Retaining member

Abstract

To provide a holding member capable of improving thermal uniformity of a surface for holding an object.SOLUTION: In one embodiment of the present disclosure, an electrostatic chuck 1 has a heating element 41 provided with a pair of heating lines 43, a first folding part 45a and a second folding part 45b. A circumferential pitch width δC, which is a distance between the first and second folding parts 45a and 45b, is greater than a radial pitch width δR that is a distance between two heating lines 42 constituting the pair of heating line 43.SELECTED DRAWING: Figure 5

Description

Technical Field

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

Background Art

[0002] As a document related to a holding member, Patent Document 1 discloses a wafer heating device used in a film forming apparatus or an etching apparatus in a manufacturing process of a semiconductor device. And, in the wafer heating device disclosed in this Patent Document 1, a heater pattern composed of heating lines for heating a wafer is embedded inside a ceramic member (ceramic substrate) having a holding surface (support surface of the wafer).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the wafer heating apparatus disclosed in Patent Document 1, the distance between a pair of folded portions in the heater pattern is made smaller than the radial distance, increasing the amount of heat generated in the pair of folded portions. As a result of increasing the amount of heat generated in the region between the pair of folded portions of the heater pattern (hereinafter referred to as the "separation region"), there is a risk of hot spots occurring at the position corresponding to the separation region on the holding surface, which may reduce the uniformity of the heat. Furthermore, although a base member is not disclosed in Patent Document 1, if a base member is provided below the ceramic member, in the portion of the base member where a hole is formed for inserting components such as power supply terminals, for example, there is no base member directly beneath the ceramic member. Therefore, the heat dissipation effect of the base member is reduced, and the temperature tends to rise. Consequently, if such a hole is formed at the position corresponding to the separation region, the temperature in this separation region will rise even more easily. Therefore, if there is a hole at the position corresponding to the separation region on the holding surface, there is a risk of hot spots occurring, which may reduce the uniformity of the heat.

[0005] Therefore, this disclosure is made to solve the above-mentioned problems and aims to provide a holding member that can improve the uniformity of heat on the surface that holds the object. [Means for solving the problem]

[0006] One embodiment of the present disclosure made to solve the above problems comprises a first plate-like member having a first surface and a second surface provided on the opposite side of the first surface, and a second plate-like member having a third surface and a fourth surface provided on the opposite side of the third surface, wherein the second surface of the first plate-like member and the third surface of the second plate-like member are thermally connected, and the holding member holds an object on the first surface, wherein the holding member has a heating element in which linear heating lines are formed substantially concentrically inside the first plate-like member or on the second surface, and when viewed from the direction of arrangement of the first plate-like member and the second plate-like member, the heating element is radially connected to the heating element. The heating element comprises a pair of heating lines consisting of two adjacent heating lines, a first pair of heating lines and a second pair of heating lines arranged apart in the circumferential direction of the heating element with a predetermined separation region in between; a first folded portion connecting the ends of the two heating lines constituting the first pair of heating lines on the separation region side; and a second folded portion connecting the ends of the two heating lines constituting the second pair of heating lines on the separation region side, wherein the circumferential pitch width, which is the distance between the first folded portion and the second folded portion, is greater than the radial pitch width, which is the distance between the two heating lines constituting the pair of heating lines.

[0007] According to this embodiment, by increasing the circumferential pitch width, the temperature rise in the separation region due to heat generation in the first and second folded portions can be suppressed. Therefore, the occurrence of hot spots (i.e., temperature singularities, which are areas where the temperature is higher than other parts) at positions corresponding to the separation region on the surface that holds the object, i.e., the first surface of the first plate-like member, can be suppressed. Thus, the uniformity of heat on the surface that holds the object can be improved.

[0008] In the above embodiment, it is preferable that the circumferential pitch width is four times or less the radial pitch width.

[0009] According to this embodiment, since the circumferential pitch width does not become too large, it is possible to suppress insufficient temperature rise in the separation region due to heat generation in the first and second folded portions. Therefore, it is possible to suppress the occurrence of cold spots (i.e., temperature singularities, areas where the temperature is lower than other parts) at positions corresponding to the separation region on the surface that holds the object. Consequently, the uniformity of the heat distribution on the surface that holds the object can be improved more reliably.

[0010] In the above embodiment, it is preferable that the resistance value per unit length of the heating line forming the first folded portion and the second folded portion is greater than the resistance value per unit length of the heating line forming the pair of heating lines.

[0011] According to this embodiment, the amount of heat generated in the first and second folded portions is increased, so that the occurrence of cold spots in the surface that holds the object at positions corresponding to the separation region can be suppressed. Therefore, the uniformity of heat on the surface that holds the object can be further improved.

[0012] In the above embodiment, it is preferable that a through hole is formed in at least one of the first plate-like member and the second plate-like member, and that when viewed from the direction of arrangement, the through hole is formed at the position of the separation region between the first folded portion and the second folded portion, and that the circumferential pitch width is greater than or equal to the circumferential width of the through hole.

[0013] According to this embodiment, since the through-hole is formed at the location of the separation region, the temperature tends to rise in this separation region. However, since the circumferential pitch width is greater than or equal to the circumferential width of the through-hole, the distance between the first folded portion and the second folded portion becomes larger, which can suppress the temperature rise in the separation region.

[0014] Furthermore, if a through hole is formed in the first plate-like member, by making the circumferential pitch width greater than or equal to the circumferential width of the through hole, it is possible to structurally prevent the heating element (first folded portion and second folded portion) from being formed in the through hole, and to ensure sufficient insulation distance between the component inserted into the through hole and the heating element.

[0015] In the above embodiment, it is preferable that the holding member is an electrostatic chuck having chuck electrodes that generate an electrostatic attraction force for holding the object.

[0016] According to this embodiment, the uniformity of heat can be improved on the surface of the electrostatic chuck that holds the object. [Effects of the Invention]

[0017] The holding member of this disclosure can improve the uniformity of heat distribution on the surface that holds the object. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic perspective view of the electrostatic chuck of this embodiment. [Figure 2] This is an XY plan view of the electrostatic chuck of this embodiment. [Figure 3] This is an XZ cross-sectional view of the ceramic member of this embodiment. [Figure 4] This is a top view of the heating element of this embodiment. [Figure 5] This is an enlarged view of the pair of folded portions of the heating element in this embodiment and the surrounding area (an enlarged view of the area α in Figure 4). [Figure 6] This diagram shows a pair of folded portions of a heating element and its surrounding area, with a circumferential pitch width of 2.5 mm. [Figure 7] This is an evaluation result of the temperature distribution in a portion of the holding surface (i.e., the position on the holding surface corresponding to the hole in the base member and the surrounding area) when the circumferential pitch width is set to 2.5 mm. [Figure 8]A diagram of a pair of folded portions of a heating element and its periphery, showing the case where the circumferential pitch width is 5.0 mm. [Figure 9] The evaluation result of the temperature distribution of a part of the holding surface when the circumferential pitch width is 5.0 mm. [Figure 10] A diagram of a pair of folded portions of a heating element and its periphery, showing the case where the circumferential pitch width is 6.0 mm. [Figure 11] The evaluation result of the temperature distribution of a part of the holding surface when the circumferential pitch width is 6.0 mm. [Figure 12] A diagram of a pair of folded portions of a heating element and its periphery, showing the case where the circumferential pitch width is 8.0 mm (and the ratio of the line width is 100%). [Figure 13] The evaluation result of the temperature distribution of a part of the holding surface when the circumferential pitch width is 8.0 mm (and the ratio of the line width is 100%). [Figure 14] A graph showing the evaluation result of the temperature difference of the holding surface with respect to the circumferential pitch width. [Figure 15] A list showing the evaluation result of the temperature difference of the holding surface with respect to the circumferential pitch width. [Figure 16] A diagram of a pair of folded portions of a heating element and its periphery, showing the case where the ratio of the line width is 75%. [Figure 17] A diagram showing the evaluation result of the temperature distribution of a part of the holding surface when the ratio of the line width is 75%. [Figure 18] A diagram of a pair of folded portions of a heating element and its periphery, showing the case where the ratio of the line width is 50%. [Figure 19] A diagram showing the evaluation result of the temperature distribution of a part of the holding surface when the ratio of the line width is 50%. [Figure 20] A diagram of a pair of folded portions of a heating element and its periphery, showing the case where the ratio of the line width is 25%. [Figure 21] A diagram showing the evaluation result of the temperature distribution of a part of the holding surface when the ratio of the line width is 25%. [Figure 22] This graph shows the evaluation results of the temperature difference on the holding surface in relation to the ratio of line width. [Figure 23] This is a table showing the evaluation results of the temperature difference on the holding surface in relation to the ratio of line width. [Figure 24] This is a diagram showing the first modified example. [Figure 25] This figure shows a second modified example. [Modes for carrying out the invention]

[0019] Embodiments of the retaining member of this disclosure will be described. In this embodiment, an electrostatic chuck 1 will be used as an example of the retaining member.

[0020] <Overall explanation of electrostatic chucks> The electrostatic chuck 1 of this embodiment is a device that attracts and holds a semiconductor wafer W by electrostatic attraction, and is used, for example, to fix a semiconductor wafer W in a vacuum chamber of a semiconductor manufacturing apparatus. The semiconductor wafer W is an example of the "object" of this disclosure.

[0021] As shown in Figure 1, the electrostatic chuck 1 includes a ceramic member 10, a base member 20, and a bonding layer 30 that joins the ceramic member 10 and the base member 20. The ceramic member 10 is an example of the "first plate-shaped member" of this disclosure, and the base member 20 is an example of the "second plate-shaped member" of this disclosure.

[0022] For the purposes of the following explanation, the XYZ axes will be defined as shown in Figure 1. Here, the Z axis is the axis in the direction of the central axis Ca of the electrostatic chuck 1 (vertical direction in Figure 1), and the X and Y axes are the radial axes of the electrostatic chuck 1.

[0023] As shown in Figure 1, the ceramic member 10 is plate-shaped, more specifically, disc-shaped, and is formed from ceramics (ceramic substrate). Specifically, the ceramic member 10 has a stepped disc shape in which two discs of different diameters overlap with a common central axis Ca (see Figure 2) (more specifically, an upper disc-shaped part 10a with a smaller diameter overlaps a lower disc-shaped part 10b with a larger diameter).

[0024] Various ceramics can be used, but from the viewpoint of strength, wear resistance, plasma resistance, etc., it is preferable to use ceramics mainly composed of aluminum oxide (alumina, Al2O3) or aluminum nitride (AlN). Here, "main component" refers to the component that makes up the largest proportion (for example, the component with a volume content of 90 vol% or more).

[0025] As shown in Figures 1 to 3, the ceramic member 10 includes a holding surface 11 (upper surface) for holding the semiconductor wafer W, and a lower surface 12 provided on the opposite side of the ceramic member 10 from the holding surface 11 in the thickness direction (i.e., the Z-axis direction). The holding surface 11 is an example of the "first surface" of this disclosure, and the lower surface 12 is an example of the "second surface" of this disclosure.

[0026] Furthermore, the diameter of the ceramic member 10 is such that the lower section 10b is larger than the upper section 10a, with the upper section 10a being, for example, about 150 to 300 mm and the lower section 10b being, for example, about 180 to 400 mm. The thickness of the ceramic member 10 is, for example, about 2 to 6 mm. The thermal conductivity of the ceramic member 10 is preferably in the range of 10 to 50 W / mK (more preferably 18 to 30 W / mK).

[0027] Furthermore, the ceramic member 10 is equipped with a chuck electrode (adsorption electrode) not shown inside. When a voltage is applied to this chuck electrode from a power source not shown, an electrostatic attraction force is generated on the chuck electrode, and the semiconductor wafer W is attracted to and held on the holding surface 11 by this electrostatic attraction force.

[0028] The base member 20 is positioned on the side opposite to the holding surface 11 relative to the ceramic member 10. This base member 20 is formed, for example, in a cylindrical shape. The base member 20 is formed of, for example, metal (e.g., aluminum or aluminum alloy), but it may be made of a material other than metal.

[0029] As shown in Figure 1, the base member 20 includes an upper surface 21 and a lower surface 22 provided on the opposite side of the upper surface 21 in the thickness direction (i.e., the Z-axis direction) of the base member 20. The upper surface 21 of the base member 20 is thermally connected to the lower surface 12 of the ceramic member 10 via a bonding layer 30. The upper surface 21 is an example of the "third surface" of this disclosure, and the lower surface 22 is an example of the "fourth surface" of this disclosure.

[0030] The diameter of the base member 20 is, for example, about 180 to 400 mm. The thickness of the base member 20 (dimension in the Z-axis direction) is, for example, about 20 to 50 mm. The thermal conductivity of the base member 20 (assuming aluminum) is preferably in the range of 160 to 250 W / mK (preferably about 230 W / mK).

[0031] The bonding layer 30 is positioned between the lower surface 12 of the ceramic member 10 and the upper surface 21 of the base member 20, and bonds the ceramic member 10 and the base member 20 in a way that allows for heat transfer.

[0032] The bonding layer 30 is composed of an adhesive made of a resin containing a thermally conductive filler (such as a silicone resin, acrylic resin, or epoxy resin). The thickness of the bonding layer 30 (dimension in the Z-axis direction) is, for example, about 0.1 to 1.5 mm. The thermal conductivity of the bonding layer 30 is, for example, 1.0 W / mK. The thermal conductivity of the bonding layer 30 (assuming a silicone resin) is preferably in the range of 0.1 to 2.0 W / mK (preferably 0.5 to 1.5 W / mK).

[0033] In the electrostatic chuck 1 described above, the base member 20 is cooled by flowing a coolant through a coolant channel (not shown) provided in the base member 20. As a result, heat is drawn from the ceramic member 10 to the base member 20 via the bonding layer 30, and the ceramic member 10 is cooled. The cooling of the ceramic member 10 then allows the semiconductor wafer W held on the holding surface 11 to be cooled.

[0034] <About the heating element> In this embodiment, as shown in Figure 3, a heating element 41 is provided inside the upper portion 10a of the ceramic member 10. That is, the heating element 41 is embedded in the upper portion 10a of the ceramic member 10. The heating element 41 generates heat to heat the semiconductor wafer W. The heating element 41 is made of, for example, tungsten or a molybdenum alloy, but may be made of other metals. The heating element 41 may also be embedded in the lower portion 10b of the ceramic member 10. Furthermore, the heating element 41 may be formed on the lower surface 12 of the ceramic member 10.

[0035] As shown in Figure 4, the heating element 41 has linear heating lines 42 formed in a substantially concentric pattern when viewed from the thickness direction of the ceramic member 10 (i.e., the Z-axis direction in Figure 1). The line width LW of the heating lines 42 is about 0.1 mm to 1.0 mm, and the heating element 41 has a pair of heating lines 43 made up of two heating lines 42 that are adjacent to each other (at least in part) in the radial direction. The two heating lines 42 that make up this pair of heating lines 43 are formed in the same circular shape. In the example shown in Figure 4, the heating element 41 has many pairs of heating lines 43, but it is sufficient to have at least two pairs of heating lines 43. Note that "substantially concentric" also includes concentric circles where a part in the circumferential direction is not connected (for example, a shape in which multiple lines are arranged in a fan shape).

[0036] As shown in Figure 5 (an enlarged view of region α in Figure 4), the heating element 41 includes a pair of heating lines 43, namely a first heating line pair 43a and a second heating line pair 43b. These first heating line pair 43a and second heating line pair 43b are arranged separately from each other in the circumferential direction of the heating element 41, separated by a predetermined separation region 44.

[0037] Furthermore, the heating element 41 is provided with a pair of folded portions 45, namely a first folded portion 45a and a second folded portion 45b. These first folded portion 45a and second folded portion 45b are arranged apart in the circumferential direction of the heating element 41, with a predetermined separation region 44 in between. The first folded portion 45a connects the ends 42a on the separation region 44 side of the two heating lines 42 that constitute the first heating line pair 43a. The second folded portion 45b connects the ends 42b on the separation region 44 side of the two heating lines 42 that constitute the second heating line pair 43b.

[0038] <Means for improving heat uniformity of the holding surface> The base member 20 has holes Ho (an example of a "through hole" in this disclosure) formed in it for inserting, for example, power supply terminals or temperature sensors. In the area where the holes Ho are formed, the volume of the base member 20 decreases, making it difficult for heat to be drawn from the ceramic member 10 to the base member 20. Therefore, the temperature tends to rise at the position on the holding surface 11 of the ceramic member 10 corresponding to the holes Ho.

[0039] In this embodiment, as shown in Figure 5, a hole Ho is formed in the separation region 44 located between the first folded portion 45a and the second folded portion 45b when viewed from the direction of arrangement of the ceramic member 10 and the base member 20 (i.e., the Z-axis direction in Figure 1). Therefore, heat is less likely to be drawn from the ceramic member 10 to the base member 20 in the separation region 44, and the temperature rises more easily. In the example shown in Figure 5, the hole Ho is formed such that its center is located at the center of the separation region 44.

[0040] Furthermore, if the circumferential pitch width δC (see Figure 5) is small and the separation region 44 is narrow, the heat generated by the first folded portion 45a and the second folded portion 45b may cause a large increase in temperature in the separation region 44, potentially resulting in the occurrence of a hot spot HS (i.e., a temperature singularity, a portion where the temperature is higher than other parts) at a position on the holding surface 11 corresponding to the separation region 44, i.e., at a position corresponding to the hole Ho.

[0041] The "circumferential pitch width δC" is the distance between the first folded portion 45a and the second folded portion 45b, and more specifically, it is the maximum length in the circumferential direction between the first folded portion 45a and the second folded portion 45b.

[0042] In this embodiment, the circumferential pitch width δC is made larger than the radial pitch width δR, and more specifically, it is made larger than or equal to the diameter Dh (circumferential width) of the hole Ho. In this way, in this embodiment, because the circumferential pitch width δC is made larger, the separation region 44 is widened, and the temperature in the separation region 44 is less likely to rise due to the heat generated by the first folded portion 45a and the second folded portion 45b. Therefore, the generation of hot spots HS at the position corresponding to the hole Ho on the holding surface 11 can be suppressed.

[0043] Here, "radial pitch width δR" refers to the distance between two heating lines 42 that constitute a pair of heating lines 43, and more specifically, the distance between the two heating lines 42 on a straight line La extending radially from the center of the holding surface 11, which has a circular outer shape. Note that the radial pitch width δR is approximately constant throughout the heating element 41, for example, between 1.5 mm and 3.5 mm.

[0044] Here, we evaluated the relationship between the circumferential pitch width δC and the temperature distribution of the holding surface 11. Specifically, under the conditions that the diameter Dh of the hole Ho is 5.0 mm, the radial pitch width δR is 2.5 mm, and the line width LW is 0.5 mm, we evaluated the temperature distribution of the holding surface 11 with circumferential pitch widths δC of 2.5 mm (see Figure 6), 5.0 mm (see Figure 8), 6.0 mm (see Figure 10), and 8.0 mm (see Figure 12).

[0045] As an evaluation result, first, when the circumferential pitch width δC was set to 2.5 mm (see Figure 6), that is, when the circumferential pitch width δC was equal to the radial pitch width δR, a hot spot HS occurred on the holding surface 11 at the position corresponding to the hole Ho, as shown in Figure 7. Furthermore, as shown in Figures 14 and 15, the temperature difference ΔT on the holding surface 11 was 15.7°C.

[0046] The "temperature difference ΔT of the holding surface 11" refers to the temperature difference between the position corresponding to the center of the hole Ho on the holding surface 11 and other positions (i.e., positions not corresponding to the hole Ho).

[0047] Furthermore, when the circumferential pitch width δC was set to 5.0 mm (see Figure 8), that is, when the circumferential pitch width δC was made larger than the radial pitch width δR and equal to the diameter Dh of the hole Ho, the results shown in Figure 9 were obtained. As shown in Figure 9, the size of the hot spot HS that occurred at the position corresponding to the hole Ho on the holding surface 11 was smaller than when the circumferential pitch width δC was set to 2.5 mm (see Figure 7). And, as shown in Figures 14 and 15, the temperature difference ΔT on the holding surface 11 was 2.7°C. Thus, by making the circumferential pitch width δC larger than the radial pitch width δR, it was possible to suppress the occurrence of hot spot HS on the holding surface 11.

[0048] Furthermore, when the circumferential pitch width δC was set to 6.0 mm (see Figure 10), that is, when the circumferential pitch width δC was greater than the diameter Dh of the hole Ho, the results shown in Figure 11 were obtained. As shown in Figure 11, a small cold spot CS (i.e., a temperature singularity, a part where the temperature is lower than other parts) occurred at the position corresponding to the hole Ho on the holding surface 11, but no hot spot HS occurred. Then, as shown in Figures 14 and 15, the temperature difference ΔT on the holding surface 11 was -0.9°C. Thus, when the circumferential pitch width δC was greater than the diameter Dh of the hole Ho, it was possible to obtain results in which no hot spot HS occurred on the holding surface 11.

[0049] Furthermore, when the circumferential pitch width δC was set to 8.0 mm (see Figure 12), that is, when the circumferential pitch width δC was made even larger than the diameter Dh of the hole Ho, the results shown in Figure 13 were obtained. As shown in Figure 13, a small cold spot CS occurred on the holding surface 11 at the position corresponding to the hole Ho, but no hot spot HS occurred. Then, as shown in Figures 14 and 15, the temperature difference ΔT on the holding surface 11 was -5.1°C. Thus, when the circumferential pitch width δC was made even larger than the diameter Dh of the hole Ho, it was possible to obtain results in which no hot spot HS occurred on the holding surface 11.

[0050] In this case, when the circumferential pitch width δC was set to 8.0 mm (see Figure 12), small cold spots CS occurred on the holding surface 11, as shown in Figure 13. Therefore, if the circumferential pitch width δC is increased further than 8.0 mm, there is a risk that even larger cold spots CS will occur.

[0051] Therefore, in this embodiment, the circumferential pitch width δC is set to four times or less the radial pitch width δR, thereby suppressing the occurrence of cold spots CS on the holding surface 11.

[0052] Furthermore, if the line width LW of the heating line 42 is reduced, its resistance increases, and the amount of heat generated increases. Therefore, if cold spots CS are likely to occur, the line width LW1 of the pair of folded portions 45 may be made smaller than the line width LW of the pair of heating lines 43. In this way, the resistance per unit length of the heating line 42 forming the pair of folded portions 45 may be made larger than the resistance per unit length of the heating line 42 forming the pair of heating lines 43. This increases the amount of heat generated by the first folded portion 45a and the second folded portion 45b, thereby suppressing the occurrence of cold spots CS on the holding surface 11.

[0053] Furthermore, "the line width LW1 of the pair of folded portions 45" refers to the line width of the heating line 42 that forms the first folded portion 45a and the second folded portion 45b. Also, "the line width LW of the pair of heating lines 43" refers to the line width of the two heating lines 42 that form the pair of heating lines 43.

[0054] Furthermore, as a method to make the resistance value per unit length of the heating line 42 forming the pair of folded portions 45 greater than the resistance value per unit length of the heating line 42 forming the pair of heating lines 43, other methods include making the thickness of the heating line 42 forming the pair of folded portions 45 smaller than the thickness of the heating line 42 forming the pair of heating lines 43, or using a material for the heating line 42 forming the pair of folded portions 45 that has a higher resistivity than the material for the heating line 42 forming the pair of heating lines 43.

[0055] Here, we evaluated the relationship between the line width LW1 of the pair of folded sections 45 and the temperature distribution of the holding surface 11. Specifically, under the conditions that the radial pitch width δR is 2.5 mm and the circumferential pitch width δC is 8.0 mm, we evaluated the temperature distribution of the holding surface 11 by changing the line width LW1 of the pair of folded sections 45. More specifically, under the condition that the line width LW is 0.5 mm, we evaluated the line width ratio LR, which represents the size of the line width LW1 of the pair of folded sections 45, at 100% (see Figure 12 above), 75% (see Figure 16), 50% (see Figure 18), and 25% (see Figure 20). Note that the "line width ratio LR" is the ratio of the line width LW1 of the pair of folded sections 45 to the line width LW of the pair of heating lines 43, and is expressed by the formula (LW1 / LW) × 100%.

[0056] As an evaluation result, first, when the line width ratio LR was set to 100% (see Figure 12 above), a cold spot CS occurred on the holding surface 11 at the position corresponding to the hole Ho, as shown in Figure 13 above. Furthermore, as shown in Figures 22 and 23, the temperature difference ΔT on the holding surface 11 was -5.1℃.

[0057] Furthermore, when the line width ratio LR was set to 75% (see Figure 16), that is, when the line width LW1 of the pair of folded portions 45 was made smaller than the line width LW of the pair of heating lines 43, the cold spots CS that occurred at the positions corresponding to the holes Ho on the holding surface 11 were smaller than when the line width ratio LR was set to 100% (see Figure 13), as shown in Figure 17. And, as shown in Figures 22 and 23, the temperature difference ΔT on the holding surface 11 was -2.2℃. Thus, by making the line width LW1 of the pair of folded portions 45 smaller than the line width LW of the pair of heating lines 43, it was possible to obtain the result that the occurrence of cold spots CS on the holding surface 11 was suppressed.

[0058] Furthermore, when the line width ratio LR was set to 50% (see Figure 18), and when the line width ratio LR was set to 25% (see Figure 20), that is, when the line width LW1 of the pair of folded portions 45 was made even smaller than the line width LW of the pair of heating lines 43, as shown in Figures 19 and 21, hot spots HS occurred at the positions corresponding to holes Ho on the holding surface 11, but cold spots CS did not occur. And, as shown in Figures 22 and 23, the temperature difference ΔT of the holding surface 11 was 1.7℃ and 16.0℃.

[0059] As a first modified example, as shown in Figure 24, the pair of folded portions 45 may be formed in an arc shape that curves away from the separation region 44 (away from the hole Ho). In this case, the circumferential pitch width δC is the straight-line distance between the radial center portion 45c of the first folded portion 45a and the radial center portion 45c of the second folded portion 45b, or in other words, the straight-line distance between the vertex of the arc of the first folded portion 45a and the vertex of the arc of the second folded portion 45b.

[0060] Furthermore, if the hole Ho is formed in the ceramic member 10, the circumferential pitch width δC is made larger than the diameter Dh of the hole Ho to ensure an insulating distance between the component inserted into the hole Ho and the pair of folded portions 45 of the heating element 41. In this case, for example, if the diameter Dh of the hole Ho is 5 mm, the circumferential pitch width δC is set to 7 mm or more.

[0061] Furthermore, if the hole Ho is formed in the ceramic member 10, and increasing the circumferential pitch width δC in this manner does not suppress the occurrence of a hot spot HS at the position corresponding to the hole Ho on the holding surface 11, then, as a second modification, as shown in Figure 25, the line width LW1 of the pair of folded portions 45 may be made larger than the line width LW of the pair of heating lines 43. By doing so, the resistance value of the heating lines 42 forming the pair of folded portions 45 is reduced, thereby reducing the amount of heat generated by the pair of folded portions 45, and thus the occurrence of a hot spot HS at the position corresponding to the hole Ho on the holding surface 11 can be suppressed.

[0062] <Effects of this embodiment> As described above, in the electrostatic chuck 1 of this embodiment, the circumferential pitch width δC, which is the distance between the first folded portion 45a and the second folded portion 45b in the heating element 41 of the ceramic member 10, is greater than the radial pitch width δR, which is the distance between the two heating lines 42 that constitute the pair of heating lines 43.

[0063] In this way, by increasing the circumferential pitch width δC, the temperature rise in the separation region 44 due to heat generation from the first folded portion 45a and the second folded portion 45b can be suppressed. Therefore, even if a hole Ho is formed in the base member 20 at a position corresponding to the separation region 44, the temperature rise in the separation region 44 can be suppressed. Consequently, the occurrence of a hot spot HS at a position corresponding to the separation region 44 on the holding surface 11, i.e., at a position corresponding to the hole Ho, can be suppressed. Thus, the uniformity of heat distribution on the holding surface 11 can be improved.

[0064] Furthermore, since the hole Ho is formed in the separation region 44, the temperature tends to rise in this separation region 44. However, in this embodiment, the circumferential pitch width δC is set to be greater than or equal to the diameter Dh of the hole Ho, so the distance between the first folded portion 45a and the second folded portion 45b becomes larger, and the temperature rise in the separation region 44 can be suppressed.

[0065] Furthermore, if a hole Ho is formed in the ceramic member 10, by making the circumferential pitch width δC larger than or equal to the diameter Dh of the hole Ho, it is possible to prevent the heating element 41 (first folded portion 45a and second folded portion 45b) from being formed in the hole Ho, and to ensure an insulating distance between the component inserted into the hole Ho and the heating element 41.

[0066] Furthermore, the circumferential pitch width δC is less than or equal to four times the radial pitch width δR.

[0067] In this way, the circumferential pitch width δC does not become too large, so that the temperature rise in the separation region 44 due to heat generation from the first folded portion 45a and the second folded portion 45b is suppressed. Therefore, the occurrence of cold spots CS on the holding surface 11 at positions corresponding to the separation region 44, i.e., at positions corresponding to holes Ho, can be suppressed. Thus, the uniformity of heat distribution on the holding surface 11 can be improved more reliably.

[0068] Furthermore, if there is a risk of cold spots CS occurring at the position corresponding to the hole Ho on the holding surface 11, the line width LW1 of the pair of folded portions 45 may be made smaller than the line width LW of the pair of heating lines 43. In this way, the resistance value per unit length of the heating lines 42 forming the pair of folded portions 45 may be made larger than the resistance value per unit length of the heating lines 42 forming the pair of heating lines 43.

[0069] This increases the amount of heat generated in the first folded portion 45a and the second folded portion 45b, thereby increasing the temperature rise in the separation region 44, and thus suppressing the occurrence of cold spots CS at the position corresponding to the hole Ho on the holding surface 11.

[0070] It should be noted that the embodiments described above are merely illustrative examples and do not limit this disclosure in any way. Various improvements and modifications are possible without departing from the gist of the disclosure.

[0071] For example, the invention of this disclosure can also be applied when the outer shape of the hole Ho is not circular. In this case, the circumferential pitch width δC only needs to be greater than or equal to the circumferential width of the hole Ho.

[0072] Furthermore, the hole Ho only needs to be formed in at least one of the ceramic member 10 and the base member 20, and may be formed across both the ceramic member 10 and the base member 20. [Explanation of Symbols]

[0073] 1. Electrostatic Chuck 10 Ceramic components 11 Holding surface 12 Bottom side 20 Base members 21 Top side 22 Bottom side 41 Heating element 42 Heating lines 42a end 42b End 43 Pair of heating lines 43a First heat line pair 43b Second heating line pair 44 Separation area 45 A pair of folded sections 45a First Fold-Over Section 45b Second Fold-Over Section 45c central part W Semiconductor wafer LW line width Ho Hole δC Circumferential pitch width HS hotspot δR radial pitch width Dh (hole) diameter ΔT (temperature difference of the holding surface) CS Cold Spot LW1 (line width of the first and second folds) LR line width ratio

Claims

1. A first plate-like member having a first surface and a second surface provided on the opposite side of the first surface, A second plate-like member having a third surface and a fourth surface provided on the opposite side of the third surface, It has, The second surface of the first plate-like member and the third surface of the second plate-like member are thermally connected. In the holding member that holds an object on the first surface, The heating element has linear heating lines formed substantially concentrically on the inside of the first plate-shaped member or on the second surface, When viewed from the direction of arrangement of the first plate-like member and the second plate-like member, The aforementioned heating element is A pair of heating lines, consisting of two heating lines adjacent to each other in the radial direction of the heating element, comprising a first pair of heating lines and a second pair of heating lines arranged separately in the circumferential direction of the heating element, separated by a predetermined separation region, A first folded portion that connects the ends of the two heating lines constituting the first heating line pair on the separation region side, A second folded portion that connects the ends of the two heating lines constituting the second pair of heating lines on the separated region side, Equipped with, The circumferential pitch width, which is the distance between the first folded portion and the second folded portion, is greater than the radial pitch width, which is the distance between the two heating lines that constitute the pair of heating lines. A through hole is formed in at least one of the first plate-like member and the second plate-like member. When viewed from the aforementioned arrangement direction, The through hole is formed at the location of the separation region between the first folded portion and the second folded portion. The circumferential pitch width is 1.0 times or more and less than 1.2 times the circumferential width of the through hole. The first folded portion and the second folded portion are formed in an arc shape. A retaining member characterized by the following.

2. In the retaining member of claim 1, The circumferential pitch width is no more than four times the radial pitch width. A retaining member characterized by the following.

3. In the retaining member of claim 1 or 2, The resistance per unit length of the heating line forming the first folded portion and the second folded portion is greater than the resistance per unit length of the heating line forming the pair of heating lines. A retaining member characterized by the following.

4. In the retaining member of claim 1 or 2, The resistance per unit length of the heating line forming the first folded portion and the second folded portion is smaller than the resistance per unit length of the heating line forming the pair of heating lines. A retaining member characterized by the following.

5. In any one of the holding members from claim 1 to 4, The holding member is an electrostatic chuck having chuck electrodes that generate an electrostatic attraction for holding the object. A retaining member characterized by the following.

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