This specification relates to a process for manufacturing a semiconductor
device, comprising the steps of: forming a lower gate electrode film on a
semiconductor substrate 10 via a gate insulating film 11; forming an upper
gate electrode film on the lower gate electrode film, the upper gate
electrode film being made of a material having a lower oxidation rate than
that of the lower gate electrode film; forming a gate electrode 12 by
patterning the upper gate electrode film and the lower gate electrode
film, the gate electrode 12 comprising a lower gate electrode element 12a
and an upper gate electrode element 12b; forming source/drain regions 15
by introducing an impurity into the semiconductor substrate 10; and
forming oxide film sidewalls 13 by oxidizing the side faces of the lower
gate electrode element 12a and the upper gate electrode element 12b, the
thickness of the oxide film sidewalls 13 in the gate length direction
being larger at the sides of the lower gate electrode element 12a than at
the sides of the upper gate electrode element 12b.
