Abstract: An MOS transistor is fabricated which is especially suitable for use in the VHF and UHF regions, comprising a common source lateral MOSFET formed on a substrate, the substrate serving as the connection for the source to the header. The substrate, which is preferably P-type, has P-type and N-type epitaxial regions lying thereon and a sinker which forms a connection from source to substrate. The vertically isolated field effect transistor has a drain on top of a mesa on the N-type epitaxial region of the substrate, a gate in the contact region overhanging the edge of a channel formed adjacent to the mesa, and a source in the lateral edges of the groove defining the edge of the mesa.The process provides for simultaneous diffusion of the source and drain regions, followed by a metal masking step for connection of the diffused source which lies in the lateral edge of the groove to the sinker, effectively connecting the source to the substrate.