X-ray reflectivity in thin film studies

Specular reflectivity measurements (XRR) were used to study the changes of density and surface roughness of amorphous carbon (a-C) thin and ultra-thin films, with regards to thickness. Also oxidation process of TiNx films, was followed. Density, thickness and surface roughness of the films were deduced using x-ray reflectivity measurements in a series of films within a range of nominal thickness from 27 Angstrom 326 Angstrom for amorphous carbon and of about 700 Angstrom for TiNx thin films. Both kinds of films were deposited by sputtering. Density and roughness of films vary as a function of thickness and it was found that amorphous carbon films deposited with positive substrate bias voltage exhibit a reduction in density and an increase in surface roughness. In the case of titanium nitride (TiNx) films, XRR measurements showed a constant increase in density and thickness and a decrease in surface roughness after exposure to air. Only the films deposited at low bias voltage are prone to oxidation.