Method of fabricating an acoustic resonator comprising a filled recessed region

1. A method for fabricating an acoustic resonator comprising:

providing a substrate;

fabricating a first electrode adjacent the substrate;

fabricating a piezoelectric layer adjacent the first electrode;

depositing electrode material to form a second electrode up to a first thickness adjacent the piezoelectric layer;

depositing a first photo mask over the second electrode;

depositing additional electrode material over at least a portion of the first photo mask to form the second electrode up to a second thickness;

removing the photo mask thereby forming a recessed region in the second electrode; and

filling the recessed region with a fill material.

2. The method of claim 1 , further including depositing a second photo mask over the second electrode before filling the recessed region.

3. The method of claim 1 further including forming a depression in the substrate.

4. The method of claim 1 further including filling the recessed region with a different material than the electrode material.

5. The method of claim 1 , wherein filling the recessed region includes filling with a material selected from the group consisting of:

dielectrics, metals, metal alloys, piezoelectrics, Mo, Pt, Al, Cu, W, Au, Ag, polyimide, BCB, SiO 2 , Si 3 N 4 , AN, ZnO, LiNbO 3 , PZT, LiTaO 3 , and Al 2 O 3 .