Study of overlay in EUV/ArF mix and match lithography

In preparation for EUV lithography (EUVL) in high volume manufacturing, a preproduction ASML NXE:3100 step-and- scan system was used to assess overlay performance under mix-and-match between EUV and ArF lithography, which will be critical for the successful insertion of EUV lithography into high volume 1x node production. Overlay sources of variation associated with EUV were investigated, including mask pattern-placement error (PPE), scan direction, and processing order. Furthermore, this study also looks into overlay control strategy development specifically for EUV/ArF mix-and-match lithography. Systematic and random overlay components will be discussed, as well as possible overlay modeling and control options.