Method for fabricating piezoelectric resonators and product

A method for fabricating first and second piezoelectric resonators, the resonant frequency of the first resonator being shifted in frequency relative to the resonant frequency of the second resonator, the method comprising:

• fabricating a substrate having a top and bottom surface and having first and second top electrodes on the top surface of the substrate and having first and second bottom electrodes on the bottom surface of the substrate, the substrate including a layer of piezoelectric material, the first and second top electrodes comprising a primary layer of conducting material, and the first and second bottom electrodes comprising a primary layer of conducting material and the first top electrode additionally comprising a differential layer of conducting material,
• a portion of the first top electrode overlapping with a portion of the first bottom electrode and said overlapping portions defining the first resonator,
• a portion of the second top electrode overlapping with a portion of the second bottom electrode and said overlapping portions defining the second resonator,
• said differential layer of conducting material of said first top electrode shifting the resonant frequency of the first resonator relative to the resonant frequency of the second resonator,
• removing from the first top electrode those portions of the first electrode that overlap with the first bottom electrode and that are not composed of a portion of both the layer of conducting material and the differential layer of conducting material.

A piezoelectric resonator having specified resonant frequency fabricated by:

• fabricating a substrate having a top and bottom surface and having a top electrode on the top surface of the substrate and having a bottom electrode on the bottom surface of the substrate, the substrate including a layer of piezoelectric material, the top electrode comprising a primary layer of conducting material,
• a portion of the top electrode overlapping with a portion of the bottom electrode and said overlapping portions defining the resonator,
• adding a differential layer of conducting material on top of the top electrode, said differential layer of conducting material shifting the resonant frequency of the resonator to approximately the specified resonant frequency,
• removing from the top electrode those portions of the top electrode that overlap with a portion of the bottom electrode and that are not composed of a portion of both the primary layer of conducting material and the differential layer of conducting material whereby the remaining portion of the top electrode that overlaps with a portion of the bottom electrode has a substantially uniform thickness.

A device comprising first and second piezoelectric resonators, the resonant frequency of the first resonator being shifted in frequency relative to the resonant frequency of the second resonator, fabricated by:

• fabricating a substrate having a top and bottom surface and having first and second top electrodes on the top surface of the substrate and having first and second bottom electrodes on the bottom surface of the substrate, the substrate including a layer of piezoelectric material, the first and second electrodes comprising a primary layer of conducting material, and the first and second bottom electrodes comprising a primary layer of conducting material and the first top electrode additionally comprising a differential layer of conducting material,
• a portion of the first top electrode overlapping with a portion of the first bottom electrode and said overlapping portions defining the first resonator,
• a portion of the second top electrode overlapping with a portion of the second bottom electrode and said overlapping portions defining the second resonator,
• said differential layer of conducting material of said first top electrode shifting the resonant frequency of the first resonator relative to the resonant frequency of the second resonator,
• removing from the first top electrode those portions of the first electrode that overlap with the first bottom electrode and that are not composed of a portion of both the layer of conducting material and the differential layer of conducting material whereby the remaining portion of the first top electrode that overlaps with the first bottom electrode has a substantially uniform thickness.