Robust Method of Fabricating Epitaxially Encapsulated MEMS Devices with Large Gaps

This paper presents a novel wafer-level thin-film encapsulation process that allows both narrow and wide trenches, which are necessary for traditional structures such as combdrives. Fully functional devices with trench widths up to 50 μm are fabricated by employing a vapor phase XeF₂ isotropic silicon etch to create large cavities and an epitaxial deposition seal to encapsulate the devices in an ultra-clean, high vacuum environment with no native oxide and humidity. In this paper, we demonstrate the robustness of the proposed fabrication process, as well as the inherent benefits of the high-temperature epitaxial encapsulation process: high quality factor, extreme stability, exceptional aging, and fatigue performance. [2017-0098].