A strategy to fabricate nanostructures with sub-nanometer line edge roughness.

Line edge roughness (LER) has been an important issue in the nanofabrication research, especially in integrated circuits. Despite numerous research studies has made efforts on achieving smaller LER value, a strategy to achieve sub-nanometer level LER still remains challenging due to inability to deposit energy with a profile of sub-nanometer LER. In this work, we introduce a strategy to fabricate structures with sub-nanometer LER, specifically, we use scanning helium ion beam to expose hydrogen silsesquioxane (HSQ) resist on thin SiNx membrane (∼20 nm) and present the 0.16 nm spatial imaging resolution based on this suspended membrane geometric construction, which is characterized by scanning transmission electron microscope (STEM). The suspended membrane serves as an energy filter of helium ion beam and due to the elimination of backscattering induced secondary electrons, we can systematically study the factors that influences the LER of the fabricated nanostructures. Furthermore, we explore the parameters including step size, designed exposure linewidth (DEL), delivered dosage and resist thickness and choosing the high contrast developer, the process window allows to fabricate lines with 0.2 nm LER is determined. AFM measurement and simulation work further reveal that at specific beam step size and DEL, the nanostructures with minimum LER can only be fabricated at specific resist thickness and dosage.

Fabrication of Robust, Anti-reflective, Transparent Superhydrophobic Coatings with a Micropatterned Multilayer Structure.

Transparent superhydrophobic coatings with mechanical stability, self-cleaning function, and anti-reflective property have drawn much attention due to the great potential in a variety of real-world applications. In this work, we develop an ingenious approach to construct micropatterned transparent superhydrophobic coatings with a multilayer structure (water contact angle ∼153.6°, sliding angle ∼3.2°). A micropatterned ultraviolet-cured resist frame facilitates durability, while the modified silica nanoparticles, which are housed within the micro-cavities and bonded by an epoxy-based adhesive, impart superhydrophobicity. The micropatterned multilayer surface could endure sandpaper abrasion while maintaining satisfactory hydrophobicity. The prepared surfaces also retain the excellent water repellency after water jet impact, acid submerging, and mechanical bending, suggesting that they are sustainable in the case of adverse conditions and can be integrated with objects with non-flat geometries. Further, the superhydrophobic coatings exhibit an anti-reflection property while preserving high transparency. Taken together, we envision that the design strategies here can offer a practicable route to produce transparent superhydrophobic coatings for diverse outdoor applications.