Semiconductor device and method of manufacturing semiconductor device

A semiconductor device, comprising:

• a substrate formed of a wide-band-gap semiconductor material that has a band gap greater than that of silicon, the substrate having a front surface and a back surface;
• a deposit layer formed of the wide-band-gap semiconductor material and having an impurity concentration lower than that of the substrate, the deposit layer having a first side and a second side opposite to the first side, and being deposited on the front surface of the substrate that is located on the second side;
• a semiconductor region selectively disposed in the deposit layer on the first side thereof;
• a semiconductor layer formed of the wide-band-gap semiconductor material, disposed on a surface of the deposit layer on the first side and a surface of the semiconductor region formed in the deposit layer, the semiconductor layer having selectively disposed therein a first region, a second region and a contact region;
• a gate electrode disposed, via a gate insulating film, on the semiconductor layer and the first region;
• an interlayer insulating film covering the gate electrode;
• a source electrode in contact with the contact region and the second region;
• a drain electrode disposed on the back surface of the substrate;
• a plating film selectively disposed on the source electrode;
• and
• a pin electrode in contact with the plating film, wherein
• the substrate, the deposit layer, and the first and second regions formed in the semiconductor layer are of a first conductivity type,
• the semiconductor region, the semiconductor layer and the contact region formed therein are of a second conductivity type,
• the source electrode has
• a first titanium nitride (TiN) film, and
• a first titanium (Ti) film, a second TiN film, a second Ti film, and a metal film containing aluminum (Al) sequentially formed on the first TiN film,
• the first TiN film is formed to cover, and in direct contact with, the interlayer insulating film,
• the first TiN film has a plurality of openings formed therein, through which the first Ti film is in contact with the contact region, the first TiN film completely separating the interlayer insulating film from the first Ti film,
• the first Ti film is formed to fully cover, and in direct contact with, the first TiN film,
• the second TiN film is formed to fully cover, and in direct contact with, the first Ti film,
• the second Ti film is formed to fully cover, and in direct contact with, the second TiN film, and
• the metal film containing Al is formed to fully cover, and in direct contact with, the second Ti film.