ELECTROACOUSTIC RESONATOR WITH MODIFIED CHARGE TRAPPING REGION
Aspects are provided for electroacoustic resonators with modified charge trapping regions. In one aspect, a device includes a substrate layer, a trap rich layer disposed on the substrate layer, the trap rich layer having a thickness less than or equal to 200 nanometers (nm), a dielectric layer disposed on the trap rich layer, a piezoelectric layer disposed on the dielectric layer, and an interdigital transducer formed in a metal layer disposed on the piezoelectric layer.
1 . An device comprising:
a substrate layer;
a trap rich layer disposed on the substrate layer, the trap rich layer having a thickness less than or equal to 200 nanometers (nm);
a dielectric layer disposed on the trap rich layer;
a piezoelectric layer disposed on the dielectric layer; and
an interdigital transducer formed in a metal layer disposed on the piezoelectric layer.
2 . The device of claim 1 , wherein the thickness of the trap rich layer is greater than or equal to 10 nm.
3 . The device of claim 1 , wherein the trap rich layer comprises Aluminum Nitride.
4 . The device of claim 1 , wherein the trap rich layer comprises Si3N4.
5 . The device of claim 1 , wherein the trap rich layer comprises Al2O3.
6 . The device of claim 1 , wherein the dielectric layer comprises SiO2.
7 . The device of claim 1 , further comprising a SiON layer disposed on the dielectric layer.
8 . The device of claim 1 , wherein the substrate layer comprises polysilicon.
9 . The device of claim 1 , wherein the substrate layer comprises a low cost high resistance silicon.
10 . The device of claim 1 , wherein the thickness of the trap rich layer is selected to reduce out-of-band spurious modes while limiting the thickness of the trap rich layer.
11 . The device of claim 1 , wherein the interdigital transducer comprises:
a first busbar;
a second busbar; and
a first plurality of electrode fingers extending from the first busbar toward the second busbar and a second plurality of electrode fingers extending from the second busbar toward the first busbar in an interdigitated configuration with the first plurality of electrode fingers.
12 . An device comprising:
a resonator configured for resonance associated with a resonance wavelength, the resonator comprising:
a conductive substrate layer;
a trap rich layer disposed on the conductive substrate layer, the trap rich layer having a thickness less than or equal to 0.125 times the resonance wavelength;
a dielectric layer disposed on the trap rich layer;
a piezoelectric layer formed on the dielectric layer; and
an interdigital transducer formed in a metal layer disposed on the piezoelectric layer.
13 . The device of claim 12 , wherein the thickness of the trap rich layer is greater than or equal to 10 nm.
14 . The device of claim 12 , wherein the trap rich layer comprises Aluminum Nitride.
15 . The device of claim 12 , wherein the trap rich layer comprises Si3N4.
16 . The device of claim 12 , wherein the trap rich layer comprises Al2O3.
17 . A method comprising:
depositing a trap rich layer on a high resistance silicon substrate, wherein the trap rich layer is deposited to a thickness of less than or equal to 200 nanometers (nm);
forming a dielectric layer on the trap rich layer;
forming a piezoelectric layer on the dielectric layer; and
forming an interdigital transducer on the piezoelectric layer.
18 . The method of claim 17 , wherein the thickness of the trap rich layer is greater than or equal to 10 nm.
19 . The method of claim 17 , wherein the trap rich layer comprises Aluminum Nitride, Si3N4, or Al2O3.
20 . The method of claim 17 , further comprising:
forming a SiON layer disposed on the dielectric layer; and
forming the trap rich layer on a conductive substrate layer, the conductive substrate layer comprises a low cost high resistance silicon.