Formation of tungsten oxide defects during tungsten CMP

초록

Most tungsten chemical mechanical polishing (CMP) processes utilize a subsequent cleaning process referred to as post-CMP cleaning for removal of contaminated layers. Even after a proper post-CMP cleaning has treated polished wafers, several defects such as slurry particles, microscratches, and metallic impurities are still easily observable. In this study, a new kind of defect has been observed at the stage between overpolishing and post-CMP clean in the course of the tungsten CMP. The circular-shape defect was composed of very thin tungsten oxide, which could be removed by several treatments such as HF solution dipping, additional oxide CMP, and the treatment of concentrated ammonium hydroxide solution during poly(vinyl alcohol) brushing. Among them, the most available method without any further process issues was the use of concentrated ammonium hydroxide solution. © 2003 The Electrochemical Society. All rights reserved.