Published on: 6/15/2017
WIMS2 researchers, Prof. Khalil Najafi and doctoral student Stacey Tang, have developed a new type of multi-axis, capacitive, MEMS accelerometer made from thick silicon. The new accelerometer can achieve sub-µg resolution (<1µg/vHz) and high areal sensitivity (1pF/g per 1mm2). It has a 3D, vertical, biomimetic hair-like structure, and is microfabricated from a thick silicon wafer using a new 2-gap microfabrication process that is also compatible with CMOS device integration.
The novel process circumvents some of the stringent requirements on deep reactive ion etching (DRIE) when etching thick (>500µm) layers. It enables the fabrication of large proof-mass (1mm tall, >2.33 milligram/mm2), high aspect-ratio (HAR) narrow sense gaps (<3 µm wide, >250 µm tall), and a large sense/feedback electrode area (>250 µm tall). The result is a MEMS accelerometer with an area smaller than any previous precision accelerometers with similar perf