Patent ID: 9000517
Filing Date: 2015-04-07
Classification: H01L

Abstract:
1. A power Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) comprising: a substrate; a first region extending from a top surface of the substrate into the substrate, wherein the first region is of a first conductivity type with a first impurity concentration; a gate dielectric over and in contact with the first region; a gate electrode over and in contact with the gate dielectric; a second region of the first conductivity type, formed within the first region at a first side of the gate electrode, wherein the second region has a second impurity concentration; a stepped drift region of a second conductivity type opposite to the first conductivity type, of a third impurity concentration, and within the first region, wherein the stepped drift region comprises a first part formed at a second side of the gate electrode, and a second part beneath the gate electrode, adjacent to the first part, with a depth less than a depth of the first part, wherein an edge of the first part adjacent to the second part is substantially aligned with an edge of the gate electrode; a source region of the second conductivity type within the second region; and a drain region of the second conductivity type within the first part of the stepped drift region.