LATERAL THIN-FILM SOI DEVICE HAVING A LATERAL DRIFT REGION AND METHOD OF MAKING SUCH A DEVICE

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 transistor device in an SOI layer 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 forms a lightly-doped drain region, and a drain contact 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 extending over a part of the lateral drift region adjacent the body region, with the gate electrode being at least substantially insulated from the body region and drift region by a surface insulation region. In order to increase breakdown voltage and/or reduce "on" resistance, the lateral drift region is provided with at least a portion with a retrograde doping profile. This may advantageously be done by doping the semiconductor substrate, oxidizing the substrate to form the buried insulating layer, forming the SOI layer on the buried insulating layer, and thermally diffusing dopant from the buried insulating layer into the SOI layer.