INFLUENCE OF ION ENERGY AND SUBSTRATE-TEMPERATURE ON THE STRUCTURE OF COPPER, GERMANIUM, AND ZINC FILMS PRODUCED BY ION PLATING

Thin films of copper, germanium, and zinc were deposited at an argon pressure of 2.7 Pa (20 mTorr) on cover glass substrates precoated with 10 nm of Au/Pd. The substrate temperatures T(s) ranged from 77 to 417 K for zinc, 77 to 543 K for copper, and 77 to 490 K for germanium. The discharge voltage was varied from 900 to 1300 V. Average film thickness was approximately 1.5-mu-m, with deposition rate approximately 0.4-mu-m/min. Ion energies were measured by the retarding field method. Examination of the film structure with a scanning electron microscope (SEM) showed that zones I and T were missing. Structural zone transition temperatures were lower than in the models proposed by Movchan and Demchishin, and Thornton. All copper and zinc films were polycrystalline. Germanium, for the above deposition rates, showed an amorphous/polycrystalline transition, as determined by reflection high-energy electron diffraction, for various ion energy and T(s) combinations. Polycrystalline germanium is observed at room temperature for energies above 340 eV. A structural zone model showing the effect of the ion energy and substrate temperature on the film structure for ion plated films is proposed.