Mapping electrically active dopant profiles by field-emission scanning electron microscopy

Secondary electron (SE) image contrast from p-type silicon has been studied using field-emission scanning electron microscopy (FE-SEM). Cross-sectional FE-SEM images of boron-doped silicon heterostructures have been compared with atomic concentration and free carrier profiles measured by secondary-ion mass spectroscopy and electrochemical capacitance-voltage profiling, respectively. FE-SEM image contrast due to dopants has been shown to be electronic in origin. Since electrically active dopant species contribute solely to SE image contrast, FE-SEM can be effectively used to map electrically active dopant profiles in two dimensions with a sensitivity as low as 1016 cm−3.