Bulk acoustic wave resonator and filter including the same
A bulk acoustic wave resonator includes a substrate, a first electrode and a second electrode formed on the substrate, and a piezoelectric layer provided between the first electrode and the second electrode. Either one or both of the first electrode and the second electrode include a molybdenum-tungsten alloy having a weight ratio of molybdenum to tungsten in a range of 3:1 to 1:3.
1. A bulk acoustic wave resonator comprising:
a substrate;
a first electrode and a second electrode formed on the substrate;
a seed layer formed between the substrate and at least one of the first and second electrodes, wherein the seed layer has a hexagonal close packing (HCP) structure, and comprises TiW; and
a piezoelectric layer disposed between the first electrode and the second electrode,
wherein either one or both of the first electrode and the second electrode comprise a molybdenum-tungsten alloy having a weight ratio of molybdenum to tungsten in a range of 3:1 to 1:3.
2. The bulk acoustic wave resonator of claim 1 , wherein the piezoelectric layer is formed of aluminum nitride.
3. The bulk acoustic wave resonator of claim 2 , wherein the piezoelectric layer includes a rare earth metal or transition metal.
4. The bulk acoustic wave resonator of claim 1 , wherein the weight ratio between the molybdenum and the tungsten in the molybdenum-tungsten alloy is in the range of 3:1 to 1:1.
5. The bulk acoustic wave resonator of claim 1 , wherein the molybdenum-tungsten alloy has a 110 crystal face orientation.
6. The bulk acoustic wave resonator of claim 1 , wherein the seed layer is formed between the substrate and the first electrode.
7. A filter comprising:
bulk acoustic wave resonators, at least one of the bulk acoustic wave resonators comprising:
a substrate;
a first electrode and a second electrode formed on the substrate;
a seed layer formed between the substrate and at least one of the first and second electrodes, wherein the seed layer has a hexagonal close packing (HCP) structure, and comprises TiW; and
a piezoelectric layer disposed between the first electrode and the second electrode,
wherein either one or both of the first electrode and the second electrode comprise a molybdenum-tungsten alloy having a weight ratio of molybdenum to tungsten in a range of 3:1 to 1:3.
8. The filter of claim 7 , wherein the piezoelectric layer is formed of aluminum nitride.
9. The filter of claim 8 , wherein the piezoelectric layer includes a rare earth metal or transition metal.
10. The filter of claim 7 , wherein the weight ratio between the molybdenum and the tungsten in the molybdenum-tungsten alloy is in the range of 3:1 to 1:1.
11. The filter of claim 7 , wherein the molybdenum-tungsten alloy has a 110 crystal face orientation.
12. The filter of claim 7 , wherein the bulk acoustic wave resonators are configured in a ladder type structure or a lattice type structure.
13. The filter of claim 7 , wherein the seed layer formed between the substrate and the first electrode.
14. A terminal, comprising:
a bulk acoustic wave resonator comprising a piezoelectric layer disposed between a first electrode and a second electrode, the first and second electrodes comprising a molybdenum-tungsten alloy having a composition that comprises 11-80 percent by weight (wt %) of tungsten; and
a seed layer formed between the substrate and at least one of the first and second electrodes, wherein the seed layer has a hexagonal close packing (HCP) structure, and comprises TiW.
15. The terminal of claim 14 , wherein the molybdenum-tungsten alloy has a composition that comprises 25-75 wt % of tungsten.