Atomic layer deposition encapsulation for acoustic wave devices
Acoustic wave devices and methods of coating a protective film of alumina (Al 2 O 3 ) on the acoustic wave devices are disclosed herein. The protective film is applied through an atomic layer deposition (ALD) process. The ALD process can deposit very thin layers of alumina on the surface of the acoustic wave devices in a precisely controlled manner. Thus, the uniform film does not significantly distort the operation of the acoustic wave device.
1. An acoustic wave device, comprising:
a piezoelectric substrate;
a set of metallic fingers formed in the piezoelectric substrate;
a first surface; and
a conformal film comprising alumina wherein the conformal film is formed on the first surface and has a thickness greater than or equal to about 50 Angstroms but less than or equal to about 300 Angstroms.
2. The acoustic wave device of claim 1 wherein the piezoelectric substrate includes a substrate surface and the set of metallic fingers include a metallic surface, the first surface comprising the substrate surface and the metallic surface.
3. The acoustic wave device of claim 2 wherein the set of metallic fingers comprises aluminum.
4. The acoustic wave device of claim 1 wherein the conformal film has a thickness greater than or equal to about 50 Angstroms but less than or equal to about 100 Angstroms.