Effect of Structure on Reducing Shear Force for Enhanced post-Chemical Mechanical Planarization (p-CMP) Cleaning Efficiency

As integrated circuit size decreases, defect reduction in Chemical Mechanical Planarization (CMP) processes is crucial. Traditionally, a contact cleaning method implementing a polyvinyl alcohol (PVA) brush with cleaning chemistry combines chemical and mechanical forces for defect removal. The PVA brush method is effective at removing primary defects, but the shear force can induce secondary defects. In p-CMP cleaning of Cu substrates, the residue film BTA-Cu⁺ is a detrimental defect formed during CMP polishing. Removing this defect relies on the PVA brush cleaning process with shear force and chemical additives, inducing surface redox reactions through an undercutting mechanism. This work focuses on using additive structures to reduce secondary defects. Different additives efficiency at residue removal through an overcutting mechanism will be tested. The “overcutting” mechanism interacts differently with the BTA-Cu⁺ film than the undercutting mechanism. Techniques will be implemented to assess the removal mechanism of additive structures. Their residue removal efficiency and shear force at the brush-substrate interface will be tested. Preliminary results show the “overcutting” mechanism decreases shear force and reduces secondary defectivity without inhibiting defect removal.