Nonvolatile semiconductor memory and method for manufacturing the same

1. A nonvolatile semiconductor memory comprising:

a semiconductor substrate;

a plurality of columnar semiconductors formed on the semiconductor substrate to vertically extend in parallel with one another and to be in a matrix as viewed from above;

plurality of charge storage insulating films formed around the columnar semiconductors, respectively:

at least two of plate-like electrodes each extending two-dimensionally to be perpendicular to the columnar semiconductors and to surround the charge storage insulating films, each electrode respectively forming a memory transistor with the columnar semiconductors and the charge storage insulating films, at least one groove vertically passing through the electrodes to expose sidewalls of the electrodes; and

a plurality of metal silicides formed on the exposed sidewalls of the electrodes, respectively.

2. The nonvolatile semiconductor memory according to claim 1 , wherein the columnar semiconductor, the charge storage insulating film and the electrode form a memory transistor operated in a depression mode.

3. The nonvolatile semiconductor memory according to claim 1 , wherein the columnar semiconductor comprises a plurality of columnar semiconductors;

wherein the charge storage insulating film comprises a plurality of charge storage insulating films respectively formed around the plurality of columnar semiconductors;

wherein the electrode is formed to surround the plurality of charge storage insulating films;

wherein the groove comprises a plurality of grooves; and

wherein the metal silicide is formed on respective sidewalls of the plurality of grooves.

4. The nonvolatile semiconductor memory according to claim 3 , wherein the electrode comprises a plurality of linear portions separated from each other by the plurality of grooves.

5. The nonvolatile semiconductor memory according to claim 4 , wherein the plurality of linear portions are connected with each other on one end of the electrode.

6. The nonvolatile semiconductor memory according to claim 4 , wherein the plurality of linear portions are connected with each other on both ends of the electrode.

7. The nonvolatile semiconductor memory according to claim 3 , wherein the plurality of columnar semiconductors are formed in parallel; and

wherein the plurality of columnar semiconductors are disposed in a matrix.

8. The nonvolatile semiconductor memory according to claim 1 , wherein the electrode comprises a plurality of electrodes alternately laminated with a plurality of insulators; and

wherein each of the plurality of electrodes surrounds the charge storage insulating film.

9. The nonvolatile semiconductor memory according to claim 8 , wherein the columnar semiconductor, the plurality of electrodes and the charge storage insulating film form a memory string having a plurality of memory transistors operated in a depression mode.

10. The nonvolatile semiconductor memory according to claim 1 further comprising:

a gate insulating film formed around the columnar semiconductor above the charge storage insulating film;

a second electrode surrounds the gate insulating film; and

a second metal silicide formed on a sidewall of the second electrode.

11. The nonvolatile semiconductor memory according to claim 10 , wherein the columnar semiconductor, the gate insulating film and the second electrode form a selection transistor operated in a depression mode.

12. The nonvolatile semiconductor memory according to claim 1 , wherein the metal silicide comprises at least one of a titanium silicide, a cobalt silicide and a nickel silicide.

13. The nonvolatile semiconductor memory according to claim 1 further comprising:

a plurality of gate insulating films formed around the columnar semiconductors above the charge storage insulating films, respectively;

a gate electrode extending two-dimensionally to be perpendicular to the columnar semiconductors and to surround the gate insulating films, the gate electrode respectively forming a select transistor with the columnar semiconductors and the gate insulating films, at least one groove vertically passing through the gate electrode to expose a sidewall of the gate electrode; and

a second metal silicide formed on the exposed sidewall of the gate electrode.

14. The nonvolatile semiconductor memory according to claim 13 , wherein the second metal silicide comprises at least one of a titanium silicide, a cobalt silicide and a nickel silicide.

15. The nonvolatile semiconductor memory according to claim 13 , wherein a plurality of grooves are formed in each electrode; and

wherein a first metal silicide is formed on sidewalls of the plurality of grooves.