Nonvolatile semiconductor memory device and manufacturing method thereof
A nonvolatile semiconductor memory device that have a new structure are provided, in which memory cells are laminated in a three dimensional state so that the chip area may be reduced. The nonvolatile semiconductor memory device of the present invention is a nonvolatile semiconductor memory device that has a plurality of the memory strings, in which a plurality of electrically programmable memory cells is connected in series. The memory strings comprise a pillar shaped semiconductor; a first insulation film formed around the pillar shaped semiconductor; a charge storage layer formed around the first insulation film; the second insulation film formed around the charge storage layer; and first or nth electrodes formed around the second insulation film (n is natural number more than 1). The first or nth electrodes of the memory strings and the other first or nth electrodes of the memory strings are respectively the first or nth conductor layers that are spread in a two dimensional state.
1. A nonvolatile semiconductor memory device comprising a plurality of memory strings arranged along a first direction and a second direction being different from the first direction, including at least one memory string having a plurality of electrically programmable memory cells connected in series, the memory string comprising:
a semiconductor layer extending in a third direction perpendicular to a substrate, and
a plurality of electrodes formed around the semiconductor layer,
wherein edges of the electrodes forming the electrodes of the memory string are configured as steps, and the electrodes of the at least one memory string are shared with a second memory string adjacent to the at least one memory string in the first direction and a third memory string adjacent to the at least one memory string in the second direction.
2. The nonvolatile semiconductor memory device according to claim 1 , the memory string further comprising:
a first insulation film formed around the semiconductor layer,
a charge storage layer formed around the first insulation film,
a second insulation film formed around the charge storage layer, and
a plurality of third insulation films formed around the second insulation film, the third insulation films being formed between the electrodes, respectively,
wherein a side surface of the electrodes and the third insulation films on the semiconductor layer is uneven, and the electrodes are formed around the second insulation film.
3. The nonvolatile semiconductor memory device according to claim 1 , the device further comprising:
a plurality of plugs, each of the plugs being connected electrically to an upper surface of each of the edges of the electrodes respectively.
4. The nonvolatile semiconductor memory device according to claim 3 , wherein the plurality of plugs includes at least a first plug and a second plug, and a distance between the bottom position of the first plug and the substrate is different from a distance between the bottom position of the second plug and the substrate.
5. The nonvolatile semiconductor memory device according to claim 3 , wherein the plurality of plugs includes at least a first plug and a second plug, and a distance between the top position of the first plug and the substrate is substantially the same as a distance between the top position of the second plug and the substrate.
6. The nonvolatile semiconductor memory device according to claim 3 , wherein each of the electrodes is connected to a word line driver via each of the plugs.
7. A nonvolatile semiconductor memory device comprising a plurality of memory strings including a first memory string, a second memory string and a third memory string, the memory strings being arranged along a first direction and a second direction being different from the first direction, the first memory string having a plurality of electrically programmable memory cells connected in series, the memory string comprising:
a semiconductor layer extending in a third direction perpendicular to a substrate, and
a plurality of electrodes formed around the semiconductor layer,
wherein edges of the electrodes forming the electrodes of the memory string are configured as steps, and the electrode surrounds the first memory string, the second memory string and the third memory string, the second memory string adjacent to the first memory string in the first direction and the third memory string adjacent to the first memory string in the second direction.
8. The nonvolatile semiconductor memory device according to claim 7 , the memory string further comprising:
a first insulation film formed around the semiconductor layer,
a charge storage layer formed around the first insulation film,
a second insulation film formed around the charge storage layer, and
a plurality of third insulation films formed around the second insulation film, the third insulation films being formed between the electrodes, respectively,
wherein a side surface of the electrodes and the third insulation films on the semiconductor layer is uneven, and the electrodes are formed around the second insulation film.
9. The nonvolatile semiconductor memory device according to claim 7 , the device further comprising:
a plurality of plugs, each of the plugs being connected electrically to an upper surface of each of the edges of the electrodes respectively.
10. The nonvolatile semiconductor memory device according to claim 9 , wherein the plurality of plugs includes at least a first plug and a second plug, and a distance between the bottom position of the first plug and the substrate is different from a distance between the bottom position of the second plug and the substrate.
11. The nonvolatile semiconductor memory device according to claim 9 , wherein the plurality of plugs includes at least a first plug and a second plug, and a distance between the top position of the first plug and the substrate is substantially the same as a distance between the top position of the second plug and the substrate.
12. The nonvolatile semiconductor memory device according to claim 9 , wherein each of the electrodes is connected to a word line driver via each of the plugs.