Semiconductor device and method of manufacturing semiconductor device

A semiconductor device comprising:

• a substrate;
• a first nitride semiconductor layer;
• a first insulating layer provided between the substrate and the first nitride semiconductor layer;
• a gate insulating layer provided between the first insulating layer and the first nitride semiconductor layer;
• a second nitride semiconductor layer provided between the gate insulating layer and the first nitride semiconductor layer, and being in contact with the first nitride semiconductor layer;
• a source electrode provided between the first insulating layer and the second nitride semiconductor layer, and electrically connected to the second nitride semiconductor layer;
• a gate electrode provided between the first insulating layer and the gate insulating layer;
• and
• a drain electrode provided between substrate and the second nitride semiconductor layer, and electrically connected to the second nitride semiconductor layer and substrate.

A method of manufacturing a semiconductor device comprising:

• laminating a buffer layer, a second nitride semiconductor layer, a first nitride semiconductor layer, and a gate insulating layer on a first substrate in this order;
• forming a gate electrode on the gate insulating layer;
• removing part of the gate insulating layer to expose the first nitride semiconductor layer,
• forming a source electrode on the first nitride semiconductor layer;
• forming a gate line connected to the gate electrode,
• forming an interlayer insulating layer covering the gate line, the gate electrode, and the gate insulating layer;
• bonding a junction insulating layer formed on a second substrate to the interlayer insulating layer,
• removing the first substrate and the buffer layer to expose the second nitride semiconductor layer, and forming a drain electrode on the second nitride semiconductor layer.