Piezoelectric element, method of manufacturing the same, surface acoustic wave element, and piezoelectric thin film resonance element

Patent metadata

Field	Value
Publication number	US-12328108-B2
Application number	US-202117474221-A
Country	US
Kind code	B2
Filing date	Sep 14, 2021
Priority date	Sep 18, 2020
Publication date	Jun 10, 2025
Grant date	Jun 10, 2025

Abstract

A piezoelectric element includes a single crystal piezoelectric film, wherein the single crystal piezoelectric film includes an aluminum nitride film and wherein a full width at half maximum at (002) diffraction peak of the aluminum nitride film is smaller than 1.00 degree.

First claim

What is claimed is:

1. A piezoelectric element comprising:
a piezoelectric film,
wherein the piezoelectric film is a laminated film including a first thin film and a highly c-axis oriented aluminum nitride film that is laminated to the first thin film,
wherein a full width at half maximum of a (002) diffraction peak of the aluminum nitride film is smaller than 1.00 degree, and
wherein the first thin film is a thin film having a negative linear expansion coefficient.

2. The piezoelectric element of claim 1 , further comprising
a base substrate,
wherein the piezoelectric film is arranged on the base substrate.

3. The piezoelectric element of claim 2 , wherein the base substrate is one selected from the group of a silicon (111) substrate, an SOI substrate in which an active layer is silicon (111), a SiC substrate, and a sapphire substrate.

4. The piezoelectric element of claim 1 , wherein the full width at half maximum at (002) diffraction peak of the aluminum nitride film is smaller than 0.36 degrees.

5. The piezoelectric element of claim 1 , wherein a film thickness of the aluminum nitride film is 70 nm or more.

6. The piezoelectric element of claim 1 , wherein a film thickness of the aluminum nitride film is 100 nm or more.

7. The piezoelectric element of claim 1 , wherein the piezoelectric film further includes a second thin film, and
wherein the second thin film is at least one selected from the group of a gallium nitride film, an aluminum gallium nitride film, and an aluminum nitride film containing scandium.

8. A surface acoustic wave element comprising the piezoelectric element of claim 1 .

9. A piezoelectric thin film resonance element comprising the piezoelectric element of claim 1 .

10. A method of manufacturing a piezoelectric element, comprising:
forming a piezoelectric film, which is a laminated film including a first thin film and a highly c-axis oriented aluminum nitride film that is laminated to the first thin film, on a base substrate,
wherein the aluminum nitride film is formed by one selected from the group of a CVD method and an MBE method,
wherein a full width at half maximum of a (002) diffraction peak of the aluminum nitride film is smaller than 1.00 degree, and
wherein the first thin film is a thin film having a negative linear expansion coefficient.

11. The method of claim 10 , wherein the base substrate is one selected from the group of a silicon (111) substrate, an SOI substrate in which an active layer is silicon (111), a SiC substrate, and a sapphire substrate.

12. The method of claim 10 , wherein the aluminum nitride film is formed by a MOCVD method.

13. The method of claim 12 , wherein the aluminum nitride film is formed by the MOCVD method in which trimethylaluminum and ammonia are used, the base substrate is set at 900 to 1,100 degrees C., and a pressure at the time of film formation is 10 to 15 kPa.

14. The method of claim 10 , wherein the full width at half maximum at (002) diffraction peak of the aluminum nitride film is smaller than 0.36 degrees.

15. The method of claim 10 , wherein a film thickness of the aluminum nitride film is 70 nm or more.

16. The method of claim 10 , wherein a film thickness of the aluminum nitride film is 100 nm or more.

17. The method of claim 10 , wherein the piezoelectric film further includes a second thin film, and
wherein the second thin film is at least one selected from the group of a gallium nitride film, an aluminum gallium nitride film, and an aluminum nitride film containing scandium.

18. The method of claim 10 , wherein the base substrate is peeled off by at least one selected from the group of etching, grinding, and polishing.

Assignees

• Rohm Co Ltd

Inventors

• Shimoji Noriyuki
• Date Tomohiro
• Ito Norikazu

Classifications

• H03H9/25

  Constructional features of resonators using surface acoustic waves {(devices for manipulating acoustic surface waves in general G10K11/36)} · CPC title

• H03H3/08

  for the manufacture of resonators or networks using surface acoustic waves · CPC title

• C30B29/403

  AIII-nitrides · CPC title

• C30B25/18

  characterised by the substrate · CPC title

• H10N30/704

  based on piezoelectric or electrostrictive films or coatings · CPC title