Thickness uniformity of films deposited on rotating substrates

The coating uniformity of optical films on large items (up to 200mm) or on cassettes with a large number of substrates has substantial significance when multilayer optical coatings are commercially fabricated. This article discusses how the thickness distribution of a deposited film over the radius of a large substrate depends on the geometrical parameters of the mechanism of planetary rotation of the substrates. It is shown that, for a certain relationship of these parameters, the nonuniformity over the thickness of the deposited film can be less than 0.05% on the entire surface of the substrate.