LOW-RESISTIVITY CU THIN-FILM DEPOSITION BY SELF-ION BOMBARDMENT

An anomalous reduction of the thin-film resistivity has been observed in the Cu deposition at room temperature using a partially ionized beam in which the self-ions are used to bombard the substrate surface during growth. A minimum thin-film resistivity of 1.83 μΩ cm has been obtained at 2 kV substrate bias voltage with an ion percentage of about 1% in the beam for films of 2500 Å thickness. This is compared to the resistivity of close to 4 μΩ cm obtained by the conventional evaporation technique without the use of self-ions. We discuss the results within the framework of the theory of grain-boundary resistivity proposed by Mayadas and Shatzkets [Phys. Rev. B 1, 1382 (1970)].