SOS MOSFET With self-aligned channel contact

Claim 1

A MOS type semiconductor device comprising: an insulating substrate; a substrate region of one conductivity type provided on said insulating substrate, said substrate region positioned under a channel region, and said substrate region having an extended substrate portion extending in the channel length, which is the direction of current flow, away from said channel region; a source region of an opposite conductivity type which is provided in said insulating substrate, contacting one side surface of said substrate region under said channel region; a drain region of the opposite conductivity type which is provided on said insulating substrate, contacting the other side surface of said substrate region under said channel region, the pair of said source and drain regions being separately formed sandwiching said substrate region under the channel region and said extended substrate portion extending to one of said source and drain regions; a gate insulating film provided on said substrate region; a gate electrode provided on said gate insulating film so as to cover said substrate region, said gate electrode having an extended gate portion corresponding to said extended substrate portion of said substrate region; and a substrate potential takeout region of one conductivity type which is provided on said insulating substrate and is connected to said extended substrate portion of said substrate region, whereby potential may be applied to said substrate region under the channel region through said substrate potential take-out region.