Abstract: A piezoelectric layer is coupled to a bottom electrode in a method of fabricating a piezoelectric resonator. A bottom metal layer of a top electrode is deposited on the piezoelectric layer. The bottom metal layer is patterned and etched. A top metal layer of the top electrode is deposited on the etched bottom metal layer. The top metal layer is patterned and etched. An interconnect metal layer is deposited on the etched top metal layer and the piezoelectric layer such that the interconnect metal layer isolates the bottom metal layer from subsequent etch steps.

Abstract: A piezoelectric resonator includes a multi-layer top electrode configured such that a top most layer protects the underlying layers from subsequent etching, thereby preventing etch undercut of the top-most layer. In one embodiment, the multi-layer top electrode is configured as a bi-layer, so that the upper layer of the bi-layer stack protects all sides of the underlying layer from subsequent etch process steps. In an alternative embodiment, at least the perimeter of a multi-layer top electrode is completely covered with overlapping interconnect metal.

Abstract: A method of fabricating a BAW piezoelectric resonator, the method comprising the steps of providing a bottom electrode and a piezoelectric layer coupled to the bottom electrode. A bottom metal layer is deposited on a top electrode on the piezoelectric layer. The bottom metal layer is patterned and etched. A top metal layer of the top electrode is deposited on the etched bottom metal layer. The top metal layer is patterned and layered such that the top metal layer completely covers the top and sides of the bottom metal layer.