Currently;
some duplexers are required to have a good temperature coefficient of frequency (TCF). An Al electrodes/36-48° YX-LiTaO3 substrate;
which is used for most surface acoustic wave (SAW) duplexers;
does not have a good TCF. Its TCF can be improved by depositing a SiO2 film with a positive TCF on a transversal SAW filter consisting of a substrate with a negative TCF such as LiTaO3 and LiNbO3. However;
resonator-type SAW devices combining a SiO2 film;
Al electrodes;
and a LiTaO3 substrate do not show good frequency characteristics because of their small reflection coefficient and so on. It is considered as a countermeasure that a resonator using the reflection of a shear horizontal (SH) wave at substrate edges will show good frequency characteristics because its reflection coefficient is very large regardless of the Al electrode and SiO 2 films thicknesses. It has been difficult to obtain a high-frequency edge reflection resonator using ordinary machining techniques because it requires extremely fine substrate edges. However;
a high-frequency edge reflection resonator with a good TCF and excellent frequency characteristics has been realized using our newly developed method of obtaining fine edges. © 2007 The Japan Society of Applied Physics;