Determination of the bulk lifetime of bare multicrystalline silicon wafers

The determination of the bulk lifetime of bare multicrystalline silicon wafers without the need of surface passivation is a desirable goal. The implementation of an in-line carrier lifetime analysis is only of benefit if the measurements can be done on bare unprocessed wafers and if the measured effective lifetime is clearly related to the bulk lifetime of the wafer. In this work, we present a detailed experimental study demonstrating the relationship between the effective carrier lifetime of unpassivated wafers and their bulk carrier lifetime. Numerical modelling is used to describe this relationship for different surface conditions taking into account the impact of a saw damage layers with poor electronic quality. Our results show that a prediction of the bulk lifetime from measurements on bare wafers is possible. Based on these results we suggest a simple procedure to implement the analysis for in-line inspection. Copyright (C) 2010 John Wiley & Sons, Ltd.