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  Wafer chuckUSPTO Application #: 20060084371Title: Wafer chuck Abstract: The influence of the slurry generated when polishing an orientation notch and the like is minimized. The holding members 10, 20 for holding the outer periphery of the wafer W and the driving mechanism 30 for driving the holding members 10, 20 all together in the closing direction are integrally combined. (end of abstract)
Agent: Wenderoth, Lind & Ponack, L.L.P. - Washington, DC, US Inventors: Takashi Yoshida, Shinichi Murakami, Hiroyuki Itou USPTO Applicaton #: 20060084371 - Class: 451388000 (USPTO) Related Patent Categories: Abrading, Work Holder, Vacuum The Patent Description & Claims data below is from USPTO Patent Application 20060084371. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to wafer chucks suitably used particularly when polishing an orientation notch and the like of the outer periphery part of the semiconductor wafer. [0003] 2. Description of the Related Art [0004] The semiconductor wafer (hereinafter referred to simply as a wafer) has a V-shaped or a circular arc shaped orientation notch formed on the outer periphery. It is to be noted that the notch may be a linear orientation flat. [0005] When forming the orientation notch in the wafer, the polishing pad contacts the outer periphery of the wafer along a predetermined trajectory so as to create a predetermined angle, which wafer is normally attracted to and fixed to the vacuum chuck that uses vacuum, (e.g., Japanese Laid-Open Patent Publication No. 2-180554 and Japanese Laid-Open Patent Publication No. 2002-28840.). That is, a concentric or a radial groove communicating to the vacuum source is formed on the upper surface of the vacuum chuck, and the wafer is attracted and held at the upper surface of the vacuum chuck by operating the vacuum pump. [0006] On the other hand, after grinding, the orientation notch has the internal part polished to realize an accurate positioning of the wafer. Thus, a similar vacuum chuck is also normally used in polishing. SUMMARY OF THE INVENTION [0007] According to the conventional technique, when slurry (mixture of fluid polishing agent containing abrasive grain and powder polishing waste of the wafer) enters the lower surface side (attraction surface side) of the wafer, microscopic defects are unavoidably created at the wafer since the vacuum chuck attracts the wafer using vacuum. [0008] The present invention, in view of the problem of the conventional art, aims to provide a wafer chuck that suppresses the influence of the slurry produced when polishing the orientation notch and the like of the outer periphery part to minimum by arranging holding members for mechanically holding the outer periphery part of the wafer. [0009] The configuration of the present invention for achieving the above aim includes a plurality of holding members for pushing the outer periphery of the wafer in the radial direction and holding the wafer, and a driving mechanism for driving the holding members all together in the closing direction. It is to be noted that "closing direction" refers to the direction of moving each holding member forward towards the center of the wafer. [0010] Each holding member is configured so as to hold the wafer by way of an elastic member. [0011] Further, a V-shaped groove for sandwiching the outer peripheral part of the wafer in a snapping manner is formed in the elastic member, which V-shaped groove is further shaped into a circular arc shape so as to lie along the circumferential direction with respect to the outer peripheral edge of the wafer. [0012] Moreover, the elastic member further includes a guide groove having an apex angle greater than the apex angle of the V-shaped groove on the opening direction side of the V-shaped groove. [0013] The elastic member is configured from fluorocarbon resin or fluorocarbon rubber molded article. [0014] When the holding members are arranged on both sides in the radial direction of the wafer with the wafer in between, a cylinder arranged in the radial direction of the wafer and connected to one of the holding members, and an interlocking mechanism for operating the other holding member in conjunction with the operation of the former holding member are arranged as the driving mechanism. [0015] Further, as the driving mechanism, feed screws arranged in the radial direction of the wafer and having screw parts in the direction opposite to each other in order to screw each screw part to the holding member, and a motor for turning the feed screw may be arranged. [0016] When a machining tool forward/backward path that approaches the wafer at a position orthogonal to the wafer and machines the outer peripheral edge of the wafer is formed in one of the holding members arranged on both sides in the radial direction of the wafer, the holding member is capable of holding the part near the machining portion of the wafer. [0017] The present invention is suitable for polishing a V-notch or Orientation flat for defining the orientation of the wafer. [0018] According to the configuration of the present invention, the holding member is driving all together in the closing direction towards the center of the wafer by way of the driving mechanism to push the outer periphery of the wafer in the radial direction and mechanically hold the wafer. That is, in such state, since the wafer is held with both surfaces floating in the air, even if slurry produced when polishing the orientation notch or orientation flat of the outer peripheral part is attached, the slurry can be easily removed in the post-process of washing and the like, and thus does not cause defects on the wafer. When a plurality of holding members are driven parallel to the wafer all together by the same stroke towards the center of the wafer by way of the driving mechanism, each holding member applies the same pushing force parallel to both surfaces of the wafer towards the central part of the wafer in the thickness direction, thereby preventing localized distortion or curve of the wafer. [0019] Each holding member holds the wafer by way of the elastic member, and thus the pushing force is suitably dispersed and applied to the outer periphery of the wafer to minimize the localized distortion produced in the wafer. Further, the V-shaped groove formed in the elastic member sandwiches the outer peripheral part of wafer in a snapping manner and holds the wafer in a further stabilized manner. The guide groove formed in the opening direction of the V-shaped groove accurately guides the outer peripheral part of the wafer and allows the same to enter therein when the holding members are driven towards the center of the wafer. [0020] The chuck according to the present invention does not require a vacuum chuck for fixing the wafer, and thus is configured to be light as a whole, and the V-notch or Orientation flat is particularly suitable in an application of polishing the notch. When polishing the internal part of the V-notch or Orientation flat, the wafer tends to perform a complex and precise movement by way of the chuck, and thus if the chuck is light weight, the driving mechanism for moving the chuck can be simplified. BRIEF DESCRIPTION OF THE DRAWINGS [0021] The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: Continue reading... Full patent description for Wafer chuck Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Wafer chuck patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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