Structural and electrical properties of Ti-W-N thin films deposited by reactive RF sputtering

Ti-W-N thin films were deposited by reactive RF sputtering with a W-Ti(30 at.%) target in an argon/nitrogen atmosphere. The nitrogen partial pressure ratio in the growth chamber was varied from 0 to 11%. The influence of the nitrogen partial pressure ratio on the properties of Ti-W-N thin films was studied. The electrical resistivity of the Ti-W-N thin films varied gradually from 117.5 μΩ•cm to 675 μΩ•cm with the increase of nitrogen partial pressure ratio from 0 to 5.88%. However, the resistivity increased sharply if the ratio was raised further. X-ray photoelectron spectroscopy (XPS) analysis showed that nitrogen concentration in the films increased with the nitrogen partial pressure ratio and reached 36% when the ratio was 11%. Binding energy analysis showed that W was mainly in W2N and Ti was mainly in TiN when the film contained a nitrogen concentration of 36%. Grazing incidence X-ray diffraction (GIXRD) analysis confirmed that a f.c.c mixed phase W2N/TiN was present in the film. Moreover, the temperature coefficient of resistance and the micromachining of the Ti-W-N thin films were investigated.