Patent ID: 9525399
Filing Date: 2016-12-20
CPC Classification: H03H

Claim Text:
1. A bulk acoustic wave (BAW) resonator, comprising: a cavity disposed in a substrate; a first electrode disposed over the cavity; a planarization layer disposed adjacent to but not over the first electrode, an edge of the planarization layer abutting an edge of the first electrode, the cavity having an edge and the planarization layer extending over the edge of the cavity and abutting a termination edge of the first electrode, and the first electrode terminating before the edge of the cavity at a distance equal to an odd integer multiple of one-quarter wavelength (λ/4) of a complex thickness-extensional eigenmode that exists outside an active region of the BAW resonator, wherein an upper surface of the planarization layer and an upper surface of the first electrode are substantially flush, and the termination edge is disposed at an angle relative to a surface of the substrate and the planarization layer has a termination edge disposed at a supplementary angle to the angle; a piezoelectric layer disposed over the first electrode and the planarization layer; and a second electrode disposed over the piezoelectric layer.