Applying Regional Level-Set Formulation to Postsawing Four-Element LED Wafer Inspection

With level-set formulation, new contours can emerge during the evolution of contours. A defect inspection system that utilizes the evolution of zero-level contours for segmenting postsawing wafer is proposed in this study. The system utilizes a regional formulation, which improves the level-set segmentation in images with intensity inhomogeneity. An automatic threshold is used to set the initial contour to a contour near the die region. Fewer iterations are thus required to evolve the zero-level set to segment the wafer. Without the needs for filtering in advance, the inspection can be performed directly on the segmented results. The proposed approach outperforms other postsawing inspection methods in terms of accuracy.