Semiconductor device and its manufacturing method

Abstract

A semiconductor device is disclosed that can include a gate electrode (6) having a lower layer (6a) and a higher layer (6b), a mask insulating film (7) formed over a higher layer (6b). A side surface insulating film (9) may be formed on sides of a gate electrode (6) and a side wall insulating film (8) may be formed on the sides of a gate electrode (6) and mask insulating film (7). A low density impurity region (3) may be formed with a gate electrode (6) and side surface insulating film (9) as a mask. A higher density impurity region (4) may be formed with a gate electrode (6) and side wall insulating film (8) as a mask. A contact plug (10) may be formed between side wall insulating films (8) that contacts a higher density impurity region (4). A gate electrode (6) may have a reverse tapered shape when viewed in cross section. A lower layer (6a) may have a reverse tapered shape and/or a side surface insulating film (9) may have a greater thickness on sides of a higher layer (6b) than on a lower layer (6a).

Dependencies are inferred from the claim text.