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Orientation Control of Thin Film Microstructure

IP.com Disclosure Number: IPCOM000035905D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Bradley, RM: AUTHOR [+4]

Abstract

The microstructure of thin films deposited on a substrate with accompanying ion bombardment can be precisely oriented by selecting the bombardment direction according to both the crystal structure of the film material and the substrate topography.

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Orientation Control of Thin Film Microstructure

The microstructure of thin films deposited on a substrate with accompanying ion bombardment can be precisely oriented by selecting the bombardment direction according to both the crystal structure of the film material and the substrate topography.

Evaporated or sputtered films usually have a preferred orientation determined by the normal to the deposit surface, typically (111) for face-centered cubic (f.c.c.) films and (110) for body-centered cubic (b.c.c.) films. Patterned topography also exerts an influence, known as graphoepitaxy, that causes microstructure orientation relative to the edges of patterned steps. Desired orientation is accomplished by choosing both the polar angle and azimuthal angle of the ion beam during film deposition. The use of a control beam is illustrated in the figure, where substrate 1 with orthogonal x-y lines 2 is being coated with deposition flux of thin film material 3. Ion beam 4 is positioned at polar angle r and azimuthal angle d to properly orient the grain structure.

With an f.c.c. aluminum film, the usual orientation (111) is normal to the substrate surface and presents 3-fold symmetry to the predominantly 4-fold symmetry of the patterned substrate. For f.c.c. structure, logical choices are (100) (4-fold) or (110) (2-fold). To obtain (100) normal orientation, the ion beam polar angle is 45o that will select the (110) channeling direction. To select the (110) normal orientation, t...