A convenient method to fabricate multilayer interconnections for microdevices

We report a new method to fabricate multilayer interconnections without requiring wet or dry etching or deposition of insulating layers. Three levels of electrical connections are obtained by merely repeating deposition, photolithography, and anodization of a metal layer. Without the need to etch metal layers or deposit and etch insulation layers, the overall process is simple, cheap, safe, and of low temperature. While the utility is general for a wide variety of microdevices and electronics, in this paper we demonstrate one application by developing a low-cost fabrication of a large-array electrowetting-on-dielectric (EWOD) chip that requires three metal layers.