# US 7,611,913 B2 · Ferroelectric rare-earth manganese-titanium oxides

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- Number: US 7,611,913 B2
- Document ID: US7611913B2
- Status: Granted
- Kind: B2
- Application number: 11/821,244
- Filed: 2007-06-22
- Published: 2007-10-25
- Granted: 2009-11-03
- Earliest claimed: 2003-09-04
- Assignees: Intematix Corporation
- Inventors: Yi-Qun Li; Young Yoo; Qizhen Xue; Ning Wang; Daesig Kim
- Web page: https://patentgrep.com/patent/US7611913B2

## CPC

- H10D 64/033: {comprising ferroelectric layers}
- C30B 29/22: Complex oxides
- C30B 29/24: with formula AMeO3, wherein A is a rare earth metal and Me is Fe, Ga, Sc, Cr, Co or Al, e.g. ortho ferrites
- H10P 14/69398: {the material having a perovskite structure, e.g. BaTiO3}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Ferroelectric rare-earth manganese-titanium oxides and methods of their manufacture. The ferroelectric materials can provide nonvolatile data storage in rapid access memory devices.

## Claims

### Claim 1

A method of preparing a ferroelectric material, said method comprising:
forming one or more layers on a substrate, the one or more layers comprising: Y, A, Mn, and B in a proportion according to the formula (Y1−xAx)(Mn1−yBy), wherein A comprises a metal having a valence of 3 and 0<x<1, and B comprises a metal having a valence of 4 or 3 and 0<y<1;
heating the layers to a temperature ranging from about 600° C. to about 800° C.; and,
providing an atmosphere comprising oxygen, said atmosphere having a pressure of less than 10−3 torr;
crystallizing the layers in the atmosphere at the temperature to form the ferroelectric material.

### Claim 2 (depends on 1)

The method of claim 1, wherein said forming layers comprises: ion beam sputtering, magnetron sputtering, pulsed laser deposition (PLD), MOCVD, MBE or EB.

### Claim 3 (depends on 1)

The method of claim 1, wherein the substrate comprises: Si, Ge, GaAs, GaN, Al2O3, SiC or AlN.

### Claim 4 (depends on 1)

The method of claim 1, wherein the B metal comprises: Ti, Cr or V.

### Claim 5 (depends on 1)

The method of claim 1, wherein the temperature comprises about 650° C. or less.

### Claim 6 (depends on 1)

The method of claim 1, wherein the atmosphere further comprises an inert gas.

### Claim 7 (depends on 6)

The method of claim 6, wherein the atmosphere comprises argon (Ar) and oxygen (O2) in a ratio less than 1:1.

### Claim 8 (depends on 6)

The method of claim 6, wherein the atmosphere comprises a pressure of 10−4 torr or less.

### Claim 9 (depends on 1)

The method of claim 1, further comprising depositing a Pt electrode on the substrate before forming the one or more layers.

### Claim 10 (depends on 1)

The method of claim 1, wherein the ferroelectric material crystallizes epitaxially in an orientation of (0004).

### Claim 11 (depends on 1)

The method of claim 1, wherein the ferroelectric material has the formula Y(Mn1−yTiy)O3 wherein y ranges from about 0.005 to about 1.

### Claim 12 (depends on 1)

The method of claim 1, wherein y ranges from about 0.35 to about 0.65.

### Claim 13 (depends on 1)

The method of claim 1, further comprising post-annealing the crystallized layers in vacuum of about 10−6 torr or less.

### Claim 14 (depends on 1)

The method of claim 1, wherein the atmosphere has a pressure of less than 10−3 torr.

### Claim 15 (depends on 1)

The method of claim 1, wherein said crystallization takes place in the atmosphere having a pressure of about 10−3 torr or less and at the temperature ranging from about 600° C. to about 800° C.

### Claim 16 (depends on 1)

The method of claim 1, wherein the layers are not heated to above 650° C.

### Claim 17 (depends on 1)

The method of claim 1, further comprising holding the temperature in the range for at least an hour.

### Claim 18 (depends on 1)

The method of claim 1, wherein said heating the layers is accomplished by heating the substrate.