QUALIFICATION OF SILICON WAFERS FOR PHOTO-VOLTAIC CELLS BY OPTICAL IMAGING

摘要

During a solar cell manufacturing process a wafer is characterized by capturing an optical image of light scattered from a surface of the wafer after an etching step that leave a surface of the wafer exposed, for example without emitter diffusion or covering layers on that surface. An image processing operation is applied to the captured image to obtain processed image, the image processing operation being of a type that emphasizes edge features. The processed image to estimate a density of dislocations on the wafer and the density is used as input of a performance prediction algorithm. The application of one or more of the further steps of processing to the wafer is controlled dependent on a prediction of a property obtained from the performance prediction algorithm. Processing may be stopped, or the wafer may be rotated for example.