| 摘要 |
PROBLEM TO BE SOLVED: To obtain the surface acoustic wave device with a desired characteristic without fine-adjustment of an electrode structure by forming an acoustic velocity adjustment film for a surface acoustic wave onto a substrate with the thickness that changes depending on each part of the substrate (including zero thickness). SOLUTION: In the case of employing a substrate of 45 deg. X-Z cut lithium tetrabolate (LBO substrate) for each interdigital electrode being a component of a multi-electrode configuration surface acoustic wave filter, to form the interdigital electrode being a component of the filter whose center frequency is, e.g. 214MHz on the substrate, an inter-electrode pitch dp , an electrode width dm and an inter-electrode gap dg are selected respectively to be 16μm, 4μm and 4μm. As a method to adjust the center frequency of the interdigital electrode being the multi-electrode configuration surface acoustic wave filter, a multi-layer structure using an SiO2 film is adopted for the surface acoustic wave filter with the interdigital electrodes formed thereon and the SiO2 film thickness is to be adjusted. Thus, the acoustic velocity adjustment film is formed on the substrate with the thickness that changes depending on each part of the substrate (including zero thickness).
|
