Highly sensitive time-of-flight secondary-ion mass spectroscopy for contaminant analysis of semiconductor surface using cluster impact ionization

To compare emission yields of secondary ions from contaminated silicon wafers between cluster and monoatomic ion impacts, pulsed C₁⁺ and C₈⁺ beams are applied to time-of-flight secondary-ion mass spectrometry. C₈⁺ impact of 0.5 MeV/atom provides higher secondary-ion emission yields per incident atom than C₁⁺ impact of 0.5 MeV/atom for organic and metallic contaminants. Higher peak intensities are also observed for a C₈⁺ ion beam with a reduced energy. The enhanced emission yields of secondary ions originating from the contaminants show that mass spectrometry with cluster impact ionization is a powerful analytical tool for highly sensitive detection of the surface contaminants on the silicon wafers.