# US 4,400,445 A · Liquid phase epitaxial growth of garnet films

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- Number: US 4,400,445 A
- Document ID: US4400445A
- Status: Granted
- Kind: A
- Application number: 06/322,677
- Filed: 1981-11-18
- Granted: 1983-08-23
- Earliest claimed: 1980-06-30
- Assignees: Bell Telephone Laboratories, Incorporated
- Inventors: George W. Berkstresser; Stuart L. Blank
- Web page: https://patentgrep.com/patent/US4400445A

## CPC

- C30B 19/02: using molten solvents, e.g. flux
- C30B 29/28: with formula A3Me5O12 wherein A is a rare earth metal and Me is Fe, Ga, Sc, Cr, Co or Al, e.g. garnets
- 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

The manufacture of magnetic bubble devices typically involves a step of epitaxially depositing a layer of a garnet material on a substrate having suitable lattice parameters, e.g., layers of certain rare earth-iron garnets are conveniently deposited on a gallium-gadolinium garnet substrate. Deposition by liquid epitaxy has been preferred and, in particular, deposition from a melt comprising garnet materials in a PbO--B.sub.2 O.sub.3 flux. According to the invention, garnet layers are epitaxially grown from a melt comprising a PbO--V.sub.2 O.sub.5 flux. Growth from such melt has desirably slow kinetics, resulting in slow deposition as is beneficial especially for the growth of layers on an assembly of substrates. Additional benefits are ease of removal of liquid droplets remaining on a grown film upon removal from the melt, both by spinning and by rinsing.

## Claims

### Claim 1

Method for making a magnetic bubble device comprising a layer of a garnet material which is epitaxially deposited on a surface of a supporting substrate, said method comprising
(1) heating a preferred melt consisting essentially of said garnet material and a flux material at a temperature corresponding to supercooling of said garnet material, said flux material comprising PbO and V.sub.2 O.sub.5, PbO being comprised in said flux material in an amount in the range of 67-99 molecular percent, and V.sub.2 O.sub.5 being comprised in said flux material in an amount of at least 50 molecular percent of the molecular percent complementary to the molecular percent PbO,
(2) bringing at least said surface of said substrate in contact with said melt, and
(3) removing said substrate from contact with said melt upon deposition of said layer on said surface,
whereby said deposition is at a desired rate per degree C. of supercooling, said desired rate being less than or equal to 0.53 times a comparison rate, said comparison rate being the rate per degree C. of supercooling when said garnet material is deposited from a comparison melt, said comparison melt consisting essentially of a PbO-B.sub.2 O.sub.3 flux and garnet constituent oxides, the B.sub.2 O.sub.3 :PbO molecular ratio in said comparison melt being 1:15.6, and the molecular ratio of yttrium oxide or its substituents versus iron oxide or its substituents being such that said garnet material is deposited from said comparison melt.

### Claim 2 (depends on 1)

Method of claim 1 in which PbO is comprised in said flux material in an amount in the range of 85-95 molecular percent.

### Claim 3 (depends on 1)

Method of claim 1 in which said garnet material is magnetic.

### Claim 4 (depends on 1)

Method of claim 1 in which heating is at a temperature which corresponds to supercooling of said garnet material by at least 3 degrees C.

### Claim 5 (depends on 1)

Method of claim 1 in which said layer has a thickness which is less than or equal to 2 micrometers.

### Claim 6 (depends on 1)

Article of manufacture comprising a magnetic bubble device made according to the method of claim 1.