Improvement of EUV mix-match overlay for production implementation

摘要

The improvement of overlay control in extreme ultra-violet (EUV) lithography is one of critical issues for successful mass production by using it. Especially it is important to improve the mix and match overlay or matched machine overlay (MMO) between EUV and ArF immersion tool, because EUV process will be applied to specific layers that have more competitive cost edge against ArF immersion multiple patterning with the early mass productivity of EUVL. Therefore it is necessary to consider the EUV overlay target with comparing the overlay specification of double patterning technology (DPT) and spacer patterning technology (SPT). This paper will discuss about required overlay controllability and current performance of EUV, and challenges for future improvement.