Acoustic resonator device

1. An acoustic resonator device comprising:

an active element having a first side and a second side, facing opposite to the first side, and having an electrical signal input electrode layer and an electrical signal output electrode layer, and wherein the active element comprises at least one piezoelectric layer;

a support, wherein the support comprises an acoustic isolation membrane, and wherein the membrane is attached to the first side of the active element; and

a multilayer stack, attached to the second side of the active element comprising at least three layers including at least one layer of high acoustic impedance and at least one layer of low acoustic impedance based on SiOC, and wherein the at least three layers of the multilayer stack have thicknesses and material so as to define a resonant frequency of the acoustic resonator device when the multilayer stack is attached to the active element.

2. The device according to claim 1 , wherein the multilayer stack comprises two layers of low acoustic impedance surrounding a layer of high acoustic impedance.

3. The device according to claim 1 , wherein the active element is in contact with a layer of low acoustic impedance of the multilayer stack.

4. The device according to claim 1 , wherein the acoustic isolation membrane is formed by one of the electrical signal input electrode layer and the electrical signal output electrode layer of the active element.

5. The device according to claim 1 , wherein the acoustic isolation membrane is located beneath a lower electrode of the active element, the lower electrode being one of the electrical signal input electrode layer and the electrical signal output electrode layer.

6. The device according to claim 5 , wherein the acoustic isolation membrane is placed in contact with the lower electrode of the active element.

7. The device according to claim 1 , wherein the active element comprises a piezoelectric layer, a lower electrode layer and an upper electrode layer, the piezoelectric layer being placed between the lower electrode layer and the upper electrode layer, and wherein the lower electrode layer being one of the electrical signal input electrode layer and the electrical signal output electrode layer and the upper electrode layer being the other one.

8. The device according to claim 1 , wherein the active element comprises two piezoelectric layers and three electrode layers, one piezoelectric layer being placed between, and contacting, two electrode layers, and wherein the two electrode layers being the electrical signal input electrode layer and the electrical signal output electrode layer.

9. The device according to claim 1 , wherein the active element comprises two piezoelectric layers, four electrode layers and a multilayer stack provided with at least three layers, including at least one layer of high acoustic impedance and at least one layer of low acoustic impedance, one piezoelectric layer being placed between two electrode layers, and the multilayer stack being placed between an electrode layer adjacent to a lower piezoelectric layer and an electrode layer adjacent to an upper piezoelectric layer.

10. The device according to claim 1 , wherein the multilayer stack operates to tune the resonant frequency by filtering out certain undesirable frequencies generated by the active element.

11. The device according to claim 1 , wherein an empty space is left beneath the acoustic isolation membrane and opposite to a side of the membrane being attached to the first side of the active element.

12. The device according to claim 1 , wherein the electrode layers are based on the following materials: Al, Au, Mo, Pt, Ti, W.

13. The device according to claim 1 , wherein the membrane is based on any silicon nitride or a metal nitride.

14. The device according to claim 1 , wherein the at least one piezoelectric layer is based on any of the following materials: AlN, BaTiO 3 , KNbO 3 , ZnO.

15. The device according to claim 1 , wherein the layers of high acoustic impedance of the multilayer stack are based on any of the following materials: AlN, SiO 2 , W, Mo.

16. A plurality of acoustic resonators, each acoustic resonator comprising:

an active element having a first side and a second side, facing opposite to the first side, and wherein the active element comprises at least one piezoelectric layer;

a support, wherein the support comprises an acoustic isolation membrane, and wherein the membrane is attached to the first side of the active element; and

a multilayer stack, attached to the second side of the active element, comprising at least three layers including at least one layer of high acoustic impedance and at least one layer of low acoustic impedance, and wherein the at least three layers of the multilayer stack have thicknesses and material so as to define a resonant frequency of the acoustic resonator when the multilayer stack is attached to the active element, and wherein the acoustic isolation membrane is attached to a side of each of the plurality of acoustic resonators.

17. The device according to claim 16 , wherein the acoustic isolation membrane comprises an electrode layer of at least two of the plurality of acoustic resonators.

18. An integrated circuit comprising:

a circuit supporting substrate;

an electronic circuit; and

at least one acoustic resonator disposed on the circuit supporting substrate and electrically coupled with the electronic circuit, each of the at least one resonator comprising:

an active element having a first side and a second side, facing opposite to the first side, and having an electrical signal input electrode layer and an electrical signal output electrode layer, and wherein the active element comprises at least one piezoelectric layer;

a support, wherein the support comprises an acoustic isolation membrane, and wherein the membrane is attached to the first side of the active element; and

a multilayer stack, attached to the second side of the active element, comprising at least three layers including at least one layer of high acoustic impedance and at least one layer of low acoustic impedance based on SiOC, and wherein the at least three layers of the multilayer stack have thicknesses and material so as to define a resonant frequency of the acoustic resonator when the multilayer stack is attached to the active element.

19. The integrated circuit of claim 18 , wherein the active element comprises a piezoelectric layer, a lower electrode layer and an upper electrode layer, the piezoelectric layer being placed between the lower electrode layer and the upper electrode layer, and wherein the lower electrode layer being one of the electrical signal input electrode layer and the electrical signal output electrode layer and the upper electrode layer being the other one, and wherein the acoustic isolation membrane is formed by the lower electrode layer of the active element, and wherein an empty space is left beneath the acoustic isolation membrane and opposite to a side of the membrane being attached to the first side of the active element.

20. The integrated circuit of claim 18 , wherein the acoustic isolation membrane is attached to a side of each of a plurality of acoustic resonators of the at least one acoustic resonator.