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

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 $300 °C.$