Nonchemically amplified resists based on triphenyl sulfonium triflate-modified polystyrene (PSTS) were prepared by a facile method of modification of polystyrene with sulfonium groups. The uploading of the sulfonium group can be well-controlled by changing the feed ratio of raw materials, resulting in PSTS0.5 and PSTS0.7 resists with sulfonium ratios of 50 and 70%, respectively. The optimum developer (methyl isobutyl ketone/ethanol = 1:7) is obtained by analyzing contrast curves of electron beam lithography (EBL). PSTS0.7 exhibits a better resolution (18 nm half-pitch (HP)) than the PSTS0.5 resist (20 nm HP) at the same developing conditions for EBL. This novel resist platform was further evaluated by extreme ultraviolet lithography, and patterning performance down to 13 nm HP at a dose of 186 mJ cm–2 with a line edge roughness of 2.8 nm was achieved. Our detailed study of the reaction and patterning mechanism suggests that the decomposition of the polar triflate and triphenyl sulfonium groups into nonpolar sulfide or polystyrene plays an important role in the solubility switch.

The development of EUV resists is one of the major challenges for the deployment of high-NA EUV lithography , which is on the roadmap for high-volume manufacturing of future semiconductor technology nodes. Resist performance is admittedly governed by a resolution-roughness-sensitivity (RLS) tradeoff. This study reports on the EUV resist progress achieved during the last year in the framework of the resist screening program by PSI and ASM L. An extensive performance characterization of different resists was carried out using the XIL-II beamline EUV interference lithography (EUV-IL) tool at the Swiss Light Source (SLS). We present the upgraded screening metrology used in 2020 at PSI enabling increased confidence in results. We report material performance towards patterning lines/spaces features with respect to the key parameters of RLS: half-pitch (HP), dose-to-size (DtS), line-width-roughness (LWR), as well as Z-factor for overall performance consideration. General progress in EUV resist development is reviewed by considering several resist platforms available today from different vendors. Different molecular and chemically amplified resist materials are demonstrated as viable for 16 nm resolution technology nodes. One chemically-amplified resist vendor shows suitable materials for 13-nm-resolution technologies while exhibiting potential for further downscaling. We present different metal-oxide resists screening with resolutions down to 10 nm HP. We finally discuss the overall progress of materials achieved between 2019 and 2020 towards reaching high-NA.

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Background: Non-chemically amplified resist (n-CAR) shows great potential as a unique lithographic material because it avoids some disadvantages of CAR, such as post-exposure instability and acid diffusion. Furthermore, since toxic and flammable developers are widely used in semiconductor manufacturing, the implementation of innovative environmentally friendly waterdevelopable photoresists is of interest.Aim: A unique n-CAR, which could be developed with an environmentally friendly developer, was prepared for electron beam (e-beam) lithography (EBL) and extreme ultraviolet lithography (EUVL).Approach: A polymer containing radiation/photosensitive sulfonium triflate group (PSSF) was synthesized and characterized by infrared, 1 H NMR, and gel permeation chromatography. The lithography performance of the PSSF photoresist was evaluated by EBL and EUVL. The patterns were analyzed with scanning electron microscope and atomic force microscope. Results:The PSSF photoresist can be used in EBL and EUVL. Post-exposure bake had no significant effect on the resolution of photoresist. Development in water should be kept at an appropriate time of 30 s to obtain the repeatable and high-resolution patterns. It shows a similar sensitivity to polymethyl methacrylate but higher contrast. Conclusions:The PSSF acts as n-CAR, and 20 nm line patterns and 35 nm 1:1 line/space patterns were achieved in EBL and EUVL, respectively. It can be developed in pure water with high contrast (γ ¼ 5.49).

A series of t -butyloxycarbonyl ( t -Boc) protected tetraphenylsilane derivatives (TPSi-Boc x , x = 60, 70, 85, 100%) were synthesized and used as resist materials to investigate the effect of t -Boc protecting ratio on advanced lithography. The physical properties such as solubility, film-forming ability, and thermal stability of TPSi-Boc x were examined to assess the suitability for application as candidates for positive-tone molecular glass resist materials. The effects of t -Boc protecting ratio had been studied in detail by electron beam lithography. The results suggest that the TPSi-Boc x resist with different t -Boc protecting ratios exhibit a significant change in contrast, pattern blur, and the density of bridge defect. The TPSi-Boc 70% resist achieves the most excellent patterning capability. The extreme ultraviolet (EUV) lithography performance on TPSi-Boc 70% was evaluated by using the soft X-ray interference lithography. The results demonstrate that the TPSi-Boc 70% resist can achieve excellent patterning capability down to 20 nm isolated lines at 8.7 mJ/cm 2 and 25 nm dense lines at 14.5 mJ/cm 2 . This study will help us to understand the relationship between the t -Boc protecting ratio and the patterning ability and supply useful guidelines for designing molecular resists.