Retaining member

Abstract

The holding member efficiently promotes heat dissipation from the object it holds, eliminating temperature singularities and bringing the temperature distribution closer to uniformity. [Solution] The holding member for holding an object has a holding surface for holding the object and comprises a holding portion with a substantially circular outer circumference, and a cooling portion arranged on the opposite side of the holding surface from the holding portion and having a flow path formed therein. When the holding member is viewed from the holding surface side, the holding portion has an alignment portion on a part of its outer circumference that is formed radially inward from the virtual circle formed by the outer circumference, and the flow path has a folded portion in the vicinity of the alignment portion in which the direction in which the flow path extends is folded back.

Description

Technical Field

[0001] The present invention relates to a holding member.

Background Art

[0002] Holding members such as electrostatic chucks for holding objects such as wafers are known (see, for example, Patent Documents 1 and 2). In the holding members described in Patent Documents 1 and 2, in order to suppress the temperature rise due to processing of the object to be held, a flow path through which a refrigerant flows is formed inside.

[0003] In the holding member described in Patent Document 1, an oriflame portion is formed in a part of the inner circumference of the circular outer circumference that holds the object, and a part of the oriflame portion is cut out radially inward. When the holding member is viewed from the holding surface side for holding the wafer, a part of the oriflame portion and the flow path overlap. In the electrostatic chuck described in Patent Document 2, when viewed from the holding surface side, the flow path is formed in a spiral shape. The flow path located on the radially outer side meanders so as to project radially outward and radially inward along the circumferential direction.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the semiconductor manufacturing equipment field, particularly in memory manufacturing (especially 3D NAND flash memory), wafers are processed with numerous fine, deep holes uniformly. High aspect ratio etching processes generate very large amounts of heat in the wafer. Fixing components such as electrostatic chucks are required not only to hold the wafer in place but also to efficiently dissipate this enormous heat and precisely and uniformly control the temperature of the entire wafer.

[0006] The orientation flat portion of the holding member described in Patent Document 1 is a part that has been cut out. As a result, the area of ​​contact with the object is smaller near the orientation flat portion compared to the area where the orientation flat portion is not formed. Consequently, cooling by the refrigerant flowing through the channel in the holding member becomes insufficient, and the temperature near the orientation flat portion becomes higher than other parts, potentially creating a hot spot. The electrostatic chuck described in Patent Document 2 does not have a cutout like the orientation flat portion and has a circular outer circumference. Therefore, the electrostatic chuck described in Patent Document 2 is less likely to generate hot spots like the holding member described in Patent Document 1. There is room for improvement in suppressing the generation of hot spots compared to the technology described in Patent Document 1.

[0007] The present invention has been made to solve at least some of the above-mentioned problems, and aims to efficiently promote heat dissipation of the object held by the holding member, eliminate temperature singularities, and bring the temperature distribution closer to uniformity. [Means for solving the problem]

[0008] The present invention was made to solve at least some of the problems described above, and can be realized in the following forms. A holding member for holding an object, comprising: a holding portion having a holding surface for holding the object and a substantially circular outer circumference; and a cooling portion positioned on the opposite side of the holding portion from the holding surface side and having a flow path formed therein, wherein when the holding member is viewed from the holding surface side, the holding portion has an alignment portion formed radially inward from a virtual circle formed by the outer circumference on a part of the outer circumference, the flow path has a folded portion in which the direction in which the flow path extends is folded back, and the folded portion is positioned along the circumferential direction of the virtual circle within a region 15° away from each end of the alignment portion, and along the radial direction of the virtual circle within a region ±0.1L from the position of the alignment portion which serves as the reference for distance L, using the distance L between the center of the virtual circle and the alignment portion. In addition, the present invention can also be realized in the following forms.

[0009] (1) According to one embodiment of the present invention, a holding member for holding an object is provided. The holding member comprises a holding portion having a holding surface for holding the object and a substantially circular outer circumference, and a cooling portion arranged on the opposite side of the holding portion from the holding surface side and having a flow path formed therein, wherein when the holding member is viewed from the holding surface side, the holding portion has an alignment portion formed radially inward from the virtual circle formed by the outer circumference on a part of the outer circumference, and the flow path has a folded portion in the vicinity of the alignment portion in which the direction in which the flow path extends is folded back.

[0010] In this configuration, the alignment portion of the holding portion is formed radially inward from the virtual circle formed by the outer circumference. Therefore, the area of ​​the alignment portion projected onto the holding surface that holds the object is smaller than other parts, making the alignment portion prone to becoming a hot spot. In contrast, in this configuration, the folded portion is positioned near the alignment portion when viewed from the holding surface, so that the refrigerant flowing through the folded portion cools the alignment portion more than other parts. As a result, heat dissipation from the object held on the holding surface is efficiently promoted, and the temperature distribution of the object approaches uniformity without the occurrence of temperature singularities.

[0011] (2) According to another embodiment of the present invention, a holding member for holding an object is provided. The holding member comprises a holding portion having a holding surface for holding the object and a substantially circular outer circumference, and a cooling portion positioned on the opposite side of the holding portion from the holding surface side, with a flow path formed inside through which a refrigerant flows, wherein when the holding member is viewed from the holding surface side, the holding portion has a positioning portion formed radially inward from a virtual circle formed by the outer circumference on a part of the outer circumference, and the flow path may have an inner flow path through which the refrigerant flows along the circumferential direction of the holding member, an outer flow path located radially outward from the inner flow path, through which the refrigerant that has flowed in the inner flow path flows along the circumferential direction, and a folded flow path connecting the inner flow path and the outer flow path such that the direction of the refrigerant flowing in the inner flow path is reversed from the direction of the refrigerant flowing in the outer flow path, and a part of which overlaps the positioning portion. In this configuration, the refrigerant flowing through the inner channel passes through the return section and flows into the outer channel. As the refrigerant flows from the inner channel to the outer channel, turbulence of the refrigerant is easily generated near the return section. The generated turbulent refrigerant efficiently promotes heat removal from the object.

[0012] (3) According to another embodiment of the present invention, a holding member for holding an object is provided. The holding member comprises a holding portion having a holding surface for holding the object and a substantially circular outer circumference, and a cooling portion disposed on the opposite side of the holding portion from the holding surface side and having a flow path formed therein, wherein when the holding member is viewed from the holding surface side, the holding portion has an alignment portion formed radially inward from a virtual circle formed by the outer circumference on a part of the outer circumference, and the flow path may have an uneven flow path that protrudes alternately radially outward and radially inward along the virtual circle, with a part of it overlapping the alignment portion. In this configuration, when viewed from the holding surface, the alignment portion, which is prone to becoming a hot spot, overlaps with a portion of the uneven flow channels that alternately protrude radially outward and radially inward. Because turbulence is easily generated in the refrigerant flowing through the uneven flow channels, the alignment portion that overlaps with the uneven flow channels is cooled more than other parts by the turbulent refrigerant. As a result, heat dissipation from the object held on the holding surface is efficiently promoted, and the temperature distribution of the object approaches uniformity without the occurrence of temperature singularities.

[0013] (4) In the holding member of the above form, when the holding member is viewed from the holding surface, the uneven flow channel may partially overlap the virtual circle. In this configuration, a portion of the uneven channel overlaps not only the alignment portion but also a virtual circle formed by a portion of the outer circumference of the holding portion. Therefore, the portion of the holding member projected onto the virtual circle, where the temperature tends to rise during processing of the object held on the holding surface, has its heat efficiently dissipated by the turbulent coolant flow generated by the uneven channel.

[0014] (5) In the holding member of the above form, when the uneven flow channel and the virtual circle are viewed from the holding surface of the holding member, there may be 11 or more combinations of overlapping and non-overlapping portions along the circumferential direction. In this configuration, there are more than 11 overlapping areas between the uneven flow channels and the virtual circle. Therefore, the heat dissipation is efficiently promoted in the areas of the holding surface onto which the virtual circle is projected, where the temperature tends to rise, by the turbulent coolant flow generated by the uneven flow channels.

[0015] (6) In the holding member of the above form, when the holding member is viewed from the holding surface, the flow path may have an uneven flow path that protrudes alternately radially outward and radially inward along the circumferential direction of the virtual circle, with a portion of it overlapping the virtual circle. In this configuration, a portion of the uneven channel overlaps not only the alignment portion but also a virtual circle formed by a portion of the outer circumference of the holding portion. Therefore, the portion of the holding member projected onto the virtual circle, where the temperature tends to rise during processing of the object held on the holding surface, has its heat efficiently dissipated by the turbulent coolant flow generated by the uneven channel.

[0016] (7) In the holding member of the above form, when the uneven flow channel and the virtual circle are viewed from the holding surface of the holding member, there may be 11 or more combinations of overlapping and non-overlapping portions along the circumferential direction. In this configuration, there are more than 11 overlapping areas between the uneven flow channels and the virtual circle. Therefore, the heat dissipation is efficiently promoted in the areas of the holding surface onto which the virtual circle is projected, where the temperature tends to rise, by the turbulent coolant flow generated by the uneven flow channels.

[0017] Furthermore, the present invention can be realized in various forms, for example, as a holding member, an electrostatic chuck, a holding device, a semiconductor manufacturing apparatus, a holding method, and a system comprising these. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic perspective view of an electrostatic chuck as one embodiment of the present invention. [Figure 2] It is a schematic cross-sectional view of an electrostatic chuck. [Figure 3] It is a schematic top view of an electrostatic chuck. [Figure 4] It is a schematic top view in which the vicinity of the orifice portion is enlarged. [Figure 5] It is a schematic top view in which the region β in FIG. 3 is enlarged. [Figure 6] It is an explanatory diagram of the temperature distribution of the ceramic member of the present embodiment. [Figure 7] It is an explanatory diagram of the temperature distribution of the ceramic member of the comparative example. [Figure 8] It is an explanatory diagram of the turbulent viscosity ratio of the refrigerant flowing in the refrigerant flow path of the present embodiment. [Figure 9] It is an explanatory diagram of the turbulent viscosity ratio of the refrigerant flowing in the refrigerant flow path of the comparative example. [Figure 10] It is an explanatory diagram of the turbulent viscosity ratio when the refrigerant flows from the inner peripheral side to the outer peripheral side in the refrigerant flow path. [Figure 11] It is an explanatory diagram of the turbulent viscosity ratio when the refrigerant flows from the outer peripheral side to the inner peripheral side in the refrigerant flow path.

Mode for Carrying Out the Invention

[0019] <Embodiment> FIG. 1 is a schematic perspective view of an electrostatic chuck (holding device) 1 as an embodiment of the present invention. In FIG. 1, an electrostatic chuck 1 and a wafer (object) W held by the electrostatic chuck 1 are shown. The electrostatic chuck 1 is a device that adsorbs and holds a wafer W as a processing target by electrostatic attraction. The electrostatic chuck 1 is used, for example, in a vacuum chamber of a semiconductor manufacturing apparatus. The wafer W has, for example, an outer periphery formed in a circular or substantially circular shape. In FIG. 1, the wafer W is represented by a broken line.

[0020] The electrostatic chuck 1 comprises a ceramic member (holding part) 10 made of a material mainly composed of alumina (Al2O3), a base member (cooling part) 20 made of a metal such as aluminum or an aluminum alloy, and a bonding layer 30 that joins the ceramic member 10 and the base member 20. As shown in Figure 1, the ceramic member 10, the bonding layer 30, and the base member 20 are stacked in this order. The Cartesian coordinate system CS shown in Figure 1 consists of three axes: the Z axis parallel to the stacking direction, and the X and Y axes which are orthogonal to the Z axis. The Cartesian coordinate system CS shown in Figure 1 corresponds to the Cartesian coordinate system CS shown in Figure 2. Hereafter, for convenience, the positive Z-axis side will also be referred to as the vertically upward side, and the negative Z-axis side will also be referred to as the vertically downward side.

[0021] As shown in Figure 1, the ceramic member 10 is a disc-shaped member. Specifically, the ceramic member 10 comprises an upper disc-shaped portion 10a and a lower disc-shaped portion 10b with a larger diameter than the upper disc-shaped portion 10a. The upper disc 10a and the lower disc 10b are stacked on top of each other such that the central axis of the upper disc 10a and the central axis of the lower disc 10b overlap on the same central axis OL1.

[0022] The diameter of the upper section 10a is, for example, about 150 to 300 mm. The diameter of the lower section 10b is, for example, about 180 to 400 mm. The combined thickness of the ceramic member 10, consisting of the upper section 10a and the lower section 10b, is, for example, about 2 to 6 mm.

[0023] Various ceramics can be used to form the upper section 10a and the lower section 10b, but from the viewpoint of strength, wear resistance, plasma resistance, etc., it is preferable to use other ceramics besides alumina, such as aluminum nitride (AlN) or silicon carbide (SiC). Here, "main component" refers to the component that is present in the largest proportion.

[0024] The base member 20 is positioned vertically below the ceramic member 10 via a bonding layer 30. As shown in Figure 1, the base member 20 is formed in a substantially cylindrical shape, for example. In this embodiment, the base member 20 is formed of a sintered body mainly composed of silicon carbide. The base member 20 may also be formed of a composite of metal and ceramics such as aluminum (Al), titanium (Ti), molybdenum (Mo), tungsten (W), alloys thereof, SUS, Al-SiC, or a material mainly composed of ceramics such as aluminum nitride or alumina.

[0025] The diameter of the base member 20 is, for example, about 180 to 400 mm. The thickness of the base member 20 along the lamination direction is, for example, about 20 to 50 mm.

[0026] The bonding layer 30 that joins the ceramic member 10 and the base member 20 may be, but is not limited to, metal bonding, resin bonding, or bonding with inorganic materials.

[0027] Figure 2 is a schematic cross-sectional view of the electrostatic chuck 1. As shown in Figure 2, the upper portion 10a of the ceramic member 10 is equipped with a disc-shaped chuck electrode 15 that generates an electrostatic attraction inside. The chuck electrode 15 generates an electrostatic attraction when a voltage is applied to it by connecting it to a power source (not shown) via a conductor (not shown) that penetrates the base member 20 and the bonding layer 30. The wafer W is attracted and held to the upper surface (holding surface) 11 on the vertically upward side of the upper portion 10a by the electrostatic attraction.

[0028] As shown in Figure 2, a refrigerant channel (channel) 23 is formed inside the base member 20 through which a refrigerant (for example, a fluorine-based inert liquid or water) flows. In other words, in the electrostatic chuck 1, the refrigerant channel 23 is located on the opposite side of the upper surface 11 of the upper stage 10a that holds the wafer W relative to the ceramic member 10.

[0029] Figure 3 is an explanatory diagram of the refrigerant flow path 23. Figure 3 shows a schematic top view of the electrostatic chuck 1. In Figure 3, the refrigerant flow path 23 formed in the base member 20 is shown by a dashed line. The refrigerant flow path 23 has a supply port 24 through which refrigerant is supplied and an outlet port 25 through which the supplied refrigerant is discharged. The cross-sectional area of ​​the refrigerant flow path 23 is the same in all parts except for the supply port 24 and the outlet port 25. The cross-sectional shape of the refrigerant flow path 23 in this embodiment is rectangular, as shown in Figure 2. As an example, the cross-sectional shape of the refrigerant flow path 23 is rectangular with sides of approximately 5.0 to 25.0 mm. As shown in Figure 3, the refrigerant flow path 23 has a substantially circular spiral (or helical) flow path shape centered on the central axis OL1 or near the central axis OL1 of the lower circular portion 10b. The wafer W held in the electrostatic chuck 1 is cooled by the refrigerant flowing through the refrigerant channel 23, and heat is transferred through the bonding layer 30 and the ceramic member 10.

[0030] As shown in Figure 3, the upper section 10a has a substantially circular shape in which an orientation flat section 12 is formed by linearly cutting out a portion of the arc on the negative Y-axis side. Figure 4 is an explanatory diagram of the orientation flat section 12. Figure 4 shows a schematic enlarged view of region α in Figure 3. As shown in Figure 4, the orientation flat section 12 is a portion cut radially inward with respect to the virtual circle VC when viewed from the stacking direction, which is the upper surface 11 side of the ceramic member 10. The virtual circle VC is the circular outer circumference of the upper section 10a other than the orientation flat section 12 when viewed from the stacking direction, and is a circle centered on the central axis OL1. The orientation flat section 12 is linearly cut radially inward with respect to the virtual circle VC. The length of the cut-out linear section is, for example, about 25.0 to 45.0 mm. The orientation flat section 12 functions as a circumferential alignment section of the wafer W by being aligned with a marking position on the wafer W.

[0031] As shown in Figure 3, the refrigerant flow path 23 has an outermost flow path (outer flow path) 23a located on the outermost periphery, an inlet side flow path (inner flow path) 23b located radially inward of the outermost flow path 23a and connected to the supply port 24, a return section 23c connecting the outermost flow path 23a and the inlet side flow path 23b, and an outlet side flow path 23d located radially inward of the inlet side flow path 23b.

[0032] As shown in Figure 3, the outermost channel 23a and the inlet channel 23b extend circumferentially. The refrigerant supplied from the supply port 24 flows through the inlet channel 23b, passes through the return section 23c, and then flows through the outermost channel 23a. After that, it flows through the outlet channel 23d and is discharged from the outlet 25.

[0033] The outermost channel 23a has multiple protrusions (protrusions and indentations) 23aC that alternately protrude radially outward and radially inward along the circumferential direction. Figure 5 is an explanatory diagram of the protrusions and indentations 23aC. Figure 5 shows a schematic enlarged view of region β in Figure 3. As shown in Figure 5, in this embodiment, when viewed from the stacking direction, a part of the protrusions and indentations 23aC overlaps with the virtual circle VC. The virtual circle VC shown in Figure 5 is identical to the circular outer shape of the upper surface 11 of the upper section 10a. Also, as shown in Figure 3, in this embodiment, when viewed from the stacking direction, the outermost channel 23a has 11 or more protrusions and indentations 23aC that overlap with the virtual circle VC. In other words, the outermost channel 23a has 11 or more protrusions and indentations 23aC that straddle the virtual circle VC. If there are 10 or fewer uneven areas 23aC, the frequency of unevenness is low, and conversely, these uneven areas 23aC may become temperature singularities.

[0034] The folded portion 23c shown in Figure 3 is positioned near the orientation flat portion 12. Here, "nearby" refers to the region where, in the circumferential direction, the angle between the orientation flat portion 12 and the intersection point VC_A of the virtual circle VC and the central axis OL1 is 15° or less, with respect to the straight line connecting the central axis OL1 and the central axis OL1, and the intersection point VC_B of the central axis OL1 on the opposite side of the orientation flat portion 12. Furthermore, the "nearby" of the orientation flat portion 12 refers to the region within ±0.1 × L from the orientation flat portion 12 when the distance between the center of the virtual circle VC and the orientation flat portion 12 is L (Figure 3) in the radial direction. More preferably, in the radial direction, it refers to the region within ±0.05 × L from the orientation flat portion 12. By cooling from the vicinity of the orientation flat portion 12, it is possible to reduce the heat input to the orientation flat portion 12 from the outside and cool the orientation flat portion 12 more efficiently.

[0035] Furthermore, as shown in Figure 3, the folded portion 23c connects to the outermost channel 23a in such a way that the refrigerant flowing counterclockwise through the inlet channel 23b is redirected clockwise. In other words, when viewed from the stacking direction, the folded portion 23c of this embodiment is formed to reverse the direction of refrigerant flow. For this reason, although the inlet channel 23b and the outermost channel 23a extend roughly parallel to each other along the circumferential direction, the direction of refrigerant flow is opposite to that of the inlet channel 23b. And, as shown in Figures 3 and 4, some of the multiple uneven portions 23aC of the outermost channel 23a overlap with the orientation flat portion 12.

[0036] Figure 6 is an explanatory diagram of the temperature distribution of wafer W cooled by the refrigerant flowing through the refrigerant channel 23. Figure 6 shows the wafer W and the refrigerant channel 23 as viewed from the stacking direction. The temperature distribution is represented by the coarseness of the hatching, with finer hatching indicating higher temperatures. In Figure 6, two regions RG01 and RG02, which are hotter than other parts of wafer W, are hatched. As shown in Figure 6, region RG01 is a part of the outer periphery of wafer W. Region RG02 is a central region of wafer W, including the center. The temperatures in regions RG01 and RG02 were approximately the same.

[0037] Figure 7 is an explanatory diagram of the temperature distribution of a wafer W cooled by a refrigerant flowing through a refrigerant channel 23x of the comparative example. In the comparative example refrigerant channel 23x shown in Figure 7, unlike the refrigerant channel 23 shown in Figures 3 and 6, the outermost channel 23a does not have an uneven portion 23aC formed thereon. In Figure 7, as in Figure 6, the temperature distribution is represented by the coarseness of the hatching. In Figure 7, hatching is applied to three regions RG11 to RG13 on the wafer W that are hotter than other parts. As shown in Figure 7, region RG11 is a part of the outer periphery of the wafer W. Region RG12 is a central region including the center of the wafer W. Region RG13 is a region that extends radially from region RG12 to region RG11.

[0038] The temperature of region RG13 was similar to that of regions RG01 and RG02 shown in Figure 6. On the other hand, the temperatures of regions RG11 and RG12 in Figure 7 were higher than those of regions RG01, RG02, and RG13. A comparison of the temperature distribution in Figure 6 and Figure 7 shows that, as shown in Figure 6, the formation of the uneven portion 23aC in the outermost channel 23a suppresses the temperature rise on the radially outer side of the wafer W. As a result, as shown in Figures 3 and 4, the temperature rise of the wafer W near the orientation flat portion 12, where the contact area with the wafer W is small and the temperature tends to rise, is suppressed.

[0039] Figures 8 and 9 are explanatory diagrams of the turbulent viscosity ratio (TVR) of the refrigerant flowing through refrigerant channels 23 and 23x. In Figure 8, the turbulent viscosity ratio of the refrigerant flowing through refrigerant channel 23 in this embodiment is represented by hatching. In Figure 9, the turbulent viscosity ratio of the refrigerant flowing through refrigerant channel 23x in a comparative example is represented by hatching. In Figures 8 and 9, the finer the hatching, the higher the turbulent viscosity ratio, that is, the greater the effect of turbulence.

[0040] In Figure 8, four regions RG21 to RG24, which have a higher turbulent viscosity ratio than other regions, are hatched. As shown in Figure 6, region RG21 is a part of the outermost channel 23a near the return section 23c. Region RG22 is the combined area of ​​the outermost channel 23a excluding region RG21 and a part of the outlet channel 23d connected to the downstream side of the outermost channel 23a. Region RG23 is the outermost region of the bent portion of the return section 23c. Region RG24 is a part of the inlet channel 23b near the center. The turbulent viscosity ratios of regions RG22 to RG24 are similar. On the other hand, the turbulent viscosity ratio of region RG21 was higher than that of regions RG22 to RG24.

[0041] In Figure 9, three regions RG31 to RG33, which are hotter than other parts, are hatched. As shown in Figure 9, region RG31 is a part of the folded portion 23cx. Region RG32 is a part of the inner circumference of the outermost channel 23ax near the folded portion 23cx. Region RG33 is a part of the central part of the outlet channel 24bx. The turbulent viscosity ratios of regions RG31 to RG33 are similar, and are similar to those of regions RG22 and RG23 in Figure 8.

[0042] A comparison of the turbulent viscosity ratio in Figure 8 and Figure 9 shows that, as shown in Figure 8, the formation of irregularities 23aC in the outermost channel 23a increases the turbulent viscosity ratio of the outermost channel 23a, and the turbulent viscosity ratio in the region RG21 (Figure 8) near the folded portion 23c becomes particularly high. The increased turbulent viscosity ratio due to the multiple irregularities 23aC, that is, the increased influence of turbulence, is thought to have led to increased heat dissipation from the outer periphery of the wafer W, as shown in Figure 6.

[0043] Figures 10 and 11 are explanatory diagrams illustrating the cooling effect according to the direction of the refrigerant flowing through the refrigerant channel 23y. Figures 10 and 11 show the shape of the refrigerant channel 23y, which differs from the shape of the refrigerant channel 23 in the embodiment, when viewed from the stacking direction. As shown in Figure 10, the refrigerant channel 23y includes an outer peripheral channel 23ya located on the outer circumference side and having an arc shape, an inner peripheral channel 23yb located radially inward from the outer peripheral channel 23ya and having an arc shape, a folded portion 23yc located on the negative Y-axis side and connecting the outer peripheral channel 23ya and the inner peripheral channel 23yb, an outer peripheral inlet / outlet 23yd formed at one end of the outer peripheral channel 23ya, and an inner peripheral inlet / outlet 23ye formed at one end of the inner peripheral channel 23yb.

[0044] Using the refrigerant flow path 23y, the turbulent viscosity ratio was compared between two cases: one where refrigerant is supplied from the inner inlet / outlet 23ye connected to the inner flow path 23yb and discharged from the outer inlet / outlet 23yd connected to the outer flow path 23ya, and another where refrigerant is supplied from the outer inlet / outlet 23yd and discharged from the inner inlet / outlet 23ye. In other words, the turbulent viscosity ratio was compared between the case where the refrigerant flows from the inside to the outside within the refrigerant flow path 23y and the case where it flows from the outside to the inside. On the other hand, the turbulent viscosity ratio of the refrigerant formed within the refrigerant flow path 23y was different.

[0045] In Figures 10 and 11, the turbulent viscosity ratio of the refrigerant is represented by hatching, similar to Figures 8 and 9. Finer hatching indicates a higher turbulent viscosity ratio. Figure 10 shows the turbulent viscosity ratio of the refrigerant when it is supplied from the inner inlet / outlet 23ye and discharged from the outer inlet / outlet yd. On the other hand, Figure 11 shows the turbulent viscosity ratio of the refrigerant when it is supplied from the outer inlet / outlet yd and discharged from the inner inlet / outlet 23ye.

[0046] As shown in Figure 10, when the refrigerant flows from the inside to the outside within the refrigerant flow path 23y, the turbulent viscosity ratios were high in the three hatched regions RG41 to RG43. Region RG41 is a part of the radially inner region near the folded portion 23yc of the outer peripheral flow path 23ya. Region RG42 is a part of the outer peripheral flow path 23ya that surrounds region RG41. Region RG43 is the bent outer peripheral portion of the folded portion yc. The turbulent viscosity ratios of regions RG42 and RG43 are similar. On the other hand, the turbulent viscosity ratio of region RG41 was higher than that of regions RG42 and RG43.

[0047] As shown in Figure 11, when the refrigerant flows from the outside to the inside within the refrigerant flow path 23y, the turbulent viscosity ratios were high in the two hatched regions RG51 and RG52. Region RG51 is a part of the radially outer region near the return portion 23yc of the inner circumferential flow path 23yb. Region RG52 is a part of the inner circumferential flow path 23yb that surrounds region RG51. The turbulent viscosity ratio of region RG51 was higher than that of region RG51 and was about the same as that of region RG41 in Figure 10. The turbulent viscosity ratio of region RG52 was about the same as that of regions RG42 and RG43 in Figure 10.

[0048] The turbulent viscosity ratio results in Figures 10 and 11 show that turbulence is likely to occur in the folded portion 23yc when the refrigerant flows from the inside to the outside within the refrigerant flow path 23y. As a result, turbulence occurs in the folded portion 23c, promoting heat dissipation from the orientation flat portion 12. Also, as shown in Figures 6 and 7, the temperature of the wafer W tends to be higher on the radially outer side than on the radially inner side. As shown in Figure 10, turbulence is likely to occur in the radially outer flow path 23ya as the refrigerant flows from the inner circumferential flow path 23yb to the outer circumferential flow path 23ya. This cools the radially outer side of the wafer W, which tends to get hotter. As a result, the temperature gradient generated on the wafer W and the upper portion 10a is suppressed, and the temperature distribution becomes more uniform.

[0049] As described above, in the electrostatic chuck 1 of this embodiment, a refrigerant flow path 23 is formed within the base member 20, as shown in Figure 2. As shown in Figure 3, when viewed from the stacking direction, the refrigerant flow path 23 has an outermost flow path 23a, an inlet-side flow path 23b, and a folded portion 23c connecting the outermost flow path 23a and the inlet-side flow path 23b. The folded portion 23c folds the inlet-side flow path 23b in the direction that extends along the circumferential direction back to the outermost flow path 23a in the direction that extends along the circumferential direction. In addition, the upper part 10a of the ceramic member 10 has an orientation flat portion 12 that is linearly cut out radially inward from the virtual circle VC formed by the outer circumference of the upper part 10a. In this embodiment, since the orientation flat portion 12 is cut out radially inward from the virtual circle VC, when viewed from the stacking direction, the area of ​​the orientation flat portion 12 on the upper surface 11 of the upper part 10a is smaller than that of other parts, and the orientation flat portion 12 is prone to becoming a hot spot. In contrast, when viewed from the stacking direction, the folded portion 23c of the refrigerant flow path 23 is positioned near the orientation flat portion 12, so that the orientation flat portion 12 is cooled more than other parts by the refrigerant flowing through the folded portion 23c. As a result, heat dissipation from the wafer W held on the upper surface 11 is efficiently promoted, and the temperature distribution of the wafer W approaches uniformity without the occurrence of temperature singularities.

[0050] Furthermore, in the electrostatic chuck 1 of this embodiment, the refrigerant flow path 23 formed within the base member 20 consists of an outermost flow path 23a located on the outer circumference and an inlet-side flow path 23b located radially inward of the outermost flow path 23a. The folded-back section 23c connects the inlet-side flow path 23b in the direction extending along the circumferential direction to the outermost flow path 23a in the direction extending along the circumferential direction. The refrigerant supplied from the supply port 24 in the refrigerant flow path 23 flows through the inlet-side flow path 23b, passes through the folded-back section 23c, and then flows through the outermost flow path 23a. In this embodiment, as the refrigerant flows from the inlet-side flow path 23b located on the inner circumference to the outermost flow path 23a located on the outer circumference, a comparison of the turbulent viscosity ratio between Figure 10 and Figure 11 shows that turbulence of the refrigerant is likely to occur near the folded-back section 23c. The generated turbulent refrigerant efficiently promotes heat removal from the wafer W. The configuration of the electrostatic chuck 1 described above can also be rephrased as follows. Electrostatic chuck 1, A ceramic member 10 having an upper surface 11 for holding a wafer W and a substantially circular outer circumference, A base member 20 is positioned on the opposite side from the upper surface 11 of the ceramic member 10, and a refrigerant flow path 23 is formed therein. Equipped with, When viewing the ceramic member 10 from the upper surface 11 side, The ceramic member 10 has an orientation flat portion 12 on a part of its outer circumference that is formed radially inward from the virtual circle VC formed by the outer circumference. The refrigerant flow path 23 is The inlet channel 23b and the outermost channel 23a located radially outward from the inlet channel 23b, It has a return section 23c that connects the inlet side flow path 23b and the outermost flow path 23a, and also returns the refrigerant flow path 23.

[0051] Furthermore, in the electrostatic chuck 1 of this embodiment, the refrigerant flow path 23 formed in the base member 20 has uneven portions 23aC that alternately protrude radially outward and radially inward along the circumferential direction, as shown in Figure 3. Some of the multiple uneven portions 23aC of the outermost flow path 23a overlap with the orientation flat portion 12. That is, in this embodiment, when viewed from the stacking direction, the orientation flat portion 12, which is prone to becoming a hot spot, overlaps with some of the uneven portions 23aC. Therefore, turbulence is easily generated in the refrigerant flowing through the uneven portions 23aC, and the orientation flat portion 12 overlapping the uneven portions 23aC is cooled more than other parts by the turbulent refrigerant. As a result, heat dissipation from the wafer W held on the upper surface 11 of the upper portion 10a is efficiently promoted, and the temperature distribution of the wafer W approaches uniformity without the occurrence of temperature singularities.

[0052] Furthermore, as shown in Figures 3 and 5, a portion of the uneven portion 23aC in this embodiment overlaps with the virtual circle VC when viewed from the stacking direction. Therefore, the portion of the electrostatic chuck 1 projected onto the virtual circle VC, where the temperature of the wafer W held on the upper surface 11 of the upper portion 10a tends to rise during processing, is efficiently cooled by the turbulent coolant generated by the uneven portion 23aC.

[0053] Furthermore, the uneven portions 23aC formed in the outermost channel 23a of this embodiment, when viewed from the stacking direction, alternately protrude radially outward and radially inward along the circumferential direction of the virtual circle VC, overlapping the virtual circle VC at 11 or more locations. In other words, there are 11 or more locations where the uneven portions 23aC and the virtual circle VC overlap. Therefore, the upper surface 11 of the upper section 10a, onto which the virtual circle VC, which tends to rise in temperature, is projected, efficiently has its heat dissipated by the turbulent coolant flow generated by the uneven portions 23aC.

[0054] <Modified form of this embodiment> The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit, for example, the following modifications are also possible.

[0055] In the above embodiment, an electrostatic chuck 1, which is an example of a holding member for holding a wafer W as an object, was described. However, the holding member has a coolant flow path 23 formed in a cooling section located on the opposite side of the object holding surface, which has a folded portion 23c, and is deformable in the range where the coolant flow path 23 is folded near the folded portion 23c. For example, in the above embodiment, the ceramic member 10 that functions as a holding part had an upper disc portion 10a and a lower disc portion 10b with different diameters. However, for example, the upper disc portion 10a may have the same diameter as the lower disc portion 10b, and the upper disc portion 10a and the lower disc portion 10b may be formed integrally. In this case, the virtual circle VC corresponds to the outer shape of the upper surface that holds the wafer W.

[0056] In the above embodiment, the folded portion 23c of the refrigerant flow path 23 overlapped the orientation flat portion 12 when viewed from the stacking direction, but it may not overlap and may be located near the orientation flat portion 12. The shape of the orientation flat portion 12 can be deformed within the range formed radially inward from the virtual circle VC representing the outer circumference of the upper portion 10a. For example, the orientation flat portion 12 may be formed as a V-shaped notch rather than a straight line when viewed from the stacking direction. A V-shaped shape such as a notch reduces the possibility of partial cracking, improving the durability of the electrostatic chuck 1. Furthermore, even if the notched orientation flat portion comes into contact with the wafer W, force is less likely to concentrate partially from the orientation flat portion to the wafer W, thus reducing the risk of damaging the wafer W.

[0057] The positions of the supply port 24 and discharge port 25 formed in the refrigerant flow path 23 of the above embodiment are deformable. In order to generate turbulence in the folded portion 23c, it is preferable that the supply port 24 and discharge port 25 be arranged so that the folded portion 23c folds the refrigerant back from the inside to the outside.

[0058] In the above embodiment, the outermost channel 23a of the refrigerant channel 23 had a plurality of irregularities 23aC formed thereon, but the irregularities 23aC do not have to be formed thereon. Also, the irregularities 23aC formed in the outermost channel 23a do not have to be arranged so as to straddle the virtual circle VC when viewed from the stacking direction. It is preferable that the irregularities 23aC straddle the virtual circle VC at 11 or more locations, but they may straddle the virtual circle VC at fewer than 11 locations. The irregularities 23aC do not have to overlap with the orientation flat 12 when viewed from the stacking direction.

[0059] The outer circumference of the holding portion having the upper surface 11 that holds the wafer W is deformable within a substantially circular range. A substantially circular holding portion means that the outer circumference of the part where the orientation flat portion 12 is not formed is circular.

[0060] The embodiments of this specification have been described above based on the embodiments and modifications described above. The embodiments described above are for the purpose of facilitating understanding of this specification and do not limit it. This specification may be modified and improved without departing from its spirit and the scope of the claims, and equivalents thereof are included in this specification. Furthermore, any technical features that are not described as essential in this specification may be deleted as appropriate.

[0061] The present invention can also be realized in the following forms. [Application Example 1] A holding member for holding an object, A holding portion having a holding surface for holding the object, with a substantially circular outer circumference, A cooling section is positioned on the opposite side from the holding surface of the holding section, and has a flow path formed therein. Equipped with, When viewing the retaining member from the retaining surface side, The holding portion has an alignment portion formed radially inward from the virtual circle formed by the outer circumference on a part of the outer circumference. The flow path has a folded portion near the alignment portion in which the direction in which the flow path extends is reversed. A retaining member characterized by the following features. [Application Example 2] A holding member for holding an object, A holding portion having a holding surface for holding the object, with a substantially circular outer circumference, A cooling section is positioned on the opposite side from the holding surface of the holding section, and has a flow path through which a refrigerant flows. Equipped with, When viewing the retaining member from the retaining surface side, The holding portion has an alignment portion formed radially inward from the virtual circle formed by the outer circumference on a part of the outer circumference. The aforementioned flow path is An inner channel through which the refrigerant flows along the circumferential direction of the holding member, An outer channel is located radially outward from the inner channel, and the refrigerant that has flowed through the inner channel flows along the circumferential direction, The device has a folded flow path that connects the inner flow path and the outer flow path, reversing the direction of the refrigerant flowing through the inner flow path and the direction of the refrigerant flowing through the outer flow path, and a portion of which overlaps the alignment portion. A retaining member characterized by the following features. [Application Example 3] A holding member for holding an object, A holding portion having a holding surface for holding the object, with a substantially circular outer circumference, A cooling section is positioned on the opposite side from the holding surface of the holding section, and has a flow path formed therein. Equipped with, When viewing the retaining member from the retaining surface side, The holding portion has an alignment portion formed radially inward from the virtual circle formed by the outer circumference on a part of the outer circumference. The aforementioned flow path has an uneven flow path that alternately protrudes radially outward and radially inward along the virtual circle, with a portion of it overlapping the alignment portion. A retaining member characterized by the following features. [Application Example 4] The retaining member described in Application Example 3, When the holding member is viewed from the holding surface, a portion of the uneven channel overlaps the virtual circle. A retaining member characterized by the following features. [Application Example 5] A retaining member as described in Application Example 3 or Application Example 4, When the aforementioned uneven channel and the virtual circle are viewed from the holding surface towards the holding member, there are 11 or more combinations of overlapping and non-overlapping portions along the circumferential direction. A retaining member characterized by the following features. [Application Example 6] A retaining member described in any one of Application Examples 1 to 5, When the holding member is viewed from the holding surface, the flow path has an uneven flow path that alternately protrudes radially outward and radially inward along the circumferential direction of the virtual circle, with a portion of it overlapping the virtual circle. A retaining member characterized by the following features. [Application Example 7] A retaining member described in any one of the application examples 1 to 6, When the aforementioned uneven channel and the virtual circle are viewed from the holding surface towards the holding member, there are 11 or more combinations of overlapping and non-overlapping portions along the circumferential direction. A retaining member characterized by the following features. [Explanation of Symbols]

[0062] 1…Electrostatic chuck (holding member) 10…Ceramic component (holding part) 10a... Upper section 10b…lower section 11…Upper surface (holding surface) of the upper section 12... Orifura section (alignment section) 15... Chuck electrode 20…Base component (cooling section) 23, 23x, 23y… Refrigerant flow path (flow path) 23a, 23ax…Outermost flow path (outer flow path) 23aC…Uneven part (uneven channel) 23b... Inlet channel (inner channel) 23c, 23cx, 23yc, 26… Folded section 23d…Outlet side flow path 23ya...Outer flow path 23yb... Inner circumferential channel 23yd…Outer entrance / exit 23ye…Inner entrance / exit 24... Supply port 25…Discharge port 30...Joining layer CS… Cartesian coordinate system OL1…Center axis VC…Virtual Yen VC_A,VC_B…intersection W...wafer (object)

Claims

1. A holding member for holding an object, A holding portion having a holding surface for holding the object, with a substantially circular outer circumference, A cooling section is positioned on the opposite side from the holding surface of the holding section, and has a flow path formed therein. Equipped with, When viewing the retaining member from the retaining surface side, The holding portion has an alignment portion formed radially inward from the virtual circle formed by the outer circumference on a part of the outer circumference. The flow path has a folded portion in which the direction in which the flow path extends is folded back, The folded portion is positioned along the circumferential direction of the virtual circle, within a region 15° away from each end of the alignment portion, and along the radial direction of the virtual circle, within a region ±0.1L from the position of the alignment portion which serves as the reference for the distance L between the center of the virtual circle and the alignment portion. A retaining member characterized by the following features.

2. A holding member for holding an object, A holding portion having a holding surface for holding the object, with a substantially circular outer circumference, A cooling section is positioned on the opposite side from the holding surface of the holding section, and has a flow path through which a refrigerant flows. Equipped with, When viewing the retaining member from the retaining surface side, The holding portion has an alignment portion formed radially inward from the virtual circle formed by the outer circumference on a part of the outer circumference. The aforementioned flow path is An inner channel through which the refrigerant flows along the circumferential direction of the holding member, An outer channel is located radially outward from the inner channel, and the refrigerant that has flowed through the inner channel flows along the circumferential direction, The device has a folded flow path that connects the inner flow path and the outer flow path, reversing the direction of the refrigerant flowing through the inner flow path and the direction of the refrigerant flowing through the outer flow path, and a portion of which overlaps the alignment portion. A retaining member characterized by the following features.

3. A holding member for holding an object, A holding portion having a holding surface for holding the object, with a substantially circular outer circumference, A cooling section is positioned on the opposite side from the holding surface of the holding section, and has a flow path formed therein. Equipped with, When viewing the retaining member from the retaining surface side, The holding portion has an alignment portion formed radially inward from the virtual circle formed by the outer circumference on a part of the outer circumference. The aforementioned flow path has an uneven flow path that alternately protrudes radially outward and radially inward along the virtual circle, with a portion of it overlapping the alignment portion. A retaining member characterized by the following features.

4. A retaining member according to claim 3, When the holding member is viewed from the holding surface, a portion of the uneven channel overlaps the virtual circle. A retaining member characterized by the following features.

5. A retaining member according to claim 4, When the aforementioned uneven channel and the aforementioned virtual circle are viewed from the holding surface towards the holding member, there are 11 or more combinations of overlapping and non-overlapping portions along the circumferential direction. A retaining member characterized by the following features.

6. A retaining member according to claim 1 or claim 2, When the holding member is viewed from the holding surface, the flow path has an uneven flow path that alternately protrudes radially outward and radially inward along the circumferential direction of the virtual circle, with a portion of it overlapping the virtual circle. A retaining member characterized by the following features.

7. A retaining member according to claim 6, When the aforementioned uneven channel and the aforementioned virtual circle are viewed from the holding surface towards the holding member, there are 11 or more combinations of overlapping and non-overlapping portions along the circumferential direction. A retaining member characterized by the following features.

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