Electrostatic chuck

Abstract

To provide an electrostatic chuck that can suppress variations in the in-plane temperature distribution of a substrate during processing.SOLUTION: An electrostatic chuck 10 includes a dielectric substrate 100 and a base plate 200 joined to the dielectric substrate 100. The base plate 200 has a coolant channel 250 through which a coolant flows, and a lift pin hole 260 formed therein. A protrusion 270 for generating turbulent flow in the coolant flow is provided in the portion of the coolant channel 250 near the lift pin hole 260.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] For example, semiconductor manufacturing equipment such as etching equipment is provided with an electrostatic chuck 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 that supports 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] It is necessary to maintain the temperature of the substrate at an appropriate temperature during processing such as etching, etc. 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 coolant flow paths, the base plate also has 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, which can cause a localized temperature rise in that area and lead to variations in the temperature distribution across the surface of the substrate.

[0007] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an electrostatic chuck that can suppress 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 present invention provides an electrostatic chuck including a dielectric substrate having a mounting surface on which an object to be attracted is placed, 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 as it passes through the turbulence generating portion, and passes through the portion of the base plate 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 without the turbulence generating portion, lowering its temperature. As a result, a local temperature rise directly above the through hole is less likely to occur, thereby suppressing variations in the in-plane temperature distribution of the substrate. [Effects of the Invention]

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

[0011] [Figure 1] 1 is a cross-sectional view schematically showing the configuration of an electrostatic chuck according to a first embodiment. [Figure 2] 5A and 5B are diagrams illustrating the configuration of a coolant flow path formed in a base plate. [Figure 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. 3 is a diagram schematically illustrating the flow of a refrigerant in a refrigerant flow path. [Figure 5] 10 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 INVENTION

[0012] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions 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 object to be attracted, that is, the substrate W, is, for example, a silicon wafer. The electrostatic chuck 10 may also be used in apparatuses other than semiconductor manufacturing apparatuses.

[0014] 1 is a schematic cross-sectional view showing the configuration of an electrostatic chuck 10 in a state where 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 also 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 "bonded surface" that is bonded to the base plate 200 via a bonding 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 also be referred to as a "top view."

[0017] An attraction electrode 130 is embedded inside the dielectric substrate 100. The attraction electrode 130 is a thin, flat layer made of a metal material such as tungsten, and is disposed parallel to the surface 110. In addition to tungsten, the attraction electrode 130 may be made of molybdenum, platinum, palladium, or the like. When a voltage is applied to the attraction electrode 130 from the outside, an electrostatic force is generated between the surface 110 and the substrate W, thereby attracting and holding the substrate W. As in this embodiment, only one attraction electrode 130 may be provided as a so-called "monopolar" electrode, 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, 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 to the outside through a through hole 240 formed in the base plate. Note that the configuration of the electric path for applying a voltage to the chucking electrode 130 may be different from that described above.

[0019] As shown in Fig. 1, a space SP is formed between the dielectric substrate 100 and the substrate W. When processing such as etching is performed in the semiconductor manufacturing equipment, helium gas for temperature adjustment is supplied to the space SP from the outside through gas holes 114. By providing helium gas between the dielectric substrate 100 and the substrate W, the thermal resistance between them is adjusted, thereby maintaining the temperature of the substrate W at an appropriate temperature. Note that 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 that is a mounting surface, and the 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 multiple 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 numeral "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 portion of the surface 110 to the position of the bottom surface 116.

[0023] The dots 112 are circular protrusions that protrude 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 comes into contact with 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 this configuration, it is possible to prevent dielectric breakdown from occurring 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. An 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 them 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 either 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 as to reduce the thermal resistance between the dielectric substrate 100 and the base plate 200.

[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 an insulating film, the dielectric strength of the base plate 200 can be increased.

[0029] A plurality of through holes are formed in the base plate 200, extending in a direction perpendicular to the surface 110. These through holes include the gas holes 114 and through holes 240 described above, as well as lift pin holes 260 (see FIG. 2), which are 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 equipment, 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 through openings 251 and 252 (not shown in FIG. 1, see FIG. 2) formed in the surface 220 of the base plate 200 opposite 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 opening 251 and the opening 252, and is formed along a path that passes through almost the entire base plate 200 when viewed from above.

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

[0033] FIG. 2 illustrates lift pin holes 260 among the multiple through holes formed in the base plate 200. The lift pin holes 260 are holes for inserting lift pins (not shown) provided in the semiconductor manufacturing equipment. A total of three lift pin holes 260 are formed, and they are arranged at equal intervals of 120 degrees when viewed from above. The lift pins that move up and down through the lift pin holes 260 attach and detach the substrate W to and from the surface 110 of the dielectric substrate 100. The lift pin holes 260, like the gas holes 214 shown in FIG. 1, are part of through holes formed to penetrate the entire electrostatic chuck 10. In FIG. 2, other through holes (such as the gas holes 214 and the through holes 240) formed in the base plate 200 are not illustrated.

[0034] Each lift pin hole 260 is formed at a position that does not overlap with the refrigerant flow path 250 when viewed from above. Range A shown in Fig. 2 includes one lift pin hole 260 and a portion of the refrigerant flow path 250 near the lift pin hole 260. Fig. 3 schematically illustrates the configuration of the portion of the base plate 200 inside range A 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 in refrigerant flow path 250 that is upstream of dotted line DL0 along the direction of refrigerant flow and extends perpendicular to that direction. Dotted line DL2 is an imaginary line that passes through a position in refrigerant flow path 250 that is downstream of dotted line DL0 along the direction of refrigerant flow and extends perpendicular to that direction.

[0037] In the refrigerant flow path 250, protrusions 270 are formed at positions indicated by dotted lines DL1 and DL2. The protrusions 270 are rectangular regions that are part of the inner wall surface of the refrigerant flow path 250, protruding inward of the refrigerant flow path 250. In this embodiment, the protrusions 270 are 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 they may be formed in other parts. The protrusions 270 formed at the position of dotted line DL1 will also be referred to as "protrusions 271" below. The protrusions 270 formed at the position of dotted line DL2 will also be referred to as "protrusions 272" below.

[0038] 4 is a schematic side view of the configuration of a portion of refrigerant flow path 250 near protrusion 271. The refrigerant passing through refrigerant flow path 250 flows in the direction of arrow FL1, and a portion of the refrigerant collides with protrusion 271. The refrigerant 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 direction of the refrigerant flow were reverse 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 holes 260 and function as "turbulence generating portions" for generating turbulence in the flow of the refrigerant. The protrusion 271 is provided in the refrigerant flow path 250 at a position upstream of the lift pin holes 260 along the direction of the refrigerant flow, and corresponds to the "first turbulence generating portion" in this embodiment. The protrusion 272 is provided in the refrigerant flow path 250 at a position downstream of the lift pin holes 260 along the direction of the refrigerant flow, and corresponds to the "second turbulence generating portion" in this embodiment. When the refrigerant flows in the opposite direction to that shown in FIG. 4, the protrusion 272 corresponds to the "first turbulence generating portion" and the protrusion 271 corresponds to the "second turbulence generating portion."

[0041] The reason for adopting such a configuration will be explained below. 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, and therefore heat is difficult to dissipate to the base plate 200 side. For this reason, a local temperature rise occurs in the above portion of the dielectric substrate 100, which may cause variations in the in-plane temperature distribution of the substrate W located further above.

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

[0043] As described above, in this embodiment, the protrusions 270 (turbulence 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 openings 251 or 252, a turbulence 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 each of 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 a 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 only needs to be provided at a position upstream of the lift pin hole 260 along the coolant flow direction.

[0046] The second embodiment will be described below. Differences from the first embodiment will be mainly described below, and descriptions of commonalities with the first embodiment will be omitted as appropriate.

[0047] Figure 5 illustrates the configuration of refrigerant flow path 250 in this embodiment from the same perspective as Figure 3. The portion of refrigerant flow path 250 shown in Figure 5 is the same as range A (see Figure 2) in the first embodiment. Dotted lines DL0, DL1, and DL2 shown in Figure 5 are all the same as those shown in Figure 3.

[0048] In this embodiment, no protrusions 270 are formed on the inner wall surface of the refrigerant flow path 250. In this embodiment, protrusions 280 are formed in the refrigerant flow path 250 at positions corresponding to dotted lines DL1 and DL2. In each of the protrusions 280, the refrigerant flow path 250 is routed along a path that protrudes in an arc. The "path that protrudes in an arc" may have a shape that follows a single perfect circle in top view, or may have a shape in which the center of curvature of the path differs depending on the location. Furthermore, the refrigerant flow path 250 may extend linearly in part of the protrusion 280. The protrusion 280 formed at the position of dotted line DL1 will be referred to as "protrusion 281" below. The protrusion 280 formed at the position of dotted line DL2 will be referred to as "protrusion 282" below.

[0049] The coolant passing through coolant flow path 250 suddenly changes its flow direction when passing through protrusion 281, causing turbulence, and passes through the portion near lift pin hole 260 in this state. If the coolant flow direction were reverse to that of this embodiment, that is, if the coolant were supplied from the outside to opening 252 instead of opening 251, the coolant would become turbulent when passing through protrusion 282, and pass through the portion near lift pin hole 260 in this state.

[0050] As described above, the protrusions 281 and 282 are both formed near the lift pin holes 260 and function as "turbulence generating portions" for generating turbulence in the coolant flow. The protrusion 281 is located in the coolant flow path 250, upstream of the lift pin holes 260 along the coolant flow direction, and corresponds to the "first turbulence generating portion" in this embodiment. The protrusion 282 is located in the coolant flow path 250, downstream of the lift pin holes 260 along the coolant flow direction, and corresponds to the "second turbulence generating portion" in this embodiment. When the coolant flows in the opposite direction to this embodiment, the protrusion 282 corresponds to the "first turbulence generating portion" and the protrusion 281 corresponds to the "second turbulence generating portion." Even with this configuration, turbulence is generated in the range AR1 shown in FIG. 5, and therefore the same effects as those described in the first embodiment can be achieved.

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

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

[0053] As described above, 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 holes 260 in a top view. By configuring in this manner, it is possible to further suppress a local temperature rise in the vicinity of the lift pin holes 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. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise. [Explanation of symbols]

[0055] 10: Electrostatic chuck 100: Dielectric substrate 110: Face 200: Base plate 250: Refrigerant 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 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, The electrostatic chuck is characterized in that a turbulence generating portion for generating turbulence in the flow of the coolant is provided in a portion of the coolant flow path near the through hole.

2. The turbulence generating section is a first turbulence generating portion provided in the refrigerant flow path at a position upstream of the through hole along a direction in which the refrigerant flows; 2. The electrostatic chuck according to claim 1, further comprising: a second turbulence generating portion provided at a position downstream of the through hole.

3. 3. The electrostatic chuck according to claim 2, wherein the first turbulence generating portion and the second turbulence generating portion are protrusions provided on an inner wall surface of the coolant flow passage.

4. In each of the first turbulence generation section and the second turbulence generation section, the refrigerant flow path is 3. The electrostatic chuck according to claim 2, wherein the electrostatic chuck is routed along a path that protrudes in an arc shape when viewed from a direction perpendicular to the mounting surface.

5. In each of the first turbulence generation section and the second turbulence generation section, the refrigerant flow path is 5. The electrostatic chuck according to claim 4, 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 through hole.

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