Acoustic resonator comprising acoustic redistribution layers and lateral features

An acoustic resonator device, comprising:

• a bottom electrode disposed over a substrate on an acoustic reflecting feature;
• a piezoelectric layer disposed on the bottom electrode;
• a top electrode disposed on the piezoelectric layer;
• an air-ring formed between the piezoelectric layer and the top electrode, the air-ring defining an outside boundary of a main membrane region;
• and
• a first frame formed between the piezoelectric layer and the top electrode,
• wherein at least one of the bottom electrode and the top electrode comprises a first conductive layer disposed adjacent to the piezoelectric layer and having a first acoustic impedance, and a second conductive layer disposed adjacent the first conductive layer and having a second acoustic impedance greater than the first acoustic impedance.

An bulk acoustic wave (BAW) resonator, comprising:

• a substrate;
• a bottom electrode disposed over the substrate on an acoustic reflecting feature;
• a piezoelectric layer disposed on the bottom electrode;
• a top electrode disposed on the piezoelectric layer;
• an air-ring defining an outside boundary of a main membrane region;
• and
• a frame formed on at least one of the piezoelectric layer, the bottom electrode and the substrate,
• wherein at least one of the bottom electrode and the top electrode comprises a plurality of conductive layers having different acoustic impedances, respectively, the lowest acoustic impedance being adjacent to the piezoelectric layer;
• and wherein the acoustic reflecting feature is one of an air-cavity or an acoustic mirror.