WIDEBAND-ENABLED ELECTROACOUSTIC DEVICE
Certain aspects of the present disclosure can be implemented in an electroacoustic device. The electroacoustic device generally includes a substrate and one or more resonator structures disposed above the substrate. In some cases, each resonator structure of the one or more resonator structures includes a bulk acoustic resonator, an acoustic mirror disposed below the bulk acoustic resonator, and one or more porous material layers disposed below the acoustic mirror and above the substrate.
1 . An electroacoustic device comprising:
a substrate; and
one or more resonator structures disposed above the substrate, wherein each resonator structure of the one or more resonator structures comprises:
a bulk acoustic resonator;
an acoustic mirror disposed below the bulk acoustic resonator; and
one or more porous material layers disposed below the acoustic mirror and above the substrate.
2 . The electroacoustic device of claim 1 , wherein the bulk acoustic resonator comprises:
a top electrode;
a piezoelectric layer disposed below the top electrode; and
a bottom electrode disposed below the piezoelectric layer.
3 . The electroacoustic device of claim 2 , wherein the one or more resonator structures comprise a first acoustic filter and a second acoustic filter and wherein the first acoustic filter and the second acoustic filter share the piezoelectric layer.
4 . The electroacoustic device of claim 3 , wherein a first thickness of the shared piezoelectric layer in the first acoustic filter is different from a second thickness of the shared piezoelectric layer in the second acoustic filter.
5 . The electroacoustic device of claim 3 , wherein a thickness of the shared piezoelectric layer varies between two different levels and is in a range between about 100 nm and 600 nm.
6 . The electroacoustic device of claim 5 , wherein a difference in the thickness of the shared piezoelectric layer between the two different levels is about 300 nm.
7 . The electroacoustic device of claim 3 , wherein a first thickness of the top electrode of the first acoustic filter is different from a second thickness of the top electrode of the second acoustic filter.
8 . The electroacoustic device of claim 3 , wherein:
the first acoustic filter comprises a first porous material layer in the one or more porous material layers,
the second acoustic filter comprises a second porous material layer in the one or more porous material layers, and
the first porous material layer has a different porosity than the second porous material layer.
9 . The electroacoustic device of claim 1 , wherein at least one of the one or more porous material layers has a porosity between about 60 and 90 percent.
10 . The electroacoustic device of claim 9 , wherein the porosity of the at least one of the one or more porous material layers is between about 70 and 80 percent.
11 . The electroacoustic device of claim 1 , wherein at least one of the one or more porous material layers has a thickness between 50 nm and 500 nm.
12 . The electroacoustic device of claim 1 , wherein at least one of the one or more porous material layers is composed of porous silicon (Si) or porous silica (SiO 2 ).
13 . The electroacoustic device of claim 1 , wherein the one or more porous material layers comprise a first porous material layer and a second porous material layer, the second porous material layer being composed of a different material than the first porous material layer.
14 . The electroacoustic device of claim 1 , wherein at least one of the one or more resonator structures comprises a solidly mounted resonator (SMR).
15 . The electroacoustic device of claim 1 , wherein the one or more resonator structures comprise a first acoustic filter and a second acoustic filter and wherein a structure of the acoustic mirror of the first acoustic filter is the same as a structure of the acoustic mirror of the second acoustic filter.
16 . The electroacoustic device of claim 1 , wherein each resonator structure of the one or more resonator structures further comprises a trimming layer disposed above the bulk acoustic resonator, and wherein the trimming layer is composed of silicon nitride (Si 3 N 4 ).
17 . A wireless device comprising the electroacoustic device of claim 1 , the wireless device further comprising:
an antenna;
a transmit path; and
a receive path, wherein the electroacoustic device is coupled between the antenna and at least one of the transmit path or the receive path.
18 . A method of fabricating an electroacoustic device, comprising:
forming one or more resonator structures above a substrate, wherein each resonator structure of the one or more resonator structures comprises:
a bulk acoustic resonator;
an acoustic mirror disposed below the bulk acoustic resonator; and
one or more porous material layers disposed below the acoustic mirror and above the substrate.
19 . The method of claim 18 , wherein:
the bulk acoustic resonator comprises:
a top electrode,
a piezoelectric layer disposed below the top electrode, and
a bottom electrode disposed below the piezoelectric layer;
forming the one or more resonator structures comprises forming a first acoustic filter and forming a second acoustic filter; and
the first acoustic filter and the second acoustic filter share the piezoelectric layer.
20 . The method of claim 19 , wherein at least one of forming the first acoustic filter or forming the second acoustic filter comprises performing ion beam etching (IBE) on a respective portion of the shared piezoelectric layer.
21 . The method of claim 20 , wherein, based on the IBE performed on the shared piezoelectric layer, a first thickness of the shared piezoelectric layer in the first acoustic filter is different from a second thickness of the shared piezoelectric layer in the second acoustic filter.
22 . The method of claim 20 , wherein, based on the IBE performed on the shared piezoelectric layer, a thickness of the shared piezoelectric layer varies between two different levels and is in a range between about 100 nm and 600 nm.
23 . The method of claim 19 , wherein:
forming the first acoustic filter comprises forming a first porous material layer of the one or more porous material layers, and
forming the second acoustic filter comprises forming a second porous material layer of the one or more porous material layers.
24 . The method of claim 19 , wherein a structure of the acoustic mirror of the first acoustic filter is the same as a structure of the acoustic mirror of the second acoustic filter.
25 . The method of claim 18 , wherein at least one of the one or more porous material layers is composed of porous silicon (Si) or porous silica (SiO 2 ).
26 . The method of claim 18 , wherein at least one of the one or more porous material layers has a porosity between about 60 and 90 percent.
27 . A method for signal processing, comprising:
receiving a signal at an input of an electroacoustic device; and
processing the signal via the electroacoustic device, wherein the electroacoustic device comprises:
a substrate; and
one or more resonator structures disposed above the substrate, wherein each resonator structure of the one or more resonator structures comprises:
a bulk acoustic resonator;
an acoustic mirror disposed below the bulk acoustic resonator; and
one or more porous material layers disposed below the acoustic mirror and above the substrate.
28 . The method of claim 27 , wherein:
the bulk acoustic resonator comprises:
a top electrode,
a piezoelectric layer disposed below the top electrode, and
a bottom electrode disposed below the piezoelectric layer;
the one or more resonator structures comprise a first acoustic filter and a second acoustic filter;
the first acoustic filter and the second acoustic filter share the piezoelectric layer; and
a first thickness of the shared piezoelectric layer in the first acoustic filter is different from a second thickness of the shared piezoelectric layer in the second acoustic filter.
29 . The method of claim 28 , wherein:
a structure of the acoustic mirror of the first acoustic filter is the same as a structure of the acoustic mirror of the second acoustic filter, and
a thickness of the shared piezoelectric layer varies between two different levels and is in a range between about 100 nm and 600 nm.
30 . The method of claim 27 , wherein at least one of the one or more porous material layers has a porosity between about 60 and 90 percent and comprises porous silicon (Si) or porous silica (SiO 2 ).