Electrostatic chuck

Abstract

The present invention provides an electrostatic chuck that can improve the in-plane uniformity of plasma density while improving RF sensitivity. Specifically, it comprises: a ceramic dielectric substrate having a first main surface on which an adsorbed object is placed and a second main surface on the opposite side of the first main surface; a base plate that supports the ceramic dielectric substrate; and at least one first electrode layer that is arranged inside the ceramic dielectric substrate and connected to a high-frequency power supply, wherein the first electrode layer is arranged 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 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 the surface roughness of the second surface is greater than the surface roughness of the first surface.

Description

Technical Field

[0001] Aspects of the present invention generally relate to an electrostatic chuck. Background Art

[0002] In a plasma processing chamber for etching, chemical vapor deposition (CVD), sputtering, ion implantation, ashing, etc., an electrostatic chuck is used as a means of adsorbing and holding a processing object such as a semiconductor wafer or a glass substrate. The electrostatic chuck applies electrostatic adsorption power to a built-in electrode, and adsorbs a substrate such as a silicon wafer by electrostatic force.

[0003] When performing plasma processing, for example, a voltage is applied from an RF (Radio Frequency) power source to an upper electrode disposed at an upper portion of a combustion chamber and a lower electrode disposed below the upper electrode, thereby generating plasma.

[0004] In conventional electrostatic chucks, a base plate disposed at the bottom of the electrostatic chuck is used as a lower electrode to generate plasma. However, in situations where an appropriate frequency is selected and further control of the plasma density distribution within the wafer surface is required, plasma control based on such a structure has limitations.

[0005] Therefore, in recent years, the following method has been tried: a lower electrode for plasma generation is built into a dielectric layer provided on a base plate to improve plasma controllability. However, there is a problem that simply building the lower electrode into the dielectric layer may not sufficiently obtain in-plane uniformity of plasma density.

[0006] Furthermore, in recent years, in addition to improving the in-plane uniformity of plasma density, there has been a demand for further improvement in the sensitivity of control to changes in RF output and the like (RF sensitivity).

[0007] Patent Document 1: Japanese Patent Application Publication No. 2008-277847

[0008] Patent Document 2: Japanese Patent Application Publication No. 2011-119654

[0009] Patent Document 3: Japanese Patent Application Publication No. 2004-103648

[0010] Patent Document 4: Japanese Patent Application Publication No. 2016-201411 Summary of the invention

[0011] The inventors have discovered the following new problem: especially when an electrode layer connected to a high-frequency power supply is provided inside a ceramic dielectric substrate, and when the power applied to the electrode layer is increased in power in order to increase the plasma density, the environment inside the combustion chamber changes due to the heat generated by the electrode layer, which has an adverse effect on the in-plane uniformity of the plasma density.

[0012] The present invention is made based on the recognition of such problems, and the technical problem to be solved is to provide an electrostatic chuck that can improve the in-plane uniformity of plasma density while improving RF sensitivity.

[0013] The first invention is an electrostatic suction cup, comprising: a ceramic dielectric substrate having a first main surface on which an object to be adsorbed is placed and a second main surface on the opposite side of the first main surface; a base plate supporting the ceramic dielectric substrate; and at least one first electrode layer arranged inside the ceramic dielectric substrate and connected to a high-frequency power supply, characterized in that, in the Z-axis direction from the base plate toward the ceramic dielectric substrate, the first electrode layer is arranged between the first main surface and the second main surface, 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 the surface roughness of the second surface is greater than the surface roughness of the first surface.

[0014] According to the electrostatic chuck, by setting the first electrode layer connected to the high-frequency power supply inside the ceramic dielectric substrate, for example, the distance between the upper electrode for plasma generation set higher than the electrostatic chuck and the first electrode layer (lower electrode) can be shortened. Thus, for example, compared with the case where the base plate is used as the lower electrode for plasma generation, the plasma density can be increased by lower power. In addition, according to the electrostatic chuck, since the surface roughness of the second surface is made greater than the surface roughness of the first surface, the contact area between the surface of the first electrode layer on the base plate side with a cooling function, that is, the second surface, and the ceramic dielectric substrate can be increased. Thus, the heat dissipation of the first electrode layer (lower electrode) can be improved, and the in-plane uniformity of the plasma density can be improved while improving the RF sensitivity.

[0015] The second invention is an electrostatic suction cup, characterized in that, in the first invention, power is supplied to the first electrode layer 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 distance between the second surface and the first surface along the Z-axis direction at the end of the first electrode layer is smaller than the distance between the second surface and the first surface along the Z-axis direction at the center of the first electrode layer.

[0016] According to this electrostatic chuck, since the distance between the first surface and the first main surface in the Z-axis direction is constant, the in-plane uniformity of the plasma density can be improved.

[0017] Generally speaking, when an alternating current flows on an electrode, a phenomenon called skin effect occurs in which the current density is higher on the electrode surface and becomes lower as it is farther from the surface. It is well 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 a high-frequency power supply, it is believed that a skin effect occurs in the first electrode layer, and the alternating current applied from the high-frequency power supply is transferred to the surface of the first electrode layer and flows. According to the electrostatic chuck, in the first electrode layer that is connected to the high-frequency power supply from the second surface side and is powered, the distance between the second surface and the first surface at the end of the first electrode layer in the Z-axis direction is smaller than the distance between the second surface and the first surface at the center of the first electrode layer in the Z-axis direction. Therefore, the power supply distance from the second surface to the first surface can be shortened. As a result, the sensitivity (RF sensitivity) of control of changes in RF output, etc. can be further improved.

[0018] In addition, according to the electrostatic chuck, since the distance between the second surface and the first surface at the end of the first electrode layer along the Z-axis direction is made smaller than the distance between the second surface and the first surface at the center of the first electrode layer along the Z-axis direction, the surface area of ​​the second surface of the first electrode layer located on the base plate side having a cooling function can be relatively increased. As a result, the first electrode layer can dissipate heat more effectively, and the in-plane uniformity of the plasma density can be further improved.

[0019] A third invention is an electrostatic chuck according to the first or second invention, wherein the first electrode layer includes at least any one of Ag, Pd, and Pt.

[0020] As described above, according to the electrostatic chuck according to the embodiment, for example, the first electrode layer including a metal such as Ag, Pd, or Pt can be used.

[0021] A fourth invention is an electrostatic chuck according to any one of the first to third inventions, wherein the first electrode layer is formed of cermet of metal and ceramic.

[0022] According to this electrostatic chuck, since the first electrode layer is formed of 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 increased.

[0023] The fifth invention is an electrostatic chuck according to any one of the first to fourth inventions, wherein a distance between the second surface and the first surface in the central portion of the first electrode layer in the Z-axis direction is not less than 1 μm and not more than 500 μm.

[0024] According to the electrostatic suction cup, since the distance along the Z-axis direction between the second surface and the first surface at the central portion of the first electrode layer (the thickness of the first electrode layer at the central portion) is within this range, the influence of the skin effect is reduced, the in-plane uniformity of the plasma density is further improved, and the decrease in RF sensitivity can be suppressed.

[0025] A sixth invention is an electrostatic chuck according to the fifth invention, wherein a distance between the second surface and the first surface in a central portion of the first electrode layer in the Z-axis direction is not less than 10 μm and not more than 100 μm.

[0026] According to the electrostatic suction cup, since the distance along the Z-axis direction between the second surface and the first surface at the central portion of the first electrode layer (the thickness of the first electrode layer at the central portion) is within this range, the influence of the skin effect is reduced, and the in-plane uniformity of the plasma density is further improved, while the decrease in RF sensitivity can be suppressed.

[0027] A seventh invention is an electrostatic chuck according to any one of the first to sixth inventions, wherein the ceramic dielectric substrate contains aluminum oxide, and a concentration of the aluminum oxide in the ceramic dielectric substrate is 90 mass % or more.

[0028] According to this electrostatic chuck, since high-purity alumina is used, the plasma resistance of the ceramic dielectric substrate can be improved.

[0029] The eighth invention is an electrostatic suction cup characterized in that, in any one of the first to seventh inventions, it further comprises at least one second electrode layer, which is arranged inside the ceramic dielectric substrate and connected to a power supply for adsorption, and in the Z-axis direction, the second electrode layer is arranged between the first electrode layer and the first main surface.

[0030] As described above, according to the electrostatic chuck according to the embodiment, in addition to the first electrode layer which is the lower electrode for generating plasma, the second electrode layer which is the adsorption electrode for adsorbing an object can be provided.

[0031] A ninth invention is an electrostatic chuck according to the eighth invention, wherein a total area of ​​the first surface of the first electrode layer is larger than a total area of ​​a surface on the first main surface side of the second electrode layer.

[0032] According to this electrostatic chuck, since the total area of ​​the first surface of the first electrode layer is made larger than the total area of ​​the surface on the first main surface side of the second electrode layer, the in-plane uniformity of the plasma density can be further improved.

[0033] A tenth invention is an electrostatic chuck according to the eighth or ninth invention, wherein the thickness of the first electrode layer is larger than the thickness of the second electrode layer.

[0034] According to this electrostatic chuck, since the thickness of the first electrode layer is made larger than the thickness of the second electrode layer, the influence of the skin effect is reduced and the in-plane uniformity of the plasma density can be further improved.

[0035] An eleventh invention is an electrostatic chuck according to any one of the eighth to tenth inventions, wherein a portion of the first electrode layer does not overlap with the second electrode layer in the Z-axis direction.

[0036] According to this electrostatic chuck, since a part of the first electrode layer is not overlapped with the second electrode layer in the Z-axis direction, the in-plane uniformity of the plasma density can be further improved.

[0037] The 12th invention is an electrostatic suction cup, characterized in that, in any one of the 8th to 11th inventions, the first electrode layer contains metal and ceramics, the second electrode layer contains metal and ceramics, and the volume ratio of the metal to the total volume of the metal contained in the first electrode layer and the volume of the ceramics is greater than the volume ratio of the metal to the total volume of the metal contained in the second electrode layer and the volume of the ceramics.

[0038] According to this electrostatic chuck, since the proportion of metal contained in the first electrode layer is greater than the proportion of metal contained in the second electrode layer, for example, the resistance of the first electrode layer to which voltage is applied from a high-frequency power supply can be further reduced, and the in-plane uniformity and RF sensitivity of the plasma density can be improved.

[0039] The 13th invention is an electrostatic suction cup, characterized in that, in any one of the 8th to 11th inventions, the first electrode layer contains metal and ceramics, the second electrode layer contains metal and ceramics, 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.

[0040] According to the electrostatic chuck, since the volume of the metal contained in the first electrode layer is 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, and the in-plane uniformity and RF sensitivity of the plasma density can be improved.

[0041] The 14th invention is an electrostatic suction cup, characterized in that, in any one of the 8th to 13th inventions, the distance between the first electrode layer and the second electrode layer along the Z-axis direction is greater than the distance between the first main surface and the second electrode layer along the Z-axis direction.

[0042] According to the electrostatic suction cup, since the distance along the Z-axis between the first electrode layer and the second electrode layer is made greater than the distance along the Z-axis between the first main surface and the second electrode layer, even when a voltage is applied from a high-frequency power supply, it is possible to more effectively suppress adverse conditions such as short circuits and insulation breakdown between the first electrode layer and the second electrode layer.

[0043] A fifteenth invention is an electrostatic chuck according to any one of the first to seventh inventions, wherein the first electrode layer is connected to a power source for attraction.

[0044] As described above, according to the electrostatic chuck according to the embodiment, RF sensitivity is improved and the electrode layer, which is the lower electrode for generating plasma, can be used as an adsorption electrode for adsorbing an object.

[0045] A sixteenth invention is an electrostatic chuck according to the second invention, wherein the width of the end portion is larger than a distance between the second surface and the first surface in the center portion of the first electrode layer in the Z-axis direction.

[0046] According to this electrostatic chuck, since the width of the end of the first electrode layer is made larger than the distance between the second surface and the first surface in the center of the first electrode layer in the Z-axis direction (i.e., the thickness in the center of the first electrode layer), the power supply distance can be shortened. As a result, the sensitivity of control to changes in RF output, etc. (RF sensitivity) can be further improved.

[0047] According to an aspect of the present invention, there is provided an electrostatic chuck capable of improving the in-plane uniformity of plasma density. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a cross-sectional view schematically showing an electrostatic chuck according to an embodiment.

[0049] Figure 2 It is a cross-sectional view schematically showing a part of the electrostatic chuck according to the embodiment in an enlarged manner.

[0050] Figure 3 (a)~ Figure 3 (c) is a cross-sectional view schematically showing a modified example of the first electrode layer of the electrostatic chuck according to the embodiment.

[0051] Figure 4 (a) and Figure 4 (b) is a plan view schematically showing a portion of the electrostatic chuck according to the embodiment.

[0052] Figure 5 (a) and Figure 5(b) is a plan view schematically showing a portion of the electrostatic chuck according to the embodiment.

[0053] Figure 6 (a) and Figure 6 (b) is a plan view schematically showing a portion of the electrostatic chuck according to the embodiment.

[0054] Figure 7 It is a cross-sectional view schematically showing a wafer processing apparatus including an electrostatic chuck according to an embodiment.

[0055] Figure 8 It is a cross-sectional view schematically showing another electrostatic chuck according to the embodiment.

[0056] Fig. 9 It is a cross-sectional view schematically showing an enlarged view of a part of another electrostatic chuck according to the embodiment.

[0057] Fig.10 (a) and Fig.10 (b) is a plan view schematically showing a portion of another electrostatic chuck according to the embodiment.

[0058] Fig.11 It is a cross-sectional view schematically showing a wafer processing apparatus including another electrostatic chuck according to an embodiment.

[0059] Fig.12 (a)~ Fig.12 (d) is a cross-sectional view schematically showing an enlarged view of an end portion of the first electrode layer according to the embodiment.

[0060] Explanation of symbols

[0061] 10-ceramic dielectric substrate; 10a-first main surface; 10b-second main surface; 11, 11A, 11B-first electrode layer; 11a-first surface; 11b-second surface; 11c-central portion; 11d-end portion; 11e-edge portion; 11p-hole; 12-second electrode layer; 12a-third surface; 12b-fourth surface; 13-convex portion; 14-groove; 15-through hole; 20-connecting portion; 50-base plate; 50a-upper portion; 50b-lower portion; 51-input path; 52-output Path; 53-gas inlet path; 55-connecting path; 60-adhesive component; 100, 100A-electrostatic suction cup; 500, 500A-wafer processing device; 501-processing container; 502-processing gas inlet port; 503-exhaust port; 504-high frequency power supply; 505-power supply for adsorption; 510-upper electrode; 510a-below; D1, D1c, D1d, D2c, D2d, D3, D4-distance; P-lower end; R1, R2-area; t-width; W-object. DETAILED DESCRIPTION

[0062] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each of the drawings, the same components are denoted by the same reference numerals and detailed descriptions thereof are appropriately omitted.

[0063] Figure 1 It is a schematic cross-sectional view illustrating an electrostatic chuck according to an embodiment.

[0064] like Figure 1 As shown, the electrostatic chuck 100 includes a ceramic dielectric substrate 10 , a first electrode layer 11 , and a base plate 50 .

[0065] The ceramic dielectric substrate 10 is a flat plate-shaped base material formed, for example, by sintering ceramics. For example, the ceramic dielectric substrate 10 contains aluminum oxide (Al2O3). 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 % (mass%) or more and 100 mass % or less, preferably 95 mass % (mass%) or more and 100 mass % or less, and more preferably 99 mass % (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. In addition, the concentration of aluminum oxide can be measured by fluorescent X-ray analysis or the like.

[0066] 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 an adsorption object W is placed. The second main surface 10b is a surface opposite to the first main surface 10a. The adsorption object W is, for example, a semiconductor substrate such as a silicon wafer.

[0067] Furthermore, in the present specification, the direction from the base plate 50 toward the ceramic dielectric substrate 10 is referred to as the Z-axis direction. For example, as illustrated in each figure, the Z-axis direction is the direction connecting the first principal surface 10a and the second principal surface 10b. The Z-axis direction is, for example, a direction substantially perpendicular to the first principal surface 10a and the second principal surface 10b. A direction orthogonal to the Z-axis direction is referred to as the X-axis direction, and a direction orthogonal to the Z-axis direction and the X-axis direction is referred to as the Y-axis direction. In the present specification, "in-plane" is, for example, in the XY plane.

[0068] The first electrode layer 11 is provided inside the ceramic dielectric substrate 10. The first electrode layer 11 is provided between the first main surface 10a and the second main surface 10b. That is, the first electrode layer 11 is provided so as to be inserted into the ceramic dielectric substrate 10. The first electrode layer 11 may be built-in by being sintered integrally with the ceramic dielectric substrate 10, for example.

[0069] In this way, since the first electrode layer 11 is disposed inside the ceramic dielectric substrate 10, the upper electrode ( Figure 7 The distance between the upper electrode 510 of the substrate and the first electrode layer 11 (lower electrode) is reduced. Thus, for example, compared with the case where the base plate 50 is used as the lower electrode, the plasma density can be increased with lower power. In other words, the power required to obtain a higher plasma density can be reduced.

[0070] The first electrode layer 11 is in the shape of a thin film extending along the first main surface 10a and the second main surface 10b of the ceramic dielectric substrate 10. The cross-sectional shape of the first electrode layer 11 will be described later.

[0071] The first electrode layer 11 is connected to a high frequency power source ( Figure 7 By supplying a high frequency power source 504 to the upper electrode ( Figure 7 A voltage (high frequency voltage) is applied to the upper electrode 510 and the first electrode layer 11, thereby generating plasma 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 a high frequency AC (alternating current) current to the first electrode layer 11. The "high frequency" mentioned here is, for example, 200 kHz or more.

[0072] The first electrode layer 11 is made of metal, for example. The first electrode layer 11 includes, for example, at least one of Ag, Pd, and Pt. The first electrode layer 11 may also include, for example, metal or ceramic. The first electrode layer 11 may also be formed of, for example, a cermet of metal and ceramic. Cermet is a composite material including 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. In addition, the strength of the first electrode layer 11 can be improved.

[0073] The metal contained in the metal ceramic includes, for example, at least one of Ag, Pd and Pt. In addition, the ceramic contained in the metal ceramic includes, for example, the same element as the ceramic contained in the ceramic dielectric substrate 10. By forming the first electrode layer 11 from a metal ceramic containing the same element as the ceramic contained in the ceramic dielectric substrate 10, the difference between the thermal expansion coefficient of the first electrode layer 11 and the thermal expansion coefficient of the ceramic dielectric substrate 10 can be reduced. As a result, the adhesion between the first electrode layer 11 and the ceramic dielectric substrate 10 is improved, and the occurrence of undesirable conditions such as peeling can be suppressed. In addition, the ceramic contained in the metal ceramic may also contain an element different from the ceramic contained in the ceramic dielectric substrate 10.

[0074] In this example, the first electrode layer 11 is connected to an adsorption power source ( Figure 7The electrostatic suction cup 100 is as follows: by applying a voltage (adsorption voltage) to the first electrode layer 11 from the adsorption power supply, electric charges are generated on the first main surface 10a side of the first electrode layer 11, and the object W is adsorbed and held by electrostatic force. In other words, the first electrode layer 11 is an adsorption electrode for adsorbing the object W. According to the embodiment, in this way, the lower electrode for generating plasma, i.e., the first electrode layer 11, can also be used as an adsorption electrode for adsorbing the object. The adsorption power supply supplies a direct current (DC) current or an AC current to the first electrode layer 11. The adsorption power supply is, for example, a DC power supply. The adsorption power supply can also be, for example, an AC power supply.

[0075] The first electrode layer 11 is provided with a connection portion 20 extending toward the second main surface 10b 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 connected to the first electrode layer 11. The connection portion 20 may also be a metal terminal that is connected by an appropriate method such as soldering.

[0076] The base plate 50 is a member that supports the ceramic dielectric substrate 10. The ceramic dielectric substrate 10 is fixed to the base plate 50 via an adhesive member 60. As the adhesive member 60, for example, a silicone adhesive is used.

[0077] The base plate 50 is made of metal such as aluminum. The base plate 50 may also be made of ceramic. The base plate 50 is divided into an upper portion 50a and a lower portion 50b, and a communication path 55 is provided between the upper portion 50a and the lower portion 50b. One end of the communication path 55 is connected to the input path 51, and the other end of the communication path 55 is connected to the output path 52.

[0078] The base plate 50 also plays a role in adjusting the temperature of the electrostatic chuck 100. For example, when cooling the electrostatic chuck 100, a cooling medium such as helium flows in from the input path 51, passes through the connecting path 55, and then flows out from the output path 52. Thus, the cooling medium absorbs the heat of the base plate 50, and the ceramic dielectric substrate 10 mounted thereon can be cooled. On the other hand, when the electrostatic chuck 100 is kept warm, a heat-insulating medium can also be placed in the connecting path 55. A heating element can also be placed inside the ceramic dielectric substrate 10 and the base plate 50. By adjusting the temperature of the base plate 50 and the ceramic dielectric substrate 10, the temperature of the object W adsorbed and held by the electrostatic chuck 100 can be adjusted.

[0079] In this example, a groove 14 is provided on the first main surface 10a side of the ceramic dielectric substrate 10. The groove 14 is recessed in the direction (Z-axis direction) from the first main surface 10a toward the second main surface 10b, and extends continuously in the XY 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 that contacts the back surface of the object W. 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 back surface of the object W placed on the electrostatic chuck 100 and the groove 14.

[0080] The ceramic dielectric substrate 10 has a through hole 15 connected to the groove 14. The through hole 15 is provided from the second main surface 10b to the first main surface 10a. That is, the through hole 15 extends in the Z-axis direction from the second main surface 10b to the first main surface 10a and penetrates the ceramic dielectric substrate 10.

[0081] By appropriately selecting the height of the projection 13 (depth of the groove 14 ), the area ratio and shape of the projection 13 and the groove 14 , etc., the temperature of the object W and the particles attached to the object W can be controlled to a preferred state.

[0082] The gas introduction path 53 is provided on the base plate 50. The gas introduction path 53 is provided, for example, to penetrate the base plate 50. The gas introduction path 53 may not penetrate the base plate 50 but may branch from other gas introduction paths 53 in the middle and be provided to the ceramic dielectric substrate 10 side. In addition, the gas introduction path 53 may be provided at multiple locations on the base plate 50.

[0083] The gas introduction path 53 communicates with the through hole 15 . That is, the heat transfer gas (helium (He) or the like) that flows into the gas introduction path 53 flows into the through hole 15 after passing through the gas introduction path 53 .

[0084] The heat transfer 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. Thus, the object W can be directly cooled by the heat transfer gas.

[0085] Figure 2 It is a cross-sectional view schematically showing a part of the electrostatic chuck according to the embodiment in an enlarged manner.

[0086] Figure 3 (a)~ Figure 3 (c) is a cross-sectional view schematically showing a modified example of the first electrode layer of the electrostatic chuck according to the embodiment.

[0087] Figure 2 Medium zoom display Figure 1 Region R1 is shown.

[0088] like Figure 2As shown, 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 on the opposite side of the first surface 11a. In other words, the first surface 11a is a surface opposite to the first main surface 10a. In other words, the second surface 11b is a surface opposite to the second main surface 10b.

[0089] In the first electrode layer 11, the surface roughness Ra2 of the second surface 11b is greater than the surface roughness Ra1 of the first surface 11a. In the present specification, the surface roughness refers to, for example, the arithmetic mean roughness (Ra), which can be calculated by the following method.

[0090] The electrostatic chuck 100 is cut out in a manner including the first electrode layer 11, and the portion filled with resin is polished and then observed using a SEM (Scanning Electron Microscope). The arithmetic mean roughness Ra is calculated from the SEM images taken at 100 to 1000 times by a method based on JIS (Japanese Industrial Standards) B 0601: 2013. In addition, the surface roughness Ra1 of the first surface 11a is calculated using a contour curve depicting the interface between the first surface 11a of the first electrode layer 11 and the ceramic dielectric substrate 10 or the void (void). The surface roughness Ra2 of the second surface 11b is calculated using a contour curve depicting the interface between the second surface 11b of the first electrode layer 11 and the ceramic dielectric substrate 10 or the void (void).

[0091] The inventors have discovered the following new problem: when the first electrode layer 11 connected to the high-frequency power source is disposed inside the ceramic dielectric substrate 10 and the high-frequency power source applied to the first electrode layer 11 is increased in power in order to increase the plasma density, the first electrode layer 11 generates heat and the combustion chamber ( Figure 8 The internal environment of the processing container 501) changes, which has an adverse effect on the in-plane uniformity of the plasma density.

[0092] In contrast, according to the embodiment, since the surface roughness Ra2 of the second surface 11b is made greater than the surface roughness Ra1 of the first surface 11a, the contact area between the second surface 11b, which is the surface of the first electrode layer 11 on the side of the base plate 50 having a cooling function, and the ceramic dielectric substrate 10 can be increased. As a result, the heat dissipation of the first electrode layer 11 (lower electrode) can be improved, and the in-plane uniformity of the plasma density can be improved.

[0093] The surface roughness Ra1 of the first surface 11 a is, for example, not less than 0.1 μm and not more than 10 μm. The surface roughness Ra2 of the second surface 11 b is, for example, not less than 0.2 μm and not more than 20 μm.

[0094] In an embodiment, the distance D1 between the first surface 11a and the first main surface 10a along the Z-axis direction is, for example, constant. In other words, the distance D1 is the distance from the first main surface 10a to the top of the first electrode layer 11 (the first surface 11a). Here, "constant" may include, for example, undulations of the first surface 11a. For example, when a cross section of the electrostatic chuck 100 is observed at a low magnification (for example, about 100 times) by a scanning electron microscope (SEM) or the like, the distance D1 may be approximately constant. For example, the difference between the distance D1c at the center 11c of the first electrode layer 11 and the distance D1d at the end 11d of the first electrode layer 11 is 0±150μm. The distance D1 (the distance D1c and the distance D1d) is, for example, about 300μm. The first surface 11a is, for example, a surface parallel to the first main surface 10a.

[0095] like Figure 2 As shown in the figure, the end portion 11d of the first electrode layer 11 is a region including the edge 11e of the first electrode layer 11 on the XY plane. The edge 11e of the first electrode layer 11 refers to the interface between the first electrode layer 11 and the ceramic dielectric substrate 10 when the first surface 11a is located and viewed from the Z-axis direction. The central portion 11c of the first electrode layer 11 is a region located between the two end portions 11d on the XY plane. The central portion 11c and the end portions 11d of the first electrode layer 11 will be described later.

[0096] In this way, since the distance D1 between the first surface 11a and the first main surface 10a in the Z-axis direction is constant, the upper electrode ( Figure 7 The distance between the upper electrode 510) and the first electrode layer 11 (lower electrode) is constant. Thus, for example, the in-plane uniformity of the plasma density can be improved compared to a case where the distance D1 between the first surface 11a and the first main surface 10a in the Z-axis direction is not constant. For example, in a case where the cross-sectional shape of the first electrode layer 11 is convex upward, the in-plane uniformity of the plasma density can be improved compared to a case where the distance between the first surface 11a and the first main surface 10a in the Z-axis direction at the end portion 11d is different from the distance between the first surface 11a and the first main surface 10a in the Z-axis direction at the center portion 11c.

[0097] 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, for example, substantially the same as the distance D2c along the Z-axis direction between the second surface 11b and the first surface 11a at the central portion 11c of the first electrode layer 11. In other words, the distance D2c is the thickness of the first electrode layer 11 at the central portion 11c. In other words, the distance D2d is the thickness of the first electrode layer 11 at the end 11d. That is, the thickness of the first electrode layer 11 at the end 11d is substantially the same as the thickness of the first electrode layer 11 at the central portion 11c. The thickness of the first electrode layer 11 is, for example, constant.

[0098] The cross-sectional shape of the first electrode layer 11 is not limited thereto. Figure 3 (a)~ Figure 3 As shown in (c), the cross-sectional shape of the first electrode layer 11 is preferably 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 smaller than the distance D2c along the Z-axis direction between the second surface 11b and the first surface 11a at the central portion 11c of the first electrode layer 11. That is, in these examples, the thickness of the first electrode layer 11 at the end 11d is smaller than the thickness of the first electrode layer 11 at the central portion 11c. For example, the thickness of the first electrode layer 11 decreases as it moves from the central portion 11c toward the end 11d. The first electrode layer 11 has a shape that convexly projects toward the second surface 11b.

[0099] The distance D2c is, for example, greater than 1 μm and less than 500 μm, preferably greater than 10 μm and less than 100 μm, and more preferably greater than 20 μm and less than 70 μm. By making the thickness of the first electrode layer 11 at the central portion 11c (distance D2c) 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. For example, the distance D2c can be obtained by finding the average value of the thickness of three points at the central portion 11c of the first electrode layer 11 on a cross-sectional SEM (Scanning Electron Microscope) image. In the present application specification, this average value is defined as the distance D2c.

[0100] A high-frequency current is supplied to the first electrode layer 11 from the second surface 11b side. Generally, when an AC current flows in 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 it moves away from the surface. In addition, the higher the frequency of the flowing AC current, the more significant the surface concentration of the current. That is, the high-frequency AC current flowing into the first electrode layer 11 from the second surface 11b side passes through the second surface 11b of the first electrode layer 11 and flows into the first surface 11a.

[0101] In the embodiment, since 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 made smaller than the distance D2c along the Z-axis direction between the second surface 11b and the first surface 11a at the central portion 11c of the first electrode layer 11, the power supply distance from the second surface 11b to the first surface 11a can be shortened. As a result, the sensitivity of control to changes in RF output, etc. (RF sensitivity) can be further improved.

[0102] In addition, according to the embodiment, the distance D2d between the second surface 11b and the first surface 11a at the end 11d of the first electrode layer 11 along the Z-axis direction is smaller than the distance D2c between the second surface 11b and the first surface 11a at the central portion 11c of the first electrode layer 11 along the Z-axis direction. For example, since the first electrode layer 11 is convex toward the second surface 11b side (that is, the base plate 50 side), the surface area of ​​the second surface 11b on the base plate 50 side of the first electrode layer 11 having a cooling function can be relatively increased. As a result, the first electrode layer 11 can dissipate heat more effectively, and the in-plane uniformity of the plasma density can be further improved.

[0103] And, in Figure 3 In the example of (a), the thickness of the first electrode layer 11 is approximately constant at the central portion 11c. In other words, at the central portion 11c, the second surface 11b is approximately parallel to the first surface 11a. On the other hand, at the end portion 11d, the thickness of the first electrode layer 11 decreases from the central portion 11c side toward the edge 11e. In other words, at 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 11e. In this example, the inclined surface is planar. As shown in FIG. Figure 3 As shown in (b), the inclined surface can also be curved.

[0104] In addition, for example Figure 3 As shown in (c), the second surface 11b may also have an inclined surface that inclines upward from the center of the second surface 11b on the XY plane toward the edge 11e. In other words, the thickness of the first electrode layer 11 may not be fixed at the center 11c. In other words, the second surface 11b may not be parallel to the first surface 11a at the center 11c. In addition, in this case, Figure 3 As shown in (c), the inclined surface can also be curved.

[0105] Figure 4 (a) Figure 4 (b) Figure 5 (a) Figure 5 (b) Figure 6 (a) Figure 6(b) is a plan view schematically showing a portion of the electrostatic chuck according to the embodiment.

[0106] These figures are plan views of the first electrode layer 11 observed from the second surface 11b side (lower side) in the electrostatic chuck 100 in a state where a portion of the ceramic dielectric substrate 10 that is arranged closer to the base plate 50 side (lower side) than the first electrode layer 11 (second surface 11b) and the base plate 50 are omitted.

[0107] like Figure 4 (a) Figure 4 (b) Figure 5 (a) Figure 5 (b) Figure 6 (a) Figure 6 As shown in (b), the electrostatic chuck 100 is provided with at least one first electrode layer 11 extending along the XY plane. The number of the first electrode layers 11 can be, for example, Figure 4 (a) and Figure 4 (b) shows 1, and can also be Figure 5 (a) and Figure 5 (b) shows two, or it can be Figure 6 (a) and Figure 6 (b) shows three or more (four in this example). When a plurality of first electrode layers 11 are provided, the first electrode layers 11 may be located on the same plane or on different planes in the Z-axis direction, for example.

[0108] exist Figure 4 (a) and Figure 4 In the example shown in (b), the first electrode layer 11 is circular when viewed along the Z-axis direction, and is arranged, for example, so that the center of the first electrode layer 11 overlaps with the center of the ceramic dielectric substrate 10. The edge 11e of the first electrode layer 11 is, for example, concentric with the edge of the ceramic dielectric substrate 10. In this example, the end 11d of the first electrode layer 11 is arranged on the outer peripheral side of the ceramic dielectric substrate 10 in a ring shape.

[0109] exist Figure 5 (a) and Figure 5In the example shown in (b), for example, the inner first electrode layer 11A and the outer first electrode layer 11B are arranged in a concentric shape. The inner first electrode layer 11A is, for example, circular when viewed along the Z-axis direction. The outer first electrode layer 11B is, for example, an annular shape surrounding the inner first electrode layer 11A when viewed along the Z-axis direction. The inner first electrode layer 11A and the outer first electrode layer 11B are arranged in a concentric shape such that the center of the inner first electrode layer 11A overlaps the center of the ceramic dielectric substrate 10. 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. In addition, 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 in a concentric shape.

[0110] exist Figure 6 (a) and Figure 6 In the example shown in (b), a plurality of first electrode layers 11 that are circular when viewed along the Z-axis direction are arranged, for example, at positions that are point-symmetrical with respect to the center of the ceramic dielectric substrate 10. Furthermore, one first electrode layer 11 may be arranged so that the center of the first electrode layer 11 overlaps with the center of the ceramic dielectric substrate 10. In other words, one first electrode layer 11 may be arranged at the center of the ceramic dielectric substrate 10. In this example, the end 11d of each first electrode layer 11 is arranged in a ring shape on the outer peripheral side of each first electrode layer 11.

[0111] In addition, if Figure 4 (b) Figure 5 (b) Figure 6 As shown in (b), the first electrode layer 11 may further include a hole 11p that penetrates the first electrode layer 11 in the Z-axis direction. When the hole 11p is provided, the end portion 11d is also disposed near the outer periphery of the hole 11p.

[0112] In the embodiment, even at any part of these end parts 11d, the relationship between the distance D2d between the first surface 11a and the second surface 11b at the end parts 11d and the distance D2c between the first surface 11a and the second surface 11b at the central part 11c can be made to satisfy D2d<D2c. On the other hand, within the scope of exerting the effect of the present invention, it is not excluded to include a part that does not satisfy D2d<D2c. In other words, in the embodiment, in at least a part of the end parts 11d as described above, D2d<D2c is preferably satisfied. For example, if there are more parts in the end parts 11d that satisfy D2d<D2c, the RF sensitivity can be further improved.

[0113] As described above, the central portion 11c of the first electrode layer 11 is a region located between the two end portions 11d on the XY plane. For example, in the first electrode layer 11, the entire region other than the end portions 11d may be regarded as the central portion 11c. In other words, in the first electrode layer 11, for example, the vicinity of the edge portion 11e may be regarded as the end portion 11d, and the rest of the region may be regarded as the central portion 11c.

[0114] Hereinafter, a method for manufacturing the ceramic dielectric substrate 10 in which the first electrode layer 11 is provided will be described.

[0115] The ceramic dielectric substrate 10 in which the first electrode layer 11 is provided can be produced, for example, by stacking the layers with the first main surface 10a side facing downward and sintering the stacked body. More specifically, for example, the first electrode layer 11 is stacked on the first layer, which becomes the ceramic layer including the first main surface 10a. The second layer, which becomes the ceramic layer including the second main surface 10b, is stacked on the first electrode layer 11. Thereafter, the stacked body is sintered.

[0116] The first electrode layer 11 is formed, for example, by screen printing, paste coating (spin coating, coating, inkjet printing, dispensing, etc.), vapor deposition, etc. For example, the first electrode layer 11 can be formed by laminating each layer multiple times with the first main surface 10a facing downward. At this time, for example, by adjusting the lamination conditions, the relationship between the surface roughness Ra2 of the second surface 11b of the first electrode layer 11 and the surface roughness Ra1 of the first surface 11a can satisfy Ra1<Ra2.

[0117] Figure 7 It is a cross-sectional view schematically showing a wafer processing apparatus including an electrostatic chuck according to an embodiment.

[0118] like Figure 7 As shown, the wafer processing apparatus 500 includes a processing container 501, a high frequency power source 504, a power source for adsorption 505, an upper electrode 510, and an electrostatic chuck 100. A processing gas inlet 502 for introducing a processing gas into the interior and the upper electrode 510 are provided on the top surface of the processing container 501. An exhaust port 503 for decompressing and exhausting the interior is provided on the bottom plate of the processing container 501. The electrostatic chuck 100 is arranged below the upper electrode 510 in the processing container 501. The first electrode layer 11 of the electrostatic chuck 100 and the upper electrode 510 are connected to the high frequency power source 504. In addition, in this example, the first electrode layer 11 of the electrostatic chuck 100 is connected to the power source for adsorption 505.

[0119] The first electrode layer 11 and the upper electrode 510 are arranged substantially parallel to each other with a predetermined interval therebetween. 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 lower surface 510a of the upper electrode 510. The object W is placed on the first main surface 10a located between the first electrode layer 11 and the upper electrode 510.

[0120] When a voltage (high frequency voltage) is applied to the first electrode layer 11 and the upper electrode 510 from the high frequency power supply 504, high frequency discharge is generated and the processing gas introduced into the processing container 501 is excited and activated by plasma, so that the object W is processed.

[0121] When a voltage (attraction voltage) is applied to the first electrode layer 11 from the attraction power supply 505 , electric charges are generated on the first principal surface 10 a side of the first electrode layer 11 , and the object W is attracted and held on the electrostatic chuck 100 by electrostatic force.

[0122] Figure 8 It is a cross-sectional view schematically showing another electrostatic chuck according to the embodiment.

[0123] Fig. 9 It is a cross-sectional view schematically showing an enlarged view of a part of another electrostatic chuck according to the embodiment.

[0124] Fig. 9 Medium zoom display Figure 8 Region R2 shown.

[0125] like Figure 8 and Fig. 9 As shown in FIG. 1 , in the electrostatic chuck 100A, a second electrode layer 12 is provided inside the ceramic dielectric substrate 10 in addition to the first electrode layer 11. 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. The second electrode layer 12 is, for example, sintered integrally to the ceramic dielectric substrate 10.

[0126] The second electrode layer 12 is in the form of a thin film along the first main surface 10a and the second main surface 10b of the ceramic dielectric substrate 10. The second electrode layer 12 is made of metal, for example. The second electrode layer 12 includes, for example, at least one of Ag, Pd, Pt, Mo, and W. The second electrode layer 12 may also include, for example, metal or ceramic.

[0127] When the first electrode layer 11 contains metal and ceramics and the second electrode layer 12 contains metal and ceramics, the volume ratio of the metal to the total volume of the metal contained in the first electrode layer 11 and the volume of the ceramics is preferably greater than the volume ratio of the metal to the total volume of the metal contained in the second electrode layer 12 and the volume of the ceramics.

[0128] In this way, since the proportion of metal contained in the first electrode layer 11 is greater than the proportion of metal contained in the second electrode layer 12, for example, the resistance of the first electrode layer 11 to which voltage is applied from a high-frequency power supply can be further reduced, and the in-plane uniformity and RF sensitivity of the plasma density can be improved.

[0129] In the embodiment, the cross-section of the first electrode layer 11 and the second electrode layer 12 can be observed by SEM-EDX (Energy Dispersive X-ray Spectroscopy) and the volume ratio of the metal to the total volume of the metal and the volume of the ceramic can be 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, the ceramic and the metal are classified by EDX component analysis, and the area ratio of the ceramic and the metal is obtained by image analysis, so that the volume ratio of the metal to the total volume of the metal and the volume of the ceramic can be calculated.

[0130] When the first electrode layer 11 includes metal and ceramics and the second electrode layer 12 includes metal and ceramics, the volume of the metal included in the first electrode layer 11 is preferably larger than the volume of the metal included in the second electrode layer 12 .

[0131] In this way, since the volume of metal contained in the first electrode layer 11 is larger than the volume of metal contained in the second electrode layer 12, for example, the resistance of the first electrode layer 11 to which voltage is applied from a high-frequency power supply can be further reduced, thereby improving the in-plane uniformity and RF sensitivity of the plasma density.

[0132] The second electrode layer 12 is connected to an adsorption power source ( Fig.11 The electrostatic chuck 100A applies a voltage (adsorption voltage) to the second electrode layer 12 from the adsorption power supply, thereby generating electric charge on the first main surface 10a side of the second electrode layer 12, and adsorbs 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 adsorption power supply supplies a direct current (DC) current or an AC current to the second electrode layer 12. In this way, according to the embodiment, in addition to the lower electrode for generating plasma, i.e., the first electrode layer 11, an adsorption electrode for adsorbing the object can also be provided.

[0133] In this example, the second electrode layer 12 is provided with a connection portion 20 extending toward the second main surface 10b of the ceramic dielectric substrate 10. The connection portion 20 is, for example, a via hole (solid type) or a through hole (hollow type) connected to the second electrode layer 12. The connection portion 20 may also be a metal terminal connected by an appropriate method such as soldering.

[0134] like Fig. 9 As shown, the second electrode layer 12 has: a third surface 12a on the first main surface 10a side; and a fourth surface 12b on the opposite side of the third surface 12a. In other words, the fourth surface 12b is a surface opposite to 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.

[0135] The third surface 12a may be parallel to the first main surface 10a. The distance D3 between the third surface 12a and the first main surface 10a along the Z-axis direction is constant, for example. In other words, the distance D3 is the distance from the first main surface 10a to the top of the second electrode layer 12 (the third surface 12a).

[0136] It is preferred that the fourth surface 12b is a surface parallel to the third surface 12a. It is also preferred that the fourth surface 12b is a surface parallel to the first main surface 10a. More specifically, it is also preferred that the distance D4 between the fourth surface 12b and the third surface 12a along the Z-axis direction is constant. In other words, the distance D4 is the thickness of the second electrode layer 12. For example, the average thickness of the second electrode layer 12 can be obtained by obtaining the average value of the thickness of three points on the cross-sectional SEM image of the second electrode layer 12.

[0137] The average thickness of the first electrode layer 11 is, for example, greater than that of the second electrode layer 12. Since the average thickness of the first electrode layer 11 is greater than that 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.

[0138] The distance along the Z-axis direction between the first electrode layer 11 and the second electrode layer 12 (i.e., the distance along the Z-axis direction between the first surface 11a and the fourth surface 12b) D5 is, for example, greater than the distance along the Z-axis direction between the first principal surface 10a and the second electrode layer 12 (i.e., the distance along the Z-axis direction between the third surface 12a and the first principal surface 10a) D3.

[0139] Since the distance D5 is made larger than the distance D3 in this way, even when a voltage is applied from a high-frequency power source, it is possible to more effectively suppress problems such as a short circuit or insulation breakdown between the first electrode layer 11 and the second electrode layer 12 .

[0140] Fig.10 (a) and Fig.10(b) is a plan view schematically showing a portion of another electrostatic chuck according to the embodiment.

[0141] These figures are plan views of the second electrode layer 12 viewed from the third surface 12a side (upper side) in a state where a portion of the ceramic dielectric substrate 10 disposed closer to the first principal surface 10a side (upper side) than the second electrode layer 12 (third surface 12a) is omitted in the electrostatic chuck 100A.

[0142] like Fig.10 (a) and Fig.10 As shown in (b), the second electrode layer 12 can be either a monopolar type or a bipolar type. When the second electrode layer 12 is a monopolar type, as shown in Fig.10 As shown in (a), a second electrode layer 12 is provided which is expanded along the XY plane. For example, when viewed along the Z-axis direction, the second electrode layer 12 is substantially circular. On the other hand, when the second electrode layer 12 is a bipolar type, as shown in FIG. Fig.10 As shown in (b), two second electrode layers 12 are provided which are expanded along the XY plane and are located on the same plane. For example, when viewed along the Z axis direction, each of the second electrode layers 12 is substantially semicircular. The second electrode layer 12 may also be in a pattern expanded along the XY plane, for example.

[0143] In the Z-axis direction, a portion of the first electrode layer 11 does not overlap the second electrode layer 12, for example. In addition, 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 total area of ​​the third surface 12a (the surface on the first main surface 10a side) of the second electrode layer 12. In other words, when viewed along the Z-axis direction, the total area of ​​the first electrode layer 11 is larger than the total area of ​​the second electrode layer 12. As a result, the in-plane uniformity of the plasma density can be further improved.

[0144] Fig.11 It is a cross-sectional view schematically showing a wafer processing apparatus including another electrostatic chuck according to an embodiment.

[0145] like Fig.11 As shown, in the wafer processing apparatus 500A, the electrostatic chuck 100 is changed to Figure 8 The electrostatic chuck 100A shown is otherwise substantially the same as Figure 7 Wafer processing apparatus 500 is shown.

[0146] In the wafer processing apparatus 500A, the adsorption power source 505 is connected to the second electrode layer 12 of the electrostatic chuck 100A, not to the first electrode layer 11 of the electrostatic chuck 100A. When a voltage (adsorption voltage) is applied to the second electrode layer 12 from the adsorption power source 505, electric charges are 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 100A by electrostatic force.

[0147] Fig.12 (a)~ Fig.12 (d) is a cross-sectional view schematically showing an enlarged view of an end portion of the first electrode layer according to the embodiment.

[0148] like Fig.12 (a)~ Fig.12 As shown in (d), the length in the X-axis direction of the end 11d of the first electrode layer 11 when viewed in cross section, i.e., the width t, is, for example, greater than the thickness D2c at the central portion 11c of the first electrode layer 11 (thickness D2c < width t). In other words, the width t of the end 11d is 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 (the portion where the inclination just ends) of the inclined surface of the second surface 11b and the edge 11e. In this way, since the width t of the end 11d is made greater than the thickness D2c at the central portion 11c of the first electrode layer 11, the power supply distance can be shortened. As a result, the sensitivity (RF sensitivity) of the control of changes in RF output, etc. can be further improved.

[0149] The lower end P of the inclined surface can be obtained from a cross-sectional image of the sample cut in a manner including the first electrode layer 11. In the embodiment, for example, at least one portion of the sample satisfies the above relationship (thickness D2c < width t). In the embodiment, more preferably, multiple portions of the sample satisfy the above relationship (thickness D2c < width t).

[0150] In addition, the angle θ of the inclined surface of the second surface 11b is, for example, not less than 10 degrees and not more than 80 degrees, preferably not less than 20 degrees and not more than 60 degrees. When the straight line connecting the edge 11e and the lower end P of the inclined surface of the second surface 11b (the part where the inclination just ends) is taken as the line L, the angle θ can be expressed by the angle (minor angle) formed by the first surface 11a and the line L. By reducing the angle θ, the power supply distance can be shortened. As a result, the sensitivity (RF sensitivity) of the control of the change of the RF output, etc. can be further improved.

[0151] In addition, although the cross-sectional shape between the lower end P and the edge 11e is curved in these figures, the cross-sectional shape between the lower end P and the edge 11e is not limited to this, and may be linear. By making it linear, for example, the power supply distance can be further shortened.

[0152] As described above, according to the embodiment, it is possible to provide an electrostatic chuck capable of improving RF sensitivity and improving the in-plane uniformity of plasma density.

[0153] The above is a description of the embodiments of the present invention. However, the present invention is not limited to the above contents. In addition, with respect to the aforementioned embodiments, as long as they have the characteristics of the present invention, the technology that is appropriately designed and changed by those skilled in the art is also included in the scope of the present invention. For example, the shape, size, material, configuration, setting method, etc. of each element possessed by the electrostatic chuck are not limited to the exemplified contents, but can be appropriately changed. In addition, as long as it is technically feasible, the various elements possessed by the aforementioned embodiments can be combined, and as long as the technology after these combinations includes the characteristics of the present invention, it is also included in the scope of the present invention.

Claims

1. An electrostatic chuck, comprising: A ceramic dielectric substrate having a first main surface on which an adsorption object is placed and a second main surface opposite to the first main surface; a base plate supporting the ceramic dielectric substrate; and at least one first electrode layer, arranged inside the ceramic dielectric substrate and connected to a high frequency power source, characterized in that: The first electrode layer is provided between the first main surface and the second main surface in a Z-axis direction from the base plate toward the ceramic dielectric substrate. 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. The surface roughness of the second surface is greater than the surface roughness of the first surface.

2. The electrostatic chuck according to claim 1, characterized in that: supplying power to the first electrode layer from the second surface side, The distance between the first surface and the first main surface along the Z-axis direction is constant, A distance between the second surface and the first surface at an end of the first electrode layer along the Z-axis direction is smaller than a distance between the second surface and the first surface at a center of the first electrode layer along the Z-axis direction.

3. The electrostatic chuck according to claim 1 or 2, characterized in that: The first electrode layer includes at least any one of Ag, Pd, and Pt.

4. The electrostatic chuck according to claim 1 or 2, characterized in that: The first electrode layer is formed of cermet of metal and ceramic.

5. The electrostatic chuck according to claim 1 or 2, characterized in that: The ceramic dielectric substrate comprises aluminum oxide, The concentration of the aluminum oxide in the ceramic dielectric substrate is 90 mass % or more.

6. The electrostatic chuck according to claim 1 or 2, characterized in that: It also includes at least one second electrode layer, which is provided inside the ceramic dielectric substrate and connected to an adsorption power source. In the Z-axis direction, the second electrode layer is provided between the first electrode layer and the first main surface.

7. The electrostatic chuck according to claim 6, characterized in that: The total area of ​​the first surface of the first electrode layer is larger than the total area of ​​the surface of the second electrode layer on the first main surface side.

8. The electrostatic chuck according to claim 6, wherein: In the Z-axis direction, a portion of the first electrode layer does not overlap with the second electrode layer.

9. The electrostatic chuck according to claim 6, wherein: The first electrode layer comprises metal and ceramic, The second electrode layer comprises metal and ceramic, The volume ratio of the metal to the total volume of the metal and the ceramic included in the first electrode layer is greater than the volume ratio of the metal to the total volume of the metal and the ceramic included in the second electrode layer.

10. The electrostatic chuck according to claim 6, wherein: The first electrode layer comprises metal and ceramic, The second electrode layer comprises metal and ceramic, The volume of the metal included in the first electrode layer is greater than the volume of the metal included in the second electrode layer.

11. The electrostatic chuck according to claim 1 or 2, characterized in that: The first electrode layer is connected to an adsorption power source.

12. The electrostatic chuck according to claim 2, wherein: The width of the end portion is larger than a distance between the second surface and the first surface in the central portion of the first electrode layer along the Z-axis direction.

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