Effect of Heat Treatment on Structural Characteristics and Electric Resistance in TaNxThin Film Deposited by RF Sputtering

TaNx thin films were deposited by RF magnetron sputtering and heat-treated from 300 to 700°C. The structural characterization of the deposited films was carried out by the analysis of X-ray diffraction patterns obtained using a polycrystalline diffractometer and the variation of electric resistance during heat treatment was studied in association with the measured and calculated structural characteristics. The measured X-ray diffraction patterns show that the phase of the film changes from near amorphous phase to FCC TaN of NaCl type with increasing heat-treatment temperature. The electric resistance rapidly decreased with heat treatment at 300°C and increased from 500 to 700°C. The decrease of sheet resistance can be explained by the release of misfit strain energy, as based on the decrease of interplanar spacing, and the increase of sheet resistance at elevated temperature is supposed to be caused by the formation of Ta oxide on the surface of the film.