Abstract Graphene is a promising material for next‐generation extreme ultraviolet (EUV) pellicles due to its excellent optical transparency, mechanical, and thermal stability under intense EUV radiation. However, challenges remain in precisely controlling its thickness at large scales and preventing hydrogen radical‐induced degradation. In this study, a multilayer graphene composite with protective capping layers, enabling nanometer‐scale thickness control is devloped. A 10‐layer, 5 nm thick graphene film achieves ≈92% transparency and an effective Young's modulus of 220 GPa. When integrated into a free‐standing molybdenum (Mo)/graphene/silicon nitride (SiN) composite, the Young's modulus increases by 29%, and the fracture load improves by 840% compared to a single‐layer SiN membrane. Molecular dynamics simulations confirm that the enhanced mechanical strength mainly results from graphene's intrinsic properties. Additionally, a full‐size pellicle with five graphene layers and a 100 nm SiN layer are fabricated, which maintains over 90% EUV transparency on a 7 nm SiN substrate. These results suggest that multilayer graphene membranes can overcome current EUV pellicle limitations and support the broader commercialization of EUV lithography in the near future.

Abstract Extreme ultraviolet lithography requires resist materials capable of patterning with low roughness and minimal stochastic defects. The dissolution behavior of resist polymers significantly affects pattern fidelity; however, the effects of the polymer composition and developer properties on the dissolution behavior have not yet been fully elucidated. In this study, we investigated the dissolution kinetics of poly[4-hydroxystyrene-co-(methyl methacrylate)-co-(methacrylic acid)] films using aqueous tetraalkylammonium hydroxide (TAAH) with varying alkyl chain lengths and concentrations. We used a quartz-crystal microbalance to monitor dissolution dynamics. The results indicated that a high ratio of nonpolar units hindered developer penetration, thereby slowing dissolution and, in some cases, forming thick transient swelling layers. In contrast, polymers containing more dissociable units exhibited less dependence on the molecular size and concentration of the alkali ions and dissolved without significant swelling. The dissolution mode was changed by increasing the number of nonpolar polymer units and extending the TAAH alkyl chains.

Advancing next‐generation EUV photoresists requires overcoming the intrinsic trade‐offs among sensitivity, resolution, and line‐edge roughness. Here, we develop a series of halogenated metal‐oxo cluster photoresists that effectively modulate this resolution–line edge roughness–sensitivity balance. Using EUV lithography, these materials achieve sub‐15 nm critical dimensions with line‐edge roughness below 1 nm. More details are discussed in the article by Li et al . on pages 25—32. image

Angstrom-scale semiconductor scaling enabled by extreme ultraviolet (EUV) lithography is critical for advancing the energy efficiency and performance of current and future microelectronics. In this talk, I will present our recent progress on the vapor-phase synthesis of novel organic–inorganic hybrid EUV resists using atomic layer deposition (ALD) techniques—specifically, vapor-phase infiltration (VPI) and molecular ALD (MALD)—and discuss their electron beam and EUV patterning characteristics. VPI involves infiltrating gaseous inorganic precursors into existing organic resists, whereas MALD uses cyclic deposition of organic and inorganic moieties. Key findings from our work include: (1) the critical role of compatibility between infiltrated inorganic species and resist developers in VPI-derived resists, and (2) the correlation between 100 eV electron beam sensitivity and EUV sensitivity in MALD resists. If time permits, I will also provide a brief overview and update on the DOE Accelerate Initiative project titled “Angstrom Era Semiconductor Patterning Material Development Accelerator”, which aims to accelerate the development of next-generation EUV photoresists through ALD-derived resist synthesis and the correlation of EUV patterning performance with cost-effective laboratory proxy characterizations.

Hybrid molecular layer deposition (MLD), the vapor-phase layer-by-layer process for depositing organic-inorganic films with subnanometer thickness and compositional control, has seen growing interest for use in the creation of photoresists for extreme ultraviolet (EUV) photolithography. MLD is well-suited for this purpose, as the wide variety of available reactants allows for the creation of thin films with tunable EUV absorptivity, air stability, etch resistance, and mechanical stability. However, while recent work to create patternable films primarily explored the impact of changing the inorganic element, such as Al and Sn, on film properties, the influence of the organic reactant on the final photoresist properties remains largely underexplored.Using our previously published high-throughput multi-chamber MLD system, we investigated the stability and mechanical properties of organic-inorganic hybrid thin films designed for EUV lithography applications. Eighteen different film chemistries were synthesized using combinations of three organometallic precursors—diethyl zinc, trimethylaluminum, and tin(IV) t-butoxide—and six organic precursors. These films were evaluated for stability in air, developer compatibility, and etchant resistance, both before and after UV exposure, while film transformations were monitored using Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Selected materials demonstrating high performance with UV exposure also underwent patterning tests using an electron beam source, with results visualized via Scanning Electron Microscopy. Our findings reveal that specific combinations of organic and inorganic components yield films with significantly improved mechanical properties, stability in air, and patternability. This research provides insight into desirable properties of organic precursors needed to create superior EUV photoresists using MLD.

This work demonstrates a fluorine‐based molecular modification strategy to achieve dual‐tone photoresist behavior from antimony oxo clusters. Fluorinated ligands enable high‐sensitivity positive‐tone patterning, while non‐fluorinated counterparts result in conventional negative‐tone patterning. The approach provides an effective method to manipulate photoresist polarity and sensitivity at the molecular level for advanced EUV lithography. More details are discussed in the article by Qi et al . on pages 3365–3372. image

The evolution of photoresists has been accelerated by escalating demands for pattern fidelity, particularly with the breakthrough of extreme ultraviolet (EUV) lithography in achieving sub-20 nm resolution. Herein, we report two kinds of partially alkyl-substituted silsesquioxane (PASS) resists to overcome the dual challenges of hydrogen silsesquioxane (HSQ) in EUV applications: inherent instability and unsatisfactory sensitivity. Through strategic integration with a photoacid generator (PAG), the optimized formulation demonstrates exceptional lithographic performance, achieving 14 nm resolution (line edge roughness of 1.3 nm) with a sensitivity of 4.3 μC/cm2 and a contrast of 5.1 under electron beam lithography. Besides, the PASS resist exhibits a 360-day gelation period and a 160-fold improvement over conventional HSQ. Systematic investigations combining micro-Raman spectroscopy and model compound studies reveal that PAG enhances both sensitivity and shelf stability through dual mechanisms: (1) a photoacid-catalyzed cross-linking reaction between siloxanes and (2) nucleophilic attack inhibition at silicon centers. These advances, coupled with successful electron-beam and ultraviolet patterning demonstrations and structural tunability, establish PASS resists as viable candidates for EUV lithography in semiconductor nanofabrication.

Molecular Functionality Switching of Isomorphic Organoantimony Complexes between High-Sensitivity Radical Initiator and Quencher for Reliable Extreme Ultraviolet Lithography

Extreme ultraviolet (EUV) lithography faces critical challenges in aberration control and patterning fidelity as technology nodes shrink below 3 nm. This work demonstrates how Source–Mask Optimization (SMO) simultaneously addresses both illumination and mask design to enhance pattern transfer accuracy and mitigate aberrations. Through a comprehensive optimization framework incorporating key process metrics, including critical dimension (CD), exposure latitude (EL), and mask error factor (MEF), we achieve significant improvements in imaging quality and process window for 40 nm minimum pitch patterns, representative of 2 nm node back-end-of-line (BEOL) requirements. Our analysis reveals that intelligent SMO implementation not only enables robust patterning solutions but also compensates for inherent EUV aberrations by balancing source characteristics with mask modifications. On average, our results show a 4.02% reduction in CD uniformity variation, concurrent with a 1.48% improvement in exposure latitude and a 5.45% reduction in MEF. The proposed methodology provides actionable insights for aberration-aware SMO strategies, offering a pathway to maintain lithographic performance as feature sizes continue to scale. These results underscore SMO’s indispensable role in advancing EUV lithography capabilities for next-generation semiconductor manufacturing.

Comprehensive SummaryThe relentless drive toward miniaturization in the semiconductor industry demands photoresists capable of patterning sub‐20 nm features for next‐generation extreme ultraviolet (EUV) lithography. Metal‐oxo clusters, with sub‐5 nm molecular dimensions, structural tunability, and high EUV absorption via metal centers, have emerged as promising EUV photoresist candidates. Advancing next‐generation photoresist materials necessitates resolving the inherent trade‐offs between sensitivity, resolution, and line‐edge roughness. In this work, we report a series of halogenated metal‐organic clusters based EUVL photoresists, aiming to modulate the sensitivity, resolution, and line‐edge roughness. Here, we report the synthesis of halogenated metal‐organic clusters as EUVL photoresists, designed to modulate the resolution‐line edge roughness‐sensitivity trade‐off. Sub‐20 nm critical dimensions and line edge roughness below 2 nm were achieved with the clusters by EUVL. The results demonstrated that halogen elements influenced the sensitivity of the clusters. To unravel the EUV‐driven reaction pathways, we analyzed the chemical transformations in these clusters after exposure using X‐ray photoelectron spectroscopy and Fourier‐transform infrared spectroscopy. These findings pave the way for the rational design of high‐performance EUV photoresists.

High-precision wafer alignment is a key technology for achieving high overlay accuracy in advanced-node semiconductor manufacturing. In immersion, extreme ultraviolet (EUV), and high-NA EUV lithography, asymmetry in alignment mark structures, introduced by processes, such as chemical–mechanical polishing, is a primary cause of alignment position deviation (APD), which significantly degrades overlay accuracy. To address this issue at its root, this paper presents a systematic design methodology for segmented grating alignment marks based on multi-objective optimization. The mark geometry is parameterized and coupled with finite-difference time-domain simulations. A non-dominated sorting genetic algorithm (NSGA-II) is employed to simultaneously maximize diffraction efficiency and minimize APD under asymmetric deformation. Optimization results for two design examples confirm the effectiveness and feasibility of the proposed approach.

The tin-oxo cage is a promising photoresist due to tin's large extreme ultraviolet (EUV) photon cross-section and small size. CO2 and H2O play a crucial role in increasing the solubility contrast of tin-oxo cages in deep ultraviolet (DUV) and EUV lithography. However, the internal reaction mechanisms remain largely unknown. This work systematically investigated the cleavage of carbon-tin bonds in tin-oxo cages by density functional theory (DFT) upon diverse irradiation (DUV and EUV). Subsequently, the interactions of the resulting intermediates with CO2/H2O (or their hybrid) were examined, revealing that hydroxyl compounds (from the dissociation of H2O) serve as pivotal precursors to trigger new cross-linking reactions (forming Sn-O-Sn and Sn-OCO-Sn products) and enhance the solubility switch. These theoretical results provide insight into the atomic-scale mechanisms of small molecules improving photoresist properties, offering new perspectives for the design and optimization of novel photoresist materials.

Toward practical application of sub-resolution grating for improved process window control in high and hyper NA EUV lithography

We report the design, cryogenic optimization, and performance modeling of a compact quasi-optical ring resonator intended to compress microwaves pulses at 170 and 250 GHz to the megawatt level. By combining ultra-low-loss CVD diamond and gold-doped silicon wafers with high-RRR copper mirrors, the calculated unloaded quality factor exceeds 4.3×105 at 20 K and yields simulated gains up to G=4.1×103. Coupling the resonator with a laser-driven semiconductor switch described by an extended Vogel model shows that 1 MW, nanosecond pulses can be generated from only 445 W of microwave drive power while dissipating 272 W into the cryostat. A practical cooling architecture using two Gifford–McMahon stages (20 and 80 K) is proposed, demonstrating that high-repetition-rate (10–20 kHz) operation is feasible with commercially available cryocoolers. The results outline a clear path toward cost-effective, table-top sources for extreme-ultraviolet lithography, dynamic nuclear polarization, and fusion systems.

The EUV light emitted by the synchrotron radiation source exhibits a stable wavelength and pollution-free characteristics, making it highly suitable for technical verification in diverse EUV lithography applications and playing a pivotal role in EUV lithography industry research. To guide the EUV light from the beamline into the experimental platform, this paper proposes a deflection system design based on the Shanghai Synchrotron Radiation Facility (SSRF). This system enables beamline diagnostics for EUV light while facilitating precise positioning and performance testing of the Mo/Si multilayer planar deflection mirror. The deflection system achieves accurate installation and alignment through a coordinate transfer protocol. By imaging the EUV incident light spot on a scintillator and analyzing variations in EUV light intensity data before and after the deflection mirror, the system can accurately measure focused light spot parameters from the beamline and achieve submicron alignment accuracy with 10 μrad angular resolution for the deflection mirror. The proposed design provides valuable insights for advancing EUV lithography technology utilizing synchrotron radiation sources.

One of the main barriers to continued device scaling in the era of extreme ultraviolet (EUV) lithography is the need for improved photoresist chemistries to address challenges such as poor EUV sensitivity, inadequate etch resistance, and pattern collapse. Metal-organic photoresists are a promising class of materials that can address many of these challenges, and among them, resists deposited via hybrid molecular layer deposition (MLD) have attracted interest for their unique advantages in thickness control, chemical homogeneity, and compatibility with vacuum processing. However, despite many successful demonstrations of patterning, little is known about how the molecular design of hybrid MLD resists affects their lithographic performance. In this work, we study the effect of the network structure, a common feature among all hybrid MLD resists, via a series of aluminum alkoxide ("alucone") negative tone resists with varying networking density. Their patterning mechanism is investigated via electron beam lithography (EBL)─a common proxy for EUV─and compared to their EUV-induced reactions studied via flood exposure and in situ characterization. We show that the resist with the least networking density demonstrates the best sensitivity and resolution, with the ability to resolve dense line/space gratings as small as 14 nm half pitch via EBL.

Lithography remains a cornerstone of modern micro- and nanoelectronics, defining the limits of miniaturization, production efficiency, and the overall competitiveness of semiconductor technologies. As semiconductor manufacturing becomes increasingly dependent on a small number of global suppliers, understanding patent activity in lithographic equipment is of strategic importance. This study provides a comprehensive patent landscape analysis of lithographic technologies and equipment over the past two decades (2004–2024). The analysis was conducted using international patent databases (PatSearch, Espacenet, Orbit Questel) and covered core IPC classes related to optical, electron-beam, X-ray, nanoimprint, and maskless lithography. Both Russian and international patents were examined to assess global trends and national contributions. The results highlight a strong concentration of patents in leading countries such as China, the United States, Japan, South Korea, and Taiwan, with corporate leaders including ASML, Carl Zeiss SMT, TSMC, Samsung, Canon, and Nikon shaping the global market. The study shows that while China demonstrates rapid growth driven by national strategies of technological independence, European countries like the Netherlands and Germany maintain a strategic role due to the presence of unique corporate champions such as ASML and Carl Zeiss SMT. For Russia, the findings emphasize the importance of developing indigenous capabilities in lithographic equipment. Current initiatives aimed at 350–130 nm nodes, along with research in advanced fields such as EUV, X-ray, and nanoimprint lithography, provide a foundation for reducing dependence on imports and building long-term technological sovereignty.

Nonionic photoacid generators (PAGs) have emerged as key components in advanced extreme ultraviolet (EUV) and electron beam (EB) photoresists, offering advantages such as low dark loss, reduced outgassing, and suppressed phase separation. However, the lack of molecular-level understanding of their acid generation mechanisms hinders rational design and leads to reliance on trial-and-error synthesis. In this study, we perform a comprehensive density functional theory (DFT) investigation on 22 representative nonionic PAGs to elucidate their postexposure reaction pathways, encompassing bond dissociation, byproduct formation, and proton transfer mechanisms. Our findings reveal four distinct electron-triggered dissociation modes, including productive N-O/C-O bond cleavage and competing, nonproductive S-O bond cleavage. We identify the relative energy barrier between productive and unproductive pathways as a critical descriptor for photoacid generation efficiency and, by extension, photoresist sensitivity. Moreover, we demonstrate that molecular conformation (bent vs extended) and electron-withdrawing or electron-donating substituents profoundly impact the selectivity of bond dissociation. Importantly, this study also clarifies the roles of various proton sources (phenolic -OH+, t-BOC+ protecting groups, and intermediates during byproduct formation) in facilitating acid formation. Our analysis quantifies the energy barriers associated with each route, highlighting structure-dependent modulation of acid generation efficiency. These insights collectively establish a structure-mechanism-function relationship for nonionic PAGs and offer a predictive framework for designing next-generation high-sensitivity PAGs tailored for advanced lithographic applications.

Extreme ultraviolet (EUV) lithography has revolutionized the high-volume manufacturing of nanoscale components. The use of EUV light leads to ionization-driven chemistry in the imaging materials of lithography, the photoresists. The complex interplay of ionization, generation of primary/secondary electrons, and the subsequent chemical mechanisms that lead to image formation in photoresists has been notoriously difficult to study. This is in particular true for the radiochemical transformations occurring during exposure. In this work, we deploy table-top EUV photoemission spectroscopy to observe in situ chemical changes occurring during exposure in a model chemically amplified photoresist and discover a surprising chemical reaction pathway, the EUV-induced breakdown of a perfluoroalkyl substance (PFAS) photoacid generator (PAG). This previously unobserved breakdown of the PFAS PAG, a critical component in the EUV exposure mechanism, manifests as changes in the intensity of the valence band peaks of the EUV photoemission spectrum, which are linked to degradation of the PFAS PAG via an advanced atomistic simulation framework. Our combined experimental and theoretical approach shows that EUV photoemission can simultaneously resolve chemical dynamics and the production of primary and secondary electrons, giving unique insights into the radiochemical transformation of photoresist materials. More generally, our approach also shows that EUV photoemission spectroscopy can provide a unique platform for tracking degradation pathways of PFAS molecules in thin films, owing to the high ionization cross section of fluorine at EUV wavelengths. Our results pave the way for utilizing accessible, table-top EUV spectroscopy systems for observing EUV photoresist chemical dynamics, with the potential for time-resolved measurements of photoemission processes in the future.

This paper provides a comprehensive review of recent advances in lithography technologies, focusing on Deep Ultraviolet (DUV), Extreme Ultraviolet (EUV), and Nanoimprint Lithography (NIL). This work synthesizes findings from existing studies to highlight the fundamental principles, performance characteristics, and practical challenges of each method. The comparison centers on key metrics, including resolution, depth of focus, exposure dose, line-edge roughness, overlay accuracy, and throughput, revealing how different approaches balance these competing factors. DUV lithography offers process maturity and cost efficiency but relies on multiple patterning to extend scaling. EUV provides higher intrinsic resolution, though it is constrained by source power, resist sensitivity, and stochastic variation. NIL demonstrates excellent resolution potential and process simplicity, yet defect control and alignment remain critical barriers for large-scale deployment. By consolidating insights across optical, material, and metrology domains, this review clarifies the trade-offs that shape manufacturability and points to opportunities for hybrid solutions, material innovation, and sustainable process design. The analysis concludes with perspectives on how coordinated progress in optics, resists, and alignment strategies can enable continued semiconductor scaling.