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Fabricating Isolated Device Quality Semiconductor Film Areas in a Foreign Substrate Using Laser Melting

IP.com Disclosure Number: IPCOM000081078D
Original Publication Date: 1974-Mar-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Hutchins, GL: AUTHOR [+2]

Abstract

The described process is directed to fabricating relatively cheap, large-area arrays of isolated semiconductor film regions on insulating substrates with sufficient material quality (good carrier mobilities and/or lifetimes), so as to be useful for device applications.

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Fabricating Isolated Device Quality Semiconductor Film Areas in a Foreign Substrate Using Laser Melting

The described process is directed to fabricating relatively cheap, large-area arrays of isolated semiconductor film regions on insulating substrates with sufficient material quality (good carrier mobilities and/or lifetimes), so as to be useful for device applications.

The process involves depositing a film of semiconductor material on a suitable insulating substrate, with the film being amorphous and/or "micro- polycrystalline" and, in general, not of device quality. The film of semiconductor material may be deposited by evaporation, sputtering, chemical vapor deposition, or the like, to a suitable thickness of, for example, 1 micrometer. Any of a variety of dopants may be incorporated either during deposition, on afterwards, for example, by diffusion or ion implantation.

A high-intensity laser beam is then employed to selectively traverse along the surface of the film of semiconductor material, and the energy is absorbed within the film, causing it to be heated locally. The beam is swept slowly enough to add sufficient heat to the film-substrate combination for considerable recrystallization to take place, but rapidly enough so that neither significant loss of material by evaporation nor appreciable change of shape caused by coalescence of any melted region due to surface tension forces, can take place. For example, a 1 watt argon-ion beam at approximately 5145 Angstroms wavelength, focused to a beam diameter of approximately 25 Mu meters, may be used. Such a beam acts to produce a melted track width of approximately 25 Mu meters in a silicon film approximately 1 Mu micrometer thick on a substrate of fused silicon dioxide.

The beam may be modulated in intensity while being swept so that only local regions along the track are heated. In this regard, it is clear that repetitive sweeps of the beam may be employed, by deflecting the beam stepwise with respect to the sweep direction such that an X-Y array of treated regions is produced.

With certain materials, relatively large amounts of recrystallization may occur without the occurrence of melting. The recrystallization here is adequa...