retainer

Abstract

To provide a retainer capable of improving the uniformity in in-plane temperature of an object being retained.SOLUTION: An electrostatic chuck 1 which has a plate-like member 10 having a retention surface 11 where a plurality of projection parts 16, 17 and 30a are formed and a reverse surface 12 provided on the opposite side from the retention surface 11, and retains a semiconductor wafer W on the retention surface 11 of the plate-like member 10 has, on bottom surfaces 18a of the recessed pars 18 other than the projection parts 16, 17 and 30a on the retention surface 11, first regions 181 at distances larger than a predetermined distance A from bottom part side faces BS of the projection parts 16, 17 and 30a and second regions 182 at distances equal to or less than the predetermined distance A from the bottom part side faces BS of the projection parts 16, 17 and 30a, the first regions 181 being larger in surface roughness than the second regions 182.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] The holding surface for holding the object is made to be an uneven surface, and the convex part of the uneven surface is made to be the holding surface for holding the object. A holding device is known in which the concave portions of the uneven surface are used as gas (helium, etc.) supply paths. In such a holding device, if particles (fine particles) are generated, the product yield will decrease. Therefore, it is necessary to suppress the generation of particles. In the suction and fixation device (holding device) described in the document 1, the top and side surfaces of the convex portions of the uneven surface and the uneven surface The bottom surfaces of the recesses are mirror-polished to prevent particle generation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-86664 Summary of the Invention [Problem to be solved by the invention]

[0004] However, on the holding surface of the above-mentioned holding device, the convex portion comes into contact with the object, but the concave portion does not. Since there is no contact with the object and heat is transferred between the object and the holding device through the gas, This causes a difference in heat transfer between the two surfaces, resulting in uneven temperature distribution within the object. ,In the object, heat transfer is easy in the contact area with the convex part (directly above the convex part), Heat transfer is difficult in the non-contact area with the convex part (directly above the concave part). In the vicinity of the convex part, the gas in the concave part is easily heated (or cooled) due to the influence of heat transfer at the convex part. On the other hand, in areas away from the convex part, the influence of heat transfer at the convex part is almost nonexistent. Therefore, there is a difference in heat transfer between the area near the protrusion and the area far from the protrusion. In this way, a difference in heat transfer occurs between the holding device and the object on the holding surface. Therefore, the temperature on the surface of the object tends to become uneven, and the uniformity of the temperature on the surface decreases. It was closed.

[0005] Therefore, the present disclosure has been made to solve the above-mentioned problems, and the object of the present disclosure is to The object of the present invention is to provide a holding device capable of improving the uniformity of the temperature in the surface of an object. do. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the present disclosure is to a first surface on which a plurality of protrusions are formed, and a second surface provided on the opposite side of the first surface; a plate-like member having A holding device for holding an object on the first surface of the plate-like member, On the first surface, a bottom surface of the recessed portion other than the protruding portion, a first region that is a region that is located at a distance from the bottom side surface of the convex portion that is greater than a predetermined distance; a second region that is a region whose distance from the bottom side surface of the convex portion is within the predetermined distance, The surface roughness of the first region is greater than the surface roughness of the second region.

[0007] Comparing the first and second regions, the second region is the peripheral region of the convex portion, and therefore the The second area is affected by the heat transfer between the object and the recessed portion more than the first area. The heat transfer is promoted through the gas filled in the space between the first and second regions. Since the first and second regions are farther from the convex parts than the first region, the influence of heat transfer through the convex parts is small. If the surface roughness of the bottom surface of the first area is the same, the first area will be more closely shaped by the object and the recess than the second area. This is disadvantageous in terms of heat transfer via the gas filled in the space formed.

[0008] Therefore, in this holding device, the surface roughness of the first region is set to be larger than the surface roughness of the second region. Therefore, in the first region, the contact area between the plate-like member and the gas filled in the recess is large. This can promote heat transfer between the plate-like member and the gas filled in the recess. Therefore, in the non-contact portion with the convex portion of the object, the gas filling the concave portion is This promotes heat transfer between the plate-like member and the object. In the second region, the surface roughness is smaller than that of the first region, so the particles This can prevent the occurrence of the non-contact portion between the object and the convex portion (the first region of the concave portion). and the second region), the heat transfer between the plate-like member and the object is improved, so that the object The temperature in the contact area and non-contact area with the convex part (the first and second areas of the concave part) of the object This reduces uneven distribution and improves the uniformity of the temperature on the surface of the object. In both cases, the generation of particles can be suppressed.

[0009] In the above-mentioned holding device, The surface roughness of the first region is Ra(Sa) 1.0 μm or less, The surface roughness of the second region is preferably less than Ra(Sa) 0.5 μm. .

[0010] The larger the surface roughness, the more easily the recesses are filled between the object and the plate-like member. While this can promote heat transfer through the gas being filled, it may also generate particles. Therefore, by setting the surface roughness of the first and second areas in this way, This improves the uniformity of the temperature on the surface of the object while preventing particle generation. It is possible.

[0011] In the above-mentioned holding device, The size of the second region from the bottom side of the convex portion is 1 / 2 the distance between the adjacent convex portions. Preferably less than 3.

[0012] Here, if the size of the second region is set to 1 / 3 or more of the distance between adjacent convex portions, the bottom of the concave portion The majority of the surface becomes the second region, and the first region becomes very small. Promoting heat transfer through a gas filled in the space formed by the object and the recess This may make it difficult to improve the uniformity of the temperature on the surface of the object. There is a problem.

[0013] Therefore, the size of the second region is set to be smaller than 1 / 3 of the distance between adjacent convex portions. By setting the object so that the gas filling the space formed by the object and the recessed portion is This can reliably promote heat transfer through the protrusions and Heat transfer between the plate-shaped member and the non-contact portion (recess) is ensured through the gas filled in the recess. Therefore, the unevenness of the temperature distribution in the object is reduced, and the object This can reliably improve the in-plane temperature uniformity.

[0014] In the above-mentioned holding device, The vertical cross-sectional shape of the convex portion is preferably a trapezoid whose top dimension is smaller than its bottom dimension. It's nice.

[0015] By forming the convex portion in this shape, the area around the contact point with the convex portion on the object can be reduced. This makes it possible to make the temperature gradient of the object gentler. This can further improve the in-plane temperature uniformity. [Effects of the Invention]

[0016] According to the present disclosure, it is possible to improve the in-plane temperature uniformity of the object being held. A retaining device may be provided. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic perspective view of an electrostatic chuck according to a first embodiment. [Figure 2] 2 is a schematic configuration diagram of an XZ side surface (partly in cross section) of the electrostatic chuck of the first embodiment. FIG. [Figure 3] 1 is a schematic configuration diagram of an electrostatic chuck in an XY plane according to a first embodiment. [Figure 4] 4 is an enlarged view of an XZ cross section showing a part of the vicinity of a protrusion of a plate-like member. FIG. [Figure 5] 1A and 1B are diagrams for explaining factors that cause the in-plane temperature uniformity of a semiconductor wafer to decrease in a conventional structure. [Figure 6] 3A to 3C are diagrams illustrating a heat transfer state in the electrostatic chuck according to the first embodiment. [Figure 7] 10A and 10B are diagrams illustrating a heat transfer state in the electrostatic chuck according to the second embodiment. [Figure 8] FIG. 10 is an enlarged view of an XZ cross section showing a part of the electrostatic chuck in the vicinity of a protrusion according to a third embodiment; [Figure 9] 10A and 10B are diagrams illustrating modified examples of the electrostatic chuck according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] A holding device according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In this embodiment, the holding device is, for example, a film forming device (CVD film forming device or sputtering device) Semiconductor manufacturing equipment such as film deposition equipment and etching equipment (plasma etching equipment) An electrostatic chuck used in the device will be described as an example.

[0019] [First embodiment] First, an electrostatic chuck 1 according to a first embodiment will be described with reference to FIGS. The electrostatic chuck 1 of this embodiment attracts and holds a semiconductor wafer W (object) by electrostatic attraction. For example, it is a device for fixing a semiconductor wafer W in a vacuum chamber of a semiconductor manufacturing device. As shown in FIG. 1, the electrostatic chuck 1 includes a plate-shaped member 10 and a base The plate-shaped member has a base member and a bonding layer that bonds the plate-shaped member and the base member.

[0020] In the following description, for convenience of explanation, the X, Y, and Z axes are defined as shown in FIG. The Z axis is the axis in the axial direction of the electrostatic chuck 1 (the vertical direction in FIG. 1), and the X axis and the Y axis is the radial axis of the electrostatic chuck 1.

[0021] As shown in FIG. 1, the plate-like member 10 is a disk-like member made of ceramics. There are various ceramics used, but the strength and wear resistance are different. From the viewpoint of plasma resistance, for example, aluminum oxide (alumina, Al2O3) or It is preferable to use ceramics whose main component is aluminum nitride (AlN). The main component here is the component with the highest content (for example, a volume content of 90v ol% or more).

[0022] The diameter of the plate-shaped member 10 is, for example, about 150 to 300 mm. The thickness is, for example, about 2 to 6 mm. The thermal conductivity of the plate-like member 10 is 10 to 50 W. / mK (more preferably, 18 to 30 W / mK).

[0023] As shown in FIGS. 1 and 2, the plate-like member 10 has a holding surface 11 for holding a semiconductor wafer W, The plate-like member 10 is provided on the opposite side to the holding surface 11 in the thickness direction (the direction corresponding to the Z-axis direction). The holding surface 11 is an example of the "first surface" of the present disclosure. The lower surface 12 is an example of the "second surface" of the present disclosure.

[0024] As shown in FIG. 2, the plate-like member 10 is provided with a chuck electrode 50 and a heater electrode 52 inside. The chuck electrode 50 is, for example, substantially circular when viewed in the Z-axis direction, and is made of a conductive material. (For example, tungsten or molybdenum). The heater electrode 52 is When viewed in the axial direction, the conductive material (e.g., a tapered portion) is formed in a pattern extending in a substantially spiral shape. It is made of metals such as tungsten, molybdenum, and platinum.

[0025] Then, power is supplied to the chuck electrode 50 from a power source (not shown). Electrostatic attraction (adsorption force) occurs, and the semiconductor wafer W is held by the plate-like member 10 due to this electrostatic attraction force. The heater electrode 52 is fixed by suction to the support surface 11. Electric power is supplied to the heater electrode 52 from a power source (not shown). When the heater electrode 52 is heated, the holding surface 11 and the semiconductor wafer W are It is heated.

[0026] The holding surface 11 of the plate-like member 10 has an uneven shape. Specifically, the holding surface 11 has: As shown in FIGS. 2 and 3, an annular protrusion 16 is formed near the outer edge of the ring. A plurality of independent columnar protrusions 17 are formed inside the annular protrusion 16. The cross section (XZ cross section) of the annular protrusion 16 has the following shape, as shown in FIG. The height (dimension in the Z-axis direction) of such an annular protrusion 16 is, for example, 10 μm. The width of the annular protrusion 16 (the dimension in the X-axis direction) is, for example, 0. It is about 5mm to 5.0mm.

[0027] As shown in FIG. 3, each of the protrusions 17 has a substantially circular shape when viewed in the Z-axis direction (plan view), and is substantially uniform. The protrusions 17 are arranged at equal intervals. The cross section (XZ cross section) of each protrusion 17 has a shape as shown in FIG. The height of the protrusion 17 is approximately the same as the height of the annular protrusion 16. The width of the protrusions 17 (the width of the protrusions 17 as viewed in the Z-axis direction) is, for example, about 10 to 20 μm. The maximum diameter of the protrusions 17 is, for example, about 0.5 to 1.5 mm. The distance B (see FIG. 4) is about 10 mm. The area inside the annular protrusion 16 where the protrusion 17 is not formed is a recess 18. There are.

[0028] As shown in FIG. 3, the plate-shaped member 10 has a lift pin penetrating the electrostatic chuck 1 in the Z-axis direction. The lift pin insertion hole 30 is formed on the support surface 11. An annular protrusion 30a is formed around the lift pin insertion hole 30. The insertion holes 30 are fitted with lift pins (not shown) that push up the semiconductor wafer W from above the holding surface 11. The lift pin is inserted from the lower surface 22 side of the base member 20. The plate-shaped member 10 is placed on the holding surface 11 by projecting outward from the holding surface 11. The semiconductor wafer W is separated from the holding surface 11 (the semiconductor wafer W is held by the lift pins). (raise).

[0029] In the electrostatic chuck 1 of this embodiment, three lift pin insertion holes 30 are formed, each of which is The lift pins are inserted into the lift pin insertion holes 30. The holes 30 are formed at equal intervals in the circumferential direction of the electrostatic chuck 1 (see FIG. 3).

[0030] 3, the plate-shaped member 10 has a gas penetrating the electrostatic chuck 1 in the Z-axis direction. The gas hole 31 is formed through which an inert gas (e.g., helium gas) is blown. This allows gas to flow from the lower surface 22 of the base member 20 into the gas hole 31. By supplying an inert gas (e.g., helium gas), the lower surface of the semiconductor wafer W and the plate-shaped portion The inert gas can be filled into the space S between the holding surface 11 (recess 18) of the material 10. It is now possible to do so.

[0031] The semiconductor wafer W is then held by the annular protrusion 16 on the holding surface 11 of the plate-like member 10 and the plurality of The semiconductor wafer is supported by the protrusions 17 and 30a and held by the electrostatic chuck 1. When the semiconductor wafer W is held by the electrostatic chuck 1, the surface (bottom surface) of the semiconductor wafer W and the plate-like member A space S exists between the holding surface 11 of the holder 10 (specifically, the recess 18 of the holding surface 11). (See FIG. 2.) An inert gas (e.g., helium) is introduced into this space S through a gas hole 31. Mugas) will be supplied.

[0032] Here, the top surfaces of the protrusions 16, 17, 30a on the holding surface 11 (or the side surfaces (in some cases) The peripheral surface is also mirror-finished. This allows the semiconductor wafer W and the protrusions 16, 17, and 30 a slides against the surface of the semiconductor wafer W and the surfaces of the protrusions 16, 17, and 30a, and the surfaces of the protrusions 16, 17, and 30a are finely scraped. This prevents the generation of particles (fine particles).

[0033] On the other hand, the bottom surface 18a of the recess 18 in the holding surface 11 is provided with the top surfaces of the protrusions 16, 17, and 30a. The surface roughness of the top and bottom surfaces is larger than that of the sides, forming two areas with different surface roughness. That is, as shown in FIG. 4, the distance from the bottom side surface BS of the protrusions 16, 17 (30a) The first region 181 is a region where the distance is greater than a predetermined distance A, and the bottom of the convex portion 16, 17 (30a) is and a second region 182, which is a region that is within a predetermined distance A from the side surface BS. Specifically, the second region 182 is formed around the protrusions 16 and 17 (30a). 0a), and the first region 181 is formed in the portion other than the second region 182. The bottom side surface BS of the protrusions 16, 17 (30a) is the same as the bottom side surface BS of the protrusions 16, 17 (30b). 0a) and the bottom surface 18a (second region 182) of the recess 18. The first region 181 and the second region 182 are subjected to polishing or polishing processes under different conditions. can be provided by sandblasting.

[0034] The size (width) of the protrusions 16, 17 (30a) of the second region 182 from the bottom side surface BS The predetermined distance A is set so that the in-plane temperature of the semiconductor wafer W has a desired temperature distribution. The distance B between adjacent convex portions (for example, 10 m in this embodiment) may be set appropriately. The distance B is set to be smaller than 1 / 3 of the base of the adjacent convex part. In this embodiment, it corresponds to the size (width) of the second region 182. The predetermined distance A is, for example, about 1 to 2 mm. , is larger than the surface roughness of the second region 182. For example, the surface roughness of the first region 181 is Ra(S a) 1.0 μm or less, and the surface roughness of the second region 182 is Ra(Sa) less than 0.5 μm. In this embodiment, for example, the surface roughness of the first region 181 is Ra(Sa) 0.8 The surface roughness in the second region 182 is Ra(Sa) 0.5 μm. The difference in surface roughness between the first region 181 and the second region 182 may be 0.1 μm or more. It is more preferable that the thickness is 0.3 μm or more.

[0035] There are two methods for measuring surface roughness: "contact measurement" and "non-contact measurement." The determination method can be based on the following measurements and measurements. Contact type: JIS B 0633:2001 Non-contact type: ISO25178

[0036] As shown in FIGS. 1 and 2, the base member 20 has an upper surface 21 and a thickness direction of the base member 20. (i.e., Z-axis direction) on the opposite side of the upper surface 21. The base member 20 is formed in a columnar shape. It is preferable that the material is made of a material such as a metal alloy, but it may be made of a material other than metal.

[0037] The diameter of the base member 20 is, for example, about 180 mm to 350 mm. The thickness of the member 20 (the dimension in the Z-axis direction) is, for example, about 20 mm to 50 mm. The thermal conductivity of the glass member 20 (assumed to be aluminum) is higher than that of the plate-like member 10, and is 180 to It is desirable that the range be 250 W / mK (preferably, about 230 W / mK).

[0038] The base member 20 is provided with a cooling medium (e.g., a fluorine-based inert liquid, water, etc.) for flowing therethrough. A coolant flow path (not shown) is formed, and by flowing the coolant through this coolant flow path, the base The member 20 is cooled, and thereby the plate-like member 10 is cooled via the bonding layer 40. It has become.

[0039] The bonding layer 40 is disposed between the lower surface 12 of the plate-like member 10 and the upper surface 21 of the base member 20. , the plate-shaped member 10 and the base member 20 are bonded together via the bonding layer 40. The lower surface 12 of the base member 10 and the upper surface 21 of the base member 20 are thermally connected to each other. For example, it is made of adhesive materials such as silicone resin, acrylic resin, and epoxy resin. The thickness of the bonding layer 40 (the dimension in the Z-axis direction) is, for example, about 0.1 to 1.0 mm. The thermal conductivity of the bonding layer 40 is, for example, 1.0 W / mK. (Silicone resin is assumed) thermal conductivity is 0.1 to 2.0 W / mK (preferably 0. It is desirable to keep the range of 1.5 to 1.5 W / mK.

[0040] Here, in the holding surface 11 of the electrostatic chuck 1 of this embodiment, the convex portions 16, 17, 30a Therefore, a difference occurs in the heat transfer between the semiconductor wafer W and the plate-like member 10 between the upper surface and the recessed portion 18. That is, the protrusions 16, 17, and 30a are in direct contact with the semiconductor wafer W, Heat transfer is facilitated between the wafer W and the plate-like member 10. On the other hand, in the recess 18, the semiconductor wafer Since the semiconductor wafer W does not come into contact with the recess 18 (space S), the gas filling the recess 18 (space S) causes the semiconductor wafer W to Since heat is exchanged between the plate-like member 10 and the plate-like member 10, heat transfer between them becomes difficult. In the conventional electrostatic chuck, as shown in FIG. 5, the protrusions 16 and 1 In the vicinity of the protrusions 16, 17, and 30a, heat transfer occurs at the protrusions 16, 17, and 30a. , 17, 30a, the recess 18 other than the recess 18 between the semiconductor wafer W and the plate-like member 10 In other words, the heat transfer between the recessed portion where the plate-like member 10 and the semiconductor wafer W are not in contact with each other is promoted. In the portion 18, there is also a difference in heat transfer.

[0041] Therefore, on the holding surface of the conventional electrostatic chuck, the semiconductor wafer W and the plate-like member 10 The order of ease of heat transfer between the protrusions 16, 17, 30a and the protrusion 1 of the recess 18 is 6, 17, 30a (near the second region 182), from the protrusions 16, 17, 30a of the recess 18 The protrusions 16, 17, 30a are arranged in the order of the distant portions (near the first region 181). The area far from the first region 181 (near the first region 181) is the most unfavorable region for heat transfer. As described above, in the conventional electrostatic chuck, the holding surface is between the semiconductor wafer W and the plate-like member 10. Since there is a difference in heat transfer between the wafers, a temperature difference is likely to occur in the semiconductor wafer W, resulting in an in-plane temperature difference. was prone to becoming uneven.

[0042] Therefore, in the electrostatic chuck 1 of this embodiment, the surface roughness of the bottom surface 18a of the recessed portion 18 is set to be equal to or less than that of the protruding portion 18b. 16, 17, 30a, and the bottom surface 18a of the recess 18 is larger than the top surface and side surface of the recess 18. The second region 182, which has a surface roughness smaller than that of the first region 181, is formed around the protrusions 16, 17, and 30a. The recess 18 is formed in a ring shape so as to surround the protrusions 16, 17, and 30a. Since the contact area with the gas filled in the recess 18 (space S) is increased, As a result, the heat transfer between the gas filling the recess 18 and the gas filling the recess 18 is promoted. Heat transfer between the plate-like member 10 and the semiconductor wafer W via the gas is promoted.

[0043] The surface roughness of the first region 181 is set to be greater than the surface roughness of the second region 182. Therefore, as shown in FIG. 6, the recessed portion 18 (void) is formed in the first region 181 where heat transfer is most unfavorable. The contact area with the gas filled in the space S) is larger than that of the second region 182. In the first region 181, the plate-like member 10 and the semiconductor wafer are bonded to each other through the gas filled in the recess 18. In this way, the heat transfer between the holding surface 11 and the W is further promoted. The plate-like portion is a portion that is not in contact with the semiconductor wafer W and is formed through the gas filled in the recess 18 (space S). The heat transfer between the material 10 and the semiconductor wafer W is improved. Therefore, the heating is uniform in the area not in contact with the protrusions 16, 17, and 30a (the area directly above the recess 18). Therefore, the protrusions 16, 17, and 30a on the semiconductor wafer W are uniformly and efficiently removed. the heat in the contact portion and the non-contact portion (the first region 181 and the second region 182 of the recess 18). This reduces the difference in the temperature of the semiconductor wafer W. This can reduce the temperature difference and improve the temperature uniformity within the surface.

[0044] Here, the larger the surface roughness of the bottom surface 18a of the recess 18, the more easily the gas fills the recess 18. The heat transfer between the semiconductor wafer W and the plate-like member 10 can be promoted through the gap. However, the possibility of particles being generated increases. In the first embodiment, the surface roughness of the first region 181 is set to Ra(Sa) 1.0 μm or less, and the surface roughness of the second region 182 is set to Ra(Sa) 1.0 μm or less. The surface roughness Ra(Sa) of each of the 82 is set to less than 0.5 μm. This prevents the generation of particles, and the temperature in the surface of the semiconductor wafer W In particular, the projections 16, In the second region 182, which is susceptible to heat transfer in the regions 17 and 30a, the surface roughness is Since it is smaller than the first region 181, it is possible to effectively suppress the generation of particles. can.

[0045] In the electrostatic chuck 1 of this embodiment, the convex portions 16, 17, and 30a of the second region 182 The predetermined distance A from the bottom side surface BS of the second region 182 (i.e., the size of the second region 182) is The distance B between the recess 18 and the recess 17 is set to be smaller than one-third of the distance B between the recess 18 and the recess 17. The majority of the bottom surface 18a becomes the second region 182, and the first region 181 becomes very small. Therefore, in the first region 181 where heat transfer is most unfavorable, the semiconductor wafer W and the recessed portion 18 As a result, the heat transfer between the gas filled in the recess 18 and ... In this case, heat transfer between the plate-like member 10 and the semiconductor wafer W occurs via the gas filled in the recess 18. This reliably reduces the temperature difference in the semiconductor wafer W. Therefore, the temperature uniformity within the surface of the semiconductor wafer W can be reliably improved.

[0046] As described above, according to the electrostatic chuck 1 of this embodiment, the bottom surface of the recess 18 is 18a, a first region 181 and a region that is visible from the first region 181 around the protrusions 16, 17, and 30a. The recess 18 has a second region 182 with a small surface roughness. In the second region 181, the contact area with the gas filling the recess 18 is larger than that in the second region 182. Therefore, heat transfer between the semiconductor wafer W and the gas filled in the recess 18 is promoted. In the recess 18, which is a non-contact portion between the semiconductor wafer W and the protrusions 16, 17, and 30a, The heat transfer between the plate-like member 10 and the semiconductor wafer W is improved. Temperature distribution in the contact and non-contact areas of the wafer W with the protrusions 16, 17, 30a Since the non-uniformity of the temperature is reduced, the temperature uniformity in the surface of the semiconductor wafer W can be improved. In addition, the second region 1 is easily affected by the heat transfer in the protrusions 16, 17, and 30a. In the first region 82, the surface roughness is smaller than that of the first region 181, so that the particles The occurrence can be effectively suppressed.

[0047] [Second embodiment] Next, a second embodiment will be described with reference to FIG. 7. The second embodiment is a modification of the first embodiment. The basic configuration is the same as that of the first embodiment, but the second embodiment differs from the first embodiment in that it does not include a heater electrode. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof will be omitted as appropriate. The following description will focus on the differences from the first embodiment.

[0048] In the electrostatic chuck 1a of this embodiment, as shown in FIG. 7, a heater is provided inside the plate-shaped member 10. There is no electrostatic chuck electrode, and only the chuck electrode 50 is provided. , the semiconductor wafer W cannot be heated, and the semiconductor wafer W is cooled (semiconductor wafer W In such an electrostatic chuck 1a, for example, During the process, heat is removed from the semiconductor wafer W that has been heated by the heat input from the plasma. The semiconductor wafer W is cooled by this.

[0049] In this electrostatic chuck 1a, the surface roughness of the bottom surface 18a of the recess 18 is set to be equal to that of the protrusions 16, 17, and 30. a, and the bottom surface 18a of the recess 18 is larger than the first region 181. The second region 182 having a small surface roughness is formed around the protrusions 16, 17, and 30a. The surface roughness of the first region 181 is set to be equal to that of the second region 30a. 7, the surface roughness of the area 182 is larger than that of the area 183. In the first region 181, the contact area with the gas filled in the recess 18 (space S) is As a result, in the first region 181, the gas filling the recess 18 becomes larger than the gas filling the recess 18. This further promotes heat transfer between the plate-like member 10 and the semiconductor wafer W via the gap.

[0050] Therefore, in the holding surface 11, the recess 18 (space S) is formed in the portion not in contact with the semiconductor wafer W. The heat transfer between the plate-like member 10 and the semiconductor wafer W is improved through the gas filled in the That is, in the semiconductor wafer W, the portions (depressions) that are not in contact with the protrusions 16, 17, and 30a are Therefore, the semiconductor wafer W is cooled uniformly and efficiently in the area directly above the portion 18. In this case, the contact portion with the protrusions 16, 17, and 30a and the non-contact portion (the first region 181 of the recess 18) are and the second region 182), the difference in heat transfer (amount of heat drawn) can be reduced. This makes it possible to reduce the temperature difference in the semiconductor wafer W and improve the temperature uniformity within the surface. It can be raised.

[0051] Here, when the heater electrode 52 is provided in the electrostatic chuck 1 as in the first embodiment, the semiconductor When the temperature in the wafer W is not uniform, the heater electrode 52 can be adjusted by adjusting its position and resistance. It is possible to adjust the in-plane temperature by using the electrostatic chuck 1a of this embodiment. If a heater electrode is not provided, the temperature can be controlled by such a heater electrode. Therefore, when the electrostatic chuck 1a of this embodiment does not have a heater electrode, By adopting such a configuration, it is possible to make the temperature uniform within the surface of the semiconductor wafer W. It becomes Noh.

[0052] [Third embodiment] Next, a third embodiment will be described with reference to FIG. 8. The third embodiment is a modification of the first embodiment. The basic configuration is the same as that of the first embodiment, but the shape of the convex portion is different from that of the first embodiment. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof is omitted as appropriate. This article will focus on the differences between the two.

[0053] In the electrostatic chuck 1b of this embodiment, as shown in FIG. 8, the holding surface 11 of the plate-shaped member 110 The cross section (XZ cross section) of the annular protrusion 116 and the protrusion 117 is trapezoidal rather than rectangular. That is, the cross section (XZ cross section) of the annular protrusion 116 has an upper surface dimension of The trapezoidal shape is smaller than the bottom side dimension. The shape of the cross section (XZ cross section) of each protrusion 117 is a trapezoidal shape with only the surface being inclined. The shape of the protrusion 11 is a trapezoid whose upper surface dimension is smaller than its bottom surface dimension. The entire peripheral surface (side surface) of the projections 116 and 117 is an inclined surface. The area (area) is the same as that of the protrusions 16 and 17 in the first embodiment. The bottom side surface BS of the convex portions 116 and 117 is the side surface of the concave portion 18 of the convex portions 116 and 117. This is the portion that connects to the bottom surface 18a (second region 182).

[0054] In addition to the same effects as those of the first embodiment, the electrostatic chuck 1b has the following advantages: In the semiconductor wafer W, the temperature distribution around the contact portion with the protrusions 116 and 117 is This allows the temperature gradient to be gentle. The temperature change occurring at the boundary between the contact area with the protrusions 116 and 117 and the non-contact area is reduced. Therefore, the temperature uniformity within the surface can be further improved.

[0055] <Modification> Here, a modification of the above embodiment will be described with reference to FIG. In the first to third embodiments, the bottom surface 18a of the recess 18 is flat, that is, the first region 1 9, there is no step at the boundary between the first region 81 and the second region 182. A step may be formed at the boundary between the region 181 and the second region 182. At the boundary between the first region 181 and the second region 182, the surface roughness is large on the bottom surface 18a of the recess 18. The second region 182 having a larger surface roughness is the lower region, and the first region having a smaller surface roughness is the upper region. Although FIG. 9 shows an example of a convex portion having a substantially rectangular cross section, The cross-sectional shape of the convex portion may be trapezoidal as in the second embodiment. The bottom side surface BS of the reference convex portion 16, 17 (30a) is the side of the convex portion 16, 17 (30a). This is the portion of the surface that connects to the upper portion (second region 182) of the bottom surface 18a of the recess 18.

[0056] It should be noted that the above-described embodiments are merely examples and do not limit the present disclosure in any way. Of course, various improvements and modifications are possible within the scope of the present invention. For example, in the above embodiment, the present disclosure is applied to an electrostatic chuck. This is not limited to electrostatic chucks, but is applicable to all holding devices that hold objects on their surfaces. It is possible.

[0057] In the above embodiment, the electrostatic chuck is provided with a base member. The present disclosure can also be applied to a holding device that does not include a material (for example, a ceramic heater, etc.). In the case where a heater electrode is provided in a holding device without such a base member, The support member may be built into the plate-like member, or may be attached to the lower surface (opposite to the holding surface) without being built into the plate-like member. The surface may be provided on the side of the casing. [Explanation of symbols]

[0058] 1. Electrostatic chuck 10 Plate-shaped member 11 Holding surface 12 Bottom side 16 Annular convex part 17 Convex part 18 Recess 18a bottom 30a convex part 40 Bonding layer 181 First area 182 Second area A. Predetermined distance (size of second area) B Distance between adjacent convex parts BS bottom side W Semiconductor wafer

Claims

1. a first surface on which a plurality of protrusions are formed, and a second surface provided on the opposite side of the first surface; a plate-like member having A holding device for holding an object on the first surface of the plate-like member, On the first surface, a bottom surface of the recess other than the protrusion, a first region that is a region that is located at a distance from the bottom side surface of the convex portion that is greater than a predetermined distance; a second region that is a region whose distance from the bottom side surface of the convex portion is within the predetermined distance, The surface roughness of the first region is greater than the surface roughness of the second region. A holding device characterized by:

2. 2. The holding device according to claim 1, The surface roughness of the first region is Ra (Sa) 1.0 μm or less, The surface roughness of the second region is less than Ra(Sa) 0.5 μm. A holding device characterized by:

3. The holding device according to claim 1 or 2, The predetermined distance is smaller than 1 / 3 of the distance between adjacent protrusions. A holding device characterized by:

4. In any one of the holding devices according to claims 1 to 3, The vertical cross-sectional shape of the convex portion is a trapezoid whose top dimension is smaller than its bottom dimension. A holding device characterized by:

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