SEGREGATION OF CU IMPURITY IN ALUMINUM ON SILICON DURING HIGH-DOSE NITROGEN-ION IMPLANTATION

Aluminium films with a thickness of 7000 angstrom (containing 0.85 wt% copper) were deposited on [100] silicon substrates. 400 keV N2+ or 350 keV N+ ions with doses ranging from 4.3 x 10(17) to 1.5 x 10(18) N/cm2 were implanted into the aluminium films or at the interface between the aluminium and silicon, respectively. Rutherford backscattering (RBS) and channelling and Fourier transform infrared spectroscopy (FTIS) were used to characterise the synthesised aluminium nitride and the depth distribution of the Cu impurity in the aluminium films after ion implantation and post annealing. The formation of a stoichiometric AlN layer was evident from RBS and IR analyses by the presence of the absorption band at 650 cm-1. Segregation of the Cu impurity into the aluminium nitride was enhanced during ion implantation by point defects generated by the N+ ion beam.