Vertical mosfet with diminished bipolar effects

Abstract

An IGFET device includes a semiconductor wafer having a first conductivity type drain region contiguous with a wafer surface. A second conductivity type body region extends into the wafer from the wafer surface so as to form a body/drain PN junction having an intercept at the surface; the body region further including a body-contact portion of relatively high conductivity disposed at the surface. A first conductivity type source region extends into the wafer so as to form a source/body PN junction which has first and second intercepts at the surface. The first intercept is spaced from the body/drain intercept so as to define a channel region in the body region at the surface, and the second intercept is contiguous with the body contact portion. The second intercept is relatively narrowly spaced from the first intercept along most of the length of the first intercept and is relatively widely spaced from the first intercept at one or more predetermined portions. A source electrode contacts the body-contact portion and the source region on the wafer surface.