Plasma wall interaction for TiNx film deposition in a hollow cathode arc discharge

The present work discusses the relation between plasma parameters and the film microstructure. Both, plasma diagnostic and film characterization were carried out. The plasma in front of the substrate was analyzed by Langmuir probe measurements and energy resolved mass spectrometry. Film properties were determined by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and X-ray reflectometry. TiN was used as film material. Thin TiNx films were deposited on Si (100) wafers using a hollow cathode arc evaporation device (HCAED). Films were grown at different nitrogen gas flows, substrate voltages and discharge powers. We observe a correlation between thin TiNx film properties and the characteristics of the plasma. Increasing the N2 gas flow as well as increasing negative substrate voltage at medium N2 gas flow results in an increasing energy flux to the surface due to ion bombardment. An increase of the nitrogen content x can be observed with the increase of ion bombardment. Higher ion bombardment leads to a small broadening of the X-ray profile. The higher ion bombardment also induces a diminishing of film texture. With increasing nitrogen gas flow the strongly preferred (002) α-Ti and (111) δ-TiNx orientations change to polycrystalline TiN. Different discharge powers result in a nearly constant ion energy flux to the substrate and lead to the same film properties. These results demonstrate the dominant influence of ions on the properties of the deposited TiNx film.