CN118317237A

CN118317237A - MEMS piezoelectric transducer and electronic equipment

Info

Publication number: CN118317237A
Application number: CN202410418288.8A
Authority: CN
Inventors: 黄湘俊; 朱莉莉; 罗士忠; 肖晶晶; 龚芝伊
Original assignee: Hubei Jiufengshan Laboratory
Current assignee: Hubei Jiufengshan Laboratory
Priority date: 2024-04-08
Filing date: 2024-04-08
Publication date: 2024-07-09

Abstract

The application relates to the technical field of MEMS (micro electro mechanical systems) electronics, in particular to an MEMS piezoelectric transducer and electronic equipment. According to the MEMS piezoelectric transducer and the electronic equipment, the MEMS piezoelectric transducer comprises at least two transduction vibration components which are stacked along the axial direction of the substrate, the two adjacent transduction vibration components are connected through the connecting unit, so that the sensitivity of the MEMS can be improved under the condition that the area of the MEMS transducer is not increased, and in the application process, the two adjacent transduction vibration components move in the same direction at the same time, so that double-sided vibration can be realized, the transduction vibration components are more stable in moving, and noise reduction and vibration stroke improvement of the vibrating diaphragm are facilitated. When the transduction vibration component which is coupled and connected by adopting the flexible material is subjected to mechanical impact, falling and the like, the impact can be buffered, the damage risk is reduced, and the reliability of the device in working is improved.

Description

MEMS piezoelectric transducer and electronic equipment

Technical Field

The invention relates to the technical field of MEMS (micro electro mechanical systems) electronics, in particular to an MEMS piezoelectric transducer and electronic equipment.

Background

Compared with the traditional device, the novel MEMS device manufactured by utilizing the Micro-Electro-MECHANICAL SYSTEM MEMS technology processing technology has the characteristics of small size, thin thickness and the like in structure, the product can be produced in batches, the full-automatic assembly has the advantage of cost, and the device has the characteristics of MEMS technology, good performance consistency, low power consumption, easy integration, intelligent and the like in performance. Microphones in mobile communication devices such as cell phones and tablets have been miniaturized by MEMS technology. When the piezoelectric MEMS device is used as an actuator, an alternating electric field is applied to the piezoelectric MEMS device, the piezoelectric material generates strain to drive the thin film to vibrate, and if the generated displacement is larger, the piezoelectric MEMS device has larger emission sensitivity when being used as the actuator. When used as a sensor, the force is transmitted to the piezoelectric material causing deformation of the piezoelectric material, thereby outputting an alternating voltage across the electrodes of the piezoelectric MEMS device, which if the output alternating voltage is greater, indicates that the MEMS device has greater sensitivity for receiving as a sensor. MEMS audio transducers based on MEMS technology are of small size and can be used for MEMS speakers or microphones for applications such as generating or receiving music, speech, etc., and for MEMS ultrasound transducers such as ultrasound detection.

However, the device formed by the silicon substrate and the piezoelectric film material is difficult to be compatible with both small size and high performance, so that how to obtain high transmitting or/and receiving sensitivity in the full frequency range (20 Hz-20 KHz) and even exceeding 20KHz under the small size, so that the requirement of meeting the application performance index of the MEMS acoustic transducer is a technical problem to be solved urgently.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a MEMS piezoelectric transducer and an electronic device.

In a first aspect, an embodiment of the present application provides a MEMS piezoelectric transducer, the MEMS piezoelectric transducer comprising:

A substrate provided with a cavity penetrating along the axis direction;

The at least two transduction vibration assemblies are stacked along the axial direction of the substrate, and the two adjacent transduction vibration assemblies are connected through the elastic connecting unit.

With reference to the first aspect, the transducing vibration assembly includes:

a transduction diaphragm;

The piezoelectric composite layer unit is arranged on the upper surface and/or the lower surface of the transduction diaphragm.

With reference to the first aspect, at least one transduction diaphragm in one transduction vibration assembly of the two adjacent transduction vibration assemblies has a spring structure; the spring structure is obtained by etching the transduction diaphragm through an MEMS etching process to generate a slotting gap.

With reference to the first aspect, the elastic connection unit includes a frame made of a flexible material and an elastic connection member; the elastic connecting piece is used for connecting the middle parts of two adjacent transduction vibration components; the frame is used for connecting the edges of two adjacent transduction vibration components.

With reference to the first aspect, the piezoelectric composite layer unit is a single-piezoelectric layer structure or a double-piezoelectric layer structure or a multi-piezoelectric layer structure.

In combination with the first aspect, the MEMS piezoelectric transducer includes a first transduction vibration assembly and a second transduction vibration assembly, the first transduction vibration assembly is disposed above the second transduction vibration assembly, and adjacent surfaces of the first transduction vibration assembly and the second transduction vibration assembly are connected by a connection unit to form a transduction cavity.

With reference to the first aspect, the transduction diaphragm of the second transduction vibration assembly is provided with a gap, and the transduction cavity is communicated with the cavity through the gap.

With reference to the first aspect, the first transduction vibration assembly includes: the first passivation layer film, the silicon supporting layer and the second passivation layer film are sequentially arranged from bottom to top.

With reference to the first aspect, the second transduction vibration assembly includes: a BOX layer, an SOI top silicon layer and a third passivation layer film which are sequentially arranged from bottom to top;

two ends of the second transduction vibration component are fixedly connected with the substrate respectively, and a spring structure in the middle of the second transduction vibration component is connected with the first transduction vibration component through a connecting unit.

In a second aspect, the present application provides an electronic device comprising the MEMS piezoelectric transducer described above.

The embodiment of the application has the following beneficial effects: according to the MEMS piezoelectric transducer and the electronic equipment, the MEMS piezoelectric transducer comprises at least two transduction vibration components which are stacked along the axial direction of the substrate, the two adjacent transduction vibration components are connected through the elastic connection unit, so that the transmitting or/and receiving sensitivity of the MEMS transducer can be improved under the condition that the area of the MEMS transducer is not increased, in the application process, the two adjacent transduction vibration components move in the same direction at the same time, double-sided vibration can be realized, the transduction vibration components are smoother in moving, noise reduction and vibration stroke improvement of the vibrating diaphragm are facilitated, and the transduction vibration components which are connected through flexible coupling can buffer impact when suffering mechanical impact, falling and the like, so that the damage risk is reduced, and the reliability of the device in working is improved.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

In order to make the above objects, features and advantages of the present invention more comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are some embodiments of the invention and that other drawings may be obtained from these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural diagram of a MEMS piezoelectric transducer according to embodiment 1 of the present invention;

FIG. 2 is a schematic view of another MEMS piezoelectric transducer according to embodiment 2 of the present invention;

FIG. 3 is a schematic view of another MEMS piezoelectric transducer according to embodiment 3 of the present disclosure;

FIG. 4 is a schematic view of another MEMS piezoelectric transducer according to embodiment 4 of the present invention;

FIG. 5 is a schematic view of another MEMS piezoelectric transducer according to embodiment 5 of the present invention;

FIG. 6 is a schematic view of another MEMS piezoelectric transducer according to embodiment 6 of the present disclosure;

FIG. 7 is a schematic diagram of a prior art simulation effect with a single transducing vibration assembly actuator;

fig. 8 is a schematic diagram of simulation results of an actuator with two transducing vibration assemblies according to the present application.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In order to facilitate understanding of the present embodiment, the application scenario and the design concept of the embodiment of the present application are briefly described below.

Devices based on silicon substrates and piezoelectric thin film materials are difficult to achieve both small size and high performance, so how to improve sound pressure level and sensitivity under small size and low driving to meet the application performance index of the MEMS acoustic transducer is a technical problem to be solved.

The embodiment of the application provides an MEMS piezoelectric transducer and electronic equipment.

Example 1

The present application provides a MEMS piezoelectric transducer comprising: a substrate 01 and a transducing vibration assembly.

The substrate 01 is provided with a cavity 60a penetrating in the axial direction.

At least two transduction vibration assemblies are arranged in a stacked manner along the axial direction of the substrate 01, and two adjacent transduction vibration assemblies are connected through elastic connection units (combined with 30a, 30b and 30c in fig. 1).

According to the MEMS piezoelectric transducer provided by the application, under the condition that the area of the MEMS piezoelectric transducer is not increased, namely, the vibration amplitude is not changed under the excitation of piezoelectric excitation, through the at least two transduction vibration components which are arranged in a stacked manner, the at least two transduction vibration components which are connected in a cascading manner obtain larger deflection, so that the pushed air quantity improves the sound pressure level of the MEMS piezoelectric transducer, improves the sensitivity, and can reduce the area of the MEMS piezoelectric transducer under the condition of outputting the same sound pressure level based on the principle so as to meet the miniaturized use requirement.

The substrate may be silicon, silicon On Insulator (SOI), glass, sapphire, quartz, glass, etc. The side of the substrate 01 adjacent to the transducing vibration assembly is parallel to the transducing vibration assembly. In actual manufacturing processes, the resonant frequency of the MEMS transducer can be changed by designing different sized cavity structures 60 a.

With reference to the first aspect, the transduction vibration assembly includes a transduction diaphragm and a piezoelectric composite layer unit.

The transduction diaphragm is composed of a top silicon layer of the SOI silicon wafer and insulating layers arranged above and below the top silicon layer of the SOI silicon wafer, and as an implementation mode, the top silicon layer of the SOI silicon wafer can be replaced by a flexible film.

In this embodiment, the top silicon layer of the SOI silicon wafer is a sandwich structure, and includes two rigid films and a flexible film, where the flexible film is disposed between the rigid films on both sides.

In this embodiment, the piezoelectric composite layer unit may be disposed on a single side surface of the transduction diaphragm, such as an upper surface or a lower surface, and may also be disposed on both side surfaces of the transduction diaphragm; the arrangement position of the piezoelectric composite layer unit can be the edge, the central area and other arbitrary positions of the transduction diaphragm. The specific setting position is adjusted according to the use requirement, and is not limited herein.

The piezoelectric composite unit can deform the transduction diaphragm under the drive of a piezoelectric signal, so that sound waves are generated.

It is worth to say that, through the electrical parallel connection between a plurality of cascade piezoelectric composite layer units, can improve the vibration stroke of transduction vibrating diaphragm, further promote the sound pressure level.

Wherein, part or all of the edges of the transduction diaphragms at the bottom are anchored on the substrate 01, and each transduction diaphragm can be vertically offset along the axial direction (the height direction shown in fig. 1) of the substrate 01; the two adjacent transduction vibration components are connected through the elastic connection unit, the elastic connection unit is a spring in the embodiment, the structural stability of the MEMS piezoelectric transducer can be improved, the vibration stroke of the transduction vibrating diaphragm in the transduction vibration component is increased, double-sided vibration can be realized to the same direction motion so as to meet the requirement of thinning, and when the vibration component is subjected to mechanical impact, falling and other conditions, the transduction vibration component coupled through the flexible material can buffer impact, so that the damage risk is reduced, and the use reliability is improved.

In the case that the piezoelectric composite layer unit is of a single piezoelectric layer structure, the piezoelectric composite layer unit is composed of two electrode layers and a piezoelectric layer disposed between the two electrode layers.

In the case that the piezoelectric composite layer unit is of a double-piezoelectric layer structure, the piezoelectric composite layer unit is composed of three electrode layers and piezoelectric layers arranged between two adjacent electrode layers.

In the case that the piezoelectric composite layer unit is of a multi-piezoelectric layer structure, the piezoelectric composite layer unit is composed of N electrode layers and piezoelectric layers arranged between two adjacent electrode layers.

The three structures are selected according to the needs in practical application, and are not limited herein.

The piezoelectric layer may be made of single crystal piezoelectric material or polycrystalline piezoelectric material, such as single crystal ALN, doped ALN, single crystal PZT, doped PZT, znO, barium titanate, lead titanate, or other piezoelectric material. The thickness of the piezoelectric layers is generally 0.2-5um, and the thickness of each piezoelectric layer can be inconsistent and can be selected according to practical conditions.

The electrode layer may be made of monocrystalline piezoelectric material, polycrystalline piezoelectric material, mo, pt, al, cu, LNO or other metal or nonmetal conductive film, monocrystalline metal material or alloy material, etc. The thickness of the electrode layers is generally 0.05-3um, and the thickness of each electrode layer can be inconsistent, and the electrode layers are selected according to practical conditions.

The thickness of the transduction diaphragm is generally 0.5-50um, preferably 1-5um. The selection may be made according to actual use requirements, design dimensions, performance parameters, and is not limited herein.

Referring to fig. 1, an embodiment of the present application provides a MEMS piezoelectric transducer, wherein a substrate 01 is an SOI substrate, the substrate 01 has a cavity 60a, and a first transduction vibration assembly is disposed on the substrate 01, and the first transduction vibration assembly includes a transduction diaphragm 40a and piezoelectric composite layer units 20c and 20d disposed on the transduction diaphragm 40 a.

A second transduction vibration assembly is disposed above the first transduction vibration assembly, the second transduction vibration assembly including a transduction diaphragm 40b and piezoelectric composite layer units 20a, 20b disposed on the transduction diaphragm 40 b. Wherein the piezoelectric composite layer unit 20b has a single piezoelectric layer structure, 21-1 is a top electrode layer, 21-2 is a piezoelectric layer, and 21-3 is a bottom electrode layer.

The middle parts of the adjacent surfaces of the first transduction vibration assembly and the second transduction vibration assembly are connected through a connecting unit 30 b; the two ends of the adjacent surfaces of the first transduction vibration assembly and the second transduction vibration assembly are connected and anchored to the substrate 01 through the rims 30a and 30 c. Wherein 30a-30c may be flexible dry film materials. The flexible dry film material can also be used to cover the slot 50a-50d with a slot width greater than 50a-50 d. The first transducing vibration assembly is connected with the second transducing vibration assembly to form a transducing cavity 60b.

When the cavity size 60a in the substrate 01 and the size of the MEMS transducer are determined, and the lower the first-order resonant frequency of the MEMS transducer is required, the smaller the thickness of the selected transduction membrane is; the higher the first order resonant frequency required, the greater the thickness of the transduction membrane should be selected. The mechanical resonance point of the MEMS transducer can be in the audio frequency range or beyond 20kHz, even in the ultrasonic frequency range, by adjusting the thickness of the transduction diaphragm and the size of the cavity 60a in the substrate 01 during the actual design, production and manufacturing process.

In combination with the first aspect, one or both of the two adjacent transduction vibration components has a spring structure, and the spring structure is obtained by etching the transduction vibration film through an MEMS etching process to generate a slotted gap.

The transduction diaphragm is provided with a sandwich structure consisting of two layers of rigid films and a flexible film, and the flexible film is arranged between the two rigid films. Therefore, compared with the rigid diaphragm in the prior art, the transduction diaphragm has certain elasticity and can reduce the rigidity. The energy-conversion diaphragm is etched with a slotting gap through a DRIE etching process, so that the internal residual stress of the energy-conversion diaphragm caused by an MEMS process can be reduced, and a spring structure is obtained after slotting the gap. Therefore, when the MEMS transducer is subjected to conditions such as mechanical impact and falling, the impact can be buffered through the spring structure, the damage risk is reduced, and the reliability of the MEMS transducer can be improved.

As an implementation manner, the transducer assembly diaphragms in one transducer assembly (such as the lower transducer assembly or the upper transducer assembly) of the two adjacent transducer assemblies have spring structures, and as the number of transducer assemblies with spring structures increases, the use reliability of the MEMS piezoelectric transducer increases, and in practical application, the transducer assemblies with elastic structures can be processed and selected according to the use requirements, which is not limited herein.

In combination with the first aspect, the MEMS piezoelectric transducer includes a first transduction vibration assembly and a second transduction vibration assembly, the first transduction vibration assembly is disposed above the second transduction vibration assembly, and adjacent surfaces of the first transduction vibration assembly and the second transduction vibration assembly are connected by an elastic connection unit to form a transduction cavity.

In combination with the first aspect, after a slit is formed in the transduction diaphragm of the second transduction vibration assembly, a transduction space cavity surrounded by the two transduction vibration assemblies and the elastic connection unit is communicated with the cavity 60a in the substrate 01 through the slit.

It will be appreciated that after the transduction diaphragm of the second transduction vibration assembly has no slit, the transduction space cavity defined by the two transduction vibration assemblies and the elastic connection unit is isolated from the cavity 60a in the substrate 01.

The first passivation layer film and the second passivation layer film are used for electrical isolation and protection, and the materials of the first passivation layer film and the second passivation layer film can be PI, alumina, silicon dioxide, aluminum nitride and the like.

two ends of the second transduction vibration assembly are fixedly connected with the substrate 01 respectively, and a spring structure in the middle of the second transduction vibration assembly is connected with the first transduction vibration assembly through an elastic connection unit.

In a second aspect the present application provides a MEMS piezoelectric device comprising a MEMS piezoelectric transducer as described above.

The elastic connection unit can be a hard substrate or a flexible substrate, and the elastic connection unit can be made of monocrystalline silicon, polycrystalline silicon, polymer PI, PIV-3, SU8, PDMS, PARYLENCE C, flexfiner SA, organic or inorganic compounds, or the like.

In this embodiment, the MEMS piezoelectric device may be a MEMS piezoelectric device, a piezoelectric actuator piezoelectric sensor, and a piezoelectric transducer; when the MEMS actuator is used, the MEMS actuator can be a MEMS loudspeaker, a MEMS micropump, a MEMS micro mirror, a MEMS switch and the like. When the MEMS sensor is used, the MEMS sensor can be a MEMS microphone, a MEMS hydrophone, a MEMS pressure sensor, a MEMS accelerometer and the like.

Referring to fig. 1, an embodiment of the present application provides a MEMS piezoelectric transducer, where a substrate 01 is an SOI substrate, the substrate 01 has a cavity 60, and a first transduction vibration assembly is disposed on the substrate 01, and the first transduction vibration assembly includes a transduction diaphragm 40a and piezoelectric composite layer units 20c and 20d disposed on the transduction diaphragm 40 a. The spring structures 42, 43, 44 are obtained after etching the slotted apertures 50a-50d in the transduction diaphragm 40a by a DRIE process. The edges 41, 45 of the transducing diaphragm 40a are anchored to the substrate 01, respectively. The transduction membrane 40a is composed of a BOX layer (i.e., a silicon oxide barrier layer) 02, an SOI top silicon layer 03, and a third passivation layer film 10a (similar to the silicon oxide barrier layer), the BOX layer 02 and the third passivation layer film 10a being used for electrical insulation and isolation protection.

The second transduction vibration assembly is arranged below the first transduction vibration assembly, and the middle parts of the adjacent surfaces of the first transduction vibration assembly and the second transduction vibration assembly are connected through the elastic connection unit 30 b. The two ends of the adjacent surfaces of the first transduction vibration assembly and the second transduction vibration assembly are connected and anchored to the substrate 01 through rims 30a and 30c, wherein 30a-30c may be flexible dry film materials. The flexible dry film material can also be used to cover the slot 50a-50d with a slot width greater than 50a-50 d. The first transducing vibration assembly is connected with the second transducing vibration assembly to form a transducing cavity 60b.

The piezoelectric composite layer units 20a,20b are provided on the second diaphragm 40 b. Wherein the piezoelectric composite layer unit 20b has a single piezoelectric layer structure, 21-1 is a top electrode layer, 21-2 is a piezoelectric layer, and 21-3 is a bottom electrode layer.

In the present application, at least one piezo-electric composite of the MEMS piezoelectric transducer may sense and/or generate acoustic waves. The at least one transducing vibration assembly enables the MEMS piezoelectric transducer to be used as a speaker and/or microphone, and the MEMS actuator device, in particular a piezoelectric MEMS driver, a piezoelectric MEMS micropump, a piezoelectric MEMS micromirror, a piezoelectric MEMS switch, etc.

For example, when the MEMS piezoelectric transducer D01 is used as a speaker, each transducing vibration assembly includes a diaphragm and one or more piezoelectric composite units through which electroacoustic conversion is performed by the piezoelectric composite units 20a to 20D. An audio signal is applied to the piezoelectric composite units 20a-20d, and the piezoelectric layer deforms to drive the first transduction vibration assembly and the second transduction vibration assembly to vibrate up and down to generate displacement deflection, so that air is pushed to make sound, and mechanical acoustic energy conversion is carried out, so that sound waves are formed.

When the first transduction vibration assembly and the second transduction vibration assembly move in the same direction respectively, the opposite surfaces of the two vibration assemblies are connected through the middle elastic connecting piece 30b, when the whole driving is applied to move upwards or downwards, compared with the situation that the two transduction vibration assemblies are not connected, the positions of the first transduction vibration assembly and the second transduction vibration assembly are relatively fixed when the two transduction vibration assemblies move, so that the displacement of the first transduction vibration assembly and the second transduction vibration assembly is increased, and the vibration stroke of the whole device can be improved. It should be noted that the audio driving signals applied to the piezo-electric composite units 20a-20d correspond to the input driving signals, and the output acoustic wave signals. The audio drive signal is typically a sinusoidal signal with a dc voltage offset plus an AC voltage, such as DV10V + AC10Vp, or driven with a bipolar signal.

For example, when the MEMS piezoelectric transducer is used as a microphone, the first transduction vibration assembly and the second transduction vibration assembly vibrate under the action of sound pressure, and the piezoelectric composite units 20a to 20d also vibrate to deform, and the piezoelectric composite units 20a to 20d convert their own vibrations into electrical signals, so that sound waves are sensed. Under the condition that the size of the device is not changed, the area of the sensing sound pressure of the plurality of mutually-spaced and stacked cascade-connected transduction diaphragms is increased, and the total receiving sensitivity of the microphone is further improved.

It should be noted that the placement of the piezo-electric composite 20a-20d may be arbitrary, and is shown in fig. 1 by way of example only, and is not intended to limit the placement of the piezo-electric composite 20a-20 d.

The slotting gaps 50a and 50b are realized on the vibrating film forming the transduction vibrating assembly through an MEMS process, the gap width is 0.5-200 um, and the slotting gaps are used for mechanically decoupling the vibrating film and releasing the process internal stress of each film layer, so that larger driving displacement and sound pressure level output can be obtained, and the residual stress of the transduction vibrating film caused by the process is reduced.

Referring to fig. 1, spring structures 42, 43, 44 are formed after the slit of the transduction diaphragm 40a of the second transduction vibration assembly is slotted, edges 41, 45 of the transduction diaphragm 40a are anchored to the substrate 01, and the first transduction vibration assembly is connected to the second transduction vibration assembly through elastic connection units 30a, 30b, 30c, wherein the elastic connection units are made of a flexible material, and the flexible material can also cover the slotted slit 50a-50d, and has a width greater than the etched slot width, and can cover the whole or part of the diaphragm. The grooving gap is covered and filled with a flowable and curable polymer flexible material, and a covered flexible film is formed after curing, so that when the MEMS sounder and the loudspeaker vibrate and sound, the flexible material is used for covering, thereby preventing the leakage of sound, preventing gas from flowing out of the grooving gap, and improving the output sound pressure level of the MEMS sounder in a low frequency band; the grooving part is covered and filled by flexible materials, the vibrating diaphragm is formed by combining rigidity and flexibility, the moving mass of the vibrating film is reduced, and larger-amplitude vibration is easy to generate, so that larger deflection is obtained. When the forces generated by the electrodes are equal, the lower the mass, the higher the acceleration of the diaphragm, and a high sound pressure level SPL is achieved at high frequencies.

Wherein, the flexible material should cover the slot gap of the transduction diaphragm, its width is greater than the slot width; the flexible material selection requires that the following conditions be met: 1) The MEMS device is compatible with MEMS technology, and can carry out the technologies of pasting, exposing, etching and the like; 2) The reliability problem, dust prevention, water prevention and insulation, and simultaneously, the plate blocks of rigid materials are attached, and the phenomena of film tearing, layering, stripping and the like can not occur under the conditions of different humidity and stress or excitation; 3) The flexible material can resist high temperature, and the temperature of the patch packaging process can not cause reliability problems of the device, such as cracking of the rigid material; 4) At a certain stretching rate, the flexible material is not damaged when the device deflects.

The flexible material may be, but is not limited to, one of the following materials: PI, flexfiner SA, polyurethane, PARYLENE C, or other organic film, the flexible material has a thickness of between 1 μm and 50 μm.

Example 2

As shown in fig. 2, another MEMS piezoelectric transducer provided in this embodiment is distinguished from the MEMS piezoelectric transducer provided in embodiment 1 in that piezoelectric composite units are provided on the upper and lower surfaces of the transduction diaphragms 40a, 40 b.

The MEMS piezoelectric transducer provided in this embodiment includes frames 30a, 30c, a first transducing vibration assembly 40a, a second transducing vibration assembly 40b and a spring structure 30b. The piezoelectric composite units are respectively arranged on the upper side and the lower side of the first transduction membrane 40a and the second transduction membrane 40b, the piezoelectric composite units 20c, 20m, 20d, 20f, 20n and 20h on the upper side and the lower side of the first transduction membrane 40a, and the piezoelectric composite units 20a, 20e, 20i, 20j, 20b and 20g on the upper side and the lower side of the second transduction membrane 40 b.

The centers of the opposite surfaces of the first transduction diaphragm 40a and the second transduction diaphragm 40b are connected together through a 30b elastic connecting piece, and the opposite ends are respectively connected and anchored on the substrate 01 through frames 30a and 30 c.

The first transduction membrane 40a has slot slits 50a-50d, and the elastic connection member 30b may be a flexible dry film or the like having elastic material, and the first transduction membrane 40a and the second transduction membrane 40b are spaced apart from each other and stacked in cascade. The frames 30a and 30c may be made of the same material as the elastic connector 30b, or may be made of a rigid material, and have no elasticity, and the connection modes may be all integrated into one piece, such as gluing, film pressing, bonding, etc.

At least two piezo-electric composite units may be disposed on the first transduction membrane 40a and the second transduction membrane 40b at both upper and lower sides and at least one piezo-electric composite unit in a central region. The polarities of the audio signals on the piezoelectric composite units can be opposite or same, the materials of the piezoelectric layers can be different, the polarities of the piezoelectric layers in the two piezoelectric composite units are opposite through polarization, and the vibration stroke is improved and the sound pressure level is further improved through electric series-parallel connection between the multi-cascade piezoelectric composite layer units.

Example 3

As shown in fig. 3, the present application provides another MEMS piezoelectric transducer in which a first transduction vibration unit and a second transduction vibration unit are connected by 30d, 30b, 30e, and after audio signals of opposite polarities are applied to piezoelectric composite units 20a and 20b in the first transduction vibration unit and piezoelectric composite units 20c and 20d in the second transduction vibration unit, respectively, the piezoelectric composite units 20a and 20b in the first transduction vibration unit are contracted to upwardly bend and deform the opposite ends at the same time, and the piezoelectric composite units 20c and 20d in the second transduction vibration unit are expanded to downwardly bend and deform the opposite ends. At another time, the piezo-electric composite units 20a and 20b in the first transduction vibration assembly are expanded such that the opposite ends are bent and deformed downward, and the piezo-electric composite units 20c and 20d in the second transduction vibration assembly are contracted such that the opposite ends are bent and deformed upward. Therefore, the first transduction vibration component and the second transduction vibration component respectively move in opposite directions, double-sided vibration can be achieved, and the vibrations in opposite directions caused by the movement of the first transduction vibration component and the second transduction vibration component can offset one part of the vibrations, so that the vibration of the MEMS piezoelectric transducer is reduced, and the stability of the device is improved.

Because first transduction vibration subassembly and second transduction vibration subassembly intermediate position interconnect, the position is relatively fixed, compares when first transduction vibration subassembly and second transduction vibration subassembly are not connected, and the displacement is all farther when the both ends that piezoelectric transducer can vibration subassembly and transduction vibration subassembly relative remove for the displacement is all bigger, then has improved the stroke of vibration, further promotes the sound pressure level. Meanwhile, the end part of the vibrating diaphragm is connected with the frame through the plurality of spring structures, the suspension of one end of the vibrating diaphragm is avoided, the working stability of the MEMS piezoelectric transducer can be improved, and when the MEMS piezoelectric transducer is subjected to mechanical impact, falls and the like, the impact can be buffered through the spring structure (such as the spring structure between the slits 50a and 50 b) obtained after slotting the slits, so that the risk of mechanical reliability is reduced.

Example 4

In combination with fig. 4, the present application provides another MEMS piezoelectric transducer, compared with the MEMS piezoelectric transducer provided in embodiment 1, in the MEMS piezoelectric transducer, the piezoelectric composite units 20f and 20h in the second transduction vibration component are respectively located below the transduction diaphragm, so that the rigidity of the diaphragm of the first transduction vibration component can be reduced, and compared with the piezoelectric transducer system formed by the second transduction vibration component alone, the structure can make the displacement travel of the second transduction vibration component larger, the pushed air quantity larger, and further improve the sound pressure level. The quality of vibration of the vibration system is reduced, the sound pressure level curve is improved, and the medium frequency performance of the loudspeaker is improved.

The vibrating diaphragm in the first transduction vibration assembly is etched to form slotted gaps 50e and 50f, and is covered by the flexible dry film material, so that the rigidity of the vibrating diaphragm can be reduced, the transduction vibrating diaphragm in the first transduction vibration assembly is sealed to prevent air pressure leakage, the flexible material replaces the rigid material, the vibration quality is reduced, the sound pressure level curve is improved, and the medium-frequency performance is improved. The elastic connecting piece between the transduction vibration components can increase the damping of the loudspeaker system to reduce the resonance Q value of the transduction vibration components and reduce the total harmonic interference THD.

The first transduction vibration component and the second transduction vibration component are connected together at the middle positions by adopting the elastic connecting piece, the left end part and the right end part are connected with the frame to be anchored on the substrate 01, the suspension between the transduction vibration components is avoided, the stability of the device in working can be improved, the first transduction vibration component is provided with a spring structure, the impact can be buffered when the MEMS piezoelectric transducer is subjected to external mechanical impact, falls and the like, and the mechanical reliability of the MEMS piezoelectric transducer is enhanced.

Example 5

Referring to fig. 5, this embodiment provides another MEMS piezoelectric transducer, which is different from the MEMS piezoelectric transducer provided in embodiment 1 in that: there are a plurality of transducing vibration assemblies spaced apart from each other and stacked in cascade.

A plurality of piezoelectric composite units are arranged on the upper surface and the lower surface of the transduction diaphragm of each vibration component; two adjacent transduction vibration components are connected in pairs through elastic connectors 30b and 30d in the middle of the opposite surfaces, and edges are connected with the two adjacent transduction vibration components through frames 30a, 30c, 30e and 30 f. The respective transduction diaphragms 40a, 40b … n may be etched into slotted slots 50a-50f or cantilever structures.

Compared with the MEMS piezoelectric transducer system formed by two transduction vibration components, the structure can enable the displacement stroke of the transduction vibration components to be larger, the pushed air quantity can be larger, and the sound pressure level is further improved. The quality of vibration of the vibration system is reduced, the sound pressure level curve is improved, and the medium frequency performance of the loudspeaker is improved.

According to the MEMS piezoelectric transducer of the embodiment of the application, the mechanical resonance point of the MEMS piezoelectric transducer can be designed to be 20Hz-20kHz in the audible sound range, when the first-order resonance frequency of the sounder is 2-5KHz, under a certain driving condition, the driving displacement of the vibrating diaphragm is larger, and the output sound pressure level of the MEMS sounder in the low-frequency range is larger, so that the MEMS piezoelectric transducer can be used in the low-frequency sounder. The mechanical resonance point of the device can be designed to be larger than 20kHz outside audible sound, the first harmonic and the third harmonic of the MEMS sounder are outside the audible frequency range, the nonlinearity of the sounder is low, the THD is low, and the device can be used in a high-frequency sounder.

As a speaker or sounder, the larger the effective radiating area of the MEMS transducer, the higher the sound pressure generated in order to produce a sufficiently loud sound. The larger the displacement of the radiating area of the diaphragm, the higher the generated sound pressure. When the single transduction diaphragm is excited to output the limited sound pressure level SPL, the piezoelectric MEMS loudspeaker formed by two or more transduction vibration components which are mutually spaced and stacked in cascade connection can be adopted, the vibration stroke of the piezoelectric loudspeaker is further improved without increasing the sound production area of the loudspeaker, and the sound pressure level output of the device is further improved, so that the whole area of the piezoelectric loudspeaker can be reduced, and the miniaturization requirement is met.

As can be seen from the above embodiments, the MEMS transducer provided by the present application can be spatially laminated and multi-stage coupled through a plurality of transduction vibration assemblies by using elastic connection units, so as to improve the stability during operation. The performance of the device is improved in a multiplied way under the condition of only increasing the thickness of the MEMS piezoelectric transducer, and the requirement of miniaturization of the piezoelectric MEMS transducer can be met. Meanwhile, when the device is subjected to mechanical impact, falling and the like, the impact can be buffered through the spring structure, and the mechanical reliability of the device is enhanced.

When the MEMS piezoelectric transducer is used as a loudspeaker, a plurality of piezoelectric composite units are arranged on the upper side and the lower side of the transduction diaphragm, and larger deflection, driving force or deflection is obtained under the action of voltage driving, so that the vibration stroke of the MEMS piezoelectric loudspeaker is further improved, and the sound pressure level is further improved. In addition, under the condition that the size of the piezoelectric loudspeaker is not changed, the air quantity pushed by the plurality of mutually-spaced and stacked cascade-connected transduction diaphragms can be larger, and the sound pressure level is further improved.

When the MEMS piezoelectric transducer is used as a microphone, the area edge of the sensing sound pressure of the plurality of transduction diaphragms which are mutually spaced and stacked in cascade connection is enlarged without changing the size of the device, and the receiving sensitivity of the device is further improved.

Example 6

As shown in connection with fig. 6, the present application provides another MEMS piezoelectric transducer, which is distinguished from the MEMS piezoelectric transducer in the above-described embodiment in that two transduction vibration units of the MEMS piezoelectric transducer are respectively provided at both sides (above and below) of the substrate 01 and are respectively anchored to the substrate 01. In the figure, the substrate 01 is provided with a cavity 60a, and the transducing diaphragm 40b of the first transducing vibration assembly is provided with gaps 50c and 50d, so that a spring structure 45 is formed; the two ends of the transducing diaphragm 40a of the second transducing vibration member are anchored to the substrate 01, respectively. The piezoelectric composite units 20c and 20d are arranged on the lower surface of the transduction diaphragm 40 a; the piezoelectric composite units 20a and 20b are disposed on the upper surface of the transduction diaphragm 40 b. Slits 50a, 50b are slotted in transduction membrane 40a and are closed off by flexible material 30c, 30 d. The transducing diaphragm 40a is connected to the substrate 01 by means of elastic connection units 30a, 30 b.

After the opposite polarity audio signals are applied to the piezoelectric composite units 20c and 20d in the first transduction vibration assembly and the piezoelectric composite units 20a and 20b in the second transduction vibration assembly, respectively, the transduction diaphragm 40a in the first transduction vibration assembly is contracted and the transduction diaphragm 40b in the second transduction vibration assembly is expanded. Thereby, drive the transduction vibrating diaphragm 40a that sets up at first transduction vibrating subassembly upward movement to drive the transduction vibrating diaphragm 40b that sets up at second transduction vibrating subassembly downward movement, transduction vibrating diaphragm 40a and transduction vibrating diaphragm 40b promote the air respectively and form the sound wave, thereby can realize two-sided sound production, and the vibration of two opposite directions that transduction vibrating subassembly motion led to at this moment can offset one portion each other, reduced piezoelectric speaker's vibration, improved electronic equipment's stability.

It can be understood that the number of the transduction vibration assemblies and the number of the piezoelectric composite units in each transduction vibration assembly can be increased and the setting positions of the transduction vibration assemblies can be changed according to different use requirements. The above modes are all within the scope of the application.

Example 7

The structure of the MEMS piezoelectric transducer serving as the MEMS piezoelectric actuator can be in a bridge structure, and the opposite sides are reinforced; the structure can also be round, rectangular or polygonal, and the periphery is reinforced. In this embodiment, the MEMS piezoelectric actuator D01 is a square structure with four reinforced sides, and has a size: 3mm by 3mm, single layer piezoelectric PZT thin film structure, SOI substrate, excitation piezoelectric DC:15V. In this embodiment, a device having a single transduction vibration component and the MEMS piezoelectric actuator having at least two transduction vibration components provided by the present application are simulated to obtain a simulation result of a maximum vibration displacement of a diaphragm of a piezoelectric MEMS device having a corresponding structure, where, in combination with the simulation effect of the MEMS actuator having the single transduction vibration component shown in fig. 7 and the simulation effect of the MEMS actuator having the two transduction vibration components shown in fig. 8, it is known from the drawings: the maximum displacement of the single transduction vibration component is 31.9um, and the device diaphragm displacement is integrated, so that the air volume of the actuator is 0.0588mm ³. Referring to fig. 8, in the MEMS actuator with two transduction vibration components provided by the application, the maximum displacement of the transduction diaphragm is 32.1um, and the displacement of the transduction diaphragm is integrated, so that the volume of air pushed by one transduction diaphragm in the MEMS actuator is 0.056mm ³, the volume of air pushed by the other transduction diaphragm in the MEMS actuator is 0.059mm ³, and the volume of air pushed by the whole MEMS actuator is 0.115mm ³. Comparing the two, the actuator with a single transduction vibration component and the MEMS piezoelectric actuator with two transduction vibration components provided by the application are illustrated, and the maximum displacement of the transduction diaphragms is close under the same electric drive, but the superposition of the two transduction diaphragms improves the pushed air quantity of the piezoelectric MEMS sounder, so that the emission sound pressure level of the device can be improved.

It can be appreciated that the MEMS piezoelectric transducer provided by the application has the following beneficial effects as a loudspeaker: 1) And a plurality of piezoelectric composite units are arranged on the upper side and the lower side of the transduction diaphragm, and larger deflection, driving force or deflection is obtained under the action of electric drive, so that the vibration stroke of the MEMS piezoelectric loudspeaker is further improved, and the sound pressure level is further improved. Meanwhile, under the condition that the size of the piezoelectric loudspeaker is not changed, the air quantity pushed by the plurality of transduction diaphragms which are mutually spaced and connected in a cascade mode can be larger, and the sound pressure level is further improved.

The MEMS piezoelectric transducer provided by the application has the following beneficial effects as a microphone: 1) Under the condition that the size of the device is not changed, the area of the multiple transduction diaphragms which are mutually spaced and connected in a cascade mode in a layered mode for sensing the sound pressure is increased, and the receiving sensitivity of the device is further improved.

The MEMS piezoelectric transducer provided by the application is used as an MEMS piezoelectric transducer, and the plurality of transduction diaphragms can be spatially laminated and connected in multiple stages through the flexible film springs, so that the stability of the MEMS piezoelectric transducer in working is improved. The performance of the device is improved in a multiplied way under the condition of only increasing the thickness of the device, and the requirement of miniaturization of the piezoelectric MEMS transducer device can be met. Meanwhile, the reliability of the device can be improved, and when the device suffers mechanical impact, falling and the like, the impact can be buffered through the spring, so that the risk of mechanical reliability is reduced.

It is worth to describe that the number of the transduction vibration components, the number of the piezoelectric composite units and the arrangement positions can be increased according to actual requirements, and the details are not repeated here.

It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described system and apparatus may refer to corresponding procedures in the foregoing method embodiments, which are not described herein again.

In addition, in the description of embodiments of the present invention, unless explicitly stated and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood by those skilled in the art in specific cases.

In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Finally, it should be noted that: the above examples are only specific embodiments of the present invention for illustrating the technical solution of the present invention, but not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the foregoing examples, it will be understood by those skilled in the art that the present invention is not limited thereto: any person skilled in the art may modify or easily conceive of the technical solution described in the foregoing embodiments, or perform equivalent substitution of some of the technical features, while remaining within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.

Claims

1. A MEMS piezoelectric transducer, the MEMS piezoelectric transducer comprising:

the substrate is provided with a cavity penetrating along the axis direction;

The at least two transduction vibration assemblies are arranged in a stacked mode along the axial direction of the substrate, and the two adjacent transduction vibration assemblies are connected through an elastic connecting unit.

2. The MEMS piezoelectric transducer of claim 1, wherein the transducing vibration assembly comprises:

a transduction diaphragm;

And the piezoelectric composite layer unit is arranged on the upper surface and/or the lower surface of the transduction diaphragm.

3. The MEMS piezoelectric transducer of claim 2 wherein at least one of two adjacent transducing vibration assemblies has a spring structure;

the spring structure is obtained by etching the transduction diaphragm through an MEMS etching process to generate a slotting gap.

4. The MEMS piezoelectric transducer of claim 1, wherein the elastic connection unit comprises a frame and an elastic connection member made of a flexible material; the elastic connecting piece is used for connecting the middle parts of two adjacent transduction vibration assemblies; the frame is used for connecting the edges of two adjacent transduction vibration components.

5. The MEMS piezoelectric transducer of claim 2 wherein the piezoelectric composite layer element is a single piezoelectric layer structure or a dual piezoelectric layer structure or a multi-piezoelectric layer structure.

6. The MEMS piezoelectric transducer of claim 1, wherein the MEMS piezoelectric transducer comprises a first transduction vibration assembly and a second transduction vibration assembly, the first transduction vibration assembly is disposed above the second transduction vibration assembly, and adjacent faces of the first transduction vibration assembly and the second transduction vibration assembly are connected by the elastic connection unit to form a transduction cavity.

7. The MEMS piezoelectric transducer of claim 6, wherein the transduction diaphragm of the second transduction vibration assembly has a slit therein, the transduction cavity being in communication with the cavity through the slit.

8. The MEMS piezoelectric transducer of claim 7, wherein the first transduction vibration assembly comprises: the first passivation layer film, the silicon supporting layer and the second passivation layer film are sequentially arranged from bottom to top.

9. The MEMS piezoelectric transducer of claim 7, wherein the second transduction vibration assembly comprises: a BOX layer, an SOI top silicon layer and a third passivation layer film which are sequentially arranged from bottom to top;

The two ends of the second transduction vibration component are fixedly connected with the substrate respectively, and the spring structure in the middle of the second transduction vibration component is flexibly connected with the first transduction vibration component through a connecting unit.

10. An electronic device comprising a MEMS piezoelectric transducer as claimed in any one of claims 1-9.