Comparison study of physical vapor-deposited and chemical vapor-deposited titanium nitride thin films using X-ray photoelectron spectroscopy

Abstract

The chemical compositions of physical vapor-deposited (PVD) and chemical vapor-deposited (CVD) titanium nitride (TiN) thin films were investigated by X-ray photoelectron spectroscopy (XPS). The effect of a H2/N2 plasma treatment on the chemical composition of CVD TiN thin film was also evaluated. The wafers were air-exposed before the XPS analysis. XPS depth profiles show that the PVD TiN has a N/Ti ratio of 1:1 with a small amount of oxygen in the film (less than 5 at.%). Significant amounts (∼20 at.%, respectively) of carbon and oxygen were observed in the air-exposed CVD TiN thin film, which has a N/Ti ratio of 0.5:1. The H2/N2 plasma treatment greatly reduced the carbon content in the CVD TiN thin film (less than 10 at.%) and a N/Ti ratio of 1:1 was achieved. High resolution XPS spectra indicate that the oxygen in all three TiN thin films analyzed was chemically bonded to Ti. The C1s peak of the as-deposited CVD TiN thin film was resolved into two peaks with binding energies of 282.2 and 284.7 eV, corresponding to the chemical states of carbide and organic carbon. After the H2/N2 plasma treatment, most of the organic carbon was removed with the remaining carbon present mainly as carbide in the CVD TiN thin film.