Patterning with EUVL: the road to 22nm node

Abstract

EUV resists have been developed to be able to print sub-30nm L/S features with EUV ADT having 0.25NA. However, a lithographic performance especially line width roughness (LWR) of EUV resist is not comparable to that of DUV resist. Shot noise effect has been regarded as a main reason for this poor performance of EUV resist [1-2]. Polymer bound PAG with sensitizer is considered as one of solutions to overcome this problem. The champion resist based on polymer bound PAG shows good performance at 30nm L/S and 27nm L/S patterns, although LWR is still worse than target. Additional processes such as smoothing process, chemical treatment process and surfactant rinse process are evaluated. Surfactant rinse process which can improve LWR and pattern collapse simultaneously is regarded as a best solution. A new resist which can overcome out-of band radiation problem is required for EUV lithography. A resist which is totally transparent at DUV or a resist which is very opaque at DUV wavelength is expected to be a solution for OOB problem of EUV lithography.