Abstract
We have built an adaptive system capable of detecting submicrometer defects in periodic structures by using real-time holography in photorefractive crystals. We summarize the design and optimization of the defect-enhancement system. We present representative results of 0.2- to 0.5-μm diameter defect detection on two different periodic substrates: chrome-on-glass masks and patterned silicon wafers. On patterned silicon we detect 94% of the 0.5-μm diameter defects with three false positives, while inspecting an area greater than 1 mm2 in 20 s or less. The throughput on the glass masks is somewhat less. To the best of our knowledge, these defects have an area 100 times smaller than those previously detected with any real-time holographic technique.
© 1994 Optical Society of America
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