Insulated gate semiconductor device

An insulated gate semiconductor device comprising:

• a semiconductor layer of a first conductivity type;
• a first operation part provided in a surface of the semiconductor layer;
• a second operation part provided in the surface of the semiconductor layer so as to be smaller in area than the first operation part;
• a first channel region of a second conductivity type opposite from the first conductivity type provided in the first operation part;
• a first transistor provided in the first operation part and comprising a gate electrode;
• a second channel region of the second conductivity type provided in the second operation part;
• a second transistor provided in the second operation part and comprising a gate electrode;
• a gate connection electrode formed of a semiconductor and connected to the gates of the first and second transistors;
• and
• a gate wiring formed of a metal and disposed on the gate connection electrode so as to be electrically in contact with the gate connection electrode,
• wherein in plan view of the insulated gate semiconductor device the first operation part is disposed around the second operation part,
• in the plan view of the insulated gate semiconductor device the gate connection electrode and the gate wiring are disposed between the first operation part and the second operation part,
• the first operation part is formed in a rectangular shape, and curvatures of four corner portions of the rectangular shape are equal, and
• the first and second channel regions are disposed so as to be separated from each other by a distance which allows depletion layers to come into contact with each other, the depletion layers spreading in the semiconductor layer when a reverse voltage is applied to the first and second transistors.