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Multiple thickness of gate oxide

  • US 6,258,673 B1
  • Filed: 12/22/1999
  • Issued: 07/10/2001
  • Est. Priority Date: 12/22/1999
  • Status: Expired due to Fees
First Claim
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1. A method of forming an integrated circuit having a first, second and third set of active areas comprising the steps of:

  • preparing a silicon substrate;

    oxidizing said silicon substrate to form a first oxide having a first thickness;

    depositing a first blocking mask to leave said first set of active areas exposed;

    implanting said first set of active areas with a dose of growth-altering ions, whereby the thermal oxide growth rate in said first set of active areas is altered;

    stripping said first blocking mask;

    forming a second blocking mask to leave said first set of active areas and said second set of active areas exposed;

    stripping said first oxide in said first and second set of active areas;

    stripping said second blocking mask;

    oxidizing said substrate in a second oxidation step such that a standard oxide thickness is formed in said second set of active areas, whereby a first oxide thickness different from said standard oxide thickness is formed in said first set of active areas, and a third oxide thickness of greater than said standard oxide thickness is formed in said third set of active areas.

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