Patent ID: 8581341
Filing Date: 2013-11-12
Classification: H01L

Abstract:
1. A power semiconductor device, comprising: a semiconductor source region, which is heavily doped with a first conductivity type; a semiconductor body region, which has a second conductivity type and is located at least partially beneath said source region; a first trench which extends through said source and body regions, and includes at least one gate electrode which is capacitively coupled to at least part of said body region; and a second trench which is at least as deep as said first trench, and which contains a field plate covered by an insulator, said second trench extending down through the body region into a first-conductivity-type semiconductor drift region which is more lightly doped than the source region; a recessed metallic source contact overlying said field plate, but separated therefrom at active device locations by said insulator, and making ohmic contact to said source region; wherein, at said active device locations, the top of said field plate is deeper than the top of said gate electrode, and the bottom of said field plate is deeper than the bottom of said gate electrode; whereby said gate electrode can invert at least part of the body region to permit passage of majority carriers from the source region through the inverted part of the body region into the drift region, and the majority carriers can pass through the drift region into a first-conductivity-type drain region; wherein said body region has a lower surface which is not planar; and further comprising an additional population of first-conductivity-type dopants surrounding downwardly extending parts of said lower surface.