Method of programming, erasing and reading memory cells in a resistive memory array
View Patent ↗The present approach is a method of writing (which may be programming or erasing) data to a selected memory cell of a memory array. The array includes a plurality of word lines, a plurality of bit lines, a plurality of memory cells each including a diode and a resistive memory device in series connecting a word line and a bit line, and a plurality of transistors, each having a first and second source/drain terminals and a gate, each transistor having a first source/drain terminal connected to a bit line. In the present method a voltage is applied to a selected word line, and a voltage is applied to the second source/drain terminal of a transistor having its first source/drain terminal connected to a selected bit line. The voltage applied to the selected word line is greater than the voltage applied to the second source/drain terminal of that transistor.
1. A method of writing data to a selected memory cell of a memory array, the array comprising a plurality of word lines, a plurality of bit lines, a plurality of memory cells each comprising a diode and a resistive memory device in series connecting a word line and a bit line, and a plurality of transistors, each having first and second source/drain terminals and a gate, each transistor having a first source/drain terminal connected to a bit line, the method comprising applying a voltage to a selected word line, and applying a voltage to the second source/drain terminal of a transistor having its first source/drain terminal connected to a selected bit line, the voltage applied to the selected word line being greater than the voltage applied to the second source/drain terminal of the transistor having its first source/drain terminal connected to the selected bit line.
2. The method of claim 1 wherein the method of writing data to the selected memory cell further comprises applying a voltage to the gate of the transistor having its first source/drain terminal connected to the selected bit line.
3. The method of claim 1 wherein the voltage applied to the selected word line is a pulsed voltage.
4. The method of claim 3 wherein voltages of the successive pulses are of increasing magnitude.
5. The method of claim 2 wherein the voltage applied to the gate is a pulsed voltage.
6. The method of claim 5 wherein voltages of the successive pulses are of increasing magnitude.
7. The method of claim 1 wherein the method of writing data to the selected memory cell further comprises applying a voltage to the second source/drain terminals of other transistors of the array at least as great as the voltage applied to the selected word line.
8. The method of claim 1 wherein the method of writing data to the selected memory cell further comprises applying a voltage to the second source/drain terminals of other transistors of the array less than the voltage applied to the selected word line.
9. The method of claim 1 wherein the writing of data is a programming step.
10. The method of claim 1 wherein the writing of data is an erase step.
11. The method of claim 1 wherein the diode of each memory cell is provided in the forward direction thereof from a word line to a bit line.
12. The method of claim 1 wherein each resistive memory device is a metal-insulator-metal (MIM) memory device.
13. A method of programming a selected memory cell of a memory array, the array comprising a plurality of word lines, a plurality of bit lines orthogonal to the word lines, a plurality of memory cells each comprising a diode and a resistive memory device in series connecting a word line and a bit line adjacent the intersection thereof, and a plurality of transistors, each having first and second source/drain terminals and a gate, each transistor having its first source/drain terminal connected to a bit line, the method comprising applying a voltage to a selected word line, applying a voltage to the second source/drain terminal of a transistor having its first source/drain terminal connected to a selected bit line, the voltage applied to the selected word line being greater than the voltage applied to the second source/drain terminal of the transistor having its first/source/drain terminal connected to the selected bit line, and applying a voltage to the gate of the transistor having its first source/drain terminal connected to the selected bit line.
14. The method of claim 13 wherein the voltage applied to the selected word line is a pulsed voltage, wherein voltages of the successive pulses are of increasing magnitude.
15. The method of claim 13 wherein each resistive memory device is a metal-insulator-metal (MIM) memory device.
16. The method of claim 15 wherein the method of programming the selected memory cell further comprises applying a voltage to the second source/drain terminals of other transistors of the array at least as great as the voltage applied to the selected word line.
17. The method of claim 15 wherein the method of programming the selected memory cell further comprises applying a voltage to the second source/drain terminals of other transistors of the array less than the voltage applied to the selected word line.
18. A method of erasing a selected memory cell of a memory array, the array comprising a plurality of word lines, a plurality of bit lines orthogonal to the word lines, a plurality of memory cells each comprising a diode and a resistive memory device in series connecting a word line and a bit line adjacent the intersection thereof, and a plurality of transistors, each having first and second source/drain terminals and a gate, each transistor having its first source/drain terminal connected to a bit line, the method comprising applying a voltage to a selected word line, applying a voltage to the second source/drain terminal of a transistor having its first source/drain terminal connected to a selected bit line, the voltage applied to the selected word line being greater than the voltage applied to the second source/drain terminal of the transistor having its first source/drain terminal connected to the selected bit line, and applying a voltage to the gate of the transistor having its first source/drain terminal connected to the selected bit line.
19. The method of claim 18 wherein the voltage applied to the gate of the transistor is a pulsed voltage, wherein voltages of the successive pulses are of increasing magnitude.
20. The method of claim 18 wherein each resistive memory device is a metal-insulator-metal (MIM) memory device.
21. The method of claim 20 wherein the method of erasing the selected memory cell further comprises applying a voltage to the second source/drain terminals of other transistors of the array at least as great as the voltage applied to the selected word line.
22. The method of claim 20 wherein the method of erasing the selected memory cell further comprises applying a voltage to the second source/drain terminals of other transistors of the array less than the voltage applied to the selected word line.
23. The method of claim 13 and further comprising erasing the selected memory cell of the memory array, comprising applying a voltage to the selected word line, applying a voltage to the second source/drain terminal of the transistor having its first source/drain terminal connected to the selected bit line, the voltage applied to the selected word line being greater than the voltage applied to the second source/drain terminal of the transistor having its first source/drain terminal connected to the selected bit line, and applying a voltage to the gate of the transistor having its first source/drain terminal connected to the selected bit line.
24. The method of claim 1 and further comprising said device incorporated in a system.
25. The method of claim 24 wherein the system is selected from the group consisting of a hand-held device, a vehicle, and a computer.