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Contactless electrical thin oxide measurements

  • US 5,485,091 A
  • Filed: 05/12/1995
  • Issued: 01/16/1996
  • Est. Priority Date: 05/12/1995
  • Status: Expired due to Term
First Claim
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1. In a method for measuring the thickness of an insulating layer on a semiconductor substrate, the steps comprising:

  • repetitively depositing a fixed charge density on the surface of said layer,measuring the resultant changes in the surface potential of said layer relative to the bulk of said substrate,establishing a theoretical bandbending versus bias characteristic for said layer and substrate, undergoing said repetitive deposition of charge density, for an assumed value of said thickness,determining an experimental bandbending versus bias characteristic using said measured change in the insulating layer surface potential for each said deposited charge, and said assumed value of thickness,comparing said theoretical and said experimental characteristics to ascertain any difference in the accumulation region of said characteristics, anditeratively incrementing said assumed value while using said measured changes in said surface potential to determine corresponding experimental bandbending versus bias characteristics andcomparing each said corresponding characteristic with said theoretical characteristic until one of said corresponding characteristics matches said theoretical characteristic in the substrate accumulation region of said characteristics.

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