Method for STI-top rounding control

  • US 6,225,187 B1
  • Filed: 04/01/1999
  • Issued: 05/01/2001
  • Est. Priority Date: 02/12/1999
  • Status: Expired due to Term
First Claim
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1. A method for STI top-rounding control, the steps comprising:

  • (a) providing a semiconductor substrate;

    (b) forming an oxide layer on the substrate;

    (c) forming a hard mask on the oxide layer;

    (d) forming a photoresist pattern with an opening exposing the hard mask at a predetermined STI trench region on the hard mask;

    (e) etching the exposed hard mask and the underlying oxide layer within the opening in sequence, and continuously over-etching to remove part of the semiconductor substrate to form a window lower than the surface of the oxide layer wherein corners of the window are round; and

    (f) using the photoresist pattern and the hard mask as an etching mask, removing part of the exposed semiconductor substrate within the window to form an STI trench.

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