Single-Mask Field Emsission Based Tunable MEMS Tunneling Accelerometer

This work presents an electrostatically tunable field emission tunneling accelerometer fabricated using a single mask fabrication process. A change in the gap between the tunneling electrodes due to acceleration modulates the tunneling current flowing across the device tunable nanoscale gap. The device is shown to follow the Fowler Nordheim principle for field emission tunneling. Sensitivities as high as 6.5 mu A/g have been demonstrated for this accelerometer for a at rest tunneling gap size of similar to 40nm. The device has been fabricated out of the 25um thick device layer of an SOI substrate via a single lithography step and deep reactive ion etching of silicon. Submicron tunneling gaps are formed by deposition of a thick layer of gold with slight sidewall coverage. Electrodes for electrostatic tuning of the emission gap embedded in the design have been used to further reduce the tunneling gap that also allows tuning of the acceleration sensitivity over a wide range.