Parylene-MEMS technique-based flexible electronics

Abstract

This paper reports a novel fabrication strategy for flexible electronics based on the parylene-MEMS (micro-electromechanical system) technique. A set of parylene-filled trenches is used to mechanically connect silicon-based functional units and realize a flexible 4$\times$6 temperature controlling array as a preliminary demonstration. The trench-filling performance of the parylene deposition is carefully studied, and an optimized process is established to minimize the keyhole inside the parylene-filled trench. The effect of trench width on the flexibility and bendability of the prepared flexible electronics devices is analyzed by finite element modeling. Performances of the thermal/electrical isolation and the mechanical connection of the prepared parylene-filled trenches have been tested. The experimental results indicate that the highest thermal isolation efficiency is approximately 72.5% with the 10 paralleled, 7 $\mu$m wide and 50 $\mu$m deep parylene-filled trenches. The leakage current of the 10 paralleled, 5 $\mu$m wide and 100 $\mu$m deep parylene-filled trenches is less than 2 pA under a voltage of 100 V. Besides, these parylene-filled trenches acting as the flexible linkage of connected silicon-based functional units exhibit high connection performance without rupture when the loading pressure is under 200 kPa. Due to the powerful silicon microfabrication capability and excellent compatibility of the parylene-MEMS technique, the present flexible electronics strategy holds a promising potential for applications in various areas.