Fully automated inline sputtering for optical coatings

Reactive magnetron sputtering using pulsed technique in combination with dual magnetron design has become a relevant factor for the production of optical coatings. This pulsed reactive magnetron sputtering process enables the deposition of highly insulating layers, like Al 2 O 3 , SiO 2 , Nb 2 O 5 , with high deposition rates, sophisticated optical properties and excellent homogeneity on large substrates. In this paper a Vertical Inline Sputtering System (VISS) for optical coatings is presented. The goal for this new type of production inline coater is a fully automated thickness control for high and low index materials. This shortened the time from design to a coated product. Fundamental for this approach is the knowledge of the behaviour of reactive magnetron sputtering, the relationship between process parameters and optical layer properties. Due to the influence of process parameters (magnetron power, argon pressure, set point of plasma emission) on layer properties (refractive index, absorption, stress, etc.) an adjustment of layer properties is necessary. Typical correlations for the deposition of SiO 2 as a low index material and Nb 2 O 5 as a high index material will be presented. Beside the knowledge about reactive magnetron sputtering a precondition to come to a fully automated production is a reproducible and accurate optical measurement. The set up of optical measurement and the steps to come to a high accuracy measurement are described. With the presentation of different examples of optical coatings the versatility of this production coater will be shown.