Saw filter having planar barrier layer and method of making

1. A surface acoustic wave (SAW) filter comprising:

a piezoelectric substrate;

a planar barrier layer disposed above the piezoelectric substrate; and

at least one metal conductor disposed in at least one trench in the planar barrier layer,

wherein each of the at least one metal conductors further comprises a stacked conductor including:

a diffusion barrier layer disposed above each of the at least one metal conductors; and

a metal layer disposed above the diffusion barrier layer,

wherein the metal layer is substantially horizontally aligned with the diffusion barrier layer, and

wherein the at least one metal conductor is buried in the piezoelectric substrate and the planar barrier layer.

2. The SAW filter of claim 1 , wherein the planar barrier layer comprises SiO 2 .

3. The SAW filter of claim 1 , wherein the piezoelectric substrate comprises LiNbO 3 .

4. The SAW filter of claim 1 , further comprising an SiO 2 layer disposed above the at least one metal conductor and the planar barrier layer.

5. The SAW filter of claim 1 , wherein the diffusion barrier layer comprises one of TaN/Ta, TaSiN/Ta, WN/Ta, and WN/Ru.

6. The SAW filter of claim 1 ,

wherein the metal conductor is substantially horizontally aligned with the diffusion barrier layer.

7. A surface acoustic wave (SAW) filter comprising:

a piezoelectric substrate;

a first SiO 2 planar barrier layer disposed above the piezoelectric substrate;

at least one Cu conductor buried in the planar barrier layer and the piezoelectric substrate;

a diffusion barrier layer disposed above each of the at least one Cu conductors;

at least one Al conductor disposed above the diffusion barrier layer; and

a second SiO 2 layer disposed above the first SiO 2 planar barrier layer and the at least one Al conductor.

8. The SAW filter of claim 1 , wherein the at least one metal conductor comprises Cu, and the metal layer comprises an Al layer.

9. A surface acoustic wave (SAW) filter comprising:

a piezoelectric substrate;

a planar barrier layer disposed above the piezoelectric substrate; and

at least one metal conductor disposed in at least one trench in the planar barrier layer, wherein each of the at least one metal conductors further comprises a stacked conductor in a damascene configuration, including:

a diffusion barrier layer disposed above the at least one metal conductor; and

a metal layer disposed above the diffusion barrier layer,

wherein the metal conductor, the diffusion barrier layer, and the metal layer are self-aligned, and

wherein the at least one metal conductor is buried in the piezoelectric substrate and the planar barrier layer.

10. The SAW filter of claim 9 , wherein the metal layer comprises Al, and wherein the at least one metal conductor comprises Cu.

11. The SAW filter of claim 9 , wherein the planar barrier layer comprises SiO 2 .

12. The SAW filter of claim 9 , wherein the piezoelectric substrate comprises LiNbO 3 .

13. The SAW filter of claim 9 , wherein the diffusion barrier layer comprises one of TaN/Ta, TaSiN/Ta, WN/Ta, and WN/Ru.