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Vertical trench misfet and method of manufacturing the same

  • US 5,981,996 A
  • Filed: 02/15/1996
  • Issued: 11/09/1999
  • Est. Priority Date: 02/17/1995
  • Status: Expired due to Term
First Claim
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1. A vertical trench MISFET comprising:

  • a semiconductor substrate having a first conductivity type semiconductor, and a second conductivity type impurity layer disposed on the first conductivity type semiconductor;

    a trench extending from a surface of said semiconductor substrate to reach said first conductivity type semiconductor;

    a second conductivity type base region formed in a top portion of said semiconductor substrate;

    a first conductivity type source region formed in a part of a surface layer of said second conductivity type base region;

    a first conductivity type drain drift region formed in a surface layer of a side wall of said trench, said first conductivity type drain drift region having a small thickness and first impurity concentration that is higher than a second impurity concentration at which a breakdown voltage measured in a hypothetical diffusion type junction is substantially equal to an element withstand voltage;

    a gate electrode formed on an exposed surface of said second conductivity type base region;

    a gate insulating film provided between said gate electrode and said second conductivity type base region;

    a source electrode disposed in contact with surfaces of both of said first conductivity type source region and said second conductivity type base region; and

    a drain electrode disposed in contact with a rear surface of said first conductivity type semiconductor.

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