Fabrication of micro/nanotubes by mask-based diffraction lithography

We demonstrate a scalable and repeatable method to fabricate micro/nanotubes. Mask-based diffraction lithography was modeled, and the effects of key parameters including the wavelength of the illuminant light, the thickness of the photoresist, the diameter of the photomask pattern and the exposure dose during the process were simulated. Analysis of the results indicates that the optical intensity distributions in the photoresist form separated regions, which can be used to fabricate micro/nanotubes. Experiments were then carried out, and we achieved the production of silicon microtubes and tube-in-tube arrays. It can be found that the outer diameter of the microtubes decreases while the inner diameter increases with the increment of exposure time, consistent with the simulation results. Thus, the optical model is suitable for explaining experimental phenomena, guiding experiments and optimizing the fabrication process. The obtained silicon microtubes exhibit fine hydrophobic properties and provide a good matrix for integrating active nanomaterials, which can provide great potential in their application to energy storage devices, solar cells, sensors and catalysts.