Patent ID: 7868394
Filing Date: 2011-01-11
Classification: H01L

Abstract:
1. A metal-oxide-semiconductor (MOS) transistor, comprising: a substrate; a buried layer of a heavily doped first conductivity type on the substrate; a covering layer of the first conductivity type lying on the buried layer and connecting to the buried layer electrically; a body region of a second conductivity type in the covering layer; a source region comprising a first semiconductor region of the first conductivity type within the body region; a drain region comprising a second semiconductor region in a form of a trench filled with a semiconductor material of the first conductivity type adjacent to the body region, wherein, the trench has a bottom surface and side surfaces and extends vertically downward from a top surface of the covering layer into the buried layer, the bottom surface of the trench lies in the buried layer, an insulating layer lines the side surfaces of the trench entirely, the insulating layer contacts the covering layer, the semiconductor material within the trench overlies the insulating layer and contacts the buried layer at the bottom surface of the trench, and a shallow trench isolation covers the semiconductor material; a gate dielectric layer disposed on the body region, the covering layer, the shallow trench isolation and the insulating layer; and a gate electrode on the gate dielectric layer.