Surface acoustic wave device
View Patent ↗Surface acoustic wave device for providing resonance of a surface acoustic wave having a wavelength λ can include a substrate and a piezoelectric layer implemented over the substrate to have a thickness greater than 2λ. The surface acoustic wave device can further include an interdigital transducer electrode formed over the piezoelectric layer to have mass density and thickness selected to provide a tuned mass-loading property for the thickness of the piezoelectric layer.
1 . A surface acoustic wave device for providing resonance of a surface acoustic wave having a wavelength λ, comprising:
a substrate;
a piezoelectric layer formed from LiTaO 3 or LiNbO 3 and disposed over the substrate, the piezoelectric layer having a thickness greater than or equal to 2λ; and
an interdigital transducer electrode formed over the piezoelectric layer, the interdigital transducer electrode having a mass density ρ greater than 1.50 g/cm 3 and a thickness greater than 0.036λ.
2 . The surface acoustic wave device of claim 1 wherein the substrate includes a quartz substrate.
3 . The surface acoustic wave device of claim 1 wherein the piezoelectric layer is implemented as a piezoelectric plate.
4 . The surface acoustic wave device of claim 1 wherein the interdigital transducer electrode has a metallization ratio (MR) of approximately 0.5, where MR=F/(F+G), F being a width of an electrode finger and G being a gap dimension between two interdigitized neighboring fingers of the interdigital transducer electrode.
5 . The surface acoustic wave device of claim 1 wherein the interdigital transducer electrode includes aluminum, titanium, magnesium, copper, nickel, silver, molybdenum, gold, platinum, tungsten, tantalum, hafnium, an alloy formed from a plurality of metals, or a structure having a plurality of layers.
6 . The surface acoustic wave device of claim 1 wherein the piezoelectric layer is a LiTaO 3 (LT) layer.
7 . The surface acoustic wave device of claim 6 wherein the LT layer is configured with Euler angles of (0−/+5°, 80 to 155°, 0−/+5°), (90−/+5°, 90°−/+5°, 0 to 180°).
8 . The surface acoustic wave device of claim 1 wherein the piezoelectric layer is a LiNbO 3 (LN) layer.
9 . The surface acoustic wave device of claim 8 wherein the LN layer is configured with Euler angles of (0−/+5°, 60 to 160°, 0−/+5°), (90−/+5°, 90°−/+5°, 0 to 180°).
10 . The surface acoustic wave device of claim 1 wherein the substrate is configured with Euler angles of (0+/−5°, θ, 35°+/−8°), (10°+/−+5°, θ, 42°+/−8°), (20°+/−5°, θ, 50°+/−8°), (0°+/−5°, θ, 0°+/−5°), (10°+/−5°, θ, 0°+/−5°), (20°+/−5°, θ, 0°+/−5°), (0°+/−5°, θ, 90°+/−5°), (10°+/−5°, θ, 90°+/−5°), (20°+/−5°, θ, 90°+/−5°), (90°+/−5°, 90°+/−5°, ψ), where each of θ and ψ has a value in a range 0° to 180°.
11 . A method for manufacturing a surface acoustic wave device that provides resonance of a surface acoustic wave having a wavelength λ, the method comprising:
forming or providing a substrate;
implementing a piezoelectric layer formed from LiTaO 3 or LiNbO 3 to be over the substrate, such that the piezoelectric layer has a thickness greater than or equal to 2λ; and
forming an interdigital transducer electrode over the piezoelectric plate, such that the interdigital transducer electrode has a mass density ρ greater than 1.50 g/cm 3 and a thickness greater than 0.036λ.
12 . The method of claim 11 wherein the forming or providing of the substrate includes forming or providing a quartz substrate.
13 . The method of claim 11 wherein the implementing of the piezoelectric layer includes implementing a piezoelectric plate.
14 . The method of claim 11 wherein the implementing of the piezoelectric layer includes forming or providing an assembly of a thick piezoelectric plate and a quartz plate, the quartz plate providing the substrate for the piezoelectric layer.
15 . The method of claim 14 wherein the implementing of the piezoelectric layer further includes performing a thinning process on the thick piezoelectric plate to provide the piezoelectric layer with the thickness greater than or equal to 2λ, such that the piezoelectric layer includes a first surface that engages with the quartz plate and a second surface, opposite from the first surface, resulting from the thinning process.
16 . The method of claim 11 wherein the implementing of the piezoelectric layer includes forming or providing an assembly of a thick piezoelectric plate and a handling substrate.
17 . The method of claim 16 wherein the implementing of the piezoelectric layer further includes performing a thinning process on the thick piezoelectric plate to provide a thinned piezoelectric plate with a thickness greater than or equal to 2λ, such that the thinned piezoelectric plate includes a first surface resulting from the thinning process and a second surface, opposite from the first surface, that engages the handling substrate.
18 . The method of claim 17 wherein the implementing of the piezoelectric layer further includes attaching a quartz plate to the first surface of the thinned piezoelectric plate such that the quartz plate provides the substrate.
19 . The method of claim 18 wherein the implementing of the piezoelectric layer further includes removing the handling substrate to expose the second surface of the thinned piezoelectric plate, and the thinned piezoelectric plate with the exposed second surface provides the piezoelectric layer.