Based on the in-line metrology sampling and modeling, the Advanced Process Control (APC) system has been widely used to control the combined effects of process errors. With the shrinking of overlay budgets, the automated optimized overlay management system has already been necessary. To further improve the overlay performance of SMEE SSA600/10A exposure system, the overlay manager system (OMS) is introduced. The Unilith software package developed by SMEE included in the OMS is used for the decomposition and analysis of sampled data. Several kinds of correction methods integrated in the OMS have been designed and have demonstrated effective results in automated overlay control. To balance the overlay performance and the metrology time, the exponential weighting method for sampling is also considered.
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