PVA Brush Technology for Next Generation Post-CMP Cleaning Applications

Abstract

This paper presents recent developments in the design and characterization of chemical-mechanical planarization (CMP) consumables, with specific emphasis on post-CMP (PCMP) cleaning polyvinyl alcohol (PVA) brushes. Special nodule design and modified charge super-clean PVA brushes were developed to obtain more effective near-wafer-edge cleaning and significantly improved overall PCMP cleaning performance in advanced applications. The profiled nodule-top, elongated-nodule brushes provided optimum cleaning contact area and contact force at the brush-wafer interface in the wafer edge region, whereas the negative zeta potential (NZP) modified PVA brushes resulted in significantly improved PCMP cleaning efficiency in smaller-node high-sensitive copper/low-k processes. The effects of extended exposure of one alkaline and four acidic PCMP cleaning chemistries on brush PVA discoloration and properties were investigated. All the tested acidic cleans caused significant discoloration, whereas the alkaline clean caused minimal change. Further, all the tested chemistries did not show much change in PVA physical properties and compressive stress.