A diaphragm based piezoelectric AlN film quality test structure

Aluminum nitride (AlN) is becoming a commonly used piezoelectric material for various applications due to its compatibility with CMOS processing. However, the piezoelectric properties of AlN are highly dependent on the deposition process and the underlying layers, and typically require several test structures in order to determine the quality of the film. This paper highlights a MEMS based diaphragm test structure which allows various types of material characterization to be tested, in order to determine the quality of the AlN film on a bulk micromachined device wafer.