PEALD AlN: Controlling growth and film crystallinity

Abstract We report on the growth kinetics and material properties of aluminium nitride (AlN) films deposited on Si(111), with plasma enhanced atomic layer deposition (PEALD). Tri‐methyl aluminium (TMA) and NH3‐plasma were used as the precursors. The ALD window was identified in terms of the process parameters, and it showed that a 0.1 s of TMA pulse, 8 s of NH3‐plasma pulse, and 350 °C were the optimal conditions for ALD to occur. In‐situ spectroscopic ellipsometry (SE), using a Cauchy optical model, was used to monitor the film growth in real time. The composition of the as‐grown AlN films were determined by X‐ray photoelectron spectroscopy (XPS), which revealed Al/N compositions of approximately 46% and 53%, also with low impurity (O, C) levels. The film crystallinity, measured with grazing incidence X‐ray diffraction (GIXRD), showed polycrystalline hexagonal (wurtzitic) crystalline planes. Finally, several techniques were employed to influence the film crystallinity. These included: ALD at different plasma powers and temperatures, in‐situ treatment of the Si(111) wafer with different plasma parameters (composition, power, duration) prior to deposition, and ALD on Si(100) and SiO 2 substrates. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)