We use DFT to investigate an atomistic mechanism for the ALD of hafnium nitride films grown using Hf[N(CH3)(2)](4) and NH3. We find a ligand-exchange mechanism similar to those thought to occur in the ALD Of HfO2 using the same Hf source and H2O. Although the Hf[N(CH3)(2)](4) half-reaction at NH* sites has a barrier similar to that of reaction with OH* sites, the barrier for the NH3 half-reaction on the Hf [N(CH3)(2)](x)(*), terminated surface is significantly larger than for reaction between H2O and Hf [N(CH3)(2)](x)(*) Thus, the NH3 half-cycle will be prone to oxygen incorporation into Hf-nitride from residual H2O. (c) 2005 Elsevier B.V. All rights reserved.