Boundary acoustic wave device with multi-layer piezoelectric substrate
Aspects of this disclosure relate to a boundary acoustic wave device. The boundary acoustic wave device can include two low acoustic impedance layers, an interdigital transducer electrode, piezoelectric material positioned between the interdigital transducer electrode and each of the two low acoustic impedance layers, and two high acoustic impedance substrates. The two low acoustic impedance layers can be positioned between the two high acoustic impedance substrates. Related acoustic wave filters, multiplexers, radio frequency modules, wireless communication devices, and methods are disclosed.
1 . A boundary acoustic wave device comprising:
two low acoustic impedance layers;
an interdigital transducer electrode;
piezoelectric material on opposing sides of the interdigital transducer electrode such that the piezoelectric material is positioned between the interdigital transducer electrode and each of the two low acoustic impedance layers; and
two high acoustic impedance substrates, the two low acoustic impedance layers being positioned between the two high acoustic impedance substrates, the two low acoustic impedance layers each having a lower acoustic impedance than each of the two high acoustic impedance substrates, the two high acoustic impedance substrates each having a higher acoustic impedance than the piezoelectric material, at least one of the two high acoustic impedance substrates being a silicon substrate, and the boundary acoustic wave device being configured to generate a boundary acoustic wave.
2 . The boundary acoustic wave device of claim 1 wherein the interdigital transducer electrode is embedded in the piezoelectric material.
3 . The boundary acoustic wave device of claim 1 wherein the interdigital transducer electrode is bonded to a layer of the piezoelectric material.
4 . The boundary acoustic wave device of claim 1 further comprising dielectric material located between interdigital transducer electrode fingers of the interdigital transducer electrode.
5 . The boundary acoustic wave device of claim 1 further comprising a dielectric layer positioned between the interdigital transducer electrode and the piezoelectric material on one of the opposing sides of the interdigital transducer electrode.
6 . A boundary acoustic wave device comprising:
two low acoustic impedance layers;
an interdigital transducer electrode;
piezoelectric material on opposing sides of the interdigital transducer electrode such that the piezoelectric material is positioned between the interdigital transducer electrode and each of the two low acoustic impedance layers;
a thermally conductive layer positioned between the interdigital transducer electrode and the piezoelectric material on one of the opposing sides of the interdigital transducer electrode; and
two high acoustic impedance substrates, the two low acoustic impedance layers being positioned between the two high acoustic impedance substrates, the two low acoustic impedance layers each having a lower acoustic impedance than each of the two high acoustic impedance substrates, the two high acoustic impedance substrates each having a higher acoustic impedance than the piezoelectric material, and the boundary acoustic wave device being configured to generate a boundary acoustic wave.
7 . The boundary acoustic wave device of claim 1 wherein the boundary acoustic wave device has an electromechanical coupling coefficient in a range from 10% to 25%.
8 . The boundary acoustic wave device of claim 1 wherein the boundary acoustic wave device has a static capacitance in a range from 2.5 picofarads to 4 picofarads.
9 . The boundary acoustic wave device of claim 1 wherein the two low acoustic impedance layers include silicon dioxide.
10 . The boundary acoustic wave device of claim 1 wherein the piezoelectric material includes lithium niobate.
11 . The boundary acoustic wave device of claim 1 wherein the piezoelectric material includes lithium tantalate.
12 . A wireless communication device comprising:
an acoustic wave filter configured to filter a radio frequency signal, the acoustic wave filter including the boundary acoustic wave device of claim 1 ; and
an antenna operatively coupled to the acoustic wave filter.
13 . A boundary acoustic wave device comprising:
two low acoustic impedance layers;
an interdigital transducer electrode;
piezoelectric material on opposing sides of the interdigital transducer electrode such that the piezoelectric material is positioned between the interdigital transducer electrode and each of the two low acoustic impedance layers, the interdigital transducer electrode is in contact with the piezoelectric material on only one of the opposing sides of the interdigital transducer electrode; and
two high acoustic impedance substrates, the two low acoustic impedance layers being positioned between the two high acoustic impedance substrates, the two low acoustic impedance layers each having a lower acoustic impedance than each of the two high acoustic impedance substrates, the two high acoustic impedance substrates each having a higher acoustic impedance than the piezoelectric material, and the boundary acoustic wave device being configured to generate a boundary acoustic wave.
14 . The boundary acoustic wave device of claim 5 wherein at least one of the two high acoustic impedance substrates is a silicon substrate.
15 . The boundary acoustic wave device of claim 6 further comprising a second interdigital transducer electrode, the thermally conductive layer positioned between the interdigital transducer electrode and the second interdigital transducer electrode.
16 . A boundary acoustic wave device comprising:
two low acoustic impedance layers;
an interdigital transducer electrode;
piezoelectric material on opposing sides of the interdigital transducer electrode such that the piezoelectric material is positioned between the interdigital transducer electrode and each of the two low acoustic impedance layers; and
two high acoustic impedance substrates, the two low acoustic impedance layers being positioned between the two high acoustic impedance substrates, the two low acoustic impedance layers each having a lower acoustic impedance than each of the two high acoustic impedance substrates, the two high acoustic impedance substrates each having a higher acoustic impedance than the piezoelectric material, at least one of the two high acoustic impedance substrates is a substrate that includes at least one of synthetic diamond, quartz, or spinel, and the boundary acoustic wave device being configured to generate a boundary acoustic wave.
17 . A radio frequency module comprising:
an acoustic wave filter configured to filter a radio frequency signal, the acoustic wave filter including the boundary acoustic wave device of claim 1 ;
a radio frequency circuit element coupled to the acoustic wave filter; and
a packaging structure enclosing the acoustic wave filter and the radio frequency circuit element.
18 . The radio frequency module of claim 17 wherein the radio frequency circuit element is a radio frequency amplifier.
19 . The radio frequency module of claim 17 wherein the radio frequency circuit element is a switch.
20 . The wireless communication device of claim 12 wherein the wireless communication device is a mobile phone.