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Semiconductor slice prealignment system

  • US 4,024,944 A
  • Filed: 12/24/1975
  • Issued: 05/24/1977
  • Est. Priority Date: 12/24/1975
  • Status: Expired due to Term
First Claim
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1. A system for accurately aligning a generally circular wafer member having a flat region along a portion of its periphery comprising:

  • a. a turnable means mounted for rotation about a central axis perpendicular to its surface;

    b. conveyer means to deliver said wafer member gently to a position at rest on said turntable;

    c. a moveable stop member including an arcuate bumper member of resilient cushioning material, the arc of said bumper being of essentially the same radius as that of said wafer member and of a length greater than the arc of said wafer member subtended by said flat region of its periphery;

    d. means to move said stop member to various positions between and including a first position wherein the bottom edge of said bumper is in contact with said turntable and the center of the arc of said bumper member lies on said central perpendicular axis of said turntable and a second position in which said bumper member is sufficiently spaced from a wafer member centered on the axis of said turntable that rotation of said wafer member is not impeded by said bumper;

    e. means providing a fluid film to support said wafer member just above said turntable;

    f. means urging said wafer member into contact with said bumper member in said first position thereby centering said wafer for rotation;

    g. sensor means indicating when said wafer is centered about said perpendicular axis;

    h. means clamping said wafer to said turntable in said centered position;

    i. controllable means to rotate said turntable about said central axis;

    j. a sensor array mounted adjacent said turntable and having at least three sensors positioned to produce sensing areas in the plane of said wafer and along an arc of a circle having a radius co-linear with but larger than the radius of said wafer member and within a spacing no greater than the length of the flat region of said wafer periphery, the middle one of said sensing areas being nearest said perpendicular axis of said turntable;

    k. controllable means to produce relative movement between said sensing areas and a centered wafer member in a direction parallel to said co-linear radii; and

    l. means responsive to all of said sensor means to control operations of said means to move said stop member, said means providing a fluid film, said means urging said wafer, said means clamping said wafer, said control means to rotate and said controllable means to produce relative movement.

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