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Proceedings Paper

Thickness distribution of evaporated films
Author(s): Anthony Musset; Ian C. Stevenson
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Paper Abstract

The emission distribution characteristics of an evaporation source can be used to defme the correct geometry in the vacuum chamber for the production of uniform-thickness coatings. We first measured the thickness of coatings on test pieces positioned at known radial distances on a single rotation flat rack in the vacuum evaporation chamber and used these data in a computer program which found the source emission function, in the form cos° , which provided the best fit to the data. is the emission angle of the evaporant stream from the source, measured from the vertical. The known emission function was then used to determine the source offset and calotte curvature which produced the best thickness uniformity over the diameter. In one example, we found 0 = 131 for A1203 evaporated from an electron beam source. This enabled us to predict a chamber geometry which yielded coatings across a calotte of diameter 81 cm with a thickness variation of 0 = 1.70, but the uniformity was less excellent (±3%) because this material is difficult to evaporate controllably. The technique is a powerful one for anyone setting up his coating chamber to produce a large number of coated substrates.

Paper Details

Date Published: 1 August 1990
PDF: 5 pages
Proc. SPIE 1270, Optical Thin Films and Applications, (1 August 1990); doi: 10.1117/12.20387
Show Author Affiliations
Anthony Musset, Denton Vacuum, Inc. (United States)
Ian C. Stevenson, Denton Vacuum, Inc. (United States)

Published in SPIE Proceedings Vol. 1270:
Optical Thin Films and Applications
Reinhard Herrmann, Editor(s)

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