Holding device

Abstract

To provide a retaining device capable of suppressing particles from sticking on an object mounted on a mount surface.SOLUTION: An electrostatic chuck 1 has a plate-like member 10 which comprises a mount surface 11 mounted with a semiconductor wafer W to be retained, and a plurality of gas discharge flow passages 44 formed in the plate-like member 10 so as to supply an inert gas to the mount surface 11, wherein the gas discharge flow passage 44 is formed extending along a thickness of the plate-like member 10 and comprises a porous body 60 inside, and a groove 16 is formed in a circumference of an opening of the gas discharge flow passage on the side of the mount surface 11.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] Electrostatic chucks are known as holding devices for holding an object. In electrostatic chucks, an inert gas is supplied and filled into a minute space between a mounting surface and the object to improve heat exchange with the object. In this type of electrostatic chuck, as described in Patent Document 1, for example, a conduit (gas hole) for supplying the inert gas to the mounting surface is formed inside a dielectric layer (plate-shaped member). A porous plug (porous body) is provided in the conduit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4959905 Summary of the Invention [Problem to be solved by the invention]

[0004] In the electrostatic chuck, particles (fine particles) are generated due to the friction between the mounting surface and the object, which causes the surface of the plate-like member to be finely scraped or the porous body to be locally damaged, etc. If the particles are generated and adhere to the object, the accuracy of various processes performed on the object may decrease, and the product yield may decrease.

[0005] In particular, in an electrostatic chuck in which a porous body is disposed in a gas hole, the porous body is more fragile and easily damaged than a plate-like member, and therefore there is a high risk of particles being generated due to the porous body. Therefore, in this type of electrostatic chuck, a measure to prevent particles from adhering to the object is desired.

[0006] Therefore, the present disclosure has been made to solve the above-mentioned problems, and aims to provide a holding device that can prevent particles from adhering to an object placed on a mounting surface. [Means for solving the problem]

[0007] In order to solve the above problems, one aspect of the present disclosure is to a plate-like member having a placement surface on which an object to be held is placed; a plurality of gas holes formed in the plate-shaped member for supplying an inert gas to the mounting surface; In a holding device having the gas hole is formed to extend in a thickness direction of the plate-like member and has a porous body therein; A groove is formed around the opening of the gas hole on the side of the mounting surface.

[0008] In this holding device, a porous body is disposed inside the gas hole, more specifically, in the portion of the gas hole that opens to the mounting surface side. A groove is formed around the opening of the gas hole where the porous body is disposed. This groove is preferably formed so as to surround the entire periphery of the opening of the gas hole.

[0009] By forming such grooves, particles generated by the porous body can be collected in the grooves, thereby preventing the particles from adhering to the object held on the mounting surface.

[0010] In the above-mentioned holding device, The groove is preferably formed in a circular ring shape.

[0011] By forming the grooves in an annular shape, the grooves are arranged equidistant from the gas hole opening so as to follow the outer periphery of the gas hole opening. Therefore, the annular grooves can reliably capture particles originating from the porous body. This can further prevent particles from adhering to the target object.

[0012] In any of the above-mentioned holding devices, a recessed portion that opens onto the mounting surface, It is preferable that the opening of the gas hole and the groove are disposed on the bottom surface of the recess.

[0013] By providing such a recess, the gas discharged from the gas hole can be spread (diffused) in the recess before hitting the object. In other words, it is possible to prevent the gas from hitting the object locally and cooling only that area. This makes it less likely that temperature singularities will occur in the object, improving the uniformity of the temperature distribution in the object.

[0014] Furthermore, particles originating from the porous body can be efficiently collected by the grooves in the recesses, which further prevents particles from adhering to the object.

[0015] In any of the above-mentioned holding devices, The surface roughness inside the groove is preferably Ra 0.1 μm or more.

[0016] By making the surface roughness inside the grooves Ra 0.1 μm or more, particles collected in the grooves are less likely to be discharged from the grooves. This allows the particles to be firmly captured in the grooves, effectively preventing them from adhering to the target object. [Effects of the Invention]

[0017] According to the present disclosure, it is possible to provide a holding device that can prevent particles from adhering to an object placed on a placement surface. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic perspective view of an electrostatic chuck according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram of the electrostatic chuck taken along an XZ cross section. [Figure 3] FIG. 3 is a diagram showing the shape of a gas flow path. [Figure 4] FIG. 3 is an enlarged view of part A shown in FIG. [Figure 5] FIG. 3 is a plan view of part A shown in FIG. 2. [Figure 6] 10A to 10C are diagrams illustrating a method for forming a groove, showing a preparation step. [Figure 7] FIG. 10 is a diagram illustrating a method for forming a groove, showing the state after processing. [Figure 8] FIG. 10 is an enlarged view showing the vicinity of an opening of a gas discharge flow path in a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] 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).

[0020] [First embodiment] First, an electrostatic chuck 1 according to a first embodiment will be described with reference to FIGS. 1 to 5. 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 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 the X and Y axes are axes in the radial direction of the electrostatic chuck 1.

[0022] 1, the plate-shaped member 10 is a disk-shaped member and includes an upper surface, i.e., a mounting surface 11 on which a semiconductor wafer W is mounted, and a lower surface 12 provided on the opposite side of the mounting surface 11 in the thickness direction (Z-axis direction) of the plate-shaped member 10. Various ceramics are used as the ceramic material for forming the plate-shaped member 10, but from the viewpoints of strength, wear resistance, plasma resistance, etc., it is preferable to use ceramics whose main component is, for example, aluminum oxide (alumina, Al2O3) or aluminum nitride (AlN). Note that the term "main component" as used here means the component with the largest content (for example, a component with a volume content of 90 vol% or more).

[0023] Here, the diameter of the plate-shaped member 10 is, for example, about 150 mm to 300 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 in the range of 10 W / mK to 50 W / mK (more preferably, 18 W / mK to 30 W / mK).

[0024] 2 and 3, a gas flow path 40 is formed inside the plate-like member 10. The gas flow path 40 supplies an inert gas (e.g., He gas) to a minute space between the mounting surface 11 and the semiconductor wafer W placed on the mounting surface 11. The mounting surface 11 has a large number of minute protrusions 70 (see FIG. 4) formed thereon to create a minute space between the semiconductor wafer W and the mounting surface 11. The gas flow path 40 includes a gas exhaust flow path 44, a gas tunnel 42, and a gas introduction flow path 46.

[0025] 2, the gas exhaust flow path 44 is a flow path that extends in the Z-axis direction, has one end connected to the gas tunnel 42, and the other end opening to the mounting surface 11. As shown in FIG. 2, a plurality of gas exhaust flow paths 44 (eight in this embodiment) are provided in the plate-shaped member 10. The gas exhaust flow paths 44 are an example of the "gas hole" of the present disclosure.

[0026] A porous body 60 is disposed inside this gas exhaust flow path 44. The porous body 60 is a cylindrical porous plug. In this embodiment, the porous body 60 is disposed throughout the gas exhaust flow path 44, that is, throughout the entire flow path from the opening on the mounting surface 11 side to the opening on the gas tunnel 42 side. However, the porous body 60 does not need to be disposed throughout the entire gas exhaust flow path 44. For example, the porous body 60 may be disposed in the gas exhaust flow path 44 over a length from the opening on the mounting surface 11 side to at least half the flow path length of the gas exhaust flow path 44 in the Z-axis direction (the length from the opening on the mounting surface 11 side to the opening on the gas tunnel 42 side).

[0027] The porous body 60 is made of a ceramic material (e.g., Al2O3, AlN, etc.) and has a porosity that allows a necessary amount of inert gas to flow onto the mounting surface 11 and can suppress the intrusion of plasma into the gas flow path 40. The porous body 60 may be formed integrally with the plate-like member 10, or may be integrally bonded to the plate-like member 10.

[0028] 3, the gas tunnel 42 is a gas flow path formed in the XY plane direction when viewed in the Z-axis direction. The gas tunnel 42 includes a pair of annular flow paths 42a, 42b and a plurality of connecting flow paths 42c that connect these annular flow paths. In this embodiment, eight connecting flow paths 42c are provided, and each connecting flow path 42c is arranged to extend radially from the center of the electrostatic chuck 1 (mounting surface 11) toward the outer periphery.

[0029] 2, the gas introduction flow path 46 is a flow path that extends in the Z-axis direction, has one end that opens to the lower surface 12, and the other end that connects to the gas tunnel 42. The gas introduction flow path 46 communicates with the through-hole 26 formed in the base member 20.

[0030] In the gas flow path 40 having such a flow path configuration, first, an inert gas is supplied to the gas introduction flow path 46 from below the electrostatic chuck 1 (plate-like member 10). Then, the inert gas supplied to the gas introduction flow path 46 is discharged onto the mounting surface 11 via the gas tunnel 42 and each gas discharge flow path 44. As a result, the inert gas is filled into the minute space between the mounting surface 11 and the semiconductor wafer W.

[0031] 4 and 5, a recess 14 is formed at the outlet of the gas flow path 40, that is, at the opening of the gas exhaust flow path 44 on the mounting surface 11 side. This recess 14 is a circular bottomed hole (counterbore) that opens on the mounting surface 11 side, and the gas exhaust flow path 44 is located at the center of the recess 14. In other words, the opening of the gas exhaust flow path 44 on the mounting surface 11 side is located on the bottom surface of the recess 14.

[0032] Furthermore, an annular groove 16 is formed on the bottom surface of the recess 14. In this embodiment, the groove 16 is provided on the outer edge (side surface) of the recess 14. That is, the groove 16 is arranged so that the center of the groove 16 substantially coincides with the center of the gas exhaust flow path 44 and surrounds the periphery of the opening of the gas exhaust flow path 44 on the mounting surface 11 side. In other words, the groove 16 is arranged at a position equidistant from the opening of the gas exhaust flow path 44 so as to follow the outer periphery of the opening of the gas exhaust flow path 44 on the mounting surface 11 side. The depth of the recess 14 is approximately 30 μm to 50 μm, and the depth of the groove 16 is approximately 10 μm to 50 μm. The width of the groove 16 is approximately 100 μm to 1000 μm, and the surface roughness inside the groove 16 is Ra 0.1 μm or more. Since a large surface roughness inside the groove 16 can cause particles to be generated, the surface roughness is preferably less than Ra 1.0 μm.

[0033] Here, a method for forming the grooves 16 will be briefly described with reference to FIGS. 6 and 7. FIGS. 6 and 7 schematically show the structure near the recesses 14 and the gas discharge flow paths 44. The grooves 16 can be formed, for example, by machining the mounting surface 11. As shown in FIG. 6, a plate-like member 10 is prepared in which a porous body 60 is provided in the gas discharge flow paths 44 and in which recesses 14 are formed. Next, the portion that will become the grooves 16 is ground away using a fine grindstone, thereby forming the grooves 16 as shown in FIG. 7. At this time, the rotating grindstone is moved along the outer periphery of the recesses 14, thereby forming the grooves 16 in an annular shape.

[0034] 2, the plate-like member 10 is provided therein with a chuck electrode 50. The chuck electrode 50 has, for example, a substantially circular shape as viewed in the Z-axis direction, and is made of a conductive material (for example, tungsten or molybdenum). The chuck electrode 50 is disposed over almost the entire area of ​​the mounting surface 11 (slightly smaller than the mounting surface 11) as viewed in the Z-axis direction. When a voltage is applied to the chuck electrode 50, an electrostatic attraction force (attraction force) is generated over the entire area of ​​the mounting surface 11, and the semiconductor wafer W is attracted and fixed to the mounting surface 11 by this electrostatic attraction force.

[0035] 1, the base member 20 joined to the plate-like member 10 is disposed on the side of the plate-like member 10 opposite the mounting surface 11, i.e., on the lower surface 12 side. The base member 20 is formed, for example, in a cylindrical shape. The base member 20 is preferably formed, for example, from a metal (for example, aluminum or an aluminum alloy), but may also be formed from a material other than a metal (for example, ceramics).

[0036] 1 and 2, the base member 20 has an upper surface 21 and a lower surface 22 provided on the opposite side 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 a bonding layer 30.

[0037] 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 made of aluminum) is preferably in the range of 160 W / mK to 250 W / mK.

[0038] 2, the base member 20 has through-holes 26 formed therein, which extend in the Z-axis direction, penetrate the base member 20, and open to the upper surface 21 and the lower surface 22. The through-holes 26 are arranged at positions overlapping with the gas introduction channels 46 of the plate-like member 10 when viewed in the Z-axis direction, and communicate with the gas introduction channels 46 via the through-holes 36 formed in the bonding layer 30.

[0039] In addition, a refrigerant flow path (not shown) is formed in the base member 20 for flowing a refrigerant (e.g., a fluorine-based inert liquid, water, etc.), and by flowing the refrigerant in this refrigerant flow path, the base member 20 is cooled, and thereby the plate-like member 10 is cooled via the bonding layer 30.

[0040] As shown in FIGS. 1 and 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-based resin, an acrylic-based resin, or an epoxy-based 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 (assumed to be a silicone-based resin) is preferably in the range of 0.1 W / mK to 2.0 W / mK.

[0041] A through hole 36 is formed in the bonding layer 30, connecting the through hole 26 and the gas introduction channel 46. The through hole 26, the through hole 36, and the gas introduction channel 46 are arranged in series in the Z-axis direction, and together they form a channel for supplying an inert gas to the gas tunnel 42.

[0042] As described above, in the electrostatic chuck 1 of this embodiment, the semiconductor wafer W is attracted and held on the mounting surface 11 by the electrostatic attraction force generated by the chuck electrode 50. Then, an inert gas supplied from the outside (the lower surface 22 side of the base member 20) to the through holes 26 flows into the gas flow passage 40 in the plate-like member 10, is discharged to the mounting surface 11 through the plurality of gas discharge passages 44, and is filled into the minute spaces formed by the minute protrusions 70 between the mounting surface 11 (portions other than the minute protrusions 70) and the semiconductor wafer W.

[0043] Here, in the electrostatic chuck 1, there is a risk that particles will be generated due to the surface of the plate-like member 10 being finely scraped or the porous body 60 being locally damaged by friction between the mounting surface 11 (microscopic convex portions 70) and the semiconductor wafer W. Furthermore, since the porous body 60 is more brittle and more easily damaged than the plate-like member 10, there is a high risk that particles will be generated due to the porous body 60.

[0044] Therefore, in the electrostatic chuck 1 of this embodiment, an annular groove 16 is formed around the opening of the gas exhaust flow path 44, in which the porous body 60 is provided, so as to surround the entire periphery of the opening. This allows particles generated due to damage to the porous body 60, for example, to be moved onto the mounting surface 11 by the inert gas and collected in the groove 16. This makes it possible to prevent particles from adhering to the semiconductor wafer W.

[0045] In the electrostatic chuck 1 of this embodiment, the opening of the gas exhaust flow path 44 and the groove 16 are arranged on the bottom surface of the recess 14 provided in the mounting surface 11. Therefore, the inert gas exhausted from the gas exhaust flow path 44 can be spread (diffused) in the recess 14 and then applied to the semiconductor wafer W.

[0046] This allows particles originating from the porous body 60 to be efficiently collected by the grooves 16 in the recesses 14. Therefore, adhesion of particles to the semiconductor wafer W can be further suppressed.

[0047] Furthermore, it is possible to prevent the inert gas from locally hitting the semiconductor wafer W and cooling only that area, which makes it difficult for temperature singularities to occur on the semiconductor wafer W, thereby improving the uniformity of the temperature distribution on the semiconductor wafer W.

[0048] Furthermore, in the electrostatic chuck 1 of this embodiment, the surface roughness inside the grooves 16 is set to Ra 0.1 μm or more. Therefore, particles collected in the grooves 16 are less likely to be discharged from the grooves 16. This allows the grooves 16 to reliably capture particles, thereby effectively suppressing adhesion of particles to the semiconductor wafer W.

[0049] As described above, according to the electrostatic chuck 1 of the present embodiment, the annular groove 16 is formed so as to completely surround the opening of the gas exhaust flow path 44 provided with the porous body 60. Therefore, particles generated due to damage to the porous body 60 or the like can be moved onto the mounting surface 11 by the inert gas and collected in the groove 16, thereby preventing particles from adhering to the semiconductor wafer W.

[0050] [Second embodiment] Next, a second embodiment will be described. The second embodiment has the same basic configuration as the first embodiment, but differs from the first embodiment in that the recess 14 is not formed. Therefore, the same components as those in the first embodiment will be denoted by the same reference numerals and their description will be omitted as appropriate, and the description will focus on the differences from the first embodiment.

[0051] 8, no recess is formed in the mounting surface 11, and the opening of the gas exhaust flow path 44 and the groove 16 are provided in the mounting surface 11. Even with such an arrangement of the opening of the gas exhaust flow path 44 and the groove 16, similar to the first embodiment, particles can be collected by the groove 16, and therefore adhesion of particles to the semiconductor wafer W can be suppressed.

[0052] It should be noted that the above-described embodiments are merely examples and do not limit the present disclosure in any way, and various improvements and modifications are possible without departing from the spirit and scope of the present disclosure. For example, in the above-described embodiments, the present disclosure is applied to an electrostatic chuck, but the present disclosure is not limited to electrostatic chucks and can be applied to any holding device that holds an object on its surface.

[0053] In addition, in the above embodiment, a circular groove is exemplified as the groove 16, but the groove 16 is not limited to a circular shape and may be, for example, a square shape, as long as it is arranged so as to surround the entire periphery of the opening of the gas exhaust flow path 44 on the mounting surface 11 side. Furthermore, in the above embodiment, an example in which only one groove 16 is provided is shown, but two or more grooves 16 can also be provided (double or triple grooves). [Explanation of symbols]

[0054] 1. Electrostatic chuck 10 Plate-shaped member 11 Placement surface 14 Recess 16 groove 40 Gas passage 44 Gas exhaust flow path 60 Porous materials W Semiconductor wafer

Claims

1. a plate-like member having a placement surface on which an object to be held is placed; a plurality of gas holes formed in the plate-shaped member for supplying an inert gas to the mounting surface; In a holding device having the gas hole is formed to extend in a thickness direction of the plate-like member and has a porous body therein; a groove is formed around an opening of the gas hole on the placement surface side, a recessed portion that opens onto the mounting surface, The opening of the gas hole and the groove are disposed on the bottom surface of the recess. A holding device characterized by:

2. 2. The holding device according to claim 1, The groove is formed in a circular ring shape. A holding device characterized by:

3. The holding device according to claim 1 or 2, The surface roughness inside the groove is Ra 0.1 μm or more. A holding device characterized by:

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