Surface acoustic wave device and method of manufacturing the same
AssigneeNihon Dempa Kogyo Co., Ltd.
InventorAtsushi Kamijo
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Abstract
In order to provide a surface acoustic wave device provided with a pseudo-single crystal aluminum electrode film, having excellent power durability, easy to manufacture, and possible to grow with good reproducibility, a titanium buffer film 4 and an electrode film composed of an aluminum film or an aluminum alloy film are formed on a piezoelectric substrate 2 composed of lithium tantalate or lithium niobate. The electrode film 5 comprises a pseudo-single crystal film composed of two (111) domains. Each of the <111> directions of two (111) domains tilts in the range of 0 to 10 degrees to the substrate surface, and the <11-2> directions in the respective (111) domain planes are 1 to 15 degrees apart.
Claims9
A surface acoustic wave device, comprising:
- a single crystal piezoelectric substrate composed of lithium tantalate (LiTaO3) or lithium niobate (LiNbO3);
- and
- an electrode formed on the piezoelectric substrate,
- wherein the electrode comprises a first film formed of titanium (Ti), and a second film formed of aluminum or aluminum alloy made by adding a small amount of metal atom to aluminum (Al),
- wherein the second film is formed of a crystal film including two (111) domains growing in different directions from each other,
- wherein both <111> directions of the two (111) domains tilt at angles within 0 to 10 degrees to the surface of the piezoelectric substrate, and
- wherein <11-2> directions in an in-plane of each of the (111) domains are arranged uniformly, while the <11-2> direction in the in-plane of one (111) domain and the <11-2> direction in the in-plane of the other (111) domain are 1 to 15 degrees apart from each other.
A method of manufacturing a surface acoustic wave device which comprises a single crystal piezoelectric substrate composed of lithium tantalate (LiTaO3) or lithium niobate (LiNbO3), comprising:
- cleaning a surface of the piezoelectric substrate;
- forming an electrode on the surface of the piezoelectric substrate following said cleaning, including:
- forming a first film formed of titanium (Ti) on the surface of the piezoelectric substrate, and
- forming, on said first film, a second film formed of aluminum or aluminum alloy made by adding a small amount of metal atom to aluminum (Al) arranged to form said electrode,
- wherein said second film is formed of a crystal film including two (111) domains growing in different directions from each other,
- wherein both <111> directions of the two (111) domains tilt at angles within 0 to 10 degrees to the surface of the piezoelectric substrate, and
- wherein <11-2> directions in an in-plane of each of the (111) domains are arranged uniformly, while the <11-2> direction in the in-plane of one (111) domain and the <11-2> direction in the in-plane of the other (111) domain are 1 to 15 degrees apart from each other,
- wherein the cleaning process cleans the surface of the piezoelectric substrate by applying ultrasonic waves to organic solvent in a state that the organic solvent is in contact with the surface of the piezoelectric substrate, without performing wet etching.
Dependencies are inferred from the claim text.