Micro-scratches generation mechanism by copper oxides adhered on silica abrasive in copper chemical mechanical polishing

Chemical mechanical polishing (CMP) may introduce micro-scratches on the copper surface, posing a substantial challenge for developing advanced technology nodes. This study used macroscopic CMP and microscopic atomic force microscopy to investigate the micro-scratches generation mechanism in copper CMP from the perspective of abrasive particles. In the near-neutral slurry containing a low concentration of H2O2, copper can be oxidized to cuprous oxide and/or cupric oxide, forming a fragile oxide layer that can be removed by silica abrasive particles. The removed copper oxides can be adhered on the silica abrasive particles through electrostatic attraction, modifying the surface state. The adhered copper oxides possess irregularities and high hardness, likely inducing high contact stress locally and resulting in micro-scratches on the copper surface.