Atomic Layer Deposition of Aluminum Nitride Using Tris(diethylamido)aluminum and Hydrazine or Ammonia

Abstract

Aluminum nitride (AlN_x) films were obtained by atomic layer deposition (ALD) using tris(diethylamido) aluminum(III) (TDEAA) and hydrazine (N₂H₄) or ammonia (NH₃). The quartz crystal microbalance (QCM) data showed that the surface reactions of TDEAA and N2H4 (or NH₃) at temperatures from 150 to 225°C were self-limiting. The rates of deposition of the nitride film at 200°C for systems with N₂H₄ and NH₃ coincided: ~1.1 Å/cycle. The ALD AlN films obtained at 200°C using hydrazine had higher density (2.36 g/cm³, 72.4% of bulk density) than those obtained with ammonia (2.22 g/cm³, 68%). The elemental analysis of the film deposited using TDEAA/N2H4 at 200°C showed the presence of carbon (~1.4 at %), oxygen (~3.2 at %), and hydrogen (22.6 at %) impurities. The N/Al atomic concentration ratio was ~1.3. The residual impurity content in the case of N₂H₄ was lower than for NH₃. In general, it was confirmed that hydrazine has a more preferable surface thermochemistry than ammonia.