Holding device

Abstract

The objective is to provide a wafer holding device that suppresses non-uniformity of the in-plane temperature distribution of a wafer caused by protrusions and grooves. [Solution] The protrusion P1 has a base B1, a top A1, and a stepped surface B1a. Assuming that there is a top central axis OA1 passing through the center of the top A1 and perpendicular to the upper surface 120a, a base central axis OB1 passing through the center of the base B1 and perpendicular to the upper surface 120a, and a groove central axis OC1 passing through the center of the groove C1 and perpendicular to the upper surface 120a, the first axis, which is one of the three axes of the top central axis OA1, base central axis OB1, and groove central axis OC1, does not coincide with at least one of the second and third axes, which are the remaining three axes of the top central axis OA1, base central axis OB1, and groove central axis OC1.

Description

Technical Field

[0001] The present disclosure relates to a holding device for holding an object.

Background Art

[0002] As a holding device for holding a wafer in a semiconductor processing apparatus, for example, an electrostatic chuck is used. The electrostatic chuck generally has a ceramic member having a suction surface and a base material. The ceramic member and the base material are adhered by an adhesive. A suction electrode is provided inside the ceramic member. By using the electrostatic attraction generated when a voltage is applied to the suction electrode, the electrostatic chuck sucks and holds the wafer on the suction surface of the ceramic member.

[0003] Some electrostatic chucks have a large number of dots formed on the surface facing the wafer. The large number of dots are for supporting the inner portion of the back surface of the wafer. For example, Patent Document 1 discloses an electrostatic chuck in which a groove portion 124 surrounding the periphery of a plurality of dots 122 is formed. It is also described that the charge 200 accumulates in the groove portion 124 and prevents it from moving to the digging surface 121.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When the groove portion 124 surrounds the periphery of the dot 122 as in Patent Document 1, in the thickness direction of the electrostatic chuck, the film thickness of the ceramic changes steeply. The dot 122 contacts the wafer, but an inert gas exists between the groove portion 124 and the wafer.

[0006] In this case, a temperature difference occurs between the area facing the dot 122 and the area facing the groove 124 on the wafer. That is, the areas of the dot 122 and the groove 124 become temperature-specific regions, resulting in an uneven distribution of in-plane temperature on the wafer. If the in-plane temperature distribution of the wafer is uneven, local differences will occur in the etching rate of the wafer.

[0007] The problem that the technology disclosed herein aims to solve is to provide a holding device that suppresses the non-uniformity of the in-plane temperature distribution of a wafer caused by protrusions and grooves. [Means for solving the problem]

[0008] The holding device of the present disclosure is a holding device having a plate-shaped member, the plate-shaped member having a first surface, a convex portion protruding from the first surface, and a groove portion formed along the periphery of the convex portion, the convex portion having a base portion disposed on the side of the first surface, a top portion disposed at a position further away from the base portion than the first surface, and a step disposed between the base portion and the top portion, and assuming a top central axis passing through the center of the top portion and perpendicular to the first surface, a base central axis passing through the center of the base portion and perpendicular to the first surface, the first axis, which is one of the three axes of the top central axis, the base central axis and the groove central axis, does not coincide with at least one of the remaining axes of the three axes of the top central axis, the base central axis and the groove central axis. [Effects of the Invention]

[0009] According to this disclosure, it is possible to suppress the non-uniformity of the in-plane temperature distribution of the wafer caused by protrusions and grooves. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a perspective view of the electrostatic chuck 100 according to the first embodiment. [Figure 2]Figure 2 is a cross-sectional view showing the internal structure of the electrostatic chuck 100 shown in Figure 1. [Figure 3] Figure 3 is a cross-sectional view illustrating the protrusions P1 and grooves C1 in the plate-shaped member 120 of the electrostatic chuck 100 according to the first embodiment. [Figure 4] Figure 4 is a plan view illustrating the protrusions P1 and grooves C1 in the plate-shaped member 120 of the electrostatic chuck 100 according to the first embodiment. [Figure 5] Figure 5 shows the range of the temperature-specific region TSA1 in the electrostatic chuck 100 of the first embodiment. [Figure 6] Figure 6 shows the range of the temperature specificity region TSA2 in an electrostatic chuck when there is no misalignment of the central axis. [Figure 7] Figure 7 shows the charge state when the electrostatic chuck 100 of the first embodiment is in use. [Figure 8] Figure 8 is a plan view showing the convex portion PS1 of the seal band SB1 in a modified example of the first embodiment. [Figure 9] Figure 9 is a cross-sectional view illustrating the protrusion P1 and groove C2 in the plate-shaped member 220 of the electrostatic chuck 200 of the second embodiment. [Figure 10] Figure 10 is a cross-sectional view illustrating the protrusions P1 and grooves C3 in the plate-shaped member 320 of the electrostatic chuck 300 of the first modified example of the second embodiment. [Figure 11] Figure 11 is a cross-sectional view illustrating the protrusion P1 and groove C4 in the plate-shaped member 420 of the electrostatic chuck 400 in a second modified example of the second embodiment. [Figure 12] Figure 12 is a cross-sectional view illustrating the protrusion P1 and groove C5 in the plate-shaped member 520 of the electrostatic chuck 500 of the third embodiment. [Figure 13] Figure 13 is a cross-sectional view illustrating the multiple protrusions and multiple grooves in the plate-shaped member 620 of the electrostatic chuck 600 of the fourth embodiment. [Modes for carrying out the invention]

[0011] [Details of Embodiments of the Present Disclosure] Embodiments of the present disclosure will be listed and described.

[0012] (1) The holding device of the present disclosure is a holding device having a plate-shaped member. The plate-shaped member has a first surface, a convex portion protruding from the first surface, and a groove portion formed along the periphery of the convex portion. The convex portion has a base portion disposed on the first surface side, a top portion disposed at a position farther from the first surface than the base portion, and a step disposed between the base portion and the top portion. When assuming a top portion central axis passing through the center of the top portion and perpendicular to the first surface, a base portion central axis passing through the center of the base portion and perpendicular to the first surface, and a groove portion central axis passing through the center of the groove portion and perpendicular to the first surface, among the three axes of the top portion central axis, the base portion central axis, and the groove portion central axis, a first axis, which is one of the three axes, does not coincide with at least one of the remaining two axes, i.e., the second axis and the third axis, of the top portion central axis, the base portion central axis, and the groove portion central axis.

[0013] In this holding device, the area of the temperature-specific region located around the convex portion and the groove portion formed on the first surface of the plate-shaped member is small. Therefore, this holding device can keep the in-plane temperature distribution of the wafer as uniform as possible.

[0014] (2) In the holding device according to (1) above, the base portion central axis coincides with one of the top portion central axis and the groove portion central axis and does not coincide with the other of the top portion central axis and the groove portion central axis.

[0015] (3) In the holding device according to (1) or (2) above, the plurality of convex portions are formed in a columnar shape.

[0016] (4) In the holding device according to any one of (1) to (3) above, the convex portion is formed in an annular shape along the outer periphery of the first surface.

[0017] (5) In the holding device described in any of (1) to (4) above, the groove portion has an inclined surface and a groove bottom portion sandwiched between the inclined surfaces, and the distance between the step and the groove bottom portion is greater than the distance between the first surface and the groove bottom portion.

[0018] (6) In the holding device described in any of (1) to (5) above, the top portion has a top surface at the position furthest from the first surface, the step surrounds the top portion, and in a cross section including the central axis of the top portion, the width of the top surface is longer than the width of one side of the step and the width of the other side.

[0019] (7) In the holding device described in any of (1) to (6) above, the top portion has a top surface at the position furthest from the first surface, and in a cross section including the central axis of the top portion, the width of the top surface is longer than the width of one of the groove portions and the other.

[0020] (8) A holding device according to any of (1) to (7) above, comprising a first protrusion and a first groove formed along the first protrusion, and a second protrusion and a second groove formed along the second protrusion, wherein the displacement of two axes among the base central axis, the top central axis and the groove central axis in the first protrusion and the first groove is different from the displacement of two axes among the base central axis, the top central axis and the groove central axis in the second protrusion and the second groove.

[0021] (9) In the holding device described in any of (1) to (8) above, the groove portion has an inclined surface and a groove bottom portion sandwiched between the inclined surfaces, and the groove bottom portion is not a flat surface.

[0022] (10) In the holding device described in any of (1) to (9) above, the groove portion has an inclined surface and a groove bottom portion sandwiched between the inclined surfaces, the groove bottom portion has a first groove bottom portion and a second groove bottom portion, and the distance between the first groove bottom portion and the first surface is smaller than the distance between the second groove bottom portion and the first surface.

[0023] The following describes specific embodiments, using a holding device for holding semiconductor wafers and the like in a semiconductor processing apparatus as an example, with reference to the figures. However, the technology described herein is not limited to these embodiments. Also, the thicknesses of each layer in the drawings do not represent the ratio of actual thicknesses.

[0024] (First Embodiment) 1. Electrostatic chuck Figure 1 is a perspective view of the electrostatic chuck 100 according to the first embodiment. Figure 2 is a cross-sectional view showing the internal structure of the electrostatic chuck 100 of Figure 1.

[0025] The electrostatic chuck 100 is a holding device for holding a semiconductor wafer W1 (hereinafter also simply referred to as "wafer W1") in a semiconductor processing apparatus. The electrostatic chuck 100 can also hold glass substrates and the like. The electrostatic chuck 100 can attract and hold semiconductor wafers and the like when performing plasma processing on semiconductor wafers and the like in a reduced-pressure chamber.

[0026] The electrostatic chuck 100 comprises a base material 110, a plate-shaped member 120, and a bonding layer 130. As shown in Figure 2, the plate-shaped member 120 has a first surface (hereinafter also referred to as the upper surface 120a) and a lower surface 120b. The upper surface 120a has ejection holes H1. The ejection holes H1 supply inert gas to the space between the wafer W1 and the upper surface 120a. The base material 110 has an upper surface 110a and a lower surface 110b. The bonding layer 130 bonds the upper surface 110a of the base material 110 and the lower surface 120b of the plate-shaped member 120.

[0027] 1-1. Base material The base material 110 has a refrigerant flow path 111 and a gas flow path 113. The refrigerant flow path 111 is a flow path for circulating a refrigerant to cool the base material 110. The gas flow path 113 is in communication with the gas flow path 123 of the plate-shaped member 120.

[0028] The main component of the base material 110 is aluminum, an aluminum alloy, a composite of metal and ceramics (Al-SiC), or ceramics (SiC). When the main component of the base material 110 is Al-SiC, for example, the aluminum component (weight %) is in the range of 30 ≤ Al ≤ 90 (e.g., 30 wt%), and the silicon component (weight %) is in the range of 10 ≤ Si ≤ 70 (e.g., 70 wt%). The diameter of the base material 110 may be larger than the diameter of the plate-shaped member 120 so that the entire plate-shaped member 120 can be placed on it.

[0029] The thermal expansion coefficient of the base material 110 is between 5 ppm / K and 9 ppm / K. By using the aforementioned materials for the plate-shaped member 120 and the base material 110, the difference in thermal expansion coefficients between the plate-shaped member 120 and the base material 110 is very small. This difference in thermal expansion coefficients is, for example, 5 ppm / K or less.

[0030] The thermal conductivity of the base material 110 is approximately 180 W / m·K. The thermal conductivity of the base material 110 is sufficiently higher than that of the plate-shaped member 120.

[0031] 1-2. Plate-shaped member The plate-shaped member 120 has an adsorption electrode 121, a heater electrode 122, and a gas flow path 123.

[0032] The main components of the plate-shaped member 120 are alumina, aluminum nitride, yttria, or a composite material of alumina and silicon carbide. The thermal expansion coefficient of the plate-shaped member 120 is, for example, 6 ppm / K or more and 8 ppm / K or less. The thermal conductivity of the plate-shaped member 120 is, for example, 18 W / m·K.

[0033] 1-3.Adsorption electrode The adsorption electrode 121 is an electrode for adsorbing the wafer W1. The adsorption electrode 121 exerts electrostatic adsorption force when a voltage is applied. Examples of electrostatic adsorption forces include Coulomb force, Johnsen-Rabec force, or gradient force. The material of the adsorption electrode 121 is tungsten, molybdenum, or an alloy thereof. The adsorption electrode 121 may also use a metallized conductive layer with a conductive paste printed on it, a metal foil, or a metal mesh.

[0034] 1-4. Heater electrodes The heater electrode 122 is a component for heating the wafer W1 and maintaining a uniform in-plane temperature distribution of the wafer W1. The main components of the heater electrode 122 are tungsten, molybdenum, or alloys thereof, or carbides thereof. The heater electrode 122 is located inside the plate-shaped member 120. The heater electrode 122 may also be located on the surface of the plate-shaped member 120 or inside a separate heater component (polyimide heater) from the plate-shaped member 120. The heater electrode 122 may use metallized conductive layers with a conductive paste printed on them, or it may use metal foil or metal mesh.

[0035] 1-5. Gas flow path A gas channel FP1 is formed inside the electrostatic chuck 100. The gas channel FP1 is a channel for delivering an inert gas such as He into the space between the wafer W1 and the upper surface 120a. The gas channel FP1 is formed extending from the base material 110 to the plate-shaped member 120. The gas channel FP1 has a gas channel 113 and a gas channel 123. The gas channel 113 is the base material side gas channel. The gas channel 123 is the plate-shaped member side gas channel. The gas channel 113 and the gas channel 123 are in communication with each other.

[0036] 1-6. Terminals As shown in Figure 2, terminal ET1 is connected to the adsorption electrode 121. Terminal ET1 is connected to an external power supply. Power is supplied to the adsorption electrode 121 via terminal ET1. Terminal ET2 is connected to the heater electrode 122. Terminal ET2 is connected to an external power supply. Power is supplied to the heater electrode 122 via terminal ET2.

[0037] 2. Protrusions and grooves Figure 3 is a cross-sectional view illustrating the protrusions P1 and grooves C1 in the plate-shaped member 120 of the electrostatic chuck 100 according to the first embodiment. Figure 4 is a plan view illustrating the protrusions P1 and grooves C1 in the plate-shaped member 120 of the electrostatic chuck 100 according to the first embodiment.

[0038] 2-1. Convex part Multiple protrusions P1 and multiple grooves C1 are formed on the upper surface 120a of the plate-like member 120. The protrusions P1 project from the upper surface 120a of the plate-like member 120. The protrusions P1 are formed in a columnar shape. The protrusions P1 have a top A1 and a base B1. The top A1 and base B1 are cylindrical in shape. The outer diameter of the base B1 is larger than the outer diameter of the top A1.

[0039] The top portion A1 has a top surface A1a and a side surface A1b. The top surface A1a is located at the tip of the top portion A1. That is, the top portion A1 has the top surface A1a at the position furthest from the upper surface 120a. The top surface A1a is the surface that contacts the wafer W1 and supports the wafer W1 when the semiconductor processing device is in use. For this reason, the top surface A1a is mirror-finished. The top surfaces A1a of the multiple protrusions P1 are shaped to conform to the back surface of the wafer W1. The top surface A1a is a surface parallel to the upper surface 120a. The side surface A1b is the outer surface of the cylinder.

[0040] The base B1 has a stepped surface B1a (hereinafter also simply referred to as "step") and a side surface B1b. The stepped surface B1a distinguishes the top A1 from the base B1. The top A1 is located further from the bottom surface 120b than the stepped surface B1a. The base B1 is located closer to the bottom surface 120b than the stepped surface B1a. The stepped surface B1a is a surface parallel to the top surface 120a. The stepped surface B1a surrounds the top A1. The distance between the stepped surface B1a and the bottom surface 120b is greater than the distance between the top surface 120a and the bottom surface 120b. The side surface B1b is the outer surface of the cylinder. As will be described later, the side surface B1b is connected to the inner side surface C1b of the groove C1.

[0041] The outer diameter of the apex A1 is, for example, 200 μm or more and 2000 μm or less. The height of the apex A1 is, for example, 1 μm or more and 50 μm or less. Here, the height of the apex A1 is the distance from the apex surface A1a to the step surface B1a. The outer diameter of the base B1 is, for example, 205 μm or more and 2500 μm or less. The height of the base B1 is, for example, 1 μm or more and 50 μm or less. Here, the height of the base B1 is the distance from the step surface B1a to the top surface 120a, and is lower than the height of the apex surface A1a. The height of the convex portion P1 is, for example, 5 μm or more and 50 μm or less. Here, the height of the convex portion P1 is the distance from the apex surface A1a to the top surface 120a.

[0042] 2-2. Groove The groove C1 is a recess formed in the plate-like member 120 in an orientation from the upper surface 120a to the lower surface 120b. The groove C1 is formed along the periphery of the convex portion P1. The groove C1 surrounds the convex portion P1. The groove C1 is formed in an annular shape. The groove C1 has a bottom surface C1a, an inner side surface C1b, and an outer side surface C1c.

[0043] The distance between the inner surface C1b and the outer surface C1c is, for example, 5 μm to 150 μm. The distance between the top surface 120a and the bottom surface C1a is, for example, 10 μm to 150 μm. The diameter of the inner surface C1b is, for example, 205 μm to 2500 μm.

[0044] From the lower surface 120b side of the plate-shaped member 120, the groove C1 is arranged in the following order: bottom surface C1a, top surface 120a, stepped surface B1a, and top surface A1a. The top surface A1a is located at the position furthest from the lower surface 120b of the plate-shaped member 120.

[0045] The bottom surface C1a is the bottom of the groove. The bottom surface C1a is sandwiched between the inner side surface C1b and the outer side surface C1c.

[0046] 2-3. Central axis of the protrusions and grooves As shown in Figure 3, the top central axis OA1, the base central axis OB1, and the groove central axis OC1 are hypothetically defined. The top central axis OA1 is the axis passing through the center of the cylindrical shape of the top A1. The base central axis OB1 is the axis passing through the center of the cylindrical shape of the base B1. The groove central axis OC1 is the axis passing through the center of the annular shape of the groove C1. The top central axis OA1, the base central axis OB1, and the groove central axis OC1 are all perpendicular to the upper surface 120a of the plate-like member 120. In this specification, unless otherwise specified, "center" refers to the geometric center (centroid) when focusing on each figure in the convex part P1, etc.

[0047] As shown in Figure 3, the top central axis OA1 does not coincide with the base central axis OB1 and the groove central axis OC1. The base central axis OB1 and the groove central axis OC1 coincide.

[0048] As shown in Figure 3, in the cross-section including the central axis OA1 of the top surface, the width LA1 of the top surface A1a is longer than one width LB1 and the other width LB2 of the stepped surface B1a.

[0049] As shown in Figure 3, in the cross-section including the central axis OA1 of the top surface, the width of the top surface A1a is longer than the width LC1 and the width LC2 of the groove C1.

[0050] The top surface A1a supports the back surface of the wafer W1. Therefore, it is desirable for the top surfaces A1a to be arranged regularly. While the top central axis OA1 is arranged regularly, the base central axis OB1 and other axes should be positioned slightly offset from the top central axis OA1. For example, the base central axis OB1 and the groove central axis OC1 can be offset outward relative to the top central axis OA1.

[0051] 3.Temperature singular region 3-1. Temperature-specific region of the electrostatic chuck of the first embodiment Figure 5 shows the range of the temperature-specific region TSA1 in the electrostatic chuck 100 of the first embodiment. As shown in Figure 5, in the temperature-specific region TSA1, the distance between the top A1 and the groove C1 is relatively short. That is, in the temperature-specific region TSA1, the change in the thickness of the ceramics of the plate-shaped member 120 is relatively steep.

[0052] On the other hand, in the first region R1 on the diagonal side of the temperature singularity, the distance between the apex A1 and the groove C1 is relatively large. That is, in the first region R1, the change in the thickness of the ceramics of the plate-like member 120 is relatively gradual.

[0053] Thus, the temperature-specific region TSA1 exists in one direction relative to the convex portion P1 and is not formed to surround the convex portion P1.

[0054] 3-2. Temperature-specific regions of electrostatic chucks when there is no misalignment of the central axis. Figure 6 shows the range of the temperature-specific region TSA2 in an electrostatic chuck when there is no misalignment of the central axis. In an electrostatic chuck when there is no misalignment of the central axis, the central axis of the convex portion and the central axis of the groove portion coincide. Therefore, the temperature-specific region TSA2 exists in an annular shape along the groove portion. Furthermore, the temperature-specific region TSA2 surrounds the convex portion P1. In this case, the temperature-specific region TSA2 extends over a relatively wide area.

[0055] 3-3. Comparison of the electrostatic chuck of the first embodiment with an electrostatic chuck without misalignment of the central axis As shown in Figures 5 and 6, the area occupied by the temperature-specific region TSA1 in the electrostatic chuck 100 of the first embodiment is smaller than the area occupied by the temperature-specific region TSA2 in the electrostatic chuck when there is no misalignment of the central axis. In the first embodiment, the area occupied by the temperature-specific region TSA1 is more limited. Therefore, the in-plane temperature distribution of the wafer W1 can be made as uniform as possible.

[0056] 4. Movement of electric charge Figure 7 shows the charge state when using the electrostatic chuck 100 of the first embodiment. As shown in Figure 7, the wafer W1 is negatively charged, and the side of the adsorption electrode 121 is positively charged. At this time, an electric field is generated in the direction of arrow EF1. Therefore, the charge moves from the wafer W1 towards the groove C1 in the directions of arrows K1a and K1b. Because an electric field is generated in the direction of arrow EF1, the charge hardly moves in the directions of arrows K2a and K2b.

[0057] The outer surface C1c of groove C1 prevents the lateral movement of charge in Figure 7. Since groove C1 serves to prevent such charge movement, it is undesirable to unnecessarily widen the width of groove C1. This is because if one width LC1 and the other width LC2 of groove C1 are long, more charge will flow into groove C1.

[0058] Therefore, it is preferable to make the shapes of the convex portion P1 and the groove portion C1 asymmetrical, as in the electrostatic chuck 100 of the first embodiment.

[0059] 5. Effects of the First Embodiment The electrostatic chuck 100 of the first embodiment has a plate-shaped member 120. The plate-shaped member 120 has an upper surface 120a, a protrusion P1 projecting from the upper surface 120a, and a groove C1 formed around the protrusion P1. The protrusion P1 has a base B1 located on the upper surface 120a side, a top A1 located at a position further away from the base B1 than the upper surface 120a, and a stepped surface B1a located between the base B1 and the top A1. Assuming that there is a central axis OA1 at the top that passes through the center of the top A1 and is perpendicular to the top surface 120a, a central axis OB1 at the base that passes through the center of the base B1 and is perpendicular to the top surface 120a, and a central axis OC1 at the groove that passes through the center of the groove C1 and is perpendicular to the top surface 120a, then the first axis, which is one of the three axes of the central axis OA1 at the top, the central axis OB1 at the base, and the central axis OC1 at the groove, does not coincide with at least one of the remaining axes of the three axes, the second axis and the third axis.

[0060] In this electrostatic chuck 100, the area of ​​the temperature-specific region located around the protrusion P1 and groove C1 formed on the upper surface 120a of the plate-shaped member is small. Therefore, this electrostatic chuck 100 can maintain the in-plane temperature distribution of the wafer as uniformly as possible.

[0061] 6. Manufacturing method 6-1. Manufacturing process for plate-shaped members A slurry is produced by mixing ceramic raw material powder, an organic binder, a plasticizer, and a solvent. Multiple ceramic sheets are produced by molding this slurry. Depending on the sheet, a portion that will become a gas channel FP1 is formed. Next, the multiple sheets are stacked and fired. A convex portion P1 and a groove portion C1 are formed on this by laser processing or the like. This produces a plate-like member 120.

[0062] 6-2. Other processes A separate manufacturing process for the base material 110 is carried out. Then, the electrostatic chuck 100 is manufactured by joining the base material 110 and the plate-shaped member 120.

[0063] 7. Variations 7-1. Relationship of the central axis The electrostatic chuck 100 has a plate-shaped member 120. The plate-shaped member 120 has an upper surface 120a, a protrusion P1 projecting from the upper surface 120a, and a groove C1 formed around the protrusion P1. The protrusion P1 has a base B1 located on the upper surface 120a side, a top A1 located at a position further away from the base B1 than the upper surface 120a, and a stepped surface B1a located between the base B1 and the top A1. Assuming that there is a central axis OA1 at the top that passes through the center of the top A1 and is perpendicular to the top surface 120a, a central axis OB1 at the base that passes through the center of the base B1 and is perpendicular to the top surface 120a, and a central axis OC1 at the groove that passes through the center of the groove C1 and is perpendicular to the top surface 120a, then the first axis, which is one of the three axes of the central axis OA1 at the top, the central axis OB1 at the base, and the central axis OC1 at the groove, does not coincide with at least one of the remaining axes of the three axes, the second axis and the third axis.

[0064] For example, the base central axis OB1 may coincide with either the apex central axis OA1 or the groove central axis OC1, but may not coincide with the other of the apex central axis OA1 or the groove central axis OC1.

[0065] 7-2. Seal Bands Figure 8 is a plan view showing the protrusion PS1 of the seal band SB1 in a modified example of the first embodiment. As shown in Figure 8, the plate-shaped member 120 of the electrostatic chuck 100 has a seal band SB1 on its outer circumference. The seal band SB1 seals the outer circumference of the plate-shaped member 120. As shown in Figure 8, the seal band SB1 has a protrusion PS1. The seal band SB1 is formed in an annular shape along the outer circumference of the upper surface 120a of the plate-shaped member 120. The protrusion PS1 is formed in an annular shape along the seal band SB1 and along the outer circumference of the upper surface 120a of the plate-shaped member 120.

[0066] The convex portion PS1 has a top portion AS1, a base portion BS1, a base portion BS2, a groove portion CS1, and a groove portion CS2. As shown in Figure 8, the top portion AS1, the base portion BS1, the base portion BS2, the groove portion CS1, and the groove portion CS2 are formed in an annular shape. The base portion BS1 is located on the inner circumference side of the top portion AS1, and the base portion BS2 is located on the outer circumference side of the top portion AS1. Similarly, the groove portion CS1 is located on the inner circumference side of the top portion AS1, and the groove portion CS2 is located on the outer circumference side of the top portion AS1.

[0067] As mentioned above, while the protrusion P1 of the first embodiment is substantially cylindrical, the protrusion PS1 of the seal band SB1 is annular, as shown in Figure 8. In a cross section passing through the center of the disc-shaped plate member 120 and perpendicular to the upper surface 120a, asymmetrical irregularities are present, as shown in Figure 3.

[0068] For each convex portion PS1 formed on the seal band SB1, a top central axis OAS1, a base central axis OBS1, and a groove central axis OCS1 can be virtually defined. In Figure 8, the top central axis OAS1, the base central axis OBS1, and the groove central axis OCS1 are shown with their angles shifted from the center of the plate-like member 120 for illustrative purposes. Since the convex portion PS1 is annular and rotationally symmetric with respect to the center of the plate-like member 120, even if an arbitrary cross-section passing through the center of the plate-like member 120 and perpendicular to the upper surface 120a is selected, it will have the same structure within the range of machining accuracy.

[0069] The top central axis OAS1 indicates the center of the width of the top AS1 in any cross section passing through the center of the plate-like member 120 and perpendicular to the upper surface 120a. The base central axis OBS1 indicates the center of the width between the base BS1 and base BS2 in any cross section passing through the center of the plate-like member 120 and perpendicular to the upper surface 120a. The groove central axis OCS1 indicates the center of the width between the groove CS1 and groove CS2 in any cross section passing through the center of the plate-like member 120 and perpendicular to the upper surface 120a.

[0070] As shown in Figure 8, in any cross section passing through the center of the plate-like member 120 and perpendicular to the upper surface 120a, the width of the base portion BS1 and the width of the base portion BS2 are different. Similarly, in any cross section passing through the center of the plate-like member 120 and perpendicular to the upper surface 120a, the width of the groove portion CS1 and the width of the groove portion CS2 are different.

[0071] Thus, when setting the top central axis OAS1, the base central axis OBS1, and the groove central axis OCS1, a cross section passing through the center of the plate-like member 120 and perpendicular to the upper surface 120a can be arbitrarily selected.

[0072] Furthermore, the seal band SB1 may have multiple protrusions PS1.

[0073] 7-3.Top surface The top surface A1a is a plane parallel to the upper surface 120a. The top surface A1a may be inclined with respect to the upper surface 120a within a range of 0° to 5°.

[0074] 7-4.Step surface The stepped surface B1a is a surface parallel to the upper surface 120a. The stepped surface B1a may be inclined with respect to the upper surface 120a within a range of 0° to 5°.

[0075] 7-5.Top The apex A1 is cylindrical. The apex A1 may have other shapes, for example, a frustocone. If the apex A1 is a frustocone, the side surface A1b is an inclined surface that slopes in a direction perpendicular to the top surface 120a. The apex A1 may also be a polygonal prism or a frustocone.

[0076] 7-6. Basal part The base B1 is cylindrical. The base B1 may have other shapes, for example, a frustoconical shape. If the base B1 is a frustoconical shape, the side surface B1b is an inclined surface that is inclined with respect to the direction perpendicular to the top surface 120a. The base B1 may also be a polygonal prism or a frustoconical shape.

[0077] 7-7. Groove The bottom surface C1a of the groove C1 is a surface parallel to the top surface 120a. The bottom surface C1a of the groove C1 may be inclined with respect to the top surface 120a within a range of 0° to 5°.

[0078] 7-8. Heater electrodes The electrostatic chuck 100 does not necessarily have a heater electrode 122. The position of the heater electrode 122 may be occupied by the adsorption electrode 121 and other electrodes besides the heater electrode 122.

[0079] 7-9. Manufacturing method Instead of laminating multiple ceramic sheets, techniques such as powder hot pressing may be used.

[0080] 7-10. Combinations You are free to combine the above variations as you wish.

[0081] (Second Embodiment) A second embodiment will be described. The explanation will focus on the differences from the first embodiment.

[0082] 1. Convex and grooved portions Figure 9 is a cross-sectional view illustrating the protrusion P1 and groove C2 in the plate-shaped member 220 of the electrostatic chuck 200 of the second embodiment. The plate-shaped member 220 has a protrusion P1 and a groove C2. The groove C2 has a groove bottom C2a and two inclined surfaces C2b and C2c. The groove bottom C2a is sandwiched between the inclined surfaces C2b and C2c. The groove bottom C2a is a depression and not a flat surface.

[0083] 2. Variations 2-1. First variation Figure 10 is a cross-sectional view illustrating the convex portion P1 and groove portion C3 in the plate-shaped member 320 of the electrostatic chuck 300 of the first modified example of the second embodiment. The plate-shaped member 320 has a convex portion P1 and a groove portion C3. The groove portion C3 has a groove bottom portion C3a and two inclined surfaces C3b and C3c. The groove bottom portion C3a is sandwiched between the inclined surfaces C3b and C3c. The groove bottom portion C3a is a depression and not a flat surface. In the inclined surfaces C3b and C3c, the angle of inclination becomes steeper as it moves away from the groove bottom portion C3a.

[0084] 2-2. Second variation Figure 11 is a cross-sectional view illustrating the protrusion P1 and groove C4 in the plate-shaped member 420 of the electrostatic chuck 400 in a second modified example of the second embodiment. The plate-shaped member 420 has a protrusion P1 and a groove C4. The groove C4 has a groove bottom C4a, a side surface C4b, a side surface C4c, a groove bottom C4d, a side surface C4e, and a side surface C4f. The groove bottom C4a is sandwiched between the side surfaces C4b and C4c. The groove bottom C4d is sandwiched between the side surfaces C4e and C4f.

[0085] The distance HC1 between the groove bottom C4a and the upper surface 120a is smaller than the distance HC2 between the groove bottom C4d and the upper surface 120a. Note that the groove bottoms C4a and C4d are connected in the circumferential direction. The depth of the groove bottom changes continuously. The depth of the groove bottom may also change in a step-like manner.

[0086] (Third embodiment) A third embodiment will be described. The explanation will focus on the differences from the first embodiment.

[0087] 1. Convex and grooved portions Figure 12 is a cross-sectional view illustrating the protrusion P1 and groove C5 in the plate-shaped member 520 of the electrostatic chuck 500 of the third embodiment. The groove C5 has a groove bottom C5a, a side surface C5b, and a side surface C5c. As shown in Figure 12, the three axes of the top central axis OA2, the base central axis OB2, and the groove central axis OC2 do not coincide with each other.

[0088] (Fourth Embodiment) A fourth embodiment will be described. The explanation will focus on the differences from the first embodiment.

[0089] 1. Convex and grooved portions Figure 13 is a cross-sectional view illustrating a plurality of protrusions and a plurality of grooves in a plate-shaped member 620 of the electrostatic chuck 600 of the fourth embodiment. As shown in Figure 13, the plate-shaped member 620 has a protrusion P6 and a groove C6 formed along the protrusion P6, and a protrusion P7 and a groove C7 formed along the protrusion P7. The protrusion P6 is the first protrusion. The protrusion P7 is the second protrusion. The groove C6 is the first groove. The groove C7 is the second groove.

[0090] The displacement of two axes among the apex central axis OA3, base central axis OB3, and groove central axis OC3 in the convex portion P6 and groove portion C6 is different from the displacement of two axes among the apex central axis OA4, base central axis OB4, and groove central axis OC4 in the convex portion P7 and groove portion C7.

[0091] Thus, the degree of axial misalignment between the protrusions P6 and P7 of the plate-shaped member 620 may differ.

[0092] (Combination of embodiments) The first to fourth embodiments may be combined, including variations. [Explanation of symbols]

[0093] 100... Electrostatic chuck (holding device) 110...Base material, 110a...Top surface, 110b...Bottom surface 120...Plate member, 120a...Top surface, 120b...Bottom surface 121...Adsorption electrode, 122...Heater electrode P1, P6, P7, PS1...Convex part, B1, BS1, BS2...Base part, A1, AS1...Top part B1a...Step surface, A1a...Top surface C1…Groove

Claims

1. A holding device having a plate-shaped member, The aforementioned plate-shaped member is Page 1 and, The protrusions that extend from the first surface, It has a groove formed along the periphery of the aforementioned protrusion, The aforementioned protrusion is, The base portion arranged on the first surface side, The top portion is located at a position away from the base portion from the first surface, It has a step between the base and the top, A central axis of the vertex that passes through the center of the vertex and is perpendicular to the first surface, The base central axis passing through the center of the base and perpendicular to the first surface, Assuming that the central axis of the groove passes through the center of the groove and is perpendicular to the first surface, The first axis, which is one of the three axes consisting of the top central axis, the base central axis, and the groove central axis, It does not coincide with at least one of the second and third axes, which are the remaining axes among the three axes consisting of the top central axis, the base central axis, and the groove central axis. holding device.

2. In the holding device according to claim 1, The aforementioned base central axis is, It coincides with one of the central axes of the top portion and the central axis of the groove portion, The central axis of the top portion and the central axis of the groove portion do not coincide with the other. holding device.

3. In the holding device according to claim 1, Multiple of the aforementioned protrusions, Formed in a columnar shape, holding device.

4. In the holding device according to claim 1, The aforementioned protrusion is, Along the outer circumference of the first surface, it is formed in an annular shape, holding device.

5. In the holding device according to claim 1, The groove portion is It has a slope and a groove bottom sandwiched between the slopes, The distance between the step and the bottom of the groove is, A distance greater than the distance between the first surface and the bottom of the groove, holding device.

6. In the holding device according to claim 1, The aforementioned top is, Having a top surface at the position furthest from the first surface, The aforementioned step is, It surrounds the aforementioned top, In the cross-section including the central axis of the vertex, The width of the top surface is, The width of one of the steps is longer than the width of the other step, holding device.

7. In the holding device according to claim 1, The aforementioned top is, Having a top surface at the position furthest from the first surface, In the cross-section including the central axis of the vertex, The width of the top surface is, The width of one of the grooves is longer than the width of the other groove, holding device.

8. In the holding device according to claim 1, A first protrusion and a first groove formed along the first protrusion, It has a second protrusion and a second groove formed along the second protrusion, The displacement of two axes among the base central axis, the top central axis, and the groove central axis in the first protrusion and the first groove is The displacement of two of the axes of the base central axis, the top central axis, and the groove central axis in the second protrusion and the second groove is different. holding device.

9. In the holding device according to claim 1, The groove portion is It has a slope and a groove bottom sandwiched between the slopes, The bottom of the groove is It is not a flat surface. holding device.

10. In the holding device according to claim 1, The groove portion is It has a slope and a groove bottom sandwiched between the slopes, The bottom of the groove is It has a first groove bottom and a second groove bottom, The distance between the bottom of the first groove and the first surface is Smaller than the distance between the bottom of the second groove and the first surface, holding device.

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