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Method of fabricating trench MIS device with graduated gate oxide layer

  • US 6,875,657 B2
  • Filed: 03/26/2002
  • Issued: 04/05/2005
  • Est. Priority Date: 08/10/2001
  • Status: Expired due to Term
First Claim
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1. A method of fabricating an MIS device comprising:

  • providing a semiconductor substrate;

    forming a trench in said substrate;

    depositing a nitride layer in said trench;

    etching said nitride layer to form an exposed area at a bottom of said trench;

    said etching exposing a lateral surface of said nitride layer on each side of said exposed area;

    heating the substrate and thereby growing an oxide layer in said exposed area, said oxide layer abutting said lateral surface of said nitride layer on each side of said exposed area;

    removing said nitride layer;

    forming a relatively thin gate oxide layer on at least a portion of a sidewall of said trench; and

    forming a gate in said trench.

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