Acoustic wave device and method of fabricating the same

Patent metadata

Field	Value
Publication number	US-2017201232-A1
Application number	US-201615331598-A
Country	US
Kind code	A1
Filing date	Oct 21, 2016
Priority date	Jan 7, 2016
Publication date	Jul 13, 2017
Grant date	—

Abstract

An acoustic wave device includes: a piezoelectric substrate; a comb-shaped electrode that is located on the piezoelectric substrate and excites an acoustic wave; and a silicon oxide film that is located on the piezoelectric substrate so as to cover the comb-shaped electrode, and has a total concentration of carbon (C), hydrogen (H), nitrogen (N), and fluorine (F) equal to or less than 3.5 atomic %.

First claim

What is claimed is:

1 . An acoustic wave device comprising:
a piezoelectric substrate; a comb-shaped electrode that is located on the piezoelectric substrate and excites an acoustic wave; and a silicon oxide film that is located on the piezoelectric substrate so as to cover the comb-shaped electrode, and has a total concentration of carbon (C), hydrogen (H), nitrogen (N), and fluorine (F) equal to or less than 3.5 atomic %.

2 . The acoustic wave device according to claim 1 , wherein
a concentration of argon (Ar) in the silicon oxide film is 0.1 atomic % or less.

3 . The acoustic wave device according to claim 2 , wherein
a concentration of carbon in the silicon oxide film is 1 atomic % or less.

4 . The acoustic wave device according to claim 2 , wherein
a concentration of hydrogen in the silicon oxide film is 2 atomic % or less.

5 . The acoustic wave device according to claim 1 , wherein
a film thickness of the silicon oxide film on an electrode finger of the comb-shaped electrode is equal to or greater than a film thickness of the electrode finger.

6 . The acoustic wave device according to claim 1 , further comprising:
a dielectric film that is formed between the piezoelectric substrate and the silicon oxide film so as to cover the comb-shaped electrode.

7 . The acoustic wave device according to claim 1 , wherein
the piezoelectric substrate includes, under the comb-shaped electrode, a region in which at least one or some of elements of the comb-shaped electrode are diffused.

8 . The acoustic wave device according to claim 7 , wherein
the piezoelectric substrate is a lithium niobate substrate or a lithium tantalate substrate, the comb-shaped electrode includes a Ti film formed on the piezoelectric substrate and a Cu film formed on the Ti film, and the one or some of elements of the comb-shaped electrode are Ti.

9 . The acoustic wave device according to claim 1 , wherein
the piezoelectric substrate is a lithium niobate substrate or a lithium tantalate substrate.

10 . The acoustic wave device according to claim 1 , further comprising:
a filter including the comb-shaped electrode.

11 . The acoustic wave device according to claim 10 , wherein
the filter includes a plurality of resonators each including the comb-shaped electrode, and the silicon oxide film integrally covers the comb-shaped electrodes included in the plurality of resonators.

12 . A method of fabricating an acoustic wave device, the method comprising:
forming a comb-shaped electrode, which excites an acoustic wave, on a piezoelectric substrate; and forming a silicon oxide film on the piezoelectric substrate so as to cover the comb-shaped electrode by TEOS-PE-CVD.

13 . The method according to claim 12 , wherein
a carrier gas is not used in the forming of the silicon oxide film.

Assignees

• Taiyo Yuden Kk

Inventors

• Nakamura Kentaro
• Matsukura Fumiya
• Matsuda Takashi
• Miyashita Tsutomu
• Tsutsumi Jun

Classifications

• H03H9/1452

  by finger overlap length, apodisation · CPC title

• H03H9/14541

  Multilayer finger or busbar electrode · CPC title

• H03H9/02834

  of temperature influence (cut angles H03H9/02543) · CPC title

• H03H9/64

  using surface acoustic waves · CPC title

• H03H3/04

  for obtaining desired frequency or temperature coefficient · CPC title