CMP Defect Reduction by Pad Design and Particle Engineering

General Requirement

Cu Low–k CMP process for 65nm-generation and beyond.

• Lower defectivity – scratches, corrosion, …
• Minimizing damage of delicate film stacks and structures with low-k dielectric materials
• Higher planarity…Low dishing / erosion
• High removal rates for higher through-put

Causes of Scratches

• Contamination of large particles
• Poorly controlled shape and morphology of abrasives
• Poorly controlled surface status of pad
• Scum (cleanliness)
• Coagulation and precipitation of ingredients and polished materials by sudden pH change during the process
• High polishing down-force

Conventional Approaches to Defect Reduction

Continuous improvement methods to reduce CMP defects include;

• smaller abrasive size,
• lower polishing downforce
• lower polishing speed
• slurry filtration.

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