Impact of Metal-Ion Contaminated Silica Particles on Gate Oxide Integrity

Abstract

The impact of metal-ion contamination (present on wafer surface before oxidation) on gate oxide integrity (GOI) is well known in literature, which is not the case for clean silica particles [1, 2]. However, it is known that particles present in ultra-pure water (UPW) decrease the random yield in semiconductor manufacturing [3]. The presence of silica in UPW is common knowledge. UPW has also a certain content of metal ions, which can be attached to silica. That means, when a wafer is in contact with UPW metal ion can directly and/or in form of a silica-metal conglomerate be attached to the wafer surface. That means, it is not known in which form metal-ion contamination will deteriorate GOI the most. In order to receive more clarity in this field a short-loop study was set up, where we want distinguish between the impacts of - low metal ion contamination (Calcium), - clean silica particles (330nm) contamination, - silica particles with metal-ion core (330nm) contamination, and - metal-ion contamination at similar concentration as the metal-ion core of the particles on GOI (uniform and none uniform distribution).