High frequency guided wave defect imaging in monocrystalline silicon wafers

摘要

Micro-cracks can be induced in thin monocrystalline silicon wafers during the manufacture of solar panels. Highfrequency guided waves allow for the monitoring of wafers and characterization of defects. Selective excitation of thefirst anti-symmetric A0 guided wave mode was achieved experimentally using a custom-made wedge transducer. TheLamb wave scattered field in the vicinity of artificial defects was measured using a noncontact laser interferometer. Thesurface extent of the shallow defects varying in size from 30 μm to 100 μm was characterized using an opticalmicroscope. The characteristics of the scattered wave field were correlated to the defect size and the detection sensitivitywas discussed.