×

Nitride cap sidewall oxide protection from BOE etch

  • US 5,364,804 A
  • Filed: 11/03/1993
  • Issued: 11/15/1994
  • Est. Priority Date: 11/03/1993
  • Status: Expired due to Term
First Claim
Patent Images

1. The method of forming a self-aligned contact to regions within a silicon substrate without lithography comprising:

  • providing a pattern of polysilicon gate electrode stack including a silicon oxide gate dielectric, a polysilicon gate electrode, a first thermal polyoxide layer over the top of said polysilicon gate electrode layer, a first silicon nitride layer over said first thermal polyoxide layer, and a silicon oxide layer over said silicon nitride layer, wherein each of said layers has its sides open to the ambient;

    implanting inert ions into said substrate which is not covered by said polysilicon gate electrode stack in such a manner as to reduce the possibility of the oxidation of the surface of said substrate;

    subjecting the said pattern of polysilicon gate electrode stack and said surface of said substrate to a thermal oxidizing ambient which causes oxidation of the said sides open to the ambient of said polysilicon layer to form a second polyoxide layer on the sides of said polysilicon layer;

    forming a second silicon nitride layer over said pattern of stack and said surface of said substrate;

    anisotropically etching said second silicon nitride layer to remove said second silicon nitride from the top of said stack and from over said surface of said substrate while leaving said second silicon nitride layer remaining upon said sides of said stack to form a self-aligned opening to regions within said silicon substrate; and

    forming said self-aligning contact to said regions through said opening.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×