Ion-beam-sputtered metal fluorides

Dense, water-free magnesium and calcium fluoride films were produced by Reactive Ion Beam Sputtering (RIBS). These films were found to J.e fluorine deficient because of a preferential sputtering of fluorine at the target This deficiency was eliminated by the addition of a fluorinecontaining gas (carbon tetrafluoride) to the coating chamber gases during deposition of the films. The chemical composition and density of the films were measured with Rutherford backscattering spectrometry. The relationship between film composition and optical properties was investigated. The results indicate that the fluorine deficiency can be eliminated without compromising either the density or environmental durability.