Thermal Stability of TiZrAlN and TiZrSiN Films Formed by Reactive Magnetron Sputtering

Abstract

Quaternary TiZrAlN and TiZrSiN films with Ti : Zr ratio of ~1 : 1 and different Al (or Si) content were deposited by simultaneous reactive magnetron sputtering of Ti, Zr, and Al (or Si) targets under Ar + N₂ plasma discharges. The elemental composition was determined by WDS and RBS methods; the phase composition was studied by X-ray diffraction. It was found that the c-(Ti,Zr,Al)N solid solution of substitution type is the basis of the (Ti,Zr)_1–xAl_xN (0.06 ≤ x ≤ 0.65) system. For the (Ti,Zr)_1–xSi_xN system (0.13 ≤ x ≤ 0.41), a dual-phase structure composed of a nanocomposite on the basis of the c-(Ti,Zr)N solid solution and grainboundary amorphous a-SiN_y phase is typical. Appearance of the second a-SiN_y phase promotes an amorphization of the films. Vacuum annealing of the films investigated at temperatures up to 1000°C does not lead to decomposition of the solid solutions which constitute the films. Both rather high deposition temperature (600°C) and stoichiometric nitrogen content can be the reasons for thermal stability of the films. Annealing-induced Al depletion of c-(Ti,Zr,Al)N solid solution grains is observed in (Ti,Zr)_1–xAl_xN films caused by the growth of the AlN based wurtzite phase at the grain boundaries.