Bulk acoustic wave resonator having doped piezoelectric layer with improved piezoelectric characteristics
A bulk acoustic wave (BAW) resonator structure includes a first electrode disposed over a substrate, a piezoelectric layer disposed over the first electrode and a second electrode disposed over the first piezoelectric layer. The piezoelectric layer is formed of a piezoelectric material doped with one of erbium or yttrium at an atomic percentage of greater than three for improving piezoelectric properties of the piezoelectric layer.
1. A bulk acoustic wave (BAW) resonator structure, comprising:
a first electrode disposed over a substrate;
a piezoelectric layer disposed over the first electrode, the piezoelectric layer comprising a piezoelectric material doped with erbium at an atomic percentage of greater than three for improving piezoelectric properties of the piezoelectric layer; and
a second electrode disposed over the piezoelectric layer.
2. The BAW resonator according to claim 1 , wherein the piezoelectric material comprises aluminum nitride (AlN).
3. The BAW resonator according to claim 2 , wherein the erbium is incorporated into a crystal lattice of the AlN.
4. The BAW resonator according to claim 2 , wherein a concentration of the erbium is less than approximately 10 atomic percent of the piezoelectric material.
5. The BAW resonator according to claim 2 , wherein a concentration of the erbium is less than approximately 40 atomic percent of the piezoelectric material.
6. The BAW resonator according to claim 2 , wherein the piezoelectric layer is provided using a target formed of an alloy comprising aluminum and the erbium, and sputtering the aluminum alloy from the target over the first electrode using a plasma comprising nitrogen.
7. The BAW resonator according to claim 2 , wherein the piezoelectric layer is provided using a plurality of targets formed of aluminum and the erbium, respectively, and sputtering the aluminum and the erbium from the corresponding targets over the first electrode using a plasma comprising nitrogen.
8. The BAW resonator according to claim 1 , wherein the substrate defines a cavity over which the first electrode is formed.
9. The BAW resonator according to claim 1 , further comprising:
an acoustic reflector formed on the substrate between the substrate and the first electrode.
10. A bulk acoustic wave (BAW) resonator structure, comprising:
a first electrode disposed over a substrate;
a piezoelectric layer disposed over the first electrode, the piezoelectric layer comprising a piezoelectric material doped with yttrium at an atomic percentage of greater than three for improving piezoelectric properties of the piezoelectric layer; and
a second electrode disposed over the piezoelectric layer.
11. The BAW resonator according to claim 10 , wherein the piezoelectric material comprises aluminum nitride (AlN).
12. The BAW resonator according to claim 11 , wherein the yttrium is incorporated into a crystal lattice of the AlN.
13. The BAW resonator according to claim 11 , wherein a concentration of the yttrium is less than approximately 10 atomic percent of the piezoelectric material.
14. The BAW resonator according to claim 11 , wherein a concentration of the yttrium is less than approximately 40 atomic percent of the piezoelectric material.
15. The BAW resonator according to claim 11 , wherein the piezoelectric layer is provided using a target formed of an alloy comprising aluminum and the yttrium, and sputtering the aluminum alloy from the target over the first electrode using a plasma comprising nitrogen.
16. The BAW resonator according to claim 11 , wherein the piezoelectric layer is provided using a plurality of targets formed of aluminum and the yttrium, respectively, and sputtering the aluminum and the yttrium from the corresponding targets over the first electrode using a plasma comprising nitrogen.
17. The BAW resonator according to claim 10 , wherein the substrate defines a cavity over which the first electrode is formed.
18. The BAW resonator according to claim 10 , further comprising:
an acoustic reflector formed on the substrate between the substrate and the first electrode.