Thickness Distribution and Step Coverage in a New Planetary Substrate Holder Geometry

Abstract

Thickness distribution and step coverage are calculated for a new planetary substrate holder geometry in which the substrate surface is vertical. Results for the new geometry are compared with those for arrangements presently in use. Substantial improvements can be obtained simultaneously for thickness uniformity, step coverage, and batch size in the new geometry. For example, maximum-to-minimum thickness variation is 0.4% on 10-in. platens in a 24-in. bell jar. Step coverage in the vicinity of 100% can be attained. The batch size with vertical platens may exceed that with horizontal ones by a factor of up to 3 in the same bell jar. Eccentric sources may be used in the new geometry to decrease cusp formation in the vicinity of steps without loss of uniformity of thickness distribution.