The Post CMP Cleaning step in the MET4 module immediately follows the planarization of the bulk Copper (Cu) and the Ta-based liner P2.At this stage, the wafer surface is heavily contaminated with residual abrasive particles, metallic ions, and organic corrosion inhibitors P1.Before proceeding to the deposition of the ILD 4-1 layer, these residues must be completely removed to ensure proper dielectric adhesion and to prevent electrical leakage paths between adjacent interconnects P2.Unlike the ST