Magnetron sputtering of a silicon target in a time-variant mixture of the reactive gases oxygen and nitrogen allows the
deposition of optical multilayer and gradient layer systems of silicon oxinitride at one stationary sputtering station. In
this paper the processes within the sputter discharge and the properties of the growing film during the change of the
reactive gas composition are investigated using optical in-situ monitoring, optical plasma emission spectroscopy and
plasma impedance monitoring. A time delay between the change to the reactive gas composition and the resulting change
to the film composition was observed. The time delay is longer for the transition from oxide to nitride deposition then
vice versa. This asymmetry is attributed to the different affinity of nitrogen and oxygen to the silicon target. Examples of
deposited antireflective coatings as well as rugate filters based on silicon oxinitride multilayer and gradient layer designs are given.
Improvements of the environmental stability of inorganic optical coatings on polymer substrates are expected from a slight variation of the chemical composition of SiO2 films by organic modification through the addition of gaseous hexamethyldisiloxane (HMDSO) to a classical plasma ion-assisted deposition process. The influence of several process parameters on the chemical composition of these coatings has been studied on polycarbonate, quartz glass and silicon substrates to define an optimum range of process parameters with regard to the useful properties obtained of the coated polymer optical component.
Antireflection (AR) properties are required for optical surfaces to avoid disturbing reflections as well as to improve the transmission of optical systems. The common method to reduce the reflection on optics is vacuum deposition of interference coatings. However, special efforts are required for each type of plastic to develop polymer-capable vacuum coating processes due to the manifold chemical and physical properties of optical polymers. An alternative procedure for the antireflection of polymers is the generation of surface structures that decrease the index of refraction in a surface region. In this paper, the suitability of the miscellaneous thermoplastic polymers for plasma-ion assisted deposition processes is evaluated. This comprises the study of damage effects caused by the contact with plasma and high-energy radiation as well as the development of special coating designs and of suitable process conditions. Coating properties achieved are discussed for PMMA and poly-cycloolefines. The same ion source arrangement as used for coating has been applied for etching an antireflective sub-wavelength surface structure into PMMA. In summary, the paper shows the practical application fields for both technologies.