Acoustic wave device with dielectric layer for transverse leakage suppression

Abstract

An acoustic wave device is disclosed. The acoustic wave device can include a piezoelectric layer, an interdigital transducer electrode over the piezoelectric layer, a temperature compensation layer over the interdigital transducer electrode, and a dielectric layer positioned partially between the piezoelectric layer and the interdigital transducer electrode. The interdigital transducer electrode includes an active region that has a center region and an edge region, a bus bar, and a gap region between the active region and the bus bar. At least a portion of the center region is in direct contact with the piezoelectric layer.

What is claimed is: 
     
         1 . An acoustic wave device comprising:
 a piezoelectric layer;   an interdigital transducer electrode over the piezoelectric layer;   a temperature compensation layer over the interdigital transducer electrode; and   a dielectric layer positioned in a first area between the piezoelectric layer and the interdigital transducer electrode so as to suppress transverse leakage of acoustic energy generated by the acoustic wave device, a second area between the piezoelectric layer and the interdigital transducer electrode being free from the dielectric layer, and the acoustic wave device configured to generate an acoustic wave.   
     
     
         2 . The acoustic wave device of  claim 1  wherein the interdigital transducer electrode includes an active region that has a center region and an edge region, a bus bar, and a gap region between the active region and the bus bar, at least a portion of the center region corresponds to the second area. 
     
     
         3 . The acoustic wave device of  claim 2  wherein the dielectric layer is positioned under the edge region and the gap region. 
     
     
         4 . The acoustic wave device of  claim 2  wherein the dielectric layer is positioned under a location at or near an interface between the edge region and the gap region. 
     
     
         5 . The acoustic wave device of  claim 2  wherein the acoustic wave has a wavelength of L, and the edge region is a region within 0.5 L to 1.2 L into the active region from the gap region. 
     
     
         6 . The acoustic wave device of  claim 2  wherein the interdigital transducer electrode has a hammer head shape that has a finger width at the edge region greater than a finger width at the center region. 
     
     
         7 . The acoustic wave device of  claim 2  further comprising a mini bus bar in the gap region. 
     
     
         8 . The acoustic wave device of  claim 1  wherein a material of the temperature compensation layer and a material of the dielectric layer are the same. 
     
     
         9 . The acoustic wave device of  claim 1  wherein the dielectric layer includes silicon dioxide. 
     
     
         10 . The acoustic wave device of  claim 1  wherein the piezoelectric layer is a lithium niobate layer having a cut angle in a range of −20° YX to 25° YX. 
     
     
         11 . The acoustic wave device of  claim 1  wherein a shear horizontal mode is a main mode of the surface wave device. 
     
     
         12 . The acoustic wave device of  claim 1  wherein a Rayleigh mode is a main mode of the surface wave device. 
     
     
         13 . The acoustic wave device of  claim 1  wherein the surface acoustic wave has a wavelength of L, and the dielectric layer has a thickness in a range from 0.005 L to 0.02 L. 
     
     
         14 . The acoustic wave device of  claim 1  further comprising a piston mode structure configured to suppress a transverse mode of the acoustic wave generated by the surface acoustic wave device. 
     
     
         15 . A surface acoustic wave device comprising:
 a lithium niobate layer having a cut angle in a range of −20° YX to 25° YX;   an interdigital transducer electrode over the piezoelectric layer;   a temperature compensation layer over the interdigital transducer electrode; and   a dielectric layer positioned in a first area between the piezoelectric layer and a first region of the interdigital transducer electrode so as to suppress transverse leakage of acoustic energy generated by the surface acoustic wave device and maintaining a coupling factor of an acoustic wave generated by the surface acoustic wave.   
     
     
         16 . The surface acoustic wave device of  claim 15  wherein the interdigital transducer electrode includes an active region that has a center region and an edge region, a bus bar, and a gap region between the active region and the bus bar, a portion between the center region and the piezoelectric layer is free from the dielectric layer. 
     
     
         17 . The surface acoustic wave device of  claim 16  wherein a portion between the bus bar and the piezoelectric layer is free from the dielectric layer. 
     
     
         18 . The surface acoustic wave device of  claim 15  wherein the surface acoustic wave has a wavelength of L, and the dielectric layer has a thickness in a range from 0.005 L to 0.02 L. 
     
     
         19 . The surface acoustic wave device of  claim 15  further comprising a piston mode structure to suppress a transverse mode of the acoustic wave generated by the surface acoustic wave device. 
     
     
         20 . A packaged module including a substrate supporting at least one filter, the at least one filter including at least one acoustic wave device of  claim 15 , the packaged module is a radio frequency front end module or a diversity receive module.