The Metallic Contamination Related Whisker Defect During Deposition and Its Removal

Abstract

We have investigated the whisker defect generation during SiH4 -based silicon film deposition, which is mostly related to metallic impurities on the surface. The metallic impurities from various dry etching systems are heavily detected during device fabrication. The contamination level on silicon surface is around three orders of magnitude higher than that of allowance level. Furthermore, the copper impurities contaminated on the a-Si surfaces are hardly removed even by the acidic solutions with high oxidation-reduction potential values. The contaminants generated the abnormal film growth which was detected after a-Si film deposition. The defect is more than 500nm in size (denote Whisker defect). They can cause serious CMP scratching on the surface or pattern lifting at post process as well as device yield drop. When the a-Si film was deposited on a-Si film, the amount of defect observed was greater than those of other surfaces.