Semiconductor device comprising a MIS transistor and method for manufacturing the same

摘要

A semiconductor device such as a lateral power MOS transistor includes: a semiconductor substrate (3) with a principal plane (3a); a base region (20,21) disposed on the principal plane (3a); a source region (22) disposed on the principal plane (3a) in the base region (20,21) to be shallower than the base region (20,21); a drain region (25) disposed on the principal plane (3a), and spaced to the base region (20,21); a trench (26) disposed on the principal plane (3a); a trench gate electrode (28) disposed in the trench (26) through a trench gate insulation film (27); a planar gate electrode (31) disposed on the principal plane (3a) of the semiconductor substrate (3) through a planar gate insulation film (30); and an impurity diffusion region (35) having high concentration of impurities and disposed in a portion of the base region (20,21) to be a channel region facing the planar gate electrode (31).