Laterally driven accelerometer fabricated in single crystalline silicon

The request for wireless sensor operations grows in medical and automotive applications. These sensors receive their energy and send their data by a t elemetric unit. The wireless transferred energy restricts the power consump tion of the sensor and signal processing to less than 3 mW. Therefore, the sensor has to be operated in open-loop. Furthermore, a main focus is direct ed to increase the sensitivity of the mechanical-electrical transducer. Con sidering both open-loop and sensitivity, the sensor has to be optimized by referring to the structure height. The way for realizing high structures, a s described in this paper, is the micromachining of silicon wafers with a s pecified thickness. The superior mechanical properties of single crystallin e silicon compared to electroplated metals or surface-micromachined devices confirm the use of silicon as sensor material. A laterally driven accelero meter is simulated, designed and fabricated comprising the technologies of deep reactive ion etching (DRIE) of silicon, silicon direct bonding (SDB) a nd chemical mechanical polishing (CMP). Characterization results confirm th e performance of this new technology. The open-loop sensor, which was chara cterized, had a height of 50 mu m with damping constant greater than 0.1. ( C) 2000 Elsevier Science S.A. All rights reserved.