Electrostatic chuck

Abstract

To provide an electrostatic chuck with a high detachment response.SOLUTION: An electrostatic chuck 10 comprises: a dielectric substrate 100; and an absorption electrode 130 that is provided into an inner part of the dielectric substrate 100. The absorption electrode 130 contains: a plurality of first electrodes 131 that is electrically connected to each other via a first bypass 151 provided at the inner part of the dielectric substrate 100; and a plurality of second electrodes 132 that is electrically connected to each other via a second bypass 152 provided at the inner part of the dielectric substrate 100.SELECTED DRAWING: Figure 1

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. As described in Patent Document 1 below, the electrostatic chuck has a dielectric substrate provided with an adsorption electrode inside. When a voltage is applied to the adsorption electrode, an electrostatic force is generated, and the substrate placed on the dielectric substrate is adsorbed and held.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the processing of the substrate in the semiconductor manufacturing apparatus is completed, after the substrate is removed from the electrostatic chuck, the next substrate is placed on the electrostatic chuck. In order to process as many substrates as possible in as short a time as possible, the electrostatic chuck is required to have high detachment responsiveness. That is, it is required to make the time from when the application of the voltage to the adsorption electrode is stopped until the electrostatic force decreases to such an extent that the substrate can be removed as short as possible.

[0005] The present invention has been made in view of such problems, and an object thereof is to provide an electrostatic chuck with high detachment responsiveness.

Means for Solving the Problems

[0006] In order to solve the above problems, the electrostatic chuck according to the present invention includes a dielectric substrate having a placement surface on which an object to be adsorbed is placed, and an adsorption electrode provided inside the dielectric substrate. The adsorption electrode includes a plurality of first electrodes electrically connected to each other via a first bypass provided inside the dielectric substrate, and a plurality of second electrodes electrically connected to each other via a second bypass provided inside the dielectric substrate.

[0007] Since the plurality of first electrodes included in the adsorption electrode are electrically connected to each other via the first bypass, they have the same potential. Similarly, since the plurality of second electrodes included in the adsorption electrode are electrically connected to each other via the second bypass, they have the same potential. By applying a voltage between the first electrode and the second electrode, an electrostatic force can be generated between the dielectric substrate and the non-adsorbed object.

[0008] The adsorption electrode in the above configuration functions as a so-called "bipolar" electrode. However, neither the first electrode, which is one of the electrodes, nor the second electrode, which is the other electrode, is a single electrode, and they are divided into a plurality as described above.

[0009] According to experiments and the like conducted by the present inventors, in the bipolar adsorption electrode, when each electrode is configured to be divided into a plurality as described above, it is confirmed that the detachment responsiveness of the electrostatic chuck is higher than that in the case of the conventional configuration where it is not divided into a plurality. The reason is considered to be that the time required for the movement of the charges induced on the surface of the substrate (silicon wafer) to be completed from the time when the application of voltage to the adsorption electrode is stopped becomes shorter as the adsorption electrode is subdivided.

Advantages of the Invention

[0010] According to the present invention, an electrostatic chuck with high detachment responsiveness can be provided.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0012] Hereinafter, this embodiment will be described with reference to the accompanying drawings. For ease of understanding of the description, the same reference numerals are given to the same components in each drawing as much as possible, and redundant descriptions are omitted.

[0013] The electrostatic chuck 10 according to this embodiment adsorbs and holds 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 adsorbed is, for example, a silicon wafer. The electrostatic chuck 10 may be used in an apparatus other than a semiconductor manufacturing apparatus.

[0014] FIG. 1 schematically shows a cross-sectional view of the configuration of the electrostatic chuck 10 in a state where the substrate W is adsorbed and held. 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 ceramic sintered body. The dielectric substrate 100 is, for example, high-purity aluminum oxide (Al 2 O 3) is included, but other materials may also be included. The purity, type, additives, etc. of the ceramics in the dielectric substrate 100 can be appropriately set in consideration of the plasma resistance required for the dielectric substrate 100 in the semiconductor manufacturing apparatus.

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

[0017] An adsorption electrode 130 is provided 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.

[0018] The adsorption electrode 130 is a so-called "bipolar" electrode and includes a first electrode 131 and a second electrode 132. When a voltage is applied between the first electrode 131 and the second electrode 132 via the power supply paths 161, 162, etc. to be described later, an electrostatic force is generated between the surface 110 and the substrate W, and thereby the substrate W is adsorbed and held. The specific configurations of the first electrode 131, the second electrode 132, and the circuits connected thereto will be described later.

[0019] As shown in FIG. 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 180 (not shown in FIG. 1, see FIG. 5) of the dielectric substrate 100. By interposing helium gas between the dielectric substrate 100 and the substrate W, the thermal resistance between the two is adjusted, and thereby the temperature of the substrate W is maintained at an appropriate temperature. Note that the gas for temperature adjustment supplied to the space SP may be a gas of a type different from helium.

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

[0021] The seal ring 111 is a wall that partitions the space SP at the outermost peripheral position. The upper end of the seal ring 111 is part of the surface 110 and abuts on the substrate W. Note that a plurality of seal rings 111 may be provided so as to divide the space SP. With such a configuration, the pressure of the helium gas in each space SP can be individually adjusted, and the surface temperature distribution of the substrate W during processing can be made closer to uniform.

[0022] The portion marked with reference numeral “116” in FIG. 1 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 as a result of 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 arranged substantially evenly and dispersedly on the mounting surface of the dielectric substrate 100. The upper end of each dot 112 is part of the surface 110 and abuts on the substrate W. By providing a plurality of such dots 112, the deflection of the substrate W is suppressed.

[0024] 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, for example. Among the base plate 200, the upper surface 210 in FIG. 1 serves as a "surface to be joined" that is joined to the dielectric substrate 100 via the joining layer 300.

[0025] The joining layer 300 is a layer provided between the dielectric substrate 100 and the base plate 200 and joins the two. The joining layer 300 is obtained by curing an adhesive made of an insulating material. In the present embodiment, a silicone adhesive is used as the adhesive. However, the joining layer 300 may be obtained by curing another type of adhesive. In any case, as the material of the joining layer 300, it is preferable to use a material having as high a thermal conductivity as possible so that the thermal resistance between the dielectric substrate 100 and the base plate 200 is reduced.

[0026] 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 the insulating film, the dielectric breakdown voltage of the base plate 200 can be increased.

[0027] Inside the base plate 200, a refrigerant flow path 250 for passing a refrigerant is formed. When a process such as etching is performed in the semiconductor manufacturing apparatus, the refrigerant is supplied from the outside to the refrigerant flow path 250, whereby the base plate 200 is cooled. The heat generated in the substrate W during the process is transmitted to the refrigerant through 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.

[0028] The specific configuration of the suction electrode 130 and the like will be described. As described above, the suction electrode 130 is a so-called "bipolar" electrode and includes a first electrode 131 and a second electrode 132. However, the first electrode 131 is not a single electrode, and a plurality of them are provided at the same height position inside the dielectric substrate 100. Similarly, the second electrode 132 is not a single electrode, and a plurality of them are provided at the same height position inside the dielectric substrate 100. The "height position" described above refers to the position in the direction perpendicular to the surface 110 which is the mounting surface. The height position of the first electrode 131 and the height position of the second electrode 132 are the same as each other. That is, the entire suction electrode 130 is provided at the same height position.

[0029] In FIG. 1, the plurality of first electrodes 131 and second electrodes 132 provided are schematically drawn. In FIG. 2, the specific shapes and arrangements of the first electrode 131 and the second electrode 132 are drawn in a top view. As shown in the figure, both the first electrode 131 and the second electrode 132 are formed so as to extend along the radial direction, and are arranged so that they are alternately arranged along the circumferential direction.

[0030] Inside the dielectric substrate 100, a first bypass 151 and a second bypass 152 are provided. These are both thin flat plate-like layers formed of a metal material such as tungsten, for example, and are arranged parallel to the surface 110 and the suction electrode 130 and at the same height position as each other. The height positions of the first bypass 151 and the second bypass 152 are positions on the surface 120 side rather than the suction electrode 130. As the materials of the first bypass 151 and the second bypass 152, in addition to tungsten, molybdenum, platinum, palladium, etc. may also be used.

[0031] FIG. 1 schematically depicts a first bypass 151 and a second bypass 152. FIG. 3 depicts, in a top view, the specific shapes and arrangements of the first bypass 151, the second bypass 152, etc. As shown in the figure, the first bypass 151 and the second bypass 152 are formed to extend in an arc shape (specifically, circularly) along a pair of concentric circles. As a result, the first bypass 151 partially overlaps all the first electrodes 131 in a top view. Similarly, the second bypass 152 also partially overlaps all the second electrodes 132 in a top view. The shapes of the first bypass 151 and the second bypass 152 do not have to be circular as in this embodiment as long as they overlap the first electrodes 131, etc. in a top view as described above.

[0032] As shown in FIGS. 1 and 3, all of the plurality of first electrodes 131 are connected to the first bypass 151 via connection portions 141. The connection portions 141 are configured as elongated vias (holes) filled with a conductor. The connection portions 141 are provided at respective positions where the first bypass 151 and the first electrodes 131 overlap in a top view, and electrically connect the first bypass 151 and the first electrodes 131 at these positions. With the above configuration, the plurality of first electrodes 131 are electrically connected to each other via the first bypass 151. Although the first electrodes 131 are divided into a plurality, the respective potentials are always the same as each other.

[0033] A power supply path 161 is connected to the first bypass 151 from the outside. In FIG. 1, the entire power supply path 161 is schematically depicted. The portion of the power supply path 161 inside the dielectric substrate 100 is configured as, for example, an elongated via (hole) filled with a conductor, and an electrode terminal (not shown) is provided at its lower end. The portion of the power supply path 161 passing through the base plate 200 is a rod-shaped metal (bus bar) having one end connected to the above electrode terminal. A through hole (not shown) for inserting the metal is formed in the base plate 200.

[0034] As shown in FIGS. 1 and 3, a plurality of second electrodes 132 are all connected to a second bypass 152 via a connection portion 142. The connection portion 142 is configured as an elongated via (hole) filled with a conductor. The connection portion 142 is provided at each position where the second bypass 152 and the second electrode 132 overlap in a top view, and electrically connects the second bypass 152 and the second electrode 132 at that position. With the above configuration, the plurality of second electrodes 132 are electrically connected to each other via the second bypass 152. Although the second electrodes 132 are divided into a plurality, the respective potentials are always the same as each other.

[0035] A power supply path 162 is connected to the second bypass 152 from the outside. In FIG. 1, the entire power supply path 162 is drawn in a simplified manner. The portion of the power supply path 162 inside the dielectric substrate 100 is configured as, for example, an elongated via (hole) filled with a conductor, and an electrode terminal (not shown) is provided at the lower end thereof. The portion of the power supply path 162 passing through the base plate 200 is a rod-shaped metal (bus bar) having one end connected to the above electrode terminal. A through hole (not shown) for inserting the metal is formed in the base plate 200.

[0036] When a voltage is externally applied between the power supply path 161 and the power supply path 162, a voltage is applied between the respective first electrodes 131 and second electrodes 132, and an electrostatic force is generated between the surface 110 and the substrate W.

[0037] According to experiments and the like conducted by the inventors, when a pair of electrodes (the first electrode 131 and the second electrode 132) constituting the bipolar adsorption electrode 130 are each divided into a plurality as in this embodiment, it was confirmed that the detachment responsiveness of the electrostatic chuck 10 is higher than in the case of the conventional configuration where they are not divided. The reason is considered to be that the time required for the movement of the charges induced on the surface of the substrate W to be completed from the time when the application of voltage to the adsorption electrode 130 is stopped becomes shorter as the first electrode 131 and the like are subdivided. Such an improvement in detachment responsiveness was confirmed not only when the substrate W is a dielectric (insulator) such as a bare wafer, but also when a part of the substrate W is a conductor.

[0038] It is expected that the larger the number of the first electrode 131 and the like, that is, the smaller the area per one of the first electrode 131 and the like, the greater the improvement in the detachment responsiveness of the electrostatic chuck 10. When the combined number of the first electrode 131 and the second electrode 132 is 50 or more, it has been confirmed that the detachment responsiveness of the electrostatic chuck 10 is sufficiently improved.

[0039] The other configurations will be described. FIG. 4(A) shows the positional relationship between the first electrode 131 and the second electrode 132 adjacent to each other in a top view and the dot 112 (projection) disposed in the vicinity thereof. As shown in the figure, a part of the plurality of dots 112 are formed at positions that do not overlap the adsorption electrode 130 in a top view. The "position that does not overlap the adsorption electrode 130" is, for example, a position between the adjacent first electrode 131 and the second electrode 132, but may be a position between a pair of adjacent first electrodes 131 or a position between a pair of adjacent second electrodes 132.

[0040] In the dot 112 formed at the above-described position, the electrostatic force generated between its tip (surface 110) and the substrate W is smaller than that in the dot 112 formed at a position overlapping the adsorption electrode 130. Therefore, it is possible to prevent a situation where the relatively low-strength dot 112 is damaged or worn due to the force from the substrate W.

[0041] As in the example of FIG. 4(B), openings H1 may be formed in each of the portions of the adsorption electrode 130 that overlap the dots 112 in a top view. In this case, all of the plurality of dots 112 will be formed at positions that do not overlap the adsorption electrode 130 in a top view. Therefore, it is possible to prevent all of the dots 112 from being damaged or worn due to the force from the substrate W.

[0042] As in the example of FIG. 4(B), an arc-shaped notch H2 may be formed in the adsorption electrode 130 in a top view in the vicinity of the dot 112 formed at a position between the first electrode 131 and the second electrode 132. Thereby, since the distance between the dot 112 and the adsorption electrode 130 is ensured, the electrostatic force generated at the tip of the dot 112 can be made sufficiently small.

[0043] FIG. 5(A) shows the positional relationship between the first electrode 131 and the second electrode 132 that are adjacent to each other in a top view and the gas hole 180 disposed in the vicinity thereof. The gas hole 180 is a hole for supplying helium gas to the space SP, and is formed so as to penetrate the dielectric substrate 100. As shown in the figure, the gas hole 180 is formed at a position that does not overlap the adsorption electrode 130 in a top view. The "position that does not overlap the adsorption electrode 130" is, for example, a position between the adjacent first electrode 131 and the second electrode 132, but may be a position between a pair of adjacent first electrodes 131 or a position between a pair of adjacent second electrodes 132.

[0044] As in the example of FIG. 5(B), an arc-shaped notch H3 may be formed in the adsorption electrode 130 in a top view in the vicinity of the gas hole 180 formed at a position between the first electrode 131 and the second electrode 132. Since the distance between the inner surface of the gas hole 180 and the adsorption electrode 130 is ensured, it is possible to suppress dielectric breakdown in the gas hole 180.

[0045] A description will be given of the second embodiment. Hereinafter, differences from the first embodiment will mainly be described, and descriptions of points common to the first embodiment will be omitted as appropriate.

[0046] In FIG. 6, the specific shapes and arrangements of the first electrode 131 and the second electrode 132 in this embodiment are depicted in a top view. As shown in the figure, both the first electrode 131 and the second electrode 132 in this embodiment are formed so as to extend along the circumferential direction (specifically, circularly), and are arranged so that they are alternately arranged along the radial direction. Note that it is preferable that the widths (dimensions along the radial direction) of the plurality of first electrodes 131 and the plurality of second electrodes 132 are appropriately adjusted so that their respective areas are the same.

[0047] In FIG. 7, the specific shapes and arrangements of the first bypass 151 and the second bypass 152, etc. in this embodiment are depicted in a top view. As shown in the figure, the first bypass 151 and the second bypass 152 in this embodiment are formed so as to extend in straight lines parallel to each other. As a result, the first bypass 151 partially overlaps all the first electrodes 131 in a top view. Similarly, the second bypass 152 also partially overlaps all the second electrodes 132 in a top view.

[0048] Also in this embodiment, similar to the first embodiment, the connection part 141 is provided at each position where the first bypass 151 and the first electrode 131 overlap in a top view, and electrically connects between the first bypass 151 and the first electrode 131 at that position. Similarly, the connection part 142 is provided at each position where the second bypass 152 and the second electrode 132 overlap in a top view, and electrically connects between the second bypass 152 and the second electrode 132 at that position. Even in the configuration as described above, the same effects as those described in the first embodiment are achieved.

[0049] The above has described the present embodiment with reference to specific examples. However, the present disclosure is not limited to these specific examples. Those in which those skilled in the art have appropriately made design changes to these specific examples are also included in the scope of the present disclosure as long as they have the features of the present disclosure. Each element included in each of the above-described specific examples, and its arrangement, conditions, shape, etc. are not limited to those exemplified and can be changed as appropriate. Each element included in each of the above-described specific examples can be appropriately combined as long as no technical contradiction occurs.

Description of Reference Numerals

[0050] 10: Electrostatic chuck 100: Dielectric substrate 110: Surface 112: Dot 130: Adsorption electrode 131: First electrode 132: Second electrode 151: First bypass 152: Second bypass W: Substrate

Claims

1. A dielectric substrate having a placement surface on which an object to be adsorbed is placed, and an adsorption electrode provided inside the dielectric substrate, characterized in that the adsorption electrode includes a plurality of first electrodes electrically connected to each other via a first bypass provided inside the dielectric substrate, and a plurality of second electrodes electrically connected to each other via a second bypass provided inside the dielectric substrate.

2. When viewed from a direction perpendicular to the placement surface, the electrostatic chuck according to Claim 1, characterized in that the first electrodes and the second electrodes are arranged to be alternately arranged along the circumferential direction.

3. When viewed from a direction perpendicular to the placement surface, the electrostatic chuck according to Claim 2, characterized in that the first bypass and the second bypass are formed to extend in concentric arc shapes.

4. When viewed from a direction perpendicular to the placement surface, the electrostatic chuck according to Claim 1, characterized in that the first electrodes and the second electrodes are arranged to be alternately arranged along the radial direction.

5. When viewed from a direction perpendicular to the placement surface, the electrostatic chuck according to Claim 4, characterized in that the first bypass and the second bypass are formed to extend in straight lines parallel to each other.

6. A plurality of protrusions are formed on the placement surface side of the dielectric substrate, and when viewed from a direction perpendicular to the placement surface, the electrostatic chuck according to Claim 1, characterized in that at least some of the protrusions are formed at positions that do not overlap with the adsorption electrode.

Images