Semiconductor device including a vertical field effect transistor, having trenches, and a diode

A semiconductor device comprising:

• (a) a vertical field effect transistor, said vertical field effect transistor comprising:
• a drain electrode formed on a first surface of a first conductivity type of a semiconductor;
• a pair of first trenches formed from a second surface of the semiconductor;
• control regions of a second conductivity type formed respectively along said first trenches;
• a source region of the first conductivity type formed along the second surface of the semiconductor between said first trenches;
• a source electrode joined to said source region;
• and
• a gate electrode adjacent to said control regions,
• said semiconductor device further comprising;
• (b) a pair of second trenches formed from the second surface of the semiconductor, independently of said field effect transistor;
• (c) control regions of the second conductivity type formed along said second trenches;
• (d) a cathode layer of the first conductivity type formed along the second surface between said second trenches;
• and
• (e) a hetero junction diode including polycrystalline silicon of the second conductivity type in contact with said cathode layer.

A silicon carbide semiconductor device comprising:

• (a) a vertical field effect transistor, said vertical field effect transistor comprising:
• a substrate of a first conductivity type having a low impurity concentration and a band gap of at least 2.0 eV;
• a first layer formed along a first surface of said substrate, said first layer being lower in resistance than said substrate;
• a drain electrode formed on a surface of said substrate;
• first trenches formed from a surface of said first layer;
• a second region of the first conductivity type formed in said first layer so as to come in contact with said first trenches;
• a source electrode joined to said second region;
• control regions of a second conductivity type formed respectively along said first trenches;
• and
• a gate electrode adjacent to said control regions,
• said semiconductor device further comprising;
• (b) a pair of second trenches formed in said first layer, independently of said field effect transistor;
• (c) control regions of the second conductivity type formed along said second trenches;
• (d) a cathode region of the first conductivity type formed in said first layer between said second trenches;
• and
• (e) a hetero junction diode including polycrystalline silicon of the second conductivity type in contact with said cathode region.