Reactive co-deposition of TiNx/SiNx nanocomposites using pulsed direct current magnetron sputtering

Abstract

Nanocrystalline-TiN/amorphous-SixNy films were reactively co-sputtered from pure Ti and Si targets over the mid-frequency range of 50–250 kHz using two asymmetric bipolar pulsed direct current power supplies. The pulsing frequency was varied in this co-deposition system as a possible means to control the nanocrystalline composite thin film properties. The resulting films were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, stress measurements, Fourier transform infrared spectroscopy, nanoindentation, sheet resistance, and field emission scanning electron microscopy. When fixing the ratio of power delivered to each target and varying only the frequency, the films were found to be silicon-rich at frequencies under 100 kHz and constant composition of 80 mol% TiN at higher frequencies. Normalized nanoindentation depths of 5%, 10% and 15% of the film thickness were performed. At 250 kHz, for example, the film had a Vickers hardness, Hv, of 25 GPa and reduced modulus, Er, of 233 GPa even though the oxygen content was over 3 at.%.