Smart ultrasonic sensors systems: investigations on aluminum nitride thin films for the excitation of high frequency ultrasound

摘要: Aluminum nitride is a promising material for the use as piezoelectric sensor resonance frequencies higher than 50 MHz and contains potential high frequency phased array application in future. This work represents the fundamental research on aluminum films with thickness of up to 10 μm based double ring magnetron sputtering process. The deposition process thin film layers silicon substrates was investigated optimized regarding their behavior. Therefore specific test setup measuring station were created to characterize sensors. Large single element transducers deposited aluminum electrodes, using different parameters magnetron sputter process, like pressure bias voltage. Afterwards acoustical measurements carried out pulse echo mode 500 charge constants (d 33 ) were determined. As result, two parameter sets found obtain an excellent piezoelectric constant about 7.2 pC/N maximum.