Automated CMP multi-slurry ratio tuning for Defect Reduction : APC : Advanced Process Control

Elevated polishing time was discovered to correlate to high defectivity and yield loss on a Floating Gate Poly CMP process. This process has a high rate slurry for bulk removal and a low rate slurry for final polish and surface roughness reduction. The polish time for the bulk slurry is the primary process control method. An automated process control was developed to maintain the bulk slurry polish time in a range that minimizes defectivity, while ensuring the critical Poly thickness remains on target.