High-breakdown-voltage semiconductor device

A high-breakdown-voltage semiconductor device comprising:

• a high-resistance semiconductor layer of a first conductivity type having a first main surface and a second main surface, a plurality of first trenches being formed on the first main surface of the high-resistance semiconductor layer in a longitudinal plane shape and arranged in parallel with each other;
• a plurality of first semiconductor regions of the first conductivity type formed on the first main surface of the high-resistance semiconductor layer, each of the plurality of first semiconductor regions being sandwiched between adjacent ones of the plurality of first trenches, and having an impurity concentration higher than that of the high-resistance semiconductor layer;
• a second semiconductor region of a second conductivity type continuously disposed in a sidewall and a bottom portion of each of the plurality of first trenches;
• a sidewall insulating film disposed on the second semiconductor region of the sidewall of each of the plurality of first trenches;
• a third semiconductor region of the second conductivity type disposed in a surface region of the second semiconductor region of the bottom portion of each of the plurality of first trenches and having an impurity concentration higher than that of the second semiconductor region;
• a fourth semiconductor region disposed on the second main surface of the high-resistance semiconductor layer, and having an impurity concentration higher than that of the high-resistance semiconductor layer;
• a first electrode formed on each of the plurality of first semiconductor regions;
• a second electrode filling each of the plurality of first trenches and in contact with the third semiconductor region;
• and
• a third electrode formed on the fourth semiconductor region;
• wherein the high-resistance semiconductor layer further comprises second trenches communicating with the plurality of first trenches at both ends of longitudinal sides thereof, each of the plurality of first semiconductor regions is surrounded by the plurality of first trenches and the second trenches.