Knowledge-directed inspection for complex multilayered patterns

Combining the knowledge-based processing with image processing is considered a key issue in the future of visual inspection of complex patterns such as multilayered semiconductor wafers. However, present technology restricts this combination, mainly because of the exhaustively long time usually required for each type of processing. To cope with this situation, a unique knowledge-directed image processing method is proposed, in which every image processing step is controlled in real time by parametric knowledge driven by design patterns. The resulting structure of the image processor is a pipeline, in which each piece of knowledge is embodied as a combination of a hardware processing unit and control unit. In this paper the types of knowledge and their implementation are explained, and an inspection machine for logic IC wafers based on this pipelined knowledgedirected image processing is introduced.