Patent ID: 8420483

Claim:
A process for making a transistor, comprising the actions, in any order except as specified below, of: in a semiconductor material, forming a source region having a first conductivity type, a body region having a second conductivity type, and a drift region having said second conductivity type, wherein said drift region has a lower doping density than said body region; forming at least one trench extending downward into said drift region of said semiconductor material; forming a dielectric layer on the inner surface of the trench; and thereafter introducing ions in said dielectric layer to produce a substantially stable density of ions in proximity to sidewalls of said trench, to thereby produce an intentionally introduced fixed net electrostatic charge; and thereafter substantially filling said trench with dielectric material, forming a recess in said trench, and forming a gate electrode in said recess which is capacitively coupled to said body region; wherein said introducing step provides a density of said ions, in proximity to said drift region in said semiconductor material, which inverts the surface of said drift region of said semiconductor material; wherein said introducing step also introduces ions into the bottom of said trench; wherein said ions are cesium ions; and wherein said semiconductor material is an epitaxial structure built on a substrate, and said trench extends into said epitaxial structure but not into said substrate.