Defectivity modulation in EUV resists through advanced filtration technologies

The availability of EUV lithography is the mainstream for resolving critical dimension of the advanced technology nodes, currently in the range of 18nm and below [1]. The first insertion of EUVL into manufacturing utilizes chemically amplified resist (CAR) [2]. The filtration of CAR, both at bulk and point-of-use (POU), has already demonstrated in ArF and ArF immersion lithography to play a significant role for microbridges reduction essentially by removing hard particle and gels [3-6]. With respect to ArFi, EUV is bringing new challenges not only for the achievement of the required line roughness, sensitivity and resolution, but also for the need of a substantial reduction of defects such as line collapse, microbridges and broken lines. In this study, it demonstrated the ability of utilizing novel POU filtration to modulate microbridges and achieving superior start-up behavior, both crucial for enabling EUVL at high volume manufacturing. Different POU filters were tested at the imec EUV cluster comprised of TEL CleanTrack LITHIUS Pro-Z and ASML NXE:3400B. The start-up performance, assessed by measuring defects down to 19nm size as a function of the flushing solvent volume, has shown the fast achievement of attaining a stable baseline. Lithography experiments targeting reduction of on-wafer defectivity, carried out with commercially available photoresists, have consistently shown a substantial reduction of after resist development (ADI) and after resist etch (AEI) microbridges on a 16nm L/S test vehicles. The effect of membrane physical intrinsic designs and novel cleaning of POU devices are discussed.