Fuse-tethers in MEMS: theory and operation

Micro-electro-mechanical-systems (MEMS) have designs which incorporate freestanding structures. These freestanding structures must be attached to the substrate during fabrication, and released when they are to be utilized. Tethers are long thin beams that mechanically anchor the freestanding structure to the substrate. In our study, we focused on the fuse-tether design and its associated Joule heating breaking technique. We investigated the breaking characteristics of two fuse-tether designs based on different current pulses. For each design, the current pulse which produced the most desirable break was chosen for more rigorous testing on 20 tethers. The reliability tests resulted in at least 80% success rate. In addition to empirical testing, we utilized ANSYStrade to simulate the Joule heating process. The ANSYStrade model produced results that closely matched the break characteristics observed in the empirical tests. This research demonstrated that a fuse-tether can be severed reliably with the Joule heating technique, and the outcome can be predicted with proper modeling before fabrication