Cellular Toxicity Assessment and Environmental Impact of Pre- and Post-CMP Nanoparticle Slurries

Abstract

Nanoparticles (NPs) of silica, ceria and alumina are used as polishing slurries for Chemical Mechanical Planarization (CMP). However, the regulations for use and toxic levels of ENPs in slurries are yet to be established. NPs’ reactivity along with their cellular toxicity and uptake are largely dependent on their physicochemical characteristics. This paper will also present the correlation between physicochemical properties of NPs and toxicity level so as to design and develop benign CMP ENPs. The current study will present a comparison between pre- and post-CMP slurries containing colloidal silica and ceria NPs. Post-CMP slurry waste were generated by polishing patterned test wafers of HDP oxide were comprehensively characterized using DLS, zeta potential, BET, XRD, FTIR, Raman, SEM and TEM. Next, slurries and waste were exposed to A549 lung epithetical cell lines for 6-48 hours to determine IC50 for cytotoxicity (cell viability and membrane integrity). It was observed that colloidal silica NPs in slurries showed dose-dependent cytotoxicity. Next, using label-free analytical technique, ICP spectroscopy, we observed that pre- and post-CMP ceria ENPs in slurries, exhibited dose-dependent uptake in A549 cells.