Resistive memory device and method of programming the same
A semiconductor memory device contains a first memory cell including a first variable resistive element, and a first circuit for controlling a write performed for the first memory cell. The first circuit performs a first write for writing first data in the first memory cell in a first time, determines whether the first write fails or not, and performs a second write for writing the first data in the first memory cell in a second time longer than the first time, if the first write fails.
1. A semiconductor memory device comprising:
a first memory cell including a first variable resistive element; and
a first circuit which controls a write performed for the first memory cell,
wherein the first circuit:
performs a first write for writing first data in the first memory cell in a first time,
determines whether or not the first write fails, and
performs a second write for writing the first data in the first memory cell in a second time longer than the first time, if the first write fails, and
wherein:
the first time is determined by a first write pulse having a first pulse width, and the second time is determined by a second write pulse having a second pulse width greater than the first pulse width,
the first write pulse is generated based on rise times of a first signal and a second signal, and
the second write pulse is generated based on rise times of the first signal and a delayed signal of the second signal.
2. The device of claim 1 , wherein the first circuit comprises:
a first latch which temporarily stores read data read from the first memory cell; and
a second latch which temporarily stores write data to be written in the first memory cell, and
wherein a determination of whether or not the first write fails is made by checking whether or not data in the first latch and data in the second latch are identical.
3. The device of claim 2 , wherein data in the first memory cell is transferred to the first latch before the determination of whether or not the first write fails is made.
4. The device of claim 2 , wherein the first write is performed in response to a first command, and the second write is performed in response to a second command different from the first command.
5. The device of claim 4 , wherein second data is kept from being transferred to the second latch in the second write by generating a third signal for the second data accompanying the second command.
6. The device of claim 4 , wherein the second command is a pre-charge command.
7. A semiconductor memory device comprising:
a first memory cell including a first variable resistive element;
a second memory cell including a second variable resistive element; and
a first circuit which controls a write performed for the first memory cell and the second memory cell,
wherein the first circuit:
performs a first write for writing first data in the first memory cell in a first time,
performs a second write for writing second data in the second memory cell in the first time,
determines whether or not the first write fails, and further determines whether or not the second write fails, and
performs a third write for writing the first data in the first memory cell in a second time longer than the first time if the first write fails, and further performs a fourth write for writing the second data in the second memory cell in the second time if the second write fails.
8. The device of claim 7 , wherein the first time is determined by a first write pulse having a first pulse width, and the second time is determined by a second write pulse having a second pulse width greater than the first pulse width.
9. The device of claim 8 , wherein:
the first write pulse is generated based on rise times of a first signal and a second signal, and
the second write pulse is generated based on rise times of the first signal and a delayed signal of the second signal.
10. The device of claim 7 , wherein the first circuit comprises:
a first latch which temporarily stores read data read from the first memory cell; and
a second latch which temporarily stores write data to be written in the first memory cell, and
wherein a determination of whether or not the first write fails is made by checking whether or not data in the first latch and data in the second latch are identical.
11. The device of claim 7 , wherein the first circuit comprises:
a third latch which temporarily stores read data read from the second memory cell; and
a fourth latch which temporarily stores write data to be written in the second memory cell, and
wherein a determination of whether or not the second write fails is made by checking whether or not data in the third latch and data in the fourth data are identical.
12. The device of claim 10 , wherein data in the first memory cell is transferred to the first latch before the determination of whether or not the first write fails is made.
13. The device of claim 11 , wherein data in the second memory cell is transferred to the third latch before the determination of whether or not the second write fails is made.
14. The device of claim 10 , wherein the first write is performed in response to a first command, and the second write is performed in response to a second command different from the first command.
15. The device of claim 14 , wherein third data is kept from being transferred to the second latch in the third write by generating a third signal for the third data accompanying the second command.
16. The device of claim 14 , wherein the second command is a pre-charge command.
17. The device of claim 11 , wherein the second write is performed in response to a third command, and the fourth write is performed in response to a fourth command different from the third command.
18. The device of claim 17 , wherein fourth data is kept from being transferred to the fourth latch in the fourth write by generating a fourth signal for the fourth data accompanying the fourth command.