Flux ionization of arc-like Ti vapor plasma

Abstract

Arc-like Ti vapor plasma is formed on the electron beam evaporator by applying low dc voltage to an anode near the evaporator. Deposition rate (R d), substrate ion current density (J s) and anode current (I a) were simultaneously measured by changing: (1) anode voltage (V a) at the constant EB gun power 4.05kW; and (2) source-to-substrate distance (distance r) at V a 30V and I a 60A. With an increase in V a from 15 to 35 V, R d 2.6 nm/s decreases only slightly, while I a and J s increases from 40 to 90 A and from 12 to 40 A/m 2, respectively, at distance r 0.45m. With a decrease in distance r from 0.52 to 0.15 m, R d and J s increase from 2.0 to 40 nm/s and from 24 to 420 A/m 2, respectively, (the measured values being mean values). The calculated mean values for flux ionization increase from 40 to 160% for condition (1), and are approximately 120% in all cases for condition (2). The latter suggests collisionless expansion of Ti ions. At this high flux ionization with no biased substrate, self-ion bombardment is more effective for Ti film densification than Ar ion bombardment.