| 摘要 |
PROBLEM TO BE SOLVED: To prevent dopant atoms from diffusing in a substrate from a gate electrode on a gate insulating film thinned to a degree that a tunnel current directly flows, and to reduce a gate leak current. SOLUTION: The method for manufacturing the semiconductor device comprises a step of forming a first gate insulating film 13A made of an oxide film on the semiconductor substrate 1 divided to a first element forming region 51 and a second element forming region 52. The method further comprises steps of removing a part included in the region 52 of the first insulating film 13A, and forming a second gate insulating film 15B made of an acid nitride film having a thickness smaller than that of the first film 13A on the region 52 by heat-treating the substrate 11 in an acid nitride atmosphere. The method also comprises steps of exposing the first film 13B and the second film 15B to nitrogen plasma, and thereby forming a first gate insulating film 13C and a second gate insulating film 15C in which the nitrogen atom is further introduced.
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