A monolithic three-axis micro-g micromachined silicon capacitive accelerometer


Chae J., Kulah H., Najafi K.

JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, vol.14, no.2, pp.235-242, 2005 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Volume: 14 Issue: 2
  • Publication Date: 2005
  • Doi Number: 10.1109/jmems.2004.839347
  • Journal Name: JOURNAL OF MICROELECTROMECHANICAL SYSTEMS
  • Journal Indexes: Science Citation Index Expanded, Scopus
  • Page Numbers: pp.235-242
  • Keywords: inertial sensors, micro-g, micromachined accelerometer, sigma-delta, switched-capacitor, three-axis accelerometer

Abstract

A monolithic three-axis micro-g resolution silicon capacitive accelerometer system utilizing a combined surface and bulk micromachining technology is demonstrated. The accelerometer system consists of three individual single-axis accelerometers fabricated in a single substrate using a common fabrication process. All three devices have 475-mu m-thick silicon proof-mass, large area polysilicon sense/drive electrodes, and small sensing gap (< 1.5 mu m) formed by a sacrificial oxide layer. The fabricated accelerometer is 7 x 9 mm(2) in size, has 160 Hz bandwidth, > similar to 5 pF/g measured sensitivity and calculated sub-mu g/root Hz mechanical noise floor for all three axes. The total measured noise floor of the hybrid accelerometer assembled with a CMOS interface circuit is 1.60 mu g/root Hz (> 1.5 kHz) and 1.08 mu g/root Hz (> 600 Hz) for in-plane and out-of-plane devices, respectively.