Localization of Inorganic Impurities in Silicon Samples by Sequential Etching and ICP-MS Detection

The investigation of trace elemental contaminations in silicon material is of major interest as it has detrimental impacts for further process steps. Thus, the detection of surface impurities in silicon samples was investigated by sequential etching steps followed by ICP-MS measurements. Due to variations of etching solutions containing HCl, HF and HNO3 trace element contents could be assigned to different layers of silicon samples, like the outer surface, the silicon oxide and the sub-oxide layer as well as the bulk material. The method is not only suitable for silicon wafers but can also be adapted to powdery samples like etched silicon nanowires and kerf silicon. In this study, we show exemplarily the sequential etching procedure for metallurgical silicon powder samples. This method enables the layer dependent quantification of impurities in silicon samples.