Large-size liftable inverted-nanobowl sheets as reusable masks for nanolithiography

A low-cost procedure is introduced for fabricating large-area, liftable, ordered TiO ₂ nanobowl sheets. The sheet is made using the template of self-assembled polystyrene spheres, followed by atomic layer deposition (ALD), ion milling, and etching. By introducing a thin organic layer between the nanobowls and the substrate, the whole sheet can be lifted-off in full size. The dimension of the holes at the bottom of the nanobowls is controlled by additional ALD; thus, the sheet has been applied as a reusable mask for producing nanodot patterns with designed sizes. This technique demonstrates a simple and economic nanolithiography approach for producing various designed patterns without using a clean room, and it has a great potential for scale-up, mass production, and commercial applications.