Electrostrictive materials and devices have been widely explored for information processing and storage devices. Electrostrictive field-effect transistor (E-FET) is an emerging steep-slope device concept which could allow low-power logic operations. However, E-FET has not been experimentally demonstrated yet, largely due to a gap in fundamental knowledge of constituent materials that meet the device requirements. Here we propose to adopt 2D materials as a backbone of E-FET that consists of a piezoelectric TMD (transition metal dichalcogenide) monolayer interfaced with another TMD channel layer. By performing literature-benchmarked finite-element simulations on various TMD heterostructures, including the flagship material stack of MoS2/PtSe2, we show that the application of a nominal gate voltage to the piezoelectric 2D layer can induce compressive stress as high as 107 N/m2 on the adjacent 2D channel layer. C-AFM (conductive atomic force microscopy) is also carried out to experimentally prove that this stress can cause reversible modulation of conductance for the 2D channel layer (PtSe2). From the phase diagram analysis that simulates both the stress and electric potential distributions inside the piezoelectric 2D layer, the stress is found to be the largest at the interface with the 2D channel layer. A scaling study is also conducted by varying the thickness of both 2D layers to ultimately guide experimental researchers through the design and manufacturing of strain FETs based on 2D materials.
The roughness induced on polymeric surfaces by plasma treatment is highly dependent on both the specific substrate material and the plasma processing parameters. Although the roughness formed on substrates processed typically parallel to the reactor powered electrode exhibits isotropic morphology, anisotropic roughness in the form of periodic nanoripples has been recently demonstrated on perpendicularly oriented substrates (at sample bottom edge). This study delves into the question of how the roughness morphology evolves for substrates that are tilted relative to the powered electrode. Poly(methyl methacrylate) (PMMA) substrates and acrylate-based photoresins, placed at various tilting angles, were subjected to oxygen-plasma treatment, using processing conditions known to create surface micro-nanotexturing. The resulting surface morphology was meticulously characterized via metrological tools and quantified through computational analysis. These findings were then compared to samples treated horizontally under identical plasma processing conditions. Remarkably, tilted surfaces of all studied materials exhibited a discernible trend in surface morphology versus distance from the reactor electrode, across all tilting angles, but prominently at tilting angles >70o. This trend was quantitatively assessed by calculating an anisotropy index, derived from a 2D Fourier analysis of scanning electron microscope (SEM) images. To further elucidate this observed morphology trend, a comprehensive modelling framework was employed. This framework included a reactor scale model and a Monte Carlo model for the calculation of particle trajectories, which predicted the angular and energy distribution functions of ions (IADF & IEDF) reaching the tilted substrates. The results of these simulations revealed a spatial gradient in both ion energy and angular distribution, providing a justification basis for the experimental observations, which clearly demonstrate that plasma processing under substrate inclination induces distinctive morphological modifications (in roughness and its anisotropy), thereby conferring unique characteristics to the treated surfaces. These findings may have significant implications in device fabrication, particularly in the realm of surface engineering.
Circulating tumor cells (CTCs) are important biomarkers for metastatic progression, but their label-free enrichment from blood remains challenging because of their rarity, heterogeneity, and partial size overlap with hematologic cells. In this study, we present a serpentine inertial microfluidic platform for the label-free, outlet-specific enrichment of CTC-sized model cells. Serpentine microchannels with a fixed width of 350 μm, inner radius of 800 μm, and curvature angle of 280° were evaluated using numerical simulations, hemocytometer counting, flow cytometry, and confocal fluorescence imaging. HeLa cells were used as CTC-sized model cells, while Jurkat and K562 cells represented smaller hematologic background populations. The two candidate two-outlet devices were evaluated as complete configurations: a 73 μm-depth device incorporating a 90° terminal outlet branch and a 105 μm-depth device incorporating a 72° terminal outlet branch. Among the tested configurations, the 105 μm/72° device showed the strongest preferential partitioning of outlet-recovered HeLa cells toward the designated collection outlet. At the flowrate of 1000 μL/min, numerical simulations predicted that approximately 92% of the outlet-recovered HeLa cells would be directed to a certain outlet, whereas the corresponding experimental measurements yielded collection-outlet HeLa fractions of 92.0% and 97.5%. At the flowrate of 2000 μL/min, the experimental values showed a greater between-run variability, at 92.5% and 71.1%. Whole-blood experiments with spiked HeLa cells further demonstrated preferential HeLa-associated partitioning toward a certain outlet in a complex biological matrix. Because the channel depth and outlet angle were varied simultaneously, the observed improvement is interpreted as the combined effect of upstream Dean-inertial migration and downstream outlet-stream alignment rather than as an isolated depth effect.
Despite many efforts for developing robust neural implants, existing devices still suffer from short lifespans. The device lifespan is limited by the triggering of the immune response after implantation, leading to structural and functional degradation of the device materials. Among the considered alternatives, Silicon Carbide (SiC) is a particularly attractive material due to its chemical inertness and biocompatibility. Moreover, monolithic SiC-based neural interfaces may be less prone to layer delamination observed in polymer-based implants. Recording neural signals with high spatial resolution requires limiting the electrode dimension at the microscale. However, decreasing the microelectrode dimension impacts the electrochemical impedance and degrades the signal-to-noise ratio. To overcome this restriction, structurization of the electrode surface using nano and microfabrication techniques appears to be a suitable solution allowing to increase the active area without the need of depositing additional active material, thus preserving the monolithic character of the device. In this study, we developed planar multi-electrode arrays fully based on a 4H-SiC stack composed of conductive n-doped and semi-insulating V-doped layer grown by Chemical Vapor Deposition (CVD) on a bulk wafer. To boost the electrochemical performances of the device, the electrode active surface area was nanostructured with a nanopillar array patterned using e-beam and dry etching techniques. Although the effectiveness of the nanofabrication step was partially mitigated by the enhanced roughness of the microelectrode surface, electrochemical measurement demonstrates a positive impact of the nanopatterning of the microelectrode impedance. Our results suggest that nanostructuration is a promising approach for the impedance modulation of small dimension electrodes.
In this work, we present and discuss our recent advances in Electro-HydroDynamic (EHD) field ion emitters operated using Ionic Liquids (ILs), which we develop towards Focused Ion Beam (FIB) applications. Using a non-conventional approach based on high density nanometer-sized tips (MT) grown on a slab planar emitter, a dedicated ion gun setup and three very dissimilar ILs, we demonstrate that stable unipolar ion emission (positive mode, (2 μA, 8 keV) can be achieved. Each ionic liquid (EMIM+,BF4−, EMIM+,DCA− and DEME,BF4−) was successfully operated over 30 min and delivered a total of 3.6 10−3C in a unipolar continuous sequence. We compare, detail and discuss, the evolution of these ILs subjected to such intense, stresses, whilst their structure changes are elucidated using spectroscopic analysis using 1H and 19F NMR. Our experiments demonstrate that severe ILs degradation, universally encountered so far, can be avoided and thus could pave the way to Task-Oriented ILs (TOILs) capable of moving towards innovative applications such as chemical direct patterning by FIB or complex Integrated Circuits (ICs) devices local delayering.
Direct laser writing grayscale lithography (DLW-GSL) is a scalable route for fabricating multi-level micro- and nanostructures, but accurate height control in thick resists remains challenging, especially in the low-dose regime. Here, we present a systematic study of calibration-pattern design for reliable DLW-GSL using a 10 μm-thick resist exposed with a 405 nm laser lithography system. We show that the extracted contrast curves depend strongly not only on processing conditions, including exposure dose and post-exposure development delay, but also on the geometry of the calibration pattern. In particular, box size, box-to-box spacing, and local grayscale-value differences significantly affect the low-gray-value response. This behaviour is attributed to a long-range background illumination, or flare-like proximity effect, which produces local dose enhancement and leads to discrepancies between calibration patterns and actual grayscale device exposures. By introducing auxiliary dummy boxes and constructing an optimized composite contrast curve, we reduce these discrepancies across both low- and high-depth regions. The optimized process enables reproducible fabrication of grayscale master molds for nanofluidic applications with depths ranging from below 500 nm to 6 μm minimizing deviations from the designed structures. This work provides a practical calibration strategy for improving nanoscale vertical accuracy in thick grayscale resist films and supports broader application of DLW-GSL in microfluidics, micro-optics, and MEMS fabrication.
A 3D-patterned back-electrode architecture is developed to enhance the optoelectronic performance and mechanical durability of flexible perovskite solar cells. Truncated pyramidal microstructures are fabricated on flexible substrates via a previously developed single-step greyscale lithography process, followed by vacuum thermal evaporation of an aluminum electrode and conformal spray-coating of the subsequent layers. This approach addresses the inherent performance-durability trade-off in flexible electronics - by using structures with a truncated geometry, localized stress concentrations are mitigated while back-reflection into the absorber layer is maximized. The optimized 3D architecture achieves a power conversion efficiency of 20.3% and a fill factor of 70%, significantly exceeding the values of planar devices - 16.6% and 61%, respectively. These improvements are primarily driven by enhanced charge collection kinetics and reduced interfacial charge-transfer resistance, complemented by optical back-reflection benefits. Furthermore, the patterned electrode demonstrates an 85-fold improvement in electromechanical stability, maintaining a sheet resistance of 52 Ω/sq. after 10,000 bending cycles, whereas the planar electrode exhibits failure exceeding 4.5 kΩ/sq. The synergistic integration of greyscale lithography with truncated geometries provides a scalable microfabrication route to resolve the conflict between optical trapping and mechanical resilience, positioning 3D texturing as a critical advancement for next-generation flexible photovoltaics.
Understanding ion electrosorption under strong electric fields is essential for advancing electrochemical desalination technologies and high-performance energy storage devices. In this work, we apply a symmetric modified Stern–Poisson–Boltzmann framework that incorporates steric constraints arising from the finite size of ions in aqueous electrolytes confined within an electrified channel. Unlike classical Gouy–Chapman theory, the proposed model accounts for excluded-volume effects, enabling the analysis of concentrated solutions and high surface potentials. We employ analytical expressions for the electric potential distribution, surface charge density, differential capacitance, and diffuse layer thickness for monovalent and divalent electrolytes at the equilibrium state that are solved numerically at the equilibrium state. Increasing electrode potential enhances surface charge density by orders of magnitude, while higher ionic valence significantly compresses the diffuse layer at low potentials but introduces repulsive crowding at strong polarization. The model further predicts that ion-removal efficiency in the channel center depends critically on electrode spacing, bulk concentration, and applied potential, with removal rates exceeding 90% under optimized conditions. These findings provide theoretical insight into steric-limited electrokinetic processes and offer design guidelines for electrochemical water purification and electrostatic energy-storage systems.
This study reports the valorisation of almond shells waste as a sustainable feedstock for the development of a cellulose-based electrochemical sensor for tetracycline detection. Cellulose from almond shells was functionalized with zinc oxide nanoparticles (ZnO) and multiwalled carbon nanotubes (MWCNTs), to form an hybrid AS-ZnO@MWCNTs Composite with enhanced physicochemical and electrochemical properties. The resulting material was characterized by scanning electron microscopy coupled with energy -dispersive X-ray spectroscopy (SEM-EDX), and Fourier-transform infrared spectroscopy (FT-IR) confirming the successful integration of ZnO and MWCNTs within the cellulose matrix. The improved electrochemical performance arises from the complementary contributions of the composite components: ZnO-containing domains provide electroactive sites for tetracycline oxidation, MWCNTs establish conductive pathways that improve electron-transfer kinetics, and the cellulose matrix supports their structural and interfacial integration. The AS-ZnO@MWCNTs/SPCE sensor exhibited excellent analytical performance toward tetracycline detection with a high sensitivity of 24.8 μA·μM−1·cm−2 and a low detection limit of 0.16 μM based on the second oxidation peak (A2). The sensor also demonstrated good selectivity in the presence of potential interfering species, as well as satisfactory repeatability, stability and reproducibility. The proposed platform was successfully applied to the detection of tetracycline in real samples, including milk and honey, showing reliable recovery values. The findings highlight the potential of cellulose recovered from agro-industrial waste as a renewable functional matrix for the development of electrochemical sensing platforms for food-safety monitoring.
Two-photon polymerization enables the fabrication of complex 3D microstructures at sub-micrometer resolution, making it a powerful platform for cell culture scaffold fabrication. However, voxel-induced anisotropy and proximity effects often result in geometric distortions that introduce unintended structural directionality, limiting the ability to decouple scaffold geometry from fabrication artifacts in cell behavior studies. In this work, we characterized these phenomena and developed practical design strategies, including elliptical cylindrical shell geometries with uniform line spacing, optimized writing path strategies, and depth-dependent power compensation, to fabricate isometric 3D cage scaffolds with controlled beam width. SEM characterization confirmed aspect ratios close to unity across all beam sizes and orientations, indicating that the adopted strategies were effective in achieving the targeted isometric geometries. NIH 3 T3 fibroblasts cultured within these scaffolds exhibited a progressive increase in nuclear volume with beam width, plateauing between 7 and 10 μm, consistent with differences in available adhesive contact area. This work provides a practical methodology for fabricating isometric scaffolds using two-photon polymerization and establishes beam width as a controllable geometric parameter for investigating geometry-dependent cell responses in 3D culture models.
Metasurfaces with dumbbell shape have been rarely addressed so far and its polarization behavior is still unknown. This paper reports the fabrication of a dumbbell-shaped nano-cavity array as a 2D metasurface with an Al/dielectric/Al (MIM) configuration by electron-beam lithography, plasma etching, and self-aligned Al metallization. Monte Carlo simulation was applied to guide the lithography process in eliminating proximity effect for forming dumbbell shape, enabling reliable control by processing parameters. Both finite-difference time-domain (FDTD) simulation and experimental characterizations were carried out to investigate the optical polarization behavior across the visible and near-infrared wavelengths of the 2D metasurface with dumbbell shaped cells. Clear polarization sensitivity was observed, demonstrating the structural effect of the unit cell shape on the polarization property from ellipse to dumbbell. Further optimization work is still needed to enhance the polarization performance of such a 2D metasurface.
Sulfamethoxazole is a widely used sulfonamide antibiotic, but its overdose can cause serious side effects, underscoring the need for sensitive and selective detection methods. In this work, we introduce a selective and novel electrochemical sensor based on a bimetallic CeBi-metal organic framework integrated with carbon nanotubes and Ketjen black nanocomposite for the efficient determination of sulfamethoxazole. The CeBi- metal organic framework was synthesized via a facile hydrothermal method, and the resulting nanocomposite was fabricated through an ultrasonic-assisted strategy to form an interconnected conductive network. Benefiting from the synergistic effects of the bimetallic metal organic framework (high surface area and abundant active sites) and the ketjen black and carbon nanotubes matrix (superior electrical conductivity and electron-transfer capability), the proposed sensor exhibits outstanding analytical performance. It offers a wide linear response range from 0.5 to 3000 nM, with an exceptionally low detection limit of 0.042 nM. Moreover, the sensor demonstrates excellent reproducibility, stability, repeatability, and selectivity. Practical applicability was successfully validated by detecting sulfamethoxazole in the blood serum samples with satisfactory recoveries (97–104%). This work presents, for the first time, the use of a CeBi-metal organic framework and ketjen black/carbon nanotubes nanocomposite as an electrochemical platform for sulfamethoxazole detection, providing a simple, cost-effective, and highly selective alternative to conventional techniques. The developed sensor holds great promise for pharmaceutical and clinical monitoring applications.
Plasmonics, the study of collective oscillations of electrons at metal-dielectric interfaces, has become an emerging and fast-growing field that enables manipulation of electromagnetic waves at sub-wavelength scales. The ability to precisely design and control plasmonic modes is credited to developments in material engineering, precision fabrication, and computational modelling, which have redefined technologies for energy harvesting, medicine, communication, and defences. This review covers different plasmonic materials, including noble metals, semiconductors, graphene-based materials, and hybrid nanostructures, together with metamaterials used for plasmonic wave manipulation. The performance limitations of conventional metals, such as high energy losses and limited tunability, can be tackled using metamaterials through tailored electromagnetic responses and enhanced control of plasmonic wave propagation, confinement, and dispersion. Comparative discussions on plasmonic performance and material characteristics are also presented. In addition, deep learning and machine learning approaches for the design and optimization of plasmonic and metamaterial systems are discussed. The fundamentals, material developments, metamaterial-assisted plasmonic engineering, and AI-enabled approaches that shape the future of plasmonic technologies and applications are emphasized in this review.
Wet chemical processing in nano-confined geometries is increasingly required for advanced device fabrication, where the etching rate (ER) of SiO2 is consistently lower than that of blanket films. Although electric double-layer (EDL) overlap has often been invoked to explain this behavior qualitatively, a quantitative, pathway-resolved understanding has been lacking.Here, we present a reaction-pathway analysis framework to quantify confinement-induced etching-rate suppression. By extending the classical Knotter model for dilute-HF etching with an additional OH−-driven dissolution pathway, we reproduce ER behavior across a wide pH range (−1 to 6) under NaOH-based pH adjustment. Statistical fitting of reaction constants (k0−k3) and a surface-speciation parameter (K3) to ER–pH data for both blanket and 3–10 nm confined SiO2 structures enables decomposition of individual pathway contributions.The analysis indicates that negatively charged pathways (HF2− and OH−) are significantly reduced under nano-confinement, whereas the neutral H2F2-driven pathway is comparatively less affected. These trends are consistent with changes in the availability or transport of anionic species in confined geometries, potentially associated with electrostatic effects such as EDL overlap, although contributions from geometric hindrance and specific adsorption cannot be independently ruled out.The fitted kinetic parameters should therefore be interpreted as effective quantities that incorporate multiple confinement-related effects. The model reproduces the ER–pH relationships with small residual errors. The root mean square error (RMSE) is 0.33 Å s−1 for the blanket dataset and 0.22, 0.13, and 0.28 Å s−1 for the 10 nm, 5 nm, and 3 nm confined structures, respectively, indicating good agreement across all conditions relative to the overall ER range. The proposed framework provides quantitative insight into wet etching behavior in nano-confined environments and offers practical guidance for selecting chemistries and pH windows to mitigate etching-rate loss in nanoscale fabrication processes.
Stereolithography (SLA) enables the rapid fabrication of rigid microfluidic devices with complex geometries, but the integration of optical and functional components remains challenging. In particular, the incorporation of glass elements often leads to interfacial defects, incomplete polymerization, and reduced mechanical robustness. In this work, we present an enhanced print-pause-print (PPP) workflow for the fabrication of modular SLA microfluidic devices incorporating glass optical interfaces and functional modules. The proposed approach combines the insertion of a glass coverslip during fabrication with an intermediate curing step designed to polymerize residual resin trapped at the glass-resin interface. This additional processing step improves interfacial bonding and enables the fabrication of leak-free devices capable of withstanding pressures up to 3 bar without interfacial failure. The resulting architecture combines the optical quality of glass with the structural rigidity of SLA printing while preserving compatibility with post-fabrication insertion of functional modules. Hydrodynamic characterization demonstrates stable laminar co-flow behavior and good agreement with numerical simulations, indicating that component integration does not alter channel geometry or flow characteristics. The versatility of the platform is further illustrated through the insertion of an electrode-functionalized module enabling electrically induced particle displacement under continuous flow. These results demonstrate a practical strategy for combining optical accessibility, robust sealing, and functional adaptability within a single SLA-fabricated microfluidic platform.
Multilayer photonic platforms enable large-scale photonic integrated circuits with compact, sophisticated routing and densely integrated components, but their fabrication requires the deposition of high-quality cladding layers and flat intermediate surfaces. Contact planarization using hydrogen silsesquioxane (HSQ) offers a low-cost solution, yet prior demonstrations have been limited to etch depths below 150 nm and minimum feature sizes of 100 nm, well short of the requirements of standard silicon photonic processes. In this work, we present a bilayer HSQ deposition process that achieves effective planarization over a substantially broader dimensional range, covering trench widths from 75 nm to 1 μm and inter-structure spacings from 50 nm to 3 μm, for silicon etch depths of both 220 nm and 300 nm. Residual thickness variations of approximately 1 nm are obtained for narrow features with spacings between 50 nm and 500 nm, rising to approximately 7 nm for large 3 μm trenches. Inter-layer optical transitions between silicon and silicon nitride single-mode waveguides exhibit insertion losses as low as 0.3 dB per interface, confirming the optical quality of the planarized layers. These results establish bilayer HSQ contact planarization as a practical, high-performance approach for silicon-silicon nitride multilayer photonic platforms.
In recent work, we have successfully employed Poly (vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] as an additively printed functional layer embedded in organic coatings on metallic substrates for various piezo- and pyroelectric sensing applications. In practice, however, printed functional layers typically exhibit less favorable physical properties compared to their ideal bulk values. Here, we present a strategy to enhance the ferroelectric performance of a printable composite formulation by incorporating ceramic aluminum nitride (AlN) nanoparticles at high fraction into the hosting P(VDF-TrFE) matrix. Although AlN exhibits comparatively modest piezoelectric properties on its own, its inclusion yields a composite whose effectively usable polarization substantially exceeds that of the baseline P(VDF-TrFE) formulation used so far. By analogy to “hard-magnetic soft materials” (soft polymers with hard magnetic fillers), the resulting nanocomposite may be viewed as a “hard ferroelectric soft material” that combines mechanical compliance and ease of processing with significantly improved ferroelectric functionality for additive manufacturing.
Grayscale lithography is a powerful technique for the fabrication of three-dimensional microstructures, particularly for optical applications requiring precise thickness control. However, optical interference effects within the photoresist, such as standing waves, can significantly affect both the developed resist profile and the resulting surface quality. In this work, we experimentally investigate the influence of standing waves on surface roughness in grayscale lithography and its subsequent transfer into silicon using one-dimensional staircase structures fabricated by Digital Micromirror Device (DMD)–based grayscale exposure. We show that standing-wave-induced dose modulations not only produce oscillations in the developed resist thickness but also lead to pronounced surface roughness maxima at specific exposure doses. These roughness features are amplified during inductively coupled plasma etching (ICP) into silicon, directly impacting the final topography. We further investigate two mitigation strategies—post-exposure bake (PEB) and bottom anti-reflective coatings (BARC). This study highlights the impact of standing waves on the generation of surface roughness in grayscale lithography and suggests approaches for controlling these effects in silicon micro-optical structures.
Cubic boron arsenide (c-BAs) has emerged as a promising III-V semiconductor owing to its combination of ultrahigh lattice thermal conductivity and attractive electronic properties. First-principles calculations demonstrate that BAs could rival diamond in thermal conductivity and have recently been experimentally validated. High-quality single crystals now routinely achieve 1000–1300 Wm−1 K−1 at room temperature, reaching ∼1500 Wm−1 K−1 in isotope-engineered samples. Cubic BAs is a wide bandgap semiconductor (∼1.8 eV) with high elastic modulus, low thermal expansion comparable to equivalent III-V semiconductors such as GaN, and exceptionally high ambipolar carrier mobility (>1600 cm2. V−1 s−1), positioning it as a premier candidate for electronics thermal management and high-power devices. At the device level, BAs has enabled record-performance thermal interfaces and heat-dissipating substrates, including integration beneath GaN or Ga2O3 electronics, where its high interfacial conductance and bulk thermal conductivity enable it to surpass diamond as a substrate in power cooling performance. Beyond bulk, theory and emerging experiments on hexagonal BAs nanosheets reveal mechanically and dynamically stable semiconductors with tuneable bandgaps, anisotropic optical response, promising thermoelectric performance, and applications in flexible, low power memristors. In this article, we present the key challenges in scalable synthesis of defect-controlled crystals and epitaxial thin films, impurity management, and integration with mainstream semiconducting platforms by reviewing the latest advancements in boron arsenide. Experimental measurements of BAs provide a definitive validation of joint three-phonon and four-phonon scattering theory, establishing the material as a benchmark for ultrahigh-thermal conductivity applications. Furthermore, its versatile electronic, optoelectronic, and nanoscale properties enable transformative use in advanced heat dissipating substrates and active layers for next-generation high-power and high-frequency electronics.
The growth of the 3D microfabrication field is fueled by the needs of various applications, ranging from optics, to microfluidics, MEMS or photonics. Following the global trend of micro-components, 3D structures are often not spared by the wish for miniaturization. On the industrial side, this objective rhymes with a requirement for a high resolution, large scale and low-cost 3D microfabrication process. Grayscale PhotoLithography (GPL) is a derivative of classical photolithography, using low-contrast photoresist and unresolved binary masks to perform the fabrication of 3D structures in a single lithography step, thus offering the desired high throughput. The goal of this work is to propose an extension of the GPL technology by the transition to a 193 nm dry photolithography process, for which a relevant low contrast photoresist has been developed. The objective is a proof of concept for the high-volume manufacturing of various submicron 3D features. A dedicated binary photomask has been designed following previously established best practices and the recourse to curvilinear sub-resolution mask features is also investigated. A new ArF photoresist formulation has been developed to meet the requirement in terms of dose sensitivity and coating thickness. This material is shown to display the desired response through the progressive behavior of its contrast curve. The combination of these two achievements enabled performing the first state of the art ArF Grayscale lithography process. The patterning of various submicron resist patterns is demonstrated through tilted SEM inspection and 3D AFM scanning. The viability of the G-ArF process as a strong contestant for the large-scale patterning of submicron 3D structures is proved. Moreover, this study opens the door to many further developments regarding this technology and its future applications.
