Abstract The Ta–Si–N thin films were prepared using a reactive magnetron co-sputtering with and without an alternating target shutter control at different N 2 flow ratios (FN 2% = FN2/(FAr + FN 2) × 100%) of 3–20%. The evolution of microstructure, composition, morphology, resistivity, and nanomechanical properties of Ta–Si–N films was characterized by X-ray diffraction (XRD), energy dispersive X-ray spectrum (EDS), scanning electronic microscopy, four-point probe technique and nanoindentation, respectively. The broad XRD peaks of Ta–Si–N films with and without target shuttering at low 3–10 FN 2% showed the microstructure was quasi-amorphous i.e. nanocrystalline grains embedded in an amorphous matrix. The quasi-amorphous Ta–Si–N without target shuttering was transformed into the polycrystalline phase at 20 FN 2% while that with target shuttering still remained in quasi-amorphous microstructure due to the increased Si content. The resistivity of quasi-amorphous Ta–Si–N films with and without target shuttering at 3–10 FN 2% ranged in 262–385 μΩ cm while that of Ta–Si–N films at 20 FN 2% was much higher at 976–9925 μΩ cm. The hardness of quasi-amorphous Ta–Si–N films with and without target shuttering at 3–10 FN 2% ranged from 14.3 to 18.5 GPa while that of polycrystalline Ta–Si–N film was about 10.3 GPa. Quasi-amorphous Ta–Si–N films had much lower resistivity, higher nanohardness and smooth morphology compared to the polycrystalline film.