66 results about "Piezoelectric mems" patented technology

The invention discloses a piezoelectric MEMS loudspeaker based on a folding ring between movable and fixed parts and application thereof, and belongs to the technical field of loudspeakers, the piezoelectric MEMS loudspeaker comprises a piezoelectric actuating assembly, a fixed assembly and a folding ring; the piezoelectric actuating assembly comprises a piezoelectric actuating composite layer, the piezoelectric actuating composite layer at least comprises a piezoelectric material layer, and the piezoelectric actuating composite layer generates mechanical displacement by applying voltage to drive the piezoelectric actuating assembly to vibrate so as to generate sound pressure; the fixing component can be a single structural component or a component with a plurality of structural components; the fixing assembly can be used for fixedly supporting the fixed supporting part of the piezoelectric actuating assembly, so that the non-fixed supporting part of the piezoelectric actuating assembly can freely move or vibrate; according to the invention, through the innovative design based on the folding ring between the moving part and the fixed part, the low-frequency vibration displacement of the vibrating diaphragm is remarkably improved, the problem that the low-frequency sound pressure of a traditional piezoelectric MEMS loudspeaker is insufficient is effectively solved, and the vibrating diaphragm can push air with a larger volume in a low-frequency band, so that a fuller low-frequency sound effect is obtained.

This application relates to the field of acoustic transducers, and particularly to a high-sensitivity MEMS acoustic device and its fabrication method. The high-sensitivity MEMS acoustic device is composed of an upper electrode layer, a piezoelectric layer, a lower electrode layer, a passive layer, an insulating layer, and a substrate connected in sequence. The multilayer composite film is radially symmetrical on the passive layer. A slit through the center of radial symmetry divides the composite film into several partitions. The upper and lower electrode layers of each partition are respectively provided with pads for signal extraction. The voltage signals of the pads in each partition are extracted through series or parallel connection. This application increases the output voltage by dividing the piezoelectric sensitive composite film into multiple sensitive regions and combining the sensitive regions in series, antiphase superposition, or other forms, thereby improving the sensitivity of the piezoelectric MEMS device.

A piezoelectric microelectromechanical systems microphone is provided comprising a substrate including at least one wall defining a cavity, the at least one wall defining an anchor region around a perimeter, a piezoelectric film layer forming a membrane, the piezoelectric film layer being supported at the anchor region by a spring region, and an electrode disposed over the piezoelectric film layer. A method of manufacturing such a MEMS microphone is also provided.

There is provided a piezoelectric microelectromechanical systems microphone comprising a sensor including at least one piezoelectric layer, at least one constraint in contact with the sensor at a position, such that the sensor is supported by the at least one constraint, and such that the sensor that the sensor has a membrane region to one side of the at least one constraint and a cantilevered region to the other side of the at least one constraint and a cavity defined at least partially by the at least one constraint. There is also provided a method of manufacturing the microphone.

A piezoelectric MEMS loudspeaker. The application discloses a MEMS structure, comprising: a substrate comprising an inner ring body and an outer ring body connected by a connecting rod, having a first cavity between the inner ring body and the outer ring body, and having a second cavity in the inner ring body; a piezoelectric composite vibration layer formed above the substrate, comprising an edge portion formed above the outer ring body and a center portion formed above the inner ring body, having a partition gap between the edge portion and the center portion. In summary, the piezoelectric MEMS loudspeaker provided by the application comprises an edge portion and a center portion, wherein the edge portion is used to generate a high-frequency sound pressure level, and the center portion is used to generate a low-frequency sound pressure level. The combination of the edge portion and the center portion makes the piezoelectric MEMS loudspeaker have a relatively flat sound pressure level frequency response curve with a wider range, thereby improving the auditory effect in the entire frequency band.

The application discloses a piezoelectric MEMS device preparation process and a device structure, and relates to the technical field of piezoelectric MEMS device preparation. The preparation process comprises the following steps: forming a groove near an edge region on a front surface of a substrate, depositing a sacrifice layer on the front surface of the substrate and patterning the sacrifice layer, so that the sacrifice layer is separated into a center region and an edge support region, forming a piezoelectric-buffer stack on the sacrifice layer and patterning the piezoelectric-buffer stack, and opening a release hole, the release hole being communicated with the center region of the sacrifice layer, introducing etching medium into the release hole to remove the center region of the sacrifice layer, and then etching a back cavity on the back surface of the substrate. The application limits the size of a diaphragm region through the groove, etches the back cavity of the substrate after the sacrifice layer is released, and compared with a traditional method of defining the diaphragm by etching the back cavity, the application completely avoids the size error of the diaphragm caused by the angle deviation of deep silicon etching, accurately locks the profile of the diaphragm, and greatly improves the size consistency and performance stability of devices in the same batch.

The application discloses a piezoelectric MEMS loudspeaker and a performance improvement method thereof, and belongs to the field of MEMS loudspeakers. The application first proposes a cantilever beam structure with a fixed support end perforation, and the structure can change the resonant frequency of the device. Further, based on the structure, the piezoelectric MEMS loudspeaker proposed in the application is composed of a plurality of triangular cantilever beams with different fixed support end perforations. Since the displacement of the triangular cantilever beam at the resonant frequency will be phase-inverted, the driving voltages of various triangular cantilever beams at both sides of the respective resonant frequencies should be opposite. Through the optimization design of the cantilever beam structure, compared with the traditional piezoelectric MEMS loudspeaker, the application can improve the sound pressure level output at the design frequency band without additional process difficulty, make the sound pressure level spectrum curve in the human ear hearing threshold frequency band relatively flat, realize compact layout, and has a good application prospect.

An acoustic sensor (e.g., for use in a piezoelectric MEMS microphone) includes a substrate and a cantilever beam attached to the substrate. The cantilever beam has a proximal portion attached to the substrate and extends to a distal tip at a free end thereof. The cantilevered beam has a multilayer structure with a plurality of piezoelectric layers and a plurality of metal electrode layers, at least a portion of one of the piezoelectric layers interposed between two metal electrode layers. One or more direct current voltage sources are electrically connected to one or more of the plurality of metal electrode layers and configured to apply a direct current bias voltage between at least two of the plurality of metal electrode layers to deflect the cantilever beam to at least partially counteract a deflection of the cantilever beam due to a residual stress in the cantilever beam.

Systems and techniques are provided for fabrication of piezoelectric MEMS devices to improve performance. For example, an apparatus can include a support stack including a substrate and a modified piezoelectric layer formed on or above the support stack. The modified piezoelectric layer includes a material structure modified by non-equilibrium thermal process to increase an average grain size within the material structure of the modified piezoelectric layer. In some implementations, the modified piezoelectric layer includes an aluminum nitride (AlN) crystalline lattice where at least a portion of aluminum in the AlN crystalline lattice are replaced with scandium forming aluminum scandium nitride (AlScN).

The application discloses a piezoelectric MEMS sensor, comprising: a substrate having a cavity; a vibration support layer formed above the substrate and covering the cavity; a lower electrode layer formed above the vibration support layer; a piezoelectric layer formed above the lower electrode layer; and an upper electrode layer having a groove and the groove divides the upper electrode layer into a center electrode layer and an outer ring electrode layer; wherein, in a first case, a first pad of the center electrode layer is used to output a first electric signal, and a second pad of the outer ring electrode layer is grounded to compensate for the voltage generated by the pyroelectric effect of the piezoelectric MEMS sensor; or in a second case, the first pad of the center electrode layer is used to output a second electric signal, the second pad of the outer ring electrode layer is used to output a third electric signal, and the lower electrode layer is grounded. The piezoelectric MEMS sensor effectively eliminates the voltage generated by the pyroelectric effect and improves the output voltage generated by the pressure difference.

The application belongs to the field of piezoelectric MEMS sensors, and relates to a piezoelectric MEMS ultrasonic sensor ranging circuit and a ranging method, which comprise an MCU, a high-voltage pulse driving circuit, an adaptive impedance matching network, a piezoelectric MEMS ultrasonic transducer, an active damping network, a preamplifier, a band-pass filter and a time gain controller; the high-voltage pulse driving circuit can greatly improve the emission sound pressure of the transducer and improve the measurement range; a controllable switch is designed at one end of the damping resistor, which can improve the emission efficiency and reduce the residual vibration, thereby reducing the measurement blind area; the adaptive impedance matching network is introduced, which can adjust the impedance inconsistent between different devices due to temperature and aging degree to the impedance matched with the ranging circuit, effectively improve the sensitivity and emission efficiency of the device, and the high sensitivity can improve the distance measurement precision of the ranging circuit.

The invention relates to the technical field of semiconductor technologies, in particular to a laminated piezoelectric MEMS structure and a preparation method thereof.The structure comprises a substrate, the substrate is provided with a front face and a back face which are opposite, a piezoelectric layer grows on the back face of the substrate, a substrate is bonded to the surface, away from the substrate, of the piezoelectric layer, and a back cavity penetrates through the substrate; the back cavity provides a vibration space for the vibrating diaphragm of the piezoelectric layer; the preparation method comprises the following steps: preparing a substrate having a front surface and a back surface opposite to each other, and growing a piezoelectric layer on the back surface of the substrate; preparing a substrate, and penetrating through the substrate to form a back cavity; the substrate is bonded to the surface, away from the substrate, of the piezoelectric layer, the back cavity is used for providing a vibration space for a vibrating diaphragm of the piezoelectric layer, the piezoelectric layer is grown through the glass substrate, the substrate serves as the substrate, the substrate can be directly and electrically connected with the first electrode and the second electrode respectively, additional packaging steps are not needed, and cost is saved.

The invention discloses a piezoelectric MEMS sound wave emission unit with broadband response and an MEMS device, and belongs to the technical field of micro electro mechanical systems. According to the piezoelectric MEMS sound wave emission unit, a composite design scheme of an annular piezoelectric driving structure and a high Young modulus film is adopted, and collaborative improvement of broadband and high sound pressure output is realized by optimizing a vibration coupling mechanism; the overall structural design is compatible with a standard MEMS (Micro Electro Mechanical System) process, and the working bandwidth and the sound pressure output performance are remarkably improved while the miniaturization of the device is maintained. The technical scheme is particularly suitable for the professional fields of ultrasonic detection / imaging, piezoelectric MEMS loudspeakers and the like, and a new technical path is provided for the development of high-performance piezoelectric micromechanical sound wave emission units.

According to an example aspect of the present invention, a method for manufacturing a piezoelectric MEMS transducer (1) is presented, the method comprising forming at least one cantilever (10) from a silicon-on-insulator (SOI) wafer, where the at least one cantilever (10) comprises a first sidewall, a second sidewall substantially parallel to the first sidewall, an aluminum nitride (AlN) layer (40) and a top electrode (50), and where the at least one cantilever (10) comprises a second sidewall substantially parallel to the first sidewall, the second sidewall, the AlN layer (40) and the top electrode (50) are electrically connected to each other. The top electrode (50) is connected to at least the first sidewall and / or the second sidewall via an AlN layer (40) therebetween.

The invention discloses a resonant piezoelectric MEMS microphone with a high signal-to-noise ratio and application thereof, and belongs to the technical field of MEMS acoustic sensors. According to the resonant piezoelectric MEMS microphone, the suspended annular-film composite structure with the two ends symmetrically and fixedly supported is adopted, the high Young modulus film is sensitive to tiny stress change caused by sound waves, the rigid boundary is restrained through the film, vibration caused by the sound waves is more efficiently transmitted to the annular piezoelectric structure, the energy loss of the sound waves can be effectively reduced, and the reliability of the microphone is improved. And the sensitivity of the resonant microphone is obviously improved. Besides, the suspended annular-film composite structure with two ends symmetrically and fixedly supported overcomes the problems of low Q value and large energy loss of a traditional resonant microphone (such as a cantilever beam structure), so that the resonant peak is sharper, and the microphone is more sensitive to tiny resonant frequency deviation caused by sound waves. Moreover, the larger the Q value is, the smaller the noise is, and compared with a traditional capacitive microphone and a traditional piezoelectric microphone, the SNR can be greatly improved in a low-frequency band.

The invention discloses a high-power low-intensity noise semiconductor laser packaging structure, which structurally comprises a heat management module, a heat sink base, a laser chip, a chip base, an optical coupling module, a packaging shell and an intensity noise processing module, wherein the laser chip, the chip base and the optical coupling module are positioned above the heat sink base; the intensity noise processing module is positioned in a non-light-path area of the inner side wall of the packaging shell; the laser chip is used as a laser emission core to provide initial laser; the optical coupling module performs beam shaping, feedback control and output coupling on laser emitted by the laser chip; the intensity noise processing module comprises a piezoelectric MEMS sensor and a photonic crystal electrical filter and is used for performing feedback suppression on intensity noise; and the thermal management module performs temperature control on the laser chip and the optical coupling module. Through the synergistic effect of controllable optical feedback of the optical coupling module and precise temperature control of the temperature controller, the semiconductor laser light source still keeps extremely low intensity noise under the high-power output condition, and good repeatability and high reliability are achieved.

Provided is a piezoelectric MEMS acoustic sensor, comprising a substrate, an inner electrode area, and an outer electrode area; the outer electrode area is located at the periphery of the inner electrode area; a lower support layer is provided on the top of the substrate, the inner electrode area and the outer electrode area are located on the lower support layer, and an upper support layer made of silicon-based material is provided on the top surfaces of the inner electrode area and the outer electrode area. The piezoelectric MEMS acoustic sensor has high sensitivity, strong resistance to hydrostatic pressure, and satisfies application requirements of different pressure resistance and operating water depth.

The invention provides a piezoelectric MEMS microphone and a preparation method thereof. The piezoelectric MEMS microphone comprises a substrate, a vibrating diaphragm, n cantilever beams and n first piezoelectric units. Wherein the substrate is provided with a cavity penetrating through the thickness direction, and the cavity is in a regular n prism shape; the vibrating diaphragm is a regular n-polygon, and the vibrating diaphragm and the substrate are coaxially arranged and are located on one side of the cavity; the n cantilever beams are distributed in a radiation array mode, one end of each cantilever beam is connected to the corresponding vertex position of the vibrating diaphragm, and the other end of each cantilever beam is connected to the middle position of the corresponding side line of the opening end of the cavity. And the n first piezoelectric units are respectively and correspondingly fixed on the n cantilever beams, and n is greater than or equal to 6. And when the sound pressure drives the vibrating diaphragm to generate vibration displacement along the thickness direction of the substrate to drive the cantilever beam to generate strain, the first piezoelectric unit positioned on the cantilever beam generates an electric signal through a piezoelectric effect. That is, the vibrating diaphragm enables each first piezoelectric unit located on the cantilever beam to generate a piezoelectric signal, thereby remarkably improving the sensitivity, frequency response and other performances of the microphone.

The application provides a piezoelectric MEMS hydrophone based on a bionic cochlea structure and a preparation method thereof. The preparation method comprises the following steps: forming a blocking layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer on a substrate, and forming a hard mask on the back of the substrate; performing photoetching on the upper electrode layer and then performing reactive ion beam etching to obtain a bionic cochlea structure pattern; performing photoetching and patterning on the piezoelectric layer to obtain a bionic cochlea structure pattern, and then etching to expose the lower electrode layer; forming a positive electrode and a negative electrode on the upper electrode layer; forming an etched hard mask; performing deep silicon etching steps on the back after photoetching and patterning to obtain a back bionic cochlea spiral cavity structure and in-situ arrayed cilia; etching and releasing the device; bonding the piezoelectric vector hydrophone with a PCB board, and wire-bonding the positive electrode and the negative electrode with the PCB board. The hydrophone has the characteristics of miniaturization, realizes wide-frequency underwater sound detection by using a bionic cochlea spiral diaphragm structure, and improves detection sensitivity by using in-situ integrated bionic cochlea cilia.

The application relates to the field of semiconductor devices and provides a piezoelectric MEMS resonator and an electronic component. The resonator comprises a cap wafer and a device wafer, the cap wafer comprises a cap layer, and the device wafer comprises: a substrate layer; a resonant cavity arranged on the substrate layer; a device silicon layer located on the upper side of the resonant cavity; a piezoelectric layer located on the upper side of the device silicon layer; a top electrode located on the upper side of the piezoelectric layer; and a first dielectric layer located on the upper side of the top electrode and covering the top electrode, the first dielectric layer is bonded to the cap layer, at least a part of the first dielectric layer bonded to the cap layer projects on the vertical direction and overlaps the projection of the top electrode on the vertical direction, and the upper surface of the at least part of the first dielectric layer bonded to the cap layer is in the same plane. In this way, the bonding properties of the cap wafer and the device wafer are improved by flattening the surface of the dielectric layer covering the top electrode, and a good bonding effect is ensured.

The invention discloses a miniature piezoelectric radiator based on multiple asymmetric cavities and virtual valves and application, and belongs to the technical field of radiators, the miniature piezoelectric radiator comprises a first cavity, a second cavity, at least one piezoelectric actuating structural member, a fixed support part, an inlet structural member or structural assembly and an outlet structural member or structural assembly; the first cavity and the second cavity form a basic peripheral frame of the radiator, and the first cavity, the second cavity, the inlet structural part and the outlet structural part or the structural assembly form an integral internal cavity. The piezoelectric actuating structural member is located in the formed whole internal cavity to form at least two internal multi-cavity structures, and the multiple cavities are cavities of an asymmetric structure; the piezoelectric MEMS device is small in size and light in weight, and can be integrated into a compact heat dissipation system. The method is particularly important for portable electronic equipment, and is beneficial to reducing the weight of the equipment, reducing the size and improving the user experience.

This invention relates to piezoelectric MEMS fans and their stress optimization design, fabrication, and chip in the field of MEMS actuators. The piezoelectric MEMS fan includes a support frame and at least one piezoelectric motion arm extending from the support frame. The piezoelectric motion arm has multiple stress-dispersing openings, and the distribution pattern of these openings is configured to disperse stress concentration within the piezoelectric motion arm during vibration. This invention designs a specific stress-dispersing opening pattern on the piezoelectric motion arm, which is optimized based on vibration stress field analysis. This pattern effectively disperses and releases the alternating stress borne by the motion arm during long-term high-frequency vibration, especially alleviating stress concentration in critical areas such as the root, thereby greatly suppressing the initiation and propagation of fatigue cracks and reducing performance degradation and the probability of fracture failure.

One or more embodiments of the present specification relate to the technical field of semiconductor processes, in particular to a piezoelectric MEMS chip based on electrode partition arrangement, the piezoelectric MEMS chip comprises a substrate, the substrate has a front surface and a back surface opposite to each other, the back surface of the substrate is provided with a back cavity, a piezoelectric layer grows on the front surface of the substrate, and the back surface of the substrate is provided with a back cavity. The piezoelectric layer comprises a bottom electrode, a piezoelectric film and a top electrode which are stacked in sequence, the bottom electrode is in contact with the front face of the substrate, and a vibrating diaphragm is arranged in the longitudinal projection range of a back cavity of the piezoelectric MEMS chip; the top electrode located in the vibrating diaphragm area comprises a central electrode arranged in the center of the vibrating diaphragm and an interdigital electrode surrounding the periphery of the central electrode. According to the embodiment of the invention, the top electrodes located in the diaphragm area adopt center-interdigital partition electrode arrangement, the limitation of single plane vibration can be exceeded, three-dimensional deformation under the combined action in multiple directions can be realized, the partition electrodes can cooperatively drive to disperse stress, and partition vibration distortion under large amplitude is reduced.

The embodiment of the application provides a piezoelectric MEMS microphone, comprising: a first piezoelectric cantilever beam and a second piezoelectric cantilever beam, wherein the first piezoelectric cantilever beam is used for converting a received sound signal into a first electric signal, and the second piezoelectric cantilever beam is used for converting the received sound signal into a second electric signal; the first electric signal and the second electric signal are opposite in phase, two groups of sensing signals are output through three channels, a differential subtraction circuit is passed through, a differential mode signal is enhanced, and a common mode noise signal is suppressed. Through the application, the problem of poor signal quality of the piezoelectric MEMS microphone is solved, and then the signal-to-noise ratio (SNR), noise resolution and other pickup characteristics of the piezoelectric MEMS microphone are improved.

A micro-electromechanical systems (MEMS) package comprising: a MEMS package comprising a substate and a lid coupled to the substrate; a piezoelectric valve coupled to the substrate and comprising a number of movable members operable to be deformed in opposite directions upon application of a voltage to modify an acoustic resistance of an acoustic port; and a first stopper defined by the substrate and a second stopper defined by the lid, the first stopper and the second stopper being aligned with the number of movable members and operable to prevent an undesirable deflection of the number of movable members.

The invention discloses a piezoelectric MEMS cantilever beam structure and electronic equipment, and relates to the technical field of micro electro mechanical systems. The piezoelectric MEMS cantilever beam structure comprises a substrate and a cantilever beam arranged on the substrate, the fixed end of the cantilever beam is fixedly connected with the top of the substrate, a stress concentration part is arranged on the side, close to the fixed end, of the free end of the cantilever beam, and the cantilever beam comprises at least two signal output electrode layers which are arranged in a stacked mode. A piezoelectric layer is arranged between every two adjacent signal output electrode layers; wherein the signal output electrode layer covers the stress concentration part of at least part of the cantilever beam. According to the piezoelectric MEMS cantilever beam structure, the deflection of the cantilever beam can be regulated and controlled by optimizing the structure of the cantilever beam, and the product yield and the low-frequency performance of the piezoelectric MEMS cantilever beam structure are improved.

A piezoelectric MEMS planar traveling wave resonator driving method based on an embedded feedback electrode relates to the technical field of traveling wave microactuators, and comprises the following steps: applying a preset input driving signal to a resonant device; collecting the output signals of the driving electrodes and the output signals of the isolated electrodes for multiple times, and calculating the phase difference between the two signals in sequence; taking an average value of the phase differences and comparing the average value with the initial phase difference; if the average phase difference is equal to the initial phase difference, the frequency of the input driving signal is kept unchanged; if the average phase difference is smaller than the initial phase difference, the frequency of the input driving signal is adjusted until the output phase difference is equal to the initial phase difference, and the frequency of the input driving signal is kept; if the average phase difference is larger than the initial phase difference, the frequency of the input driving signal is adjusted until the output phase difference is equal to the initial phase difference, and the frequency of the input driving signal is kept, and the problems that in a traditional resonator driving method, the precision of monitoring the resonance state is low, and the device structure is complex are solved.

The application provides a piezoelectric MEMS ultrasonic transducer simulating a Langevin vibrator and a preparation method thereof, which comprises, from bottom to top, a first silicon layer, a first electrode layer, a piezoelectric layer, a second electrode layer and a second silicon layer; wherein: a plurality of array units are arranged on the first silicon layer, the array units are separated by grooves, the grooves penetrate the piezoelectric layer and the second electrode layer, and the second electrode layer is divided into a plurality of second electrode layer units by the grooves; the second silicon layer comprises a plurality of stepped protruding structures, and the protruding structures are respectively located on the second electrode layer units; the protruding structure comprises coaxially arranged upper and lower second silicon layers, and the upper second silicon layer is away from the second electrode layer unit; and the area of the upper second silicon layer is smaller than that of the lower second silicon layer. 33 The piezoelectric MEMS ultrasonic transducer of the application can be used in small-size high-precision occasions such as intracardiac blood vessel imaging and fingerprint identification.

The invention discloses a high-sensitivity piezoelectric MEMS microphone, and belongs to the technical field of MEMS acoustic sensors. The structure comprises a support substrate provided with at least one cavity, wherein at least one cantilever beam unit is arranged above each cavity; the cantilever beam unit comprises at least one piezoelectric cantilever beam; one end part of the piezoelectric cantilever beam is a fixed supporting part, and the rest parts are free parts; the fixing and supporting part is connected to the supporting substrate, the free part is suspended above the cavity, and the junction of the fixing and supporting part and the free part is a fixing and supporting end; the piezoelectric cantilever beam comprises a piezoelectric film and a structural layer which are stacked, and the piezoelectric film covers the surface of the side, away from the supporting substrate, of the structural layer; a coplanar electrode is arranged on the surface of one side, deviating from the structural layer, of the piezoelectric film; and the coplanar electrode comprises at least two electrodes which are arranged in parallel along the length direction of the piezoelectric cantilever beam. By optimizing electrode configuration and material selection, the charge collection efficiency caused by mechanical strain is improved, and the electrical signal output performance of the device is enhanced.

A system for compensating for thermal stress in piezoelectric microelectromechanical systems devices can have a piezoelectric layer at least partially spanning a cavity such that it generates electrical signals when external forces cause the piezoelectric layer to vibrate with respect to the cavity. At least one electrode layer can include a conductive metal positioned adjacent the piezoelectric layer and configured as an electrode to accept the electrical signals. The piezoelectric layer and electrode layer can have an expected thermal stress tending to cause expected deflection even when external forces are not causing the piezoelectric layer to vibrate. A compensation layer can be positioned adjacent at least one of the piezoelectric layer and the at least one electrode layer and configured to counteract the expected deflection from the expected thermal stress.