Granted Patent B2

US 8,064,262 · App. 12/233,577 · Granted Nov 22, 2011

Abstract

Claims (31)

1. A semiconductor device comprising:

a first data storage region comprising a non-volatile main data storage region;

a second data storage region comprising a non-volatile reference region wherein an erasing operation and a writing operation are performed on both the first data storage region and the second data storage region, wherein the non-volatile reference region comprises a first memory cell and a second memory cell that are both connected to a word line, the first memory cell stores a first logic value and has a first threshold voltage setting, the second memory cell stores a second logic value and has a second threshold voltage setting that is less than the first threshold voltage setting, a reference voltage value is determined between the first and second threshold voltage settings; and

a control unit coupled to the first and second data storage regions, wherein every time the control unit erases collectively data stored in the first and second data storage regions, the control unit determines a stress information related to the second data storage region by writing data to the second data storage region, next the control unit determines a stress condition corresponding to the first data storage region based on the stress information, and next the control unit uses the stress condition to verify a threshold voltage of the first data storage region.

2. The semiconductor device of claim 1 , wherein the second data storage region stores a reference information that is referred to when data is read from the first data storage region.

3. The semiconductor device of claim 1 , wherein the stress information comprises a change of threshold voltage of the second data storage region caused by stress applied to the second data storage region.

4. The semiconductor device of claim 3 , wherein the control unit decreases the stress of the writing operation to the first data storage region when the change of threshold voltage is greater than a defined voltage value.

5. The semiconductor device of claim 3 , wherein the control unit increases the stress of the writing operation to the first data storage region when the change of threshold value is less than a defined voltage value.

6. The semiconductor device of claim 1 , wherein the stress information comprises a frequency of stress applied to the second data storage region.

7. The semiconductor device of claim 6 , wherein the control unit decreases the stress of the writing operation on the first data storage region when the frequency of stress applied to the second data storage region is less than a defined frequency value, and the control unit increases the stress of the writing operation on the first data storage region when the frequency of stress applied to the second data storage region is greater than the defined frequency value.

8. The semiconductor device of claim 1 , further comprising a volatile data storage region coupled to the control unit which stores the stress information.

9. The semiconductor device of claim 1 , wherein the first and the second data storage regions are both connected to the word line.

10. A method for controlling a semiconductor device which comprises a first data storage region comprising a non-volatile main data storage region and a second data storage region comprising a non-volatile reference region, the method comprising:

determining a reference voltage between a first threshold voltage setting and a second threshold voltage setting, wherein the non-volatile reference region comprises a first memory cell and a second memory cell that are both connected to a word line, the first memory cell stores a first logic value and has the first threshold voltage setting, the second memory cell stores a second logic value and has the second threshold voltage setting that is less than the first threshold voltage setting;

erasing collectively data stored in the first and the second data storage regions;

every time after the erasing, determining a stress information related to the second data storage region by writing data to the second data storage region;

after the determining the stress information, determining a stress condition corresponding to the first data storage region based on the stress information related to the second data storage region; and

after the determining the stress condition, using the stress condition to verify a threshold voltage of the first data storage region.

11. The method of claim 10 , wherein said semiconductor device comprises flash memory.

12. The method of claim 10 , further comprising after the determining the stress information, storing the stress information with a volatile data storage region.

13. The method of claim 10 , further comprising measuring an amount of change in a threshold voltage of the second data storage region.

14. The method of claim 13 , further comprising adjusting a writing stress condition of the second data storage region.

15. The method of claim 13 , further comprising storing as the stress information the amount of change in the threshold voltage of the second data storage region.

16. A flash memory comprising:

a first data storage region comprising a non-volatile main data storage region;

a second data storage region comprising a non-volatile reference region wherein an erasing operation and a writing operation are performed on both the first data storage region and the second data storage region, wherein the non-volatile reference region comprises a first memory cell and a second memory cell that are both connected to a word line, the first memory cell stores a first logic value and has a first threshold voltage setting, the second memory cell stores a second logic value and has a second threshold voltage setting that is less than the first threshold voltage setting, a reference voltage value is determined between the first and second threshold voltage settings; and

a control unit coupled to the first and second data storage regions, wherein every time the control unit erases collectively data stored in the first and second data storage regions, the control unit determines a stress information related to the second data storage region by writing data to the second data storage region, next the control unit determines a stress condition corresponding to the first data storage region based on the stress information, and next the control unit uses the stress condition to verify a threshold voltage of the first data storage region, wherein the stress information comprises a frequency of the stress applied to the second data storage region.

17. The flash memory of claim 16 , wherein the second data storage region stores a reference information that is referred to when data is read from the first data storage region.

18. The flash memory of claim 16 , wherein the stress information comprises a change of threshold voltage of the second data storage region caused by stress applied to the second data storage region.

19. The flash memory of claim 18 , wherein the control unit decreases the stress of the writing operation to the first data storage region when the change of threshold voltage is greater than a defined voltage value, and the control unit increases the stress of the writing operation to the first data storage region when the change of threshold value is less than the defined voltage value.

20. The flash memory of claim 18 , wherein the first and the second data storage regions are both connected to the word line.

Assignments (8)