KR20200013611A - 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 {ELECTROSTATIC CHUCK}

Aspects of the present invention generally relate to electrostatic chucks.

An electrostatic chuck is used as a means for adsorbing and holding a processing object such as a semiconductor wafer or a glass substrate in a plasma processing chamber in which etching, chemical vapor deposition (CVD), sputtering, ion implantation, and ashing are performed. The electrostatic chuck applies electrostatic adsorption power to an electrode to be built in and absorbs a substrate such as a silicon wafer by electrostatic power.

When performing the plasma treatment, for example, a voltage is applied from an RF (Radio Frequency) power source (high frequency power source) to an upper electrode formed above the chamber and a lower electrode formed below the upper electrode to generate a plasma.

In the conventional electrostatic chuck, plasma is generated using a base plate formed under the electrostatic chuck as a lower electrode. However, there is a limit to plasma control in such a configuration in the situation where additional control of the in-plane distribution of the plasma density is required by selecting an appropriate frequency.

Thus, in recent years, attempts have been made to increase plasma controllability by embedding a lower electrode for plasma generation in a dielectric layer formed on a base plate. However, there is a problem that the in-plane uniformity of plasma density may not be sufficiently obtained only by embedding the lower electrode in the dielectric layer.

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

Japanese Patent Publication No. 2008-277847 Japanese Patent Publication No. 2011-119654 Japanese Patent Publication No. 2004-103648 Japanese Patent Application Laid-Open No. 2016-201411

The first invention provides a ceramic dielectric substrate having a first main surface on which an object to be adsorbed is loaded, a second main surface opposite to the first main surface, a base plate supporting the ceramic dielectric substrate, and an interior of the ceramic dielectric substrate. At least one first electrode layer formed on the substrate and connected to a high frequency power source, and at least one second electrode layer formed inside the ceramic dielectric substrate and connected to a suction power source, wherein the first electrode layer is formed on the base. In the Z-axis direction from the plate toward the ceramic dielectric substrate, between the first main surface and the second main surface, the second electrode layer is 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 and a second surface on the side opposite to the first surface, and is in an electrostatic chuck fed from the second surface side. The distance along the Z axis direction between the first surface and the first main surface is constant, and the distance along the Z axis direction between the second surface and the first surface at the end of the first electrode layer is The electrostatic chuck 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.

According to this electrostatic chuck, a first electrode layer connected to a high frequency power supply is formed inside the ceramic dielectric substrate, for example, between the upper electrode and the first electrode layer (lower electrode) for plasma generation formed above the electrostatic chuck. Can shorten the distance. As a result, for example, the plasma density can be increased at a lower power than when the base plate is used as a lower electrode for plasma generation. Moreover, according to this electrostatic chuck, the in-plane uniformity of plasma density can be improved by making the distance along the Z-axis direction between a 1st surface and a 1st main surface constant.

In general, when an alternating current flows through the electrode, a phenomenon called a skin effect occurs in which the current density is high at the electrode surface and lowers from the surface. It is known that the higher the frequency of the alternating current, the greater the concentration of the current on the surface. In the present invention, since the first electrode layer is connected to the high frequency power source, the skin effect occurs in the first electrode layer, and the alternating current applied from the high frequency power source is thought to flow along the surface of the first electrode layer. According to the electrostatic chuck, in the first electrode layer connected with the high frequency power supply from the second surface side and fed with power, the distance along the Z-axis direction between the second surface and the first surface at the end of the first electrode layer is determined by the first electrode layer. It is made smaller than the distance along the Z-axis direction between the 2nd surface and the 1st surface in the center part of an electrode layer. Therefore, the feeding distance from the second surface to the first surface can be shortened. Thereby, the response (RF response) to control, such as a change of RF output, can be improved.

In addition, conventionally, a second electrode layer is formed inside the dielectric substrate to be connected to a power supply for adsorption. In addition, when the first electrode layer connected to the high frequency power source is formed inside the ceramic dielectric substrate and the power applied to the first electrode layer is increased in order to increase the plasma density, the heat generation of the first electrode layer is particularly important. This results in a new problem that the environment in the chamber is changed and adversely affects the in-plane uniformity of the plasma density. According to this electrostatic chuck, the distance along the Z-axis direction between the second surface and the first surface at the end of the first electrode layer is defined by the Z-axis between the second surface and the first surface in the central portion of the first electrode layer. By making it smaller than the distance along a direction, the surface area of the 2nd surface of the 1st electrode layer located in the side of a base plate which has a cooling function can be made relatively large. As a result, the first electrode layer can be more effectively radiated, and the in-plane uniformity of the plasma density can be further improved.

The second invention is the electrostatic chuck of the first invention, wherein the sum of the areas of the first surface of the first electrode layer is larger than the sum of the areas of the surface of the first main surface side of the second electrode layer.

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

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

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

The fourth invention is the electrostatic chuck of any one of the first to third aspects, wherein the thickness of the first electrode layer is larger than that of the second electrode layer.

According to this electrostatic chuck, by making the thickness of the first electrode layer larger than the thickness of the second electrode layer, the influence of the skin effect can be reduced, and the in-plane uniformity of the plasma density can be further increased. When the first electrode layer connected to the high frequency power source is simply thickened, it has been found that RF response may deteriorate. In the present invention, the thickness of the first electrode layer is increased, while the distance along the Z-axis direction between the second surface and the first surface at the end of the first electrode layer is determined by the second surface and the first surface in the central portion of the first electrode layer. It is made smaller than the distance along the Z-axis direction between 1 surface. Therefore, the fall of RF responsiveness can be suppressed, reducing the influence of a skin effect.

According to a fifth aspect of the invention, the distance along the Z-axis direction between the second surface and the first surface in the central portion of the first electrode layer is 1 µm or more and 500 µm or less. An electrostatic chuck characterized in that.

According to this electrostatic chuck, the effect of the skin effect is achieved by setting the distance along the Z-axis direction (thickness of the first electrode layer in the center portion) between the second surface and the first surface in the center portion of the first electrode layer in this range. It is possible to reduce and further increase the in-plane uniformity of the plasma density and to suppress a decrease in RF responsiveness.

The sixth invention is the electrostatic chuck of the fifth invention, wherein a distance along the Z-axis direction between the second surface and the first surface in the central portion of the first electrode layer is 10 µm or more and 100 µm or less. .

According to this electrostatic chuck, the effect of the skin effect is achieved by setting the distance along the Z-axis direction (thickness of the first electrode layer in the center portion) between the second surface and the first surface in the center portion of the first electrode layer in this range. It is possible to reduce and further increase in-plane uniformity of the plasma density, and to suppress a decrease in RF responsiveness.

According to a seventh aspect of the present invention, the first electrode layer is an electrostatic chuck comprising at least one of Ag, Pd, and Pt.

Thus, according to the electrostatic chuck according 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 the electrostatic chuck of any one of the first to seventh aspects, wherein the first electrode layer is made of a cermet of metal and ceramics.

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

The ninth invention is the electrostatic chuck according to the eighth invention, wherein the ceramics contain elements such as ceramics contained in the ceramic dielectric substrate.

According to this electrostatic chuck, the difference between the thermal expansion rate of the first electrode layer and the thermal expansion rate of the ceramic dielectric substrate can be reduced by forming the first electrode layer with a cermet of ceramics containing elements such as ceramics contained in the ceramic dielectric substrate. Thereby, the adhesiveness of a 1st electrode layer and a ceramic dielectric substrate can be improved, and problems, such as peeling, can be suppressed.

The tenth invention is the electrostatic chuck of the eighth invention, wherein the ceramics contain an element different from the ceramics included in the ceramic dielectric substrate.

Thus, according to the electrostatic chuck according to the embodiment, thermal characteristics, mechanical characteristics, electrical characteristics, and the like can be arbitrarily designed by forming the first electrode layer with a cermet of ceramics containing elements different from the ceramics included in the ceramic dielectric substrate. .

According to an eleventh invention of any one of the first to tenth aspects, the first electrode layer includes metal and ceramics, and the second electrode layer includes metal and ceramics, and the metal included in the first electrode layer. Wherein the ratio of the volume of the metal to the sum of the volume of the ceramics and the volume of the ceramics is greater than the ratio of the volume of the metal to the sum of the volume of the metal and the volume of the ceramics included in the second electrode layer. It is an electrostatic chuck.

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

In a twelfth invention, the invention of any one of the first to the tenth, wherein the first electrode layer comprises a metal and ceramics, the second electrode layer comprises a metal and ceramics, the metal contained in the first electrode layer The volume of the electrostatic chuck is larger than the volume of the metal contained in the second electrode layer.

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

According to the thirteenth invention, the ceramic dielectric substrate comprises aluminum oxide, and the concentration of the aluminum oxide in the ceramic dielectric substrate is 90% by mass or more. Chuck.

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

In a fourteenth aspect of the present invention, the distance along the Z-axis direction between the first electrode layer and the second electrode layer is in the Z-axis direction between the first main surface and the second electrode layer. An electrostatic chuck characterized in that it is greater than the distance along.

According to this electrostatic chuck, the distance along the Z axis between the first electrode layer and the second electrode layer is greater than the distance along the Z axis between the first main surface and the second electrode layer so that even when a voltage is applied from the high frequency power source, The occurrence of problems such as short circuits or breakdowns between the two electrode layers can be more effectively suppressed.

In a fifteenth aspect of the invention, the width of the end portion is a distance along the Z-axis direction between the second surface and the first surface in the central portion of the first electrode layer. An electrostatic chuck characterized by being larger.

According to this electrostatic chuck, the distance along the Z-axis direction between the second surface and the first surface in the center portion of the first electrode layer (ie, the thickness in the center portion of the first electrode layer) is defined by the width of the end portion of the first electrode layer. By making it larger, the feeding distance can be shortened. Thereby, the response (RF response) to control, such as a change of RF output, can be improved more.

A sixteenth invention provides a ceramic dielectric substrate having a first main surface on which an object to be adsorbed is loaded, a second main surface opposite to the first main surface, a base plate for supporting the ceramic dielectric substrate, and an interior of the ceramic dielectric substrate. And at least one electrode layer connected to the high frequency power source, wherein the electrode layer is formed between the first main surface and the second main surface in the Z-axis direction from the base plate toward the ceramic dielectric substrate, The electrode layer has a first surface on the first main surface side and a second surface on the opposite side to the first surface, and in the electrostatic chuck fed from the second surface side, the electrode layer includes a cermet of metal and ceramics. The distance along the Z-axis direction between the first surface and the first main surface is constant, and between the second surface and the first surface at the end of the electrode layer. The distance along the Z-axis direction is smaller than the distance along the Z-axis direction between the second surface and the first surface in the central portion of the electrode layer.

According to this electrostatic chuck, by forming the electrode layer connected to the high frequency power supply inside the ceramic dielectric substrate, the distance between the upper electrode for plasma generation and the electrode layer (lower electrode) formed above the electrostatic chuck can be shortened. As a result, for example, the plasma density can be increased with low power as compared with the case where the base plate is used as a lower electrode for plasma generation. Moreover, according to this electrostatic chuck, the in-plane uniformity of plasma density can be improved by making the distance along the Z-axis direction between a 1st surface and a 1st main surface constant.

In general, when an alternating current flows through the electrode, a phenomenon called a skin effect occurs in which the current density is high at the electrode surface and lowers from the surface. It is known that the higher the frequency of the alternating current, the greater the concentration of the current on the surface. In this invention, since an electrode layer is connected with a high frequency power supply, it is thought that a skin effect arises in an electrode layer, and the alternating current applied from the high frequency power supply flows along the surface of an electrode layer. According to this electrostatic chuck, in the electrode layer connected to the high frequency power supply from the second surface side and fed with power, the distance along the Z-axis direction between the second surface and the first surface at the end of the electrode layer is determined at the center portion of the electrode layer. It is made smaller than the distance along the Z-axis direction between a 2nd surface and a 1st surface. Therefore, the feeding distance from the second surface to the first surface can be shortened. Thereby, the response (RF response) to control, such as a change of RF output, can be improved.

In addition, when the electrode layer connected to the high frequency power source is formed inside the ceramic dielectric substrate and the power applied to the electrode layer is increased in order to increase the plasma density, the environment in the chamber is changed due to the heat generation of the electrode layer. We found a new problem that adversely affects the in-plane uniformity of density. According to this electrostatic chuck, the distance along the Z axis direction between the second surface and the first surface at the end of the electrode layer is the distance along the Z axis direction between the second surface and the first surface at the center of the electrode layer. By making it smaller, the surface area of the 2nd surface of the electrode layer located in the base plate side which has a cooling function can be made relatively large. As a result, the electrode layer can be radiated more effectively, and the in-plane uniformity of the plasma density can be further improved. According to this electrostatic chuck, by forming the electrode layer in a cermet, the adhesion between the electrode layer and the ceramic dielectric substrate can be enhanced and the strength of the electrode layer can be increased.

According to a sixteenth invention, in the sixteenth invention, the distance along the Z-axis direction between the second surface and the first surface in the central portion of the electrode layer is 1 µm or more and 500 µm or less.

According to this electrostatic chuck, the influence of the skin effect is reduced by reducing the distance along the Z-axis direction (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 to this range. In addition, the in-plane uniformity of the density can be further increased, and the degradation of the RF responsiveness can be suppressed.

The eighteenth invention is the electrostatic chuck of the seventeenth invention, wherein a distance along the Z-axis direction between the second surface and the first surface in the central portion of the electrode layer is 10 µm or more and 100 µm or less.

According to this electrostatic chuck, the influence of the skin effect is reduced by reducing the distance along the Z-axis direction (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 to this range. The in-plane uniformity of the density can be further increased, and the degradation of the RF responsiveness can be suppressed.

19th invention is an electrostatic chuck in any one of 16th-18th invention, The said electrode layer contains at least any one of Ag, Pd, and Pt.

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

In the twentieth aspect of the present invention, in any of the sixteenth to nineteenth aspects of the present invention, the ceramic is an electrostatic chuck comprising an element such as ceramic contained in the ceramic dielectric substrate.

According to this electrostatic chuck, the difference between the thermal expansion rate of the electrode layer and the thermal expansion rate of the ceramic dielectric substrate can be reduced by forming the electrode layer with a cermet of ceramics containing elements such as ceramics contained in the ceramic dielectric substrate. Thereby, adhesiveness of an electrode layer and a ceramic dielectric substrate can be improved and problems, such as peeling, can be suppressed.

In a twenty-first aspect of the present invention, the ceramic is an electrostatic chuck comprising an element different from ceramics contained in the ceramic dielectric substrate.

Thus, according to the electrostatic chuck according to the embodiment, thermal characteristics, mechanical characteristics, electrical characteristics, and the like can be arbitrarily designed by forming the electrode layer with a cermet of ceramics containing an element different from the ceramics included in the ceramic dielectric substrate.

In the twenty-second aspect of the present invention, the ceramic dielectric substrate comprises aluminum oxide, and the concentration of aluminum oxide in the ceramic dielectric substrate is 90% by mass or more. Chuck.

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

In a twenty-third aspect of the present invention, there is provided an electrostatic chuck, wherein the electrode layer is connected to a power supply for adsorption.

Thus, according to the electrostatic chuck which concerns on embodiment, the electrode layer which is a lower electrode for generating a plasma can be used also as an adsorption electrode for adsorb | sucking a target object.

24th invention is invention of any one of 16th-23rd, The width | variety of the said edge part is larger than the distance along the Z-axis direction between the said 2nd surface and the said 1st surface in the said center part of the said electrode layer. An electrostatic chuck characterized in that.

According to this electrostatic chuck, the feeding distance is increased by making the width of the end portion of the electrode layer larger than the distance along the Z-axis direction (ie, thickness in the center portion of the electrode layer) between the second surface and the first surface in the center portion of the electrode layer. You can shorten it. Thereby, the response (RF response) to control, such as a change of RF output, can be improved more.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows typically the electrostatic chuck which concerns on embodiment.
It is sectional drawing which expands and shows typically a part of electrostatic chuck which concerns on embodiment.
3 (a) and 3 (b) are cross-sectional views schematically showing modifications 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 according to the embodiment.
5 (a) and 5 (b) are plan views schematically showing a part of the electrostatic chuck according to the embodiment.
6 (a) and 6 (b) are plan views schematically showing a part of the electrostatic chuck according to the embodiment.
7 (a) and 7 (b) are plan views schematically showing a part of the electrostatic chuck according to the embodiment.
It is sectional drawing which shows typically the wafer processing apparatus provided with the electrostatic chuck which concerns on embodiment.
9 (a) to 9 (d) are cross-sectional views schematically showing an enlarged end of the first electrode layer according to the embodiment.
It is sectional drawing which shows typically an electrostatic chuck which concerns on embodiment.
It is sectional drawing which expands and shows typically a part of electrostatic chuck which concerns on embodiment.
12 (a) and 12 (b) are cross-sectional views schematically showing modifications of the electrode layer of the electrostatic chuck according to the embodiment.
It is sectional drawing which shows typically the wafer processing apparatus provided with the electrostatic chuck which concerns on embodiment.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described, referring drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same component, and detailed description is abbreviate | omitted suitably.

1 is a schematic cross-sectional view illustrating an electrostatic chuck according to the embodiment.

As shown in FIG. 1, the electrostatic chuck 100 includes a ceramic dielectric substrate 10, a first electrode layer 11, a second electrode layer 12, and a base plate 50.

The ceramic dielectric substrate 10 is, for example, a flat substrate made of sintered ceramic. For example, the ceramic dielectric substrate 10 includes aluminum oxide (alumina: Al ₂ O ₃ ). For example, the ceramic dielectric substrate 10 is formed of high purity aluminum oxide. The concentration of aluminum oxide in the ceramic dielectric substrate 10 is, for example, 90 mass% or more and 100 mass% or less, preferably 95 mass% or more and 100 mass% or less, more preferably 99 It is the mass% or more and 100 mass% or less. By using high purity aluminum oxide, the plasma resistance of the ceramic dielectric substrate 10 can be improved. The concentration of aluminum oxide can be measured by fluorescence X-ray 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 object W for adsorption is loaded. The second main surface 10b is a surface opposite to the first main surface 10a. The object W for adsorption is a semiconductor substrate, such as a silicon wafer, for example.

In addition, in this specification, the direction toward the ceramic dielectric substrate 10 from the base plate 50 is made into the Z-axis direction. The Z-axis direction is a direction which connects the 1st main surface 10a and the 2nd main surface 10b as illustrated in each figure, for example. The Z-axis direction is, for example, a direction substantially perpendicular to the first main surface 10a and the second main surface 10b. One of the directions orthogonal to the Z-axis direction is assumed to be the X-axis direction, the Z-axis direction and the direction orthogonal to the X-axis direction as the Y-axis direction. In this specification, "in-plane" is in X-Y plane, for example.

The first electrode layer 11 and the second electrode layer 12 are formed in the ceramic dielectric substrate 10. The first electrode layer 11 and the second electrode layer 12 are formed between the first main surface 10a and the second main surface 10b. That is, the first electrode layer 11 and the second electrode layer 12 are formed to be inserted into the ceramic dielectric substrate 10. The first electrode layer 11 and the second electrode layer 12 may be embedded by, for example, integrally sintering the ceramic dielectric substrate 10.

The first electrode layer 11 is positioned between the first main surface 10a and the second main surface 10b in the Z-axis direction. The second electrode layer 12 is positioned 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, the first electrode layer 11 is formed inside the ceramic dielectric substrate 10, whereby the upper electrode (the upper electrode 510 of FIG. 8) and the first electrode layer 11 formed above the electrostatic chuck 100. The distance between (lower electrodes) can be shortened. As a result, for example, the plasma density can be increased with low power as compared with the case where the base plate 50 is used as the lower electrode. In other words, the power required to obtain a high plasma density can be reduced.

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

The first electrode layer 11 is connected to a high frequency power source (high frequency power source 504 of FIG. 8). When a voltage (high frequency voltage) is applied to the upper electrode (the upper electrode 510 of 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 (AC) current to the first electrode layer 11. "High frequency" here is 200 kHz or more, for example.

The first electrode layer 11 is made of metal, for example. The first electrode layer 11 includes at least one of Ag, Pd, and Pt, for example. The first electrode layer 11 may contain, for example, metal and ceramics. The first electrode layer 11 may be made of, for example, a cermet of metal and ceramics. Cermets are composites containing metals and ceramics (oxides, carbides, etc.). By forming the first electrode layer 11 in a cermet, the adhesion between the first electrode layer 11 and the ceramic dielectric substrate 10 can be improved. In addition, the strength of the first electrode layer 11 can be increased.

The metal included in the cermet includes, for example, at least one of Ag, Pd, and Pt. In addition, the ceramics included in the cermet include an element such as ceramics included in the ceramic dielectric substrate 10, for example. The first electrode layer 11 is formed of a cermet of ceramics containing elements such as ceramics included in the ceramic dielectric substrate 10 so that the thermal expansion rate of the first electrode layer 11 and the thermal expansion coefficient of the ceramic dielectric substrate 10 The car can be made small. Thereby, the adhesiveness of the 1st electrode layer 11 and the ceramic dielectric substrate 10 can be improved, and problems, such as peeling, can be suppressed. In addition, the ceramics contained in the cermet may contain an element different from the ceramics contained in the ceramic dielectric substrate 10.

The second electrode layer 12 is connected to a suction power source (the suction power source 505 in FIG. 8). The electrostatic chuck 100 generates a charge on the first main surface 10a side of the second electrode layer 12 by applying a voltage (adsorption voltage) to the second electrode layer 12 from the power supply for adsorption, and thus, The object W is adsorbed and held. In other words, the second electrode layer 12 is an adsorption electrode for adsorbing the object (W). The adsorption power supply supplies direct current (DC) current or AC current to the second electrode layer 12. The adsorption power supply is, for example, a DC power supply. The adsorption power supply 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 one of Ag, Pd, Pt, Mo, and W, for example. The second electrode layer 12 may contain metal and ceramics, for example.

When the first electrode layer 11 includes metals and ceramics, and the second electrode layer 12 includes metals and ceramics, the metal is the sum of the volume of the metals included in the first electrode layer 11 and the volume of the ceramics. The ratio of the volume of the metal is preferably greater than the ratio of the volume of the metal to the sum of the volume of the metal contained in the second electrode layer 12 and the volume of the ceramics.

As such, the ratio of the metal included in the first electrode layer 11 is greater than the ratio of the metal included in the second electrode layer 12. For example, the electrical resistance of the first electrode layer 11 to which a voltage is applied from a high frequency power source. Can be made smaller, and the in-plane uniformity and the RF responsiveness of the plasma density can be improved.

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

When the first electrode layer 11 includes metal and ceramics and the second electrode layer 12 includes metal and ceramics, the volume of metal included in the first electrode layer 11 is included in the second electrode layer 12. It is also preferable that the volume is larger than the volume of the metal.

In this way, the volume of the metal included in the first electrode layer 11 is larger than the volume of the metal included in the second electrode layer 12, for example, the electrical resistance of the first electrode layer 11 to which voltage is applied from a high frequency power source. Can be made smaller, and the in-plane uniformity and the RF responsiveness of the plasma density can be improved.

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

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

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

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

In this example, the grooves 14 are formed on the first main surface 10a 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. When the part in which the groove | channel 14 is not formed is made into the convex part 13, the object W is mounted in the convex part 13. As shown in FIG. The first main surface 10a is a surface in contact with the rear surface of the object W. As shown in FIG. That is, the first main surface 10a is a plane including the upper surface of the convex portion 13. A space is formed between the groove 14 and the rear surface of the object W loaded on the electrostatic chuck 100.

The ceramic dielectric substrate 10 has a through hole 15 connected to the groove 14. The through-hole 15 is formed from the 2nd main surface 10b to the 1st main surface 10a. That is, the through hole 15 extends in the Z-axis direction from the second main surface 10b to the first main surface 10a and penetrates the ceramic dielectric substrate 10.

The height of the convex portion 13 (depth of the groove 14), the area ratio of the convex portion 13 and the groove 14, the shape, and the like are appropriately selected so that they are attached to the temperature of the object W or the object W. You can control the particles to be in the desired state.

The gas introduction passage 53 is formed in the base plate 50. The gas introduction passage 53 is formed to penetrate the base plate 50, for example. The gas introduction passage 53 may be formed from the middle of the other gas introduction passage 53 to the ceramic dielectric substrate 10 side without passing through the base plate 50. In addition, the gas introduction passage 53 may be formed in a plurality of places of the base plate 50.

The gas introduction passage 53 communicates with the through hole 15. That is, the delivery gas (helium, etc.) which flowed in into the gas introduction path 53 flows into the through-hole 15 after passing through the gas introduction path 53.

The delivery gas flowing into the through hole 15 passes through the through hole 15 and then flows into the space formed between the object W and the groove 14. As a result, the object W can be directly cooled by the delivery gas.

It is sectional drawing which expands and shows typically a part of electrostatic chuck which concerns on embodiment.

3 (a) and 3 (b) are cross-sectional views schematically showing modifications of the first electrode layer of the electrostatic chuck according to the embodiment.

FIG. 2 enlarges and shows the area | region R1 shown in FIG.

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

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

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

Thus, the upper electrode (the upper electrode 510 of FIG. 8) and the first electrode layer 11 (by making the distance D1 along the Z-axis direction between the first surface 11a and the first main surface 10a constant. The distance between the lower electrodes can be made constant. Thereby, for example, the in-plane uniformity of the plasma density can be improved as compared with the case where the distance D1 along the Z-axis direction between the first surface 11a and the first main surface 10a is not constant. have. For example, when the cross-sectional shape of the first electrode layer 11 is convex upward, the distance along the Z-axis direction between the first surface 11a and the first main surface 10a at the end portion 11d is the central portion ( In-plane uniformity of the plasma density can be improved as compared with the distance along the Z-axis direction between the first surface 11a and the first main surface 10a in 11c).

The cross-sectional shape of the first electrode layer 11 is convex downward. More specifically, the distance D2d along the Z-axis direction between the second surface 11b and the first surface 11a at the end 11d of the first electrode layer 11 is determined by the first electrode layer 11. It is smaller than the distance D2c along the Z-axis direction between the 2nd surface 11b and the 1st surface 11a in the center part 11c. In other words, the distance D2c is the thickness of the first electrode layer 11 in the center portion 11c. In other words, the distance D2d is the thickness of the first electrode layer 11 at the end portion 11d. That is, the thickness of the first electrode layer 11 at the end portion 11d is smaller than the thickness of the first electrode layer 11 at the center portion 11c. For example, the thickness of the first electrode layer 11 decreases from the central portion 11c toward the end portion 11d. The first electrode layer 11 is convex toward 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, 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 center portion 11c in this range, the influence of the skin effect can be reduced, and the in-plane uniformity of the plasma density can be further increased. Distance D2c can be calculated | required as an average value of the thickness of three points in the center part 11c in the cross-sectional SEM (Scanning Electron Microscope) image of the 1st electrode layer 11, for example. In this specification, this average value is defined as distance D2c.

The high frequency current is supplied to the first electrode layer 11 from the second surface 11b side. In general, when AC current flows through the electrode layer, a skin effect occurs in which the current density is high at the surface of the electrode layer and lowers from the surface. As the flowing AC current is high frequency, the surface concentration of the current becomes more remarkable. That is, high frequency AC current flowing from the second surface 11b side to the first electrode layer 11 flows into the first surface 11a along the second surface 11b of the first electrode layer 11. .

In the embodiment, the distance D2d along the Z-axis direction between the second surface 11b and the first surface 11a at the end 11d of the first electrode layer 11 is determined by the first electrode layer 11. The first surface 11a from the second surface 11b fed by being smaller than the distance D2c along the Z-axis direction between the second surface 11b and the first surface 11a at the center portion 11c of the first surface 11a. The feeding distance to can be shortened. Thereby, the response (RF response) to control, such as a change of RF output, can be improved more.

The inventors of the present invention form the first electrode layer 11 connected to the high frequency power supply in the ceramic dielectric substrate 10 and further increase the high frequency power applied to the first electrode layer 11 to increase the plasma density. In particular, a new problem has been found that the first electrode layer 11 generates heat, the environment inside the chamber (the processing container 501 of FIG. 8) changes, and adversely affects the in-plane uniformity of the plasma density. On the other hand, according to embodiment, the distance D2d along the Z-axis direction between the 2nd surface 11b and the 1st surface 11a in the edge part 11d of the 1st electrode layer 11 is 1st. It is made smaller than the distance D2c along the Z-axis direction between the 2nd surface 11b and the 1st surface 11a in the center part 11c of the electrode layer 11. For example, by making the first electrode layer 11 convex toward the second surface 11b side (that is, the base plate 50 side), the base plate 50 side having the cooling function of the first electrode layer 11 is provided. The surface area of the second surface 11b, which is the surface of, can be made relatively large. Thereby, the 1st electrode layer 11 can be dissipated more effectively, and the in-plane uniformity of plasma density can be improved more.

In this example, the thickness of the first electrode layer 11 is constant at the center portion 11c. In other words, in the center part 11c, the 2nd surface 11b is parallel with respect to the 1st surface 11a. On the other hand, at the end portion 11d, the thickness of the first electrode layer 11 decreases from the center portion 11c side toward the edge portion 11e. In other words, in the end portion 11d, the second surface 11b has an inclined surface that is inclined upward from the central portion 11c side toward the edge portion 11e. In this example, the inclined plane is planar. The inclined surface may be curved, as shown in Fig. 3A.

The cross-sectional shape of the first electrode layer 11 is not limited to this. For example, as shown in FIG.3 (b), even if the 2nd surface 11b has the inclined surface which inclines upward toward the edge part 11e from the center in the XY plane of the 2nd surface 11b. good. In other words, in the center portion 11c, the thickness of the first electrode layer 11 may not be constant. In other words, in the center part 11c, the 2nd surface 11b does not need to be parallel with respect to the 1st surface 11a. At this time, the inclined surface may be curved, as shown in Fig. 3B.

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 side opposite to the third surface 12a. In other words, the fourth surface 12b is a surface facing the first electrode layer 11. In other words, the fourth surface 12b is a surface opposite to the first surface 11a of the first electrode layer 11.

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

It is also preferable that the 4th surface 12b is a surface parallel to the 3rd surface 12a. It is also preferable that the 4th surface 12b is a surface parallel to 1st main surface 10a. More specifically, the distance D4 along the Z-axis direction between the fourth surface 12b and the third surface 12a is also 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 obtained, for example, as an average value of three thicknesses in the cross-sectional SEM image of the second electrode layer 12.

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

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, the distance along the Z-axis direction between the first main 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). Greater than (D3).

In this way, by making the distance D5 larger than the distance D3, even if a voltage is applied from the high frequency power supply, problems such as short circuits or breakdown between the first electrode layer 11 and the second electrode layer 12 can be more effectively prevented. It can be suppressed.

4 (a), 4 (b), 5 (a), 5 (b), 6 (a) and 6 (b) are plan views schematically showing a part of the electrostatic chuck according to the embodiment. to be.

These figures show a portion of the electrostatic chuck 100 that is located on the base plate 50 side (lower side) of the ceramic dielectric substrate 10 than the first electrode layer 11 (the second surface 11b), and the base. It is the top view which looked at the 1st electrode layer 11 from the side (lower side) of the 2nd surface 11b in the state which abbreviated the plate 50 and the like.

As shown in FIG. 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, At least one first electrode layer 11 is formed along the XY plane. The number of the first electrode layers 11 may be one, for example, as shown in Figs. 4A and 4B, and two as shown in Figs. 5A and 5B. It may be sufficient, and may be three or more (four in this example), as shown to FIG. 6 (a) and FIG. 6 (b). When the plurality of first electrode layers 11 are formed, each of the first electrode layers 11 may be located on the same plane, for example, or may be located on another plane in the Z-axis direction.

In the example shown in FIGS. 4A and 4B, the circular shape of the first electrode layer 11 when viewed along the Z-axis direction is, for example, the center of the first electrode layer 11 and the ceramic dielectric substrate 10. ) Centers are arranged to overlap. The edge portion 11e of the first electrode layer 11 is, for example, concentric with the edge portion of the ceramic dielectric substrate 10. In this example, the end portion 11d of the first electrode layer 11 is annularly arranged on the outer circumferential side of the ceramic dielectric substrate 10.

In the example shown in Figs. 5A and 5B, for example, the inner first electrode layer 11A and the outer first electrode layer 11B are formed concentrically. The inner first electrode layer 11A is circular when viewed along the Z-axis direction, for example. The outer first electrode layer 11B is, for example, an annular shape that surrounds 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 disposed concentrically, for example, where the center of the inner first electrode layer 11A and the center of the ceramic dielectric substrate 10 overlap each other. . In this example, the end portion 11d of the outer first electrode layer 11B is annularly disposed on the center side of the ceramic dielectric substrate 10 and the outer circumferential side of the ceramic dielectric substrate 10, respectively. The end portion 11d of the inner first electrode layer 11A is annularly arranged on the outer circumferential side of the ceramic dielectric substrate. 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. 6A and 6B, the plurality of first electrode layers 11 that are circular when viewed along the Z-axis direction are respectively point-symmetrical with respect to the center of the ceramic dielectric substrate 10, for example. It is arrange | positioned at the position which becomes. One of the first electrode layers 11 may be arranged so that the center of the first electrode layer 11 and the center of the ceramic dielectric substrate 10 overlap each other. In other words, one of the first electrode layers 11 may be disposed in the center of the ceramic dielectric substrate 10. In this example, the end portion 11d of each first electrode layer 11 is arranged in an annular shape on the outer circumferential side of each first electrode layer 11.

4 (b), 5 (b), and 6 (b), the first electrode layer 11 has a hole 11p penetrating the first electrode layer 11 in the Z-axis direction. It may be formed. When the hole 11p is formed, the edge part 11d is arrange | positioned also in the vicinity of the outer periphery of the hole 11p.

In embodiment, the distance D2d between the 1st surface 11a and the 2nd surface 11b in the edge part 11d and the center part 11c in any part of these edge parts 11d. The relationship between the distance D2c between the first surface 11a and the second surface 11b may satisfy D2d <D2c. In addition, in the range which exhibits the effect of this invention, it does not exclude including the location which does not satisfy D2d <D2c. In other words, in embodiment, D2d <D2c should just be satisfied in at least one part of 11 d of said ends. For example, when there are many places which satisfy | fill D2d <D2c in the edge part 11d, RF responsiveness can be improved further.

As described above, the central portion 11c of the first electrode layer 11 is a region located between the two end portions 11d in 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 according to the embodiment.

These figures omit portions of the ceramic dielectric substrate 10 located on the first main surface 10a side (upper side) of the ceramic dielectric substrate 10 than the second electrode layer 12 (third surface 12a). In the state, it is a top view which looked at the 2nd electrode layer 12 from the 3rd surface 12a side (upper side).

As shown in Figs. 7A and 7B, the second electrode layer 12 may be monopolar or bipolar. When the second electrode layer 12 is monopolar, as shown in Fig. 7A, one second electrode layer 12 widening along the X-Y plane is formed. The second electrode layer 12 is substantially circular when viewed along the Z-axis direction, for example. On the other hand, when the second electrode layer 12 is bipolar, as shown in FIG. 7 (b), two second electrode layers 12 are formed along the X-Y plane and positioned on the same plane. Each of the second electrode layers 12 is substantially semi-circular when viewed along the Z-axis direction, for example. The second electrode layer 12 may have a pattern that widens along the X-Y plane, for example.

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

Hereinafter, the manufacturing method of the ceramic dielectric substrate 10 in which the 1st electrode layer 11 and the 2nd electrode layer 12 were formed inside is demonstrated.

In the ceramic dielectric substrate 10 having the first electrode layer 11 and the second electrode layer 12 formed therein, for example, each layer is laminated with the first main surface 10a side down, and the laminate is It can manufacture by sintering. More specifically, for example, the second electrode layer 12 is laminated on the first layer serving as the ceramic layer including the first main surface 10a. A second layer serving as 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 stacked on the second layer. A third layer serving as a ceramic layer including the second main surface 10b is stacked on the first electrode layer 11. And this laminated body is sintered.

The first electrode layer 11 is formed by, for example, screen printing, application of a paste (spin coat, coater, ink jet, dispenser, etc.), vapor deposition, or the like. For example, the first electrode layer 11 can be formed by stacking each layer in a plurality of times in a state where the first main surface 10a is down. At this time, for example, the distance D2d between the first surface 11a and the second surface 11b at the end 11d and the center portion 11c are adjusted by adjusting the stacking range or the like. The relationship between the distance D2c between the first surface 11a and the second surface 11b can satisfy D2d <D2c.

It is sectional drawing which shows typically the wafer processing apparatus provided with the electrostatic chuck which concerns on embodiment.

As shown in FIG. 8, the wafer processing apparatus 500 includes a processing container 501, a high frequency power supply 504, an adsorption power supply 505, an upper electrode 510, and an electrostatic chuck 100. Doing. The ceiling of the processing container 501 is provided with a processing gas inlet 502 for introducing a processing gas therein and an upper electrode 510. An exhaust port 503 is formed in the bottom plate of the processing container 501 for evacuating the inside under reduced pressure. The electrostatic chuck 100 is disposed below the upper electrode 510 in the processing container 501. The first electrode layer 11 and the upper electrode 510 of the electrostatic chuck 100 are connected to the high frequency power supply 504. The second electrode layer 12 of the electrostatic chuck 100 is connected to a suction power source 505.

The first electrode layer 11 and the upper electrode 510 are formed substantially parallel to each other at a predetermined interval. More specifically, the first surface 11a of the first electrode layer 11 is substantially parallel to the lower surface 510a of the upper electrode 510. In addition, the first main surface 10a of the ceramic dielectric substrate 10 is substantially parallel to the bottom surface 510a of the upper electrode 510. The object W is mounted on the first main surface 10a positioned between the first electrode layer 11 and the upper electrode 510.

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

When a voltage (adsorption voltage) is applied from the absorption power supply 505 to the second electrode layer 12, electric charges are generated on the first main surface 10a side of the second electrode layer 12, and the target ( W) is held by the electrostatic chuck 100 by suction.

9 (a) to 9 (d) are cross-sectional views schematically showing an enlarged end of the first electrode layer according to the embodiment.

As shown in Figs. 9A to 9D, the width t, which is the length in the X-axis direction of the end portion 11d of the first electrode layer 11 when viewed in cross section, is, for example, the first. It is larger than the thickness D2c in the center part 11c of the electrode layer 11 (thickness D2c <width t). The width t of the end portion 11d is, in other words, the width of the inclined surface of the second surface 11b. In other words, 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, the feeding distance can be shortened by making the width t of the end portion 11d larger than the thickness D2c in the center portion 11c of the first electrode layer 11. Thereby, the response (RF response) to control, such as a change of RF output, can be improved more.

The lower end P of the inclined surface can be obtained from the cross-sectional image of the sample cut to include the first electrode layer 11. In the embodiment, for example, at least one of the samples satisfies the above relationship (thickness D2c <width t). In embodiment, it is more preferable that several places among a sample satisfy said 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, preferably 20 degrees or more and 60 degrees or less. The angle θ is the first surface 11a when the straight line connecting the edge 11e and the lower end P (where the slope ends) of the inclined surface of the second surface 11b is a line L. It may be represented by the angle (heat angle) formed by the line (L). By reducing the angle θ, the feeding distance can be shortened. Thereby, the response (RF response) to control, such as a change of RF output, can be improved more.

In addition, in these figures, although the lower end P and the edge part 11e show the curved cross-sectional shape, between the lower end P and the edge part 11e is not limited to this, A linear cross-sectional shape may be sufficient. By making it linear, for example, the feeding distance can be made shorter.

10 is a schematic cross-sectional view illustrating the electrostatic chuck according to the embodiment.

As shown in FIG. 10, the electrostatic chuck 100A includes a ceramic dielectric substrate 10, an electrode layer 110, and a base plate 50.

An electrode layer 110 is formed in the ceramic dielectric substrate 10. The electrode layer 110 is formed between the first main surface 10a and the second main surface 10b. That is, the electrode layer 110 is formed to be inserted into the ceramic dielectric substrate 10. The electrode layer 110 may be embedded by, for example, integrally sintering the ceramic dielectric substrate 10.

Thus, by forming 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) formed above the electrostatic chuck 100A. The distance between them can be shortened. As a result, for example, the plasma density can be increased with low power as compared with the case where the base plate 50 is used as the lower electrode. In other words, the power required to obtain a high plasma density can be reduced.

The shape of the electrode layer 110 is a thin film along the first and second main surfaces 10a and 10b 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 of FIG. 13). When a voltage (high frequency voltage) is applied to the upper electrode (the upper electrode 510 of 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 (AC) current to the electrode layer 110.

The electrode layer 110 includes a cermet of metal and ceramics. By forming the electrode layer 110 in a cermet, adhesion between the electrode layer 110 and the ceramic dielectric substrate 10 may be improved. In addition, the strength of the electrode layer 110 may be increased.

The metal included in the cermet includes, for example, at least one of Ag, Pd, and Pt. In addition, the ceramics included in the cermet include an element such as ceramics included in the ceramic dielectric substrate 10, for example. The electrode layer 110 is formed of a cermet of ceramics containing an element such as ceramics included in the ceramic dielectric substrate 10 to reduce the difference between the thermal expansion rate of the electrode layer 110 and the thermal expansion rate of the ceramic dielectric substrate 10. Can be. Thereby, the adhesiveness of the electrode layer 110 and the ceramic dielectric substrate 10 can be improved, and problems, such as peeling, can be suppressed. In addition, the ceramics contained in the cermet may contain an element different from the ceramics contained in the ceramic dielectric substrate 10.

For example, the electrode layer 110 is also connected to a suction power source (suction power source 505 in FIG. 13) in addition to a high frequency power source. The electrostatic chuck 100A generates a charge on the first main surface 10a side of the electrode layer 110 by applying a voltage (adsorption voltage) to the electrode layer 110 from the power supply for adsorption, and thus the object W is driven by electrostatic power. Keep adsorption. In other words, the electrode layer 110 may be an adsorption electrode for adsorbing the object (W). According to the embodiment, the electrode layer which is the lower electrode for plasma generation for generating a plasma in this way can also be used as an adsorption electrode for adsorbing an object. Adsorption power supplies DC (DC) current or AC current to the electrode layer (110).

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

It is sectional drawing which expands and shows typically a part of electrostatic chuck which concerns on embodiment.

12 (a) and 12 (b) are cross-sectional views schematically showing modifications of the electrode layer of the electrostatic chuck according to the embodiment.

FIG. 11 shows an enlarged view 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 first main surface 10a side. The second surface 110b is a surface opposite to the first surface 110a. In other words, the first surface 110a is a surface facing the first main surface 10a. In other words, the second surface 110b is 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. In other words, the distance D11 is a distance from the first main surface 10a to the upper surface (first surface 110a) of the electrode layer 110. Here, the term "schedule" may include, for example, a wave of the first surface 110a and the like. For example, when the cross section of the electrostatic chuck 100A is observed at a low magnification (for example, about 100 times) with a scanning electron microscope (SEM) or the like, the distance D11 may be substantially 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. Distance D11 (distance D11c and distance D11d) is about 300 micrometers, for example. The first surface 110a is, for example, a surface parallel to the first main surface 10a.

As shown in FIG. 11, the end portion 110d of the electrode layer 110 is an area including an edge 110e in the X-Y plane of the electrode layer 110. The edge portion 110e of the electrode layer 110 is located on the first surface 110a and refers to the interface between the electrode layer 110 and the ceramic dielectric substrate 10 when viewed from the Z-axis direction. The central portion 110c of the electrode layer 110 is a region located between the two ends 110d in 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, the distance D11 along the Z-axis direction between the first surface 110a and the first main surface 10a is constant so that the upper electrode (the upper electrode 510 of FIG. 13) and the electrode layer 110 (the lower electrode) are fixed. You can make the distance between) constant. Thereby, for example, the in-plane uniformity of the plasma density can be improved as 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. have. For example, when the cross-sectional shape of the electrode layer 110 is convex upward, the distance along the Z-axis direction between the first surface 110a and the first main surface 10a at the end 110d is the central portion 110c. In-plane uniformity of the plasma density can be improved as compared with the case in which the distance along the Z-axis direction between the first surface 110a and the first main surface 10a is different.

The cross-sectional shape of the electrode layer 110 is convex downward. More specifically, the distance D12d along the Z-axis direction between the second surface 110b and the first surface 110a at the end 10 of the electrode layer 110 is the central portion 110c of the electrode layer 110. It is smaller than the distance D12c along the Z-axis direction between the 2nd surface 110b and the 1st surface 110a in. In other words, the distance D12c is 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 at the end 110d. That is, the thickness of the electrode layer 110 in the end part 110d is smaller than the thickness of the electrode layer 110 in the center part 110c. For example, the thickness of the electrode layer 110 decreases as it goes from the central portion 110c to the end portion 110d. The electrode layer 110 is convex toward the second surface 110b.

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, more preferably 20 µm or more and 70 µm or less. By setting the thickness (distance D12c) of the electrode layer 110 in the center portion 110c to this range, the influence of the skin effect can be reduced, and the in-plane uniformity of the plasma density can be further increased. Distance D12c can be calculated | required as an average value of the thickness of three points in the center part 110c in the cross-sectional SEM (Scanning Electron Microscope) image of the electrode layer 110, for example. In this specification, this average value is defined as distance D12c.

The high frequency current is supplied to the electrode layer 110 from the second surface 110b side. In general, when AC current flows through the electrode layer, a skin effect occurs in which the current density is high at the surface of the electrode layer and lowers from the surface. As the flowing AC current is high frequency, the surface concentration of the current becomes more remarkable. That is, high-frequency AC current flowing from the second surface 110b side to the electrode layer 110 flows into the first surface 110a along the second surface 110b of the electrode layer 110.

In the embodiment, the distance D12d along the Z-axis direction between the second surface 110b and the first surface 110a at the end 110d of the electrode layer 110 is the central portion 11c of the electrode layer 110. Feeding distance from the second surface 110b to the first surface 110a which is fed by being smaller than the distance D12c along the Z-axis direction between the second surface 110b and the first surface 110a in the Can be shortened. Thereby, the response (RF response) to control, such as a change of RF output, can be improved more.

The inventors of the present invention form the electrode layer 110 to be connected to the high frequency power supply in the ceramic dielectric substrate 10, and in order to increase the high frequency power applied to the electrode layer 110 in order to increase the plasma density, in particular, the electrode layer. A new problem has been found that the heat generated by 110 causes the environment in the chamber (the processing container 501 of FIG. 13) to change and adversely affect the in-plane uniformity of the plasma density. On the other hand, according to embodiment, the distance D12d along the Z-axis direction between the 2nd surface 110b and the 1st surface 110a in the edge part 110d of the electrode layer 110 of the electrode layer 110 It is made smaller than the distance D12c along the Z-axis direction between the 2nd surface 110b and the 1st surface 110a in the center part 110c. For example, the second layer that is the surface on the side of the base plate 50 having the cooling function of the electrode layer 110 is formed by making the electrode layer 110 convex to the second surface 110b side (that is, the base plate 50 side). The surface area of the face 110b can be made relatively large. Thereby, the electrode layer 110 can be radiated more effectively, and the in-plane uniformity of plasma density can be improved more.

In this example, the thickness of the electrode layer 110 is constant at the center portion 110c. In other words, in the center part 110c, the 2nd surface 110b is parallel with respect to the 1st surface 110a. On the other hand, in the end part 110d, the thickness of the electrode layer 110 becomes small toward the edge part 110e from the center part 110c side. In other words, in the end part 110d, the 2nd surface 110b has the inclined surface which inclines upward toward the edge part 110e from the center part 110c side. In this example, the inclined plane is planar. The inclined surface may be curved, as shown in Fig. 12A.

The cross-sectional shape of the electrode layer 110 is not limited to this. For example, as shown in FIG.12 (b), even if the 2nd surface 110b has the inclined surface which inclines upward toward the edge part 110e from the center in the XY plane of the 2nd surface 110b. good. In other words, in the central portion 110c, the thickness of the electrode layer 110 may not be constant. In other words, in the center part 110c, the 2nd surface 110b does not need to be parallel with respect to the 1st surface 110a. At this time, the inclined surface may be curved, as shown in Fig. 12B.

The arrangement of the electrode layer 110 may be the same as the arrangement of the first electrode layer 11, for example. More specifically, for example, the first electrode layer shown in FIGS. 4 (a), 4 (b), 5 (a), 5 (b), 6 (a), and 6 (b) may be used. The arrangement of 11 can also be applied to the electrode layer 110.

In addition, the shape of the electrode layer 110 may be the same as the shape of the first electrode layer 11, for example. More specifically, for example, the shape of the first electrode layer 11 shown in FIGS. 9A to 9D can also be applied to the electrode layer 110.

Hereinafter, the manufacturing method of the ceramic dielectric substrate 10 in which the electrode layer 110 was formed inside is demonstrated.

The ceramic dielectric substrate 10 having the electrode layer 110 formed therein can be produced by, for example, laminating each layer with the first main surface 10a side down and sintering the laminate. More specifically, for example, the electrode layer 110 is laminated on the first layer, which becomes a ceramic layer including the first main surface 10a. A second layer serving as a ceramic layer including the second main surface 10b is stacked on the electrode layer 110. And this laminated body is sintered.

The electrode layer 110 is formed by, for example, screen printing, application of a paste (spin coat, coater, ink jet, dispenser, etc.), vapor deposition, or the like. For example, in the state where the first main surface 10a is faced down, the electrode layer 110 may be formed by dividing each layer in a plurality of times. At this time, for example, the distance D12d between the first surface 110a and the second surface 110b at the end 110d and the center portion 110c are adjusted by adjusting the stacking range. The relationship between the distance D12c between the first surface 110a and the second surface 110b may satisfy D12d <D12c.

It is sectional drawing which shows typically the wafer processing apparatus provided with the electrostatic chuck which concerns on embodiment.

As shown in FIG. 13, the wafer processing apparatus 500A includes a processing container 501, a high frequency power supply 504, an adsorption power supply 505, an upper electrode 510, and an electrostatic chuck 100A. Doing. The electrostatic chuck 100A is disposed below the upper electrode 510 in the processing container 501. The electrode layer 110 and the upper electrode 510 of the electrostatic chuck 100A are connected to the high frequency power supply 504. The electrode layer 110 of the electrostatic chuck 100A is connected to the suction power source 505.

The electrode layer 110 and the upper electrode 510 are formed substantially parallel to each other at a predetermined interval. More specifically, the first surface 110a of the electrode layer 110 is substantially parallel to the lower surface 510a of the upper electrode 510. In addition, the first main surface 10a of the ceramic dielectric substrate 10 is substantially parallel to the bottom surface 510a of the upper electrode 510. The object W is mounted on the first main surface 10a positioned between the electrode layer 110 and the upper electrode 510.

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

When a voltage (adsorption voltage) is applied to the electrode layer 110 from the adsorption power supply 505, electric charges are generated on the first main surface 10a side of the electrode layer 110, and the object W is electrostatically discharged by electrostatic power. The suction is held by the chuck 100A.

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

In the above, embodiment of this invention was described. However, the present invention is not limited to these techniques. Regarding the embodiments described above, design changes made by those skilled in the art as appropriate are included in the scope of the present invention as long as the features of the present invention are provided. For example, the shape, dimension, material, arrangement, installation form, and the like of each element included in the electrostatic chuck are not limited to those illustrated, but can be changed as appropriate. In addition, each element with which each embodiment mentioned above can be combined as far as technically possible, and combining these elements is also included in the scope of the present invention as long as it contains the characteristics of this invention.

Claims (24)

A ceramic dielectric substrate having a first main surface on which an object to be adsorbed is mounted, and a second main surface opposite to the first main surface;
A base plate supporting the ceramic dielectric substrate;
At least one first electrode layer formed inside the ceramic dielectric substrate and connected to a high frequency power source;
At least one second electrode layer formed inside the ceramic dielectric substrate and connected to a power supply for adsorption;
The first electrode layer is formed between the first main surface and the second main surface in the Z-axis direction from the base plate toward the ceramic dielectric substrate.
The second electrode layer is formed between the first electrode layer and the first main surface in the Z-axis direction.
In the electrostatic chuck having the first surface on the first main surface side and the second surface on the side opposite to the first surface, the first electrode layer is fed from the second surface side,
The distance along the Z-axis direction between the first surface and the first main surface is constant,
The distance along the Z axis direction between the second surface and the first surface at the end of the first electrode layer is the Z axis between the second surface and the first surface in the central portion of the first electrode layer. An electrostatic chuck characterized by being less than a distance along the direction. The method of claim 1,
The sum of the areas of the first surface of the first electrode layer is larger than the sum of the areas of the surface of the first main surface side of the second electrode layer. The method of claim 1,
In the Z-axis direction, a part of the first electrode layer does not overlap with the second electrode layer, characterized in that the electrostatic chuck. The method according to any one of claims 1 to 3,
The thickness of the first electrode layer is greater than the thickness of the second electrode layer, the electrostatic chuck. The method according to any one of claims 1 to 3,
The distance along the Z-axis direction between the second surface and the first surface in the central portion of the first electrode layer is 1 µm or more and 500 µm or less. The method of claim 5, wherein
An electrostatic chuck, wherein the distance along the Z-axis direction between the second surface and the first surface in the central portion of the first electrode layer is 10 µm or more and 100 µm or less. The method according to any one of claims 1 to 3,
The first electrode layer comprises at least one of Ag, Pd, and Pt. The method according to any one of claims 1 to 3,
The first electrode layer is an electrostatic chuck, characterized in that consisting of a cermet of metal and ceramics. The method of claim 8,
Wherein said ceramics comprise an element such as ceramics contained in said ceramic dielectric substrate. The method of claim 8,
And said ceramics comprises an element different from ceramics contained in said ceramic dielectric substrate. The method according to any one of claims 1 to 3,
The first electrode layer includes a metal and ceramics,
The second electrode layer includes a metal and ceramics,
The ratio of the volume of the metal to the sum of the volume of the metal and the volume of the ceramics included in the first electrode layer is based on the sum of the volume of the metal and the volume of the ceramics included in the second electrode layer. An electrostatic chuck characterized in that it is larger than the proportion of the volume. The method according to any one of claims 1 to 3,
The first electrode layer includes a metal and ceramics,
The second electrode layer includes a metal and ceramics,
The volume of the metal included in the first electrode layer is larger than the volume of the metal included in the second electrode layer. The method according to any one of claims 1 to 3,
The ceramic dielectric substrate comprises aluminum oxide,
An electrostatic chuck in which the concentration of said aluminum oxide in said ceramic dielectric substrate is 90 mass% or more. The method according to any one of claims 1 to 3,
The distance along the Z axis direction between the first electrode layer and the second electrode layer is greater than the distance along the Z axis direction between the first main surface and the second electrode layer. The method according to any one of claims 1 to 3,
The width of the end portion is larger 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. A ceramic dielectric substrate having a first main surface on which an object to be adsorbed is mounted, and a second main surface opposite to the first main surface;
A base plate supporting the ceramic dielectric substrate;
At least one electrode layer formed inside the ceramic dielectric substrate and connected to a high frequency power source,
The electrode layer is formed between the first main surface and the second main surface in the Z-axis direction from the base plate toward the ceramic dielectric substrate.
In the electrostatic chuck having the first surface on the first main surface side and the second surface on the side opposite to the first surface, the electrode layer is fed from the second surface side,
The electrode layer comprises a cermet of metal and ceramics,
The distance along the Z-axis direction between the first surface and the first main surface is constant,
The distance along the Z axis direction between the second surface and the first surface at the end of the electrode layer is the distance along the Z axis direction between the second surface and the first surface in the central portion of the electrode layer. Electrostatic chuck characterized in that smaller. The method of claim 16,
The distance along the Z-axis direction between the second surface and the first surface in the central portion of the electrode layer is 1 µm or more and 500 µm or less. The method of claim 17,
The distance along the Z-axis direction between the second surface and the first surface in the central portion of the electrode layer is 10 µm or more and 100 µm or less. The method according to any one of claims 16 to 18,
The electrode layer comprises at least one of Ag, Pd, and Pt. The method according to any one of claims 16 to 18,
Wherein said ceramics comprise an element such as ceramics contained in said ceramic dielectric substrate. The method according to any one of claims 16 to 18,
And said ceramics comprises an element different from ceramics contained in said ceramic dielectric substrate. The method according to any one of claims 16 to 18,
The ceramic dielectric substrate comprises aluminum oxide,
An electrostatic chuck in which the concentration of said aluminum oxide in said ceramic dielectric substrate is 90 mass% or more. The method according to any one of claims 16 to 18,
And said electrode layer is connected to a suction power source. The method according to any one of claims 16 to 18,
The end portion has a width greater than the distance along the Z-axis direction between the second surface and the first surface in the central portion of the electrode layer.

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