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Self-aligned trench formation

  • US 8,101,497 B2
  • Filed: 09/11/2008
  • Issued: 01/24/2012
  • Est. Priority Date: 09/11/2008
  • Status: Active Grant
First Claim
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1. A method of forming a device, the method comprising:

  • forming a layer of polysilicon on a substrate;

    forming a first set of trenches in the substrate, wherein remaining portions of the polysilicon layer remain above the substrate in inter-trench regions between trenches of the first set;

    filling the first set of trenches with a filler material, wherein the filler material extends upward to at least a level adjacent the remaining portions of the polysilicon layer;

    selectively etching the remaining portions of the polysilicon layer from the inter-trench regions;

    forming spacers on sidewalls of the filler material in the inter-trench regions; and

    etching a second set of trenches into the substrate between the spacers.

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