Multiform structures with silicon nanopillars by cesium chloride self-assembly and dry etching

We develop a novel method to fabricate multiform structures of Si nanopillars (diameters > 40 nm, aspect ratio > 10, coverage ratio > 35%) by dry etch with self-assembled cesium chloride (CsCl) nanoislands as mask. The pillars can cover structures of lateral size 1 μm and unpolished Si wafer, enabling uneven surface to be textured by nanopillars without complex process or expensive polishing. Planar micro-patterns and tridimensional localization of nanopillars have been easily realized, useful for integrating nanopillars to devices. By figuring out substrate influences, fast formation of CsCl islands within 1 min has been achieved for the first time, making CsCl process flow to be possibly controlled within 30 min. Based on the deliquescence of salt, CsCl self-assembly is simple, widely tunable and compatible, which endows the approaches great practical potential.

Highlights► Nanopillars homogeneously cover uneven surface by dry etch with CsCl nanoislands. ► Wettability and roughness of substrate influence CsCl mask formation. ► Formation within 1 min and process flow within 30 min are possible. ► 2D patterns are realized by using photoresist as lift-off or intermediate layer. ► Two rounds of 2D process enable 3D patterns of nanopillars.