Method of designing a BAW resonator and filter and the resulting devices are provided. Embodiments include patterning a bottom electrode of a resonator, patterning a top electrode of the resonator, and intersecting area of the resonator, wherein the effective area includes a closed-loop contour line including a pulse function pattern with predefined amplitude, period and a number of repetitions of pulses along the closed-loop contour line.

Acoustic wave devices are disclosed. The devices include a substrate, a bi-layer reflector and an acoustic wave resonator. The bi-electric reflector is above the substrate and includes a first layer that has a first acoustic impedance, and a second layer that has a second acoustic impedance lower than the first acoustic impedance. The first layer has a first surface that includes a floating region that provides a ceiling of a cavity. The second layer is on top of the floating region of the first layer. The acoustic wave resonator is on top of the second layer of the bi-layer reflector. The acoustic wave resonator includes a piezoelectric layer, an electrode and a counter-electrode such that application of a radio frequency voltage between the electrode and the counter-electrode creates acoustic resonance waves in the piezoelectric layer.

A quartz crystal device includes a crystal element, a container, a conductive adhesive having flexibility, first pillow portions, and a second pillow portion. The first pillow portions hold the crystal element floated from an inner bottom surface of the container at the proximities of the two positions. The second pillow portion opposes the crystal element at a proximity of a second side. The second side opposes the first side of the crystal element. A height of the first pillow portion is represented as h and a length of the first pillow portion in a direction perpendicular to the first side is represented as X1, where the h is 20 μm to 50 μm and the X1 is 150 μm or less. The conductive adhesive covers at least a top surface and a side surface of the first pillow portion. The side surface is in a center side of the crystal element.

Aspects of this disclosure relate to bulk acoustic wave resonators with patterned mass loading layers. Two different bulk acoustic wave resonators of an acoustic wave filter and/or an acoustic wave die have respective patterned mass loading layers with different densities. The patterned mass loading layers contribute to the two different bulk acoustic wave resonators having different respective resonant frequencies. Related bulk acoustic wave devices, filters, acoustic wave dies, radio frequency modules, wireless communication devices, and methods are disclosed.

Aspects of this disclosure relate to bulk acoustic wave resonators. A bulk acoustic wave resonator includes a patterned mass loading layer that affects a resonant frequency of the bulk acoustic wave resonator. The patterned mass loading layer can have a duty factor in a range from 0.2 to 0.8 in a main acoustically active region of the bulk acoustic wave resonator. Related filters, acoustic wave dies, radio frequency modules, wireless communications devices, and methods are disclosed.

Aspects of this disclosure relate bulk acoustic wave resonators with a patterned mass loading layer at least contributing to a difference in mass loading between a main acoustically active region of the bulk acoustic wave resonator and a recessed frame region of the bulk acoustic wave resonator. Related methods of manufacturing can involve forming the patterned mass loading layer in the main acoustically active region and the recessed frame region in a common processing step such that the patterned mass loading layer has a higher density in the main acoustically active region than in the recessed frame region.

Aspects of this disclosure relate to methods of manufacturing bulk acoustic wave resonators. During a common processing step, a first patterned mass loading layer for a first bulk acoustic wave resonator is formed and a second patterned mass loading layer for a second bulk acoustic wave resonator is formed. The first patterned mass loading layer has a different density than the second patterned mass loading layer.

A vibrator, a vibrating element and a method for producing the vibrating element may include vibrating piece having a central portion and a peripheral portion. The vibrator, the vibrating element and the method may further include a pair of excitation electrodes provided on a first side and a second side of a main surface of the central portion. The vibrator, the vibrating element and the method may further include a pair of connection electrodes provided on the peripheral portion and electrically connected to the pair of excitation electrodes. The vibrator, the vibrating element and the method may further include a substrate configured to be connected to the pair of connection electrodes via an electrically-conductive holding member interposed therebetween and configured to support the vibration element in an excitable manner.

A bulk-acoustic wave resonator includes: a first electrode; a piezoelectric layer at least partially disposed on an upper portion of the first electrode; and a second electrode disposed to cover at least a portion of the piezoelectric layer. The second electrode includes a frame disposed at an edge of an active region of the bulk-acoustic wave resonator, and the first electrode, the piezoelectric layer and the second electrode are disposed to overlap one another at the edge of the active region. The frame includes a wall disposed at the edge of the active region and a trench formed on an internal side of the wall. An internal boundary line of the trench has a concave-convex shape in a plane parallel to an upper surface of the frame.

Acoustic wave devices are disclosed. The devices include a substrate, a bi-layer reflector and an acoustic wave resonator. The bi-electric reflector is above the substrate and includes a first layer that has a first acoustic impedance, and a second layer that has a second acoustic impedance lower than the first acoustic impedance. The first layer has a first surface that includes a floating region that provides a ceiling of a cavity. The second layer is on top of the floating region of the first layer. The acoustic wave resonator is on top of the second layer of the bi-layer reflector. The acoustic wave resonator includes a piezoelectric layer, an electrode and a counter-electrode such that application of a radio frequency voltage between the electrode and the counter-electrode creates acoustic resonance waves in the piezoelectric layer.