ACOUSTIC WAVE DEVICE WITH MULTI-LAYER PIEZOELECTRIC SUBSTRATE

• US 20190326879A1
• Filed: 04/11/2019
• Published: 10/24/2019
• Est. Priority Date: 04/18/2018
• Status: Active Grant

• Current Assignee: Skyworks Solutions Incorporated
• Original Assignee: Skyworks Solutions Incorporated
• Inventors: Nakamura, Hiroyuki, Goto, Rei, Maki, Keiichi
• Granted Patent: US 11,689,178 B2
• Time in Patent Office: Days
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H03H 9/0222 of interface-acoustic, boundary, pseudo-acoustic or Stonely wave devices
• CPC Class Codes: H03H 9/02559 of lithium niobate or lithium-tantalate substrates
• CPC Class Codes: H03H 9/02574 of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate
• CPC Class Codes: H03H 9/02834 of temperature influence cut angles H03H9/02543
• CPC Class Codes: H03H 9/02866 of bulk wave excitation and reflections
• CPC Class Codes: H03H 9/0547 consisting of a vertical arrangement H03H9/0566 takes precedence
• CPC Class Codes: H03H 9/058 for surface acoustic wave devices
• CPC Class Codes: H03H 9/145 for networks using surface acoustic waves
• CPC Class Codes: H03H 9/25 Constructional features of resonators using surface acoustic waves devices for manipulating acoustic surface waves in general G10K11/36
• CPC Class Codes: H03H 9/465 in combination with other electronic elements
• CPC Class Codes: H03H 9/54 comprising resonators of piezoelectric or electrostrictive material H03H9/64 takes precedence
• CPC Class Codes: H03H 9/64 using surface acoustic waves
• CPC Class Codes: H03H 9/6489 Compensation of undesirable effects
• CPC Class Codes: H04B 1/0057 using diplexing or multiplexing filters for selecting the desired band

Abstract

Aspects of this disclosure relate to an acoustic wave device that includes high velocity layers on opposing sides of a piezoelectric layer. A low velocity layer can be positioned between the piezoelectric layer and one of the high velocity layers, in which the low velocity layer has a lower acoustic velocity than the high velocity layers. The acoustic wave device can be configured to generate a boundary acoustic wave such that acoustic energy is concentrated at a boundary of the piezoelectric layer and the low velocity layer.

Claims

1. An acoustic wave device comprising:

a piezoelectric layer;

an interdigital transducer electrode on the piezoelectric layer;

high velocity layers on opposing sides of the piezoelectric layer; and

a low velocity layer positioned between the piezoelectric layer and a first high velocity layer of the high velocity layers, the low velocity layer having a lower acoustic velocity than the high velocity layers, the acoustic velocity of the low velocity layer being a speed of sound of a shear wave propagating in the low velocity layer, and the acoustic wave device being configured to generate a boundary acoustic wave such that acoustic energy is concentrated at a boundary of the piezoelectric layer and the low velocity layer.

2. The acoustic wave device of claim 1 wherein each of the high velocity layers has a higher acoustic velocity than a velocity of the boundary acoustic wave.

3. The acoustic wave device of claim 1 wherein the low velocity layer includes silicon dioxide.

4. The acoustic wave device of claim 3 wherein the high velocity layers are silicon layers.

5. The acoustic wave device of claim 1 wherein at least one of the high velocity layers is a silicon layer.

6. The acoustic wave device of claim 1 wherein at least one of the high velocity layers includes at least one of silicon nitride, aluminum nitride, diamond, quartz, or spinel.

7. The acoustic wave device of claim 1 wherein the piezoelectric layer is a lithium tantalate layer.

8. The acoustic wave device of claim 1 wherein the piezoelectric layer is a lithium niobate layer.

9. The acoustic wave device of claim 1 wherein the high velocity layers are made of the same material as each other.

10. The acoustic wave device of claim 1 wherein the boundary acoustic wave has a wavelength of λ

and at least one of the high velocity layers has a thickness in a range from 1λ

to 10λ

.

11. The acoustic wave device of claim 1 wherein the acoustic wave device has a thickness in a range from 10 micrometers (um) to 100 um.

12. The acoustic wave device of claim 1 wherein the boundary acoustic wave has a wavelength of λ

and the piezoelectric layer has a thickness of less than 2λ

.

13. The acoustic wave device of claim 1 wherein a velocity of the boundary acoustic wave is in a range from 2500 meters per second to 4800 meters per second.

14. The acoustic wave device of claim 1 wherein a velocity of the boundary acoustic wave is in a range from 4100 meters per second to 4800 meters per second.

15. A radio frequency module comprising:

an acoustic wave filter configured to filter a radio frequency signal, the acoustic wave filter including an acoustic wave device including a piezoelectric layer, an interdigital transducer electrode on the piezoelectric layer, high velocity layers on opposing sides of the piezoelectric layer, and a low velocity layer disposed between the piezoelectric layer and a first high velocity layer of the high velocity layers, the low velocity layer having a lower acoustic velocity than the high velocity layers, and the acoustic wave device being configured to generate a boundary acoustic wave such that acoustic energy is concentrated at a boundary of the piezoelectric layer and the low velocity layer; and

a radio frequency switch coupled to the acoustic wave filter, the radio frequency switch being packaged with the acoustic wave filter.

16. The radio frequency module of claim 15 further comprising a power amplifier, the radio frequency switch configured to selectively electrically connect an output of the power amplifier to the acoustic wave filter.

17. The radio frequency module of claim 15 further comprising an antenna port, the radio frequency switch configured to selectively electrically connect the acoustic wave filter to an antenna port of the radio frequency module.

18. A method of filtering a radio frequency signal with an acoustic wave filter, the method comprising:

providing a radio frequency signal to an acoustic wave filter; and

filtering the radio frequency signal with the acoustic wave filter, the acoustic wave filter including an acoustic wave device that includes a piezoelectric layer, an interdigital transducer electrode on the piezoelectric layer, high velocity layers on opposing sides of the piezoelectric layer, a low velocity layer positioned between the piezoelectric layer and a first high velocity layer of the high velocity layers, the low velocity layer having a lower acoustic velocity than the high velocity layers, and the acoustic wave device generating a boundary acoustic wave such that acoustic energy is concentrated at a boundary of the piezoelectric layer and the low velocity layer.

19. The method of claim 18 wherein the high velocity layers are silicon layers and the low velocity layer is a silicon dioxide layer.

20. The method of claim 19 wherein the piezoelectric layer is a lithium niobate layer or a lithium tantalate layer.