Extreme Ultraviolet (EUV) Lithography is a candidate for device manufacturing at the 22nm half pitch node and beyond. The key challenge for EUV resists remains to simultaneously meet the requirements for Sensitivity, Resolution and Line-edge-roughness (LER) for Line/Space features (LS), respectively local CD uniformity (LCDU) for Contact holes (CH). The introduction of the ASML NXE:3100 pre-production EUV scanner at Imec, with off-axis illumination provides resolution capability well below 22nm.In this paper we make a assessment of the EUV resist performance for 22nm LS and 28-26nm contacts on the NXE:3100. At 22nm feature sizes, pattern collapse and LER become the main resolution and process windows limiters. The application of FIRM TM Extreme 10 rinse was found to be effective to improve the collapse margin and reduce LER on several resists. Using dipole illumination setting, we achieved 22nm LS at 13.5mJ/cm 2 with 3.1nm (3) LER with wide processing latitudes. Several resists resolved down to 20nm LS. Champion resolution of 19nm LS was obtained in one resist at 20mJ/cm 2 . Using quasar illumination, 28nm HP contact holes were obtained with LCDU value of 1.0nm (1) at <20mJ/cm 2 , showing wide process latitudes. Printing 26nm HP contacts is feasible but requires further improvement in LCDU and contact shape circularity.

Resist ability to simultaneously meet the requirements for Resolution, LER and Sensitivity (RLS) remains one of the critical issues EUV Lithography is facing. As good progress in resolution and sensitivity have been made, nowadays LER and pattern collapse are considered as the two main items requiring improvement. In this paper, the current performance of EUV resist on the ASML ADT is reviewed and the effectiveness of process improvements for pattern collapse and LER reduction has been investigated. Results are presented of EUV resist screening for sub-28nm LS and 30nm contact holes on the ASML ADT to prepare for a resist process on the pre-production tool NXE:3100, currently under installation at imec. Acceptable resist performance was obtained for 28nm LS with some of the new resist materials outperforming the current imec reference resist in terms of LER. By applying a 20% mask bias, imaging of 30nm contacts at <14mJ/cm 2 with wide processing latitudes was achieved. Local variation of contact CD however is a serious limitation at smaller contact sizes. The use of TBAH developer and the application of FIRM rinse were found to be effective to reduce pattern collapse and to extend processing windows. With the FIRM rinse in addition LER was improved. Finally the feasibility of printing 22nm LS at 13mJ/cm 2 with 4.7nm LER have been demonstrated on the NXE:3100 using dipole illumination.

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