Novel phosphate-functionalized silica-based dispersions for selectively polishing silicon nitride over silicon...

We prepared and characterized novel phosphate-functionalized silica particles, and showed that, by using them during chemical mechanical polishing, both silicon dioxide and polysilicon removal rates can be suppressed while simultaneously enhancing silicon nitride removal rates. We achieved a silicon nitride:silicon dioxide:polysilicon removal rate selectivity of (>20):1:1. The measured removal rates of silicon dioxide, silicon nitride, and polysilicon are related to the electrostatic interactions and chemical reactivity between these films and the modified-silica abrasives.