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.