Film bulk acoustic wave resonator (fbar) having stress-relief

Abstract

An acoustic resonator structure comprises: a substrate having a cavity, which has a plurality of sides; a first electrode disposed over the cavity; a piezoelectric layer disposed over a portion of the first electrode and extending over at least one of the sides; and a second electrode disposed over the piezoelectric layer, an overlap of the first electrode, the piezoelectric layer and the second electrode forming an active area of the FBAR. The active area of the FBAR is completely suspended over the cavity.

1 . A film bulk acoustic resonator (FBAR) structure, comprising:
 a substrate comprising a cavity having a plurality of sides;   a first electrode disposed over the cavity, the first electrode extending over at least one but not all of the sides of the cavity;   a piezoelectric layer disposed over at least a portion of the first electrode, and extending over the at least one of the sides having the first electrode extending thereover; and   a second electrode disposed over the piezoelectric layer, a contacting overlap of the first electrode, the piezoelectric layer and the second electrode forming an active area of the FBAR.   
     
     
         2 . The FBAR structure of  claim 1 , wherein the active area is suspended over the cavity and does not extend over any of the sides. 
     
     
         3 . The FBAR structure of  claim 1 , wherein the second electrode extends over only one of the sides. 
     
     
         4 . The FBAR structure of  claim 3 , wherein the first electrode does not extend over the only one of the sides. 
     
     
         5 . The FBAR structure of  claim 1 , further comprising a bridge connecting the second electrode to one of the sides. 
     
     
         6 . The FBAR structure of  claim 5 , wherein a spacer is provided beneath the bridge. 
     
     
         7 . The FBAR structure of  claim 6 , wherein the spacer is filled with a non-etchable borosilicate glass (NEBSG). 
     
     
         8 . The FBAR structure of  claim 7 , wherein the spacer is filled with air. 
     
     
         9 . The FBAR structure of  claim 1 , wherein the piezoelectric layer and the first electrode each extend over the at least one side. 
     
     
         10 . The FBAR structure of  claim 9 , wherein the piezoelectric layer and the first electrode each extend over a second side. 
     
     
         11 . A film bulk acoustic resonator (FBAR) structure, comprising:
 a substrate comprising a cavity having a plurality of sides;   a first electrode disposed over the cavity;   a piezoelectric layer disposed over a portion of the first electrode and extending over at least one of the sides;   a second electrode disposed over the piezoelectric layer, a contacting overlap of the first electrode, the piezoelectric layer and the second electrode forming an active area of the FBAR, wherein the active area of the FBAR is completely suspended over the cavity.   
     
     
         12 . The FBAR structure of  claim 11 , further comprising a bridge connecting the second electrode to one of the sides. 
     
     
         13 . The FBAR structure of  claim 11 , further comprising a first and a second bridge in disposed in tandem and connecting the second electrode to one of the sides. 
     
     
         14 . The FBAR structure of  claim 12 , wherein a spacer is provided beneath the bridge. 
     
     
         15 . The FBAR structure of  claim 14 , wherein the spacer is filled with a non-etchable borosilicate glass (NEBSG). 
     
     
         16 . The FBAR structure of  claim 14 , wherein the spacer is filled with air. 
     
     
         17 . The FBAR structure of  claim 11 , wherein the first electrode extends over only two of the sides. 
     
     
         18 . The FBAR structure of  claim 17 , wherein the piezoelectric layer extends over one of the two sides. 
     
     
         19 . The FBAR structure of  claim 17 , wherein the piezoelectric layer extends over the two sides.