Interfaces evolution in Ti/Si multilayers obtained by laser ablation

Ti-Si material compositions with layered structures are very interesting for sensors and optoelectronics applications. The ultra-thin multilayered Ti/Si films were prepared by pulsed excimer laser ablation (PLA) at wavelength of 193 nm from the Ti and Si targets. Two samples S1 and S2 with multilayered structures of four bilayer period of ~20 nm and five bilayer period of ~1 nm thickness of the Ti-Si layers on Si(100) substrates, respectively were deposited. Samples were post-deposition heated at 600°C in argon atmosphere for 10 min by rapid thermal process (RTP). The composition structures were investigated by transmission electron microscopy (TEM), secondary ion mass spectrometry (SIMS), grazing X-Ray reflectance (XRR), and X-ray diffraction (XRD) methods. The results show that intermixing of the Ti- and Si-based films appears even in the as deposited layers. The multilayered structure of the S2 sample after post-deposition annealing indicates the formation of the titanium silicide layer. The domination of interfacial and surface energies leads to the formation of metastable phase with a low interfacial energy.