With the growing importance of three-dimensional (3D) nanomaterials and devices, there has been a great demand for highfidelity, full profile topographic characterizations in a nondestructive manner. A promising route is to employ a high-aspect-ratio (HAR) probe in atomic force microscopy (AFM) imaging. However, the fabrication of HAR-AFM probes continues to suffer from extravagant cost, limited material choice, and complicated manufacturing steps. Here, we report one-step, on-demand electrohydrodynamic 3D printing of metallic HAR-AFM probes with tailored dimensions. Our additive fabrication approach yields a freestanding metallic nanowire with an aspect ratio over 30 directly on a cantilever within tens of seconds, producing a HAR-AFM probe. Furthermore, the benefits associated with unprecedented simplicity in the probe's dimension control, material selection, and regeneration are provided. The 3D-printed HAR-AFM probe exhibits a better fidelity in deep trench AFM imaging than a standard pyramidal probe. We expect this approach to find facile, material-saving manufacturing routes in particular for customizing functional nanoprobes.
The fabrication of high‐resolution patterns on flexible substrates is an essential step in the development of flexible electronics. However, the patterning process on flexible substrates often requires expensive equipment and tedious lithographic processing. Here, a bottom‐up patterning technique, termed electrochemical replication and transfer (ERT) is reported, which fabricates multiscale patterns of a wide variety of materials by selective electrodeposition of target materials on a predefined template, and subsequent transfer of the electrodeposited materials to a flexible substrate, while leaving the undamaged template for reuse for over 100 times. The additive and parallel patterning attribute of ERT allows the fabrication of multiscale patterns with resolutions spanning from sub‐100 nm to many centimeters simultaneously, which overcomes the trade‐off between resolution and throughput of conventional patterning techniques. ERT is suitable for fabricating a wide variety of materials including metals, semiconductors, metal oxides, and polymers into arbitrary shapes on flexible substrates at a very low cost.
Functional nanostructures are exploited for a variety of cutting-edge fields including plasmonics, metasurfaces, and biosensors, just to name a few. Some applications require nanostructures with uniform feature sizes while others rely on spatially varying morphologies. However, fine manipulation of the feature size over a large area remains a substantial challenge because mainstream approaches to precise nanopatterning are based on low-throughput pixel-by-pixel processing, such as those utilizing focused beams of photons, electrons, or ions. In this work, we provide a solution toward wafer-scale, arbitrary modulation of feature size distribution by introducing a lithographic portfolio combining interference lithography (IL) and grayscale-patterned secondary exposure (SE). Employed after the high-throughput IL, a SE with patterned intensity distribution spatially modulates the dimensions of photoresist nanostructures. Based on this approach, we successfully fabricated 4-inch wafer-scale nanogratings with uniform linewidths of <5% variation, using grayscale-patterned SE to compensate for the linewidth difference caused by the Gaussian distribution of the laser beams in the IL. Besides, we also demonstrated a wafer-scale structural color painting by spatially modulating the filling ratio to achieve gradient grayscale color using SE.
Patterning high-aspect-ratio gratings by the phase-locked two-beam fiber-optic interference lithography (2-FOIL) is numerically and experimentally investigated in this paper. The Dill model is applied in the numerical simulation to understand the effects of an exposure dose and pattern contrast on the exposed photoresist grating profiles. Exposure experiments on the authors’ home-built 2-FOIL setup are conducted to demonstrate the suitability for manipulating the linewidth of photoresist gratings by tuning the exposure dose to achieve high aspect ratios over 6 at high pattern contrast thanks to the phase-locking mechanism. The high-aspect-ratio photoresist gratings serve as an excellent etching mask for the subsequent pattern transfer into underlying silicon substrates for high-aspect-ratio silicon gratings. Using these high-aspect-ratio silicon gratings as the nanoimprint mold, a square nanomesh is demonstrated by means of the multiple-step nanoimprint lithography. The authors’ work demonstrates that the proposed phase-locked 2-FOIL system enables high pattern contrast under long exposure duration, making it a suitable tool for fabricating high-aspect-ratio grating structures.
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