A capacitive low-g three-axis accelerometer

This paper presents a compact accelerometer which integrates three spring-proof mass systems on a single structure for sensing three-axis motion in size of 1.3 times 1.28 mm² for operating range of plusmn 2 g. SOG-bulk micromachining and DRIE are adopted to fabricate this accelerometer with high aspect-ratio sensing structure and high yield. This accelerometer shows excellent z-axis output sensitivity and resolution as high as 1.434 V/g and 49 mug/radic(Hz) respectively. For the performances of in-plane accelerometers, the sensitivity and minimum cross-axis sensitivity are 1.442 V/g and 0.03% for x-axis accelerometer and are 1.241 V/g and 0.21% for y-axis accelerometer. From the characterization, this accelerometer design demonstrates high cross-axis sensitivity immunity, high sensitivity, and good linearity for both in-plane and out-of-plane accelerometers that suggests this three-axis accelerometer to be potential for satisfying the needs of future applications to consumer and cell phone market.