Deposition of Multilayer Optical Coatings Using Closed Field Magnetron Sputtering

Closed field” magnetron (CFM) sputtering offers a flexible and high throughput deposition process for optical coatings and thin films required in display technologies. CFM sputtering uses two or more different metal targets to deposit multilayers comprising a wide range of dielectrics, metals and conductive oxides. Moreover, CFM provides a room temperature deposition process with high ion current density, low bias voltage and reactive oxidation in the entire volume around the rotating substrate drum carrier, thereby producing films over a large surface area at high deposition rate with excellent and reproducible optical properties. Machines based on the Closed Field are scalable to meet a range of batch and in-line size requirements. Typically, thin film thickness control to <±1% is accomplished simply using time, although optical monitoring can be used for more demanding applications. Fine layer thickness control and deposition of graded index layers is also assisted with a specially designed rotating shutter mechanism. This paper presents data on optical properties for CFM deposited optical coatings, including anti-reflection, IR blocker and color control and thermal control filters, graded coatings, narrow band filters as well as conductive transparent oxides such as indium tin oxide. Benefits of the CFM sputter process are described.