Study of sol-gel type ceria particle for CMP process in leading-edge CMOS device

With continuous shrink in the size of integrated circuits, the complexity, and the number of processing steps continue to increase. CMP is one of the crucial steps to maintain good process yields. The number of FEOL CMP steps has increased drastically in leading-edge nodes and also made the process requirements more stringent. In order to meet these requirements, selection of the right consumables is very critical. Slurry plays a vital role in CMP processes and there is always a big requirement for extreme selective slurry with self-stopping capabilities. Also, the final CMP surface should be very smooth with no defects and scratch free. Ceria-based slurries are gaining importance as they have good planarization and self-stopping capabilities in the latest device technology. In this paper, we have investigated some of the notable ceria types such as composite ceria, calcined ceria and wet ceria. The particle hardness of wet ceria is 1/25 th level compare to other ceria particles. This helps the surface be defect and scratch-free. In our experiment, 60% reduction in surface roughness and 90% reduction in scratches on patterned wafers was observed.