Semiconductor memory device and method of manufacturing the same
View Patent ↗A method of manufacturing a semiconductor memory device includes the steps of providing a gate insulating film on an active region, depositing a first conductive film on the gate insulating film, processing the first conductive film, the gate insulating film, and the active region to provide an 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 between the openings, depositing a first insulating film which covers the side and bottom surface of the opening, depositing a second insulating film over the first insulating film, shaping the first and second insulating films into a side wall spacer shape by etching to provide charge retention sections beside the gate electrode and providing diffusion areas at opposite sides of the gate electrode beneath the charge retention sections in the active region.
1. 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.
2. The method of manufacturing of a semiconductor memory device according to claim 1 , wherein
the third step includes arranging a side wall of the opening beneath the lower side of the gate insulating film to a tilted form which becomes further distanced from the gate electrode as being closer to the bottom of the opening.
3. The method of manufacturing of a semiconductor memory device according to claim 1 , wherein
the third step includes a sub step of processing the first conductive film and the gate insulating film to provide the opening, a sub step of providing a fourth insulating film which covers the side and bottom surface of the opening, and a sub step of removing the fourth insulating film.
4. The method of manufacturing of a semiconductor memory device according to claim 3 , wherein
the fourth insulating film is a silicon oxide film.
5. The method of manufacturing of a semiconductor memory device according to claim 1 , wherein
a step of depositing a third insulating film on the second insulating film after the fifth step of depositing the second insulating film and the sixth step includes processing the first insulating film, the second insulating film, and the third insulating film to a side wall spacer form by etching.
6. The method of manufacturing of a semiconductor memory device according to claim 5 , wherein
the third insulating film is a silicon oxide film.
7. The method of manufacturing of a semiconductor memory device according to claim 1 , wherein
the first insulating film is a silicon oxide film.
8. The method of manufacturing of a semiconductor memory device according to claim 1 , wherein
the second insulating film is a silicon nitride film.