Inline Bulk-lifetime Prediction on as-cut Multicrystalline Silicon Wafers

Solar cell production using multicrystalline silicon is rife with uncertainties about material quality and its impact on subsequent processing steps. However, inline electrical metrology can provide predictive information about bulk silicon quality before processing resources are applied, allowing later metrology to focus on process control. In this work, we show an industrial algorithm which enables bulk lifetime prediction in as-cut multicrystalline wafers, agnostic of wafer origin, using an inline Quasi-Steady-State Photoconductance (QSSPC) measurement setup from Sinton Instruments. In addition, we demonstrate a robust method to extract emitter saturation current density from post-diffusion wafer measurements. Finally, we extend the use of inline QSSPC with a corrected doping measurement that utilizes the theory of grain-boundary potential barriers to interpret excess conductance.