Method for the production of a bulk acoustic wave resonator with a reduced parasitic capacitance

Patent metadata

Field	Value
Publication number	US-11601107-B2
Application number	US-201816956375-A
Country	US
Kind code	B2
Filing date	Dec 21, 2018
Priority date	Dec 26, 2017
Publication date	Mar 7, 2023
Grant date	Mar 7, 2023

Abstract

A method for producing an adjustable bulk acoustic wave resonator comprising a transducer stack (E1) and a tuning stack (E2). According to the invention, transducer stack (E1) includes two defined electrodes (4, 6) and piezoelectric material (2), and stack (E2) includes a layer of piezoelectric material (8) and two defined electrodes (10, 12). The method includes: a) production of the transducer stack; b) formation of an electrically insulating layer on an electrode (6) of the transducer stack; c) formation of a defined electrode (10) of the tuning stack on the electrically insulting layer such that it is aligned with the electrodes of the transducer stack; d) assembly, on the electrode (10), of a substrate of piezoelectric material; e) fracturing of the substrate of piezoelectric material; and f) formation of the other defined electrode (12) of the tuning stack, aligned with the defined electrode (10).

First claim

The invention claimed is:

1. A method for a production of an acoustic resonator including at least a first functional stack and a second functional stack, the first functional stack including at least one first element consisting of a first layer of piezoelectric or dielectric material interposed between two structured electrically conducting layers, a coverage surface of the two structured electrically conducting layers defining a first active zone, the second functional stack including at least one second element consisting of a second layer of piezoelectric material interposed between a first and a second electrode, a coverage surface of the first and second electrodes defining a second active zone, said method including:
providing the first functional stack including the first layer of piezoelectric or dielectric material as well as both the structured electrically conducting layers associated with each other defining the first active zone,
forming the first electrode of the second functional stack on the first functional stack, so as to align the first electrode with the first active zone, and forming a first bonding layer of an electrically insulating material on the first electrode,
providing a part of the second functional stack comprising at least one second bonding layer of an electrically insulating material and the second layer of piezoelectric material,
assembling the first functional stack and the part of the second functional stack comprising at least one second bonding layer and the second layer of piezoelectric material by contacting the first and at least one second bonding layers,
forming the second electrode of the second functional stack, so as to define the second active zone in alignment with the first active zone.

2. The production method according to claim 1 , wherein assembling between the first functional stack and the part of the second functional stack is direct bonding.

3. The production method according to claim 1 , wherein the first and the at least one second bonding layers are of a further dielectric material.

4. The production method according to claim 1 , wherein the first and at least one second bonding layers are such that they form an intermediate layer with a thickness between 10 nm and 50 nm.

5. The production method according to claim 1 , wherein the alignment of the first electrode with the first active zone and the production of the second electrode so as to align the second active zone with the first active zone are achieved by implementing a mask aligner or a photorepeater during a photolithography step.

6. The production method according to claim 1 , wherein the first functional stack is a transducer and the second functional stack including the second layer of piezoelectric material forms frequency tuning means for said transducer.

7. The production method according to claim 6 , including, before forming the second functional stack, a step of removing a portion of a given thickness of the second layer of piezoelectric material of the second stack up to a given thickness.

8. The production method according to claim 7 , wherein the step of removing the portion with the given thickness of the second layer of piezoelectric material is achieved by fracturing the second layer of piezoelectric material of the second functional stack, said second layer of piezoelectric material having undergone beforehand an ion implantation to a depth slightly higher than a given depth of the first layer of piezoelectric material of the first functional stack.

9. The production method according to claim 6 , wherein the first functional stack includes a support substrate supporting the two structured electrically conducting layers and the first layer of the piezoelectric material.

10. The production method according to claim 9 , including a step of structuring the support substrate to form a cavity under the acoustic resonator.

11. The production method according to claim 10 , wherein the step of structuring the support substrate to form the cavity under the resonator comprises etching a sacrificial layer.

12. The production method according to claim 6 , wherein the first layer of piezoelectric material is produced by ion implantation and fracturing.

13. The production method according to claim 1 , wherein the first functional stack forms a Bragg mirror and the first stack and the second functional stack form a bulk acoustic wave resonator on the Bragg mirror.

14. The production method according to claim 13 , wherein the first layer and/or the second layer of piezoelectric material are of X-cut lithium niobate.

15. The production method according to claim 14 , wherein the first layer and/or the second layer of piezoelectric material have a thickness from 100 nm to several hundred nm.

16. The production method according to claim 13 , wherein the first and/or the second layer of piezoelectric material is (are) of Y+163°-cut lithium niobate.

17. The production method according to claim 16 , wherein the first and/or the second layer of piezoelectric material have a thickness from 100 nm to several hundred nm.

Assignees

• Commissariat Energie Atomique
• Commissariat A Lenergie Atomique Etaux Energies Alternatives

Inventors

• Gorisse Marie
• Reinhardt Alexandre
• Benaissa Lamine
• Moulet Jean-Sébastien

Classifications

• H10W10/181

  Semiconductor-on-insulator [SOI] isolation regions, e.g. buried oxide regions of SOI wafers · CPC title

• H10P90/1916

  with separation or delamination along an ion implanted layer, e.g. Smart-cut · CPC title

• H03H9/175

  Acoustic mirrors · CPC title

• H03H9/131

  consisting of a multilayered structure · CPC title

• H03H2009/02204

  operating on an additional circuit element, e.g. applying a tuning DC voltage to a passive circuit element connected to the resonator · CPC title