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Process to control etch profiles in dual-implanted silicon films

  • US 6,605,543 B1
  • Filed: 12/30/1999
  • Issued: 08/12/2003
  • Est. Priority Date: 12/30/1999
  • Status: Expired due to Fees
First Claim
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1. A method for selectively etching a gate stack having a silicon layer covering a thin oxide layer which covers a substrate, the silicon layer having an anti-reflective coating layer thereon comprising:

  • etching through the anti-reflective coating layer of the gate stack, with a first process gas having a fluorine-based chemistry, until the silicon layer is exposed;

    etching the silicon layer of the gate stack with a second process gas including a mixture of HBr, Cl2, and CF4;

    etching the gate stack with a third process gas including a mixture of HBr,Cl2 and 80% He—

    O2 until the thin oxide is exposed; and

    over etching the gate stack with a fourth process gas including a mixture of HBr, 80% He—

    O2 and He.

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