Semiconductor device

A semiconductor device comprising:

• a semiconductor chip that has a main surface;
• a trench separation structure that demarcates a device region in the main surface and that includes a separation trench which is formed in the main surface, a separation insulating film which covers an inner wall of the separation trench and a separation electrode which is embedded in the separation trench across the separation insulating film;
• a functional device that is formed in the device region at the main surface;
• and
• a field insulating film that partially covers the main surface at an interval from the functional device in the device region and has an insulating side wall in which an inclined angle made with the main surface is not less than 20° and not more than 40°,
• wherein the functional device includes a trench gate structure that has a gate trench formed in the main surface, and an upper electrode and a lower electrode which are embedded in the gate trench so as to be insulated and separated in an up/down direction by an insulator,
• the field insulating film is formed at an interval from the trench gate structure,
• the functional device includes a plurality of unit transistors each of which includes the plurality of trench gate structures,
• the functional device includes an n-system gate-split transistor that includes n-number (n≥2) of system transistors each of which is constituted of one or the plurality of unit transistors systematized as an individually controlled object, and which generate a single output signal by selectively controlling the n-number of the system transistors, and
• the semiconductor device further comprises a control circuit that is formed in a region of the main surface which is different from the device region, and that individually controls the n-number of the system transistors.