JP4445318B2 - Vacuum chuck for wafer - Google Patents

Description

  The present invention relates to a wafer chuck that can safely suck and hold a semiconductor wafer.

  In order to hold a semiconductor wafer and, for example, polish a peripheral portion, a suction chuck using a vacuum is used.

Conventional suction chucks have a radial concave groove on a circular suction surface, and each concave groove communicates with a vacuum source through a central connection hole, and a concentric suction pad is radially arranged with respect to the suction surface. (Patent Document 1). In some cases, a seal packing is attached to the outermost periphery of the suction surface (Patent Document 2).
JP-A-6-246609 Japanese Utility Model Publication No. 7-31245

  According to the former of the prior art (Patent Document 1), since the radial concave grooves communicate with each other in the circumferential direction of the suction surface through a gap existing between concentric suction pads, the wafer is bent. If a partial gap is generated between the suction pad and the suction pad, the entire vacuum is easily broken and the wafer may fall off the suction surface. In the latter case (Patent Document 2), it is possible to prevent the workpiece from falling off, but the presence of the packing tends to cause excessive adsorption force on the wafer, resulting in damage or damage to the wafer. It is inevitable to stick.

  Therefore, in view of the problems of the prior art, the object of the present invention is to devise the shape of the suction pad attached to the suction surface and to form the outer peripheral portion of the suction surface via a flexible outer flange. An object of the present invention is to provide a suction chuck for a wafer capable of safely sucking and holding the wafer.

  To achieve this object, the structure of the present invention includes a main body having a circular suction surface, a flexible outer flange that forms an outer peripheral portion of the suction surface and expands the suction surface, and an attachment to the suction surface. And a suction surface including the outer flange and a circular suction pad having the same diameter, and the suction surface is formed with a radial concave groove communicating with a vacuum source through a central connection hole. Forms multiple concentric openings in the radial direction, and each opening is separated at the same circumferential position with a central angle corresponding to the relative angle of each groove, and for each sector part including each groove The main point is to divide the suction surface into independent areas.

  Each concave groove can extend to the outer peripheral portion of the main body without the tip reaching the inner periphery of the outer flange.

  Moreover, the opening part on the outermost peripheral side may be formed in the outer peripheral part of the suction surface by the outer flange, or may be communicated with another opening part adjacent to the inside and reaching the tip of the groove.

  According to the configuration of the invention, the concentric openings of the suction pad are partitioned at the same circumferential position with a central angle corresponding to the relative angle of each concave groove. Therefore, the suction surface constitutes an independent area for each fan-shaped part including each concave groove through the partitioning part of the opening, and even if the vacuum breaks in a specific area, the effect on other areas It is possible to hold the wafer safely without spilling over.

  If a flexible outer flange is provided on the main body, the outer peripheral portion of the suction surface is formed by the outer flange. That is, even if an external force for processing is applied to the outer periphery of the wafer that is attracted to the attracting surface and the wafer is bent, the outer peripheral portion of the attracting surface by the outer flange follows the wafer. There is no possibility of creating a gap and thereby breaking the vacuum, and the wafer can be held more stably. The outer flange is set to have a flexure strength of about 0.2 to 0.5 mm when the external force of 10 kg as a whole is applied to the outer circumference of 200 to 300 mm in the axial direction of the main body. It is preferable to do. If the bending strength is excessive, the amount of bending is insufficient and it is meaningless to provide the outer flange on the main body. If the bending strength is insufficient, the bending amount becomes excessive and the wafer being processed may be damaged.

  If the outermost peripheral opening communicates with the opening adjacent to the inner side, the groove on the suction surface only needs to reach the latter opening. Therefore, even when a thin outer flange is provided, the groove and the outer flange are provided. And the degree of freedom of design can be improved. Further, if the suction pad has a circular shape with the same diameter as the suction surface, the entire area of the suction surface can be effectively used to suck the wafer. However, the diameter of the suction surface is set somewhat smaller than the wafer to be suctioned.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The wafer chuck is formed by forming a circular suction surface 11 on the lower surface of the main body 10 and attaching a suction pad 21 to the suction surface 11 (FIGS. 1 and 2). However, FIG. 1 is a bottom view of the main body 10.

  The main body 10 is formed as a circular shade-shaped block body of, for example, polyaster resin. A connecting hole 12 connected to a vacuum source (not shown) passes vertically in the center of the main body 10, and stepped bolt holes 13, 13... Are formed upward around the connecting hole 12. Has been. A flexible outer flange 14 is formed on the outer periphery of the lower end of the main body 10, and the outer flange 14 forms an outer peripheral portion of the suction surface 11 and enlarges the suction surface 11.

  On the suction surface 11, radial concave grooves 15, 15... Are formed. Each concave groove 15 has a base end that opens to the connecting hole 12, and a distal end that extends to the outer peripheral portion of the main body 10 so as not to reach the inner periphery of the outer flange 14.

  The suction pad 21 has a circular shape with the same diameter as the suction surface 11, the outermost peripheral portion is continuous in a circular shape, and concentric openings 21 a, 21 a... Are formed in multiple directions in the radial direction of the suction surface 11. Each opening 21 a is partitioned at the same position in the circumferential direction of the suction surface 11 with a central angle β corresponding to the relative angle α of each concave groove 15. That is, the openings 21a, 21a,... On the same circumference are divided into the same number as the number of the concave grooves 15, 15.. The outermost peripheral opening 21a communicates with another opening 21a adjacent to the inner side through a notch 21b in the middle in the circumferential direction. Further, the central portion of the suction pad 21 covers the entire suction surface 11 except for the connection hole 12 and the bolt holes 13, 13. The openings 21a, 21a,... Of the suction pad 21 divide the suction surface 11 into independent areas in units of fan-shaped portions within the central angle β including the concave grooves 15, and all the openings 21a, 21a,. Is communicated with the concave groove 15 in the area. However, the suction pad 21 has a relative relationship with the suction surface 11 such that the relative angle α and the central angle β≈α overlap each other by about half.

  The suction pad 21 is a thin non-woven fabric, and is adhered to the suction surface 11 via, for example, a double-sided adhesive tape 21c (FIG. 3). However, FIGS. 3A and 3B are an enlarged view of a main part of FIG. 2 and an enlarged sectional view taken along line YY of FIG. A step 14 a is formed on the outer peripheral portion of the lower surface of the outer flange 14 of the main body 10 (FIG. 3B). The step 14 a is a total thickness of the suction pad 21 and the double-sided adhesive tape 21 c with respect to the suction surface 11. The height of the suction pad 21 is approximately the same as that of the outermost peripheral portion of the suction pad 21. In addition, you may replace the double-sided adhesive tape 21c with a suitable adhesive or an adhesive agent.

  The wafer chuck can stably hold and hold the wafer W on the suction surface 11 via the suction pad 21 by connecting the connecting hole 12 to a vacuum source (FIGS. 2 and 4). However, in FIG. 4, a hollow shaft 41 with a seal 41d is connected to the connecting hole 12, and the hollow shaft 41 is connected to a vacuum source (not shown). Moreover, the main body 10 is attached to the flange 41a fixed to the hollow shaft 41 via the nut 41b downward via attachment bolts 41c, 41c. The wafer W has a disk shape that is somewhat larger in diameter than the outer diameter of the suction surface 11 including the outer flange 14, and the polishing pad 46 on the inner surface of the fixing member 42 that opens downward by rotating the hollow shaft 41. The peripheral edge can be slid evenly and the peripheral edge can be polished smoothly. On the inner surface of the fixing member 42, a concave spherical surface portion K2 is formed in a band shape between the linear portions K1 and K1, and the outer periphery of the wafer W slightly forms a hollow shaft 41 with respect to the axial center of the spherical surface portion K2. By tilting, it is assumed that the entire circumference is in slidable contact with the substantially entire surface of the polishing pad 46 of the spherical surface portion K2.

  The fixing member 42 is screwed to the lower surface of the outer flange of the cover 44 via a ring-shaped spacer 43, and the cover 44 is screwed to the lower end of a cylindrical frame member 45 that houses the hollow shaft 41 on the central axis. Has been. The cover 44 is screwed to the frame member 45 via bolts 44a, 44a ..., the fixing member 42 is screwed to the spacer 43 via bolts 42a, 42a ..., and the spacer 43 is bolts 43a, 43a ... Are screwed to the outer flange of the cover 44 via. However, in FIG. 4, only two bolts 44a, 43a, and 42a are shown, respectively.

  When polishing the peripheral edge of the wafer W, an appropriate processing force is applied upward via the hollow shaft 41 (in the direction of the arrow in FIG. 4). At this time, even if the outer peripheral portion of the wafer W is bent, the outer flange 14 forming the outer peripheral portion of the suction surface 11 is bent and bent, and the openings 21a, 21a. Since the groove 15 is divided into independent areas, there is no possibility that the wafer W will inadvertently fall off the suction surface 11. Further, the step 14 a on the lower surface of the outer flange 14 improves the sealing performance between the wafer W and the suction surface 11.

  In the above description, the number of the radial concave grooves 15, 15... Of the suction surface 11 and the number of the radial direction of the openings 21 a of the suction pad 21 can be arbitrarily changed. However, the circumferential division of the openings 21a, 21a,... Corresponds to the number of the concave grooves 15, 15.. The present invention is not limited to the polishing process of the peripheral edge of the wafer W as shown in FIG. 4, but can be suitably used for other processing processes and transfer processes of the wafer W. Further, in the use state, the suction surface 11 can take any posture other than downward.

Overall bottom view Overall longitudinal section Explanatory drawing of enlarged cross section Usage diagram

Explanation of symbols

α ... Relative angle β ... Center angle 10 ... Main body 11 ... Suction surface 12 ... Connecting hole 14 ... Outer flange 15 ... Groove 21 ... Suction pad 21a ... Opening

Patent Applicant BB Kinmei Co., Ltd.
Attorney Tadaaki Matsuda, Attorney

Claims (4)

Have a circular suction surface, a body which have a flexible outer flange to expand the suction surface forms the outer peripheral portion of the suction surface, and attached to the suction surface, the suction that includes the outer flange A circular suction pad having the same diameter as the surface, and a radial concave groove communicating with a vacuum source through a central connection hole is formed in the suction surface, and the suction pad has a concentric circular shape. multiply-formed openings in the radial direction, each of the openings, the delimiter at the same position in the circumferential direction at a central angle of the relative angle corresponds in each groove, each sector portion including the respective grooves A suction chuck for a wafer, wherein the suction surface is divided into independent areas . Each groove without tip reaches the inner periphery of the outer flange, vacuum chuck for the wafer according to claim 1, wherein Rukoto extend to the outer periphery of the main body. 3. The wafer chuck according to claim 1, wherein the outermost peripheral opening is formed in an outer peripheral portion of the suction surface by the outer flange . The opening of the outermost side, suction chuck for wafers to that請 Motomeko 3 Symbol mounting, characterized in that communicating with another of the opening that reaches the tip of the groove adjacent to the inside.

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