AVS 53rd International Symposium
    Applied Surface Science Thursday Sessions
       Session AS-ThP

Paper AS-ThP23
Development of Closed Field Reactive Magnetron Sputtering for Multilayer Optical Coating

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: Aspects of Applied Surface Science Poster Session
Presenter: J.M. Walls, Applied Multilayers Ltd, UK
Authors: J.M. Walls, Applied Multilayers Ltd, UK
D.R. Gibson, Applied Multilayers Ltd, UK
E.M. Waddell, Applied Multilayers Ltd, UK
Correspondent: Click to Email
Closed Field reactive magnetron sputtering has been used for many years to produce state-of â?"the-art tribological and wear resistant coatings. In this paper, we report on its recent development and application to multilayer optical coatings. Optical coatings require precise control of the stoichiometry of dielectric metal oxides and layer thickness control within sub-nanometre tolerance. The process operates with metal targets and although the targets are partially oxidised the deposition rates are close to the metal mode. This requires the use of pulsed dc power and a new hysterisis control strategy based on monitoring target Voltage. Thickness control is achieved using time only. In addition, the process incorporates shutters to allow target pre-conditioning and fine interface control. In addition to describing the new process, this paper will discuss the optical properties of a range of optical materials including dielectrics such as SiO2, Nb2O5, TiO2, ZrO2 and Al2O3 together with important transparent conducting oxides such as indium tin oxide (ITO). The Closed Field technique produces reactive plasma conditions that combine low energy (<50eV) and high ion current density (>5mA.cm-2) to provide ideal conditions for thin film growth with the further advantage that the vacuum hardware is relatively simple and there is no requirement for an auxiliary ion or plasma source. The process produces non-absorbing, dense, spectrally stable coatings that are also exceptionally smooth (rms roughness typically <1nm). The Closed Field sputtering process is also â?ocoldâ?, making it suitable for use on the widest range of substrates including polymers. This paper will describe the new process and provide examples of multilayer coatings for important applications in the visible and infra-red on glass and a variety of polymer substrate materials.