Semiconductor device and a method of manufacturing the same
A semiconductor device having a nonvolatile memory is reduced in size. In an AND type flash memory having a plurality of nonvolatile memory cells having a plurality of first electrodes, a plurality of word lines crossing therewith, and a plurality of floating gate electrodes disposed at positions which respectively lie between the plurality of adjacent first electrodes and overlap the plurality of word lines, as seen in plan view, the plurality of floating gate electrodes are formed in a convex shape, as seen in cross section, so as to be higher than the first electrodes. As a result, even when nonvolatile memory cells are reduced in size, it is possible to process the floating gate electrodes with ease. In addition, it is possible to improve the coupling ratio between floating gate electrodes and control gate electrodes of the word lines without increasing the area occupied by the nonvolatile memory cells.
1. A semiconductor device including a plurality of non-volatile memory cells electrically connected to a word line extending in a first direction in plane view, comprising:
a plurality of floating gates formed over a semiconductor substrate;
a plurality of first insulating films formed between each of the said floating gates in the first direction, respectively;
a second insulating film formed over a top surface of each of the first insulating films, side surfaces of each of the floating gates and a top surface of each of the floating gates; and
a control gate configured to serve as a word line formed over the second insulating film,
wherein a height of the top surface of each of the floating gates is higher than a height of the top surface of each of the first insulating films,
wherein each of the first insulating films is formed in self-alignment with a corresponding one of the floating gates,
wherein a length of each the of the floating gates in a second direction, perpendicular to the first direction, is larger than a length of each of the floating gates in the first direction, and
wherein a length from a top surface of the second insulating film which is formed over the first insulating films to the top surface of the floating gates is larger than a length of the space between each of the floating gates in the first direction, and larger than the length of each of the floating gates in the first direction.
2. A semiconductor device according to the claim 1 ,
wherein the second insulating film includes a first silicon oxide film, a first silicon nitride film and a second silicon oxide film.
3. A semiconductor device according to the claim 1 ,
wherein each of the floating gates includes a polysilicon film.
4. A semiconductor device according to the claim 1 ,
wherein the control gate includes a polysilicon film and a tungsten silicide film.
5. A semiconductor device according to the claim 1 ,
wherein each of the first insulating films includes a silicon oxide film.
6. A semiconductor device according to the claim 1 ,
wherein the non-volatile memory cells comprise flash memory cells, respectively.