Micro-Tethering for Fabrication of Encapsulated Inertial Sensors With High Sensitivity

Flader, I.B., Chen, Y.H., Yang, Y.S., Ng, E.J., Shin, D.D., Heinz, D.B., Ortiz, L.C., Alter, A.L., Park, W., Goodson, K.E., Kenny, T.W., 2019, "Micro-Tethering for Fabrication of Encapsulated Inertial Sensors With High Sensitivity," J. MicroElectroMechanical Systems, Vol. 28, pp. 372-381.

Download PDF

This paper demonstrates a post-fabrication technique for creating highly compliant structures inside a hermetic, wafer-scale encapsulation process. Single crystal silicon micro-tethers were fabricated alongside compliant structures to temporarily provide additional anchoring and increased device rigidity during the fabrication process. This technique mitigates in-process stiction for compliant devices by tethering the large, free-moving structures during fabrication. After successful fabrication, the micro-tethers can be selectively removed by two methods. The first method utilizes a potential voltage difference across the device. Joule heating can be concentrated in the microtether and the device separated after supplying requisite heat energy. The second method utilizes mechanical fracturing where a large external force is applied to separate the device from the tether. Micro-tethers in this paper were attached to differential resonant beam accelerometers, and were designed for detachment by each method: Joule heating and mechanical fracture. Our results show that the 40 mu m thick device can be successfully detached by both methods, indicated by the device sensitivity increase from similar to 100 Hz/g to similar to 400 Hz/g.

Related Projects

The basic physics of phonon conduction in dielectrics and semiconductors has been the focus of research for more than a century. However, recent improvements in nanofabrication technologies have...
The most innovative energy conversion technologies, ranging from solar and thermoelectrics to lasers (which convert electric energy to light), are benefitting from nanostructures and/or...