Excimer laser-induced chemical vapor deposition of titanium silicide

Abstract

A pulsed ArF excimer laser has been used to deposit thin conductive films of titanium silicide on silicon and silicon oxide substrates. The films are deposited from a gas mixture of titanium tetrachloride and silane by initiating photochemical reactions near the heated substrate. The resistivity, composition, crystal structure, and morphology of the films vary as a function of gas composition and substrate temperature. Films deposited at 400 °C, with SiH4/TiCl4 mole ratios of ∼2, have resistivities of 300 μΩ cm, which drop to 20–30 μΩ cm on annealing at 650–700 °C. At higher deposition temperatures (450–550 °C) the films have resistivities of ∼110 μΩ cm and show similar annealing behavior. The as-deposited films are a mixture of amorphous and a metastable Ti-Si crystalline phase. On annealing they convert to polycrystalline TiSi2. Films deposited at 400–450 °C are smooth and show conformal step coverage. The film roughness increases at higher deposition temperatures.