Pattern collapse due to the strong capillary forces of water continues to constrain the process margins for EUV CAR patterning at small feature sizes. While PFAS-containing rinse formulations are widely recognized for its role in collapse mitigation during the development process, there is a growing demand for a PFAS-free solution as regulations become more stringent. In this study, a novel PFAS-free rinse formulation was found to have comparable lithographic performance to a conventional PFAS rinse formulation, effectively maintaining significant collapse mitigation performance at the 14 nm half-pitch.

ASML started a program to select the “Next Generation Lithography” in 1997 with active participation on Electron Beam Projection Lithography, Ion Beam Projection Lithography as well as Extreme Ultraviolet (EUV) Lithography. These technologies have been explored by various consortia worldwide, EUV Lithography since the mid 80’s. The extendibility to smaller nodes was a decisive advantage for EUV and by 2001 ASML decided to focus on EUV. By 2006 ASML shipped the first two full field scanners, with a Numerical Aperture (NA) equal to 0.25 EUV Alpha-demo tools. These tools have been instrumental to boost the learning on mask and resist, yet significant innovations in e.g. source power were needed before EUV could enter into High Volume Manufacturing (HVM). Today EUV NA=0.33 is being used in HVM of logic as well as DRAM IC makers and the first NA=0.55 scanners have been shipped. ASML and Zeiss are currently exploring next steps in our EUV roadmap, including a “hyper-NA” system with a NA>0.7. Such a scanner could extend the single patterning capabilities down to 5 nm lines & spaces (L/S). Further improvements on the resist are key to utilize current and future EUV scanners to their full potential.

Polylactic acid (PLA), a biodegradable material derived from renewable sources, has been challenging to fabricate through injection molding, owing to its narrow crystallization range and poor heat resistance. Conventional injection molding also encounters difficulties with gas venting in the cavity, which impedes microscale processing. This study successfully performed micro-injection molding of standard PLA under typical conditions. Using an amine-containing gas-permeable hybrid molds, PLA microstructures measuring 1.2 μm in height and 2.7 μm in base diameter were successfully molded, demonstrating high moldability. This study established the viability of micro-injection molding for PLA and may provide an important foundation for the future development of micro-surface fabricated devices made of PLA in the biomedical field, such as blood coagulation prevention medical devices based on microfabrication technology.

In this paper, we improved both the sensitivity and resolution of photosensitive polyimide (PSPI) by using the highly acidic dissolution inhibitor (DI) in three-component chemically amplified PSPI. The PSPI consists of a polyimide, DI, and a photoacid generator. The DIs were phenol type dissolution inhibitors (tBoc-DI) and carboxylic acid type dissolution inhibitors (tBu-DI). PSPIs containing tBu-DI were more sensitive than those containing tBoc-DI. In all PSPIs, 3 μm line-and-space (L/S) patterns were successfully produced at the initial film thickness of ca. 3.5 µm. The pattern shape of PSPIs containing tBu-DI were closer to a rectangle and higher resolution than that of PSPIs containing tBoc-DI. These results were attributed to the fact that tBu-DI exhibited higher dissolution acceleration in the exposed area than tBoc-DI. These results reveal that tBu-DI resolves the trade-off between the sensitivity and resolution of the PSPI.

Organic solar cells (OSCs) have been anticipated as a promising renewable energy source. In particular, green-light wavelength-selective (GLWS) OSCs have the potential to convert green light into electricity while allowing blue and red light to support crop growth, making them suitable for greenhouse integration. To realize GLWS OSCs, P3HT has been selected as a suitable GLWS donor. However, compatible GLWS nonfullerene acceptors (NFAs) compatible for P3HT remain limited. Here, we designed and synthesized new fused-ring NFAs, TPBTz-RD and i-TPBTz-RD, incorporating a benzothiadiazole (BTz) unit into their conjugated systems. These NFAs exhibited sharp absorption bands in the green-light wavelength region due to their rigid fused-ring skeletons. Inverted OSCs fabricated with P3HT and TPBTz-RD as the active layer showed a moderate power conversion efficiency (PCE) of 2.12%. The GLWS factor (S_G) and the PCEs in the green-light region (PCE-GR) of the OSCs were determined to be 0.85 and 3.5%, respectively. The P3HT:TPBTz-RD blend film showed enhanced photosynthetic rates in strawberry leaves compared to those under a referential P3HT:SNTz-RD blend film. These results suggest that the fine-tuning of absorption band is important to develop GLWS OSCs for agrivoltaics.

Polymeric microneedles have attracted attention as a minimally invasive medical device. To reduce pain during insertion, the needles should be as thin and small as possible. However, the relatively low mechanical strength of polymer materials imposes limitations on the needle shape. To establish the design principles for polymer microneedle geometries, we conducted elastoplastic analysis using the finite element method. Young's modulus, isotropic tangent modulus, and yield stress were obtained by bilinear fitting of the stress-strain curve. Prescribed displacements were applied to three-dimensional solid model of microneedles with varying tip diameters (45, 80, 110 μm) to achieve total reaction forces of 100, 200, and 300 mN at the tip surface, and the deformation and von Mises stress distributions were calculated. In the simulation, elastic deformation was calculated using Young's modulus in areas where the von Mises stress was below the yield stress, whereas plastic deformation was calculated using the isotropic tangent modulus in areas where the stress exceeded the yield stress. Microneedles with tip diameters of 45 μm and 80 μm undergo plastic deformation under a total reaction force of 200 mN or greater, whereas microneedles with a tip diameter of 110 μm deform only elastically, even at 300 mN. Because the simulation results align with the findings from previous insertion and compression tests, the simulation model developed in this study is expected to effectively predict the deformation during insertion in the design of microneedles.

Antifouling properties of the superhydrophilic structure on the surface of a snail shell and the superhydrophobicity of the double roughness structure on the surface of a lotus leaf are well-known examples of biomimetics. For our earlier studies, we replicated a snail shell surface microstructure by irradiating polymer films, fabricated via the solvent casting method, using atmospheric pressure low-temperature plasma (APLTP). For industrial application of biomimetics, establishing techniques for forming microstructures on resin plates is desirable. For this study, we investigated the morphology of microstructures formed on commercially available poly(methyl methacrylate) (PMMA) plates by irradiating them with APLTP under different oxygen addition conditions. Results demonstrated that a coarse spike-like microstructure was formed under low oxygen addition conditions. These findings suggest that control of reactive species in the plasma is crucially important for producing desired microstructural characteristics.

Nanoimprint lithography, a technique within microfabrication, continues to progress due to its ability to pattern large areas with high resolution, efficiency, and cost-effectiveness. Among its variants, UV nanoimprint lithography offers rapid curing through UV light and exceeds thermal nanoimprint lithography in terms of the throughput. However, UV nanoimprint lithography often traps air during the imprinting process and molds made from non-gas-permeable materials such as quartz and metal can result in molding defects. In this study, a new TiO₂-SiO₂ radical-based gas-permeable mold surface material was developed using the sol-gel method to enhance ultraviolet-based nanoimprint lithography for precise processing. Compared to existing material, this surface material exhibited superior performance in terms of both gas permeability and mechanical properties, with oxygen gas permeability 1.2 times higher, carbon dioxide gas permeability 1.3 times higher, and flexural strength 1.1 times higher than those of existing material. Based on these performance enhancements, the microfabrication demonstrated superior transfer accuracy compared to master molds with specifications of (a) pitch: 20 μm, height: 17.1 μm, bottom diameter: 7.14 μm, and (b) pitch: 50 μm, height: 17.0 μm, bottom diameter: 7.14 μm, achieving (a) height 99.9%, bottom diameter 99.0%, and (b) height 99.8%, bottom diameter 94.1%.  Additionally, these gas-permeable molds facilitated high-precision fine processing on the surface of lactic acid-glycolic acid copolymers, reaching (a) bottom diameter of 95.3% and (b) 93.7%, respectively. The findings from this study will advance precision processing technology, improve the accuracy of fine processing in machine tools, and enhance production efficiency. This is particularly anticipated to aid the development of advanced production systems in sectors such as medical devices, semiconductor manufacturing, optical components, and microfluidic devices, thereby promoting future industrial growth.