Growth of cubic-TaN thin films by plasma-enhanced atomic layer deposition

Abstract

Low resistivity cubic-TaN thin films were grown by plasma-enhanced-atomic layer deposition using TaCl5 as the metal precursor and hydrogen/nitrogen plasma. The deposition has been performed by alternate exposures of TaCl5 and the plasma of hydrogen and nitrogen mixture. X-ray diffraction analyses show that the film is composed of cubic TaN grains, in contrast to the previously reported highly resistive Ta3N5 films grown by Ta3N5 grown by TaCl5 and NH3 as precursors. The composition and thickness were measured by Rutherford backscattering and hydrogen concentrations were obtained by forward recoil elastic spectrometry as a function of growth parameters. The N content of the cubic TaN films was controlled from N/Ta=0.7 up to 1.3 by changing nitrogen partial pressure. The resistivity and growth rate increase with increasing N concentration in the film. The Cl and H content were found to be strong functions of plasma exposure time and growth temperatures, and TaN films with resistivity as low as 350 μΩ cm were obtained at a low growth temperature of 300 °C.