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Improved Thickness Uniformity of Liquid Phase Epitaxy Magnetic Films

IP.com Disclosure Number: IPCOM000078978D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Parsons, AH: AUTHOR [+2]

Abstract

In the past, one method for producing uniformly thick films was to place the film in an isotherm. For the liquid base epitaxy "tipping" process, this was found to be parallel to the flux surface in the "tipped" position and about 5 mm below the flux surface. This gave a thickness variation of about 9-10 interference fringes across a 15 mm diameter wafer.

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Improved Thickness Uniformity of Liquid Phase Epitaxy Magnetic Films

In the past, one method for producing uniformly thick films was to place the film in an isotherm. For the liquid base epitaxy "tipping" process, this was found to be parallel to the flux surface in the "tipped" position and about 5 mm below the flux surface. This gave a thickness variation of about 9-10 interference fringes across a 15 mm diameter wafer.

It is possible to improve this uniformity by a factor of about 3 using the following method. The method involves placing a sheet of platinum over the substrate and parallel to the substrate surface, on which liquid phase epitaxy is to occur. The separation between the substrate and the sheet of platinum must be greater than 1/2 mm or else the flux will not completely drain off the substrate, when the apparatus is tipped back. Optimum separation was found to be about
0.5 and 1.5 mm.

The improved thickness uniformity is believed to result from the fact that the sheet of platinum prevents thermal convection, which disturbs the temperature distribution at the growing interface.

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