Electrostatic chuck

Abstract

An electrostatic chuck capable of suppressing variations in the in-plane temperature distribution of a substrate during processing. An electrostatic chuck 10 includes a dielectric substrate 100 and a base plate 200 bonded to the dielectric substrate 100. A coolant flow path 250 through which a coolant passes and a lift pin hole 260 are formed in the base plate 200. A protrusion 270 is provided in a portion of the coolant flow path 250 near the lift pin hole 260 to generate turbulence in the flow of the coolant.

Description

[Technical field]

[0001] The present invention relates to an electrostatic chuck. [Background technology]

[0002] For example, in semiconductor manufacturing equipment such as an etching device, an electrostatic chuck is provided as a device for attracting and holding a substrate such as a silicon wafer to be processed. The electrostatic chuck includes a dielectric substrate provided with an attracting electrode and a base plate for supporting the dielectric substrate, which are joined together. When a voltage is applied to the attracting electrode, an electrostatic force is generated, and the substrate placed on the dielectric substrate is attracted and held.

[0003] During processing such as etching, it is necessary to maintain the temperature of the substrate at an appropriate temperature. For this reason, as described in Patent Document 1 below, a coolant flow path for passing a coolant is formed inside the base plate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-028960 Summary of the Invention [Problem to be solved by the invention]

[0005] In addition to the above-mentioned coolant flow paths, the base plate is also provided with a plurality of through holes, such as holes for passing lift pins and holes for supplying an inert gas such as helium gas to the substrate side.

[0006] In the area of ​​the dielectric substrate directly above the through hole formed in the base plate, heat is not easily transferred to the base plate side, which may cause a localized temperature rise in that area, resulting in uneven temperature distribution within the substrate.

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrostatic chuck capable of suppressing variations in the in-plane temperature distribution of a substrate during processing. [Means for solving the problem]

[0008] In order to solve the above problems, the electrostatic chuck according to the present invention includes a dielectric substrate having a mounting surface on which an object to be attracted is mounted, and a base plate joined to the dielectric substrate. The base plate is formed with a coolant flow path through which a coolant passes and a through hole extending in a direction perpendicular to the mounting surface. A turbulence generating portion is provided in a portion of the coolant flow path near the through hole to generate turbulence in the flow of the coolant.

[0009] In an electrostatic chuck having such a configuration, the coolant passing through the coolant flow passage generates turbulence when passing through the turbulence generating portion, and passes through the portion near the through hole in this state. The portion of the base plate near the through hole is cooled more efficiently than in a case where the turbulence generating portion is not present, and the temperature is reduced. As a result, a local temperature rise is unlikely to occur directly above the through hole, and the variation in the in-plane temperature distribution of the substrate can be suppressed. Effect of the Invention

[0010] According to the present invention, it is possible to provide an electrostatic chuck capable of suppressing variations in the in-plane temperature distribution of a substrate during processing. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view illustrating a schematic configuration of an electrostatic chuck according to a first embodiment. [Diagram 2] 5A and 5B are diagrams illustrating a configuration of a coolant flow path formed in a base plate. [Diagram 3] 3 is an enlarged view showing the configuration of a portion of the refrigerant flow path in FIG. 2 near a through hole. [Figure 4] FIG. 4 is a diagram illustrating a schematic flow of a refrigerant in a refrigerant flow path. [Diagram 5] 13 is an enlarged view showing the configuration of a portion of a refrigerant flow path according to a second embodiment, in the vicinity of a through hole. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components in each drawing are denoted by the same reference numerals as much as possible, and duplicated description will be omitted.

[0013] A first embodiment will be described. An electrostatic chuck 10 according to this embodiment is configured to electrostatically attract and hold a substrate W to be processed inside a semiconductor manufacturing apparatus (not shown), such as an etching apparatus. The substrate W to be attracted is, for example, a silicon wafer. The electrostatic chuck 10 may be used in an apparatus other than a semiconductor manufacturing apparatus.

[0014] 1 shows, in a schematic cross-sectional view, the configuration of an electrostatic chuck 10 in a state in which the electrostatic chuck 10 attracts and holds a substrate W. The electrostatic chuck 10 includes a dielectric substrate 100 and a base plate 200.

[0015] The dielectric substrate 100 is a substantially disk-shaped member made of a sintered ceramic body. The dielectric substrate 100 contains, for example, high-purity aluminum oxide (Al2O3), but may contain other materials. The purity, type, and additives of the ceramics in the dielectric substrate 100 can be appropriately set in consideration of the plasma resistance and other properties required of the dielectric substrate 100 in semiconductor manufacturing equipment.

[0016] 1 of the dielectric substrate 100 is a "mounting surface" on which the substrate W is placed. Also, a lower surface 120 of the dielectric substrate 100 in FIG. 1 is a "joined surface" that is joined to the base plate 200 via a joining layer 300. The viewpoint when the electrostatic chuck 10 is viewed from the side of the surface 110 along a direction perpendicular to the surface 110 will hereinafter be referred to as a "top view".

[0017] An adsorption electrode 130 is embedded inside the dielectric substrate 100. The adsorption electrode 130 is a thin, flat layer made of a metal material such as tungsten, and is disposed so as to be parallel to the surface 110. The material of the adsorption electrode 130 may be molybdenum, platinum, palladium, or the like, in addition to tungsten. When a voltage is applied to the adsorption electrode 130 from the outside, an electrostatic force is generated between the surface 110 and the substrate W, thereby adsorbing and holding the substrate W. Only one adsorption electrode 130 may be provided as a so-called "monopolar" electrode as in this embodiment, or two may be provided as so-called "bipolar" electrodes.

[0018] A power supply terminal 132 is embedded in the surface 120 of the dielectric substrate 100. The power supply terminal 132 is a terminal for receiving a voltage to be applied to the chucking electrode 130 from the outside. The power supply terminal 132 has a circular shape when viewed from above. The power supply terminal 132 and the chucking electrode 130 are electrically connected by a via 131. The via 131 is a long and narrow hole filled with a conductor. One end of a bus bar 13, which is a rod-shaped conductive member, is connected to the power supply terminal 132. A voltage is applied to the chucking electrode 130 from the outside via the bus bar 13. The bus bar 13 is drawn out to the outside through a through hole 240 formed in the base plate. The configuration of the electric path for applying a voltage to the chucking electrode 130 may be different from that described above.

[0019] 1, a space SP is formed between the dielectric substrate 100 and the substrate W. When a process such as etching is performed in the semiconductor manufacturing apparatus, helium gas for temperature adjustment is supplied from the outside to the space SP through the gas hole 114. By providing helium gas between the dielectric substrate 100 and the substrate W, the thermal resistance between them is adjusted, and the temperature of the substrate W is thereby maintained at an appropriate temperature. The temperature adjustment gas supplied to the space SP may be a type of gas other than helium.

[0020] A seal ring 111 and dots 112 are provided on a surface 110 which is a mounting surface, and the above-mentioned space SP is formed around these.

[0021] The seal ring 111 is a wall that divides the space SP at the outermost position. The upper end of the seal ring 111 forms part of the surface 110 and abuts against the substrate W. Note that a plurality of seal rings 111 may be provided to divide the space SP. With this configuration, it is possible to individually adjust the pressure of the helium gas in each space SP and make the surface temperature distribution of the substrate W during processing more uniform.

[0022] 1, the portion marked with the reference symbol "116" is the bottom surface of the space SP. Hereinafter, this portion will also be referred to as the "bottom surface 116." The seal ring 111, together with the dots 112 described below, is formed by digging down a part of the surface 110 to the position of the bottom surface 116.

[0023] The dots 112 are circular protrusions protruding from the bottom surface 116. A plurality of dots 112 are provided and are distributed approximately evenly on the mounting surface of the dielectric substrate 100. The upper end of each dot 112 forms part of the surface 110 and abuts against the substrate W. By providing a plurality of such dots 112, bending of the substrate W is suppressed.

[0024] Gas holes 114 are formed in the dielectric substrate 100. The gas holes 114 are holes for supplying helium gas to the space SP, and are circular through-holes formed to extend perpendicularly to the surface 110. A plurality of gas holes 114 are formed, but only one of them is shown in Fig. 1. Helium gas supplied from the outside passes through gas holes 214 formed in the base plate 200, and is then supplied to the space SP through each gas hole 114.

[0025] A porous body made of, for example, alumina may be disposed inside the gas hole 114. With such a configuration, it is possible to suppress the occurrence of dielectric breakdown in the path through the gas hole 114 while ensuring the flow of gas through the gas hole 114.

[0026] The base plate 200 is a substantially disk-shaped member that supports the dielectric substrate 100. The base plate 200 is formed of a metal material such as aluminum. The upper surface 210 of the base plate 200 in FIG. 1 is a "bonded surface" that is bonded to the dielectric substrate 100 via a bonding layer 300.

[0027] The bonding layer 300 is a layer provided between the dielectric substrate 100 and the base plate 200, and bonds the two together. The bonding layer 300 is formed by curing an adhesive made of an insulating material. In this embodiment, a silicone adhesive is used as the adhesive. However, the bonding layer 300 may be formed by curing another type of adhesive. In any case, it is preferable to use a material with as high a thermal conductivity as possible as the material for the bonding layer 300 so that the thermal resistance between the dielectric substrate 100 and the base plate 200 is small.

[0028] An insulating film may be formed on the surface of the base plate 200. For example, an alumina film formed by thermal spraying can be used as the insulating film. By covering the surface of the base plate 200 with the insulating film, the dielectric strength of the base plate 200 can be increased.

[0029] In the base plate 200, a plurality of through holes are formed so as to extend in a direction perpendicular to the surface 110. Such through holes include the gas holes 114 and through holes 240 described above, as well as lift pin holes 260 (see FIG. 2) not shown in FIG. 1. All of these are circular through holes formed so as to penetrate the entire base plate 200.

[0030] A coolant flow path 250 for passing a coolant is formed inside the base plate 200. When a process such as etching is performed in the semiconductor manufacturing apparatus, a coolant is supplied to the coolant flow path 250 from the outside, thereby cooling the base plate 200. Heat generated in the substrate W during the process is transferred to the coolant via the helium gas in the space SP, the dielectric substrate 100, and the base plate 200, and is discharged to the outside together with the coolant. The coolant is supplied to and discharged from the coolant flow path 250 via openings 251, 252 (not shown in FIG. 1, see FIG. 2) formed in the surface 220 of the base plate 200 opposite to the surface 210.

[0031] The configuration of the refrigerant flow path 250 will be described. Fig. 2 shows a schematic top view of the configuration of the refrigerant flow path 250 formed inside the base plate 200. As described above, openings 251 and 252 are provided on the surface 220 of the base plate 200. The refrigerant flow path 250 connects between the openings 251 and 252, and is formed along a path that passes through substantially the entire base plate 200 in the top view.

[0032] Both of the openings 251 and 252 are circular openings when viewed from above, and are formed to extend perpendicularly to the surface 220 from the surface 220 toward the coolant flow path 250. In this embodiment, a coolant is supplied from the outside to the opening 251. The coolant that has passed through the coolant flow path 250 and is used to cool the substrate W is discharged from the opening 252 to the outside.

[0033] FIG. 2 illustrates a lift pin hole 260 among a plurality of through holes formed in the base plate 200. The lift pin hole 260 is a hole for inserting a lift pin (not shown) provided in a semiconductor manufacturing device. A total of three lift pin holes 260 are formed, and are arranged at equal intervals of 120 degrees when viewed from above. The substrate W is attached to and detached from the surface 110 of the dielectric substrate 100 by the lift pin that moves up and down through the lift pin hole 260. The lift pin hole 260 is a part of a through hole formed to penetrate the entire electrostatic chuck 10, similar to the gas hole 214 shown in FIG. 1. In FIG. 2, other through holes (such as the gas hole 214 and the through hole 240) formed in the base plate 200 are omitted from illustration.

[0034] Each lift pin hole 260 is formed at a position that does not overlap with the coolant flow path 250 when viewed from above. Range A shown in Fig. 2 includes one lift pin hole 260 and a portion of the coolant flow path 250 near the lift pin hole 260. Fig. 3 shows a schematic configuration of the inner portion of range A of the base plate 200 when viewed from above.

[0035] 3 is an imaginary line that passes through the center of the lift pin hole 260 and extends in a direction perpendicular to the direction in which the coolant flows through the coolant flow path 250. The portion of the coolant flow path 250 that intersects with the dotted line DL0 can be said to be the portion that is closest to the lift pin hole 260.

[0036] 3 is an imaginary line that passes through a position on the upstream side of dotted line DL0 along the direction of the refrigerant flow in refrigerant flow path 250 and extends in a direction perpendicular to the same direction. Dotted line DL2 is an imaginary line that passes through a position on the downstream side of dotted line DL0 along the direction of the refrigerant flow in refrigerant flow path 250 and extends in a direction perpendicular to the same direction.

[0037] In the refrigerant flow path 250, a protrusion 270 is formed at a position indicated by a dotted line DL1 and a position indicated by a dotted line DL2. The protrusion 270 is a rectangular region that is a part of the inner wall surface of the refrigerant flow path 250 protruding toward the inside of the refrigerant flow path 250. In this embodiment, the protrusion 270 is formed so as to protrude from the bottom surface (the inner wall surface on the face 220 side) of the refrigerant flow path 250, but may be formed in another part. The protrusion 270 formed at the position of the dotted line DL1 is also referred to as a "protrusion 271" below. The protrusion 270 formed at the position of the dotted line DL2 is also referred to as a "protrusion 272" below.

[0038] 4 is a schematic side view of the configuration of a portion of coolant flow path 250 near protrusion 271. The coolant passing through coolant flow path 250 flows in the direction of arrow FL1, and a part of the coolant collides with protrusion 271. The coolant generates turbulent flow FL2 by colliding with protrusion 271, and passes through the portion near lift pin hole 260 in this state.

[0039] If the flow direction of the refrigerant were the opposite to that described above, i.e., if the refrigerant were supplied from the outside to opening 252 instead of opening 251, the refrigerant would collide with protrusion 272, causing turbulence, and would pass through the area near lift pin hole 260 in that state.

[0040] In this way, the protrusions 271 and 272 are both formed in positions near the lift pin hole 260 and function as "turbulence generating parts" for generating turbulence in the flow of the refrigerant. The protrusion 271 is provided in the refrigerant flow passage 250 at a position upstream of the lift pin hole 260 along the direction of the refrigerant flow, and corresponds to the "first turbulence generating part" in this embodiment. The protrusion 272 is provided in the refrigerant flow passage 250 at a position downstream of the lift pin hole 260 along the direction of the refrigerant flow, and corresponds to the "second turbulence generating part" in this embodiment. When the refrigerant flows in the opposite direction to that in FIG. 4, the protrusion 272 corresponds to the "first turbulence generating part" and the protrusion 271 corresponds to the "second turbulence generating part."

[0041] The reason for adopting such a configuration will be explained. In the portion of the dielectric substrate 100 directly above the lift pin holes 260 formed in the base plate 200, the base plate 200 is not present directly below, so heat is difficult to be transferred to the base plate 200 side. For this reason, a local temperature rise occurs in the above-mentioned portion of the dielectric substrate 100, and the in-plane temperature distribution of the substrate W located further above may become uneven.

[0042] Therefore, in this embodiment, as described above, the protrusion 270, which is a turbulent flow generating part, is provided in the part of the coolant flow passage 250 near the lift pin hole 260. As shown in FIG. 4, the coolant passing through the coolant flow passage 250 generates a turbulent flow FL2 when passing through the position of the protrusion 270, and passes through the part near the lift pin hole 260 in this state. The part of the base plate 200 near the lift pin hole 260 is cooled more efficiently than when the protrusion 270 is not provided, and the temperature is reduced. As a result, a local temperature rise is unlikely to occur directly above the lift pin hole 260, and the variation in the in-plane temperature distribution of the substrate W can be suppressed.

[0043] As described above, in this embodiment, the protrusions 270 (turbulent flow generating portions) are provided at both a position (dotted line DL1) upstream of the lift pin hole 260 along the coolant flow direction and a position (dotted line DL2) downstream of the lift pin hole 260. With this configuration, regardless of whether the coolant is supplied from the opening 251 or 252, a turbulent flow is generated in the range AR1 shown in FIG. 3, and the portion near the lift pin hole 260 can be efficiently cooled.

[0044] The protrusions 270 (turbulence generating portions) are provided at positions near the three lift pin holes 260. Protrusions 270 similar to those described above may also be provided near through holes other than the lift pin holes 260 (such as the gas holes 214 and the through holes 240).

[0045] In the case where the coolant flows in a specific direction, only one of the protrusions 271 and 272 may be provided. In this case, the protrusion 270 may be provided at a position upstream of the lift pin hole 260 along the coolant flow direction.

[0046] A second embodiment will be described below. In the following, differences from the first embodiment will be mainly described, and descriptions of commonalities with the first embodiment will be omitted as appropriate.

[0047] In Fig. 5, the configuration of coolant flow path 250 in this embodiment is depicted from the same perspective as in Fig. 3. The portion of coolant flow path 250 shown in Fig. 5 is the same as range A (see Fig. 2) in the first embodiment. Also, dotted lines DL0, DL1, and DL2 shown in Fig. 5 are all the same as those shown in Fig. 3.

[0048] In this embodiment, the protrusion 270 is not formed on the inner wall surface of the refrigerant flow path 250. In this embodiment, the protrusion 280 is formed at the position corresponding to the dotted line DL1 and the position corresponding to the dotted line DL2 in the refrigerant flow path 250. In each of the protrusions 280, the refrigerant flow path 250 is routed along a path that protrudes in an arc shape. The "path that protrudes in an arc shape" may be a shape that follows a single perfect circle in a top view, but may also be a shape in which the center of curvature of the path differs from one place to another. In addition, the refrigerant flow path 250 may extend linearly in a part of the protrusion 280. The protrusion 280 formed at the position of the dotted line DL1 is also referred to as the "protrusion 281" below. The protrusion 280 formed at the position of the dotted line DL2 is also referred to as the "protrusion 282" below.

[0049] The coolant passing through the coolant flow passage 250 suddenly changes its flow direction when passing through the protruding portion 281, generating a turbulent flow, and passes through the portion near the lift pin hole 260 in this state. If the flow direction of the coolant were the opposite to that of this embodiment, that is, if the coolant was supplied from the outside to the opening 252 instead of the opening 251, the coolant would generate a turbulent flow when passing through the protruding portion 282, and would pass through the portion near the lift pin hole 260 in this state.

[0050] In this way, the protrusions 281 and 282 are both formed in positions near the lift pin hole 260 and function as "turbulence generating parts" for generating turbulence in the flow of the coolant. The protrusion 281 is provided in the coolant flow passage 250 at a position upstream of the lift pin hole 260 along the direction of the coolant flow, and corresponds to the "first turbulence generating part" in this embodiment. The protrusion 282 is provided in the coolant flow passage 250 at a position downstream of the lift pin hole 260 along the direction of the coolant flow, and corresponds to the "second turbulence generating part" in this embodiment. When the coolant flows in the opposite direction to this embodiment, the protrusion 282 corresponds to the "first turbulence generating part" and the protrusion 281 corresponds to the "second turbulence generating part". Even in this configuration, turbulence is generated in the range AR1 shown in FIG. 5, so that the same effect as that described in the first embodiment can be achieved.

[0051] The direction in which the protruding portion 281 protrudes in an arc shape is indicated by an arrow A1 in Fig. 5. This direction can be said to be, among any direction along the dotted line DL1, a direction toward the side where the lift pin hole 260 is provided in the top view.

[0052] The direction in which the protruding portion 282 protrudes in an arc shape is indicated by an arrow A2 in Fig. 5. This direction can be said to be, among any direction along the dotted line DL2, a direction toward the side where the lift pin hole 260 is provided in the top view.

[0053] Thus, in this embodiment, in each of the protruding portion 281 (first turbulence generation portion) and the protruding portion 282 (second turbulence generation portion), the coolant flow path 250 is routed along a path that protrudes in an arc shape toward the lift pin hole 260 in a top view. With this configuration, it is possible to further suppress a local temperature rise in the vicinity of the lift pin hole 260.

[0054] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Any design modifications made by a person skilled in the art to these specific examples are also included within the scope of the present disclosure as long as they have the features of the present disclosure. The elements of each of the above-mentioned specific examples and their arrangements, conditions, shapes, etc. are not limited to those exemplified and can be changed as appropriate. The combination of each of the elements of each of the above-mentioned specific examples can be changed as appropriate as long as no technical contradiction occurs. [Explanation of symbols]

[0055] 10: Electrostatic chuck 100: Dielectric substrate 110: Face 200: Base plate 250: Coolant flow path 260: Lift pin hole 270,271,272:Protrusion 280,281,282:Protrusion W: Substrate

Claims

1. a dielectric substrate having a mounting surface on which an object to be attached is placed; a base plate joined to the dielectric substrate; The base plate includes: a refrigerant flow path through which the refrigerant passes; A through hole extending in a direction perpendicular to the mounting surface is formed, a turbulence generating portion for generating turbulence in the flow of the coolant is provided in a portion of the coolant flow path adjacent to the through hole, The turbulent flow generating portion is a first turbulence generating portion provided in the refrigerant flow passage at a position upstream of the through hole along a direction in which the refrigerant flows; A second turbulence generating portion is provided at a position downstream of the through hole, In each of the first turbulence generation section and the second turbulence generation section, the refrigerant flow path is An electrostatic chuck, characterized in that, when viewed from a direction perpendicular to the mounting surface, the electrostatic chuck is routed along a path that protrudes in an arc shape, the radius of curvature of which is locally smaller.

2. In each of the first turbulence generation section and the second turbulence generation section, the refrigerant flow path is 2. The electrostatic chuck according to claim 1, wherein, when viewed from a direction perpendicular to the mounting surface, the electrostatic chuck is routed along a path that protrudes in an arc shape toward the side where the through hole is provided.

3. A dielectric substrate having a mounting surface on which an object to be attracted is placed; a base plate joined to the dielectric substrate; The base plate includes: a refrigerant flow path through which the refrigerant passes; A through hole extending in a direction perpendicular to the mounting surface is formed, a turbulence generating portion for generating turbulence in the flow of the coolant is provided in a portion of the coolant flow path adjacent to the through hole, In the turbulent flow generating portion, the coolant flow path is An electrostatic chuck, characterized in that, when viewed from a direction perpendicular to the mounting surface, the electrostatic chuck is routed along a path that protrudes in an arc shape, the radius of curvature of which is locally smaller.

4. A dielectric substrate having a mounting surface on which an object to be attracted is placed; a base plate joined to the dielectric substrate; The base plate includes: a refrigerant flow path through which the refrigerant passes; A through hole extending in a direction perpendicular to the mounting surface is formed, In a portion of the refrigerant flow path in the vicinity of the through hole, the refrigerant flow path is An electrostatic chuck, characterized in that, when viewed from a direction perpendicular to the mounting surface, the electrostatic chuck is routed along a path that protrudes in an arc shape, the radius of curvature of which is locally smaller.

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