Semiconductor device comprising insulated-gate bipolar transistor

A semiconductor device comprising a transistor portion, wherein the transistor portion includes:

• a drift region of a first conductivity type formed in a semiconductor substrate;
• a base region of a second conductivity type formed in the semiconductor substrate and above the drift region;
• an emitter region of the first conductivity type selectively formed in a partial region on a front surface side of the base region and having a concentration higher than a concentration in the drift region;
• an accumulation layer of the first conductivity type provided between the drift region and the base region and having a concentration higher than the concentration in the drift region;
• a plurality of trenches formed in a front surface of the semiconductor substrate and are arrayed in a first direction;
• and
• a plurality of mesa regions, each mesa region of the plurality of mesa regions formed between adjacent of each of the plurality of trenches, wherein
• the plurality of mesa regions includes:
• a plurality of first mesa regions in which the emitter region is provided in the most upper front surface of the semiconductor substrate;
• and
• a plurality of second mesa regions in which the emitter region is not provided in the most upper front surface of the semiconductor substrate,
• the plurality of trenches includes:
• a first trench in which a first conductive material is embedded, the first trench having an extending direction that is adjacent to a first of the plurality of mesa regions;
• a second trench in which the first conductive material is embedded, the second trench having an extending direction that is adjacent to a second of the plurality of mesa regions;
• and
• a third trench in which a second conductive material is embedded, the third trench having the extending direction that is adjacent to the first of the plurality of mesa regions or the second of the plurality of mesa regions, and the first conductive material is a gate conductive portion.