Semiconductor device

A semiconductor device comprising:

• a semiconductor substrate of a first conductivity type;
• a low voltage region provided on an upper surface side of the semiconductor substrate;
• a high voltage region provided on the upper surface side of the semiconductor substrate;
• a RESURF region of a second conductivity type provided on the upper surface side of the semiconductor substrate and separating the low voltage region and the high voltage region;
• a source electrode electrically connected to the low voltage region;
• a drain electrode electrically connected to the high voltage region;
• a gate electrode connected to the upper surface of the semiconductor substrate via a gate oxide film between the low voltage region and the high voltage region;
• an oxide film provided on an upper surface of the RESURF region;
• and
• a first field plate provided on an upper surface of the oxide film, wherein
• the oxide film includes a first portion and a second portion that protrudes toward the RESURF region with respect to the first portion and is thicker than the first portion, and
• the first field plate is provided so as to expose the first portion.