Electrostatic chuck member and electrostatic chuck device

Abstract

To provide an electrostatic chuck member which can be made into an electrostatic chuck device with high thermal uniformity, and provide an electrostatic chuck device which comprises such an electrostatic chuck member and of which thermal uniformity is high.SOLUTION: An electrostatic chuck member comprises: a substrate of which the top face is a mounting surface to mount a tabular specimen thereon; and an electrode for electrostatic adsorption provided on a surface of the substrate on an opposite side of the mounting surface or inside of the substrate. The substrate includes: an annular projection which protrudes upward and is provided in a closed annular shape along an edge of the top face; and a plurality of projections provided while protruding upward inside of the annular projection. An outer peripheral part of the electrode for electrostatic adsorption overlaps the annular projection in a planar view, and a top face of the annular projection on an outer peripheral side is higher than that on an inner peripheral side and tilted with respect to a top face of a reference projection closest to the annular projection in the plurality of projections.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electrostatic chuck member and an electrostatic chuck device. [Background technology]

[0002] Semiconductor manufacturing equipment that performs plasma processes uses an electrostatic chuck device that can easily attach and secure a plate-shaped sample (wafer) to a sample stage and maintain the wafer at a desired temperature. The electrostatic chuck device includes an electrostatic chuck member (plate-shaped ceramic body) that has a base body, one main surface of which is a mounting surface on which the wafer is placed, and an electrostatic attraction electrode that generates an electrostatic force (Coulomb force) between the base body and the wafer placed on the mounting surface (see, for example, Patent Document 1). The base body is usually made of a ceramic sintered body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-270084 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a trend toward higher integration of semiconductor devices. Therefore, microfabrication technology for wiring and three-dimensional packaging technology are required when manufacturing these devices. To implement these processing technologies, semiconductor manufacturing equipment is required to reduce the temperature distribution (temperature difference) within the wafer surface.

[0005] However, conventional techniques sometimes fail to reduce the temperature difference within the wafer surface to within a desired range, and improvements have been sought.

[0006] In this specification, the degree of temperature difference within the surface of a wafer held by an electrostatic chuck device during plasma processing is sometimes referred to as "thermal uniformity." Also, a small temperature difference within the surface of a wafer during plasma processing is sometimes referred to as "good thermal uniformity."

[0007] The present invention has been made in view of the above circumstances, and has an object to provide an electrostatic chuck member that can be used to form an electrostatic chuck device with good thermal uniformity. Another object of the present invention is to provide an electrostatic chuck device with good thermal uniformity that includes such an electrostatic chuck member. [Means for solving the problem]

[0008] A known electrostatic chuck device has a configuration in which an annular protrusion (seal band) that is closed in plan view around the periphery of a base body is provided, and a gaseous coolant (e.g., helium) is supplied to the area surrounded by the annular protrusion. In such an electrostatic chuck device, the wafer is in contact with the upper surface of the annular protrusion, and the coolant flows in the space between the wafer and the annular protrusion on the substrate, thereby cooling the wafer and reducing the temperature difference across the wafer surface, making it possible to maintain the wafer at a desired temperature.

[0009] In a wafer processed by an electrostatic chuck device having the above configuration, the peripheral edge of the wafer in contact with the annular convex portion is not in contact with the coolant and is therefore insufficiently cooled, which tends to result in a temperature difference between the peripheral edge and the portion not in contact with the annular convex portion (the portion exposed to the coolant).In order to reduce the area where such a temperature difference occurs and to effectively utilize the peripheral edge of the wafer, it is conceivable to narrow the width of the annular convex portion as much as possible.

[0010] On the other hand, the electrostatic attraction electrode of an electrostatic chuck member typically does not extend to the side surface of the electrostatic chuck member in a plan view. As a result, the wafer attraction force at the peripheral portion of the electrostatic chuck member tends to be weaker than at the center of the electrostatic chuck member in a plan view. Therefore, at the peripheral portion of the electrostatic chuck member, the pressure of the refrigerant flowing through the grooves can cause the wafer to lift up from the electrostatic chuck member, resulting in leakage of the refrigerant. As a result of research conducted by the inventors, it was found that narrowing the width of the annular convex portion makes it easier for the refrigerant to leak from the peripheral portion of the electrostatic chuck member, reducing the wafer cooling efficiency and thermal uniformity.

[0011] As a result of intensive research conducted by the inventors based on the above findings, it was found that the leakage of coolant that occurs at the peripheral edge portion of the electrostatic chuck member can be suppressed by controlling the shape of the annular convex portion, and thus the present invention was completed.

[0012] In order to solve the above problems, one aspect of the present invention includes the following aspects.

[0013] [1] An electrostatic chuck member comprising: a base whose upper surface is a mounting surface on which a plate-shaped sample is placed; and an electrostatic adsorption electrode provided on the surface of the base opposite the mounting surface or inside the base, wherein the base has an annular convex portion that protrudes upward along the edge of the upper surface and is provided in a closed ring shape, and a plurality of convex portions that protrude upward inside the annular convex portion, the upper surface of the annular convex portion being higher on the outer periphery than on the inner periphery and inclined relative to the upper surface of a reference convex portion that is closest to the annular convex portion among the plurality of convex portions, the width of the annular convex portion being 0.1 mm or more and 4.0 mm or less, and the inclination angle of the upper surface of the annular convex portion relative to the upper surface of the reference convex portion being greater than 0° and not more than 3°.

[0014] [2] The electrostatic chuck member according to [1], wherein the plurality of convex portions form a plurality of convex portion groups arranged concentrically with the annular convex portion, and the convex portion included in the convex portion group closest to the annular convex portion among the plurality of convex portion groups is the reference convex portion.

[0015] [3] An electrostatic chuck device comprising the electrostatic chuck member according to [1] or [2].

[0016] [4] The electrostatic chuck device according to [3], wherein the base has a concave shape in a cross section in the thickness direction of the base, the height of which gradually increases from the center of the mounting surface toward the outer periphery of the mounting surface.

[0017] [5] The electrostatic chuck device according to [3], wherein the base has a convex shape in a cross section in the thickness direction of the base, the height of which gradually decreases from the center of the mounting surface toward the outer periphery of the mounting surface. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide an electrostatic chuck member that can be used to form an electrostatic chuck device with good thermal uniformity. Furthermore, it is possible to provide an electrostatic chuck device with good thermal uniformity that includes such an electrostatic chuck member. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an electrostatic chuck device 1A according to an embodiment. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing the configuration of the peripheral edge portion of the electrostatic chuck member 2A. [Figure 3] FIG. 3 is an explanatory diagram illustrating the effects of the electrostatic chuck device 1A of this embodiment. [Figure 4] FIG. 4 is an explanatory diagram illustrating the effects of the electrostatic chuck device 1A of this embodiment. [Figure 5] FIG. 5 is a schematic cross-sectional view showing a modification of this embodiment. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a modification of this embodiment. [Figure 7] FIG. 7 is an enlarged cross-sectional view showing the configuration of the peripheral edge portion of an electrostatic chuck member 2B according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0020] An electrostatic chuck member and an electrostatic chuck device according to this embodiment will be described below with reference to Figures 1 to 6. Note that in all the following figures, the dimensions and proportions of the components are appropriately changed to make the drawings easier to understand.

[0021] <Electrostatic chuck member, electrostatic chuck device> 1 is a schematic cross-sectional view showing an electrostatic chuck device 1A according to this embodiment. The electrostatic chuck device 1A includes an electrostatic chuck member 2A, a base 3, and an adhesive layer 4. The electrostatic chuck member 2A and the base 3 are stacked together with the adhesive layer 4 interposed therebetween.

[0022] In this specification, the side of the base 3 on which the electrostatic chuck member 2A is placed may be referred to as "upper," and the opposite side may be referred to as "lower." In the following description, each part of the electrostatic chuck device 1A will be described with the vertical direction as the stacking direction. However, the vertical direction here is used merely for the sake of simplicity of description and does not limit the position of the electrostatic chuck device 1A during use.

[0023] <Electrostatic chuck member> The electrostatic chuck member 2A includes a base 10A and an electrostatic attraction electrode 13. The base 10A has a circular plate shape in a plan view. The upper surface of the base 10A is a mounting surface 10a on which a wafer W is mounted. A focus ring surrounding the wafer W may be disposed outside the mounting surface 10a of the electrostatic chuck member 2A.

[0024] The base 10A includes a mounting plate 11A, a support plate 12, and an insulating material layer .

[0025] The mounting plate 11A and the support plate 12 are made of ceramics that have sufficient mechanical strength and durability against corrosive gases and their plasma.

[0026] The ceramics constituting the mounting plate 11A and the support plate 12 contain aluminum oxide (Al2O3) as a main component. "Main component" means that it accounts for 50% or more by volume of the entire material. For example, aluminum oxide (Al2O3) sintered compact, aluminum oxide (Al2O3)-silicon carbide (SiC) composite sintered compact, etc. are preferably used. In particular, from the viewpoints of dielectric properties at high temperatures, high corrosion resistance, plasma resistance, and heat resistance, Al2O3-SiC composite sintered compact is preferred as the material constituting the mounting plate 11A and the support plate 12.

[0027] The upper surface of the mounting plate 11A is provided with an annular protrusion 21 that protrudes upward along the edge of the upper surface of the mounting plate 11A and has a closed ring shape in a plan view. In this specification, the term "plan view" refers to a field of view seen from the thickness direction of the electrostatic chuck member 2A.

[0028] A plurality of protrusions 22 protruding upward are provided on the upper surface of the mounting plate 11A in an area inside the annular protrusion 21. The electrostatic chuck device 1A supports the wafer W on the upper surface of the annular protrusion 21 and the tip portions (upper surfaces) of the plurality of protrusions 22. That is, in the electrostatic chuck device 1A, an imaginary plane connecting the upper surface of the annular protrusion 21 and the upper surfaces of the plurality of protrusions 22 corresponds to the mounting surface 10a.

[0029] When a wafer W is placed on the mounting surface 10a, the space surrounded by the underside of the wafer W, the annular protrusion 21, and the plurality of protrusions 22 functions as a flow path C for flowing a cooling gas. The electrostatic chuck device 1A is provided with a gas supply hole (not shown) that penetrates the electrostatic chuck device 1A in the thickness direction, and the cooling gas is supplied from the gas supply hole to the flow path C. The cooling gas flowing through the flow path C cools the wafer W that is heated during plasma processing.

[0030] The plurality of protrusions 22 may form a plurality of protrusion groups arranged concentrically with the annular protrusion 21. For example, the two protrusions 22A closest to the annular protrusion 21 in the field of view of FIG. 1 constitute a protrusion group arranged in a ring shape concentrically with the annular protrusion 21 in a plan view. Similarly, the two protrusions 22B adjacent to the protrusion 22A constitute a protrusion group arranged concentrically with the protrusion group including the annular protrusion 21 and the protrusion 22A in a plan view. The remaining protrusions 22 may also similarly constitute protrusion groups and be arranged concentrically.

[0031] (electrode for electrostatic adsorption) The electrostatic attraction electrode 13 is disposed inside the base 10A and integrally bonds the mounting plate 11A and the support plate 12. In Fig. 1, the electrostatic attraction electrode 13 is provided inside the base, but the electrostatic attraction electrode 13 may also be provided on the surface of the base 10A opposite to the mounting surface (i.e., on the underside of the support plate 12).

[0032] The electrostatic attraction electrode 13 extends in a plate shape along the mounting surface 10a of the base 10A. When a voltage is applied to the electrostatic attraction electrode 13, it generates an electrostatic attraction force that holds the wafer W on the mounting surface 10a.

[0033] The electrostatic attraction electrode 13 is made of a composite of an insulating material and a conductive material. The insulating material contained in the electrostatic attraction electrode 13 is not particularly limited, but is preferably at least one selected from the group consisting of aluminum oxide (Al2O3), aluminum nitride (AlN), silicon nitride (Si3N4), yttrium (III) oxide (Y2O3), yttrium aluminum garnet (YAG), and SmAlO3.

[0034] The conductive material contained in the electrostatic attraction electrode 13 is preferably at least one selected from the group consisting of molybdenum carbide (MoC), molybdenum (Mo), tungsten carbide (WC), tungsten (W), tantalum carbide (TaC), tantalum (Ta), silicon carbide (SiC), carbon black, carbon nanotubes, and carbon nanofibers.

[0035] The thickness of the electrostatic chuck member 2A is preferably 0.5 mm or more and 5 mm or less. When the thickness of the electrostatic chuck member 2A is 0.5 mm or more, the withstand voltage of the electrostatic chuck member 2A is high. Furthermore, when the thickness of the electrostatic chuck member 2A is 5 mm or less, the heat capacity of the electrostatic chuck member 2A is small, making it easier to maintain a uniform temperature of the plate-shaped sample, which is the processing object, during plasma processing.

[0036] A power supply terminal 15 for applying a DC voltage to the electrostatic chucking electrode 13 is connected to the electrostatic chucking electrode 13. The power supply terminal 15 is a rod-shaped member provided for applying a DC voltage to the electrostatic chucking electrode 13. There are no particular limitations on the material of the power supply terminal 15 as long as it is a conductive material with excellent heat resistance. However, a material with a thermal expansion coefficient similar to that of the electrostatic chucking electrode 13 and the support plate 12 is preferred. For example, the conductive ceramics that constitute the electrostatic chucking electrode 13, or metal materials such as tungsten (W), tantalum (Ta), molybdenum (Mo), niobium (Nb), and Kovar alloy are preferably used.

[0037] The power supply terminal 15 is inserted into an insulating cylindrical insulator 16. The insulator 16 is inserted into a through-hole provided in the base 3 and is joined and integrated with the base 3. The power supply terminal 15 is inserted into a through-hole provided in the support plate 12 and the insulator 16, and is electrically joined to the electrostatic attraction electrode 13.

[0038] The insulating layer 14 is provided in a closed ring shape around the electrostatic attraction electrode 13. The insulating layer 14 protects the electrostatic attraction electrode 13 from the plasma used in the plasma process and the corrosive gas that is the plasma raw material. The insulating layer 14 also bonds and integrates the mounting plate 11A and the support plate 12 around the electrostatic attraction electrode 13.

[0039] The insulating layer 14 is made of an insulating material having the same composition or the same main component as the material that constitutes the mounting plate 11A and the support plate 12.

[0040] <Foundation> The base 3 is a disk-shaped member in a plan view, and supports the electrostatic chuck member 2A from below. An upper surface 3a of the base 3 faces the lower surface of the base body 10A in the vertical direction via an adhesive layer 4. The base 3 supports the electrostatic chuck member 2A on the upper surface 3a.

[0041] A flow path 31 for circulating a coolant is provided inside the base 3. The coolant flowing through the flow path 31 may be water, He gas, N2 gas, or the like. The flow path 31 extends along the upper surface 3a. The coolant in the flow path 31 cools the entire base 3 and also cools the electrostatic chuck member 2A via the upper surface 3a.

[0042] The base 3 is connected to an external high frequency power source via a matching box (not shown) and also serves as an internal electrode for generating plasma.

[0043] 2 is an enlarged cross-sectional view showing the configuration of the peripheral edge portion of the electrostatic chuck member 2 A. FIG. 2 is an enlarged view of the same cross section as FIG. 1, and shows the structure around the annular protrusion 21.

[0044] The electrostatic attraction electrode 13 is preferably provided so as to extend as close to the side surface of the base 10A as possible. On the other hand, if the width WA of the annular protrusion 21 is narrowed to effectively utilize the peripheral edge of the wafer W, the outer periphery 13x of the electrostatic attraction electrode 13 may not overlap with the annular protrusion 21 in a plan view. In the electrostatic chuck device 1A, as shown in FIG. 2, the outer periphery 13x of the electrostatic attraction electrode 13 does not overlap with the annular protrusion 21 in a plan view.

[0045] Even with the electrostatic chuck device 1A having such a configuration, the wafer W can be attracted to the annular protrusion 21 and made to come into close contact with it by controlling the shape of the upper surface 21a of the annular protrusion 21.

[0046] (Annular convex part) In the electrostatic chuck device 1A, the above problem is solved by setting the shape of the annular protrusion 21, namely, (a) the width of the annular protrusion 21 and (b) the inclination angle of the upper surface 21a of the annular protrusion 21, within appropriate ranges.

[0047] (a) Width of the annular protrusion 21 The annular protrusion 21 is formed to have the same width over the entire circumferential range. The width of the annular protrusion 21 refers to the radial length of the annular protrusion 21 in a plan view.

[0048] The width WA of the annular protrusion 21 is 0.1 mm or more and 4.0 mm or less. The width WA of the annular protrusion 21 may be 0.5 mm or more, 1.0 mm or more, or 1.5 mm or more. The width WA of the annular protrusion 21 may be 3.5 mm or less, 3.0 mm or less, 2.5 mm or less, or 2.0 mm or less.

[0049] The upper and lower limits of the width WA of the annular protrusion 21 can be arbitrarily combined. For example, the width WA may be 0.3 mm or more and 4.0 mm or less, or 0.5 mm or more and 2.0 mm or less.

[0050] By setting the width of the annular protrusion 21 to 4.0 mm or less, the flow path C can be formed relatively wide, and the cooling gas can effectively cool the wafer W up to the peripheral portion of the wafer W. This enables the electrostatic chuck device 1A to appropriately control the temperature up to the peripheral portion of the wafer W, and it is expected that the state of plasma processing (etching) in the peripheral portion of the wafer W will be stable and the yield will be improved.

[0051] Furthermore, by setting the width WA of the annular protrusion 21 to 0.1 mm or more, it becomes possible to adsorb the wafer W onto the upper surface 21a and seal the cooling gas in the flow path C. As an example, the width WA of the annular protrusion 21 can be set to 2 mm.

[0052] (b) Inclination angle of the upper surface 21a of the annular protrusion 21 The upper surface 21a of the annular protrusion 21 is formed so that the outer periphery is higher than the inner periphery. Furthermore, the upper surface 21a is inclined relative to the upper surface 22a of the protrusion 22A that is closest to the annular protrusion 21. The upper surface 21a of the annular protrusion 21 is an inclined surface that is lower on the inside and higher on the outside over the entire circumference in the circumferential direction.

[0053] In Figure 2, the inner upper end 211 of the annular protrusion 21 (the inner end of the upper surface 21a) is at the same height as the upper surface 22a of the protrusion 22A, and the outer upper end 212 of the annular protrusion 21 (the outer end of the upper surface 21a) is located higher than the upper surface 22a of the protrusion 22A.

[0054] The protrusion 22A corresponds to the "reference protrusion" in the present invention. That is, among the plurality of protrusion groups that the base 10A has, the protrusion 22 included in the protrusion group that is closest to the annular protrusion 21 can be used as the "reference protrusion" when discussing the inclination of the upper surface 21a of the annular protrusion 21.

[0055] The inclination angle θ of the upper surface 21a of the annular protrusion 21 is the angle formed between the upper surface 21a and the upper surface 22a of the protrusion 22A, which is the reference protrusion. The inclination angle θ of the upper surface 21a of the annular protrusion 21 is greater than 0° and not greater than 3°. The inclination angle θ may be 0.01° or greater, or may be 1° or greater. The inclination angle θ may also be 2° or less, or may be 2.5° or less.

[0056] The upper and lower limits of the tilt angle θ can be arbitrarily combined. The tilt angle may be 0.01° or more and 3° or less, or 0.01° or more and 1.8° or less.

[0057] The inclination angle θ of the upper surface 21a can be determined by measuring the width WA and the difference A in height between the upper end 211 and the upper end 212 using a measuring device (for example, a surface roughness / contour shape composite measuring device (product name: SURFCOM NEX, manufactured by Tokyo Seimitsu Co., Ltd.)) and calculating the arc tangent of A / WA.

[0058] Typically, when grinding the upper surface of the base 10A (mounting plate 11A), a rotary grindstone is moved in the surface direction of the upper surface of the base 10A while being pressed against the base 10A. Furthermore, by rotating the base 10A around the central axis of the base 10A, the upper surface is ground while changing the grinding position in the circumferential direction.

[0059] In such processing, the peripheral edge of the base 10A may be ground while the grinding wheel is protruding outward from the top surface of the base 10A. When the grinding wheel is protruding outward from the top surface of the base 10A in this way, the pressure applied to the base 10A by the grinding wheel is increased compared to when grinding the inner side of the base 10A in a planar view, making it easier to grind the base 10A. As a result, the peripheral edge of the base 10A tends to be lower than the inner side of the base 10A in a planar view.

[0060] In contrast, when manufacturing the electrostatic chuck member 2A of this embodiment, the pressure with which the grindstone is pressed is set relatively smaller on the periphery of the base 10A than on the inside of the base 10A. This allows the upper surface 21a of the annular protrusion 21 to be an inclined surface. It is advisable to set the processing conditions by conducting a preliminary experiment.

[0061] 3 and 4 are explanatory diagrams illustrating the effects of the electrostatic chuck device 1A of the present embodiment, and are diagrams corresponding to Fig. 2. Figs. 3 and 4 illustrate the difference in effect due to the difference in the inclination of the upper surface of the annular convex portion.

[0062] 3 has an annular convex portion 29 whose upper surface is an inclined surface that is higher on the inside and lower on the outside. The electrostatic chuck device 1X has the same configuration as the electrostatic chuck device 1A described above except for the shape of the annular convex portion 29 (the inclination angle of the upper surface), and will be described using the same reference numerals as those of the electrostatic chuck device 1A.

[0063] A wafer W is placed on the mounting surface 10a of the electrostatic chuck device 1X, and a voltage is applied to the electrostatic attraction electrode 13. As a result, the electrostatic chuck device 1X generates an electrostatic attraction force F1 that attracts the wafer W toward the electrostatic chuck member 2X, and attracts the wafer W to the mounting surface 10a.

[0064] At this time, the peripheral edge WE of the wafer W overlaps the annular protrusion 29 in plan view. However, because the upper surface 29a of the annular protrusion 29 has a low inclined surface on the outer side, the peripheral edge WE is likely to lift up from the upper surface 29a (indicated by the symbol α in the figure). Furthermore, if the width of the annular protrusion 29 is narrowed to effectively utilize the peripheral edge of the wafer W, the contact area between the wafer W and the annular protrusion 29 becomes smaller, which makes it easier for the cooling gas flowing through the flow path C to leak. Therefore, heat dissipation to the electrostatic chuck member 2X is hindered in the peripheral edge WE, making temperature control difficult.

[0065] 4, when a wafer W is placed on the mounting surface 10a of the electrostatic chuck device 1A and a voltage is applied to the electrostatic attraction electrode 13, the electrostatic chuck device 1A similarly generates an electrostatic attraction force F1 to attract the wafer W to the mounting surface 10a. At this time, the wafer W is attracted to the upper surface 22a of the protrusion 22A, and is attracted to the upper surface 21a of the annular protrusion 21 while bending downward because the upper surface 21a is an inclined surface with a higher outer side.

[0066] As a result, a restoring force F2 occurs at the peripheral edge WE of the wafer W when the elastically deformed wafer W recovers. The restoring force F2 presses the wafer W against the electrostatic chuck member 2A, bringing the lower surface of the wafer W into close contact with the upper surface 21a of the annular protrusion 21.

[0067] As described above, the inclination angle θ of the upper surface 21a of the annular protrusion 21 is greater than 0° and not greater than 3°. When the inclination angle θ is greater than 0° (i.e., the upper surface 21a is inclined), a restoring force F2 acts on the wafer W. Therefore, in the electrostatic chuck device 1A, the wafer W and the upper surface 21a of the annular protrusion 21 can be easily brought into close contact with each other.

[0068] Furthermore, if the inclination angle θ exceeds 3°, the wafer W must be locally and steeply warped at the peripheral edge WE in order for the wafer W to adhere closely to the upper surface 21a. Considering the hardness of the wafer W, such deformation is often difficult. Therefore, in an electrostatic chuck device in which the inclination angle θ of the upper surface 21a of the annular convex portion exceeds 3°, the inclined upper surface 21a makes it easier for the peripheral edge WE of the wafer W to lift up from the upper surface 21a.

[0069] Furthermore, when plasma etching the wafer W using, for example, an electrostatic chuck device, the wafer W is attracted to the mounting surface 10a and is irradiated with plasma from the normal direction at the center of the mounting surface 10a. If an electrostatic chuck device is used in which the inclination angle θ of the upper surface 21a of the annular convex portion exceeds 3°, and if the wafer W is locally deformable at the peripheral portion WE and can be closely attached to the upper surface 21a, the peripheral portion WE will be etched in a state inclined by more than 3° with respect to the plasma irradiated from the normal direction.

[0070] If etching is performed under such conditions, the processing state at the peripheral edge WE will be significantly different from the processing state at the center of the wafer W, making it difficult to obtain appropriate processing results. As a result, even if such an electrostatic chuck device is used, it is difficult to achieve the effect of "effectively utilizing the wafer peripheral edge" that is expected by narrowing the width of the annular convex portion.

[0071] In contrast, in an electrostatic chuck device in which the inclination angle θ is 3° or less, the wafer W can be appropriately deformed around the annular protrusion 21, and can be easily brought into close contact with the upper surface 21a of the annular protrusion 21. In addition, appropriate plasma processing can be performed on the peripheral edge WE of the wafer W.

[0072] As described above, in the electrostatic chuck device 1A, by appropriately adjusting the shape of the annular protrusion 21, in addition to the electrostatic attraction force F1, a restoring force F2 can be applied to the peripheral edge WE of the wafer W. As a result, in the electrostatic chuck device 1A, even if the width of the annular protrusion 21 is narrowed to effectively utilize the peripheral edge of the wafer W, leakage of cooling gas at the contact portion between the wafer W and the annular protrusion 21 is suppressed. This enables effective heat dissipation from the peripheral edge WE to the electrostatic chuck member 2A, enabling appropriate temperature control of the wafer W.

[0073] 3 shows an electrostatic chuck device 1X having an annular protrusion 29 as an extreme example, but even if the upper surface of the annular protrusion is a horizontal plane similar to the upper surface 22a of the protrusion 22A, the restoring force F2 at the peripheral portion WE of the wafer W cannot be expected. That is, as in the electrostatic chuck device 1A of this embodiment, when the upper surface 21a of the annular protrusion 21 is The outer circumference is higher than the inner circumference The angle of inclination θ is in the range of more than 0° and 3° or less with respect to the top surface of the reference convex portion of the plurality of convex portions 22 that is closest to the annular convex portion 21. When this requirement is satisfied, a restoring force F2 is generated as explained in "(b) Inclination angle of upper surface 21a of annular convex portion 21", and the effect of the present invention is achieved.

[0074] According to the electrostatic chuck member having the above-described configuration, it is possible to provide an electrostatic chuck device with good thermal uniformity.

[0075] Furthermore, according to the electrostatic chuck device having the above-described configuration, the inclusion of the electrostatic chuck member improves the temperature uniformity.

[0076] (Variation) 5 and 6 are schematic cross-sectional views showing modifications of this embodiment, and correspond to FIG.

[0077] 5 includes an electrostatic chuck member 2B, a base 3, and an adhesive layer 4. The electrostatic chuck member 2B includes a base 10B and an electrostatic attraction electrode 13. The base 10B includes a mounting plate 11B, a support plate 12, and an insulating material layer 14.

[0078] The cross-sectional shape of the base 10B in the thickness direction is a concave shape whose height gradually increases from the center 10b of the mounting surface 10a toward the outer periphery 10c of the mounting surface 10a. The cross-sectional shape of the base 10B may be a curved concave shape, or may be a V-shape whose lowest point is the center 10b and which slopes toward the center 10b.

[0079] 6 includes an electrostatic chuck member 2C, a base 3, and an adhesive layer 4. The electrostatic chuck member 2C includes a base 10C and an electrostatic attraction electrode 13. The base 10C includes a mounting plate 11C, a support plate 12, and an insulating material layer 14.

[0080] The cross-sectional shape of the base 10C in the thickness direction is a convex shape whose height gradually increases from the center 10b of the mounting surface 10a toward the outer periphery 10c of the mounting surface 10a.

[0081] In these electrostatic chuck devices 1B and 1C, (1) The width of the annular convex portion is 0.1 mm or more and 4.0 mm or less, (2) The inclination angle of the upper surface of the annular convex portion relative to the upper surface of the reference convex portion is greater than 0° and less than 3°. By satisfying these requirements, an electrostatic chuck member and an electrostatic chuck device with good thermal uniformity can be obtained, similar to the electrostatic chuck device 1A described above.

[0082] In the above embodiment, the outer circumferential portion 13x of the electrostatic attraction electrode 13 of the electrostatic chuck member 2A is described as not overlapping with the annular protrusion 21 in plan view, but this is not limiting.

[0083] 7 is an enlarged cross-sectional view showing the configuration of the peripheral edge portion of an electrostatic chuck member 2B according to a modified example, and corresponds to FIG. 2. As in the electrostatic chuck member 2B shown in FIG. 7, the outer circumferential portion 13x of the electrostatic attraction electrode 13 may overlap the annular protrusion 21 in a plan view. When the outer circumferential portion 13x of the electrostatic attraction electrode 13 overlaps the annular protrusion 21 in a plan view, in addition to the effect of the upper surface 22a of the annular protrusion 21 being the inclined surface described above, an electrostatic attraction force can be transmitted to the wafer W via the annular protrusion 21. This allows the wafer W (see FIG. 1) to be strongly attracted to the annular protrusion 21 and brought into close contact with it.

[0084] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. The shapes and combinations of the components shown in the above examples are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention. [Explanation of symbols]

[0085] 1A, 1B, 1C, 1X...electrostatic chuck device, 2A, 2B, 2C, 2X...electrostatic chuck member, 10a...mounting surface, 10b...center, 10c...periphery, 10A, 10B, 10C...base, 13...electrostatic attraction electrode, 13x...periphery, 21, 29...annular convex portion, 22, 22A, 22B...convex portion, WA...width, θ...inclination angle

Claims

1. a base whose upper surface is a mounting surface on which a plate-shaped sample is placed; an electrostatic attraction electrode provided on the surface of the base opposite to the placement surface or inside the base, the base includes an annular protrusion that protrudes upward along the edge of the upper surface and is provided in a closed annular shape; a plurality of protrusions provided inside the annular protrusion and protruding upward, an upper surface of the annular convex portion is higher on the outer circumferential side than on the inner circumferential side and is inclined with respect to an upper surface of a reference convex portion of the plurality of convex portions that is closest to the annular convex portion; The width of the annular convex portion is 0.1 mm or more and 4.0 mm or less, An electrostatic chuck member, wherein an inclination angle of the upper surface of the annular convex portion with respect to the upper surface of the reference convex portion is greater than 0° and is equal to or smaller than 3°.

2. the plurality of protrusions form a plurality of protrusion groups arranged concentrically with the annular protrusion, 2. The electrostatic chuck member according to claim 1, wherein the reference convex portion is a convex portion included in the convex portion group that is closest to the annular convex portion among the plurality of convex portion groups.

3. An electrostatic chuck device comprising the electrostatic chuck member according to claim 1 or 2.

4. 4. The electrostatic chuck device according to claim 3, wherein the base has a concave shape in a cross section in the thickness direction of the base, the height of which gradually increases from the center of the mounting surface toward the outer periphery of the mounting surface.

5. 4. The electrostatic chuck device according to claim 3, wherein the base has a convex shape whose height gradually decreases from the center of the mounting surface toward the outer periphery of the mounting surface in a cross section in the thickness direction of the base.

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