Novel Diffusion Barrier with Ultra-Thin Silicon Nitride Cap Layer

A novel type of diffusion barrier, consisting of a conducting layer whose surface is enriched with silicon nitride, was developed. The new barrier was prepared by thermal decomposition of a metal-organic precursor, tetrakis(dimethylamino) titanium (TDMAT), followed by in-situ silane anneal and subsequent surface nitridation. It combines the conformality and conductivity advantages of the underlying diffusion barrier with the good barrier properties of silicon nitride. The new barrier films were characterized by sheet resistance measurement, secondary electron micrographs (SEM) and x-ray photoelectron spectroscopy (XPS). The thermal stability of Cu/capped barrier/Si multilayer structures was demonstrated.