CMP: AIMING FOR PERFECT PLANARIZATION

摘要

This paper presents a new ceria-based system for STL It involves a direct planarization approach, where planarization efficiency has been greatly improved. This utilizes further development of proprietary additives following the approach from ref, the suspension of the ceria was greatly improved to enable use as a one component system. Ceria abrasive chemically modified slurries were investigated for low defectivity planarization on STI pattern wafers. Planarization efficiency and remaining step-height were evaluated versus polishing time against current standard slurries. Optimization was achieved with planarization efficiency an order of magnitude greater than conventional slurries. Our approach with the formulation typical of commercially available product that provided a high selectivity ceria slurry did not achieve the desired planarization anticipated. Using chemically modified ceria-based slurry we achieved a with very low removal rate on blanket wafers and a high planarization rate on patterned wafers. The authors demonstrated complete planarization of a benchmark 5x5 mm active area on patterned wafers. The chemically modified slurry demonstrated that direct STI could be achieved without the need for reserve mask etching processes and dummy structures.