Patent ID: 7895720

Claim:
A method of forming a thin film acoustic device having a piezoelectric film between a base electrode and a second electrode that enable application of an electric field to the piezoelectric film, the method comprising: (a) providing a substrate; (b) forming the base electrode as a stair-step shaped electrode by; (b1) depositing a plurality of conducting layers on the substrate wherein any odd conducting layer is composed of a first conducting material and any even conducting layer is composed of a conducting material, which is different from the first conducting material, such that adjacent layers of the odd and even conducting layers have different etch profiles from each other; (b2) selectively laterally etching one of the conducting layers; (b3) selectively laterally etching an other of the conducting layers directly below the one conducting layer; and (b4) stopping step (b3) at a point where the other of the conducting layers is etched less than the one conducting layer to form a step of the stair-step shaped electrode; (c) depositing the piezoelectric film on the base electrode; and (d) forming the second electrode over the piezoelectric film.