Effects of Addition of Resin Particles to Ceria-Based Slurry on Pre-Metal Dielectric Planarization

Abstract

The effects of the addition of resin particles to ceria-based slurry on pre-metal dielectric (PMD) planarization were investigated using the chemical mechanical polishing (CMΡ) method. In the next generation complementary metal oxide semiconductor (CMOS) image sensor devices, the PMD film was resized because of the scaling down of device dimensions, and a large convex area is formed. The global planarity after PMD CMΡ becomes poor as the size of the convex area expands because of an effect of deformation of the polishing pad. To improve the global planarity for the large convex area, the addition of the resin particles to the ceria-based slurry was investigated. The addition of the resin particles having the cationic surface functional group was effective to improve global planarity. Based on the analysis of interaction between the resin particles and a film, a new polishing model is proposed. The resin particles absorbed to the surface electrostatically and moved to a concave area by sheer stress during CMΡ. In the concave area, the embedded resin particles protect the film from the abrasion of ceria abrasive and enhance the selectivity of the removal rate between the concave and convex areas, and, as a result, the global planarity is improved.