特徴比較によるLSIホトマスクパタ-ン外観検査の自動化

概要

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This paper describes a defect recognition method which can be applied for automating visual inspection of LSI photomasks. The method recognizes defects such as short circuits, protrusions and pinholes. It can be classified as socalled "comparison method" in which the pattern under inspection is compared with a standard pattern and an unoverlapped portion of the patterns is regarded as a defect. The usual comparison method has a drawback: it can not detect defects smaller than the alignment error of the two patterns.Using the newly-developped comparison method, these small defects as well as bigger ones, can be detected. The method detects defects by extracting local features from the compared two patterns and by comparing them, instead of simply performing an exclusive-or operation of the two patterns.The mechanical, electrical and optical structure of the automatic inspection system for LSI photomask patterns, which utilizes this method, is also described. The system detects defects as small as 0.8 micronmeter at the 100% assurance. The inspection speed is 90 minutes per 100×100mm photomask.
公益社団法人計測自動制御学会の論文