Fbar structure having single crystalline piezoelectric layer and fabricating method thereof

Abstract

A film bulk acoustic resonator (FBAR) structure includes a bottom cap wafer, a piezoelectric layer disposed on the bottom cap wafer, the piezoelectric layer including a single crystalline piezoelectric material, a bottom electrode disposed below the piezoelectric layer; a top electrode disposed above the piezoelectric layer; and a cavity disposed below the bottom electrode.

What is claimed is: 
     
         1 . A film bulk acoustic resonator (FBAR) structure, comprising:
 a bottom cap wafer;   a piezoelectric layer disposed on the bottom cap wafer, the piezoelectric layer including a single crystalline piezoelectric material;   a bottom electrode disposed below the piezoelectric layer;   a top electrode disposed above the piezoelectric layer; and   a cavity disposed below the bottom electrode.   
     
     
         2 . The FBAR structure of  claim 1 , wherein the single crystalline piezoelectric material has a crystallinity of less than 0.5 degrees at Full Width Half Maximum (FWHM) measured using X-ray diffraction (XRD). 
     
     
         3 . The FBAR structure of  claim 1 , wherein the single crystalline piezoelectric material includes aluminum nitride (AlN), aluminum nitride doped with scandium (ScAlN), zinc oxide (ZnO), or lead zirconate titanate (PZT). 
     
     
         4 . The FBAR structure of  claim 1 , further comprising:
 a first insulating layer disposed below the cavity;   a second insulating layer disposed above the bottom cap wafer; and   a metal bonding layer bonding the first insulating layer with the second insulating layer.   
     
     
         5 . The FBAR structure of  claim 4 , wherein the metal bonding layer includes at least a first metal bonding layer and a second metal bonding layer. 
     
     
         6 . The FBAR structure of  claim 5 , wherein a combination of materials of the first metal bonding layer and the second metal bonding layer is selected from a group of gold-gold (Au—Au), aluminum-copper (Al—Cu), copper-copper (Cu—Cu), gold-silver (Au—Ag), copper-tin (Cu—Sn), aluminum-germanium (Al—Ge), gold-silicon (Au—Si), gold-germanium (Au—Ge), gold-tin (Au—Sn), copper-tin (Cu—Sn), and gold-indium (Au—In). 
     
     
         7 . The FBAR structure of  claim 4 , further comprising a ground contact layer electrically connecting the metal bonding layer to ground. 
     
     
         8 . The FBAR structure of  claim 7 , further comprising a ground contact window formed in the first insulating layer and the piezoelectric layer, and exposing the metal bonding layer,
 wherein the ground contact layer is electrically connected to the metal bonding layer via the ground contact window.   
     
     
         9 . The FBAR structure of  claim 4 , wherein the first insulating layer and the second insulating layer include silicon oxide (SiO 2 ) or silicon carbide (SiC). 
     
     
         10 . The FBAR structure of  claim 1 , further comprising:
 a top passivation layer disposed above the top electrode; and   a bottom passivation layer disposed below the bottom electrode.   
     
     
         11 . The FBAR structure of  claim 10 , wherein the top passivation layer and the bottom passivation layer include silicon nitride (SiN) or aluminum nitride (AlN). 
     
     
         12 . The FBAR structure of  claim 1 , further comprising a boundary layer surrounding the cavity. 
     
     
         13 . The FBAR structure of  claim 12 , wherein the boundary layer includes silicon (Si), silicon nitride (SiN), aluminum nitride (AlN), polysilicon, amorphous silicon, or a stacked combination of two or more of those materials. 
     
     
         14 . The FBAR structure of  claim 1 , further comprising:
 a bottom electrode contact layer electrically connected with the bottom electrode; and   a top electrode contact layer electrically connected with the top electrode.   
     
     
         15 . The FBAR structure of  claim 14 , further comprising:
 a bottom electrode contact window formed in the piezoelectric layer and exposing the bottom electrode,   wherein the bottom electrode contact layer is electrically connected with the bottom electrode via the bottom electrode contact window.   
     
     
         16 . The FBAR structure of  claim 14 , wherein each one of the bottom electrode contact layer and the top electrode contact layer includes aluminum (Al), copper (Cu), gold (Au), titanium (Ti), tungsten (W), platinum (Pt), or a stacked combination of two or more of those materials. 
     
     
         17 . The FBAR structure of  claim 1 , wherein each one of the top electrode and the bottom electrode includes molybdenum (Mo), aluminum (Al), copper (Cu), platinum (Pt), tantalum (Ta), tungsten (W), palladium (Pd), ruthenium (Ru), or a stacked combination of two or more of those materials. 
     
     
         18 . The FBAR structure of  claim 1 , wherein the bottom cap wafer includes silicon (Si), silicon carbide (SiC), sapphire (Al 2 O 3 ), or a stacked combination of two or more of those materials. 
     
     
         19 . The FBAR structure of  claim 1 , wherein a projection of at least one edge of the top electrode is located within the cavity. 
     
     
         20 . The FBAR structure of  claim 1 , wherein a projection of at least one side of the bottom electrode is located within the cavity.