Non-volatile semiconductor storage device
According to one embodiment, a semiconductor storage device includes a memory cell array having memory cell capable of holding N-bit data; and a sense amplifier comprising a first latch holding information on a threshold distribution, a second latch holding write data, and a third latch holding lower information of the N-bit data, and supplying a first to a fourth voltages to the memory cell to write the data to the memory cell using the first to fourth voltages. The sense amplifier supplies the first to third voltages to the memory cell based on information in the second and the third latches, and based on a result of transfer of the information held by the first latch to the second latch, supplies the fourth voltage or the first voltage to the memory cell.
1. A non-volatile semiconductor storage device comprising:
a memory cell array having memory cells which are arranged in a matrix along a bit line direction and a word line direction and each of which is capable of holding N-bit (N: natural number) data; and
a sense amplifier comprising a first latch capable of temporarily holding information on a threshold distribution, a second latch capable of holding write data, and a third latch capable of holding, lower information of the N-bit data, the sense amplifier capable of supplying a first to a fourth voltages to each of the memory cells to write the data to the memory cell using the first to fourth voltages,
wherein the sense amplifier supplies the first to third voltages to the memory cell based on information held by the second latch and the third latch, and then,
based on a result of transfer of the information held by the first latch to the second latch, supplies the fourth voltage, the first voltage, or the third voltage to the memory cell.
2. The non-volatile semiconductor storage device according to claim 1 ,
wherein the sense amplifier comprises:
a first transistor supplied with a non-selection voltage through one end of the first transistor and connected to the bit line at the other end of the first transistor; and
a second transistor connected to the third latch at one end of the second transistor and connected to the bit line at the other end of the second transistor along with the other end of the first transistor,
when the second latch holds a first result as the result, the first transistor supplies the fourth voltage lower than a write voltage inhibition voltage to the bit line, and
when the second latch holds a second result as the result, the second transistor supplies the first voltage or the third voltage which is lower than the fourth voltage to the bit line based on the information held by the third latch.
3. The non-volatile semiconductor storage device according to claim 2 , further comprising a control unit configured to control on and off timings for the first transistor and the second transistor,
wherein, when the first transistor supplies the second voltage, the control unit switches a signal level supplied. to a gate of the first transistor from a fifth voltage to a sixth voltage lower than the fifth voltage, and
when the second transistor supplies the third voltage, the control unit switches the signal level supplied to a gate of the second transistor to a seventh voltage lower than the sixth voltage.
4. The non-volatile semiconductor storage device according to claim 3 , wherein the N-bit threshold distribution includes a first state representing an erase state, and a second state, a third state, and a fourth state in order of increasing voltage, and
the threshold distribution capable of being temporarily held by the first latch is positioned between a first verify voltage which is higher than the first state and lower than the second state and a second verify voltage which is higher than the first state and lower than the first verify voltage.