Programmable Resistance Memory

• US 20110211391A1
• Filed: 05/10/2011
• Published: 09/01/2011
• Est. Priority Date: 03/10/2009
• Status: Active Grant

• Current Assignee: Ovonyx Memory Technology, LLC (Micron Technology, Inc.)
• Original Assignee: Ovonyx Incorporated (Micron Technology, Inc.)
• Inventors: Parkinson, Ward
• Granted Patent: US 8,792,270 B2
• Time in Patent Office: Days
• US Class Current: 365/163
• CPC Class Codes: G11C 11/56 using storage elements with more than two stable states represented by steps, e.g. of voltage, current, phase, frequency
• CPC Class Codes: G11C 11/5678 using amorphous/crystalline phase transition storage elements
• CPC Class Codes: G11C 13/0004 comprising amorphous/crystalline phase transition cells
• CPC Class Codes: G11C 13/004 Reading or sensing circuits or methods
• CPC Class Codes: G11C 13/0061 Timing circuits or methods
• CPC Class Codes: G11C 13/0069 Writing or programming circuits or methods
• CPC Class Codes: G11C 16/32 Timing circuits
• CPC Class Codes: G11C 2013/0092 Write characterized by the shape, e.g. form, length, amplitude of the write pulse
• CPC Class Codes: G11C 27/005 with non-volatile charge storage, e.g. on floating gate or MNOS
• CPC Class Codes: G11C 29/00 Checking stores for correct operation ; Subsequent repair; Testing stores during standby or offline operation
• CPC Class Codes: G11C 29/021 in voltage or current generators
• CPC Class Codes: G11C 29/028 with adaption or trimming of parameters
• CPC Class Codes: G11C 29/50 Marginal testing, e.g. race, voltage or current testing
• CPC Class Codes: G11C 29/50008 of impedance
• CPC Class Codes: G11C 29/52 Protection of memory contents; Detection of errors in memory contents
• CPC Class Codes: G11C 7/16 Storage of analogue signals in digital stores using an arrangement comprising analogue/digital [A/D] converters, digital memories and digital/analogue [D/A] converters

Abstract

A memory includes an interface through which it provides access to memory cells, such as phase change memory cells. Such access permits circuitry located on a separate integrated circuit to provide access signals, including read and write signals suitable for binary or multi-level accesses.

Claims

1. A method of operating an electronic device comprising:

providing a first conductive line;

providing a second conductive line;

coupling an access device and a programmable resistance device in series between said first conductive line and said second conductive line;

applying a first electrical pulse to said first conductive line, said first electrical pulse increasing the magnitude of the voltage of said first conductive line;

monitoring the voltage of said first conductive line;

detecting a decrease in the magnitude of the voltage of said first conductive line, said decrease occurring at a first time;

detecting the voltage of said first conductive line at said first time;

terminating said first electrical pulse; and

applying a second electrical pulse to said first conductive line, said second electrical pulse forcing a first voltage on said first conductive line, said first voltage having a magnitude greater than or equal to the magnitude of said voltage detected at said first time.

2. The method of claim 1, wherein said access device is a threshold switching device.

3. The method of claim 1, wherein said access device is a diode.

4. The method of claim 1, wherein said programmable resistance device is a memory device.

5. The method of claim 4, wherein said memory device is a phase-change device.

6. The method of claim 1, wherein said monitoring voltage comprises directing a current from said first conductive line to a capacitor.

7. The method of claim 6, further comprising comparing the rate of change of said voltage of said first conductive line to a first reference rate of voltage change.

8. The method of claim 7, further comprising comparing the rate of change of said voltage of said first conductive line to a second reference rate of voltage change.

9. The method of claim 1, wherein said decrease in the magnitude of said voltage of said first conductive line is detected as a decrease in the rate of charging of said first conductive line.

10. The method of claim 9, wherein said decrease in the rate of charging of said first conductive line is discontinuous.

11. The method of claim 1, wherein said first electrical pulse causes said access device to transform from a resistive state to a conductive state.

12. The method of claim 9, wherein said transformation occurs at said first time.

13. The method of claim 1, wherein said decrease in said magnitude of said voltage of said first conductive line is discontinuous.

14. The method of claim 1, wherein said terminating said first electrical pulse includes directing current from said first electrical pulse to a quench transistor.

15. The method of claim 1, further comprising measuring the current passing between said first conductive line and said second conductive line.

16. The method of claim 15, wherein the current is the current produced by said first voltage.

17. The method of claim 16, further comprising computing the ratio of said first voltage to said current produced by said first voltage.

18. The method of claim 1, further comprising applying a third electrical pulse to said first conductive line, said third electrical pulse forcing a second voltage on said first conductive line, said second voltage differing from said first voltage and having a magnitude greater than or equal to the magnitude of said voltage detected at said first time.

19. The method of claim 18, wherein said first voltage causes a first current to pass between said first conductive line and said second conductive line and said second voltage causes a second current to pass between said first conductive line and said second conductive line and wherein said method further comprises determining the difference between said first current and said second current.

20. The method of claim 19, further comprising determining the difference between said first voltage and said second voltage

21. The method of claim 20, further comprising determining the ratio of said difference between said first voltage and said second voltage to said difference between said first current and said second current.

22. The method of claim 1, further comprising terminating said first electrical pulse if said magnitude of said voltage of said first conductive line reaches a pre-determined voltage.

23. The method of claim 22, wherein said pre-determined voltage is a voltage sufficient to induce a change in the resistance of said programmable resistance device.

24. The method of claim 1, wherein said first voltage is insufficient to alter the state of said programmable resistance device.

25. A method of operating an electronic device comprising:

providing a first conductive line;

providing a second conductive line;

coupling an access device and a programmable resistance device in series between said first conductive line and said second conductive line, said access device having a threshold voltage, said access device switching from a resistive state to a conductive state upon application of said threshold voltage; and

detecting the state of said programmable resistance device with an electrical pulse, said electrical pulse producing a voltage across said access device, said voltage being less than said threshold voltage.