Filling trenches on a SiO₂ substrate with Cu using a hot refractory anode vacuum arc

First results of complete filling of 100 nm wide × 300 nm deep trenches with Cu using the expanding plasma plume from a hot refractory anode vacuum arc (HRAVA) plasma source are presented. The arc was ignited between a consumed water-cooled cylindrical Cu cathode (30 mm diameter) and a non-consumed W cylindrical anode (32 mm diameter, 30 mm height) that was heated by the arc. An arc current of 200 A was applied for periods of 180 s. The films were deposited on a Si substrate with a top SiO₂ layer. The substrates were exposed to the plasma plume for 120 s, while a shutter was open. The distance to the substrate from the electrode axis was varied over the range of about 74-122 mm. A pulsed bias voltage of -75 or -100 V, with a 60 kHz pulse repetition rate and a 50-80% duty cycle was applied to the substrate. The films were examined using a scanning electron microscope. The average film resistivity was measured with a four point probe. The deposition rate was as high as 425 nm/min, and the minimum average resistivity was 5.5 μΩ cm.