One-step fabrication of micro/nanotunnels in metal interlayers

A micro/nanotunnel is a very useful structure, which has been used as an interconnected pass in various micro/nano systems. Here, a novel micro/nanotunnel fabrication method in a metal interlayer ZnS–SiO₂/Sn/ZnS–SiO₂ sandwich structure is proposed based on a laser direct writing (LDW) technique. The experimental results show that the arched tunnel is 170 nm in width and 50 nm in height, far beyond the diffraction limit of the LDW system with a 533 nm laser and 0.9 NA objective lens. In only one step, an arbitrary tunnel can be fabricated, exhibiting its simple, designable and practical features, and providing a new route for micro/nanotunnel fabrication.