Acoustic resonator structure comprising a bridge

Abstract

An acoustic resonator comprises a first electrode a second electrode and a piezoelectric layer disposed between the first and second electrodes. The acoustic resonator further comprises a reflective element disposed beneath the first electrode, the second electrode and the piezoelectric layer. An overlap of the reflective element, the first electrode, the second electrode and the piezoelectric layer comprises an active area of the acoustic resonator. The acoustic resonator also comprises a bridge adjacent to a termination of the active area of the acoustic resonator.

1 . An acoustic resonator, comprising:
 a first electrode;   a second electrode;   a piezoelectric layer disposed between the first and second electrodes;   a reflective element disposed beneath the first electrode, the second electrode and the piezoelectric layer, an overlap of the reflective element, the first electrode, the second electrode and the piezoelectric layer defining an active area of the acoustic resonator, wherein the first electrode substantially covers the reflective element, and the piezoelectric layer extends over an edge of the first electrode; and   a bridge adjacent to a termination of the active area of the acoustic resonator, wherein the bridge overlaps a portion of the first electrode.   
     
     
         2 . An acoustic resonator as claimed in  claim 1 , further comprising an electrical connection to one of a plurality of sides of the second electrode, wherein the bridge is disposed between the connection and the one side of the second electrode. 
     
     
         3 . An acoustic resonator as claimed in  claim 1 , wherein adjacent to termination of the active area of the acoustic resonator, the piezoelectric layer comprises a transition comprising defects. 
     
     
         4 . An acoustic resonator as claimed in  claim 3 , wherein the second electrode does not contact the transition. 
     
     
         5 . An acoustic resonator as claimed in  claim 1 , wherein the bridge comprises a gap. 
     
     
         6 . An acoustic resonator as claimed in  claim 5 , wherein the gap comprises a region between the second electrode and the piezoelectric layer. 
     
     
         7 . An acoustic resonator as claimed in  claim 6 , wherein adjacent to termination of the active area of the acoustic resonator, the piezoelectric layer comprises a transition comprising defects, and the transition is disposed beneath the region of the gap. 
     
     
         8 . An acoustic resonator as claimed in  claim 1 , wherein the second electrode comprises an upper surface with a side and a recess is disposed along the side. 
     
     
         9 . An acoustic resonator as claimed in  claim 1 , wherein the second electrode comprises an upper surface with a side, and a frame element is disposed along the side. 
     
     
         10 . A film bulk acoustic resonator (FBAR), comprising:
 a first electrode;   a second electrode;   a piezoelectric layer disposed between the first and second electrodes;   a cavity disposed beneath the first electrode, the second electrode and the piezoelectric layer, an overlap of the cavity, the first electrode, the second electrode and the piezoelectric layer defining an active area of the acoustic resonator, wherein the first electrode substantially covers the cavity, and the piezoelectric layer extends over an edge of the first electrode; and   a bridge adjacent to a termination of the active area of the acoustic resonator, wherein the bridge overlaps a portion of the first electrode.   
     
     
         11 . An FBAR as claimed in  claim 10 , further comprising an electrical connection to one of a plurality of sides of the second electrode, wherein the bridge is disposed between the connection and the one side of the second electrode. 
     
     
         12 . An FBAR as claimed in  claim 10 , wherein adjacent to termination of the active area of the acoustic resonator, the piezoelectric layer comprises a transition comprising defects. 
     
     
         13 . An FBAR as claimed in  claim 12 , wherein the second electrode does not contact the transition. 
     
     
         14 . An FBAR as claimed in  claim 10 , wherein the bridge comprises a gap. 
     
     
         15 . An FBAR as claimed in  claim 14 , wherein the gap comprises a region between the second electrode and the piezoelectric layer. 
     
     
         16 . An FBAR as claimed in  claim 15 , wherein adjacent to termination of the active area of the acoustic resonator, the piezoelectric layer comprises a transition comprising defects, and the transition is disposed beneath the region of the gap. 
     
     
         17 . An FBAR as claimed in  claim 10 , wherein the second electrode comprises an upper surface with a side and a recess is disposed along the side. 
     
     
         18 . An FBAR as claimed in  claim 10 , wherein the second electrode comprises an upper surface with a side, and a frame element is disposed along the side. 
     
     
         19 . An FBAR as claimed in  claim 20 , further comprising a low acoustic impedance material beneath the bridge. 
     
     
         20 . A filter element comprising an acoustic resonator, the acoustic resonator comprising:
 a first electrode;   a second electrode;   a piezoelectric layer disposed between the first and second electrodes;   a reflective element disposed beneath the first electrode, the second electrode and the piezoelectric layer, an overlap of the reflective element, the first electrode, the second electrode and the piezoelectric layer defining an active area of the acoustic resonator, wherein the first electrode substantially covers the reflective element, and the piezoelectric layer extends over an edge of the first electrode; and   a bridge adjacent to a termination of the active area of the acoustic resonator, wherein the bridge overlaps a portion of the first electrode.   
     
     
         21 . An acoustic wave resonator, comprising:
 (a) a substrate;   (b) an acoustic mirror formed in or on the substrate, having a first edge and an opposite, second edge;   (c) a dielectric layer formed on the substrate such that the dielectric layer is substantially in contact with the first and second edges of the acoustic mirror;   (d) a first electrode formed on the acoustic mirror, having a first end portion and an opposite, second end portion defining a body portion therebetween, wherein at least one of the first and second end portions is formed extending to the dielectric layer;   (e) a piezoelectric layer formed on the first electrode, having a body portion, a first end portion and a second end portion oppositely extending from the body portion onto the dielectric layer; and   (f) a second electrode formed on the piezoelectric layer, having a first portion situated on the body portion of the piezoelectric layer, and a second portion extending from the first portion such that the junction of the first portion and the second portion locates between the first and second edges of the acoustic mirror and the second portion of the second electrode and the first end portion of the piezoelectric layer define an air gap therebetween.   
     
     
         22 . The acoustic wave resonator of  claim 21 , wherein the air gap is filled with a dielectric material. 
     
     
         23 . The acoustic wave resonator of  claim 22 , wherein the dielectric material comprises carbon (C) doped silicon dioxide (SiO 2 ), crosslinked polyphenylene polymer (SiLK), or benzocyclobutene (BCB). 
     
     
         24 . The acoustic wave resonator of  claim 21 , wherein the second portion of the second electrode comprises a convex bridge. 
     
     
         25 . The acoustic wave resonator of  claim 21 , wherein the first and second end portions of first electrode are formed to have a vertical profile. 
     
     
         26 . The acoustic wave resonator of  claim 21 , Wherein the first end portion of the first electrode extends beyond the first edge of the acoustic mirror and is situated on the dielectric layer. 
     
     
         27 . The acoustic wave resonator of  claim 26 , wherein the first edge of the acoustic mirror and the junction of the first portion and the second portion of the second electrode define a first distance, d 1 . 
     
     
         28 . The acoustic wave resonator of  claim 27 , wherein the junction of the body portion and the first end portion of the first electrode and the junction of the first portion and the second portion of the second electrode define a second distance, d 2 . 
     
     
         29 . An acoustic wave resonator, comprising:
 (a) a substrate having a top surface;   (b) an acoustic mirror formed on the top surface of the substrate or in the substrate, having a first edge and an opposite, second edge;   (c) a first electrode formed on the acoustic mirror, having a end portion;   (d) a piezoelectric layer formed on the first electrode; and   (e) a second electrode formed on the piezoelectric layer, wherein at least one of the first electrode and the second electrode and the piezoelectric layer define an air gap in a region that overlaps the end portion of the first electrode.   
     
     
         30 . The acoustic wave resonator of  claim 29 , further comprising a dielectric layer formed on the substrate such that the dielectric layer is substantially in contact with the first and second edges of the acoustic mirror. 
     
     
         31 . The acoustic wave resonator of  claim 29 , wherein the air gap is filled with a dielectric material. 
     
     
         32 . The acoustic wave resonator of  claim 31 , wherein the dielectric material comprises carbon (C) doped silicon dioxide (SiO 2 ), crosslinked polyphenylene polymer (SiLK), or benzocyclobutene (BCB).