Low-temperature resistivity and microstructure of reactive magnetron co-sputtered Ta–Si–N thin films

Abstract

The low-temperature electrical property of composite tantalum silicon nitride (Ta–Si–N) thin films deposited at low and high nitrogen flow ratios (FN2%) has been investigated. The microstructure and morphology of both quasi-amorphous Ta–Si–N films were characterized by a grazing incident x-ray diffractometer, scanning electron microscope and atomic force microscope, which could influence the electrical resistivity of Ta–Si–N at low temperatures of 10–300 K. The film deposited at low FN2% had a lower resistivity because of low N content compared with that at high FN2%. The resistivity of Ta–Si–N at low FN2% distinctly decreased with increasing temperature at 10–300 K while that at high FN2% had a steep drop at 70–120 K. The transport mechanism of Ta–Si–N resistivity at low temperatures was discussed by the weak localization model. The film deposited at high FN2% showed crossover from 2D localization to 3D localization while that at low FN2% exhibited only the 3D localization. Both samples showed that electron–phonon scattering was the dominant scattering mechanism in both 2D and 3D weak localization effects.