Atomic Layer Deposition of AlN with Tris(Dimethylamido)Aluminum and NH₃

Abstract

Atomic layer deposition of aluminum nitride on Si wafers using tris(dimethylamido)aluminum and ammonia has been investigated in the temperature range from 180 to 400°C. Saturated growth behavior not observed with NH3 pulsed in continuous mode has been achieved in NH3 exposure mode. Thin AlN films have been analyzed by spectroscopic ellipsometry and SIMS for optical and chemical properties, X-ray diffraction for crystallinity, and mercury probe for electrical properties. Polycrystalline and high purity AlN films have been obtained at 300°C or higher. A high dielectric constant in the range of 7.4-7.7 and high breakdown field of 5.3-5.6 MV/cm with relatively low leakage current in the 10-7 to 10-8 A/cm2 range at 2MV/cm have been obtained for AlN films deposited between 300 and 400°C in NH3 exposure mode.