Holding device

Abstract

To provide a holding device capable of improving thermal uniformity on a holding surface for holding an object.SOLUTION: An electrostatic chuck 1 comprises: a ceramic plate-like member 10 having a holding surface 11 and a lower surface 12 provided on the opposite side, in the thickness direction, to the holding surface 11; and a chuck electrode 50 and a heater electrode 60 which are disposed inside the plate-like member 10. The electrostatic chuck holds a semiconductor wafer W on the holding surface 11. On the plate-like member 10, there are disposed: a coolant passage 18 for flowing a coolant; and feeding terminals 54 and 64 which are electrically connected to the chuck electrode 50 and the heater electrode 60, respectively. The plate-like member has terminal holes 14 and 15 which are opened to the lower surface 12. Bottom surfaces 14b and 15b of the terminal holes 14 and 15 are disposed further on the lower surface 12 side than a passage upper surface 18a located on the holding surface 11 side on an inner surface of the coolant passage 18.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] In semiconductor manufacturing processes, electrostatic chucks (holding devices) are used to hold semiconductor wafers. A widely known electrostatic chuck includes a ceramic plate-shaped member for holding the semiconductor wafer, a metallic base member with a coolant flow path, and a bonding layer that bonds the plate-shaped member to the base member. In this type of electrostatic chuck, the bonding layer may be damaged by plasma during processing of the semiconductor wafer. Therefore, it is necessary to protect the bonding layer from plasma. Furthermore, the bonding layer restricts heat transfer between the base member and the plate-shaped member. Furthermore, the different thermal expansion coefficients of the plate-shaped member and the base member may result in poor bonding in the bonding layer.

[0003] Therefore, as an electrostatic chuck that does not use a bonding layer, for example, Patent Document 1 discloses an electrostatic chuck that is composed only of a monolithic body (plate-shaped member). In this electrostatic chuck, an internal electrode and a coolant flow path are provided within the ceramic monolithic body. This solves the above-mentioned problems that arise from providing a bonding layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2022-520784 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the electrostatic chuck described in Patent Document 1, the bottom surface of the blind hole, which is provided for arranging a power supply terminal that supplies power to the internal electrode in the monolithic body, is located higher (on the holding surface side) than the upper surface of the coolant flow path. This results in a deeper blind hole and a larger volume. Furthermore, because the blind hole is an open space, heat transfer is significantly worse in the blind hole than in other areas. Therefore, the cooling effect of the coolant is reduced around the blind hole, and the area directly above the blind hole becomes a temperature singularity on the holding surface, potentially deteriorating the thermal uniformity of the holding surface.

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

[0007] In order to solve the above problems, one aspect of the present disclosure is to a ceramic plate-like member having a first surface and a second surface provided on the opposite side of the first surface in a thickness direction; an internal electrode disposed inside the plate-shaped member, A holding device for holding an object on the first surface, the plate-like member is formed with a coolant flow path for allowing a coolant to flow, and a bottomed hole in which a power supply terminal electrically connected to the internal electrode is disposed and which opens to the second surface, The bottom surface of the bottomed hole is located closer to the second surface than a third surface, which is located closer to the first surface, of the inner surface of the refrigerant flow path.

[0008] In this holding device, the bottom surfaces of the blind holes are positioned below the third surface of the refrigerant flow path, making the blind holes shallower. This reduces the volume of the blind holes (increasing the volume of the plate-shaped member), improving heat transfer at the positions where the blind holes are located. Furthermore, because there are no blind holes (spaces) on the first surface side of the refrigerant flow path from the third surface, the heat of the refrigerant can be transferred uniformly throughout the entire plate-shaped member in a planar view. As a result, heat conduction can be improved in the portions of the blind holes on the first surface side of the third surface of the plate-shaped member, improving thermal uniformity on the first surface.

[0009] In the above-mentioned holding device, It is preferable that the bottom surface of the blind hole is located closer to the second surface than a fourth surface, which is located on the second surface side of the inner surface of the refrigerant flow path.

[0010] By positioning the bottom of the blind hole below the fourth surface of the refrigerant flow path in this manner, the volume of the blind hole can be further reduced (the volume of the plate-shaped member can be further increased). This allows the heat of the refrigerant to be transferred more efficiently and uniformly to the first surface. This further improves the thermal uniformity on the first surface.

[0011] In addition, in any of the above-mentioned holding devices, The plate-like member may include a plurality of the internal electrodes.

[0012] By providing multiple internal electrodes within the plate-shaped member in this manner, for example, when a heater electrode is provided, the temperature uniformity of the first surface can be further improved. Furthermore, when a high-frequency electrode is provided, the plasma can be controlled with high precision, thereby improving the accuracy of the process treatment of the held object. In other words, by providing a heater electrode and a high-frequency electrode within the plate-shaped member, the temperature uniformity of the first surface, in other words, the temperature uniformity of the held object, can be improved while also improving the accuracy of the process treatment of the object.

[0013] In addition, in any of the above-mentioned holding devices, The plate-like member may have a plurality of blind holes formed therein.

[0014] When multiple blind holes are formed in the plate-shaped member in this manner, the bottom surfaces of all blind holes are positioned closer to the second surface of the plate-shaped member than the third surface of the refrigerant flow path, thereby allowing the heat of the refrigerant to be transferred efficiently and uniformly to the entire first surface. Therefore, even when the plate-shaped member has multiple blind holes, temperature singularities are unlikely to occur at the positions of all blind holes, thereby improving thermal uniformity on the first surface. [Effects of the Invention]

[0015] According to the present disclosure, it is possible to provide a holding device that can improve the temperature uniformity on the first surface (holding surface) of the holding member. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic perspective view of an electrostatic chuck according to an embodiment; [Figure 2] 1 is a schematic configuration diagram of an XZ cross section of an electrostatic chuck according to an embodiment. [Figure 3] 10A and 10B are diagrams illustrating an example in which the arrangement positions of terminal holes are changed. [Figure 4] FIG. 10 is a diagram showing a first modified example. [Figure 5] FIG. 10 is a diagram showing a second modified example. [Figure 6] FIG. 10 is a schematic configuration diagram of an XZ cross section of an electrostatic chuck according to another embodiment (first embodiment). [Figure 7] FIG. 10 is a schematic configuration diagram of an XZ cross section of an electrostatic chuck according to another embodiment (mode 2). [Figure 8] FIG. 10 is a schematic diagram of an XZ cross section of an electrostatic chuck according to another embodiment (Fourth Embodiment). [Figure 9] FIG. 10 is a schematic diagram of an XZ cross section of an electrostatic chuck according to another embodiment (sixth embodiment). DETAILED DESCRIPTION OF THE INVENTION

[0017] A holding device according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In this embodiment, the holding device will be described by taking as an example an electrostatic chuck used in semiconductor manufacturing equipment such as an etching device (such as a plasma etching device) or a film forming device (such as a CVD film forming device or a sputtering film forming device).

[0018] An electrostatic chuck 1 according to this embodiment will now be described with reference to FIGS. 1 and 2. The electrostatic chuck 1 according to this 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 includes a plate-shaped member 10, a chuck electrode, a high-frequency electrode, and a coolant flow path. The chuck electrode, the high-frequency electrode, and the coolant flow path are disposed within the plate-shaped member 10. In other words, the electrostatic chuck 1 does not use a bonding layer.

[0019] 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 the 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, and the direction of the XY plane is an example of the "plane direction" in the present disclosure.

[0020] As shown in FIG. 1, the plate-shaped member 10 is a stepped, disc-shaped member made of ceramics. The plate-shaped member 10 has a convex shape with a smaller diameter at the top than at the bottom. While various ceramics can be used, it is preferable to use ceramics whose main component is aluminum oxide (alumina, Al2O3) or aluminum nitride (AlN) from the viewpoints of strength, wear resistance, plasma resistance, etc. Here, the term "main component" refers to the component with the largest content (for example, a component with a volume content of 90 vol% or more).

[0021] 1 and 2, the plate-shaped member 10 has a holding surface 11 (upper surface) that holds the semiconductor wafer W, and a lower surface 12 that is provided on the opposite side of the holding surface 11 in the thickness direction (i.e., the Z-axis direction) of the plate-shaped member 10. 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.

[0022] Here, the diameter of the plate-shaped member 10 is, for example, about 150 mm to 300 mm at the top and about 180 mm to 400 mm at the bottom. The thickness of the plate-shaped member 10 is, for example, about 2 mm to 60 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).

[0023] As shown in FIG. 2, the plate-like member 10 includes a chuck electrode 50 therein. The chuck electrode 50 has, for example, a substantially circular shape when viewed in the Z-axis direction and is made of a conductive material (e.g., tungsten, molybdenum, etc.). A power supply terminal 54, which is connected to an external power supply (not shown), is electrically connected to the chuck electrode 50 via an electrically connected conductive member 52. The conductive member 52 is composed of a plurality of vias and electrode pads, and these vias and pads are made of a conductive material (e.g., tungsten, molybdenum, etc.). When a voltage is applied to the chuck electrode 50 from the external power supply via the power supply terminal 54 and the conductive member 52, an electrostatic attraction force (attraction force) is generated, and the semiconductor wafer W is attracted and fixed to the holding surface 11 by this electrostatic attraction force.

[0024] The plate-shaped member 10 also includes a heater electrode 60. The heater electrode 60 is made of a conductive material (e.g., tungsten, molybdenum, etc.). The heater electrode 60 is a heating resistor that heats the holding surface 11 to a predetermined temperature, and is patterned, for example, in a spiral shape when viewed in the Z-axis direction. A power supply terminal 64, which is connected to an external power supply (not shown), is electrically connected to the heater electrode 60 via an electrically connected conductive member 62. The conductive member 62 is composed of a plurality of vias and electrode pads, and these vias and pads are made of a conductive material (e.g., tungsten, molybdenum, etc.). When a voltage is applied to the heater electrode 60 from the external power supply via the power supply terminal 64 and the conductive member 62, the heater electrode 60 generates heat, thereby heating the plate-shaped member 10.

[0025] The plate-like member 10 is formed with terminal holes 14, 15 for arranging the power supply terminals 54, 64. These terminal holes 14, 15 are bottomed holes that open to the lower surface 12 and have a circular recessed shape (a shape recessed toward the holding surface 11) formed in the Z-axis direction. In other words, the terminal holes 14, 15 are an example of the "bottomed hole" of the present disclosure. The diameter of these terminal holes 14, 15 is smaller than the diameter of the inlet / outlet of the refrigerant flow path 18, which will be described later. The depth (length in the Z-axis direction) of the terminal holes 14, 15 will be described later.

[0026] The terminal holes 15 in which the power supply terminals 64 that supply power to the heater electrode 60 are disposed can be disposed at any position depending on the shape of the heater electrode 60. For example, as shown in Fig. 3, if the heater electrode 60 is provided up to the vicinity of the lower outer edge of the plate-shaped member 10, the terminal holes 15 may be disposed on the outer periphery side. Similarly, the terminal holes 14 in which the power supply terminals 54 that supply power to the chuck electrode 50 are disposed can also be disposed at any position.

[0027] Furthermore, a coolant flow path 18 for flowing a coolant (e.g., a fluorine-based inert liquid, water, etc.) is formed inside the plate-shaped member 10. The coolant flow path 18 is arranged so as to extend in the XY plane, and has, for example, a substantially spiral shape when viewed in the Z-axis direction (plan view). By flowing a coolant through such a coolant flow path 18, the plate-shaped member 10 is cooled over the entire XY plane. This allows the semiconductor wafer W held on the holding surface 11 to be cooled.

[0028] Here, the deeper the terminal holes 14, 15 are, the larger the volume of the bottomed holes (the space formed in the plate-shaped member 10). The areas of the terminal holes 14, 15 have extremely poor heat transfer compared to other areas of the plate-shaped member 10. Therefore, the cooling effect of the refrigerant flowing through the refrigerant flow path 18 is reduced around the terminal holes 14, 15, and the areas directly above the terminal holes 14, 15 on the holding surface 11 may become temperature singular points, which may deteriorate the thermal uniformity on the holding surface 11.

[0029] Therefore, in the electrostatic chuck 1 of this embodiment, the bottom surfaces 14b, 15b of the terminal holes 14, 15 are arranged closer to the lower surface 12 than the flow path upper surface 18a, which is located on the holding surface 11 side of the inner surface of the coolant flow path 18. The flow path upper surface 18a is an example of the "third surface" in the present disclosure.

[0030] This allows the depths of the terminal holes 14, 15 to be shallower in the electrostatic chuck 1. Therefore, the volume of the terminal holes 14, 15 is reduced (the volume of the plate-shaped member 10 is increased), improving heat conduction near the terminal holes 14, 15 and preventing temperature singularities from occurring directly above the terminal holes 14, 15 on the holding surface 11. Furthermore, the diameters of the terminal holes 14, 15 are smaller than the diameters of the inlets and outlets of the coolant flow paths 18, which also prevents temperature singularities from occurring on the holding surface 11. Furthermore, since there is no space above the upper surface 18a of the coolant flow paths 18 (on the holding surface 11 side) within the plate-shaped member 10, the heat of the coolant flowing through the coolant flow paths 18 can be uniformly transferred to the entire plate-shaped member 10 when viewed in the Z-axis direction (plan view). Therefore, in the plate-shaped member 10, the heat conduction in the portion above (on the holding surface 11 side of) the bottom surfaces 14b, 15b of the terminal holes 14, 15 can be improved, and the temperature uniformity on the holding surface 11 can be improved.

[0031] In the electrostatic chuck 1 of this embodiment, the bottom surface 15b of the terminal hole 15 is disposed below (on the lower surface 12 side of) the flow path lower surface 18b of the coolant flow path 18. This makes it possible to further reduce the volume of the terminal hole 15 (further increase the volume of the plate-shaped member 10). Therefore, the heat of the coolant flowing through the coolant flow path 18 can be more efficiently and uniformly transferred to the holding surface 11, thereby further improving the temperature uniformity on the holding surface 11.

[0032] Furthermore, the electrostatic chuck 1 of this embodiment includes a heater electrode 60 in addition to the chuck electrode 50 within the plate-shaped member 10. This allows the temperature distribution of the holding surface 11 to be controlled with high precision, thereby further improving the temperature uniformity on the holding surface 11.

[0033] Modified examples of the electrostatic chuck will now be described with reference to Fig. 4 and Fig. 5. First, a first modified example is a configuration in which the depth of the terminal holes 14 is shallower than in the above-described embodiment, as shown in Fig. 4. That is, in the electrostatic chuck 1a of the first modified example, the bottom surfaces 14b, 15b of the two terminal holes 14, 15 are located below the plate-shaped member 10 (toward the lower surface 12) and the flow path upper surface 18a of the coolant flow path 18.

[0034] In the electrostatic chuck 1a of this first modified example, the volume of the terminal hole 14 in the plate-shaped member 10 is reduced compared to the above embodiment. Specifically, as shown in Fig. 4, the bottom surface 14b of the terminal hole 14 is disposed below (on the side of the lower surface 12) the flow path lower surface 18b of the coolant flow path 18. As a result, the diameter of the terminal hole 14 remains unchanged, but the depth is shallower, and therefore the volume of the terminal hole 14 is reduced.

[0035] The bottom surfaces 15b of the terminal holes 15 are also located below (closer to the bottom surface 12) than the flow path lower surface 18b of the coolant flow path 18. In this manner, in the electrostatic chuck 1a of the first modified example, the bottom surfaces 14b, 15b of the terminal holes 14, 15 formed in the plate-shaped member 10 are located below (closer to the bottom surface 12) than the flow path lower surface 18b of the coolant flow path 18. In other words, all of the bottom surfaces of the multiple terminal holes formed in the plate-shaped member 10 are located below (closer to the bottom surface 12) than the flow path lower surface 18b of the coolant flow path 18.

[0036] This allows the heat of the refrigerant flowing through the refrigerant flow path 18 to be transferred to the holding surface efficiently and uniformly across the entire surface. Therefore, temperature singularities are less likely to occur at the positions of the terminal holes 14, 15 formed in the plate-like member 10, thereby improving the temperature uniformity on the holding surface 11.

[0037] Next, in a second modified example, as shown in FIG. 5 , a plurality of heater electrodes are provided within a plate-shaped member 10. That is, in an electrostatic chuck 1b of the second modified example, a heater electrode 60 is arranged inside an XY plane within the plate-shaped member 10, and a heater electrode 70 is arranged outside the heater electrode 60. A bottom surface 16b of a terminal hole 16, in which a power supply terminal 74 for supplying power to the newly provided heater electrode 70 is arranged, is located below (on the side of the lower surface 12) a flow path lower surface 18b of the coolant flow path 18. The power supply terminal 74 is electrically connected to the heater electrode 70 via a conductive member 72. Although a case in which two heater electrodes are arranged is illustrated here, three or more heater electrodes may be arranged.

[0038] In this way, the electrostatic chuck 1b of the second modified example is provided with multiple heater electrodes 60, 70 within the plate-shaped member 10, thereby enabling more precise temperature control on the holding surface 11, thereby further improving the thermal uniformity on the holding surface 11.

[0039] As described above, according to the electrostatic chuck 1 (1a, 1b) of this embodiment, the bottom surfaces 14b, 15b (16b) of the terminal holes 14, 15 (16) are located below the flow path upper surface 18a of the coolant flow path 18, so the depth of the terminal holes 14, 15 (16) can be made shallow. Therefore, the volume of the terminal holes 14, 15 (16) is reduced (the volume of the plate-shaped member 10 is increased), and heat transfer at the positions where the terminal holes 14, 15 (16) are arranged can be improved. Furthermore, because there is no space on the holding surface 11 side of the flow path upper surface 18a of the coolant flow path 18, heat from the coolant flowing through the coolant flow path 18 can be uniformly transferred to the entire plate-shaped member 10 in the Z-axis direction (plan view). For these reasons, heat conduction can be improved in the portion of the plate-shaped member 10 closer to the holding surface 11 than the bottom surfaces 14b, 15b (16b) of the terminal holes 14, 15 (16), and therefore, thermal uniformity on the holding surface 11 can be improved.

[0040] Here, as other embodiments, embodiments 1 to 10 will be described. First, as embodiment 1, as shown in Fig. 6, a space S may be provided directly above the refrigerant flow path 18 (above the flow path upper surface 18a in the Z-axis direction). Since the portion directly above the refrigerant flow path 18 has particularly good heat dissipation, providing the space S can suppress heat dissipation from the portion directly above the refrigerant flow path 18, reducing uneven heat dissipation and improving temperature uniformity on the holding surface 11.

[0041] As a second embodiment, as shown in FIG. 7, a gas flow path 19 for supplying an inert gas (e.g., He gas) to the holding surface 11 may be provided between the refrigerant flow path 18 and the lower surface 12 in the Z-axis direction (below the refrigerant flow path 10).

[0042] In a third embodiment, the plate-shaped member 10 may be made of a plurality of ceramic materials instead of a single ceramic material. For example, by using a high-purity ceramic material for the holding surface 11, which is the same as the other portions, the performance of the electrostatic chuck can be improved while reducing costs.

[0043] 8, the refrigerant flow paths 18 may be arranged in multiple stages in the Z-axis direction, and gas flow paths 19 may be provided between the refrigerant flow paths 18 arranged at different positions in the Z-axis direction. In this way, the gas flow paths 19 act as a heat insulating layer, making it possible to adjust the amount of heat drawn.

[0044] In a fifth embodiment, when the refrigerant flow paths 18 are provided in multiple stages in the Z-axis direction, they may be arranged so as not to overlap each other as viewed in the Z-axis direction. By arranging the refrigerant flow paths 18 in this manner, heat dissipation can be improved and the temperature uniformity on the holding surface 11 can also be improved.

[0045] 9, the refrigerant flow path 18 and the gas flow path 19 may be arranged so as not to overlap each other when viewed in the Z-axis direction. This makes it possible to prevent a decrease in the heat dissipation effect of the gas flow path 19.

[0046] In a seventh embodiment, the coolant flow path 18 may be disposed between the internal electrodes in the Z-axis direction. For example, it may be disposed between the chuck electrode 50 and the heater electrode 60. Such an arrangement allows the heat dissipation effect to be expanded in the planar direction (over the entire holding surface 11).

[0047] In a ninth embodiment, when the refrigerant flow paths 18 and the gas flow paths 19 are each provided in multiple stages in the Z-axis direction, the refrigerant flow paths 18 and the gas flow paths 19 may be arranged alternately in the Z-axis direction. This allows the amount of heat drawn to be adjusted by the gas flow paths 19 when the amount of heat drawn is too large, thereby improving the temperature uniformity on the holding surface 11.

[0048] In form 10, it is preferable to arrange terminal holes 14, 15, and 16 on the inlet side (near the inlet) of refrigerant flow path 18, that is, upstream of the flow of refrigerant. This allows terminal holes 14, 15, and 16, which tend to become hot, to be efficiently cooled, which makes it possible to suppress the occurrence of temperature singularities on holding surface 11 and improve the thermal uniformity on holding surface 11.

[0049] The above-described embodiment is merely illustrative and does not limit the present disclosure in any way. Naturally, various improvements and modifications are possible within the spirit and scope of the present disclosure. For example, the above-described embodiment illustrates a case in which two internal electrodes (chuck electrode 50 and heater electrode 60) are provided within plate-shaped member 10, but the present disclosure can also be applied to a case in which other internal electrodes (such as a radio-frequency electrode or a driver electrode) are provided. When a radio-frequency electrode is provided, plasma can be controlled with high precision, thereby improving the accuracy of processing of semiconductor wafers. Furthermore, when a driver electrode is provided, the entire holding surface is heated uniformly by heat generated by the driver electrode, thereby further improving the uniformity of temperature on holding surface 11.

[0050] Furthermore, in the above embodiment, the plate-like member 10 has been exemplified as having a stepped shape, but the plate-like member 10 may have a shape without a step (simple disk shape). [Explanation of symbols]

[0051] 1. Electrostatic chuck 10 Plate-shaped member 11 Holding surface 12 Bottom side 14 terminal holes 14b bottom 15 terminal holes 15b Bottom 18 refrigerant flow path 18a Upper surface of flow channel 18b Lower surface of flow path 19 Gas flow path 50 Chuck electrode 60 heater electrode W Semiconductor wafer

Claims

1. a ceramic plate-like member having a first surface and a second surface provided on the opposite side of the first surface in a thickness direction; an internal electrode disposed inside the plate-shaped member, A holding device for holding an object on the first surface, the plate-like member is formed with a coolant flow path for allowing a coolant to flow, and a bottomed hole in which a power supply terminal electrically connected to the internal electrode is disposed and which opens to the second surface, The bottom surface of the blind hole is disposed closer to the second surface than a third surface, which is located on the first surface side of the inner surface of the refrigerant flow path. A holding device characterized by:

2. 2. The holding device according to claim 1, The bottom surface of the blind hole is disposed closer to the second surface than a fourth surface, which is located on the second surface side of the inner surface of the refrigerant flow path. A holding device characterized by:

3. The holding device according to claim 1 or 2, The plate-shaped member includes a plurality of the internal electrodes. A holding device characterized by:

4. 2. The holding device according to claim 1, The plate-like member has a plurality of the blind holes formed therein. A holding device characterized by:

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