Existing semiconductor transistor processes may be leveraged to form lateral extensions adjacent to a conventional gate structure. The dielectric thickness under these lateral gate extensions can be varied to tune RF switch FET device performance and enable resistance to breakdown at high operating voltages. These extensions may be patterned with dimensions that are not limited by lithographic resolution and overlay capabilities and are compatible with conventional processing for ease of integration with other devices. The lateral extensions and dielectric spacers may be used to form self-aligned source, drain, and channel regions. A thick dielectric layer may be formed under a narrow extension gate to improve operation voltage range. The present invention provides an innovative structure with lateral gate extensions which may be referred to as EGMOS (extended gate metal oxide semiconductor).