Using various nano processing technologies to achieve precise control processing of multiple nanostructures

Nanostructures and devices prepared by various nano-processing technologies have played an important role in the fields of micro-nano photonics, micro-nano electronics, biology, and nano-energy, but they also play an important role in the size, shape, spatial arrangement, and assembly of nano-processing. And other process control puts forward higher and higher requirements.

Existing traditional nano-processing technologies (such as electron beam exposure, focused ion beam direct writing, anodizing, and self-assembly technology) usually have the advantages of achieving controllable processing of special nanostructures such as disorder, hybridization, irregularity, and diameter reduction. Obvious limitations, it is difficult to achieve precise control of complex and multiple nanostructures in materials and shapes. Therefore, a more powerful nanofabrication method is needed to meet the extreme processing requirements of special nanostructures.

The team of the Institute of Physics, Chinese Academy of Sciences/Beijing National Research Center for Condensed Matter Physics Microprocessing Laboratory team is committed to the research of new methods and principles of nanomanufacturing and the application of optoelectronic devices.

Grain boundary fracture and strain processing of the sub-5 nm metal gap structure array developed in the early stage (Adv. Mater. 2015, 27, 3002; Nanoscale. 2018, 10, 3073; Small. 2019, 15, 1804177) and nano-origami 3D processing Methods (Light: Sci. & Appl. 2016, 5, e16096; Adv. Mater. 2019, 31, 1802211; Nano Lett. 2019, 19, 3432; Laser Photonics Rev. 2020, 14, 1900179; Nat. Commun. 2021, 12, 1299).

Geng Guangzhou (the first author of the paper) of the team, under the guidance of the chief engineer Li Junjie, and Gu Changzhi, a researcher in the N10 group, developed a soft template-based atomic layer assembly nano-fabrication technology, which solved the problem of traditional rigid templates. Good flexibility, scalability, and universality, and its powerful nanostructure construction capability can realize the controllable cutting processing of various materials hybrid, heterogeneous complex nanostructure arrays, and functional device applications.

The related research results are titled Precise tailoring of multiple nanostructures based on atomic layer assembly via versatile soft-templates, published on Nano Today. 2021, 38, 101145, and selected as the front cover of the journal's volume 39C.

Researchers first used electron beam exposure technology to expose the designed pattern on the electron beam resist soft template, and then used atomic layer deposition technology to conformally assemble various functional materials (such as TiO2, ZnO, Al2O3 and HfO2, etc.), and then remove the top layer and soft membrane plate through a separate etching process, and finally prepare large-area complex nanostructure arrays with various specificities.

This soft film-based atomic layer assembly processing technology combines the high resolution of electron beam exposure and the advantages of precise and controllable atomic layer deposition and conformal coating. It can not only prepare various hollow/solid multiple nanostructures but also realize In the processing of flexible substrates, especially ultra-high aspect ratio (~80:1), ultra-high precision (~1 nm), ultra-thin tube wall (~8 nm), and excellent uniformity of extreme nanostructures can be obtained.

Based on this processing method, researchers have also developed a multi-stage tubular diameter-reducing nanostructure processing technology, which uses multi-layer resist atomic layer assembly processing technology, which overcomes the use of conventional micro-nano processing technology for multiple engraving, The steps are cumbersome and time-consuming, and the processing accuracy is not high. The perfectly prepared various variable diameter nanostructure arrays have potential application value in optical metasurfaces, multifunctional multiplexed nanodevices, and biological fields.

In addition, by using this assembly processing technology, it is also possible to prepare a three-dimensional nanostructure array that is hybridized and compounded by a variety of materials and is multi-element orderly and controllable, which is used in the preparation of nano-optoelectronic devices such as photonic crystals and three-dimensional ring gate transistors that are Multi-functionally regulated. Has application prospects.

To verify the functional device application of the atomic layer assembly processing method, the researchers used this process to design and fabricate an all-media high-efficiency optical metasurface device with anisotropic structure characteristics, through the difference of the high aspect ratio nano fin structure unit The angle rotation and misalignment arrangement realize the arbitrary polarization control of the wide-band vector beam.

At the same time, it also designed and prepared Al2O3/TiO2 composite hollow hexagonal nanostructure arrays with high aspect ratio and large specific surface area, and combined with Pd nanoparticles. Based on the principle of heterogeneous interface two-dimensional electron gas, high-performance hydrogen was constructed. The sensor, the sensor performance obtained has a greater improvement than the traditional planar hydrogen sensor, especially the high sensitivity and the shortest recovery time at a lower temperature, which provides an ideal solution for the high-performance hydrogen sensor.

This atomic layer assembly nano-processing method gives traditional exposure and assembly technologies more powerful processing capabilities and potentials and shows better flexibility, scalability, and universality in the controllable processing of multiple nanostructures. It provides a simpler and more precise processing strategy for complex three-dimensional nanostructure array technology, which shows application potential in the process of multiple designs, extreme processing, and functional realization of advanced nanostructures and devices.

The research work was funded by the National Key Research and Development Program of the Ministry of Science and Technology, the National Natural Science Foundation of China, and the Chinese Academy of Sciences.