CN113596690B - Structure and device of novel piezoelectric type MEMS microphone - Google Patents

Abstract

The invention relates to the structure and device of a novel piezoelectric MEMS microphone, and mainly relates to the field of microphones. The structure of the novel piezoelectric MEMS microphone that this application relates to, the first electrode layer, the piezoelectric structure layer and the second electrode layer can vibrate under the action of the sound signal, so that the first electrode layer and the second electrode layer The amount of charge on the microphone changes, that is, the output electrical signal of the microphone structure changes. By detecting the output electrical signal, an accurate sound signal can be obtained. Energy conversion using piezoelectric materials integrated on the surface of thin-film silicon. When the film is compressed by the airflow, the film deforms and drives the piezoelectric material to deform, and the piezoelectric material produces an electrical signal for output when its physical properties are improved. That is, the present application increases the sensitivity of the microphone to detect sound signals by increasing the edge and central apertures, thereby making the sound-related voltage signal output by the microphone more accurate and stable.

Description

The Structure and Device of a New Piezoelectric MEMS Microphone

technical field

The invention relates to the field of microphones, and mainly relates to the structure and device of a novel piezoelectric MEMS microphone.

Background technique

Microphone, scientific name microphone, translated from English microphone (microphone), also known as microphone, microphone. Microphones are energy conversion devices that convert sound signals into electrical signals. There are moving coil, condenser, electret and recently emerging silicon micro microphones, as well as liquid microphones and laser microphones. Most microphones are electret condenser microphones, which work by utilizing a polymeric diaphragm with permanent charge isolation.

In the prior art, in order to reduce the resonance frequency of the sensor and further improve the sensitivity of the piezoelectric microphone, most manufacturers adopt slots on the piezoelectric film.

However, the design of the slot in the prior art makes the leakage of the low-frequency signal or even the intermediate-frequency signal very serious, which makes the sensitivity of the microphone in the prior art low.

Contents of the invention

The purpose of the present invention is to, aiming at the deficiencies in the above-mentioned prior art, provide a kind of structure and the device of novel piezoelectric MEMS microphone, to solve the design of the slot in the prior art makes the leakage of low-frequency signal or even intermediate-frequency signal very serious, The problem that the sensitivity of the microphone in the prior art is low.

In order to achieve the above object, the technical solution adopted in the embodiment of the present invention is as follows:

In the first aspect, the present application provides a structure of a novel piezoelectric MEMS microphone, which includes: a substrate, a piezoelectric structure layer, a first electrode layer, and a second electrode layer; the substrate is a cavity structure, and the cavity structure One side of the substrate is provided with an opening, the first electrode layer is arranged above the opening position, the piezoelectric structure layer is arranged on the side of the first electrode layer away from the substrate, and the second electrode layer is arranged on the side of the piezoelectric structure layer far away from the first electrode layer. One side of the electrode layer, and the same position on the first electrode layer, the piezoelectric structure layer and the second electrode layer is provided with through edge holes, and the edge holes are distributed in the first electrode layer, the piezoelectric structure layer and the second electrode layer edge position.

Optionally, there are four edge holes in the structure, and the four edge holes are set in pairs.

Optionally, the structure further includes a first connection hole and a second connection hole, the axes of the first connection hole and the second connection hole are perpendicular to each other, and the first connection hole and the second connection hole pass through the first electrode layer, the piezoelectric The structural layer and the second electrode layer, and the two ends of the first connection hole and the second connection hole are respectively connected to two corresponding edge holes.

Optionally, the structure further includes a second piezoelectric structure layer and a third electrode layer, the second piezoelectric structure layer is disposed on the side of the second electrode layer away from the substrate, and the third electrode layer is disposed on the second piezoelectric structure layer. layer away from the side of the second electrode.

Optionally, the first connection hole and the second connection hole penetrate through the second piezoelectric structure layer and the third electrode layer.

Optionally, the structure further includes a support part, and the support part is disposed on a side of the substrate away from the first electrode.

Optionally, the structure further includes a silicon oxide portion and a device layer silicon portion, the silicon oxide portion is disposed on a side of the substrate close to the first electrode layer, and the device layer silicon portion is disposed between the silicon oxide portion and the first electrode layer.

In the second aspect, the application provides a device for a novel piezoelectric MEMS microphone, which includes: a digital-to-analog conversion device and the structure of any one of the novel piezoelectric MEMS microphones in the first aspect, the positive and negative of the digital-to-analog conversion device The poles are respectively electrically connected to the first electrode layer and the second electrode layer of the structure, and are used to convert the voltage signals output by the first electrode layer and the second electrode layer into digital signals.

The beneficial effects of the present invention are:

The structure of the novel piezoelectric MEMS microphone involved in the application comprises: a substrate, a piezoelectric structure layer, a first electrode layer and a second electrode layer; the substrate is a cavity structure, and one side of the substrate of the cavity structure An opening is provided, the first electrode layer is arranged on the opening position, the piezoelectric structure layer is arranged on the side of the first electrode layer away from the substrate, and the second electrode layer is arranged on the side of the piezoelectric structure layer away from the first electrode layer, And the same positions on the first electrode layer, the piezoelectric structure layer and the second electrode layer are provided with penetrating edge holes, and the edge holes are distributed at the edge positions of the first electrode layer, the piezoelectric structure layer and the second electrode layer. The edge positions of the first electrode layer, the piezoelectric structure layer and the second electrode layer of the structure of the application are all provided with edge holes, so that the first electrode layer, the piezoelectric structure layer and the second electrode layer can be , vibrate, and the amplitude is increased, because the surface charge of the piezoelectric structure layer is transferred under the action of the vibration, so that the amount of charge on the first electrode layer and the second electrode layer changes, that is, the output of the microphone structure When the voltage changes, an accurate sound signal can be obtained by detecting the output voltage signal. When the film is compressed by the airflow, the film deforms and drives the piezoelectric material to deform. The piezoelectric material produces an electrical signal when its physical properties improve. output. When the film is pressed by the continuous air flow, the physical properties of the pressure material are also improved accordingly, and a continuous electrical signal is generated with it. That is, the present application improves the sensitivity of the sound signal detection of the microphone of the present application by adding the connection holes between the edge and the center, thereby making the sound-related voltage signal output by the microphone more accurate and stable.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.

Fig. 1 is the structural representation of the structure of a kind of novel piezoelectric MEMS microphone that the embodiment of the present invention provides;

Fig. 2 is the structural representation of the structure of another novel piezoelectric MEMS microphone provided by an embodiment of the invention;

Fig. 3 is the schematic diagram of the structure of another novel piezoelectric MEMS microphone provided by an embodiment of the invention;

4 is a schematic diagram of the structure of another novel piezoelectric MEMS microphone provided by an embodiment of the invention;

5 is a schematic diagram of the structure of another novel piezoelectric MEMS microphone provided by an embodiment of the invention;

Fig. 6 is a schematic diagram of the influence of a change in the arc length of the circular edge hole of the structure of a novel piezoelectric MEMS microphone on the resonant frequency of the overall microphone structure provided by an embodiment of the invention;

7 is a schematic diagram of the influence of the change of the side lengths of the first connection hole and the second connection hole in the center of the structure of a novel piezoelectric MEMS microphone provided by an embodiment of the invention on the resonant frequency of the overall microphone;

Fig. 8 is a schematic diagram of the influence of the radius change of the structure central cavity of a novel piezoelectric MEMS microphone on the resonant frequency of the overall structure of the microphone provided by an embodiment of the invention;

9 is a schematic diagram of a sensitivity curve of a MEMS piezoelectric microphone provided by an embodiment of the invention;

FIG. 10 is a schematic diagram of a frequency response curve of a MEMS piezoelectric microphone provided by an embodiment of the present invention.

Icons: 10-substrate; 20-first electrode layer; 30-piezoelectric structure layer; 40-second electrode layer; 50-edge hole; 60-first connection hole; 70-second connection hole; 80-th Two piezoelectric structural layers; 90—the third electrode layer.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is an embodiment of the metal plate of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations.

Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

In order to make the implementation process of the present invention clearer, the following will be described in detail in conjunction with the accompanying drawings.

Fig. 1 is the structure schematic diagram of the structure of a kind of novel piezoelectric MEMS microphone that the embodiment of the invention provides; As shown in Fig. 1, the application provides the structure of a kind of novel piezoelectric MEMS microphone, and structure comprises: substrate 10, piezoelectric The electrical structure layer 30, the first electrode layer 20 and the second electrode layer 40; the substrate 10 is a cavity structure, and one side of the substrate 10 of the cavity structure is provided with an opening, and the first electrode layer 20 is covered and arranged at the opening position, The piezoelectric structure layer 30 is disposed on the side of the first electrode layer 20 away from the substrate 10, the second electrode layer 40 is disposed on the side of the piezoelectric structure layer 30 away from the first electrode layer 20, and the first electrode layer 20, piezoelectric The electrical structure layer 30 and the second electrode layer 40 are provided with through edge holes 50 at the same positions, and the edge holes 50 are distributed at the edge positions of the first electrode layer 20 , the piezoelectric structure layer 30 and the second electrode layer 40 .

The structure of the microphone includes substrate 10, first electrode layer 20, piezoelectric structure layer 30, and second electrode layer 40 from bottom to top. The shape and size of the substrate 10 are set according to actual needs, and are not described here To be specifically defined, for the convenience of description, the substrate 10 is described here as a cuboid cavity structure. One surface of the substrate 10 of the cuboid cavity structure is provided with an opening, and the size of the opening is based on actual needs. However, for the convenience of description, the size and shape of the opening are the same as the size and shape of the opening side of the substrate 10, and the position of the opening is sequentially covered with the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer. Two electrode layers 40, the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40 are film-like structures, so that the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40 can be Vibration occurs under the action of the sound signal, and the edge positions of the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40 are provided with edge holes 50, the edge holes 50 are elongated holes, and the edge holes 50 runs through the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40. The specific shape of the edge hole 50 is set according to the shape of the opening. Generally, if the shape of the opening is circular, the edge The shape of the hole 50 is an arc-shaped hole arranged around the edge of the circular opening. If the shape of the opening is rectangular, the shape of the edge hole 50 is a plurality of linear holes arranged at the edge of the rectangle.

The microphone structure of the present application is provided with an edge hole 50 passing through the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40, so that the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40 The amplitude of the formed vibration layer is increased under the action of the sound signal, so that the flatness and sensitivity of the sound signal output by the microphone of the present application are higher. When the microphone of the present application acquires the sound signal, the first electrode layer 20 , the piezoelectric structure layer 30 and the second electrode layer 40 receive the vibration of the sound signal, and under the action of the vibration of the sound signal, resonate, and the amplitude is increased, because the piezoelectric structure layer 30 is under the action of the vibration The surface charge is transferred, so that the amount of charge on the first electrode layer 20 and the second electrode layer 40 changes, that is, the output voltage of the microphone structure changes. By detecting the output voltage signal, an accurate sound signal can be obtained. Since the sensitivity of the microphone is negatively correlated with the resonant frequency of the vibrating part in the microphone, and the resonant frequency and the amplitude are also negatively correlated, the sensitivity of the microphone is positively correlated with the amplitude of the vibrating part in the microphone, that is, the present application increases the edge The hole 50 improves the sensitivity of the sound signal detection of the microphone of the present application, thereby making the sound-related voltage signal output by the microphone more accurate and stable.

In practical applications, the materials of the first electrode layer 20 and the second electrode layer 40 can be selected from molybdenum, titanium, gold, copper and alloys, etc., and the material of the piezoelectric structure layer 30 is a piezoelectric material. A large class of single crystal or polycrystalline solid materials with charges appearing on both ends of them under pressure are important carriers for energy conversion and signal transmission. Piezoelectric materials have good dynamic characteristics and rich mode shapes, and the acoustic emission spectrum of various materials covers almost the entire frequency band. With its excellent electromechanical coupling effect, piezoelectric materials can quickly respond to external forces. The piezoelectric material in this patent can be aluminum nitride, which has the same or higher performance than other MEMS piezoelectric materials (such as zinc oxide, lead zirconate titanate), and its compatibility is better than that of the two Either material is better. In addition, the piezoelectric material can also choose lithium niobate and the like.

Optionally, there are four edge holes 50 in this structure, and the four edge holes 50 are set in pairs.

The four edge holes 50 are arranged through the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40, and are opposite to each other, that is, if the shape of the opening position is circular, the adjacent two The included angle at the center of the edge hole 50 is 90 degrees, showing an arc shape, and the size of the edge hole can be changed. The line connecting the centers of the two edge holes 50 passes through the center of the circle. If the shape of the opening is rectangular, Then the four arc holes are arranged on the four sides of the rectangle respectively, and the center positions of the four edge holes 50 coincide with the center positions of the four sides of the opening of the rectangle respectively. The setting of the four edge holes 50 makes the application The microphone has a symmetrical structure. Under the action of the sound signal, the vibration frequency and vibration amplitude of each part of the microphone structure are the same, which avoids the energy interaction of each part of the microphone structure under the action of different vibration frequencies or different amplitudes. To offset the energy loss caused by the microphone structure of the present application, the energy loss is reduced, so that the vibration information of the sound signal obtained by the microphone is more accurate, and the vibration imbalance caused by the asymmetric structure is reduced, so that the obtained sound signal The error of the vibration information.

Fig. 2 is the structural representation of the structure of another kind of novel piezoelectric MEMS microphone that the embodiment of the invention provides; As shown in Fig. 2, optionally, this structure also comprises first connecting hole 60 and second connecting hole 70, the The axes of the first connection hole 60 and the second connection hole 70 are perpendicular to each other, and the first connection hole 60 and the second connection hole 70 pass through the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40, and the first connection Two ends of the hole 60 and the second connecting hole 70 are respectively connected to two corresponding edge holes 50 .

The first connection hole 60 and the second connection hole 70 are vertically arranged on the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40, and the first connection hole 60 and the second connection hole 70 The first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40 are all penetrated, the number of the edge holes 50 is four, and the first connection hole 60 is connected to the corresponding one of the four edge holes 50. The second connection hole 70 connects the remaining two edge holes 50 of the four edge holes 50. If the opening is a circular hole, the first connection hole 60 and the second connection hole 70 are respectively connected to the corresponding two edges. The central position of the hole 50, so that the first connecting hole 60 and the second connecting hole 70 pass through the central position of the circular opening, if the opening is a rectangular hole, the first connecting hole 60 and the second connecting hole 70 respectively Connect the edge holes 50 on the opposite sides of the rectangular opening so that the intersection of the first connecting hole 60 and the second connecting hole 70 coincides with the midpoint of the rectangular opening, and the microphone is provided with the first The connection hole 60 and the second connection hole 70 divide the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40 of the microphone into four parts, so that when the microphone of the present application is working, the four parts The vibrating parts are tilted upwards or downwards respectively, so that the amplitude of the vibration information of the microphone in the acquisition of the sound signal is further increased under the action of the four parts of the vibrating parts, that is, the microphone can be used under the sound signal of the same intensity. Under the action of , the vibration amplitude is larger and the vibration frequency is reduced, so that the flatness in the frequency band of the microphone is further improved, so that the quality of the acquired sound information is higher, and then the microphone of the present application detects sound signals More accurate; In addition, the first connection hole 60 and the second connection hole 70 reduce the area that needs to be fixed by the vibrating part, and also further improve the amplitude of the sound signal acquired by the microphone of the present application, so that the ability of the application to output piezoelectricity is improved. enhanced.

Fig. 3 is the structure schematic diagram of the structure of another kind of novel piezoelectric MEMS microphone that the embodiment of the invention provides; As shown in Fig. The axes of the hole and the second connection hole are perpendicular to each other, and the first connection hole and the second connection hole pass through the first electrode layer, the piezoelectric structure layer and the second electrode layer, and the two ends of the first connection hole and the second connection hole Respectively connect the joints of the corresponding two edge holes, so that in this embodiment, the piezoelectric structure layer 30, the first electrode layer 20, the second electrode layer 40, the edge hole 50, the first connection hole 60 and the second The vibrating part composed of the two connection holes 70 can generate larger vibration amplitude under the action of the same force, which further makes the sensitivity of the acoustic signal transmission of the present application high.

Fig. 4 is a schematic structural view of the structure of another novel piezoelectric MEMS microphone provided by the embodiment of the invention; as shown in Fig. 4, optionally, the structure also includes a second piezoelectric structure layer 80 and a third electrode layer 90 , the second piezoelectric structure layer 80 is disposed on the side of the second electrode layer 40 away from the substrate 10 , and the third electrode layer 90 is disposed on the side of the second piezoelectric structure layer 80 away from the second electrode.

The upper part of the second electrode layer 40 is provided with the second piezoelectric structure layer 80, the upper part of the second piezoelectric structure layer 80 is provided with the third electrode layer 90, the piezoelectric structure layer 30 and the second piezoelectric structure layer 80 Both will generate vibration under the action of the sound signal, thereby changing the voltage information in the piezoelectric structure layer 30 and the second piezoelectric structure layer 80, so that the accuracy of the sound information obtained by the application is further improved, and the vibration part Adding the second piezoelectric structure layer 80 and the third electrode layer 90 on top of the original first electrode layer 20, piezoelectric structure layer 30 and second electrode layer 40 further reduces the resonant frequency of the vibrating part, so that the The flatness within the frequency band of the microphone is further improved, so that the quality of the acquired sound information is higher.

Fig. 5 is the structure schematic diagram of the structure of another kind of novel piezoelectric MEMS microphone that the embodiment of the invention provides; There are a first connection hole 60 and a second connection hole 70, and the first connection hole 60 and the second connection hole 70 connect the first electrode layer 20, the piezoelectric structure layer 30, the second electrode layer 40, and the second piezoelectric layer of the microphone to each other. The electrical structure layer 80 and the third electrode layer 90 are equally divided into four parts, so that when the microphone of the present application is working, the vibrating parts of the four parts are respectively tilted up or down, so that the microphone of the present application can obtain sound signals. The amplitude of the vibration information is further increased under the action of the vibration parts of the four parts, that is, the microphone has a larger vibration amplitude and a reduced vibration frequency under the action of the sound signal of the same intensity, so that within the frequency band of the microphone The flatness is further improved, so that the quality of the acquired sound information is higher, and the microphone of the present application detects the sound signal more accurately; in addition, the first connection hole 60 and the second connection hole 70 reduce the vibration of the vibration part. The area that needs to be fixed further increases the amplitude of the sound signal acquired by the microphone of this application, so that the ability of this application to output piezoelectricity is enhanced.

Fig. 6 is a schematic diagram of the influence of the change of the arc length of the circular edge hole of the structure of a novel piezoelectric MEMS microphone provided by an embodiment of the invention on the resonant frequency of the overall microphone structure; A schematic diagram of the influence of the change of the length of the first connection hole and the second connection hole side length on the overall microphone resonance frequency in the structure of the novel piezoelectric MEMS microphone; Fig. 8 is a schematic diagram of a novel piezoelectric MEMS microphone provided by an embodiment of the invention A schematic diagram of the influence of the radius change of the central cavity of the structure on the resonant frequency of the overall structure of the microphone; Figure 9 is a schematic diagram of the sensitivity of a MEMS piezoelectric microphone provided by an embodiment of the invention; Figure 10 is a schematic diagram of a MEMS piezoelectric microphone provided by an embodiment of the invention Schematic diagram of the frequency response curve of an electric microphone; the structure provided in this embodiment can make the structure of the present application reach a lower frequency range by optimizing the device size, wherein the optimized size includes the first electrode layer 20 and the second electrode layer 40 1. The size of the piezoelectric material layer 30, including size and material thickness, makes the structure of the present application reach a lower frequency range, and then has great potential in the design and manufacture of low-frequency piezoelectric devices, as shown in Figure 6, the abscissa indicates The arc length of the edge hole of the circular cavity, the ordinate indicates the resonant frequency of the structure, changing the arc length of the edge hole, according to the data schematic diagram, when other parameters are determined, the increase of the arc length of the edge hole will reduce the resonant frequency of the device, Then affect the sensitivity of the microphone structure; as shown in Figure 7, the abscissa represents the size of the width of the first connection hole and the second connection hole, and the ordinate represents the resonant frequency of the structure. According to the data schematic diagram, when other parameters are determined, the center The increase in the width of the connection hole will increase the resonant frequency of the device, which is positively correlated with the resonant frequency; as shown in Figure 8, the abscissa indicates the size of the circular cavity at the opening position, and the ordinate indicates the resonant frequency of the structure. According to the data schematic diagram , when other parameters are determined, the increase of the cavity size will reduce the resonant frequency of the device, which is negatively correlated with the resonant frequency, and is an important factor affecting the resonant frequency of the device. In addition, the thickness of each unit of the structural layer also plays a key role in the structure. It should be optimized from the simulated structure, and the optimal size should be finally determined considering the feasibility of the process preparation. At the same time, the multi-physics field coupling simulation of the structure can also be obtained, as shown in Figure 9, the abscissa represents the frequency, and the ordinate represents the sensitivity of the structure, that is, the proportional relationship between the output voltage and the input sound pressure. This schematic diagram can show that the sensitivity of the microphone varies with From the change of vibration frequency, it can be concluded that the sensitivity of the structure can reach 0.225mV/Pa, and the sensitivity can be further improved by further optimizing the key dimensions of the structure combined with the optimization of materials. In addition, Fig. 10 shows the frequency response curve of the microphone structure shown in the fifth embodiment of the present invention, which shows the relationship between the output of the structure and the input frequency. It can be seen that in the frequency range of 20-20kHz, the unevenness of the structure is about It is 0.45dB, the maximum unevenness is far within 3dB, and the flatness of the frequency response curve is relatively high.

Optionally, the structure further includes a support portion, and the support portion is disposed on a side of the substrate 10 away from the first electrode.

The support part is arranged on the side of the substrate 10 away from the first electrode layer 20, and the support part is used to support the substrate 10 to prevent the piezoelectric structure layer 30 from breaking. When the microphone structure vibrates, the support layer can act To protect and prevent the structure from breaking when overloaded. Therefore, in practical applications, the support layer at the bottom of the substrate 10 is generally prepared using a Si—Si bonding process.

Optionally, the structure further includes a silicon oxide part and a device layer silicon part, the silicon oxide part is arranged above the substrate 10, is consistent with the upper surface of the substrate 10, and has the same opening position, and the device layer silicon part is placed on the oxide layer. The upper part of the silicon is placed on the side of the first electrode layer away from the first piezoelectric layer.

The substrate layer structure adopts an SOI substrate, which can reduce process steps and improve the reliability of process preparation. The SOI bottom silicon and SOI silicon oxide part are used as supporting layers, and the bottom silicon and silicon oxide parts both adopt the opening structure shown in the cantilever beam substrate 10, and the SOI top device layer silicon is used for the first electrode layer 20 and the piezoelectric structure. Layer 30 and the second electrode layer 40 are supported by the vibrating part, which is equivalent to increasing the thickness of the entire vibrating part. The upper surface is consistent. The presence of silicon on the top layer of the SOI device increases the thickness of the entire cantilever beam, improves the reliability of the device, and relatively increases the resonant frequency of the device, thereby further improving the flatness of the microphone's frequency band. The audio information is of higher quality.

Optionally, the structure further includes a silicon layer, and the silicon layer is disposed on a side of the first electrode layer 20 close to the substrate 10 .

The silicon layer is used to support the first electrode layer 20, the piezoelectric material layer and the second electrode layer 40, so as to increase the vibration part composed of the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40 thickness, so that under the action of an acoustic signal of the same intensity, the vibration amplitude of the vibrating part composed of the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40 is reduced, that is, the piezoelectric structure layer 30 The deformation of the piezoelectric structure layer 30 is smaller, thereby changing the voltage information in the piezoelectric structure layer 30, so that the accuracy of the sound information obtained by the present application is further improved, and thickening the vibrating part further reduces the resonant frequency of the vibrating part , so that the flatness within the frequency band of the microphone is further improved, so that the quality of the acquired sound information is higher.

The process preparation method of the structure provided by this application: prepare a silicon wafer, sequentially sputter electrode material/piezoelectric material/electrode material on a silicon substrate, pattern the electrode material/piezoelectric material/electrode material sequentially from top to bottom, and Complete the etching of the electrode pad, and finally perform back cavity etching to etch the substrate opening cavity

The application provides a device for a novel piezoelectric MEMS microphone, which includes: a digital-to-analog conversion device and the structure of any one of the above-mentioned novel piezoelectric MEMS microphones, the positive and negative poles of the digital-to-analog conversion device are respectively connected to the first structure of the structure. The first electrode layer 20 is electrically connected to the second electrode layer 40 for converting the voltage signal output by the first electrode layer 20 and the second electrode layer 40 into a digital signal.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (6)

1. the structure of a novel piezoelectric MEMS microphone is characterized in that, said structure comprises: substrate, piezoelectric structure layer, first electrode layer and second electrode layer; Described substrate is cavity structure, and One side of the substrate of the cavity structure is provided with an opening, the first electrode layer is covered and arranged above the opening position, and the piezoelectric structure layer is arranged on a side of the first electrode layer away from the substrate. side, the second electrode layer is arranged on the side of the piezoelectric structure layer away from the first electrode layer, and the first electrode layer, the piezoelectric structure layer and the second electrode layer are the same The position of the penetrating edge hole is provided, and the edge hole is distributed at the edge positions of the first electrode layer, the piezoelectric structure layer and the second electrode layer; the position of the edge hole of the structure is Four, the four edge holes are set in pairs, the structure also includes a first connection hole and a second connection hole, the axes of the first connection hole and the second connection hole are perpendicular to each other, and the The first connection hole and the second connection hole pass through the first electrode layer, the piezoelectric structure layer and the second electrode layer, and the two ends of the first connection hole and the second connection hole Connect the corresponding two edge holes respectively. 2. the structure of novel piezoelectric MEMS microphone according to claim 1, is characterized in that, described structure also comprises second piezoelectric structure layer and the 3rd electrode layer, and described second piezoelectric structure layer is arranged on said The second electrode layer is disposed on a side away from the substrate, and the third electrode layer is disposed on a side of the second piezoelectric structure layer away from the second electrode. 3. The structure of the novel piezoelectric MEMS microphone according to claim 2, wherein the first connection hole and the second connection hole run through the second piezoelectric structure layer and the third electrode layer. 4 . The structure of the novel piezoelectric MEMS microphone according to claim 3 , wherein the structure further comprises a support portion, and the support portion is disposed on a side of the substrate away from the first electrode. 5. The structure of the novel piezoelectric MEMS microphone according to claim 4, wherein the structure further comprises a silicon oxide portion and a device layer silicon portion, and the silicon oxide portion is arranged on the substrate near the first electrode layer On one side, the silicon part of the device layer is disposed between the silicon oxide part and the first electrode layer. 6. A device for a novel piezoelectric MEMS microphone, characterized in that, said device comprises: a digital-to-analog conversion device and the structure of the novel piezoelectric MEMS microphone described in any one of claims 1-5, said digital The positive and negative poles of the mode conversion device are respectively electrically connected to the first electrode layer and the second electrode layer of the structure, and are used to convert the voltage signals output by the first electrode layer and the second electrode layer into digital signals.

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