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), an internal electrode (430) provided inside the dielectric substrate (100), a power supply terminal (150) provided on a surface (120) of the dielectric substrate (100), and a connection portion (160) connecting the internal electrode (430) and the power supply terminal (150). A region (AR10) overlapping with the power supply terminal (150) in a top view includes a first region (AR11) that encompasses the center of the power supply terminal (150) and a second region (AR12) that surrounds the first region (AR11) from the outer periphery, and the internal electrode (430) is not provided in the first region (AR11).

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 has a dielectric substrate on which an attracting electrode is provided. When a voltage is applied to the attracting electrode, an electrostatic force is generated, attracting and holding the substrate placed on the dielectric substrate.

[0003] The dielectric substrate is provided with an internal electrode therein, such as the above-mentioned attraction electrode, RF electrode, or heat generating portion of the heater.

[0004] As described in Patent Document 1 below, a power supply terminal for receiving power from an external source is provided on the surface of the dielectric substrate opposite to the mounting surface. The power supply terminal and the internal electrode are electrically connected through a connection portion (via) provided inside the dielectric substrate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-25435 Summary of the Invention [Problem to be solved by the invention]

[0006] The current density is high in the area where the internal electrodes are connected, which increases the amount of heat generated. This can cause a localized temperature rise directly above the power supply terminal. As a result, the temperature distribution across the substrate during processing can vary greatly.

[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] 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 placed, an internal electrode provided inside the dielectric substrate, a power supply terminal provided on the surface of the dielectric substrate opposite the mounting surface, and a connection portion connecting the internal electrode and the power supply terminal. When viewed from a direction perpendicular to the mounting surface, the region overlapping with the power supply terminal includes a first region that includes the center of the power supply terminal and a second region that surrounds the first region from the outer periphery. In this electrostatic chuck, the internal electrode is not provided in the first region.

[0009] The dielectric substrate has a region (first region) directly above the power supply terminal where no internal electrodes are provided. Joule heat is naturally not generated in the region where no internal electrodes are provided. Therefore, compared to when internal electrodes are also present in the first region, local temperature increases directly above the power supply terminal can be suppressed. This makes it possible to suppress variations in the temperature distribution within the surface of the substrate during processing. [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 illustrating a configuration of an electrostatic chuck according to an embodiment of the present invention. [Figure 2] 10A and 10B are diagrams illustrating an example of how to divide a dielectric substrate into regions for arranging each heat generating portion. [Figure 3] FIG. 10 is a diagram showing an example of a heat generating portion routed in one area. [Figure 4] 3A and 3B are diagrams illustrating the configuration of a power supply terminal and its surrounding area. 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] The 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 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. The attraction electrode 130 may be made of a material other than tungsten, such as molybdenum, platinum, or palladium. When a voltage is applied to the attraction electrode 130 from the outside via a power supply path (not shown), an electrostatic force is generated between the surface 110 and the substrate W, thereby attracting and holding the substrate W. The power supply path may be configured in any of various well-known ways. The attraction electrode 130 may be provided as a single so-called "monopolar" electrode as in this embodiment, or as two so-called "bipolar" electrodes.

[0018] In addition to the chucking electrode 130, a heat generating portion 431 is also embedded inside the dielectric substrate 100. The heat generating portion 431 functions as a built-in heater for heating the dielectric substrate 100. The heat generating portion 431 is a linear conductor that generates heat when power is supplied from an external source. The heat generating portion 431 is routed along a plane parallel to the surface 110 at a height position closer to the surface 120 than the chucking electrode 130 (lower in FIG. 1 ).

[0019] The dielectric substrate 100 is divided into a plurality of regions that do not overlap each other when viewed from above, and one heat generating portion 431 is routed in each region. In other words, a plurality of heat generating portions 431 corresponding to the number of the regions are embedded in the dielectric substrate 100. By individually adjusting the heat generation amount of each heat generating portion 431, it is possible to make the in-plane temperature distribution of the substrate W during processing more uniform.

[0020] 2 shows an example of how to divide the regions as described above from a top view. In this example, the dielectric substrate 100 is divided into a total of 24 regions HA. The linear heat generating portions 431 are individually routed in each region HA. In other words, in this embodiment, a total of 24 heat generating portions 431 are provided.

[0021] 3 shows an example of a heat generating portion 431 routed in one area HA. ​​In each area HA, one linear heat generating portion 431 is routed along a path that passes uniformly through almost the entire area.

[0022] Circular pad portions 432, 433 are formed on both ends of the heat generating portion 431. The heat generating portion 431 and the pad portions 432, 433 are formed by screen printing a metal material such as tungsten, and are integrated with the heat generating portion 431. The pad portions 432, 432 are portions that are electrically connected to the power supply terminal 150, which will be described later. The heat generating portion 431 and the pad portions 432, 433 connected thereto as a whole will hereinafter be referred to as the "internal electrode 430."

[0023] 3 is a schematic view of the heat generating portion 431 and differs from the actual shape. The same applies to the positions of the pad portions 432 and 433.

[0024] Returning to Figure 1, the explanation will continue. A recess 121 is formed on surface 120 of dielectric substrate 100 so as to recess back toward surface 110. The end of recess 121 on the surface 110 side is located closer to surface 120 than heat generating portion 431. When viewed from above, recess 121 has a circular shape.

[0025] A power supply terminal 150 is embedded inside the recess 121. The power supply terminal 150 is a metal terminal having a substantially cylindrical shape, and serves as a portion that receives power from the outside to be supplied to the heat generating portion 431. One end of a contact probe 402 is connected to the power supply terminal 150. Power is supplied to the heat generating portion 431 from the outside via this contact probe 402. The entire power supply terminal 150 may be embedded inside the recess 121, or a portion of the power supply terminal 150 may protrude outside the recess 121. Alternatively, the recess 121 may not be provided, and the power supply terminal 150 may abut against the surface 120.

[0026] The power supply terminal 150 and the internal electrode 430 are electrically connected via a connection portion 160. The connection portion 160 is an electrical path provided inside the dielectric substrate 100 and is also called a "via." The connection portion 160 is formed by filling a hole extending in a direction perpendicular to the surface 110 with a metal such as tungsten.

[0027] Although a plurality of power supply terminals 150 are provided on the dielectric substrate 100, only a single power supply terminal 150 is shown in Fig. 1. The specific configuration of the power supply terminal 150 and its vicinity will be described later.

[0028] 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 a gas hole (not shown). 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] A coolant flow path 250 for flowing 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 an opening (not shown) formed in a surface 220 of the base plate 200 opposite to the surface 210.

[0036] A through hole 260 is formed in the base plate 200 at a position that overlaps with the power supply terminal 150 in a top view. The through hole 260 is a circular hole that is formed to pass vertically through the base plate 200 from the surface 210 to the surface 220. The contact probe 402 described above is inserted into the through hole 260 from the surface 220 side, and one end of the contact probe 402 is connected to the power supply terminal 150.

[0037] 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.

[0038] The specific configuration of the power supply terminal 150 and its surrounding area will be described with reference to Fig. 4. Fig. 4(A) illustrates a top view of the pad portion 432 and a part of the heat generating portion 431 connected thereto. Fig. 4(B) shows a cross section BB of Fig. 4(A). This cross section includes the central axis AX of the power supply terminal 150.

[0039] The power supply terminal 150 is disposed in a position directly below the pad portion 432. The central axis AX of the power supply terminal 150 coincides with the center of the pad portion 432 in a top view. In FIG. 4(A), the outline of the power supply terminal 150 directly below the pad portion 432 is shown by a dotted line. The area inside the dotted line can be said to be the area that overlaps with the power supply terminal 150 in a top view. This area will also be referred to as "area AR10" below.

[0040] A circular opening 435 is formed in the center of the pad portion 432. The center of the opening 435 in top view is on the central axis AX. The pad portion 432 of this embodiment is formed in an annular shape that surrounds the periphery of the opening 435.

[0041] The pad portion 432 and the power supply terminal 150 are connected by a total of six connection portions 160. The connection portions 160 are arranged in a circular pattern at equal intervals along the annular pad portion 432. In FIG. 4(B), the upper ends of the connection portions 160 are directly connected to the pad portion 432. The lower ends of the connection portions 160 are electrically connected to the upper ends of the power supply terminals 150. They may be directly connected to each other, or another conductive member may be interposed between them. For example, the connection portions 160 and the power supply terminals 150 may be electrically connected to each other via a brazing material used to fix the power supply terminals 150 to the recess 121 (see FIG. 1).

[0042] Of the above-described area AR10, the area that overlaps with the opening 435 in top view is hereinafter also referred to as a “first area AR11.” The first area AR11 is an area that includes the central axis AX of the power supply terminal 150 in top view.

[0043] The region AR10 excluding the first region AR11 will be referred to as the “second region AR12” below. The second region AR12 is a region that surrounds the first region AR11 from the outer periphery in a top view.

[0044] Thus, the region AR10 overlapping with the power supply terminal 150 in top view includes the first region AR11 and the second region AR12. As is clear from the above definitions, the internal electrode 430 is provided only in the second region AR12 of the region AR10, and is not provided in the first region AR11.

[0045] The reason for adopting such a configuration will be explained. When the substrate W is being processed, the current density is high in the portion of the internal electrode 430 where the connection portion 160 is connected, and therefore the amount of heat generated is likely to be large. Therefore, there is a possibility that the temperature of the substrate W will rise locally in the portion directly above the power supply terminal 150. In particular, if the coolant flow path 250 of the base plate 200 is routed so as to avoid the area directly below the power supply terminal 150, the local temperature rise directly above the power supply terminal 150 will be even more likely to occur. As a result, there is a possibility that the in-plane temperature distribution of the substrate W will vary greatly.

[0046] Therefore, in this embodiment, as described above, the opening 435 is formed in the pad portion 432 of the internal electrode 430. That is, the internal electrode 430 is not provided in the first area AR11 that encompasses the central axis AX of the power supply terminal 150 in top view. Since the internal electrode 430 is not present in the first area AR11, Joule heat is naturally not generated. Therefore, compared to when the internal electrode 430 is also present in the first area AR11, it is possible to suppress a local temperature rise directly above the power supply terminal 150. This makes it possible to suppress variations in the in-plane temperature distribution of the substrate W during processing.

[0047] In this embodiment, the multiple connection portions 160 are arranged in a circle in top view, and are arranged to surround the first region AR11 from the outer periphery. With this configuration, it is possible to suppress temperature variations along the circumferential direction around the central axis AX.

[0048] Instead of providing a plurality of connection portions 160 as in the present embodiment, it is also possible to provide, for example, only one cylindrical connection portion 160. In this case, the central axis of the cylindrical connection portion 160 is aligned with the central axis AX, and the inner diameter of the connection portion 160 is set to be equal to or larger than the diameter of the first region AR11.

[0049] The configuration of the area near the pad section 432 has been described above, but the configuration of the area near the pad section 433 is similar to that described above.

[0050] The internal electrode may be a heater electrode as in this embodiment, or may be another electrode provided inside the dielectric substrate 100. For example, it may be an RF electrode (not shown) for attracting plasma, or an attraction electrode 130. The configuration of the part where these internal electrodes and the power supply terminals are electrically connected may be the same as the configuration described above.

[0051] 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]

[0052] 10: Electrostatic chuck 100: Dielectric substrate 110,120: face 150: Power supply terminal 160: Connection part 430: Internal electrode AR10:Area AR11: 1st area AR12: 2nd area W: Substrate

Claims

1. a dielectric substrate having a mounting surface on which an object to be attracted is placed; an internal electrode provided inside the dielectric substrate; a power supply terminal provided on a surface of the dielectric substrate opposite to the mounting surface; a connection portion connecting the internal electrode and the power supply terminal, When viewed from a direction perpendicular to the placement surface, The area overlapping with the power supply terminal is a first region including a center of the power supply terminal; a second region surrounding the first region from an outer periphery thereof, The internal electrode is not provided in the first region, The electrostatic chuck is characterized in that the internal electrode is provided in an annular shape in the second region.

2. When viewed from a direction perpendicular to the placement surface, 2. The electrostatic chuck according to claim 1, wherein the connection portion is disposed so as to surround the first region from the outer periphery side.

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