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

Abstract

To provide an electrostatic chuck that can suppress the occurrence of abnormal discharge. [Solution] The electrostatic chuck 30 has an insulating substrate 40 having a mounting surface 40A on which an object to be adsorbed is placed, and an opposite surface 40B provided on the opposite side of the mounting surface 40A, and a gas hole 60 that penetrates the insulating substrate 40 in the thickness direction. The gas hole 60 has a hole portion 61 extending from the opposite surface 40B toward the mounting surface 40A, an expanding space 62 that communicates with the hole portion 61 and widens the space of the gas hole 60 in the planar direction, and a hole portion 63 that communicates with the expanding space 62 and extends from the expanding space 62 toward the mounting surface 40A. The hole portion 61 is provided so as not to overlap with the hole portion 63 in a planar view. The planar size of the expanding space 62 is formed to be larger than the planar size of the hole portion 61 and the planar size of the hole portion 63 combined. The dimensions of the expanding space 62 along the thickness direction are smaller than the dimensions of the hole portion 61 along the planar direction.

Description

Technical Field

[0006] , , , , ,

[0005] , , , , ,

[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 and a plasma etching apparatus used in manufacturing a semiconductor device have a stage for accurately holding a 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] As an example of the substrate fixing device, there is one having a structure provided with a gas supply unit for cooling the wafer (see, for example, Patent Document 1). The gas supply unit supplies gas to the surface of the electrostatic chuck through a gas flow path provided in the base plate and a gas hole provided in the electrostatic chuck. The gas flow path is formed to extend linearly along the thickness direction of the base plate. The gas hole is formed to extend linearly along the thickness direction of the electrostatic chuck.

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 the above substrate fixing device, it is desired to suppress the occurrence of abnormal discharge in the gas supply unit.

Means for Solving the Problems

[0007] According to one aspect of the present invention, it has the effect of suppressing the occurrence of abnormal discharge. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic cross-sectional view (cross-sectional view along line 1-1 in Figure 2) showing a substrate fixing device according to one embodiment. [Figure 2] Figure 2 is a schematic plan view showing a substrate fixing device according to one embodiment. [Figure 3] Figure 3 is an exploded perspective view showing an electrostatic chuck according to one embodiment. [Figure 4] Figure 4 is a schematic plan view showing each insulating layer of an electrostatic chuck according to one embodiment. [Figure 5] Figure 5 is a schematic cross-sectional view showing a manufacturing method for an electrostatic chuck according to one embodiment. [Figure 6] Figure 6 is a schematic cross-sectional view showing a manufacturing method for an electrostatic chuck according to one embodiment. [Figure 7] Figure 7 is a schematic cross-sectional view showing a manufacturing method for an electrostatic chuck according to one embodiment. [Figure 8]Figure 8 is a schematic cross-sectional view showing a manufacturing method for an electrostatic chuck according to one embodiment. [Figure 9] Figure 9 is a schematic cross-sectional view showing a manufacturing method for an electrostatic chuck according to one embodiment. [Figure 10] Figure 10 is a schematic cross-sectional view showing a manufacturing method for an electrostatic chuck according to one embodiment. [Figure 11] Figure 11 is an exploded perspective view showing an example of a modified electrostatic chuck. [Modes for carrying out the invention]

[0009] One embodiment will be described below with reference to the attached drawings. For convenience, the attached drawings may show enlarged versions of characteristic parts to make the features easier to understand, and the dimensional ratios of each component may differ in each drawing. In addition, in the cross-sectional views, to make the cross-sectional structure of each member easier to understand, the hatching of some members has been replaced with a textured pattern, and the hatching of some members has been omitted. In this specification, "plan view" refers to viewing the object from the vertical direction (up and down direction in the drawing) as shown in Figure 1, etc., and "planar shape" refers to the shape of the object as viewed from the vertical direction as shown in Figure 1, etc. In this specification, "up and down direction" and "left and right direction" refer to the direction in which the symbol indicating each member in each drawing is correctly readable. Unless otherwise stated, the numerical range of "X1~X2" defined by the upper limit X1 and lower limit X2 in this disclosure refers to a range of X1 or more and X2 or less.

[0010] (Overall configuration of the substrate fixing device 10) As shown in Figure 1, the substrate fixing device 10 includes a base plate 20, an electrostatic chuck 30 placed on the base plate 20, and a gas supply unit 50. The electrostatic chuck 30 is bonded to the upper surface of the base plate 20 by an adhesive such as silicone resin. Alternatively, the electrostatic chuck 30 may be fixed to the base plate 20 by screws. An object to be adsorbed (not shown) is placed on the upper surface of the electrostatic chuck 30. An example of an object to be adsorbed is a wafer. The diameter of the wafer can be, for example, about 8 inches, 12 inches, or 18 inches. The substrate fixing device 10 adsorbs and holds the object to be adsorbed placed on the electrostatic chuck 30.

[0011] (Configuration of base plate 20) The base plate 20 is a base (foundation) for mounting the electrostatic chuck 30. The base plate 20 has the rigidity to support the electrostatic chuck 30. As the material of the base plate 20, for example, a metallic material such as aluminum or cemented carbide, or a composite material of such a metallic material and a ceramic material can be used. In this embodiment, aluminum or an aluminum alloy is used, and its surface is anodized, due to its ease of availability, ease of processing, and good thermal conductivity.

[0012] The shape and size of the base plate 20 can be any shape and size. The base plate 20 is formed in a disc shape to match the shape of the object to be adsorbed placed on the electrostatic chuck 30, for example. 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. Hereinafter, in this specification, "disc-shaped" refers to a disc-shaped object with a circular planar shape and a predetermined thickness. In addition, the ratio of thickness to diameter is not a factor in the definition of "disc-shaped". Furthermore, objects with partially formed recesses or protrusions are also included in the definition of "disc-shaped".

[0013] (Configuration of electrostatic chuck 30) The electrostatic chuck 30 has an insulating substrate 40 having a mounting surface 40A on which the object to be adsorbed is placed and an opposite surface 40B provided on the side opposite to the mounting surface 40A, and an electrode (not shown) built in the insulating substrate 40. The electrostatic chuck 30 is a holding body that adsorbs and holds a wafer as an object to be adsorbed. The electrode not shown is, for example, an electrostatic electrode for adsorbing an object to be adsorbed placed on the mounting surface 40A of the insulating substrate 40. The electrode adsorbs and holds the object to be adsorbed on the mounting surface 40A by an electrostatic force generated by a voltage applied from an adsorption power source provided outside the substrate fixing device 10, for example. The electrostatic chuck 30 is, for example, a Johnsen-Rahbek type electrostatic chuck. Note that the electrostatic chuck 30 may be a Coulomb force type electrostatic chuck.

[0014] (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 in a disk shape, for example. The diameter of the insulating substrate 40 may be equal to the diameter of the base plate 20, for example, or may be smaller than the diameter 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 10 mm.

[0015] 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, ceramic materials 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, ceramic materials 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 a ceramic material.

[0016] The insulating substrate 40 has, for example, a structure in which a plurality of (here, four) insulating layers 41, 42, 43, 44 are laminated. Each of the insulating layers 41, 42, 43, 44 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, between the insulating layer 42 and the insulating layer 43, and between the insulating layer 43 and the insulating layer 44 are shown by solid lines. These interfaces are formed by laminating a plurality of green sheets, and there may be cases where the positions are different depending on the lamination state, the interfaces are not straight in the cross section, or the interfaces are not clear.

[0017] The mounting surface 40A of the insulating substrate 40 is provided, for example, on the upper surface of the insulating layer 44. The opposite surface 40B of the insulating substrate 40 is provided, for example, on the lower surface of the insulating layer 41. The opposite surface 40B is joined to the upper surface of the base plate 20 by, for example, an adhesive not shown.

[0018] (Configuration of the gas supply unit 50) A plurality of gas supply units 50 are provided inside the base plate 20 and the electrostatic chuck 30. Each gas supply unit 50 is formed so as to penetrate the base plate 20 in the thickness direction (the vertical direction in the figure) and also penetrate the electrostatic chuck 30 in the thickness direction (the vertical direction in the figure). That is, each gas supply unit 50 penetrates from the lower surface of the base plate 20 to the upper surface of the electrostatic chuck 30 (that is, the mounting surface 40A). Each gas supply unit 50 is formed to open below the base plate 20 and also open above the electrostatic chuck 30. For example, a gas for cooling an object to be adsorbed and held on the mounting surface 40A of the electrostatic chuck 30 is introduced into each gas supply unit 50. As the cooling gas, an inert gas can be used. As the inert gas, for example, helium (He) gas, argon (Ar) gas, or the like can be used.

[0019] As shown in Figure 2, the multiple gas supply units 50 are, for example, scattered on the mounting surface 40A of the electrostatic chuck 30 in a plan view. In this example, eight gas supply units 50 are arranged along the outer edge of the electrostatic chuck 30 in a plan view. The number of gas supply units 50 can be determined as needed. For example, the number of gas supply units 50 can be several tens to several hundred.

[0020] As shown in Figure 1, each gas supply unit 50 has a gas passage 51 provided in the base plate 20 and a gas hole 60 provided in the insulating substrate 40 of the electrostatic chuck 30. Each gas supply unit 50 is formed so as to penetrate from the lower surface of the base plate 20 to the mounting surface 40A of the insulating substrate 40 by the gas passage 51 and the gas hole 60 communicating with each other. In each gas supply unit 50, the lower end of the gas passage 51 becomes the inlet (inlet) of the gas supply unit 50 into which inert gas is introduced from a gas supply source (not shown). In each gas supply unit 50, the upper end of the gas hole 60 becomes the outlet (outlet) of the gas supply unit 50 into which the inert gas introduced into the gas supply unit 50 is discharged. In each gas supply unit 50, inert gas is introduced into the interior of the gas supply unit 50 through the gas passage 51, and the inert gas is discharged from the upper end of the gas hole 60 through the gas passage 51 and the gas hole 60. The inert gas discharged from the upper end of the gas hole 60 can be used to cool the object to be adsorbed by filling the space between the object to be adsorbed and the mounting surface 40A, for example.

[0021] (Configuration of gas flow path 51) Each gas passage 51 is formed to penetrate the base plate 20 in the thickness direction. That is, each gas passage 51 penetrates from the lower surface of the base plate 20 to the upper surface of the base plate 20. Each gas passage 51 is formed to open both below and above the base plate 20.

[0022] (Configuration of gas holes 60) Each gas hole 60 is formed to penetrate the insulating substrate 40 of the electrostatic chuck 30 in the thickness direction (lamination direction). Each gas hole 60 penetrates from the opposite side 40B of the insulating substrate 40 to the mounting surface 40A of the insulating substrate 40. Each gas hole 60 is formed to communicate with each gas channel 51. Inert gas is introduced into each gas hole 60 from each gas channel 51. Note that multiple gas holes 60 have similar structures to each other. Therefore, in the following description, the specific structure of one gas hole 60 (see the dashed-dotted frame in Figure 2) will be described.

[0023] Each gas hole 60 has one or more holes 61 penetrating the insulating layer 41 in the thickness direction, an expanding space 62 that widens the space in the planar direction, one or more holes 63 penetrating the insulating layer 42 in the thickness direction, and an expanding space 64 that widens the space in the planar direction. Each gas hole 60 has one or more holes 65 penetrating the insulating layer 43 in the thickness direction, an expanding space 66 that widens the space in the planar direction, and one or more holes 67 penetrating the insulating layer 44 in the thickness direction. In this embodiment, each gas hole 60 has one hole 61, one expanding space 62, one hole 63, one expanding space 64, one hole 65, one expanding space 66, and one hole 67. Each gas hole 60 is formed to penetrate from the opposite side 40B of the insulating substrate 40 to the mounting surface 40A of the insulating substrate 40, by the communication of the hole portions 61, 63, 65, 67 and the enlarged spaces 62, 64, 66 with each other. Here, the planar direction is the direction perpendicular to the thickness direction of the insulating substrate 40.

[0024] (Configuration of the hole 61) The hole 61 is formed to open to the bottom of the insulating substrate 40. The hole 61 communicates with the gas passage 51. The hole 61 is formed to extend from the opposite side 40B of the insulating substrate 40 toward the mounting surface 40A. The hole 61 is formed to extend linearly, for example, along the thickness direction of the insulating substrate 40. The upper end of the hole 61 communicates with the enlarged space 62. The shape and size of the hole 61 can be any shape and any size.

[0025] As shown in Figures 3 and 4, the planar shape of the hole 61 in this embodiment is formed to be circular. The planar size of the hole 61 is formed to be smaller than the planar size of the enlarged space 62. The diameter (opening diameter) of the hole 61 can be, for example, about 0.05 mm to 0.5 mm.

[0026] (Configuration of the enlarged space 62) As shown in Figure 1, the enlarged space 62 is provided between the insulating layer 41 and the insulating layer 42. The enlarged space 62 is formed to be surrounded by the insulating layer 41 and the insulating layer 42. The enlarged space 62 is provided, for example, on the upper surface of the insulating layer 41. The enlarged space 62 is formed to be recessed upward from the lower surface of the insulating layer 42. The enlarged space 62 is formed not to penetrate the insulating layer 42 in the thickness direction. The enlarged space 62 is formed to be open to the bottom of the insulating layer 42, for example. The depth of the enlarged space 62 is less than the thickness of the insulating layer 42. That is, the dimensions of the enlarged space 62 along the thickness direction of the insulating substrate 40 are less than the dimensions of the insulating layer 42 along the thickness direction. The depth of the enlarged space 62 is less than the diameter of the hole 61. That is, the dimensions of the enlarged space 62 along the thickness direction are less than the dimensions of the hole 61 along the plane direction. The dimensions of the expanded space 62 along the thickness direction can be, for example, approximately 0.02 mm to 0.15 mm.

[0027] As shown in Figure 4, the enlarged space 62 is formed to extend in a planar direction from the hole 61. In a plan view, the enlarged space 62 is formed to surround the hole 61 and the hole 63. In a plan view, the enlarged space 62 is formed to extend into the region between the hole 61 and the hole 63, and also to extend into the region outside the holes 61 and 63. The shape and size of the enlarged space 62 can be any shape and any size. In this embodiment, the planar shape of the enlarged space 62 is formed to be circular. The planar size of the enlarged space 62 is formed to be larger than the combined planar size of the hole 61 and the hole 63. The planar size of the enlarged space 62 can be, for example, about 5 to 12 times the planar size of the hole 61. The diameter of the enlarged space 62 can be, for example, about 1.0 mm to 3.0 mm.

[0028] (Configuration of hole 63) As shown in Figure 1, the lower end of the hole 63 communicates with the enlarged space 62. The hole 63 is formed to extend, for example, from the enlarged space 62 toward the mounting surface 40A. The hole 63 is formed to extend, for example, linearly along the thickness direction of the insulating substrate 40. The hole 63 is formed to extend from the enlarged space 62 to the upper surface of the insulating layer 42. The upper end of the hole 63 communicates with the enlarged space 64.

[0029] As shown in Figure 4, the hole 63 is positioned so as not to overlap with the hole 61 in a plan view. For example, the hole 63 is positioned 180 degrees around the center point of the enlarged space 62 from the hole 61 in a plan view. In the region where the hole 63 overlaps with the enlarged space 62 in a plan view, the hole 63 is positioned so as large as possible in separation distance between the hole 61 and the hole 63.

[0030] The shape and size of the hole 63 can be any shape and size. In this embodiment, the planar shape of the hole 63 is formed to be circular. The planar size of the hole 63 is set to be approximately the same size as the planar size of the hole 61, for example. The planar size of the hole 63 is formed to be smaller than the planar size of the enlarged space 62. The diameter of the hole 63 can be approximately 0.05 mm to 0.5 mm, for example.

[0031] (Configuration of the expanded space 64) As shown in Figure 1, the enlarged space 64 is provided between the insulating layer 42 and the insulating layer 43. The enlarged space 64 is formed to be surrounded by the insulating layer 42 and the insulating layer 43. The enlarged space 64 is provided, for example, on the upper surface of the insulating layer 42. The enlarged space 64 is formed to be recessed upward from the lower surface of the insulating layer 43. The enlarged space 64 is formed so as not to penetrate the insulating layer 43 in the thickness direction. The enlarged space 64 is formed to be open to the bottom of the insulating layer 43, for example. The dimensions of the enlarged space 64 along the thickness direction are smaller than the dimensions of the insulating layer 43 along the thickness direction. The dimensions of the enlarged space 64 along the thickness direction are smaller than the dimensions of the hole 63 along the plane direction. The dimensions of the enlarged space 64 along the thickness direction can be, for example, about 0.02 mm to 0.15 mm.

[0032] As shown in Figure 4, the enlarged space 64 is formed to extend in a planar direction from the hole 63. In a plan view, the enlarged space 64 is formed to surround the hole 63 and the hole 65. In a plan view, the enlarged space 64 is formed to extend into the region between the hole 63 and the hole 65, and also to extend into the region outside the holes 63 and 65. The shape and size of the enlarged space 64 can be any shape and any size. In this embodiment, the planar shape of the enlarged space 64 is formed to be circular. As shown in Figure 3, the enlarged space 64 is formed to overlap with the enlarged space 62 in a plan view. For example, the enlarged space 64 is formed to overlap with the entire enlarged space 62 in a plan view. The planar size of the enlarged space 64 is formed to be larger than the combined planar size of the hole 63 and the hole 65. The planar size of the enlarged space 64 can be, for example, about 5 to 12 times the planar size of the hole 63. The planar size of the enlarged space 64 is set to be approximately the same size as the planar size of the enlarged space 62, for example. The diameter of the enlarged space 64 can be approximately 1.0 mm to 3.0 mm, for example.

[0033] (Configuration of hole 65) As shown in Figure 1, the lower end of the hole 65 communicates with the enlarged space 64. The hole 65 is formed to extend, for example, from the enlarged space 64 toward the mounting surface 40A. The hole 65 is formed to extend, for example, linearly along the thickness direction of the insulating substrate 40. The hole 65 is formed to extend from the enlarged space 64 to the upper surface of the insulating layer 43. The upper end of the hole 65 communicates with the enlarged space 66.

[0034] As shown in Figure 4, the hole 65 is positioned so as not to overlap with the hole 63 in a plan view. For example, the hole 65 is positioned so as to be rotated 180 degrees around the center point of the enlarged space 64 from the hole 63 in a plan view. In the region where the enlarged space 64 overlaps with the hole 65 in a plan view, the hole 65 is positioned so as large as possible in separation distance between the hole 63 and the hole 65. For example, the hole 65 is positioned so as to overlap with the hole 61 in a plan view.

[0035] The shape and size of the hole 65 can be any shape and size. In this embodiment, the planar shape of the hole 65 is formed to be circular. The planar size of the hole 65 is set to be approximately the same size as the planar size of the hole 61, for example. The planar size of the hole 65 is formed to be smaller than the planar size of the enlarged space 64. The diameter of the hole 65 can be approximately 0.05 mm to 0.5 mm, for example.

[0036] (Configuration of the enlarged space 66) As shown in Figure 1, the expansion space 66 is provided between the insulating layer 43 and the insulating layer 44. The expansion space 66 is formed to be surrounded by the insulating layer 43 and the insulating layer 44. The expansion space 66 is provided, for example, on the upper surface of the insulating layer 43. The expansion space 66 is formed to be recessed upward from the lower surface of the insulating layer 44. The expansion space 66 is formed so as not to penetrate the insulating layer 44 in the thickness direction. The expansion space 66 is formed to be open to the bottom of the insulating layer 44, for example. The dimensions of the expansion space 66 along the thickness direction are smaller than the dimensions of the insulating layer 44 along the thickness direction. The dimensions of the expansion space 66 along the thickness direction are smaller than the dimensions of the hole 65 along the plane direction. The dimensions of the expansion space 66 along the thickness direction can be, for example, about 0.02 mm to 0.15 mm.

[0037] As shown in Figure 4, the enlarged space 66 is formed to extend in a planar direction from the hole 65. In a plan view, the enlarged space 66 is formed to surround the hole 65 and the hole 67. In a plan view, the enlarged space 66 is formed to extend into the region between the hole 65 and the hole 67, and also to extend into the region outside the holes 65 and 67. The shape and size of the enlarged space 66 can be any shape and any size. In this embodiment, the planar shape of the enlarged space 66 is formed to be circular. As shown in Figure 3, the enlarged space 66 is formed to overlap with the enlarged spaces 62 and 64 in a planar view. For example, the enlarged space 66 is formed to overlap with the entirety of the enlarged spaces 62 and 64 in a planar view. The planar size of the enlarged space 66 is formed to be larger than the combined planar size of the hole 65 and the hole 67. The planar size of the enlarged space 66 can be, for example, about 5 to 12 times the planar size of the hole 65. The planar size of the enlarged space 66 is set to be approximately the same size as the planar size of the enlarged space 62, for example. The diameter of the enlarged space 66 can be approximately 1.0 mm to 3.0 mm, for example.

[0038] (Configuration of hole 67) As shown in Figure 1, the lower end of the hole 67 communicates with the enlarged space 66. The hole 67 is formed to extend, for example, from the enlarged space 66 toward the mounting surface 40A. The hole 67 is formed to extend, for example, linearly along the thickness direction of the insulating substrate 40. The hole 67 is formed to extend from the enlarged space 66 to the upper surface of the insulating layer 44, i.e., the mounting surface 40A. The upper end of the hole 67 is formed to open above the insulating substrate 40. The upper end of the hole 67 is the outlet of the gas supply unit 50 for discharging inert gas to the outside of the gas supply unit 50.

[0039] As shown in Figure 4, the hole 67 is positioned so as not to overlap with the hole 65 in a plan view. For example, the hole 67 is positioned so as to be rotated 180 degrees around the center point of the enlarged space 66 from the hole 65 in a plan view. In the region where the enlarged space 66 overlaps with the hole 67 in a plan view, the hole 67 is positioned so as large as possible in separation distance between the hole 65 and the hole 67. For example, the hole 67 is positioned so as to overlap with the hole 63 in a plan view.

[0040] The shape and size of the hole 67 can be any shape and any size. In this embodiment, the planar shape of the hole 67 is formed to be circular. The planar size of the hole 67 is set to be, for example, about the same size as the planar size of the hole 61. The planar size of the hole 67 is formed to be smaller than the planar size of the enlarged space 66. The diameter of the hole 67 can be, for example, about 0.05 mm to 0.5 mm.

[0041] As shown in Figure 1, in the gas supply unit 50 described above, inert gas is introduced into the gas supply unit 50 through the gas flow path 51, and the inert gas flows into the hole 61 through the gas flow path 51. In the gas supply unit 50, the inert gas that flows into the expanded space 62 through the hole 61 moves in a planar direction within the expanded space 62, and then flows into the expanded space 64 through the hole 63. In the gas supply unit 50, the inert gas that flows into the expanded space 64 moves in a planar direction within the expanded space 64, and then flows into the expanded space 66 through the hole 65. In the gas supply unit 50, the inert gas that flows into the expanded space 66 moves in a planar direction within the expanded space 66, and then flows into the hole 67, and the inert gas is discharged from the gas supply unit 50 through the hole 67. The inert gas discharged from the hole 67 can be used to cool the object to be adsorbed by filling the space between the lower surface of the object to be adsorbed and the mounting surface 40A, for example.

[0042] (action) Next, the operation of the substrate fixing device 10 will be explained. The substrate fixing device 10 is positioned, 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, a raw material gas is introduced into the chamber, and a high-frequency voltage is applied to the base plate 20 to generate plasma and perform processing on the object to be adsorbed (e.g., 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 50, which consists of a gas channel 51 and gas holes 60. The inert gas is supplied to the lower surface of the object to be adsorbed placed on the mounting surface 40A by passing sequentially through the gas channel 51, hole 61, expansion space 62, hole 63, expansion space 64, hole 65, expansion space 66 and hole 67. When plasma is generated in this manner, abnormal discharge may occur in the gas supply unit 50.

[0043] In conventional electrostatic chucks, if the gas holes are formed to extend in a straight line along the thickness direction of the electrostatic chuck, the distance of the path for the inert gas to flow becomes shorter, resulting in a larger amount of inert gas being present inside the gas holes. Therefore, when a high voltage is applied, the probability of collision between the plasma and the inert gas accumulating inside the gas holes increases, making it easier for abnormal discharges to occur inside the gas holes.

[0044] In contrast, the electrostatic chuck 30 of this embodiment has a structure in which the gas hole 60 has a hole 61 that penetrates the insulating layer 41 in the thickness direction, an expanding space 62 that widens the space of the gas hole 60 in the planar direction, and a hole 63 that penetrates the insulating layer 42 in the thickness direction. Furthermore, the holes 61 and 63 are arranged so that they do not overlap each other in a plan view. With this configuration, by connecting the holes 61 and 63 through the expanding space 62, the path through which the inert gas flows can be lengthened. As a result, the inert gas flows a longer distance than in the conventional design, so the probability of the plasma accumulating inside the gas hole 60 colliding with the inert gas can be lowered compared to the conventional design. As a result, the occurrence of abnormal discharge in the gas hole 60 can be suitably suppressed, and the occurrence of dielectric breakdown and the like caused by abnormal discharge can be suitably suppressed.

[0045] Furthermore, the dimensions of the expanded space 62 along the thickness direction were set to be smaller than the dimensions of the hole 61 along the plane direction. With this configuration, the expanded space 62 can be formed to be narrow in the thickness direction. As a result, for example, when He gas is used as the inert gas, the movement of He molecules in the expanded space 62 can be suppressed, thereby reducing the probability of collisions between He molecules. Specifically, compared to the case where the expanded space 62 is formed to penetrate the insulating layer 42 in the thickness direction, the movement of He molecules within the expanded space 62 can be suppressed, thereby reducing the probability of collisions between He molecules. As a result, the occurrence of abnormal discharge in the gas hole 60 can be suitably suppressed, and the occurrence of dielectric breakdown and other issues caused by abnormal discharge can be suitably suppressed.

[0046] (Manufacturing method for substrate fixing device 10) Next, the manufacturing method of the substrate fixing device 10 will be described. Here, the manufacturing method of the electrostatic chuck 30 will be described in detail.

[0047] First, in the process shown in Figure 5, green sheets 71, 72, 73, and 74 made of ceramic material and organic material are prepared. Each of the green sheets 71, 72, 73, and 74 is a sheet made by mixing, for example, aluminum oxide (alumina) with a binder, solvent, etc. The planar size of each of the green sheets 71, 72, 73, and 74 corresponds to the planar size of the insulating substrate 40 shown in Figure 1. The green sheets 71, 72, 73, and 74 are fired in a process described later to become the insulating layers 41, 42, 43, and 44 shown in Figure 1.

[0048] Next, in the process shown in Figure 6, through holes 71X, 72X, 73X, and 74X are formed in the green sheets 71, 72, 73, and 74, respectively, penetrating them in the thickness direction. The through hole 71X is located at the position corresponding to the hole 61 shown in Figure 1. The through hole 72X is located at the position corresponding to the hole 63 shown in Figure 1. The through hole 73X is located at the position corresponding to the hole 65 shown in Figure 1. The through hole 74X is located at the position corresponding to the hole 67 shown in Figure 1. The through holes 71X, 72X, 73X, and 74X can be formed, for example, by laser processing or machining.

[0049] Next, in the process shown in Figure 7, resin paste 81 is filled into the through-hole 71X using a squeegee, and resin paste 83 is filled into the through-hole 72X. Similarly, resin paste 85 is filled into the through-hole 73X using a squeegee, and resin paste 87 is filled into the through-hole 74X. Resin pastes 81, 83, 85, and 87 are composed of materials that can be volatilized in the firing process described later. As materials for resin pastes 81, 83, 85, and 87, for example, a mixture of resin and carbon can be used.

[0050] Next, in the process shown in Figure 8, resin paste 92 is formed on the upper surface of the green sheet 71, for example by a printing method (screen printing), and resin paste 94 is formed on the upper surface of the green sheet 72. Similarly, resin paste 96 is formed on the upper surface of the green sheet 73, for example by a printing method. Resin paste 92 is provided in a position corresponding to the enlarged space 62 shown in Figure 1. Resin paste 92 is provided so as to overlap with resin pastes 81 and 83 in a plan view. Resin paste 94 is provided in a position corresponding to the enlarged space 64 shown in Figure 1. Resin paste 94 is provided so as to overlap with resin pastes 83 and 85 in a plan view. Resin paste 96 is provided in a position corresponding to the enlarged space 66 shown in Figure 1. Resin paste 96 is provided so as to overlap with resin pastes 85 and 87 in a plan view. Resin pastes 92, 94, and 96 are made of materials that can be volatilized in the firing process described later, similar to resin pastes 81, 83, 85, and 87. For example, a mixture of resin and carbon can be used as the material for the resin pastes 92, 94, and 96. The resin paste 92 may be formed on the underside of the green sheet 72. Alternatively, the resin paste 94 may be formed on the underside of the green sheet 73, or the resin paste 96 may be formed on the underside of the green sheet 74.

[0051] Next, in the process shown in Figure 9, green sheets 72, 73, and 74 are placed on green sheet 71 in that order. At this time, green sheets 71, 72, 73, and 74 are aligned so that the resin pastes 81, 83, 85, 87 and resin pastes 92, 94, 96 overlap each other in a plan view. Then, green sheets 71, 72, 73, and 74 are stacked to form the structure 70. Green sheets 71, 72, 73, and 74 are bonded to each other, for example, by heating and applying pressure. In this process, resin paste 92 is embedded between green sheet 71 and green sheet 72, resin paste 94 is embedded between green sheet 72 and green sheet 73, and resin paste 96 is embedded between green sheet 73 and green sheet 74.

[0052] Next, in the process shown in Figure 10, the structure 70 shown in Figure 9 is fired. As a result, the green sheets 71, 72, 73, and 74 are sintered to form insulating layers 41, 42, 43, and 44, respectively, and an insulating substrate 40 is formed by laminating these insulating layers 41, 42, 43, and 44. The firing temperature is, for example, around 1500°C to 1600°C. During firing in this process, the resin pastes 81, 83, 85, 87, 92, 94, and 96 shown in Figure 9 are volatilized and removed. As a result, gas holes 60 are formed inside the insulating substrate 40, in which holes 61 and enlarged spaces 62, holes 63 and enlarged spaces 64, holes 65 and enlarged spaces 66 and holes 67 are connected.

[0053] The electrostatic chuck 30 can be manufactured through the above manufacturing process. In this embodiment, insulating layer 41 is an example of a first insulating layer, insulating layer 42 is an example of a second insulating layer, hole 61 is an example of a first hole, hole 63 is an example of a second hole, and hole 63 is an example of a third hole. Enlarged space 62 is an example of a first enlarged space, and enlarged space 64 is an example of a second enlarged space. Also, green sheet 71 is an example of a first green sheet, green sheet 72 is an example of a second green sheet, through hole 71X is an example of a first through hole, and through hole 72X is an example of a second through hole. Resin paste 81 is an example of a first resin paste, resin paste 83 is an example of a second resin paste, and resin paste 92 is an example of a third resin paste.

[0054] (Effects of this embodiment) Next, the effects and advantages of this embodiment will be explained. (1) The electrostatic chuck 30 has an insulating substrate 40 having a mounting surface 40A on which an object to be adsorbed is placed and an opposite surface 40B provided on the opposite side of the mounting surface 40A, and a gas hole 60 that penetrates the insulating substrate 40 in the thickness direction. The gas hole 60 has a hole portion 61 extending from the opposite surface 40B toward the mounting surface 40A, an expanding space 62 that communicates with the hole portion 61 and widens the space of the gas hole 60 in the planar direction, and a hole portion 63 that communicates with the expanding space 62 and extends from the expanding space 62 toward the mounting surface 40A. The hole portion 61 is provided so as not to overlap with the hole portion 63 in a planar view. The planar size of the expanding space 62 is formed to be larger than the planar size of the hole portion 61 and the planar size of the hole portion 63 combined. The dimensions of the expanding space 62 along the thickness direction are smaller than the dimensions of the hole portion 61 along the planar direction.

[0055] With this configuration, by connecting the holes 61 and 63 through an expanding space 62 that widens the space of the gas hole 60 in the planar direction, the path of the gas hole 60 can be made more complex, and the distance over which the inert gas flows can be increased. As a result, the inert gas flows a longer distance than before, so the probability of collision between the plasma lingering inside the gas hole 60 and the inert gas can be reduced compared to before. As a result, the occurrence of abnormal discharges within the gas hole 60 can be effectively suppressed, and the occurrence of dielectric breakdown and other problems caused by abnormal discharges can be effectively suppressed.

[0056] (2) Furthermore, the dimensions of the expanded space 62 along the thickness direction were set to be smaller than the dimensions of the hole 61 along the plane direction. With this configuration, the expanded space 62 can be formed to be narrow in the thickness direction. As a result, for example, when He gas is used as the inert gas, the movement of He molecules in the expanded space 62 can be suppressed, thereby reducing the probability of collisions between He molecules. Specifically, compared to the case in which the expanded space 62 is formed to penetrate the insulating layer 42 in the thickness direction, the movement of He molecules in the expanded space 62 can be suppressed, thereby reducing the probability of collisions between He molecules. In this way, by providing the expanded space 62, the path of the gas hole 60 is lengthened, while the movement of He molecules in the expanded space 62 can be suppressed by forming the expanded space 62 to be narrow in the thickness direction. As a result, the occurrence of abnormal discharge in the gas hole 60 can be suitably suppressed, and the occurrence of dielectric breakdown caused by abnormal discharge can be suitably suppressed.

[0057] (3) Incidentally, if the holes 61 and 63 are formed so that they do not overlap in a plan view, the overall shape of the gas hole 60 may be made spiral. In this case, the enlarged space 62 is formed in a curved shape that curves and extends from the hole 61 to the hole 63 in a plan view. In such a case, the inert gas will flow in one direction along the spiral path.

[0058] In contrast, in the electrostatic chuck 30 of this embodiment, the expanded space 62 is formed to extend in the region between the holes 61 and 63, as well as to the region outside the holes 61 and 63, in a plan view. This makes the planar size of the expanded space 62 larger compared to the case where the gas holes 60 are formed in a spiral shape, and allows the expanded space 62 to be formed more widely in the planar direction. Therefore, a larger space can be secured in the expanded space 62 relative to the amount of He molecules introduced into the gas holes 60. Consequently, the probability of He molecules colliding with each other within the expanded space 62 can be suitably reduced.

[0059] (4) The gas hole 60 further has an expanding space 64 that communicates with the hole 63 and widens the space of the gas hole 60 in the planar direction, and a hole 65 that communicates with the expanding space 64 and extends from the expanding space 64 toward the mounting surface 40A. In a plan view, the hole 65 is provided so as not to overlap with the hole 63 and so as to overlap with the hole 61.

[0060] In this configuration, the gas pore 60 is formed in a structure in which the pore 61, the enlarged space 62, the pore 63, the enlarged space 64, and the pore 65 are connected. This makes the path of the gas pore 60 more complex, allowing the distance over which the inert gas flows to be longer. Therefore, since the inert gas flows a longer distance than before, the probability of the plasma remaining inside the gas pore 60 colliding with the inert gas can be reduced compared to before.

[0061] (Example of change) The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0062] In the above embodiment, the planar shapes of the enlarged spaces 62, 64, and 66 were formed in a circular shape, but this is not limited to this. For example, the planar shapes of the enlarged spaces 62, 64, and 66 may be formed in a polygonal or elliptical shape.

[0063] In the above embodiment, the planar shapes of the enlarged spaces 62, 64, and 66 were formed to be the same shape as each other, but the embodiment is not limited to this. For example, the planar shapes of the enlarged spaces 62, 64, and 66 may be formed to be different shapes as well.

[0064] In the above embodiment, the number of holes 61 and 63 communicating with one enlarged space 62 is set to one, but the number of holes 61 and 63 is not particularly limited. Similarly, the number of holes 63 and 65 communicating with one enlarged space 64, and the number of holes 65 and 67 communicating with one enlarged space 66 are not particularly limited.

[0065] For example, as shown in Figure 11, two or more holes 61 may be connected to one enlarged space 62, and two or more holes 63 may be connected to one enlarged space 62. Alternatively, two or more holes 63 may be connected to one enlarged space 64, and two or more holes 65 may be connected to one enlarged space 64. Furthermore, two or more holes 65 may be connected to one enlarged space 66, and two or more holes 67 may be connected to one enlarged space 66.

[0066] In this case, each of the two holes 61 is provided so as not to overlap with the two holes 63 in a plan view. Each of the two holes 63 is provided, for example, at a position rotated 90 degrees around the center point of the enlarged space 62 from each hole 61 in a plan view. Each of the two holes 65 is provided so as not to overlap with the two holes 63 in a plan view, and so as to overlap with each of the two holes 61 in a plan view. Each of the two holes 65 is provided, for example, at a position rotated 90 degrees around the center point of the enlarged space 64 from each hole 63 in a plan view. Each of the two holes 67 is provided so as not to overlap with the two holes 65 in a plan view, and so as to overlap with each of the two holes 63 in a plan view. Each of the two holes 67 is provided, for example, at a position rotated 90 degrees around the center point of the enlarged space 66 from each hole 65 in a plan view.

[0067] In the above embodiment, each gas vent 60 has a structure with three expansion spaces 62, 64, and 66, but the number of expansion spaces in each gas vent 60 is not limited to this. For example, each gas vent 60 may have one or two expansion spaces, or four or more. For example, each gas vent 60 may have only one expansion space 62.

[0068] In the above embodiment, insulating layer 41 and insulating layer 42 may be joined to each other by an adhesive layer. Insulating layer 42 and insulating layer 43 may be joined to each other by an adhesive layer. Insulating layer 43 and insulating layer 44 may be joined to each other by an adhesive layer.

[0069] In the above embodiment, the insulating substrate 40 has a structure in which four insulating layers 41, 42, 43, and 44 are laminated, but it is not limited to this. For example, the insulating substrate 40 may have a structure in which two or three insulating layers are laminated. For example, the insulating substrate 40 may have a structure in which five or more insulating layers are laminated.

[0070] The structure of the electrostatic chuck 30 in the above embodiment is not particularly limited. For example, a heating element (heater) may be provided inside the insulating substrate 40, which generates heat when a voltage is applied from outside the substrate fixing device 10, and heats the mounting surface 40A of the insulating substrate 40 to a predetermined temperature. For example, an embossed structure may be provided on the mounting surface 40A of the insulating substrate 40.

[0071] The structure of the base plate 20 in the above embodiment is not particularly limited. For example, the shape of the gas flow path 51 is not particularly limited. Also, a heater may be provided inside the base plate 20.

[0072] The substrate fixing device 10 of the above embodiment is applicable to semiconductor manufacturing equipment, such as dry etching equipment. Examples of dry etching equipment include parallel plate type reactive ion etching (RIE) equipment. The substrate fixing device 10 can also be applied to semiconductor manufacturing equipment such as plasma CVD (Chemical Vapor Deposition) equipment and sputtering equipment. [Explanation of symbols]

[0073] 10 Board fixing device 20 base plates 30 Electrostatic Chuck 40 Insulating substrate 40A Mounting surface 40B Opposite side 41. Insulating layer (first insulating layer) 42. Insulating layer (second insulating layer) 43 Insulating layer 44 Insulating layer 50 Gas Supply Department 51 Gas flow path 60 gas holes 61 Hole (1st hole) 62. Enlarged Space (First Enlarged Space) 63 Hole (2nd hole) 64. Enlarged Space (Second Enlarged Space) 65 Hole (3rd hole) 66 Expanded Space 67 Hole 71 Green Seat (Green Seat 1) 71X Through hole (1st through hole) 72 Green Seat (Second Green Seat) 72X through hole (second through hole) 73, 74 Green Seats 73X,74X through hole 81 Resin paste (First resin paste) 83 Resin paste (Second resin paste) 85, 87, 94, 96 Resin paste 92 Resin paste (Third resin paste)

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 opposite side of the mounting surface, The insulating substrate has gas holes that penetrate in the thickness direction, The aforementioned gas hole is A first hole extending from the opposite surface toward the aforementioned mounting surface, A first enlarged space that communicates with the first hole and expands the space of the gas hole in a planar direction perpendicular to the thickness direction, It has a second hole that communicates with the first enlarged space and extends from the first enlarged space toward the aforementioned mounting surface, The first hole is provided so as not to overlap with the second hole in a plan view. The planar size of the first enlarged space is formed to be larger than the combined planar size of the first hole and the second hole. An electrostatic chuck in which the dimensions of the first enlarged space along the thickness direction are smaller than the dimensions of the first hole along the plane direction.

2. The planar shape of the first enlarged space is formed in a circular shape. The electrostatic chuck according to claim 1, wherein the first enlarged space is formed to extend in a plan view to the region between the first hole and the second hole, and to extend to a region outside the first hole and the second hole.

3. The aforementioned gas hole is A second expanding space that communicates with the second hole and widens the space of the gas hole in the planar direction, It has a third hole that communicates with the second enlarged space and extends from the second enlarged space toward the aforementioned mounting surface, The electrostatic chuck according to claim 2, wherein the third hole is provided so as not to overlap with the second hole in a plan view, and so as to overlap with the first hole.

4. The electrostatic chuck according to claim 3, wherein the second enlarged space is provided so as to overlap with the entirety of the first enlarged space in a plan view.

5. The gas hole has one first hole, one first enlarged space, and one second hole. The electrostatic chuck according to claim 1, wherein the second hole is located in a position rotated 180 degrees from the first hole around the center point of the first enlarged space in a plan view.

6. The insulating substrate has a first insulating layer having the opposite side and a second insulating layer laminated on the first insulating layer. The first hole is formed so as to penetrate the first insulating layer in the thickness direction, The first enlarged space is formed on the upper surface of the first insulating layer and is formed to be recessed upward from the lower surface of the second insulating layer. The electrostatic chuck according to claim 1, wherein the second hole is formed so as to penetrate the second insulating layer in the thickness direction.

7. The aforementioned gas hole is Two first holes penetrating the first insulating layer in the thickness direction, A first expanded space is provided between the first insulating layer and the second insulating layer, The second insulating layer has two second holes that penetrate in the thickness direction, The two first holes are in communication with the one first enlarged space, The two second holes are in communication with the one first enlarged space. The electrostatic chuck according to claim 6, wherein each of the two first holes is provided so as not to overlap with the two second holes in a plan view.

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

9. The process involves preparing the first green sheet and the second green sheet, The process involves forming a first through-hole that penetrates the first green sheet in the thickness direction, and forming a second through-hole that penetrates the second green sheet in the thickness direction, The process involves filling the first through-hole with a first resin paste and filling the second through-hole with a second resin paste, A step of forming a third resin paste on the upper surface of the first green sheet or the lower surface of the second green sheet so as to overlap the first resin paste and the second resin paste in a plan view, A step of laminating the second green sheet on the first green sheet with the third resin paste sandwiched in between, The process includes a step of firing the first green sheet and the second green sheet which are stacked on top of each other, A method for manufacturing an electrostatic chuck, wherein in the firing step, the first resin paste, the second resin paste, and the third resin paste are volatilized to form a gas hole having a first hole that penetrates the first green sheet in the thickness direction, a first enlarged space communicating with the first hole, and a second hole that communicates with the first enlarged space and penetrates the second green sheet in the thickness direction.

Images