Lateral junction field effect transistor device

Claim 1

A semiconductor device with a junction field effect transistor of the lateral JFET type, comprising a semiconductor substrate (11) of a first conductivity type and having a relatively light doping level, a first semiconductor layer (12) of a second conductivity type opposite to that of the first on said substrate and having a relatively light doping .level, source, gate, and drain contact regions (18, 17/19, 15/21) located at the surface of said first semiconductor layer, the gate region (17/19) being of the first conductivity type, more heavily doped than said substrate, and located between the source and the drain contact regions (18, 15/21) which latter regions are of the second conductivity type and more heavily doped than said first layer, means for electrically isolating the lateral JFET device from adjacent portions of said first semiconductor layer (12) and a buried semiconductor layer (13) of said second conductivity type located between said first layer (12) and said substrate (11) and forming a p-n isolation junction (14) with said substrate, characterized in that said buried semiconductor layer (13) of the second conductivity type has a doping level greater than that of said first semiconductor layer (12), said buried layer (13) extending beneath at least said drain contact region (15/21) and a surface semiconductor layer (16/20) of said first conductivity type, said surface layer being located at the surface of said first layer (12) and between said gate and said drain contact regions (17/19, 15/21), said surface layer (16/20) having a doping level on the same order of magnitude as that of said substrate (11).