Atomic layer deposition of HfN films and improving the film performance by annealing under NH atmosphere

HfN x films were deposited by atomic layer deposition (ALD) using Hf[N(CH 3 )(C 2 H 5 )] 4 (TEMAHf) and NH 3 as the Hf-precursor and reactant gas, respectively. A precleaning step using TEMAHf as a reducing agent was devised to minimize the oxygen concentration in the as-deposited film. Consequently, the oxygen concentration in the film was reduced by ∼66%. In addition, the carbon impurity concentration caused by the side effects of the precleaning step and the remaining oxygen concentration were effectively reduced through post-NH 3 annealing. The oxygen concentration inside HfN x decreased as the annealing temperature increased. HfN x films annealed under 900 °C showed dielectric properties similar to hafnium oxynitride (HfO x N y ). However, films annealed over 950 °C transformed into a more electrically conducting HfN film, showing a resistivity of ∼10 6 μΩ cm. Flowchart illustrating how the films are deposited (a) without and (b) with cleaning step, and Auger electron spectroscopy depth profile of 15 nm HfN x deposited with precleaning step, before annealing (c) and after 900 °C annealing at NH 3 atmosphere.