Crack Detection and Analyses using Resonance Ultrasonic Vibrations in Crystalline Silicon Wafers

An experimental approach for fast crack detection and length determination in full-size solar-grade crystalline silicon (Si) wafers using a resonance ultrasonic vibrations (RUV) technique is presented. The RUV method is based on excitation of the longitudinal resonance vibrations and their real-time frequency response analysis. On a set of identical cast Si wafers with introduced periphery cracks, it was demonstrated that the crack results in a downward frequency shift in a selected RUV peak, increasing the resonance peak band width and a reduction of the peak amplitude. The frequency shift and peak broadening were found to increase with the length of the crack. Finite element analyses modeling supports experimental RUV results and the mechanism of resonance variation