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Apparatus for optical inspection of wafers during polishing

  • US 6,045,433 A
  • Filed: 06/29/1995
  • Issued: 04/04/2000
  • Est. Priority Date: 05/23/1995
  • Status: Expired due to Term
First Claim
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1. A thickness measuring unit for mounting on a water track of a polisher for measuring the thickness of a top layer of a wafer, said thickness measuring unit comprising:

  • a. a curved gate having a radius of curvature generally similar to that of said wafer, said curved gate being located at a gripping position;

    b. a window mounted in a bottom surface of said water track;

    c. a gripper for moving said wafer from said gripping position to a measuring position above a layer of water located above said window, said gripper including a gripping pad, having a planar surface wherein said planar surface of said gripping pad is at an angle to a horizontal plane; and

    d. an optical system, mounted underneath said window, for measuring said thickness of said top layer through said window and said layer of water.

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