Metallization on three dimensions microstructures using photoresist spray coating for microdirect methanol fuel cell

High-efficientcy micro-electrochemical devices are realized by increasing electrode surface areas while maintaining keeping chip size. The use of three dimensional (3-D) electrodes instead of planar electrodes is effective for this purpose. To realize a metal pattern on 3-D structures, spray coating was utilized and the optimum condition for achieving a good photoresist step coverage was determined. A good step coverage of the photoresist was obtained on the obtuse corner formed by the anisotropic wet etching of (100) silicon and even on the vertical corner formed by deep reactive ion etching (RIE). We applied this method to fabricate a high-performance micro direct methanol fuel cell (μDMFC). An open circuit voltage of 548 mV and a maximum power density of 0.72 mW/cm² were obtained at room temperature with 2 M methanol.