An accelerometer made in a two-layer surface-micromachining technology

A microaccelerometer has been fabricated in surface-micromachining technology and is designed to work in the 50g range. An important advantage of this type of sensor is that only two polysilicon layers are needed. Nevertheless, the sensor works as a differential capacitor and can also be driven in a force-balanced mode. Compared to laterally driven structures, the technological steps are less critical. The typical bandwidth of the structure is approximately 3 kHz. The overall change in capacitance is 13 fF. In order to calculate the critical damping and to reduce deformation of the mass, simulations have been carried out.