may be less likely to be cooled compared to the central portion of the upper surface which is the wafer placement surface. One reason is that the outer peripheral portion of the wafer holder is close to external equipment such as a chamber where the wafer holder is installed. By enhancing the cooling capacity of the outer peripheral portion as in the above configuration, it becomes possible to further enhance the isothermal property of the entire wafer holder.

[0021] (7) In the cross-section of the first plate passing through the center of the first plate and perpendicular to the upper surface, the density of the number of the flow paths in the outer peripheral portion may be higher than the density of the number of the flow paths in the central portion.

[0022] According to the above configuration, it is possible to provide a difference in the cooling capacity between the central portion and the outer peripheral portion of the first plate with a simple configuration.

[0023] (8) The thickness of the second plate may be 0.5 mm or more and 50 mm or less.

[0024] When the thickness of the second plate is within the above range, the effect of enhancing the rigidity of the entire wafer holder by the second plate supporting the first plate from the lower surface side can be enhanced.

[0025] (9) It may further include a heat insulating material interposed between the outer peripheral portion of the lower surface and a support for supporting the wafer holder.

[0026] The wafer holder is attached to the chamber main body or the base by a support such as a support column that supports the outer peripheral portion of the first plate from the lower surface side. By providing a heat insulating material as in the above configuration, the heat of the first plate being transmitted to the base etc. through the support such as a support column is suppressed. With such a configuration, the isothermal property of the wafer holder can be further enhanced.

[0027] (10) The material of the first plate may be any one of copper, copper alloy, aluminum, or aluminum alloy.

[0028] If the material of the first plate is the above-described metal, a wafer holder excellent in heat conduction can be obtained at a practical cost. That is, it is possible to efficiently heat or cool in both cases where the temperature of the mounting surface is heated by a heater and cooled by a refrigerant.

[0029] (11) The material of the first plate may be ceramics or a composite of ceramics.

[0030] If the material of the first plate is ceramics or the like, it is easier to obtain high rigidity at the same thickness compared to the case of metal. Therefore, even in a configuration where the first plate is provided with a flow path, a wafer holder that is more difficult to bend can be obtained. Or, a wafer holder having the same rigidity can be configured with a thinner thickness.

[0031] (12) The material of the second plate may be ceramics or a composite of ceramics.

[0032] If the material of the second plate is ceramics or the like, it is easier to obtain high rigidity at the same thickness compared to the case of metal, and a wafer holder that is more difficult to bend can be obtained. Or, a wafer holder having the same rigidity can be configured with a thinner thickness. When the first plate is also made of ceramics, the ceramics of the second plate may be the same material as or different from the ceramics of the first plate.

[0033] (13) The heater is provided in contact with the lower surface, The heater may be a laminate of a first resin layer, a heater circuit layer, and a second resin layer.

[0034] The heater with the above configuration is in the form of a thin flat plate and has excellent adhesion to the lower surface of the first plate. Also, it is possible to reduce the overall thickness of the wafer holder. Furthermore, since it can be easily adhered to the lower surface of the first plate other than the leg portions, the production of the wafer holder is easy. The materials of the first resin layer and the second resin layer may be polyimide resin or silicone resin filled with filler.

[0035] [Details of Embodiments of the Present Disclosure] The wafer holder according to an embodiment of the present disclosure will be described with reference to the drawings. The wafer holder of the present disclosure can be used as part of a semiconductor manufacturing apparatus. Hereinafter, the wafer holder used in a wafer prober will be described as an example. A wafer prober is an inspection apparatus that measures the electrical performance of each chip in a state where a semiconductor wafer on which a circuit is formed is controlled to a predetermined temperature before cutting the wafer into individual chips. The wafer holder according to an embodiment of the present disclosure is not limited to a wafer prober and can also be used for wafer holders for other applications having a similar structure. The same reference numerals in the drawings denote the same components. The sizes and positional relationships of the members shown in each drawing are represented for the purpose of clarifying the description and do not necessarily represent actual dimensional relationships. Also, the side on which the wafer is placed is defined as the upper side, and the opposite side is defined as the lower side for representing the direction.

[0036] [Configuration of Wafer Holder] (Embodiment) The wafer holder 1 exemplified in this embodiment will be described with reference to the drawings. FIG. 1 is a schematic plan view of the wafer holder according to the embodiment as viewed from the lower side, and FIG. 2 is a longitudinal sectional view schematically showing the A-A cross section of FIG. 1. Referring to FIGS. 1 and 2, the wafer holder 1 includes a first plate 10, a heater 30, and a second plate 20. Note that the wafer holder 1 may further include another plate (not shown), but this is not essential. The upper surface 11 of the first plate 10 is a mounting surface on which the wafer S is placed. Hereinafter, the upper surface 11 of the first plate 10 may be referred to as the mounting surface 11.

[0037] The wafer holder 1 of this example includes a flow path 100 for flowing a refrigerant inside the first plate 10. FIG. 3 is a diagram for explaining the shape of the flow path 100 as an example in a plan view. FIG. 3 is a schematic cross-sectional view showing the B-B cross section of FIG. 2. However, these figures are merely schematic diagrams for explaining the configuration, and the sizes and positional relationships of the respective parts do not necessarily correspond to each other. FIG. 3 shows a state in which the portion where the flow path 100 of the wafer holder 1 exists is cut by a plane parallel to the mounting surface 11. The flow path 100 is formed so that concentric arcs are connected inside the first plate 10 which is circular in plan view, for example. The refrigerant flows into the flow path 100 from the inlet 101, circulates through the flow path 100, and is discharged from the outlet 102. The shape of the flow path 100 is an example for explanation and is not limited to the illustrated shape. In this example, there is one flow path 100, but the number of flow paths may be plural. A plurality of flow paths may be provided in the same plane, or the flow paths may be configured to branch or merge inside.

[0038] FIG. 2 simply shows a state in which a plurality of cross sections of the flow path in a direction perpendicular to the flow direction of the refrigerant are arranged. The first plate is composed of a plate-shaped main body 15 having an upper surface 11 and a lower surface 12, and legs 13 provided on the lower surface 12. The legs 13 are preferably formed as a member integral with the main body 15. The legs 13 and the main body 15 may be separate members.

[0039] The heater 30 is arranged to contact the lower surface 12 of the first plate 10. The heater 30 is provided on substantially the entire lower surface 12 except for the leg portion 13. Here, the heater 30 is a plate-shaped heater which will be described later. In this example, the surface of the heater 30 opposite to the side contacting the first plate 10 does not contact the second plate 20. That is, in this example, there is a space 14 other than the leg portion 13 of the first plate 10 between the heater 30 and the second plate 20. Due to the existence of the space 14, the heat transfer between the first plate 10 and the second plate 20 is suppressed. The space 14 may be filled with other members. For example, the other member may be a heat insulating material. Note that the heater 30 is not limited to the plate-shaped heater as in this example. Also, the heater 30 may be arranged to be embedded in the first plate 10 in addition to contacting the lower surface 12 of the first plate 10.

[0040] The upper surface 21 of the second plate 20 contacts the lower end surface 13a of the leg portion 13 of the first plate 10. The first plate 10 and the second plate 20 are fixed by a fastening member 50 so that their respective surfaces are in close contact. In this example, the fastening member 50 is a bolt inserted from the lower surface 22 of the second plate 20 and is fixed by a threaded portion provided inside the leg portion 13 of the first plate 10. When the fastening member 50 deeply penetrates into the first plate 10 and reaches the position where the flow path 100 exists, as illustrated in FIG. 3, the flow path 100 is provided so as to avoid the fastening member 50.

[0041] <First Plate> The first plate 10 is a member having a plate-shaped main body portion 15 whose upper surface is used as a wafer placement surface 11. Although not shown in this example, a suction mechanism for the wafer S may be provided on the upper surface 11 of the first plate 10 which serves as the placement surface of the wafer S. Specific examples of the suction mechanism include a vacuum chuck including a groove portion provided on the upper surface 11 of the first plate 10 and an exhaust passage for exhausting from the groove portion, an electrostatic chuck, a mechanical clamp, and the like. When a vacuum chuck is provided, a suction passage may be provided inside the first plate 10 separately from the refrigerant flow passage 100. The overall shape of the first plate 10 is a shape adapted to the shape of the wafer S, and is usually circular in a top view. The size of the first plate 10 is such that there is a slight margin around when the wafer S is placed thereon. Examples of the size of the wafer S include a diameter of 200 mm, a diameter of 300 mm, a diameter of 450 mm, and the like. For example, when the size of the wafer S is 300 mm in diameter, the diameter of the first plate 10 can be 310 mm.

[0042] The first plate 10 includes legs 13 protruding from the lower surface 12 of the main body portion 15. The legs 13 may be made of the same material as the main body portion 15. When the legs 13 and the main body portion 15 are made of the same material, the legs 13 and the main body portion 15 may be integrally formed, or the legs 13 may be formed by cutting out from a single material. The shapes of the legs 13 are illustrated in FIGS. 4A to 4F. FIGS. 4A to 4F all illustrate representative arrangement shapes of the legs 13 in a plan view of the first plate 10. The shape, number, thickness, length, arrangement, etc. of the legs 13 are not limited to these. The legs 13 shown in FIG. 4A are an example of a plurality of straight portions extending radially from the center of the first plate 10. The legs 13 shown in FIG. 4B are an example of an arc portion concentric with the center of the first plate 10. The legs 13 may be configured by combining the straight legs 13 shown in FIG. 4A and the arc legs 13 shown in FIG. 4B. As a combined shape, the legs 13 may be in the shapes shown in FIGS. 4C, 4D, and 4E. Further, as illustrated in FIG. 4F, the legs 13 may be arranged at the center of the first plate 10.

[0043] On the lower surface 12 of the main body portion 15, the ratio of the area occupied by the leg portion 13 to the total area of the lower surface 12 is preferably 5% or more and 50% or less. The total area of the lower surface 12 is the area of the circle of the circular lower surface. The area occupied by the leg portion 13 is the sum of the areas of the portions where the leg portion 13 and the main body portion 15 are in contact. When the leg portion 13 is integrally formed with the main body portion 15, it is the area of the virtual cross-section of the leg portion 13 when the leg portion 13 is cut along the lower surface 12. If the ratio of the above area is less than 5%, sufficient rigidity of the entire first plate cannot be obtained. If the ratio of the area exceeds 50%, sufficient heat insulation between the main body portion 15 and the second plate 20 cannot be obtained. Also, if the ratio of the area exceeds 50%, in the structure where the heater 30 is disposed on the lower surface 12, the area for providing the heater 30 becomes small, and effective heating performance is impaired. The lower limit of the ratio of the area of the leg portion 13 is more preferably 7% or more, and the upper limit is more preferably 21% or less.

[0044] As the material of the first plate 10, a metal, a non-metal, or a composite of a metal and a non-metal having excellent thermal conductivity can be used. The higher the thermal conductivity of the material of the first plate 10, the more preferable. Examples of the metal include copper, copper alloy, silver, silver alloy, aluminum, aluminum alloy, etc. Examples of the non-metal include silicon and ceramics. Examples of the ceramics include aluminum nitride and silicon carbide. Examples of the composite of ceramics include a composite of silicon and silicon carbide, a composite of aluminum and silicon carbide, a composite of aluminum, silicon, and silicon carbide, etc. The material of the first plate 10 in this example is copper.

[0045] The thermal conductivity of the constituent material of the first plate 10 is preferably 100 W / m·K or more. This thermal conductivity is more preferably 200 W / m·K or more, 300 W / m·K or more, and particularly preferably 400 W·K or more. As typical values, the thermal conductivity of aluminum is about 230 W / m·K, the thermal conductivity of copper is about 400 W / m·K, and the thermal conductivity of silver is about 420 / m·K. The thermal conductivity of silicon carbide is about 200 W / m·K, and the thermal conductivity of aluminum nitride is about 150 W / m·K.

[0046] The surface of the first plate 10 may be subjected to a surface treatment. Examples of this surface treatment include plating. Specific examples of plating include Ni plating and Ni-P plating. Examples of plating methods include electrolytic plating and electroless plating. The surface treatment in this example is Ni-P plating by electroless plating. When copper containing oxygen-free copper is used as the first plate 10, it is preferable to perform Ni plating or Ni-P plating. Since copper easily diffuses into silicon, which is a constituent material of the wafer, the above diffusion can be suppressed by performing Ni plating or Ni-P plating. As a result, the reliability of the device obtained from the wafer is ensured.

[0047] The first plate 10 is provided with a refrigerant flow path 100. Although the cross-sectional shape of the flow path 100 is not limited, considering the cooling efficiency of the wafer and the ease of manufacturing the wafer holder, the cross-section of the flow path 100 is preferably rectangular. The rectangle is such that two opposite sides are parallel to the placement surface 11 and the other two sides are perpendicular to the placement surface 11. This is because the distance between the refrigerant flowing through the flow path 100 and the placement surface 11 is close and constant, making it easy to keep the temperature distribution of the placement surface 11 uniform. The flow path 100 needs to have a sufficient cross-sectional area to allow the refrigerant to flow at the target flow rate. The cross-sectional area of the flow path 100 in the direction perpendicular to the flow of the refrigerant depends on the type of refrigerant used and the temperature at which it is used, but is 5 mm 2 or more is considered necessary. The cross-sectional area of the flow path 100 is preferably 10 mm 2 or more, and more preferably 15 mm 2 or more.

[0048] <Second Plate> The second plate 20 is a member that supports the first plate 10 from the lower surface side. The overall shape of the second plate 20 is a shape that matches the shape of the wafer S, and is usually circular in plan view. The size of the second plate 20 may be the same as that of the first plate 10, or may be smaller than the first plate 10. The first plate 10 and the second plate 20 are arranged so as to have a common center in plan view. When the diameter of the first plate 10 is larger than the diameter of the second plate 20, an annular portion that is the outer peripheral portion of the lower surface 12 of the first plate 10 is exposed.

[0049] As the material of the second plate 20, a metal, a non-metal, or a composite of a metal and a non-metal with excellent thermal conductivity can be used. Examples of the metal include copper, copper alloy, silver, silver alloy, aluminum, and aluminum alloy. Examples of the non-metal include silicon and ceramics. Examples of the ceramics include aluminum nitride and silicon carbide. Examples of the composite of ceramics include a composite of silicon and silicon carbide, a composite of aluminum and silicon carbide, and a composite of aluminum, silicon, and silicon carbide. Since the second plate 20 has a function of supporting the first plate 10, ceramics or a composite thereof with high rigidity is preferably used. In this example, the material of the second plate 20 is ceramics, which is a composite of silicon and silicon carbide. The thermal conductivity of the constituent material of the second plate 20 is preferably 100 W / m·K or more. More preferably, this thermal conductivity is 200 W / m·K or more, 300 W / m·K or more, and particularly preferably 400 W or more.

[0050] <Heater> The heater 30 is a heating element used to heat or cool the wafer S to a predetermined temperature. The shape of the heater 30 in this embodiment is flat. FIG. 5 shows a schematic diagram for explaining the cross-sectional structure of the heater 30 according to this embodiment. The heater 30 in this example is a laminate of a first resin layer 31, a heater circuit layer 32, and a second resin layer 33. The heater circuit layer 32 is a metal circuit pattern as a resistance heating element, which generates heat when energized. In this example, the heater circuit layer 32 is composed of a stainless steel thin film. Other metals may be used for the heater circuit layer 32, and it is not limited thereto. Although the laminated structure is schematically explained in FIG. 5, it is preferable that the first resin layer 31 and the second resin layer 33 are filled so as to fill the gaps of the heater circuit layer 32. Further, the surfaces of the first resin layer 31 and the second resin layer 33 may have an uneven shape according to the arrangement of the heater circuit layer 32 instead of being flat.

[0051] The first resin layer 31 and the second resin layer 33 are resin sheets used for insulating the heater circuit layer 32 and maintaining the pattern shape. In this example, polyimide resin is used as the first resin layer 31. Also, a silicone resin filled with a filler is used as the second resin layer 33. The first resin layer 31 using polyimide resin has, for example, a thermal conductivity of 0.3 W / m·K and a thickness of 0.05 mm. The second resin layer 33 using a silicone resin filled with a filler has, for example, a thermal conductivity of 5 W / m·K and a thickness of 0.5 mm. In this example, the heater 30 is provided on the lower surface 12 of the first plate 10. The joining of the heater 30 and the lower surface 12 of the first plate is, for example, by screwing. The second resin layer 33 is in contact with the first plate 10. The shape of the heater 30 is generally disk-shaped as a whole. The heater 30 is attached so as to be in close contact with the lower surface 12 of the first plate excluding the leg portion 13. The specific shape of the heater 30 is a shape excluding the shape corresponding to the leg portion 13 from a circle. Therefore, the heater 30 is not limited to being composed of a single sheet as a whole, and may have a shape divided into a plurality of sheets. When the lower surface of the first plate 10 is divided into a plurality of closed regions by the leg portions 13, the heater 30 is divided into a plurality of parts.

[0052] (Modification example) FIG. 6 is a diagram showing a modified example of the wafer holder 1 according to the embodiment. The wafer holder 1 in FIG. 6 is characterized by the configuration of the flow path 100 provided in the first plate 10. That is, in a cross section perpendicular to the upper surface 11 and passing through the center of the first plate 10, the flow path 100 is configured such that the cooling capacity of the outer peripheral portion of the first plate 10 is higher than that of the central portion of the first plate 10. Here, the central portion of the first plate 10 is a circular region having as an outer edge a circle with a radius of 90% of the radius of the wafer S placed on the upper surface 11, centered on the center of the wafer S. That is, from the center line CL shown in FIG. 6, the region having as an outer edge a circle drawn with a value of (DS / 2)×0.9 of the diameter DS of the wafer S as the radius is the central portion. The outer peripheral portion of the first plate 10 is an annular region having as an inner peripheral edge the outer edge described above and as an outer peripheral edge a concentric circle with a radius of 99% of the radius of the first plate 10. That is, the outer peripheral portion is an annular region having as an inner peripheral edge the outer edge of the central portion described above and as an outer peripheral edge a concentric circle with a radius of (D1 / 2)×0.99 of the diameter D1 of the first plate 10.

[0053] FIG. 6 shows a configuration in which the density of the number of the flow paths 100 in the outer peripheral portion is higher than the density of the number of the flow paths 100 in the central portion as a configuration example for increasing the cooling capacity of the outer peripheral portion compared to the central portion of the first plate 10. Inside the first plate 10, the adjacent intervals of the flow paths 100 are closer in the outer peripheral portion than in the central portion of the first plate 10. With this structure, the density of the flow paths 100 in the outer peripheral portion becomes high, and the cooling capacity can be increased. Note that when the density of the number of the flow paths 100 is not constant in each of the central portion and the outer peripheral portion, the density is the average density within each range. In addition, as a configuration for increasing the cooling capacity of the outer peripheral portion, the cross-sectional shape of the flow path 100 may be different between the central portion and the outer peripheral portion. For example, the cross-sectional area of the flow path 100 in the outer peripheral portion may be made different from that in the central portion, or the length of the side parallel to the mounting surface 11 in the shape of the flow path 100 may be increased. Further, the interval between the side parallel to the mounting surface 11 of the flow path 100 and the mounting surface 11 may be made different between the central portion and the outer peripheral portion.

[0054] Using FIG. 7, the dimensional relationships of the wafer holder 1 of the present embodiment will be described. Referring to FIG. 7, the thickness of the first plate 10 is L1, the diameter of the main body 15 is D1, and the thickness is L15. The thickness of the leg portion 13 of the first plate 10 is L13. The thickness of the second plate 20 is L2, and the diameter is D2. The cross section of the flow path 100 is a rectangle with a width W and a height H. The thickness direction interval between the upper end surface of the flow path 100 and the upper surface 11 of the first plate 10 is LA. The thickness direction interval between the lower end surface of the flow path 100 and the lower surface 12 of the main body 15 of the first plate 10 is LB.

[0055] The interval LA between the upper end surface of the flow path 100 and the upper surface 11 of the first plate 10 is preferably 2 mm or more and 45 mm or less. If LA is less than 2 mm, there will be a problem with the rigidity of the first plate 10. If LA exceeds 45 mm, the cooling capacity cannot be exerted, and the temperature in the plane of the upper surface 11, which is the mounting surface, tends to be non-uniform. The interval LA is more preferably 2 mm or more and 10 mm or less. The interval LB between the lower end surface of the flow path 100 and the lower surface 12 is preferably 2 mm or more and 33 mm or less. If LB is less than 2 mm, there will be a problem with the rigidity of the first plate 10. If LB exceeds 33 mm, the heat capacity of the first plate 10 becomes too large. The interval LB is more preferably 2 mm or more and 10 mm or less. The interval between the upper surface 11 and the lower end surface 13a of the leg portion 13, that is, the thickness L1 of the first plate 10, is preferably 16 mm or more and 80 mm or less. If L1 is less than 16 mm, the overall rigidity of the first plate 10 is inferior, and the first plate 10 is likely to bend. Also, if L1 exceeds 80 mm, the heat capacity of the first plate 10 becomes large, which has an adverse effect on the heating and cooling capabilities and time constants. The thickness L2 of the second plate 20 is preferably 0.5 mm or more and 50 mm or less. If L2 is less than 0.5 mm, even if the second plate 20 is made of highly rigid ceramics or the like, the effect of supporting the first plate 10 and increasing the overall rigidity of the wafer holder cannot be sufficiently exerted. Also, if L2 exceeds 50 mm, the overall thickness of the wafer holder becomes excessively large and the heat capacity also becomes too large.

[0056] [Bending of Wafer Holder] [Bending Rate] The deflection and deflection ratio of the wafer holder 1 will be described. A force may act on the mounting surface 11 side of the wafer holder 1. When a probe for inspection is pressed against the wafer S in a state where the wafer S is placed, a downward force is applied to the wafer holder 1. In addition, when inspecting or processing the wafer S in a pressurized environment or a decompressed environment for the wafer S itself, a force due to the pressure difference between the mounting surface 11 side and the lower surface 22 side of the wafer holder 1 is applied.

[0057] FIG. 8 is a diagram for explaining the relationship between the force applied to the wafer holder 1 and the deflection. FIG. 8 is a diagram in which a force F from above to below is applied to the mounting surface 11. A support 60 is provided to support the wafer holder 1. The support 60 is, for example, a cylindrical column. The support 60 is arranged such that, for example, an annular end face of the support 60 directly contacts or contacts via another member at the outer peripheral portion of the lower surface 12 of the first plate 10. When the force F is applied to the mounting surface 11, the first plate 10 and the second plate 20 deflect into a shape in which the central portion bulges downward. When a negative force is applied depending on the usage form, that is, when the force F is applied upward in the figure, the deflection becomes a shape that bulges upward. The absolute value of the displacement amount in the direction perpendicular to the mounting surface 11 generated between the central portion and the peripheral portion of the mounting surface 11 is defined as the deflection amount D. The deflection amount D varies depending on the size of the wafer holder 1 supported by the support 60. That is, even if the same force F is applied to the wafer holder 1 made of the same material, the deflection amount D will be different if the size, thickness, arrangement of the leg portions 13, etc. of the wafer holder 1 are different. Therefore, the value obtained by dividing the deflection amount D by the diameter of the portion of the wafer holder 1 supported by the support 60 is defined as the deflection ratio. The deflection ratio is a dimensionless quantity.

[0058] In the present disclosure, in order to obtain the required rigidity of the wafer holder 1 while suppressing heat transfer between the first plate 10 and the second plate 20, the leg portion 13 is provided. By the leg portion 13, a heat insulation space can be provided between the lower surface 12 side of the first plate 10 and the heater 30 and the second plate 20. By providing the leg portion 13, the rigidity of the wafer holder 1 can be increased as compared with the configuration without the leg portion 13. As a result, while securing the thickness of the first plate 10 necessary to obtain rigidity, the heater 30 can be disposed closer to the mounting surface 11, so that the heat uniformity in the mounting surface 11 can be enhanced. Also, the deflection ratio of the wafer holder 1 under the condition that a force F of 0.1 MPa acts on the entire mounting surface 11 can be made 0.3×10 -3 or less. More preferably, the deflection ratio is 0.2×10 -3 or less.

[0059] The rigidity of the wafer holder 1 is affected by the Young's modulus of the entire wafer holder and the thickness of each plate. When the flow path 100 is provided inside, the portion where the flow path 100 exists is more likely to deflect than other portions. Therefore, it is preferable to consider excluding the flow path 100 from the rigidity design. Let LT be the thickness obtained by subtracting the height of the flow path from the thickness of the entire wafer holder. Referring to FIG. 7, the thickness of the entire wafer holder is L1 + L2. Also, the thickness of the wafer holder excluding the height of the flow path is LT = L1 + L2 - H. Here, when the material of the heater 30 is a resin sheet and a heating element circuit and the thickness of the heater 30 is thinner than that of the other plates, the thickness of the heater 30 may be considered negligible. This is because the contribution of the heater 30 to the rigidity of the wafer holder 1 is extremely small.

[0060] <Average Young's modulus> Define the average Young's modulus of the wafer holder 1 by the following formula. Here, let the Young's modulus of the material of the main body 15 of the first plate 10 be Y15, the Young's modulus of the material of the leg portion 13 of the first plate 10 be Y13, and the Young's modulus of the material of the second plate 20 be Y2. Also, referring to FIG. 7 again, use the thickness L15 of the main body 15 of the first plate 10, the thickness L13 of the leg portion 13, the thickness L2 of the second plate 20, and the height H of the flow path 100 for the calculation. Also, let the area ratio of the leg portion 13 in the first plate 10 be α. Average Young's modulus = (L15 - H)×Y15 + L13×Y13×α + L2×Y2

[0061] In order to reduce the deflection of the mounting surface 11 to a certain level or less, it is preferable to make the value of the product of the average Young's modulus (kN / mm 2 ) and the thickness LT (mm) 1800 kN / mm or more. By making the value of the product of the average Young's modulus and LT 1800 kN / mm or more, the deflection rate when a force F of 0.1 MPa is applied to the mounting surface 11 can be made 0.3×10 -3 or less. Furthermore, by making the value of the product of the average Young's modulus and LT 2700 kN / mm or more, the deflection rate when a force F of 0.1 MPa is applied to the mounting surface 11 can be made 0.2×10 -3 or less. Although there is no upper limit to the value of the product of the average Young's modulus and LT, considering suppressing the overall thickness of the wafer holder to a certain level or less and the Young's modulus of the available materials, the upper limit is 10000 kN / mm or less, preferably about 8000 kN / mm or less.

[0062] <Effect of flow path width> Also, when the distance between the upper end surface of the flow path 100 and the placement surface 11 is small and the width of the flow path 100 is wide, the wafer holder 1 is likely to bend. The reason for the easy bending is that there is a wide space immediately below the placement surface 11. When the distance from the placement surface 11 to the upper end surface of the flow path 100 is represented as LA (mm) and the width of the flow path 100 is represented as W (mm), by setting LA / W ≥ 3.0, the bending can be further reduced. In order to reduce the amount of bending, it is more preferably LA / W ≥ 5.0, and even more preferably LA / W ≥ 6.0. To increase LA / W, it is advisable to increase LA or decrease W. However, if LA is increased too much, the distance between the flow path 100 and the placement surface 11 becomes large, and the cooling efficiency decreases. Also, if W is decreased too much, the cross-sectional area of the flow path 100 decreases, and the resistance of the refrigerant flow increases, resulting in a decrease in cooling efficiency. Therefore, the upper limit of LA / W is preferably 30, and more preferably 20. Even more preferably, LA / W is 10 or less.

[0063] [Semiconductor manufacturing apparatus] The basic configuration of a semiconductor manufacturing apparatus including the wafer holder 1 of the above embodiment is schematically shown in FIGS. 9 and 10. The wafer holder 1 is placed in the chamber 70. The wafer holder 1 is supported from the lower surface side by a support 60 provided in the chamber 70. The support 60 and the wafer holder 1 are hermetically joined. Here, the wafer holder 1 preferably has a heat insulating material 40 that can be interposed between it and the support 60. By providing the heat insulating material 40, the inflow of heat from the support 60 and the outflow of heat to the support 60 can be suppressed. The efficiency of cooling using the flow path 100 and heating by the heater 30 can be increased by heat insulation. Also, heat insulation can enhance the temperature uniformity of the placement surface 11. The material of the heat insulating material 40 is not particularly limited as long as it has environmental resistance in the used state. For the heat insulating material 40, PTFE (polytetrafluoroethylene), polyetheretherketone (PEEK), alumina, mullite, etc. are preferably used.

[0064] When hermetically joining the wafer holder 1 and the support 60, a sealing member such as an O-ring may be used together with the heat insulating material 40 or so as to also serve as the heat insulating material 40. FIG. 9 shows an example in which the lower surface side of the first plate 10 of the wafer holder 1 is supported by the support 60. FIG. 10 shows an example in which the lower surface side of the second plate 20 which is the lowermost surface of the wafer holder 1 is supported by the support 60. In both cases, the wafer holder 1 is connected to the support 60 and the chamber 70 via the heat insulating material 40. The structure of the wafer holder 1 is not limited to the figure, and other configurations described by the present disclosure can be applied. Although not shown, the semiconductor manufacturing apparatus can include other structures used for processing a semiconductor wafer. Structures related to introduction and discharge of gas into the chamber 70, a shower head, a structure related to plasma generation, etc. are provided.

[0065] The shape of the support 60 in this example is cylindrical. The outer diameter of the support 60 is preferably the same as or slightly smaller than the outer diameter of the wafer holder 1. As the material of the support 60, ceramics or a composite of ceramics having high rigidity, like other plates, is preferably used.

[0066] In the semiconductor manufacturing apparatus shown in FIG. 9 or FIG. 10, necessary gas is introduced into the chamber 70 or gas is discharged to maintain a vacuum. The portion on the lower surface side of the wafer holder 1 and surrounded by the support 60 is normally at atmospheric pressure. For example, when the inside of the chamber 70 is maintained in a vacuum, a pressure difference equivalent to atmospheric pressure is generated between the upper and lower surfaces of the wafer holder 1. Also in this case, as described by the present disclosure, the wafer holder 1 may be deformed. Therefore, as described above, it is effective to use the wafer holder 1 having a rigidity that is not easily deformed even in a configuration having a cooling mechanism inside.

[0067] It should be considered that all aspects of the embodiments disclosed this time are illustrative and not restrictive. The present invention is not limited to these examples, but is indicated by the claims, and is intended to include the meaning equivalent to the claims and all modifications within the scope.

[0068] <Supplementary Note> The present disclosure includes the following embodiments.

[0069] (Supplementary Note 1) A wafer holder including a first plate, a second plate, and a heater, wherein the upper surface of the first plate is a placement surface for a wafer, The first plate includes a disk-shaped main body portion having a refrigerant flow path inside and a leg portion protruding from the lower surface of the main body portion, The heater is provided at a position in contact with the lower surface or inside the first plate, The second plate is provided so as to be in contact with the lower end surface of the leg portion, The distance between the upper end surface of the flow path and the upper surface is 2 mm or more and 45 mm or less, The distance between the lower end surface of the flow path and the lower surface is 2 mm or more and 33 mm or less, The distance between the upper surface and the lower end surface is 16 mm or more and 80 mm or less, The cross section of the flow path in the direction perpendicular to the upper surface is a rectangle having sides parallel to the upper surface, A wafer holder in which the distance LA between the upper surface and the flow path and the width W of the flow path satisfy the relationship LA / W≥3.0.

[0070] (Supplementary Note 2) A wafer holder including a first plate, a second plate, and a heater, wherein the upper surface of the first plate is a placement surface for a wafer, The first plate includes a disk-shaped main body portion having a refrigerant flow path inside and a leg portion protruding from the lower surface of the main body portion, The heater is provided at a position in contact with the lower surface or inside the first plate, The second plate is provided so as to be in contact with the lower end surface of the leg portion, The distance between the upper end surface of the flow path and the upper surface is 2 mm or more and 45 mm or less, The distance between the lower end surface of the flow path and the lower surface is 2 mm or more and 33 mm or less, The distance between the upper surface and the lower end surface is 16 mm or more and 80 mm or less, The cross-section of the flow path in the direction perpendicular to the placement surface is a rectangle having sides parallel to the upper surface. A wafer holder, wherein the value obtained by multiplying the value LT (mm) obtained by subtracting the height of the flow path from the thickness of the entire wafer holder by the average Young's modulus (kN / mm 2 ) of the wafer holder is 1800 kN / mm or more.

[0071] (Appendix 3) A wafer holder including a first plate, a second plate, and a heater, wherein the upper surface of the first plate serves as a placement surface for the wafer. The first plate includes a disk-shaped main body portion having a refrigerant flow path therein and a leg portion protruding from the lower surface of the main body portion. The heater is provided at a position in contact with the lower surface or inside the first plate. The second plate is provided so as to be in contact with the lower end surface of the leg portion. Supporting the outer peripheral portion of the lower surface, in a test of applying a force of 0.1 MPa to the upper surface, the deflection ratio of the placement surface is 0.3×10 -3 or less. A wafer holder.

Explanation of Reference Numerals

[0072] 1 Wafer holder 10 First plate 11 Placement surface (upper surface of the first plate) 12 Lower surface of the first plate 13 Leg portion 13a Lower end surface 14 Space 15 Main body portion 20 Second plate 21 Upper surface of the second plate 22 Lower surface of the second plate 30 Heater 31 First resin layer 32 Heater circuit layer 33 Second resin layer 40 Heat insulating material 50 Fastening member 60 Support 70 Chamber 100 Flow path 101 Inlet 102 Outlet S Wafer

Claims

1. A wafer holder comprising a first plate, a second plate, and a heater, wherein an upper surface of the first plate serves as a placement surface for a wafer, the first plate includes a disk-shaped main body portion having a refrigerant flow path therein and a leg portion protruding from a lower surface of the main body portion, the heater is provided at a position in contact with the lower surface or inside the first plate, the second plate is provided so as to be in contact with a lower end surface of the leg portion, a distance between an upper end surface of the flow path and the upper surface is 2 mm or more and 45 mm or less, a distance between a lower end surface of the flow path and the lower surface is 2 mm or more and 33 mm or less, a distance between the upper surface and the lower end surface is 16 mm or more and 80 mm or less, in a cross-section of the first plate that is perpendicular to the upper surface and passes through the center of the first plate, the flow path is configured such that a cooling capacity of an outer peripheral portion of the first plate is higher than a cooling capacity of a central portion of the first plate, the central portion is a circular region having an outer edge defined by a circle with a radius of 90% of the radius of the wafer centered on the center of the wafer placed on the upper surface, the outer peripheral portion is an annular region having an inner peripheral edge defined by the outer edge and an outer peripheral edge defined by a concentric circle with a radius of 99% of the radius of the first plate, wafer holder.

2. A wafer holder comprising a first plate, a second plate, and a heater, wherein an upper surface of the first plate serves as a placement surface for a wafer, the first plate includes a disk-shaped main body portion having a refrigerant flow path therein and a leg portion protruding from a lower surface of the main body portion, the heater is provided at a position in contact with the lower surface or inside the first plate, the second plate is provided so as to be in contact with a lower end surface of the leg portion, a distance between an upper end surface of the flow path and the upper surface is 2 mm or more and 45 mm or less, a distance between a lower end surface of the flow path and the lower surface is 2 mm or more and 33 mm or less, a distance between the upper surface and the lower end surface is 16 mm or more and 80 mm or less, further comprising a heat insulating material interposed between an outer peripheral portion of the lower surface and a support for supporting the wafer holder, wafer holder.

3. In a cross-section of the first plate that passes through the center of the first plate and is perpendicular to the upper surface, a density of the number of the flow paths in the outer peripheral portion is higher than a density of the number of the flow paths in the central portion, the wafer holder according to Claim 1.

4. Further comprising a heat insulating material interposed between an outer peripheral portion of the lower surface and a support for supporting the wafer holder, The wafer holder according to claim 1 or claim 3.

5. The distance between the upper end surface of the flow path and the upper surface is 2 mm or more and 10 mm or less, The distance between the lower end surface of the flow path and the lower surface is 2 mm or more and 10 mm or less. The wafer holder according to any one of claims 1 to 4.

6. The ratio of the area of the leg portion to the total area of the lower surface on the lower surface is 5% or more and 50% or less. The wafer holder according to any one of claims 1 to 5.

7. The leg portion has a plurality of straight portions extending radially from the center of the first plate in a plan view of the first plate. The wafer holder according to any one of claims 1 to 6.

8. The leg portion has an arc portion concentric with the center of the first plate in a plan view of the first plate. The wafer holder according to any one of claims 1 to 7.

9. The thickness of the second plate is 0.5 mm or more and 50 mm or less. The wafer holder according to any one of claims 1 to 8.

10. The material of the first plate is any one of copper, copper alloy, aluminum, or aluminum alloy. The wafer holder according to any one of claims 1 to 9.

11. The material of the first plate is ceramics or a composite of ceramics. The wafer holder according to any one of claims 1 to 9.

12. The material of the second plate is ceramics or a composite of ceramics. The wafer holder according to any one of claims 1 to 11.

13. The heater is provided in contact with the lower surface. The heater is a laminate of a first resin layer, a heater circuit layer, and a second resin layer. The wafer holder according to any one of claims 1 to 12.

Images