P1H-5 Uniformity Optimization of the Electromechanical Coupling Coefficient in AlN Based Bulk Acoustic Wave Resonators

High yield bulk acoustic wave (BAW) device manufacturing is a challenge: properties of all films in a complex film stack need to be optimized. The commonly used piezoelectric AIN is one of the central films. Key parameters for this film are best possible uniformity of following physical parameters: acoustic thickness, electromechanical coupling coefficient and mechanical quality factor. This paper investigates possible causes for observed non-uniformity of the coupling coefficient. Such non-uniformities reduce the production yield in BAW volume manufacturing.