Angular distribution of mass flux from arc-like Ti vapor plasma

Abstract

Arc-like Ti vapor plasma that appears symmetrical is formed on the electron beam evaporation source in high vacuum by applying ~ 20 V dc voltage to the anode set diagonally above the source. Angular distributions of both ion and mass fluxes from the plasma at the longitudinal section, including the anode, are investigated. The angular distribution of Ti ion flux from the plasma with 40 V–80 A discharge is unsymmetric (maximum ion current density is 16 Am −2 at θ = 0 ° and source-to-Faraday cup distance 460 mm): the ion current at the anode side (back side) is much higher than that at the front side. However, the ion current decreases near the anode direction. Angular distribution of mass flux from the plasma agrees largely with that of ion flux, but disagrees with that of mass flux from the vacuum evaporation source (cos 3 θ distribution). Therefore, ionization efficiency of Ti vapor in the plasma is considered to be high. Rough surface and small voids are seen at vacuum evaporation, but not at the arc-like discharge evaporation. The cross section fractured in liquid nitrogen is brittle in the former, but ductile in the latter. This shows that self-ion bombardment greatly affects Ti film densification.