Abstract: A bulk acoustic wave (BAW) device comprises a layer stack including first and second electrodes, a first piezoelectric layer between the electrodes, and a second piezoelectric layer between the first piezoelectric layer and the second electrode. A polarization of a crystal structure of the second piezoelectric layer is opposite to a polarization of a crystal structure of the first piezoelectric layer to achieve higher order resonant frequencies in the BAW device by means other than merely thinning layers in the layer stack. In some examples, the BAW device is a two-terminal device and does not include a metal layer configured to be a third electrode. In some examples, the BAW device includes at least one intermediate layer between the first and second piezoelectric layers, and a total combined thickness of the at least one intermediate layer is less than 4% of a total thickness of the layer stack.

Abstract: An apparatus is disclosed for implementing a microacoustic filter with a cavity stack. In an example aspect, the apparatus includes a microacoustic filter with an electrode structure, a cavity stack, a buffer layer, and a piezoelectric layer. The cavity stack comprises a conductive layer, a substrate layer, and at least two pillars extending past a plane defined by a surface of the substrate layer and towards the conductive layer to form a cavity between the substrate layer and the conductive layer. The buffer layer is disposed between the conductive layer of the cavity stack and the electrode structure. The piezoelectric layer is disposed between the buffer layer and the electrode structure.

Abstract: A bulk acoustic wave (BAW) device with resonance-tuned layer stack is disclosed. The BAW device includes two acoustic resonators with top electrodes in different regions on a top side of a piezoelectric layer. The BAW device includes an acoustic mirror on a bottom side of the piezoelectric layer and a bottom electrode between the acoustic mirror and the piezoelectric layer. The piezoelectric layer includes a recess in a second region on the bottom side of the piezoelectric layer. The bottom electrode is disposed in the recess on the bottom side of the piezoelectric layer. A distance between a first top electrode in a first region and the bottom electrode may be greater than a distance between a second top electrode in the second region and the bottom electrode.

Abstract: In at least one embodiment, the electric component comprises a first BAW-resonator (1), a second BAW-resonator (2) electrically connected to the first BAW-resonator and a carrier substrate (3) with a top side (30) on which the BAW-resonators are arranged. The first and the second BAW-resonator each comprise a bottom electrode (11,21) and a top electrode (12,22). The bottom electrodes are in each case located between the carrier substrate and the respective top electrode. A first piezoelectric layer (13) is arranged between the top electrode and the bottom electrode of the first BAW-resonator and laterally protrudes from the first BAW-resonator. The second BAW-resonator is mounted on the first piezoelectric layer in a region laterally next to the first BAW-resonator and comprises a second piezoelectric layer (23) between its top electrode and its bottom electrode. The two piezoelectric layers may have different thickness to realize resonators with different resonance frequencies on the same die.

Abstract: In order to improve heat dissipation from electrical components with heat-generating component structures, it is proposed to provide a radiation layer with a large surface in the area of the component structures. Preferably, the radiation layer is very heat-conductive or in heat-conductive connection with the component structures.

Abstract: A method for forming an aluminum nitride layer (310, 320) comprises the provision of a substrate (100) and the forming of a patterned metal nitride layer (110). A bottom electrode metal layer (210) is formed on the exposed portions (101) of the substrate. An aluminum nitride layer portion (320) grown above the exposed portion (101) of the substrate (100) exhibits piezoelectric properties. An aluminum nitride layer portion (310) grown above the patterned metal nitride layer (110) exhibits no piezoelectric properties (310). Both aluminum nitride layer portions (320, 310) are grown simultaneously.

Abstract: In order to improve heat dissipation from electrical components with heat-generating component structures, it is proposed to provide a radiation layer with a large surface in the area of the component structures. Preferably, the radiation layer is very heat-conductive or in heat-conductive connection with the component structures.