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
Recent advances in EUVL lithography is mainly centered on improving the RLS trade-off by employing new resist
platforms, bulkier PAGs, EUV sensitizers etc. Among the several new kinds of PAGs proposed till date, the focus of
development was mainly on the acid strength, compatibility with resin etc., whilst always retaining the mono, Di or tri
phenyl chromophore of the PAG. Herein we report on the use of chromophore-less PAG for the patterning of EUVL
resists. Resist performance using model acrylate and PHS based resist was studied. The patterned resists were
characterized using SEM. Thermal stability of the PAG was compared with model chromophore containing PAG.
Electrostatic self-assembly (ESA) is combined with optical lithography to develop a novel process to form 70 nm space patterns to overcome the resolution limit of ArF lithography with numerical aperture (NA) of 0.75. It is proven that patterned photo resist are useful template with specific topography to undergo the subsequent ESA. Weak polyelectrolytes are shown to control the attachment amount by adjusting pH. Puddle-assembly is applied instead of spin- or dip-assembly considering pattern profile and practicality to be used in the real FAB environment. With optimized composition and assembly method, it is successful to form 70 nm spaces patterns by ESA-induced chemical attachment above 45 nm, combined with ArF lithography of 0.75 NA. Since it works at room temperature without extra process unit after exposure and development, it overcomes the disadvantages of the conventional chemical shrink processes such as thickness loss, dependence on pattern and photo resist, and throughput lowering. In addition, in-wafer uniformities are comparable to that of forming 120 nm spaces patterns with only ArF lithography, which proves that the combination of ESA and optical lithography can be a potentially and practically alternative way of forming uniform 70 nm spaces patterns over 200 nm substrates. It also means that now it is time for top-down and bottom-up approaches to meet together to access nano world.