Patent ID: 8551821

Claim:
A method of manufacturing a normally off nitride semiconductor device, comprising the steps of: forming a buffer layer on a substrate; forming a first nitride semiconductor layer on the buffer layer; patterning a source/drain region; patterning a masking barrier made of SiO 2 in a gate region from above the first nitride semiconductor layer; forming a hetero junction layer below the source/drain region by forming a second nitride semiconductor layer having a band gap different from that of the first nitride semiconductor layer, the masking barrier interposed between the source region and the drain region; removing the masking barrier; forming an insulating film on the second nitride semiconductor layer and a layer where the masking barrier is removed; patterning the source/drain region, etching the insulating film in the source/drain region, and forming electrodes in the source/drain region; and forming a gate electrode on the insulating film in the gate region.