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

Abstract

This invention relates to an electrostatic chuck, comprising: an insulating substrate having a placement surface on which an object is placed and a counter surface disposed on opposite sides of the placement surface; and a gas hole penetrating from the counter surface to the placement surface. The gas hole has a first hole portion extending from the counter surface toward the placement surface, a second hole portion extending from the placement surface toward the counter surface, and a third hole portion disposed between the first hole portion and the second hole portion and formed to communicate with each other. The first hole portion is configured not to overlap with the second hole portion in a plan view.

Description

Technical Field

[0001] This invention relates to an electrostatic chuck, a substrate fixing device, and a method for manufacturing an electrostatic chuck. Prior Technology

[0002] In related technologies, film forming equipment (e.g., CVD equipment, PVD equipment, and the like) and plasma etching equipment used in the manufacture of semiconductor devices such as ICs and LSIs have platforms for accurately holding substrates (e.g., silicon wafers) in a vacuum processing chamber. Regarding this platform, for example, a substrate holding device configured to hold the wafer, for example, by means of electrostatic chucks mounted on a substrate, is proposed.

[0003] The substrate fixing device includes, for example, a metal substrate (substrate), an electrostatic chuck bonded to the substrate, and electrostatic electrodes disposed in the electrostatic chuck. Furthermore, the substrate fixing device includes a gas supply component for cooling the wafer. The gas supply component supplies gas to the surface of the electrostatic chuck via a gas flow path disposed in the substrate and gas holes disposed in the electrostatic chuck (e.g., see PTL 1). [List of Citations] [Patent Documents]

[0004] PTL 1: JP-A-2013-232640 Summary of the Invention

[0005] In the substrate fixing device of the related technology, when high-frequency power is supplied to the metal substrate and plasma is generated on the wafer surface while the wafer is placed on the electrostatic chuck, abnormal discharge may occur in the gas supply component.

[0006] One specific example disclosed herein relates to an electrostatic chuck. The electrostatic chuck includes: An insulating substrate having a placement surface on which an object is placed for adsorption and an opposing surface disposed on an opposite side of the placement surface; and A gas pore that penetrates from the opposing surface to the placement surface. The gas orifice includes a first orifice portion extending from the opposing surface toward the placement surface, a second orifice portion extending from the placement surface toward the opposing surface, and a third orifice portion disposed between the first orifice portion and the second orifice portion and formed to allow communication between the first orifice portion and the second orifice portion. The first hole portion is configured so that it does not overlap with the second hole portion in the plan view.

[0007] According to one embodiment of the present invention, the ability to suppress abnormal discharge can be obtained. Simple Explanation of the Diagram

[0008] Figure 1A shows a schematic cross-sectional view of the substrate fixing device according to the first specific example. Figure 1B is an enlarged cross-sectional view of a portion of the substrate fixing device shown in Figure 1A (a cross-sectional view along line 1b-1b in Figure 2). Figure 2 is a schematic plan view showing a portion of the substrate fixing device according to the first specific example. Figures 3A and 3B are schematic cross-sectional views showing the manufacturing method of the electrostatic chuck according to the first specific example. Figures 4A and 4B are schematic cross-sectional views showing the manufacturing method of the electrostatic chuck according to the first specific example. Figures 5A and 5B are schematic cross-sectional views showing the manufacturing method of the electrostatic chuck according to the first specific example. Figures 6A and 6B are schematic cross-sectional views showing the manufacturing method of the electrostatic chuck according to the first specific example. Figures 7A and 7B are schematic cross-sectional views showing the manufacturing method of the electrostatic chuck according to the second specific example. Figures 8A and 8B are schematic cross-sectional views showing the manufacturing method of the electrostatic chuck according to the second specific example. Figures 9A and 9B are schematic cross-sectional views showing the manufacturing method of the electrostatic chuck according to the second specific example. Figures 10A and 10B are schematic cross-sectional views showing the manufacturing method of the electrostatic chuck according to the third specific example. Figures 11A and 11B are schematic cross-sectional views showing the manufacturing method of the electrostatic chuck according to the third specific example. Figures 12A and 12B are schematic cross-sectional views showing the manufacturing method of the electrostatic chuck according to the third specific example. Figure 13 shows a schematic cross-sectional view of a substrate fixing device according to a modified specific example. Figure 14 shows a schematic cross-sectional view of the substrate fixing device according to a comparative embodiment. Implementation

[0009] The following description refers to the accompanying drawings. Note that, for convenience, the feature parts are enlarged in the drawings to make them easier to understand, and the size proportions of individual components may differ in each drawing. Furthermore, in the cross-sectional views, the shading of some components is shown in a satin pattern, and the shading of some components is omitted to facilitate understanding of the cross-sectional structure of each component. Note that in this specification, "in a plan view" means the object viewed from the vertical direction (up and down direction) in Figure 1A and similar figures, and "planar shape" means the shape of the object viewed from the vertical direction in Figure 1A and similar figures. In this specification, "up and down direction" and "left and right direction" refer to the directions in which the component symbols indicating each component can be correctly read in each drawing are set to their normal positions.

[0010] (First specific example) The first specific example is described below with reference to Figures 1A to 6B. <Configuration of substrate fixing device 10> As shown in Figure 1A, the substrate holding device 10 includes a base plate 20 and an electrostatic chuck 30 disposed on the base plate 20. The electrostatic chuck 30 is bonded to the upper surface of the base plate 20 by an adhesive such as polysiloxane. Note that the electrostatic chuck 30 can also be fixed to the base plate 20 by screws. An object (not shown) is placed on the upper surface of the electrostatic chuck 30. The object is, for example, a substrate, such as a semiconductor wafer. The substrate holding device 10 is configured to adsorb and hold the object placed on the electrostatic chuck 30.

[0011] (Configuration of base plate 20) The base plate 20 can be formed in any shape and size. The base plate 20 is formed in a dish shape, for example, consistent with the shape of the object to be adsorbed and 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, "dish-shaped" refers to a planar shape having a circular shape and a predetermined thickness. Note that in "dish-shaped," the thickness relative to the diameter is not important. Furthermore, shapes that are believed to have concave or convex portions are also included in the term "dish-shaped."

[0012] Regarding the material of the base plate 20, for example, metallic materials such as aluminum or sintered carbides, composite materials of metallic and ceramic materials, or similar materials can be used. In this specific example, from the viewpoints of simple usability, ease of processing, and advantageous thermal conductivity, aluminum or aluminum alloys whose surfaces have been anodized (forming an insulating layer) are used.

[0013] (Configuration of gas flow path 21) The base plate 20 has a gas flow path 21 that penetrates through the base plate 20 in the thickness direction (up and down direction in the figure). The gas flow path 21 supplies gas, for example, for cooling an adsorbed object placed on the electrostatic chuck 30. An inert gas can be used for cooling. For example, helium (He), argon (Ar), or similar gases can be used. The gas flow path 21 is formed to penetrate from the upper surface of the base plate 20 connected to the electrostatic chuck 30 to the upper lower surface located 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 configured to communicate with the gas flow path portions 22 and the gas flow path portions 23.

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

[0016] Each gas flow path portion 23 is formed to be open above the base plate 20. Each gas flow path portion 23 is formed to extend from the upper surface, for example, along the thickness direction of the base plate 20 towards the lower surface of the base plate 20. The upper end portion of each gas flow path portion 23 is used as an outlet (outlet) for discharging the inert gas introduced into the gas flow path 21. A plurality of gas flow path portions 23 are configured to be separated from each other in a plane orthogonal to the thickness direction of the base plate 20 in a cross-sectional view. A plurality of gas flow path portions 23 are, for example, dispersed on the upper surface of the base plate 20 in a planar 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 approximately tens to hundreds.

[0017] The gas flow path portion 24 is configured to communicate with, for example, a gas flow path portion 22 and a plurality of gas flow path portions 23. The gas flow path portion 24 is configured to branch, for example, 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 a planar direction from the upper 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 a planar direction from the upper portion of the flow path portion 24B. In this specific example, the flow path portion 24C extends to the left from the upper portion of the flow path portion 24B in the figure and to the right from the upper portion of the flow path portion 24B in the figure. The flow path portion 24C is formed in a ring shape, for example, in a plan view. The flow path portion 24C is configured to communicate with the lower portions of the plurality of gas flow path portions 23.

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

[0019] (Configuration of insulating substrate 40) The insulating substrate 40 can be formed in any shape and size. The insulating substrate 40 is formed in a dish shape, for example, consistent with the shape of the object being adsorbed and placed on the electrostatic chuck 30. The planar shape of the insulating substrate 40 is, for example, formed to have the same shape and size as the planar shape of the substrate 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 dimensions of the planar shape of the insulating substrate 40 can be smaller than the dimensions of the planar shape of the substrate 20.

[0020] Regarding the material of the insulating substrate 40, materials with insulating properties can be used. For example, ceramics such as alumina (Al₂O₃), aluminum nitride (AlN), and silicon nitride, and organic materials such as polysiloxane and polyimide resins can be used. In this specific example, from the viewpoints of simplicity, ease of processing, and relatively high resistance to plasma, ceramics such as alumina and aluminum nitride are used as the material of the insulating substrate 40. In other words, the insulating substrate 40 of this specific example is a ceramic substrate made of ceramic.

[0021] The insulating substrate 40 has a structure in which, for example, insulating layers 41, 42, and 43 are laminated (here, three layers). Each insulating layer 41, 42, and 43 is a sintered body formed, for example, by sintering a green sheet made of a mixture of alumina and organic materials. In the figures, the interfaces between insulating layers 41 and 42, and between insulating layers 42 and 43, are shown by solid lines. These interfaces are formed by laminating multiple green sheets, and their positions may vary depending on the lamination state. These interfaces may not be straight in cross-section, or they may be indistinct.

[0022] The insulating substrate 40 has a placement surface 40A on which an object to be adsorbed is placed, and a counter surface 40B disposed on the opposite side of the placement surface 40A. The placement surface 40A is disposed on, for example, the upper surface of the insulating layer 43. The placement surface 40A has a plurality of embossed patterns 44. The plurality of embossed patterns 44 are arranged side by side, for example, along the planar direction of the insulating substrate 40. The plurality of embossed patterns 44 are formed, for example, by providing a plurality of recessed portions 45 that are recessed from the upper surface of the insulating layer 43 toward the substrate 20. Each recessed portion 45 is formed to extend from the upper surface of the insulating layer 43 to a middle portion in the thickness direction of the insulating layer 43. The counter surface 40B is disposed on, for example, the lower surface of the insulating layer 41. The counter surface 40B is, for example, bonded to the upper surface of the substrate 20.

[0023] (Configuration of gas pore 50) The insulating substrate 40 has gas holes 50 penetrating from the opposing surface 40B of the insulating substrate 40 to the placement surface 40A. The insulating substrate 40 has a plurality of gas holes 50. The plurality of gas holes 50 are respectively provided corresponding to a plurality of gas flow path portions 23. The plurality of gas holes 50 are formed to communicate with the plurality of flow path portions 23. For example, an inert gas used to cool an adsorbent placed on the placement surface 40A is introduced into each gas hole 50. For example, an inert gas is introduced from each gas flow path portion 23 into each gas hole 50.

[0024] Each gas hole 50 has a hole portion 51 extending from the opposing surface 40B toward the placement surface 40A, a hole portion 52 extending from the placement surface 40A toward the opposing surface 40B, and a hole portion 53 disposed between the hole portion 51 and the hole portion 52 and formed to allow the hole portion 51 and the hole portion 52 to communicate.

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

[0026] As shown in Figure 2, the planar shape of the hole portion 51 in this specific example is circular. The planar shape of the hole portion 51 is formed to be smaller than that of the hole portion 53. In other words, the hole portion 51 is a smaller aperture than the hole portion 53. For example, the hole portion 51 completely overlaps with the hole portion 53 in the planar view.

[0027] (Configuration of Hole Section 52) As shown in Figure 1B, the hole portion 52 is formed to be open above the insulating substrate 40. The hole portion 52 is formed to extend from the placement surface 40A of the insulating substrate 40, for example, along the thickness direction of the insulating substrate 40. The hole portion 52 is formed to extend linearly along the thickness direction of the insulating substrate 40. The hole portion 52 is formed to penetrate the insulating layer 43, for example, in the thickness direction. The lower end portion of the hole portion 52 is formed to communicate with the hole portion 53. The upper end portion of the hole portion 52 is the outlet of the gas hole 50, which discharges inert gas to the outside of the gas hole 50. The shape and size of the hole portion 52 can be formed in any shape and size.

[0028] As shown in Figure 2, the planar shape of the hole portion 52 in this specific example is circular. The planar shape of the hole portion 52 is smaller than that of the hole portion 53. In other words, the hole portion 52 is a smaller aperture than the hole portion 53. The opening width (opening diameter) of the hole portion 52 may be equal to or different from the opening width (opening diameter) of the hole portion 51. For example, the opening width of the hole portion 52 may be smaller than the opening width of the hole portion 51. For example, the hole portion 52 completely overlaps with the hole portion 53 in the planar view.

[0029] (Configuration of Hole Section 53) As shown in Figure 1B, a hole portion 53 is disposed between hole portions 51 and 52 in the thickness direction of the insulating substrate 40. The hole portion 53 is formed to extend in the planar direction of the insulating substrate 40. For example, the hole portion 53 is disposed in the insulating layer 42. The hole portion 53 is configured, for example, to penetrate through the insulating layer 42 in the thickness direction. A portion of the lower end of the hole portion 53 is formed to communicate with the hole portion 51. A portion of the upper end of the hole portion 53 is formed to communicate with the hole portion 52. The shape and size of the hole portion 53 can be formed in any shape and size.

[0030] As shown in Figure 2, the planar shape of the hole portion 53 in this embodiment is circular. The planar shape of the hole portion 53 is formed to be larger than the planar shapes of the hole portions 51 and 52. The planar shape of the hole portion 53 is formed to be, for example, twice or more larger than the planar shapes of each of the hole portions 51 and 52. The diameter of the hole portion 53 may be, for example, about 5 mm to 6 mm, the diameter of the hole portion 51 may be, for example, about 2 mm to 3 mm, and the diameter of the hole portion 52 may be, for example, about 2 mm to 3 mm.

[0031] (Positional relationship of holes 51, 52 and 53) As shown in Figures 1B and 2, hole portions 51 and 52 are configured not to overlap each other in the plan view. Hole portion 51 is configured such that the entire hole portion 51 does not overlap with hole portion 52 in the plan view. In the plan view, the entire hole portion 51 overlaps with hole portion 53, and the entire hole portion 52 overlaps with hole portion 53. Hole portion 51 is configured, for example, near the inner peripheral surface of hole portion 53 in the plan view. Hole portion 51 is configured such that a portion of its inner peripheral surface overlaps with a portion of the inner peripheral surface of hole portion 53 in the plan view. Hole portion 52 is configured, for example, near the inner peripheral surface of hole portion 53. Hole portion 52 is configured such that a portion of its inner peripheral surface overlaps with a portion of the inner peripheral surface of hole portion 53 in the plan view. Hole portions 51 and 52 are configured, for example, at the furthest points from each other within the area where they overlap with hole portion 53 in the plan view. Here, the inner peripheral surface of the hole portion 53 has a first portion 53A and a second portion 53B symmetrically disposed with respect to the central axis A1 of the hole portion 53 and the first portion 53A. The central axis A1 passes through the center of the plane of the hole portion 53 and extends along the thickness direction of the insulating substrate 40. In this specific example, a portion of the inner peripheral surface of the hole portion 51 overlaps with the first portion 53A in the plan view, and a portion of the inner peripheral surface of the hole portion 52 overlaps with the second portion 53B in the plan view. Therefore, the distance between the inner peripheral surfaces of the holes 51 and 52 that are furthest apart from each other is equal to the distance between the first portion 53A and the second portion 53B in the planar direction, i.e., the diameter of the hole portion 53.

[0032] As shown in Figure 1B, in the portion where the inner peripheral surfaces of hole portions 51 and 53 overlap in the plan view, the inner peripheral surfaces of hole portion 51 and hole portion 53 (i.e., the first portion 53A) are formed to extend continuously in the thickness direction of the insulating substrate 40. Furthermore, in the portion where the inner peripheral surfaces of hole portions 52 and 53 overlap in the plan view, the inner peripheral surfaces of hole portion 52 and hole portion 53 (i.e., the second portion 53B) are formed to extend continuously in the thickness direction of the insulating substrate 40.

[0033] The gas orifice 50 is formed in a crank shape in cross-section. The cross-sectional shape of the gas orifice 50 has a crank shape including two curved portions. In other words, the cross-sectional shape of the gas orifice 50 has a crank shape consisting of an orifice portion 51 extending upward from the opposing surface 40B, an orifice portion 53 extending in the planar direction from the upper end portion of the orifice portion 51, and an orifice portion 52 extending upward from the orifice portion 53 at a position offset from the orifice portion 51 in the planar view. In the gas orifice 50, inert gas is introduced into the orifice portion 51 via the gas flow path 21, and the inert gas flows into the orifice portion 53 through the orifice portion 51. Furthermore, in the gas orifice 50, the inert gas flowing into the orifice portion 53 moves in the planar direction within the orifice portion 53 and then flows into the orifice portion 52, and the inert gas is discharged from the gas orifice 50 through the orifice portion 52. The inert gas discharged from the orifice 52 fills the space between the lower surface of the adsorption target and the placement surface 40A, for example, thereby cooling the adsorption target.

[0034] (Configuration of porous body 60) A porous body 60 with permeability is provided in the gas pore 50. The porous body 60 is provided in, for example, the pore portion 53 of the gas pore 50. The porous body 60 has pores present in the porous body 60. These pores communicate with the pore portions 51 and 52, allowing gas to pass from the lower side (pore portion 51 side) of the porous body 60 to the upper side (pore 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, in the pore portion 53. Regarding the porous body 60, for example, glass fiber, heat-resistant resin sponge, or the like can be used. For example, the porous body 60 is not provided in the pore portions 51 and 52.

[0035] (Configuration of electrostatic electrode 70) As shown in Figure 1A, an electrostatic electrode 70 is disposed in an insulating substrate 40. The electrostatic electrode 70 is, for example, a conductive layer formed in the shape of a film. The electrostatic electrode 70 is disposed, for example, in a portion of the insulating substrate 40 located near the placement surface 40A. The electrostatic electrode portion 70 is formed, for example, on the upper surface of an insulating layer 42. The electrostatic electrode 70 is disposed, for example, sandwiched between insulating layers 42 and 43. The electrostatic electrode 70 is electrically connected to, for example, an adsorption power source (not shown). The electrostatic electrode 70 is configured to fix the target object to the placement surface 40A by the electrostatic force generated by the voltage applied from the adsorption power source. Regarding the material of the electrostatic electrode 70, for example, tungsten (W) or molybdenum (Mo) can be used. Note that although one electrostatic electrode 70 is shown in Figure 1A, it includes a plurality of electrodes actually disposed on the same plane.

[0036] (operate) Next, the operation of the substrate fixing device 10 will be explained. For example, with the substrate holder 10 positioned in a chamber (not shown), the target object is placed on the placement surface 40A of the electrostatic chuck 30. Plasma is generated by introducing a raw material gas into the chamber and applying a high-frequency voltage to the substrate 20 to process the target object (e.g., a wafer). At this time, an inert gas, such as He gas, is introduced from a gas supply source (not shown) into a gas supply component configured via a gas flow path 21 and gas holes 50. The inert gas sequentially 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, and is supplied to the lower surface of the target object placed on the placement surface 40A. When plasma is generated in this manner, abnormal discharge may occur between the target object and the metal substrate 20. Regarding the path of abnormal discharge, as shown in Figure 1B, a path R1 can be taken as an example, which runs from the outlet of the inert gas in the gas hole 50 (i.e., the upper part of the hole portion 52) through the interior of the gas hole 50 to the substrate 20. Path R1 is, for example, the shortest path from the upper part of the hole portion 52 through the interior of the gas hole 50 to the upper surface of the substrate 20.

[0037] Here, as shown in the comparative embodiment in FIG14, when there is a path R2 in the gas hole 50C extending linearly from the outlet 50D of the gas hole 50C along the thickness direction of the insulating substrate 40C (static chuck 30C) to the upper surface of the substrate 20, the length of the path R2 is consistent with the thickness of the insulating substrate 40C. In other words, the length of the abnormal discharge path R2 is consistent with the dimension in the thickness direction of the insulating substrate 40C.

[0038] Conversely, as shown in FIG1B, in the electrostatic chuck 30 of this embodiment, the hole portion 51 formed in the opposing surface 40B of the insulating substrate 40 and the hole portion 52 formed in the placement surface 40A are configured not to overlap each other in the planar view. According to this configuration, the upper portion of the hole portion 52 (which is the outlet of the gas hole 50) and the lower portion of the hole portion 51 open on the upper surface side of the substrate 20 can be offset in the planar direction. Therefore, the offset of holes 51 and 52 in the planar direction can make the length of the abnormal discharge path R1 longer than the thickness of the insulating substrate 40. Specifically, in the electrostatic chuck 30 of this embodiment, path R1 extends from the upper portion of the hole portion 52 along the thickness direction of the insulating layer 43 to the lower portion of the hole portion 52. Path R1, for example, extends from the lower portion of the hole portion 52 to the upper portion of the hole portion 51 in the hole portion 53. At this time, since the hole portions 51 and 52 are offset from each other in the plan view, the shortest path from the lower end of the hole portion 52 to the upper end of the hole portion 51 extends obliquely in a direction intersecting the thickness direction of the insulating layer 42. Therefore, the length of the path R1 in the hole portion 53 becomes longer than the thickness of the insulating layer 42. The path R1 extends from the upper end of the hole portion 51 along the thickness direction of the insulating layer 41 to the upper surface of the substrate 20. In this way, the length of the path R1 becomes longer than the thickness of the insulating layers 41 to 43 (insulating substrate 40), and longer than the path R2 in the comparative embodiment (see Figure 14). As a result, the probability of collision between the plasma and the inert gas remaining in the gas hole 50 can be reduced compared to the comparative embodiment. As a result, the occurrence of abnormal discharge can be advantageously suppressed, and the occurrence of dielectric collapse and the like caused by abnormal discharge can be advantageously suppressed.

[0039] <Manufacturing Method of 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.

[0040] First, as shown in Figure 3A, green sheets 81, 82, and 83 are prepared from ceramic and organic materials. Each of the green sheets 81, 82, and 83 has a sheet shape, for example, in which alumina (aluminum oxide) is mixed with a binder, solvent, and the like. The planar dimensions of each of the green sheets 81, 82, and 83 correspond to the planar dimensions of the insulating substrate 40 shown in Figure 1A.

[0041] Green sheet 83 is fired to become the insulating layer 43 shown in FIG1A as described later. Green sheet 83 has a through hole 83X penetrating through it in the thickness direction. The through hole 83X is located at a position corresponding to the hole portion 52 shown in FIG1A. The planar dimensions of the through hole 83X are formed to be smaller than the planar dimensions of the hole portion 52 shown in FIG1A. Green sheet 82 is fired to become the insulating layer 42 shown in FIG1A as described later. Green sheet 82 has a through hole 82X penetrating through it in the thickness direction. The through hole 82X is located at a position corresponding to the hole portion 53 shown in FIG1A. The planar dimensions of the through hole 82X are set to correspond to the planar dimensions of the hole portion 53 shown in FIG1A. Green sheet 81 is fired to become the insulating layer 41 shown in FIG1A as described later. No through holes are formed in the green sheet 81. Note that through holes 82X and 83X are formed by, for example, laser machining or other machining methods.

[0042] Next, in the process shown in Figure 3B, the green sheets 81, 82, and 83 are simultaneously heated under pressure and compressed in the thickness direction. Through this process, the dimensions of each of the green sheets 81, 82, and 83 in the thickness direction become smaller than their dimensions before this process. By compressing the green sheets 81, 82, and 83 in the thickness direction in this manner, the shrinkage of each of the green sheets 81, 82, and 83 can be stably controlled when they are fired in the process described later.

[0043] Subsequently, as shown in Figure 4A, for example, a conductor pattern 71 is formed on the upper surface of the green sheet 82 by a printing method (screen printing) using a conductive paste. The conductor pattern 71 becomes the electrostatic electrode 70 shown in Figure 1A after firing in a process described later. Note that, regarding the conductive paste, a paste comprising metal particles or conductive ceramic particles such as molybdenum, a binder, and a solvent can be used. Note that the conductor pattern 71 can also be formed on the lower surface of the green sheet 83.

[0044] Furthermore, in the process shown in Figure 4A, a green sheet 82 is placed on a green sheet 81 with the surface on which the conductor pattern 71 is formed facing upwards. Then, the green sheets 81 and 82 are laminated. The green sheets 81 and 82 are bonded together, for example, by pressing the green sheets while simultaneously heating them. Through this process, the opening below the through hole 82X in the green sheet 82 is closed by the green sheet 81.

[0045] Next, as shown in Figure 4B, the paste material 61 (which is the precursor of the porous body 60 shown in Figure 1A) is filled into the through-holes 82X using a doctor blade or similar tool. At this time, since the opening on one side (in this case, the lower side) of the through-holes 82X is closed by the green sheet 81, the paste material 61 can be easily filled into the through-holes 82X. The paste material 61 includes, for example, ceramic beads such as alumina beads that constitute the porous body 60 shown in Figure 1A. Regarding the paste material 61, for example, a material comprising alumina beads, a binder, and a solvent can be used.

[0046] Next, as shown in Figure 5A, with the green sheet 82 positioned on the upper side, the green sheet 83 is placed on top of the green sheets 81 and 82. At this time, the positions of the green sheets 81, 82, and 83 are aligned such that the through hole 83X overlaps with the through hole 82X in the plan view. Then, the green sheets 81, 82, and 83 are laminated to form structure 80. For example, the green sheets 81, 82, and 83 are bonded together by pressing and heating them simultaneously. Through this process, the conductor pattern 71 is embedded between the green sheets 82 and 83, and the through hole 83X communicates with the through hole 82X.

[0047] Next, in the process shown in Figure 5B, the structure 80 shown in Figure 5A is fired. Here, the sintered green sheets 81, 82, and 83 become insulating layers 41, 42, and 43, respectively, and a ceramic substrate 80A is formed therein, with insulating layers 41, 42, and 43 laminated. The firing temperature is, for example, 1500°C to 1600°C. Through this firing process, the organic components, such as solvents, of the paste material 61 shown in Figure 5A are volatilized, and the alumina beads of the paste material 61 are sintered. Here, a large number of alumina beads are provided in the through-holes 82X, and a porous body 60 is formed in the through-holes 82X. At this time, since the through-holes 83X are formed in the insulating layer 43, the gases generated by the volatilization of the organic components of the paste material 61 can advantageously be discharged to the outside of the ceramic substrate 80A through the through-holes 83X. Here, the outward expansion and deformation of the insulating layers 41 and 43 due to the aforementioned gases can be advantageously suppressed. Note that the ceramic substrate 80A has an electrostatic electrode 70 obtained via the conductor pattern 71 shown in sintering diagram 5A. Various processes are performed on the ceramic substrate 80A.

[0048] Next, as shown in FIG6A, a through-hole 81X is formed that penetrates through the insulating layer 41 in the thickness direction and communicates with the through-hole 82X, and a through-hole 83Y is formed that penetrates through the insulating layer 43 in the thickness direction and communicates with the through-hole 82X. 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. Thus, a gas hole 50 having through-holes 81X, 82X, and 83Y is formed in the ceramic substrate 80A. The through-hole 83Y is formed, for example, by increasing the opening width of the through-hole 83X shown in FIG5B. The through-hole 81X is formed so that it does not overlap with the through-hole 83Y in the plan view. Note that the through-holes 81X and 83Y are formed by, for example, laser machining or mechanical processing.

[0049] Next, as shown in FIG. 6B, both the upper and lower surfaces of the ceramic substrate 80A are polished. This forms the upper surface of the ceramic substrate 80A as a placement surface 40A. Next, a plurality of recessed portions 45 are formed on the placement surface 40A, and embossing 44 is formed on the placement surface 40A. This yields the insulating substrate 40 shown in FIG. 1A. Note that the recessed portions 45 are formed by, for example, laser machining or mechanical processing.

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

[0051] (effect) Next, the effectiveness of this specific example will be explained. (1) The hole portion 51 extending from the opposite surface 40B of the insulating substrate 40 towards the placement surface 40A and the hole portion 52 extending from the placement surface 40A towards the opposite surface 40B are configured not to overlap each other in the planar view. According to this configuration, the upper part of the hole portion 52 (which is the outlet of the gas hole 50) and the lower part of the hole portion 51 open on the upper surface side of the substrate 20 can be offset in the planar direction. Therefore, the offset of the holes 51 and 52 in the planar direction can make the length of the abnormal discharge path R1 longer than the thickness of the insulating substrate 40. In this way, the probability of collision between the plasma and the inert gas remaining in the gas hole 50 can be reduced. As a result, the occurrence of abnormal discharge can be advantageously suppressed, and the occurrence of dielectric collapse and similar phenomena caused by abnormal discharge can be advantageously suppressed.

[0052] (2) The planar shape of the hole portion 53 is formed to be larger than that of the hole portions 51 and 52. According to this configuration, the offset between the hole portions 51 and 52 in the planar direction can be easily increased in the state where they overlap with the hole portion 53 in the planar view. In this way, the length of the abnormal discharge path R1 can be easily increased.

[0053] (3) Hole portion 51 is configured such that the entire hole portion 51 overlaps with hole portion 53, and a portion of the inner peripheral surface of hole portion 51 overlaps with a first portion 53A of the inner peripheral surface of hole portion 53 in the plan view. Furthermore, hole portion 52 is configured such that the entire hole portion 52 overlaps with hole portion 53, and a portion of the inner peripheral surface of hole portion 52 overlaps with a second portion 53B of the inner peripheral surface of hole portion 53 in the plan view. According to this configuration, hole portions 51 and 52 can be located at the furthest points from each other within the area where they overlap with hole portion 53 in the plan view. This allows for a larger offset between hole portions 51 and 52 in the planar direction, resulting in a longer abnormal discharge path R1. Therefore, the occurrence of abnormal discharge can be more advantageously suppressed.

[0054] (4) A porous body 60 is disposed in the pore portion 53. This can suppress plasma from remaining in the gas pore 50, specifically in the pore portion 53. As a result, the probability of collision between the plasma remaining in the gas pore 50 and the inert gas can be reduced, thereby suppressing the occurrence of abnormal discharge.

[0055] (Second specific example) The second example will now be described with reference to Figures 7A to 9B. In this example, the manufacturing method of the electrostatic chuck 30 differs from that of the first example. The differences from the first example will be explained below. Components identical to those shown in Figures 1 to 6 are indicated by the same component symbols, and detailed descriptions of each of these components are omitted.

[0056] First, as shown in Figure 7A, a green sheet 81 with a through hole 81X, a green sheet 82 with a through hole 82X, and a green sheet 83 with a through hole 83Y are prepared. Here, the through hole 81X is located at a position corresponding to the hole portion 51 shown in Figure 1A. The planar shape dimensions of the through hole 81X are set to correspond to the planar shape dimensions of the hole portion 51 shown in Figure 1A. The through hole 83Y is located at a position corresponding to the hole portion 52 shown in Figure 1A. The planar shape dimensions of the through hole 83Y are set to correspond to the planar shape dimensions of the hole portion 52 shown in Figure 1A. The through holes 81X and 83Y are formed at positions in the planar view where they do not overlap with each other.

[0057] Next, as shown in Figure 7B, the green sheets 81, 82 and 83 are simultaneously heated under pressure and compressed in the thickness direction. Next, in the process shown in Figure 8A, for example, the conductor pattern 71 is formed on the upper surface of the green sheet 82 by screen printing. Note that the conductor pattern 71 can also be formed on the lower surface of the green sheet 83.

[0058] Furthermore, in the process shown in Figure 8A, a green sheet 82 is placed on top of the surface on which the conductor pattern 71 is formed. At this time, the positions of the green sheets 81 and 82 are aligned such that the through hole 81X overlaps with the through hole 82X in the plan view. Then, the green sheets 81 and 82 are laminated.

[0059] Next, as shown in Figure 8B, paste material 71 is filled into the through hole 82X. Next, as shown in Figure 9A, with the green sheet 82 positioned on the upper side, the green sheet 83 is placed on top of the green sheets 81 and 82. At this time, the positions of the green sheets 81, 82, and 83 are aligned such that the through hole 83Y overlaps with the through hole 82X in the plan view, but the through hole 83Y does not overlap with the through hole 81X in the plan view. Then, the green sheets 81, 82, and 83 are laminated to form structure 80.

[0060] Next, in the process shown in FIG9B, the structure 80 shown in FIG9A is fired. Here, the sintered green sheets 81, 82, and 83 become insulating layers 41, 42, and 43, respectively, and a ceramic substrate 80A is formed therein, in which insulating layers 41, 42, and 43 are laminated. Through firing in this process, the organic components, such as solvents, of the paste material 61 shown in FIG9A are volatilized, and the alumina beads of the paste material 61 are sintered. Here, a porous body 60 with a large number of alumina beads is formed in the through-hole 82X. At this time, since through-holes 81X and 83Y are formed in the insulating layers 41 and 43, the gases generated by the volatilization of the organic components of the paste material 61 can advantageously be discharged to the outside of the ceramic substrate 80A through the through-holes 81X and 83Y. Here, the outward expansion and deformation of the insulating layers 41 and 43 due to the aforementioned gases can be advantageously suppressed. Through this process, gas holes 50 having through holes 81X, 82X and 83Y are formed in the ceramic substrate 80A. At this time, through hole 81X corresponds to hole portion 51, through hole 82X corresponds to hole portion 53 and through hole 83Y corresponds to hole portion 52.

[0061] Subsequently, both the upper and lower surfaces of the ceramic substrate 80A are polished. This forms the upper surface of the ceramic substrate 80A as a placement surface 40A. Next, a large number of recessed portions 45 are formed on the placement surface 40A, and embossing 44 is formed on the placement surface 40A. This process yields the insulating substrate 40 and the electrostatic chuck 30.

[0062] Based on the aforementioned specific examples, the same effects (1) to (4) as those in the first specific example can be obtained. (Third specific example) The third example will now be described with reference to Figures 10A to 12B. In this example, the manufacturing method of the electrostatic chuck 30 differs from that of the first example. The following mainly describes the differences from the first example. Components identical to those shown in Figures 1 to 9 are indicated by the same component symbols, and detailed descriptions of each of these components are omitted.

[0063] First, in the process shown in Figure 10A, green sheet 81, green sheet 82 with through hole 82X, and green sheet 83 are prepared. Here, the through hole is not formed in green sheets 81 and 83.

[0064] Next, in the process shown in Figure 10B, the green sheets 81, 82 and 83 are simultaneously heated under pressure and compressed in the thickness direction. Next, in the process shown in Figure 11A, for example, the conductor pattern 71 is formed on the upper surface of the green sheet 82 by screen printing. Note that the conductor pattern 71 can also be formed on the lower surface of the green sheet 83.

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

[0066] Next, as shown in Figure 11B, with the green sheet 82 positioned on the upper side, the green sheet 83 is placed on top of the green sheets 81 and 82. Then, the green sheets 81, 82, and 83 are laminated to form structure 80.

[0067] Next, in the process shown in Figure 12A, the structure 80 shown in Figure 11B is fired. Here, the sintered green sheets 81, 82, and 83 become insulating layers 41, 42, and 43, respectively, and a ceramic substrate 80A is formed therein, in which insulating layers 41, 42, and 43 are laminated. Through this firing process, a porous body 60 is formed from the paste material 61 shown in Figure 11B within the through-holes 82X.

[0068] Next, as shown in FIG12B, a through-hole 81X is formed that penetrates the insulating layer 41 in the thickness direction and communicates with the through-hole 82X, and a through-hole 83Y is formed that penetrates the insulating layer 43 in the thickness direction and communicates with the through-hole 82X. 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. Thus, a gas hole 50 having through-holes 81X, 82X, and 83Y is formed in the ceramic substrate 80A.

[0069] Subsequently, both the upper and lower surfaces of the ceramic substrate 80A are polished. This forms the upper surface of the ceramic substrate 80A as a placement surface 40A. Next, a large number of recessed portions 45 are formed on the placement surface 40A, and embossing 44 is formed on the placement surface 40A. This process yields the insulating substrate 40 and the electrostatic chuck 30.

[0070] Based on the aforementioned specific examples, the same effects (1) to (4) as those in the first specific example can be obtained. (Other specific examples) The above specific examples can be modified and implemented as follows. The above specific examples and the following modified specific examples can be combined and implemented within the scope of technical consistency.

[0071] In the above specific examples, the hole portion 51 is configured such that a portion 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 the plan view. However, there is no specific limitation on the formation position of the hole portion 51.

[0072] For example, as shown in Figure 13, the hole portion 51 may be located at a position in the plan view that overlaps with the hole portion 53 and is separated from the inner peripheral surface of the hole portion 53. In the above specific examples, the hole portion 52 is configured such that a portion 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 the plan view. However, there is no specific limitation on the formation position of the hole portion 52.

[0073] For example, as shown in Figure 13, the hole portion 52 may be located at a position in the plan view that overlaps with the hole portion 53 and is separated from the inner peripheral surface of the hole portion 53. In the above specific examples, the entire hole portion 51 is configured to overlap with the hole portion 53 in the plan view. However, the present invention is not limited thereto. For example, only a portion of the hole portion 51 may overlap with the hole portion 53 in the plan view. In other words, the hole portion 51 and the hole portion 53 may be configured to partially overlap each other in the plan view.

[0074] In the above specific examples, the entire hole portion 52 is configured to overlap with the hole portion 53 in the plan view. However, the present invention is not limited thereto. For example, only a portion of the hole portion 52 may overlap with the hole portion 53 in the plan view. In other words, the hole portion 52 and the hole portion 53 may be configured to partially overlap each other in the plan view.

[0075] In the above specific examples, insulating layer 41 and insulating layer 42 can be bonded to each other by an adhesive layer. In addition, insulating layer 42 and insulating layer 43 can be bonded to each other by an adhesive layer.

[0076] In the above specific examples, the insulating substrate 40 has a structure in which three insulating layers 41, 42, and 43 are laminated. However, the present invention is not limited thereto. 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 specifically implemented in which four insulating layers are laminated, and the hole portion 53 may be formed to penetrate through two insulating layers in the thickness direction.

[0077] In the above specific examples, the gas orifice 50 is formed as a structure having a crank shape in the cross-sectional view. However, the shape of the gas orifice 50 is not specifically limited. For example, the gas orifice 50 may be formed as a structure in which two or more crank shapes are continuous in the cross-sectional view.

[0078] In the above specific examples, there are no specific limitations on the structure of the electrostatic chuck 30. For example, the insulating substrate 40 may be provided with a heat-generating element (heater) that generates heat by applying voltage and heating from the outside of the substrate fixing device 10, so that the placement surface 40A of the insulating substrate 40 reaches a predetermined temperature.

[0079] In the above specific examples, there are no specific limitations on the structure of the base plate 20. For example, there are no specific limitations on the shape of the gas flow path 21. In addition, a heater may be provided in the base plate 20.

[0080] In the above specific examples, the embossing 44 on the surface 40A can be omitted. In the above specific examples, the substrate fixing device 10 is applied to semiconductor manufacturing equipment, such as dry etching equipment. Examples of dry etching equipment include parallel planar reactive ion etching (RIE) equipment. In addition, the substrate fixing device 10 can also be applied to semiconductor manufacturing equipment such as plasma CVD (chemical vapor deposition) equipment and sputtering equipment.

[0081] 10: Substrate fixing device 20: Base plate 21: Gas flow path 22: Gas Flow Path Section 23: Gas Flow Path Section 24: Gas Flow Path Section 24A: Flow path section 24B: Flow path section 24C: Flow path section 30: Electrostatic clamp 30C: Static Clamp 40: Insulating substrate 40A: Placement Surface 40B: Relative surface 40C: Insulating substrate 41: Insulation layer 42: Insulation layer 43: Insulation layer 44: Embossing 45: Concave portion 50: Gas pore 50C: Gas pores 50D: Discharge outlet 51: Hole section 52: Hole section 53: Hole section 53A: Part 1 53B: Part Two 60:Porous body 61: Paste Materials 70: Electrostatic electrode 71: Conductor pattern; paste material 80: Structure 80A: Ceramic substrate 81: Green sheet 81X: Through hole 82: Green sheet 82X: Through hole 83: Green sheet 83X: Through hole 83Y: Through hole A1: Central axis R1: Path R2: Path

Claims

1. An electrostatic chuck, comprising: An insulating substrate has a placement surface on which an object is placed and an opposing surface disposed on an opposite side of the placement surface; and a gas hole penetrating from the opposing surface to the placement surface; wherein the gas hole has a first hole portion extending from the opposing surface toward the placement surface, a second hole portion extending from the placement surface toward the opposing surface, and a third hole portion disposed between the first hole portion and the second hole portion and formed to allow communication between the first hole portion and the second hole portion; wherein the first hole portion is configured not to overlap with the second hole portion in a planar view; wherein the planar shapes of the first hole portion, the second hole portion, and the third hole portion are each formed into a circular shape; wherein the third hole portion has a planar shape larger than the first hole portion and the second hole portion; wherein one of the inner peripheral surfaces of the third hole portion has a first portion and a second portion disposed symmetrically with respect to the central axis of the third hole portion and the first portion. The first hole portion is located in the plan view and is configured such that the entire first hole portion overlaps with the third hole portion, and is configured such that a portion of the inner peripheral surface of one of the first hole portions overlaps with the first portion. The second hole portion is located in the plan view and is configured such that the entire second hole portion overlaps with the third hole portion, and is configured such that a portion of the inner peripheral surface of one of the second hole portions overlaps with the second portion.

2. An electrostatic chuck, comprising: An insulating substrate has a placement surface on which an object to be adsorbed is placed and a opposing surface disposed on an opposite side of the placement surface; and a gas hole penetrating from the opposing surface to the placement surface, wherein the gas hole has a first hole portion extending from the opposing surface toward the placement surface, a second hole portion extending from the placement surface toward the opposing surface, and a third hole portion disposed between the first hole portion and the second hole portion and formed to allow the first hole portion and the second hole portion to communicate with each other, wherein the first hole portion is configured not to overlap with the second hole portion in a plan view, and the electrostatic chuck further includes a porous body disposed in the third hole portion.

3. As in request item 2, the electrostatic clamp, wherein, The third hole portion has a larger planar shape than the first hole portion and the second hole portion.

4. As in request item 3, the electrostatic clamp, wherein, The first hole portion is configured such that the entire first hole portion overlaps with the third hole portion in a plan view, and the second hole portion is configured such that the entire second hole portion overlaps with the third hole portion in a plan view.

5. As in request item 4, the electrostatic clamp, wherein, The inner peripheral surface of one of the third hole portions has a first portion and a second portion symmetrically disposed with respect to the central axis of the third hole portion and the first portion, wherein the first hole portion is configured such that a portion of the inner peripheral surface of the first hole portion overlaps with the first portion in a plan view, and wherein the second hole portion is configured such that a portion of the inner peripheral surface of the second hole portion overlaps with the second portion in a plan view.

6. An electrostatic clamp as requested in any of items 1 to 5, wherein, The insulating substrate includes a first insulating layer having one of the opposing surfaces, a second insulating layer laminated on the first insulating layer, and a third insulating layer having the placement surface and laminated on the second insulating layer, wherein the first hole portion penetrates through the first insulating layer in the thickness direction, wherein the second hole portion penetrates through the third insulating layer in the thickness direction, and wherein the third hole portion penetrates through the second insulating layer in the thickness direction.

7. A substrate fixing device, comprising: Request an electrostatic clamp for any one of items 1 to 6; and a base plate bonded to the opposite surface of the electrostatic chuck.

8. A method for manufacturing an electrostatic chuck, the method comprising: Prepare a first green sheet, a second green sheet having a first through hole, and a third green sheet; The second green sheet is laminated onto the first green sheet; a paste material comprising ceramic beads and a solvent is filled into the first through hole; the third green sheet is laminated onto the second green sheet; the first green sheet, the second green sheet, and the third green sheet laminated on top of each other are fired; a second through hole is formed penetrating through the first green sheet in the thickness direction; and a third through hole is formed penetrating through the third green sheet in the thickness direction, wherein during the firing, the solvent is evaporated and the ceramic beads are sintered, such that a porous body is formed in the first through hole, wherein the first through hole is formed such that the second through hole and the third through hole are interconnected, and wherein the second through hole and the third through hole are formed such that they do not overlap in a plan view.

9. A method for manufacturing the electrostatic chuck as described in claim 8, comprising: Before the third green sheet is laminated onto the second green sheet, a fourth through hole is formed in the thickness direction through the third green sheet. After firing, the second through hole and the third through hole are formed, and in the formation of the third through hole, the third through hole is formed to increase the opening width of the fourth through hole.

10. A method for manufacturing the electrostatic chuck as described in claim 8, wherein, The second through hole is formed before the second green sheet is laminated onto the first green sheet, and the third through hole is formed before the third green sheet is laminated onto the second green sheet.

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