Granted Patent B2

US 7,269,080 · App. 11/195,359 · Granted Sep 11, 2007

Abstract

Claims (56)

1. A nonvolatile phase change memory device comprising:

a memory array formed by memory cells arranged in rows and columns, word lines and bit lines connected to terminals of memory cells arranged in a same row and, respectively, in a same column;

a row decoder coupled to the memory array to bias the word lines;

a column decoder coupled to the memory array to bias the bit lines;

a biasing circuit coupled to the row decoder and to the column decoder to supply a first biasing voltage to a first terminal and a second biasing voltage to a second terminal of an addressed memory cell; and

wherein the first biasing voltage is a positive biasing voltage and the second biasing voltage is a negative biasing voltage, wherein the biasing circuit is coupled to the row decoder and to the column decoder to further supply a third biasing voltage to a first terminal and a fourth biasing voltage to a second terminal of non-addressed memory cells wherein the third biasing voltage and the fourth biasing voltage are in the range between the first biasing voltage and the second biasing voltage.

2. A nonvolatile phase change memory device according to claim 1 wherein during writing or reading of an addressed memory cell the first biasing voltage and the second biasing voltage have the same absolute values.

3. A nonvolatile phase change memory device according to claim 1 wherein during writing of an addressed memory cell the first biasing voltage and the second biasing voltage have different absolute values.

4. A nonvolatile phase change memory device according to claim 1 wherein the row decoder is coupled to the first terminal and the column decoder is coupled to the second terminal of the addressed memory cell.

5. A nonvolatile phase change memory device according to claim 1 wherein the column decoder is coupled to the first terminal and the row decoder is coupled to the second terminal of the addressed memory cell.

6. A nonvolatile phase change memory device according to claim 1 wherein during writing of the addressed memory cell, the third biasing voltage is lower than the fourth biasing voltage.

7. A nonvolatile phase change memory device according to claim 6 wherein the row decoder is coupled to the first terminal and the column decoder is coupled to the second terminal of the non-addressed memory cell.

8. A nonvolatile phase change memory device according to claim 6 wherein the column decoder is coupled to the first terminal and the row decoder is coupled to the second terminal of the non-addressed memory cell.

9. A nonvolatile phase change memory device according to claim 1 wherein during writing or reading of the addressed memory cell, the third biasing voltage is equal to the fourth biasing voltage.

10. A nonvolatile phase change memory device according to claim 1 wherein memory cells arranged in the same row have first terminals connected to a same word line and memory cells arranged in the same column have second terminals connected to a same bit line.

11. A nonvolatile phase change memory device according to claim 1 wherein memory cells arranged in the same column have first terminals connected to a same bit line and memory cells arranged in the same row have second terminals connected to a same word line.

12. A method of biasing a nonvolatile phase change memory device including a memory array formed by memory cells arranged in rows and columns, word lines and bit lines connected to terminals of memory cells arranged in a same row and, respectively, in a same column; a row decoder coupled to the memory array to bias the word lines; a column decoder coupled to the memory array to bias the bit lines; the method comprising:

biasing a first terminal of an addressed memory cell at a positive first biasing voltage;

biasing a second terminal of the addressed memory cell at a negative second biasing voltage; and

biasing a first and a second terminals of non-addressed memory cells at a third biasing voltage and, respectively, a fourth biasing voltage, wherein the third biasing voltage and the fourth biasing voltage are in the range between the first biasing voltage and the second biasing voltage.

13. A biasing method according to claim 12 wherein during writing or reading of the addressed memory cell, the first biasing voltage and the second biasing voltage have the same absolute values.

14. A biasing method according to claim 12 wherein during writing of the addressed memory cell the first biasing voltage and the second biasing voltage have different absolute values.

15. A biasing method according to claim 12 wherein during writing of the addressed memory cell, the third biasing voltage is lower than the fourth biasing voltage.

16. A biasing method according to claim 12 wherein during writing or reading of the addressed memory cell, the third biasing voltage is equal to the fourth biasing voltage.

17. A system comprising:

a processing unit;

an interface coupled to said processing unit; and

a nonvolatile phase change memory device coupled to said interface, wherein the nonvolatile phase change memory device includes a memory array formed by memory cells arranged in rows and columns, word lines and bit lines connected to terminals of memory cells arranged in a same row and, respectively, in a same column; a row decoder coupled to the memory array to bias the word lines; a column decoder coupled to the memory array to bias the bit lines; a biasing circuit coupled to the row decoder and to the column decoder to supply a first biasing voltage to a first terminal and a second biasing voltage to a second terminal of an addressed memory cell; and wherein the first biasing voltage is a positive biasing voltage and the second biasing voltage is a negative biasing voltage, wherein the biasing circuit is coupled to the row decoder and to the column decoder to further supply a third biasing voltage to a first terminal and a fourth biasing voltage to a second terminal of non-addressed memory cells, wherein the third biasing voltage and the fourth biasing voltage are in the range between the first biasing voltage and the second biasing voltage.

18. A system according to claim 17 wherein said interface is a wireless interface.

19. A method of biasing a phase change memory device including an addressed memory cell and a non-addressed memory cell, the method comprising:

providing a first potential to a first terminal of the addressed memory cell wherein the first potential is a negative potential;

providing a second potential to a second terminal of the addressed memory cell;

providing a third potential to a first terminal of the non-addressed memory cell; and

providing a fourth potential to a second terminal of the non-addressed memory cell.

20. A method of biasing according to claim 19 wherein

providing the first potential includes providing the first potential to a row decoder that couples the first potential to the first input of the addressed memory cell; and

providing the second potential includes providing the second potential to a column decoder that couples the second potential to the second input of the addressed memory cell.

21. A method of biasing according to claim 19 wherein

providing the first potential includes providing the first potential to a column decoder that couples the first potential to the first input of the addressed memory cell; and

providing the second potential includes providing the second potential to a row decoder that couples the second potential to the second input of the addressed memory cell.

22. A method of biasing according to claim 19 wherein

providing the third potential includes providing the third potential to a row decoder that couples the third potential to the first input of the non-addressed memory cell;

providing the fourth potential includes providing the fourth potential to a column decoder that couples the fourth potential to the second input of the non-addressed memory cell; and

wherein the third potential lower than the fourth potential.

23. A method of biasing according to claim 19 wherein

providing the third potential includes providing the third potential to a column decoder that couples the third potential to the first input of the non-addressed memory cell;

providing the fourth potential includes providing the fourth potential to a row decoder that couples the fourth potential to the second input of the non-addressed memory cell; and

wherein the third potential lower than the fourth potential.

24. A method of biasing according to claim 19 wherein the magnitude of the third potential is similar to the magnitude of the fourth potential.

25. A method of biasing according to claim 19 wherein the third potential and fourth potential are within a range between the first potential and the second potential.

26. A method of biasing according to claim 19 further comprising writing to the addressed memory cell.

27. A method of biasing according to claim 19 further comprising reading from the addressed memory cell.

28. A system according to claim 17 wherein the row decoder is coupled to the first terminal and the column decoder is coupled to the second terminal of the addressed memory cell.

29. A system according to claim 17 wherein during writing of the addressed memory cell, the third biasing voltage is lower than the fourth biasing voltage.

30. A system according to claim 17 wherein the row decoder is coupled to the first terminal of the non-addressed memory cell and the column decoder is coupled to the second terminal of the non-addressed memory cell.

31. A system according to claim 17 wherein during writing or reading of the addressed memory cell, the third biasing voltage is equal to the fourth biasing voltage.

Assignments (9)