Reversible Tuning of the Surface Chemical Reactivity of Titanium Nitride and Nitride−Carbide Diffusion Barrier Thin Films

Abstract

The chemical properties of titanium nitride−carbide (TiNC) and titanium nitride (TiN) films deposited on silicon are investigated comparatively, showing that the surface reactivity of nitride-based films can be modified precisely and reversibly by controlling the surface elemental composition. These materials are used as diffusion barrier films, and therefore understanding their surface chemistry is key for controlling further deposition steps during interconnect metallization. Chemical vapor deposition (CVD) using Ti[N(CH3)2]4 leads to the formation of TiNC, and nitridation of this film through postannealing under NH3 decreases significantly the carbon content on the surface, leaving essentially a TiN surface, as characterized through the use of spectroscopic, depth-profiling, and microscopic techniques. As determined by the temperature-programmed desorption (TPD) studies of ethylene (carbidization reagent) and dimethylamine (decomposition product of the deposition precursor), the TiN surface is more rea...