Metallic film deposition using a vacuum arc plasma source with a refractory anode

Abstract

Conventional metallic film deposition techniques are compared with the hot refractory anode vacuum arc (HRAVA) developed in the last decade. In the HRAVA process, the anode is heated by the arc, and a dense plasma plume of cathode material is formed by re-evaporation of cathode material from the anode. The steady-state HRAVA mode is reached when the anode is sufficiently hot and a plasma plume expands radially. HRAVA processes using high arc current ( I = 145–340 A), metal cathodes (Cu, Ti, Cr), refractory anodes (graphite, Mo, W) and 5–18 mm inter-electrode gaps were investigated theoretically and experimentally. It was found that the anode surface temperature increased approximately linearly with the arc current: on a graphite anode from 1950 K to 2200 K when I increased from 175 to 340 A, and on a W anode from 2250 to 2500 K when I increased from 150 to 250 A. High quality, macroparticle free metal thin films formed on substrates arranged radially around the electrode axis and having a direct line of sight to the anode, but not to the cathode. The deposition rate was determined in 300 A arcs with Cu cathodes, at distances of L = 110 and 80 mm from the arc axis, to be 2.0 and 3.6 μm/min, respectively. The Cr deposition rate at L = 80 mm for I = 200 to 300 A was 0.72 to 1.4 μm/min, and for Ti at L = 100 mm, 0.88 to 1.8 μm/min. The main advantages of the HRAVA source is simplicity of the construction, generation of highly energetic and ionized metallic vapor, and high deposition rate.