Piezoelectric Scanning Micromirror With Built-In Sensors Based on Thin Film Aluminum Nitride

Abstract

A micromirror with piezoelectric thin film aluminum nitride (AIN) as transducer material for actuation and detection is presented. Four sensor elements are integrated for closed-loop monitoring of the resonant driven microscanner with an entire footprint of 6 mm2. The sensor and actuator elements are monolithically fabricated in 150 mm SOI technology. The micromirror is characterized in terms of its scanning and sensor characteristics. A large optical scan angle of 137.9° (34.5° mechanical tilt angle corresponding) at 3385 Hz and 20 V actuation voltage is achieved. The median resonant voltage sensitivity is 4.7 °/V. For the sensor characterization, a cross-talk compensation is introduced, which significantly improves the signal quality and thus enables an accurate charge determination. The sensor signal increases linearly to the deflection. A dynamic sensor angle sensitivity of 48.4 fC/° is reached. Possible applications of the micromirror are consumer electronics, such as LIDAR or medical applications, such as fluorescence microscopy.