Field-effect transistor and semiconductor device

Abstract

To provide a field-effect transistor and a semiconductor device with improved ESD resistance. A field-effect transistor including: a gate electrode provided on a first-conductivity-type region of a semiconductor substrate with an insulating film provided between the gate electrode and the first-conductivity-type region; a source region of a second conductivity type provided in the semiconductor substrate on one of sides across the gate electrode; a drain region of the second conductivity type provided in the semiconductor substrate on the other of the sides, the other side facing the one side across the gate electrode; a first region of the first conductivity type provided below the drain region and having a higher concentration than the first-conductivity-type region; a second region of the first conductivity type provided to reach a surface in the semiconductor substrate on the other side and having a higher concentration than the first-conductivity-type region; and an extraction electrode connected to the second region.

Dependencies are inferred from the claim text.