EFFECT OF CR IMPLANTATION ON THE MORPHOLOGY OF AL-SI FILMS

Al:Si 1% films subjected to irradiation with Cr+ ions are investigated for their morphology and appearance of hillocks. The oxidized silicon wafers were coated with 1 mu m thick metallic layers by magnetron spu ttering. Prior to sintering at 450 degrees C for 30 min the films were implanted with chromium ions at an energy of 130 keV and to doses 4 X 10(15)-9 X 10(15) cm(-2). Investigations of the processed surface usi ng SEM, alpha-step together with a procedure for digital evaluation of the surface morphology examined by an optical microscope show that ch romium implantation leads to a significant reduction of the hillock po pulation, in particular those of the largest size. The effect is obser ved for Al:Si and Al:Si:Cu alloys but not for pure Al. SIMS profiling gives evidence of measurable mobility of Cr atoms during the annealing . TEM analysis displays a noticeable reduction of the material grain s ize and reveals in Cr+ implanted Al:Si layers an array of fine precipi tates located within the grain volume. From the fact that the modifica tion of grain-growth kinetics occurs only when Si is present in the fi lm one may conclude that Cr atoms precipitate in Si-rich phases (binar y or ternary). Other effects of Cr implantation into Al-based films ar e: reduction of the lattice constant and an increase in sheet resistan ce (by 10%). Formation of Cr-containing precipitates seems beneficial in suppressing overall diffusivity in the layer preventing,thus the gr ains from excessive vertical growth.