Influence of phosphorus-induced point defects on a gold-gettering mechanism in silicon

Deep-level transient spectroscopy (DLTS) and neutron-activation analysis have been applied to measure the gold distribution after a phosphorus gettering step. It is found that the gettering mechanism is able to operate without induced dislocations but depends mainly on the surface phosphorus concentration. For example, when Cs=1021/cm3, the gold concentration is reduced by a factor 103 over the whole thickness of a wafer. This Au trapping phenomenon is attributed to the presence of a phosphorus-induced point defect and related to the emitter push effect mechanism.