# US 5,350,606 A · Single crystal ferroelectric barium titanate films

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- Number: US 5,350,606 A
- Document ID: US5350606A
- Status: Granted
- Kind: A
- Application number: 08/074,159
- Filed: 1993-06-09
- Granted: 1994-09-27
- Earliest claimed: 1989-03-30
- Assignees: Kanegafuchi Chemical Industry Co., Ltd.; Nippon Steel Corporation; NEC Corporation; Seisan Kaihatsu Kagaku Kenkyusho
- Inventors: Toshio Takada; Takahito Terashima; Kenji Iijima; Kazunuki Yamamoto; Kazuto Hirata; Yoshichika Bando
- Web page: https://patentgrep.com/patent/US5350606A

## CPC

- C30B 23/02: Epitaxial-layer growth
- C30B 29/32: Titanates; Germanates; Molybdates; Tungstates
- 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

## Abstract

A ferroelectric thin film consisting of a single crystal of BaTiO.sub.3 which has a perovskite structure is produced by a method comprising evaporating Ba and Ti in an atomic ratio of 1:1 from discrete evaporation sources of Ba and Ti to deposit them on a substrate in a vacuum deposition vessel while supplying a small amount of an oxygen gas to the reactor.

## Claims

### Claim 1

A method for producing a substantially single crystal ferroelectric thin film having a thickness of not larger than 1 .mu.m, which method comprises evaporating Ba and Ti in an atomic ratio of 1:1 from discrete evaporation sources of Ba and Ti to deposit the evaporated Ba and Ti on a substrate in a vacuum deposition vessel while supplying oxygen gas in an amount sufficient to maintain oxygen pressure within the vessel between 10.sup.-5 and 10.sup.-3 Torr.

### Claim 2 (depends on 1)

The method according to claim 1, wherein a plasma is generated during evaporation of Ba and Ti and deposition of BaTiO.sub.3 on the substrate.

### Claim 3 (depends on 1)

The method according to claim 1, wherein said oxygen gas is supplied towards the substrate surface to form an oxygen-containing atmosphere having a relatively high pressure near the substrate.

### Claim 4 (depends on 1)

The method according to claim 1, wherein a single crystal is used as the substrate with its (001) plane forming the substrate surface.

### Claim 5 (depends on 1)

The method according to claim 1, wherein a single crystal is used as the substrate with its (110) plane forming the substrate surface.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the substrate is heated at a temperature not lower than 500.degree. C.

### Claim 7 (depends on 1)

The method according to claim 1, wherein a deposition rate of BaTiO.sub.3 is 4 .ANG./sec. or less.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the ferroelectric thin film thus produced comprises a single crystal of BaTiO.sub.3 having a perovskite structure.

### Claim 9 (depends on 6)

The method according to claim 6, wherein the ferroelectric thin film thus produced consists of a single crystal of BaTiO.sub.3 having a perovskite structure.