US Patent 7327073 Acoustic resonators

An acoustic resonator of one inventive aspect includes a substrate, at least one generally crystalline primer layer provided on the substrate either directly or on top of one or more intermediate layers, a generally smooth and generally crystalline electrode layer provided on the primer layer, and a piezoelectric layer provided on the electrode layer. The primer layer, or at least one of the primer layers, has a crystallographic structure belonging to a first crystal system, and the electrode layer has a crystallographic structure belonging to a second crystal system which is different to the first system. The atomic spacing of the primer layer or at least one of said primer layers and that of the electrode matches to within about 15%.