SEMICONDUCTOR DEVICE HAVING TRENCH FILLED UP WITH GATE ELECTRODE AND METHOD OF MANUFACTURING THE SAME

摘要

A method for manufacturing a semiconductor device comprises: preparing a first conductivity type semiconductor substrate (1) having a principal surface (1a) and a back surface (1 b) at an opposite side of the principal surface; forming a first trench (62) in the semiconductor substrate, the first trench extending in the semiconductor substrate from the principal surface in a perpendicular direction with respect to the principal surface, wherein the remaining semiconductor substrate constitutes a first conductivity type drain region (4); forming a drift formation film (63) constituting a first conductivity type drift region (1 c), in the first trench such that the drift formation film covers an inner wall of the first trench and has a recess; forming a base formation film (64) constituting a second conductivity type base region (2) in the recess of the drift formation film such that the base formation film covers the drift region in the first trench and has a recess; forming a source formation film (65) constituting a first conductivity type source region in the recess of the base formation film to fully fill the first trench such that the source formation film covers the base region in the first trench; flattening the drift formation film, the base formation film, and the source formation film; forming a second trench (5) in the semiconductor substrate, the second trench passing through the base region in a direction (Y), which is parallel to the principal surface, from the source region and extending from the principal surface in the perpendicular direction; forming a gate insulating film (6) in the second trench; forming a gate electrode (7) on a surface of the gate insulating film; forming a source electrode (9) electrically connected to the source region and the base region; and forming a drain electrode (10) electrically connected to the drain region.