Fabrication of Multilayer Dielectric Films

Abstract

For the fabrication of multilayer dielectric films for mirrors or filters, an evaporation system was built for attaining (1) thickness variations below ±0.5% on substrates up to 6 in. in diameter and (2) simultaneous deposition on five such substrates. During deposition, the substrates perform a planetary rotation around the source thereby greatly reducing thickness variations and angle-of-incidence effects, together with inhomogeneities in the evaporation characteristic of the source. Details of the system and the optical monitoring arrangement are given. The experimental thickness variation amounted to ±0.15% on the 6-in.-diam substrates. Reflectances of up to 99.8% could be attained with the losses due to scattering. The application of the mirrors to optical information-storage experiments is briefly described.