Study of Low-residual Stress Amorphous Film Deposition Method for LiTaO₃/Quartz or LiNbO₃/Quartz Bonding toward 5G Surface Acoustic Wave Devices

Analysis of longitudinal leaky surface acoustic waves on LiNbO3/amorphous layer/quartz structure

“…Our research group reported that, by using a 50 nm thick amorphous SiO 2 or Al 2 O 3 thin film deposited by ion beam sputtering as an middle layer, the residual stress was reduced and the bonding strength at the interface of the bonded LN/quartz structure was extremely improved. 24,25) For a such an LN/amorphous layer/quartz substrate structure, we calculated the propagation properties of an LLSAW including attenuation and K 2 , and we also simulated the Q factors in its resonance properties. 26,27) In this paper, we investigated the propagation and resonance characteristics of LLSAW on LN/amorphous layer/ quartz substrate structures theoretically in more detail.…”

“…The X31°Y-LT/X32°Y -quartz was selected for the cut angle and propagation direction of the LT thin-plate and quartz support substrate. 25) Figure 4 shows the (a) phase velocity, (b) attenuation, and (c) K 2 without and with the amorphous layer as functions of the normalized LT thin-plate thickness (h/λ). The amorphous film thickness was assumed to be the same as that in the above-mentioned structure with LN because the film thickness dependence showed the same tendency as that in the above-mentioned LN structure.…”