The Nanosecond Effect of Intense Laser Radiation on Thin TiAlN Films

Abstract

The spectral dependences (λ = 0.35–1.0 μm) of transmittance and reflectance R of binary TiAlN nitride thin films deposited by magnetron sputtering of the target on glass substrates and on Si wafers have been measured. TiAlN/Si films 0.5 μm thick were exposed to single nanosecond (70 ns) pulses of ruby laser radiation in order to study the effect of thermophysical processes laser-induced in TiAlN on the dynamics of R(t) at probe wavelengths λ₁ = 0.53 μm and λ₂ = 1.06 μm and on the state of the zones of laser irradiation, which was studied by optical and scanning electron microscopy. The dynamic change of R increase at λ₁ and decrease at λ₂ associated with pulsed heating of the film and which is observed in the experiment increases as irradiation energy density W increases with the approach to the threshold energy of laser ablation of nitride of ~1 J/cm². Laser-induced thermophysical processes occurring at W = 0.6–0.9 J/cm² lead to specific modification of the TiAlN layer with the formation of a grid of cracks due to thermal stresses arising during the action of the laser pulse. Increasing W results in a more developed cellular/mesh film structure characterized by a smaller average cell size.