US Patent 7550803 Vertical double-diffusion metal-oxide-semiconductor transistor device

A vertical double-diffusion metal-oxide-semiconductor (VDMOS) transistor device includes a first conductive type semiconductor substrate, a gate structure formed in a first trench in the first conductive type semiconductor substrate, a first conductive type well surrounding the gate structure, a source region adjacent to the gate structure formed in the first conductive type well, a drain region surrounding the source region, and a trench isolation structure formed in a second trench between the source region and the drain region.