WO2020000648A1 - Mems麦克风 - Google Patents

Mems麦克风 Download PDF

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Publication number
WO2020000648A1
WO2020000648A1 PCT/CN2018/104439 CN2018104439W WO2020000648A1 WO 2020000648 A1 WO2020000648 A1 WO 2020000648A1 CN 2018104439 W CN2018104439 W CN 2018104439W WO 2020000648 A1 WO2020000648 A1 WO 2020000648A1
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WO
WIPO (PCT)
Prior art keywords
diaphragm
substrate
mems microphone
microphone
lower electrode
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PCT/CN2018/104439
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English (en)
French (fr)
Inventor
邹泉波
董永伟
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歌尔股份有限公司
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Application filed by 歌尔股份有限公司 filed Critical 歌尔股份有限公司
Priority to US16/760,803 priority Critical patent/US11297414B2/en
Publication of WO2020000648A1 publication Critical patent/WO2020000648A1/zh

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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
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only 
    • H04R1/28—Transducer mountings or enclosures modified by provision of mechanical or acoustic impedances, e.g. resonator, damping means
    • H04R1/2807—Enclosures comprising vibrating or resonating arrangements
    • H04R1/283—Enclosures comprising vibrating or resonating arrangements using a passive diaphragm
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
    • B81B3/0018—Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators
    • 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
    • H04R19/005—Electrostatic transducers using semiconductor materials
    • 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
    • H04R31/006—Interconnection of transducer parts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B2201/00—Specific applications of microelectromechanical systems
    • B81B2201/02—Sensors
    • B81B2201/0257—Microphones or microspeakers
    • 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

Definitions

  • the present invention relates to the field of acoustic-electric conversion, and more particularly, to a mechanism of a MEMS microphone, particularly a microphone structure having a high SNR.
  • the current MEMS microphone whether it is a capacitive sensing structure or a piezoelectric sensing structure, needs to design a huge back cavity with environmental pressure to ensure that the rigidity of the flowing air is far from the diaphragm.
  • the volume of the dorsal cavity is usually much larger than 1 mm 3 , for example, it is usually designed to be 1-15 mm 3 .
  • the microphone chip when packaged, its cavity needs to be opened. This limits the design of the smallest MEMS microphone package (> 3mm 3 ).
  • An object of the present invention is to provide a new technical solution for a MEMS microphone.
  • a MEMS microphone including a substrate and a diaphragm supported above the substrate through a spacer, the substrate, the spacer, and the diaphragm surrounding a vacuum cavity;
  • the static deflection distance of the membrane under atmospheric pressure is less than the distance between the diaphragm and the substrate;
  • a lower electrode forming a capacitor structure with the diaphragm is provided on the substrate, and an electret layer that provides an electric field between the diaphragm and the lower electrode is provided on the substrate.
  • the vibrating membrane is made of an insulating material, and an upper electrode forming a capacitor structure with a lower electrode is provided on the vibrating membrane.
  • the diaphragm uses a composite structure, and the upper electrode is disposed in the composite structure of the diaphragm.
  • the upper electrode on the diaphragm is connected to the circuit layout on the substrate through a lead.
  • the mechanical sensitivity of the diaphragm is 0.02 to 0.9 nm / Pa.
  • the initial gap between the diaphragm and the substrate is 1-100 ⁇ m.
  • it also includes an ASIC circuit, which is integrated on the substrate.
  • a reinforcing portion is provided in a middle region of the diaphragm away from the vacuum chamber.
  • a pad for external connection is provided on a side of the substrate remote from the vacuum chamber.
  • the electric field between the diaphragm and the lower electrode is 100-300V / ⁇ m.
  • the diaphragm and the substrate are enclosed in a vacuum cavity, an electric field can be provided between the diaphragm and the substrate through an electret layer. Moreover, a high electric field can be formed in the vacuum cavity without causing the problem of breakdown, which greatly improves the sensitivity of the MEMS microphone of the present invention.
  • a vacuum cavity is enclosed between the diaphragm and the substrate, and the viscosity of the air in the vacuum cavity is much lower than the viscosity of the air in the ambient pressure, thereby reducing the effect of acoustic resistance on the vibration of the diaphragm and improving the vibration of the diaphragm.
  • Signal-to-noise ratio of the microphone since the MEMS microphone of this structure does not require a large-capacity back cavity, the overall size of the MEMS microphone can be greatly reduced, and the reliability of the microphone is enhanced.
  • FIG. 1 is a schematic structural diagram of a first embodiment of a microphone according to the present invention.
  • FIG. 2 is a schematic structural diagram of a second embodiment of a microphone according to the present invention.
  • FIG. 3 is a schematic diagram of the operation principle of the microphone in the embodiment of FIG. 2.
  • FIG. 4 is a schematic diagram of a packaging method of a microphone according to the present invention.
  • the present invention provides a MEMS microphone including a substrate 1 and a diaphragm 2 supported above the substrate 1 by a spacer 3.
  • the substrate 1, the spacer 3, and the diaphragm 2 form a vacuum cavity. 4.
  • the substrate 1 of the present invention can be made of single crystal silicon or other materials well known to those skilled in the art, and the spacer 3 can be formed by layer-by-layer deposition, patterning, and sacrificial processes, and supported on the substrate 1 by the spacer 3.
  • the vacuum chamber 4 can be sealed, for example, by low pressure plasma enhanced chemical vapor deposition (PECVD) at 200-350 ° C.
  • PECVD low pressure plasma enhanced chemical vapor deposition
  • the vacuum chamber 4 is preferably less than 1 kPa, which makes the residual gas viscosity in the vacuum chamber 4 much lower than the air viscosity at standard pressure.
  • the diaphragm 2 Since a vacuum cavity lower than atmospheric pressure is formed between the diaphragm and the substrate 1, the diaphragm 2 will statically deflect under atmospheric pressure and no sound pressure, that is, the diaphragm 2 will be statically deflected toward the substrate 1. .
  • the static deflection distance of the diaphragm is designed to be smaller than the distance between the diaphragm 2 and the substrate 1. This can be achieved mainly by changing the rigidity of the diaphragm 2 and / or changing the distance between the diaphragm and the substrate 1.
  • the size of the diaphragm 2 can be increased.
  • the rigidity of the diaphragm can also be improved by selecting a suitable diaphragm material.
  • the diaphragm 2 can be designed to have a mechanical sensitivity of 0.02 to 0.9 nm / Pa. In other words, every time 1Pa pressure is applied, the diaphragm 2 will deflect from 0.02-0.9nm.
  • the rigidity of this diaphragm 2 is 10-100 times that of the traditional diaphragm, making the diaphragm 2 hard enough to resist external Atmospheric pressure.
  • the corresponding initial gap between the diaphragm 2 and the substrate 1 can be designed in the range of 1-100 ⁇ m, and with the rigid diaphragm 2 described above, the problem that the diaphragm 2 collapses does not occur under atmospheric pressure.
  • the MEMS microphone can use a highly sensitive detection component, such as an electret type capacitance detection structure.
  • the detection structure includes a lower electrode 6 disposed on the substrate 1, and the lower electrode 6 and the diaphragm 2 form a capacitor structure capable of outputting a variable electrical signal.
  • the diaphragm 2 may be made of insulating material.
  • An upper electrode 5 is provided on the diaphragm 2, and the lower electrode 6 and the upper electrode 5 on the diaphragm 2 constitute a device capable of outputting a changed electrical signal.
  • the upper electrode 5 and the lower electrode 6 may be formed by a MEMS deposition and etching process well known to those skilled in the art, which will not be described in detail here.
  • the lower electrode 6 may be disposed on the substrate 1 at a position on the side of the vacuum chamber 4.
  • an insulating layer 8 is provided to bury the lower electrode 6.
  • the upper electrode 5 may be provided on the diaphragm 2 on a side of the vacuum chamber 4 or on the diaphragm 2 on a side remote from the vacuum chamber 4.
  • the diaphragm 2 may adopt a composite structure.
  • a cover layer 20 having a sacrificial hole needs to be first provided on the sacrificial layer, and the sacrificial layer below the cover layer 20 is etched through the sacrificial hole;
  • a filling layer 21 is deposited on the cover layer 20 to close the sacrificial holes in the cover layer 20 to form a vacuum cavity.
  • the upper electrode 5 may be provided in the composite structure of the diaphragm 2, for example, it is formed on the filling layer 21, and a passivation layer 22 is provided on the outside for protection, which is not described in detail here.
  • the microphone of the present invention is provided on the substrate 1 with an electret layer 7 that provides an electric field between the diaphragm 2 / the upper electrode 5 and the lower electrode 6.
  • the electret layer 7 is disposed on the substrate 1, is located above the lower electrode 6, and is covered by an insulating layer 8.
  • the diaphragm 2 vibrates, the interval between the upper electrode 5 and the lower electrode 6 changes, so that the capacitor structure can output a changed electrical signal.
  • the working principle of such a capacitor belongs to the common knowledge of those skilled in the art.
  • the electret layer 7 may be configured to provide an electric field of 100-300 V / ⁇ m for the diaphragm 2 and the lower electrode 6,
  • the diaphragm 2 and the substrate 1 surround a vacuum cavity 4, a high electric field can be formed in the vacuum cavity 4 without causing a problem of breakdown.
  • the diaphragm 2 with high rigidity is used.
  • the electric field between the upper electrode 6 and the lower electrode 5 is 100-300V / ⁇ m, that is, it can reach several hundred volts in a vacuum gap of several micrometers, which is 10 to 100 times the electric field of a conventional microphone. This can greatly improve the sensitivity of the MEMS microphone of the present invention.
  • a vacuum cavity is enclosed between the diaphragm 2 and the substrate 1.
  • the viscosity of the air in the vacuum cavity is much lower than the air viscosity in the ambient pressure, so that the effect of acoustic resistance on the vibration of the diaphragm can be reduced. Improved microphone signal-to-noise ratio.
  • the MEMS microphone of this structure does not require a large-capacity back cavity, the overall size of the MEMS microphone can be greatly reduced, and the reliability of the microphone is enhanced.
  • a reinforcing portion 9 is provided in a middle region of the diaphragm 2 side away from the vacuum chamber, as shown in FIG. 2.
  • the reinforcing portion 9 is used to strengthen the rigidity of the middle region of the diaphragm 2, and it can be regarded as a central thickening layer.
  • the material and the material of the diaphragm 2 are the same or different.
  • the region of the diaphragm 2 reinforced by the reinforcing portion 9 can be deflected toward the substrate 1 synchronously, and the diaphragm
  • the central area of 2 makes a piston movement similar to the up-and-down translation, instead of the traditional curved bending motion of the diaphragm, which increases the amount of change in the capacitor detection.
  • the MEMS microphone of the present invention can be manufactured by a surface micromachining or bulk silicon micromachining process, and also by a bonding process.
  • a part of the spacer, the lower electrode, and the electret layer are formed on the first substrate by a surface micromachining or bulk silicon micromachining process, and the diaphragm and the other part of the spacer are formed on the second substrate.
  • an upper electrode, a passivation layer, and a pad can be formed on the diaphragm 2 after the second substrate is completely removed. This is no longer specified.
  • the upper electrode 5 on the diaphragm 2 can be connected to a pin of the substrate 1 through a lead or the circuit layout. Since there is a gap 3 between the diaphragm 2 and the substrate 1, one end of the lead wire is conductive with the upper electrode 5 during conduction, and the other end extends to the position of the gap 3 on the diaphragm 2 and penetrates.
  • the MEMS microphone of the present invention does not require a large-capacity back cavity, a wafer-level package (WLP) can be completely used, and a conventional PCB board package is not required.
  • the microphone can be directly mounted on an external terminal.
  • a pad 13 is formed on an end of the substrate 1 away from the vacuum chamber 4, and an electrical signal located above the substrate 1 can be led to the solder through the metallized through hole 12.
  • the plate 13 enables the MEMS microphone to be directly mounted on the external terminal through the pad 13.
  • the ASIC circuit of the microphone can be integrated on the substrate 1, and the output end of the capacitor and the ASIC circuit can be conducted through the circuit layout on or in the substrate 1, so that The electrical signal output by the capacitor can be processed by the ASIC circuit.
  • the ASIC chip 11 may also be directly provided on the substrate 1, and will not be described in detail here.
  • the edge of the diaphragm 2 and the substrate 1 and the ASIC chip 11 may be packaged through a plastic package 10 to expose only the region where the diaphragm 2 is suspended.
  • the external pins can be formed on the upper surface of the substrate (the side adjacent to the diaphragm), and the microphone can be directly mounted to the outside by means of bump welding (solder ball). On the terminal.
  • the MEMS microphone of the present invention can also adopt a conventional package structure, for example, a package structure surrounded by a circuit board and a housing is provided.
  • the MEMS microphone is installed in the package structure to form a traditional top package structure or top package structure.
  • the form of the microphone module is then mounted on an external terminal.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Otolaryngology (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
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  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
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Abstract

本发明公开了一种MEMS麦克风，包括衬底以及通过间隔部支撑在衬底上方的振膜，所述衬底、间隔部、振膜围成了真空腔；其中，振膜在大气压力下的静态偏转距离小于振膜与衬底之间的距离；在所述衬底上设置有与振膜构成电容器结构的下电极，在所述衬底上设置有为振膜与下电极之间提供电场的驻极体层。本发明的麦克风，可通过驻极体层来提供电场；另外真空腔可以降低声阻对振膜振动的影响，提高麦克风的信噪比；另外，由于该结构的MEMS麦克风不需要较大容积的背腔，因此可以大大降低MEMS麦克风的整体尺寸，增强了麦克风的可靠性。 (图1)

Description

MEMS麦克风 技术领域
本发明涉及声电转换领域，更具体地，涉及一种MEMS麦克风的机构，尤其是一种具有高SNR的麦克风结构。
背景技术
现在的MEMS麦克风，无论是电容式的感测结构还是压电式的感测结构，均需要设计一个具有环境压力的巨大后腔，以确保流动空气的刚性远远振膜。背腔的容积通常远大于1mm 3，例如通常设计为1-15mm 3。而且麦克风芯片在封装的时候，需要开放其腔体。这就限制了MEMS麦克风最小尺寸封装的设计(>3mm 3)。
这是由于如果后腔容积过小，则不利于空气的流通，这种空气的刚性则会大大降低振膜的机械灵敏度。另外，为了均压，背极板上通常会设计密集的通孔，由于空气粘度造成的间隙或穿孔中的空气流动阻力成为MEMS麦克风噪声的主导因素，从而限制了麦克风的高信噪比性能。
发明内容
本发明的一个目的是提供一种MEMS麦克风的新技术方案。
根据本发明的第一方面，提供了一种MEMS麦克风，包括衬底以及通过间隔部支撑在衬底上方的振膜，所述衬底、间隔部、振膜围成了真空腔；其中，振膜在大气压力下的静态偏转距离小于振膜与衬底之间的距离；
在所述衬底上设置有与振膜构成电容器结构的下电极，在所述衬底上设置有为振膜与下电极之间提供电场的驻极体层。
可选地，所述振膜采用绝缘材质，在所述振膜上设置有与下电极构成电容器结构的上电极。
可选地，所述振膜采用复合结构，所述上电极设置在振膜的复合结构 中。
可选地，振膜上的上电极通过引线与衬底上的电路布图导通。
可选地，所述振膜的机械灵敏度为0.02至0.9nm/Pa。
可选地，所述振膜和衬底之间的初始间隙为1-100μm。
可选地，还包括ASIC电路，所述ASIC电路集成在衬底上。
可选地，在所述振膜远离真空腔一侧的中部区域设置有补强部。
可选地，在所述衬底远离真空腔的一侧设置有用于外接的焊盘。
可选地，所述振膜与下电极之间的电场为100-300V/μm。
本发明的MEMS麦克风，由于振膜与衬底围成了真空腔，并可通过驻极体层为振膜与衬底之间提供电场。而且可以在真空腔内形成高电场而不会造成击穿的问题，大大提高了本发明MEMS麦克风的灵敏度。
本发明的MEMS麦克风，振膜与衬底之间围成了真空腔，真空腔内的空气粘度远远低于环境压力中的空气粘度，从而可以降低声阻对振膜振动的影响，提高了麦克风的信噪比。另外，由于该结构的MEMS麦克风不需要较大容积的背腔，因此可以大大降低MEMS麦克风的整体尺寸，增强了麦克风的可靠性。
通过以下参照附图对本发明的示例性实施例的详细描述，本发明的其它特征及其优点将会变得清楚。
附图说明
构成说明书的一部分的附图描述了本发明的实施例，并且连同说明书一起用于解释本发明的原理。
图1是本发明麦克风第一实施方式的结构示意图。
图2是本发明麦克风第二实施方式的结构示意图。
图3是图2实施例中麦克风的动作原理示意图。
图4是本发明麦克风其中一种封装方式的示意图。
具体实施方式
为了使本发明解决的技术问题、采用的技术方案、取得的技术效果易 于理解，下面结合具体的附图，对本发明的具体实施方式做进一步说明。
参考图1，本发明提供了一种MEMS麦克风，其包括衬底1以及通过间隔部3支撑在衬底1上方的振膜2，衬底1、间隔部3、振膜2围成了真空腔4。
本发明的衬底1可以采用单晶硅或者本领域技术人员所熟知的其它材质，并可通过逐层沉积、图案化、牺牲的工艺形成间隔部3以及通过间隔部3支撑在衬底1上的振膜2。如有必要，在间隔部3与衬底1之间还设置有绝缘层8，在此不再具体说明。
真空腔4例如可由低压等离子体增强化学气相沉积(PECVD)在200-350℃下进行密封。这种MEMS工艺属于本领域技术人员的公知常识，在此不再具体说明。其中真空腔4优选小于1kPa，这使得真空腔4中的残余气体粘度大大低于标准压力下的空气粘度。
由于振膜与衬底1之间形成了低于大气压力的真空腔，因此振膜2在大气压力下且无声压时会发生静态偏转，即振膜2会朝向衬底1的方向发生静态偏转。为了防止振膜2静态时偏转至与衬底1接触，设计该振膜的静态偏转距离要小于振膜2与衬底1之间的距离。这主要可以通过改变振膜2的刚性和/或改变振膜与衬底1之间的距离来实现。
例如可以加厚振膜2的尺寸，当然也可以通过选择合适的振膜材质来提升振膜的刚性。例如可以通过设计使得振膜2具有0.02至0.9nm/Pa的机械灵敏度。也就是说，每受1Pa的压力，振膜2则会发生0.02-0.9nm的偏转，这种振膜2的刚性是传统振膜的10-100倍，使得振膜2足够坚硬以抵抗外界的大气压力。
振膜2和衬底1之间的相应初始间隙可以设计在1-100μm的范围内，配合上述刚性的振膜2，使得在大气压力下不会发生振膜2塌陷的问题。
为了提高MEMS麦克风的灵敏度，MEMS麦克风可以采用高灵敏度的检测构件，例如驻极体式的电容检测结构。
在本发明一个具体的实施方式中，检测结构包括设置在衬底1上的下电极6，该下电极6与振膜2构成了可以输出变化电信号的电容器结构。
在本发明另一个具体的实施方式中，振膜2可以采用绝缘材质，在振 膜2上设置有上电极5，下电极6与振膜2上的上电极5构成了可以输出变化电信号的电容器结构。上电极5、下电极6可通过本领域技术人员所熟知的MEMS沉积、刻蚀工艺形成，在此对其不再具体说明。
下电极6可以设置在衬底1上位于真空腔4一侧的位置上。可选的是，设置绝缘层8将下电极6掩埋起来。上电极5可以设置在振膜2上位于真空腔4一侧的位置，或者设置在振膜2上远离真空腔4一侧的位置。
还可以是，振膜2可以采用复合结构，例如为了形成真空腔，需要首先在牺牲层上设置一层具有牺牲孔的覆盖层20，通过牺牲孔将覆盖层20下方的牺牲层腐蚀掉；之后在覆盖层20的上方沉积一层填充层21，以将覆盖层20上的牺牲孔封闭住，形成真空腔。上电极5可以设置在振膜2的复合结构中，例如形成在填充层21上，外侧再设置一层钝化层22进行保护，在此不再具体说明。
本发明的麦克风，在衬底1上设置有为振膜2/上电极5与下电极6之间提供电场的驻极体层7。该驻极体层7设置在衬底1上，且位于下电极6的上方，并通过绝缘层8覆盖。通过振膜2振动时上电极5与下电极6之间的间隔变化，使得电容器结构可以输出变化的电信号。这种电容器的工作原理属于本领域技术人员的公知常识。
在本发明一个具体的实施方式中，驻极体层7可以被配置为振膜2与下电极6提供100-300V/μm的电场，
本发明的MEMS麦克风，由于振膜2与衬底1围成了真空腔4，使得可以在真空腔4内形成高电场而不会造成击穿的问题，尤其采用刚性高的振膜2。在本发明中，上电极6与下电极5之间的电场为100-300V/μm，也就是说，在几微米的真空间隙内可达几百伏特，是传统麦克风电场的10至100倍。由此可大大提高本发明MEMS麦克风的灵敏度。
本发明的MEMS麦克风，振膜2与衬底1之间围成了真空腔，真空腔内的空气粘度远远低于环境压力中的空气粘度，从而可以降低声阻对振膜振动的影响，提高了麦克风的信噪比。另外，由于该结构的MEMS麦克风不需要较大容积的背腔，因此可以大大降低MEMS麦克风的整体尺寸，增强了麦克风的可靠性。
在本发明一个可选的实施方式中，在振膜2远离真空腔一侧的中部区域设置有补强部9，参考图2。补强部9用于强化振膜2中部区域的刚性，其可以看成是中心增厚层，材质和振膜2的材质相同，也可以不同。
参考图3，通过在振膜2的中心区域设置补强部9，使得振膜2在振动时，被补强部9补强的振膜2区域可以同步向衬底1方向发生偏转，振膜2的中心区域作类似上下平动的活塞运动，而不是传统振膜的弧形弯曲运动方式，这提高了电容器检测的变化量。
本发明的MEMS麦克风，除了采用表面微加工或者体硅微加工的工艺制造，还可以采用键合的工艺。
在制造时，例如通过表面微加工或者体硅微加工的工艺将一部分间隔部、下电极、驻极体层形成在第一衬底上，将振膜、另一部分间隔部形成在第二衬底上，然后通过键合的工艺在真空环境中将两部分间隔部键合在一起；将第二衬底完全去除后，可在振膜2上形成上电极、钝化层以及焊盘等，在此不再具体说明。
本发明的麦克风，振膜2上的上电极5可以通过引线连接到衬底1的引脚上或者电路布图中。由于振膜2与衬底1之间还有间隔部3，因此在导通的时候，引线的一端与上电极5导通，另一端在振膜2上延伸至间隔部3的位置，并穿过间隔部3连接到衬底1的电路布图中。由于下电极6设置在衬底1上，因此下电极6可以直接通过引线导通到衬底1的电路布图中，在此不再具体说明。
本发明的MEMS麦克风，由于不需要较大容积的背腔，使得可以完全采用晶圆级封装(WLP)，无需传统的PCB板封装，该麦克风可以直接安装到外部终端上。在本发明一个具体的实施方式中，参考图4，在衬底1远离真空腔4的一端形成有焊盘13，并可通过金属化通孔12将位于衬底1上方的电信号引到焊盘13上，使得MEMS麦克风可以通过焊盘13直接安装到外部终端上。
在本发明一个可选的实施方式中，衬底1上可以集成麦克风的ASIC电路，可以通过衬底1上或者衬底1内的电路布图将电容器的输出端与ASIC电路导通起来，使得电容器输出的电信号可以经过ASIC电路进行处理。也 可以在衬底1上直接设置ASIC芯片11，在此不再具体说明。
进一步可选的是，可以将振膜2的边缘与衬底1、ASIC芯片11通过塑封体10封装起来，只将振膜2悬空的区域露出。
在本发明另一个具体的实施方式中，外接的引脚可以形成在衬底的上表面(邻近振膜的一侧)，可通过凸点焊接(植锡球)的方式直接将麦克风安装到外部终端上。
当然，本发明的MEMS麦克风还可以采用传统封装的结构，例如设置由电路板以及壳体围成的封装结构，MEMS麦克风安装在封装结构内，形成传统的顶部封装结构或者顶部封装结构，最终以麦克风模组的形式再安装到外部的终端上。
本发明已通过优选的实施方式进行了详尽的说明。然而，通过对前文的研读，对各实施方式的变化和增加也是本领域的一般技术人员所显而易见的。申请人的意图是所有这些变化和增加都落在了本发明权利要求所保护的范围中。
相似的编号通篇指代相似的元件。为清晰起见，在附图中可能有将某些线、层、元件、部件或特征放大的情况。
本文中使用的术语仅为对具体的实施例加以说明，其并非意在对本发明进行限制。除非另有定义，本文中使用的所有术语(包括技术术语和科学术语)均与本发明所属领域的一般技术人员的理解相同。

Claims (10)

  1. 一种MEMS麦克风，其特征在于：包括衬底以及通过间隔部支撑在衬底上方的振膜，所述衬底、间隔部、振膜围成了真空腔；其中，振膜在大气压力下的静态偏转距离小于振膜与衬底之间的距离；
    在所述衬底上设置有与振膜构成电容器结构的下电极，在所述衬底上设置有为振膜与下电极之间提供电场的驻极体层。
  2. 根据权利要求1所述的MEMS麦克风，其特征在于：所述振膜采用绝缘材质，在所述振膜上设置有与下电极构成电容器结构的上电极。
  3. 根据权利要求1或2所述的MEMS麦克风，其特征在于：所述振膜采用复合结构，所述上电极设置在振膜的复合结构中。
  4. 根据权利要求1至3任一项所述的MEMS麦克风，其特征在于：振膜上的上电极通过引线与衬底上的电路布图导通。
  5. 根据权利要求1至4任一项所述的MEMS麦克风，其特征在于：所述振膜的机械灵敏度为0.02至0.9nm/Pa。
  6. 根据权利要求1至5任一项所述的MEMS麦克风，其特征在于：所述振膜和衬底之间的初始间隙为1-100μm。
  7. 根据权利要求1至6任一项所述的MEMS麦克风，其特征在于：还包括ASIC电路，所述ASIC电路集成在衬底上。
  8. 根据权利要求1至7任一项所述的MEMS麦克风，其特征在于：在所述振膜远离真空腔一侧的中部区域设置有补强部。
  9. 根据权利要求1至8任一项所述的MEMS麦克风，其特征在于：在所述衬底远离真空腔的一侧设置有用于外接的焊盘。
  10. 根据权利要求1至9任一项所述的MEMS麦克风，其特征在于：所述振膜与下电极之间的电场为100-300V/μm。
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