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The selection of an affordable method to fabricate plasmonic metasurfaces needs to guarantee complex control over both tunability and reproducibility of their spectral and morphological properties, making plasmonic metasurfaces suitable for integration into different sensing devices. Displacement Talbot lithography could be a valid solution thanks to the limited fabrication steps required, also providing the highly desired industrial scalability. Fabricated plasmonic metasurfaces are represented by a gold nanohole array on a glass substrate based on a triangular pattern. Scanning electron microscopy measurements have been recorded, showing the consistency of the surface features with the optimized design parameters. Reflectance and transmittance measurements have also been carried out to test the reliability and standardization of the metasurface's optical response. Furthermore, these plasmonic metasurfaces have also been successfully tested for probing refractive index variations in a microfluidic system, paving the way for their use in sensitive, real-time, label-free, and multiplexing detection of bio-molecular events. [ABSTRACT FROM AUTHOR]

We demonstrate the fabrication of metal and dielectric nanostructures using interference lithography with extreme ultraviolet (EUV) and soft x-ray synchrotron radiation down to a 2.5 nm wavelength. These specific wavelengths are chosen because of the industrial relevance for EUV lithography and because they are in the vicinity of the oxygen absorption edge of the high-resolution hydrogen silsesquioxane photoresist, allowing for the exposure of thick layers. We investigate the requirements to fabricate such structures and demonstrate that tall metal nanostructures with aspect ratios up to 7 could be achieved by EUV interference lithography and subsequent electroplating. We use the unique depth-of-focus-free property of interference and achromatic Talbot lithography to fabricate uniformly tilted dielectric nanostructures. [ABSTRACT FROM AUTHOR]

Extreme ultraviolet interference lithography (EUV-IL) is a relatively simple and inexpensive technique that can pattern high-resolution line/space and has been successfully used for the resist performance testing. While the aerial image in EUV-IL formed by two beams is straightforward to understand and has contrast of 1, the aerial image formed by four beams providing contact holes is rather complicated. The beam polarization and relative phases of the individual beams play a significant role in the aerial image formation in four-beam interference lithography. In particular, controlling the relative phase of the beams is very difficult to achieve due to short wavelength. To circumvent this problem, we propose an effective double exposure four-beam interference lithography method, by intentionally designing the grating with a slightly different pitch to create an optical path difference that is longer than the coherence length of the EUV light (13.5 nm). We numerically prove the effective double exposure four-beam interference is not sensitive to the phases difference and verify our analytical model by printing both positive tone chemically amplified resist and a negative tone inorganic resist. [ABSTRACT FROM AUTHOR]

Grayscale electron beam lithography (g-EBL) is a fabrication technique that allows for tunable control of resist topography. In most cases, the height of the structures is in the submicron regime. Here, we present an extensive experimental characterization of the post electron beam exposure behavior of poly(methyl methacrylate) (PMMA) 950 K for grayscale structuring with several micrometers in height. The obtained results show that the development depth for the same electron dose is dependent on the time between exposure and development. This dependence becomes more prominent at higher exposure doses. Additionally, it was found that a post-exposure bake influences the dose-response behavior of the resist material and, therefore, also the obtained three-dimensional (3D) structure. This work paves the way for well-controlled 3D micrometer structuring via g-EBL. Unlabelled Image • Grayscale e-beam lithography is used for the fabrication of three-dimensional structures with several micrometers in height. • The contrast curve of PMMA 950K depends on the time between e-beam exposure and development. • The change of the contrast curve over time can be described by a unifying exponential fit function. • A post-exposure bake influences the dose-response behavior of PMMA (950 K). [ABSTRACT FROM AUTHOR]

Periodic patterning is important for various scientific and technological applications, especially in the nanoscale. Achromatic Talbot lithography (ATL) utilizing extreme ultraviolet (EUV) wavelengths, notably 13.5 nm, is a powerful lithographic technique enabling high-resolution and high-throughput nanopatterning over large areas. Improving the resolution and the throughput of the technique requires elaborate designs based on simulations and nanofabrication of transmission diffraction gratings on thin silicon nitride membranes. Our simulations point to the fact that compared to conventional ATL masks with hole arrays, masks consisting of annular rings and intersecting annular rings show increased performance in terms of throughput. A set of masks with uncrossed and crossed annular rings have been nanofabricated and exposed with spatially coherent synchrotron EUV light and the experimental results confirm our theoretical predictions that masks with annular rings and crossed rings yield dot arrays with improved throughput. The presented technique may enable applications in science and technology where large-area and periodic nanopatterning is needed. Unlabelled Image • Achromatic talbot lithography at EUV wavelengths is a powerful technique for periodic patterning. • The efficiency of the technique can improve by implementing masks with annular ring arrays instead of hole arrays. • The resolution of the technique can increase by intersecting the rings. • Masks comprising annular rings have been designed, simulated, and fabricated by high-resolution electron beam lithography. • Experiments with extreme ultraviolet confirm the theoretical predictions. [ABSTRACT FROM AUTHOR]