Device having a titanium-alloyed surface
Disclosed is a device that includes a crystalline substrate and a patterned aluminum-based material layer disposed onto the crystalline substrate. The patterned aluminum-based material layer has a titanium-alloyed surface. A titanium-based material layer is disposed over select portions of the titanium-alloyed surface. In an exemplary embodiment, the patterned aluminum-based material layer forms a pair of interdigitated transducers to provide a surface wave acoustic (SAW) device. The SAW device of the present disclosure is usable to realize SAW-based filters for wireless communication equipment.
1. A device comprising:
a crystalline substrate;
a patterned aluminum-based material layer disposed onto the crystalline substrate, wherein the patterned aluminum-based material layer has a titanium-alloyed surface; and
a titanium-based material layer disposed between 10% and 90% of the titanium-alloyed surface.
2. The device of claim 1 wherein the patterned aluminum-based material layer forms a pair of interdigitated transducers to provide a surface acoustic wave device.
3. The device of claim 2 wherein the titanium-based material layer is disposed between 10% and 75% of the titanium-alloyed surface.
4. The device of claim 2 wherein the titanium-based material layer is disposed between 10% and 50% of the titanium-alloyed surface.
5. The device of claim 2 wherein the crystalline substrate is lithium tantalate (LiTaO 3 ).
6. The device of claim 2 wherein the crystalline substrate is lithium niobate (LiNbO 3 ).
7. The device of claim 2 wherein the patterned aluminum-based material layer is 99% aluminum.
8. The device of claim 2 wherein the patterned aluminum-based material layer is an aluminum alloy.
9. The device of claim 8 wherein the aluminum alloy is aluminum/copper.
10. The device of claim 2 wherein the titanium-based material layer is 99% titanium.
11. The device of claim 2 wherein the titanium-based material layer is a titanium alloy.
12. The device of claim 11 wherein the titanium alloy is titanium/aluminum.
13. The device of claim 2 wherein the patterned aluminum-based material layer has a pattern of interdigitated fingers.
14. The device of claim 2 further including an under bump metallurgy layer comprising a metal disposed directly onto portions of the titanium-alloyed surface of the patterned aluminum-based material layer not covered by the titanium-based material layer.
15. The device of claim 14 wherein contact resistivity between the under bump metallurgy layer metal and the titanium-alloyed surface is in the range of 1×10 −8 and 1×10 −7 ohm/cm 2 .
16. The device of claim 2 wherein the titanium-based material layer has a thickness that is in the range of 20 angstroms (Å) to 50 Å.
17. The device of claim 2 wherein the titanium-based material layer has a thickness that is in the range of 50 Å to 70 Å.
18. The device of claim 2 wherein the titanium-based material layer has a thickness that is in the range of 70 Å to 100 Å.
19. The device of claim 2 wherein the titanium-based material layer has a thickness that is in the range of 100 Å to 500 Å.