Semiconductor device

A method of manufacturing a semiconductor device, comprising:

• providing a semiconductor substrate comprising a first semiconductor layer and a second semiconductor layer on the first semiconductor layer;
• depositing a first insulating layer over the second semiconductor layer;
• depositing a titanium nitride layer on the first insulating layer and reducing the nitrogen content in the titanium nitride layer as it is deposited, and depositing a titanium layer on the titanium nitride layer, without applying an external heating source to the substrate during the deposition of both the titanium nitride and titanium layers;
• pattern etching the titanium and titanium nitride layers to form a stacked electrode structure therefrom;
• and
• annealing the titanium nitride and titanium layers.

A nitride semiconductor device, comprising:

• a first nitride semiconductor layer;
• a second nitride semiconductor layer having a different nitrogen concentration than the first nitride semiconductor layer located over the first semiconductor layer;
• a source electrode in ohmic contact with the second nitride semiconductor layer;
• a drain electrode in ohmic contact with the second nitride semiconductor layer;
• a gate insulating layer on the second nitride semiconductor layer and located between the source and the drain electrodes;
• and
• a gate electrode comprising titanium nitride disposed on the gate insulating layer and a titanium layer located on the titanium nitride layer on a side thereof opposite to the location of the gate insulating layer, wherein the nitrogen content of the titanium nitride layer is greater adjacent to the gate insulating layer than adjacent to the titanium layer.