JP2020039003A - Electrostatic chuck - Google Patents

Abstract

To provide an electrostatic chuck capable of improving RF response while improving in-plane uniformity of plasma density.SOLUTION: An electrostatic chuck includes a ceramic dielectric substrate having first and second principal surfaces, a base plate, a first electrode layer provided in the ceramic dielectric substrate and connected with a high frequency power supply, and a second electrode layer provided in the ceramic dielectric substrate and connected with an adsorption power supply. The first electrode layer is provided between the first and a second principal surfaces in the Z-axis direction, the second electrode layer is provided between the first electrode layer and the first principal surfaces in the Z-axis direction, the first electrode layer has a first face on the first principal surface side, and a second face of the opposite side to the first face, electric power is supplied from the second face side, the distance between the first face and the first principal surface is constant in the Z axis direction, and the distance between the second face and the first face in the Z axis direction at the end of the first electrode layer is smaller than the distance between the second face and the first face in the Z axis direction in the central part of the first electrode layer.SELECTED DRAWING: Figure 2

Description

  Aspects of the present invention generally relate to electrostatic chucks.

  2. Description of the Related Art In a plasma processing chamber for performing etching, CVD (Chemical Vapor Deposition), sputtering, ion implantation, ashing, and the like, an electrostatic chuck is used as a means for attracting and holding a processing target such as a semiconductor wafer or a glass substrate. The electrostatic chuck applies electrostatic attraction power to a built-in electrode to attract a substrate such as a silicon wafer by electrostatic force.

  When performing plasma processing, for example, a voltage is applied from an RF (Radio Frequency) power supply (high-frequency power supply) to an upper electrode provided in an upper part of the chamber and a lower electrode provided below the upper electrode. Then, plasma is generated.

  In a conventional electrostatic chuck, plasma is generated using a base plate provided below the electrostatic chuck as a lower electrode. However, in a situation where an appropriate frequency is selected and further control of the distribution of the plasma density in the wafer surface is required, there is a limit to the plasma control in such a configuration.

  Therefore, in recent years, attempts have been made to improve the plasma controllability by incorporating a lower electrode for plasma generation in a dielectric layer provided on a base plate. However, there is a problem that sufficient in-plane uniformity of the plasma density cannot be sufficiently obtained only by incorporating the lower electrode in the dielectric layer.

  In recent years, in addition to the improvement of the in-plane uniformity of the plasma density, it has been required to further improve the responsiveness (RF responsiveness) to control such as a change in RF output.

JP 2008-277847 A JP 2011-119654 A JP 2004-103648 A JP-A-2014-201411

  The present invention has been made based on the recognition of such a problem, and it is an object of the present invention to provide an electrostatic chuck capable of improving RF uniformity while improving in-plane uniformity of plasma density.

  A first invention is a ceramic dielectric substrate having a first main surface on which an object to be adsorbed is placed, and a second main surface opposite to the first main surface, and the ceramic dielectric substrate. A first electrode layer provided inside the ceramic dielectric substrate and connected to a high-frequency power supply; and a base plate provided inside the ceramic dielectric substrate and connected to a power supply for adsorption. At least one second electrode layer, wherein the first electrode layer is provided between the first main surface and the second main surface in a Z-axis direction from the base plate to the ceramic dielectric substrate. The second electrode layer is provided between the first electrode layer and the first main surface in the Z-axis direction, and the first electrode layer is provided on the first surface on the first main surface side. And a second surface opposite to the first surface. The distance along the Z-axis direction between the first surface and the first main surface in the electrostatic chuck fed from the second surface side is constant, and the distance between the end of the first electrode layer is The distance along the Z-axis direction between the second surface and the first surface is along the Z-axis direction between the second surface and the first surface at the center of the first electrode layer. An electrostatic chuck characterized by being smaller than a distance.

According to this electrostatic chuck, by providing the first electrode layer connected to the high-frequency power supply inside the ceramic dielectric substrate, for example, the upper electrode for plasma generation provided above the electrostatic chuck and the first electrode layer are provided. The distance to the electrode layer (lower electrode) can be reduced. Thereby, for example, the plasma density can be increased with lower power than when the base plate is used as a lower electrode for plasma generation. According to this electrostatic chuck, the uniformity of the plasma density can be improved by keeping the distance between the first surface and the first main surface along the Z-axis direction constant.
Generally, when an alternating current flows through the electrode, a phenomenon called a skin effect occurs in which the current density is high at the electrode surface and decreases when the electrode is away from the surface. It is known that the higher the frequency of the alternating current, the greater the concentration of the current on the surface. In the present invention, since the first electrode layer is connected to the high-frequency power supply, a skin effect occurs in the first electrode layer, and it is considered that the alternating current applied from the high-frequency power supply flows along the surface of the first electrode layer. . According to this electrostatic chuck, in the first electrode layer that is connected and supplied with the high-frequency power from the second surface side, the Z-axis direction between the second surface and the first surface at the end of the first electrode layer. The distance along the first electrode layer is smaller than the distance along the Z-axis direction between the second surface and the first surface at the center of the first electrode layer. Therefore, the power supply distance from the second surface to the first surface can be reduced. Thereby, responsiveness (RF responsiveness) to control such as a change in RF output can be improved.
Conventionally, a second electrode layer connected to a power supply for suction has been provided inside a dielectric substrate. In addition, when the first electrode layer connected to the high frequency power supply is provided inside the ceramic dielectric substrate, and the power applied to the first electrode layer is increased to increase the plasma density, In particular, the inventors have found a new problem that the environment in the chamber changes due to the heat generated by the first electrode layer, which adversely affects in-plane uniformity of plasma density. According to this electrostatic chuck, the distance along the Z-axis direction between the second surface and the first surface at the end of the first electrode layer is set equal to the distance between the second surface and the first surface at the center of the first electrode layer. Is smaller than the distance along the Z-axis direction, the surface area of the second surface of the first electrode layer located on the base plate side having the cooling function can be relatively increased. Thus, the first electrode layer can be more effectively dissipated, and the in-plane uniformity of the plasma density can be further increased.

  In a second aspect based on the first aspect, a total area of the first surface of the first electrode layer is larger than a total area of the first main surface side of the second electrode layer. An electrostatic chuck characterized by the following.

  According to this electrostatic chuck, the total area of the first surface of the first electrode layer is made larger than the total area of the surface on the first main surface side of the second electrode layer, so that the in-plane plasma density is reduced. Uniformity can be further improved.

  A third invention is the electrostatic chuck according to the first invention, wherein a part of the first electrode layer does not overlap with the second electrode layer in the Z-axis direction.

  According to this electrostatic chuck, the in-plane uniformity of the plasma density can be further improved by preventing a part of the first electrode layer from overlapping with the second electrode layer in the Z-axis direction.

  A fourth invention is the electrostatic chuck according to any one of the first to third inventions, wherein a thickness of the first electrode layer is larger than a thickness of the second electrode layer.

  According to this electrostatic chuck, by making the thickness of the first electrode layer larger than the thickness of the second electrode layer, the influence of the skin effect can be reduced, and the in-plane uniformity of the plasma density can be further increased. it can. It has been found that when the first electrode layer connected to the high-frequency power supply is simply thickened, there is a concern that RF responsiveness may be deteriorated. In the present invention, while increasing the thickness of the first electrode layer, the distance along the Z-axis direction between the second surface and the first surface at the end of the first electrode layer is set at the center of the first electrode layer. The distance between the second surface and the first surface of the portion along the Z-axis direction is smaller. Therefore, it is possible to suppress the decrease in the RF responsiveness while reducing the influence of the skin effect.

  In a fifth aspect based on any one of the first to fourth aspects, a distance along the Z-axis direction between the second surface and the first surface at a central portion of the first electrode layer is: An electrostatic chuck having a thickness of 1 μm or more and 500 μm or less.

  According to this electrostatic chuck, the distance between the second surface and the first surface at the center of the first electrode layer along the Z-axis direction (the thickness of the first electrode layer at the center) is defined as this range. Thus, the influence of the skin effect can be reduced, the in-plane uniformity of the plasma density can be further increased, and the decrease in the RF responsiveness can be suppressed.

  In a sixth aspect based on the fifth aspect, the distance along the Z-axis direction between the second surface and the first surface at the center of the first electrode layer is not less than 10 μm and not more than 100 μm. An electrostatic chuck characterized by the following.

  According to this electrostatic chuck, the distance between the second surface and the first surface at the center of the first electrode layer along the Z-axis direction (the thickness of the first electrode layer at the center) is defined as this range. Thereby, the influence of the skin effect can be reduced, the in-plane uniformity of the plasma density can be further increased, and the decrease in the RF responsiveness can be suppressed.

  A seventh invention is the electrostatic chuck according to any one of the first to sixth inventions, wherein the first electrode layer contains at least one of Ag, Pd, and Pt.

  As described above, according to the electrostatic chuck according to the embodiment, for example, the first electrode layer including a metal such as Ag, Pd, and Pt can be used.

  An eighth invention is the electrostatic chuck according to any one of the first to seventh inventions, wherein the first electrode layer is made of a cermet of a metal and a ceramic.

  According to this electrostatic chuck, by forming the first electrode layer by cermet, the adhesion between the first electrode layer and the ceramic dielectric substrate can be increased, and the strength of the first electrode layer can be increased. it can.

  A ninth invention is the electrostatic chuck according to the eighth invention, wherein the ceramic contains the same element as the ceramic contained in the ceramic dielectric substrate.

  According to this electrostatic chuck, the first electrode layer is formed of a ceramic cermet containing the same element as the ceramic contained in the ceramic dielectric substrate, so that the coefficient of thermal expansion of the first electrode layer and the thermal expansion coefficient of the ceramic dielectric substrate are increased. The difference from the expansion coefficient can be reduced. Thereby, the adhesion between the first electrode layer and the ceramic dielectric substrate can be increased, and defects such as peeling can be suppressed.

  A tenth invention is the electrostatic chuck according to the eighth invention, wherein the ceramic contains an element different from the ceramic contained in the ceramic dielectric substrate.

  As described above, according to the electrostatic chuck according to the embodiment, the first electrode layer is formed of the ceramic cermet containing an element different from the ceramic included in the ceramic dielectric substrate, so that the thermal characteristics, the mechanical characteristics, and the electrical characteristics are obtained. Can be arbitrarily designed.

  In an eleventh aspect based on any one of the first to tenth aspects, the first electrode layer includes a metal and a ceramic, the second electrode layer includes a metal and a ceramic, The ratio of the volume of the metal to the sum of the volume of the metal and the volume of the ceramic included in the electrode layer is determined by the ratio of the volume of the metal to the total of the volume of the metal and the volume of the ceramic included in the second electrode layer. An electrostatic chuck characterized by being larger than a volume ratio.

  According to this electrostatic chuck, by making the ratio of the metal included in the first electrode layer larger than the ratio of the metal included in the second electrode layer, for example, the first electrode layer to which a voltage is applied from a high-frequency power supply Can be further reduced, and in-plane uniformity of plasma density and RF responsiveness can be improved.

  In a twelfth aspect based on any one of the first to tenth aspects, the first electrode layer includes a metal and a ceramic, the second electrode layer includes a metal and a ceramic, In the electrostatic chuck, a volume of the metal included in the electrode layer is larger than a volume of the metal included in the second electrode layer.

  According to this electrostatic chuck, by making the volume of the metal contained in the first electrode layer larger than the volume of the metal contained in the second electrode layer, for example, the first electrode layer to which a voltage is applied from a high frequency power supply Can be further reduced, and in-plane uniformity of plasma density and RF responsiveness can be improved.

  In a thirteenth aspect based on any one of the first to twelfth aspects, the ceramic dielectric substrate contains aluminum oxide, and the concentration of the aluminum oxide in the ceramic dielectric substrate is 90% by mass or more. An electrostatic chuck characterized in that:

  According to this electrostatic chuck, plasma resistance of the ceramic dielectric substrate can be improved by using high-purity aluminum oxide.

  In a fourteenth aspect based on any one of the first to thirteenth aspects, a distance between the first electrode layer and the second electrode layer along the Z-axis direction is equal to the distance between the first main surface and the first principal surface. An electrostatic chuck, wherein the distance is larger than a distance along a Z-axis direction between the second electrode layer and the second electrode layer.

  According to this electrostatic chuck, the distance along the Z axis between the first electrode layer and the second electrode layer is made larger than the distance along the Z axis between the first main surface and the second electrode layer. Thus, even when a voltage is applied from a high-frequency power supply, it is possible to more effectively suppress the occurrence of problems such as a short circuit and dielectric breakdown between the first electrode layer and the second electrode layer.

  In a fifteenth aspect based on any one of the first to fourteenth aspects, the width of the end portion is set between the second surface and the first surface in the central portion of the first electrode layer. An electrostatic chuck characterized by being longer than a distance along the Z-axis direction.

  According to this electrostatic chuck, the width of the end of the first electrode layer is set to the distance along the Z-axis direction between the second surface and the first surface at the center of the first electrode layer (that is, the first electrode layer). (Thickness at the central part of the sheet)), the power supply distance can be shortened. Thereby, the responsiveness (RF responsiveness) to the control such as the change of the RF output can be further improved.

  According to an aspect of the present invention, there is provided an electrostatic chuck capable of enhancing RF responsiveness while improving in-plane uniformity of plasma density.

FIG. 2 is a cross-sectional view schematically illustrating the electrostatic chuck according to the embodiment. FIG. 3 is a cross-sectional view schematically illustrating an enlarged part of the electrostatic chuck according to the embodiment. FIGS. 3A and 3B are cross-sectional views schematically illustrating a modification of the first electrode layer of the electrostatic chuck according to the embodiment. FIGS. 4A and 4B are plan views schematically illustrating a part of the electrostatic chuck according to the embodiment. FIGS. 5A and 5B are plan views schematically showing a part of the electrostatic chuck according to the embodiment. FIGS. 6A and 6B are plan views schematically illustrating a part of the electrostatic chuck according to the embodiment. 7A and 7B are plan views schematically illustrating a part of the electrostatic chuck according to the embodiment. 1 is a cross-sectional view schematically illustrating a wafer processing apparatus including an electrostatic chuck according to an embodiment. FIGS. 9A to 9D are cross-sectional views schematically illustrating an enlarged end portion of the first electrode layer according to the embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the drawings, similar components are denoted by the same reference numerals, and detailed description will be omitted as appropriate.

FIG. 1 is a schematic sectional view illustrating the electrostatic chuck according to the embodiment.
As shown in FIG. 1, the electrostatic chuck 100 includes a ceramic dielectric substrate 10, a first electrode layer 11, a second electrode layer 12, and a base plate 50.

The ceramic dielectric substrate 10 is a flat base material made of, for example, a sintered ceramic. For example, the ceramic dielectric substrate 10 includes aluminum oxide (alumina: Al ₂ O ₃ ). For example, the ceramic dielectric substrate 10 is formed of high-purity aluminum oxide. The concentration of aluminum oxide in the ceramic dielectric substrate 10 is, for example, 90% by mass (mass%) or more and 100% by mass or less, preferably 95% by mass (mass%) or more and 100% by mass or less, and more preferably 99% by mass (mass%) or less. %) To 100 mass% or less. By using high-purity aluminum oxide, the plasma resistance of the ceramic dielectric substrate 10 can be improved. Note that the concentration of aluminum oxide can be measured by X-ray fluorescence analysis or the like.

  The ceramic dielectric substrate 10 has a first main surface 10a and a second main surface 10b. The first main surface 10a is a surface on which the suction target W is placed. The second main surface 10b is a surface opposite to the first main surface 10a. The suction target W is, for example, a semiconductor substrate such as a silicon wafer.

  In the present specification, the direction from the base plate 50 to the ceramic dielectric substrate 10 is defined as a Z-axis direction. The Z-axis direction is, for example, a direction connecting the first main surface 10a and the second main surface 10b as illustrated in each drawing. The Z-axis direction is, for example, a direction substantially perpendicular to the first main surface 10a and the second main surface 10b. One direction orthogonal to the Z-axis direction is referred to as an X-axis direction, and a direction orthogonal to the Z-axis direction and the X-axis direction is referred to as a Y-axis direction. In the specification of the present application, “in the plane” is, for example, in the XY plane.

  A first electrode layer 11 and a second electrode layer 12 are provided inside the ceramic dielectric substrate 10. The first electrode layer 11 and the second electrode layer 12 are provided between the first main surface 10a and the second main surface 10b. That is, the first electrode layer 11 and the second electrode layer 12 are provided so as to be inserted into the ceramic dielectric substrate 10. The first electrode layer 11 and the second electrode layer 12 may be embedded in the ceramic dielectric substrate 10, for example, by being integrally sintered.

  The first electrode layer 11 is located between the first main surface 10a and the second main surface 10b in the Z-axis direction. The second electrode layer 12 is located between the first main surface 10a and the first electrode layer 11 in the Z-axis direction. In other words, the first electrode layer 11 is located between the second electrode layer 12 and the second main surface 10b in the Z-axis direction.

  By providing the first electrode layer 11 inside the ceramic dielectric substrate 10 in this manner, the upper electrode (the upper electrode 510 in FIG. 8) provided above the electrostatic chuck 100 and the first electrode layer 11 (the lower electrode) Electrode) can be shortened. Thus, for example, the plasma density can be increased with lower power than when the base plate 50 is used as the lower electrode. In other words, the power required to obtain a high plasma density can be reduced.

  The shape of the first electrode layer 11 and the second electrode layer 12 is a thin film along the first main surface 10a and the second main surface 10b of the ceramic dielectric substrate 10. The cross-sectional shapes of the first electrode layer 11 and the second electrode layer 12 will be described later.

  The first electrode layer 11 is connected to a high-frequency power supply (the high-frequency power supply 504 in FIG. 8). When a voltage (high-frequency voltage) is applied to the upper electrode (the upper electrode 510 in FIG. 8) and the first electrode layer 11 from a high-frequency power supply, plasma is generated inside the processing container 501. The first electrode layer 11 is, in other words, a lower electrode for generating plasma. The high-frequency power supply supplies a high-frequency AC (alternating current) to the first electrode layer 11. The “high frequency” here is, for example, 200 kHz or more.

  The first electrode layer 11 is made of, for example, a metal. The first electrode layer 11 includes, for example, at least one of Ag, Pd, and Pt. The first electrode layer 11 may include, for example, a metal and a ceramic. The first electrode layer 11 may be made of, for example, a cermet of a metal and a ceramic. Cermet is a composite material containing a metal and a ceramic (oxide, carbide, etc.). By forming the first electrode layer 11 by cermet, the adhesion between the first electrode layer 11 and the ceramic dielectric substrate 10 can be increased. Further, the strength of the first electrode layer 11 can be increased.

  The metal contained in the cermet includes, for example, at least one of Ag, Pd, and Pt. The ceramic contained in the cermet contains, for example, the same element as the ceramic contained in the ceramic dielectric substrate 10. By forming the first electrode layer 11 with a ceramic cermet containing the same element as the ceramic contained in the ceramic dielectric substrate 10, the coefficient of thermal expansion of the first electrode layer 11 and the coefficient of thermal expansion of the ceramic dielectric substrate 10 can be reduced. Can be reduced. Thereby, the adhesion between the first electrode layer 11 and the ceramic dielectric substrate 10 can be enhanced, and problems such as peeling can be suppressed. The ceramic contained in the cermet may contain an element different from the ceramic contained in the ceramic dielectric substrate 10.

  The second electrode layer 12 is connected to a power supply for suction (a power supply for suction 505 in FIG. 8). The electrostatic chuck 100 generates an electric charge on the first main surface 10a side of the second electrode layer 12 by applying a voltage (adsorption voltage) to the second electrode layer 12 from a power supply for adsorption, and applies an electrostatic force to the target. The object W is held by suction. In other words, the second electrode layer 12 is an adsorption electrode for adsorbing the target object W. The power supply for suction supplies a direct current (DC) current or an AC current to the second electrode layer 12. The power supply for suction is, for example, a DC power supply. The suction power supply may be, for example, an AC power supply.

  The second electrode layer 12 is made of, for example, a metal. The second electrode layer 12 includes, for example, at least one of Ag, Pd, Pt, Mo, and W. The second electrode layer 12 may include, for example, a metal and a ceramic.

  When the first electrode layer 11 includes a metal and a ceramic, and the second electrode layer 12 includes a metal and a ceramic, the volume of the metal with respect to the sum of the volume of the metal and the volume of the ceramic included in the first electrode layer 11. The ratio is preferably larger than the ratio of the volume of the metal to the sum of the volume of the metal contained in the second electrode layer 12 and the volume of the ceramic.

  As described above, by increasing the ratio of the metal included in the first electrode layer 11 to the ratio of the metal included in the second electrode layer 12, for example, the first electrode layer 11 to which a voltage is applied from a high-frequency power source can be used. Electric resistance can be further reduced, and in-plane uniformity of plasma density and RF responsiveness can be improved.

  In the embodiment, the ratio of the volume of the metal to the sum of the volume of the metal and the volume of the ceramic is determined by observing the cross sections of the first electrode layer 11 and the second electrode layer 12 by SEM-EDX (Energy Dispersive X-ray Spectroscopy). Can be determined by image analysis. More specifically, a cross-sectional SEM-EDX image of the first electrode layer 11 and the second electrode layer 12 is obtained, classified into ceramics and metal by EDX component analysis, and the area ratio between ceramics and metal is analyzed by image analysis. By calculating, the ratio of the volume of the metal to the sum of the volume of the metal and the volume of the ceramics can be calculated.

  When the first electrode layer 11 includes a metal and a ceramic, and the second electrode layer 12 includes a metal and a ceramic, the volume of the metal included in the first electrode layer 11 is equal to the volume of the metal included in the second electrode layer 12. It is also preferred that it be larger than the volume.

  As described above, by making the volume of the metal included in the first electrode layer 11 larger than the volume of the metal included in the second electrode layer 12, for example, the first electrode layer 11 to which a voltage is applied from a high-frequency power source is used. Electric resistance can be further reduced, and in-plane uniformity of plasma density and RF responsiveness can be improved.

  The second electrode layer 12 is provided with a connection portion 20 extending toward the second main surface 10 b of the ceramic dielectric substrate 10. The connection portion 20 is, for example, a via (solid type) or a via hole (hollow type) that is electrically connected to the second electrode layer 12. The connection part 20 may be a metal terminal connected by an appropriate method such as brazing.

  The base plate 50 is a member that supports the ceramic dielectric substrate 10. The ceramic dielectric substrate 10 is fixed on the base plate 50 by an adhesive member 60. As the bonding member 60, for example, a silicone adhesive is used.

  The base plate 50 is made of, for example, a metal such as aluminum. The base plate 50 may be made of, for example, ceramic. The base plate 50 is, for example, divided into an upper part 50a and a lower part 50b, and a communication path 55 is provided between the upper part 50a and the lower part 50b. One end of the communication path 55 is connected to the input path 51, and the other end of the communication path 55 is connected to the output path 52.

  The base plate 50 also serves to adjust the temperature of the electrostatic chuck 100. For example, when cooling the electrostatic chuck 100, a cooling medium such as helium gas flows in from the input path 51, passes through the communication path 55, and flows out from the output path 52. Thereby, the heat of the base plate 50 is absorbed by the cooling medium, and the ceramic dielectric substrate 10 mounted thereon can be cooled. On the other hand, when keeping the temperature of the electrostatic chuck 100, it is also possible to put a heating medium in the communication path 55. A heating element can be built in the ceramic dielectric substrate 10 or the base plate 50. By adjusting the temperatures of the base plate 50 and the ceramic dielectric substrate 10, the temperature of the target object W sucked and held by the electrostatic chuck 100 can be adjusted.

  In this example, a groove 14 is provided on the first main surface 10a side of the ceramic dielectric substrate 10. The groove 14 is depressed in a direction (Z-axis direction) from the first main surface 10a toward the second main surface 10b, and extends continuously in the XY plane. Assuming that a portion where the groove 14 is not provided is the protrusion 13, the object W is placed on the protrusion 13. The first main surface 10a is a surface that is in contact with the back surface of the object W. That is, the first main surface 10 a is a plane including the upper surface of the convex portion 13. A space is formed between the back surface of the object W placed on the electrostatic chuck 100 and the groove 14.

  The ceramic dielectric substrate 10 has a through hole 15 connected to the groove 14. The through hole 15 is provided from the second main surface 10b to the first main surface 10a. That is, the through hole 15 extends in the Z-axis direction from the second main surface 10b to the first main surface 10a, and penetrates through the ceramic dielectric substrate 10.

  By appropriately selecting the height of the protrusion 13 (depth of the groove 14), the area ratio of the protrusion 13 and the groove 14, the shape, and the like, the temperature of the target object W and the particles adhering to the target object W are brought into a preferable state. You can control.

  The base plate 50 is provided with a gas introduction path 53. The gas introduction path 53 is provided, for example, so as to penetrate the base plate 50. The gas introduction path 53 does not penetrate the base plate 50, and may be branched from the middle of another gas introduction path 53 and provided to the ceramic dielectric substrate 10 side. Further, the gas introduction paths 53 may be provided at a plurality of locations on the base plate 50.

  The gas introduction path 53 communicates with the through hole 15. That is, the transfer gas (such as helium (He)) flowing into the gas introduction path 53 flows into the through hole 15 after passing through the gas introduction path 53.

  The transmission gas flowing into the through hole 15 flows into the space provided between the object W and the groove 14 after passing through the through hole 15. Thereby, the object W can be directly cooled by the transmission gas.

FIG. 2 is an enlarged cross-sectional view schematically illustrating a part of the electrostatic chuck according to the embodiment.
FIGS. 3A and 3B are cross-sectional views schematically illustrating a modification of the first electrode layer of the electrostatic chuck according to the embodiment.
FIG. 2 shows the region R1 shown in FIG. 1 in an enlarged manner.

  As shown in FIG. 2, the first electrode layer 11 has a first surface 11a and a second surface 11b. The first surface 11a is a surface on the first main surface 10a side. The second surface 11b is a surface opposite to the first surface 11a. The first surface 11a is, in other words, a surface facing the second electrode layer 12. The second surface 11b is, in other words, a surface facing the second main surface 10b.

  The distance D1 along the Z-axis direction between the first surface 11a and the first main surface 10a is constant. In other words, the distance D1 is a distance from the first main surface 10a to the upper surface of the first electrode layer 11 (the first surface 11a). Here, "constant" can include, for example, undulations of the first surface 11a. For example, when the cross section of the electrostatic chuck 100 is observed at a low magnification (for example, about 100 times) with a scanning electron microscope (SEM) or the like, the distance D1 may be substantially constant. For example, the difference between the distance D1c at the center 11c of the first electrode layer 11 and the distance D1d at the end 11d of the first electrode layer 11 is 0 ± 150 μm. The distance D1 (the distance D1c and the distance D1d) is, for example, about 300 μm. The first surface 11a is, for example, a surface parallel to the first main surface 10a.

  As shown in FIG. 2, an end portion 11 d of the first electrode layer 11 is a region including an edge 11 e in the XY plane of the first electrode layer 11. The edge 11e of the first electrode layer 11 is located on the first surface 11a and indicates an interface between the first electrode layer 11 and the ceramic dielectric substrate 10 when viewed from the Z-axis direction. The central portion 11c of the first electrode layer 11 is a region located between the two end portions 11d on the XY plane. The center 11c and the end 11d of the first electrode layer 11 will be described later.

  As described above, by keeping the distance D1 along the Z-axis direction between the first surface 11a and the first main surface 10a constant, the upper electrode (the upper electrode 510 in FIG. 8) and the first electrode layer 11 (the lower electrode) Electrode) can be constant. Thereby, for example, the in-plane uniformity of the plasma density can be improved as compared with a case where the distance D1 along the Z-axis direction between the first surface 11a and the first main surface 10a is not constant. For example, when the cross-sectional shape of the first electrode layer 11 is convex upward, the distance along the Z-axis direction between the first surface 11a and the first main surface 10a at the end 11d is equal to the distance at the center 11c. The in-plane uniformity of the plasma density can be improved as compared with the case where the distance along the Z-axis direction between the first surface 11a and the first main surface 10a is different.

  The cross-sectional shape of the first electrode layer 11 is convex downward. More specifically, the distance D2d along the Z-axis direction between the second surface 11b and the first surface 11a at the end 11d of the first electrode layer 11 is equal to the second distance at the center 11c of the first electrode layer 11. It is smaller than a distance D2c along the Z-axis direction between the surface 11b and the first surface 11a. The distance D2c is, in other words, the thickness of the first electrode layer 11 at the central portion 11c. The distance D2d is, in other words, the thickness of the first electrode layer 11 at the end 11d. That is, the thickness of the first electrode layer 11 at the end 11d is smaller than the thickness of the first electrode layer 11 at the center 11c. For example, the thickness of the first electrode layer 11 decreases from the center 11c to the end 11d. The first electrode layer 11 has a convex shape on the second surface 11b side.

  The distance D2c is, for example, 1 μm or more and 500 μm or less, preferably 10 μm or more and 100 μm or less, and more preferably 20 μm or more and 70 μm or less. By setting the thickness (distance D2c) of the first electrode layer 11 in the central portion 11c within this range, the effect of the skin effect can be reduced, and the in-plane uniformity of the plasma density can be further increased. The distance D2c can be determined, for example, as an average value of the thicknesses of three points at the central portion 11c in a cross-sectional SEM (Scanning Electron Microscope) image of the first electrode layer 11. In the present specification, this average value is defined as a distance D2c.

  A high-frequency current is supplied to the first electrode layer 11 from the second surface 11b side. Normally, when an AC current flows through the electrode layer, a skin effect occurs in which the current density is high at the surface of the electrode layer and decreases as the distance from the surface increases. In addition, as the flowing AC current has a higher frequency, the surface concentration of the current becomes more remarkable. That is, the high-frequency AC current flowing into the first electrode layer 11 from the second surface 11b side flows through the second surface 11b of the first electrode layer 11 and flows into the first surface 11a.

  In the embodiment, the distance D2d along the Z-axis direction between the second surface 11b and the first surface 11a at the end 11d of the first electrode layer 11 is set to the second surface at the center 11c of the first electrode layer 11. By making the distance D2c along the Z-axis direction between the first surface 11b and the first surface 11a smaller, the power supply distance from the second surface 11b to the first surface 11a to which power is supplied can be reduced. Thereby, responsiveness (RF responsiveness) to control such as change of RF output can be further improved.

  The present inventors have provided a first electrode layer 11 connected to a high-frequency power supply inside a ceramic dielectric substrate 10 and furthermore, a high-frequency power supply applied to the first electrode layer 11 to increase the plasma density has a high power. In particular, the present inventors have found a new problem that the first electrode layer 11 generates heat, changes the environment in the chamber (the processing vessel 501 in FIG. 8), and adversely affects in-plane uniformity of plasma density. . On the other hand, according to the embodiment, the distance D2d along the Z-axis direction between the second surface 11b and the first surface 11a at the end 11d of the first electrode layer 11 is set to the central portion of the first electrode layer 11. The distance D2c along the Z-axis direction between the second surface 11b and the first surface 11a in 11c is made smaller. For example, by forming the first electrode layer 11 to have a convex shape on the second surface 11b side (that is, the base plate 50 side), the second surface 11b on the base plate 50 side having a cooling function of the first electrode layer 11 is provided. Can have a relatively large surface area. Thereby, the first electrode layer 11 can be more effectively dissipated, and the in-plane uniformity of the plasma density can be further increased.

  In this example, the thickness of the first electrode layer 11 is constant at the central portion 11c. In other words, in the central part 11c, the second surface 11b is parallel to the first surface 11a. On the other hand, at the end 11d, the thickness of the first electrode layer 11 decreases from the center 11c toward the edge 11e. In other words, at the end 11d, the second surface 11b has an inclined surface inclined upward from the center 11c toward the edge 11e. In this example, the inclined surface is planar. The inclined surface may be a curved surface as shown in FIG.

  The cross-sectional shape of the first electrode layer 11 is not limited to this. For example, as shown in FIG. 3B, the second surface 11b may have an inclined surface that is inclined upward from the center of the second surface 11b in the XY plane toward the edge 11e. . In other words, the thickness of the first electrode layer 11 at the central portion 11c may not be constant. In other words, in the central portion 11c, the second surface 11b may not be parallel to the first surface 11a. At this time, the inclined surface may be a curved surface as shown in FIG.

  As shown in FIG. 2, the second electrode layer 12 has a third surface 12a on the first main surface 10a side and a fourth surface 12b opposite to the third surface 12a. The fourth surface 12b is, in other words, a surface facing the first electrode layer 11. The fourth surface 12b is, in other words, a surface facing the first surface 11a of the first electrode layer 11.

  The third surface 12a may be a surface parallel to the first main surface 10a. The distance D3 along the Z-axis direction between the third surface 12a and the first main surface 10a is, for example, constant. The distance D3 is, in other words, a distance from the first main surface 10a to the upper surface of the second electrode layer 12 (the third surface 12a).

  The fourth surface 12b is also preferably a surface parallel to the third surface 12a. The fourth surface 12b is also preferably a surface parallel to the first main surface 10a. More specifically, it is also preferable that the distance D4 along the Z-axis direction between the fourth surface 12b and the third surface 12a is constant. The distance D4 is, in other words, the thickness of the second electrode layer 12. The thickness of the second electrode layer 12 can be determined, for example, as an average value of the thicknesses of three points in a cross-sectional SEM image of the second electrode layer 12.

  The thickness of the first electrode layer 11 is larger than the thickness of the second electrode layer 12, for example. By making the thickness of the first electrode layer 11 larger than the thickness of the second electrode layer 12, the influence of the skin effect can be reduced, and the in-plane uniformity of the plasma density can be further increased.

  The distance D5 along the Z-axis direction between the first electrode layer 11 and the second electrode layer 12 (that is, the distance along the Z-axis direction between the first surface 11a and the fourth surface 12b) D5 is, for example, The distance D3 between the first main surface 10a and the second electrode layer 12 along the Z-axis direction (that is, the distance along the Z-axis direction between the third surface 12a and the first main surface 10a) D3.

  As described above, by making the distance D5 greater than the distance D3, even when a voltage is applied from a high-frequency power supply, a problem such as a short circuit or dielectric breakdown between the first electrode layer 11 and the second electrode layer 12 occurs. Can be suppressed more effectively.

FIGS. 4A, 4B, 5A, 5B, 6A, and 6B schematically show a part of the electrostatic chuck according to the embodiment. FIG.
In these drawings, in the electrostatic chuck 100, a portion of the ceramic dielectric substrate 10 located on the base plate 50 side (lower side) of the first electrode layer 11 (second surface 11b), the base plate 50, and the like are omitted. FIG. 5 is a plan view of the first electrode layer 11 viewed from the second surface 11b side (lower side) in a state where the first electrode layer 11 is formed.

  As shown in FIG. 4A, FIG. 4B, FIG. 5A, FIG. 5B, FIG. 6A, and FIG. , And at least one first electrode layer 11 extending along the XY plane. The number of the first electrode layers 11 may be, for example, one as shown in FIGS. 4A and 4B, or 2 as shown in FIGS. 5A and 5B. 6 or three or more (four in this example) as shown in FIGS. 6A and 6B. When a plurality of first electrode layers 11 are provided, each of the first electrode layers 11 may be located on, for example, the same plane or on different planes in the Z-axis direction.

  In the example shown in FIGS. 4A and 4B, the first electrode layer 11 which is circular when viewed along the Z-axis direction is, for example, the center of the first electrode layer 11 and the ceramic dielectric. It is arranged so that the center of the substrate 10 overlaps. The edge 11 e of the first electrode layer 11 is, for example, concentric with the edge of the ceramic dielectric substrate 10. In this example, the end 11 d of the first electrode layer 11 is annularly arranged on the outer peripheral side of the ceramic dielectric substrate 10.

  In the example shown in FIGS. 5A and 5B, for example, the inner first electrode layer 11A and the outer first electrode layer 11B are provided concentrically. The inner first electrode layer 11A is, for example, circular when viewed along the Z-axis direction. The outer first electrode layer 11B has, for example, an annular shape surrounding the inner first electrode layer 11A when viewed along the Z-axis direction. Each of the inner first electrode layer 11A and the outer first electrode layer 11B is arranged, for example, concentrically where the center of the inner first electrode layer 11A and the center of the ceramic dielectric substrate 10 overlap. In this example, the end 11d of the outer first electrode layer 11B is annularly arranged on the center side of the ceramic dielectric substrate 10 and on the outer peripheral side of the ceramic dielectric substrate 10, respectively. The end 11d of the inner first electrode layer 11A is annularly arranged on the outer peripheral side of the ceramic dielectric substrate. The number of first electrode layers 11 is not limited to two, and three or more first electrode layers 11 may be arranged concentrically.

  In the example shown in FIGS. 6A and 6B, each of the plurality of first electrode layers 11 that is circular when viewed along the Z-axis direction is, for example, the center of the ceramic dielectric substrate 10. Are arranged at positions that are point-symmetric with respect to. One of the first electrode layers 11 may be arranged such that the center of the first electrode layer 11 and the center of the ceramic dielectric substrate 10 overlap. In other words, one of the first electrode layers 11 may be arranged at the center of the ceramic dielectric substrate 10. In this example, the end 11 d of each first electrode layer 11 is annularly arranged on the outer peripheral side of each first electrode layer 11.

  In addition, as shown in FIGS. 4B, 5B, and 6B, the first electrode layer 11 is provided with a hole 11p that penetrates the first electrode layer 11 in the Z-axis direction. You may be. When the hole 11p is provided, the end 11d is also arranged near the outer periphery of the hole 11p.

  In the embodiment, the distance D2d between the first surface 11a and the second surface 11b at the end 11d and the first surface 11a and the second surface 11b at the center 11c at any position of the end 11d. May satisfy the relationship D2d <D2c. On the other hand, as long as the effects of the present invention are achieved, it is not excluded that a portion that does not satisfy D2d <D2c is included. In other words, in the embodiment, D2d <D2c may be satisfied in at least a part of the end 11d as described above. For example, if there are many places in the end 11d that satisfy D2d <D2c, the RF responsiveness can be further improved.

  As described above, the central portion 11c of the first electrode layer 11 is a region located between the two end portions 11d on the XY plane. For example, in the first electrode layer 11, all regions other than the end 11d may be regarded as the center 11c. In other words, in the first electrode layer 11, for example, the vicinity of the edge 11e can be regarded as the end 11d, and the other portion can be regarded as the center 11c.

7A and 7B are plan views schematically illustrating a part of the electrostatic chuck according to the embodiment.
These figures show the electrostatic chuck 100 in a state where a portion of the ceramic dielectric substrate 10 located on the first main surface 10a side (upper side) of the second electrode layer 12 (third surface 12a) is omitted. FIG. 5 is a plan view of a second electrode layer 12 viewed from a third surface 12a side (upper side).

  As shown in FIGS. 7A and 7B, the second electrode layer 12 may be a monopolar type or a bipolar type. When the second electrode layer 12 is of a monopolar type, as shown in FIG. 7A, one second electrode layer 12 extending along the XY plane is provided. The second electrode layer 12 is, for example, substantially circular when viewed along the Z-axis direction. On the other hand, when the second electrode layer 12 is of a bipolar type, as shown in FIG. 7B, two second electrode layers 12 extending along the XY plane and located on the same plane are provided. Each of the second electrode layers 12 is, for example, substantially semicircular when viewed along the Z-axis direction. The second electrode layer 12 may have, for example, a pattern extending along the XY plane.

  In the Z-axis direction, a part of the first electrode layer 11 does not overlap with, for example, the second electrode layer 12. The total area of the first surface 11a of the first electrode layer 11 (the surface on the first main surface 10a side) is, for example, the third surface 12a of the second electrode layer 12 (the surface on the first main surface 10a side). Is greater than the sum of the areas. In other words, when viewed along the Z-axis direction, the total area of the first electrode layers 11 is larger than the total area of the second electrode layers 12. Thereby, the in-plane uniformity of the plasma density can be further improved.

  Hereinafter, a method for manufacturing the ceramic dielectric substrate 10 in which the first electrode layer 11 and the second electrode layer 12 are provided will be described.

  The ceramic dielectric substrate 10 in which the first electrode layer 11 and the second electrode layer 12 are provided is, for example, laminated with the first main surface 10a side down, and the laminated body is sintered. It can be manufactured by the following. More specifically, for example, the second electrode layer 12 is laminated on the first layer serving as the ceramic layer including the first main surface 10a. On the second electrode layer 12, a second layer serving as a ceramic layer between the first electrode layer 11 and the second electrode layer 12 is laminated. The first electrode layer 11 is laminated on the second layer. On the first electrode layer 11, a third layer serving as a ceramic layer including the second main surface 10b is laminated. Then, the laminate is sintered.

  The first electrode layer 11 is formed by, for example, screen printing, application of a paste (spin coating, coater, inkjet, dispenser, or the like), vapor deposition, or the like. For example, the first electrode layer 11 can be formed by laminating each layer a plurality of times with the first main surface 10a facing down. At this time, the distance D2d between the first surface 11a and the second surface 11b at the end 11d and the distance between the first surface 11a and the second surface 11b at the center 11c, for example, by adjusting the lamination range. The relationship with D2c can satisfy D2d <D2c.

FIG. 8 is a cross-sectional view schematically illustrating a wafer processing apparatus including the electrostatic chuck according to the embodiment.
As shown in FIG. 8, the wafer processing apparatus 500 includes a processing container 501, a high-frequency power supply 504, a power supply for suction 505, an upper electrode 510, and the electrostatic chuck 100. On the ceiling of the processing container 501, a processing gas inlet 502 for introducing a processing gas into the inside, and an upper electrode 510 are provided. The bottom plate of the processing container 501 is provided with an exhaust port 503 for evacuating and exhausting the inside. The electrostatic chuck 100 is disposed below the upper electrode 510 inside the processing container 501. The first electrode layer 11 and the upper electrode 510 of the electrostatic chuck 100 are connected to a high frequency power supply 504. The second electrode layer 12 of the electrostatic chuck 100 is connected to a power supply 505 for suction.

  The first electrode layer 11 and the upper electrode 510 are provided substantially in parallel at a predetermined interval from each other. More specifically, the first surface 11a of the first electrode layer 11 is substantially parallel to the lower surface 510a of the upper electrode 510. The first main surface 10a of the ceramic dielectric substrate 10 is substantially parallel to the lower surface 510a of the upper electrode 510. The object W is placed on the first main surface 10a located between the first electrode layer 11 and the upper electrode 510.

  When a voltage (high-frequency voltage) is applied from the high-frequency power supply 504 to the first electrode layer 11 and the upper electrode 510, a high-frequency discharge occurs, and the processing gas introduced into the processing container 501 is excited and activated by the plasma, and the target is heated. The object W is processed.

  When a voltage (attraction voltage) is applied to the second electrode layer 12 from the attraction power supply 505, electric charges are generated on the first main surface 10a side of the second electrode layer 12, and the object W is electrostatically charged by the electrostatic force. The chuck 100 sucks and holds the chuck.

FIGS. 9A to 9D are cross-sectional views schematically illustrating an enlarged end portion of the first electrode layer according to the embodiment.
As shown in FIGS. 9A to 9D, the width t, which is the length in the X-axis direction of the end 11 d of the first electrode layer 11 in a cross-sectional view, is, for example, the first electrode layer 11. It is larger than the thickness D2c at the central portion 11c (thickness D2c <width t). The width t of the end 11d is, in other words, the width of the inclined surface of the second surface 11b. That is, the width t is the length in the X-axis direction between the lower end P of the inclined surface of the second surface 11b (where the inclination ends) and the edge 11e. As described above, by making the width t of the end 11d larger than the thickness D2c of the center 11c of the first electrode layer 11, the power supply distance can be shortened. Thereby, the responsiveness (RF responsiveness) to the control such as the change of the RF output can be further improved.

  The lower end P of the inclined surface can be obtained from a cross-sectional image of the sample cut so as to include the first electrode layer 11. In the embodiment, for example, at least one of the samples satisfies the above relationship (thickness D2c <width t). In the embodiment, it is more preferable that a plurality of locations in the sample satisfy the above relationship (thickness D2c <width t).

  The angle θ of the inclined surface of the second surface 11b is, for example, not less than 10 degrees and not more than 80 degrees, preferably not less than 20 degrees and not more than 60 degrees. Is the angle between the first surface 11a and the line L (a sub-angle) when a straight line connecting the edge 11e and the lower end P (where the inclination ends) of the inclined surface of the second surface 11b is defined as a line L. ). By reducing the angle θ, the power supply distance can be shortened. Thereby, the responsiveness (RF responsiveness) to the control such as the change of the RF output can be further improved.

  In these figures, the section between the lower end P and the edge 11e has a curved cross-sectional shape, but the section between the lower end P and the edge 11e is not limited to this, and may have a linear cross-sectional shape. With the linear shape, for example, the power supply distance can be further reduced.

  As described above, according to the embodiment, it is possible to provide an electrostatic chuck that can increase the RF responsiveness while improving the in-plane uniformity of the plasma density.

  The embodiment of the invention has been described. However, the invention is not limited to these descriptions. With respect to the above-described embodiments, those to which a person skilled in the art has appropriately changed the design are also included in the scope of the present invention as long as they have the features of the present invention. For example, the shape, size, material, arrangement, installation form, and the like of each element included in the electrostatic chuck are not limited to those illustrated, and can be appropriately changed. In addition, each element included in each of the embodiments described above can be combined as far as technically possible, and a combination of these elements is also included in the scope of the present invention as long as it includes the features of the present invention.

  Reference Signs List 10 ceramic dielectric substrate, 10a first main surface, 10b second main surface, 11, 11A, 11B first electrode layer, 11a first surface, 11b second surface, 11c central portion, 11d end portion, 11e edge portion, 11p hole, 12 second electrode layer, 12a third surface, 12b fourth surface, 13 convex portion, 14 groove, 15 through hole, 20 connecting portion, 50 base plate, 50a upper portion, 50b lower portion, 51 input path, 52 output path , 53 gas introduction path, 55 communication path, 60 adhesive member, 100 electrostatic chuck, 500 wafer processing apparatus, 501 processing container, 502 processing gas introduction port, 503 exhaust port, 504 high frequency power supply, 505 suction power supply, 510 upper electrode , 510a Lower surface, D1, D1c, D1d, D2c, D2d, D3, D4 Distance, P lower end, R1 area , T width, W object

Claims (15)

A ceramic dielectric substrate having a first main surface on which an object to be adsorbed is placed, and a second main surface opposite to the first main surface;
A base plate supporting the ceramic dielectric substrate,
At least one first electrode layer provided inside the ceramic dielectric substrate and connected to a high-frequency power supply;
At least one second electrode layer provided inside the ceramic dielectric substrate and connected to a power supply for suction;
With
The first electrode layer is provided between the first main surface and the second main surface in a Z-axis direction from the base plate to the ceramic dielectric substrate,
The second electrode layer is provided between the first electrode layer and the first main surface in the Z-axis direction,
In the electrostatic chuck, the first electrode layer has a first surface on the first main surface side and a second surface opposite to the first surface, and is supplied with power from the second surface side. ,
The distance along the Z-axis direction between the first surface and the first main surface is constant,
The distance along the Z-axis direction between the second surface and the first surface at the end of the first electrode layer is equal to the distance between the second surface and the first surface at the center of the first electrode layer. An electrostatic chuck having a distance smaller than the distance along the Z-axis direction.   2. The electrostatic chuck according to claim 1, wherein a total area of the first surface of the first electrode layer is larger than a total area of a surface on the first main surface side of the second electrode layer. 3. .   The electrostatic chuck according to claim 1, wherein a part of the first electrode layer does not overlap with the second electrode layer in the Z-axis direction.   The electrostatic chuck according to claim 1, wherein a thickness of the first electrode layer is larger than a thickness of the second electrode layer.   The distance along the Z-axis direction between the second surface and the first surface at the center of the first electrode layer is 1 μm or more and 500 μm or less. An electrostatic chuck according to one of the preceding claims.   The electrostatic chuck according to claim 5, wherein a distance along the Z-axis direction between the second surface and the first surface at a central portion of the first electrode layer is 10 µm or more and 100 µm or less. .   The electrostatic chuck according to any one of claims 1 to 6, wherein the first electrode layer includes at least one of Ag, Pd, and Pt.   The electrostatic chuck according to any one of claims 1 to 7, wherein the first electrode layer is made of a cermet of a metal and a ceramic.   9. The electrostatic chuck according to claim 8, wherein the ceramic contains the same element as the ceramic contained in the ceramic dielectric substrate.   9. The electrostatic chuck according to claim 8, wherein the ceramic contains an element different from the ceramic contained in the ceramic dielectric substrate. The first electrode layer includes a metal and a ceramic,
The second electrode layer includes a metal and a ceramic,
The ratio of the volume of the metal to the sum of the volume of the metal and the volume of the ceramic included in the first electrode layer is based on the sum of the volume of the metal and the volume of the ceramic included in the second electrode layer. The electrostatic chuck according to any one of claims 1 to 10, wherein the ratio is larger than a volume ratio of the metal. The first electrode layer includes a metal and a ceramic,
The second electrode layer includes a metal and a ceramic,
The electrostatic chuck according to claim 1, wherein a volume of the metal included in the first electrode layer is larger than a volume of the metal included in the second electrode layer. . The ceramic dielectric substrate includes aluminum oxide,
The electrostatic chuck according to claim 1, wherein a concentration of the aluminum oxide in the ceramic dielectric substrate is 90% by mass or more.   The distance along the Z-axis direction between the first electrode layer and the second electrode layer is larger than the distance along the Z-axis direction between the first main surface and the second electrode layer. The electrostatic chuck according to claim 1, wherein:   The width of the end portion is greater than a distance along the Z-axis direction between the second surface and the first surface in the central portion of the first electrode layer. The electrostatic chuck according to any one of the above.

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