Optimized salicide clean to reduce post fill defectivity

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 seen 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.