Micro-patterning of metallic film structures through direct-write dewetting

A new method of patterning metallic thin films is described. Through the use of a focused laser deflected by a high-speed, galvanometer scanning system, a variety of fine metal patterns are realized on inorganic and organic substrates. This method exploits the metastable wetting characteristics of metallic thin films as deposited by physical vapor deposition upon non-metallic substrates. Differences in surface energy and intermolecular forces between the target and the substrate provide a driving force for retraction of the thin film, while the laser provides the energy needed to overcome the kinetic barrier to dewetting. Electronically isolated feature sizes in the range of the tens of microns are fabricated. During formation, material is displaced rather than ablated allowing controlled accumulation of the target material. This results in a user-determined increase of the metal feature thickness. Evidence of accurate and reproducible periodic and complex structures made feasible by virtue of the scan system, are presented. This technique provides an alternative to current thin film patterning techniques and introduces a new way of building out-of-plane structures from metallic thin films. Application fields may include flexible sensors, electrochemical devices, and especially microfluidic devices, as the technique allows formation of conductive micro-channels with user-defined height.