Raised and recessed frames on bottom and top plates of a BAW resonator

A film bulk acoustic wave resonator comprising:

• a piezoelectric film having a central region defining a main active domain in which a main acoustic wave is generated during operation;
• an upper electrode disposed on a top surface of the piezoelectric film;
• a lower electrode disposed on a lower surface of the piezoelectric film;
• a dielectric material layer disposed on a lower surface of the lower electrode;
• a carrier substrate disposed below a lower surface of the dielectric material layer;
• lower recessed frame regions disposed laterally on opposite sides of the central region, the dielectric material layer disposed on the lower surface of the lower electrode throughout the central region, the lower recessed frame regions, and throughout areas extending between the central region and the lower recessed frame regions, the lower recessed frame regions defined by regions of the dielectric material layer having a lesser thickness than a thickness of the dielectric material layer in the central region;
• and
• lower raised frame regions disposed laterally on opposite sides of the lower recessed frame regions from the central region, the lower raised frame regions defined by regions of the lower electrode having a greater thickness than a thickness of the lower electrode in the central region, the dielectric material layer extending throughout the lower raised frame regions and having a thickness in the lower raised frame regions less than the thickness of the dielectric material layer in the central region.