Structure and properties of Ti-Si-N films prepared by ICP assisted magnetron sputtering

Inductively coupled plasmas (ICPs) were generated to assist magnetron sputtering. By bombarding the growing film with a high-density (∼2.0 mA/cm2) low-energy (∼22 eV) ion flux, Ti-Si-N films containing 0-12 at.% Si were deposited on Si(100) substrates at low deposition temperature (<150 °C). The residual compressive stresses of these films were measured to be lower than 1.5 GPa. Film hardness was significantly enhanced by the addition of a small amount of Si and attained a maximum value of 48 GPa at approximately 5.8 at.% Si. From X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results, the superhard Ti-Si-N films were characterized as having a nanocomposite structure, consisting of nanocolumns of TiN crystallites with amorphous Si3N4 inside the column boundaries. The hardest Ti-Si-N film exhibited a pronounced TiN(200) texture. No refinement of crystallite size by the addition of Si was observed in the present series of Ti-Si-N films. Thus, the hardness enhancement was attributed to nanocomposite effect.