Electrochemistry of copper post-CMP cleaning examined in combination with brush-scrubbing in a malonic acid solution.

• A malonic acid solution at neutral-pH is used for post CMP cleaning of copper. • Brushing combined with malonic acid's chemistry removes ∼ 97 % of CMP residues. • Relative roles of chemistry and brush scrubbing in post CMP cleaning are examined. • Tribology-coupled electroanalysis effectively probes post CMP cleaning mechanism. • An electrochemical method is demonstrated to assess post CMP cleaning efficiencies. Post-CMP cleaning (PCMPC) is used in the fabrication of integrated circuits to remove unwanted residues of chemical mechanical planarization (CMP) from wafer surfaces. PCMPC combines (electro)chemical surface reactions in a cleaning solution with mechanical scrubbing by a brush. Using tribo-electrochemical protocols, the present work simultaneously probes the (electro)chemical and mechanical functions of PCMPC and determines the corresponding cleaning efficiency. Employing malonic acid as a cost effective, environmentally compatible cleaning solution for copper, it is demonstrated how this electroanalytical approach can facilitate the tasks of developing and evaluating effective PCMPC solutions. The results indicate that malonic acid in a pH neutral environment removes Cu-oxides and their co-adsorbed organic residues of CMP. A detailed electrochemical procedure is illustrated for quantifying the residue removal efficiency of PCMPC, and the role of brush scrubbing in the overall cleaning process is identified. [ABSTRACT FROM AUTHOR]