Patent ID: 7128941

Claim:
A method of fabricating a film bulk acoustic resonator (FBAR) device, said device comprising a series resonator and a shunt resonator, said method comprising the steps of: (a) preparing a substrate; (b) forming an insulating layer on the substrate; (c) forming a sacrificial layer on the insulating layer; (d) forming a plurality of sacrificial regions by selectively removing the sacrificial layer; (e) forming a membrane support layer on the insulating layer with the selectively removed sacrificial layer; (f) forming a membrane layer on the sacrificial regions and the membrane support layer; (g) forming a plurality of active regions in the membrane layer and on the sacrificial regions so that a thickness of the active region corresponding to the series resonator differs from a thickness of the active region corresponding to the shunt resonator; (h) forming lower electrodes on the membrane layer including the active regions; (i) forming an piezoelectric layer on the lower electrodes; (j) forming upper electrodes on the piezoeleciric layer; and (k) forming air-gaps by removing the sacrificial regions; wherein the thicknesses of the active regions of the membrane layer are less than those of other regions of the membrane layer.