An integrated engineering approach to improve wafer edge yield

This paper presents an integrated engineering approach to improve Esort yield at the wafer edge region. In absence of any systematic or parametric issue, the yield loss at the wafer edge region is investigated and initial failure models are then created. Various process improvement schemes which include improved ILD/IMD thickness profile by optimizing Chemical Mechanical Polishing (CMP) recipe, better edge pattern coverage by printing extra lithographic shots and improved Via etch recipes, are explored to resolve the edge losses. These schemes are successfully demonstrated in a production environment with an impressive overall improvement of 5-11 % in Esort yield by reducing the edge loss by more than 70 %. A flow-chart detailing the key improvement steps is presented as well.