SOI-type semiconductor device with suppressed spread of depletion region

摘要

In a semiconductor device including a semiconductor substrate (1, 1'), an insulating layer (2) formed on the semiconductor substrate and a semiconductor layer (3) formed on the insulating layer, the impurity concentration of at least one part of the semiconductor substrate in the proximity of the insulating layer is rich, i.e., higher than that of the other part of the semiconductor substrate.