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Wafer position error detection and correction system

  • US 5,980,194 A
  • Filed: 07/15/1996
  • Issued: 11/09/1999
  • Est. Priority Date: 07/15/1996
  • Status: Expired due to Term
First Claim
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1. A wafer position error detection system comprising:

  • a wafer handling chamber having a vacuum sealable opening for admitting wafers from a region external to the wafer handling chamber;

    at least one wafer holding chamber disposed adjacent to the wafer handling chamber, the wafer holding chamber having an opening large enough to admit a wafer, the wafer holding chamber including a valve for closing the opening;

    a wafer transport robot capable of translating a wafer along a first coordinate direction and along a second coordinate direction, the wafer transport robot having a blade adapted for carrying wafers, wherein the blade defines a slot;

    at least one detection sensor disposed to detect an edge of the slot and an edge of the wafer as the wafer is retracted from or placed into the wafer holding chamber;

    a controller device responsive to the detection sensor, wherein the controller device identifies the distance between the edge of the slot and the edge of the wafer on the blade as the wafer transport robot is translated along the first coordinate direction, and detects as a function of said identified distance a condition in which a wafer disposed on the wafer transport robot blade is displaced.

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