Semiconductor device and method for fabricating the same

摘要

A method for fabricating a semiconductor device includes the steps of: forming a first insulating film on a semiconductor substrate; removing part of the first insulating film; forming a second insulating film having a leakage current density higher than that of the first insulating film on a region where the part of the first insulating film has been removed on the semiconductor substrate; forming an undoped semiconductor film on the first and second insulating films; implanting an impurity into part of the undoped semiconductor film, thereby defining semiconductor regions of a first conductivity type dotted as discrete islands; forming a third insulating film on the semiconductor regions of the first conductivity type and the undoped semiconductor film; and removing part of the third insulating film by wet etching. At least the second insulating film is formed under the semiconductor regions of the first conductivity type.