Surface-Tension-Driven Self-Alignment of Microchips on Black-Silicon-Based Hybrid Template in Ambient Air

In this paper, we demonstrate self-alignment of microchips on a simple-to-fabricate hybrid template with both water and UV-curing adhesive (EPO-TEK UVO-114). The hybrid template contains receptor sites with solid edges for droplet confinement and large wetting contrast between the receptor sites and the substrate for microchip manipulation. Nanostructured black silicon surface functionalized with fluoropolymer is used as a substrate, while protruded silicon dioxide patterns covered with fluoropolymer serve as receptor sites. A simple and fast process consisting only of one pass of photolithography, cryogenic deep reactive-ion etching (RIE), and RIE steps is used to fabricate the hybrid template. The self-assembly tests are carried out in a hybrid microassembly setup. Dummy microchips of sizes 200 μm × 200 μm × 50 μm are self-aligned on 200 μm × 200 μm receptor sites in ambient air with both water and adhesive.