# US 7,608,849 B2 · Non-volatile switching element, method for manufacturing the same, and integrated circuit having non-volatile switching elements

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- Number: US 7,608,849 B2
- Document ID: US7608849B2
- Status: Granted
- Kind: B2
- Application number: 11/554,808
- Filed: 2006-10-31
- Published: 2007-06-28
- Granted: 2009-10-27
- Earliest claimed: 2005-12-28
- Assignees: Kabushiki Kaisha Toshiba
- Inventors: Tsunehiro Ino; Masato Koyama
- Web page: https://patentgrep.com/patent/US7608849B2

## CPC

- H10N 70/20: Multistable switching devices, e.g. memristors
- H10B 63/80: {Arrangements comprising multiple bistable or multi-stable switching components of the same type on a plane parallel to the substrate, e.g. cross-point arrays}
- H10N 70/823: {adapted for essentially horizontal current flow, e.g. bridge type devices}
- H10N 70/8613: {Heating or cooling means other than resistive heating electrodes, e.g. heater in parallel}
- H10N 70/882: {Compounds of sulfur, selenium or tellurium, e.g. chalcogenides}
- H10N 70/8822: {Sulfides, e.g. CuS}
- H10N 70/883: {Oxides or nitrides}
- H10N 70/8833: {Binary metal oxides, e.g. TaOx}
- H10N 70/8836: {Complex metal oxides, e.g. perovskites, spinels}
- Y10S 257/93: Thermoelectric, e.g. peltier effect cooling
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B: ELECTRONIC MEMORY DEVICES
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

The present invention provides a non-volatile switching element having a novel structure that operates at a high speed and enables high integration, and an integrated circuit that includes such non-volatile switching elements. The switching element includes: a switching film formed on a substrate, made of a material causing a 10 times or greater change in electric resistance with a temperature change within a range of ±80 K from a predetermined temperature; a Peltier element causing the switching film to have the temperature change; a heat conducting/electric insulating film provided between the switching film and the Peltier element, to conduct heat from the Peltier element; and a pair of electrodes connected to the switching film.

## Claims

### Claim 1

A non-volatile switching element comprising:
a switching film formed on a substrate, made of a material causing a 10 times or greater change in electric resistance with a temperature change within a range of ±80 K from a predetermined temperature;
a Peltier element causing the switching film to have the temperature change;
a heat conducting and electric insulating film provided between the switching film and the Peltier element, to conduct heat from the Peltier element; and
a pair of electrodes connected to the switching film.

### Claim 2 (depends on 1)

The non-volatile switching element according to claim 1, wherein the switching film contains a material selected from the group consisting of (V1-xCrx)2O3 wherein 0.0097≦x≦0.0140 and (Ba0.999-xSrx)Ce0.001TiO3 wherein 0.3≦x≦0.4.

### Claim 3 (depends on 1)

The non-volatile switching element according to claim 1, wherein the switching film contains a material selected from the group consisting of (V1-xCrx)2O3 wherein 0.0110≦x≦0.0119and (Ba0.999-xSrx)Ce0.001TiO3 wherein 0.3≦x≦0.4.

### Claim 4 (depends on 1)

The non-volatile switching element according to claim 1, wherein the switching film contains a material selected from the group consisting of (V1-xCrx)2O3 wherein 0≦x≦0.018, (V1-xTix)2O3 wherein 0≦x≦0.052, Ni(S1-xSex)2 wherein 0.26≦x≦0.275, NiS, CuIr2(S1-xSex)4 wherein 0≦x≦0.1, Ti2O3, Fe3O4, EuO1-x wherein 0.0005≦x≦0.004, WO3.0, BaCo0.9Ni0.1S2-x wherein 0.05≦x≦0.20, and Ba0.999-xSrxCe0.001TiO3 wherein 0.3≦x≦0.4.

### Claim 5 (depends on 1)

The non-volatile switching element according to claim 1, wherein the switching film contains a material selected from the group consisting of (V1-xCrx)2O3 wherein 0.0048≦x≦0.0097 and Ba0.999-xSrxCe0.001TiO3 wherein x =0, or 0.3≦x≦0.4.

### Claim 6 (depends on 1)

The non-volatile switching element according to claim 1, wherein the switching film contains a material having the composition of (V1−xCrx)2O3 wherein −0.00007222×T+0.03344−0.0004≦x≦−0.00007222×T+0.03344 +0.0004and where T is an absolute temperature of from 173 K to 403 K.

### Claim 7 (depends on 1)

The non-volatile switching element according to claim 1, wherein the switching element is a normally-on element, and the switching film contains (V1-xCrx)2O3 wherein 0.0093≦x≦0.0097.

### Claim 8 (depends on 1)

The non-volatile switching element according to claim 1, wherein the switching element is a normally-off element, and the switching film contains a material selected from the group consisting of (V1-xCrx)2O3 wherein 0.0140≦x≦0.0150, CuIr2(S1-xSex)4 wherein 0≦x≦0.05, and WO3.0.

### Claim 9 (depends on 1)

The non-volatile switching element according to claim 1, wherein a material of the switching film has a thermal hysteresis.

### Claim 10 (depends on 1)

The non-volatile switching element according to claim 1, wherein the switching film has electric resistivity at predetermined temperature, 10 times or more lower than electric resistance at a temperature 80 K lower than the predetermined temperature, or 10 times or more higher than a temperature 80 K higher than the predetermined temperature.

### Claim 11 (depends on 1)

The non-volatile switching element according to claim 1, wherein:
the heat conducting and electric insulating film is provided to cover the switching film from above;
the Peltier element is located in a region that is immediately above the switching film and is on the heat conducting and electric insulating film; and
the pair of electrodes are provided on both side faces of the switching film.

### Claim 12 (depends on 11)

The non-volatile switching element according to claim 11, further comprising:
at least one of a first insulator and a second insulator, the first insulator being provided between the substrate and the switching film and containing a material with heat conductivity lower than 2.0 (W/mK), and the second insulator covering side faces and a top face of the Peltier element and containing a material with heat conductivity lower than 2.0 (W/mK).

### Claim 13 (depends on 1)

The non-volatile switching element according to claim 1, wherein:
the heat conducting and electric insulating film is provided to cover a lower face, side faces, and a top face of the Peltier element; and
the switching film is provided to cover the heat conducting and electric insulating film.

### Claim 14 (depends on 1)

The non-volatile switching element according to claim 1, wherein:
the heat conducting and electric insulating film is provided to cover a lower face and side faces of the switching film; and
the Peltier element is provided on the side face of the switching film so as to interpose the heat conducting and electric insulating film therebetween.

### Claim 15 (depends on 1)

An integrated circuit comprising:
a plurality of cells arranged in a matrix form, each of the cells having the non-volatile switching element according to claim 1.

### Claim 16 (depends on 15)

The integrated circuit according to claim 15, wherein:
each of the cells includes a pair of first connection electrodes connected to the pair of electrodes, and a pair of second connection electrodes for applying current to the Peltier element,
each of the cells is a memory cell in which the switching element operates as a memory element,
electric power is supplied to the Peltier element of the memory element of at least one of the cells via the second connection electrodes, so as to change the electric resistivity of the switching film to perform writing in the cell, and
current is applied to the switching film via the first connection electrodes, so as to perform reading from the cell.

### Claim 17 (depends on 16)

The integrated circuit according to claim 16, further comprising a mechanism configured to supply electric power so as to cause a temperature change opposite from a temperature change of the Peltier electrode of at least one of the cells, when writing is to be performed in the at least one of the cells, the electric poser being supplied to the Peltier element of each cell adjacent to the cell in which the writing is to be performed.

### Claim 18 (depends on 16)

The integrated circuit according to claim 16, wherein bias power is supplied to the Peltier element of each of the cells so as to set the switching film of each cell at the predetermined temperature.

### Claim 19 (depends on 18)

The integrated circuit according to claim 18, wherein the bias power for setting the switching film at the predetermined temperature is superimposed on power for performing writing on a cell in which writing is to be performed.

### Claim 20

A method for manufacturing a non-volatile switching element, comprising:
forming a switching film on a substrate, the switching film made of a material causing a 10 times or more change in electric resistivity with a temperature change within a range of ±80 K from a predetermined temperature;
forming a heat conducting and electric insulating film on the switching film;
forming a first Peltier electrode film of a first conductivity type on the heat conducting and electric insulating film so as to overlap the switching film;
forming a second Peltier electrode film of a second conductivity type on the first Peltier electrode film so as to overlap the switching film;
forming a Peltier element that includes the first Peltier electrode film and the second Peltier electrode film by pattering the first and second Peltier electrode films;
performing ion implantation to the switching film located on both sides of the Peltier element, so as to form a switching portion at the portion of the switching film that is located immediately below the Peltier element and to which ions are not injected; and
forming electrodes of the switching portion by performing heat treatment to alloy the portion of the switching film to which the ions are injected.

### Claim 21 (depends on 1)

The non-volatile switching element according to claim 1, wherein the heat conducting and electric insulating film is an AIN film.

### Claim 22 (depends on 1)

The non-volatile switching element according to claim 1, wherein the heat conducting and electric insulating film is at least one selected from the group consisting of BN, diamond, Si3N4 and Al2O3.

### Claim 23 (depends on 20)

The method for manufacturing a non-volatile switching element according to claim 20, wherein the heat conducting and electric insulating film is an AIN film.

### Claim 24 (depends on 20)

The method for manufacturing a non-volatile switching element according to claim 20, wherein the heat conducting and electric insulating film is at least one film selected from the group consisting of BN, diamond, Si3N4 and Al2O3.