Patent ID: 9252280
Filing Date: 2016-02-02
CPC Classification: H01L

Claim Text:
1. A Metal Oxide Semiconductor Field Effect Transistor (MOSFET), comprising: a Semiconductor on Insulator (SOI) wafer, which comprises a semiconductor substrate, a buried insulating layer, and a semiconductor layer, the buried insulating layer being on the semiconductor substrate, and the semiconductor layer being on the buried insulating layer; a gate stack on the semiconductor layer; a source region and a drain region, which are in the semiconductor layer and on opposite sides of the gate stack; and a channel region, which is in the semiconductor layer and sandwiched by the source region and the drain region, wherein the MOSFET further comprises a back gate located in the semiconductor substrate, the back gate having a first doped region in a lower portion of the back gate with a first doping type, a second doped region in an upper portion of the back gate with the first doping type, and an anti-doped region below the channel region and in the second doped region with a second doping type, wherein the doping concentration of the second doped region of the back gate decreases gradually in a direction from either the source region or the drain region towards the center of the channel region, and wherein the anti-doped region has a doping concentration lower than a doping concentration of the second doped region of the back gate.