Frequency response study of surface acoustic wave devices with SiO _x N _y film using LiTaO₃ substrate

Abstract

In an attempt to suppress the frequency variation of a surface acoustic wave device caused by dielectric film deposition on an interdigital transducer (IDT) electrode, we fabricated a one-port resonator and examined the correlation with frequency response and refractive index when a SiOxNy film is deposited. Our data showed that the resonator frequency changes as the refractive index of the SiOxNy film changes. We also found that the frequency drift caused by the SiOxNy deposition can be suppressed if the refractive index is kept in a certain range. Then, we performed a finite element method spectral domain analysis to calculate frequency response using the Young’s modulus obtained in this experiment. The calculated frequency response indicated that the refractive index of the SiOxNy film needs to be altered in accordance with the IDT electrode thickness. We suggest that one of the effective ways of controlling the frequency response is to manage the refractive index of SiOxNy.

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

“…Many studies have been conducted on the usual SAW propagation modes including Rayleigh-type SAWs (R-SAWs) and leaky SAWs (LSAWs) used for SAW filters. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] For example, an "incredible high performance SAW resonator" with a large Q factor and a small TCF for an LSAW has been reported, which has a structure composed of LiTaO 3 (LT), aluminum nitride (AlN), and SiO 2 thin films. 9) A "hetero acoustic layer SAW device" with a wide fractional bandwidth and large impedance ratio has also reported for LSAWs, 10) Moreover, temperature-compensated SAW filters with an LT substrate bonded to a sapphire support substrate to realize a highly stable TCF for an LSAW have achieved practical use.…”

Longitudinal leaky surface acoustic wave with low attenuation on LiTaO3 or LiNbO3 thin plate bonded to quartz substrate

“…For these reasons, SAW propagation modes have been studied by focusing on the material and on substrate structures with various combinations of materials. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] For example, towards realizing a highly stable TCF for an LSAW, temperature-compensated SAW filters with an LT substrate bonded to a sapphire support substrate have achieved practical use. 21) Recently, an "incredible high-performance SAW (I.H.P.…”

Zero temperature coefficient of sound velocity in vitreous silicon oxynitride thin films

“…We synthesized v-SiO x N y films on (100) Si substrates by a reactive sputtering method with a Si target under an Ar/N 2 /O 2 atmosphere. 18 We controlled the composition by changing the flow rates of Ar, N 2 , and O 2 gases; it was determined by the X-ray photoelectron spectroscopy (XPS) method as follows: The binding energy of the Si(2p) bond changes with the content ratios of N and O between 101 and 103 eV, 19 and we determined the content ratios of O and N to Si from the spectrum-area ratios of O(1s) and N(1s) to Si(2p), respectively (Fig. S1 in the supplementary material).…”