Patent ID: 7825465

Claim:
A trench-gate field effect transistor comprising: trenches extending into a silicon region of a first conductivity type; a gate electrode in each trench; body regions of second conductivity type extending over the silicon region between adjacent trenches, each body region forming a first PN junction with the silicon region, and each body region including a silicon-germanium layer of the second conductivity type laterally extending between adjacent trenches; a gate dielectric layer lining at least upper sidewalls of each trench, the gate dielectric layer insulating the gate electrode from the body region; source regions of the first conductivity flanking the trenches, each source region forming a second PN junction with one of the body regions; and channel regions extending in the body regions along sidewalls of the trenches between the source regions and a bottom surface of the body regions, wherein the silicon-germanium layers extend into corresponding channel regions to thereby reduce the channel resistance.