Ceria Slurry Particles Removal Optimization

摘要

One of the critical parameters affecting STI CMP with ceria slurry is the establishment of an efficient post-CMP cleaning process that leaves the polished surface defect- and contamination-free. The scrubber and buff recipe parameters as well as cleaning chemistry are the major variables impacting ceria slurry post-STI CMP cleaning process development. Determination of the optimal scrubber and buff recipe parameters and the effect of the cleaning chemical treatment, in terms of maximum defect reduction, is the focus of our study. In order to reduce slurry particles, organic contaminants, and polished surface defect counts to acceptable levels, universal cleaning recipes for the mechanical brush scrubbers have been developed, established, and successfully proven with experimental data. The effect of scrubber recipe parameters such as cleaning chemistry concentration, brush heights, process cleaning time, and wafer rotational speed for Lam Synergy~® as well as the appropriate alkaline post-CMP cleaning formulations on the cleaning efficiency will be discussed. In addition, optimization of the mechanical parameters and cleaning chemistry of the buff process using an Applied Materials Mirra~® polisher was successfully implemented and lead to significant defectivity reduction.