EFFECT OF ADDED SURFACTANT ON OXIDE TO POLYS1LICON SELECTIVITY DURING CHEMICAL MECHANICAL POLISHING

摘要

In this study, the effect of added surfactant on oxide to polysilicon selectivity during chemical mechanical polishing (CMP) has been investigated. Slurries with surfactants such as Brij surfactants, polyethylene oxide (PEO) and ethylene oxide (EO)-propylene oxide (PO)-EO triblock copolymer enhanced oxide to polysilicon polishing selectivity. Although a current commercial oxide slurry has low oxide to polysilicon selectivity of 0.5:1, slurries with surfactants show an improved polysilicon selectivity due to a combined effect of adsorption and interfacial adhesion of surfactant molecules on the polysilicon surface. The selectivity of the Brij surfactant added slurries displayed strong dependency on the hydrophile-lipophile-balance (HLB) value rather than the type of alkyl group or the chain length. Especially, Brij52 with low HLB value gave an oxide to polysilicon selectivity of 9.3 which is 17 times higher than the selectivity for the commercial oxide slurry. Also, a high molecualr weight polymeric surfactant such as PEO gave greater selectivity than a low molecular weight surfactant such as PEO. Further, it was found that slurries with surfactants worked effectively in damascene structure pattern having polysilicon stopping layer.