Top electrodes and dielectric spacer layers for bulk acoustic wave resonators

A method of fabrication of a bulk acoustic wave (BAW) resonator, the method comprising:

• forming a bottom electrode below a piezoelectric layer;
• selectively forming a dielectric spacer layer on one or more portions of the piezoelectric layer such that the piezoelectric layer is between the bottom electrode and the dielectric spacer layer;
• forming a top electrode on the dielectric spacer layer and the piezoelectric layer, the top electrode defining a central region and a border (BO) region, the BO region comprising an outer BO region and an inner BO region, the inner BO region being between the outer BO region and the central region, and the dielectric spacer layer being in contact with the piezoelectric layer under the outer BO region and the inner BO region;
• and
• forming a passivation layer in a conformal arrangement on the top electrode and along a sidewall of the BO region.

A bulk acoustic wave (BAW) resonator comprising:

• a bottom electrode;
• a piezoelectric layer on the bottom electrode;
• a top electrode on the piezoelectric layer, the top electrode defining a central region and a border (BO) region, the BO region comprising an outer BO region and an inner BO region, the inner BO region being between the outer BO region and the central region;
• a dielectric spacer layer arranged between the top electrode and the piezoelectric layer within the BO region, the dielectric spacer layer being in contact with the piezoelectric layer under the outer BO region and the inner BO region;
• and
• a passivation layer conformally arranged over the top electrode, wherein the passivation layer is inset from a peripheral edge of the piezoelectric layer.

A method of fabrication of a bulk acoustic wave (BAW) resonator, the method comprising:

• forming a bottom electrode below a piezoelectric layer;
• selectively forming a dielectric spacer layer on one or more portions of the piezoelectric layer such that the piezoelectric layer is between the bottom electrode and the dielectric spacer layer;
• forming a top electrode on dielectric spacer layer and the piezoelectric layer, the top electrode defining a central region and a border (BO) region, the BO region comprising an outer BO region and an inner BO region, the inner BO region being between the outer BO region and the central region, and the dielectric spacer layer being in contact with the piezoelectric layer under the outer BO region and the inner BO region;
• and
• forming a passivation layer in a conformal arrangement on the top electrode such that the passivation layer is inset from a peripheral edge of the piezoelectric layer.