Silicide formation using a scanning cw laser beam

A scanning cw laser has been used to react e-beam-deposited Pd, Pt, and Nb thin films with single-crystal silicon substrates. A single laser scan is capable of reacting 1300 Å of Pd with Si to form either Pd2Si or PdSi, depending on the laser power. Multiple laser scans are necessary to completely react 1100 Å of Nb to form NbSi2. X-ray diffraction analysis shows that the Pd and Nb silicides formed are essentially single phase. The formation of Pd2Si and NbSi2 can be understood by a solid-phase diffusion mechanism. However, it is suggested that a nucleation-reaction-controlled process is occurring in the formation of the PdSi compound. The formation of a superconducting Pt2Si3 is also shown.