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Apparatus and method for thick wafer measurement

  • US 5,386,119 A
  • Filed: 03/25/1993
  • Issued: 01/31/1995
  • Est. Priority Date: 03/25/1993
  • Status: Expired due to Term
First Claim
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1. A method for determining thickness of a semiconductor layer, comprising the steps of:

  • combining an input light image of an infrared source with an output reflected light image of the source from the semiconductor layer which input and output light images traverse a variable length image path; and

    detecting, for each of a plurality of areas of a surface of the semiconductor, a signal burst in the combined input and output light images at a discrete length in the variable length image path corresponding to the thickness of the semiconductor layer.

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