Embedded Defect Depth Estimation Using NIR Model-Less TSOM

Defect inspection in the packaging process requires high sensitivity and throughput. Through-focus Scanning Optical Microscopy (TSOM) can measure dimensions smaller than the resolution limit of optical microscopes, making it a subject of extensive research. Particularly, the model-less TSOM, which does not require separate modeling, is faster and computationally less intensive than model-based TSOM. This paper applies NIR model-less TSOM to measure the depth of embedded defects in OLED displays. As a result, we successfully estimated the depth of 43 embedded defects with an accuracy of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.36\ \mu \mathrm{m}$</tex> (DOF/17.8).