Semiconductor memory device and manufacturing method thereof

摘要

A semiconductor memory device includes a control gate electrode formed on a first main surface of a semiconductor substrate through a first insulating film, and a floating gate electrode covering a stepped region which connects the first main surface of the semiconductor substrate and a second main surface positioned at a lower level than the first main surface through a second insulating film and having a side surface capacitively coupled with one side surface of the control gate electrode through a third insulating film. The stepped region has a first stepped portion connected with the first main surface and a second stepped portion connecting the first stepped portion and the second main surface.