Proceedings PaperStatistical method for influence of exposure and focus error on CD variation
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Lithographic process fluctuations are treated as statistical values and reduced to effective exposure and focus error. The distribution function of CD is derived in the analytical formula in order to calculate CD yield which is important to device characteristics. The process fluctuations are represented as a summation of mean value for interval of process control and deviation from the mean value. New process window for the mean values is proposed using the CD yield. The process window expands when the frequency of process control increases. Quantitative evaluation is performed under the allowable CD yield.