The present disclosure relates to a Bulk Acoustic Wave (BAW) resonator with tunable electromechanical coupling. The disclosed BAW resonator includes a bottom electrode, a top electrode, and a multilayer transduction structure sandwiched therebetween. Herein, the multilayer transduction structure is composed of multiple transduction layers, and at least one of the transduction layers is formed of a ferroelectric material, whose polarization will vary with an electric field across the ferroelectric material. Upon adjusting direct current (DC) bias voltage across the bottom electrode and the top electrode, an overall polarization of the multilayer transduction structure and an overall electromechanical coupling coefficient of the multilayer transduction structure are capable of being changed. Once the change of the overall electromechanical coupling coefficient of the multilayer transduction structure is completed, the overall electromechanical coupling coefficient of the multilayer transduction structure will remain unchanged after removing the DC bias voltage.

A resonator includes a silicon substrate, a bottom electrode stacked on a portion of the silicon substrate, a piezoelectric layer covering the bottom electrode and another portion of the silicon substrate, a top electrode stacked on the piezoelectric layer, and a Bragg reflecting ring. The Bragg reflecting ring is formed on a side of the piezoelectric layer connected to the top electrode and surrounds the top electrode. The Bragg reflecting ring includes a Bragg high-resistivity layer and a Bragg low-resistivity layer alternately arranged along the radial direction of the Bragg reflecting ring. An acoustic impedance of the Bragg high-resistivity layer is greater than an acoustic impedance of the Bragg low-resistivity layer. The Bragg reflecting ring forms reflection surfaces to reflect the laterally propagating clutter waves, thereby suppressing the parasitic mode in the working frequency band, improving the frequency response curve of the resonator and the overall performance of the resonator.

An acoustic wave device includes a piezoelectric body made of lithium niobate and disposed directly or indirectly on a supporting substrate, and IDT electrode disposed directly or indirectly on the piezoelectric body. When the wavelength of an acoustic wave that is determined by a pitch of electrode fingers of the IDT electrode is denoted by λ, the thickness of the piezoelectric body is equal to or less than about 1λ. The acoustic wave device uses the plate wave S0 mode propagating in the piezoelectric body. The Euler angles of the lithium niobate are (0°±10°, θ, 90°±10°), provided that θ is from about 0° to about 180° inclusive.

An electroacoustic device includes, stacked in a direction a silicon-based substrate, a first electrode, a piezoelectric layer with the basis of a perovskite taken from among lithium niobate LiNbO3, lithium tantalum LiTaO3, or an Li(Nb,Ta)O3 alloy, on the first electrode, a second electrode disposed on the piezoelectric layer. Advantageously, the first electrode is made of a nitride-based electrically conductive refractory material, such as TiN, VN, TaN. The invention also relates to a method for producing such a device.

Provided is an acoustic resonator in a transverse excitation shear mode. The acoustic resonator comprises: an acoustic mirror (120), which comprises at least one first acoustic reflecting layer (121, 123, 125) and at least one second acoustic reflecting layer (122, 124), wherein the acoustic impedance of each first acoustic reflecting layer is less than that of each second acoustic reflecting layer; a piezoelectric layer (130), which is arranged on the acoustic mirror, and which comprises lithium niobate of a single crystal material and/or lithium tantalate of a single crystal material; electrode units (142, 143, 144), which are arranged on the piezoelectric layer (130) and are used for forming an electric field; and transverse reflectors (152, 154), which are arranged on the piezoelectric layer, are used for transversely reflecting acoustic waves, and can have a high electromechanical coupling coefficient and a high Q value at a frequency greater than 3 GHz.

Techniques for improving Bulk Acoustic Wave (BAW) reflector and resonator structures are disclosed, including filters, oscillators and systems that may include such devices. A Bulk Acoustic Wave (BAW) resonator of this disclosure may comprise a substrate and an active piezoelectric resonant volume. The active piezoelectric resonant volume of the Bulk Acoustic Wave (BAW) resonator may have a main resonant frequency. The active piezoelectric resonant volume of the Bulk Acoustic Wave (BAW) resonator may comprise first and second piezoelectric layers having respective piezoelectric axis that substantially oppose one another. A first patterned layer may be disposed within the active piezoelectric volume. This may, but need not facilitate suppression of spurious modes. The main resonant frequency of the Bulk Acoustic Wave (BAW) resonator may be in a super high frequency (SHF) band. The main resonant frequency of the Bulk Acoustic Wave (BAW) resonator may be in an extremely high frequency (EHF) band.

A micro-electrical-mechanical system (MEMS) resonator device includes at least one functionalization material arranged over at least a central portion, but less than an entirety, of a top side electrode. For an active region exhibiting greatest sensitivity at a center point and reduced sensitivity along its periphery, omitting functionalization material over at least one peripheral portion of a resonator active region prevents analyte binding in regions of lowest sensitivity. The at least one functionalization material extends a maximum length in a range of from about 20% to about 95% of an active area length and extends a maximum width in a range of from about 50% to 100% of an active area width. Methods for fabricating MEMS resonator devices are also provided.

A solidly mounted resonator having an electromagnetic shielding structure and a method for manufacturing the same. The solidly mounted resonator includes: a substrate; an acoustic-wave reflecting layer formed on the substrate; a resonance function layer formed on the acoustic-wave reflecting layer; and a metal shielding wall formed on the substrate, wherein the metal shielding wall surrounds an effective region in the acoustic-wave reflecting layer and the resonance function layer. The electromagnetic shielding structure is formed simultaneously with the resonator, and it is not necessary to provide an additional electromagnetic shielding device. An influence of an external or internal electromagnetic interference source on the resonator is avoided while ensuring a small dimension and a high performance of the resonator.

An integrated circuit (IC) resonator module for an IC package includes an acoustic resonator having a surface and a Bragg reflector adhered to the surface of the acoustic resonator. The Bragg reflector includes low impedance layers formed of a first material with a first acoustic impedance and a high impedance layer formed of a second material with a second acoustic impedance. The second acoustic impedance is greater than the first acoustic impedance. The Bragg reflector further includes a Bragg grating layer formed of randomly or periodically spaced patches of the second material separated by vias filled with the first material.

A bulk acoustic wave resonator device comprises a piezoelectric material layer, a first metal layer having a lower surface disposed on the upper surface of the piezoelectric material layer, a second metal layer having an upper surface disposed on the lower surface of the piezoelectric material layer, and an oxide raised frame disposed between the lower surface of the first metal layer and the upper surface of the second metal layer and surrounding a central active region of the bulk acoustic wave resonator device, the central active region having a first side and a second side, the oxide raised frame having a width on the first side of the central active region that is different from the width of the oxide raised frame on the second side of the central active region to improve an operating parameter of the bulk acoustic wave resonator.