Effect of alkaline agent with organic additive in colloidal silica slurry on polishing rate selectivity of polysilicon-to-SiO2 in polysilicon CMP

Abstract

We have studied the effects of varying the size and the concentration of the abrasive in colloidal silica slurry and the concentration of different alkaline agent with organic polymer were investigated. We found that the surface roughness of the polysilicon film with TMAH was better than other alkaline agent. In addition, with increasing TMAH concentration, the polishing rate of polysilicon and the polysilicon-to-oxide polishing rate selectivity were reduced after an initial increase. And the organic polymer suppresses the polishing rate of the oxide film. We explained the reason by difference of hydrophobicity between polysilicon and oxide film with addition of alkaline agent and PAM in order to elucidate the mechanism of increase in polysilicon-to-oxide polishing rate selectivity.