Patent ID: 7511339
Filing Date: 2009-03-31
Classification: H01L

Abstract:
1. A field effect transistor comprising: a semiconductor substrate having dopants of a first conductivity type; a trench extending a predetermined depth into the semiconductor substrate, wherein a gate structure is formed inside the trench; a doped well having dopants of a second conductivity type opposite to the first conductivity type and extending into the semiconductor substrate to form a well junction at a first depth; a doped source region having dopants of the first conductivity type and extending into the semiconductor substrate to form a source junction at a second depth; and a doped heavy body region having dopants of the second conductivity type and extending into the doped well to form a heavy body junction at a depth that is deeper than the source junction and shallower than the trench, wherein the heavy body region forms an abrupt junction at the interface between the heavy body region having dopants of the second conductivity type and the doped well having dopants of the second conductivity type, such that, when voltage is applied to the transistor, a peak electric filed occurs near the area of the interface.