| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high coupling leaky surface acoustic wave substrate in thin film structure having superior frequency temperature characteristics, and a surface acoustic wave functional element which reduces an insertion loss in a high frequency band. <P>SOLUTION: A thin film layer of an SiO<SB>2</SB>film is formed on a LiNbO<SB>3</SB>substrate and when the LiNbO3 substrate has a cut angle of rotated Y plate within a range from -10° to +30°, the thin film layer has a film thickness dimension H and a wavelength of an operating center frequency of a surface acoustic wave is defined as λ, the value of H/λ is from 0.115 to 0.31. As a result, an electromechanical coupling coefficient k<SP>2</SP>for a leaky surface acoustic wave faster than a Rayleigh type surface acoustic wave can be 0.20 or more, frequency/temperature characteristics can be settled within the range from -30 to +30 ppm/°C, thereby obtaining the functional element with the great electromechanical coupling coefficient k<SP>2</SP>and excellent frequency temperature characteristics. <P>COPYRIGHT: (C)2008,JPO&INPIT |
