In situ spectroscopic ellipsometry for studying the growth and optical constants of ALD AlN films

This work reports on the applications of in situ spectroscopic ellipsometry (SE) in studying the growth characteristics and optical functions of aluminum nitride (AlN) thin films made by atomic layer deposition (ALD). We used SE to measure the film thickness in real-time during the deposition, and to study the growth rate and the self-limiting reaction of the ALD growth mode. The Cauchy-Urbach model was applied to parameterize and study the evolution of the refractive index, n, and extinction coefficient, k, of the AlN layers during growth. We observed a strong thickness dependence of the optical constants.