CN113596690B - Structure and device of novel piezoelectric type MEMS microphone - Google Patents
Structure and device of novel piezoelectric type MEMS microphone Download PDFInfo
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- CN113596690B CN113596690B CN202110927935.4A CN202110927935A CN113596690B CN 113596690 B CN113596690 B CN 113596690B CN 202110927935 A CN202110927935 A CN 202110927935A CN 113596690 B CN113596690 B CN 113596690B
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- 238000006243 chemical reaction Methods 0.000 claims abstract description 10
- 239000000758 substrate Substances 0.000 claims description 42
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical group [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 15
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical group [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 claims description 8
- 239000000919 ceramic Substances 0.000 claims description 3
- 230000000149 penetrating effect Effects 0.000 claims description 3
- 230000005236 sound signal Effects 0.000 abstract description 25
- 239000000463 material Substances 0.000 abstract description 23
- 230000035945 sensitivity Effects 0.000 abstract description 14
- 239000010408 film Substances 0.000 abstract 2
- 230000000694 effects Effects 0.000 abstract 1
- 239000002210 silicon-based material Substances 0.000 abstract 1
- 239000010409 thin film Substances 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 22
- 230000009471 action Effects 0.000 description 15
- 229910052710 silicon Inorganic materials 0.000 description 12
- 239000010703 silicon Substances 0.000 description 12
- 238000000034 method Methods 0.000 description 7
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- 230000008859 change Effects 0.000 description 4
- 239000007772 electrode material Substances 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 229910052814 silicon oxide Inorganic materials 0.000 description 3
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 230000002596 correlated effect Effects 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
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- 238000005457 optimization Methods 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
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- 230000009286 beneficial effect Effects 0.000 description 1
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- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 230000001808 coupling effect Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- HFGPZNIAWCZYJU-UHFFFAOYSA-N lead zirconate titanate Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ti+4].[Zr+4].[Pb+2] HFGPZNIAWCZYJU-UHFFFAOYSA-N 0.000 description 1
- 229910052451 lead zirconate titanate Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 238000000059 patterning Methods 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
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- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R17/00—Piezoelectric transducers; Electrostrictive transducers
- H04R17/02—Microphones
- H04R17/025—Microphones using a piezoelectric polymer
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R19/00—Electrostatic transducers
- H04R19/04—Microphones
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
- H04R2201/003—Mems transducers or their use
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Piezo-Electric Transducers For Audible Bands (AREA)
- Micromachines (AREA)
Abstract
The invention relates to a structure and a device of a novel piezoelectric type MEMS microphone, and mainly relates to the field of microphones. The utility model relates to a novel piezoelectric type MEMS microphone's structure, this first electrode layer, piezoelectric structure layer and second electrode layer can vibrate under sound signal's effect for the electric charge volume on this first electrode layer and the second electrode layer changes, and the output signal of telecommunication of this microphone structure changes promptly, through detecting the output signal of telecommunication, can obtain accurate sound signal. The piezoelectric material integrated on the surface of the thin-film silicon material is used for energy conversion. When the film is pressed by the airflow, the film deforms and drives the piezoelectric material to deform, and the piezoelectric material generates an electric signal to output when the physical characteristics are improved. This application is through increasing edge and central hole for the sensitivity that this application's microphone detected sound signal obtains improving, and then makes the voltage signal relevant with the sound that this microphone output more accurate stable.
Description
Technical Field
The invention relates to the field of microphones, in particular to a structure and a device of a novel piezoelectric type MEMS (micro-electromechanical systems) microphone.
Background
The microphone, known as a microphone, is translated from an english microphone (microphone), and is also called a microphone or a microphone. A microphone is an energy conversion device that converts a sound signal into an electrical signal. There are classes of moving coil, capacitor, electret and recently emerging silicon micro-microphones, but also liquid microphones and laser microphones. Most microphones are electret condenser microphones which operate on the principle of using a diaphragm of polymeric material with permanent charge isolation.
In the prior art, in order to lower the resonant frequency of the sensor and further improve the sensitivity of the piezoelectric microphone, most manufacturers adopt a slot on the piezoelectric film.
However, the design of the slot in the prior art makes the leakage of low frequency signals and even medium frequency signals very severe, making the prior art microphone less sensitive.
Disclosure of Invention
The present invention is directed to provide a structure and a device of a novel piezoelectric MEMS microphone, so as to solve the problem that the leakage of low frequency signals and even medium frequency signals is very serious due to the design of slots in the prior art, and the sensitivity of the microphone in the prior art is low.
In order to achieve the above purpose, the embodiment of the present invention adopts the following technical solutions:
in a first aspect, the present application provides a structure of a novel piezoelectric MEMS microphone, the structure including: the piezoelectric ceramic comprises a substrate, a piezoelectric structural layer, a first electrode layer and a second electrode layer; the substrate is the cavity structure, and the one side of cavity structure's substrate is provided with the opening, and first electrode layer covers and sets up in open position top, and the piezoelectric structure layer sets up the one side of keeping away from the substrate at first electrode layer, and the second electrode layer sets up the one side of keeping away from first electrode layer at piezoelectric structure layer, and the same position is provided with the marginal hole that runs through on first electrode layer, piezoelectric structure layer and the second electrode layer, and the marginal hole distributes in the marginal position of first electrode layer, piezoelectric structure layer and second electrode layer.
Optionally, the number of the edge holes of the structure is four, and the four edge holes are arranged in a pairwise correspondence manner.
Optionally, the structure further includes a first connection hole and a second connection hole, axes of the first connection hole and the second connection hole are perpendicular to each other, the first connection hole and the second connection hole penetrate through the first electrode layer, the piezoelectric structure layer and the second electrode layer, and two ends of the first connection hole and the second connection hole are respectively connected to the 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 a side of the second electrode layer 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.
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 comprises a support portion disposed on a side of the substrate away from the first electrode.
Optionally, the structure further comprises a silicon oxide part and a device layer silicon part, the silicon oxide part is arranged on one side of the substrate close to the first electrode layer, and the device layer silicon part is arranged between the silicon oxide part and the first electrode layer.
In a second aspect, the present application provides an apparatus of a novel piezoelectric MEMS microphone, the apparatus including: the digital-to-analog conversion device and the novel piezoelectric MEMS microphone structure of any one of the first aspect are characterized in that the positive electrode and the negative electrode of the digital-to-analog conversion device are respectively electrically connected with the first electrode layer and the second electrode layer of the structure and used for converting voltage signals output by the first electrode layer and the second electrode layer into digital signals.
The invention has the beneficial effects that:
the utility model relates to a novel piezoelectric type MEMS microphone's structure, the structure includes: the piezoelectric ceramic comprises a substrate, a piezoelectric structural layer, a first electrode layer and a second electrode layer; the substrate is a cavity structure, one side of the substrate of the cavity structure is provided with an opening, the first electrode layer covers and is arranged at the position of the opening, the piezoelectric structure layer is arranged at one side of the first electrode layer far away from the substrate, the second electrode layer is arranged at one side of the piezoelectric structure layer far away from the first electrode layer, the first electrode layer and the second electrode layer are provided with penetrating edge holes at the same position, 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 holes are formed in the edge positions of the first electrode layer, the piezoelectric structure layer and the second electrode layer of the structure of the microphone structure, so that the first electrode layer, the piezoelectric structure layer and the second electrode layer can vibrate under the action of sound signals, the amplitude is increased, electric charges are transferred under the action of vibration of the piezoelectric structure layer, the electric charge quantity on the first electrode layer and the second electrode layer is changed, namely, the output voltage of the microphone structure is changed, and the accurate sound compression signals can be obtained by detecting the output voltage signals when the film is subjected to airflow, the deformation and the piezoelectric material is deformed to improve the physical output characteristics. When the film is pressed by continuous air flow, the physical property of the pressure material is correspondingly improved, and a continuous electric signal is generated. This application is through increasing edge and central connecting hole promptly for the microphone of this application detects the sensitivity of sound signal and obtains improving, and then makes the voltage signal that is relevant with the sound of this microphone output more accurate stable.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a schematic structural diagram of a structure of a novel piezoelectric MEMS microphone according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a structure of another novel piezoelectric MEMS microphone according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a structure of another novel piezoelectric MEMS microphone according to an embodiment of the present invention;
fig. 4 is a schematic diagram illustrating a structure of another novel piezoelectric MEMS microphone according to an embodiment of the present invention;
fig. 5 is a schematic diagram illustrating a structure of another novel piezoelectric MEMS microphone according to an embodiment of the present invention;
fig. 6 is a schematic diagram illustrating an influence of a change in an arc length of a circular edge hole of a novel piezoelectric MEMS microphone structure on a resonant frequency of the whole microphone structure according to an embodiment of the present invention;
fig. 7 is a schematic diagram illustrating an influence of changes in side lengths of a first connection hole and a second connection hole in a center of a structure of a novel piezoelectric MEMS microphone on a resonance frequency of the whole microphone according to an embodiment of the present invention;
fig. 8 is a schematic diagram illustrating an influence of a radius change of a central cavity of a novel piezoelectric MEMS microphone on a resonant frequency of an overall structure of the microphone according to an embodiment of the present invention;
fig. 9 is a schematic diagram of a sensitivity curve of a MEMS piezoelectric microphone according to an embodiment of the present invention;
fig. 10 is a schematic frequency response curve of a MEMS piezoelectric microphone according to an embodiment of the present invention.
Icon: 10-a substrate; 20-a first electrode layer; 30-a piezoelectric structure layer; 40-a second electrode layer; 50-edge holes; 60-a first connection hole; 70-a second connection hole; 80-a second piezoelectric structure layer; 90-a third electrode layer.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiment is a metal plate embodiment of the present invention, and not all embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.
In order to make the implementation of the present invention clearer, the following detailed description is made with reference to the accompanying drawings.
Fig. 1 is a schematic structural diagram of a structure of a novel piezoelectric MEMS microphone according to an embodiment of the present invention; as shown in fig. 1, the present application provides a structure of a novel piezoelectric MEMS microphone, the structure including: a substrate 10, a piezoelectric structure layer 30, a first electrode layer 20, and a second electrode layer 40; the substrate 10 is a cavity structure, an opening is formed in one surface of the substrate 10 of the cavity structure, the first electrode layer 20 is covered and arranged at the opening, the piezoelectric structure layer 30 is arranged on one side, away from the substrate 10, of the first electrode layer 20, the second electrode layer 40 is arranged on one side, away from the first electrode layer 20, of the piezoelectric structure layer 30, the edge holes 50 which penetrate through the piezoelectric structure layer 30 are formed in the same positions of the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40, 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 microphone is configured from bottom to top as a substrate 10, a first electrode layer 20, a piezoelectric structure layer 30, and a second electrode layer 40 in sequence, where the shape and size of the substrate 10 are set according to actual needs, and are not specifically limited herein, for convenience of description, the shape of the substrate 10 is a rectangular cavity structure, one surface of the substrate 10 of the rectangular cavity structure is provided with an opening, and the size of the opening is determined according to actual needs, and for convenience of description, the size and shape of the opening are the same as the size and shape of the open surface of the substrate 10, the opening position is sequentially covered with the first electrode layer 20, the piezoelectric structure layer 30, and the second electrode layer 40, and the first electrode layer 20, the piezoelectric structure layer 30, and the second electrode layer 40 are all film-shaped structures, so that the first electrode layer 20, the piezoelectric structure layer 30, and the second electrode layer 40 can vibrate under the action of a sound signal, and the edge positions of the first electrode layer 20, the rectangular structure layer 30, and the second electrode layer 40 are provided with an edge hole 50, and the edge position of the edge hole 50 is a linear shape, and if the edge position of the opening is a plurality of linear shape, the edge hole is provided with an arc-shaped edge hole 50, and the edge of the circular opening is provided with a circular shape.
The microphone structure of the present application is provided with the edge hole 50 penetrating through the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40, so that the amplitude of the vibration layer formed by the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40 is increased under the action of the sound signal, and thus the flatness and the 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 resonate under the action of the vibration of the sound signal, and the amplitude is increased, since the surface charge of the piezoelectric structure layer 30 is transferred under the action of the vibration, the charge amount on the first electrode layer 20 and the second electrode layer 40 is changed, that is, the output voltage of the microphone structure is changed, an accurate sound signal can be obtained by detecting the output voltage signal, since the sensitivity of the microphone is negatively correlated with the resonance frequency of the vibration part in the microphone, and the resonance frequency and the amplitude are also negatively correlated, the sensitivity of the microphone is increased, and the microphone is further, the microphone structure can obtain an accurate sound signal by increasing the edge hole, and further, the microphone can improve the detection of the sound signal, and the microphone.
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, alloys, and the like, the material of the piezoelectric structure layer 30 is a piezoelectric material, which is a large single crystal or polycrystalline solid material that generates charges on both end surfaces thereof under the action of pressure, and is an important carrier for energy conversion and signal transmission. The piezoelectric material has good dynamic characteristics and abundant vibration modes, and the acoustic emission frequency spectrum of various materials almost covers the whole frequency band. The piezoelectric material can respond to external force quickly due to the excellent electromechanical coupling effect of the piezoelectric material. The piezoelectric material in this patent can be selected from aluminum nitride, which has the same or higher performance than other MEMS piezoelectric materials (such as zinc oxide, lead zirconate titanate) and has better compatibility than either of the two materials. In addition, lithium niobate and the like can be selected as the piezoelectric material.
Optionally, the number of the edge holes 50 of the structure is four, and four edge holes 50 are correspondingly arranged 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 in pairs, that is, if the shape of the opening position is circular, an included angle between the center positions of two adjacent edge holes 50 is 90 degrees, the edge holes are arc-shaped, the size of the edge holes can be changed, a connecting line of the center positions of the two opposite edge holes 50 passes through the center position, if the shape of the opening position is rectangular, four arc holes are respectively arranged on four side lines of the rectangle, and the center positions of the four edge holes 50 are respectively superposed with the center positions of four sides of the opening of the rectangle, the microphone of the present application has a symmetrical structure due to the arrangement of the four edge holes 50, the microphone of the symmetrical structure is under the action of a sound signal, the vibration frequency and the vibration amplitude of each part of the microphone structure are the same, the energy loss caused by mutual energy cancellation of each part of the microphone structure under the action of different vibration frequencies or different amplitudes is avoided, and the energy loss is reduced, so that the vibration information of the microphone obtained by the microphone is more accurate to obtain an unbalanced sound signal.
Fig. 2 is a schematic structural diagram of a structure of another novel piezoelectric MEMS microphone according to an embodiment of the present invention; as shown in fig. 2, optionally, the structure further includes a first connection hole 60 and a second connection hole 70, axes of the first connection hole 60 and the second connection hole 70 are perpendicular to each other, the first connection hole 60 and the second connection hole 70 penetrate through the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40, and two ends of the first connection hole 60 and the second connection hole 70 are respectively connected to the two corresponding edge holes 50.
The first connection hole 60 and the second connection hole 70 are perpendicularly 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 penetrate the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40, the number of the edge holes 50 is four, the first connection hole 60 connects two corresponding 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 respectively connect the center positions of the two corresponding edge holes 50, so that the first connection hole 60 and the second connection hole 70 pass through the center position of the circular opening, if the opening is a rectangular hole, the first connection hole 60 and the second connection hole 70 respectively connect the edge holes 50 on two opposite sides of the rectangular opening, the intersection point of the first connection hole 60 and the second connection hole 70 is overlapped with the middle point of the rectangular opening, the first connection hole 60 and the second connection hole 70 are arranged on the microphone, the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40 of the microphone are equally divided into four parts, so that when the microphone of the present application works, the vibration parts of the four parts are respectively tilted upwards or downwards, the amplitude of the vibration information of the microphone of the present application is further increased under the action of the vibration parts of the four parts, namely, the vibration amplitude is larger and the vibration frequency is reduced under the action of the sound signals with the same intensity, the flatness in the frequency band of the microphone is further improved, and the quality of the obtained sound information is higher, therefore, the microphone can detect the sound signal more accurately; in addition, the first connection hole 60 and the second connection hole 70 reduce the area of the vibrating portion to be fixed, and further improve the amplitude of the sound signal acquired by the microphone of the present application, so that the capability of the present application to output the piezoelectric is enhanced.
Fig. 3 is a schematic structural diagram of a structure of another novel piezoelectric MEMS microphone according to an embodiment of the present invention; as shown in fig. 3, optionally, the structure further includes a first connection hole and a second connection hole, axes of the first connection hole and the second connection hole are perpendicular to each other, the first connection hole and the second connection hole penetrate through the first electrode layer, the piezoelectric structure layer and the second electrode layer, and two ends of the first connection hole and the second connection hole are respectively connected to a connection point of two corresponding edge holes, so that, in this embodiment, an amplitude generated by the vibration portion composed of 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 connection hole 70 under the same force is larger, and further, the sensitivity of the present application for transmitting acoustic signals is high.
Fig. 4 is a schematic structural diagram of a structure of another novel piezoelectric MEMS microphone according to an embodiment of the present invention; as shown in fig. 4, optionally, the structure further includes a second piezoelectric structure layer 80 and a third electrode layer 90, the second piezoelectric structure layer 80 is disposed on a side of the second electrode layer 40 away from the substrate 10, and the third electrode layer 90 is disposed on a side of the second piezoelectric structure layer 80 away from the second electrode.
The second piezoelectric structure layer 80 is arranged on the upper portion of the second electrode layer 40, the third electrode layer 90 is arranged on the upper portion of the second piezoelectric structure layer 80, the piezoelectric structure layer 30 and the second piezoelectric structure layer 80 both vibrate under the action of the sound signal, so that voltage information in the piezoelectric structure layer 30 and the second piezoelectric structure layer 80 is changed, the accuracy of the sound information obtained by the method is further improved, the second piezoelectric structure layer 80 and the third electrode layer 90 are added to the vibration portion on the top of the original first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40, so that the resonant frequency of the vibration portion is further reduced, the flatness in the frequency band of the microphone is further improved, and the quality of the obtained sound information is higher.
Fig. 5 is a schematic structural diagram of a structure of another novel piezoelectric MEMS microphone according to an embodiment of the present invention; as shown in fig. 5, optionally, the second piezoelectric structure layer 80 and the third electrode layer 90 are further provided with a first connection hole 60 and a second connection hole 70, and the first connection hole 60 and the second connection hole 70 divide the first electrode layer 20, the piezoelectric structure layer 30, the second electrode layer 40, the second piezoelectric structure layer 80, and the third electrode layer 90 of the microphone into four parts, so that when the microphone of the present application is in operation, the vibration parts of the four parts are respectively tilted upward or downward, so that the amplitude of the microphone acquiring the vibration information of the sound signal 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 smaller vibration frequency under the action of the sound signal with the same intensity, so that the flatness in the frequency band of the microphone is further improved, 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 area of the vibration part which needs to be fixed, and further improve the amplitude of the sound signal acquired by the microphone of the present application, so that the capability of the present application for outputting the piezoelectric is enhanced.
Fig. 6 is a schematic diagram illustrating an influence of a change in an arc length of a circular edge hole of a novel piezoelectric MEMS microphone structure on a resonant frequency of the whole microphone structure according to an embodiment of the present invention; fig. 7 is a schematic diagram illustrating an influence of changes in side lengths of a first connection hole and a second connection hole in a center of a structure of a novel piezoelectric MEMS microphone on a resonance frequency of the whole microphone according to an embodiment of the present invention; fig. 8 is a schematic diagram illustrating an influence of a radius change of a central cavity of a novel piezoelectric MEMS microphone on a resonant frequency of an overall structure of the microphone according to an embodiment of the present invention; fig. 9 is a sensitivity diagram of a MEMS piezoelectric microphone according to an embodiment of the invention; fig. 10 is a schematic diagram of a frequency response curve of a MEMS piezoelectric microphone according to an embodiment of the present invention; according to the structure provided by the embodiment, the size of the device can be optimized, so that the structure of the present application can reach a lower frequency range, wherein the optimized size includes the sizes of the first electrode layer 20, the second electrode layer 40 and the piezoelectric material layer 30, including the size and the material thickness, so that the structure of the present application can reach the lower frequency range, and further has great potential in the design and preparation of a low-frequency piezoelectric device, as shown in fig. 6, the abscissa represents the arc length of the edge hole of the circular cavity, the ordinate represents the resonance frequency of the structure, and the arc length of the edge hole is changed; as shown in fig. 7, the abscissa represents 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, in the case of determining other parameters, the increase of the width of the central connection hole will increase the resonant frequency of the device, and the increase of the width of the central connection hole is in positive correlation with the resonant frequency; as shown in fig. 8, the abscissa indicates the size of the circular cavity at the position of the opening, and the ordinate indicates the resonant frequency of the structure, according to the data diagram, under the condition of other parameter determination, the increase of the cavity size can reduce the resonant frequency of the device, and the increase is in negative correlation with the resonant frequency and is an important factor influencing the resonant frequency of the device. In addition, the thickness of each unit of the structural layer plays a key role in the structure, and the optimal size is finally determined by considering the process preparation feasibility from the optimization of the simulation structure. Meanwhile, the structure can be obtained by performing multi-physical field coupling simulation, as shown in fig. 9, the abscissa represents frequency, and the ordinate represents the sensitivity of the structure, that is, the proportional relation between the output voltage and the input sound pressure, and the schematic diagram can represent the variation of the sensitivity of the microphone along with the vibration frequency, so that the sensitivity of the structure can reach 0.225mV/Pa, and the sensitivity can be further improved by further optimizing the key size of the structure and combining the optimization of materials. In addition, fig. 10 is a frequency response curve of the microphone structure according to the five embodiments of the present invention, which shows the relationship between the output and input frequencies of the structure, and it can be seen that in the frequency range of 20-20kHz, the unevenness of the structure is about 0.45dB, the maximum unevenness is far within 3dB, and the flatness of the frequency response curve is high.
Optionally, the structure further comprises a support portion disposed on a side of the substrate 10 remote from the first electrode.
The supporting portion is disposed on a side of the substrate 10 away from the first electrode layer 20, and is used for supporting the substrate 10 to prevent the piezoelectric structure layer 30 from breaking, and when the microphone structure vibrates, the supporting layer can play a role in protecting the structure from breaking when overloaded. Therefore, in practical applications, the support layer on the bottom of the substrate 10 is generally prepared using a Si — Si bonding process.
Optionally, the structure further includes a silicon oxide portion and a device layer silicon portion, the silicon oxide portion is disposed above the substrate 10, is consistent with the upper surface of the substrate 10, has the same opening position, and the device layer silicon portion is disposed on the upper portion of the silicon oxide and is disposed on the side of the first electrode layer away from the first piezoelectric layer.
The substrate layer structure adopts an SOI substrate, and the process procedures can be reduced and the reliability of process preparation can be improved by adopting the SOI substrate. The SOI bottom layer silicon and the SOI silicon oxide part are used as supporting layers, meanwhile, the bottom layer silicon and the silicon oxide part are both of an opening structure shown by the cantilever beam substrate 10, and the SOI top layer device layer silicon is used for supporting the vibration part formed by the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40, so that the thickness of the whole vibration part is increased, and the SOI bottom layer silicon and the SOI silicon oxide part are placed on one side, far away from the first piezoelectric layer, of the first electrode layer and are consistent with the upper surface of the structure of the electrode layer and the piezoelectric layer. The thickness of the whole cantilever beam is increased due to the existence of SOI top device layer silicon, the reliability of the device is improved, and the resonant frequency of the device is relatively improved, so that the flatness in the frequency band of the microphone is further improved, and the quality of the obtained sound information is higher.
Optionally, the structure further comprises a silicon layer disposed on a side of the first electrode layer 20 adjacent to the substrate 10.
The silicon layer is used for supporting the first electrode layer 20, the piezoelectric material layer and the second electrode layer 40, so as to increase the thickness of the vibration part composed of the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40, so that under the action of the acoustic signal with the same strength, the vibration part composed of the first electrode layer 20, the piezoelectric structure layer 30 and the second electrode layer 40 generates vibration with reduced amplitude, that is, the deformation amount of the piezoelectric structure layer 30 is smaller, and further the voltage information in the piezoelectric structure layer 30 is changed, so that the accuracy of the sound information acquired in the application is further improved, and the resonance frequency of the vibration part is further reduced by thickening the vibration part, so that the flatness in the frequency band of the microphone is further improved, and the quality of the acquired sound information is higher.
The process preparation method of the structure provided by the application comprises the following steps: preparing a silicon chip, sputtering electrode material/piezoelectric material/electrode material on a silicon substrate in sequence, patterning the electrode material/piezoelectric material/electrode material from top to bottom in sequence, completing etching of an electrode pad, and finally performing back cavity etching to etch an open cavity of the substrate
The application provides a pair of novel piezoelectric type MEMS microphone's device, the device includes: the structure of the digital-analog conversion device and the novel piezoelectric MEMS microphone comprises the digital-analog conversion device, wherein the positive electrode and the negative electrode of the digital-analog conversion device are respectively and electrically connected with the first electrode layer 20 and the second electrode layer 40 of the structure, and are used for converting voltage signals output by the first electrode layer 20 and the second electrode layer 40 into digital signals.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. A structure of a novel piezoelectric MEMS microphone, the structure comprising: the piezoelectric ceramic comprises a substrate, a piezoelectric structural layer, a first electrode layer and a second electrode layer; the substrate is of a cavity structure, an opening is formed in one surface of the substrate of the cavity structure, the first electrode layer is arranged above the opening in a covering mode, the piezoelectric structure layer is arranged on one side, away from the substrate, of the first electrode layer, the second electrode layer is arranged on one side, away from the first electrode layer, of the piezoelectric structure layer, penetrating edge holes are formed in the same positions of the first electrode layer, the piezoelectric structure layer and the second electrode layer, and the edge holes are distributed in the edge positions of the first electrode layer, the piezoelectric structure layer and the second electrode layer; the structure the position of edge hole is four, four two liang of correspondence settings in edge hole, the structure still includes first connecting hole and second connecting hole, first connecting hole with the axis mutually perpendicular of second connecting hole, just first connecting hole with the second connecting hole runs through first electrode layer piezoelectric structure layer with the second electrode layer, just first connecting hole with two corresponding edge holes are connected respectively at the both ends of second connecting hole.
2. The structure of the novel piezoelectric MEMS microphone as claimed in claim 1, further comprising a second piezoelectric structure layer and a third electrode layer, wherein the second piezoelectric structure layer is disposed on a side of the second electrode layer 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 a novel piezoelectric MEMS microphone as claimed in claim 2, wherein the first connection hole and the second connection hole penetrate the second piezoelectric structure layer and the third electrode layer.
4. The structure of a novel piezoelectric MEMS microphone as claimed in claim 3, further comprising a support portion disposed on a side of the substrate away from the first electrode.
5. The structure of a novel piezoelectric MEMS microphone as claimed in claim 4, further comprising a silicon oxide part disposed on a side of the substrate close to the first electrode layer and a device layer silicon part disposed between the silicon oxide part and the first electrode layer.
6. An apparatus of a novel piezoelectric MEMS microphone, the apparatus comprising: the structure of a digital-to-analog conversion device and the novel piezoelectric MEMS microphone according to any one of claims 1 to 5, wherein the positive electrode and the negative electrode of the digital-to-analog conversion device are electrically connected with the first electrode layer and the second electrode layer of the structure respectively, and are used for converting voltage signals output by the first electrode layer and the second electrode layer into digital signals.
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