Patent ID: 9543396
Date: 2017-01-10
CPC Classifications: H01L

Claim:
1. A vertical power transistor device comprising: a semiconductor layer of a first conductivity type; a plurality of cylindrically-shaped dielectric regions disposed in the semiconductor layer, each cylindrically-shaped dielectric region having an outer side that extends in a vertical direction from a top surface of the semiconductor layer downward, each cylindrically-shaped dielectric region having a circular cross-section in a horizontal plane perpendicular to the vertical direction, adjacent ones of the cylindrically-shaped dielectric regions being laterally separated along a common diametrical axis by a narrow region of the semiconductor layer having a first width; each cylindrically-shaped dielectric region having a cylindrical field plate member centrally disposed therein, 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 cylindrically-shaped dielectric region, the cylindrically-shaped 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 a ring-shaped gate member disposed in each cylindrically-shaped dielectric region between the narrow region and the cylindrical field plate member.