Vertical GaN-based metal insulator semiconductor FET

A vertical III-nitride field effect transistor comprising:

• a drain comprising an n+ type material;
• a drain contact electrically coupled to the drain;
• a drift region comprising a second III-nitride material coupled to the drain and disposed adjacent to the drain along a vertical direction;
• a channel region comprising a third III-nitride material coupled to the drift region;
• a gate region coupled to the channel region;
• a gate contact electrically coupled to the gate region;
• a source coupled to the channel region;
• and
• a source contact electrically coupled to the source;
• wherein the channel region is disposed between the drain and the source along the vertical direction such that current flow during operation of the vertical III-nitride field effect transistor is along the vertical direction from the source to the drain via the drift region.

A method comprising:

• providing a III-nitride substrate having a top surface and an opposing bottom surface;
• forming a first III-nitride epitaxial layer over the top surface of the III-nitride substrate, wherein the first III-nitride epitaxial layer is characterized by a first conductivity;
• forming a second III-nitride epitaxial layer over the first III-nitride layer, wherein the second III-nitride epitaxial layer is characterized by a second conductivity opposite of the first conductivity;
• forming a third III-nitride epitaxial layer over the second III-nitride layer, wherein the third III-nitride epitaxial layer is characterized by a third conductivity;
• removing a portion of the third III-nitride epitaxial layer and the second III-nitride epitaxial layer to form a first trench extending through a thickness of the third III-nitride epitaxial layer and further protruding into the second III-nitride epitaxial layer;
• removing another portion of the third III-nitride epitaxial layer, the second III-nitride epitaxial layer, and a portion of the first III-nitride epitaxial layer to form a second trench extending through the thickness of the third III-nitride epitaxial layer, through a thickness of the second III-nitride material, and further protruding into the first III-nitride epitaxial layer;
• forming a dielectric layer over the third III-nitride epitaxial layer;
• forming a first metallic structure electrically coupled to the third III-nitride layer;
• forming a second metallic structure electrically coupled to the second III-nitride layer;
• and
• forming a metal structure overlying the dielectric layer, wherein the metal structure is electrically coupled to the third III-nitride layer via the first metallic structure and to the second III-nitride layer via the second metallic structure.