US-12620969-B2 - Assembly with piezoelectric layer with embedded interdigital transducer electrode

US12620969B2US 12620969 B2US12620969 B2US 12620969B2US-12620969-B2

Abstract

An acoustic wave device assembly is disclosed. The acoustic wave device assembly can include a first acoustic wave device that includes a first substrate, a first piezoelectric layer, a first solid acoustic mirror that is disposed between the first substrate and the first piezoelectric layer, and a first interdigital transducer electrode that is embedded in the piezoelectric layer. The acoustic wave device assembly can include a second acoustic wave device that includes a second substrate, a second piezoelectric layer, a second solid acoustic mirror that is disposed between the second substrate and the second piezoelectric layer, and a second interdigital transducer electrode that is in contact with the second piezoelectric layer. The second acoustic wave device is stacked over the first acoustic wave device. The first acoustic wave device and the second acoustic wave device are spaced by a spacer assembly such that a cavity is formed between the first acoustic wave device and the second acoustic wave device.

Inventors

Hironori Fukuhara
Rei GOTO

Assignees

SKYWORKS SOLUTIONS, INC.

Dates

Publication Date: 20260505
Application Date: 20220720

Claims (20)

1 . An acoustic wave device assembly comprising: a first acoustic wave device including a first substrate, a first piezoelectric layer, a first solid acoustic mirror disposed between the first substrate and the first piezoelectric layer, and a first interdigital transducer electrode embedded in the first piezoelectric layer; and a second acoustic wave device including a second substrate, a second piezoelectric layer, a second solid acoustic mirror disposed between the second substrate and the second piezoelectric layer, and a second interdigital transducer electrode in contact with the second piezoelectric layer, the second acoustic wave device being stacked with the first acoustic wave device, the first acoustic wave device and the second acoustic wave device being spaced by a spacer assembly such that a cavity is formed between the first acoustic wave device and the second acoustic wave device, the second solid acoustic mirror closer to the cavity than the second piezoelectric layer, and a third solid acoustic mirror disposed between the second piezoelectric layer and a third substrate.
2 . The acoustic wave device assembly of claim 1 wherein the second interdigital transducer electrode is embedded in the second piezoelectric layer.
3 . The acoustic wave device assembly of claim 1 wherein the first interdigital transducer electrode is completely embedded in the first piezoelectric layer such that the first interdigital transducer electrode is positioned closer to the cavity than to the first solid acoustic mirror.
4 . The acoustic wave device assembly of claim 1 wherein the first solid acoustic mirror includes alternating low impedance layers and high impedance layers that has a higher impedance than the low impedance layers of first solid acoustic mirror.
5 . The acoustic wave device assembly of claim 4 wherein the second solid acoustic mirror includes alternating low impedance layers and high impedance layers that has a higher impedance than the low impedance layers of second solid acoustic mirror.
6 . The acoustic wave device assembly of claim 5 wherein the low impedance layers of the first solid acoustic mirror and the low impedance layers of the second solid acoustic mirror have different thicknesses.
7 . The acoustic wave device assembly of claim 1 wherein the first piezoelectric layer and the second piezoelectric layer are positioned between the first and third substrates.
8 . The acoustic wave device assembly of claim 1 wherein the second substrate is disposed between the first and second piezoelectric layers.
9 . The acoustic wave device assembly of claim 1 wherein at least one of the first acoustic wave device or the second acoustic wave device is a laterally excited bulk acoustic wave resonator.
10 . The acoustic wave device assembly of claim 1 wherein at least one of the first acoustic wave device or the second acoustic wave device is a leaky longitudinal surface acoustic wave resonator.
11 . The acoustic wave device assembly of claim 1 wherein the first acoustic wave device has a single mirror structure and the second acoustic wave device has a double mirror structure.
12 . An acoustic wave device assembly comprising: a first acoustic wave device including a first substrate, a first piezoelectric layer having a first portion and a second portion, a first solid acoustic mirror disposed between the first substrate and the first piezoelectric layer, and a first interdigital transducer electrode on the first portion of the first piezoelectric layer and covered by the second portion of the first piezoelectric layer; and a second acoustic wave device including a second substrate, a second piezoelectric layer, a second solid acoustic mirror disposed between the second substrate and the second piezoelectric layer, and a second interdigital transducer electrode in contact with the second piezoelectric layer, the second acoustic wave device being stacked with the first acoustic wave device, the first acoustic wave device and the second acoustic wave device being spaced by a spacer assembly such that a cavity is formed between the first acoustic wave device and the second acoustic wave device, the second solid acoustic mirror closer to the cavity than the second piezoelectric layer, and a third solid acoustic mirror disposed between the second piezoelectric layer and a third substrate.
13 . The acoustic wave device assembly of claim 12 wherein the second interdigital transducer electrode is embedded in the second piezoelectric layer.
14 . The acoustic wave device assembly of claim 12 wherein a thickness of the first portion of the first piezoelectric layer is greater than a thickness of the second portion of the second piezoelectric layer.
15 . The acoustic wave device assembly of claim 12 wherein the first solid acoustic mirror includes alternating low impedance layers and high impedance layers that has a higher impedance than the low impedance layers of first solid acoustic mirror.
16 . The acoustic wave device assembly of claim 15 wherein the second solid acoustic mirror includes alternating low impedance layers and high impedance layers that has a higher impedance than the low impedance layers of second solid acoustic mirror.
17 . The acoustic wave device assembly of claim 16 wherein the low impedance layers of the first solid acoustic mirror and the low impedance layers of the second solid acoustic mirror have different thicknesses.
18 . The acoustic wave device assembly of claim 12 wherein the first piezoelectric layer and the second piezoelectric layer are positioned between the first and third substrates.
19 . The acoustic wave device assembly of claim 12 wherein the second substrate is disposed between the first and second piezoelectric layers.
20 . The acoustic wave device assembly of claim 12 wherein the first acoustic wave device has a single mirror structure and the second acoustic wave device has a double mirror structure.

Description

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application, including U.S. Provisional Patent Application No. 63/251,982, filed Oct. 4, 2021, titled “STACKED ACOUSTIC WAVE DEVICE ASSEMBLY,” are hereby incorporated by reference under 37 CFR 1.57 in their entirety. BACKGROUND Technical Field Embodiments of the invention relate to stacked acoustic wave device assemblies. Description of the Related Technology An acoustic wave filter can include a plurality of resonators arranged to filter a radio frequency signal. Example acoustic wave filters include surface acoustic wave (SAW) filters and bulk acoustic wave (BAW) filters. A surface acoustic wave resonator can include an interdigital transductor electrode on a piezoelectric substrate. The surface acoustic wave resonator can generate a surface acoustic wave on a surface of the piezoelectric layer on which the interdigital transductor electrode is disposed. In BAW resonators, acoustic waves propagate in a bulk of a piezoelectric layer. Example BAW resonators include film bulk acoustic wave resonators (FBARs) and solidly mounted resonators (SMRs). Certain acoustic resonators can include features of SAW resonators and features of BAW resonators. A stacked acoustic wave device assembly can include a plurality of acoustic wave devices (or: acoustic wave resonators). Acoustic wave filters can be implemented in radio frequency electronic systems. For instance, filters in a radio frequency front end of a mobile phone can include acoustic wave filters. An acoustic wave filter can be a band pass filter. A plurality of acoustic wave filters can be arranged as a multiplexer. For example, two acoustic wave filters can be arranged as a duplexer. The two acoustic wave filters of a duplexer can be included in one stacked acoustic wave device assembly. As another example, four acoustic wave filters can be arranged as a quadplexer, for example four acoustic wave filters provided by the two acoustic filter devices of each of two stacked acoustic wave devices assemblies. SUMMARY The innovations described in the claims each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of the claims, some prominent features of this disclosure will now be briefly described. A stacked acoustic wave device assembly is disclosed. The stacked acoustic wave device assembly can include a first acoustic wave device that includes a first substrate, a first piezoelectric layer, a first solid acoustic mirror disposed between the first substrate and the first piezoelectric layer, and a first interdigital transducer electrode in contact with the first piezoelectric layer. The stacked acoustic wave device assembly can include a second acoustic wave device that includes a second substrate, a second piezoelectric layer, a second solid acoustic mirror disposed between the second substrate and the second piezoelectric layer, and a second interdigital transducer electrode in contact with the second piezoelectric layer. The second acoustic wave device is stacked over the first acoustic wave device. The first acoustic wave device and the second acoustic wave device are spaced by a spacer assembly such that a cavity is formed between the first acoustic wave device and the second acoustic wave device. In one embodiment, the first piezoelectric layer has a first side and a second side opposite the first side. The second piezoelectric layer can be arranged such that the first side of the first piezoelectric layer faces the second piezoelectric layer. The first solid acoustic mirror can be arranged such that the second side of the first piezoelectric layer faces the first solid acoustic mirror. In one embodiment, the first piezoelectric layer is arranged at a first side of the second piezoelectric layer and the second solid acoustic mirror is arranged at a second side of the second piezoelectric layer opposite to the first side of the second piezoelectric layer. In one embodiment, the first interdigital transducer electrode and the second interdigital transducer electrode face each other in the cavity. In one embodiment, the first solid acoustic mirror, the first piezoelectric layer, the first interdigital transducer electrode, the second interdigital transducer electrode, the spacer assembly, the second piezoelectric layer, and the second solid acoustic mirror are positioned between the first substrate and the second substrate. In one embodiment, at least one of the first acoustic wave device or the second acoustic wave device is a laterally excited bulk acoustic wave resonator, and includes lithium niobate having a crystal orientation of (α, β, γ), with α between −10° and +10°, β between −10° and +10°, and γ between 80° and 100° in Euler angles. In one embodiment, at least one of the first acousti