Characterization of atomic layer deposited nanoscale structure on dense dielectric substrates by X-ray reflectivity

Interfaces play a crucial role in determining the ultimate properties of nanoscale structures. However, the characterization of such structures is difficult, as the interface can no longer be defined as the separation between two materials. The high sensitivity of electron density to surface and interface reactions has attracted increasing interest in application of X-ray reflectivity (XRR) as probing technique. In this study, the nanolaminate structures were formed by atomic layer deposition (ALD) of tungsten nitride carbide (WNC) and tantalum nitride (TaN) thin films on silicon carbide (SiC), silicon oxide (SiO2) and silicon oxynitride (SiON) substrates and subsequently characterized by XRR. The goal is to establish a relationship between surface chemistry, interface properties and density of the final structure. To achieve this objective, the density variations at the interfaces between ALD TaN and ALD WNC with SiC, SiO2 and SiON films will be quantified by modeling analysis of XRR reflection spectra. From these modeled electron density profiles, specific mechanisms leading to surface dependent structural behavior are proposed.