Patent ID: 7977198

Claim:
A method of manufacturing a semiconductor device comprising a field effect transistor, said method comprising: forming a substrate including the field effect transistor, the field effect transistor including a heterojunction, a gate electrode, a source electrode, and a drain electrode, said field effect transistor formed in a device formation region; forming a device separation region on a semiconductor substrate and spaced apart from the source electrode and drain electrode by forming a layer device separated by implantation of an ion into said semiconductor substrate, wherein the device separation region includes a layer with a conductive impurity introduced therein, and wherein the device separation region electrically isolates the device formation region upon which the field effect transistor is formed; and forming a substrate voltage applying electrode on a surface of at least a part of said device separation region and continuously surrounding a plurality of sides of the field effect transistor, the substrate voltage applying electrode spaced apart from and electrically separated from the source electrode and the drain electrode.