Producing Cu interconnections on a Si substrate using a hot refractory anode vacuum arc

A radially expanding metallic plasma plume was generated by a hot refractory anode vacuum arc (HRAVA) sustained between a 30 mm diam consumed water-cooled cylindrical Cu cathode and a non-consumed cylindrical W anode (32 mm diam, 30 mm height). The anode was heated by a I=200 A arc 180 s. Films were deposited on Si substrates with a top SiO₂ layer having trenches with an aspect ratio (depth/width) as high as 3. The substrates were exposed to the plasma plume for 120 s. The distance to the substrate from the electrode axis was varied. Pulsed bias voltages, of -75 and -100 V, 60 kHz and 25-100% duty cycle, were applied to the substrate. The films were examined using a scanning electron microscope and characterized by X-ray diffraction and a four point probe. The deposited Cu films had strong (111) texture, and a typical grain size of 45 nm. Macroparticle-free Cu films were deposited at rates of up to 425 nm/min. The average film resistivity increased with distance from the electrode axis.