Ceramic heater and holding member

Abstract

In a ceramic heater, a heating element includes: a first pair of heating lines and a second pair of heating lines each serving as a pair of heating lines constituted by two heating lines adjacent in a radial direction of the heating element, the first pair of heating lines and the second pair of heating lines being arranged apart by a predetermined separation region in a circumferential direction of the heating element; a first return portion connecting end portions of the two heating lines of the first pair of heating lines on the separation region side to each other; and a second return portion connecting end portions of the two heating lines of the second pair of heating lines on the separation region side to each other, in a pair of return portions constituted by the first return portion and the second return portion, a separation between the first return portion and the second return portion at an end portion on one side in a radial direction of the heating element of the pair of return portions is narrower than a separation between the first return portion and the second return portion at a central portion in the radial direction of the heating element of the pair of return portions.

Description

Technical Field

[0001] This disclosure relates to ceramic heaters and retaining members for holding objects. Background Technology

[0002] As a document relating to ceramic heaters and holding members, Patent Document 1 discloses a wafer heating device used in a film deposition apparatus and an etching apparatus in the manufacturing process of a semiconductor device. Moreover, the wafer heating device disclosed in Patent Document 1 has a heater pattern for heating the wafer embedded inside a ceramic substrate having a wafer support surface.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 3477062 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] In the wafer heating apparatus disclosed in Patent Document 1, the distance between the folds of the heater pattern is shortened at the folded-back positions on the wafer support surface in the ceramic substrate. Therefore, the center-to-center distance of the folded-back portions is relatively short, potentially leading to hot spots. Furthermore, no heater pattern is embedded in the outermost peripheral portion, which is further outward than the outermost peripheral position corresponding to the heater pattern. This tends to cause temperature drops, potentially leading to cold spots. Therefore, the outermost peripheral portion on the wafer support surface of the ceramic substrate becomes a temperature anomaly, potentially reducing heat uniformity.

[0008] Therefore, this disclosure was made to solve the above-mentioned problems, and its purpose is to provide a ceramic heater capable of improving the heat uniformity of a surface and a holding member having the ceramic heater.

[0009] Solution for solving the problem

[0010] To address the aforementioned issues, this disclosure provides a ceramic heater, which is a plate-shaped ceramic heater comprising: a ceramic substrate; and a heating element embedded in the ceramic substrate, wherein the linear heating wires of the heating element are formed in a generally concentric circular shape. The ceramic heater is characterized in that, when viewed from the thickness direction of the ceramic heater, the heating element comprises: a first pair of heating wires and a second pair of heating wires, each being a pair of heating wires formed by two adjacent heating wires in the radial direction of the heating element. The first pair of heating wires and the second pair of heating wires are separated in the circumferential direction of the heating element by a predetermined separation region. The first fold-back section connects the ends of the two heating wires constituting the first heating wire pair to each other on the separation region side; and the second fold-back section connects the ends of the two heating wires constituting the second heating wire pair to each other on the separation region side. In the pair of fold-back sections formed by the first fold-back section and the second fold-back section, the interval between the first fold-back section and the second fold-back section at one end of the pair of fold-back sections in the radial direction of the heating element is narrower than the interval between the first fold-back section and the second fold-back section at the central portion of the pair of fold-back sections in the radial direction of the heating element.

[0011] According to this technical solution, the interval between the pair of folded-back portions is narrower at one end in the radial direction, thus increasing the heating amount around that end in the radial direction. Therefore, it is possible to suppress the formation of cold spots around the end in the radial direction where the temperature tends to decrease. Furthermore, the interval between the pair of folded-back portions is wider at the center in the radial direction, thus reducing the heating amount around the center in the radial direction. Therefore, it is possible to suppress the formation of hot spots around the center in the radial direction where the temperature tends to increase. Therefore, the temperature distribution around the pair of folded-back portions can be improved, thereby enhancing the surface heat uniformity of the ceramic heater.

[0012] Preferably, in the above technical solution, the end of the pair of folded-back portions on one side of the heating element in the radial direction is the end of the pair of folded-back portions on the outer peripheral side of the heating element in the radial direction, and the interval between the first folded-back portion and the second folded-back portion at the end of the pair of folded-back portions on the outer peripheral side of the heating element in the radial direction is narrower than the interval between the first folded-back portion and the second folded-back portion at the end of the pair of folded-back portions on the inner peripheral side of the heating element in the radial direction.

[0013] According to this technical solution, the interval between the pair of folded-back portions is narrower at the radially outer peripheral end, thus increasing the heating amount around the radially outer peripheral end. Therefore, it is possible to suppress cold spots at the radially outer peripheral end where a temperature drop is likely to occur, i.e., in the portion where the heating element is not positioned due to the folding back (specifically, the portion located radially further outward than the separation area). Consequently, the surface heat uniformity of the heater can be improved.

[0014] Another technical solution of this disclosure, completed to solve the above-mentioned problem, is a ceramic heater, which is a plate-shaped ceramic heater, comprising: a ceramic substrate; and a heating element embedded in the ceramic substrate, wherein the linear heating wires of the heating element are formed in a generally concentric circle shape. The ceramic heater is characterized in that, when viewed from the thickness direction of the ceramic heater, the heating element comprises: a first pair of heating wires and a second pair of heating wires, each consisting of two adjacent heating wires in the radial direction of the heating element, the first pair of heating wires and the second pair of heating wires being separated in the circumferential direction of the heating element by a predetermined separation region; and a first fold-back portion that separates the two heating wires constituting the first pair of heating wires from the separation region side. The ends of the first and second fold-back portions are connected to each other; and the second fold-back portion connects the ends of the two heating wires constituting the second heating wire pair to each other on the separation region side. In the pair of fold-back portions consisting of the first and second fold-back portions, the interval between the first and second fold-back portions at the outer peripheral end of the pair of fold-back portions in the radial direction of the heating element is narrower than the interval between the first and second fold-back portions at the inner peripheral end of the pair of fold-back portions in the radial direction of the heating element. Near the position of the outer peripheral end, the first and second fold-back portions are formed toward the separation region side, thereby narrowing the interval between the first and second fold-back portions.

[0015] According to this technical solution, the interval between the pair of folded-back portions is narrower at the radially outer peripheral end, thus increasing the heating amount around the radially outer peripheral end. Therefore, it is possible to suppress cold spots at the radially outer peripheral end where a temperature drop is likely to occur, i.e., in the portion where the heating element is not positioned due to the folding back of the heating element. Consequently, the surface heat uniformity of the heater can be improved.

[0016] Preferably, in the above technical solution, the interval between the first fold-back portion and the second fold-back portion narrows as it moves from the position of the inner circumferential end of the heating element in the radial direction to the position of the outer circumferential end of the heating element in the radial direction.

[0017] According to this technical solution, in a pair of folded-back sections, the heating amount can be increased as the position moves from the radially inner circumferential end to the outer circumferential end. Therefore, the surface heat uniformity of the heater can be improved more effectively.

[0018] Preferably, in the above technical solution, the pair of folded-back portions are formed at the outermost periphery of the heating element.

[0019] In the portion of the outer periphery further radially than the outermost circumference of the heating element, no heating element is disposed. Therefore, there is a tendency for temperature to decrease, especially in the portion further radially than the separation region between the pair of folds located at the outermost circumference of the heating element, where the temperature tends to decrease significantly, and cold spots are easily generated. Therefore, according to this technical solution, the heating amount around the radially outer periphery end of the pair of folds located at the outermost circumference of the heating element can be increased, thereby suppressing the generation of cold spots in the portion further radially than the separation region between the pair of folds located at the outermost circumference of the heating element.

[0020] Preferably, in the above technical solution, the ceramic substrate includes: a first portion having a holding surface for holding an object; and a second portion disposed on the side opposite to the holding surface side in the thickness direction of the ceramic heater relative to the first portion, wherein, when viewed from the thickness direction of the ceramic heater, the second portion has an outer periphery larger than that of the first portion, and the heating element is disposed in the first portion.

[0021] In the second part, which is larger than the first part on the outer periphery, no heating element is provided, thus there is a tendency for temperature to drop, making it prone to cold spots. Therefore, according to this technical solution, the interval between the pair of folded-back portions is narrower at the radially outer peripheral end, thereby increasing the heating amount around the radially outer peripheral end. Consequently, cold spots can be suppressed at the radially outer peripheral end where temperature tends to drop, i.e., in the portion where no heating element is provided due to the folding back. Therefore, the surface heat uniformity of the heater can be improved.

[0022] Furthermore, when the heating element is located in the second position, heat may dissipate outwards. However, by placing the heating element in the first position, heat is less likely to dissipate outwards. Therefore, the holding surface of the object being held can be heated more effectively. Consequently, the generation of cold spots can be suppressed, and heat uniformity can be improved.

[0023] Preferably, in the above technical solution, at least one of the inner peripheral side of the corner where the end of the heating element on the radial side or the outer peripheral side of the pair of folded-back portions connects to the first folded-back portion and the inner peripheral side of the corner where the end of the heating element on the separation region side of the heating wire constituting the first heating wire pair connects to the first folded-back portion is formed into a rounded corner shape.

[0024] According to this technical solution, it is possible to suppress the formation of cracks at the corners of the heating element.

[0025] Another technical solution of this disclosure, which was completed to solve the above-mentioned problem, is a holding device that holds an object, characterized in that the holding device has the ceramic heater.

[0026] The effects of the invention

[0027] The ceramic heater and retaining member disclosed herein can improve the surface heat uniformity of the ceramic heater. Attached Figure Description

[0028] Figure 1 This is a schematic perspective view of the electrostatic chuck of this embodiment.

[0029] Figure 2 This is an XY plan view of the electrostatic chuck of this embodiment.

[0030] Figure 3 This is an XZ sectional view of the ceramic component in this embodiment.

[0031] Figure 4 This is a top view of the heating element in this embodiment.

[0032] Figure 5 This is an enlarged view of a pair of folded-back portions located at the outermost periphery of the heating element in this embodiment, and their surrounding area.

[0033] Figure 6 This is a diagram showing a modified example of a pair of folded sections located at the outermost periphery of the heating element.

[0034] Figure 7 This is a diagram showing a modified example of a pair of folded sections located at the outermost periphery of the heating element.

[0035] Figure 8 This is a diagram showing a modified example of a pair of folded sections located at the outermost periphery of the heating element.

[0036] Figure 9 This is an enlarged view of a pair of folded sections and their surroundings located at the outermost periphery of the heating element in the prior art.

[0037] Figure 10 It is an evaluation result of the temperature distribution of the portion of the holding surface of the ceramic component in the prior art that corresponds to a pair of folded-back portions and their surrounding positions located at the outermost periphery of the heating element. Detailed Implementation

[0038] Embodiments of the ceramic heater and retaining member of this disclosure will be described. In this embodiment, the ceramic member 10 will be used as an example of a ceramic heater, and the electrostatic chuck 1 will be used as an example of a retaining member.

[0039] <Overall Description of Electrostatic Chuck>

[0040] The electrostatic chuck 1 of this embodiment is a device that uses electrostatic attraction to hold a semiconductor wafer W, for example, used to fix the semiconductor wafer W in the vacuum chamber of a semiconductor manufacturing apparatus. Furthermore, the semiconductor wafer W is an example of the "object" of this disclosure.

[0041] like Figure 1 As shown, the electrostatic chuck 1 has a ceramic component 10, a base component 20, and a bonding layer 30 that joins the ceramic component 10 and the base component 20 together. Furthermore, the ceramic component 10 is an example of the "ceramic heater" or "ceramic substrate" of this disclosure.

[0042] Additionally, in the following explanations, for ease of clarification, such as... Figure 1 The XYZ axes are defined as shown. Here, the Z-axis is the direction of the central axis Ca of the electrostatic chuck 1 (in...). Figure 1 The axis is the vertical axis (the middle axis is the vertical axis), and the X-axis and Y-axis are the radial axes of the electrostatic chuck 1.

[0043] like Figure 1 As shown, the ceramic component 10 is a plate-shaped component, more specifically a disk-shaped component, formed of ceramic (ceramic substrate). Specifically, the ceramic component 10 comprises two disks of different diameters such that the central axis Ca (reference) Figure 2 The common way of overlapping (more specifically, the upper disk-shaped part 10a with a smaller diameter overlaps on the lower disk-shaped part 10b with a larger diameter) is a stepped disk shape.

[0044] In this way, the lower layer 10b is located on the side opposite to the holding surface 11 in the thickness direction (the direction consistent with the Z-axis, the vertical direction) of the ceramic member 10, and has a larger outer perimeter than the upper layer 10a when viewed from the thickness direction of the ceramic member 10. Furthermore, the upper layer 10a is an example of the "first part" of this disclosure, and the lower layer 10b is an example of the "second part".

[0045] Various types of ceramics can be used, but from the viewpoints of strength, wear resistance, and plasma resistance, ceramics with alumina (Al2O3) or aluminum nitride (AlN) as the main component are preferred. Furthermore, the term "main component" here refers to the component with the highest proportion (e.g., a component with a volume content of 90 vol% or more).

[0046] like Figures 1-3 As shown, the ceramic component 10 includes: a holding surface 11 (upper surface) that holds the semiconductor wafer W; and a lower surface 12 that is provided on the side opposite to the holding surface 11 in the thickness direction (i.e., the Z-axis direction) of the ceramic component 10. Furthermore, in this embodiment, the upper layer 10a includes the holding surface 11. Additionally, the holding surface 11 is an example of the surface of the "ceramic heater" of this disclosure.

[0047] Furthermore, regarding the diameter of the ceramic component 10, the lower layer 10b is larger than the upper layer 10a, with the upper layer 10a being, for example, about 150 to 300 mm and the lower layer 10b being, for example, about 180 to 400 mm. The thickness of the ceramic component 10 is, for example, about 2 to 6 mm. In addition, the thermal conductivity of the ceramic component 10 is preferably in the range of 10 to 50 W / mK (more preferably, 18 to 30 W / mK).

[0048] Furthermore, the ceramic component 10 has a chuck electrode (adsorption electrode) (not shown) inside. By applying a voltage to the chuck electrode (not shown), an electrostatic attraction is generated on the chuck electrode, and the semiconductor wafer W is adsorbed and held on the holding surface 11 by the electrostatic attraction.

[0049] The base member 20 is disposed on the side opposite to the retaining surface 11 relative to the ceramic member 10. The base member 20 is formed, for example, in a cylindrical shape. Furthermore, the base member 20 is formed, for example, of a metal (e.g., aluminum, aluminum alloy), but may also be made of a material other than metal.

[0050] Moreover, such as Figure 1 As shown, the base member 20 includes an upper surface 21 and a lower surface 22, which is located on the side opposite to the upper surface 21 in the thickness direction (i.e., the Z-axis direction) of the base member 20. Furthermore, 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.

[0051] The diameter of the base member 20 is, for example, about 180 to 400 mm. Furthermore, the thickness (dimension in the Z-axis direction) of the base member 20 is, for example, about 20 to 50 mm. Additionally, the thermal conductivity of the base member 20 (assuming it is aluminum) is preferably in the range of 160 to 250 W / mK (preferably, about 230 W / mK).

[0052] The bonding layer 30 is disposed between the lower surface 12 of the ceramic component 10 and the upper surface 21 of the base component 20, bonding the ceramic component 10 and the base component 20 in a heat-conducting manner.

[0053] The bonding layer 30 is composed of an adhesive material containing a resin (such as a silicone resin, acrylic resin, or epoxy resin) with thermally conductive filler. The thickness (dimension in the Z-axis direction) of the bonding layer 30 is, for example, approximately 0.1 to 1.5 mm. Furthermore, the thermal conductivity of the bonding layer 30 is, for example, 1.0 W / mK. Additionally, the thermal conductivity of the bonding layer 30 (assuming it is a silicone resin) is preferably in the range of 0.1 to 2.0 W / mK (preferably 0.5 to 1.5 W / mK).

[0054] <About heating elements>

[0055] In this embodiment, such as Figure 3 As shown, a heating element 41 is provided inside the upper layer 10a of the ceramic component 10. That is, the heating element 41 is embedded in the upper layer 10a of the ceramic component 10. Furthermore, the heating element 41 is used to heat the semiconductor wafer W. The heating element 41 is formed, for example, of a tungsten or molybdenum alloy, but it can also be made of other metals.

[0056] like Figure 4 As shown, when viewed from the thickness direction of the ceramic component 10, the linear heating wires 42 of the heating element 41 are formed in a generally concentric circle shape, and the line width of the heating wires 42 is about 0.1 mm to 1.0 mm. The heating element 41 has a pair of heating wires 43 formed by two heating wires 42 arranged adjacent to each other in the radial direction (at least partially) of the heating element 41. The two heating wires 42 constituting the pair of heating wires 43 are formed in the same arc shape. In addition, in Figure 4 In the example shown, the heating element 41 has a plurality of pairs of heating wires 43, but it is sufficient to have at least two pairs of heating wires 43.

[0057] like Figure 5 As shown, the heating element 41 has a first heating wire pair 43a and a second heating wire pair 43b as a pair of heating wires 43. The first heating wire pair 43a and the second heating wire pair 43b are separated in the circumferential direction of the heating element 41 by a predetermined separation region 44.

[0058] Furthermore, the heating element 41 includes a first fold-back portion 45a and a second fold-back portion 45b as a pair of fold-back portions 45. The first fold-back portion 45a and the second fold-back portion 45b are arranged separately in the circumferential direction of the heating element 41, separated by a predetermined separation region 44. The first fold-back portion 45a connects the ends 42a of the two heating wires 42 constituting the first heating wire pair 43a on the separation region 44 side to each other. The second fold-back portion 45b connects the ends 42b of the two heating wires 42 constituting the second heating wire pair 43b on the separation region 44 side to each other.

[0059] in addition, Figure 5 A pair of heating wires 43, a separation region 44, and a pair of folded-back portions 45 are shown at the outermost periphery of the heating element 41, but a pair of heating wires 43, a separation region 44, and a pair of folded-back portions 45 are also shown at locations other than the outermost periphery of the heating element 41.

[0060] <Methods for improving the heat uniformity of the surface>

[0061] Here, in the case where the heating element 41 is disposed inside the upper layer 10a of the ceramic component 10 as described above, in the prior art, at the outermost periphery of the heating element 41, the interval δ between the first fold-back portion 45a and the second fold-back portion 45b is constant along the radial direction of the heating element 41, or, as... Figure 9 As shown, the radial spacing δ on the outer periphery of the heating element 41 (δ2 in the figure) is greater than the radial spacing δ on the inner periphery (δ1 in the figure).

[0062] Furthermore, in such prior art, in the portion where the heating element 41 is not positioned due to the heating wire 42 of the heating element 41 folding back at a pair of fold-back portions 45 (more specifically, located on the outer peripheral side (radially outer peripheral side) of the separation region 44), Figure 9 The periphery of the upper part of the surface (the area around the surface) experiences a drop in temperature, creating cold spots (temperature anomalies), making it difficult to ensure uniform heat distribution across surface 11. Additionally, as... Figure 10 As shown, as an evaluation result of the temperature distribution in the retaining surface 11, it was found that a region with a lower temperature was generated on the outer periphery of the retaining surface 11.

[0063] Therefore, in this embodiment, a pair of folded-back portions 45 (in the outermost periphery of the heating element 41) are formed. Figure 4 In the part α) enclosed by the dashed line, such as Figure 4 , Figure 5 As shown, a pair of folded portions 45 are formed in a kana-ha shape (narrowed towards the outer periphery of the heating element 41). Furthermore, the gap δ (hereinafter referred to as "gap δ") between the first folded portion 45a and the second folded portion 45b narrows towards the outer periphery of the heating element 41. Figure 4 , Figure 5 (The upper side) gradually narrows.

[0064] Therefore, in this embodiment, as Figure 5 As shown, the distance δ at the outer peripheral end 45-2 (radially outer peripheral end) of a pair of folded-back portions 45 is narrower than the distance δ at the inner peripheral end 45-1 (radially inner peripheral end) of a pair of folded-back portions 45. That is, for distance δ, the outer peripheral distance δ2 is narrower than the inner peripheral distance δ1. In addition, although the outer peripheral distance δ2 is narrower, it maintains a distance that does not short-circuit.

[0065] Here, the inner circumferential spacing δ1 is the spacing δ at the end 45-1 of the inner circumferential side of the pair of folded-back portions 45 in the radial direction of the heating element 41. Furthermore, the outer circumferential spacing δ2 is the spacing δ at the end 45-2 of the outer circumferential side of the pair of folded-back portions 45 in the radial direction of the heating element 41. Additionally, the spacing δ1 on the inner circumferential side and the spacing δ2 on the outer circumferential side are 0.5 mm to 5.0 mm; as an example, the inner circumferential spacing δ1 is 3.5 mm and the outer circumferential spacing δ2 is 1.0 mm.

[0066] Furthermore, the inner circumferential end 45-1 and the outer circumferential end 45-2 are examples of the "radial end on one side" of this disclosure. In addition, the outer circumferential end 45-2 is an example of the "radial outer circumferential end" of this disclosure.

[0067] Moreover, in a pair of fold-back sections 45, such as Figure 5 As shown, the interval δ gradually narrows from the position of the inner peripheral end 45-1 to the position of the outer peripheral end 45-2.

[0068] Furthermore, from another perspective, in a pair of fold-back sections 45, such as Figure 5 As shown, the spacing δ at the outer peripheral end 45-2 is narrower than the spacing δ at the radially central portion 45-3. That is, in a pair of folded-back portions 45, the spacing δ2 on the outer peripheral side is narrower than the spacing δ3 in the central portion. Furthermore, the spacing δ3 in the central portion is the spacing δ at the radially central portion 45-3 of the heating element 41 in a pair of folded-back portions 45. In addition, the central portion 45-3 is located at a position equidistant from the inner peripheral end 45-1 and the outer peripheral end 45-2 (i.e., one radially extending end and the other radially extending end of the heating element 41).

[0069] In this way, the interval δ between the pair of folded-back portions 45 formed at the outermost periphery of the heating element 41 is narrower at the outer peripheral end 45-2, thus increasing the heating amount around the outer peripheral end 45-2. Therefore, the tendency for temperature decrease at the outermost periphery of the heating element 41 can be suppressed, that is, the portion of the heating element 41 where the heating wire 42 is folded back at the pair of folded-back portions 45 and the heating element 41 is not disposed (more specifically, the portion located on the outer periphery side of the separation region 44). Figure 5 The upper part of the ceramic component 10 generates cold spots. Therefore, the heat uniformity of the holding surface 11 of the ceramic component 10 can be improved.

[0070] <Effects of this implementation method>

[0071] As described above, in this embodiment, the interval δ at the end of the pair of folded-back portions 45 on one side of the heating element 41 in the radial direction, i.e., the interval δ2 on the outer peripheral side, is narrower than the interval δ3 in the central portion.

[0072] In this way, the interval δ is narrower at the end 45-2 on the outer peripheral side, thus increasing the heating amount around the end 45-2 on the outer peripheral side. Therefore, it is possible to suppress the formation of cold spots around the end 45-2 on the outer peripheral side, where there is a tendency for temperature to drop.

[0073] Furthermore, the spacing δ at the radially central portion 45-3 is wider than the spacing δ at the outer peripheral end portion 45-2, thus reducing the heating around the radially central portion 45-3 of the pair of folded-back portions 45. Therefore, it is possible to suppress the generation of hot spots around the radially central portion 45-3 of the pair of folded-back portions 45, which tend to experience temperature increases.

[0074] Furthermore, in a pair of folded-back portions 45, the spacing δ2 on the outer periphery is narrower than the spacing δ1 on the inner periphery.

[0075] In this way, the spacing δ is narrower at the outer peripheral end 45-2, thus increasing the heating amount around the outer peripheral end 45-2. Therefore, it is possible to suppress the formation of cold spots around the outer peripheral end 45-2, where there is a tendency for temperature to drop. Consequently, the heat uniformity of the holding surface 11 of the ceramic component 10 can be improved.

[0076] Furthermore, the interval δ gradually narrows from the position of the inner peripheral end 45-1 to the position of the outer peripheral end 45-2.

[0077] Therefore, in the pair of folded-back portions 45, the heating amount can be increased from the position of the inner peripheral end 45-1 to the position of the outer peripheral end 45-2. Thus, the heat uniformity of the holding surface 11 of the ceramic component 10 can be improved more effectively.

[0078] Furthermore, a pair of folded portions 45, as described above, are formed at the outermost periphery of the heating element 41, that is, a pair of folded portions 45 in the shape of kana ハ are formed.

[0079] Therefore, in the pair of fold-back portions 45 located at the outermost periphery of the heating element 41, the heating amount around the periphery of the outer peripheral end 45-2 can be increased, thus suppressing the generation of cold spots in the portion closer to the outer periphery than the separation region 44, which is located between the pair of fold-back portions 45 located at the outermost periphery of the heating element 41.

[0080] Furthermore, in this embodiment, such a heating element 41 is disposed inside the upper layer 10a of the ceramic component 10.

[0081] In the outer peripheral portion of the lower layer 10b, which is larger than the upper layer 10a, no heating element 41 is disposed. Therefore, there is a tendency for the temperature to drop, and cold spots are easily generated. Therefore, according to this embodiment, the spacing δ is narrower at the outer peripheral end 45-2, thereby increasing the heating amount around the outer peripheral end 45-2. Therefore, cold spots can be suppressed in the outer peripheral end 45-2 area where there is a tendency for the temperature to drop, i.e., in the portion where the heating element 41 is not disposed due to its retraction. Therefore, the heat uniformity of the holding surface 11 of the ceramic member 10 can be improved.

[0082] Furthermore, when the heating element 41 is located in the lower layer 10b, heat may dissipate outwards. However, by placing the heating element 41 in the upper layer 10a, heat is less likely to dissipate outwards. Therefore, the holding surface 11 can be heated more effectively. Consequently, the generation of cold spots can be suppressed, and heat uniformity can be improved.

[0083] In addition, such as Figure 5 As shown, alternatively, at the outer peripheral end 45-2 of one of the pair of folded-back portions 45, the inner peripheral sides of corner portion 46a and corner portion 46b are provided with rounded corner-shaped portions 47, forming a rounded corner shape (i.e., an arc shape). Here, corner portion 46a is the portion where the end 42a on the separation region 44 side of the heating wire 42 constituting the first heating wire pair 43a connects to the first folded-back portion 45a, and is located on the outer peripheral side. Similarly, corner portion 46b is the portion where the end 42b on the separation region 44 side of the heating wire 42 constituting the second heating wire pair 43b connects to the second folded-back portion 45b, and is also located on the outer peripheral side. Alternatively, only the inner peripheral side of either corner portion 46a or corner portion 46b may be provided with rounded corner-shaped portions 47, forming a rounded corner shape. The radius of curvature R of the rounded corner-shaped portion 47 is, for example, 0.05 mm to 0.3 mm, and as an example, 0.1 mm.

[0084] Therefore, the width of the heating wire 42 can be increased in the corners 46a and 46b, which are formed into acute angles, thereby suppressing the occurrence of cracks in the heating wire 42.

[0085] In addition, as a variation, such as Figure 6 As shown, the pair of folded-back portions 45 can also be formed in a stepped shape. Figure 6 In the example shown, for a pair of folded-back portions 45, they are formed in a stepped shape such that the first folded-back portion 45a and the second folded-back portion 45b are offset toward the separation region 44 from the position of the end 45-2 on the outer periphery side.

[0086] In addition, as other variations, such as Figure 7 , Figure 8 As shown, for a pair of folded-back portions 45, the first folded-back portion 45a and the second folded-back portion 45b can be formed into an arc shape, or a shape resembling the kanji "く", such that the distance between them narrows by δ as they move from the radially central portion 45-3 toward the inner peripheral end 45-1 and the outer peripheral end 45-2. In this case, the distance δ at the radially one end, i.e., the position of the inner peripheral end 45-1 and the outer peripheral end 45-2, can be narrower than the distance δ at the radially central portion 45-3.

[0087] Furthermore, in the heating element 41, multiple pairs of folded-back portions 45 are formed, and they are also formed at positions other than the outermost periphery of the heating element 41. At this time, for at least one pair of folded-back portions 45 among the multiple pairs of folded-back portions 45, it is acceptable to form a pair of folded-back portions 45 in the shape of kana "ハ", ​​a stepped shape, an arc shape, or a kana "く".

[0088] Alternatively, at a position other than the outermost periphery of the heating element 41, a pair of folded portions 45 may be formed in a kana-ha shape that narrows toward the inner periphery of the heating element 41, thereby the interval δ gradually narrows toward the inner periphery of the heating element 41.

[0089] Furthermore, the above-described embodiments are merely illustrative and do not limit this disclosure in any way. Various modifications and variations can be made without departing from its spirit.

[0090] Explanation of reference numerals in the attached figures

[0091] 1. Electrostatic chuck; 10. Ceramic component; 10a. Upper layer; 11. Holding surface; 41. Heating element; 42. Heating wire; 42a. End (on the separation area side of the heating wire); 43. A pair of heating wires; 43a. First pair of heating wires; 43b. Second pair of heating wires; 44. Separation area; 45. A pair of fold-back sections; 45a. First fold-back section; 45b. Second fold-back section; 45-1. End on the inner circumferential side (of the pair of fold-back sections); 45-2. End on the outer circumferential side (of the pair of fold-back sections); 45-3. Central section in the radial direction (of the pair of fold-back sections); 46a. Corner; 46b. Corner; 47. Rounded corner section; W. Semiconductor wafer; δ. Spacing (between the first and second fold-back sections); δ1. Spacing on the inner circumferential side; δ2. Spacing on the outer circumferential side; δ3. Spacing in the central section; α. Part; R. Radius of curvature.

Claims

1. A ceramic heater, which is a plate-shaped ceramic heater, comprising: a ceramic substrate; and a heating element embedded in the ceramic substrate, wherein the linear heating wires of the heating element are formed in a generally concentric circular shape, characterized in that... When viewed from the thickness direction of the ceramic heater, The heating element comprises: The first heating wire pair and the second heating wire pair are each a pair of heating wires consisting of two adjacent heating wires in the radial direction of the heating element. The first heating wire pair and the second heating wire pair are arranged separately in the circumferential direction of the heating element, separated by a predetermined separation area. The first fold-back section connects the ends of the two heating wires constituting the first heating wire pair on the separated region side to each other; and The second fold-back section connects the ends of the two heating wires forming the second heating wire pair on the separated region side to each other. In the pair of fold-back sections formed by the first fold-back section and the second fold-back section, The distance between the first fold-back portion and the second fold-back portion at one end of the pair of fold-back portions in the radial direction of the heating element is narrower than the distance between the first fold-back portion and the second fold-back portion at the central portion of the pair of fold-back portions in the radial direction of the heating element. The pair of folded-back portions are formed at the outermost periphery of the heating element. The first heating wire pair and the second heating wire pair are connected together at a location outside the separation area.

2. The ceramic heater according to claim 1, wherein, The end of the pair of folded-back portions on one radial side of the heating element is the end of the pair of folded-back portions on the outer peripheral side of the heating element in the radial direction. The distance between the first fold-back portion and the second fold-back portion at the outer peripheral end of the pair of fold-back portions in the radial direction of the heating element is narrower than the distance between the first fold-back portion and the second fold-back portion at the inner peripheral end of the pair of fold-back portions in the radial direction of the heating element.

3. A ceramic heater, which is a plate-shaped ceramic heater, comprising: a ceramic substrate; and a heating element embedded in the ceramic substrate, wherein the linear heating wires of the heating element are formed in a generally concentric circular shape, characterized in that... When viewed from the thickness direction of the ceramic heater, The heating element comprises: The first heating wire pair and the second heating wire pair are each a pair of heating wires consisting of two adjacent heating wires in the radial direction of the heating element. The first heating wire pair and the second heating wire pair are arranged separately in the circumferential direction of the heating element, separated by a predetermined separation area. The first fold-back section connects the ends of the two heating wires constituting the first heating wire pair on the separated region side to each other; and The second fold-back section connects the ends of the two heating wires forming the second heating wire pair on the separated region side to each other. In the pair of fold-back sections formed by the first fold-back section and the second fold-back section, The distance between the first fold-back portion and the second fold-back portion at the outer peripheral end of the pair of fold-back portions in the radial direction of the heating element is narrower than the distance between the first fold-back portion and the second fold-back portion at the inner peripheral end of the pair of fold-back portions in the radial direction of the heating element. Near the end of the outer periphery, the first fold-back portion and the second fold-back portion are formed laterally toward the separation region, thereby narrowing the gap between the first fold-back portion and the second fold-back portion. The pair of folded-back portions are formed at the outermost periphery of the heating element. The first heating wire pair and the second heating wire pair are connected together at a location outside the separation area.

4. The ceramic heater according to claim 2 or 3, wherein, The interval between the first fold-back portion and the second fold-back portion narrows as it moves from the position of the inner circumferential end of the heating element in the radial direction to the position of the outer circumferential end of the heating element in the radial direction.

5. The ceramic heater according to any one of claims 1 to 3, wherein, The ceramic substrate comprises: The first part has a holding surface for holding the object; and The second portion is located on the side opposite to the holding surface side in the thickness direction of the ceramic heater relative to the first portion, and when viewed from the thickness direction of the ceramic heater, the second portion has a larger outer perimeter than the first portion. The heating element is located at the first part.

6. The ceramic heater according to any one of claims 1 to 3, wherein, At the end of the heating element on one radial side or the outer peripheral side of one of the pair of folded-back portions, At least one of the inner circumferential side of the corner where the end of the heating wire on the separation region side of the first heating wire pair connects to the first fold-back portion and the inner circumferential side of the corner where the end of the heating wire on the separation region side of the second heating wire pair connects to the second fold-back portion is formed into a rounded corner shape.

7. A ceramic heater, which is a plate-shaped ceramic heater, comprising: a ceramic substrate; and a heating element embedded in the ceramic substrate, wherein the linear heating wires of the heating element are formed in a generally concentric circular shape, characterized in that... When viewed from the thickness direction of the ceramic heater, The heating element comprises: The first heating wire pair and the second heating wire pair are each a pair of heating wires consisting of two adjacent heating wires in the radial direction of the heating element. The first heating wire pair and the second heating wire pair are arranged separately in the circumferential direction of the heating element, separated by a predetermined separation area. The first fold-back section connects the ends of the two heating wires constituting the first heating wire pair on the separated region side to each other; and The second fold-back section connects the ends of the two heating wires forming the second heating wire pair on the separated region side to each other. In the pair of fold-back sections formed by the first fold-back section and the second fold-back section, The interval between the first and second fold-back portions at their outer peripheral ends in the radial direction of the heating element, and the interval between the first and second fold-back portions at their inner peripheral ends in the radial direction of the heating element, are narrower than the interval between the first and second fold-back portions at their central portion in the radial direction of the heating element. The pair of folded-back portions are formed at the outermost periphery of the heating element. The first heating wire pair and the second heating wire pair are connected together at a location outside the separation area.

8. The ceramic heater according to any one of claims 1 to 3 and 7, wherein, The end of the heating wire of the heating element is located on the side opposite to the separation region relative to the pair of folded-back portions.

9. A retaining member that retains an object, characterized in that, The retaining member has a ceramic heater as described in any one of claims 1 to 8.

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