The growth of tungsten nitride carbide, WNxCy, films obtained by atomic layer deposition is determined by the density and type of substrate reactive sites. WNxCy film growth on silicon dioxide is determined by the silanol group concentration, which is a function of the substrate growth temperature. An enhanced WNxCy growth is observed when WNxCy is deposited on hydrogen-terminated silicon due to an initial chemical vapor deposition growth. On silicon nitride, a short transient regime is observed in comparison to the carbide and oxide surfaces attributed to enhanced binding of the triethylboron precursor and compatibility at the interface silicon nitride/WNxCy. (c) 2006 The Electrochemical Society.