To ensure successful mass production for GAA MBCFET structures and beyond, EUV overlay technology has advanced to withstand extreme process conditions. Commonly used method for its effectiveness was using overlay feedforward strategy to compensate upcoming critical layers such as ‘N+1’, or ‘N+2’ layer with current layer ‘N’ assuming the applied layers have kindred stack properties with identical overlay targets. Overlay feedforward strategy has been developed internally in great sophistication to significantly enhance on product overlay(OPO) proven also in mass production phase. However, it has been recognized that using aforementioned strategy to specific products rooting from GAA MBCFET structure may not be as beneficial as anticipated. In this paper, we would like to present the source of this strange phenomenon largely due to wafer warpage, in which we provide comprehensive solutions to measure, contain and permanently eradicate the originating in-coming process. After implementation of the authors' solution, overlay feedforward strategy demonstrated to be efficacious even for highly biased process excursions.
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