World's Smallest Accelerometer

Miniaturization is one of the key drivers in the development of modern MEMS inertial sensors, in particular for Consumer Electronics (CE) where circuit board space is often extremely limited. We have recently built world's smallest commercialized accelerometer - the three-axis acceleration sensors BMA530 and BMA580 measure only 1.2 × 0.8 × 0.55 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup>, thereby reducing the footprint vs. standard molded sensors (LGA 2 × 2 × 0.95 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup>) by more than a factor of 4 and the box volume by more than a factor of 7. The tremendous size reduction is enabled by a combination of stringent optimization of MEMS and ASIC design, vertical integration of MEMS and ASIC on wafer level, and chip-scale packaging (CSP) technologies including through-silicon vias (TSV) in the ASIC. Despite their extremely small size, BMA530 and BMA580 show no tradeoff in performance compared to significantly larger LGA based CE accelerometers. For example, Bias Instabilities of x and y axes lie in the range of 15 − 50 μg and for the z axis at 50 − 80 μg.