Bulk acoustic wave device with stacked piezoelectric layers

Abstract

Aspects of this disclosure relate to a bulk acoustic wave device with a plurality of piezoelectric layers having at least one polarization inversion. The bulk acoustic wave device can include a plurality of stacked piezoelectric layers. The plurality of stacked piezoelectric layers can include a piezoelectric layer formed by atomic layer deposition. The bulk acoustic wave device can excite an overtone mode as a main mode. Related filters, multiplexers, packaged radio frequency modules, radio frequency front ends, wireless communication devices, and methods are disclosed.

What is claimed is: 
     
         1 . A bulk acoustic wave device with stacked piezoelectric layers, the bulk acoustic wave device comprising:
 a first electrode;   a second electrode; and   a plurality of stacked piezoelectric layers positioned between the first electrode and the second electrode, the plurality of stacked piezoelectric layers including a piezoelectric layer formed by atomic layer deposition, the bulk acoustic wave device configured to excite an overtone mode as a main mode.   
     
     
         2 . The bulk acoustic wave device of  claim 1  wherein the plurality of stacked piezoelectric layers includes a piezoelectric layer formed by sputtering that is directly over the piezoelectric layer formed by atomic layer deposition, and the piezoelectric layer formed by sputtering has a same polarization as the piezoelectric layer formed by atomic layer deposition. 
     
     
         3 . The bulk acoustic wave device of  claim 1  wherein the plurality of stacked piezoelectric layers includes a piezoelectric layer formed by sputtering that is directly under the piezoelectric layer formed by atomic layer deposition, and the piezoelectric layer formed by sputtering has an opposite polarization as the piezoelectric layer formed by atomic layer deposition. 
     
     
         4 . The bulk acoustic wave device of  claim 1  wherein the plurality of stacked piezoelectric layers includes a second piezoelectric layer formed by atomic layer deposition. 
     
     
         5 . The bulk acoustic wave device of  claim 1  wherein the plurality of stacked piezoelectric layers includes alternating piezoelectric layers formed by atomic layer deposition and piezoelectric layers formed by a method different than atomic layer deposition. 
     
     
         6 . The bulk acoustic wave device of  claim 5  wherein at least one of the piezoelectric layers formed by the method different than atomic layer deposition includes a dopant. 
     
     
         7 . The bulk acoustic wave device of  claim 5  wherein each of the piezoelectric layers formed by the method different than atomic layer deposition includes a dopant. 
     
     
         8 . The bulk acoustic wave device of  claim 6  wherein the dopant is scandium. 
     
     
         9 . The bulk acoustic wave device of  claim 1  wherein the plurality of stacked piezoelectric layers includes a doped piezoelectric layer, and the piezoelectric layer formed by atomic layer deposition is undoped. 
     
     
         10 . The bulk acoustic wave device of  claim 1  wherein each of the plurality of stacked piezoelectric layers includes aluminum nitride. 
     
     
         11 . The bulk acoustic wave device of  claim 1  wherein the overtone mode has a frequency in a range from 10 gigahertz to 40 gigahertz. 
     
     
         12 . The bulk acoustic wave device of  claim 1  wherein the overtone mode has a frequency in a range from 20 gigahertz to 30 gigahertz. 
     
     
         13 . The bulk acoustic wave device of  claim 1  wherein the overtone mode has a frequency in a range from 24 gigahertz to 30 gigahertz. 
     
     
         14 . The bulk acoustic wave device of  claim 1  wherein the overtone mode has a frequency in a range from 10 gigahertz to 20 gigahertz. 
     
     
         15 . The bulk acoustic wave device of  claim 1  further comprising an interposer layer positioned between the piezoelectric layer formed by atomic layer deposition and another one of the plurality of stacked piezoelectric layers. 
     
     
         16 . A packaged radio frequency module comprising:
 an acoustic wave filter configured to filter a radio frequency signal, the acoustic wave filter including bulk acoustic wave resonator, the bulk acoustic wave resonator including a plurality of stacked piezoelectric layers, the plurality of stacked piezoelectric layers including a piezoelectric layer formed by atomic layer deposition, and the bulk acoustic wave resonator configured to excite an overtone mode as a main mode;   a radio frequency circuit element; and   a package structure enclosing the acoustic wave filter and the radio frequency circuit element.   
     
     
         17 . The packaged radio frequency module of  claim 16  wherein the overtone mode has a frequency in a range from 10 gigahertz to 40 gigahertz. 
     
     
         18 . The packaged radio frequency module of  claim 16  wherein the radio frequency circuit element includes a radio frequency switch. 
     
     
         19 . The packaged radio frequency module of  claim 16  wherein the radio frequency circuit element includes a radio frequency amplifier. 
     
     
         20 . A method of filtering a radio frequency signal, the method comprising:
 receiving a radio frequency signal at an acoustic wave filter that includes a bulk acoustic wave resonator, the bulk acoustic wave resonator including a plurality of stacked piezoelectric layers, the plurality of stacked piezoelectric layers including a piezoelectric layer formed by atomic layer deposition, and the bulk acoustic wave resonator configured to excite an overtone mode as a main mode; and   filtering the radio frequency signal with the acoustic wave filter.