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