Embedded capacitors with buried metal layer underneath bulk acoustic wave resonator for electromechanical coupling coefficient control
Aspects and embodiments disclosed herein include a film bulk acoustic wave resonator comprising a substrate including a layer of dielectric material disposed on an upper surface of the substrate, a layer of piezoelectric material, a top electrode disposed on a top surface of the layer of piezoelectric material, a bottom electrode disposed on a bottom surface of the layer of piezoelectric material, a cavity defined between a lower surface of the bottom electrode and an upper surface of the layer of dielectric material, and a layer of conductive material buried within the layer of dielectric material at least partially beneath the cavity and the bottom electrode.
1 . A film bulk acoustic wave resonator comprising:
a substrate including a layer of dielectric material disposed on an upper surface of the substrate;
a layer of piezoelectric material;
a top electrode disposed on a top surface of the layer of piezoelectric material;
a bottom electrode disposed on a bottom surface of the layer of piezoelectric material, a cavity defined between a lower surface of the bottom electrode and an upper surface of the layer of dielectric material; and
a layer of conductive material buried within the layer of dielectric material and disposed beneath only a portion of the cavity and the bottom electrode.
2 . The film bulk acoustic wave resonator of claim 1 wherein at least a portion of an upper surface of the layer of conductive material is disposed beneath the upper surface of the layer of dielectric material.
3 . The film bulk acoustic wave resonator of claim 2 wherein at least a portion of a lower surface of the layer of conductive material is disposed above a lower surface of the layer of dielectric material.
4 . The film bulk acoustic wave resonator of claim 1 wherein the layer of conductive material is electrically connected to the top electrode.
5 . The film bulk acoustic wave resonator of claim 4 wherein a portion of the layer of conductive material extends outward from an area beneath the cavity and electrically connects to a top electrical contact that is electrically connected to the top electrode.
6 . The film bulk acoustic wave resonator of claim 4 further comprising a through-substrate via passing through the substrate and electrically connecting the layer of conducting material to an electrical contact disposed on a lower surface of the substrate.
7 . The film bulk acoustic wave resonator of claim 1 wherein the layer of conductive material is electrically connected to neither the top electrode nor the bottom electrode.
8 . The film bulk acoustic wave resonator of claim 7 wherein the layer of conductive material is electrically floating.
9 . The film bulk acoustic wave resonator of claim 7 wherein the layer of conductive material is disposed entirely beneath the cavity.
10 . The film bulk acoustic wave resonator of claim 7 further comprising a through-substrate via passing through the substrate and electrically connecting the layer of conducting material to an electrical contact disposed on a lower surface of the substrate.
11 . The film bulk acoustic wave resonator of claim 1 wherein the layer of conductive material is electrically connected to the bottom electrode.
12 . The film bulk acoustic wave resonator of claim 11 wherein the layer of conductive material is directly connected to the bottom electrode.
13 . The film bulk acoustic wave resonator of claim 11 further comprising a through-substrate via passing through the substrate and electrically connecting the layer of conducting material to an electrical contact disposed on a lower surface of the substrate.
14 . The film bulk acoustic wave resonator of claim 1 wherein the layer of conductive material changes an electromechanical coupling coefficient of the film bulk acoustic wave resonator.
15 . The film bulk acoustic wave resonator of claim 1 wherein the layer of conductive material lowers an electromechanical coupling coefficient of the film bulk acoustic wave resonator.
16 . The film bulk acoustic wave resonator of claim 1 wherein the layer of conductive material defines a first plate of a capacitor and one of the top electrode or the bottom electrode defines a second plate of the capacitor.
17 . A ladder filter including a series arm film bulk acoustic wave resonator comprising:
a substrate including a layer of dielectric material disposed on an upper surface of the substrate;
a layer of piezoelectric material;
a top electrode disposed on a top surface of the layer of piezoelectric material;
a bottom electrode disposed on a bottom surface of the layer of piezoelectric material, a cavity defined between a lower surface of the bottom electrode and an upper surface of the layer of dielectric material; and
a layer of conductive material buried within the layer of dielectric material and disposed beneath only a portion of the cavity and bottom electrode.
18 . The ladder filter of claim 17 further comprising a capacitor electrically connected in parallel to the series arm film bulk acoustic wave resonator.
19 . The ladder filter of claim 18 wherein the layer of conductive material defines a first plate of the capacitor and one of the top electrode or the bottom electrode defines a second plate of the capacitor.
20 . An electronic device including the ladder filter of claim 19 .