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In the semiconductor industry, there is a growing trend of using smaller ceria nanoparticles (CNPs) during the Swallow Trench Isolation (STI) CMP process. However, the use of these CNPs has made it more difficult to clean residual particles from the SiO2 film surface after CMP. This study aimed to investigate the effects of gas-dissolved water (GDW) on CNP surfaces and the mechanical cleaning effects of nucleated bubbles applying megasonic conditions. The study found that CNP surface was reduced by H2 GDW and CO2 GDW, but oxidized by O2 GDW. The concentration of Ce3+ ions on CNP surfaces changed from 18.64% to 19.48%, from 20.31% to 21.94%, and from 21.27% to 19.22% when CNPs were respectively immersed in H2 GDW, CO2 GDW, and O2 GDW for 3 to 12 hours. Adhesion energy between CNPs and SiO2 particle surface, following immersion of CNPs in H2 GDW, CO2 GDW, and O2 GDW for 6 hours, was found to be 6.06E-16 J, 6.18E-16 J, and 4.83E-16 J, respectively. After cleaning with GDW and applying megasonic, residual Ce ion concentrations on the SiO2 film surface were found to be 0.06 ppb, 0.41 ppb, and 0.10 ppb for H2 GDW, CO2 GDW, and O2 GDW, respectively.
Park et al. (Fri,) studied this question.