Investigation and solution of bump-like killer defects

In this study, we investigated the root cause of the conducting bump defects detected by optical inspection system that had the same signature as sampling pattern of electron beam inspection (EBI) at tungsten (W) chemical mechanical polish (CMP) and at copper (Cu) CMP. We found that the bump defects were formed due to the combined effects of EBI and de-ionized (DI) water clean right after EBI. Model of micro plating was proposed and experiment results agreed with the model. We also propose the solution to avoid the yield killing bump defects in future EBI applications.