This paper presents the first design and demonstration of a novel inverse acoustic band gap (IABG) structure in aluminum nitride (AlN) and its direct integration with contour-mode wideband transducers in the Very High Frequency (VHF) range. This design implements an efficient approach to co-fabricate in-plane AlN electro-acoustic transducers with bulk acoustic waves (BAWs) IABG arrays (10x10). The IABG unit cell consists of a cylindrical high acoustic velocity (V) media, which is held by four thin tethers, surrounded by a low acoustic velocity matrix (air). The center media is formed by 2-μm-thick AlN, which is sandwiched by 200-nm-thick top and bottom platinum (Pt) layers. The experimental results indicate that the designed IABG has a stop band from 185 MHz to 240 MHz and is centered at 218 MHz in the Γ-Χ direction. This demonstration not only confirms the existence of the frequency band gap in the IABG structure, but also opens possibilities for the integration of ABG structures with RF MEMS devices.
Date of this Version
2009 Joint Meeting of the European Frequency and Time Forum and the IEEE International Frequency Control Symposium (EFTF-IFCS 2009)
Date Posted: 13 July 2010