electrostatic chuck

Abstract

The present invention provides an electrostatic chuck capable of suppressing variations in the in-plane temperature distribution of a substrate during processing. [Solution] The electrostatic chuck 10 comprises a dielectric substrate 100, an internal electrode 430 provided inside the dielectric substrate 100, a power supply terminal 150 provided on the inner surface 120 of the dielectric substrate 100, and a connecting portion 160 connecting the internal electrode 430 and the power supply terminal 150. In a top view, the region AR10 that overlaps with the power supply terminal 150 includes a first region AR11 encompassing the center of the power supply terminal 150 and a second region AR12 surrounding 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 Art

[0002] For example, in a semiconductor manufacturing apparatus such as an etching apparatus, an electrostatic chuck is provided as a device for adsorbing and holding a substrate such as a silicon wafer to be processed. The electrostatic chuck has a dielectric substrate provided with adsorption electrodes. When a voltage is applied to the adsorption electrodes, an electrostatic force is generated, and the substrate placed on the dielectric substrate is adsorbed and held.

[0003] An internal electrode is provided inside the dielectric substrate. Examples of the internal electrode include the above-described adsorption electrode, an RF electrode, and a heating part of a heater.

[0004] As described in Patent Document 1 below, on the surface of the dielectric substrate opposite to the placement surface, a power supply terminal for receiving power supply from the outside is provided. Also, between the power supply terminal and the internal electrode, they are electrically connected via a connection part (via) provided inside the dielectric substrate.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the part where the connection parts of the internal electrodes are connected, the current density becomes high, so the amount of heat generation becomes large. For this reason, there is a possibility of local temperature rise in the part directly above the power supply terminal. As a result, there is a possibility that the variation in the in-plane temperature distribution of the substrate during processing becomes large.

[0007] The present invention has been made in view of these problems, and its objective 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 comprises a dielectric substrate having a mounting surface on which an object to be adsorbed is placed, an internal electrode provided inside the dielectric substrate, a power supply terminal provided on the side of the dielectric substrate opposite to the mounting surface, and a connecting 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 encompassing the center of the power supply terminal and a second region surrounding the first region from the outer periphery. In this electrostatic chuck, the internal electrode is not provided in the first region.

[0009] In the dielectric substrate, there is a region (the first region) directly above the power supply terminal where no internal electrodes are provided. Naturally, no Joule heating occurs in the region where no internal electrodes are provided. Therefore, compared to the case where internal electrodes are present in the first region, localized temperature rise directly above the power supply terminal can be suppressed. This makes it possible to suppress variations in the in-plane temperature distribution 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 drawing]

[0011] [Figure 1] This is a schematic cross-sectional view showing the configuration of the electrostatic chuck according to this embodiment. [Figure 2] This figure shows an example of how to divide a dielectric substrate into regions for arranging different heat-generating components. [Figure 3] This figure shows an example of a heat-generating component routed within a single region. [Figure 4] This diagram shows the configuration of the power supply terminal and its vicinity. [Modes for carrying out the invention]

[0012] This embodiment will now be described with reference to the attached drawings. To facilitate understanding of the explanation, the same reference numerals are used for identical components in each drawing whenever possible, and redundant explanations are omitted.

[0013] The electrostatic chuck 10 according to this embodiment is used to attract and hold a substrate W to be processed by electrostatic force 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 apparatus other than semiconductor manufacturing apparatus.

[0014] Figure 1 shows a schematic cross-sectional view of the electrostatic chuck 10 in a state where the substrate W is adsorbed and held. The electrostatic chuck 10 comprises a dielectric substrate 100 and a base plate 200.

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

[0016] The upper surface 110 of the dielectric substrate 100 in Figure 1 is the "mounting surface" on which the substrate W is placed. The lower surface 120 of the dielectric substrate 100 in Figure 1 is the "bonded surface" to which it is bonded to the base plate 200 via the bonding layer 300. The viewpoint from which the electrostatic chuck 10 is viewed from the surface 110 side, along a direction perpendicular to surface 110, will also be referred to as the "top view" below.

[0017] An adsorption electrode 130 is embedded inside the dielectric substrate 100. The adsorption electrode 130 is a thin flat plate-like layer formed of a metal material such as tungsten, for example, and is arranged to be parallel to the surface 110. As the material of the adsorption electrode 130, in addition to tungsten, molybdenum, platinum, palladium, etc. may also be used. When a voltage is applied to the adsorption 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, and thereby the substrate W is adsorbed and held. As the configuration of the above power supply path, various known configurations can be adopted. The adsorption electrode 130 may be provided only one as a so-called "single-pole" electrode as in this embodiment, or two may be provided as a so-called "bipolar" electrode.

[0018] Inside the dielectric substrate 100, in addition to the adsorption electrode 130, a heating part 431 is also embedded. The heating part 431 functions as a built-in heater for heating the dielectric substrate 100. The heating part 431 is a conductor routed in a line shape and generates heat when supplied with power from the outside. The heating part 431 is routed along a plane parallel to the surface 110 at a height position on the surface 120 side (the lower side in FIG. 1) than the adsorption electrode 130.

[0019] The dielectric substrate 100 is divided into a plurality of non-overlapping regions in a top view, and one heating part 431 is routed in each region. That is, a plurality of heating parts 431 corresponding to the number of the above regions are embedded in the dielectric substrate 100. By individually adjusting the heat generation amount in each heating part 431, the in-plane temperature distribution of the substrate W during processing can be made closer to uniform.

[0020] FIG. 2 shows an example of the above-described way of dividing regions in a top view. In this example, the dielectric substrate 100 is divided into a total of 24 regions HA. The linear heating parts 431 are individually routed in each region HA. That is, a total of 24 heating parts 431 are provided in this embodiment.

[0021] FIG. 3 shows an example of the heating part 431 routed in one area HA. In each area HA, a single linear heating part 431 is routed along a path that evenly passes through substantially all of its range.

[0022] Circular pad parts 432 and 433 are formed at both ends of the heating part 431. The heating part 431 and the pad parts 432 and 433 are formed, for example, by screen printing a metal material such as tungsten and are integrated with the heating part 431. The pad parts 432 and 432 are parts that are electrically connected to the power supply terminal 150 described later. The entire heating part 431 and the pad parts 432 and 433 connected thereto are also referred to as "internal electrode 430" hereinafter.

[0023] Note that the shape of the heating part 431 shown in FIG. 3 is schematic and different from the actual shape. The same applies to the positions of the pad parts 432 and 433.

[0024] Returning to FIG. 1, the description will be continued. A recess 121 is formed on the surface 120 of the dielectric substrate 100 so as to recess backward in a concave shape toward the surface 110 side. The end portion of the recess 121 on the surface 110 side is located at a position closer to the surface 120 side than the heating part 431. The shape of the recess 121 in a top view is circular.

[0025] A power supply terminal 150 is embedded inside the recess 121. The power supply terminal 150 is a substantially cylindrical metal terminal and is a part that receives power supplied to the heating part 431 from the outside. One end of the contact probe 402 is connected to the power supply terminal 150. The external power supply to the heating part 431 is performed via this contact probe 402. The entire power supply terminal 150 may be embedded inside the recess 121, or a part of the power supply terminal 150 may protrude outside the recess 121. Also, there may be a mode in which the recess 121 is not provided and the power supply terminal 150 is in contact with 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 circuit provided inside the dielectric substrate 100, and is also known as a "via". The connection portion 160 is formed by filling a hole extending perpendicular to the surface 110 with a metal such as tungsten.

[0027] Although multiple power supply terminals 150 are provided on the dielectric substrate 100, only a single power supply terminal 150 is shown in Figure 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 etching or other processes are performed in the semiconductor manufacturing apparatus, helium gas for temperature control is supplied to the space SP from the outside through a gas hole (not shown). By interposing 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 gas supplied to the space SP for temperature control may be a different type of gas than helium.

[0029] A sealing ring 111 and dots 112 are provided on the mounting surface 110, and the above-mentioned space SP is formed around them.

[0030] The seal ring 111 is a wall that partitions the space SP at its outermost position. The upper end of the seal ring 111 is part of the surface 110 and contacts the substrate W. Multiple seal rings 111 may be provided to divide the space SP. This configuration allows for individual adjustment of the helium gas pressure in each space SP, making the surface temperature distribution of the substrate W more uniform during processing.

[0031] In Figure 1, the portion labeled "116" is the bottom surface of the space SP. Hereafter, this portion will also be referred to as "bottom surface 116". The seal ring 111, along with the dot 112 described below, is formed as a result of excavating a portion of the surface 110 down to the position of the bottom surface 116.

[0032] The dots 112 are circular protrusions that extend from the bottom surface 116. Multiple 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 is part of the surface 110 and contacts the substrate W. By providing multiple such dots 112, the bending of the substrate W is suppressed.

[0033] The base plate 200 is a roughly disc-shaped member that supports the dielectric substrate 100. The base plate 200 is made of a metallic material such as aluminum. Of the base plate 200, the upper surface 210 in Figure 1 is the "bonded surface" which is bonded to the dielectric substrate 100 via the bonding layer 300.

[0034] The bonding layer 300 is a layer provided between the dielectric substrate 100 and the base plate 200, and it bonds the two together. The bonding layer 300 is made 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 made by curing another type of adhesive. In any case, it is preferable to use a material with the highest possible thermal conductivity for the bonding layer 300 so that the thermal resistance between the dielectric substrate 100 and the base plate 200 is reduced.

[0035] A refrigerant channel 250 for circulating refrigerant is formed inside the base plate 200. When etching or other processes are performed in the semiconductor manufacturing equipment, refrigerant is supplied from the outside to the refrigerant channel 250, thereby cooling the base plate 200. During processing, the heat generated in the substrate W is transferred to the refrigerant 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 refrigerant. The supply and discharge of refrigerant to and from the refrigerant channel 250 is performed through an opening (not shown) formed on the 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 when viewed from above. The through-hole 260 is a circular hole formed to penetrate the base plate 200 vertically from surface 210 to surface 220. The contact probe 402 mentioned earlier is inserted through the through-hole 260 from surface 220, and one end of it is connected to the power supply terminal 150.

[0037] An insulating film may be formed on the surface of the base plate 200. As the insulating film, for example, an alumina film formed by thermal spraying can be used. 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 vicinity will be explained with reference to Figure 4. Figure 4(A) shows the pad portion 432 and a part of the heat-generating portion 431 connected thereto in a top view. Figure 4(B) shows the BB cross section of Figure 4(A). This cross section includes the central axis AX of the power supply terminal 150.

[0039] The power supply terminal 150 is positioned 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 Figure 4(A), the outline of the power supply terminal 150 located directly below the pad portion 432 is shown by a dotted line. The area inside this 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. In a top view, the center of the opening 435 lies on the central axis AX. In this embodiment, the pad portion 432 is formed in an annular shape that surrounds the opening 435.

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

[0042] Of the region AR10 mentioned above, the region that overlaps with the aperture 435 in a top view will also be referred to as the "first region AR11" below. The first region AR11 is the region that encompasses the central axis AX of the power supply terminal 150 in a top view.

[0043] The region of region AR10 excluding the first region AR11 described above will also be referred to as the "second region AR12" below. The second region AR12 is the region that surrounds the first region AR11 from the outer periphery when viewed from above.

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

[0045] The reason for this configuration is as follows: When the substrate W is being processed, the current density is high in the part of the internal electrode 430 where the connection part 160 is connected, so the amount of heat generated tends to be large. Therefore, there is a possibility that the temperature of the substrate W may rise locally in the part directly above the power supply terminal 150. In particular, if the refrigerant flow path 250 of the base plate 200 is routed to avoid being directly below the power supply terminal 150, a localized temperature rise directly above the power supply terminal 150 is even more likely to occur. As a result, there is a possibility that the in-plane temperature distribution of the substrate W will become more varied.

[0046] Therefore, in this embodiment, as described above, an 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 region AR11 which encompasses the central axis AX of the power supply terminal 150 in a top view. Since the internal electrode 430 is not present in the first region AR11, Joule heating is naturally not generated. As a result, compared to the case where the internal electrode 430 is also present in the first region AR11, a localized temperature rise directly above the power supply terminal 150 can be suppressed. This makes it possible to suppress variations in the in-plane temperature distribution of the substrate W during processing.

[0047] In this embodiment, multiple connection parts 160 are arranged in a circular pattern when viewed from above, and these are arranged to surround the first region AR11 from the outer periphery. This configuration makes it possible to suppress the occurrence of temperature variations along the circumferential direction around the central axis AX.

[0048] Instead of providing multiple connecting parts 160 as in this embodiment, for example, only one cylindrical connecting part 160 may be provided. In this case, the central axis of the cylindrical connecting part 160 should be aligned with the central axis AX, and the inner diameter of the connecting part 160 should be greater than or equal to the diameter of the first region AR11.

[0049] The above describes the configuration of the area near the pad portion 432, but the configuration of the area near the pad portion 433 is the same as described above.

[0050] The internal electrodes may be heater electrodes as in this embodiment, but they may also be other electrodes provided inside the dielectric substrate 100. For example, they may be RF electrodes (not shown) for attracting plasma, or adsorption electrodes 130, etc. The configuration of the part in which these internal electrodes and the power supply terminals are electrically connected may be the same as the configuration described above.

[0051] The embodiments have been described above with reference to specific examples. However, this disclosure is not limited to these specific examples. Modifications made to these specific examples by those skilled in the art are also included within the scope of this disclosure, as long as they retain the features of this disclosure. The elements, their arrangement, conditions, shapes, etc., of each of the aforementioned specific examples are not limited to those illustrated and can be modified as appropriate. The elements of each of the aforementioned specific examples can be combined in different ways as appropriate, as long as no technical inconsistencies 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: Circuit board

Claims

1. A dielectric substrate having a mounting surface on which an object to be adsorbed is placed, An internal electrode provided inside the dielectric substrate, Of the dielectric substrate, a power supply terminal is provided on the side opposite to the mounting surface described above, It comprises a connecting portion that connects the internal electrode and the power supply terminal, When viewed from a direction perpendicular to the mounting surface, The area overlapping with the aforementioned power supply terminal is, A first region encompassing the center of the power supply terminal, A second region that surrounds the first region from the outer periphery, An electrostatic chuck characterized in that the internal electrodes are not provided in the first region.

2. When viewed from a direction perpendicular to the mounting surface, The electrostatic chuck according to claim 1, characterized in that the connecting portion is arranged to surround the first region from the outer periphery.

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