Manufacturing of high-precision optical coatings using cylindrical cathodes in a sputter-up configuration

Abstract

Sputtering of high-precision optical coatings with a large number of layers as well as high precision has always been a challenging task due to insufficient long term stability of reactive sputtering processes. In previous solutions planar targets have been used that suffered from inhomogeneous surface leading to higher material cost, increased tendency to arcing and particle generation. In the present paper an approach is presented that overcomes the challenge of planar magnetrons. A rotating pattern coater is equipped with two dual cylindrical magnetrons in a sputter-up configuration. Simulated gas flows as well as material distributions are presented. Thin films prepared by metallic sputtering and plasma oxidization (metamode) as well as reactive MF-sputtering are investigated. Properties such as stress, optical density and surface roughness of Ta2O5 and SiO2 are discussed