Laser irradiation of nano-metric Al/Ti multilayers

Multilayered 5×(Al/Ti) structures, deposited on a Si substrate to a total thickness of 130 nm, were treated by unfocused Nd:YAG laser pulses (150 ps) with energies of 85 and 65 mJ. Irradiations were performed in air with 10, 50 and 100 successive laser pulses. Characterizations were done by using Rutherford backscattering spectrometry (RBS), elastic recoil detection analysis (ERDA), x-ray diffraction (XRD) and transmission electron microscopy (TEM). The results obtained show that laser irradiation, at either energy, induced almost full intermixing of deposited layers and formation of intermetallic compounds, but this was more pronounced for the applied laser pulses with a higher energy. The intermixed layer–silicon interface remains intact for all numbers of applied laser pulses and for both energies. The formation of an oxide layer on the sample surfaces was also observed, the thickness of which is greater for the higher laser beam energy. (paper)