Surface Deformation of Metal Films Under Controlled Pressure for Generating Ultra-flat Metal Surfaces

Abstract

We present a technique to generate ultra-smooth surfaces and direct pattern imprinting on thin metal films by flattening the bumps and spikes of a freshly vacuum deposited metal film. The technique was implemented by using a small footprint mechanical imprint press that has the capability to vary the applied pressure from 100MPa to 600MPa. The mechanical press was incorporated with a tactile force sensor that enabled direct monitoring of the applied pressure. We demonstrated the feasibility of the technique on an e-beam evaporated silver (Ag) metal film with thickness ranging from 150Å (optically thin) to 1000Å (optically thick). The film was deposited on double-polished (100)-oriented silicon surface and double-polished borosilicate glass, resulting in a varying degree of film smoothness. The surface morphology of the pressed thin film was then studied using atomic force microscopy and SEM. Our demonstration with the e-beam evaporated silver thin film exhibits the potential for applications in decreasing the scattering-induced losses in optical metamaterials, plasmonic nanodevices and electrical shorts in molecular-scale electronic devices.