This Post CMP Cleaning step immediately follows Metal 3 (MET3) Cu and Ta-based liner CMP and prepares the wafer for ILD 3-1 deposition P1.During the preceding Cu and barrier CMP steps, the wafer surface becomes heavily contaminated with abrasive particles and organic corrosion inhibitors, such as benzotriazole (BTA) P1, P2.These residues render the copper surface highly hydrophobic, which can cause severe drying defects and poor adhesion of the subsequent stacking layers P2.Therefore, this clean