Resonator device including electrode with buried temperature compensating layer

Abstract

An acoustic resonator device includes a composite first electrode on a substrate, a piezoelectric layer on the composite electrode, and a second electrode on the piezoelectric layer. The first electrode includes a buried temperature compensating layer having a positive temperature coefficient. The piezoelectric layer has a negative temperature coefficient, and thus the positive temperature coefficient of the temperature compensating layer offsets at least a portion of the negative temperature coefficient of the piezoelectric layer.

1 . An acoustic wave resonator, comprising:
 (a) a substrate;   (b) an acoustic reflector formed on the substrate;   (c) a bottom electrode formed on the acoustic reflector;   (d) a piezoelectric layer formed on the bottom electrode; and   (e) a composite structure formed on the piezoelectric layer, comprising: (i) a first electrode formed on the piezoelectric layer; (ii) a temperature compensation layer formed on the first electrode; and (iii) a second electrode formed on the temperature compensation layer and electrically connected to the first electrode.   
     
     
         2 . The acoustic wave resonator of claim I, wherein the temperature compensation layer has a temperature coefficient of frequency that is opposite to that of the piezoelectric layer. 
     
     
         3 . The acoustic wave resonator of  claim 1 , wherein the temperature compensation layer is formed with a material of tellurium oxide, silicon oxide, or a combination of them. 
     
     
         4 . The acoustic wave resonator of  claim 1 , wherein the temperature compensation layer is formed to have one or more vias or trenches such that the first electrode and the second electrode are electrically connected to one another through the one or more vias or trenches. 
     
     
         5 . An acoustic wave resonator, comprising:
 (a) a substrate;   (b) an acoustic reflector formed on the substrate;   (c) a composite structure formed on the acoustic reflector, comprising: (i) a first electrode formed on the acoustic reflector; (ii) a temperature compensation layer formed on the first electrode; and (iii) a second electrode formed on the temperature compensation layer and electrically connected to the first electrode;   (d) a piezoelectric layer formed on the second electrode of the composite structure; and   (e) a top electrode formed on the piezoelectric layer.   
     
     
         6 . The acoustic wave resonator of  claim 5 , wherein the temperature compensation layer has a temperature coefficient of frequency that is opposite to that of the piezoelectric layer. 
     
     
         7 . The acoustic wave resonator of  claim 5 , wherein the temperature compensation layer is formed with a material of tellurium oxide, silicon oxide, or a combination of them. 
     
     
         8 . The acoustic wave resonator of  claim 5 , wherein the temperature compensation layer is formed to have one or more vias or trenches such that the first electrode and the second electrode are electrically connected to one another through the one or more vias or trenches. 
     
     
         9 . An acoustic wave resonator, comprising a composite structure comprising:
 (a) a first electrode;   (b) a temperature compensation layer formed on the first electrode, wherein the temperature compensation layer has one or more vias or trenches formed therein; and   (c) a second electrode formed on the temperature compensation layer and electrically connected to the first electrode at least through the one or more vias or trenches of the temperature compensation layer.   
     
     
         10 . The acoustic wave resonator of  claim 1 , further comprising:
 (a) an acoustic reflector formed on a substrate;   (b) a bottom electrode formed on the acoustic reflector; and   (c) a piezoelectric layer formed on the bottom electrode, wherein t le composite structure is disposed on the piezoelectric layer.   
     
     
         11 . The acoustic wave resonator of  claim 1 , further comprising:
 (a) an acoustic reflector formed on a substrate;   (b) a piezoelectric layer formed on the composite structure that in turn, is disposed on the acoustic reflector; and   (c) a top electrode formed on the piezoelectric layer.