Design, Fabrication, and Assembly of Multi-chip Walking Silicon Microrobots

Microrobots can someday be used as a tool to further expand investigative capabilities– for example, archeologists could use them to research buried cities such as the one in Tiwanaku, Bolivia, or emergency response workers could send robots ahead in search-and- rescue operations. The anatomy of a microrobot can be broken down into its body, brain and power. Typically, each subsystem is fabricated using a different process, creating the need for multi-chip assembly. Microrobots in the literature are often assembled post-process using methods such as wire bonding, silver epoxy, and flip-chip bonding. These approaches tend to be time consuming, tedious and may even harm the devices. Additionally, not all of them provide the necessary mechanical robustness needed for a moving walking microrobot. This work presents a zero-insertion force (ZIF) socket as a solution to achieving robust electrical, and mechanical assembly of a walking silicon microrobot. The ZIF socket and body of the microrobot are composed of various micro-electro mechanical systems (MEMS) fabricated using a three-mask silicon-on-insulator (SOI) process. First, successful MEMS- MEMS assembly using a ZIF socket is presented, as well as important design considerations. Subsequently, proof-of-concept and first results for MEMS-CMOS assembly is shown, inte- grating a complimentary metal-oxide semiconductor (CMOS) chip into a ZIF socket. Finally, the full system design of a walking silicon microrobot (not yet fabricated) using the Single Chip micro Mote (SCμM) CMOS chip as a brain, and a solar cell chip (Zappy2) for power is introduced.