Ceramic heater and holding member

Abstract

To provide a holding member capable of improving heat uniformity on a holding surface even if a gas tunnel is included.SOLUTION: An electrostatic chuck 1 comprises a holding surface 11, a bottom face 12 provided at an opposite side of the holding surface 11 in a Z axis direction, a heater electrode 60 disposed between the holding surface 11 and the bottom face 12 and a gas passage 40 for supplying an inert gas from the side of the bottom face 12 onto the holding surface 11 and holds a semiconductor wafer W on the holding surface 11. The gas passage 40 includes a gas tunnel 44 which is disposed while extending in a plane direction. The heater electrode 60 includes arcuate parts 62 and 62 and folded parts 64 and 64 which are disposed at both sides of the gas tunnel 44 along with the gas tunnel 44 so as not to overlap the gas tunnel 44 in a view in the Z axis direction.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] In the semiconductor manufacturing process, an electrostatic chuck (holding member) is used to hold a semiconductor wafer. This electrostatic chuck generates electrostatic attraction to hold the semiconductor wafer on its holding surface. In order to perform various processes on the semiconductor wafer with high accuracy, it is necessary to uniformly control the temperature of the semiconductor wafer (the temperature of the holding surface of the electrostatic chuck).

[0003] An example of such an electrostatic chuck is disclosed in Patent Document 1. The electrostatic chuck disclosed therein has a ceramic insulator (holding member) that holds a semiconductor wafer and an aluminum base for cooling the ceramic insulator. The ceramic insulator is provided with a cooling gas flow passage that supplies a cooling gas between the semiconductor wafer and the electrostatic chuck, and a heater for heating the semiconductor wafer. This electrostatic chuck is capable of uniformly controlling the temperature of the semiconductor wafer by adjusting the flow rate of the coolant and the flow rate of the cooling gas flowing through the aluminum base and the heat generation amount of the heater. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-12795 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above electrostatic chuck, the cooling gas flow path acts as a heat insulating layer, and thus heat transfer is hindered in the area where the cooling gas flow path is formed. Therefore, the area directly above the cooling gas flow path on the holding surface is likely to have a higher temperature than other areas. On the other hand, the area directly above the area where the heater is not disposed on the holding surface is likely to have a lower temperature than the area directly above the area where the heater is disposed. For these reasons, the above electrostatic chuck may have a poor thermal uniformity on the holding surface.

[0006] Therefore, the present disclosure has been made to solve the above-mentioned problems, and has an object to provide a holding member that can improve the thermal uniformity on the holding surface. [Means for solving the problem]

[0007] In order to solve the above problems, one aspect of the present disclosure is to A holding member for holding an object on the first surface, the holding member comprising: a first surface; a second surface provided on an opposite side to the first surface in a thickness direction; a heater electrode disposed between the first surface and the second surface; and a gas passage for supplying an inert gas onto the first surface from the second surface side, The gas passage includes a gas tunnel extending in a planar direction, The heater electrode is characterized in having a first heater line and a second heater line arranged on both sides of the gas tunnel along the gas tunnel so as not to overlap with the gas tunnel when viewed in the thickness direction.

[0008] This holding member includes a first heater line and a second heater line as heater electrodes, and the first heater line and the second heater line are arranged on both sides of the gas tunnel along the gas tunnel so as not to overlap with the gas tunnel when viewed in the thickness direction. That is, the heater electrodes (the first heater line and the second heater line) are arranged so as to sandwich the gas tunnel.

[0009] This makes it possible to suppress a temperature rise in the region directly above the gas tunnel on the first surface, while suppressing a temperature drop in the region directly above the portion where the heater electrode is not disposed. Therefore, it is possible to reduce the temperature difference between the region directly above the portion where the heater electrode is not disposed on the first surface and the region directly above the portion where the heater electrode is disposed. Therefore, it is possible to improve the thermal uniformity on the first surface.

[0010] In the above-mentioned holding member, The first heater line and the second heater line are preferably heater lines in a portion of the heater electrode where bent portions are arranged to face each other. The opposing arrangement here means that a portion of the first heater line and a portion of the second heater line are opposed to each other.

[0011] Here, the temperature in the region where the bent portions of the heater electrodes are arranged opposite to each other tends to be lower than in other regions, and therefore the region directly above the region where the bent portions of the heater electrodes are arranged opposite to each other on the first surface may become a temperature singularity.

[0012] Therefore, by arranging the first heater line and the second heater line on both sides of the gas tunnel along the gas tunnel so as not to overlap the gas tunnel when viewed in the thickness direction in the region where the bent portions are arranged opposite to each other, it is possible to reduce the temperature difference between the region where the bent portions are arranged opposite to each other and other regions. This makes it possible to prevent the occurrence of temperature singularities on the first surface, thereby further improving the thermal uniformity on the first surface.

[0013] In any one of the above-mentioned holding members, As viewed in the thickness direction, the distance between the first heater line and the gas tunnel is preferably the same as the distance between the second heater line and the gas tunnel.

[0014] By making the distances between the gas tunnel and the first heater line and between the gas tunnel and the second heater line equal, the temperature distribution between the first heater line and the gas tunnel and the temperature distribution between the second heater line and the gas tunnel can be made equal. Therefore, the temperature distribution between the first heater line and the second heater line can be made uniform. Therefore, the thermal uniformity on the first surface can be further improved.

[0015] In any one of the above-mentioned holding members, The distance between the first heater line and the second heater line disposed opposite to each other is preferably smaller than the length of the heater line having a longer opposing straight portion out of the first heater line or the second heater line.

[0016] By setting the distance between the first heater line and the second heater line (the distance between the first heater line and the second heater line and the gas line when viewed in the thickness direction) in this manner, the temperature singularity occurring between the first heater line and the second heater line can be efficiently heated. Therefore, the temperature difference between the temperature singularity and other regions on the first surface can be further reduced. Therefore, the thermal uniformity on the first surface can be reliably improved. Effect of the Invention

[0017] According to the present disclosure, it is possible to provide a holding member that can improve the thermal uniformity on the holding surface even when a gas tunnel is provided. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic perspective view of an electrostatic chuck according to an embodiment. [Diagram 2] 2 is a partial cross-sectional view of an XZ cross section of an electrostatic chuck according to an embodiment. FIG. [Diagram 3] FIG. 2 is a diagram showing the shape of a gas tunnel as viewed in the Z-axis direction. [Figure 4] 4 is a diagram showing the shape of a heater electrode as viewed in the Z-axis direction. FIG. [Diagram 5] FIG. 4 is a diagram showing the positional relationship between a gas tunnel and a heater electrode. [Figure 6] 6 is an enlarged view of the part circled by the dashed dotted line in FIG. 5. FIG. [Figure 7] 13A and 13B are diagrams illustrating modified examples of a bent portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] A holding member according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In this embodiment, the holding member will be described as being applied to an electrostatic chuck used in semiconductor manufacturing equipment such as a film forming apparatus (such as a CVD film forming apparatus or a sputtering film forming apparatus) or an etching apparatus (such as a plasma etching apparatus).

[0020] 1 to 6, an electrostatic chuck 1 according to the present embodiment will be described. The electrostatic chuck 1 according to the present embodiment is a device that attracts and holds a semiconductor wafer W (object) by electrostatic attraction, and is used, for example, to fix the semiconductor wafer W in a vacuum chamber of a semiconductor manufacturing device. As shown in FIG. 1, the electrostatic chuck 1 has a plate-shaped member 10, a base member 20, and a bonding layer 30 that bonds the plate-shaped member 10 and the base member 20 together.

[0021] In the following description, for convenience of explanation, the X, Y and Z axes are defined as shown in Fig. 1. Here, the Z axis is an axis in the axial direction of the electrostatic chuck 1 (the vertical direction in Fig. 1) and is an example of the "thickness direction" in the present disclosure. The X and Y axes are axes in the radial direction of the electrostatic chuck 1.

[0022] As shown in Fig. 1, the plate-shaped member 10 is a disk-shaped member and is made of ceramics. Specifically, the plate-shaped member 10 has a stepped disk shape in which two disks of different diameters are overlapped with a common central axis (more specifically, a disk-shaped upper stage portion 10a having a smaller diameter is overlapped on a disk-shaped lower stage portion 10b having a larger diameter). In this way, the lower stage portion 10b is provided on the opposite side of the holding surface 11 side with respect to the upper stage portion 10a in the thickness direction of the plate-shaped member 10 (a direction that coincides with the Z-axis direction, a vertical direction), and has a larger outer periphery than the upper stage portion 10a when viewed from the thickness direction of the plate-shaped member 10.

[0023] As the ceramic, various ceramics are used. From the viewpoints of strength, abrasion resistance, plasma resistance, etc., for example, aluminum oxide (alumina, Al 2 O 3 It is preferable to use ceramics mainly composed of aluminum nitride (AlN) or aluminum nitride (AlN). Note that the main component here means the component with the highest content (for example, a component with a volume content of 90 vol% or more).

[0024] 1 and 2, the plate-shaped member 10 has a holding surface 11 (upper surface) that holds a semiconductor wafer W, and a lower surface 12 provided on the opposite side to the holding surface 11 in the thickness direction (i.e., the Z-axis direction) of the plate-shaped member 10. In this embodiment, the upper portion 10a has the holding surface 11, and the semiconductor wafer W is held on the holding surface 11. Note that the holding surface 11 is an example of a "first surface" in the present disclosure, and the lower surface 12 is an example of a "second surface" in the present disclosure.

[0025] Here, the diameter of the plate-shaped member 10 is larger at the lower portion 10b than at the upper portion 10a, and the upper portion 10a has a diameter of, for example, about 150 mm to 300 mm, while the lower portion 10b has a diameter of, for example, about 180 mm to 400 mm. The thickness of the plate-shaped member 10 is, for example, about 2 mm to 6 mm. The thermal conductivity of the plate-shaped member 10 is preferably within a range of 10 W / mK to 50 W / mK (more preferably, 18 W / mK to 30 W / mK).

[0026] 2, the plate-shaped member 10 has therein a gas passage 40. The gas passage 40 is a passage for supplying an inert gas (e.g., He gas) to the holding surface 11. The gas passage 40 has a plurality of gas holes 42 extending in the Z-axis direction and opening on the holding surface 11, a gas tunnel 44 extending in the XY plane direction and connecting the gas holes 42 together, and a gas introduction passage 46 opening on the lower surface 12, extending in the Z-axis direction, and connecting to the gas tunnel 44.

[0027] A plurality of gas holes 42 are provided, and are arranged, for example, in a circumferential shape (for each circular path described later) at equal intervals when viewed in the Z-axis direction. A gas tunnel 44 extending in the XY plane direction (within the XY plane) is formed so as to connect each gas hole 42. As shown in FIG. 3, this gas tunnel 44 includes circular paths 44a, 44b, and 44c, and a plurality of connecting paths 44d, 44e, and 44f connecting these circular paths. Each connecting path 44d, 44e, and 44f is a linear passage extending in the radial direction. The connecting path 44d connects the circular path 44a and the circular path 44b, and the connecting path 44e connects the circular path 44b and the circular path 44c. The connecting path 44f is arranged to pass through the center of the circular path 44c, and is connected to the circular path 44c at a symmetrical position on the circular path 44c.

[0028] With the gas passage 40 configured as described above, the inert gas supplied from the gas inlet path 46 to the gas tunnel 44 is supplied to the minute space between the semiconductor wafer W and the holding surface 11 through the multiple gas holes 42. The gas passage 40 only needs to be positioned so as not to interfere with other components provided inside the plate-like member 10, and its position, shape, and the like are not limited to the above example and can be changed as appropriate.

[0029] 2, the plate-like member 10 is provided therein with a heater electrode 60. As shown in FIG. 4, the heater electrode 60 has a plurality of arcuate portions 62 and a folded portion 64 connecting adjacent arcuate portions in the radial direction when viewed in the Z-axis direction. The heater electrode 60 has a shape that can be drawn in one stroke (when viewed in the Z-axis direction) by folding back a single heater line at multiple points. The heater electrode 60 is made of a conductive material (e.g., tungsten, molybdenum, etc.) and generates heat when power is supplied from an external power source. This makes it possible to heat the semiconductor wafer W held on the holding surface 11.

[0030] The arc portion 62 is composed of a plurality of arc-shaped heater lines having different diameters, and in this embodiment, there are a substantially circular portion and a semicircular portion. The folded portions 64 are formed to extend linearly in the radial direction, and are arranged in pairs so as to be adjacent and opposed to each other in the circumferential direction. Both ends of each of the pair of folded portions 64 are connected to the respective ends of the adjacent arc portion 62 in the radial direction.

[0031] As a result, in the heater electrode 60, a bent portion 66 is formed in the vicinity of the folded portion 64, in which the heater line is bent (bent) at a substantially right angle to form a U-shape. And, since the folded portions 64 are arranged in a pair to face each other, the bent portions 66 are similarly arranged to face each other. Note that the "facing arrangement" in this disclosure does not only include a case where the pair of folded portions 64, 64 are arranged to face each other in their entirety as in this embodiment, but also a case where the pair of folded portions 64, 64 are arranged to face each other in part (such as a case where they are arranged with a radial shift or where the folded portions have different lengths).

[0032] As shown in FIG. 5, most of the heater electrode 60 is disposed on both sides of the gas tunnel 44 along the gas tunnel 44 so as not to overlap with the gas tunnel 44 when viewed in the Z-axis direction. That is, most of the heater electrode 60 is disposed so as to sandwich the gas tunnel 44. Specifically, the arc portions 62a and 62b are disposed on both radial sides of the circular passage 44a, the arc portions 62c and 62d are disposed on both radial sides of the circular passage 44b, and the arc portions 62e and 62f are disposed on both radial sides of the circular passage 44c. Note that one of the adjacent arc portions 62a and 62b, the arc portions 62e and 62f, and the arc portions 62e and 62f is an example of a "first heater line" of the present disclosure, and the other is an example of a "second heater line" of the present disclosure.

[0033] Also, a pair of turn-back portions 64a, 64a are arranged on both circumferential sides of the connecting path 44d, a pair of turn-back portions 64b, 64b are arranged on both circumferential sides of the connecting path 44e, and a pair of turn-back portions 64c, 64c and 64d, 64d are arranged on both circumferential sides of the connecting path 44f. Furthermore, a pair of turn-back portions 64g, 64g are arranged on both circumferential sides of the end of the connecting path 44d, a pair of turn-back portions 64f, 64f are arranged on both circumferential sides of the connecting portion between the connecting path 44d and the connecting path 44e, and a pair of turn-back portions 64e, 64e are arranged on both circumferential sides of the connecting portion between the connecting path 44e and the connecting path 44f. Note that one of the pair of turn-back portions 64a to 64g is an example of a "first heater line" of the present disclosure, and the other is an example of a "second heater line" of the present disclosure.

[0034] Here, the positional relationship between the gas tunnel 44 and the heater electrode 60 as viewed in the Z-axis direction will be described with reference to Fig. 6. In a portion where the heater electrodes 60 are arranged so as to sandwich the gas tunnel 44, the gas tunnel 44 is located at the center of the adjacent turn-back portions 64 or arc portions 62. Specifically, as shown in Fig. 6, the intervals C1, C2 between the connecting path 44d and the turn-back portions 64a, 64a are equal (C1 = C2), and the intervals D1, D2 between the circular path 44b and the arc portions 62b, 62c are equal (D1 = D2). This arrangement relationship is also the same for other connecting paths and turn-back portions and circular paths and arc portions.

[0035] Then, in the bent portions 66 arranged opposite to each other, the distance A between the opposite (circumferentially adjacent) folded-back portions 64, 64 is set to be smaller than the longer of the distances B1, B2 of the opposite straight portions of the folded-back portions 64, 64. In the present embodiment, since the distances B1, B2 of the straight portions of the opposite folded-back portions 64, 64 are the same, A > B1 (= B2). Note that the lengths B1, B2 of the straight portions of the folded-back portions 64, 64 are the distances between the center lines of the arc portions 62 adjacent in the radial direction.

[0036] Here, the distances B1, B2 of the straight portions of the opposite folded-back portions 64, 64 are generally set to be the same, but in order to avoid interference with other components or for other reasons, the distance of one straight portion may be shorter. In such a case, for example, if the distance B1 of the straight portions of the opposite folded-back portions 64, 64 is shorter than the distance B2 (B1 < B2), the relationship with the distance A between the opposite (circumferentially adjacent) folded-back portions 64, 64 is A < B2.

[0037] As shown in FIG. 1, the base member 20 is disposed on the side opposite to the holding surface 11 side with respect to the plate-like member 10. This base member 20 is formed, for example, in a columnar shape. Further, the base member 20 is formed of, for example, a metal (for example, aluminum, an aluminum alloy, etc.), but may be other than a metal.

[0038] Then, as shown in FIGS. 1 and 2, the base member 20 includes an upper surface 21 and a lower surface 22 provided on the side opposite to 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 plate-like member 10 via the bonding layer 30. Further, a through hole 26 penetrating in the thickness direction (Z-axis direction, vertical direction in FIG. 2) between the upper surface 21 and the lower surface 22 is formed in the base member 20, and this through hole 26 communicates with the gas introduction path 46.

[0039] The diameter of the base member 20 is, for example, about 180 mm to 400 mm. The thickness (dimension in the Z-axis direction) of the base member 20 is, for example, about 20 mm to 50 mm. The thermal conductivity of the base member 20 (assumed to be aluminum) is desirably within the range of 160 mm to 250 W / mK (preferably, about 230 W / mK).

[0040] Further, a coolant flow passage 23 for flowing a coolant (e.g., a fluorine-based inert liquid, water, etc.) is formed in the base member 20. By flowing a coolant in this coolant flow passage 23, the base member 20 is cooled, and the plate-like member 10 is cooled via the bonding layer 30. This allows the semiconductor wafer W held on the holding surface 11 to be cooled.

[0041] As shown in FIG. 1 and FIG. 2, the bonding layer 30 is disposed between the lower surface 12 of the plate-shaped member 10 and the upper surface 21 of the base member 20, and bonds the plate-shaped member 10 and the base member 20 in a heat-transferable manner. The bonding layer 30 is made of a resin adhesive such as a silicone resin, an acrylic resin, or an epoxy resin. The thickness (dimension in the Z-axis direction) of the bonding layer 30 is, for example, about 0.1 mm 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 within a range of 0.1 W / mK to 2.0 W / mK (preferably, 0.5 W / mK to 1.5 W / mK). The bonding layer 30 has a through hole formed therein for communicating the through hole 26 with the gas introduction passage 46.

[0042] Here, in the electrostatic chuck 1, since the gas passage 40 acts as a heat insulating layer, there is a risk that heat transfer will be hindered and deteriorated in the portion where the gas passage 40 is formed. That is, in the holding surface 11, the region directly above the gas passage 40 is likely to have a higher temperature than other regions, while the region directly above the portion where the heater electrode 60 is not arranged is likely to have a lower temperature than the region directly above the portion where the heater electrode 60 is arranged (because it is likely to become a temperature singularity), and therefore, there is a risk that the thermal uniformity in the holding surface 11 will deteriorate.

[0043] Therefore, in the electrostatic chuck 1 of this embodiment, adjacent arc portions 62, 62 and a pair of folded portions 64, 64 are arranged on both sides of the gas passage 40 along the gas passage 40 so as not to overlap with the gas passage 40 when viewed in the Z-axis direction; in other words, adjacent arc portions 62, 62 and a pair of folded portions 64a-64g are arranged on either side of the gas tunnel 44.

[0044] Therefore, it is possible to reduce the temperature difference between the region immediately above the portion of the holding surface 11 where the heater electrode 60 is not disposed and the region immediately above the portion where the heater electrode 60 is disposed. Therefore, it is possible to improve the temperature uniformity on the holding surface 11.

[0045] In the electrostatic chuck 1, when viewed in the Z-axis direction, the heater electrode 60 is arranged so that the distances C1, C2 between the connecting paths 44d-44f and the folded-back portions 64, 64 are equal (C1=C2), and the distances D1, D2 between the circular paths 44a-44c and the arc portion 62 are also equal (D1=D2).

[0046] This makes it possible to make uniform the temperature distribution between the folded-back portions 64, 64 arranged opposite to each other in the circumferential direction and the temperature distribution between the adjacent arc portions 62, 62 in the radial direction. Therefore, the temperature uniformity on the holding surface 11 can be further improved.

[0047] In addition, in the electrostatic chuck 1, in the region where the bent portions 66, 66 are arranged opposite each other, which is likely to have a lower temperature than other regions, the heater electrodes 60 (folded portions 64a to 64f) are arranged on both sides of the gas tunnel 44 along the gas tunnel 44 so as not to overlap with the gas tunnel 44 (connecting paths 44d to 44f) when viewed in the Z-axis direction.

[0048] This can reduce the temperature difference between the region where the bent portions 66, 66 are arranged opposite to each other and other regions. Therefore, the occurrence of temperature singularities on the holding surface 11 can be suppressed, and the temperature uniformity on the holding surface 11 can be further improved.

[0049] Furthermore, in the electrostatic chuck 1, in the bent portions 66 disposed opposite to each other, the distance A between the folded portions 64, 64 is set to be smaller than the distances B1, B2 between the facing straight portions of the folded portions 64, 64 (A <B1=B2)。

[0050] This makes it possible to efficiently heat the portion directly above the gas tunnel 44, which is likely to become a temperature singularity on the holding surface 11. Therefore, since the temperature difference between the portion directly above the gas tunnel 44 and other areas on the holding surface 11 can be made smaller, the thermal uniformity on the holding surface 11 can be reliably improved.

[0051] By arranging the heater electrode 60 in this manner, in the region where the bent portions 66, 66 are arranged opposite each other, the temperature difference between the region and other regions in a conventional electrostatic chuck was 2°C or more, but in the electrostatic chuck 1 of this embodiment, the temperature difference can be kept to less than 1°C.

[0052] As described above, according to the electrostatic chuck 1 of the present embodiment, the heater electrodes 60 are disposed so as to sandwich the gas tunnel 44 when viewed in the Z-axis direction, and therefore, it is possible to suppress a temperature increase in the region immediately above the gas tunnel 44 on the holding surface 11, while suppressing a temperature decrease in the region immediately above the portion where the heater electrode 60 is not disposed. This makes it possible to reduce the temperature difference between the region immediately above the portion where the heater electrode 60 is not disposed on the holding surface 11 and the region immediately above the portion where the heater electrode 60 is disposed. Therefore, even if the gas tunnel 44 is provided, it is possible to improve the thermal uniformity on the holding surface 11.

[0053] It should be noted that the above embodiment is merely an example, does not limit the present disclosure in any way, and various improvements and modifications are possible without departing from the spirit of the present disclosure. For example, in the above embodiment, the bent portion is exemplified as a U-shaped portion formed by adjacent arc portions and folded portions, but the bent portion is not limited to this shape, and may be shaped to straddle a gas tunnel, for example, as shown in FIG. 7.

[0054] In addition, the above embodiment illustrates a case where the heater electrode 60 is arranged on the holding surface 11 side of the gas tunnel 44, but the present disclosure can also be applied to a case where the heater electrode 60 is arranged on the lower surface 12 side of the gas tunnel 44.

[0055] In addition, in the above embodiment, a heater electrode that is not divided into multiple parts (single-zone type) is exemplified, but the heater electrode may be divided into multiple parts and the temperature of each zone may be controlled (multi-zone type), and the present disclosure can also be applied to a holding member equipped with a multi-zone type heater electrode. [Explanation of symbols]

[0056] 1. Electrostatic chuck 10 Plate-shaped member 11 Holding surface 12 Bottom side 20 Base material 30 Bonding layer 40 Gas passage 44 Gas Tunnel 44a~44c Circular Route 44d~44f Connecting road 60 Heater electrode 62 Arc section 62a~62f Arc section 64 Turning section 64a~64g folded part 66 Bend A Distance between folds B1, B2 Distance of straight part of turn back C1, C2 Distance between turnaround and connecting road D1, D2 Distance between the arc and the circular path W Semiconductor wafer

Claims

1. A holding member for holding an object on the first surface, the holding member comprising: a first surface; a second surface provided on an opposite side to the first surface in a thickness direction; a heater electrode disposed between the first surface and the second surface; and a gas passage for supplying an inert gas onto the first surface from the second surface side, The gas passage includes a gas tunnel extending in a planar direction, The heater electrode has a first heater line and a second heater line that are arranged on both sides of the gas tunnel along the gas tunnel so as not to overlap the gas tunnel when viewed in the thickness direction. A holding member characterized by:

2. 2. The holding member according to claim 1, The first heater line and the second heater line are heater lines in a portion of the heater electrode where bent portions are arranged opposite to each other. A holding member characterized by:

3. The holding member according to claim 1 or 2, When viewed in the thickness direction, the distance between the first heater line and the gas tunnel is the same as the distance between the second heater line and the gas tunnel. A holding member characterized by:

4. The holding member according to claim 2, The distance between the first heater line and the second heater line that are disposed opposite to each other is shorter than the length of the heater line that has a longer opposing straight portion of the first heater line or the second heater line. A holding member characterized by:

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