Texas Instruments Incorporated
Vertical trench gate MOSFET with deep well region for junction termination

Abstract:

A trench gate metal oxide semiconductor field effect transistor (MOSFET) device includes an epitaxial layer on a substrate both doped a first conductivity type. Active area trenches have polysilicon gates over a double shield field plate. A junction termination trench includes a single shield field plate in a junction termination area which encloses the active area that includes a retrograde dopant profile of the second conductivity type into the epitaxial layer in the junction termination area. Pbody regions of a second conductivity type are between active trenches and between the outermost active trench and the junction termination trench. Source regions of the first conductivity type are in the body regions between adjacent active trenches. Metal contacts are over contact apertures that extend through a pre-metal dielectric layer reaching the body region under the source region, the single shield field plate, and that couples together the polysilicon gates.