Substrate fixing device

Abstract

To provide a substrate fixing device capable of improving a uniformity of a temperature of a mounting surface.SOLUTION: A substrate fixing device 10 includes: a base plate 20 made of a low thermal expansion ceramic; an electrostatic chuck 70 made of the low thermal expansion ceramic having a mounting surface 71A on which an object to be attracted is mounted; and a brazing part 80 that joins the base plate 20 and the electrostatic chuck 70. The base plate 20 is made of a ceramic material having a thermal expansion coefficient of 0±1 ppm / K at a room temperature. The electrostatic chuck 70 is made of the ceramic material having the thermal expansion coefficient of 0±1 ppm / K at a room temperature.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a substrate fixing device. [Background technology]

[0002] Conventionally, film formation apparatuses (e.g., CVD apparatuses and PVD apparatuses) and plasma etching apparatuses used in manufacturing semiconductor devices such as ICs and LSIs have a substrate fixing device for precisely holding a substrate such as a silicon wafer in a vacuum processing chamber. In the substrate fixing device, a ceramic electrostatic chuck is bonded to a metal base plate by an adhesive layer (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-23088 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional substrate clamping devices, variations in temperature can occur on the mounting surface of the electrostatic chuck, on which the object to be clamped is mounted. Specifically, when the substrate clamping device is exposed to temperatures as low as -60°C or as high as 180°C, a large difference occurs between the amount of thermal deformation of the electrostatic chuck and the amount of thermal deformation of the base plate. This can cause large stresses to act on the adhesive layer, which can lead to cohesive failure of the adhesive layer. When cohesive failure occurs in the adhesive layer, the in-plane uniformity of the thermal resistance of the adhesive layer decreases, resulting in variations in temperature on the mounting surface of the electrostatic chuck. [Means for solving the problem]

[0005] According to one aspect of the present invention, there is provided an electrostatic chuck comprising a base plate made of a low thermal expansion ceramic, an electrostatic chuck made of a low thermal expansion ceramic having a mounting surface on which an object to be attracted is placed, and a first brazing part joining the base plate and the electrostatic chuck, wherein the base plate is made of a ceramic material having a thermal expansion coefficient of 0±1 ppm / K at room temperature, and the electrostatic chuck is made of a ceramic material having a thermal expansion coefficient of 0±1 ppm / K at room temperature. [Effects of the Invention]

[0006] According to one aspect of the present invention, it is possible to achieve an effect of improving the temperature uniformity of the mounting surface. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a substrate fixing device according to one embodiment. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing a part of the substrate fixing device shown in FIG. [Figure 3] FIG. 3 is a schematic cross-sectional view showing a method for manufacturing the substrate fixing device. [Figure 4] FIG. 4 is a schematic cross-sectional view showing a method for manufacturing a substrate fixing device. [Figure 5] FIG. 5 is a schematic cross-sectional view showing a method for manufacturing a substrate fixing device. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a modified example of the substrate fixing device. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment will be described below with reference to the accompanying drawings. For convenience, the accompanying drawings may show characteristic portions enlarged to make the features easier to understand, and the dimensional ratios of each component may differ from one drawing to another. In addition, in the cross-sectional views, the hatching of some components is shown with a matte finish, and the hatching of some components is omitted, to make the cross-sectional structure of each component easier to understand. The terms "up-down direction" and "left-right direction" used in this specification refer to the direction in which the symbols indicating each component in each drawing can be read correctly.

[0009] (Overall configuration of the substrate fixing device 10) As shown in FIG. 1 , the substrate fixing device 10 includes a base plate 20 made of low-thermal expansion ceramic, an electrostatic chuck 70 made of low-thermal expansion ceramic, and a brazing portion 80 that joins the base plate 20 and the electrostatic chuck 70. The substrate fixing device 10 includes, for example, a protective layer 90 that protects the brazing portion 80. The electrostatic chuck 70 is fixed to the upper surface of the base plate 20 by the brazing portion 80. The substrate fixing device 10 is an apparatus that attracts and holds a substrate (not shown), which is an object to be attracted, by the electrostatic chuck 70 mounted on the upper surface of the base plate 20. An example of the substrate is a silicon wafer. The diameter of the substrate can be, for example, approximately 8 inches, 12 inches, or 18 inches.

[0010] The base plate 20 and the electrostatic chuck 70 may be made of a low-thermal expansion ceramic material. For example, a ceramic material with a thermal expansion coefficient of 0±1 ppm / K at room temperature may be used. That is, a ceramic material with a thermal expansion coefficient of zero may be used. For example, a ceramic material containing cordierite (2MgO·2Al2O3·5SiO2) as its main component may be used. Here, the term "main component" as used herein refers to a component that accounts for 90% by weight or more of the components contained in the target portion. The base plate 20 and the electrostatic chuck 70 may be made of the same low-thermal expansion ceramic material or different low-thermal expansion ceramic materials. Note that room temperature is a temperature range of approximately 22°C to 26°C.

[0011] (Configuration of base plate 20) The base plate 20 is a base (base) for mounting the electrostatic chuck 70. The base plate 20 has enough rigidity to support the electrostatic chuck 70. The thickness of the base plate 20 can be, for example, about 20 mm to 50 mm.

[0012] The base plate 20 has a lower portion 21 and an upper portion 22 stacked on the upper surface of the lower portion 21. The lower portion 21 is formed, for example, in a disk shape. The upper portion 22 is formed, for example, in a disk shape. The upper portion 22 is arranged, for example, concentrically on the upper surface of the lower portion 21. The planar size of the upper portion 22 is smaller than the planar size of the lower portion 21. The diameter of the upper portion 22 is smaller than the diameter of the lower portion 21. The upper portion 22 is formed so as to protrude upward from the upper surface of the lower portion 21.

[0013] A cooling path 30, for example, is provided inside the base plate 20. The cooling path 30 has an inlet 31 provided at one end and an outlet 32 ​​provided at the other end. The cooling path 30 is connected to, for example, a cooling medium control device (not shown) provided outside the substrate fixing device 10. The cooling medium control device introduces a cooling medium from the inlet 31 into the cooling path 30 and discharges the cooling medium from the outlet 32. The cooling medium is circulated through the cooling path 30 to cool the base plate 20, thereby cooling the substrate attracted to the electrostatic chuck 70. Note that, for example, water or Galden can be used as the cooling medium.

[0014] A gas flow path 40, for example, is provided inside the base plate 20. The gas flow path 40 is formed so as to penetrate the base plate 20 in the thickness direction (the vertical direction in the drawing). Specifically, the gas flow path 40 penetrates from the upper surface of the upper portion 22 to the lower surface of the lower portion 21. For example, a gas for cooling the substrate attracted to the electrostatic chuck 70 is introduced into the gas flow path 40. An inert gas can be used as the cooling gas. For example, helium (He) gas or argon (Ar) gas can be used as the inert gas.

[0015] The base plate 20 has a structure in which, for example, multiple layers (two layers in this case) of ceramic plates 51 and 52 are stacked. The base plate 20 has the ceramic plates 51 and 52 and a brazing portion 60 that joins the ceramic plates 51 and 52. The ceramic plate 52 is joined to the upper surface of the ceramic plate 51 by the brazing portion 60.

[0016] The ceramic plate 51 constitutes, for example, the lower portion 21 of the base plate 20. The ceramic plate 51 is formed, for example, in a disk shape. The ceramic plate 51 has, for example, an inlet portion 31, an outlet portion 32, and a recess portion 33 that constitute the cooling path 30.

[0017] The recess 33 is formed to be recessed downward from the upper surface of the ceramic plate 51. The recess 33 is formed to open above the ceramic plate 51. The inlet portion 31 is formed to be recessed upward from the lower surface of the ceramic plate 51 and to be in communication with the recess 33. The inlet portion 31 is formed to be in communication below the ceramic plate 51. The outlet portion 32 is formed to be recessed upward from the lower surface of the ceramic plate 51 and to be in communication with the recess 33. The outlet portion 32 is formed to be in communication below the ceramic plate 51.

[0018] 2, the ceramic plate 51 has holes 41 that form the gas flow paths 40. The holes 41 are formed so as to penetrate the ceramic plate 51 in the thickness direction. The holes 41 are formed so as to open to the upper side of the ceramic plate 51 and also to open to the lower side of the ceramic plate 51. The holes 41 are formed so as to extend linearly along the thickness direction of the ceramic plate 51, for example.

[0019] The ceramic plate 52 constitutes, for example, the upper portion 22 of the base plate 20. The ceramic plate 52 is formed, for example, in a disk shape. The planar size of the ceramic plate 52 is smaller than the planar size of the ceramic plate 51.

[0020] Ceramic plate 52 is provided so as to close the opening of recess 33 of ceramic plate 51. In this manner, cooling path 30 is formed by ceramic plate 52 closing the opening of recess 33, recess 33, inlet portion 31, and outlet portion 32 (see FIG. 1).

[0021] The ceramic plate 52 has holes 42, 43 that form the gas flow path 40. The holes 42 and 43 are formed to communicate with each other. The holes 42 and 43 are formed to penetrate the ceramic plate 52 in the thickness direction in cooperation with each other. The hole 42 is formed to be recessed upward from the lower surface of the ceramic plate 52. The hole 42 is formed to open downward of the ceramic plate 52. The hole 42 is formed to communicate with the hole 41 of the ceramic plate 51. The hole 42 is formed to extend linearly along the thickness direction of the ceramic plate 52, for example.

[0022] The hole 43 is formed so as to be recessed downward from the upper surface of the ceramic plate 52 and so as to communicate with the hole 42. The hole 43 is formed so as to open upward from the ceramic plate 52. The planar size of the hole 43 is, for example, larger than the planar size of the hole 42. That is, the opening area of ​​the hole 43 is larger than the opening area of ​​the hole 42. The hole 43 is formed so as to overlap the entire hole 42 in a plan view. Furthermore, the ceramic plate 52 may be provided with a groove formed so as to be recessed downward from the upper surface of the ceramic plate 52.

[0023] The brazing portion 60 has a conductive pattern 61 formed on the upper surface of the ceramic plate 51, a conductive pattern 62 formed on the lower surface of the ceramic plate 52, and a brazing material 63 that joins the conductive patterns 61, 62.

[0024] The conductive pattern 61 is provided so as to overlap the ceramic plate 52 in a plan view, for example. The conductive pattern 61 is provided so as not to overlap the recessed portion 33 and the hole portion 41 in a plan view, for example. The conductive pattern 62 is provided so as to overlap the conductive pattern 61 in a plan view, for example. The conductive pattern 62 is provided so as not to overlap the recessed portion 33 and the hole portions 41 and 42 in a plan view, for example.

[0025] The brazing material 63 bonds the conductive pattern 61 and the conductive pattern 62 together. The brazing material 63 is bonded to the upper surface of the conductive pattern 61 and also to the lower surface of the conductive pattern 62. In this way, the conductive pattern 61 and the conductive pattern 62 are bonded to each other by brazing using the brazing material 63. By bonding the conductive pattern 61 and the conductive pattern 62 to each other, the ceramic plate 51 and the ceramic plate 52 are bonded to each other. As a result, the ceramic plate 52 is stacked on the upper surface of the ceramic plate 51. Note that the brazing material 63 may be, for example, silver brazing.

[0026] (Configuration of electrostatic chuck 70) 1, the electrostatic chuck 70 includes a substrate body 71 and an electrode 72 built into the substrate body 71. The electrostatic chuck 70 is, for example, a Johnsen-Rahbek type electrostatic chuck. The electrostatic chuck 70 may also be a Coulomb force type electrostatic chuck. The electrostatic chuck 70 is a holder that attracts and holds a substrate, which is an object to be attracted.

[0027] The substrate body 71 is formed, for example, in a disk shape. The diameter of the substrate body 71 may be, for example, equal to the diameter of the upper portion 22 of the base plate 20, or may be larger than the diameter of the upper portion 22. In this embodiment, the diameter of the substrate body 71 is equal to the diameter of the upper portion 22. The diameter of the substrate body 71 may be, for example, approximately 150 mm to 500 mm. The thickness of the substrate body 71 may be, for example, approximately 0.5 mm to 10 mm.

[0028] The substrate body 71 has a mounting surface 71A (here, the upper surface) on which a substrate, which is an object to be attracted, is mounted. The substrate body 71 is, for example, a dielectric material. The substrate body 71 is, for example, a ceramic substrate.

[0029] The substrate body 71 is provided with, for example, a gas flow path 73. The gas flow path 73 is formed to penetrate the substrate body 71 in the thickness direction. The gas flow path 73 is formed to open both upward and downward of the substrate body 71. The gas flow path 73 is formed to communicate with the gas flow path 40 of the base plate 20. As shown in FIG. 2 , the gas flow path 73 is formed to communicate with the hole portion 43 of the ceramic plate 52. The gas flow path 73 is formed to extend linearly along the thickness direction of the substrate body 71. The planar size of the gas flow path 73 is, for example, smaller than the planar size of the hole portion 43. That is, the opening area of ​​the gas flow path 73 is smaller than the opening area of ​​the hole portion 43. The gas flow path 73 is formed to overlap the hole portion 43 in its entirety in a planar view. For example, the gas flow path 73 is formed at a position different from the hole portion 42 in a planar view.

[0030] 1, in the substrate fixing device 10, a gas hole 11 is formed by a gas flow path 40 and a gas flow path 73. The gas hole 11 is formed so as to penetrate from the mounting surface 71A of the substrate main body 71 to the underside of the base plate 20 by communicating the gas flow path 40 with the gas flow path 73. In the gas hole 11, an inert gas is introduced into the gas hole 11 through the gas flow path 40, and the inert gas is discharged from the gas hole 11 through the gas flow path 73. The inert gas discharged from the gas flow path 73 can cool the substrate by filling, for example, the space between the mounting surface 71A and the underside of the substrate placed on the mounting surface 71A.

[0031] The electrode 72 is, for example, an electrostatic electrode for attracting a substrate placed on the mounting surface 71A. The electrode 72 is an electrode formed in a thin film. The electrode 72 is, for example, built into a portion of the substrate body 71 located near the mounting surface 71A in the thickness direction. The electrode 72 is, for example, arranged on a plane parallel to the mounting surface 71A. The electrode 72 is, for example, electrically connected to an attraction power supply provided outside the substrate fixing device 10. When a predetermined voltage is applied from the attraction power supply, the electrode 72 generates an electrostatic attraction force between the electrode 72 and the substrate placed on the mounting surface 71A. This allows the substrate to be attracted and held on the mounting surface 71A. The attraction and holding force of the electrostatic chuck 70 increases as the voltage applied to the electrode 72 increases. The electrode 72 may be unipolar or bipolar. Examples of materials that can be used for the electrode 72 include tungsten (W) and molybdenum (Mo). Although each drawing shows one electrode 72, in reality it includes a plurality of electrodes arranged on the same plane.

[0032] (Configuration of brazed portion 80) As shown in FIG. 2, the brazing portion 80 includes a conductive pattern 81 formed on the upper surface of the base plate 20, a conductive pattern 82 formed on the lower surface of the electrostatic chuck 70, and a brazing material 83 that joins the conductive patterns 81 and 82.

[0033] The conductive pattern 81 is formed on the upper surface of the ceramic plate 52. For example, the conductive pattern 81 is provided so as to overlap the electrostatic chuck 70 in a plan view. For example, the conductive pattern 81 is provided so as not to overlap the hole portion 43 and the gas flow path 73 in a plan view. For example, the conductive pattern 81 is formed so as to cover the entire upper surface of the ceramic plate 52.

[0034] The conductive pattern 82 is formed on the lower surface of the substrate main body 71. For example, the conductive pattern 82 is provided so as to overlap with the conductive pattern 81 in a plan view. For example, the conductive pattern 82 is provided so as not to overlap with the hole portion 43 and the gas flow path 73 in a plan view.

[0035] The brazing material 83 bonds the conductive pattern 81 and the conductive pattern 82 together. The brazing material 83 is bonded to the upper surface of the conductive pattern 81 and also to the lower surface of the conductive pattern 82. In this manner, the conductive pattern 81 and the conductive pattern 82 are bonded to each other by brazing using the brazing material 83. The conductive pattern 81 and the conductive pattern 82 are bonded to each other, whereby the base plate 20 and the electrostatic chuck 70 are bonded to each other. As a result, the electrostatic chuck 70 is stacked on the upper surface of the base plate 20. Note that, for example, silver brazing can be used as the brazing material 83.

[0036] (Configuration of protective layer 90) The protective layer 90 has the function of protecting the brazing portions 60, 80 from plasma. The protective layer 90 is formed on the outer surface of the base plate 20 and the outer surface of the electrostatic chuck 70 so as to cover the brazing portions 60, 80. The protective layer 90 is formed so as to cover the entire outer surface of the brazing portion 60. That is, the protective layer 90 is formed so as to cover the entire outer surface of the conductive pattern 61, the entire outer surface of the conductive pattern 62, and the entire outer surface of the brazing material 63. The protective layer 90 is formed so as to cover the entire outer surface of the brazing portion 80. That is, the protective layer 90 is formed so as to cover the entire outer surface of the conductive pattern 81, the entire outer surface of the conductive pattern 82, and the entire outer surface of the brazing material 83. The protective layer 90 is formed so as to cover the outer surfaces of the brazing portions 60, 80 around the entire circumferential direction of the base plate 20. The protective layer 90 is formed, for example, so as to continuously cover the brazing portions 60 and 80.

[0037] The protective layer 90 is formed, for example, so as to cover the entire outer surface of the upper portion 22 of the base plate 20. That is, the protective layer 90 is formed so as to cover the entire outer surface of the ceramic plate 52. The protective layer 90 is formed, for example, so as to cover a portion of the outer surface of the electrostatic chuck 70. The protective layer 90 is formed, for example, so as to cover a portion of the outer surface of the substrate main body 71. The protective layer 90 of this embodiment is formed so as to cover the outer surface of the lower portion of the substrate main body 71 and to expose the outer surface of the upper portion of the substrate main body 71.

[0038] The protective layer 90 may be made of, for example, a low-thermal expansion ceramic material. For example, ceramic materials such as aluminum oxide, aluminum nitride, and yttrium oxide may be used for the protective layer 90. For example, fluororesin or epoxy resin, which has excellent plasma resistance, may also be used for the protective layer 90.

[0039] In this embodiment, gas flow path 40 is an example of a first gas flow path, hole 41 is an example of a first hole, holes 42 and 43 are examples of second hole, and gas flow path 73 is an example of a second gas flow path. Ceramic plate 51 is an example of a first ceramic plate, and ceramic plate 52 is an example of a second ceramic plate. Brazing portion 60 is an example of a second brazing portion, conductive pattern 61 is an example of a third conductive pattern, conductive pattern 62 is an example of a fourth conductive pattern, and brazing material 63 is an example of a second brazing material. Brazing portion 80 is an example of a first brazing portion, conductive pattern 81 is an example of a first conductive pattern, conductive pattern 82 is an example of a second conductive pattern, and brazing material 83 is an example of a first brazing material.

[0040] (Manufacturing Method of Substrate Fixing Device 10) Next, a description will be given of a manufacturing method of the substrate holding device 10. For convenience of explanation, the parts that will ultimately become the components of the substrate holding device 10 will be described using the reference numerals of the final components.

[0041] 3, a ceramic plate 51 is prepared, having a conductive pattern 61 for brazing formed on its upper surface. A ceramic plate 52 is prepared, having a conductive pattern 62 for brazing formed on its lower surface and a conductive pattern 81 for brazing formed on its upper surface. An electrostatic chuck 70 is also prepared, having a substrate body 71, having a conductive pattern 82 for brazing formed on its lower surface. These two ceramic plates 51, 52 and the substrate body 71 can be manufactured by, for example, a green sheet method.

[0042] 4, the inlet portion 31, the outlet portion 32 (see FIG. 1), and the recessed portion 33 are formed in the ceramic plate 51, and the hole portion 41 is also formed. The inlet portion 31, the outlet portion 32, the recessed portion 33, and the hole portion 41 can be formed by, for example, laser processing or machining.

[0043] 4, holes 42 and holes 43 are formed in ceramic plate 52. These holes 42 and holes 43 can be formed by, for example, laser processing or machining.

[0044] 4, gas flow paths 73 are formed in the substrate body 71. The gas flow paths 73 can be formed by, for example, laser processing or mechanical processing. Next, ceramic plate 52 is placed above ceramic plate 51 with conductive pattern 62 facing conductive pattern 61. At this time, ceramic plates 51 and 52 are aligned so that hole 42 overlaps with hole 41 in a plan view. Furthermore, substrate main body 71 is placed above ceramic plate 52 with conductive pattern 82 facing conductive pattern 81. At this time, ceramic plate 52 and substrate main body 71 are aligned so that gas flow path 73 overlaps with hole 43 in a plan view.

[0045] Next, in the step shown in FIG. 5 , the conductive patterns 61 and 62 are joined by brazing using a brazing material 63. This allows the ceramic plate 52 to be joined to the upper surface of the ceramic plate 51. Furthermore, the conductive patterns 81 and 82 are joined by brazing using a brazing material 83. This allows the substrate body 71 to be joined to the upper surface of the ceramic plate 52. This step closes the opening of the recess 33 with the ceramic plate 52. As a result, the cooling path 30 is formed by the inlet 31 and outlet 32 ​​(see FIG. 1 ) formed in the ceramic plate 51, the recess 33, and the ceramic plate 52 closing the opening of the recess 33. This step also connects the hole 41 in the ceramic plate 51 with the holes 42 and 43 in the ceramic plate 52 to form the gas flow path 40, and also connects the gas flow path 40 with the gas flow path 73 to form the gas hole 11.

[0046] Through the above manufacturing steps, the base plate 20 having the ceramic plates 51 and 52 is formed, and the electrostatic chuck 70 is bonded onto the base plate 20. Next, a protective layer 90 that covers the brazed portions 60, 80 is formed on the outer surface of the ceramic plate 52 and the outer surface of the substrate main body 71. The protective layer 90 can be formed by, for example, physical vapor deposition or chemical vapor deposition. When a fluororesin or epoxy resin is used as the material for the protective layer 90, the protective layer 90 can be formed, for example, by applying a liquid resin to the outer surface of the ceramic plate 52 and the outer surface of the substrate main body 71 and then curing it.

[0047] Through the above manufacturing steps, the substrate fixing device 10 of this embodiment can be manufactured. Next, the effects of this embodiment will be described. (1) The substrate fixing device 10 includes a base plate 20 made of low thermal expansion ceramic, an electrostatic chuck 70 made of low thermal expansion ceramic and having a mounting surface 71A on which an object to be clamped is mounted, and a brazing portion 80 that joins the base plate 20 and the electrostatic chuck 70. The base plate 20 is made of a ceramic material having a thermal expansion coefficient of 0±1 ppm / K at room temperature. The electrostatic chuck 70 is made of a ceramic material having a thermal expansion coefficient of 0±1 ppm / K at room temperature.

[0048] According to this configuration, both the base plate 20 and the electrostatic chuck 70 are made of a low-thermal-expansion ceramic material. Therefore, even when the substrate-fixing device 10 is exposed to a low temperature of approximately −60° C. or a high temperature of approximately 180° C., the base plate 20 and the electrostatic chuck 70 hardly experience thermal deformation, such as thermal expansion or thermal contraction. Therefore, even when the substrate-fixing device 10 is exposed to a low temperature of approximately −60° C. or a high temperature of approximately 180° C., a large difference between the amount of thermal deformation of the base plate 20 and the amount of thermal deformation of the electrostatic chuck 70 can be effectively prevented. As a result, thermal stress caused by thermal expansion and thermal contraction can be effectively prevented from acting on the brazed portion 80 provided between the base plate 20 and the electrostatic chuck 70. This effectively prevents the brazed portion 80 from being damaged due to thermal stress. Therefore, a decrease in the in-plane uniformity of the thermal resistance of the brazed portion 80 due to damage to the brazed portion 80 can be effectively prevented. Therefore, it is possible to suppress variations in temperature on the mounting surface 71A of the electrostatic chuck 70, and it is possible to improve the uniformity of the temperature on the mounting surface 71A of the electrostatic chuck 70.

[0049] (2) During operation of the substrate fixing device 10, the temperature of the base plate 20 and the temperature of the electrostatic chuck 70 may differ from each other. In this case, even if the base plate 20 and the electrostatic chuck 70 are made of the same ceramic material, if the thermal expansion coefficient of the ceramic material is 6 to 8 ppm / K, thermal stress occurs due to the difference in thermal expansion caused by the temperature difference.

[0050] In contrast, in the substrate fixing device 10 of this embodiment, both the base plate 20 and the electrostatic chuck 70 are made of a low-thermal expansion ceramic material. Therefore, even if the temperature of the base plate 20 and the temperature of the electrostatic chuck 70 are different from each other, the base plate 20 and the electrostatic chuck 70 are hardly thermally deformed. Therefore, it is possible to preferably prevent a large difference from occurring between the amount of thermal deformation of the base plate 20 and the amount of thermal deformation of the electrostatic chuck 70. As a result, it is possible to preferably prevent thermal stress caused by thermal expansion and thermal contraction from acting on the brazing portion 80 that joins the base plate 20 and the electrostatic chuck 70.

[0051] (3) Even when the substrate-fixing device 10 is exposed to a low temperature of about −60° C. or a high temperature of about 180° C., the substrate-fixing device 10 (i.e., the base plate 20, the electrostatic chuck 70, and the brazing portion 80) can be prevented from being damaged. Therefore, a single substrate-fixing device 10 can be suitably used over a wide temperature range.

[0052] (4) A protective layer 90 is formed on the outer surface of the base plate 20 and the outer surface of the electrostatic chuck 70 so as to cover the brazed portions 60, 80. This protective layer 90 can protect the brazed portions 60, 80 from plasma. This can prevent the brazed portions 60, 80 from being deteriorated by plasma, thereby extending the life of the substrate fixing device 10.

[0053] (5) The brazing portion 80 has a conductive pattern 81 formed on the upper surface of the base plate 20, a conductive pattern 82 formed on the lower surface of the electrostatic chuck 70, and a brazing material 83. In this configuration, the conductive patterns 81, 82 are joined by brazing with the brazing material 83, thereby joining the electrostatic chuck 70 onto the base plate 20. The substrate fixing device 10 formed in this manner has a structure including the conductive patterns 81, 82. Therefore, the rigidity of the substrate fixing device 10 can be increased compared to when, for example, the base plate 20 and the electrostatic chuck 70 are joined to each other with an adhesive.

[0054] (6) The base plate 20 is configured by a plurality of ceramic plates 51, 52 joined to one another by brazing portions 60. In this configuration, conductive patterns 61, 62 for brazing are provided on the ceramic plates 51, 52. The conductive patterns 61, 62 are then joined by brazing with a brazing material 63, thereby joining the ceramic plate 52 onto the ceramic plate 51. The base plate 20 thus formed has a structure including the conductive patterns 61, 62. Therefore, the rigidity of the base plate 20 can be increased compared to, for example, a case in which the ceramic plates 51, 52 are joined to one another by an adhesive.

[0055] (7) The plurality of ceramic plates 51, 52 are joined by the brazing portions 60, and the base plate 20 and the electrostatic chuck 70 are joined by the brazing portions 80. With this configuration, the ceramic plates 51, 52 and the substrate body 71 can be joined by the brazing materials 63, 83, etc., which are harder than adhesive. This improves the airtightness of the cooling paths 30 and the gas holes 11 formed in the ceramic plates 51, 52 and the substrate body 71.

[0056] (Other embodiments) The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0057] The structure of the substrate fixing device 10 in the above embodiment can be modified as needed. 6, the protective layer 90 may be formed to cover the entire outer surface of the upper portion 22 of the base plate 20 and the entire outer surface of the electrostatic chuck 70. That is, the protective layer 90 may be formed to cover the entire outer surface of the ceramic plate 52 and the entire outer surface of the substrate body 71.

[0058] 6, the protective layer 90 may be formed to cover the entire outer surface of the lower portion 21 of the base plate 20. In other words, the protective layer 90 may be formed to cover the entire outer surface of the ceramic plate 51.

[0059] The protective layer 90 in the above embodiment may be omitted. The electrostatic chuck 70 of the above embodiment may have a built-in electrode other than the electrode 72. The built-in electrode may be, for example, a heating element for heating a substrate placed on the mounting surface 71A.

[0060] The mounting surface 71A of the electrostatic chuck 70 in the above embodiment may be provided with an embossment. The shape of the gas holes 11 in the substrate fixing device 10 of the above embodiment may be changed as appropriate. Also, the gas holes 11 may be omitted.

[0061] The shape of the cooling passage 30 in the base plate 20 of the above embodiment may be changed as appropriate. Also, the cooling passage 30 may be omitted. In the above embodiment, the base plate 20 and the electrostatic chuck 70 are joined to each other by the brazing portion 80, but this is not limiting. For example, the base plate 20 and the electrostatic chuck 70 may be joined to each other by joining the conductive patterns 81, 82 to each other with a conductive adhesive.

[0062] In the base plate 20 of the above embodiment, the ceramic plates 51, 52 are joined to each other by the brazing portion 60, but this is not limiting. For example, the conductive patterns 61, 62 may be joined to each other by a conductive adhesive. Also, the conductive patterns 61, 62 may be omitted, and the ceramic plates 51, 52 may be joined to each other by an adhesive such as a silicone adhesive.

[0063] In the above embodiment, there is no particular limitation on the number of ceramic plates 51, 52 in the base plate 20. For example, the base plate 20 may have one ceramic plate, or three or more ceramic plates.

[0064] In the manufacturing method of the above embodiment, the recesses 33 and holes 41, 42, 43 are formed in the ceramic plates 51, 52 after the green sheets are fired, but this is not limiting. For example, the recesses 33 and holes 41, 42, 43 may be formed in the green sheets before firing, i.e., before firing.

[0065] In the manufacturing method of the above embodiment, the gas flow passages 73 are formed in the substrate body 71 after the green sheet is fired, but this is not limiting. For example, the gas flow passages 73 may be formed in the green sheet before firing, i.e., before firing.

[0066] The substrate holding device 10 in the above embodiment is applied to semiconductor manufacturing equipment, such as a dry etching device. An example of a dry etching device is a parallel plate reactive ion etching device. The substrate holding device 10 can also be applied to semiconductor manufacturing equipment such as a plasma CVD (Chemical Vapor Deposition) device or a sputtering device. [Explanation of symbols]

[0067] 10 Board fixing device 11 Gas vent 20 base plate 21 Lower 22 Upper 30 Cooling path 31 Introduction 32 Discharge section 33 Recess 40 Gas flow path 41 Hole (1st hole) 42,43 Hole (2nd hole) 51 Ceramic plate (first ceramic plate) 52 Ceramic plate (second ceramic plate) 60 Brazed part (second brazed part) 61 Conductive pattern (third conductive pattern) 62 Conductive pattern (fourth conductive pattern) 63 Brazing filler metal (second brazing filler metal) 70 Electrostatic Chuck 71 Board body 71A mounting surface 72 electrode 73 Gas flow path 80 Brazed part (first brazed part) 81 Conductive pattern (first conductive pattern) 82 Conductive pattern (second conductive pattern) 83 Brazing filler metal (first brazing filler metal) 90 protective layer

Claims

1. A low thermal expansion ceramic base plate and an electrostatic chuck made of low thermal expansion ceramic and having a mounting surface on which an object to be attracted is mounted; a first brazing portion that joins the base plate and the electrostatic chuck; and the base plate is made of a ceramic material having a thermal expansion coefficient of 0±1 ppm / K at room temperature; The electrostatic chuck is made of a ceramic material having a thermal expansion coefficient of 0±1 ppm / K at room temperature.

2. The substrate fixing device according to claim 1 , further comprising a protective layer formed on an outer surface of the base plate and an outer surface of the electrostatic chuck so as to cover the first brazing portion.

3. the base plate has a lower portion and an upper portion stacked on an upper surface of the lower portion; The upper portion has a planar size smaller than the planar size of the lower portion, 3. The substrate fixing device according to claim 2, wherein the protective layer is formed so as to cover the entire outer surface of the upper portion and the entire outer surface of the electrostatic chuck.

4. The first brazing portion is a first conductive pattern formed on an upper surface of the base plate; a second conductive pattern formed on a lower surface of the electrostatic chuck; The substrate fixing device according to claim 1 , further comprising: a first brazing material that joins the first conductive pattern and the second conductive pattern.

5. The base plate is a first ceramic plate; a second ceramic plate provided on the first ceramic plate; a second brazing portion that joins the first ceramic plate and the second ceramic plate, The second brazing portion is a third conductive pattern formed on an upper surface of the first ceramic plate; a fourth conductive pattern formed on the lower surface of the second ceramic plate; The substrate fixing device according to claim 1 , further comprising: a second brazing material that joins the third conductive pattern and the fourth conductive pattern.

6. the base plate has a cooling passage formed by a recess recessed downward from an upper surface of the first ceramic plate and the second ceramic plate provided so as to close an opening of the recess, the third conductive pattern is provided so as to overlap the second ceramic plate in a plan view, The substrate fixing device according to claim 5 , wherein the fourth conductive pattern is provided so as to overlap the third conductive pattern but not to overlap the recess in a plan view.

7. the base plate has a first gas flow path penetrating the base plate in a thickness direction, the electrostatic chuck has a second gas flow passage communicating with the first gas flow passage; the first gas flow path has a first hole portion penetrating the first ceramic plate in a thickness direction, and a second hole portion penetrating the second ceramic plate in a thickness direction and communicating with the first hole portion; The substrate fixing device according to claim 5 , wherein the second gas flow passage is formed to penetrate the electrostatic chuck in a thickness direction and to communicate with the second hole portion.

8. The substrate fixing device of claim 1 , further comprising an electrode built into the electrostatic chuck.

9. 2. The substrate fixing device according to claim 1, wherein said base plate and said electrostatic chuck are made of a ceramic material containing the same material as a main component.

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