Effect of interdigital transducers structure on insertion loss of high-frequency surface acoustic wave devices

With the development of information technology, surface acoustic wave (SAW) devices are strongly required to exhibit higher integration, and lower insertion loss, as well as complementary metal oxide semiconductor (CMOS), processes compatibility. Aluminum nitride (AlN) is an excellent piezoelectric material that is compatible with CMOS processes; however, the insertion loss for AlN/Si SAW devices is high under conventional interdigital transducers (IDT) structure. In this work, AlN piezoelectric film-based floating electrode unidirectional transducers (FEUDT) structures are developed, and its propagation characteristics are simulated with the help of finite-element method (FEM). By Fourier transforming the corresponding time response, the insertion loss of the devices is calculated to be − 15.52 (forward) and − 22.94 dB (backward). According to simulation structure, FEUDT and IDT-structured devices with 3.6 μm wavelength are fabricated by electron beam lithography, and operating frequency of both devices reached 1.4 GHz, which is basically consistent with simulation results, and insertion loss of floating electrode unidirectional transducers structures is about 11 dB lower than that of conventional structure.