Compound Semiconductor Device with Buried Field Plate

A semiconductor device, comprising:

• a first III-V semiconductor material;
• a second III-V semiconductor material on the first III-V semiconductor material, the second III-V semiconductor material comprising a different material than the first III-V semiconductor material such that the first III-V semiconductor material has a two-dimensional electron gas (2DEG);
• a gate region on the second III-V semiconductor material with the second III-V semiconductor material interposed between the 2DEG and the gate region;
• a source region extending through the second III-V semiconductor material to the first III-V semiconductor material;
• a drain region extending through the second III-V semiconductor material to the first III-V semiconductor material and spaced apart from the source region;
• and
• a metallization on a side of the first III-V semiconductor material facing away from the second III-V semiconductor material, the first III-V semiconductor material having a thickness which increases in a direction extending laterally from the source region to the drain region.

A method of manufacturing a semiconductor device, comprising:

• forming a first compound semiconductor material on a semiconductor substrate;
• forming a second compound semiconductor material on the first compound semiconductor material, the second compound semiconductor material comprising a different material than the first compound semiconductor material such that the first compound semiconductor material has a two-dimensional electron gas (2DEG);
• forming a buried field plate in the first compound semiconductor material so that the 2DEG is interposed between the buried field plate and the second compound semiconductor material;
• and
• electrically connecting the buried field plate to a terminal of the semiconductor device.