Bulk acoustic wave resonator having a plurality of compensation layers and duplexer using same

Abstract

A bulk acoustic wave resonator (BAWR) includes a bulk acoustic resonance unit and at least one compensation layer. The bulk acoustic resonance unit includes a first electrode, a second electrode, and a piezoelectric layer disposed between the first electrode and the second electrode. The first electrode, the second electrode, and the piezoelectric layer each include a material that modifies a resonance frequency based on a temperature, and the at least one compensation layer includes a material that adjusts the resonance frequency modified based on the temperature in a direction opposite to a direction of the modification.

What is claimed is: 
     
         1 . A film bulk acoustic wave resonator (BAWR) comprising:
 a substrate;   a bulk acoustic resonance unit comprising a first electrode, a second electrode, and a piezoelectric layer disposed between the first electrode and the second electrode;   a first compensation layer disposed above the bulk acoustic resonance unit; and   a property compensation layer disposed above the first compensation layer,   wherein the property compensation layer is disposed above the edges of a surface of the compensation layer so that a remaining portion of the surface between the edges is not covered by the property compensation layer.   
     
     
         2 . The BAWR of  claim 1 , wherein the first compensation layer adjusts a temperature coefficient of the bulk acoustic wave resonance unit. 
     
     
         3 . The BAWR of  claim 1 , wherein the first compensation layer comprises a silicon oxide-based material, a silicon nitride-based material, silicon oxide doped with an impurity, or silicon nitride doped with the impurity. 
     
     
         4 . The BAWR of  claim 3 , wherein the impurity comprises at least one element selected from the group consisting of arsenic (As), antimony (Sb), phosphorus (P), boron (B), germanium (Ge), silicon (Si), and aluminum (Al.). 
     
     
         5 . The BAWR of  claim 1 , further comprising:
 a second compensation layer disposed below the second electrode   
     
     
         6 . A duplexer comprising:
 a phase shifter configured to shift a phase of a received signal, and output the phase-shifted received signal; and   a filter configured to filter the phase-shifted received signal output from the phase shifter, and output the filtered phase-shifted received signal to a receive output of the duplexer;   wherein the filter comprises a film bulk acoustic source resonator comprising:   a first electrode,   a second electrode,   a piezoelectric layer disposed between the first electrode and the second electrode,   a compensation layer disposed above the bulk acoustic resonance unit, and   a property compensation layer disposed above the compensation layer, wherein the property compensation layer is disposed above the edges of a surface of the compensation layer so that a remaining portion of the surface between the edges is not covered by the property compensation layer.