Binyamin Rubin, Matthias Falmbigl, Antonio Checco, Jason George, Veeco Instruments Inc., Plainview, NY
Ion Beam Sputtering (IBS) is unique amongst the physical vapor deposition processes due to the high energy of the film-forming particles. This higher particle energy together with the low working pressure typically results in good film adhesion, bulk-like density, low defectivity, and low surface roughness. With continuously growing demands on the optical coatings efforts to further minimize absorption, especially in the UV range, become more important. There are two primary mechanisms contributing to absorption in ion beam sputtered coatings: 1) incorporation of impurities during the film growth; 2) damage of the coating by high-energy particles and ions. Both effects were previously investigated for TiO₂ and SiO₂ films. It was found that the absorption level depends on both the impurity species, and the film material. In this study, we investigate the influence of different impurities on various ion beam sputtered oxide coatings that can originate from chamber walls or ion source grids. Our findings demonstrate that contaminations and absorption can be effectively reduced by optimizing grid design and grid material selection.