A silicon accelerometer is designed for possible use in an automotive airbag system, and fabricated by using micromachining technology. Design specification and dimension are determined considering existing products and literature. A cantilever type is chosen because its characteristics of good sensitivity. A piezoresistive circuit is adopted for signal generation and diagnostic purposes.
An optimum design is obtained to maximize the sensitivity under various mechanical constraints on damping ratio, natural frequency, maximum allowable displacement and stress, and transverse sensitivity. It is then fabricated by using suitable micromachining processes. The dimensional difference occurred between the prototype and the design is discussed, and the measured characteristics compared with the analysis results. Significant difference is found existing. The resulting performance, however, has indicated that the design goal can be achieved with some design modifications and suitable tuning of the fabrication processes.
