Composite memory material comprising a mixture of phase-change memory material and dielectric material

• US 5,825,046 A
• Filed: 10/28/1996
• Issued: 10/20/1998
• Est. Priority Date: 10/28/1996
• Status: Expired due to Term

• Current Assignee: Ovonyx Memory Technology, LLC
• Original Assignee: Energy Conversion Devices
• Inventors: Czubatyj, Wolodymyr, Ovshinsky, Stanford R., Strand, David A., Klersy, Patrick, Kostylev, Sergey, Pashmakov, Boil
• Primary Examiner(s): Crane, Sara W.
• Application Number:
  US08/739,080
• Time in Patent Office: 722 Days
• Field of Search: 257/2, 257/4, 257/5, 257/77, 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 2213/72 Array wherein the access device being a diode
• CPC Class Codes: H10N 70/026 by physical vapor deposition, e.g. sputtering
• CPC Class Codes: H10N 70/041 Modification of the switching material, e.g. post-treatment, doping
• 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 70/881 Switching materials
• CPC Class Codes: H10N 70/8822 Sulfides, e.g. CuS
• CPC Class Codes: H10N 70/8828 Tellurides, e.g. GeSbTe
• CPC Class Codes: H10N 70/883 Oxides or nitrides
• CPC Class Codes: H10N 70/8833 Binary metal oxides, e.g. TaOx

Abstract

A composite memory material comprising a mixture of active phase-change memory material and inactive dielectric material. The 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. A single cell memory element comprising the aforementioned composite memory material, and a pair of spacedly disposed contacts.

Claims

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

a volume of memory material defining a single-cell memory element comprising a heterogeneous mixture of active phase-change material and inactive dielectric material; and

a pair of spacedly disposed contacts for supplying an electrical signal to said volume of memory material, said contacts providing terminals for reading information stored in and writing information to said memory element.

2. The memory element of claim 1, wherein said phase-change memory 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.

3. The memory element of claim 2, wherein said phase-change memory material includes at least one chalcogen element and at least one transition metal element.

4. The memory element of claim 3, wherein said chalcogen element is selected from the group of Te, Se and mixtures or alloys thereof.

5. The memory element of claim 4, wherein said chalcogen element is a mixture of both Te and Se.

6. The memory element of claim 3, 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.

7. 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.

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

9. The memory element of claim 1, wherein the percentage by volume of said dielectric material is between about 10% and about 90%.

10. The memory element of claim 9, wherein the percentage by volume of said dielectric material is between about 20% and about 80%.

11. The memory element of claim 10, wherein the percentage by volume of said dielectric material is between about 40% and about 60%.

12. An electrically operated, directly overwritable, multibit, single cell memory element comprising:

a volume of memory material defining a single cell memory element, said memory material constituting means for assuming a large dynamic range of electrical resistance values with the ability to be set directly to one of a plurality of resistance values within said dynamic range without the need to be set to a specific starting or erased resistance value, regardless of the previous resistance value of said material in response to a selected electrical input signal so as to provide said single cell with multibit storage capabilities; and

a pair of spacedly disposed contacts for supplying said electrical input signal to set said memory material to a selected resistance value within said dynamic range, wherein at least one of said spacedly disposed contacts is a mixture of a first contact material and a second contact material, wherein said first contact material includes carbon, and wherein said second contact material includes at least one transition metal element.

13. The memory element of claim 12, wherein said second contact material includes one or more elements selected from the group consisting of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W and mixtures or alloys thereof.

14. The memory element of claim 13, wherein said second contact material includes Ti and W.