Patent ID: 7157748

Claim:
A nitride-based semiconductor device comprising: a first semiconductor layer consisting essentially of a nitride-based semiconductor; a second semiconductor layer disposed on the first semiconductor layer and consisting essentially of a non-doped or first conductivity type nitride-based semiconductor, the first and second semiconductor layers forming a hetero-interface; a gate electrode disposed on the second semiconductor layer; first and second trenches formed in a surface of the second semiconductor layer at positions sandwiching the gate electrode; third and fourth semiconductor layers of the first conductivity type respectively formed in surfaces of the first and second trenches and each consisting essentially of a diffusion layer having a resistivity lower than the first and second semiconductor layers; a source electrode electrically connected to the third semiconductor layer; a drain electrode electrically connected to the fourth semiconductor layer and an insulating layer interposed between a side of at least one electrode of the source electrode and the drain electrode and an inner surface of at least one trench of the first and second trenches, in which said at least one electrode is disposed.