PHASE CHANGE MEMORY DEVICES, METHOD FOR ENCODING, AND METHODS FOR STORING DATA

• US 20130155766A1
• Filed: 12/17/2012
• Published: 06/20/2013
• Est. Priority Date: 12/16/2011
• Status: Active Grant

• Current Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Original Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Inventors: LIU, Zhiyong
• Granted Patent: US 9,093,141 B2
• Time in Patent Office: Days
• US Class Current: 365/163
• CPC Class Codes: G11B 9/04 using record carriers having variable electric resistance; Record carriers therefor
• CPC Class Codes: G11C 13/0004 comprising amorphous/crystalline phase transition cells
• CPC Class Codes: G11C 13/0069 Writing or programming circuits or methods
• CPC Class Codes: G11C 2013/008 Write by generating heat in the surroundings of the memory material, e.g. thermowrite
• CPC Class Codes: H10N 70/231 based on solid-state phase change, e.g. between amorphous and crystalline phases, Ovshinsky effect
• CPC Class Codes: H10N 70/257 based on radiation or particle beam assisted switching, e.g. optically controlled devices
• CPC Class Codes: H10N 70/826 adapted for essentially vertical current flow, e.g. sandwich or pillar type devices
• CPC Class Codes: H10N 70/8613 Heating or cooling means other than resistive heating electrodes, e.g. heater in parallel
• CPC Class Codes: H10N 70/8828 Tellurides, e.g. GeSbTe

Abstract

Phase change memory cells including a phase change media can be encoded using a source of energy that is not integral with the memory cell. External sources of energy include thermal heads, such as those used in direct thermal printing or thermal transfer printing and sources of electromagnetic radiation, such as lasers. Such types of phase change memory devices can be associated with substrates that include thermochromic materials or are suitable for thermal transfer printing so that the memory cells can be encoded and print media applied to the substrate using the same source of thermal energy.

Claims

1. A phase-change memory device comprising:

a memory cell including a phase change media having a crystallization temperature and a melting temperature;

a first electrically conductive member beneath the phase change media, and a second electrically conductive member above the phase change media; and

a substrate associated with the memory cell, wherein the memory cell is free of a resistive material configured to emit thermal energy in response to flow of electric current through the resistive material and increase the temperature of the phase change media by transferring at least a portion of the emitted thermal energy to the phase change media.

2. The memory device of claim 1, wherein the phase change media comprises a chalcogenide.

3. The memory device of claim 1, wherein the phase change media is a chalcogenide alloy including elements selected from tellurium, germanium, antimony, and sulfur.

4. The memory device of claim 1, further comprising a plurality of additional memory cells.

5. The memory device of claim 4, wherein the substrate is a semiconductive material.

6. The memory device of claim 4 wherein the substrate further comprises a thermochromic media.

7. The memory device of claim 4, wherein the substrate further comprises a thermal transfer print media.

8. The memory device of claim 5, wherein the substrate further comprises a thermochromic media or a thermal transfer print media.

9. A device for changing the state of a phase change media in a phase-change memory cell associated with a substrate, the device comprising:

an energy source selectively operable to increase the temperature of the substrate to a degree sufficient to increase the temperature of the phase change media to above its crystallization temperature or its melting temperature;

a transport assembly selectively operable to impart relative movement between the energy source and the substrate; and

a control circuit communicatively coupled to control an amount of energy generated by the energy source and a position of the energy source relative to the substrate to control the transfer of energy from the energy source to the substrate.

10. The device of claim 9, wherein the energy source is a source of thermal energy.

11. The device of claim 10, wherein the source of thermal energy is a thermal print head or a thermal transfer print head.

12. The device of claim 9, wherein the energy source is a source of electromagnetic radiation.

13. The device of claim 9, wherein the transport assembly is configured to move the substrate relative to the energy source.

14. The device of claim 9, wherein the transport assembly is configured to move the energy source relative to the substrate.

15. A method of changing the state of a phase change media in a phase-change memory cell associated with a substrate, the method comprising:

positioning the substrate adjacent to an energy source;

causing the energy source to increase the temperature of the substrate;

transferring thermal energy resulting from the increase in temperature of the substrate to the phase change media;

increasing the temperature of the phase change media in the absence of an input of thermal energy from a source other than the energy source; and

changing the phase change media from an amorphous state to a crystalline state or from a crystalline state to an amorphous state.

16. The method of claim 15, wherein causing the energy source to increase the temperature of the substrate further comprises contacting the substrate with a source of thermal energy.

17. The method of claim 15, wherein causing the energy source to increase the temperature of the substrate further comprises irradiating at least a portion of the substrate with electromagnetic energy.

18. The method of claim 15, further comprising applying a print media to the substrate.

19. A method of storing retrievable data comprising:

positioning a substrate associated with a plurality of memory cells adjacent an energy source by moving the substrate and energy source relative to each other, wherein each memory cell includes a phase change media having a crystalline state and an amorphous state, a first electrically conductive member beneath the phase change media, and a second electrically conductive member above the phase change media;

causing the energy source to increase the temperature of the substrate by transferring energy from the energy source to the substrate;

transferring thermal energy resulting from the increase in the temperature of the substrate to the phase change media; and

changing the phase change media from an amorphous state to a crystalline state or from a crystalline state to an amorphous state.

20. The method of claim 19, wherein causing the energy source to increase the temperature of the substrate further comprises contacting the substrate with a source of thermal energy.

21. The method of claim 19, wherein causing the energy source to increase the temperature of the substrate further comprises irradiating the substrate with electromagnetic energy.

22. The method of claim 19, further comprising applying print media to the substrate.