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Vertical transistor device structure with cylindrically-shaped field plates

  • US 10,325,988 B2
  • Filed: 12/13/2016
  • Issued: 06/18/2019
  • Est. Priority Date: 12/13/2013
  • Status: Active Grant
First Claim
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1. A vertical power transistor device comprising:

  • a semiconductor layer of a first conductivity type;

    a plurality of dielectric regions disposed in the semiconductor layer, each dielectric region having an outer side that extends in a vertical direction from a top surface of the semiconductor layer downward, each dielectric region having a rounded-square cross-section in a horizontal plane perpendicular to the vertical direction, adjacent ones of the dielectric regions being laterally separated by a narrow region of the semiconductor layer;

    a cylindrical field plate member centrally disposed within each dielectric region, the cylindrical field plate member having a circular cross-section in the horizontal plane and comprising a conductive material that fully extends laterally across a diameter of the circular cross-section of the cylindrical field plate member, the conductive material, extending in the vertical direction from the top surface downward to near a bottom of the dielectric region, the dielectric region laterally separating the cylindrical field plate member from the narrow region;

    a source region of the first conductivity type disposed at the top surface of the narrow region;

    a body region of a second conductivity type, the body region separating the source from a lower portion of the narrow region, the lower portion comprising a drift region;

    a drain region of the first conductivity type disposed beneath the semiconductor layer; and

    an annular gate member disposed in each dielectric region between the narrow region and the cylindrical field plate member.

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