Large-Area Dual-Scale Metal Transfer by Adhesive Force

A study was conducted to demonstrate a dual-scale metal transfer from the ridge and valley parts of a mold by utilizing a difference in adhesive force. This dual-scale patterning allowed for metal patterns of two different length scales from a single master, significantly reducing process complexity and costs involved in preparing a master. A polyurethane acrylate (PUA) mold was replicated from a silicon master by replica molding for the investigations. A thin metal layer was deposited on the PUA mold using a thermal evaporator with a layer thickness of 20-200nm. A thin and flat Norland Optical Adhesive (NOA) 71 layer was spin-coated on a clean Pyrex wafer as an adhesive layer and attached to a poly(ethylene terephthalate) (PET) support to transfer a metal layer from the ridges of the mold. A metal was also deposited with a relatively high deposition rate by a thermal evaporator, giving rise to voids within the valleys and upon removal of the mold.