Semiconductor device

A semiconductor device comprising:

• a silicon carbide substrate having first and second principal surfaces;
• a first-conductive-type silicon carbide layer provided on the first principal surface of the silicon carbide substrate;
• a second-conductive-type first silicon carbide region formed at a surface of the silicon carbide layer;
• a first-conductive-type second silicon carbide region formed at the surface of the first silicon carbide region;
• a second-conductive-type third silicon carbide region formed at the surface of the first silicon carbide region;
• a second-conductive-type fourth silicon carbide region formed between the first silicon carbide region and the second silicon carbide region, the fourth silicon carbide region having an impurity concentration higher than that of the first silicon carbide region;
• a gate insulator continuously formed on surfaces of the silicon carbide layer, the first silicon carbide region, and the fourth silicon carbide region;
• a gate electrode formed on the gate insulator;
• an inter-layer insulator with which the gate electrode is covered;
• a first electrode electrically connected to the second silicon carbide region and the third silicon carbide region;
• and
• a second electrode formed on the second principal surface of the silicon carbide substrate.