Patent ID: 7576388

Claim:
A field effect transistor comprising: a first silicon region comprising a body region having a first conductivity type, the first silicon region having a top surface; a gate-trench region extending from the top surface of the first silicon region into the first silicon region, wherein the gate-trench region has a first sidewall, a bottom, and a second sidewall, the gate-trench region comprising: a source-shield region comprising a first conductive region; a gate region comprising a second conductive region, the gate region located between the top surface of the first silicon region and the source-shield region; a first insulating layer between the gate region and the first sidewall; and a second insulating layer between the gate region and the second sidewall, the second insulating layer being thicker than the first insulating layer; a highly-doped drain region of a second conductivity type at the top surface of the first silicon region and contacting a drain electrode, the highly-doped drain region being laterally spaced from the gate-trench region, the second conductivity type being opposite to the first conductivity type; a lightly-doped drain region of the second conductivity type in the first silicon region, the lightly-doped drain region laterally extending along the top surface of the first silicon region between the second sidewall of the gate-trench region and the highly-doped drain region, and further extending under the bottom of the gate-trench region; wherein a portion of the lightly-doped drain region laterally extending along the top surface of the first silicon region extends to a depth shallower than a bottom of the gate-trench region; and a source region at the top surface of the first silicon region, the source region comprising a dopant region of the second conductivity type extending along the first sidewall of the gate-trench region.