RF resonator electrode and membrane combinations and method of fabrication
View Patent ↗A piezoelectric resonator membrane having a thickness in the range of 200 nm to 500 nm wherein the thickness may be controlled to within 1%; the membrane being sandwiched between electrodes to create a resonator, wherein at least one of the electrodes comprises aluminum thereby minimizing damping due to the weight of the electrode.
1. A resonator comprising a piezoelectric membrane sandwiched between upper and lower electrodes, wherein the lower electrode comprises aluminum, wherein the piezoelectric membrane is a single crystal, and wherein the piezoelectric membrane further includes Ba x Sr (1-x) TiO 3 .
2. A resonator comprising a piezoelectric membrane sandwiched between upper and lower electrodes, wherein the lower electrode includes aluminum, and wherein the piezoelectric membrane includes Ba x Sr (1-x) TiO 3 single crystal.
3. The resonator of claim 2 wherein the piezoelectric membrane has an <111> orientation.
4. The resonator of claim 1 wherein x is between 0.2 and 0.5 and is controlled to within a tolerance of ±1%.
5. The resonator of claim 1 further comprising an adhesion layer between the lower electrode and the piezoelectric membrane.
6. The resonator of claim 5 wherein the adhesion layer comprises titanium.
7. The resonator of claim 5 wherein the adhesion layer has a thickness in the range of 5 nm to 50 nm.
8. The resonator of claim 1 wherein the lower electrode is 100 nm±5 nm thick.
9. The resonator of claim 1 wherein both upper and lower electrodes comprise aluminum.