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Semiconductor device that uses a transistor for field shield

  • US 8,395,198 B2
  • Filed: 07/15/2011
  • Issued: 03/12/2013
  • Est. Priority Date: 07/15/2010
  • Status: Expired due to Fees
First Claim
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1. A semiconductor device comprising:

  • a semiconductor substrate including first, second and third portions;

    the first and second portions being partitioned by a cell gate trench having a bottom surface, a first side surface located on the first portion side, and a second side surface located on the second portion side,the first and third portions being partitioned by a first field-shield gate trench exposing a third side surface located on the first portion side and a fourth side surface located on the third portion side, anda distance between the third and fourth surfaces being narrower than a distance between the first and second surfaces,a first upper diffusion layer that is provided on an upper part of the first portion of the semiconductor substrate;

    a second upper diffusion layer that is provided on an upper part of the second portion of the semiconductor substrate;

    a third upper diffusion layer that is provided on an upper part of the third portion of the semiconductor substrate;

    a lower diffusion layer that is provided in the bottom surface of the cell gate trench;

    a first and a second storage element that are electrically connected to the first and second upper diffusion layers, respectively;

    a bit line that is electrically connected to the lower diffusion layer;

    a first and a second cell gate electrode that cover the first and second side surfaces, respectively, via a gate insulating film; and

    a first field-shield gate electrode that is embedded in the first field-shield gate trench via a gate insulating film.

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