Semiconductor device

A semiconductor device comprising:

• a semiconductor substrate of a first conductivity type;
• a cap insulating film that is embedded in the semiconductor substrate and has a first side surface perpendicular to an upper surface of the semiconductor substrate, a second side surface opposite to the first side surface, and a lower surface opposite to the upper surface of the semiconductor substrate;
• a first gate electrode of which whole of a body thereof is embedded in the semiconductor substrate and that is covered with a lower surface of the cap insulating film;
• a gate insulating film of which whole of a body thereof is embedded in the semiconductor substrate and that is formed between the gate electrode and the semiconductor substrate;
• a first diffusion region that covers the first side surface of the cap insulating film;
• a second diffusion region that covers the second side surface of the cap insulating film;
• and
• a first selective element that covers the second side surface of the cap insulating film and an upper surface of the second diffusion region, and has a third diffusion region in contact with the upper surface of the semiconductor substrate, wherein
• the gate electrode and the first and second diffusion regions constitute a first field-effect transistor,
• the semiconductor substrate and the second and third diffusion regions constitute a first bipolar transistor,
• the field-effect transistor and the first bipolar transistor constitute the first selective element,
• the first and second diffusion regions have a second conductivity type opposite to the first conductivity type, and
• the third diffusion region has the first conductivity type.