High Q SAW resonator using upper-electrodes on grooved-electrodes in LiTaO3

Al-electrodes on 36-48°YX-LiTaO₃ substrates have been widely used in surface acoustic wave (SAW) filters and SAW duplexers because of having an optimum electro-mechanical coupling factor, reflection coefficient and good Q-factor. In this paper, authors proposed and constructed a new SAW structure composed of upper Al-electrodes accumulated on lower grooved Cu-electrodes in the LiTaO₃ substrate, which has approximately same electro-mechanical coupling factor and reflection coefficient as the Al-electrodes (0.1λ)/36-48°YX-LiTaO₃ in order to realize high Q-factor. As the result, the SAW resonator having superior Q-factor was realized compared with that of Al-electrodes( 0.1λ)/42°YX-LiTaO₃ substrates.