Semiconductor device and manufacturing method thereof

A manufacturing method of a semiconductor device, the manufacturing method comprising:

• sequentially forming a first n− type layer and a second n− type layer on a first surface of an n+ type silicon carbide substrate;
• forming an n+ type region on the second n− type layer;
• forming a first trench and a second trench spaced apart from each other by etching the n+ type region and the second n− type layer;
• forming a p type region to surround a lateral portion and a lower portion of the first trench;
• forming a p+ type region between the lower surface of the first trench and the p type region;
• forming a gate insulating layer in the second trench;
• forming a gate electrode on the gate insulating layer;
• forming an oxide layer on the gate electrode;
• forming a source electrode on the oxide layer and the n+ type region, and in the first trench;
• and
• forming a drain electrode at a second surface of the n+ type silicon carbide substrate,
• wherein the source electrode contacts the p+ type region disposed under the first trench.