Holding device

Abstract

This invention provides a technology to improve the uniformity of heat distribution on the mounting surface of a holding device. [Solution] The holding device comprises a plate-shaped part having a mounting surface on which an object is placed, a resistance heating element disposed inside the plate-shaped part, and a plurality of via conductors disposed inside the plate-shaped part and connected to the resistance heating element, wherein the resistance heating element has a heating wire and a plurality of pads connected to the heating wire, and at least one of the plurality of pads is connected to the via conductor at a position different from each of the ends of the heating wire.

Description

Technical Field

[0001] The present invention relates to a holding device.

Background Art

[0002] Conventionally, a holding device including a resistance heating element for heating an object placed on a placement surface has been known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, even with the prior art such as Patent Document 1, there is still room for improvement in the technology for improving the heat uniformity of the placement surface in the holding device.

[0005] An object of the present invention is to provide a technology for improving the heat uniformity of a placement surface in a holding device.

Means for Solving the Problems

[0006] The present invention has been made to solve at least a part of the above problems and can be realized in the following forms.

[0007] (1) According to one embodiment of the present invention, a holding device is provided. The holding device comprises a plate-shaped portion having a mounting surface on which an object is placed, a resistance heating element disposed inside the plate-shaped portion, and a plurality of via conductors disposed inside the plate-shaped portion and connected to the resistance heating element, wherein the resistance heating element has a heating wire and a plurality of pads connected to the heating wire, and at least one of the plurality of pads is connected to the via conductor at a position different from each of the ends of the heating wire.

[0008] In this configuration, the resistive heating element has a heating wire and a plurality of pads connected to the heating wire. In the resistive heating element, at least one of the plurality of pads connected to the heating wire is connected to a via conductor at a different position from each of the ends of the heating wire. The resistive heating element generates heat corresponding to the magnitude of the electrical resistance of the heating wire between the two pads connected to the via conductor. That is, by adjusting the position of the pads connected to the via conductor, the electrical resistance that determines the amount of heat generated by the resistive heating element can be easily adjusted. Therefore, the uniformity of heating on the mounting surface can be improved.

[0009] (2) In the above-described holding device, the resistance heating element may have three or more pads, and the three or more pads may be connected to the heating wire while being spaced apart from each other. With this configuration, since the three or more pads connected to the heating wire are spaced apart from each other, the electrical resistance of the resistance heating element can be adjusted by selecting two pads from the three or more pads to be connected to the via conductor. Therefore, the uniformity of the heat distribution on the mounting surface can be easily improved.

[0010] (3) In the above-described holding device, the first pad among the three or more pads is connected to one end of the heating wire, the remaining pads among the three or more pads, excluding the first pad, are connected to the heating wire on the other end side of the heating wire from the center of the heating wire, and the first pad and the second pad among the remaining pads are each connected to the via conductor. With this configuration, the first pad connected to one end of the heating wire is connected to the via conductor. The remaining pads among the three or more pads, excluding the first pad, are connected to the heating wire on the other end side of the heating wire from the center of the heating wire, and the second pad among the remaining pads is connected to another via conductor. This makes it easy to adjust the electrical resistance of the resistive heating element when it is heating up by selecting the second pad from among the remaining pads, while keeping the electrical resistance of the resistive heating element at or above a value corresponding to half the length of the heating wire. Therefore, the uniformity of the heat distribution on the mounting surface can be further easily improved.

[0011] (4) In the above-described holding device, the first pad among the three or more pads is connected to one end of the heating wire, and the remaining pads among the three or more pads, excluding the first pad, are connected to the heating wire within a length of 10% or less of the length of the heating wire from the other end of the heating wire, and the first pad and the second pad among the remaining pads are each connected to the via conductor. With this configuration, the remaining pads, excluding the first pad connected to the via conductor, are arranged biased toward the other end of the heating wire. Since the remaining pads, including the second pad connected to another via conductor, are connected to the heating wire within a length of 10% or less of the length of the heating wire from the other end of the heating wire, the magnitude of the electrical resistance of the resistive heating element when it generates heat can be adjusted with high precision to be equal to or greater than the value corresponding to 90% of the length of the heating wire. Therefore, the uniformity of the heat distribution on the mounting surface can be further improved.

[0012] (5) In the above-described form of the holding device, the resistance heating element is arranged facing the mounting surface, and in a plan view of the mounting surface of the plate-shaped portion, the first pad of the three or more pads is connected to the heating wire at the outer periphery of the area where the resistance heating element is placed, and the remaining pads of the three or more pads, excluding the first pad, are connected to the heating wire inward of the area where the resistance heating element is placed. With this configuration, the first pad connected to the via conductor is connected to the heating wire at the outer periphery of the area where the resistance heating element is placed. The remaining pads, including the second pad connected to another via conductor, are connected to the heating wire inward of the area where the resistance heating element is placed. A portion of the heating wire from the point where the second pad is connected to the other end of the heating wire does not generate heat because no current flows through it even when the resistance heating element is generating heat, but because it is located inward of the area where the resistance heating element is placed, it does not significantly affect the temperature distribution in the entire area where the resistance heating element is placed. This makes it easy to adjust the electrical resistance of the resistance heating element for the purpose of improving the uniformity of the mounting surface.

[0013] Furthermore, the present invention can be realized in various forms, for example, in the form of a method for manufacturing a holding device, a system including a holding device, a method for controlling these devices and systems, a computer program that causes these devices and systems to perform the holding of an object, a server device for distributing the computer program, a non-temporary storage medium storing the computer program, and so on. [Brief explanation of the drawing]

[0014] [Figure 1] This is a perspective view of the holding device of the first embodiment. [Figure 2] This is a cross-sectional view of the holding device according to the first embodiment. [Figure 3] This is a schematic diagram of the external appearance of the holding device of the first embodiment. [Figure 4] This is an enlarged view of section A in Figure 3. [Figure 5]This is a schematic diagram of the resistance heating element included in the holding device of the first embodiment. [Figure 6] This is a schematic diagram of the resistance heating element included in the holding device of the second embodiment. [Figure 7] This is a schematic diagram of the resistance heating element included in the holding device of the third embodiment. [Modes for carrying out the invention]

[0015] <First Embodiment> Figure 1 is a perspective view of the holding device 1 of this embodiment. Figure 2 is a cross-sectional view of the holding device 1 of this embodiment. The holding device 1 of this embodiment is an electrostatic chuck that holds an object, such as a wafer W, by electrostatic attraction. The electrostatic chuck is used, for example, as a table on which a wafer W (object) is placed in a chamber. The holding device 1 comprises a ceramic part 10, a base part 20, and a joint part 30. In the holding device 1 of this embodiment, as shown in Figure 1, the ceramic part 10, the joint part 30, and the base part 20 are stacked in that order. For convenience, Figures 1 and 2 show the stacking direction of the ceramic part 10, the joint part 30, and the base part 20 as the z-axis, with the x-axis intersecting perpendicular to the z-axis and the y-axis intersecting perpendicular to the z-axis and x-axis.

[0016] The ceramic part 10 is a component having a roughly disc shape, with ceramic as its main component. Here, "main component" means the component with the highest proportion. In this embodiment, the ceramic part 10 has alumina (Al2O3) as its main component. The ceramic part 10 comprises a plate-shaped part 11, a resistance heating element 12, a resistance thermometer 13, a plurality of via conductors 14, 15, and a chuck electrode 16.

[0017] The plate-like part 11 is a component made of ceramic and having a substantially disc shape. The plate-like part 11 of the present embodiment is made of alumina and has substantially the same shape as the ceramic part 10. Note that the material forming the plate-like part 11 may be other ceramic materials such as aluminum nitride (AlN) and silicon carbide (SiC). The plate-like part 11 has a mounting surface 11a on which the wafer W is placed.

[0018] The resistance heating element 12 is disposed inside the plate-like part 11. The holding device 1 of the present embodiment includes a plurality of resistance heating elements 12. The resistance heating element 12 is formed of a conductive material. In the holding device of the present embodiment, the plurality of resistance heating elements 12 are arranged so as to face the mounting surface 11a of the plate-like part 11 as shown in FIG. 2.

[0019] FIG. 3 is a schematic external view of the holding device 1 of the present embodiment. FIG. 4 is an enlarged view of part A in FIG. 3. FIG. 3 is a schematic view showing the external appearance of the holding device 1 when viewed from the positive side in the z-axis direction. In the holding device 1 of the present embodiment, the surface 10a of the ceramic part 10 on which the mounting surface 11a is formed is virtually divided into a plurality of segments SE. Specifically, a plurality of circular boundary lines BL1 (shown as chain lines BL1 in FIG. 3) having a circular shape centered on the central axis C1 of the holding device 1 are set on the surface 10a of the ceramic part 10, and a plurality of virtual annular regions are set between two adjacent boundary lines BL1. Each of the plurality of annular regions is divided into a plurality of segments SE by a plurality of boundary lines BL2 (shown as two-dot chain lines BL2 in FIG. 3). The plurality of resistance heating elements 12 are arranged one by one in each of the plurality of segments SE as shown in FIG. 4. Details of the resistance heating element 12 will be described later.

[0020] The via conductor 14 is disposed inside the plate-like portion 11 and connected to the resistive heating element 12. The via conductor 14 is connected to a driver electrode 14a disposed inside the plate-like portion 11, and the driver electrode 14a is connected to a power supply terminal 14b. Thereby, power is supplied to the resistive heating element 12 from an external power source via the power supply terminal 14b, the driver electrode 14a, and the via conductor 14. When power is supplied, the resistive heating element 12 generates heat capable of heating the wafer W placed on the placement surface 11a.

[0021] The temperature sensor 13 is disposed inside the plate-like portion 11. The holding device 1 of the present embodiment includes a plurality of temperature sensors 13. The temperature sensor 13 is formed of platinum, nickel, or the like corresponding to the operating temperature range of the holding device 1. The plurality of temperature sensors 13 are arranged inside the plate-like portion 11 so as to be located in the negative z-axis direction of each of the plurality of resistive heating elements 12 so as to correspond to each of the plurality of resistive heating elements 12. The temperature sensor 13 is used to detect the temperature near the corresponding resistive heating element 12. The temperature near the resistive heating element 12 detected using the temperature sensor 13 is used to adjust the heat generation amount of the resistive heating element 12.

[0022] The via conductor 15 is disposed inside the plate-like portion 11 and connected to the temperature sensor 13. The via conductor 15 is connected to a driver electrode 15a disposed inside the plate-like portion 11, and the driver electrode 15a is connected to a power supply terminal 15b. Thereby, a current of a constant value is supplied to the temperature sensor 13 from an external power source via the power supply terminal 15b, the driver electrode 15a, and the via conductor 15.

[0023] The chuck electrode 16 is located inside the plate-shaped portion 11. The chuck electrode 16 is made of a conductive material such as tungsten (W), molybdenum (Mo), or platinum (Pt). The chuck electrode 16 is connected to an external power source via a power supply terminal 16a. When powered by an external power source, the chuck electrode 16 generates an electrostatic attraction force capable of adsorbing and holding the wafer W to the mounting surface 11a of the plate-shaped portion 11. In this embodiment, as shown in Figure 2, the chuck electrode 16 is located further from the mounting surface 11a than the resistance heating element 12 and the resistance thermometer 13, but the positional relationship between the resistance heating element 12, the resistance thermometer 13, and the chuck electrode 16 inside the plate-shaped portion 11 is not limited to this. In addition to the resistance heating element 12, the resistance thermometer 13, and the chuck electrode 16, high-frequency electrodes and the like may also be located inside the ceramic portion 10.

[0024] The base portion 20 is a substantially disc-shaped component mainly composed of a metal such as aluminum or an aluminum alloy, a metal matrix composite such as an Al-SiC composite material, or a ceramic such as silicon carbide (SiC). In this embodiment, the base portion 20 is made of aluminum. In this embodiment, the base portion 20 is larger than the ceramic portion 10. For example, if the diameter of the ceramic portion 10 is 300 mm, the diameter of the base portion 20 will be 340 mm. However, the size relationship between the ceramic portion 10 and the base portion 20 is not limited to this. They may be the same size.

[0025] Multiple refrigerant channels 21 are formed inside the base portion 20. A refrigerant such as a fluorine-based inert liquid or water flows through the refrigerant channels 21. As a result, the base portion 20 is cooled, and the ceramic portion 10 is cooled via the joint portion 30.

[0026] The joint 30 joins the ceramic part 10 and the base part 20. The joint 30 is, for example, a bonding sheet containing a silicone-based organic adhesive, an inorganic adhesive, or an Al-based metal adhesive. The joint 30 should preferably have high adhesive strength to both the ceramic part 10 and the base part 20, as well as high pressure resistance and high thermal conductivity.

[0027] Figure 5 is a schematic diagram of the resistance heating element 12 provided in the holding device 1 of this embodiment. Next, the features of the holding device 1 of this embodiment will be described. The resistance heating element 12 provided in the holding device 1 has a heating wire 121 and a plurality of pads 122 connected to the heating wire 121. The heating wire 121 is made of a conductive material with relatively high electrical resistance, and when current flows through it, it generates a heat amount corresponding to the magnitude of the electrical resistance. In this embodiment, the heating wire 121 has a plurality of bends, for example, bends 121a, 121b, 121c, 121d, 121e, 121f, etc., so that the temperature distribution is small throughout the inside of one segment SE. For convenience, in Figure 5, the outer shape of the segment SE on which the resistance heating element 12 is arranged is shown by the dashed line BL. The shape of the heating wire 121 is not limited to the shape shown in Figure 5.

[0028] Multiple pads 122 connect the heating wire 121 to the via conductor 14. The resistive heating element 12 shown in Figure 5 has six pads 122a, 122b, 122c, 122d, 122e, and 122f. In this embodiment, each of the six pads 122a, 122b, 122c, 122d, 122e, and 122f is connected to the heating wire 121 while being spaced apart from each other. Note that the number of pads 122 in the resistive heating element 12 is not limited to six. At least two are sufficient.

[0029] In the resistive heating element 12, at least one of the multiple pads 122 is connected to a via conductor 14 at a position different from each of the two ends Eg1 and Eg2 of the heating wire 121. Specifically, pad 122a of the six pads 122 is connected to one end Eg1 of the heating wire 121. Pad 122a is connected to one of the two via conductors 14 that supply power to the heating wire 121. Each of the six pads 122b, 122c, 122d, 122e, and 122f is connected to the heating wire 121 at a position different from each of the two ends Eg1 and Eg2 of the heating wire 121, i.e., between the two ends Eg1 and Eg2 of the heating wire 121. Of the pads 122b, 122c, 122d, 122e, and 122f, pad 122e is connected to a via conductor 14 other than the via conductor 14 connected to pad 122a, which supplies power to the heating wire 121. When power is supplied to the resistive heating element 12 shown in Figure 5 via the two via conductors 14, current flows through the heating wire 121 between pads 122a and 122e, generating an amount of heat corresponding to the electrical resistance of the heating wire 121 between pads 122a and 122e. In other words, by selecting the pads to which the two via conductors 14 are connected, the amount of electrical resistance of the resistive heating element 12 when it heats up can be adjusted. Pad 122a corresponds to the "first pad" in the claims. Pad 122e corresponds to the "second pad" in the claims.

[0030] In this embodiment, of the six pads 122, pads 122b, 122c, 122d, 122e, and 122f, excluding pad 122a, are each connected to the heating wire 121 at a point on the other end Eg2 side of the heating wire 121, relative to the center C121 of the heating wire 121, in terms of length. That is, the positions where pads 122b, 122c, 122d, 122e, and 122f are arranged on the heating wire 121 are biased toward the other end Eg2 side of the heating wire 121, relative to the center C121 of the heating wire 121, in terms of the length of the heating wire 121 itself.

[0031] Next, the manufacturing method of the holding device 1 will be described. In the manufacturing method of the holding device 1, the ceramic part 10 and the base part 20 are manufactured separately, and the separately manufactured ceramic part 10 and base part 20 are joined together by a joint part 30.

[0032] In the manufacturing method for the ceramic part 10, first, a slurry for the green sheet and a metallization paste are prepared. The slurry for the green sheet is prepared by mixing a mixture containing, for example, alumina powder, an acrylic binder, a dispersant, and a plasticizer with an organic solvent using a ball mill. The metallization paste is prepared by mixing a mixture of alumina powder, an acrylic binder, and an organic solvent with conductive powder such as tungsten or molybdenum.

[0033] The prepared slurry for the green sheet is formed into a sheet using a casting device, and the resulting molded product is dried. This yields a green sheet. On a specific green sheet from among several green sheets, a portion that will become the resistance heating element 12 is printed using a metallizing paste, for example, by a screen printing device. The portion that will become the resistance heating element 12 includes a portion that will become the heating wire 121 and a portion that will become a plurality of pads 122.

[0034] In the manufacturing method of the holding device 1 of this embodiment, the thickness of the portion that will become the heating wire 121 printed by the screen printing device is measured, and the electrical resistance of the heating wire 121 is predicted. Using the predicted electrical resistance of the heating wire 121, two portions that will become pads 122 are selected from among the multiple portions that will become pads 122 already printed, so that the electrical resistance of the resistive heating element 12 is the electrical resistance that has been assumed in advance. In the manufacturing method of the holding device 1 of this embodiment, for each of the multiple portions that will become the resistive heating element 12, two portions that will become pads 122 are selected to be connected to each of the two via conductors 14. However, the manufacturing method of the portion that will become the resistive heating element 12 is not limited to this. The portions that will become pads 122 to be connected to the via conductors 14 may be printed using the predicted electrical resistance of the heating wire 121.

[0035] In the manufacturing method of the holding device 1 of this embodiment, a portion that will become the resistance thermometer 13 and the chuck electrode 16 is placed on a green sheet separate from the specific green sheet, and portions that will become the via conductors 14 and 15, the driver electrodes 14a and 15a, and the power supply terminals 14b, 15b, and 16a are formed. Subsequently, a laminate of green sheets is manufactured by laminating a specific green sheet on which the portion that will become the resistance heating element 12 is printed, and a green sheet on which the portion that will become the resistance thermometer 13 and the chuck electrode 16 is placed. The ceramic portion 10 is manufactured by firing the laminate of green sheets in an electric furnace. In the manufacturing method of the base portion 20, a plurality of metal plates are laminated, each having a portion that will become the refrigerant flow path 21 and portions on which the power supply terminals 14b, 15b, and 16a are placed. Note that the manufacturing methods of the ceramic portion 10 and the base portion 20 are not limited to these.

[0036] In the manufacturing method of the holding device 1, a bonding sheet, which will serve as the bonding portion 30, is placed on the surface of either the separately manufactured ceramic portion 10 or the base portion 20. The bonding sheet is processed with portions for which power supply terminals 14b, 15b, and 16a are arranged. For example, the bonding sheet is placed on the surface of the base portion 20, the bonding sheet is sandwiched between the ceramic portion 10 and the base portion 20, and the entire assembly is heated, thereby bonding the ceramic portion 10 and the base portion 20 by the bonding portion 30. The holding device 1 is manufactured by attaching the power supply terminals 14b, 15b, and 16a to the ceramic portion 10 and the base portion 20 that are bonded by the bonding portion 30. However, the manufacturing method of the holding device 1 is not limited to this.

[0037] In the manufacturing method of the holding device 1, as described above, the resistance heating element 12 is formed by printing on a green sheet using a screen printing device with metallized paste. In the method of forming the heating element using a screen printing device, a certain directionality may occur in the thickness of the heating element due to the direction of printing. For this reason, each of the resistance heating elements 12 placed in each of the multiple segments SE shown in Figure 3 may have a different electrical resistance.

[0038] In the holding device 1 of this embodiment, the resistive heating element 12 has a heating wire 121 and a plurality of pads 122 connected to the heating wire 121. In the manufacturing method of the holding device 1 of this embodiment, when manufacturing the ceramic part 10, two pads 122 connected to each of the two via conductors 14 are selected from among the plurality of pads 122 using the predicted result of the electrical resistance of the heating wire 121. This makes it possible to suppress variations in the electrical resistance of the plurality of resistive heating elements 12.

[0039] As described above, according to the holding device 1 of this embodiment, the resistive heating element 12 has a heating wire 121 and a plurality of pads 122 connected to the heating wire 121. In the resistive heating element 12, at least one of the plurality of pads 122 connected to the heating wire 121 is connected to the via conductor 14 at a position different from each of the two ends Eg1 and Eg2 of the heating wire 121. The resistive heating element 12 generates heat corresponding to the magnitude of the electrical resistance of the heating wire 121 between the two pads 122 connected to each of the two via conductors 14. That is, by selecting the pads 122 connected to the via conductors 14 and adjusting the length of the heating wire 121 through which the current flows, the electrical resistance that determines the amount of heat generated by the resistive heating element 12 can be easily adjusted. Therefore, the uniformity of the heat distribution on the mounting surface 11a can be improved.

[0040] Furthermore, according to the holding device 1 of this embodiment, since the multiple pads 122 connected to the heating wire 121 are spaced apart from each other, the electrical resistance of one resistive heating element 12 can be adjusted by selecting two pads 122 from among the multiple pads 122 to connect to each of the two via conductors 14. Therefore, the uniformity of the heat distribution on the mounting surface 11a can be easily improved.

[0041] Furthermore, according to the holding device 1 of this embodiment, the pad 122a connected to one end Eg1 of the heating wire 121 is connected to one of the two via conductors 14. Of the multiple pads 122, the remaining pads 122b, 122c, 122d, 122e, and 122f, excluding pad 122a, are each connected to the heating wire 121 on the other end Eg2 side of the heating wire 121, closer to the center C121 of the heating wire 121, and pad 122e is connected to the other via conductor 14 of the two via conductors 14. This makes it easy to adjust the electrical resistance of the resistive heating element 12 when it is heating up by selecting the pad 122 connected to the other via conductor 14 from the remaining pads 122b, 122c, 122d, 122e, and 122f, while keeping the electrical resistance of the resistive heating element 12 at or above a value corresponding to half the length of the heating wire 121. Therefore, the uniformity of the heat distribution on the mounting surface 11a can be further easily improved.

[0042] <Second Embodiment> Figure 6 is a schematic diagram of the resistance heating element provided in the holding device of the second embodiment. Compared with the holding device 1 of the first embodiment (Figure 2), the holding device of the second embodiment differs in that the position in which the pads are connected to the heating wires in the resistance heating element is different.

[0043] The holding device of the second embodiment comprises a ceramic part, a base part 20, and a joint part 30. The holding device of this embodiment is an electrostatic chuck that holds an object such as a wafer W by electrostatic attraction.

[0044] The ceramic part of the holding device of this embodiment comprises a plate-shaped portion 11, a resistance heating element 42, a resistance thermometer 13, a plurality of via conductors 14, 15, and a chuck electrode 16. The resistance heating element 42 is arranged inside the plate-shaped portion 11 so as to face the mounting surface 11a of the plate-shaped portion 11. The holding device of this embodiment comprises a plurality of resistance heating elements 42. The resistance heating element 42 is made of a conductive material with relatively high electrical resistance and generates heat when current flows through it.

[0045] The resistive heating element 42 has a heating wire 121 and a plurality of pads 422 connected to the heating wire 121. The plurality of pads 422 are formed to connect to the heating wire 121. The resistive heating element 42 shown in Figure 6 has six pads 422a, 422b, 422c, 422d, 422e, and 422f. Note that the number of pads 422 that the resistive heating element 42 has only needs to be at least two.

[0046] In the resistive heating element 42, at least one of the multiple pads 422 is connected to a via conductor 14 at a position different from each of the two ends Eg1 and Eg2 of the heating wire 121. Specifically, pad 422a of the six pads 422 is connected to one end Eg1 of the heating wire 121. Pad 422a is connected to one of the two via conductors 14 that supply power to the heating wire 121. Each of the six pads 422b, 422c, 422d, 422e, and 422f of the six pads 422 is connected to the heating wire 121 between one end Eg1 and the other end Eg2. Of the pads 422b, 422c, 422d, 422e, and 422f, pad 422d is connected to a via conductor 14 other than the via conductor 14 that supplies power to the heating wire 121, which is connected to pad 422a. When power is supplied to the resistive heating element 42 shown in Figure 6 via two via conductors 14, current flows through the heating wire 121 between pads 422a and 422d, generating an amount of heat corresponding to the electrical resistance of the heating wire 121 between pads 422a and 422d. In other words, by selecting the pads connected to the two via conductors 14, the electrical resistance of the resistive heating element 42 when it generates heat can be adjusted. Pad 422a corresponds to the "first pad" in the claims. Pad 422d corresponds to the "second pad" in the claims.

[0047] In this embodiment, each of the six pads 422b, 422c, 422d, 422e, and 422f, excluding pad 422a, is connected to the heating wire 121 within a range of 10% of the length of the heating wire 121 from the other end Eg2 of the heating wire 121. In Figure 6, the range of 10% of the length of the heating wire 121 from the other end Eg2 is shown by the dashed line R2. Also in Figure 6, the range of the heating wire 121 from one end Eg1 to 90% of the length of the heating wire 121 is shown by the solid line L1, and the range of the heating wire 121 from the other end Eg2 to 10% of the length of the heating wire 121 is shown by the dashed line L2. As shown in Figure 6, in the resistive heating element 42, the remaining pads 422b, 422c, 422d, 422e, and 422f, excluding pad 422a, are connected to the portion of the heating wire 121 indicated by the dashed line L2.

[0048] As described above, according to the holding device of this embodiment, the pads 422b, 422c, 422d, 422e, and 422f of the resistive heating element 42 are connected to the via conductor 14 at positions different from those of both ends Eg1 and Eg2 of the heating wire 121. This makes it easy to adjust the electrical resistance that determines the amount of heat generated by the resistive heating element 42 by selecting the pad 422 connected to the via conductor 14 and adjusting the length of the heating wire 121 through which the current flows. Therefore, the uniformity of the heat distribution on the mounting surface 11a can be improved.

[0049] Furthermore, according to the holding device of this embodiment, each of the remaining pads 422b, 422c, 422d, 422e, and 422f, excluding pad 422a which is connected to the via conductor 14, is positioned biased toward the other end Eg2 side of the heating wire 121. Each of the remaining pads 422b, 422c, 422d, 422e, and 422f, including pad 422d which is connected to a via conductor 14 different from the via conductor 14 connected to pad 422a, is connected to the heating wire 121 within a length range of 10% or less of the length of the heating wire 121 from the other end Eg2 of the heating wire 121. This makes it possible to adjust with high precision the magnitude of the electrical resistance of the resistive heating element 42 when it generates heat, while keeping it at or above a value corresponding to 90% of the length of the heating wire 121. Therefore, the uniformity of the heat distribution on the mounting surface 11a can be further improved.

[0050] <Third Embodiment> Figure 7 is a schematic diagram of the resistance heating element provided in the holding device of the third embodiment. Compared with the holding device 1 of the first embodiment (Figure 2), the holding device of the third embodiment differs in that the position in which the pads are connected to the heating wires in the resistance heating element is different.

[0051] The holding device of the third embodiment comprises a ceramic part, a base part 20, and a joint part 30. The holding device of this embodiment is an electrostatic chuck that holds an object, such as a wafer W, by electrostatic attraction.

[0052] The ceramic part of the holding device of this embodiment comprises a plate-shaped portion 11, a resistance heating element 52, a resistance thermometer 13, a plurality of via conductors 14, 15, and a chuck electrode 16. The resistance heating element 52 is arranged inside the plate-shaped portion 11 so as to face the mounting surface 11a of the plate-shaped portion 11. The holding device of this embodiment comprises a plurality of resistance heating elements 52. The resistance heating element 52 is made of a conductive material with relatively high electrical resistance and generates heat when current flows through it.

[0053] The resistive heating element 52 has a heating wire 521 and a plurality of pads 522 connected to the heating wire 521. The heating wire 521 is made of a conductive material and generates a heat amount corresponding to the magnitude of its electrical resistance when current flows through it. In this embodiment, the heating wire 521 has a plurality of bends, as shown in Figure 7, so that the temperature distribution is small throughout the inside of one segment SE. For convenience, the outline of the segment SE on which the resistive heating element 52 is arranged is shown by the dashed line BL in Figure 7. The plurality of pads 522 connect the heating wire 521 to the via conductor 14. The resistive heating element 52 shown in Figure 7 has five pads 522a, 522b, 522c, 522d, and 522e. Note that the number of pads 522 on the resistive heating element 52 is sufficient to be at least two.

[0054] In the resistive heating element 52, at least one of the multiple pads 522 is connected to a via conductor 14 at a position different from each of the two ends Eg1 and Eg2 of the heating wire 521. Specifically, pad 522a of the five pads 522 is connected to one end Eg1 of the heating wire 521. Pad 522a is connected to one of the two via conductors 14 that supply power to the heating wire 521. Each of the five pads 522b, 522c, 522d, and 522e is connected to the heating wire 521 between one end Eg1 and the other end Eg2. Of the pads 522b, 522c, 522d, and 522e, pad 522d is connected to a via conductor 14 other than the via conductor 14 that supplies power to the heating wire 521, which is connected to pad 522a. When power is supplied to the resistive heating element 52 shown in Figure 7 via two via conductors 14, current flows through the heating wire 521 between pads 522a and 522d, generating an amount of heat corresponding to the electrical resistance of the heating wire 521 between pads 522a and 522d. In other words, by selecting the pads connected to the two via conductors 14, the electrical resistance of the resistive heating element 52 when it generates heat can be adjusted. Pad 522a corresponds to the "first pad" in the claims. Pad 522d corresponds to the "second pad" in the claims.

[0055] In the resistive heating element 52, in a plan view of the mounting surface 11a of the plate-shaped portion 11, pad 522a of the plurality of pads 522 is connected to the heating wire 521 at the outer periphery of the area where the resistive heating element 52 is placed, while the remaining pads 522b, 522c, 522d, and 522e of the plurality of pads 522, excluding pad 522a, are connected to the heating wire 521 inward from pad 522a within the area where the resistive heating element 52 is placed. In other words, in the resistive heating element 52, in a plan view of the mounting surface 11a of the plate-shaped portion 11, pads 522b, 522c, 522d, and 522e are located inward from pad 522a within the area where the resistive heating element 52 is placed.

[0056] Here, we will specifically explain the positional relationship between pads 522b, 522c, 522d, and 522e and pad 522a in the resistive heating element 52. In the resistive heating element 52 shown in Figure 7, the region R52 is defined by the outline OL52, which passes through the outermost part of the heating wire 521 and is set to have the largest area. Next, the point where diagonals D1 and D2 intersect in the shape of region R52 is defined as the center C52 of region R52. If the shape of the region is a polygon with five or more sides, the centroid of the polygon is defined as the center of the region. Next, among the virtual circles centered at the center C52 of region R52, the virtual circle that circumscribes pad 522a is defined as virtual circle VC52. In region R521, which is between the outline OL52 and virtual circle VC52, pad 522 is connected to the heating wire 521 and is the "outer periphery of region R52 where the resistive heating element 52 is placed". On the other hand, in region R522 (the region with dot hatching in Figure 7) inside the virtual circle VC52 of region R52, pads 522b, 522c, 522d, and 522e are connected to the heating wire 521, and are "inside pad 522a in the region where the resistive heating element 52 is placed."

[0057] In the resistive heating element 52, as shown in Figure 7, pads 522b, 522c, 522d, and 522e are located inside pad 522a. As a result, when adjusting the electrical resistance of the resistive heating element 52, as shown in Figure 7, when pad 522d is connected to the via conductor 14, no current flows through the heating wire 521 from the point where pad 522d is connected to the other end Eg2, and therefore this part does not generate heat. However, since the part where no current flows is located inside the region R52 where the resistive heating element 52 is placed, it is possible to suppress deterioration of the temperature distribution in the region R52 where the resistive heating element 52 is placed.

[0058] Furthermore, in the resistive heating element 52, a portion of the heating wire 521 that does not carry current by selecting the pad to connect to the via conductor 14 is located in the inner region R522 of the virtual circle VC52, as shown in Figure 7. As a result, the portion of the heating wire 512 that does not carry current is located even further inward within the region R52 where the resistive heating element 52 is placed, thus further suppressing deterioration of the temperature distribution in the region R52 where the resistive heating element 52 is placed.

[0059] As described above, according to the holding device of this embodiment, the pads 522b, 522c, 522d, and 522e of the resistive heating element 52 are connected to the via conductor 14 at positions different from those of both ends Eg1 and Eg2 of the heating wire 521. This makes it easy to adjust the electrical resistance that determines the amount of heat generated by the resistive heating element 52 by selecting the pad 522 connected to the via conductor 14 and adjusting the length of the heating wire 521 through which the current flows. Therefore, the uniformity of the heat distribution on the mounting surface 11a can be improved.

[0060] Furthermore, according to the holding device of this embodiment, the pad 522a connected to the via conductor 14 is connected to the heating wire 121 in region R521 of region R52 where the resistive heating element 52 is placed. The remaining pads 522b, 522c, 522d, and 522e, including the pad 522d connected to another via conductor 14, are connected to the heating wire 121 inward from pad 522a in region R52 where the resistive heating element 52 is placed. A portion of the heating wire 521 from the point where pad 522d is connected to the other end Eg2 of the heating wire 521 does not generate heat because no current flows through it even when the resistive heating element 52 is generating heat. However, because it is located inward within region R52 where the resistive heating element 52 is placed, it does not significantly affect the temperature distribution in the entire region R52 where the resistive heating element 52 is placed. This makes it easy to adjust the electrical resistance of the resistive heating element 52 for the purpose of improving the uniformity of the heat distribution on the mounting surface 11a.

[0061] <Modified form of this embodiment> The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit, for example, the following modifications are also possible.

[0062] [Example 1] In the above embodiment, one of the multiple pads is connected to a via conductor at one end of the heating wire, and the remaining pads are connected to via conductors at positions different from each of the ends of the heating wire. The two pads connected to the via conductor may each be connected to the heating wire at positions different from each of the ends of the heating wire.

[0063] [Differentiation 2] In the first embodiment, some of the pads, specifically the remaining pads 122b, 122c, 122d, 122e, and 122f of the six pads 122 excluding pad 122a, are connected to the heating wire 121 on the other end Eg2 side of the heating wire 121, rather than at the center C121. In the second embodiment, each of the remaining pads 422b, 422c, 422d, 422e, and 422f of the six pads 422 excluding pad 422a, are connected to the heating wire 121 within a length of 10% or less of the length of the heating wire 121 from the other end Eg2 of the heating wire 121. In the third embodiment, in the area where the resistance heating element 52 is arranged in a plan view of the mounting surface 11a of the plate-shaped portion 11, pads 522b, 522c, 522d, and 522e are located inward from pad 522a. However, the positions in which the multiple pads connect to the heating element are not limited to this. The multiple pads may, for example, be connected to the heating element at equal intervals. In addition, among the multiple pads, the remaining pads, excluding the pad connected to the via conductor at one end of the heating element, may be connected to the heating element within a length of no more than 10% of the length of the heating element from the other end of the heating element, and inward from the pad connected to the via conductor at one end of the heating element, in the area where the resistance heating element is arranged in a plan view of the mounting surface 11a of the plate-shaped portion 11.

[0064] [Difference 3] In the above-described embodiment, the multiple resistance heating elements are arranged one at a time in each segment set on the surface of the ceramic part. The configuration in which the resistance heating elements are arranged is not limited to this.

[0065] [Differentiation Example 4] In the above-described embodiment, the holding device comprises a ceramic part mainly composed of ceramic, a base part made of metal, and a joint part that joins the ceramic part and the base part. The configuration of the holding device is not limited to this. The entire device may be made of ceramic, or it may be made of a composite material of ceramic and metal.

[0066] The embodiments of this specification have been described above based on the embodiments and modifications described above. The embodiments described above are for the purpose of facilitating understanding of this specification and do not limit it. This specification may be modified and improved without departing from its spirit and the scope of the claims, and equivalents thereof are included in this specification. Furthermore, any technical features that are not described as essential in this specification may be deleted as appropriate.

[0067] <Application Example 1> A holding device, A plate-shaped part having a mounting surface on which an object is placed, A resistance heating element is disposed inside the plate-shaped portion, The plate-shaped portion comprises a plurality of via conductors arranged inside the plate-shaped portion and connected to the resistance heating element, The aforementioned resistance heating element, Heating wire and It has a plurality of pads connected to the heating element, At least one of the plurality of pads is connected to the via conductor at a position different from each of the ends of the heating wire, holding device. <Application Example 2> The holding device described in Application Example 1, The resistance heating element has three or more pads, The three or more pads are connected to the heating element while being spaced apart from each other. holding device. <Application Example 3> A holding device as described in Application Example 1 or Application Example 2, The first of the three or more pads is connected to one end of the heating wire, Of the three or more pads, the remaining pads, excluding the first pad, are connected to the heating element at the other end of the heating element, rather than at the center of the heating element. The first pad and the second pad among the remaining pads are each connected to the via conductor, holding device. <Application Example 4> A holding device described in any one of the examples from Application Example 1 to Application Example 3, The first of the three or more pads is connected to one end of the heating wire, Of the three or more pads, the remaining pads, excluding the first pad, are connected to the heating element within a range of 10% of the length of the heating element from the other end of the heating element. The first pad and the second pad among the remaining pads are each connected to the via conductor, holding device. <Application Example 5> A holding device described in any one of Application Examples 1 to 4, The resistance heating element is positioned so as to face the mounting surface described above, In a plan view of the aforementioned mounting surface of the plate-like portion, The first of the three or more pads is connected to the heating wire at the outer periphery of the area where the resistance heating element is placed, The remaining pads among the three or more pads, excluding the first pad, are connected to the heating element in the region, inward from the first pad. holding device. [Explanation of Symbols]

[0068] 1,2,3,4…holding device 11…Plate-like part 11a... Mounting surface 12, 42, 52… Resistive heating element 14, 15… Via conductors 121,521… heating wire 122, 122a, 122b, 122c, 122d, 122e, 122f, 422, 422a, 422b, 422c, 422d, 422e, 422f, 522, 522a, 522b, 522c, 522d, 522e… pad C121...Center of the heating element Eg1... one end of the heating element Eg2...the other end of the heating element R2... Length range R52... Region where the resistance heating element is placed. R521,R522…area W...wafer

Claims

1. A holding device, A plate-shaped part having a mounting surface on which an object is placed, A resistance heating element is disposed inside the plate-shaped portion, The plate-shaped portion comprises a plurality of via conductors arranged inside the plate-shaped portion and connected to the resistance heating element, The aforementioned resistance heating element, Heating wire and It has a plurality of pads connected to the heating element, At least one of the plurality of pads is connected to the via conductor at a position different from each of the ends of the heating wire, holding device.

2. A holding device according to claim 1, The resistance heating element has three or more pads, The three or more pads are connected to the heating element while being spaced apart from each other. holding device.

3. A holding device according to claim 2, The first of the three or more pads is connected to one end of the heating wire, Of the three or more pads, the remaining pads, excluding the first pad, are connected to the heating element at the other end of the heating element, rather than at the center of the heating element. The first pad and the second pad among the remaining pads are each connected to the via conductor, holding device.

4. A holding device according to claim 2, The first of the three or more pads is connected to one end of the heating wire, Of the three or more pads, the remaining pads, excluding the first pad, are connected to the heating element within a range of 10% of the length of the heating element from the other end of the heating element. The first pad and the second pad among the remaining pads are each connected to the via conductor, holding device.

5. A holding device according to claim 2, The resistance heating element is positioned so as to face the mounting surface described above, In a plan view of the aforementioned mounting surface of the plate-like portion, The first of the three or more pads is connected to the heating wire at the outer periphery of the area where the resistance heating element is placed, The remaining pads among the three or more pads, excluding the first pad, are connected to the heating element in the region, inward from the first pad. holding device.

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