Withdrawal Weighting Image-Impedance Connected SAW Filters with Al-Mo Alloy Electrodes

摘要

To obtain high reliability of surface acoustic wave (SAW) devices, Mo was added to Al electrodes on 128° Y-X LiNbO_3 substrates by a d.c. magnetron sputtering deposition. Influence of Mo additive on the mechanical properties of Al films was investigated. It was found that the Al-Mo alloy films displayed a superior adhesion to substrates. With the Al-Mo alloy films, a 1.65 GHz-range image-impedance connected SAW filter was designed and fabricated. In this structure of SAW filter, for satisfying stopband requirements a dual-track structure was applied. Withdrawal weighting of interdigital transducers (IDT) was used to adjust the bandwidth of SAW filter.