13 March 2012 CDU prediction based on in-situ image measurements
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Control of CD uniformity is a key aspect of IC manufacturing. Ability to accurately predict wafer-measured CD prior to exposure is critical to CDU control. In this paper we present a method to calculate a predicted CD value based on in-situ measurements, and estimate CD uniformity across the field of an exposure tool. This method is based on direct measurements of aerial image using a sensor built into the wafer stage of SMEE SSA600-series exposure scanners. Using this sensor to measure image of several features at 9 points across the exposure field, we compare predicted CD and ADI CD obtained using a standard wafer process and CD-SEM.
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A. Bourov, A. Bourov, J. R. Cheng, J. R. Cheng, L. Duan, L. Duan, J. Yang, J. Yang, J. Min, J. Min, "CDU prediction based on in-situ image measurements", Proc. SPIE 8326, Optical Microlithography XXV, 83261T (13 March 2012); doi: 10.1117/12.916629; https://doi.org/10.1117/12.916629

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