New evaporation method of high-melting-temperature materials utilizing a vacuum discharge

By utilizing a discharge caused between electrodes (specimens) in a high vacuum (≃2×10−5 Torr) and without inert gas, the evaporation of high-melting-temperature materials (W, Ta, and C) has been successfully achieved. The main part of the instrument was composed of two electrodes (0.8–1.5 mmφ) and a helical filament (0.8–1 mmφ, 10 turns). An alternating voltage was supplied between electrodes (sparking gap: 0.5–2 mm), and in order to get sparking easily, the electrodes were preheated by bombarding with electrons (emission: 500 μA) from the filament. After starting, the high voltage was lowered to a range of 1–2 kV and the filament fell in disuse. Then the discharge was maintained stably. The structure of 600-Å-thick W films deposited by this method was mostly of the ordered W3W.