Reliability of an 1000 G Range Vertically Integrated Silicon on Insulator (SOI) Impact Switch

We report on a reliability study of an inertial impact switch designed to be operated at up to 1000 g acceleration range and entirely fabricated from single-crystal silicon, except for the thin-film metallic contacts. The device is distinguished by its vertically integrated architecture, enabling wafer-level fabrication and making the device to be truly manufacturable. The microfabrication process involved evaporation of the metallic contacts, deep reactive ion etching (DRIE) of a silicon on insulator (SOI) substrate and of an additional bottom wafer, and direct wafer bonding. Drop test results, which are in accordance with the model predictions, demonstrate the functionality of the sensor. Reliability tests carried out by running tens of drops at the 1000 g acceleration level, demonstrated high repeatability of the switch performance metrics. The results of an extensive experimental study indicate that thin metallic layers deposited on Si can serve as reliable Ohmic contacts in high g impact switches.