Two-terminal reversibly switchable memory device

Patent metadata

Field	Value
Publication number	US-10224480-B2
Application number	US-201715797452-A
Country	US
Kind code	B2
Filing date	Oct 30, 2017
Priority date	Feb 6, 2004
Publication date	Mar 5, 2019
Grant date	Mar 5, 2019

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.

First claim

The invention claimed is:

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.

Assignees

• Hefei Reliance Memory Ltd

Inventors

• Rinerson Darrell
• Chevallier Christophe J
• Kinney Wayne
• Lambertson Roy
• Sanchez Jr John E
• Schloss Lawrence
• Swab Philip
• Ward Edmond

Classifications

• G11C2213/31

  Material having complex metal oxide, e.g. perovskite structure · CPC title

• G11C2213/54

  Structure including a tunneling barrier layer, the memory effect implying the modification of tunnel barrier conductivity · CPC title

• G06F30/30

  Circuit design · CPC title

• G11C13/0009

  RRAM elements whose operation depends upon chemical change · CPC title

• G11C13/0069

  Writing or programming circuits or methods · CPC title