LAMÉ MODE RESONATOR WITH ALUMINUM NITRIDE (AlN) MIRROR LAYER
Aspects include devices and methods for a resonator with an aluminum nitride mirror layer. Some aspects may include an aluminum nitride layer formed on or above a substrate, an electrode layer formed on or above the aluminum nitride layer opposite the substrate, a piezoelectric layer formed on the electrode layer, and an interdigital transducer formed on the piezoelectric layer.
1 . An electroacoustic structure comprising:
a substrate;
an aluminum nitride layer formed on or above the substrate;
an electrode layer formed on or above the aluminum nitride layer opposite the substrate;
a piezoelectric layer formed on the electrode layer; and
an interdigital transducer formed on the piezoelectric layer.
2 . The electroacoustic structure of claim 1 , wherein the piezoelectric layer comprises a crystalline structure selected to excite Lamé mode resonance.
3 . The electroacoustic structure of claim 2 , wherein the piezoelectric layer further comprises aluminum scandium-30 nitride (AlSc30N).
4 . The electroacoustic structure of claim 1 , wherein the electroacoustic structure has a resonance frequency between 3 gigahertz (GHz) and 8 GHz.
5 . The electroacoustic structure of claim 1 , wherein the aluminum nitride layer has a thickness approximately equal to a wavelength of a resonance frequency of the electroacoustic structure.
6 . The electroacoustic structure of claim 1 , wherein the interdigital transducer comprises a plurality of copper (Cu) electrode fingers.
7 . The electroacoustic structure of claim 1 , wherein the electrode layer comprises molybdenum (Mo).
8 . The electroacoustic structure of claim 1 , further comprising a silicon oxide (SiO2) layer formed on or above the aluminum nitride layer.
9 . The electroacoustic structure of claim 1 , wherein:
the electroacoustic structure is a resonator of a filter circuit within a wireless transceiver of a wireless communication device; and
the filter circuit is electrically coupled to an antenna of the wireless communication device.
10 . A method of fabricating an electroacoustic structure, the method comprising:
fabricating a silicon substrate;
forming an aluminum nitride layer on the silicon substrate; and
fabricating an electroacoustic stack on or above the aluminum nitride layer, the electroacoustic stack comprising a piezoelectric layer different from the aluminum nitride layer and a interdigital transducer, wherein the piezoelectric layer comprises a crystalline structure configured to excite a plate mode resonance.
11 . The method of claim 10 , wherein fabricating the electroacoustic stack comprises fabricating a lower interdigital transducer on the aluminum nitride layer;
forming the piezoelectric layer on or above the lower interdigital transducer; and
forming an upper interdigital transducer on the piezoelectric layer, where the interdigital transducer comprises the upper interdigital transducer and the lower interdigital transducer.
12 . The method of claim 10 , wherein fabricating the electroacoustic stack further comprises:
forming a silicon dioxide (SiO2) layer between the piezoelectric layer and the silicon substrate; and
forming an electrode layer between the SiO2 layer and the piezoelectric layer.
13 . The method of claim 12 , wherein the piezoelectric layer further comprises aluminum scandium-30 nitride (AlSc30N); and
wherein the electroacoustic structure has a resonance frequency between 3 gigahertz (GHz) and 8 GHz.
14 . The method of claim 13 , wherein the aluminum nitride layer is formed with a thickness approximately equal to a wavelength of the resonance frequency; and
wherein the electrode layer comprises molybdenum (Mo).
15 . An electroacoustic structure comprising:
a substrate;
an aluminum nitride layer formed on or above the substrate; and
an electroacoustic stack formed on or above the aluminum nitride layer, the electroacoustic stack comprising a piezoelectric layer different from the aluminum nitride layer and a interdigital transducer, the piezoelectric layer having a crystalline structure configured to excite a plate mode resonance.
16 . The electroacoustic structure of claim 15 , wherein the electroacoustic stack further comprises a silicon dioxide (SiO2) layer formed between the piezoelectric layer and the substrate.
17 . The electroacoustic structure of claim 16 , further comprising an electrode layer formed between the SiO2 layer and the piezoelectric layer.
18 . The electroacoustic structure of claim 17 , wherein the piezoelectric layer further comprises aluminum scandium-30 nitride (AlSc30N); and
wherein the electrode layer comprises molybdenum (Mo).
19 . The electroacoustic structure of claim 15 , wherein the interdigital transducer of the electroacoustic stack comprises a top interdigital transducer formed on or above the piezoelectric layer and a lower interdigital transducer formed under or below the piezoelectric layer.
20 . The electroacoustic structure of claim 19 , wherein a dielectric material is positioned between electrode fingers of the lower interdigital transducer.