electrostatic chuck

Abstract

The present invention provides an electrostatic chuck capable of suppressing variations in the in-plane temperature distribution of a substrate during processing. [Solution] The electrostatic chuck 10 comprises a dielectric substrate 100, an RF electrode 140 provided inside the dielectric substrate 100, and a covering conductive layer 160 covering the bottom surface 151 and inner surface 152 of a recess 150 formed on the surface 120 of the dielectric substrate 100. The covering conductive layer 160 is connected to the RF electrode 140 exposed on the inner surface 152 of the recess 150, and the thickness of the covering conductive layer 160 is greater than the thickness of the RF electrode 140.

Description

Technical Field

[0001] The present invention relates to an electrostatic chuck.

Background Art

[0002] For example, in a semiconductor manufacturing apparatus such as an etching apparatus, an electrostatic chuck is provided as a device for adsorbing and holding a substrate such as a silicon wafer to be processed. The electrostatic chuck includes a dielectric substrate provided with an adsorption electrode, and a base plate that supports the dielectric substrate, and these have a configuration in which they are joined to each other. When a voltage is applied to the adsorption electrode, an electrostatic force is generated, and the substrate placed on the dielectric substrate is adsorbed and held.

[0003] Inside the dielectric substrate, an internal conductor layer is provided separately from the above-described adsorption electrode. For example, an RF electrode that functions as one of a pair of opposing electrodes for generating plasma in a semiconductor manufacturing apparatus may be provided as the above-mentioned "internal conductor layer". Also, an electrode that functions as a heater for heating the dielectric substrate may be provided as the above-mentioned "internal conductor layer".

[0004] As a configuration for guiding the power supplied from the outside to the internal conductor layer, for example, as described in Patent Document 1 below, a configuration in which the power supply terminal provided on the lower surface of the dielectric substrate and the internal conductor layer are electrically connected via a via is known. A "via" is a hole formed in a dielectric substrate filled with a conductor.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Because vias are thin conductors, their electrical resistance is relatively high. Therefore, in a configuration where vias connect the power supply terminals to the internal conductor layer, localized heat generation may occur at the vias. As a result, the in-plane temperature distribution of the substrate during processing may become more variable.

[0007] The present invention has been made in view of these problems, and its objective is to provide an electrostatic chuck that can suppress variations in the in-plane temperature distribution of a substrate during processing. [Means for solving the problem]

[0008] To solve the above problems, the electrostatic chuck according to the present invention comprises a dielectric substrate having a mounting surface on which an object to be adsorbed is placed, an internal conductor layer provided inside the dielectric substrate, and a covering conductor layer covering the bottom surface and inner surface of a recess formed on the side of the dielectric substrate opposite to the mounting surface. The covering conductor layer is connected to the internal conductor layer exposed on the inner surface of the recess, and the thickness of the covering conductor layer is greater than the thickness of the internal conductor layer.

[0009] In the electrostatic chuck with the above configuration, a recess is formed to a depth that penetrates the internal conductor layer, and the internal conductor layer exposed on the inner surface of the recess is connected to the covering conductor layer that covers the bottom and inner surface of the recess. Compared to when a thin via is present in the middle of the circuit, the cross-sectional area of ​​the circuit is increased, so the amount of localized heat generated in the part connected to the internal conductor layer can be suppressed more than in conventional designs.

[0010] However, in the above configuration, a portion of the electrical circuit connected to the internal conductor layer, specifically the covering conductor layer covering the bottom surface of the recess, is located closer to the mounting surface compared to conventional vias. Therefore, there is concern that the Joule heat generated in this portion may adversely affect the in-plane temperature distribution of the substrate.

[0011] Therefore, in the electrostatic chuck with the above configuration, the thickness of the coating conductor layer is made greater than the thickness of the internal conductor layer, thereby reducing the overall electrical resistance of the coating conductor layer. As a result, the amount of heat generated at positions close to the mounting surface (for example, the bottom surface of the recess) is further suppressed, and variations in the in-plane temperature distribution of the substrate during processing can be suppressed. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an electrostatic chuck that can suppress variations in the in-plane temperature distribution of a substrate during processing. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic cross-sectional view showing the configuration of the electrostatic chuck according to the first embodiment. [Figure 2] This figure shows the configuration of the part of the electrostatic chuck according to the first embodiment that receives power from an external source. [Figure 3] This figure shows the configuration of the part of the electrostatic chuck that receives power from an external source, according to a modified example of the first embodiment. [Figure 4] This figure shows the configuration of the part of the electrostatic chuck according to the second embodiment that receives power from an external source. [Figure 5] This diagram shows the configuration of the part of the electrostatic chuck relating to the comparative example that receives power from an external source. [Modes for carrying out the invention]

[0014] This embodiment will now be described with reference to the attached drawings. To facilitate understanding of the explanation, the same reference numerals are used for identical components in each drawing whenever possible, and redundant explanations are omitted.

[0015] A first embodiment will be described. The electrostatic chuck 10 according to this embodiment is used to attract and hold a substrate W to be processed by electrostatic force inside a semiconductor manufacturing apparatus (not shown), such as an etching apparatus. The substrate W to be attracted is, for example, a silicon wafer. The electrostatic chuck 10 may also be used in apparatus other than semiconductor manufacturing apparatus.

[0016] Figure 1 shows a schematic cross-sectional view of the electrostatic chuck 10 in a state where the substrate W is adsorbed and held. The electrostatic chuck 10 comprises a dielectric substrate 100 and a base plate 200.

[0017] The dielectric substrate 100 is a substantially disc-shaped component made of a ceramic sintered body. The dielectric substrate 100 contains, for example, high-purity aluminum oxide (Al2O3), but may also contain other materials. The purity and type of ceramics in the dielectric substrate 100, as well as the additives, can be appropriately set considering the plasma resistance and other properties required of the dielectric substrate 100 in semiconductor manufacturing equipment.

[0018] The upper surface 110 of the dielectric substrate 100 in Figure 1 is the "mounting surface" on which the substrate W is placed. The opposite surface 120 of the dielectric substrate 100 (the lower side in Figure 1) is the "bonded surface" that is bonded to the base plate 200 via the bonding layer 300. The viewpoint from which the electrostatic chuck 10 is viewed from the surface 110 side, along a direction perpendicular to surface 110, will also be referred to as the "top view" below.

[0019] An adsorption electrode 130 is embedded inside the dielectric substrate 100. The adsorption electrode 130 is a thin flat plate-like layer formed of a metal material containing palladium, and is arranged to be parallel to the surface 110. As the material of the adsorption electrode 130, in addition to palladium, molybdenum, platinum, tungsten, etc. may also be used. When a voltage is applied to the adsorption electrode 130 from the outside via a power supply path (not shown), an electrostatic force is generated between the surface 110 and the substrate W, whereby the substrate W is adsorbed and held. As the configuration of the above power supply path, for example, various known configurations can be adopted. The adsorption electrode 130 may be provided only one as a so-called "unipolar" electrode as in this embodiment, or may be provided two as a so-called "bipolar" electrode.

[0020] Inside the dielectric substrate 100, in addition to the above adsorption electrode 130, an RF electrode 140 is also embedded. The RF electrode 140 is provided as one of a pair of opposing electrodes for generating plasma in a semiconductor manufacturing apparatus. The other of the opposing electrodes is provided at a position above the electrostatic chuck 10 in the semiconductor manufacturing apparatus. When a high-frequency alternating voltage is applied between these opposing electrodes, plasma is generated above the substrate W and is used for processes such as film formation and etching on the substrate W.

[0021] The RF electrode 140 is, like the adsorption electrode 130, a thin flat plate-like layer formed of a metal material containing palladium. As the material of the RF electrode 140, in addition to palladium, molybdenum, platinum, tungsten, etc. may also be used. The RF electrode 140 is embedded at a position closer to the surface 120 side than the adsorption electrode 130. The RF electrode 140 is arranged to be parallel to the surface 110, like the adsorption electrode 130. The RF electrode 140 is a substantially circular single electrode in a top view. The RF electrode 140 corresponds to the "internal conductor layer" in this embodiment.

[0022] Power is supplied to the RF electrode 140 from an external power source via a contact probe 400. The contact probe 400 is a rod-shaped conductive member electrically connected to an external power source (not shown). There may be only one or more contact probes 400 connected to the dielectric substrate 100. A recess 150 is formed on the surface 120 of the dielectric substrate 100 to receive the tip of the contact probe 400. The specific configuration of the recess 150 and its vicinity will be described later.

[0023] A space SP is formed between the dielectric substrate 100 and the substrate W. When etching or other processes are performed in the semiconductor manufacturing apparatus, helium gas for temperature control is supplied to the space SP from the outside through a gas hole (not shown). By interposing helium gas between the dielectric substrate 100 and the substrate W, the thermal resistance between them is adjusted, thereby maintaining the temperature of the substrate W at an appropriate temperature. Note that the gas supplied to the space SP for temperature control may be a different type of gas than helium.

[0024] A sealing ring 111 and dots 112 are provided on the mounting surface 110, and the above-mentioned space SP is formed around them.

[0025] The seal ring 111 is a wall that partitions the space SP at its outermost position. The upper end of the seal ring 111 is part of the surface 110 and contacts the substrate W. Multiple seal rings 111 may be provided to divide the space SP. This configuration allows for individual adjustment of the helium gas pressure in each space SP, making the surface temperature distribution of the substrate W more uniform during processing.

[0026] In Figure 1, the portion labeled "116" is the bottom surface of the space SP. Hereafter, this portion will also be referred to as "bottom surface 116". The seal ring 111, along with the dot 112 described below, is formed as a result of excavating a portion of the surface 110 down to the position of the bottom surface 116.

[0027] The dots 112 are circular protrusions that extend from the bottom surface 116. Multiple dots 112 are provided and are distributed approximately evenly on the mounting surface of the dielectric substrate 100. The upper end of each dot 112 is part of the surface 110 and contacts the substrate W. By providing multiple such dots 112, the bending of the substrate W is suppressed.

[0028] The base plate 200 is a substantially disc-shaped member that supports the dielectric substrate 100. The base plate 200 is made of a metallic material such as aluminum. The base plate 200 is bonded to the surface 120 of the dielectric substrate 100 via a bonding layer 300. Of the base plate 200, the upper surface 210 in Figure 1 is the "bonded surface" that is bonded to the dielectric substrate 100.

[0029] The bonding layer 300 is a layer provided between the dielectric substrate 100 and the base plate 200, and it bonds the two together. The bonding layer 300 is made by curing an adhesive made of an insulating material. In this embodiment, a silicone adhesive is used as the adhesive. However, the bonding layer 300 may be made by curing another type of adhesive. In any case, it is preferable to use a material with the highest possible thermal conductivity for the bonding layer 300 so that the thermal resistance between the dielectric substrate 100 and the base plate 200 is reduced.

[0030] An insulating film may be formed on the surface of the base plate 200. As the insulating film, for example, an alumina film formed by thermal spraying can be used. By covering the surface of the base plate 200 with an insulating film, the dielectric strength of the base plate 200 can be increased.

[0031] A refrigerant channel 250 is formed inside the base plate 200 for passing a refrigerant. When etching or other processes are performed in the semiconductor manufacturing equipment, a refrigerant is supplied from the outside to the refrigerant channel 250, thereby cooling the base plate 200. During processing, the heat generated in the substrate W is transferred to the refrigerant via the helium gas in the space SP, the dielectric substrate 100, and the base plate 200, and is discharged to the outside together with the refrigerant. The supply and discharge of refrigerant to and from the refrigerant channel 250 is performed through an opening (not shown) formed on the surface 220 of the base plate 200 opposite to the surface 210.

[0032] A through-hole 260 is formed in the base plate 200 at a position that overlaps with the recess 150 when viewed from above. The through-hole 260 is provided for inserting the contact probe 400 described above, and is formed to penetrate the base plate 200 perpendicularly from surface 210 to surface 220. A cylindrical member may be placed between the inner surface of the through-hole 260 and the contact probe 400 to prevent discharge from occurring between them.

[0033] Figure 2 shows an enlarged view of the electrostatic chuck 10 shown in Figure 1, specifically the portion that receives external power supply to the RF electrode 140, namely the recess 150 and its vicinity.

[0034] The recess 150 is a bottomed hole formed by receding a portion of the surface 120 of the dielectric substrate 100 toward the surface 110. The shape of the recess 150 in a top view is circular. Of the inner surface of the recess 150, the bottom surface of the recess 150 (i.e., the end facing the surface 110) will hereafter be referred to as the "bottom surface 151". Also, of the inner surface of the recess 150, the inner surface will hereafter be referred to as the "inner surface 152".

[0035] The height of the bottom surface 151 is on the surface 110 side (upward side in Figure 2) of the RF electrode 140. In other words, the recess 150 is formed to a depth that penetrates the RF electrode 140. As a result, the RF electrode 140 is exposed in an annular shape on the inner surface 152 of the recess 150.

[0036] The entire inner surface of the recess 150 is covered by a covering conductor layer 160. The covering conductor layer 160 is, for example, made by adding titanium to silver solder, and can be directly brazed to the surface of the dielectric substrate 100, which is a ceramic. In addition to silver and titanium, the covering conductor layer 160 may also contain copper or the like. The portion of the covering conductor layer 160 that covers the bottom surface 151 of the recess 150 will hereafter be referred to as the "first covering conductor layer 161". The portion of the covering conductor layer 160 that covers the inner surface 152 of the recess 150 will hereafter be referred to as the "second covering conductor layer 162".

[0037] The second insulating conductor layer 162 is electrically connected to the RF electrode 140 exposed on the inner surface 152 of the recess 150. Therefore, the first insulating conductor layer 161, which is integrated with the second insulating conductor layer 162, is also electrically connected to the RF electrode 140.

[0038] The contact probe 400 is inserted into the recess 150 from the lower side in Figures 1 and 2, and its tip 411 is brought into contact with the first coating conductor layer 161. As a result, the power supplied from the outside via the contact probe 400 flows through the first coating conductor layer 161 along arrow AR1, through the second coating conductor layer 162 along arrow AR2, and then supplied to the RF electrode 140 along arrow AR3.

[0039] The thickness of the RF electrode 140 is, for example, about 15 μm to 20 μm. The thickness of the covering conductor layer 160 is, for example, about 30 μm to 50 μm.

[0040] In this embodiment, the coating conductor layer 160 is provided such that the thickness T21 of the first coating conductor layer 161 and the thickness T22 of the second coating conductor layer 162 are both thicker than the thickness T1 of the RF electrode 140.

[0041] To explain the advantages of the above configuration, the configuration of the comparative example shown in Figure 5 will be described. In this comparative example, the height position of the bottom surface 151 of the recess 150 is at a height position that is on the side of surface 120 (downward side in Figure 5) than the RF electrode 140. In other words, the recess 150 in this comparative example is not formed to a depth that reaches the RF electrode 140.

[0042] The covering conductor layer 160 is formed to cover only the bottom surface 151 of the recess 150. The powered member 170 is joined to the bottom surface 151 by the covering conductor layer 160, which is a brazing material. The powered member 170 is a disc-shaped metal member formed from, for example, a material containing molybdenum, and is positioned to cover substantially the entire bottom surface 151. The tip 411 of the contact probe 400 abuts against this powered member 170.

[0043] The insulating conductor layer 160 and the RF electrode 140 are electrically connected by a plurality of vias 165. Each via 165 is an electrical circuit formed by filling a narrow hole, which is formed to extend perpendicular to the surface 110, with a metal such as palladium.

[0044] With this configuration, power supplied from the outside via the contact probe 400 can be supplied to the RF electrode 140 via the powered member 170, the covering conductor layer 160, and the via 165.

[0045] However, since via 165 is a thin conductor, its electrical resistance is relatively high. Therefore, in the configuration of this comparative example, there is a possibility that localized heat generation may occur in the area of ​​via 165. As a result, there is a possibility that the in-plane temperature distribution of the substrate W during processing will become more variable.

[0046] Therefore, in the electrostatic chuck 10 according to this embodiment, as explained with reference to Figure 2, a recess 150 is formed to a depth that penetrates the RF electrode 140, and the inner surface of the recess 150 is covered with a covering conductor layer 160, thereby forming an electrical circuit connected to the RF electrode 140.

[0047] Compared to the comparative example configuration in which via 165 is used as part of the circuit, the configuration of this embodiment allows for a larger cross-sectional area of ​​the circuit, thereby suppressing localized heat generation in the portion connected to the RF electrode 140.

[0048] However, in the configuration of this embodiment, a portion of the circuit connected to the RF electrode 140, specifically the first covering conductor layer 161 covering the bottom surface 151 of the recess 150, is located closer to the mounting surface compared to the via 165 of the comparative example. Therefore, there is concern that the Joule heat generated in the first covering conductor layer 161 may adversely affect the in-plane temperature distribution of the substrate W.

[0049] Therefore, in this embodiment, the thickness (T21, T22) of the coating conductor layer 160 is made greater than the thickness T1 of the RF electrode 140, thereby reducing the overall electrical resistance of the coating conductor layer 160. As a result, the amount of heat generated near the mounting surface is further suppressed, and variations in the in-plane temperature distribution of the substrate W during processing can be suppressed.

[0050] The thickness T21 of the first covering conductor layer 161 and the thickness T22 of the second covering conductor layer 162 may be the same or different. In either case, it is sufficient that the thickness of each part of the covering conductor layer 160 is greater than the thickness of the internal conductor layer, which is the RF electrode 140. More preferably, the thickness of each part of the covering conductor layer 160 is 1.5 times or more the thickness of the RF electrode 140.

[0051] The portion of the covering conductor layer 160 that covers the bottom surface 151 is the part to which physical external force is applied by the contact probe 400. Therefore, if the surface roughness of the bottom surface 151 is made rougher, the adhesion force of the first covering conductor layer 161 to the bottom surface 151 will increase, thereby improving the durability of the first covering conductor layer 161 against external force.

[0052] On the other hand, if the surface roughness of the inner surface 152 is made too rough, there is a possibility that the electrical connection between the RF electrode 140 and the second coating conductor layer 162 cannot be secured. For this reason, by making the inner surface 152 a smooth surface, the electrical connection between the RF electrode 140 and the second coating conductor layer 162 can be reliably secured.

[0053] For the reasons stated above, it is preferable to make the surface roughness of the bottom surface 151 of the recess 150 (e.g., arithmetic mean roughness Ra or maximum height Rz) rougher than the surface roughness of the inner surface 152 of the recess 150.

[0054] Palladium is known to readily form alloys with silver, forming strong bonds. As in this embodiment, by selecting materials such that the RF electrode 140 contains palladium and the coating conductor layer 160 contains silver, adhesion between the RF electrode 140 and the coating conductor layer 160 can be ensured.

[0055] The internal conductive layer powered by the contact probe 400 may be the RF electrode 140 as in this embodiment, but it may also be another layer. For example, it may be a conductive layer embedded inside the dielectric substrate 100, serving as a heater for heating the dielectric substrate 100.

[0056] A modified version of this embodiment will be described with reference to Figure 3. In this modified version, the contact probe 400 is provided as one of the components constituting the electrostatic chuck 10. Power is supplied from an external power source to the RF electrode 140 by bringing a contact pin (not shown) into contact with the end face 421 of the contact probe 400 opposite to the tip 411 from the outside. In the following, the differences from the first embodiment will be mainly described, and the points common to the first embodiment will be omitted as appropriate.

[0057] The electrostatic chuck 10 according to this modified example comprises a first member 500, a second member 600, and a third member 700. The contact probe 400 is held inside the through hole 260 by these members. The contact probe 400 has a large-diameter portion 410 on the surface 210 side and a small-diameter portion 420 on the surface 220 side. The outer diameter of the large-diameter portion 410 is larger than the outer diameter of the small-diameter portion 420.

[0058] The first member 500 is a substantially cylindrical member positioned to cover the inner surface of the through hole 260. The first member 500 is made of an insulating material, such as resin.

[0059] The portion of the through hole 260 facing the surface 220 is enlarged in diameter. This enlarged portion will also be referred to as the "enlarged diameter portion 261" below. A female screw 262 is formed on the inner surface of the enlarged diameter portion 261. The first member 500 covers the entire inner surface of the through hole 260, excluding the enlarged diameter portion 261. The first member 500 is fixed to the inner surface of the through hole 260, for example, by adhesive.

[0060] In the example shown in Figure 3, the portion of the through-hole 260 facing the surface 210 is also enlarged in diameter, and accordingly, the portion of the first member 500 facing the surface 210 is similarly enlarged in diameter. The first member 500 may be divided into two parts with different diameters.

[0061] The second member 600 is a substantially cylindrical member that surrounds the contact probe 400 from the outer circumference and is positioned inside the first member 500. The second member 600 is made of an insulating material such as resin. The second member 600 has a large-diameter portion 610 on the side facing surface 210 and a small-diameter portion 620 on the side facing surface 220. The outer diameter of the large-diameter portion 610 is larger than the outer diameter of the small-diameter portion 620 and is approximately equal to the inner diameter of the first member 500. The inner diameters of both the large-diameter portion 610 and the small-diameter portion 620 are approximately equal to the outer diameter of the small-diameter portion 420 of the contact probe 400.

[0062] A spring 450 is positioned around the small-diameter portion 420 of the contact probe 400. The end of the spring 450 on the surface 210 side is in contact with the large-diameter portion 410 of the contact probe 400. The end of the spring 450 on the surface 220 side is in contact with the large-diameter portion 610 of the second member 600. In Figure 3, the spring 450 is sandwiched between the large-diameter portions 410 and 610 and is compressed vertically to be shorter than its natural length. The restoring force of the spring 450 biases the contact probe 400 upwards in Figure 3. In other words, the tip 411 of the contact probe 400 is pressed against the first coating conductor layer 161.

[0063] The third member 700 is a substantially cylindrical member that surrounds the small-diameter portion 620 of the second member 600 from the outside. The third member 700 is made of an insulating material such as resin. The third member 700 has a small-diameter portion 710 on the side facing surface 210 and a large-diameter portion 720 on the side facing surface 220. A male screw 722 is formed on the outer circumferential surface of the large-diameter portion 720. The male screw 722 is screwed into a female screw 262 formed on the inner surface of the through hole 260. Therefore, when the third member 700 is rotated around its central axis, the third member 700 moves in the vertical direction in Figure 3.

[0064] The outer diameter of the small-diameter portion 710 is approximately equal to the inner diameter of the first member 500. The inner diameter of both the small-diameter portion 710 and the inner diameter of the large-diameter portion 720 are approximately equal to the outer diameter of the small-diameter portion 620 of the second member 600. The upper end of the small-diameter portion 710 is inserted between the first member 500 and the second member 600, and is in contact with the large-diameter portion 610 of the second member 600 from below.

[0065] In this configuration, discharge between the base plate 200 and the contact probe 400 is prevented by the first member 500, the second member 600, and the third member 700. Furthermore, by rotating the third member 700 around its central axis and moving it in the vertical direction in Figure 3, the force with which the contact probe 400 is pressed against the first coated conductor layer 161 can be adjusted.

[0066] The second embodiment will now be described. The following will primarily focus on the differences from the first embodiment, while common points will be omitted as appropriate.

[0067] Figure 4 shows an enlarged view, similar to Figure 2, of the electrostatic chuck 10 according to this embodiment, specifically the portion that receives external power supply to the RF electrode 140, i.e., the recess 150 and its vicinity. In this embodiment, a powered member 170, similar to the comparative example in Figure 5, is joined to the bottom surface 151 of the recess 150 via the first covering conductor layer 161. The tip 411 of the contact probe 400 is in contact with the powered member 170.

[0068] In this configuration, the powered member 170 can also be considered as part of the covering conductor layer 160 that covers the inner surface of the recess 150. In this case, the thickness T23 of the portion of the covering conductor layer 160 that covers the bottom surface 151 of the recess 150 is greater than the thickness T1 of the RF electrode 140 and even greater than the thickness T22 of the second covering conductor layer 162. By making the portion of the covering conductor layer 160 that the tip 411 of the contact probe 400 contacts (i.e., the portion that is prone to wear) thicker, it is possible to ensure that the function of the covering conductor layer 160 is maintained for a long period of time.

[0069] Furthermore, in the configuration of the first embodiment shown in Figure 2, the same effect as described above can be achieved by making the thickness T21 of the first covering conductor layer 161 greater than the thickness T22 of the second covering conductor layer 162.

[0070] The embodiments have been described above with reference to specific examples. However, this disclosure is not limited to these specific examples. Modifications made to these specific examples by those skilled in the art are also included within the scope of this disclosure, as long as they retain the features of this disclosure. The elements, their arrangement, conditions, shapes, etc., of each of the aforementioned specific examples are not limited to those illustrated and can be modified as appropriate. The elements of each of the aforementioned specific examples can be combined in different ways as appropriate, as long as no technical inconsistencies arise. [Explanation of symbols]

[0071] 10: Electrostatic Chuck 100: Dielectric substrate 110,120: face 140:RF electrode 150: Recess 151: Bottom 152: Inner surface 160: Insulated conductor layer 161: First insulating conductor layer 162: Second insulating conductor layer W: Circuit board

Claims

1. A dielectric substrate having a mounting surface on which an object to be adsorbed is placed, An internal conductive layer provided inside the dielectric substrate, The dielectric substrate comprises a covering conductive layer that covers the bottom surface and inner surface of a recess formed on the surface opposite to the surface described above, The covering conductor layer is connected to the inner conductor layer that is exposed on the inner surface of the recess. An electrostatic chuck characterized in that the thickness of the covering conductor layer is greater than the thickness of the internal conductor layer.

2. The electrostatic chuck according to claim 1, characterized in that the thickness of the covering conductor layer is 1.5 times or more the thickness of the inner conductor layer.

3. The electrostatic chuck according to claim 1, characterized in that the thickness of the portion of the covering conductor layer that covers the bottom surface of the recess is greater than the thickness of the portion of the covering conductor layer that covers the inner surface of the recess.

4. The electrostatic chuck according to claim 1, characterized in that the surface roughness of the bottom surface of the recess is rougher than the surface roughness of the inner surface of the recess.

5. The electrostatic chuck according to claim 1, characterized in that the internal conductive layer contains palladium.

6. The electrostatic chuck according to any one of claims 1 to 5, characterized in that the covering conductor layer contains silver.

Images