ARSENIC ION-BEAM-INDUCED MIXING IN TA PD THIN-FILMS ON SILICON/

In this paper we present a study of atomic mixing in Ta/Pd bilayers de posited on silicon, induced by As+ ion implantation. The films were de posited by de sputtering to thicknesses of 60 nm (Pd) and 50 nm (Ta) o n n-(111)Si wafers. After deposition the samples were implanted with A s+ ions at 250 keV and 450 keV, to doses from 1 x 10(15) ions cm(-2) t o 1 x 10(16) ions cm(-2), at room temperature (RT). Thermal treatments of samples were performed in vacuum (1 x 10(-5) mbar) at 400 degrees C and at 600 degrees C, for 20 min. Structural changes were analysed b y Rutherford backscattering spectroscopy (RBS), X-ray diffraction (XRD ) and scanning electron microscopy (SEM). We have studied the effects of the ion ranges and doses on the reactions in films, and also the ef fects of additional thermal treatments. The results indicate a depende nce of the mixing processes on the film thickness to the ion range rat io (d/R(p)). The pronounced structural changes and intermixing of comp onents at the Ta/Pd interface are due to the high value of F-D, damage energy deposited by the incident ions at the interface. Post-implanta tion annealing at 600 degrees C initiates the reaction of Ta with Si a t the Pd2Si/Ta interface, enabled by rapid silicon diffusion through t he Pd2Si phase, which has already formed during annealing at 400 degre es C.