SOS transistor structure

Claim 1

A MOS transistor formed in a semiconductor layer, and arranged on an insulating base, comprising: a channel region of a first conduction type having a more heavily doped part adjacent to the base and a more weakly doped part extending to the surface of the semiconductor layer; source and drain regions of a second conduction type contiguous to opposite edges of, and separated by, the weakly doped part of the channel region; a source contact being connected to the source region; a drain contact being connected to the drain region; a control electrode being arranged on top of said more weakly doped part of the channel region and separated therefrom by an insulating layer; said channel region and said control electrode extending to opposite edges of said semiconductor layer; wherein said more heavily doped part of the channel region extends under the source region, completely separating the source region from the base; a second region of said first conduction type being arranged contiguous (a) to the source region, (b) to said more heavily doped part of the channel region, and (c) to the surface of the semiconductor layer, said second region and said more heavily doped part of the channel region completely separating the source region from said base and from the edges of the semiconductor layer.