A miniaturized bulk micromachined triaxial accelerometer fabricated using deep reactive etching through a multilevel thickness membrane

摘要

We present the design, fabrication and characterization of an application specific triaxial accelerometer for post-surgery heart monitoring. The accelerometer chip is designed as a 2 × 4 × 1.2 mm~3 chip with nominal acceleration range of ±4 g and frequencies below 50 Hz. It has been fabricated using a multiproject wafer service with an additional deep reactive ion etching process to obtain controlled etch-through of membranes of 3, 23 and 400 μm thicknesses simultaneously. The novelty of the work presented here is the bulk micromachining technique using both deep reactive dry etching and alkali-based anisotropic wet etching of single crystal (100) silicon wafers used to obtain a space efficient design. Proof of concept is demonstrated with preliminary testing, with an acceleration sensitivity of ～0.04 mv/V/g for out of plane (z axis) acceleration.