Laser-induced chemical vapor deposition of titanium silicide films

Abstract

Films of titanium silicide have been deposited from gas mixtures of SiH4 and TiCl4 using laser irradiation to initiate chemical vapor deposition. Two different laser excitation sources have been used. A CO2 laser initiates deposition through the thermal decomposition of silane, whereas an ArF excimer laser causes deposition by the photolytic dissociation of titanium chloride. Both methods permit control of the substrate temperature independently from the reactor gas temperature. The substrate temperature has been found to strongly influence the resulting titanium silicide film morphology and crystal structure. The different chemistries initiated by the CO2 and excimer lasers have much less influence on the final film properties. Smooth films with a resistivity of 20 μΩ cm are obtained with either method by depositing the films at a low substrate temperature (400 °C) followed by an annealing step at elevated temperature (650–800 °C).