Two-terminal reversibly switchable memory device

• US 10,224,480 B2
• Filed: 10/30/2017
• Issued: 03/05/2019
• Est. Priority Date: 02/06/2004
• Status: Active Grant

• Current Assignee: Hefei Reliance Memory Limited
• Original Assignee: Hefei Reliance Memory Limited
• Inventors: Rinerson, Darrell, Chevallier, Christophe J., Kinney, Wayne, Lambertson, Roy, Sanchez, Jr., John E., Schloss, Lawrence, Swab, Philip, Ward, Edmond
• Primary Examiner(s): Fan, Bo
• Application Number:
  US15/797,452
• Publication Number:
  US 20180130946A1
• Time in Patent Office: 491 Days
• Field of Search: 257 4, 365148, 365 51, 365185
• CPC Class Codes: G06F 30/30 Circuit design
• CPC Class Codes: G11C 11/5685 using storage elements comprising metal oxide memory material, e.g. perovskites
• CPC Class Codes: G11C 13/0007 comprising metal oxide memory material, e.g. perovskites
• CPC Class Codes: G11C 13/0009 RRAM elements whose operation depends upon chemical change
• CPC Class Codes: G11C 13/004 Reading or sensing circuits or methods
• CPC Class Codes: G11C 13/0069 Writing or programming circuits or methods
• CPC Class Codes: G11C 2013/0045 Read using current through the cell
• CPC Class Codes: G11C 2013/005 Read using potential difference applied between cell electrodes
• CPC Class Codes: G11C 2013/009 Write using potential difference applied between cell electrodes
• CPC Class Codes: G11C 2213/11 Metal ion trapping, i.e. using memory material including cavities, pores or spaces in form of tunnels or channels wherein metal ions can be trapped but do not react and form an electro-deposit creating filaments or dendrites
• CPC Class Codes: G11C 2213/31 Material having complex metal oxide, e.g. perovskite structure
• CPC Class Codes: G11C 2213/32 Material having simple binary metal oxide structure
• CPC Class Codes: G11C 2213/53 Structure wherein the resistive material being in a transistor, e.g. gate
• CPC Class Codes: G11C 2213/54 Structure including a tunneling barrier layer, the memory effect implying the modification of tunnel barrier conductivity
• CPC Class Codes: G11C 2213/56 Structure including two electrodes, a memory active layer and a so called passive or source or reservoir layer which is NOT an electrode, wherein the passive or source or reservoir layer is a source of ions which migrate afterwards in the memory active layer to be only trapped there, to form conductive filaments there or to react with the material of the memory active layer in redox way
• CPC Class Codes: G11C 2213/71 Three dimensional array
• CPC Class Codes: G11C 2213/79 Array wherein the access device being a transistor
• CPC Class Codes: H10B 63/30 comprising selection components having three or more electrodes, e.g. transistors
• CPC Class Codes: H10B 63/84 arranged in a direction perpendicular to the substrate, e.g. 3D cell arrays
• CPC Class Codes: H10N 70/026 by physical vapor deposition, e.g. sputtering
• CPC Class Codes: H10N 70/24 : based on migration or redistribution of ionic species, e.g. anions, vacancies
• CPC Class Codes: H10N 70/245 : the species being metal cations, e.g. programmable metallization cells
• 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 70/841 : Electrodes
• CPC Class Codes: H10N 70/8833 : Binary metal oxides, e.g. TaOx
• CPC Class Codes: H10N 70/8836 : Complex metal oxides, e.g. perovskites, spinels

Abstract

A memory using mixed valence conductive oxides is disclosed. The memory includes a mixed valence conductive oxide that is less conductive in its oxygen deficient state and a mixed electronic ionic conductor that is an electrolyte to oxygen and promotes an electric filed to cause oxygen ionic motion.

Claims

1. An apparatus, comprising:

a first electrode;

a second electrode; and

a memory element (ME) positioned between the first electrode and the second electrode, the ME electrically coupled in series with the first and second electrodes, the ME comprising;

a mixed valence oxide in contact with the first electrode;

a mixed electronic ionic conductor in contact with the mixed valence oxide; and

a repository in contact with the mixed electronic ionic conductor and the second electrode, wherein a conductivity of the ME changes in response to a first voltage applied across the first electrode and the second electrode.

2. The apparatus of claim 1, wherein the conductivity of the ME can be reversibly switched between a first conductivity and a second conductivity that is less than the first conductivity as a function of ion deficiency.

3. The apparatus of claim 1, wherein the mixed valence oxide comprises a crystalline structure.

4. The apparatus of claim 3, wherein the crystalline structure comprises a single crystalline structure.

5. The apparatus of claim 1, wherein the mixed valence oxide maintains crystallinity in a plurality of valence states.

6. The apparatus of claim 1, wherein the repository comprises an oxygen repository.

7. The apparatus of claim 1, wherein the mixed electronic ionic conductor comprises an electrolyte and is permeable to ions from the mixed valence oxide responsive to the first voltage applied across the first electrode and the second electrode.

8. The apparatus of claim 1, wherein mobile ions in the mixed valence oxide are operative to change the conductivity of the mixed valence oxide from a higher conductivity to a lower conductivity responsive to the mobile ions being transported into the repository or from the lower conductivity to the higher conductivity responsive to the mobile ions being transported back into the mixed valence oxide.

9. The apparatus of claim 1, further comprising:

a line coupled to the first electrode; and

a component coupled to the line, the component configured to energize the line to apply a second voltage across the first electrode and the second electrode, the second voltage operative to generate a read current having a magnitude that is indicative of a present conductivity of the ME, wherein applying the second voltage is non-destructive to the present conductivity of the ME, wherein the present conductivity is indicative of stored data.

10. The apparatus of claim 9, wherein a magnitude of the second voltage is less than a magnitude of the first voltage.

11. The apparatus of claim 1, the mixed valence oxide comprises mobile oxygen ions.

12. The apparatus of claim 1, wherein the mixed valence oxide comprises perovskite conductive metal oxide.

13. The apparatus of claim 1, wherein the electronic ionic conductor comprises aluminum oxide.

14. An apparatus, comprising:

a first electrode;

a second electrode; and

a memory element (ME) positioned between the first electrode and the second electrode, the ME electrically coupled in series with the first electrode and the second electrode, the ME comprising;

a mixed valence oxide coupled with the first electrode; and

a mixed electronic ionic conductor coupled with the mixed valence oxide and the second electrode, wherein a conductivity of the ME changes responsive to a first voltage applied across the first electrode and the second electrode;

wherein responsive to the first voltage the mixed electronic ionic conductor holds ions from the mixed valence oxide.

15. The apparatus of claim 14, wherein responsive to a second voltage applied across the first electrode and the second electrode of an opposite polarity from the first voltage, the ions held in the mixed electronic ionic conductor return to the mixed valence oxide.

16. The apparatus of claim 14, wherein the conductivity of the ME can be reversibly switched between a first conductivity and a second conductivity that is less than the first conductivity as a function of ion deficiency.

17. The apparatus of claim 14, further comprising:

a line coupled to the first electrode; and

a component coupled to the line, the component configured to energize the line to apply a second voltage across the first electrode and the second electrode, the second voltage operative to generate a read current having a magnitude that is indicative of a present conductivity of the ME, wherein applying the second voltage is non-destructive to the present conductivity of the ME.

18. A memory device comprising:

array of memory cells arranged in a plurality of lines in a first direction and a plurality of lines in a second direction, wherein each memory cell of the array comprises;

a first electrode;

a second electrode; and

a memory element (ME) positioned between the first electrode and the second electrode, the ME electrically coupled in series with the first electrode and the second electrode, the ME comprising;

a mixed valence oxide coupled with the first electrode; and

a mixed electronic ionic conductor coupled with the mixed valence oxide and the second electrode, wherein a conductivity of the ME changes responsive to a first voltage applied across the first electrode and the second electrode;

wherein responsive to the first voltage the mixed electronic ionic conductor holds ions from the mixed valence oxide.