Lateral thin film silicon-on-insulator (SOI) device with multiple doping profile slope in drift region

摘要

A lateral thin-film Silicon-On-Insulator (SOI) device includes a semiconductor substrate, a buried insulating layer on the substrate and a lateral MOS device on the buried insulating layer and having a source region of a first conductivity type formed in a body region of a second conductivity type opposite to that of the first. A lateral drift region of a first conductivity type is provided adjacent the body region, and a drain region of the first conductivity type is provided laterally spaced apart from the body region by the drift region. A gate electrode is provided over a part of the body region in which a channel region is formed during operation and over at least a part of the lateral drift region adjacent the body region, with the gate electrode being insulated from the body region and drift region by an insulation region. In order to provide an optimum combination of low "on" resistance and high breakdown voltage, the lateral drift region is provided with a graded lateral doping profile, with two substantially linearly graded drift region portions having different doping profile slopes. Specifically, the slope of the doping profile is higher in the portion of the lateral drift region adjacent the drain region than in the portion of the lateral drift region adjacent the body region.