Power semiconductor device

A semiconductor device comprising:

• a semiconductor layer;
• and
• a trench gate extending from a front surface of the semiconductor layer toward a back surface thereof,
• wherein the semiconductor layer comprises:
• a first semiconductor region of a first conductive type;
• a second semiconductor region of a second conductive type provided above the first semiconductor region and facing a side surface of the trench gate;
• and
• a third semiconductor region of the first conductive type provided above the second semiconductor region, separated from the first semiconductor region by the second semiconductor region, and facing the side surface of the trench gate, and
• wherein the first semiconductor region comprises:
• a lower semiconductor region;
• and
• an upper semiconductor region disposed between the lower semiconductor region and the second semiconductor region and having a lower impurity concentration than the lower semiconductor region,
• the upper semiconductor region being disposed at a shallower position than the trench gate and faces the side surface of the trench gate;
• and
• a side surface region disposed between the side surface of the trench gate and the upper semiconductor region and having a higher impurity concentration than the upper semiconductor region.