CN114866936A - Differential capacitance type MEMS microphone and manufacturing method thereof - Google Patents
Differential capacitance type MEMS microphone and manufacturing method thereof Download PDFInfo
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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
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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
- H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
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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
- H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
- H04R31/003—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor for diaphragms or their outer suspension
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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
- H04R7/00—Diaphragms for electromechanical transducers; Cones
- H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
- H04R7/04—Plane diaphragms
Abstract
The present invention relates to a differential capacitive MEMS microphone and a method of manufacturing the same, the microphone comprising: a first diaphragm; the first back plate is arranged above the first vibrating diaphragm; a second back plate; the second vibrating diaphragm is arranged above the second back plate; the supporting layer is arranged between the first vibrating diaphragm and the first back plate and between the second back plate and the second vibrating diaphragm; the first diaphragm and the first backboard form a first capacitor used for outputting a first capacitance signal, the second diaphragm and the second backboard form a second capacitor used for outputting a second capacitance signal, and the first capacitance signal and the second capacitance signal form a differential signal. The first capacitance value signal and the second capacitance value signal output by the microphone form a differential signal, so that the high-frequency noise immunity can be improved, and a better audio signal processing effect is ensured. And the manufacturing process is simple, the photoetching level is less, the method is compatible with the existing mature technology, the large-scale mass production is easier, and the manufacturing difficulty and the cost are low.
Description
Technical Field
The invention relates to the technical field of semiconductor devices, in particular to a differential capacitance type MEMS microphone and a manufacturing method thereof.
Background
Micro-Electro-Mechanical systems (MEMS) devices are typically produced using integrated circuit fabrication techniques. The silicon-based microphone has wide application prospect in the fields of hearing aids, mobile communication equipment and the like. MEMS microphone chips have been studied for over 20 years, during which many types of microphone chips have been developed, among which piezo-resistive, and capacitive, among others, with capacitive MEMS microphones being the most widely used. The capacitive MEMS microphone has the following advantages: small volume, high sensitivity, good frequency characteristics, low noise, etc.
The structure of the capacitor type MEMS microphone is designed by combining a single vibrating diaphragm and a single back plate, and the structure is designed by arranging the vibrating diaphragm of the MEMS microphone at the lower part and arranging the back plate at the upper part; the other is the structural design that the vibrating membrane of the MEMS microphone is arranged on the upper part and the back plate is arranged on the lower part. The above-mentioned microphone structure has poor anti-interference capability, and the THD Value (Total Harmonic Distortion) of the microphone is large.
Disclosure of Invention
Accordingly, there is a need for a differential capacitive MEMS microphone with high interference rejection and a method for manufacturing the same.
A differential capacitive MEMS microphone comprising:
a first diaphragm;
the first back plate is arranged above the first vibrating diaphragm;
a second back plate;
the second vibrating diaphragm is arranged above the second back plate;
the supporting layer is arranged between the first vibrating diaphragm and the first back plate and between the second back plate and the second vibrating diaphragm;
the first capacitance formed by the first diaphragm and the first backboard is used for outputting a first capacitance signal, the second capacitance formed by the second diaphragm and the second backboard is used for outputting a second capacitance signal, and the first capacitance signal and the second capacitance signal form a differential signal.
When sound pressure acts on the device downwards, the first vibrating diaphragm and the second vibrating diaphragm move downwards, the distance between the first vibrating diaphragm and the first back plate is increased, and the first capacitance value is decreased; and the distance between the second diaphragm and the second back plate becomes smaller, and the second capacitance value becomes larger. Because the first capacitance value and the second capacitance value are opposite in change, the first capacitance value signal and the second capacitance value signal form a differential signal, the high-frequency immunity can be improved, and a better audio signal processing effect is ensured.
In one embodiment, the first diaphragm has the same shape and size as the second diaphragm, and the first backplate has the same shape and size as the second backplate.
In one embodiment, the support layer is a sacrificial layer made of an insulating material.
In one embodiment, no supporting layer is disposed at a portion between the first diaphragm and the first backplate so as to form a first cavity, and no supporting layer is disposed at a portion between the second diaphragm and the second backplate so as to form a second cavity.
In one embodiment, the first back plate and the second back plate are both provided with a plurality of sound holes.
In one embodiment, the first diaphragm and the second diaphragm are flexible films, and the first backplate and the second backplate are rigid films.
In one embodiment, the liquid crystal display further comprises a substrate, and the first diaphragm and the second back plate are arranged on the substrate.
In one embodiment, the liquid crystal display further comprises an insulating layer, and the insulating layer is arranged between the substrate and the first diaphragm and between the substrate and the second back plate.
In one embodiment, the method further comprises the following steps:
the first bonding pad is arranged on the upper surface of the first back plate;
the second bonding pad is arranged on the upper surface of the first vibrating diaphragm;
the third bonding pad is arranged on the upper surface of the second vibrating diaphragm;
and the fourth bonding pad is arranged on the upper surface of the second back plate.
In one embodiment, the first diaphragm and the second diaphragm are both made of conductive materials.
A method of manufacturing a differential capacitive MEMS microphone, comprising:
forming a first vibrating diaphragm and a second back plate on a substrate through deposition, photoetching and etching;
forming a sacrificial layer on the first vibrating diaphragm and the second back plate through deposition, photoetching and etching;
forming a second vibrating diaphragm and a first back plate on the sacrificial layer through deposition, photoetching and etching;
etching the substrate into a back cavity by photoetching and etching;
and releasing the sacrificial layer by corrosive agent to form a first cavity between the first diaphragm and the first back plate, form a second cavity between the second diaphragm and the second back plate, and form a plurality of sound holes on the first back plate and the second back plate.
The manufacturing method of the differential capacitance type MEMS microphone has the advantages of simple manufacturing process, fewer photoetching levels, compatibility with the existing mature technology, easiness in large-scale mass production, low production and manufacturing difficulty and low cost.
In one embodiment, after the step of forming the second diaphragm and the first backplate and before the step of etching the substrate into the back cavity, the method further includes a step of forming a first pad located on the upper surface of the first backplate, a second pad located on the upper surface of the first diaphragm, a third pad located on the upper surface of the second diaphragm, and a fourth pad located on the upper surface of the second backplate by deposition, photolithography, and etching.
In one embodiment, the step of etching the substrate into the back cavity by photolithography and etching includes forming the back cavity by a double-sided photolithography and inductively coupled plasma etching process.
In one embodiment, the step of etching the substrate into the back cavity further includes back thinning the substrate.
In one embodiment, the step of releasing the sacrificial layer by etchant comprises etching the sacrificial layer using a buffered oxide etchant.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is an exemplary capacitive MEMS microphone structure;
FIG. 2 is an exemplary dual-backplate structure of a capacitive MEMS microphone structure;
FIG. 3 is a schematic diagram of a capacitive MEMS microphone according to an embodiment;
FIG. 4 is a flow diagram of a method of fabricating a capacitive MEMS microphone in one embodiment;
FIGS. 5a, 5b and 5c are schematic cross-sectional views of the device of step S410 in one embodiment;
FIG. 6 is a schematic cross-sectional view of a device after completion of step S420 in one embodiment;
FIGS. 7a, 7b, and 7c are schematic cross-sectional views of the device of step S430 in one embodiment;
FIG. 8 is a schematic cross-sectional view of a device after completion of step S440 in one embodiment;
FIG. 9 is a cross-sectional diagram illustrating the completed device in step S450 according to one embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only. When an element or layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it can be directly on, adjacent to, connected or coupled to the other elements or layers or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
When the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
Embodiments of the invention are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the invention, such that variations from the shapes shown are to be expected, for example, due to manufacturing techniques and/or tolerances. Thus, embodiments of the invention should not be limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing techniques. For example, an implanted region shown as a rectangle will typically have rounded or curved features and/or implant concentration gradients at its edges rather than a binary change from implanted to non-implanted region. Also, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation is performed. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present invention.
Fig. 1 shows an exemplary structure of a capacitive MEMS microphone, which has poor interference rejection and a large THD Value (Total Harmonic Distortion) of the microphone.
Fig. 2 is an exemplary structure of a capacitive MEMS microphone with a dual-backplate structure, which can eliminate the non-linear change of capacitance caused by the vibration of the diaphragm and reduce the total harmonic distortion. However, since the thickness of the structure is large, warpage of the wafer (wafer) is large (mainly, warpage of the substrate is large). On the other hand, the structure is complex, the photoetching level is more, the MEMS microphone structure is incompatible with the existing mature MEMS microphone structure, the manufacturing cost and the difficulty are higher, and the MEMS microphone structure is not beneficial to market competition.
Referring to fig. 3, the present application provides a differential capacitive MEMS microphone, including a first diaphragm 112, a first back plate 114, a second diaphragm 122, a second back plate 124, and a support layer 130. The first back plate 114 is disposed above the first diaphragm 112, and the second diaphragm 122 is disposed above the second back plate 124. The support layer 130 is disposed between the first diaphragm 112 and the first backplate 114, and between the second backplate 124 and the second diaphragm 122.
The first capacitor C1 formed by the first diaphragm 112 and the first backplate 114 is used to output a first capacitance signal, the second capacitor C2 formed by the second diaphragm 122 and the second backplate 124 is used to output a second capacitance signal, and the first capacitance signal and the second capacitance signal form a differential signal.
In one embodiment of the present application, the first diaphragm 112 and the second diaphragm 122 are flexible films, and the first backplate 114 and the second backplate 124 are rigid films. Specifically, the first diaphragm 112 and the second diaphragm 122 are flexible films having tensile stress and being conductive, and can deform to some extent when ambient air vibrates, and form a plate capacitor together with the first back plate 114/the second back plate 124, as one pole of the plate capacitor. The first back plate 114 and the second back plate 124 have large stress and are fixed when the first diaphragm 112 and the second diaphragm 122 vibrate. In one embodiment of the present application, the first diaphragm 112 is softer than the first backplate 114 and the second diaphragm 122 is softer than the second backplate 124.
In one embodiment of the present application, the first diaphragm 112, the second diaphragm 122, the first backplate 114 and the second backplate 124 are made of conductive materials. In other embodiments, the first diaphragm 112, the second diaphragm 122, the first back plate 114, and the second back plate 124 may also be a composite structure including a conductive layer, for example, one or more of the following materials: si, Ge, SiGe, SiC, Al, W, Ti, or Al/W/Ti nitrides. In the embodiment shown in FIG. 3, the first backplate 114 comprises a polysilicon film of conductive material and a silicon nitride film on the polysilicon film; similarly, the second back plate 124 includes a polysilicon film of conductive material and a silicon nitride film on the polysilicon film.
It will be appreciated that fig. 3 is an example of some of the main structures of a capacitive MEMS microphone, which may have other structures than those shown in the figures.
When sound pressure acts on the device downwards, the first diaphragm 112 and the second diaphragm 122 move downwards, the distance between the first diaphragm 112 and the first back plate 114 is increased, and the first capacitance value is decreased; and the distance between the second diaphragm 122 and the second back plate 124 becomes smaller, and the second capacitance value becomes larger. Because the first capacitance value and the second capacitance value are opposite in change, the first capacitance value signal and the second capacitance value signal form a differential signal, the high-frequency immunity can be improved, the total harmonic distortion is reduced, and the better audio signal processing effect is ensured.
In one embodiment of the present application, the shape and size of the first diaphragm 112 are the same as those of the second diaphragm 122, the shape and size of the first back plate 114 are the same as those of the second back plate 124, and the material of the first diaphragm 112 is the same as that of the second diaphragm 122. This arrangement makes it possible to make the absolute value of the amount of change in the first capacitance value equal to the absolute value of the amount of change in the second capacitance value.
In the embodiment shown in fig. 3, the support layer 130 is not disposed at a portion between the first diaphragm 112 and the first back plate 114 to form the first cavity 131, and the support layer 130 is not disposed at a portion between the second diaphragm 122 and the second back plate 124 to form the second cavity 133. In one embodiment of the present application, the first cavity 131 and the second cavity 133 are cylindrical cavities; in other embodiments, the first cavity 131 and the second cavity 133 may also be rectangular parallelepiped or other shapes.
In one embodiment of the present application, the support layer 130 is a sacrificial layer, and the cavity is actually released from the sacrificial layer, and during the release process, the sacrificial layer at the cavity position is etched away to form the cavity. In one embodiment of the present application, the thickness of the support layer 130 is 3-5 microns. In one embodiment of the present application, the supporting layer 130 is made of an insulating material. In one embodiment of the present application, the conductive structure (polysilicon film) of the second backplate 124 and the first diaphragm 112 are insulated and isolated by a support layer 130.
In the embodiment shown in fig. 3, a plurality of sound holes with specific sizes are formed on both the first back plate 114 and the second back plate 124, and the sound waves can be transmitted to the first diaphragm 112/the second diaphragm 122 through the sound holes. In one embodiment of the present application, the sound holes are evenly distributed on the first backing plate 114 and the second backing plate 124; in other embodiments, the sound holes may also be non-uniformly distributed, such as more concentrated in the middle area of first/ second backing plates 114, 124.
In the embodiment shown in fig. 3, the differential capacitive MEMS microphone further comprises a substrate 110. The first diaphragm 112 and the second backplate 124 are disposed on the substrate 110. In the present embodiment, the material of the substrate 110 is Si, and the material of the substrate 110 may also be other semiconductors or semiconductor compounds, such as Ge, SiGe, SiC, SiO2, or Si3N 4. The substrate 110 has a back cavity opened just below the first cavity 131 and the second cavity 133.
In the embodiment shown in fig. 3, the differential capacitance MEMS microphone further includes an insulating layer 113, and the insulating layer 113 is disposed between the substrate 110 and the first diaphragm 112, and between the substrate 110 and the second backplate 124. The insulating layer 113 serves to insulate the substrate 100 and the lower electrode layer from each other. In one embodiment of the present application, the insulating layer 113 also serves as an etch stop for the back cavity etch. In one embodiment of the present application, the insulating layer 113 is a silicon oxide layer.
In one embodiment of the present application, the differential capacitive MEMS microphone further includes a first pad 142 disposed on the upper surface of the first backplate 114, a second pad 144 disposed on the upper surface of the first diaphragm 112, a third pad 146 disposed on the upper surface of the second diaphragm 122, and a fourth pad 148 disposed on the upper surface of the second backplate 124. In one embodiment of the present application, the first pad 142, the second pad 144, the third pad 146, and the fourth pad 148 are all composed of metal. The first bonding pad 142, the second bonding pad 144, the third bonding pad 146 and the fourth bonding pad 148 can lead out the first back plate 114, the first diaphragm 112, the second diaphragm 122 and the second back plate 124 when the differential capacitor type MEMS microphone is packaged and wired. In the embodiment shown in fig. 3, the first pads 142 are disposed on the conductive structures (polysilicon films) extending from the first back plate 114 to the support layer 130, and the silicon nitride films are not disposed at the positions where the first pads 142 are disposed; similarly, the fourth pads 148 are disposed on the conductive structures (polysilicon films) extending from the second back plate 124 to the support layer 130, and the silicon nitride films are not disposed at the positions where the fourth pads 148 are disposed.
In an embodiment of the present application, the differential capacitive MEMS microphone may increase an acoustic overload point of 10% of Total Harmonic Distortion (THD) to 135dB SPL, and a signal-to-noise ratio may be 70dB, which is improved by about 6dB compared with the prior art. The distance of the microphone for receiving the voice command of the user is doubled, and the microphone is particularly suitable for far-field sound pickup equipment such as intelligent sound boxes and intelligent homes.
The present application correspondingly provides a method for manufacturing a differential capacitive MEMS microphone, which can be used to manufacture the differential capacitive MEMS microphone described in any of the above embodiments. Fig. 4 is a flow chart of a method for manufacturing a differential capacitive MEMS microphone in an embodiment, comprising the steps of:
and S410, forming a first vibrating diaphragm and a second back plate on the substrate through deposition, photoetching and etching.
Referring to fig. 5a, after depositing polysilicon (Poly) and silicon nitride, a polysilicon layer 212a and a silicon nitride layer 224a are formed.
In the embodiment shown in fig. 5a, a step of forming a silicon oxide layer 213 on the substrate 210 is further included prior to depositing the polysilicon and silicon nitride. Polysilicon and silicon nitride are deposited over the silicon oxide layer 213. In one embodiment of the present application, the silicon oxide layer 213 is formed by depositing a field oxide layer. In other embodiments, the silicon oxide layer 213 may also be formed by thermal growth.
In one embodiment of the present application, the material of the substrate 210 is Si. The material of the substrate 210 may also be other semiconductors or semiconductor compounds, such as one of Ge, SiGe, SiC, SiO2, or Si3N 4.
Referring to fig. 5b, after depositing polysilicon and silicon nitride, the silicon nitride layer 224a is etched and etched; the photoresist is then removed, and the polysilicon layer 212a is then etched and etched to form the second backplate 224 and the first diaphragm 212, as shown in fig. 5 c.
And S420, forming a sacrificial layer on the first vibrating diaphragm and the second back plate through deposition, photoetching and etching.
Referring to FIG. 6, in the present embodiment, an oxide layer is deposited on the first diaphragm 212 and the second backplate 224, and then a sacrificial layer 230 is formed by photolithography and etching.
And S430, forming a second diaphragm and a first back plate on the sacrificial layer through deposition, photoetching and etching.
Referring to fig. 7a, polysilicon and silicon nitride are deposited on sacrificial layer 230 to form polysilicon layer 222a and silicon nitride layer 214 a. The silicon nitride layer 214a is then lithographically and etched, as shown in FIG. 7 b; the photoresist is removed, and the polysilicon layer 222a is etched by photolithography to form the first backplate 214 and the second diaphragm 222, as shown in fig. 7 c. .
S440, forming first to fourth pads by deposition, photolithography and etching.
A metal layer is deposited and then patterned and etched through PAD (PAD) metal lithography to form a first PAD 242 on the upper surface of the first backplate 214, a second PAD 244 on the upper surface of the first diaphragm 212, a third PAD 246 on the upper surface of the second diaphragm 222, and a fourth PAD 248 on the upper surface of the second backplate 224. Specifically, the first pads 242 are disposed on the conductive structure (polysilicon film) extending from the first backplane 214 to the support layer 230, and the silicon nitride film is not disposed at the positions where the first pads 242 are disposed; similarly, the fourth pads 248 are disposed on the conductive structures (polysilicon films) of the second backplane 224 extending to the support layer 230, and the locations where the fourth pads 248 are disposed are not disposed with silicon nitride films, see fig. 8.
S450, etching the substrate to form a back cavity through photoetching and etching.
In one embodiment of the present application, the photolithography uses a double-sided photolithography process, and then the back surface of the substrate 210 is etched by an Inductively Coupled Plasma (ICP) etching process to form a back cavity, see fig. 9.
In an embodiment of the present application, step S450 is preceded by a step of back thinning the substrate 210. Specifically, the thinning may be performed after step S440 and before step S450.
S460, releasing the sacrificial layer by the etchant.
After the etching of the sacrificial layer 230 is completed, a first cavity is formed between the first diaphragm 212 and the first backplate 214, a second cavity is formed between the second diaphragm 222 and the second backplate 224, and a plurality of sound holes are formed in the first backplate 214. Since the material of the sacrificial layer 230 is the same as that of the silicon oxide layer 213, the silicon oxide layer 213 is etched together, thereby forming a plurality of acoustic holes on the second backplate 224. The etched structure can be seen in fig. 3, in which the conductive structure (polysilicon film) of the second backplate 124 and the first diaphragm 112 are isolated from each other by the support layer 130. .
In one embodiment of the present application, the etchant is a Buffered Oxide Etchant (BOE).
The manufacturing method of the differential capacitance type MEMS microphone has the advantages of simple manufacturing process, fewer photoetching levels (mainly including seven photoetching steps S410-S450, wherein the step S410 and the step S430 are both two photoetching steps, and the structure shown in the reference figure 2 generally needs more than 12 photoetching steps), compatibility with the existing mature technology, easiness in large-scale mass production, and low production and manufacturing difficulty and cost.
It should be understood that, although the steps in the flowchart of fig. 4 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least a portion of the steps in fig. 4 may include multiple steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, which are not necessarily performed in sequence, but may be performed in turn or alternately with other steps or at least a portion of the other steps or stages.
In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features of the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A differential capacitive MEMS microphone, comprising:
a first diaphragm;
the first back plate is arranged above the first vibrating diaphragm;
a second back plate;
the second vibrating diaphragm is arranged above the second back plate;
the supporting layer is arranged between the first vibrating diaphragm and the first back plate and between the second back plate and the second vibrating diaphragm;
the first diaphragm and the first backboard form a first capacitor used for outputting a first capacitance signal, the second diaphragm and the second backboard form a second capacitor used for outputting a second capacitance signal, and the first capacitance signal and the second capacitance signal form a differential signal.
2. The differential capacitive MEMS microphone of claim 1, wherein the first diaphragm is the same shape and size as the second diaphragm, and the first backplate is the same shape and size as the second backplate.
3. The differential capacitance MEMS microphone of claim 1, wherein the supporting layer is a sacrificial layer made of an insulating material, a portion between the first diaphragm and the first backplate is not provided with a supporting layer to form a first cavity, and a portion between the second diaphragm and the second backplate is not provided with a supporting layer to form a second cavity.
4. The differential capacitive MEMS microphone of claim 1, wherein the first backplate and the second backplate each have a plurality of sound holes formed therein.
5. The differential capacitive MEMS microphone of claim 1, wherein the first and second diaphragms are flexible membranes and the first and second back plates are rigid membranes.
6. The differential capacitive MEMS microphone of claim 1, further comprising a substrate, wherein the first diaphragm and the second backplate are disposed on the substrate.
7. The differential capacitive MEMS microphone of claim 6, further comprising an insulating layer disposed between the substrate and the first diaphragm and between the substrate and the second backplate.
8. The differential capacitive MEMS microphone of claim 1, further comprising:
the first bonding pad is arranged on the upper surface of the first back plate;
the second bonding pad is arranged on the upper surface of the first vibrating diaphragm;
the third bonding pad is arranged on the upper surface of the second vibrating diaphragm;
and the fourth bonding pad is arranged on the upper surface of the second back plate.
9. A method of manufacturing a differential capacitive MEMS microphone, comprising:
forming a first vibrating diaphragm and a second back plate on a substrate through deposition, photoetching and etching;
forming a sacrificial layer on the first vibrating diaphragm and the second back plate through deposition, photoetching and etching;
forming a second vibrating diaphragm and a first back plate on the sacrificial layer through deposition, photoetching and etching;
etching the substrate into a back cavity by photoetching and etching;
and releasing the sacrificial layer by using a corrosive agent, forming a first cavity between the first diaphragm and the first back plate, forming a second cavity between the second diaphragm and the second back plate, and forming a plurality of sound holes on the first back plate and the second back plate.
10. The method of manufacturing a differential capacitive MEMS microphone according to claim 9, wherein after the step of forming the second diaphragm and the first backplate and before the step of etching the substrate into the back cavity, the method further comprises a step of forming a first bonding pad on an upper surface of the first backplate, a second bonding pad on an upper surface of the first diaphragm, a third bonding pad on an upper surface of the second diaphragm, and a fourth bonding pad on an upper surface of the second backplate by deposition, photolithography, and etching.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110076653.8A CN114866936A (en) | 2021-01-20 | 2021-01-20 | Differential capacitance type MEMS microphone and manufacturing method thereof |
| PCT/CN2021/113044 WO2022156200A1 (en) | 2021-01-20 | 2021-08-17 | Differential-capacitance type mems microphone and manufacturing method therefor |
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| CN202110076653.8A CN114866936A (en) | 2021-01-20 | 2021-01-20 | Differential capacitance type MEMS microphone and manufacturing method thereof |
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| WO2022156200A1 (en) | 2022-07-28 |
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