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Contactless technique for semicondutor wafer testing

  • US 4,812,756 A
  • Filed: 08/26/1987
  • Issued: 03/14/1989
  • Est. Priority Date: 08/26/1987
  • Status: Expired due to Fees
First Claim
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1. A contactless measurement method for testing a doped wafer with an insulator layer disposed thereover, comprising the steps of:

  • depositing charges on the top surface of said insulator layer to create an inverted surface with a depletion region and thereby a field-induced junction in the wafer therebelow with an accumulated guard ring on the wafer surface;

    changing the depth to which said depletion region extends below said inverted wafer surface to create a surface potential transition, andmeasuring a parameter of the resultant surface potential transient between the top surface of said insulator layer and the bulk of said wafer.

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