Organic contaminant detection of silicon wafers using negative secondary ions induced by cluster ion impacts

Emission yields of carbon and hydrogenated carbon cluster secondary ions CpHq+/- (P >= 1, q >= 0) originating from organic contaminants on a silicon wafer are compared between monoatomic (0.5-MeV/atom C-1(+)) and cluster ion (0.5-MeV/atom C-8(+)) impacts using time-of-flight (TOF) secondary ion mass spectrometry. CpHq- for the cluster ion impact exhibits the highest emission yield per incident atom among CpHq+/- with the same p number. The highest relative CpHq- emission yield for the cluster ion impact reaches similar to 20 and similar to 60 times higher in comparison with those of CpHq- and CpHq+ with the same p number for the impact of the monoatomic ion with the same velocity, respectively. Combination of negative secondary ion TOF measurements with cluster impact ionization is a promising tool for highly sensitive detection of organic-contaminants on silicon wafers. (C) 2008 The Japan Society of Applied Physics.