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Growing Crack Free Single Crystal Films

IP.com Disclosure Number: IPCOM000078583D
Original Publication Date: 1973-Feb-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Chaudhari, P: AUTHOR [+4]

Abstract

Industry now requires that very thin films (of the order of 10,000 Angstroms= 1 mu m) be grown free of deep cracks. The method proposed for achieving this is as follows. A thin film of the order of 1000 Angstroms or less in thickness is made by depositing an amorphous layer of that material, which is the device material used by industry to suit its particular need, onto a single-crystal material which is similar in structure and composition to the crystalline film of the material to be deposited. The amorphous film is then made to crystallize. This is achieved by heating the film and substrate to a temperature high enough for a boundary -- which converts the amorphous material to its crystalline form -- to migrate from the interface between the film and substrate to the free surface of the film.

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Growing Crack Free Single Crystal Films

Industry now requires that very thin films (of the order of 10,000 Angstroms= 1 mu m) be grown free of deep cracks. The method proposed for achieving this is as follows. A thin film of the order of 1000 Angstroms or less in thickness is made by depositing an amorphous layer of that material, which is the device material used by industry to suit its particular need, onto a single-crystal material which is similar in structure and composition to the crystalline film of the material to be deposited. The amorphous film is then made to crystallize. This is achieved by heating the film and substrate to a temperature high enough for a boundary -- which converts the amorphous material to its crystalline form -- to migrate from the interface between the film and substrate to the free surface of the film. If cracks form during this heat treatment this does not matter. The process described ensures that they are later filled.

Next, a second 1000 Angstrom thick film, of the same material as the first, is deposited in amorphous form onto the first now crystalline film. This new film partly fills the cracks formed in the first one, as shown in the figure. The substrate, film 1 and film 2 are now heated once more to convert film 2 into its crystalline form. Film 2 may crack during this process, but if it does the cracks are partly filled by a third film placed on the second. If a film 1 micron thick is required, then ten 1000 Angstroms fi...