Systematic investigation on the ultratrace analytical monitoring of anionic surfactants on silicon wafer surface by capillary electrophoresis using designed experiments

Abstract

Surface purity of silicon wafers is an important parameter to monitor to achieve high yield of semiconductor devices in a production line. Surfactants are used to facilitate the removal of particles from bare and structured wafers surface by reducing the surface potential. Surfactant residues after the final cleaning steps may be present on wafer surface this will cause detrimental effects on electronic devices. The objective of this work is the development of a robust method for ultra-trace analytical determination of dodecylbenzene sulfonate on silicon wafer surfaces with high hydrofluoric acid matrix using capillary electrophoresis. Taguchi methodology as a systematic optimization tool is used for determination of in-capillary precondition procedure for surfactant analysis. The percent recovery for wafer surface is between of 80% and 108% in vapor phase decomposition (VPD)-matrix. Together with the optimized method and high-resolution detector cell, the LOD and LOQ are 6.5 ppb and 24.5 ppb respectively.