Optimized Salicide Clean To Reduce Post Fill Defectivity CFM: Contamination Free Manufacturing

Post salicidization cleaning is known to be challenging. A marginal process may leave unreactive metal residues on the surface which may lead to gate & active area shorts or contact fill issues. Since the etch rates as well as PRE (Particle Removal Efficiency) are typically lower near wafer edge/bevel region, this area is more prone to residual contamination. Such near edge/bevel contamination is s een to get redistributed on top of the wafer surface during contact fill CMP (Chemical Mechanical Planarization) and cause further downstream contact shorting and lithography artifacts. In this work, a correlation between post salicide particles/flakes and post contact fill CMP defectivity is established. Salicide clean was optimized to reduce the wafer edge/bevel particles and a corresponding improvement was observed of post fill CMP defectivity. The defectivity reduction translated into die yield improvement.