A NOVEL SILICON ACCELEROMETER WITH A SURROUNDING MASS STRUCTURE

A new accelerometer with a surrounding mass structure is proposed to achieve the extreme reduction in sensor die size. The sensor has a very high sensitivity due to a high seismic mass area ratio compared to a conventional accelerometer. This structure provides a heavy seismic mass without a plating which lowers compatibility with standard IC processes. This sensor has one support at a gravitation center for the sensor die, four cantilever beams spread symmetrically around the support and a surrounding seismic mass which is linked to the cantilever beams. The fabricated sensor has a rhombic structure with a 5 mm × 3.5 mm diagonal size. The 0.02 mV/g/V sensitivity is obtained with a beam size of 500 × 100 × 10 μm. This paper describes the structure and the fabrication process as well as the characteristics for the sensor. © 1990.