The application of dynamic recoil mixing to enhance adhesion of gold films on silica substrates

Abstract

Dynamic recoil mixing (DRM) in which a film of constant thickness is maintained on top of a substrate whilst the surface of the film is bombarded by 10 keV Ar + ions has been employed to deposit adherent Au thin films on silica substrates. Scratch tests have indicated that the film adhesion increases by an order of magnitude at an Ar + fluence of 1 × 10 17 ions cm −2. Scratch test analysis suggests further improvements in adhesion following the introduction of oxygen into the low energy sputtering gun during the deposition of the first 10 nm Au film on the substrate. It is suggested that the DRM process causes the formation of an intermixed layer of Au silica which enhances the mechanical interlocking and the chemical reactivity of the film-substrate material and thereby increases the adhesion. When oxygen is used, chemical bonding and the possible formation of Au oxide may be responsible for a further enhancement of adhesion.