Piezoelectric acoustic resonator manufactured with piezoelectric thin film transfer process

Abstract

A method and structure for a transfer process for an acoustic resonator device. In an example, a bulk acoustic wave resonator (BAWR) with an air reflection cavity is formed. A piezoelectric thin film is grown on a crystalline substrate. A first patterned electrode is deposited on the surface of the piezoelectric film. An etched sacrificial layer is deposited over the first electrode and a planarized support layer is deposited over the sacrificial layer, which is then bonded to a substrate wafer. The crystalline substrate is removed and a second patterned electrode is deposited over a second surface of the film. The sacrificial layer is etched to release the air reflection cavity. Also, a cavity can instead be etched into the support layer prior to bonding with the substrate wafer. Alternatively, a reflector structure can be deposited on the first electrode, replacing the cavity.

What is claimed is: 
     
         1 . An acoustic resonator device comprising:
 a substrate;   a support layer overlying the substrate, the support layer having an air cavity;   a first electrode overlying the air cavity and a portion of the support layer;   a first passivation layer overlying the support layer and being physically coupled to the first electrode;   a piezoelectric film overlying the support layer, the first electrode, and the air cavity, the piezoelectric film having an electrode contact via;   a second electrode formed overlying the piezoelectric film; and   a top metal formed overlying the piezoelectric film, the top metal being physically coupled to the first electrode through the electrode contact via.   
     
     
         2 . The device of  claim 1  wherein the substrate includes silicon (S), silicon carbide (SiC), sapphire (Al 2 O 3 ), silicon dioxide (SiO 2 ), or other silicon materials. 
     
     
         3 . The device of  claim 1  wherein the piezoelectric film is a single crystal or polycrystalline piezoelectric film that includes aluminum nitride (AlN), gallium nitride (GaN), Al x Ga 1-x N alloys, or other epitaxial materials. 
     
     
         4 . The device of  claim 1  wherein the piezoelectric film is an upper portion of a polycrystalline piezoelectric film that includes aluminum nitride (AlN), gallium nitride (GaN), Al x Ga 1-x N alloys, or other polycrystalline epitaxial materials. 
     
     
         5 . The device of  claim 1  wherein the piezoelectric layer has a thickness ranging from 0.15 um to 0.55 um. 
     
     
         6 . The device of  claim 1  wherein the first electrode, second electrode, and top metal can include molybdenum (Mo), ruthenium (Ru), tungsten (W), or other conductive materials. 
     
     
         7 . The device of  claim 1  wherein the first electrode or the second electrode includes an electrode cavity. 
     
     
         8 . The device of  claim 1  wherein the support layer includes silicon dioxide (SiO 2 ) or other silicon materials. 
     
     
         9 . The device of  claim 1  wherein the first electrode or the second electrode includes an energy confinement structure. 
     
     
         10 . The device of  claim 9  wherein the first electrode, the piezoelectric film, and the second electrode form a resonator area; and
 wherein the energy confinement structure is configured surrounding the resonator area. 
 
     
     
         11 . An acoustic resonator device comprising:
 a substrate;   a support layer overlying the substrate;   a reflector structure overlying the support layer, wherein the reflector structure includes at least a pair of layers having a low acoustic impedance layer and a high acoustic impedance layer;   a first electrode overlying the reflector structure and a portion of the support layer;   a piezoelectric film overlying the support layer, the first electrode, and the reflector structure, the piezoelectric film having an electrode contact via;   a second electrode formed overlying the piezoelectric film; and   a top metal formed overlying the piezoelectric film, the top metal being physically coupled to the first electrode through the electrode contact via.   
     
     
         12 . The device of  claim 11  wherein the substrate includes silicon (S), silicon carbide (SiC), sapphire (Al 2 O 3 ), silicon dioxide (SiO 2 ), or other silicon materials. 
     
     
         13 . The device of  claim 11  wherein the piezoelectric film is a single crystal or polycrystalline piezoelectric film that includes aluminum nitride (AlN), gallium nitride (GaN), Al x Ga 1-x N alloys, or other epitaxial materials. 
     
     
         14 . The device of  claim 11  wherein the piezoelectric film is an upper portion of a polycrystalline piezoelectric film that includes aluminum nitride (AlN), gallium nitride (GaN), Al x Ga 1-x N alloys, or other polycrystalline epitaxial materials. 
     
     
         15 . The device of  claim 11  wherein the piezoelectric layer has a thickness ranging from 0.15 um to 0.55 um. 
     
     
         16 . The device of  claim 11  wherein the first electrode, second electrode, and top metal can include molybdenum (Mo), ruthenium (Ru), tungsten (W), or other conductive materials. 
     
     
         17 . The device of  claim 11  wherein the first electrode or the second electrode includes an electrode cavity. 
     
     
         18 . The device of  claim 11  wherein the support layer includes silicon dioxide (SiO 2 ) or other silicon materials. 
     
     
         19 . The device of  claim 11  wherein the first electrode or the second electrode includes an energy confinement structure. 
     
     
         20 . The device of  claim 18  wherein the first electrode, the piezoelectric film, and the second electrode form a resonator area; and
 wherein the energy confinement structure is configured surrounding the resonator area.