Design criteria for a clean thin film deposition facility are discussed. A low-energy ion beam film deposition system satisfying the design requirements has been constructed. Initial performance data are given for gaseous ion beams and for several ion beam-deposited elemental metallic films. The facility has numerous features built in to allow a wide range of diagnostic tests to be carried out on films produced within the system, both in situ and in external equipment such as electron microscopes and Rutherford backscattering analysis. A deposition energy between 70 and 75 eV is suggested as an optimum energy range for deposition of Pb+ and Mg+ onto carbon substrates.