A structure and method for integrating a crystal resonator with a control circuit are disclosed. A lower cavity (120) is formed in a device wafer (100) containing the control circuit (110), and the device wafer (100) is then processed so that the lower cavity (120) is exposed from a back side (100D) of the device wafer (100). A substrate (600) in which an upper cavity (610) is formed at a corresponding location is bonded to the back side (100D) of the device wafer (100) in such a manner that the piezoelectric vibrator (500) is sandwiched between the device wafer (100) and the substrate (600), with the upper cavity (610) and the lower cavity (120) being aligned with each other on opposing side of the piezoelectric vibrator (500), thus resulting in the formation of the crystal resonator and simultaneously achieving the integration of the crystal resonator with the control circuit (110). This crystal resonator is more compact in size, less power-consuming and able to integrate with other semiconductor components with an increased degree of integration.

A method for integrating a crystal resonator with a control circuit and an integrated structure thereof. Integration of the crystal resonator with the control circuit (110) is accomplished by forming a lower cavity (120) in a device wafer (100) containing the control circuit (110) and an upper cavity (310) in a substrate (300), and by bonding the substrate (300) to the device wafer (100) in such a manner that the piezoelectric vibrator is sandwiched between the device wafer (100) and the substrate (300). A semiconductor die (700) can be further bonded to a back side of the same device wafer (100). This results in an increased degree of integration of the crystal resonator and allows on-chip modulation of its parameters. This crystal resonator is more compact in size, less power-consuming and easier to integrate with other semiconductor components with a higher degree of integration, compared with traditional crystal resonators.

A structure and method for integrating a crystal resonator with a control circuit are disclosed. The integration of the crystal resonator with the control circuit is accomplished by bonding a substrate (300) containing an upper cavity (310) to a device wafer containing both the control circuit and a lower cavity (120) so that a piezoelectric vibrator is sandwiched between the device wafer (100) and the substrate (300). In addition, a semiconductor die (700) may be bonded to a back side of the device wafer (100).

A radio frequency (RF) front-end (RFFE) device includes a die having a front-side dielectric layer on an active device. The active device is on a first substrate. The RFFE device also includes a microelectromechanical system (MEMS) device. The MEMS device is integrated on the die at a different layer than the active device. The MEMS device includes a cap layer composed of a cavity in the front-side dielectric layer of the die. The cavity in the front-side dielectric layer is between the first substrate and a second substrate. The cap is coupled to the front-side dielectric layer.

Techniques for improving acoustic wave device structures are disclosed, including filters, oscillators and systems that may include such devices. First and second layers of piezoelectric material may be acoustically coupled with one another to have a piezoelectrically excitable resonance mode. The first layer of piezoelectric material may have a first piezoelectric axis orientation, and the second layer of piezoelectric material may have a second piezoelectric axis orientation that substantially opposes the first piezoelectric axis orientation of the first layer of piezoelectric material. The first and second layers of piezoelectric material have respective thicknesses so that the acoustic wave device has a resonant frequency that is in a super high frequency band or an extremely high frequency band.

Techniques for improving Bulk Acoustic Wave (BAW) resonator structures are disclosed, including filters, oscillators and systems that may include such devices. First and second layers of piezoelectric material may be acoustically coupled with one another to have a piezoelectrically excitable resonance mode. The first layer of piezoelectric material may have a first piezoelectric axis orientation, and the second layer of piezoelectric material may have a second piezoelectric axis orientation that opposes the first piezoelectric axis orientation of the first layer of piezoelectric material. A top acoustic reflector including a first pair of top metal electrode layers may be electrically and acoustically coupled with the first layer of piezoelectric material to excite the piezoelectrically excitable main resonance mode at a resonant frequency.

Techniques for improving Bulk Acoustic Wave (BAW) resonator structures are disclosed, including filters, oscillators and systems that may include such devices. A first layer of doped piezoelectric layer material and a second layer of piezoelectric material may be acoustically coupled with one another to have a piezoelectrically excitable resonance mode. The first layer of doped piezoelectric material may have a first piezoelectric axis orientation, and the second layer of piezoelectric material may have a second piezoelectric axis orientation that substantially opposes the first piezoelectric axis orientation of the first layer of piezoelectric material. An acoustic reflector including a first pair of metal electrode layers may be electrically and acoustically coupled with the first layer of doped piezoelectric material and the second layer of piezoelectric material to excite the piezoelectrically excitable main resonance mode at a resonant frequency.

Techniques for improving acoustic wave device structures are disclosed, including filters and systems that may include such devices. An acoustic wave device may include a substrate. The acoustic wave device may include first and second layers of piezoelectric material acoustically coupled with one another, in which the first layer of piezoelectric material has a first piezoelectric axis orientation, and the second layer of piezoelectric material has a second piezoelectric axis orientation that substantially opposes the first piezoelectric axis orientation of the first layer of piezoelectric material. The acoustic wave device may include an interposer layer interposed between the first and second layers of piezoelectric material. The interposer may facilitate an enhancement of an electromechanical coupling coefficient of the acoustic wave device.

Techniques for improving Bulk Acoustic Wave (BAW) reflector and resonator structures are disclosed, including filters, oscillators and systems that may include such devices. First and second layers of piezoelectric material may be acoustically coupled with one another to have a piezoelectrically excitable resonance mode. The first layer of piezoelectric material may have a first piezoelectric axis orientation, and the second layer of piezoelectric material may have a second piezoelectric axis orientation that substantially opposes the first piezoelectric axis orientation of the first layer of piezoelectric material. A top acoustic reflector electrode may include a first pair of top metal electrode layers electrically and acoustically coupled with the first and second layer of piezoelectric material to excite the piezoelectrically excitable resonance mode at a resonant frequency of the BAW resonator. The resonant frequency of the BAW resonator may be in a super high frequency band or an extremely high frequency band.

Acoustic resonators and filter devices, and methods for making acoustic resonators and filter devices. An acoustic resonator includes a substrate having a surface and a single-crystal piezoelectric plate having front and back surfaces. The back surface is attached to the surface of the substrate except for a portion of the piezoelectric plate forming a diaphragm spanning a cavity in the substrate. A conductor pattern formed is formed on the front surface of the piezoelectric plate, including an interdigital transducer (IDT) with interleaved fingers of the IDT on the diaphragm. An insulating layer is formed between the piezoelectric plate and portions of the conductor pattern other than the interleaved fingers.