Micro/nano-mechanical structure fabricated by transfer printing

Abstract

A fabrication of micro-electro-mechanical systems (MEMS) generally involves complicated conventional semiconductor processes. Simply micro/nano-structuring process is a technical issue on further wide range of MEMS application. This study proposes to apply transfer printing to fabricate a mechanical structure for MEMS elements. Some metals (Au, Cu and Ni) are previously deposited to be thin-films on a micro-ridged poly-dimethyl-siloxane (PDMS) stamp, while a micro-grooved SU-8 is prepared as a substrate. Contact-and-release process allows the metal thin-film to be locally transferred from the micro-ridges of stamp to the micro-grooved substrate. The transferred Au and Ni thin-films successfully form to be an ultra-thin fixed beam, “cross-linked structure”, of which the thickness is less than 100 nm. The fabricated structure is applicable to a nano-scale mechanical oscillator. The production yield of fixed beam increases with thin-film thickness and highly-dense of thin-film. The micro-roughness and hydrophobicity of stamp enhance the production yield of ultrathin fixed beam. These experimental results clearly indicate that the proposed process is dominated by an adhesion force between the stamp and the thin-film as well as the mechanical strength of the thin-film. Nevertheless, it is confirmed the transfer printing process is effective for a fabrication of MEMS element.