CMP Defect Reduction and Mitigation: Practices and Future Trends
An exponential correlation is found to exist between the number of added defects on polished blanket wafers and the inverse of defect size for particulate CMP defects. Smaller surface defects are much more abundant and more difficult to remove. Pad surface pore geometry can influence the transport of debris during polish, and hence modulate the generation of defects such as polish residue (PR), foreign materials (FM), and scratches. The conditioner and conditioning process also plays a role. Besides the selection and optimization of cleaning chemical and post cleaning process itself, overall CMP defect reduction and mitigation must take into account the events and consumables in the polish modules. The drive towards finer and 3D device geometry presents further challenges in defect detection and reduction.