Property and Processing Comparison of Optical Coatings Made by Ion Assisted Evaporation and Magnetron Sputtering

Abstract

AbstractIon Assisted Evaporation and Magnetron Sputtering are the two most important Physical Vapor Deposition processes used for optical coatings today. Each has advantages and limitations, and each is best for different coating applications. This paper provides a brief but comprehensive comparison of the two. Starting with introductory process descriptions, the paper compares Ion Assist and Sputtering feature-by-feature and ranks them in scorecard fashion. Features examined include: adatom energetics, reactivity, materials compatibility, thickness uniformity, deposition rate, substrate temperature, durability, environmental stability, refractive indices, absorption, scatter, mechanical stress control, and scalability (chamber and substrate size). The comparison is illustrated with examples from the author's twenty-four years of optical coating experience at three companies, with more than forty coating chambers (small, medium and very large), in research, development and production coating environments.