Semiconductor memory device and method of manufacturing the same

A method of manufacturing of a semiconductor memory device comprising:

• a first step of providing a gate insulating film on an active region of the first conduction type which is formed on a part of a semiconductor substrate surface;
• a second step of depositing a first conductive film on the gate insulating film;
• a third step of processing the first conductive film, the gate insulating film, and the active region to provide at least one opening of which the bottom is located below the interface between the active region and the gate insulating film and then providing a gate electrode surrounded by the opening or between the openings;
• a fourth step of depositing a first insulating film which covers the side and bottom surface of the opening;
• a fifth step of depositing a second insulating film over the first insulating film;
• a sixth step of shaping the first insulating film and the second insulating film into a side wall spacer shape by etching thus to provide charge retention sections onto the opening at both sides of the gate electrode;
• and
• a seventh step of providing diffusion areas of the second conduction type, which is different from the first conduction type, at opposite sides of the gate electrode beneath the charge retention sections in the active region.