Development of the Cleaning Method Using High-Speed Shear Flow of Ultrapure Water (2nd Report)

-Study of Cu removal mechanism by cleaning using high-speed shear flow of ultrapure water-

Abstract

We notified that Cu concentration on the Si substrate surface could be reduced to less than 2.4×10⁹atoms/cm² by the cleaning method using high-speed shear flow of ultrapure water. But the mechanism of Cu removal in this cleaning method was not clarified. In this study, we have attempted the clarification of Cu removal mechanism by the observation and analysis of the Si substrate surface after the cleaning using high-speed shear flow of ultrapure water and SPM (sulfuric acid-hydrogen peroxide mixture) cleaning. In consequence, we showed that a lot of bosses were not observed on the Si substrate surface contaminated by Cu after the cleaning using high-speed shear flow of ultrapure water though after SPM cleaning. And we supposed the reasons about removing Cu from Si substrate and not forming a lot of bosses on the Si substrate surface by Pourbaix diagram for Cu-H₂O system.