Electrostatic chuck, substrate fixing device, and method for manufacturing electrostatic chuck

Abstract

To provide an electrostatic chuck capable of suppressing the occurrence of abnormal discharge.SOLUTION: An electrostatic chuck 30 includes an insulating substrate 40 having a mounting surface 40A on which an object to be adsorbed is mounted and an opposite surface 40B provided on the opposite side of the mounting surface 40A, and a gas hole 50 penetrating from the opposite surface 40B to the mounting surface 40A. The gas hole 50 includes a hole portion 51 extending from the opposite surface 40B toward the mounting surface 40A, a hole portion 52 extending from the mounting surface 40A toward the opposite surface 40B, and a hole portion 53 provided between the hole portion 51 and the hole portion 52 and communicating the hole portion 51 and the hole portion 52. The hole portion 51 is provided so as not to overlap with the hole portion 52 in plan view.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electrostatic chuck, a substrate fixing device, and a method for manufacturing an electrostatic chuck.

Background Art

[0002] Conventionally, a film forming apparatus (for example, a CVD apparatus or a PVD apparatus) or a plasma etching apparatus used for manufacturing semiconductor devices such as ICs and LSIs has a stage for accurately holding a substrate (for example, a silicon wafer) in a vacuum processing chamber. As such a stage, for example, a substrate fixing device that adsorbs and holds a wafer by an electrostatic chuck mounted on a base plate has been proposed.

[0003] The substrate fixing device has, for example, a metal base plate (base), an electrostatic chuck adhered onto the base plate, and an electrostatic electrode built in the electrostatic chuck. Further, the substrate fixing device has a gas supply unit for cooling the wafer. The gas supply unit supplies gas to the surface of the electrostatic chuck through a gas flow path provided in the base plate and gas holes provided in the electrostatic chuck (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in a conventional substrate fixing device, when high-frequency power is supplied to a metal base plate in a state where a wafer is placed on an electrostatic chuck to generate plasma on the surface of the wafer, abnormal discharge may occur in the gas supply unit.

Means for Solving the Problems

[0006] According to one aspect of the present invention, there is provided an insulating substrate having a mounting surface on which an object to be adsorbed is placed and an opposite surface provided on the side opposite to the mounting surface, and a gas hole penetrating from the opposite surface to the mounting surface. The gas hole has a first hole portion extending from the opposite surface toward the mounting surface, a second hole portion extending from the mounting surface toward the opposite surface, and a third hole portion provided between the first hole portion and the second hole portion and communicating the first hole portion and the second hole portion. The first hole portion is provided so as not to overlap the second hole portion in a plan view. and the planar shape of each of the first hole portion, the second hole portion, and the third hole portion is formed in a circular shape, the planar shape of the third hole portion is formed larger than that of the first hole portion and the second hole portion, the inner peripheral surface of the third hole portion has a first portion and a second portion arranged point-symmetrically with respect to the central axis of the third hole portion with the first portion, the first hole portion is provided such that, in a plan view, the whole of the first hole portion overlaps with the third hole portion and a part of the inner peripheral surface of the first hole portion overlaps with the first portion, and the second hole portion is provided such that, in a plan view, the whole of the second hole portion overlaps with the third hole portion and a part of the inner peripheral surface of the second hole portion overlaps with the second portion 。

Effect of the Invention

[0007] According to one aspect of the present invention, there is an effect of suppressing the occurrence of abnormal discharge.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Embodiments for Carrying Out the Invention

[0009] Hereinafter, each embodiment will be described with reference to the accompanying drawings. Note that, for convenience, the accompanying drawings may show the characteristic parts enlarged to make the characteristics easier to understand, and the dimensional ratios of the respective components may be different in each drawing. Also, in the cross-sectional views, in order to make the cross-sectional structures of the respective members easier to understand, the hatching of some members is shown replaced with a satin pattern, and the hatching of some members is omitted. In this specification, "plan view" means looking at an object from the vertical direction (the up-and-down direction in the drawing such as FIG. 1), and "planar shape" means the shape of an object as seen from the vertical direction such as FIG. 1. The "up-and-down direction" and "left-and-right direction" in this specification are the directions when the reference signs indicating the respective members in each drawing can be read correctly with the correct position.

[0010] (First Embodiment) Hereinafter, the first embodiment will be described according to FIGS. 1 to 6. (Configuration of Substrate Fixing Device 10) As shown in Fig. 1(a), the substrate fixing device 10 has a base plate 20 and an electrostatic chuck 30 disposed on the base plate 20. The electrostatic chuck 30 is joined to the upper surface of the base plate 20 by an adhesive such as silicone resin, for example. Note that the electrostatic chuck 30 may be fixed to the base plate 20 with screws. An object to be adsorbed (not shown) is placed on the upper surface of the electrostatic chuck 30. The object to be adsorbed is, for example, a substrate such as a semiconductor wafer. The substrate fixing device 10 adsorbs and holds the object to be adsorbed placed on the electrostatic chuck 30.

[0011] (Configuration of the base plate 20) The shape and size of the base plate 20 can be arbitrary shapes and arbitrary sizes. The base plate 20 is formed in a disc shape, for example, according to the shape of the object to be adsorbed placed on the electrostatic chuck 30. The diameter of the base plate 20 can be, for example, about 150 mm to 500 mm. The thickness of the base plate 20 can be, for example, about 10 mm to 50 mm. Here, in this specification, "disc shape" refers to a shape having a circular planar shape and a predetermined thickness. In the "disc shape", the magnitude relationship between the diameter and the thickness is not limited. Also, those having partially formed concave or convex portions are also included in the "disc shape".

[0012] As the material of the base plate 20, for example, a metal material such as aluminum or cemented carbide, or a composite material of the metal material and a ceramic material can be used. In this embodiment, aluminum or an aluminum alloy is used from the viewpoints of easy availability, easy processing, and good thermal conductivity, and the one with anodizing treatment (insulating layer formation) applied to its surface is used.

[0013] (Configuration of the gas flow path 21) The base plate 20 has a gas flow path 21 that penetrates the base plate 20 in the thickness direction (the vertical direction in the figure). For example, a gas for cooling an object to be adsorbed placed on the electrostatic chuck 30 is supplied to the gas flow path 21. As the cooling gas, an inert gas can be used. As the inert gas, for example, helium (He) gas, argon (Ar) gas, etc. can be used. The gas flow path 21 is formed so as to penetrate from the upper surface of the base plate 20 that is connected to the electrostatic chuck 30 to the lower surface on the opposite side of the upper surface.

[0014] The gas flow path 21 has a gas flow path portion 22 formed on the lower surface of the base plate 20, a plurality of gas flow path portions 23 formed on the upper surface of the base plate 20, and a gas flow path portion 24 that communicates the gas flow path portion 22 and the gas flow path portion 23.

[0015] The gas flow path portion 22 is formed so as to open downward of the base plate 20. The gas flow path portion 22 is formed, for example, so as to extend along the thickness direction of the base plate 20 from the lower surface to the upper surface of the base plate 20. The lower end portion of the gas flow path portion 22 is an inlet (flow inlet) of the gas flow path 21 into which an inert gas is introduced from a gas supply source (not shown).

[0016] Each gas flow path portion 23 is formed so as to open upward of the base plate 20. Each gas flow path portion 23 is formed, for example, so as to extend along the thickness direction of the base plate 20 from the upper surface to the lower surface of the base plate 20. The upper end portion of each gas flow path portion 23 is an outlet (flow outlet) of the gas flow path 21 that discharges the inert gas introduced into the gas flow path 21. The plurality of gas flow path portions 23 are provided apart from each other in a plane direction orthogonal to the thickness direction of the base plate 20 in a cross-sectional view. The plurality of gas flow path portions 23 are, for example, scattered on the upper surface of the base plate 20 in a plan view. The number of gas flow path portions 23 can be appropriately determined as needed. For example, the number of gas flow path portions 23 can be about several tens to several hundreds.

[0017] The gas flow path portion 24 is formed, for example, to communicate the gas flow path portion 22 and a plurality of gas flow path portions 23. The gas flow path portion 24 is formed, for example, to branch one gas flow path portion 22 into a plurality of gas flow path portions 23. The gas flow path portion 24 has, for example, a flow path portion 24A extending in the planar direction from the upper end portion of the gas flow path portion 22, a flow path portion 24B extending in the thickness direction of the base plate 20 from the end portion of the flow path portion 24A, and a flow path portion 24C extending in the planar direction from the upper end portion of the flow path portion 24B. The flow path portion 24C of the present embodiment extends from the upper end portion of the flow path portion 24B in the left direction in the drawing and also extends from the upper end portion of the flow path portion 24B in the right direction in the drawing. The flow path portion 24C is formed, for example, in an annular shape in a plan view. The flow path portion 24C communicates with the lower end portions of the plurality of gas flow path portions 23.

[0018] (Configuration of the electrostatic chuck 30) The electrostatic chuck 30 has an insulating substrate 40 and an electrostatic electrode 70 built in the insulating substrate 40.

[0019] (Configuration of the insulating substrate 40) The shape and size of the insulating substrate 40 can be any shape and any size. The insulating substrate 40 is formed, for example, in a disc shape in accordance with the shape of an object to be adsorbed placed on the electrostatic chuck 30. The planar shape of the insulating substrate 40 is formed, for example, in the same shape and the same size as the planar shape of the base plate 20. The diameter of the insulating substrate 40 can be, for example, about 150 mm to 500 mm. The thickness of the insulating substrate 40 can be, for example, about 1 mm to 5 mm. Note that the size of the planar shape of the insulating substrate 40 may be smaller than the size of the planar shape of the base plate 20.

[0020] As the material of the insulating substrate 40, a material having insulating properties can be used. For example, as the material of the insulating substrate 40, ceramics such as aluminum oxide (Al2O3), aluminum nitride (AlN), and silicon nitride, or organic materials such as silicone resin and polyimide resin can be used. In the present embodiment, ceramics such as aluminum oxide and aluminum nitride are adopted as the material of the insulating substrate 40 from the viewpoints of easy availability, easy processing, and relatively high resistance to plasma and the like. That is, the insulating substrate 40 of the present embodiment is a ceramic substrate made of ceramics.

[0021] The insulating substrate 40 has, for example, a structure in which a plurality of (here, three) insulating layers 41, 42, and 43 are laminated. Each of the insulating layers 41, 42, and 43 is a sintered body formed by sintering a green sheet made of, for example, a mixture of aluminum oxide and an organic material. In each drawing, the interfaces between the insulating layer 41 and the insulating layer 42 and between the insulating layer 42 and the insulating layer 43 are indicated by solid lines. These interfaces are formed by laminating a plurality of green sheets, and may have different positions depending on the lamination state, the interfaces may not be straight in the cross section, or the interfaces may not be clear.

[0022] The insulating substrate 40 has a mounting surface 40A on which an object to be adsorbed is mounted and an opposite surface 40B provided on the side opposite to the mounting surface 40A. The mounting surface 40A is provided, for example, on the upper surface of the insulating layer 43. A plurality of embosses 44 are formed on the mounting surface 40A. The plurality of embosses 44 are provided, for example, side by side along the planar direction of the insulating substrate 40. The plurality of embosses 44 are formed, for example, by providing a plurality of recesses 45 that are recessed from the upper surface of the insulating layer 43 toward the base plate 20. Each recess 45 is formed so as to extend from the upper surface of the insulating layer 43 to the middle in the thickness direction of the insulating layer 43. The opposite surface 40B is provided, for example, on the lower surface of the insulating layer 41. The opposite surface 40B is joined, for example, to the upper surface of the base plate 20.

[0023] (Configuration of the gas hole 50) The insulating substrate 40 has gas holes 50 that penetrate from the opposite surface 40B of the insulating substrate 40 to the mounting surface 40A. The insulating substrate 40 has a plurality of gas holes 50. The plurality of gas holes 50 are provided corresponding to the plurality of gas flow path portions 23 respectively. The plurality of gas holes 50 are formed so as to communicate with the plurality of gas flow path portions 23 respectively. An inert gas for cooling an object to be adsorbed placed on the mounting surface 40A is introduced into each gas hole 50, for example. The inert gas is introduced into each gas hole 50 from each gas flow path portion 23, for example.

[0024] Each gas hole 50 has a hole portion 51 extending from the opposite surface 40B toward the mounting surface 40A, a hole portion 52 extending from the mounting surface 40A toward the opposite surface 40B, and a hole portion 53 provided between the hole portion 51 and the hole portion 52 and communicating the hole portion 51 and the hole portion 52.

[0025] (Configuration of hole portion 51) The hole portion 51 is formed to open downward of the insulating substrate 40. The hole portion 51 communicates with the gas flow path 21, specifically, the gas flow path portion 23. The hole portion 51 is formed to extend, for example, along the thickness direction (vertical direction in the figure) of the insulating substrate 40 from the opposite surface 40B of the insulating substrate 40. The hole portion 51 is formed to extend linearly along the thickness direction of the insulating substrate 40. The hole portion 51 is formed to penetrate the insulating layer 41 in the thickness direction, for example. The upper end portion of the hole portion 51 communicates with the hole portion 53. The shape and size of the hole portion 51 can be any shape and any size.

[0026] As shown in FIG. 2, the planar shape of the hole portion 51 of the present embodiment is formed in a circular shape. The planar shape of the hole portion 51 is formed smaller than the planar shape of the hole portion 53. That is, the hole portion 51 is a finer hole than the hole portion 53. The hole portion 51, for example, entirely overlaps the hole portion 53 in a plan view.

[0027] (Configuration of hole portion 52) As shown in FIG. 1(b), the hole portion 52 is formed so as to open above the insulating substrate 40. The hole portion 52 is formed, for example, so as to extend along the thickness direction of the insulating substrate 40 from the mounting surface 40A of the insulating substrate 40. The hole portion 52 is formed so as to extend linearly along the thickness direction of the insulating substrate 40. The hole portion 52 is formed, for example, so as to penetrate the insulating layer 43 in the thickness direction. The lower end portion of the hole portion 52 communicates with the hole portion 53. The upper end portion of the hole portion 52 is the discharge port of the gas hole 50 for discharging the inert gas to the outside of the gas hole 50. The shape and size of the hole portion 51 can be any shape and any size.

[0028] As shown in FIG. 2, the planar shape of the hole portion 52 of the present embodiment is formed in a circular shape. The planar shape of the hole portion 52 is formed smaller than the planar shape of the hole portion 53. That is, the hole portion 52 is a finer hole than the hole portion 53. The opening width (opening diameter) of the hole portion 52 may be equal to the opening width of the hole portion 51 or may be different from the opening width of the hole portion 51. The hole portion 52, for example, entirely overlaps the hole portion 53 in plan view.

[0029] (Configuration of hole portion 53) As shown in FIG. 1(b), the hole portion 53 is provided between the hole portion 51 and the hole portion 52 in the thickness direction of the insulating substrate 40. The hole portion 53 is formed so as to extend in the planar direction of the insulating substrate 40. The hole portion 53 is provided, for example, in the insulating layer 42. The hole portion 53 is provided, for example, so as to penetrate the insulating layer 42 in the thickness direction. A part of the lower end portion of the hole portion 53 communicates with the hole portion 51. A part of the upper end portion of the hole portion 53 communicates with the hole portion 52. The shape and size of the hole portion 53 can be any shape and any size.

[0030] As shown in FIG. 2, the planar shape of the hole portion 53 of the present embodiment is formed in a circular shape. The planar shape of the hole portion 53 is formed larger than the planar shapes of the hole portions 51 and 52. The planar shape of the hole portion 53 is formed, for example, more than twice as large as the planar shapes of the hole portions 51 and 52 respectively.

[0031] (Positional relationship of hole portions 51, 52, and 53) As shown in FIGS. 1(b) and 2, the hole portion 51 and the hole portion 52 are provided so as not to overlap each other in plan view. The hole portion 51 is provided so that the entire hole portion 51 does not overlap the hole portion 52 in plan view. In plan view, the entire hole portion 51 overlaps the hole portion 53, and the entire hole portion 52 overlaps the hole portion 53. The hole portion 51 is provided, for example, in the vicinity of the inner peripheral surface of the hole portion 53 in plan view. The hole portion 51 is provided, for example, so that a part of the inner peripheral surface of the hole portion 51 overlaps a part of the inner peripheral surface of the hole portion 53 in plan view. The hole portion 52 is provided, for example, in the vicinity of the inner peripheral surface of the hole portion 53. The hole portion 52 is provided, for example, so that a part of the inner peripheral surface of the hole portion 52 overlaps a part of the inner peripheral surface of the hole portion 53 in plan view. The hole portion 51 and the hole portion 52 are provided, for example, at positions farthest from each other within the range where the entire hole portions 51 and 52 overlap the hole portion 53 in plan view. Here, the inner peripheral surface of the hole portion 53 has a first portion 53A and a second portion 53B that is arranged point-symmetrically with respect to the first portion 53A and the central axis A1 of the hole portion 53. The central axis A1 passes through the planar center of the hole portion 53 and extends along the thickness direction of the insulating substrate 40. In the present embodiment, a part of the inner peripheral surface of the hole portion 51 overlaps the first portion 53A in plan view, and a part of the inner peripheral surface of the hole portion 52 overlaps the second portion 53B in plan view. Therefore, the distance between the inner peripheral surfaces of the hole portions 51 and 52 that are farthest from each other is equal to the distance between the first portion 53A and the second portion 53B, that is, the diameter of the hole portion 53, in the planar direction.

[0032] As shown in FIG. 1(b), in the overlapping portion of the inner peripheral surfaces of the hole portions 51 and 53 in plan view, the inner peripheral surface of the hole portion 51 and the inner peripheral surface of the hole portion 53 (that is, the first portion 53A) are formed so as to continuously extend in the thickness direction of the insulating substrate 40. Further, in the overlapping portion of the inner peripheral surfaces of the hole portions 52 and 53 in plan view, the inner peripheral surface of the hole portion 52 and the inner peripheral surface of the hole portion 53 (that is, the second portion 53B) are formed so as to continuously extend in the thickness direction of the insulating substrate 40.

[0033] The gas hole 50 is formed in a crank shape in a cross-sectional view. The cross-sectional shape of the gas hole 50 has a crank shape with two bent portions. That is, the cross-sectional shape of the gas hole 50 is composed of a hole portion 51 extending upward from the opposite surface 40B, a hole portion 53 extending in the planar direction from the upper end portion of the hole portion 51, and a hole portion 52 extending upward from the hole portion 53 at a position shifted from the hole portion 53 in a plan view, having a crank shape. In the gas hole 50, an inert gas is introduced into the hole portion 51 through the gas flow path 21, and the inert gas flows into the hole portion 53 through the hole portion 51. Further, in the gas hole 50, the inert gas flowing into the hole portion 53 moves in the planar direction within the hole portion 53 and then flows into the hole portion 52, and the inert gas is discharged from the gas hole 50 through the hole portion 52. The inert gas discharged from the hole portion 52 can cool the adsorption object by being filled, for example, between the lower surface of the adsorption object placed on the placement surface 40A and the placement surface 40A.

[0034] (Configuration of the porous body 60) A porous body 60 having air permeability is provided inside the gas hole 50. The porous body 60 is provided, for example, inside the hole portion 53 of the gas hole 50. The porous body 60 has pores inside the porous body 60. The pores communicate with the hole portions 51 and 52 so that gas can pass from the lower side (hole portion 51 side) to the upper side (hole portion 52 side) of the porous body 60. The porous body 60 is formed, for example, by providing a large number of ceramic beads such as alumina beads inside the hole portion 53. As the porous body 60, for example, glass fiber or heat-resistant resin sponge can also be used. The porous body 60 is not provided in the hole portions 51 and 52, for example.

[0035] (Configuration of the electrostatic electrode 70) As shown in Fig. 1(a), the electrostatic electrode 70 is provided inside the insulating substrate 40. The electrostatic electrode 70 is, for example, a conductor layer formed in a film shape. The electrostatic electrode 70 is provided, for example, at a portion located in the vicinity of the mounting surface 40A inside the insulating substrate 40. The electrostatic electrode 70 is formed, for example, on the upper surface of the insulating layer 42. The electrostatic electrode 70 is provided so as to be sandwiched between the insulating layer 42 and the insulating layer 43, for example. The electrostatic electrode 70 is electrically connected to an adsorption power source (not shown), for example. The electrostatic electrode 70 fixes the object to be adsorbed to the mounting surface 40A by the electrostatic force generated by the voltage applied from the adsorption power source. As the material of the electrostatic electrode 70, for example, tungsten (W) or molybdenum (Mo) can be used. Although Fig. 1(a) shows one electrostatic electrode 70, actually it includes a plurality of electrodes arranged on the same plane.

[0036] (Operation) Next, the operation of the substrate fixing device 10 will be described. The substrate fixing device 10 is arranged, for example, in a chamber (not shown), and the object to be adsorbed is placed on the mounting surface 40A of the electrostatic chuck 30. Then, while introducing a raw material gas into the chamber and applying a high-frequency voltage to the base plate 20, plasma is generated to perform a process on the object to be adsorbed (for example, a wafer). At this time, an inert gas such as He gas is introduced from a gas supply source (not shown) into the gas supply unit including the gas flow path 21 and the gas holes 50. The inert gas passes through the gas flow path 21, the hole portion 51 of the gas hole 50, the porous body 60 in the hole portion 53, and the hole portion 52 in this order, and is supplied to the lower surface of the object to be adsorbed placed on the mounting surface 40A. When plasma is generated in this way, abnormal discharge may occur between the object to be adsorbed and the metal base plate 20. As a path of the abnormal discharge, as shown in Fig. 1(b), there is a path R1 from the discharge port of the inert gas in the gas hole 50, that is, the upper end portion of the hole portion 52 through the inside of the gas hole 50 to the base plate 20. The path R1 is, for example, the shortest path from the upper end portion of the hole portion 52 through the inside of the gas hole 50 to the upper surface of the base plate 20.

[0037] Here, as in the comparative example shown in FIG. 14, when there is a path R2 that extends linearly along the thickness direction of the insulating substrate 40C (electrostatic chuck 30C) from the discharge port 50D of the gas hole 50C to the upper surface of the base plate 20 in the gas hole 50C, the length of the path R2 coincides with the thickness of the insulating substrate 40C. That is, the length of the abnormal discharge path R2 coincides with the dimension in the thickness direction of the insulating substrate 40C.

[0038] On the other hand, as shown in FIG. 1(b), in the electrostatic chuck 30 of the present embodiment, the hole portion 51 formed on the opposite surface 40B of the insulating substrate 40 and the hole portion 52 formed on the mounting surface 40A are provided so as not to overlap each other in a plan view. According to this configuration, the upper end portion of the hole portion 52, which is the discharge port of the gas hole 50, and the lower end portion of the hole portion 51 that opens to the upper surface side of the base plate 20 can be displaced in the planar direction. For this reason, the length of the abnormal discharge path R1 can be made longer than the thickness of the insulating substrate 40 by the amount of displacement of the hole portions 51 and 52 in the planar direction. More specifically, the path R1 in the electrostatic chuck 30 of the present embodiment extends from the upper end portion of the hole portion 52 along the thickness direction of the insulating layer 43 to the lower end portion of the hole portion 52. The path R1 extends, for example, from the lower end portion of the hole portion 52 to the upper end portion of the hole portion 51 inside the hole portion 53. At this time, since the hole portion 51 and the hole portion 52 are provided so as to be displaced from each other in a plan view, the shortest path from the lower end portion of the hole portion 52 to the upper end portion of the hole portion 51 extends in an oblique direction intersecting the thickness direction of the insulating layer 42. For this reason, the length of the path R1 in the hole portion 53 becomes longer than the thickness of the insulating layer 42. Then, the path R1 extends from the upper end portion of the hole portion 51 along the thickness direction of the insulating layer 41 to the upper surface of the base plate 20. In this way, the length of the path R1 becomes longer than the thicknesses of the insulating layers 41 to 43 (insulating substrate 40) and longer than the path R2 (see FIG. 14) of the comparative example. Thereby, the probability that the plasma staying inside the gas hole 50 collides with the inert gas can be reduced as compared with the comparative example. As a result, the occurrence of abnormal discharge can be suitably suppressed, and the occurrence of insulation breakdown or the like due to abnormal discharge can be suitably suppressed.

[0039] (Manufacturing method of the substrate fixing device 10) Next, a method for manufacturing the substrate fixing device 10 will be described. Here, the method for manufacturing the electrostatic chuck 30 will be described in detail.

[0040] First, in the process shown in FIG. 3(a), green sheets 81, 82, and 83 made of a ceramic material and an organic material are prepared. Each of the green sheets 81, 82, 83 is, for example, a sheet-like material obtained by mixing aluminum oxide (alumina) with a binder, a solvent, etc. The planar size of each of the green sheets 81, 82, 83 corresponds to the planar size of the insulating substrate 40 shown in FIG. 1(a).

[0041] The green sheet 83 becomes the insulating layer 43 shown in FIG. 1(a) by being fired in a process described later. The green sheet 83 is provided with a through hole 83X that penetrates the green sheet 83 in the thickness direction. The through hole 83X is provided at a position corresponding to the hole portion 52 shown in FIG. 1(a). The planar size of the through hole 83X is formed smaller than the planar size of the hole portion 52 shown in FIG. 1(a). The green sheet 82 becomes the insulating layer 42 shown in FIG. 1(a) by being fired in a process described later. The green sheet 82 is provided with a through hole 82X that penetrates the green sheet 82 in the thickness direction. The through hole 82X is provided at a position corresponding to the hole portion 53 shown in FIG. 1(a). The planar size of the through hole 82X is set according to the planar size of the hole portion 53 shown in FIG. 1(a). The green sheet 81 becomes the insulating layer 41 shown in FIG. 1(a) by being fired in a process described later. No through hole is formed in the green sheet 81. Note that the through holes 82X and 83X are formed, for example, by a laser processing method or a machining method.

[0042] Next, in the process shown in Fig. 3(b), each of the green sheets 81, 82, 83 is compressed in the thickness direction by pressing while heating. By this process, the dimensions of each of the green sheets 81, 82, 83 in the thickness direction become smaller than before this process. By compressing each of the green sheets 81, 82, 83 in the thickness direction in this way, the amount of shrinkage of each of the green sheets 81, 82, 83 when each of the green sheets 81, 82, 83 is fired in a process described later can be stably controlled.

[0043] Subsequently, in the process shown in Fig. 4(a), a conductor pattern 71 is formed on the upper surface of the green sheet 82 using a conductive paste, for example, by a printing method (screen printing). This conductor pattern 71 becomes the electrostatic electrode 70 shown in Fig. 1(a) by being fired in a process described later. As the conductive paste, one containing metal particles such as molybdenum or conductive ceramic particles, a binder, and a solvent can be used. Note that the conductor pattern 71 may be formed on the lower surface of the green sheet 83.

[0044] Also, in the process shown in Fig. 4(a), with the surface on which the conductor pattern 71 is formed facing upward, the green sheet 82 is placed on the green sheet 81. Then, the green sheets 81 and 82 are laminated. The green sheets 81 and 82 are adhered to each other, for example, by pressing while heating. By this process, the opening on the lower side of the through hole 82X of the green sheet 82 is blocked by the green sheet 81.

[0045] Next, in the process shown in FIG. 4(b), the paste material 61, which is the precursor of the porous body 60 shown in FIG. 1(a), is filled into the through-hole 82X using a squeegee or the like. At this time, since one opening (here, the lower side) of the through-hole 82X is blocked by the green sheet 81, the paste material 61 can be easily filled into the through-hole 82X. The paste material 61 contains, for example, ceramic beads such as alumina beads that constitute the porous body 60 shown in FIG. 1(a). As the paste material 61, for example, a material containing alumina beads, a binder, and a solvent can be used.

[0046] Subsequently, in the process shown in FIG. 5(a), the green sheet 83 is placed on the green sheets 81 and 82 with the green sheet 82 disposed on the upper side. At this time, the green sheets 81, 82, and 83 are aligned so that the through-hole 83X overlaps the through-hole 82X in a plan view. Then, the green sheets 81, 82, and 83 are laminated to form the structure 80. The green sheets 81, 82, and 83 are adhered to each other, for example, by applying pressure while heating. By this process, the conductor pattern 71 is incorporated between the green sheet 82 and the green sheet 83, and the through-hole 83X is communicated with the through-hole 82X.

[0047] Next, in the process shown in FIG. 5(b), the structure 80 shown in FIG. 5(a) is fired. As a result, the green sheets 81, 82, and 83 are sintered respectively to form the insulating layers 41, 42, and 43, and a ceramic substrate 80A in which these insulating layers 41, 42, and 43 are laminated is formed. The temperature during firing is, for example, 1500°C to 1600°C. By firing in this process, organic components such as the solvent of the paste material 61 shown in FIG. 5(a) are volatilized, and the alumina beads of the paste material 61 are sintered. As a result, a large number of alumina beads are provided inside the through-hole 82X, and a porous body 60 is formed inside the through-hole 82X. At this time, since the through-hole 83X is formed in the insulating layer 43, the gas generated by the volatilization of the organic components of the paste material 61 can be suitably discharged to the outside of the ceramic substrate 80A through the through-hole 83X. Thereby, it is possible to suitably suppress the insulating layers 41 and 43 from being deformed so as to bulge outward due to the above-described gas. Note that the ceramic substrate 80A incorporates the electrostatic electrode 70 obtained by sintering the conductor pattern 71 shown in FIG. 5(a). Various processes are performed on such a ceramic substrate 80A.

[0048] Next, in the process shown in FIG. 6(a), a through-hole 81X that penetrates the insulating layer 41 in the thickness direction and communicates with the through-hole 82X is formed, and a through-hole 83Y that penetrates the insulating layer 43 in the thickness direction and communicates with the through-hole 82X is formed. Here, the through-hole 81X corresponds to the hole portion 51, the through-hole 82X corresponds to the hole portion 53, and the through-hole 83Y corresponds to the hole portion 52. As a result, a gas hole 50 having the through-holes 81X, 82X, and 83Y is formed in the ceramic substrate 80A. The through-hole 83Y is formed, for example, so as to increase the opening width of the through-hole 83X shown in FIG. 5(b). The through-hole 81X is formed so as not to overlap the through-hole 83Y in plan view. The through-holes 81X and 83Y are formed, for example, by a laser processing method or a machining method.

[0049] Subsequently, in the process shown in FIG. 6(b), both the upper and lower surfaces of the ceramic substrate 80A are polished. As a result, the upper surface of the ceramic substrate 80A becomes the mounting surface 40A. Next, a large number of recesses 45 are formed in the mounting surface 40A, and an emboss 44 is formed in the mounting surface 40A. Thereby, the insulating substrate 40 shown in FIG. 1(a) is obtained. The recesses 45 are formed, for example, by a laser processing method or a machining method.

[0050] Through the above manufacturing process, the electrostatic chuck 30 can be manufactured. In the present embodiment, the insulating layer 41 is an example of a first insulating layer, the insulating layer 42 is an example of a second insulating layer, the insulating layer 43 is an example of a third insulating layer, the hole 51 is an example of a first hole, the hole 52 is an example of a second hole, and the hole 53 is an example of a third hole. Further, the green sheet 81 is an example of a first green sheet, the green sheet 82 is an example of a second green sheet, and the green sheet 83 is an example of a third green sheet. Further, the through hole 82X is an example of a first through hole, the through hole 81X is an example of a second through hole, the through hole 83Y is an example of a third through hole, and the through hole 83X is an example of a fourth through hole.

[0051] (Effect) Next, the effects of the present embodiment will be described. (1) The hole 51 extending from the opposite surface 40B of the insulating substrate 40 toward the mounting surface 40A and the hole 52 extending from the mounting surface 40A toward the opposite surface 40B are provided so as not to overlap each other in a plan view. According to this configuration, the upper end portion of the hole 52, which is the discharge port of the gas hole 50, and the lower end portion of the hole 51 opening on the upper surface side of the base plate 20 can be displaced in the plane direction. Therefore, the length of the abnormal discharge path R1 can be made longer than the thickness of the insulating substrate 40 by the amount of displacement of the holes 51 and 52 in the plane direction. Thereby, the probability that the plasma staying inside the gas hole 50 collides with the inert gas can be reduced. As a result, the occurrence of abnormal discharge can be preferably suppressed, and the occurrence of insulation breakdown or the like due to abnormal discharge can be preferably suppressed.

[0052] (2) The planar shape of the hole portion 53 was formed to be larger than the planar shapes of the hole portions 51 and 52. According to this configuration, in a state where the hole portion 53 overlaps in plan view, the amount of deviation in the planar direction between the hole portion 51 and the hole portion 52 can be easily increased. Thereby, the length of the abnormal discharge path R1 can be easily increased.

[0053] (3) The hole portion 51 was provided such that the entire hole portion 51 overlaps the hole portion 53 and a part of the inner peripheral surface of the hole portion 51 overlaps the first portion 53A of the inner peripheral surface of the hole portion 53 in plan view. Also, the hole portion 52 was provided such that the entire hole portion 52 overlaps the hole portion 53 and a part of the inner peripheral surface of the hole portion 52 overlaps the second portion 53B of the inner peripheral surface of the hole portion 53 in plan view. According to this configuration, the hole portion 51 and the hole portion 52 can be provided at positions farthest from each other within the range where the entire hole portions 51 and 52 overlap the hole portion 53 in plan view. Thereby, the amount of deviation between the hole portion 51 and the hole portion 52 in the planar direction can be made larger, so that the length of the abnormal discharge path R1 can be made longer. Therefore, the occurrence of abnormal discharge can be more suitably suppressed.

[0054] (4) A porous body 60 was provided inside the hole portion 53. Thereby, the retention of plasma in the gas hole 50, particularly inside the hole portion 53, can be suppressed. As a result, the probability of collision between the plasma retained inside the gas hole 50 and the inert gas can be reduced, so that the occurrence of abnormal discharge can be suppressed.

[0055] (Second Embodiment) Hereinafter, the second embodiment will be described with reference to FIGS. 7 to 9. In this embodiment, the manufacturing method of the electrostatic chuck 30 is different from that of the first embodiment. Hereinafter, the description will focus on the differences from the first embodiment. The same members as those shown in the previous FIGS. 1 to 6 are denoted by the same reference numerals, and detailed descriptions of these elements are omitted.

[0056] First, in the process shown in Fig. 7(a), a green sheet 81 having a through-hole 81X, a green sheet 82 having a through-hole 82X, and a green sheet 83 having a through-hole 83Y are prepared. Here, the through-hole 81X is provided at a position corresponding to the hole portion 51 shown in Fig. 1(a). The size of the planar shape of the through-hole 81X is set according to the size of the planar shape of the hole portion 51 shown in Fig. 1(a). The through-hole 83Y is provided at a position corresponding to the hole portion 52 shown in Fig. 1(a). The size of the planar shape of the through-hole 83Y is set according to the size of the planar shape of the hole portion 52 shown in Fig. 1(a). The through-hole 81X and the through-hole 83Y are formed at positions that do not overlap each other in a plan view.

[0057] Next, in the process shown in Fig. 7(b), each of the green sheets 81, 82, 83 is compressed in the thickness direction by pressurizing while heating each of the green sheets 81, 82, 83. Subsequently, in the process shown in Fig. 8(a), a conductor pattern 71 is formed on the upper surface of the green sheet 82, for example, by screen printing. Note that the conductor pattern 71 may be formed on the lower surface of the green sheet 83.

[0058] Also, in the process shown in Fig. 8(a), with the surface on which the conductor pattern 71 is formed facing upward, the green sheet 82 is placed on the green sheet 81. At this time, the green sheets 81 and 82 are aligned so that the through-hole 81X overlaps the through-hole 82X in a plan view. Then, the green sheets 81 and 82 are laminated.

[0059] Next, in the process shown in Fig. 8(b), the paste material 61 is filled into the through-hole 82X. Subsequently, in the process shown in Fig. 9(a), the green sheet 83 is placed on the green sheets 81 and 82 with the green sheet 82 disposed on the upper side. At this time, the green sheets 81, 82, and 83 are aligned so that the through-hole 83Y overlaps the through-hole 82X in a plan view and the through-hole 83Y does not overlap the through-hole 81X in a plan view. Then, the green sheets 81, 82, and 83 are laminated to form a structure 80.

[0060] Next, in the process shown in FIG. 9(b), the structure 80 shown in FIG. 9(a) is fired. As a result, the green sheets 81, 82, and 83 are sintered respectively to form the insulating layers 41, 42, and 43, and a ceramic substrate 80A in which these insulating layers 41, 42, and 43 are laminated is formed. By firing in this process, organic components such as the solvent of the paste material 61 shown in FIG. 9(a) are volatilized, and the alumina beads of the paste material 61 are sintered. As a result, a porous body 60 composed of a large number of alumina beads is formed inside the through hole 82X. At this time, since the through holes 81X and 83Y are formed in the insulating layers 41 and 43, the gas generated by the volatilization of the organic components of the paste material 61 can be suitably discharged to the outside of the ceramic substrate 80A through the through holes 81X and 83Y. Thereby, it is possible to suitably suppress the insulating layers 41 and 43 from being deformed so as to bulge outward due to the above-described gas. By this process, gas holes 50 having through holes 81X, 82X, and 83Y are formed in the ceramic substrate 80A. At this time, the through hole 81X corresponds to the hole portion 51, the through hole 82X corresponds to the hole portion 53, and the through hole 83Y corresponds to the hole portion 52.

[0061] Thereafter, both the upper and lower surfaces of the ceramic substrate 80A are polished. As a result, the upper surface of the ceramic substrate 80A is formed as the mounting surface 40A. Next, a large number of recesses 45 are formed in the mounting surface 40A, and an emboss 44 is formed in the mounting surface 40A. Thereby, the insulating substrate 40 and the electrostatic chuck 30 can be manufactured.

[0062] According to the embodiment described above, effects similar to the effects of (1) to (4) of the first embodiment can be achieved. (Third Embodiment) Hereinafter, the third embodiment will be described with reference to FIGS. 10 to 12. In this embodiment, the manufacturing method of the electrostatic chuck 30 is different from that of the first embodiment. Hereinafter, the description will be centered on the differences from the first embodiment. The same members as those shown in FIGS. 1 to 9 above are denoted by the same reference numerals respectively, and detailed descriptions of these elements are omitted.

[0063] First, in the process shown in FIG. 10(a), a green sheet 81, a green sheet 82 having a through-hole 82X, and a green sheet 83 are prepared. Here, no through-holes are formed in the green sheets 81 and 83.

[0064] Next, in the process shown in FIG. 10(b), while heating each of the green sheets 81, 82, and 83, pressure is applied to compress each of the green sheets 81, 82, and 83 in the thickness direction. Subsequently, in the process shown in FIG. 11(a), a conductor pattern 71 is formed on the upper surface of the green sheet 82, for example, by screen printing. Note that the conductor pattern 71 may be formed on the lower surface of the green sheet 83.

[0065] Next, with the surface on which the conductor pattern 71 is formed facing upward, the green sheet 82 is laminated on the green sheet 81. Next, the paste material 61 is filled into the through-hole 82X. At this time, since one (here, the lower side) opening of the through-hole 82X is blocked by the green sheet 81, the paste material 61 can be easily filled into the through-hole 82X.

[0066] Subsequently, in the process shown in FIG. 11(b), the green sheet 83 is placed on the green sheets 81 and 82 with the green sheet 82 disposed on the upper side. Then, the green sheets 81, 82, and 83 are laminated to form a structure 80.

[0067] Next, in the process shown in FIG. 12(a), the structure 80 shown in FIG. 11(b) is fired. As a result, the green sheets 81, 82, and 83 are sintered respectively to form insulating layers 41, 42, and 43, and a ceramic substrate 80A in which these insulating layers 41, 42, and 43 are laminated is formed. By firing in this step, a porous body 60 is formed from the paste material 61 shown in FIG. 11(b) inside the through-hole 82X.

[0068] Next, in the process shown in FIG. 12(b), a through hole 81X that penetrates the insulating layer 41 in the thickness direction and communicates with the through hole 82X is formed, and a through hole 83Y that penetrates the insulating layer 43 in the thickness direction and communicates with the through hole 82X is formed. Here, the through hole 81X corresponds to the hole portion 51, the through hole 82X corresponds to the hole portion 53, and the through hole 83Y corresponds to the hole portion 52. As a result, the gas hole 50 having the through holes 81X, 82X, and 83Y is formed in the ceramic substrate 80A.

[0069] Thereafter, both the upper and lower surfaces of the ceramic substrate 80A are polished. As a result, the upper surface of the ceramic substrate 80A is formed as the mounting surface 40A. Next, a large number of recesses 45 are formed in the mounting surface 40A, and an emboss 44 is formed in the mounting surface 40A. Thereby, the insulating substrate 40 and the electrostatic chuck 30 can be manufactured.

[0070] According to the embodiment described above, the same effects as those of (1) to (4) of the first embodiment can be achieved. (Other Embodiments) Each of the above embodiments can be implemented with the following modifications. Each of the above embodiments and the following modification examples can be implemented in combination with each other within a technically non - conflicting range.

[0071] ·In each of the above embodiments, the hole portion 51 is provided such that a part of the inner peripheral surface of the hole portion 51 overlaps with the first portion 53A of the inner peripheral surface of the hole portion 53 in a plan view, but the formation position of the hole portion 51 is not particularly limited.

[0072] For example, as shown in FIG. 13, the hole portion 51 may be provided at a position that overlaps with the hole portion 53 in a plan view and is separated from the inner peripheral surface of the hole portion 53. ·In each of the above embodiments, the hole portion 52 is provided such that a part of the inner peripheral surface of the hole portion 52 overlaps with the second portion 53B of the inner peripheral surface of the hole portion 53 in a plan view, but the formation position of the hole portion 52 is not particularly limited.

[0073] For example, as shown in FIG. 13, the hole 52 may be provided at a position overlapping the hole 53 in a plan view and away from the inner peripheral surface of the hole 53. · In each of the above embodiments, the entire hole 51 overlaps the hole 53 in a plan view, but the present invention is not limited to this. For example, only a part of the hole 51 may overlap the hole 53 in a plan view. That is, the hole 51 and the hole 53 may be provided so as to partially overlap each other in a plan view.

[0074] · In each of the above embodiments, the entire hole 52 overlaps the hole 53 in a plan view, but the present invention is not limited to this. For example, only a part of the hole 52 may overlap the hole 53 in a plan view. That is, the hole 52 and the hole 53 may be provided so as to partially overlap each other in a plan view.

[0075] · In each of the above embodiments, the insulating layer 41 and the insulating layer 42 may be joined to each other by an adhesive layer. Also, the insulating layer 42 and the insulating layer 43 may be joined to each other by an adhesive layer.

[0076] · The insulating substrate 40 of each of the above embodiments has a structure in which three insulating layers 41, 42, and 43 are laminated, but the present invention is not limited to this. For example, the insulating substrate 40 may have a structure in which four or more insulating layers are laminated. For example, the insulating substrate 40 may be embodied in a structure in which four insulating layers are laminated, and the hole 53 may be formed so as to penetrate two insulating layers in the thickness direction.

[0077] · The gas hole 50 of each of the above embodiments is formed in a structure having one crank shape in a cross-sectional view, but the shape of the gas hole 50 is not particularly limited. For example, the gas hole 50 may be formed in a structure in which two or more crank shapes are continuous in a cross-sectional view.

[0078] · The structure of the electrostatic chuck 30 in each of the above embodiments is not particularly limited. For example, a heating element (heater) may be provided inside the insulating substrate 40 to generate heat by applying a voltage from the outside of the substrate fixing device 10, so that the mounting surface 40A of the insulating substrate 40 reaches a predetermined temperature.

[0079] · The structure of the base plate 20 in each of the above embodiments is not particularly limited. For example, the shape of the gas flow path 21 is not particularly limited. Also, a heater may be provided inside the base plate 20.

[0080] · The emboss 44 on the mounting surface 40A in each of the above embodiments may be omitted. · The substrate fixing device 10 in each of the above embodiments is applied to a semiconductor manufacturing apparatus, for example, a dry etching apparatus. Examples of the dry etching apparatus include a parallel plate type reactive ion etching (RIE) apparatus. Also, the substrate fixing device 10 can be applied to semiconductor manufacturing apparatuses such as a plasma CVD (Chemical Vapor Deposition) apparatus and a sputtering apparatus.

Explanation of Reference Numerals

[0081] 10 Substrate fixing device 20 Base plate 21 Gas flow path 30 Electrostatic chuck 40 Insulating substrate 40A Mounting surface 40B Opposite surface 41 Insulating layer (first insulating layer) 42 Insulating layer (second insulating layer) 43 Insulating layer (third insulating layer) 50 Gas hole 51 Hole portion (first hole portion) 52 Hole portion (second hole portion) 53 Hole portion (third hole portion) 53A First part 53B Second part 60 Porous body 61 Paste material 70 Electrostatic electrode 81 Green sheet (first green sheet) 81X Through-hole (second through-hole) 82 Green sheet (second green sheet) 82X Through-hole (first through-hole) 83 Green sheet (third green sheet) 83X Through-hole (fourth through-hole) 83Y Through-hole (third through-hole) A1 Central axis R1 Path

Claims

1. An insulating substrate having a mounting surface on which an object to be adsorbed is placed and an opposite surface provided on the side opposite to the mounting surface, and a gas hole penetrating from the opposite surface to the mounting surface, wherein the gas hole has a first hole portion extending from the opposite surface toward the mounting surface, a second hole portion extending from the mounting surface toward the opposite surface, and a third hole portion provided between the first hole portion and the second hole portion and communicating the first hole portion and the second hole portion, wherein the first hole portion is provided so as not to overlap the second hole portion in a plan view, wherein each of the first hole portion, the second hole portion, and the third hole portion is formed in a circular shape in a plan view, wherein the third hole portion is formed to have a larger planar shape than the first hole portion and the second hole portion, wherein an inner peripheral surface of the third hole portion has a first portion and a second portion arranged point-symmetrically with respect to a central axis of the third hole portion with respect to the first portion, wherein the first hole portion is provided so that the entire first hole portion overlaps the third hole portion and a part of an inner peripheral surface of the first hole portion overlaps the first portion in a plan view, wherein the second hole portion is provided so that the entire second hole portion overlaps the third hole portion and a part of an inner peripheral surface of the second hole portion overlaps the second portion in a plan view, which is an electrostatic chuck.

2. An insulating substrate having a mounting surface on which an object to be adsorbed is placed and an opposite surface provided on the side opposite to the mounting surface, and a gas hole penetrating from the opposite surface to the mounting surface, wherein the gas hole has a first hole portion extending from the opposite surface toward the mounting surface, a second hole portion extending from the mounting surface toward the opposite surface, and a third hole portion provided between the first hole portion and the second hole portion and communicating the first hole portion and the second hole portion, further comprising a porous body provided inside the third hole portion, wherein the first hole portion is provided so as not to overlap the second hole portion in a plan view, which is an electrostatic chuck.

3. The electrostatic chuck according to claim 2, wherein the third hole portion is formed to have a larger planar shape than the first hole portion and the second hole portion.

4. The electrostatic chuck according to claim 3, wherein the first hole portion is provided so that the entire first hole portion overlaps the third hole portion in a plan view, and the second hole portion is provided so that the entire second hole portion overlaps the third hole portion in a plan view.

5. The inner peripheral surface of the third hole portion has a first portion and a second portion arranged point-symmetrically with respect to the central axis of the first portion and the third hole portion. The first hole portion is provided such that, in a plan view, a part of the inner peripheral surface of the first hole portion overlaps with the first portion. The electrostatic chuck according to claim 4, wherein the second hole portion is provided such that, in a plan view, a part of the inner peripheral surface of the second hole portion overlaps with the second portion.

6. The insulating substrate has a first insulating layer having the opposite surface, a second insulating layer laminated on the first insulating layer, and a third insulating layer having the mounting surface and laminated on the second insulating layer. The first hole portion penetrates the first insulating layer in the thickness direction. The second hole portion penetrates the third insulating layer in the thickness direction. The electrostatic chuck according to any one of claims 1 to 5, wherein the third hole portion penetrates the second insulating layer in the thickness direction.

7. An electrostatic chuck according to any one of claims 1 to 6, and A substrate fixing device having a base plate joined to the opposite surface of the electrostatic chuck.

8. A step of preparing a first green sheet, a second green sheet having a first through hole, and a third green sheet, A step of laminating the second green sheet on the first green sheet, A step of filling the inside of the first through hole with a paste material containing ceramic beads and a solvent, A step of laminating the third green sheet on the second green sheet, A step of firing the mutually laminated first green sheet, second green sheet, and third green sheet, A step of forming a second through hole penetrating the first green sheet in the thickness direction, A step of forming a third through hole penetrating the third green sheet in the thickness direction, In the firing step, a porous body is formed in the first through hole by volatilizing the solvent and sintering the ceramic beads, The first through hole is formed so as to communicate the second through hole and the third through hole, A method for manufacturing an electrostatic chuck, wherein the second through hole and the third through hole are formed so as not to overlap each other in a plan view.

9. Before the step of laminating the third green sheet on the second green sheet, the method includes a step of forming a fourth through hole penetrating the third green sheet in the thickness direction. After the firing step, a step of forming the second through-hole and a step of forming the third through-hole are carried out. The method for manufacturing an electrostatic chuck according to claim 8, wherein in the step of forming the third through-hole, the third through-hole is formed so as to increase the opening width of the fourth through-hole.

10. Before the step of laminating the second green sheet on the first green sheet, a step of forming the second through-hole is carried out. The method for manufacturing an electrostatic chuck according to claim 8, wherein before the step of laminating the third green sheet on the second green sheet, a step of forming the third through-hole is carried out.

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