Abstract: A method for fabricating a Thin Film Bulk Acoustic Wave Resonator (FBAR). The method comprises the steps of: (A) forming a sacrificial layer comprising one of a metal and a polymer over a selected portion of a substrate; (B) forming a protective layer on the sacrificial layer and on selected portions of the substrate; (C) forming a bottom electrode layer on a selected portion of the protective layer; (D) forming a piezoelectric layer on a selected portion of the bottom electrode layer and on a selected portion of the protective layer; (E) forming a top electrode on a selected portion of the piezoelectric layer; and (F) removing the sacrificial layer to form an air gap. The use of a metal or a polymer material to form sacrificial layers has several advantages over the use of zinc-oxide (ZnO) to form such layers. In accordance with a further aspect of the invention, an FBAR is provided which includes a glass substrate.

Abstract: A method for fabricating a Thin Film Bulk Acoustic Wave Resonator (FBAR). The method comprises the steps of: (A) forming a sacrificial layer comprising one of a metal and a polymer over a selected portion of a substrate; (B) forming a protective layer on the sacrificial layer and on selected portions of the substrate; (C) forming a bottom electrode layer on a selected portion of the protective layer; (D) forming a piezoelectric layer on a selected portion of the bottom electrode layer and on a selected portion of the protective layer; (E) forming a top electrode on a selected portion of the piezoelectric layer; and (F) removing the sacrificial layer to form an air gap. The use of a metal or a polymer material to form sacrificial layers has several advantages over the use of zinc-oxide (ZnO) to form such layers. In accordance with a further aspect of the invention, an FBAR is provided which includes a glass substrate.

Abstract: A filter and a method for fabricating a filter comprising a thin film bulk acoustic wave resonator (FBAR), the FBAR including a plurality of layers of different materials deposited on top of each other and oh top of a substrate, the FBAR including a piezolayer sandwiched between a top electrode on the side of the piezolayer facing away from the substrate, and a bottom electrode on the side of the piezolayer facing the substrate, the FBAR further including an acoustic mirror made from a number of layers of different materials selected to provide in combination high reflectivity of sound energy, the method comprising the step of forming the bottom electrode from a material having a small acoustic impedance.

Abstract: A method for tuning a Thin Film Bulk Acoustic Wave Resonator (FBAR) located on a wafer. The FBAR comprises a plurality of layers having respective thicknesses. The FBAR exhibits at least one of a series resonance and a parallel resonance at respective frequencies that are a function of the thickness of at least one of the layers. A first step of the method includes measuring a frequency at which the FBAR exhibits one of a series resonance and a parallel resonance. A next step includes calculating an amount (A) by which the thickness of the at least one layer needs to be altered in order to minimize a difference between the measured frequency and a reference frequency. A further step includes altering the thickness of the at least one layer by the amount (A).

Abstract: A Thin Film Bulk Acoustic Wave Resonator (FBAR), comprising a top electrode layer, a substrate, an acoustic mirror that is formed atop the substrate, and a piezoelectric layer that is formed between the top electrode layer and the acoustic mirror. The acoustic mirror is comprised of a plurality of stacked layers. One of the stacked layers forms a bottom electrode layer. At least another one of the stacked layers comprises a polymer material. The piezoelectric produces vibrations in response to a voltage being applied between the top electrode and the bottom electrode. The acoustic mirror acoustically isolates these vibrations from the substrate. The polymer material is preferably an electronic grade polymer and has a capability of withstanding a deposition of the piezoelectric layer at an elevated temperature. The layers forming the acoustic mirror which do not comprise the polymer material comprise a high acoustic impedance material such as, by example, tungsten (W).