Evaluation of post-Cu CMP cleaning of organic residues using microfluidic device

The removal kinetics of organic residues remaining after chemical mechanical planarization (CMP) were studied using a microfluidic device that monitored the open circuit potential (OCP) response to rapid changes in electrolyte composition. Citric acid at various pH values, ranging from 2 to 9, was investigated as the cleaning solution. It is found that the optimized pH value of the citric-acid cleaning solution is 5. The in situ electrochemical methodology is effective for preliminary evaluation or optimization of cleaning solutions. In addition, the electrochemical methodology may be utilized in screening inhibitors used in CMP process for their susceptibility to post-process cleaning.