Patent ID: 7332771

Claim:
A vertical power transistor trench-gate semiconductor device comprising a semiconductor body having an active area with a plurality of electrically parallel transistor cells, wherein trench-gates in the active area each comprise a trench extending into the semiconductor body with gate material in the trench, wherein the transistor cells have source and drain regions or a first conductivity type which are separated by a channel-accommodating region of a second, opposite, conductivity type adjacent a trench-gate, wherein ruggedness regions are provided which are localised regions of the second conductivity type but which are more heavily doped than the channel-accommodating regions and which extend into the drain region, wherein the trench-gates are parallel stripes which each extend across the active area, wherein the source regions and the ruggedness regions extend to a source contact surface of the semiconductor body as alternating stripe areas having a width perpendicular to and fully between each of two adjacent parallel stripe trench-gates, and wherein the device is characterized by the ruggedness regions being more heavily doped than the source regions.