Investigation of the microstructure, chemical composition and lateral gorwth of TiN films deposited by laser-induced chemical vapour deposition

A study of the laser direct writing of titanium nitride on mild steel substrates by pytolytic laser-induced chemical vapour deposition was carried out under different operating conditions. Lines of TiN were deposited from a reactive gas mixture of TiC1₄, N₂ and H₂ using a continuous wave TEM₀₀CO₂ laser beam as heat source. The deposited material was analysed by optical and scanning electron microscopies, wavelength-dispersive X-ray microanalysis and profilometry techniques. Golden coloured TiN films, close to the stoichiometric composition, were produced exhibiting good adherence, very fine grain size (~100nm) and broad gaussian, profiles. A time kinetics study based on the lateral growth rate of the deposited lines is also presented. From the transiente growth conditions, an empirical relation between the interaction time needed to achieve film deposition and the laser irradiance was established, which led to a value for the incubation period of 5.4 ns. This relation also gave a value for the threshold laser irradiance of 1.54 x 10ᶣ W cm-², in good agreement with the value found experimentally.