Substrate Fixing Device

Abstract

The present invention provides a substrate fixing device, which has a base plate with a gas supply part inside and an electrostatic chuck arranged on the base plate, the electrostatic chuck has a base body whose surface is a supporting surface for an adsorbed object and air holes penetrating the base body, gas is supplied to the supporting surface from the gas supply part via the air holes, the air holes have a first recessed portion recessed from the surface on the opposite side of the supporting surface of the base body toward the supporting surface side, a second recessed portion further recessed from the bottom surface of the first recessed portion toward the supporting surface side, and a through hole penetrating from the bottom surface of the second recessed portion to the supporting surface, a porous body is filled in the entire area within the first recessed portion and the area within the second recessed portion except for the unfilled area, the unfilled area is a recessed portion recessed from the position of the bottom surface of the second recessed portion connected to the through hole toward the surface on the opposite side, and the recess is a space connected to the through hole.

Description

Technical Field

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

[0002] Conventionally, a film forming apparatus (eg, a CVD apparatus, a PVD apparatus, etc.) or a plasma etching apparatus used in manufacturing semiconductor devices such as ICs and LSIs generally has a stage for holding a wafer with high precision in a vacuum processing chamber.

[0003] As such a stage, for example, a substrate fixing device is proposed that adsorbs and holds a wafer as an adsorption object by means of an electrostatic chuck mounted on a base plate. As an example of a substrate fixing device, a device having a structure provided with a gas supply unit for cooling the wafer can be cited. For example, the gas can be supplied to the surface of the electrostatic chuck via a gas flow path inside the base plate and a ceramic porous body and / or a through hole provided on the electrostatic chuck.

[0004] [Patent Document 1: (Japan) Patent Publication No. 2015-195346

[0005] However, when the substrate fixing device is applied to a plasma etching device, abnormal discharge may occur in the electrostatic chuck when the wafer is etched, causing damage to the wafer and / or the plasma etching device itself.

[0006] As a countermeasure for abnormal discharge, providing a ceramic porous body as described above is also effective, but the inventors of the present invention have discovered that, depending on the structure of the connecting portion between the porous body and the through hole, abnormal discharge may occur near (near) the connecting portion between the porous body and the through hole. Summary of the invention

[0007] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to suppress the occurrence of abnormal discharge in a substrate fixing device.

[0008] The present substrate fixing device comprises a base plate with a gas supply portion inside and an electrostatic chuck arranged on the base plate, the electrostatic chuck comprising a base body whose surface is a supporting surface for an adsorbed object and an air hole penetrating the base body, the gas being supplied from the gas supply portion to the supporting surface via the air hole, wherein the air hole comprises a first recessed portion recessed from the surface on the opposite side of the supporting surface of the base body toward the supporting surface side, a second recessed portion recessed from the bottom surface of the first recess further toward the supporting surface side, and a through hole penetrating from the bottom surface of the second recess to the supporting surface, the porous body being filled in the entire area within the first recess and in the area within the second recess except for an unfilled area, the unfilled area being a recessed portion recessed from a position of the bottom surface of the second recess connected to the through hole toward the surface on the opposite side, and the recess being a space connected to the through hole.

[0009] According to the disclosed technology, the occurrence of abnormal discharge can be suppressed in the substrate fixing device. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1A and Figure 1B This is a cross-sectional view schematically illustrating the substrate fixing device according to this embodiment.

[0011] Figure 2 This is a diagram for explaining a porous body.

[0012] FIG. 3A to FIG. 3C This is an illustrative diagram (part 1) of the manufacturing steps of the substrate fixing device according to the present embodiment.

[0013] Figure 4A and Figure 4B This is an illustrative diagram (part 2) of the manufacturing steps of the substrate fixing device according to the present embodiment.

[0014] FIG. 5A to FIG. 5C This is an illustrative diagram of an electrostatic chuck of a substrate fixing device according to a comparative example.

[0015] Fig. 6A and Figure 6B It is an illustrative diagram of the manufacturing steps of the substrate fixing device of the comparative example.

[0016] The reference numerals are described as follows:

[0017] 1 Substrate fixing device

[0018] 10. Bottom Plate

[0019] 10a Upper surface

[0020] 10b Lower surface

[0021] 11 Gas supply unit

[0022] 15 Cooling mechanism

[0023] 20 Adhesive layer

[0024] 30 Electrostatic chuck

[0025] 31 Matrix

[0026] 31a Bearing surface

[0027] 32 Electrostatic Electrode

[0028] 33 Stoma

[0029] 33s Unfilled area

[0030] 60 porous bodies

[0031] 111 Gas flow path

[0032] 112 Gas injection unit

[0033] 113 Gas exhaust part

[0034] 151 Refrigerant flow path

[0035] 152 Refrigerant inlet

[0036] 153 Refrigerant discharge part

[0037] 331, 332 concave part

[0038] 331a, 332a bottom

[0039] 333, 335 through hole

[0040] 333a End face

[0041] 601 Spherical oxide ceramic particles

[0042] 602 Mixed Oxide DETAILED DESCRIPTION

[0043] Hereinafter, the mode for carrying out the invention will be described with reference to the drawings. It should be noted that in each figure, the same components are given the same reference numerals and the repeated description is omitted.

[0044] Figure 1A and Figure 1B is a cross-sectional view schematically illustrating the substrate fixing device of this embodiment. Figure 1A It is the overall picture. Figure 1B yes Figure 1A A partial enlarged view of part A. Figure 1AAs can be seen, the substrate fixing device 1 includes a base plate 10 , an adhesive layer 20 , and an electrostatic chuck 30 as main components.

[0045] The base plate 10 is a component for mounting the electrostatic chuck 30. The thickness of the base plate 10 is, for example, about 20 to 40 mm. The base plate 10 is, for example, formed of aluminum and can be used as an electrode for controlling plasma. By supplying a predetermined high-frequency power to the base plate 10, the energy for causing the generated ions in a plasma state to collide with the wafer adsorbed on the electrostatic chuck 30 can be controlled, thereby enabling efficient etching processing.

[0046] A gas supply unit 11 is provided inside the base plate 10 to supply gas for cooling the wafer attracted and held on the electrostatic chuck 30 . The gas supply unit 11 includes a gas flow path 111 , a gas injection unit 112 , and a gas exhaust unit 113 .

[0047] The gas flow path 111 is, for example, a hole formed in an annular shape inside the base plate 10. The gas injection portion 112 is a hole whose one end is connected to the gas flow path 111 and whose other end is exposed to the outside from the lower surface 10b of the base plate 10, and an inert gas (for example, He, Ar, etc.) can be introduced into the gas flow path 111 from the outside of the substrate fixing device 1. The gas exhaust portion 113 is a hole whose one end is connected to the gas flow path 111 and whose other end is exposed to the outside from the upper surface 10a of the base plate 10 and penetrates the adhesive layer 20, and the inert gas introduced into the gas flow path 111 can be exhausted. The gas exhaust portions 113 are dispersed on the upper surface 10a of the base plate 10 in the plan view. The number of the gas exhaust portions 113 can be appropriately determined according to needs, for example, it can be about dozens to hundreds.

[0048] It should be noted that the plan view refers to a view when the object is observed from the normal direction of the mounting surface 31 a of the base 31 , and the planar shape refers to the shape of the object when it is observed from the normal direction of the mounting surface 31 a of the base 31 .

[0049] A cooling mechanism 15 is provided inside the base plate 10. The cooling mechanism 15 includes a refrigerant (coolant) flow path 151, a refrigerant introduction portion 152, and a refrigerant discharge portion 153. The refrigerant flow path 151 is, for example, a hole formed in an annular shape inside the base plate 10. The refrigerant introduction portion 152 is a hole that is connected to the refrigerant flow path 151 at one end and exposed to the outside from the lower surface 10b of the base plate 10 at the other end, and a refrigerant (for example, cooling water, heat transfer liquid (Gald en) etc.) can be introduced into the refrigerant flow path 151 from the outside of the substrate fixing device 1. The refrigerant discharge portion 153 is a hole that is connected to the refrigerant flow path 151 at one end and exposed to the outside from the lower surface 10b of the base plate 10 at the other end, and the refrigerant introduced into the refrigerant flow path 151 can be discharged.

[0050] The cooling mechanism 15 is connected to a refrigerant control device (not shown) provided outside the substrate fixing device 1. The refrigerant control device (not shown) can introduce the refrigerant into the refrigerant flow path 151 from the refrigerant introduction portion 152, and can discharge the refrigerant from the refrigerant discharge portion 153. By allowing the cooling mechanism 15 to circulate the refrigerant to cool the base plate 10, the wafer adsorbed on the electrostatic chuck 30 can be cooled.

[0051] The electrostatic chuck 30 is a part that sucks and holds a wafer as a suction target. The planar shape of the electrostatic chuck 30 is, for example, circular. The diameter of the wafer as a suction target of the electrostatic chuck 30 is, for example, 8, 12, or 18 inches.

[0052] The electrostatic chuck 30 is provided on the upper surface 10a of the base plate 10 via the adhesive layer 20. The adhesive layer 20 is, for example, a silicone adhesive. The thickness of the adhesive layer 20 is, for example, about 0.1 to 1.0 mm. The adhesive layer 20 can bond the electrostatic chuck 30 and the base plate 10, and has the effect of reducing the stress generated by the difference in thermal expansion coefficient between the ceramic electrostatic chuck 30 and the aluminum base plate 10.

[0053] The electrostatic chuck 30 includes a base 31 and an electrostatic electrode 32. The upper surface of the base 31 is a support surface 31a for an adsorbed object. The electrostatic chuck 30 is, for example, a Johnsen-Rabbeck electrostatic chuck. However, the electrostatic chuck 30 may also be a Coulomb force electrostatic chuck.

[0054] The substrate 31 is a dielectric, and ceramics such as aluminum oxide (Al2O3) and aluminum nitride (AlN) can be used as the substrate 31. The substrate 31 can contain oxides of two or more elements selected from silicon (Si), magnesium (Mg), calcium (Ca), aluminum (Al), and yttrium (Y) as an auxiliary agent. The thickness of the substrate 31 is, for example, about 5 to 10 mm, and the relative dielectric constant (Relative permittivity) (1 kHz) of the substrate 31 is, for example, about 9 to 10.

[0055] The electrostatic electrode 32 is a thin film electrode and is built into the base 31. The electrostatic electrode 32 is connected to a power source provided outside the substrate fixing device 1. When a predetermined voltage is applied from the power source, an adsorption force based on static electricity is generated between the electrostatic electrode 32 and the wafer. Accordingly, the wafer can be adsorbed and held on the carrying surface 31a of the base 31 of the electrostatic chuck 30. As for the adsorption and holding force, the higher the voltage applied to the electrostatic electrode 32, the stronger it is. The electrostatic electrode 32 can be in a monopolar shape or a bipolar shape. As the material of the electrostatic electrode 32, for example, tungsten, molybdenum, etc. can be used.

[0056] A heating element may be disposed inside the base 31 . When a voltage is applied from the outside of the substrate fixing device 1 , the heating element generates heat and heats the support surface 31 a of the base 31 to a predetermined temperature.

[0057] The base 31 is provided with gas holes 33 at positions corresponding to the gas discharge portions 113. The gas can be supplied from the gas supply portion 111 to the placement surface 31a through the gas holes 33.

[0058] The air hole 33 has a concave portion 331 that is recessed from the lower surface 31b, which is the surface on the opposite side of the bearing surface 31a of the base 31, toward the bearing surface 31a, a concave portion 332 that is further recessed from the bottom surface (step surface) 331a of the concave portion 331 toward the bearing surface 31a, and a through hole 333 that penetrates from the bottom surface (step surface) 332a of the concave portion 332 to the bearing surface 31a. The concave portion 331, the concave portion 332, and the through hole 333 are, for example, concentrically arranged and interconnected. In a plan view, the size of the concave portion 332 is smaller than that of the concave portion 331, and the size of the through hole 333 is smaller than that of the concave portion 332. However, the size of the concave portion 332 may be the same as that of the concave portion 331 or the same as that of the through hole 333.

[0059] The planar shapes of the recess 331, the recess 332, and the through hole 333 are, for example, circular. In this case, the inner diameter of the recess 332 is smaller than the inner diameter of the recess 331, and the inner diameter of the through hole 333 is smaller than the inner diameter of the recess 332. The inner diameter of the recess 331 is, for example, about 1 mm to 5 mm. The inner diameter of the recess 332 is, for example, about 0.8 mm to 4.8 mm. The inner diameter of the through hole 333 is, for example, about 0.6 mm to 3.2 mm. As an example of a combination of the inner diameters of the recess 331, the recess 332, and the through hole 333, for example, the inner diameter of the recess 331 = 2 mm, the inner diameter of the recess 332 = 0.8 mm, and the inner diameter of the through hole 333 = 0.6 mm. The following describes an example in which the planar shapes of the recess 331, the recess 332, and the through hole 333 are circular.

[0060] The depth of the recess 331 is, for example, about 4 mm to 8 mm. The depth of the recess 332 is, for example, about 50 μm to 500 μm. The depth of the through hole 333 is, for example, about 1.3 mm to 1.7 mm.

[0061] The entire area in the recess 331 and the area in the recess 332 except the unfilled area 33s are filled with the porous body 60. The through hole 333 is not filled with the porous body 60. The unfilled area 33s is a recessed portion that is recessed from the position of the bottom surface 332a of the recess 332 that is connected to the through hole 333 toward the lower surface 31b side of the substrate 31, and is a space connected to the through hole 333. The planar shape of the unfilled area 33s is circular, and the inner diameter of the unfilled area 33s is substantially the same as the inner diameter of the through hole 333. The unfilled area 33s does not enter the recess 331. In other words, the depth of the unfilled area 33s is shallower than the depth of the recess 332. The depth of the unfilled area 33s can be any depth as long as it is shallower than the depth of the recess 332.

[0062] It should be noted that the through hole 333 and the unfilled area 33s are integrally formed space portions, but for the sake of convenience, the side of the bearing surface 31a relative to the bottom surface 332a of the recess 332 is called the through hole 333, and the side of the recess 331 relative to the bottom surface 332a of the recess 332 is called the unfilled area 33s.

[0063] like Figure 2 As shown, the porous body 60 includes a plurality of spherical oxide ceramic particles 601 and a mixed oxide 602 that integrates the plurality of spherical oxide ceramic particles 601 .

[0064] The diameter of the spherical oxide ceramic particles 601 is, for example, in the range of 30 μm to 1000 μm. A preferred example of the spherical oxide ceramic particles 601 is spherical aluminum oxide particles. The spherical oxide ceramic particles 601 are preferably contained in the porous body 60 at a weight ratio of 80 wt % or more (97 wt % or less).

[0065] The mixed oxide 602 is fixed to a part of the outer surface (spherical surface) of the plurality of spherical oxide ceramic particles 601 and supports the particles. The mixed oxide 602 is formed of oxides of two or more elements selected from silicon (Si), magnesium (Mg), calcium (Ca), aluminum (Al) and yttrium (Y), for example.

[0066] The porous body 60 has pores P formed inside. The pores P are connected to the outside in a manner that allows gas to pass from the bottom to the top of the porous body 60. The porosity of the pores P formed in the porous body 60 is preferably in the range of 20% to 50% of the entire volume of the porous body 60. On the inner surface of the pores P, a portion of the outer surface of the spherical oxide ceramic particles 601 and the mixed oxide 602 are exposed.

[0067] It should be noted that, when the substrate 31 is formed of aluminum oxide, the substrate 31 preferably contains oxides of two or more elements selected from silicon, magnesium, calcium, and yttrium as other components. In addition, the composition ratio of the oxides of two or more elements selected from silicon, magnesium, calcium, and yttrium in the substrate 31 is preferably set to be the same as the composition ratio of the oxides of two or more elements selected from silicon, magnesium, calcium, and yttrium in the mixed oxide 602 of the porous body 60.

[0068] Thus, by making the oxide composition ratios of the substrate 31 and the mixed oxide 602 of the porous body 60 the same, when the porous body 60 is sintered, no material migration occurs between the substrate 31 and the porous body 60, thereby ensuring the flatness of the interface between the substrate 31 and the porous body 60.

[0069] [Method for manufacturing substrate fixing device]

[0070] FIG. 3A to FIG. 3B and Figure 4A and Figure 4B is an illustrative diagram of the manufacturing steps of the substrate fixing device of this embodiment, showing Figure 1B Here, refer to FIG. 3A to FIG. 3B and Figure 4A and Figure 4B , the description will focus on the steps of forming the air holes 33 on the electrostatic chuck 30.

[0071] First, a substrate 31 having an electrostatic electrode 32 built therein is manufactured by a well-known manufacturing method including the steps of processing a through hole in a green sheet, filling a conductive paste in the through hole, forming a pattern as an electrostatic electrode, stacking and firing other green sheets, and flattening the surface.

[0072] Then, if Figure 3A As shown, a recess 331 is formed from the lower surface 31b of the base 31 toward the side of the bearing surface 31a. As for the recess 331, as described above, for example, the plane shape is circular, the inner diameter is about 1mm to 5mm, and the depth is about 4mm to 8mm. The recess 331 can be formed at a position corresponding to the gas discharge portion 113 of the bottom plate 10 by drilling, for example, and the number of the recesses 331 corresponds to the gas discharge portion 113.

[0073] Next, if Figure 3BAs shown, a concave portion 332 is formed which is further recessed from the bottom surface 331a of the concave portion 331 toward the side of the bearing surface 31a. As for the concave portion 332, as described above, for example, the planar shape is a circle with a smaller diameter than the concave portion 331, the inner diameter is about 0.8mm to 4.8mm, and the depth is about 50μm to 500μm. The concave portion 332 can be formed concentrically with the concave portion 331 by drilling, for example.

[0074] Afterwards, if Figure 3C As shown in FIG. 1 , a through hole 335 is formed which penetrates from the bottom surface 332a of the recessed portion 332 to the bearing surface 31a. For example, the through hole 335 has a planar shape with a diameter smaller than that of the through hole 333 (see FIG. 1 ). Figure 1B ) is circular, with an inner diameter of about 0.3 mm to 1.6 mm and a depth of about 1.3 mm to 1.7 mm. The through hole 335 is formed, for example, by drilling to be concentric with the recesses 331 and 332. It should be noted that Figure 3B The steps shown and Figure 3C The order of the steps shown may also be reversed.

[0075] Next, if Figure 4A As shown, a porous body 60 is formed in the recesses 331 and 332. The porous body 60 can be formed by filling the paste as the precursor of the porous body 60 into the recesses 331 and 332 using a squeegee or the like and sintering. In the case where a part of the porous body 60 protrudes from the lower surface 31b side of the substrate 31, the end face of the porous body 60 is made substantially flush with the lower surface 31b of the substrate 31 by grinding or the like. Here, as for the through hole 335, when the paste as the precursor of the porous body 60 is filled into the recesses 331 and 332, it is necessary to serve as an escape path for air, thereby playing a role in promoting the filling of the paste. It should be noted that a part of the porous body 60 can enter the through hole 335, but if the inner diameter of the through hole 335 is large, the paste will flow out, so it is preferred to appropriately reduce the inner diameter of the through hole 335.

[0076] The paste as the precursor of the porous body 60 contains, for example, spherical aluminum oxide particles at a predetermined weight ratio. The remainder of the paste contains, for example, oxides of two or more elements selected from silicon, magnesium, calcium, aluminum, and yttrium, and further contains an organic binder and / or a solvent. As the organic binder, for example, polyvinyl butyral can be used. As the solvent, for example, alcohol can be used.

[0077] Next, a base plate 10 on which a cooling mechanism 15 and the like are formed in advance is prepared, and an adhesive layer 20 (uncured) is formed on the base plate 10. Figure 4AThe structure shown is arranged on the base plate 10 via the adhesive layer 20, and the adhesive layer 20 is cured.

[0078] Afterwards, if Figure 4B As shown, at the position where the through hole 335 is formed, a through hole 333 having a larger diameter than the through hole 335 is formed. By enlarging and opening the through hole 335 to form the through hole 333, the flow rate of the gas supplied from the bottom plate 10 side to the carrying surface 31a side can be increased compared to the case where the through hole 333 is not formed, and the temperature controllability of the wafer can be improved.

[0079] The through hole 333 is, for example, a circular shape with a diameter larger than the through hole 335 and smaller than the recess 332, with an inner diameter of about 0.6 mm to 3.2 mm and a depth of about 1.3 mm to 1.7 mm. The through hole 333 can be formed concentrically with the recesses 331 and 332 by drilling, for example.

[0080] The end surface 333a of the through hole 333 in the base 31 is formed to enter the recess 332. That is, the end surface 333a of the through hole 333 is located between the bottom surface 332a of the recess 332 and the bottom surface 331a of the recess 331 in the thickness direction of the base 31. According to this, a recessed portion is formed from the position of the bottom surface 332a of the recess 332 connected to the through hole 333 toward the lower surface 31b side of the base 31, and the recessed portion is a space connected to the through hole 333, that is, an unfilled area 33s.

[0081] It should be noted that as long as it can be located in the recess 332, the end face 333a in the base 31 is not necessarily a plane. For example, it can also be a mortar-shaped surface that is recessed toward the bottom face 331a of the recess 331 near the central part corresponding to the shape of the tip of the drill bit.

[0082] Through the above steps, you have completed Figure 1A and Figure 1B The production of the substrate fixing device 1 shown.

[0083] Here, the effects of the substrate fixing device 1 will be described with reference to a comparative example. FIG. 5A to FIG. 5C FIG. 2 is an illustrative diagram of an electrostatic chuck of a substrate fixing device of a comparative example. Figure 5A to Figure 5C As shown, the electrostatic chuck 30X of the substrate fixing device of the comparative example is different from the electrostatic chuck 30 of the substrate fixing device 1 (see FIG. 1 ) in that the air hole 33 is replaced by the air hole 33X. Figure 1A and Figure 1B etc.) are different.

[0084] The air hole 33X of the substrate fixing device 1X does not have the recessed portion 332. The air hole 33X is composed of a recessed portion 331 and a through hole 333 that penetrates from the bottom surface 331a of the recessed portion 331 to the supporting surface 31a. The recessed portion 331 and the through hole 333 are, for example, arranged concentrically and communicated with each other. In a plan view, the size of the through hole 333 is smaller than that of the recessed portion 331. In addition, the size range of the recessed portion 331 and the through hole 333 is the same as that of the substrate fixing device 1.

[0085] When making the substrate fixing device 1X, just execute FIG. 3A to FIG. 3C and Figure 4A and Figure 4B The steps shown are as follows Figure 3B All the steps except

[0086] In the case of the electrostatic chuck 30X, manufacturing variations can result in Figure 5A to Figure 5C Three states are shown. Figure 5A This is the ideal state for the electrostatic chuck 30X. Figure 5A In the embodiment, the entire area inside the recess 331 is filled with the porous body 60 , and the inner diameter of the through hole 333 is constant.

[0087] Compared to Figure 5A , Figure 5B In the embodiment, although the entire area in the recess 331 is filled with the porous body 60, the inner diameter of the through hole 333 is not constant. Specifically, the portion of the through hole 333 that communicates with the recess 331 becomes a small diameter portion 333x.

[0088] The small diameter portion 333x is formed by Fig. 6A and Figure 6B Made according to the steps shown. Fig. 6A and Figure 6B This is the same step as that of FIG. 4 for the substrate fixing device 1 . Fig. 6A In the step of filling the recess 331 with the porous body 60 . Figure 6B In the step of forming the through hole 333 by drilling, however, due to manufacturing deviation, the tip of the drill bit 500 does not reach the bottom surface 331a of the recess 331, so the recess 331 side of the through hole 335 is not processed and remains as the small diameter portion 333x. In other words, the inner diameter of the small diameter portion 333x is equal to Fig. 6A The through hole 335 in the steps is the same.

[0089] Once the small diameter portion 333x is formed, the flow rate of the gas supplied from the bottom plate 10 side to the bearing surface 31a side will be reduced, so it is not preferred from the perspective of reducing the cooling capacity of the wafer. Therefore, in the actual manufacturing steps, in order to avoid the formation of the small diameter portion 333x, it is necessary to leave enough margin to allow the tip of the drill bit 500 to drop above the design value. Figure 5C As shown, although the small diameter portion 333 x is not formed, an unfilled region 33 t which is not filled with the porous body 60 is formed in the recess 331 .

[0090] The unfilled area 33t is a recessed portion that is recessed from the position of the bottom surface 331a of the recessed portion 331 that is connected to the through hole 333 toward the lower surface 31b side of the base 31, and is a space that is connected to the through hole 333. The planar shape of the unfilled area 33t is circular, and the inner diameter of the unfilled area 33t is substantially the same as the inner diameter of the through hole 333.

[0091] The unfilled area 33t is due to Figure 6B In the step of , the tip of the drill bit 500 reaches a position beyond the bottom surface 331a of the recess 331, resulting in a space formed by removing a portion of the porous body 60. Once a space is formed on a portion of the recess 331, abnormal discharge may occur near the space. This is a phenomenon discovered by the inventor of the present invention.

[0092] In this way, Figure 6B In the step of reducing the diameter of the drill bit 500, if a sufficient margin is left to allow the tip of the drill bit 500 to drop to a value greater than the design value in order to avoid forming the small diameter portion 333x, the shape of the air hole 33X will become Figure 5C If the shape of the air hole 33X is Figure 5A In the ideal state shown, there will be no problems such as reduction in gas flow and abnormal discharge.

[0093] However, in the substrate fixing device 1 of the present embodiment, the recess 332 is arranged between the recess 331 and the through hole 333. Therefore, if the depth of the recess 332 is set deeper than the range in which the position of the tip of the drill 500 can be controlled, even if the position of the tip of the drill 500 deviates, the unfilled area 33s will always be located in the recess 332 and will not enter the recess 331.

[0094] In the case where the central portion of the tip of the drill bit 500 is in a pointed shape, the protrusion is generally 50 μm or less. For this reason, in the case where the position of the tip of the drill bit 500 can be controlled with very high accuracy, the depth of the recess 332 can be 50 μm. On the other hand, in the process of managing the manufacturing steps, it is preferred to determine the depth of the recess 332 in such a way that the tip of the drill bit 500 does not enter the recess 331 even if the position of the tip of the drill bit 500 deviates. In this case, a depth of 500 μm for the recess 332 is sufficient. That is, the depth of the recess 332 is preferably greater than 50 μm and less than 500 μm.

[0095] According to the research of the inventors of the present invention, abnormal discharge occurs when the unfilled area 33s enters the concave portion 331, but abnormal discharge does not occur if the unfilled area 33s is located in the concave portion 332. That is, in the substrate fixture 1 in which the unfilled area 33s does not reach the concave portion 331 and the entire area in the concave portion 331 is filled with the porous body 60, the occurrence of abnormal discharge can be suppressed compared to the conventional substrate fixture shown in the comparative example.

[0096] Although the preferred embodiments and the like have been described in detail above, the present invention is not limited to the above embodiments and the like, and various modifications and substitutions may be made to the above embodiments and the like without departing from the scope described in the claims.

[0097] For example, as the suction target of the substrate fixing device of the present invention, in addition to semiconductor wafers (silicon wafers, etc.), glass substrates used in the manufacturing process of liquid crystal panels, etc. can be listed.

[0098] Based on the above, a substrate fixing device can be provided, comprising a base plate with a gas supply portion inside and an electrostatic chuck arranged on the base plate, the electrostatic chuck comprising a base body whose surface is a supporting surface for an adsorbed object and an air hole penetrating the base body, the gas is supplied to the supporting surface from the gas supply portion via the air hole, the air hole comprising a first recessed portion recessed from the surface on the opposite side of the supporting surface of the base body toward the supporting surface side, a second recessed portion recessed from the bottom surface of the first recess further toward the supporting surface side, and a through hole penetrating from the bottom surface of the second recess to the supporting surface, the porous body fills the entire area within the first recess and the area within the second recess except for the unfilled area, the unfilled area being a recessed portion recessed from the position of the bottom surface of the second recess connected to the through hole toward the surface on the opposite side, and the recess is a space connected to the through hole.

[0099] In a plan view, the size of the second recess is smaller than that of the first recess, and the size of the through hole is smaller than that of the second recess.

[0100] The second recess has a depth of 50 μm or more and 500 μm or less.

[0101] The porous body includes a plurality of communicating pores, and the gas is supplied through the plurality of communicating pores.

[0102] The substrate and the porous body include the same oxide ceramic.

[0103] The oxide ceramic is aluminum oxide.

[0104] The matrix and the porous body contain oxides of the same two or more elements, and a composition ratio of the oxides in the matrix is ​​set to be the same as a composition ratio of the oxides in the porous body.

[0105] The two or more elements may be selected from silicon, magnesium, calcium and yttrium.

[0106] An electrostatic chuck may also be provided, comprising: a substrate having a first surface for adsorbing an object and a second surface located on the opposite side of the first surface, the substrate including a through hole, the through hole having a first opening on the first surface and a second opening on the second surface, the through hole having a stepped tapering shape tapering toward the first opening, and a first step surface (331a) and a second step surface (332a) closer to the first surface than the first step surface are formed in the substrate; and a porous body embedded in the substrate from the second opening to the second step surface. The end surface of the porous body that is in direct contact with the second step surface includes a recessed portion facing the second opening.

[0107] The recessed portion is exposed to the outside of the electrostatic chuck through the first opening.

[0108] The first step surface and the second step surface both face the second opening.

[0109] The electrostatic chuck also has an electrostatic electrode disposed inside the base.

[0110] In addition, a substrate fixing device may be provided, comprising: a base plate having a gas supply unit therein; and the electrostatic chuck as described above located on the base plate, wherein the gas can be supplied from the gas supply unit to the first surface via the through hole in which the porous body is provided.

[0111] Finally, it should be noted that although the embodiments of the present invention have been described above, the above contents are not intended to limit the present invention.

Claims

1. A substrate fixing device, comprising: A bottom plate having a gas supply inside; and An electrostatic chuck is disposed on the base plate, The electrostatic chuck has: A substrate having a surface serving as a support surface for an adsorbed object, wherein the substrate is a dielectric; and Pores penetrating the substrate, The gas is supplied from the gas supply unit to the carrying surface through the gas hole. in, The pores have: a first recessed portion recessed from a surface of the base body on the opposite side of the support surface toward the support surface; A second recessed portion further recessed from the bottom surface of the first recessed portion toward the mounting surface; and a through hole extending from the bottom surface of the second recess to the support surface; The porous body is filled in the entire area of ​​the first recess and in the area of ​​the second recess except for the unfilled area. The unfilled region is a recessed portion that is recessed from a position of the bottom surface of the second recessed portion that is connected to the through hole toward the surface on the opposite side, and the recessed portion is a space that is connected to the through hole. The bottom of the recessed portion is located between the bottom surface of the first recessed portion and the bottom surface of the second recessed portion in the thickness direction of the base.

2. The substrate fixing device according to claim 1, wherein: In a plan view, the size of the second recess is smaller than that of the first recess, and the size of the through hole is smaller than that of the second recess.

3. The substrate fixing device according to claim 1 or 2, wherein: The second recess has a depth of 50 μm or more and 500 μm or less.

4. The substrate fixing device according to claim 1 or 2, wherein: The porous body has a plurality of interconnected pores. The gas is supplied through the plurality of gas holes that are in communication.

5. The substrate fixing device according to claim 1 or 2, wherein: The substrate and the porous body include the same oxide ceramic.

6. The substrate fixing device according to claim 5, wherein: The oxide ceramic is aluminum oxide.

7. The substrate fixing device according to claim 1 or 2, wherein: The substrate and the porous body contain oxides of the same two or more elements, The composition ratio of the oxide in the matrix is ​​set to be the same as the composition ratio of the oxide in the porous body.

8. The substrate fixing device according to claim 7, wherein: The two or more elements are selected from silicon, magnesium, calcium and yttrium.

9. An electrostatic chuck, comprising: A substrate having a first surface for adsorbing an object and a second surface located on the opposite side of the first surface, the substrate being a dielectric, the substrate including a through hole, the through hole having a first opening on the first surface and a second opening on the second surface, the through hole having a stepped tapered shape tapering toward the first opening, and a first step surface and a second step surface closer to the first surface than the first step surface are formed in the substrate; and a porous body embedded in the base from the second opening to the second step surface, in, The end surface of the porous body directly in contact with the second step surface includes a recessed portion facing the second opening. The bottom of the recessed portion is located between the first step surface and the second step surface in the thickness direction of the base.

10. The electrostatic chuck of claim 9, wherein: The recessed portion is exposed to the outside of the electrostatic chuck through the first opening.

11. The electrostatic chuck of claim 9, wherein: The first step surface and the second step surface both face the second opening.

12. The electrostatic chuck of claim 9, further comprising: The electrostatic electrode is arranged inside the substrate.

13. A substrate fixing device, comprising: a bottom plate having a gas supply portion therein; and an electrostatic chuck as claimed in claim 9 located on the bottom plate, in, Gas is supplied from the gas supply portion to the first surface via the through-hole in which the porous body is provided.

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