Abstract: The present disclosure provides a preparation method for the composite substrate, wherein the preparation method includes: performing first bonding between a first wafer and a second wafer, and performing a first thinning treatment on the second wafer to obtain a composite wafer; and performing second bonding between one side of the second wafer of the composite wafer and a piezoelectric wafer, and performing a second thinning treatment on the piezoelectric wafer to obtain the composite substrate. At most three single crystal layers can be realized by the preparation method for the composite substrate and the composite substrate. By using the anisotropy regulation for each layer of material, the more plentiful and more accurate performance regulation can be realized, so as to solve the problems that cannot be solved in the prior composite substrate, so that the device performance can be further improved.

Abstract: Disclosed are methods of preparing a Surface Acoustic Wave (SAW) device, comprising: sequentially depositing a Cu electrode, a silicon oxide film, modifying the surface of the silicon oxide film, and then depositing a piezoelectric film, and an Al electrode on a substrate having an interdigital (IDT) electrode pattern to obtain the SAW device. In some embodiments, the Cu and Al electrodes both have IDT electrode patterns corresponding to the IDT pattern of the substrate. Because the Sezawa wave mode that is adopted is formed by coupling film thickness vibration and transverse vibration, the present invention is characterized in that a longitudinal electric field and a transverse electric field are excited through the double-layer electrodes whereby the electromechanical coupling coefficient of the SAW device can be improved by changing the coupling pattern between the electric fields and the piezoelectric film.

Abstract: A surface acoustic wave (SAW) device having a high electromechanical coupling coefficient based on double-layer electrodes and a preparation method thereof. A structure of the SAW device includes a Cu electrode, a piezoelectric film and an Al electrode on a substrate in sequence. A signal terminal of the Cu electrode is opposite to a ground terminal of the Al electrode. A ground terminal of the Cu electrode is opposite to a signal terminal of the Al electrode. Since Sezawa wave mode that is adopted is formed by coupling film thickness vibration and transverse vibration, a longitudinal electric field (in a direction of thickness of a film) and a transverse electric field (in a propagation direction of SAW) are excited through the double-layer electrodes so that the electromechanical coupling coefficient of the SAW device is improved by changing a coupling pattern between the electric fields and the piezoelectric film.