Holding member and electrostatic chuck

Abstract

To provide a holding member and an electrostatic chuck capable of suppressing further particle shedding from a protrusion or wafer due to shedding particles.SOLUTION: A holding member for holding an object has a holding surface which is the surface that holds the object, a convex portion and a concave portion are formed on the holding surface, and a groove portion is formed on the top surface which defines the apex of the convex portion.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] There is known an electrostatic chuck that includes a holding member that holds a target object, a wafer, by electrostatic attraction. Patent Documents 1 to 3 disclose electrostatic chucks in which a convex portion on which the wafer is placed is formed on the holding surface of the holding member that holds the target object. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3784274 [Patent Document 2] Patent No. 4417197 [Patent Document 3] JP 2002-222851 A Summary of the Invention [Problem to be solved by the invention]

[0004] Contact between the protrusion and the wafer may cause particles to fall off from the protrusion or the wafer. The particles thus fallen off may be caught between the protrusion and the wafer and cause stress concentration, which may promote further particle falling off from the protrusion or the wafer. The electrostatic chucks disclosed in Patent Documents 1 to 3 do not take this into consideration at all. For this reason, there has been a demand for a technology that can suppress further particle falling off from the protrusion or the wafer due to the fallen particles.

[0005] The present invention has been made to solve at least some of the above-mentioned problems, and aims to provide a holding member and an electrostatic chuck that can suppress the occurrence of further particle shedding from protrusions or wafers due to shedding particles. [Means for solving the problem]

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following forms. (1) According to one aspect of the present invention, there is provided a holding member for holding an object, the holding member having a holding surface which is a surface on the side that holds the object, a convex portion and a concave portion formed on the holding surface, and a groove portion formed on a top surface that defines the top of the convex portion.

[0007] According to this configuration, a groove is formed on the top surface that defines the top of the convex portion. Therefore, when the holding member and the wafer thermally expand with different thermal expansion coefficients, the shed particles rolling on the top surface of the convex portion can fall into the groove. Therefore, the shed particles rolling between the convex portion and the wafer can be removed, and further shed particles from the convex portion or the wafer due to the shed particles can be suppressed. As a result, the durability of the holding member can be improved.

[0008] (2) In the holding member of the above aspect, at least one of the grooves may extend to an end of the top surface. According to this configuration, the shed particles that have fallen into the groove can be discharged from the end of the top surface, thereby preventing the groove from becoming filled with the accumulated shed particles.

[0009] (3) In the holding member of the above aspect, at least one of the grooves may be formed in a straight line extending in a direction perpendicular to an imaginary line passing through the center of the holding surface and the center of the top surface. Since the top surface thermally expands in a direction generally along the imaginary straight line, the direction in which the shed particles roll on the top surface also generally along the imaginary straight line. With this configuration, it is possible to increase the likelihood that the shed particles will fall into the groove portion.

[0010] (4) In the retaining member of the above form, when looking at the retaining surface from the side facing the retaining surface, one of the convex portions and another of the convex portions are arranged closer to the center of the retaining surface than the first of the convex portions, and the proportion of the total area of ​​the groove portions on the top surface of the one of the convex portions may be greater than the proportion of the total area of ​​the groove portions on the top surface of the other of the convex portions. The further away from the center of the holding surface when viewed from the side facing the holding surface, the greater the difference in the degree of expansion when the holding member and the wafer thermally expand with different thermal expansion coefficients. In other words, the further away from the center of the holding surface the protrusion is, the greater the amount of friction at the contact portion between the protrusion and the wafer, making it more likely that a large number of shed particles will be generated. With this configuration, the proportion of the total area of ​​the grooves on the top surface of one protrusion is greater than that of the other protrusion, so that appropriate proportions of grooves can be arranged on the top surface of each of the other protrusion and the one protrusion according to the amount of shed particles generated.

[0011] (5) In the retaining member of the above form, when the retaining surface is viewed from the side facing the retaining surface, and the top surface of at least a part of the convex portion is divided into two regions by a virtual perpendicular line passing through the center of the top surface and extending in a direction perpendicular to a virtual straight line passing through the center of the retaining surface and the center of the top surface, the proportion of the total area of ​​the groove portions in the region farther from the center of the retaining surface may be greater than the proportion of the total area of ​​the groove portions in the region closer to the center of the retaining surface. When the holding surface is viewed from the side facing the holding surface, the difference in the degree of expansion when the holding member and the wafer thermally expand with different thermal expansion coefficients inevitably becomes larger in the region of the top surface of the convex portion that is farther from the center of the holding surface. In other words, the amount of friction at the contact portion between the convex portion and the wafer increases in the region of the top surface that is farther from the center of the holding surface, so that many shed particles are likely to be generated. With this configuration, the ratio of the total area of ​​the grooves to the region farther from the center of the holding surface is larger than that of the region closer to the center of the holding surface, so that grooves can be arranged in an appropriate ratio according to the expected amount of shed particles to be generated in each region.

[0012] (6) In the holding member of the above embodiment, at least one of the grooves may have an opening edge that has a cross-sectional shape of a C-surface or an R-surface. According to this configuration, it is possible to suppress chipping at the opening edge of the groove, and therefore it is possible to suppress the generation of particles from the opening edge.

[0013] (7) In the holding member of the above aspect, when the holding surface is viewed from the side facing the holding surface, at least one of the groove portions may be formed in a convex arc shape toward an outer edge of the holding surface. Since the holding surface thermally expands radially from the center, the direction in which the shed particles roll on the top surface is also generally radial, so this configuration increases the likelihood that the shed particles will fall into the groove.

[0014] (8) According to another aspect of the present invention, there is provided an electrostatic chuck comprising the holding member according to the above aspect and an electrostatic electrode that generates an electrostatic attractive force on the holding surface. According to this configuration, when power is supplied to the electrostatic electrode, an electrostatic attraction (adsorption force) is generated, and the electrostatic attraction force can hold the target object on the holding surface side. In addition, since a groove is formed on the top surface of the protrusion, it is possible to provide an electrostatic chuck that improves the durability of the holding member by suppressing further particle shedding from the protrusion or the wafer due to the shedding particles.

[0015] The present invention can be realized in various forms, for example, in the form of a holding member, an electrostatic chuck, a vacuum chuck, a ceramic heater, a semiconductor manufacturing apparatus, parts including these, and methods of manufacturing these. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is an explanatory diagram showing an electrostatic chuck including a holding member according to a first embodiment. [Diagram 2]FIG. 4 is an explanatory diagram showing the holding surface as viewed from the side facing the holding surface. [Diagram 3] FIG. [Figure 4] 1 is an explanatory diagram showing a cross section of a groove portion G. FIG. [Diagram 5] 13 is an explanatory view showing a convex portion formed on a holding surface of a holding member of a second embodiment. FIG. [Figure 6] 13 is an explanatory view showing a convex portion formed on a holding surface of a holding member according to a third embodiment. FIG. [Figure 7] 13 is an enlarged view of a protrusion formed on a holding surface of a holding member according to a fourth embodiment. FIG. [Figure 8] 13 is an explanatory view showing a convex portion formed on a holding surface of a holding member according to a fifth embodiment. FIG. [Figure 9] 13 is an enlarged view of a protrusion formed on a holding surface of a holding member according to a sixth embodiment. FIG. [Figure 10] 13 is an explanatory view showing a convex portion formed on a holding surface of a holding member according to a seventh embodiment. FIG. [Figure 11] 13 is an enlarged view of a protrusion formed on a holding surface of a holding member according to an eighth embodiment. FIG. [Figure 12] 13 is an explanatory diagram showing a groove portion of a modified example. FIG. [Figure 13] 13 is an explanatory diagram showing a groove portion of a modified example. FIG. [Figure 14] 13 is an explanatory diagram showing a groove portion of a modified example. FIG. [Figure 15] 13 is an explanatory diagram showing a groove portion of a modified example. FIG. [Figure 16] 13 is an explanatory diagram showing a groove portion of a modified example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] First Embodiment FIG. 1 is an explanatory diagram showing a schematic cross-sectional configuration of an electrostatic chuck 1 including a holding member 10 according to a first embodiment. FIG. 1 shows X, Y and Z axes which are orthogonal to each other. These X, Y and Z axes are also shown in FIG. 2. The electrostatic chuck 1 is a device that attracts and holds a target object, a wafer W, by electrostatic attraction. The arrow shown in FIG. 1 indicates the direction in which the wafer W is attracted to the electrostatic chuck 1. The electrostatic chuck 1 is used, for example, to fix the wafer W in a vacuum chamber of a semiconductor manufacturing device. The electrostatic chuck 1 includes a holding member 10 and an electrostatic electrode 30.

[0018] The holding member 10 is a disk-shaped member and is formed with ceramic as the main component. The main component refers to the component with the highest volume content. Examples of the constituent material of the holding member 10 include aluminum oxide (alumina) and aluminum nitride, and in this embodiment, it is alumina. The holding member 10 has a holding surface 10f and a back surface 10b. The holding surface 10f is a circular surface on the side that holds the wafer W. The back surface 10b is a circular surface located on the opposite side to the holding surface 10f. The holding surface 10f is formed with an annular protrusion 12, a plurality of protrusions 14, and a plurality of recesses 16.

[0019] FIG. 2 is an explanatory diagram showing the holding surface 10f as viewed from the side facing the holding surface 10f (the +Z-axis direction side). The annular convex portion 12 is formed along the outer edge of the holding surface 10f. Each of the convex portions 14 is formed inside the annular convex portion 12. Each of the convex portions 14 is generally arranged regularly from the center O of the holding surface 10f. For example, as shown in FIG. 2, in the holding member 10 of the first embodiment, each of the convex portions 14 is arranged radially. The concave portions 16 are formed between the convex portions 14. In other words, the formation position of the concave portions 16 corresponds to a position inside the annular convex portion 12 where no convex portion 14 is formed.

[0020] 1, the protrusion 14 is defined by a side surface S and a top surface T. The side surface S is a surface that defines the side of the protrusion 14. The top surface T is a surface that defines the top of the protrusion 14.

[0021] A plurality of through-flow passages 22 are formed inside the holding member 10. Each of the through-flow passages 22 is a passage that penetrates between the holding surface 10f and the back surface 10b, and is a passage for supplying an inert gas, such as helium gas, supplied from the back surface 10b side to the holding surface 10f side. The through-flow passages 22 are connected to the recess 16 on the holding surface 10f side.

[0022] The electrostatic electrode 30 is a disk-shaped member provided inside the holding member 10, and is made of a conductive material such as tungsten or molybdenum. The electrostatic electrode 30 generates an electrostatic attractive force on the holding surface 10f when power is supplied from an external power source (not shown). The wafer W is attracted toward the holding surface 10f by this electrostatic attractive force, and is thereby held on the holding surface 10f.

[0023] When electrostatic attraction is generated on the holding surface 10f, the wafer W is held on the holding surface 10f by contacting with the annular convex portion 12 and the convex portion 14. In a state in which the wafer W is placed on such an annular convex portion 12 and the convex portion 14, inert gas is supplied between the wafer W and the holding surface 10f to increase thermal conductivity between the wafer W and the holding surface 10f. In detail, the inert gas is supplied from the rear surface 10b side through the through-flow passage 22 to the holding surface 10f side from the recess 16. The inert gas supplied to the holding surface 10f side flows through the space between the wafer W and the recess 16 and diffuses throughout the space.

[0024] In addition to the electrostatic electrode 30, a plurality of heater electrodes (not shown) made of a conductive material such as tungsten or molybdenum are provided inside the holding member 10. The heater electrodes generate heat using power supplied from an external power source (not shown), thereby warming the wafer W held by the holding member 10. The heating of the wafer W by such heater electrodes is performed because there is a risk of the accuracy of each process (film formation, etching, etc.) on the wafer W decreasing if the temperature of the wafer W does not reach a desired temperature.

[0025] FIG. 3 is an explanatory diagram showing an enlarged view of one of the plurality of protrusions 14 formed on the holding surface 10f. The protrusion 14 shown in FIG. 3 is the protrusion 14 seen from the side facing the holding surface 10f (the +Z-axis direction side) as in FIG. 2. That is, FIG. 3 shows the protrusion 14 seen from the side facing the top surface T. Grooves G1 to G5 are formed on the top surface T. The grooves G1 to G5 are formed in a straight line extending in a direction perpendicular to the imaginary straight line IL passing through the center O of the holding surface 10f (see FIG. 2) and the center TO of the top surface T. Furthermore, the grooves G1 to G5 extend to the end of the top surface T. In this embodiment, the widths of the grooves G1 to G5 are the same, and the intervals between the grooves G1 to G5 (the distance between adjacent grooves among the grooves G1 to G5) are approximately equal. Hereinafter, the grooves formed on the top surface T of the protrusion 14 will be collectively referred to as grooves G.

[0026] FIG. 4 is an explanatory diagram showing a cross section of the groove G taken along the line F4-F4 in FIG. 3. The cross section of the groove G is a cross section perpendicular to the direction in which the groove G extends. The opening edge EG shown in FIG. 4 is the edge of the opening OP of the groove G. As shown in FIG. 4, the cross section of the opening edge EG is a C-plane shape. The width WD of the groove G is preferably 90% or more of the crystal grain diameter (Scherrer diameter) of the ceramic constituting the holding member 10. The crystal grain diameter is calculated from the half-width of the X-ray diffraction peak by the Scherrer formula. In addition, the depth DP of the groove G is preferably 90% or more of the crystal grain diameter (Scherrer diameter) of the ceramic constituting the holding member 10 and is equal to or less than the height of the convex portion 14, from the viewpoint of suppressing chipping or cracking of the convex portion 14. In this embodiment, all the grooves G formed on the top surfaces T of all the convex portions 14 are the grooves G as described in FIGS. 3 and 4. In other embodiments, all of the groove portions G formed on the top surfaces T of some of the protrusions 14 are groove portions G as described in Figures 3 and 4, and the groove portions G formed on the top surfaces T of the other protrusions 14 may include groove portions G different from the groove portions G as described in Figures 3 and 4 in addition to the groove portions G as described in Figures 3 and 4, or may only include groove portions G different from the groove portions G as described in Figures 3 and 4.

[0027] Contact between the protrusion 14 and the wafer W may cause grains to fall off from the protrusion 14 or the wafer W. Such grains may also occur when the holding member 10 holds the wafer W, and the holding member 10 and the wafer W expand at different thermal expansion rates due to heating by the heater electrode, causing friction at the contact portion between the protrusion 14 and the wafer W. The thermal expansion of the holding member 10 is, as explained with reference to FIG. 2, an expansion that spreads radially from the center O in the XY plane. The same applies to the thermal expansion of the wafer W. The shed grains may be sandwiched between the protrusion 14 and the wafer W, concentrating stress, thereby promoting further grains to fall off from the protrusion 14 or the wafer W. The shed grains may also be rolled on the top surface T due to the thermal expansion of the protrusion 14 and the wafer W, which have different thermal expansion rates, and thus promoting further grains to fall off.

[0028] In this regard, according to the holding member 10 of the first embodiment, a groove portion G is formed in the top surface T that defines the top of the protrusion 14. Therefore, when the holding member 10 and the wafer W thermally expand with different thermal expansion coefficients, the shed particles rolling on the top surface T can be dropped into the groove portion G. Therefore, the shed particles caught between the protrusion 14 and the wafer W can be removed, and further shed particles from the protrusion 14 or the wafer W due to the shed particles can be suppressed. As a result, the durability of the holding member 10 can be improved.

[0029] According to the holding member 10 of the first embodiment, the groove portion G is formed in a straight line extending in a direction perpendicular to the imaginary straight line IL, as shown in Fig. 3. The top surface T thermally expands in a direction generally along the imaginary straight line IL (strictly speaking, radially from the center O of the holding surface 10f), so the direction in which the shed particles roll on the top surface T is also generally along the imaginary straight line IL. For this reason, because the groove portion G is formed in a straight line extending in a direction perpendicular to the imaginary straight line IL, it is possible to increase the likelihood that the shed particles will fall into the groove portion G.

[0030] According to the holding member 10 of the first embodiment, as shown in Fig. 3, the groove portion G extends to the end of the top surface T. Therefore, the shed particles that have fallen into the groove portion G can be discharged from the end of the top surface T. This makes it possible to prevent the groove portion G from becoming filled with the accumulation of shed particles.

[0031] According to the holding member 10 of the first embodiment, the cross-sectional shape of the opening edge EG is a C-shaped surface, as shown in Fig. 4. This makes it possible to suppress chipping at the opening edge EG. This makes it possible to suppress particle generation from the opening edge EG.

[0032] Furthermore, according to the electrostatic chuck 1 of the present embodiment, an electrostatic attraction force (adsorption force) is generated by supplying power to the electrostatic electrode 30, and the wafer W can be held on the holding surface 10f side by this electrostatic attraction force. In addition, since the groove portion G is formed in the top surface T of the protrusion 14, it is possible to provide an electrostatic chuck 1 with improved durability of the holding member 10 by suppressing further particle shedding from the protrusion 14 or the wafer W due to the shedding particles.

[0033] <Second embodiment> FIG. 5 is an explanatory diagram showing three convex portions 14a1 to 14a3 among the convex portions 14 formed on the holding surface 10f of the holding member of the second embodiment. The holding member of the second embodiment is the same as the holding member 10 of the first embodiment, except that the groove portion G formed on the top surface T of the convex portion 14 is different from the holding member 10 of the first embodiment. Similarly, the following third to eighth embodiments are the same as the holding member 10 of the first embodiment, except that the groove portion G formed on the top surface T of the convex portion 14 is different from the holding member 10 of the first embodiment. That is, all of the embodiments are configured to be provided in an electrostatic chuck, similar to the holding member 10 of the first embodiment. The convex portions 14a1 to 14a3 shown in FIG. 5 are the convex portions 14a1 to 14a3 seen from the side facing the holding surface 10f (the +Z axis direction side), similar to the convex portion 14 shown in FIG. 3. In the description of the holding member of the second embodiment, the same components as those of the holding member 10 of the first embodiment are denoted by the same reference numerals, and the preceding description will be referred to (the same applies to the following third to eighth embodiments). When the holding surface 10f is viewed from the side facing the holding surface 10f, the convex portions 14a1 to 14a3 are arranged in the order of convex portion 14a1, convex portion 14a2, and convex portion 14a3 at positions close to the center O of the holding surface 10f (the convex portion 14a1 is arranged at the position closest to the center O of the holding surface 10f).

[0034] Grooves Ga1 to Ga5 are formed on the top surface Ta1 of the protrusion 14a1. Grooves Ga6 to Ga12 are formed on the top surface Ta2 of the protrusion 14a2. Grooves Ga13 to Ga21 are formed on the top surface Ta3 of the protrusion 14a3. The grooves Ga1 to Ga21 have the same width, but the intervals at which the grooves Ga1 to Ga5 are formed, the intervals at which the grooves Ga6 to Ga12 are formed, and the intervals at which the grooves Ga13 to Ga21 are formed are different. In detail, the intervals at which the grooves Ga6 to Ga12 are formed are narrower than the intervals at which the grooves Ga1 to Ga5 are formed, and the intervals at which the grooves Ga13 to Ga21 are formed are narrower than the intervals at which the grooves Ga6 to Ga12 are formed. That is, when viewing the holding surface 10f from the side facing the holding surface 10f, the ratio of the total area of ​​the grooves Ga6 to Ga12 to the top surface Ta2 of the protrusion 14a2 is greater than the ratio of the total area of ​​the grooves Ga1 to Ga5 to the top surface Ta1 of the protrusion 14a1. Also, when viewing the holding surface 10f from the side facing the holding surface 10f, the ratio of the total area of ​​the grooves Ga13 to Ga21 to the top surface Ta3 of the protrusion 14a3 is greater than the ratio of the total area of ​​the grooves Ga6 to Ga12 to the top surface Ta2 of the protrusion 14a2. Thus, in this embodiment, in all the protrusions 14 formed on the holding surface 10f, the ratio of the total area of ​​the grooves G to the top surface T of the protrusion 14 farther away from the center O of the holding surface 10f is greater. In other words, when the holding surface 10f is viewed from the side facing the holding surface 10f and the convex portion 14 closer to the center of the holding surface 10f than the one convex portion 14 is defined as the other convex portion 14, the ratio of the total area of ​​the groove portion G to the top surface T of the one convex portion 14 is larger than the ratio of the total area of ​​the groove portion G to the top surface of the other convex portion 14. Here, the ratio of the total area of ​​the groove portion G to the top surface T refers to the ratio of the total area of ​​the area where the groove portion G is formed to the area of ​​the top surface T (the entire area including both the area where the groove portion G is formed and the area where the groove portion G is not formed) when the holding surface 10f is viewed from the side facing the holding surface 10f. In FIG. 5, it refers to the ratio of the total area of ​​the linear portion representing the groove portion G to the area of ​​the circle representing the top surface T. In addition, from the viewpoint of ensuring an area of ​​the top surface T that comes into contact with the wafer W (an area in which the groove portions G are not formed), it is preferable that the total area of ​​the groove portions G on the top surface T be less than half the area of ​​the top surface T when viewed from the side facing the holding surface 10f.

[0035] When viewed from the side facing the holding surface 10f (in the field of view of FIG. 2), the difference in the degree of expansion between the holding member 10 and the wafer W due to thermal expansion with different thermal expansion coefficients inevitably becomes greater as the position of the holding surface 10f is farther from the center O. That is, the amount of friction at the contact portion between the convex portion 14 and the wafer W increases as the position of the convex portion 14 is farther from the center of the holding surface 10f, and therefore a large number of shed particles are likely to be generated. In this regard, according to the holding member of the second embodiment, the proportion of the area of ​​the groove portion G in the top surface T of the one convex portion 14 is larger than that of the other convex portion 14 (the convex portion 14 closer to the center of the holding surface 10f than the one convex portion 14), so that the groove portion G can be arranged in an appropriate proportion on the top surface T according to the expected amount of shed particles to be generated in each of the other convex portion 14 and the one convex portion 14.

[0036] <Third embodiment> Fig. 6 is an explanatory diagram showing three convex portions 14b1-14b3 among the convex portions 14 formed on the holding surface 10f of the holding member of the third embodiment. When the holding surface 10f is viewed from the side facing the holding surface 10f, the convex portions 14b1-14b3 are arranged at positions close to the center O of the holding surface 10f in the order of convex portion 14b1, convex portion 14b2, and convex portion 14b3, similar to the convex portions 14a1-14a3 shown in Fig. 5 (the convex portion 14b1 is arranged at the position closest to the center O of the holding surface 10f).

[0037] Grooves Gb1 to Gb5 are formed in the top surface Tb1 of the protrusion 14b1. Grooves Gb6 to Gb10 are formed in the top surface Tb2 of the protrusion 14b2. Grooves Gb11 to Gb15 are formed in the top surface Tb3 of the protrusion 14b3. The grooves Gb1 to Gb5 have the same width, the grooves Gb6 to Gb10 have the same width, and the grooves Gb11 to Gb15 have the same width. On the other hand, the widths of the grooves Gb1 to G5, the widths of the grooves Gb6 to Gb10, and the widths of the grooves Gb11 to Gb15 are different. In detail, the width of each of the grooves Gb6 to Gb10 is wider than the width of each of the grooves Gb1 to Gb5, and the width of each of the grooves Gb11 to Gb15 is wider than the width of each of the grooves Gb6 to Gb10. That is, when the holding surface 10f is viewed from the side facing the holding surface 10f, the ratio of the total area of ​​the grooves Gb6 to Gb10 to the top surface Tb2 of the convex portion 14b2 is greater than the ratio of the total area of ​​the grooves Gb1 to Gb5 to the top surface Tb1 of the convex portion 14b1. Also, when the holding surface 10f is viewed from the side facing the holding surface 10f, the ratio of the total area of ​​the grooves Gb11 to Gb15 to the top surface Tb3 of the convex portion 14b3 is greater than the ratio of the total area of ​​the grooves Gb6 to Gb10 to the top surface Tb2 of the convex portion 14b2. Thus, in this embodiment, among all the protrusions 14 formed on the retaining surface 10f, the protrusions 14 located farther from the center O of the retaining surface 10f have a larger proportion of the total area of ​​the grooves G in the top surface T. According to the retaining member of the third embodiment, as with the retaining member of the second embodiment, an appropriate proportion of grooves G can be arranged on the top surface T according to the amount of shed particles expected to be generated at each of the protrusions 14 depending on the distance from the center O of the retaining surface 10f.

[0038] <Fourth embodiment> FIG. 7 is an explanatory diagram showing an enlarged view of one of the protrusions 14c among the multiple protrusions 14 formed on the holding surface 10f of the holding member of the fourth embodiment. The protrusion 14c shown in FIG. 7 is the protrusion 14c as viewed from the side facing the holding surface 10f. Grooves Gc1 to Gc5 are formed on the top surface Tc of the protrusion 14c. In this embodiment, the widths of the grooves Gc1 to Gc5 are the same, but the intervals between the grooves Gc1 and Gc2 are wider than the intervals between the grooves Gc3 to Gc5. The imaginary perpendicular line IP is an imaginary perpendicular line that passes through the center TcO of the top surface Tc and extends in a direction perpendicular to the imaginary straight line IL that passes through the center O of the holding surface 10f and the center TcO of the top surface Tc as viewed from the side facing the holding surface 10f. When the top surface Tc is divided into two regions by this imaginary perpendicular line IP, the ratio of the total area of ​​the grooves G in the region F farther from the center O of the holding surface 10f is greater than the ratio of the total area of ​​the grooves G in the region N closer to the center O of the holding surface 10f. In FIG. 7, the ratio of the total area of ​​the grooves G in the region F or the region N refers to the ratio of the total area of ​​the linear portions representing the grooves G to the area of ​​the semicircle representing the region F or the region N. In this embodiment, in the top surfaces T of all the convex portions 14 formed on the holding surface 10f, the ratio of the total area of ​​the grooves G in the region F is greater than the ratio of the total area of ​​the grooves G in the region N. In other embodiments, a similar relationship may be established only in the top surfaces T of some of the convex portions 14 formed on the holding surface 10f.

[0039] When viewing the holding surface 10f from the side facing the holding surface 10f, the difference in the degree of expansion when the holding member 10 and the wafer W thermally expand with different thermal expansion coefficients inevitably becomes larger in a region of the top surface T of the protrusion 14 that is farther from the center O of the holding surface 10f. That is, the amount of friction at the contact portion between the protrusion 14 and the wafer W increases in a region of the top surface T that is farther from the center O of the holding surface 10f, and therefore many shed particles are likely to be generated. In this regard, according to the holding member of the fourth embodiment, the proportion of the total area of ​​the grooves G in region F is larger than that in region N, so that an appropriate proportion of the grooves G can be arranged on the top surface T according to the expected amount of shed particles to be generated in each region.

[0040] <Fifth embodiment> 8 is an explanatory diagram showing three convex portions 14d1 to 14d3 among the convex portions 14 formed on the holding surface 10f of the holding member of the fifth embodiment. When the holding surface 10f is viewed from the side facing the holding surface 10f, the convex portions 14d1 to 14d3 are arranged at positions close to the center O of the holding surface 10f in the order of convex portion 14d1, convex portion 14d2, and convex portion 14d3 (the convex portion 14d1 is arranged at the position closest to the center O of the holding surface 10f).

[0041] Grooves Gd1 to Gd5 are formed in the top surface Td1 of the protrusion 14d1. Grooves Gd6 to Gd11 are formed in the top surface Td2 of the protrusion 14d2. Grooves Gd12 to Gd18 are formed in the top surface Td3 of the protrusion 14d3. The grooves Gd1 to Gd18 have the same width. Meanwhile, the interval between the grooves Gd1 and Gd2 is wider than the interval between the grooves Gd3 to Gd5, the interval between the grooves Gd6 and Gd7 is wider than the interval between the grooves Gd8 to Gd11, and the interval between the grooves Gd12 and Gd13 is wider than the interval between the grooves Gd14 to Gd18.

[0042] When each of the top surfaces Td1 to Td3 is divided into two regions by a virtual perpendicular line IP similar to that of FIG. 7, the ratio of the total area of ​​the grooves G to the region Fd1 to Fd3 (regions farther from the center O of the holding surface 10f) is larger than that of the regions Nd1 to Nd3 (regions closer to the center O of the holding surface 10f). Also, the ratio of the total area of ​​the grooves G to the top surface T increases in the order of the convex portion 14d3, the convex portion 14d2, and the convex portion 14d1 (the ratio of the total area of ​​the grooves G to the top surface T is the largest for the convex portion 14d3). In this embodiment, the relationship described using the convex portions 14d1 to 14d3 holds for all the convex portions 14 formed on the holding surface 10f. According to the retaining member of the fifth embodiment, an appropriate proportion of grooves G can be arranged on the top surface T depending on both the amount of shed particles expected to be generated at each of the convex portions 14 based on the distance from the center O of the retaining surface 10f and the amount of shed particles expected to be generated in each region within the convex portion 14.

[0043] Sixth Embodiment Fig. 9 is an explanatory diagram showing an enlarged view of one protrusion 14e among the multiple protrusions 14 formed on the holding surface 10f of the holding member of the sixth embodiment. The protrusion 14e shown in Fig. 9 is the protrusion 14e seen from the side facing the holding surface 10f. Grooves Ge1-Ge6 are formed in the top surface Te of the protrusion 14e. The grooves Ge1-Ge3 each have the same width, and the grooves Ge4-Ge6 each have the same width, but the width of the grooves Ge1-Ge3 is different from the width of the grooves Ge4-Ge6.

[0044] When the top surface Te is divided into two regions by a virtual perpendicular line IP similar to those in FIGS. 7 and 8, the area ratio of the groove portion G to the region Fe (region farther from the center O of the holding surface 10f) is larger than that of the region Ne (region closer to the center O of the holding surface 10f). In this embodiment, in the top surfaces T of all the protrusions 14 formed on the holding surface 10f, the ratio of the total area of ​​the groove portion G to the region Fe is larger than the ratio of the total area of ​​the groove portion G to the region Ne. In other embodiments, the same relationship may be established only in the top surfaces T of some of the protrusions 14 formed on the holding surface 10f. In such a holding member of the sixth embodiment, the groove portion G can be arranged on the top surface T at an appropriate ratio according to the expected amount of shed particles in each region.

[0045] Seventh embodiment 10 is an explanatory diagram showing three convex portions 14f1 to 14f3 among the convex portions 14 formed on the holding surface 10f of the holding member of the seventh embodiment. When the holding surface 10f is viewed from the side facing the holding surface 10f, the convex portions 14f1 to 14f3 are arranged at positions close to the center O of the holding surface 10f in the order of convex portion 14f1, convex portion 14f2, and convex portion 14f3 (the convex portion 14f1 is arranged at the position closest to the center O of the holding surface 10f).

[0046] Grooves Gf1-Gf6 are formed in the top surface Tf1 of the protrusion 14f1. Grooves Gf7-Gf12 are formed in the top surface Tf2 of the protrusion 14f2. Grooves Gf13-Gf18 are formed in the top surface Tf3 of the protrusion 14f3. The grooves Gf1-Gf3, Gf7-Gf9, and Gf13-Gf15 all have the same width. The grooves Gf4-Gf6 all have the same width, the grooves Gf10-Gf12 all have the same width, and the grooves Gf16-Gf18 all have the same width. On the other hand, the width of each of the grooves Gf1 to Gf3 is different from that of each of the grooves Gf4 to Gf6, the width of each of the grooves Gf7 to Gf9 is different from that of each of the grooves Gf10 to Gf12, and the width of each of the grooves Gf13 to Gf15 is different from that of each of the grooves Gf16 to Gf ​​18. Furthermore, the widths increase in the order of the width of each of the grooves Gf16 to Gf18, the width of each of the grooves Gf10 to Gf12, and the width of each of the grooves Gf4 to Gf6 (the width of each of the grooves Gf16 to Gf18 is the largest).

[0047] When each of the top surfaces Tf1 to Tf3 is divided into two regions by a virtual perpendicular line IP similar to those in FIGS. 7 to 9, the area ratio of the grooves G to the region Ff1 to Ff3 (regions farther from the center O of the holding surface 10f) is larger than that of the region Nf1 to Nf3 (regions closer to the center O of the holding surface 10f). Also, the ratio of the total area of ​​the grooves G to the top surface T increases in the order of the convex portion 14f3, the convex portion 14f2, and the convex portion 14f1 (the ratio of the total area of ​​the grooves G to the top surface T is the largest for the convex portion 14f3). In this embodiment, the relationship described using the convex portions 14f1 to 14f3 holds for all the convex portions 14 formed on the holding surface 10f. Even in such a retaining member of the seventh embodiment, an appropriate proportion of grooves G can be arranged on the top surface T depending on both the amount of shed particles expected to be generated in each of the convex portions 14 based on the distance from the center O of the retaining surface 10f and the amount of shed particles expected to be generated in each region within the convex portion 14.

[0048] Eighth embodiment FIG. 11 is an explanatory diagram showing an enlarged view of one convex portion 14g among the multiple convex portions 14 formed on the holding surface 10f of the holding member of the eighth embodiment. The convex portion 14g shown in FIG. 11 is the convex portion 14g seen from the side facing the holding surface 10f. Grooves Gg1 to Gg5 are formed on the top surface Tg of the convex portion 14g. Also, the grooves Gg1 to Gg5 are formed in a convex arc shape toward the outer edge of the holding surface 10f when the holding surface 10f is seen from the side facing the holding surface 10f (see FIG. 2). In this embodiment, all the grooves G formed on the top surfaces T of all the convex portions 14 are the grooves G described in FIG. 11. In other embodiments, all of the groove portions G formed on the top surfaces T of some of the protrusions 14 are groove portions G as described in FIG. 11, and the groove portions G formed on the top surfaces T of the other protrusions 14 may include groove portions G different from the groove portions G as described in FIG. 11 in addition to the groove portions G as described in FIG. 11, or may only include groove portions G different from the groove portions G as described in FIG. 11.

[0049] Since the holding surface 10f thermally expands radially from the center O, the direction in which the shed particles roll on the top surface Tg is also generally radial. Therefore, since the grooves Gg1-Gg5 are formed in a convex arc shape with respect to such a radial direction, the holding member of the eighth embodiment can increase the possibility that the shed particles will fall into the grooves Gg1-Gg5.

[0050] <Modifications of this embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit and scope of the invention. For example, the following modifications are also possible.

[0051] In the first embodiment, the holding surface 10f is formed with the annular protrusion 12, the multiple protrusions 14, and the multiple recesses 16, but is not limited thereto. For example, the holding surface 10f may not be formed with the annular protrusion 12, but may have the multiple protrusions 14 and the multiple recesses 16.

[0052] In the above embodiment, the plurality of through-flow passages 22 are formed inside the holding member 10, but this is not limited thereto. For example, in addition to the plurality of through-flow passages 22, a passage that connects the through-flow passages 22 inside the holding member 10 and a passage that branches off from the passage and connects to the recess 16 may be formed inside the holding member 10.

[0053] In the electrostatic chuck according to the above embodiment, a plate-shaped base member may be joined to the rear surface of the holding member. If a coolant flow passage is formed inside the base member, when an object is held by the holding member, the coolant flows through the coolant flow passage from the base member through the holding member to cool the object.

[0054] In the second and third embodiments (see Figs. 5 and 6), the ratio of the total area of ​​the grooves G to the top surface T of all the protrusions 14 formed on the holding surface 10f increases as the protrusions 14 are positioned farther from the center O of the holding surface 10f, but this is not limited thereto. A similar relationship may be established only for some of the protrusions 14 formed on the holding surface 10f.

[0055] In the fifth and seventh embodiments (see Figs. 8 and 10), the relationship described using the convex portions 14d1-14d3 or the convex portions 14f1-14f3 holds for all the convex portions 14 formed on the holding surface 10f, but this is not limiting. The relationship described using the convex portions 14d1-14d3 or the convex portions 14f1-14f3 may hold for only some of the convex portions 14 formed on the holding surface 10f.

[0056] In the fifth embodiment (see FIG. 8), the ratio of the total area of ​​the grooves G in the regions Fd1-Fd3 is larger than that in the regions Nd1-Nd3, but this is not limited thereto. The ratio of the total area of ​​the grooves G in the regions Nd1-Nd3 may be larger than that in the regions Fd1-Fd3. In such a case, the intervals at which the grooves G are formed in the regions Nd1-Nd3 may be narrower than the intervals at which the grooves G are formed in the regions Fd1-Fd3. Since the movement amount of the shed particles rolling between the protrusion 14 and the wafer W is smaller in the region of the top surface T closer to the center O of the holding surface 10f, the removal efficiency of the grooves G in such a region can be increased by narrowing the intervals at which the grooves G are formed.

[0057] The shape of the groove G is not limited to the shape described in the above embodiment. For example, it may be a shape as shown in FIG. 12 to FIG. 15. FIG. 12 shows a convex portion 14h having a groove Gh formed on a top surface Th. The groove Gh is a lattice-shaped groove. Such a groove Gh improves the strength against rubbing at the contact portion between the convex portion 14 and the wafer W. FIG. 13 shows a convex portion 14i having a groove Gi formed on a top surface Ti. FIG. 14 shows a convex portion 14j having a groove Gj formed on a top surface Tj. The grooves Gi and Gj each include radial portions Ri and Rj extending radially from the center O of the holding surface 10f, and bridging portions Bi and Bj extending to the end of the top surface T while bridging the radial portions. The bridging portion Bi of the groove Gi is linear, whereas the bridging portion Bj of the groove Gj is arc-shaped protruding toward the outer edge of the holding surface 10f. In such grooves Gi, Gj, the radial portions Ri, Rj are included, thereby further improving the strength against rubbing at the contact portion between the protrusion 14 and the wafer W. FIG. 15 shows the protrusion 14k having grooves Gk1-Gk3 formed in the top surface Tk. The grooves Gk1-Gk3 are grooves formed in a concentric shape. In such grooves Gk1-Gk3, even if at least one of the holding member 10 and the wafer W does not thermally expand radially but expands in a direction significantly different from each other, the shed particles rolling between the protrusion 14 and the wafer W can be efficiently collected.

[0058] The cross-sectional shape of the groove G is not limited to the shape described in FIG. 4. For example, it may be a shape as shown in FIG. 16(A) to (C). FIG. 16(A) is an explanatory diagram showing a cross section of the groove Gl formed on the top surface Tl of the convex portion 14l. The cross-sectional shape of the groove Gl is a trapezoid. FIG. 16(B) is an explanatory diagram showing a cross section of the groove Gm formed on the top surface Tm of the convex portion 14m. The cross-sectional shape of the groove Gm is a V-shape. FIG. 16(C) is an explanatory diagram showing a cross section of the groove Gn formed on the top surface Tn of the convex portion 14n. The cross-sectional shape of the opening edge portion EGn of the groove Gn is an R-shaped surface. In such a groove Gn, chipping at the opening edge portion EGn can be suppressed in the same way as the opening edge portion EG having a C-shaped surface shown in FIG. 4, and thus generation of particles from the opening edge portion EGn can be suppressed. In addition, the cross-sectional shapes of the groove portion G shown in Figure 4 and Figures 16(A) to (C) all include corners at the bottom of the groove portion G, but it goes without saying that the bottom of the groove portion G may not include corners and may only include a curved surface.

[0059] Although the present aspect has been described above based on the embodiment and modified examples, the above-mentioned embodiment of the aspect is intended to facilitate understanding of the present aspect and does not limit the present aspect. The present aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents are included in the present aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[0060] The present invention can also be realized in the following forms. [Application example 1] A holding member for holding an object, The holding member has a holding surface which is a surface on which the object is held, The holding surface is formed with a convex portion and a concave portion, A holding member, characterized in that a groove is formed in a top surface that defines the top of the protrusion. [Application example 2] The holding member according to Application Example 1, A retaining member, wherein at least one of the grooves extends to an edge of the top surface. [Application example 3] The holding member according to Application Example 1 or Application Example 2, A holding member, characterized in that at least one of the groove portions is formed in a straight line extending in a direction perpendicular to an imaginary line passing through the center of the holding surface and the center of the top surface. [Application example 4] The holding member according to any one of Application Examples 1 to 3, When the holding surface is viewed from a side facing the holding surface, One of the protrusions and the other protrusion are disposed closer to the center of the holding surface than the one of the protrusions, A retaining member, characterized in that a proportion of a total area of ​​the groove portions to the top surface of one of the convex portions is greater than a proportion of a total area of ​​the groove portions to the top surface of the other of the convex portions. [Application example 5] The holding member according to any one of Application Examples 1 to 4, A retaining member characterized in that, when viewing the retaining surface from a side facing the retaining surface, the top surface of at least some of the convex portions is divided into two regions by a virtual perpendicular line passing through the center of the top surface and extending in a direction perpendicular to a virtual straight line passing through the center of the retaining surface and the center of the top surface, the proportion of the total area of ​​the groove portions in the region farther from the center of the retaining surface is greater than the proportion of the total area of ​​the groove portions in the region closer to the center of the retaining surface. [Application Example 6] The holding member according to any one of Application Examples 1 to 5, A holding member, wherein at least one of the grooves has an opening edge portion having a cross-sectional shape of a C-surface or an R-surface. [Application Example 7] The holding member according to any one of Application Examples 1 to 6, A holding member, characterized in that, when viewing the holding surface from the side facing the holding surface, at least one of the groove portions is formed in a convex arc shape toward the outer edge of the holding surface. [Application Example 8] 1. An electrostatic chuck comprising: A holding member according to any one of Application Examples 1 to 7, and an electrostatic electrode that generates an electrostatic attractive force on the holding surface. [Explanation of symbols]

[0061] 1...Electrostatic chuck 10...Retaining member 10b…Back side 10f…Holding surface 12...Ring-shaped protrusion 14…Convex part T…Top surface G…Groove 16…Recess 22...Through-flow passage 30...Electrostatic electrode

Claims

1. A holding member for holding an object, The holding member has a holding surface which is a surface on which the object is held, The holding surface is formed with a convex portion and a concave portion, A holding member, characterized in that a groove is formed in a top surface that defines the top of the protrusion.

2. 2. The holding member according to claim 1, A retaining member, wherein at least one of the grooves extends to an edge of the top surface.

3. 2. The holding member according to claim 1, A holding member, characterized in that at least one of the groove portions is formed in a straight line extending in a direction perpendicular to an imaginary line passing through the center of the holding surface and the center of the top surface.

4. 2. The holding member according to claim 1, When the holding surface is viewed from a side facing the holding surface, One of the protrusions and the other protrusion are disposed closer to the center of the holding surface than the one of the protrusions, A retaining member, characterized in that a proportion of a total area of ​​the groove portions to the top surface of one of the convex portions is greater than a proportion of a total area of ​​the groove portions to the top surface of the other of the convex portions.

5. 2. The holding member according to claim 1, A retaining member characterized in that, when viewing the retaining surface from the side facing the retaining surface, the top surface of at least some of the convex portions is divided into two regions by a virtual perpendicular line passing through the center of the top surface and extending in a direction perpendicular to a virtual straight line passing through the center of the retaining surface and the center of the top surface, the proportion of the total area of ​​the groove portions in the region farther from the center of the retaining surface is greater than the proportion of the total area of ​​the groove portions in the region closer to the center of the retaining surface.

6. 2. The holding member according to claim 1, A holding member, wherein at least one of the grooves has an opening edge portion having a cross-sectional shape of a C-surface or an R-surface.

7. 2. The holding member according to claim 1, A holding member, characterized in that, when viewing the holding surface from the side facing the holding surface, at least one of the groove portions is formed in a convex arc shape toward the outer edge of the holding surface.

8. 1. An electrostatic chuck comprising: A holding member according to any one of claims 1 to 7; and an electrostatic electrode that generates an electrostatic attractive force on the holding surface.

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