Dielectric layer in acoustic wave device for electro-mechanical de-coupling

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 that is positioned partially between the piezoelectric layer and the interdigital transducer electrode. The dielectric layer that is positioned so as to partially electro-mechanically de-couple the piezoelectric layer from the interdigital transducer electrode.

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 partially between the piezoelectric layer and the interdigital transducer electrode so as to partially electro-mechanically de-couple the piezoelectric layer from the interdigital transducer electrode, the acoustic wave device configured to generate an acoustic wave.   
     
     
         2 . The acoustic wave device of  claim 1  wherein the dielectric layer is 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. 
     
     
         3 . The acoustic wave device of  claim 1  wherein a second area between the piezoelectric layer and the interdigital transducer electrode being free from the dielectric layer. 
     
     
         4 . The acoustic wave device of  claim 3  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. 
     
     
         5 . The acoustic wave device of  claim 4  wherein the dielectric layer is positioned under the edge region and the gap region. 
     
     
         6 . The acoustic wave device of  claim 4  wherein the dielectric layer is positioned under a location at or near an interface between the edge region and the gap region. 
     
     
         7 . The acoustic wave device of  claim 4  wherein the acoustic wave has a wavelength of L, and the edge region is a region within 0.5L to 1.2L into the active region from the gap region. 
     
     
         8 . The acoustic wave device of  claim 4  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. 
     
     
         9 . The acoustic wave device of  claim 4  further comprising a mini bus bar in the gap region. 
     
     
         10 . 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. 
     
     
         11 . The acoustic wave device of  claim 1  wherein the dielectric layer includes silicon dioxide. 
     
     
         12 . 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. 
     
     
         13 . The acoustic wave device of  claim 1  wherein a shear horizontal mode is a main mode of the surface wave device. 
     
     
         14 . The acoustic wave device of  claim 1  wherein a Rayleigh mode is a main mode of the surface wave device. 
     
     
         15 . 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 0.005L to 0.02L. 
     
     
         16 . 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. 
     
     
         17 . An acoustic wave device comprising:
 a piezoelectric layer;   a dielectric layer partially on the piezoelectric layer;   an interdigital transducer electrode including an active region having 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 disposed directly on the piezoelectric layer and at least a portion of the edge region disposed directly on the dielectric layer so as to electro-mechanically de-couple the piezoelectric layer from the portion of the edge region of the interdigital transducer electrode; and   a temperature compensation layer over the interdigital transducer electrode, the acoustic wave device configured to generate an acoustic wave.   
     
     
         18 . The acoustic wave device of  claim 17  wherein the dielectric layer is positioned under the edge region and the gap region. 
     
     
         19 . The acoustic wave device of  claim 17  wherein the dielectric layer is positioned under a location at or near an interface between the edge region and the gap region. 
     
     
         20 . The acoustic wave device of  claim 17  wherein the acoustic wave has a wavelength of L, and the edge region is a region within 0.5L to 1.2L into the active region from the gap region.