TW202111856A - Electrostatic chuck - Google Patents

Abstract

The present invention provides an electrostatic chuck capable of increasing RF responsiveness while increasing thickness uniformity of plasma density. The electrostatic chuck comprises: a ceramic dielectric substrate having a first circumferential surface and a second circumferential surface; a base plate; a first electrode layer formed in the ceramic dielectric substrate and connected to a high-frequency power source; and a second electrode layer formed in the ceramic dielectric substrate and connected to a power source for suction. The first electrode layer is formed between the first circumferential surface and the second circumferential surface in a Z-axis direction. The second electrode layer is formed between the first electrode layer and the first circumferential surface in the Z-axis direction. The first electrode layer has a first surface and a second surface opposite to the first surface. Power is fed from the second surface side. The distance in the Z-axis direction between the first surface and the first circumferential surface is constant. The distance in the Z-axis direction between the first surface and the second surface at the end of the first electrode layer is smaller than the distance in the Z-axis direction between the first surface and the second surface at the center of the first electrode layer.

Description

Electrostatic chuck

The aspect of the present invention generally relates to electrostatic chuck.

In a plasma processing chamber for etching, CVD (Chemical Vapor Deposition), sputtering, ion implantation, ashing, etc. The electrostatic chuck is used as a means for sucking and holding processing objects such as semiconductor wafers or glass substrates. The electrostatic chuck applies electric power for electrostatic adsorption to the built-in electrodes, and uses electrostatic force to adsorb silicon wafers and other substrates.

When plasma processing is performed, for example, an RF (Radio Frequency) power supply (high-frequency power supply) applies a voltage to the upper electrode arranged in the upper part of the reaction chamber and the lower electrode arranged below the upper electrode to generate plasma .

In the conventional electrostatic chuck, a base plate disposed under the electrostatic chuck is used as a lower electrode to generate plasma. However, when an appropriate frequency is selected and further control of the plasma density distribution within the wafer plane is required, there is a limit to the plasma control of this configuration.

Therefore, in recent years, attempts have been made to build a lower electrode for plasma generation in a dielectric layer arranged on the bottom plate to improve plasma controllability. However, there is a problem that the in-plane uniformity of the plasma density cannot be sufficiently obtained when only the lower electrode is built into the dielectric layer.

Furthermore, in recent years, in addition to improving the in-plane uniformity of the plasma density, it is required to further improve the responsiveness (RF responsiveness) of control such as changes in the RF output.

[Patent Document 1]: Japanese Patent Application Publication No. 2008-277847 [Patent Document 2]: Japanese Patent Application Publication No. 2011-119654 [Patent Document 3]: Japanese Patent Application Publication No. 2004-103648 [Patent Document 4]: Japanese Patent Application Publication No. 2016-201411

The purpose of the present invention is to provide an electrostatic chuck which can improve the in-plane uniformity of the plasma density and at the same time improve the RF responsiveness.

The first invention is an electrostatic chuck, which is characterized by comprising: a ceramic dielectric substrate having: a first principal surface (principal surface) on which an object to be adsorbed is placed, and a first principal surface opposite to the aforementioned first principal surface The second main surface of the side; the bottom plate, supporting the aforementioned ceramic dielectric substrate; at least one first electrode layer, arranged inside the aforementioned ceramic dielectric substrate, connected to the high-frequency power supply; at least one second electrode layer, with The first electrode layer is arranged inside the ceramic dielectric substrate and connected to the power supply for suction. The first electrode layer is arranged on the first main surface and the second main surface in the Z-axis direction from the bottom plate to the ceramic dielectric substrate. Between the main surfaces, the second electrode layer is arranged between the first electrode layer and the first main surface in the Z-axis direction, and the first electrode layer has a first surface on the first main surface side, The second surface opposite to the first surface is powered from the second surface side, the distance between the first surface and the first main surface along the Z axis direction is constant, and the first electrode layer The distance between the second surface and the first surface along the Z-axis direction in the end portion of the first electrode layer is smaller than the distance between the second surface and the first surface in the central portion of the first electrode layer The aforementioned distance in the Z-axis direction.

According to this electrostatic chuck, by arranging the first electrode layer connected to the high-frequency power supply inside the ceramic dielectric substrate, for example, the upper electrode for plasma generation and the first electrode layer arranged above the electrostatic chuck can be shortened. The distance between one electrode layer (lower electrode). According to this, for example, compared with the case where the bottom plate is used as the lower electrode for plasma generation, the plasma density can be increased with low power. Furthermore, according to this electrostatic chuck, by making the distance along the Z-axis direction between the first surface and the first main surface constant, the in-plane uniformity of the plasma density can be improved. Generally, when alternating current flows on the electrode, the current density is high on the electrode surface, and the farther away from the surface, the lower the current density is called skin effect. It is known that the higher the frequency of the alternating current, the greater the concentration of the current toward the surface. In the present invention, since the first electrode layer is connected to the high-frequency power source, it can be considered that the skin effect is generated in the first electrode layer, and the alternating current applied from the high-frequency power source is transmitted and flows on the surface of the first electrode layer. According to this electrostatic chuck, in the first electrode layer connected to the high-frequency power supply from the second surface side and supplied with power, the end portion of the first electrode layer between the second surface and the first surface is along the Z-axis direction The distance of is smaller than the distance along the Z-axis direction between the second surface and the first surface in the central portion of the first electrode layer. Therefore, the power supply distance from the second surface to the first surface can be shortened. According to this, it is possible to improve the responsiveness (RF responsiveness) of control such as changes in the RF output. In addition, conventionally, a second electrode layer connected to a power supply for adsorption is arranged inside a dielectric substrate. In addition, the following new problem was discovered: the first electrode layer connected to the high-frequency power source is arranged inside the ceramic dielectric substrate, and the power applied to the first electrode layer is increased in order to increase the plasma density. In the case of power conversion, the environment in the reaction chamber changes due to the heat generated by the first electrode layer, which adversely affects the in-plane uniformity of the plasma density. According to the electrostatic chuck, the distance along the Z-axis direction between the second surface and the first surface in the end of the first electrode layer is made smaller than the second surface and the first surface in the central portion of the first electrode layer. The distance between the surfaces along the Z-axis direction can relatively increase the surface area of the second surface of the first electrode layer on the side of the bottom plate that has a cooling function. According to this, the first electrode layer can dissipate heat more effectively, and the in-plane uniformity of the plasma density can be further improved.

The second invention is an electrostatic chuck characterized in that, in the first invention, the total area of the first surface of the first electrode layer is larger than the area of the surface on the first main surface side of the second electrode layer. total.

According to this electrostatic chuck, by making the total area of the first surface of the first electrode layer larger than the total area of the surface on the first main surface side of the second electrode layer, the in-plane uniformity of the plasma density can be further improved.

The third invention is an electrostatic chuck, characterized in that in the first invention, in the Z-axis direction, a part of the first electrode layer does not overlap with the second electrode layer.

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

The fourth invention is an electrostatic chuck characterized in that, in any one of the first to third inventions, the thickness of the first electrode layer is greater than the thickness of the second electrode layer.

According to the electrostatic chuck, by making the thickness of the first electrode layer greater 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 improved. It has been found that if the first electrode layer connected to the high-frequency power source is simply thickened, there is a concern that the RF responsiveness will deteriorate. In the present invention, the thickness of the first electrode layer is increased. On the other hand, the distance between the second surface and the first surface in the end of the first electrode layer along the Z-axis direction is smaller than that of the first electrode layer. The distance along the Z-axis direction between the second surface and the first surface in the central portion. Therefore, the influence of the skin effect can be reduced, and the reduction in RF responsiveness can be suppressed at the same time.

The fifth invention is an electrostatic chuck characterized in that, in any one of the first to fourth inventions, the gap between the second surface and the first surface in the central portion of the first electrode layer The distance along the aforementioned Z-axis direction is 1 μm or more and 500 μm or less.

According to the electrostatic chuck, the distance in the Z-axis direction between the second surface and the first surface in the center portion of the first electrode layer (the thickness of the first electrode layer in the center portion) is within this range, The skin effect can be reduced, the in-plane uniformity of the plasma density can be improved, and the decrease in RF responsiveness can be suppressed.

The sixth invention is an electrostatic chuck, characterized in that, in the fifth invention, the distance between the second surface and the first surface in the central portion of the first electrode layer along the Z-axis direction is 10 μm Above and below 100μm.

According to the electrostatic chuck, the distance in the Z-axis direction between the second surface and the first surface in the center portion of the first electrode layer (the thickness of the first electrode layer in the center portion) is within this range, The skin effect can be reduced, the in-plane uniformity of the plasma density can be improved, and the decrease in RF responsiveness can be suppressed.

The seventh invention is an electrostatic chuck characterized in that in any one of the first to sixth inventions, the first electrode layer includes at least any one of Ag, Pd, and Pt.

In this way, according to the electrostatic chuck related to the embodiment, for example, a first electrode layer containing a metal such as Ag, Pd, and Pt can be used.

The eighth invention is an electrostatic chuck characterized in that, in any one of the first to seventh inventions, the first electrode layer is made of a cermet of metal and ceramic.

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

The ninth invention is an electrostatic chuck, characterized in that in the eighth invention, the ceramic contains the same elements as the ceramic included in the ceramic dielectric substrate.

According to the electrostatic chuck, by forming the first electrode layer with ceramic cermet containing the same elements as the ceramic contained in the ceramic dielectric substrate, the coefficient of thermal expansion and the coefficient of thermal expansion of the first electrode layer can be reduced. The difference in the thermal expansion coefficient of the ceramic dielectric substrate. According to this, the adhesion between the first electrode layer and the ceramic dielectric substrate can be improved, and defects such as peeling can be suppressed.

The tenth invention is an electrostatic chuck, characterized in that in the eighth invention, the ceramic contains an element different from the ceramic contained in the ceramic dielectric substrate.

In this way, according to the electrostatic chuck related to the embodiment, by forming the first electrode layer with a ceramic cermet containing elements different from the ceramic contained in the ceramic dielectric substrate, thermal characteristics, mechanical characteristics, and electrical characteristics can be arbitrarily designed. Features, etc.

The eleventh invention is an electrostatic chuck characterized in that in any one of the first to tenth inventions, the first electrode layer includes metal and ceramic, and the second electrode layer includes metal and ceramic. The ratio of the volume of the metal to the total volume of the metal contained in the first electrode layer and the volume of the ceramic is greater than the sum of the volume of the metal contained in the second electrode layer and the volume of the ceramic The ratio of the volume of the metal.

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

The twelfth invention is an electrostatic chuck characterized in that, in any one of the first to tenth inventions, the first electrode layer includes metal and ceramic, the second electrode layer includes metal and ceramic, and The volume of the metal contained in the first electrode layer is greater than the volume of the metal contained in the second electrode layer.

According to the 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 resistance of the first electrode layer to which a voltage is applied from a high-frequency power supply can be further reduced. Improve in-plane uniformity of plasma density and RF responsiveness.

The thirteenth invention is an electrostatic chuck, characterized in that, in any one of the first to twelfth inventions, the ceramic dielectric substrate contains alumina, and the oxide in the ceramic dielectric substrate The concentration of aluminum is 90% by mass or more.

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

The fourteenth invention is an electrostatic chuck characterized in that, in any one of the first to thirteenth inventions, the distance between the first electrode layer and the second electrode layer is along the Z-axis direction The distance is greater than the distance between the first main surface and the second electrode layer along the Z-axis direction.

According to the electrostatic chuck, by making the distance along the Z axis between the first electrode layer and the second electrode layer greater than the distance along the Z axis between the first main surface and the second electrode layer, even if it is from high When a voltage is applied from a high-frequency power supply, it is also possible to more effectively suppress defects such as short-circuit and/or dielectric breakdown between the first electrode layer and the second electrode layer.

The fifteenth invention is an electrostatic chuck, characterized in that, in any one of the first to fourteenth inventions, the width of the end portion is greater than that of the second in the center portion of the first electrode layer. The distance between the surface and the first surface along the Z-axis direction.

According to the electrostatic chuck, by making the width of the end of the first electrode layer larger than the distance along the Z axis between the second surface and the first surface in the central portion of the first electrode layer (that is, the first electrode The thickness in the center of the layer), the power supply distance can be shortened. According to this, it is possible to further improve the responsiveness (RF responsiveness) of control such as changes in the RF output.

The sixteenth invention is an electrostatic chuck characterized by comprising: 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 a bottom plate , Supporting the ceramic dielectric substrate; at least one electrode layer, arranged inside the ceramic dielectric substrate, connected to a high-frequency power supply, the electrode layer in the Z-axis direction from the base plate toward the ceramic dielectric substrate The upper surface is arranged between the first main surface and the second main surface, and the electrode layer has a first surface on the first main surface side and a second surface on the opposite side of the first surface. Power is supplied to the surface side, the electrode layer contains metal and ceramic cermet, the distance between the first surface and the first main surface along the Z-axis direction is constant, and the second surface at the end of the electrode layer The distance between the surface and the first surface along the Z-axis direction is smaller than the distance between the second surface and the first surface in the central portion of the electrode layer along the Z-axis direction.

According to this electrostatic chuck, by arranging the electrode layer connected to the high-frequency power supply inside the ceramic dielectric substrate, it is possible to shorten the upper electrode and the electrode layer (lower part) for plasma generation arranged above the electrostatic chuck. The distance between the electrodes). According to this, for example, compared with the case where the bottom plate is used as the lower electrode for plasma generation, the plasma density can be increased with low power. Furthermore, according to this electrostatic chuck, by making the distance along the Z-axis direction between the first surface and the first main surface constant, the in-plane uniformity of the plasma density can be improved. Generally, when alternating current flows on the electrode, the current density is high on the electrode surface, and the farther away from the surface, the lower it is called skin effect. It is known that the higher the frequency of the alternating current, the greater the concentration of the current toward the surface. In the present invention, since the electrode layer is connected to the high-frequency power source, it can be considered that a skin effect is generated in the electrode layer, and the alternating current applied from the high-frequency power source is transmitted and flows on the surface of the electrode layer. According to this electrostatic chuck, in the electrode layer connected to the high-frequency power supply from the second surface side, the distance between the second surface and the first surface in the end of the electrode layer along the Z-axis direction is smaller than that of the electrode layer. The distance along the Z-axis direction between the second surface and the first surface in the central portion of the layer. Therefore, the power supply distance from the second surface to the first surface can be shortened. According to this, it is possible to improve the responsiveness (RF responsiveness) of control such as changes in the RF output. In addition, the following new problem was discovered: the case where the electrode layer connected to the high-frequency power supply is arranged inside the ceramic dielectric substrate, and the power supply applied to the electrode layer is increased in order to increase the plasma density. In particular, the environment in the reaction chamber changes due to the heat generated by the electrode layer, which adversely affects the in-plane uniformity of the plasma density. According to the electrostatic chuck, the distance along the Z-axis direction between the second surface and the first surface in the end portion of the electrode layer is smaller than the distance between the second surface and the first surface in the center portion of the electrode layer. The distance along the Z-axis direction can relatively increase the surface area of the second surface of the electrode layer on the bottom plate side that has a cooling function. According to this, the electrode layer can dissipate heat more effectively, and the in-plane uniformity of the plasma density can be improved. Furthermore, according to the electrostatic chuck, by forming the electrode layer with cermet, the adhesion between the electrode layer and the ceramic dielectric substrate can be improved, and the strength of the electrode layer can be improved.

The seventeenth invention is an electrostatic chuck, characterized in that, in the sixteenth invention, the distance between the second surface and the first surface in the center portion of the electrode layer along the Z-axis direction is 1 μm Above and below 500μm.

According to this electrostatic chuck, by setting the distance along the Z-axis direction (the thickness of the electrode layer in the center portion) between the second surface and the first surface in the center portion of the electrode layer within this range, the skin can be reduced. The influence of the effect can further improve the in-plane uniformity of the plasma density while suppressing the decrease in RF responsiveness.

The eighteenth invention is an electrostatic chuck, characterized in that, in the seventeenth invention, the distance between the second surface and the first surface in the center portion of the electrode layer along the Z-axis direction is 10 μm Above and below 100μm.

According to this electrostatic chuck, by setting the distance along the Z-axis direction (the thickness of the electrode layer in the center portion) between the second surface and the first surface in the center portion of the electrode layer within this range, the skin can be reduced. The influence of the effect can further improve the in-plane uniformity of the plasma density while suppressing the decrease in RF responsiveness.

The nineteenth invention is an electrostatic chuck characterized in that, in any one of the sixteenth to eighteenth inventions, the electrode layer includes at least any one of Ag, Pd, and Pt.

In this way, according to the electrostatic chuck according to the embodiment, for example, an electrode layer of a cermet containing a metal such as Ag, Pd, and Pt and a ceramic can be used.

The twentieth invention is an electrostatic chuck characterized in that, in any one of the sixteenth to nineteenth inventions, the ceramic includes the same elements as the ceramic included in the ceramic dielectric substrate.

According to the electrostatic chuck, by forming the electrode layer with ceramic cermet containing the same elements as the ceramic contained in the ceramic dielectric substrate, the difference between the thermal expansion coefficient of the electrode layer and the thermal expansion coefficient of the ceramic dielectric substrate can be reduced . Accordingly, the adhesion between the electrode layer and the ceramic dielectric substrate can be improved, and defects such as peeling can be suppressed.

The twenty-first invention is an electrostatic chuck characterized in that, in any one of the sixteenth to nineteenth inventions, the ceramic includes an element different from the ceramic included in the ceramic dielectric substrate.

In this way, according to the electrostatic chuck related to the embodiment, by forming the electrode layer with a ceramic cermet containing elements different from the ceramic contained in the ceramic dielectric substrate, thermal characteristics, mechanical characteristics, electrical characteristics, etc. can be arbitrarily designed .

The twenty-second invention is an electrostatic chuck characterized in that, in any one of the sixteenth to twenty-first inventions, the ceramic dielectric substrate includes alumina, and the ceramic dielectric substrate The concentration of the aforementioned alumina is 90% by mass or more.

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

The twenty-third invention is an electrostatic chuck, characterized in that in any one of the sixteenth to twenty-second inventions, the aforementioned electrode layer is connected to a power source for adsorption.

In this way, according to the electrostatic chuck according to the embodiment, the electrode layer of the lower electrode for generating plasma can also be used as an adsorption electrode for adsorbing an object.

The twenty-fourth invention is an electrostatic chuck characterized in that, in any one of the sixteenth to twenty-third inventions, the width of the end portion is greater than the width of the end portion in the center portion of the electrode layer. The distance between the two surfaces and the first surface along the Z-axis direction.

According to this electrostatic chuck, by making the width of the end of the electrode layer larger than the distance along the Z-axis between the second surface and the first surface in the central portion of the electrode layer (that is, the distance in the central portion of the electrode layer) Thickness), can shorten the power supply distance. According to this, it is possible to further improve the responsiveness (RF responsiveness) of control such as changes in the RF output.

Hereinafter, the embodiments of the present invention will be described with reference to the drawings. In addition, in each drawing, the same symbol is attached to the same constituent element, and detailed description is abbreviate|omitted suitably. Fig. 1 is a schematic cross-sectional view illustrating an electrostatic chuck related to the embodiment. As shown in FIG. 1, the electrostatic chuck 100 includes a ceramic dielectric substrate 10, a first electrode layer 11 and a second electrode layer 12, and a bottom plate 50.

The ceramic dielectric substrate 10 is a flat substrate made of, for example, sintered ceramics. For example, the ceramic dielectric substrate 10 includes alumina (alumina: Al ₂ O ₃ ). For example, the ceramic dielectric substrate 10 is formed of high-purity alumina. The concentration of alumina in the ceramic dielectric substrate 10 is, for example, 90 mass% or more and 100 mass% or less, preferably 95 mass% or more, 100 mass% or less, more preferably 99 mass% ( mass%) above but below 100mass%. By using high-purity alumina, the plasma resistance of the ceramic dielectric substrate 10 can be improved. In addition, the concentration of alumina 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 sucked object W is placed. The second main surface 10b is a surface on the opposite side to the first main surface 10a. The object W to be adsorbed is, for example, a semiconductor substrate such as a silicon wafer.

In addition, in the specification of the present application, the direction from the base plate 50 toward the ceramic dielectric substrate 10 is referred to as the 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 figure. The Z-axis direction is, for example, a direction slightly perpendicular to the first main surface 10a and the second main surface 10b. One of the directions orthogonal to the Z-axis direction is regarded as the X-axis direction, and the directions orthogonal to the Z-axis direction and the X-axis direction are regarded as the Y-axis direction. In the specification of this case, [in-plane] means, for example, in the X-Y plane.

A first electrode layer 11 and a second electrode layer 12 are arranged inside the ceramic dielectric substrate 10. The first electrode layer 11 and the second electrode layer 12 are arranged between the first main surface 10a and the second main surface 10b. In other words, the first electrode layer 11 and the second electrode layer 12 are arranged to be inserted into the ceramic dielectric substrate 10. The first electrode layer 11 and the second electrode layer 12 may be built-in by integrally sintering the ceramic dielectric substrate 10, for example.

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.

In this way, by arranging the first electrode layer 11 inside the ceramic dielectric substrate 10, the upper electrode (the upper electrode 510 in FIG. 8) and the first electrode layer 11 arranged above the electrostatic chuck 100 can be shortened. The distance between the (lower electrodes). According to this, for example, compared with the case where the bottom plate 50 is used as the lower electrode, the plasma density can be increased with low electric power. In other words, the power required to obtain a high plasma density can be reduced.

The shapes of the first electrode layer 11 and the second electrode layer 12 are thin films along the first main surface 10 a and the second main surface 10 b of the ceramic dielectric substrate 10. The cross-sectional shape 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 source (high-frequency power source 504 in FIG. 8). By applying a voltage (high-frequency voltage) 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. In other words, the first electrode layer 11 is a lower electrode for generating plasma. The high-frequency power supply supplies high-frequency AC (alternating current) current to the first electrode layer 11. The "high frequency" referred to here is, for example, 200 kHz or more.

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

The metal contained in the cermet includes, for example, at least any one of Ag, Pd, and Pt. In addition, 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 elements as the ceramic contained in the ceramic dielectric substrate 10, the thermal expansion coefficient of the first electrode layer 11 and the thermal expansion of the ceramic dielectric substrate 10 can be reduced The difference in coefficients. Accordingly, the adhesion between the first electrode layer 11 and the ceramic dielectric substrate 10 can be improved, and defects such as peeling can be suppressed. In addition, the ceramic contained in the cermet may also contain an element different from the ceramic contained in the ceramic dielectric substrate 10.

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

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

When the first electrode layer 11 contains metal and ceramics, and the second electrode layer 12 contains metal and ceramics, the ratio of the volume of the metal to the total volume of the metal contained in the first electrode layer 11 and the volume of the ceramic is greater than that of the first electrode layer 11 The ratio of the total volume of the metal to the volume of the ceramic contained in the second electrode layer 12 is preferable.

In this way, by making the ratio of the metal contained in the first electrode layer 11 larger than the ratio of the metal contained in the second electrode layer 12, for example, the resistance of the first electrode layer 11 to which a voltage is applied from a high-frequency power supply can be further reduced. Improve in-plane uniformity of plasma density and RF responsiveness.

In the embodiment, the ratio of the volume of the metal to the total volume of the ceramic can be observed by SEM-EDX (Energy Dispersive X-ray Spectroscopy: Energy Dispersive X-ray Spectroscopy). The cross section of the second electrode layer 12 is obtained by image analysis. More specifically, the cross-sectional SEM-EDX images of the first electrode layer 11 and the second electrode layer 12 are obtained, classified into ceramics and metals by EDX component analysis, and the area ratio of ceramics and metals can be calculated by image analysis. The ratio of the volume of the metal to the total volume of the metal and the volume of the ceramic.

When the first electrode layer 11 includes metal and ceramic, and the second electrode layer 12 includes metal and ceramic, the volume of the metal included in the first electrode layer 11 is preferably greater than the volume of the metal included in the second electrode layer 12.

In this way, by making the volume of the metal contained in the first electrode layer 11 larger than the volume of the metal contained in the second electrode layer 12, for example, the resistance of the first electrode layer 11 to which a voltage is applied from a high-frequency power supply can be further reduced. Improve in-plane uniformity of plasma density and RF responsiveness.

The second electrode layer 12 is provided with a connection portion 20 extending on the second main surface 10 b side 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 bottom plate 50 is a member that supports the ceramic dielectric substrate 10. The ceramic dielectric substrate 10 is fixed on the bottom plate 50 by an adhesive member 60. As the adhesive member 60, for example, a silicone adhesive is used.

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

The bottom plate 50 also plays a role of adjusting the temperature of the electrostatic chuck 100. For example, when the electrostatic chuck 100 is cooled, a cooling medium (cooling medium) such as helium gas flows in from the input channel 51, passes through the connecting channel 55, and flows out from the output channel 52. Accordingly, by absorbing the heat of the bottom plate 50 by the cooling medium, the ceramic dielectric substrate 10 mounted thereon can be cooled. On the other hand, when the electrostatic chuck 100 is kept warm, a heat preservation medium can also be placed in the connecting channel 55. A heating element (heating element) can also be built in the ceramic dielectric substrate 10 or the base plate 50. By adjusting the temperature of the bottom plate 50 or the ceramic dielectric substrate 10, the temperature of the object W held by the electrostatic chuck 100 can be adjusted.

In this example, a groove 14 is provided on the first main surface 10 a side of the ceramic dielectric substrate 10. The groove 14 is recessed in the direction (Z-axis direction) from the first main surface 10a to the second main surface 10b, and extends continuously in the X-Y plane. If the portion where the groove 14 is not provided is regarded as the convex portion 13, the object W is placed on the convex portion 13. The first main surface 10a is a surface in contact with the back surface of the object W. That is, the first main surface 10 a is a flat surface including the top 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 arranged 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 10 b to the first main surface 10 a, and penetrates the ceramic dielectric substrate 10.

By appropriately selecting the height of the protrusion 13 (the depth of the groove 14), the area ratio of the protrusion 13 and the groove 14, the shape, etc., the temperature of the object W or the particles attached to the object W can be controlled at a relatively high level. Good condition.

The bottom plate 50 is provided with a gas introduction passage 53. The gas introduction path 53 is arranged so as to penetrate the bottom plate 50, for example. The gas introduction path 53 may not penetrate the bottom plate 50 but branch from the middle of another gas introduction path 53 and may be arranged on the ceramic dielectric substrate 10 side. In addition, the gas introduction passage 53 may be arranged in a plurality of places on the bottom plate 50.

The gas introduction passage 53 communicates with the through hole 15. That is, the transport gas (helium (He), etc.) that has flowed into the gas introduction channel 53 flows into the through hole 15 after passing through the gas introduction channel 53.

The conveyed 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. According to this, the object W can be directly cooled by the conveying gas.

Fig. 2 is a cross-sectional view schematically showing an enlarged part of an electrostatic chuck according to the embodiment. 3(a) and 3(b) are cross-sectional views schematically showing modified examples of the first electrode layer of the electrostatic chuck according to the embodiment. Fig. 2 is an enlarged display of the region R1 shown in Fig. 1.

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 side of the first main surface 10a. The second surface 11b is a surface opposite to the first surface 11a. In other words, the first surface 11 a is 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. The distance D1 is, in other words, the distance from the first main surface 10a to the top surface (first surface 11a) of the first electrode layer 11. Here, "constant" means that, for example, the undulations of the first surface 11a can be included. For example, when observing the cross section of the electrostatic chuck 100 with a scanning electron microscope (SEM) or the like at a low magnification (for example, about 100 times), the distance D1 may be approximately constant. For example, the difference between the distance D1c in the central portion 11c of the first electrode layer 11 and the distance D1d in the end portion 11d of the first electrode layer 11 is 0±150 μm. The distance D1 (distance D1c and 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 11d of the first electrode layer 11 is a region including an edge 11e on the X-Y plane of the first electrode layer 11. The edge portion 11e of the first electrode layer 11 refers to the interface between the first electrode layer 11 and the ceramic dielectric substrate 10 when viewed from the Z-axis direction on the first surface 11a. The central portion 11c of the first electrode layer 11 is a region located between the two end portions 11d on the X-Y plane. The center part 11c and the end part 11d of the 1st electrode layer 11 are mentioned later.

In this way, by making the distance D1 between the first surface 11a and the first main surface 10a constant along the Z-axis direction, the upper electrode (upper electrode 510 in FIG. 8) and the first electrode layer 11 (lower electrode The distance between) is constant. According to this, for example, compared with the case where the distance D1 between the first surface 11a and the first main surface 10a along the Z-axis direction is not constant, the in-plane uniformity of the plasma density can be improved. For example, the cross-sectional shape of the first electrode layer 11 is convex upward, and the distance between the first surface 11a and the first main surface 10a in the end portion 11d along the Z-axis direction is different from that in the central portion 11c. Compared with the case of the distance along the Z-axis direction between the first surface 11a and the first main surface 10a, the in-plane uniformity of the plasma density can be improved.

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 in the end portion 11d of the first electrode layer 11 and the first surface 11a is smaller than the second surface in the central portion 11c of the first electrode layer 11. The distance D2c between the surface 11b and the first surface 11a along the Z-axis direction. The distance D2c is, in other words, the thickness of the first electrode layer 11 in the central portion 11c. The distance D2d is, in other words, the thickness of the first electrode layer 11 in the end 11d. That is, the thickness of the first electrode layer 11 in the end portion 11d is smaller than the thickness of the first electrode layer 11 in the central portion 11c. For example, the thickness of the first electrode layer 11 decreases from the center portion 11c to the end portion 11d. The first electrode layer 11 has a shape protruding to 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 influence of the skin effect can be reduced, and the in-plane uniformity of the plasma density can be further improved. The distance D2c can be obtained by, for example, an average value of the thickness of three points in the central portion 11c on the cross-sectional SEM (Scanning Electron Microscope) image of the first electrode layer 11. In the specification of this case, the average value is defined as the distance D2c.

The first electrode layer 11 is supplied with a high-frequency current from the second surface 11b side. Generally, when AC current flows through the electrode layer, a skin effect is generated in which the current density is high on the surface of the electrode layer and becomes lower as soon as it moves away from the surface. Moreover, the higher the high frequency of the flowing AC current, the more significant the surface concentration of the current is. That is, the high-frequency AC current flowing into the first electrode layer 11 from the second surface 11b side is conducted to the second surface 11b of the first electrode layer 11 and flows into the first surface 11a.

In the embodiment, the distance D2d between the second surface 11b and the first surface 11a in the end portion 11d of the first electrode layer 11 along the Z-axis direction is smaller than that in the center portion 11c of the first electrode layer 11. The distance D2c between the second surface 11b and the first surface 11a along the Z-axis direction can shorten the power supply distance from the second surface 11b for power supply to the first surface 11a. According to this, it is possible to further improve the responsiveness (RF responsiveness) of control such as changes in the RF output.

The present inventors have discovered the following new problem. The first electrode layer 11 connected to the high-frequency power supply is arranged inside the ceramic dielectric substrate 10, and then applied to the first electrode layer in order to increase the plasma density. When the high-frequency power supply of 11 increases, especially the first electrode layer 11 generates heat, the environment inside the reaction chamber (processing container 501 in FIG. 8) changes, and the in-plane uniformity of the plasma density is adversely affected. In contrast, according to the embodiment, the distance D2d between the second surface 11b and the first surface 11a in the end portion 11d of the first electrode layer 11 along the Z-axis direction is smaller than that in the central portion 11c of the first electrode layer 11 The distance D2c between the second surface 11b and the first surface 11a along the Z-axis direction. For example, by making the first electrode layer 11 protrude toward the second surface 11b side (that is, the bottom plate 50 side), the second surface of the first electrode layer 11 on the bottom plate 50 side with the cooling function can be relatively enlarged. Surface area of face 11b. According to this, the first electrode layer 11 can dissipate heat more effectively, and the in-plane uniformity of the plasma density can be further improved.

In addition, in this example, the thickness of the first electrode layer 11 is constant in the central portion 11c. In other words, in the central portion 11c, the second surface 11b is parallel to the first surface 11a. On the other hand, in the end portion 11d, the thickness of the first electrode layer 11 becomes smaller from the central portion 11c side toward the edge portion 11e. In other words, in the end portion 11d, the second surface 11b has an inclined surface inclined upward from the central portion 11c side toward the edge portion 11e. In this example, the inclined surface is flat. The inclined surface may be curved as shown in Fig. 3(a).

The cross-sectional shape of the first electrode layer 11 is not limited to this. For example, as shown in FIG. 3(b), the second surface 11b may have an inclined surface inclined upward from the center on the X-Y plane of the second surface 11b toward the edge portion 11e. In other words, in the central portion 11c, the thickness of the first electrode layer 11 may not be necessarily required. In other words, in the central portion 11c, the second surface 11b may not be parallel to the first surface 11a. In this case, the inclined surface may be curved as shown in FIG. 3(b).

As shown in FIG. 2, the second electrode layer 12 has a third surface 12a on the side of the first main surface 10a, and a fourth surface 12b on the opposite side of the third surface 12a. In other words, the fourth surface 12 b is a surface facing the first electrode layer 11. In other words, the fourth surface 12 b is a surface facing the first surface 11 a 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 constant, for example. The distance D3, in other words, is the distance from the first main surface 10a to the top surface of the second electrode layer 12 (third surface 12a).

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

The thickness of the first electrode layer 11 is, for example, greater than the thickness of the second electrode layer 12. By making the thickness of the first electrode layer 11 greater 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 improved.

The distance 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, greater than the first main The distance along the Z-axis direction between the surface 10a and the second electrode layer 12 (that is, the distance along the Z-axis direction between the third surface 12a and the first main surface 10a) D3.

In this way, by making the distance D5 larger than the distance D3, even when a voltage is applied from a high-frequency power supply, it is possible to more effectively suppress short-circuit and/or insulation breakdown between the first electrode layer 11 and the second electrode layer 12 Bad condition.

Figures 4(a), 4(b), 5(a), 5(b), 6(a) and 6(b) are top views schematically showing a part of the electrostatic chuck related to the embodiment . In these figures, in the electrostatic chuck 100, the part of the ceramic dielectric substrate 10 located on the side (lower side) of the bottom plate 50 is omitted instead of the first electrode layer 11 (second surface 11b), and the bottom plate 50 etc. are omitted. In the state, the top view of the first electrode layer 11 is seen from the second surface 11b side (lower side).

4(a), FIG. 4(b), FIG. 5(a), FIG. 5(b), FIG. 6(a), and FIG. 6(b), the electrostatic chuck 100 is, for example, arranged along XY At least one first electrode layer 11 with an enlarged plane. The number of the first electrode layer 11 may be one as shown in Fig. 4(a) and Fig. 4(b), or two as shown in Fig. 5(a) and Fig. 5(b), or as shown in Fig. 5(b). 6(a) and Fig. 6(b) show three or more (four in this example). When a plurality of first electrode layers 11 are arranged, each of the first electrode layers 11 may be located on the same plane, for example, or may be located on different planes in the Z-axis direction.

In the example shown in FIGS. 4(a) and 4(b), the circular first electrode layer 11 when viewed along the Z-axis direction, for example, is arranged such that the center of the first electrode layer 11 and the ceramic dielectric The centers of the substrates 10 overlap. The edge portion 11e of the first electrode layer 11 is concentric to the edge portion of the ceramic dielectric substrate 10, for example. In this example, the end 11 d of the first electrode layer 11 is arranged in a ring shape on the outer peripheral side of the ceramic dielectric substrate 10.

In the examples shown in FIGS. 5(a) and 5(b), for example, the inner first electrode layer 11A and the outer first electrode layer 11B are arranged concentrically. The inner first electrode layer 11A has a circular shape when viewed along the Z-axis direction, for example. The outer first electrode layer 11B has, for example, a circular ring 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 in a concentric circle in which the center of the inner first electrode layer 11A overlaps with the center of the ceramic dielectric substrate 10, for example. In this example, the end 11d of the outer first electrode layer 11B is arranged in a ring shape on the center side of the ceramic dielectric substrate 10 and the outer peripheral side of the ceramic dielectric substrate 10, respectively. Furthermore, the end 11d of the inner first electrode layer 11A is arranged in a ring shape on the outer peripheral side of the ceramic dielectric substrate. In addition, the number of the 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. 6(a) and 6(b), the plurality of first electrode layers 11 that are circular when viewed along the Z-axis direction are respectively arranged in the center of the ceramic dielectric substrate 10, for example. Become a point symmetrical position. In addition, one of the first electrode layers 11 may be arranged such that the center of the first electrode layer 11 overlaps with the center of the ceramic dielectric substrate 10. In other words, one of the first electrode layers 11 may be arranged in the center of the ceramic dielectric substrate 10. In this example, the end 11 d of each first electrode layer 11 is arranged in a ring shape on the outer peripheral side of each first electrode layer 11.

Furthermore, as shown in FIG. 4(b), FIG. 5(b), and FIG. 6(b), the first electrode layer 11 may be provided with a hole 11p that penetrates the first electrode layer 11 in the Z-axis direction. When the hole 11p is provided, the end 11d is also arranged near the outer periphery of the hole 11p.

In the embodiment, even at any of the end portions 11d, the distance D2d between the first surface 11a and the second surface 11b in the end portion 11d and the first surface 11a and the center portion 11c can be adjusted to The relationship of the distance D2c between the second surfaces 11b satisfies D2d<D2c. On the other hand, in the range that achieves the effect of the present invention, it is not excluded that a point that does not satisfy D2d<D2c is included. In other words, in the embodiment, it is only necessary to satisfy D2d<D2c in at least a part of the end portion 11d as described above. For example, if there are many places satisfying D2d<D2c in the end portion 11d, 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 X-Y plane. For example, in the first electrode layer 11, all regions other than the end portion 11d may be regarded as the center portion 11c. In other words, in the first electrode layer 11, for example, the vicinity of the edge portion 11e can be regarded as the end portion 11d, and the rest can be regarded as the center portion 11c.

7(a) and 7(b) are plan views schematically showing a part of the electrostatic chuck related to the embodiment. These figures are in the state where the portion of the ceramic dielectric substrate 10 on the first main surface 10a side (upper side) is omitted from the electrostatic chuck 100 instead of the second electrode layer 12 (third surface 12a). The top view of the second electrode layer 12 is seen from the third surface 12a side (upper side).

As shown in FIG. 7(a) and FIG. 7(b), the second electrode layer 12 may be a unipolar type or a bipolar type. When the second electrode layer 12 is of a unipolar type, as shown in FIG. 7(a), one second electrode layer 12 that expands along the X-Y plane is arranged. For example, the second electrode layer 12 has a slightly circular shape 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. 7(b), two second electrode layers 12 that expand along the X-Y plane and are located on the same plane are arranged. Each of the second electrode layers 12 has a substantially semicircular shape when viewed along the Z-axis direction, for example. The second electrode layer 12 may have a pattern expanded along the X-Y plane, for example.

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

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

The ceramic dielectric substrate 10 in which the first electrode layer 11 and the second electrode layer 12 are arranged can be obtained by, for example, laminating each layer with the first main surface 10a side facing down, and sintering the layered body. Make. More specifically, for example, the second electrode layer 12 is laminated on the first layer that is the ceramic layer including the first main surface 10a. A second layer which becomes a ceramic layer between the first electrode layer 11 and the second electrode layer 12 is laminated on the second electrode layer 12. The first electrode layer 11 is laminated on the second layer. On the first electrode layer 11, a third layer including a ceramic layer of the second main surface 10b is laminated. Then, the layered body is sintered.

The first electrode layer 11 is, for example, applied by screen printing, paste (spin coating), coater, ink-jet, dispenser (dispenser, etc.) and evaporation (evaporation). For example, in a state where the first main surface 10a faces downward, the first electrode layer 11 can be formed by laminating each layer in plural times. At this time, for example, by adjusting the stacking range, the distance D2d between the first surface 11a and the second surface 11b in the end portion 11d and the distance between the first surface 11a and the second surface 11b in the central portion 11c can be made The relationship of the distance D2c satisfies D2d<D2c.

Fig. 8 is a cross-sectional view schematically showing a wafer processing apparatus equipped with an 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 suction power supply 505, an upper electrode 510, and an electrostatic chuck 100. At the top of the processing container 501, a processing gas introduction port 502 for introducing processing gas into the interior, and an upper electrode 510 are provided. The bottom plate of the processing container 501 is provided with an exhaust port 503 for depressurizing and exhausting the inside. The electrostatic chuck 100 is arranged under the upper electrode 510 in the inside of 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 arranged substantially in parallel with each other at a predetermined interval. More specifically, the first surface 11 a of the first electrode layer 11 is slightly parallel to the bottom surface 510 a of the upper electrode 510. Furthermore, the first main surface 10a of the ceramic dielectric substrate 10 is slightly parallel to the bottom surface 510a of the upper electrode 510. The object W is placed on the first main surface 10 a between the first electrode layer 11 and the upper electrode 510.

If 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, high frequency discharge occurs, and the processing gas introduced into the processing container 501 is caused by plasma It is activated and activated, and the processing target object W is processed.

When a voltage (suction voltage) is applied to the second electrode layer 12 from the suction power supply 505, an electric charge is generated on the first main surface 10a side of the second electrode layer 12, and the object W is adsorbed and held on the electrostatic chuck by electrostatic force 100.

9(a) to 9(d) are cross-sectional views schematically showing the end of the first electrode layer related to the embodiment in an enlarged manner. As shown in FIGS. 9(a) to 9(d), the width t of the length in the X-axis direction of the end portion 11d of the first electrode layer 11 in a cross-sectional view is, for example, greater than that in the central portion 11c of the first electrode layer 11 Thickness D2c (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 (where the inclination ends) of the inclined surface of the second surface 11b and the edge portion 11e. In this way, by making the width t of the end portion 11d larger than the thickness D2c in the central portion 11c of the first electrode layer 11, the power supply distance can be shortened. According to this, it is possible to further improve the responsiveness (RF responsiveness) of control such as changes in the RF output.

The lower end P of the inclined surface can be obtained from a cross-sectional image of a 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-mentioned relationship (thickness D2c<width t). In the embodiment, it is more preferable that a plurality of places in the sample satisfy the above-mentioned relationship (thickness D2c<width t).

The angle θ of the inclined surface of the second surface 11b is, for example, 10 degrees or more and 80 degrees or less, and preferably 20 degrees or more and 60 degrees or less. The angle θ can be expressed as follows: when the line connecting the lower end P (the end of the inclination) of the inclined surface of the edge portion 11e and the second surface 11b is taken as the line L, the angle between the first surface 11a and the line L ( Inferior angle). By reducing the angle θ, the power supply distance can be shortened. According to this, it is possible to further improve the responsiveness (RF responsiveness) of control such as changes in the RF output.

In addition, although a curved cross-sectional shape is shown between the lower end P and the edge portion 11e in these figures, the area between the lower end P and the edge portion 11e is not limited to this, and a linear cross-sectional shape may be used. By being linear, for example, the power supply distance can be further shortened.

Fig. 10 is a schematic cross-sectional view illustrating an electrostatic chuck related to the embodiment. As shown in FIG. 10, the electrostatic chuck 100A includes a ceramic dielectric substrate 10, an electrode layer 110, and a bottom plate 50.

An electrode layer 110 is arranged inside the ceramic dielectric substrate 10. The electrode layer 110 is disposed between the first main surface 10a and the second main surface 10b. In other words, the electrode layer 110 is arranged to be inserted into the ceramic dielectric substrate 10. The electrode layer 110 may be built-in by being integrally sintered on the ceramic dielectric substrate 10, for example.

In this way, by arranging the electrode layer 110 inside the ceramic dielectric substrate 10, the upper electrode (upper electrode 510 in FIG. 13) and the electrode layer 110 (lower electrode) arranged above the electrostatic chuck 100A can be shortened. the distance between. According to this, for example, compared with the case where the bottom plate 50 is used as the lower electrode, the plasma density can be increased with low electric power. In other words, the power required to obtain a high plasma density can be reduced.

The shape of the electrode layer 110 is a thin film along the first main surface 10 a and the second main surface 10 b of the ceramic dielectric substrate 10. The cross-sectional shape of the electrode layer 110 will be described later.

The electrode layer 110 is connected to a high-frequency power source (high-frequency power source 504 in FIG. 13). By applying a voltage (high-frequency voltage) to the upper electrode (the upper electrode 510 in FIG. 13) and the electrode layer 110 from a high-frequency power source, plasma is generated inside the processing container 501. In other words, the electrode layer 110 is a lower electrode for generating plasma. The high-frequency power supply supplies high-frequency AC (alternating current) current to the electrode layer 110.

The electrode layer 110 includes cermet of metal and ceramic. By forming the electrode layer 110 with cermet, the adhesion between the electrode layer 110 and the ceramic dielectric substrate 10 can be improved. Moreover, the strength of the electrode layer 110 can be improved.

The metal contained in the cermet includes, for example, at least any one of Ag, Pd, and Pt. In addition, 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 electrode layer 110 with a ceramic cermet containing the same elements as the ceramic contained in the ceramic dielectric substrate 10, the difference between the thermal expansion coefficient of the electrode layer 110 and the thermal expansion coefficient of the ceramic dielectric substrate 10 can be reduced. Accordingly, the adhesion between the electrode layer 110 and the ceramic dielectric substrate 10 can be improved, and defects such as peeling can be suppressed. In addition, the ceramic contained in the cermet may also contain an element different from the ceramic contained in the ceramic dielectric substrate 10.

The electrode layer 110 is connected to, for example, a power supply for suction (suction power supply 505 in FIG. 13) in addition to a high-frequency power supply. The electrostatic chuck 100A applies a voltage (suction voltage) to the electrode layer 110 from the suction power supply to generate an electric charge on the first main surface 10a side of the electrode layer 110, and attracts and holds the object W by electrostatic force. In other words, the electrode layer 110 may be an adsorption electrode for adsorbing the object W. According to the embodiment, in this way, the electrode layer of the lower electrode for plasma generation for generating plasma can be used as an adsorption electrode for adsorbing an object. The power supply for adsorption supplies direct current (DC) or AC current to the electrode layer 110.

The electrode layer 110 is provided with a connection portion 20 extending on the second main surface 10 b side of the ceramic dielectric substrate 10.

Fig. 11 is a cross-sectional view schematically showing an enlarged part of an electrostatic chuck according to the embodiment. Figs. 12(a) and 12(b) are cross-sectional views schematically showing modified examples of the electrode layer of the electrostatic chuck according to the embodiment. FIG. 11 is an enlarged display of the region R2 shown in FIG. 10.

As shown in FIG. 11, the electrode layer 110 has a first surface 110a and a second surface 110b. The first surface 110a is a surface on the side of the first main surface 10a. The second surface 110b is a surface opposite to the first surface 110a. The first surface 110a, in other words, is a surface facing the first main surface 10a. The second surface 110b is, in other words, a surface facing the second main surface 10b.

The distance D11 along the Z-axis direction between the first surface 110a and the first main surface 10a is constant. The distance D11, in other words, is the distance from the first main surface 10a to the top surface (first surface 110a) of the electrode layer 110. Here, "constant" means that, for example, the undulation of the first surface 110a can be included. For example, when observing the cross section of the electrostatic chuck 100A with a scanning electron microscope (SEM) or the like at a low magnification (for example, about 100 times), the distance D11 may be approximately constant. For example, the difference between the distance D11c in the center portion 110c of the electrode layer 110 and the distance D11d in the end portion 110d of the electrode layer 110 is 0±150 μm. The distance D11 (distance D11c and distance D11d) is, for example, about 300 μm. The first surface 110a is, for example, a surface parallel to the first main surface 10a.

As shown in FIG. 11, an end portion 110d of the electrode layer 110 is a region including an edge 110e on the X-Y plane of the electrode layer 110. The edge 110e of the electrode layer 110 refers to the interface between the electrode layer 110 and the ceramic dielectric substrate 10 when viewed from the Z-axis direction on the first surface 110a. The central portion 110c of the electrode layer 110 is a region located between the two end portions 110d on the X-Y plane. The definition of the central portion 110c and the end portion 110d of the electrode layer 110 is the same as the definition of the central portion 11c and the end portion 11d of the first electrode layer 11.

In this way, by making the distance D11 between the first surface 110a and the first main surface 10a constant along the Z-axis direction, the upper electrode (the upper electrode 510 in FIG. 13) and the electrode layer 110 (lower electrode) The distance between is constant. According to this, for example, compared with the case where the distance D11 along the Z-axis direction between the first surface 110a and the first main surface 10a is not constant, the in-plane uniformity of the plasma density can be improved. For example, the cross-sectional shape of the electrode layer 110 is convex upward, and the distance between the first surface 110a in the end portion 110d and the first main surface 10a along the Z-axis direction is different from the first surface in the central portion 110c. Compared with the case of the distance along the Z-axis direction between the surface 110a and the first main surface 10a, the in-plane uniformity of the plasma density can be improved.

The cross-sectional shape of the electrode layer 110 is downward convex. More specifically, the distance D12d in the Z-axis direction between the second surface 110b and the first surface 110a in the end 110d of the electrode layer 110 is smaller than the second surface 110b and the first surface 110b in the central portion 110c of the electrode layer 110. The distance D12c between one surface 110a along the Z-axis direction. The distance D12c is, in other words, the thickness of the electrode layer 110 in the central portion 110c. In other words, the distance D12d is the thickness of the electrode layer 110 in the end 110d. That is, the thickness of the electrode layer 110 in the end portion 110d is smaller than the thickness of the electrode layer 110 in the central portion 110c. For example, the thickness of the electrode layer 110 decreases from the central portion 110c toward the end portion 110d. The electrode layer 110 has a shape convex to the second surface 110b side.

The distance D12c 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 D12c) of the electrode layer 110 in the central portion 110c within this range, the influence of the skin effect can be reduced, and the in-plane uniformity of the plasma density can be further improved. The distance D12c can be obtained, for example, by the average value of the thickness of three points in the central portion 110c on the cross-sectional SEM (Scanning Electron Microscope) image of the electrode layer 110. In the specification of this case, the average value is defined as the distance D12c.

The electrode layer 110 is supplied with a high-frequency current from the second surface 110b side. Generally, when AC current flows through the electrode layer, a skin effect is generated in which the current density is high on the surface of the electrode layer and becomes lower as soon as it moves away from the surface. Moreover, the higher the high frequency of the flowing AC current, the more significant the surface concentration of the current is. That is, the high-frequency AC current flowing into the electrode layer 110 from the second surface 110b side is conducted to the second surface 110b of the electrode layer 110 and flows into the first surface 110a.

In the embodiment, the distance D12d along the Z-axis direction between the second surface 110b and the first surface 110a in the end 110d of the electrode layer 110 is smaller than the second surface in the central portion 110c of the electrode layer 110. The distance D12c between the first surface 110b and the first surface 110a along the Z-axis direction can shorten the power supply distance from the second surface 110b to the first surface 110a. According to this, it is possible to further improve the responsiveness (RF responsiveness) of control such as changes in the RF output.

The present inventors discovered the following new problem. The electrode layer 110 connected to a high-frequency power supply is arranged inside the ceramic dielectric substrate 10, and the high-frequency applied to the electrode layer 110 is further increased in order to increase the plasma density. When the power supply is increased in power, especially the electrode layer 110 generates heat, the environment inside the reaction chamber (processing container 501 in FIG. 13) changes, and the in-plane uniformity of the plasma density is adversely affected. In contrast, according to the embodiment, the distance D12d between the second surface 110b and the first surface 110a in the end portion 110d of the electrode layer 110 along the Z-axis direction is smaller than the second surface in the central portion 110c of the electrode layer 110 The distance D12c between 110b and the first surface 110a along the Z-axis direction. For example, by making the electrode layer 110 convex toward the second surface 110b side (that is, the bottom plate 50 side), the surface area of the second surface 110b of the electrode layer 110 on the bottom plate 50 side that has a cooling function can be relatively enlarged. . Accordingly, the electrode layer 110 can dissipate heat more effectively, and the in-plane uniformity of the plasma density can be further improved.

In addition, in this example, the thickness of the electrode layer 110 is constant in the central portion 110c. In other words, in the central portion 110c, the second surface 110b is parallel to the first surface 110a. On the other hand, in the end portion 110d, the thickness of the electrode layer 110 decreases from the central portion 110c side toward the edge portion 110e. In other words, in the end portion 110d, the second surface 110b has an inclined surface inclined upward from the central portion 110c side toward the edge portion 110e. In this example, the inclined surface is flat. The inclined surface may be curved as shown in Fig. 12(a).

The cross-sectional shape of the electrode layer 110 is not limited to this. For example, as shown in FIG. 12(b), the second surface 110b may have an inclined surface inclined upward from the center on the X-Y plane of the second surface 110b toward the edge portion 110e. In other words, in the central portion 110c, the thickness of the electrode layer 110 is not necessarily required. In other words, in the central portion 110c, the second surface 110b may not be parallel to the first surface 110a. In this case, the inclined surface may be curved as shown in FIG. 12(b).

The configuration of the electrode layer 110 may be the same as the configuration of the first electrode layer 11 described above, for example. More specifically, for example, the first electrode shown in Fig. 4(a), Fig. 4(b), Fig. 5(a), Fig. 5(b), Fig. 6(a), and Fig. 6(b) The configuration of the layer 11 is suitable for the electrode layer 110.

Furthermore, the shape of the electrode layer 110 may be the same as the shape of the first electrode layer 11 described above, for example. More specifically, the shape of the first electrode layer 11 shown in FIGS. 9(a) to 9(d) may be applied to the electrode layer 110, for example.

Hereinafter, a method of manufacturing the ceramic dielectric substrate 10 in which the electrode layer 110 is disposed is described.

The ceramic dielectric substrate 10 in which the electrode layer 110 is arranged inside can be produced, for example, by laminating each layer with the first main surface 10a side facing down, and sintering the layered body. More specifically, for example, the electrode layer 110 is laminated on the first layer that is the ceramic layer including the first main surface 10a. On the electrode layer 110, a second layer including a ceramic layer of the second main surface 10b is laminated. Then, the layered body is sintered.

The electrode layer 110 is formed by, for example, screen printing, paste coating (spin coating, coater, inkjet, dispenser, etc.), vapor deposition, and the like. For example, in a state where the first main surface 10a faces downward, the electrode layer 110 can be formed by laminating each layer in plural times. At this time, for example, by adjusting the stacking range, the distance D12d between the first surface 110a and the second surface 110b in the end portion 110d and the distance between the first surface 110a and the second surface 110b in the center portion 110c can be made The relationship of the distance D12c satisfies D12d<D12c.

Fig. 13 is a cross-sectional view schematically showing a wafer processing apparatus equipped with an electrostatic chuck according to the embodiment. As shown in FIG. 13, the wafer processing apparatus 500A includes a processing container 501, a high-frequency power supply 504, a suction power supply 505, an upper electrode 510, and an electrostatic chuck 100A. The electrostatic chuck 100A is arranged under the upper electrode 510 in the inside of the processing container 501. The electrode layer 110 and the upper electrode 510 of the electrostatic chuck 100A are connected to a high-frequency power supply 504. The electrode layer 110 of the electrostatic chuck 100A is connected to a power supply 505 for suction.

The electrode layer 110 and the upper electrode 510 are arranged substantially in parallel with each other at a predetermined interval. More specifically, the first surface 110 a of the electrode layer 110 is slightly parallel to the bottom surface 510 a of the upper electrode 510. Furthermore, the first main surface 10a of the ceramic dielectric substrate 10 is slightly parallel to the bottom surface 510a of the upper electrode 510. The object W is placed on the first main surface 10 a between the electrode layer 110 and the upper electrode 510.

When a voltage (high-frequency voltage) is applied to the electrode layer 110 and the upper electrode 510 from the high-frequency power supply 504, a high-frequency discharge occurs, and the processing gas introduced into the processing container 501 is activated by plasma excitation, so that The processing target W is processed.

When a voltage (suction voltage) is applied to the electrode layer 110 from the suction power supply 505, an electric charge is generated on the first main surface 10a side of the electrode layer 110, and the object W is attracted and held on the electrostatic chuck 100A by electrostatic force.

As described above, according to the embodiment, an electrostatic chuck can be provided, which can improve the in-plane uniformity of the plasma density and at the same time improve the RF responsiveness.

The embodiments of the present invention have been described above. However, the present invention is not limited to these descriptions. Regarding the aforementioned embodiments, those skilled in the art may appropriately add design changes as long as they have the characteristics of the present invention and are included in the scope of the present invention. For example, the shape, size, material, arrangement, installation form, etc. of each element included in the electrostatic chuck are not limited to those illustrated and can be appropriately changed. In addition, the various elements provided in the aforementioned embodiments can be combined as technically as possible, and a combination of these elements is included in the scope of the present invention as long as they also include the features of the present invention.

10: Ceramic dielectric substrate 10a: The first major surface 10b: Second major surface 11, 11A, 11B: the first electrode layer 11a, 110a: first side 11b, 110b: second side 11c, 110c: central part 11d, 110d: end 11e, 110e: margin 11p: hole 12: The second electrode layer 12a: Third side 12b: Fourth side 13: Convex 14: Groove 15: Through hole 20: Connection part 50: bottom plate 50a: upper part 50b: lower part 51: input channel 52: output channel 53: Gas inlet 55: Connect Channel 60: Next component 100, 100A: Electrostatic chuck 110: Electrode layer 500, 500A: Wafer processing equipment 501: processing container 502: Process gas inlet 503: exhaust port 504: high frequency power supply 505: Power supply for adsorption 510: Upper electrode 510a: bottom surface D1, D1c, D1d, D2c, D2d, D11, D11c, D11d, D12c, D12d, D3, D4, D5: distance P: bottom R1, R2: area t: width W: Object

Fig. 1 is a cross-sectional view schematically showing an electrostatic chuck related to the embodiment. Fig. 2 is a cross-sectional view schematically showing an enlarged part of an electrostatic chuck according to the embodiment. 3(a) and 3(b) are cross-sectional views schematically showing modified examples of the first electrode layer of the electrostatic chuck according to the embodiment. 4(a) and 4(b) are plan views schematically showing a part of the electrostatic chuck related to the embodiment. 5(a) and 5(b) are plan views schematically showing a part of the electrostatic chuck related to the embodiment. 6(a) and 6(b) are plan views schematically showing a part of the electrostatic chuck related to the embodiment. 7(a) and 7(b) are plan views schematically showing a part of the electrostatic chuck related to the embodiment. Fig. 8 is a cross-sectional view schematically showing a wafer processing apparatus equipped with an electrostatic chuck according to the embodiment. 9(a) to 9(d) are cross-sectional views schematically showing the end of the first electrode layer related to the embodiment in an enlarged manner. Fig. 10 is a cross-sectional view schematically showing an electrostatic chuck related to the embodiment. Fig. 11 is a cross-sectional view schematically showing an enlarged part of an electrostatic chuck according to the embodiment. Figs. 12(a) and 12(b) are cross-sectional views schematically showing modified examples of the electrode layer of the electrostatic chuck according to the embodiment. Fig. 13 is a cross-sectional view schematically showing a wafer processing apparatus equipped with an electrostatic chuck according to the embodiment.

10: Ceramic dielectric substrate

10a: The first major surface

10b: Second major surface

11: The first electrode layer

11a: First side

11b: Second side

11c: Central part

11d: end

11e: margin

12: The second electrode layer

12a: Third side

12b: Fourth side

20: Connection part

50: bottom plate

60: Next component

D1, D1c, D1d, D2c, D2d, D3, D4, D5: distance

W: Object

Claims (15)

An electrostatic chuck, characterized in that it contains: The ceramic dielectric substrate has: a first main surface on which the object to be adsorbed is placed, and a second main surface opposite to the first main surface; The bottom plate supports the ceramic dielectric substrate; At least one first electrode layer is arranged inside the ceramic dielectric substrate and connected to a high-frequency power supply; and At least one second electrode layer is arranged inside the ceramic dielectric substrate and connected to the power supply for adsorption, The first electrode layer is arranged between the first main surface and the second main surface in the Z-axis direction from the bottom plate to the ceramic dielectric substrate, The second electrode layer is arranged between the first electrode layer and the first main surface in the Z-axis direction, The first electrode layer has a first surface on the first main surface side and a second surface on the opposite side of the first surface, and power is supplied from the second surface side, The first electrode layer has: a first end that is located on the outer peripheral side of the ceramic dielectric substrate when projected on a plane perpendicular to the Z-axis direction; and a second end that is projected on a plane perpendicular to the Z-axis direction When the plane is located on the ceramic dielectric substrate further than the first end, The distance between the first surface and the first main surface along the Z-axis direction is constant, The distance along the Z-axis direction between the second surface in the first end portion of the first electrode layer and the first surface is smaller than the distance between the second surface and the first surface in the central portion of the first electrode layer. The distance between the first surfaces along the Z axis, The distance along the Z-axis direction between the second surface in the second end portion of the first electrode layer and the first surface is smaller than the distance between the second surface and the first surface in the central portion of the first electrode layer. The distance between the first surfaces along the Z-axis direction. For example, the electrostatic chuck of claim 1, wherein the first electrode layer has: a first part located on the outer peripheral side of the ceramic dielectric substrate when projected on a plane perpendicular to the Z-axis direction; and a second part projected on When the plane perpendicular to the Z-axis direction is located on the ceramic dielectric substrate further than the first part, The first part has the first end and the second end, The second part has a third end located on the ceramic dielectric substrate further inside than the second end when projected on a plane perpendicular to the Z-axis direction, The distance along the Z-axis direction between the second surface in the third end portion of the first electrode layer and the first surface is smaller than the distance between the second surface and the first surface in the central portion of the first electrode layer. The distance between the first surfaces along the Z-axis direction. Such as the electrostatic chuck of claim 1 or claim 2, wherein the total area of the first surface of the first electrode layer is greater than the total area of the surface on the first main surface side of the second electrode layer. Such as the electrostatic chuck of claim 1 or claim 2, wherein in the Z-axis direction, a part of the first electrode layer does not overlap with the second electrode layer. Such as the electrostatic chuck of claim 1 or claim 2, wherein the thickness of the first electrode layer is greater than the thickness of the second electrode layer. Such as the electrostatic chuck of claim 1 or claim 2, wherein the distance along the Z-axis direction between the second surface in the central portion of the first electrode layer and the first surface is 1 μm or more and 500 μm or less. The electrostatic chuck of claim 6, wherein the distance along the Z-axis direction between the second surface in the central portion of the first electrode layer and the first surface is 10 μm or more and 100 μm or less. For example, the electrostatic chuck of claim 1 or claim 2, wherein the first electrode layer includes at least any one of Ag, Pd, and Pt. For example, the electrostatic chuck of claim 1 or claim 2, wherein the first electrode layer is composed of metal and ceramic cermet. The electrostatic chuck of claim 9, wherein the ceramic contains the same elements as the ceramic contained in the ceramic dielectric substrate. The electrostatic chuck of claim 9, wherein the ceramic contains an element different from the ceramic contained in the ceramic dielectric substrate. For example, the electrostatic chuck of claim 1 or claim 2, wherein the first electrode layer includes metal and ceramic, The second electrode layer includes metal and ceramic, The ratio of the volume of the metal to the total volume of the metal contained in the first electrode layer and the volume of the ceramic is greater than the total volume of the metal contained in the second electrode layer and the volume of the ceramic The ratio of the volume of the metal. For example, the electrostatic chuck of claim 1 or claim 2, wherein the first electrode layer includes metal and ceramic, The second electrode layer includes metal and ceramic, The volume of the metal contained in the first electrode layer is greater than the volume of the metal contained in the second electrode layer. Such as the electrostatic chuck of claim 1 or claim 2, wherein the ceramic dielectric substrate contains alumina, The concentration of the alumina in the ceramic dielectric substrate is 90% by mass or more. For example, the electrostatic chuck of claim 1 or claim 2, wherein the width of at least one of the first end portion and the second end portion is larger than the second surface and the first surface in the central portion of the first electrode layer The distance along the Z-axis direction between.

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