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Method and apparatus for measurement of mobile charges with a corona screen gun

  • US 5,767,693 A
  • Filed: 09/04/1996
  • Issued: 06/16/1998
  • Est. Priority Date: 09/04/1996
  • Status: Expired due to Term
First Claim
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1. A method for measuring mobile charge in a dielectric layer on a heated semiconductor wafer, said method comprising:

  • applying corona charges having a first polarity to a surface of said layer until said surface has a potential at least as much as a first potential value;

    applying corona charges having an opposite polarity to said first polarity to said surface while contemporaneously repeatedly measuring a first parameter indicative of the quantity of said opposite polarity charges and contemporaneously measuring a second parameter indicative of said surface potential until said surface has a potential at least as much as a second potential value;

    applying corona charges having said first polarity to said surface while contemporaneously repeatedly measuring a third parameter indicative of the quantity of said first polarity charges and contemporaneously measuring a fourth parameter indicative of said surface potential until said surface has a potential at least as much as a third potential value; and

    determining said mobile charge from said measured parameters.

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