Memory element with memory material comprising phase-change material and dielectric material

• US 6,087,674 A
• Filed: 04/20/1998
• Issued: 07/11/2000
• Est. Priority Date: 10/28/1996
• Status: Expired

• Current Assignee: Ovonyx Memory Technology, LLC (Micron Technology, Inc.)
• Original Assignee: Energy Conversion Devices
• Inventors: Kostylev, Sergey, Pashmakov, Boil, Ovshinsky, Standford R., Czubatyj, Wolodymyr, Strand, David A., Klersy, Patrick J.
• Primary Examiner(s): CRANE, SARA W
• Application Number:
  US09/063,174
• Time in Patent Office: 813 Days
• Field of Search: 257/1, 257/2, 257/3, 257/4, 257/5, 257/50, 365/163
• US Class Current: 257/2
• CPC Class Codes: G11C 13/0004 comprising amorphous/crystalline phase transition cells
• CPC Class Codes: G11C 2213/35 Material including carbon, e.g. graphite, grapheme
• CPC Class Codes: G11C 2213/51 Structure including a barrier layer preventing or limiting migration, diffusion of ions or charges or formation of electrolytes near an electrode
• CPC Class Codes: G11C 2213/52 Structure characterized by the electrode material, shape, etc.
• CPC Class Codes: G11C 2213/72 Array wherein the access device being a diode
• 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 70/826 adapted for essentially vertical current flow, e.g. sandwich or pillar type devices
• CPC Class Codes: H10N 70/828 Current flow limiting means within the switching material region, e.g. constrictions
• CPC Class Codes: H10N 70/8418 adapted for focusing electric field or current, e.g. tip-shaped
• CPC Class Codes: H10N 70/8828 Tellurides, e.g. GeSbTe

Abstract

An electrically operated, single cell memory element comprising: a volume of memory material defining a single-cell memory element, the memory material comprising a heterogeneous mixture of a phase-change material and a dielectric material; and means for delivering an electrical signal to at least a portion of the volume of memory material. An electrically operated, single-cell memory element comprising: a volume of memory material defining the single-cell memory element, the memory material comprising a phase-change material and a dielectric material where the phase-change material has a plurality of detectable resistivity values and can be set directly to one of the resistivity values without the need to be set to a specific starting or erased resistivity value, regardless of the previous resistivity value of the material, in response to an electrical signal; and means for delivering the electrical signal to at least a portion of the volume of memory material.

Claims

1. An electrically operated, single-cell memory element comprising:

a volume of memory material comprising a heterogeneous mixture of a phase-change material and a dielectric material, said phase-change material programmable to a plurality of detectable resistivity values in response to an electrical signal, said dielectric material being between about 60 and 90 percent of said volume of memory material; and

means for delivering said electrical signal to at least a portion of said volume of memory material.

2. The memory element of claim 1, wherein said phase-change material can be set directly to one of said resistivity values without the need to be set to a specific starting or erased resistivity value, regardless of the previous resistivity value of said material, in response to said electrical signal.

3. The memory element of claim 1, wherein said phase-change material includes one or more elements selected from the group consisting of Te, Se, Ge, Sb, Bi, Pb, Sn, As, S, Si, P, O and mixtures or alloys thereof.

4. The memory element of claim 3, wherein said phase-change material includes at least one chalcogen element and at least one transition metal element.

5. The memory element of claim 4, wherein said chalcogen element is selected from the group of Te, Se and mixtures or alloys thereof.

6. The memory element of claim 5, wherein said chalcogen element is a mixture of both Te and Se.

7. The memory element of claim 4, wherein said at least one transition metal element is selected from the group consisting of Cr, Fe, Ni, Nb, Pd, Pt and mixtures or alloys thereof.

8. The memory element of claim 1, wherein said dielectric material is one or more materials selected from the group consisting of oxides, nitrides, fluorides, sulfides, chlorides, carbides, oxynitrides, carboxynitrides, borides, phosphides and mixtures or alloys thereof.

9. The memory element of claim 1, wherein said dielectric material is an organic dielectric material.

10. The memory element of claim 1, wherein said means for delivering is a first contact and a second contact adjoining said volume of memory material.

11. The memory element of claim 1, wherein said means for delivering comprises at least one tapered contact, said tapered contact tapering to a peak adjoining said volume of memory material.

12. The memory element of claim 1, wherein said means for delivering comprises at least one field emitter positioned in close proximity to said volume of memory material.

13. The memory element of claim 1, wherein said means for delivering comprises at least one field emitter positioned within the tunneling distance of said volume of memory material.

14. The memory element of claim 2, wherein said phase-change material has two detectable resistivity values.

15. The memory element of claim 2, wherein said phase-change material has at least three detectable resistivity values.