Defect enhancement in periodic masks using 1/2-Talbot effect |
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Authors: | Eugenio Garbusi José A Ferrari |
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Institution: | Instituto de Física, Facultad de Ingeniería (UdelaR), Julio Herrera y Reissig 565, Montevideo 11300, Uruguay |
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Abstract: | In this paper, we present a simple system for defect enhancement in periodic masks, enabling in this way their rapid localization. The system uses the fact that periodic structures under coherent illumination generate replicas of itself displaced half period at certain distances (1/2-Talbot’s length). Projecting back this displaced self-image onto the mask creates a suppression of the periodic structure. If the mask presents defects, the cancellation of the periodic structure allows their detection since the self-imaging phenomenon occurs only for the periodic structure. The technique may be applied to transmission masks like semiconductor wafers, photomasks for integrated circuits or LCD panels. |
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Keywords: | Talbot effect Optical inspection |
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