Wettability enhancement by rough surfaces generated by thin film technology

Abstract Wettability is a very important property of surfaces, especially in microsystem applications. It can be manipulated directly by surface properties—especially by the roughness of the surface. The wettability of smooth hydrophilic surfaces is improved by roughening them. The contrary effect is observed with smooth hydrophobic surfaces—by roughening, the contact angle will increase. In this article, a thin film process with excellent edge coverage is demonstrated. A sputtered tin (Sn) layer forms a reproducible, well-defined rough surface with an average roughness of approximately 188 nm. Wettability can be manipulated in a wide range with a Wenzel-relation of approximately r=2.6.