WO2022110349A1 - 一种压电式麦克风及其制作方法 - Google Patents

一种压电式麦克风及其制作方法 Download PDF

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Publication number
WO2022110349A1
WO2022110349A1 PCT/CN2020/136636 CN2020136636W WO2022110349A1 WO 2022110349 A1 WO2022110349 A1 WO 2022110349A1 CN 2020136636 W CN2020136636 W CN 2020136636W WO 2022110349 A1 WO2022110349 A1 WO 2022110349A1
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Prior art keywords
diaphragm
sub
piezoelectric
fixed
elastic
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French (fr)
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石正雨
童贝
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AAC Technologies Holdings Shenzhen Co Ltd
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AAC Acoustic Technologies Shenzhen Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
    • H04R17/02—Microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; 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 
    • H04R1/222—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only  for microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; 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; ELECTRIC HEARING AIDS; 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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; 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
    • H04R7/06—Plane diaphragms comprising a plurality of sections or layers

Definitions

  • the present application relates to a piezoelectric microphone, and in particular, to a piezoelectric microphone with a diaphragm having a large torque.
  • MEMS microphones There are many types of microphones, including moving coil, condenser, aluminum ribbon, carbon, etc.
  • ECM electret
  • MEMS microelectromechanical
  • SMT surface mount
  • the MEMS microphone In the MEMS microphone, it is divided into two types: capacitive and piezoelectric. Piezoelectric versus capacitive update.
  • the main advantage of piezoelectric technology is that it is robust and unaffected by the environment, while capacitive technology suffers from performance degradation over time: in condenser microphones, if there is particulate contamination between the diaphragm and the backplate, the performance of the microphone will be reduced. Change.
  • SNR signal-to-noise ratio
  • the width of the free end of the piezoelectric microphone cantilever beam of the existing structure is smaller than that of the fixed end, the torque generated under the action of sound pressure is low, and the signal-to-noise ratio is low, and the free end warps under the residual stress, resulting in a large gap, which affects Microphone low frequency performance.
  • the purpose of this application is to provide a piezoelectric microphone.
  • it includes a base with a back cavity and a piezoelectric cantilever diaphragm fixed on the base; the piezoelectric cantilever vibrator
  • the membrane at least includes a first sub-diaphragm and a second sub-diaphragm, one end of each sub-diaphragm is fixed with the base to form a fixed end, and the other end is suspended above the back cavity to form a movable end connected to the fixed end, and the width of the movable end is not less than Regarding the width of the fixed end
  • the piezoelectric microphone further includes an elastic elastic member, one end of the elastic elastic member is connected to the movable end of the first sub-diaphragm, and the other end is connected to the second sub-diaphragm and/or the base.
  • the back cavity is in the shape of a square
  • the elastic elastic member connecting the first sub-diaphragm and the second sub-diaphragm is located on the central axis of the square and is parallel to the fixed ends of the first and second sub-diaphragms.
  • the back cavity is in the shape of an octagon
  • the elastic expansion member connecting the first sub-diaphragm and the second sub-diaphragm is located on the central axis of the octagon, and is connected to the fixed ends of the first sub-diaphragm and the second sub-diaphragm. parallel.
  • the back cavity is hexagonal
  • the elastic expansion member connecting the first sub-diaphragm and the second sub-diaphragm is located on the central axis of the hexagon, and is connected to the fixed ends of the first sub-diaphragm and the second sub-diaphragm. parallel.
  • the back cavity is in the shape of a cross
  • the elastic expansion member connecting the first sub-diaphragm and the second sub-diaphragm is located on the central axis of the cross and is parallel to the fixed ends of the first and second sub-diaphragms.
  • the elastic elastic member is a flexible spring structure.
  • the elastic elastic member is a hollow pattern on the sub-diaphragm.
  • the hollow pattern includes a zigzag groove, a swastika groove or a rhombus groove
  • Another aspect of the present application provides a method for making a piezoelectric microphone, comprising the following steps:
  • S1 deposit a layer of piezoelectric material on the substrate, so that the piezoelectric material is fixed on the substrate material;
  • S2 Divide the first sub-diaphragm and the second sub-diaphragm on the piezoelectric material, and fix one end of each sub-diaphragm with the base to form a fixed end, and the other end to form a free movable end, and the width of the movable end is not less than the fixed end the width of the end;
  • a back cavity with a polygonal shape is etched on the substrate.
  • the elastic elastic member is a hollow pattern on the sub-diaphragm.
  • the width of the movable end of the cantilever beam in the structure of the piezoelectric microphone is not less than the width of the fixed end, and a larger torque will be generated under the action of sound pressure, thereby improving the signal-to-noise ratio of the microphone;
  • a flexible spring structure is arranged on the free moving edge of the cantilever beam, so that when the cantilever beam is warped, the spring deforms with the cantilever beam, thereby avoiding the generation of gaps and improving the low-frequency performance of the microphone.
  • FIG. 1 is a top view of a specific embodiment of the present application and an enlarged view of an elastic telescopic element
  • FIG. 2 is a top view of a plurality of specific embodiments of the present application.
  • FIG. 3 is a perspective view of a specific embodiment of the present application.
  • Fig. 4(a) is a schematic diagram of the prior art without elastic elastic members
  • Fig. 4(b) is a functional schematic diagram of the elastic elastic members in the present application and an enlarged view thereof.
  • the present application provides a piezoelectric microphone 100 , which includes a substrate 10 having a back cavity 11 , and a piezoelectric cantilever diaphragm 20 fixed above the substrate 10 .
  • the piezoelectric cantilever beam diaphragm 20 includes a pair of first sub-diaphragms 21 and second sub-diaphragms 22 arranged oppositely.
  • the pair of sub-diaphragms of the piezoelectric cantilever beam diaphragm 20 will deform under the action of external sound pressure. , and the piezoelectric effect occurs to generate electrical signal output.
  • the back cavity 11 is a cavity formed by the substrate 10 and the piezoelectric cantilever beam diaphragm 20. Due to the existence of the back cavity 11, when the same sound intensity acts on the piezoelectric cantilever beam diaphragm 20, the piezoelectric cantilever beam diaphragm 20 will vibrate. The displacement is greatly increased, and thus the increased strain produces more charge.
  • the first sub-diaphragm 21 and the second sub-diaphragm 22 have the same shape, each sub-diaphragm has at least one fixed end 211, 221 fixed on the base 10, and at least one of the sub-diaphragms is elastically connected to the other sub-diaphragm.
  • the movable ends 212 and 222 of the telescopic piece 30 are connected.
  • the elastic elastic member 30 and the fixed ends connecting the first sub-diaphragm 21 and the second sub-diaphragm 22 with the base 10 form certain constraints on the first sub-diaphragm 21 and the second sub-diaphragm 22, so that the first sub-diaphragm 21 and the second sub-diaphragm 22 are bound to a certain extent.
  • the membrane 21 and the second sub-diaphragm 22 are suspended above the back cavity 11 of the substrate 10, and make the two first sub-diaphragms 21 and the second sub-diaphragm 22 on the same plane as much as possible, so as to reduce the damage caused by the two diaphragms.
  • the signal-to-noise ratio decreases due to the deformation of the first sub-diaphragm 21 and the second sub-diaphragm 22 .
  • the lengths of the movable ends 212 and 222 of the sub-diaphragm are not less than the lengths of the fixed ends 211 and 221 .
  • the material of the substrate 10 may be a material such as silicon that can be processed by an etching process, so that the back cavity 11 can be etched on the base material of the substrate 10 .
  • the material of the piezoelectric cantilever diaphragm 20 is a ceramic material capable of generating piezoelectric effect, such as AlN, perovskite oxide and the like.
  • the material of the piezoelectric cantilever diaphragm 20 may be deposited on the base by methods such as physical vapor deposition.
  • the piezoelectric cantilever beam diaphragm 20 has only two first sub-diaphragms 21 and the fixed ends 211 and 221 of the second sub-diaphragm 22 connected to the base 10.
  • the piezoelectric cantilever beam diaphragm 20 is adjacent to the base 10 except for the fixed ends 211 and 221 of the first sub-diaphragm 21 and the second sub-diaphragm 22, The connection is also made using elastic elastic members 30 .
  • all sides of the piezoelectric cantilever diaphragm 20 are connected to the base 10, which can further improve the stability.
  • the piezoelectric cantilever beam vibrating film 20 includes at least three-layer structures, which respectively include a first electrode sheet, a piezoelectric diaphragm, and a second electrode sheet that are sequentially stacked along the vibration direction, and the first electrode sheet is provided with On the side of the piezoelectric cantilever diaphragm 20 close to the back cavity 11 . More specifically, the piezoelectric cantilever diaphragm 20 may also have a five-layer structure or a multi-layer structure.
  • the elastic elastic member 30 is a soft spring structure, which connects the base 10 and the piezoelectric cantilever beam diaphragm 20 and connects the two first sub-diaphragms 21 ,
  • the spring and the piezoelectric cantilever beam diaphragm 20 can be deformed together, thereby avoiding the generation of the gap as shown in FIG. 4(a), thereby improving the low frequency of the microphone. performance.
  • the soft spring structure as the elastic elastic member 30 is a hollow pattern etched on the first sub-diaphragm 21 and the second sub-diaphragm 22 .
  • the hollow pattern may be a zigzag groove, a swastika groove or a rhombus groove.
  • the above-mentioned hollow pattern is etched on the piezoelectric cantilever beam vibrating film 20 deposited on the base by a method such as physical vapor deposition by photolithography.
  • the required movable ends 212 , 222 and the part where the piezoelectric cantilever beam diaphragm 20 is connected to the base 10 can be directly etched on a whole piece of the deposited piezoelectric cantilever beam diaphragm 20 . .
  • the present application also provides a method for making a piezoelectric microphone, comprising the following steps:
  • S1 deposit a layer of piezoelectric material on the substrate, so that the piezoelectric material is fixed on the substrate material;
  • S2 Divide the first sub-diaphragm 21 and the second sub-diaphragm 22 on the piezoelectric material, and fix one end of each sub-diaphragm with the base 10 to form a fixed end, and the other end to form a free movable end.
  • the width of the end is not less than the width of the fixed end.
  • the sides where the first sub-diaphragm 21 and the second sub-diaphragm 22 are connected to each other are set as the movable ends 212 and 222, which are connected with each other.
  • the movable ends 212 and 222 are parallel and fixed on the base 10 as fixed ends.
  • the shape of the back cavity 11 determines the shape of the piezoelectric cantilever beam diaphragm 20 covering the substrate 10 . Therefore, it is necessary to ensure that the length of the movable ends 212 and 222 of the sub-diaphragms 21 and 22 is not less than the length of the fixed ends 211 and 221 .
  • the elastic stretchable member is a hollow pattern on the piezoelectric cantilever beam diaphragm.
  • a piezoelectric cantilever beam diaphragm 20 formed by a pair of first sub-diaphragms 21 and second sub-diaphragms 22 having the same shape is fixed and suspended on the substrate 10 with The octagonal shape is above the back cavity 11 to receive the external sound pressure and convert it into an electrical signal.
  • the movable ends 212 and 222 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are connected to each other along the central axis of the octagon of the back cavity 11 through the elastic elastic member 30, so that the first sub-diaphragm 21,
  • the second sub-diaphragm 22 is connected to form the piezoelectric cantilever beam diaphragm 20, and the fixed ends 211 and 221 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are located on two opposite sides of the eight sides parallel to the central axis. on each side, and is fixedly connected with the base 10.
  • the lengths of the movable ends 212 and 222 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are greater than the lengths of the fixed ends 211 and 221, which makes the piezoelectric cantilever beam diaphragm 20 play a role in the sound pressure. There is a larger torque under the lower, which can improve the signal-to-noise ratio.
  • a piezoelectric cantilever beam vibrating membrane 20 formed by a pair of the first sub-diaphragm 21 and the second sub-diaphragm 22 having the same shape is fixed and suspended on the substrate 10 having the same shape.
  • the movable ends 212 and 222 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are connected to each other along the central axis of the hexagon by the elastic elastic member 30 , so that the first sub-diaphragm 21 and the second sub-diaphragm 22 are connected to each other along the central axis of the hexagon.
  • the diaphragms 22 are connected to form the piezoelectric cantilever beam diaphragm 20, and the fixed ends 211 and 221 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are located on two sides of the six sides that are parallel to and opposite to the central axis, and fixedly connected with the base 10 .
  • the lengths of the movable ends 212 and 222 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are not less than the lengths of the fixed ends 211 and 221 , which makes the piezoelectric cantilever beam diaphragm 20 operate under the sound pressure. There is a larger moment under the action, which can improve the signal-to-noise ratio.
  • a piezoelectric cantilever beam vibrating membrane 20 formed by a pair of the first sub-diaphragm 21 and the second sub-diaphragm 22 having the same shape is fixed and suspended on the substrate 10 having the same shape.
  • Above the back cavity 11 in the shape of a cross to receive the external sound pressure and convert it into an electrical signal.
  • the movable ends 212 and 222 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are connected to each other along the central axis of the cross through the elastic elastic member 30 , so that the first sub-diaphragm 21 and the second sub-diaphragm 22 are connected to each other by the elastic expansion member 30 .
  • 22 is connected to form a piezoelectric cantilever beam diaphragm 20, and the fixed ends 211 and 221 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are located on two sides parallel to and opposite to the central axis of the cross, and are connected to the base. 10 are fixedly connected.
  • the lengths of the movable ends 212 and 222 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are not less than the lengths of the fixed ends 211 and 221, which makes the piezoelectric cantilever beam diaphragm 20 in the sound Under the action of pressure, there is a larger moment, which can improve the signal-to-noise ratio.
  • a piezoelectric cantilever beam vibrating membrane 20 formed by a pair of the first sub-diaphragm 21 and the second sub-diaphragm 22 having the same shape is fixed and suspended on the substrate 10 having the same shape.
  • the movable ends 212 and 222 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are connected to each other along the central axis of the square by the elastic expansion member 30 , so that the first sub-diaphragm 21 and the second sub-diaphragm 22
  • the piezoelectric cantilever beam diaphragm 20 is formed by connection, and the fixed ends 211 and 221 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are located on the two sides parallel to and opposite to the central axis of the square, and are fixed to the base 10 connected.
  • the part of the piezoelectric cantilever beam diaphragm 20 adjacent to the base 10 except the fixed ends 211 and 221 of the first sub-diaphragm 21 and the second sub-diaphragm 22 also uses an elastic elastic member 30 to connect.
  • the lengths of the movable ends 212 and 222 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are greater than the lengths of the fixed ends 211 and 221, which makes the piezoelectric cantilever beam diaphragm 20 play a role in the sound pressure. There is a larger torque under the lower, which can improve the signal-to-noise ratio.
  • the terms “comprising”, “comprising” or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device comprising a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus.
  • an element qualified by the phrase “comprising a" does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Manufacturing & Machinery (AREA)
  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Multimedia (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)

Abstract

本申请提供了一种压电式麦克风，包括具有背腔的基底，以及固定在所述基底上方的压电悬臂梁振膜；压电悬臂梁振膜至少包括第一子振膜和第二子振膜，每一子振膜一端与基底固定形成固定端，另一端悬置于背腔上方形成与固定端连接的活动端，活动端的宽度不小于固定端的宽度，压电式麦克风还包括弹性伸缩件，弹性伸缩件一端连接着第一子振膜的活动端，另一端连接着第二子振膜和/或基底上。本申请的悬臂梁活动端的宽度不小于固定端的宽度，在声压作用下将产生更大力矩，从而提高麦克风信噪比。

Description

一种压电式麦克风及其制作方法 技术领域
本申请涉及一种压电式麦克风，尤其涉及一种振膜具有较大力矩的压电式麦克风。
 背景技术
麦克风种类繁多，包括动圈式、电容式、铝带式、碳精式等等，在移动应用中，又以又以驻极体（ECM）电容麦克风和微机电（MEMS）麦克风最为常见。微机电麦克风外形较小，与驻极体麦克风相比，具有更强的耐热、抗振和抗射频干扰性能。此外，微机电麦克风可以采用全自动贴片（SMT）生产工艺，而大多数驻极体麦克风则需要手工焊接。
在微机电麦克风中，又分为电容式和压电式两种。压电式比电容式更新。压电技术的主要优势是坚固耐用，不受环境影响，而电容技术存在性能随时间下降的问题：在电容式麦克风中，如果在振膜和背板之间有颗粒物污染，麦克风的性能将会改变。压电麦克风的另一个优势是信噪比（SNR）更高，目前根据已知的方法，可以获得超过75dB的信噪比，理论上甚至可以超过80dB。
 技术问题
但是现有结构压电麦克悬臂梁自由端的宽度小于固定端，声压作用下产生力矩较低，具有较低的信噪比，并且在残余应力下自由端翘曲，产生较大的缝隙，影响麦克风低频性能。
 技术解决方案
在本申请的目的在于提供一种压电式麦克风，在本申请一个方面的技术方案中，包括具有背腔的基底以及固定在所述基底上方的压电悬臂梁振膜；压电悬臂梁振膜至少包括第一子振膜和第二子振膜，每一子振膜一端与基底固定形成固定端，另一端悬置于背腔上方形成与固定端连接的活动端，活动端的宽度不小于固定端的宽度，压电式麦克风还包括弹性伸缩件，弹性伸缩件一端连接着第一子振膜的活动端，另一端连接着第二子振膜和/或基底上。
优选的，背腔呈正方形，连接第一子振膜和第二子振膜的弹性伸缩件位于正方形的中轴线，并且与第一子振膜和第二子振膜的固定端平行。
优选的，背腔呈八边形，连接第一子振膜和第二子振膜的弹性伸缩件位于八边形的中轴线，并且与第一子振膜和第二子振膜的固定端平行。
优选的，背腔呈六边形，连接第一子振膜和第二子振膜的弹性伸缩件位于六边形的中轴线，并且与第一子振膜和第二子振膜的固定端平行。
优选的，背腔呈十字形，连接第一子振膜和第二子振膜的弹性伸缩件位于十字形的中轴线，并且与第一子振膜和第二子振膜的固定端平行。
优选的，弹性伸缩件是柔性弹簧结构。
优选的，弹性伸缩件是子振膜上的镂空图样。
优选的，镂空图样包括回字形沟槽、万字纹形沟槽或者是菱花纹形沟槽
本申请的另一个方面，提供了一种制作压电式麦克风的方法，包括以下步骤：
S1：在基底上沉积一层压电材料，使压电材料固定在基底材料上；
S2：在压电材料上分割出第一子振膜和第二子振膜，并使每一子振膜一端与基底固定形成固定端，另一端形成自由的活动端，活动端的宽度不小于固定端的宽度；
S3：生成弹性伸缩件，弹性伸缩件一端连接着第一子振膜的活动端，另一端连接着第二子振膜和/或基底上；
S4：在基底上蚀刻出具有多边形形状的背腔。优选的，在所述步骤S3中，弹性伸缩件是子振膜上的镂空图样。
 有益效果
本申请技术方案所能取得的有益技术效果包括：压电式麦克风的结构中悬臂梁活动端的宽度不小于固定端的宽度，在声压作用下将产生更大力矩，从而提高麦克风信噪比；在悬臂梁自由运动边缘设置柔性弹簧结构，可以使得在悬臂梁发生翘曲时，弹簧跟随悬臂梁一起形变，从而避免了产生缝隙,从而提高麦克风的低频性能。
 附图说明
为了更清楚地说明本申请实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本申请一个具体实施例的俯视图以及弹性伸缩件的放大图；
图2是本申请的多个具体实施例的俯视图；
图3是本申请一个具体实施例的立体图；
图4(a)是不含弹性伸缩件的现有技术的示意图;图4(b)本申请中弹性伸缩件的功能示意图及其放大图。
 本发明的实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。需要说明的是，当元件被称为“固定于”另一个元件，它可以直接在另一个元件上或者也可以存在居中的元件。当一个元件被认为是“连接”另一个元件，它可以是直接连接到另一个元件或者可能同时存在居中元件。本文所使用的术语“垂直的”、“水平的”、“左”、“右”以及类似的表述只是为了说明的目的。
参考图1、图3，本申请提供了一种压电式麦克风100，其包括具有背腔11的基底10，以及固定在基底10上方的压电悬臂梁振膜20。压电悬臂梁振膜20包括一对相对布置的第一子振膜21、第二子振膜22，压电悬臂梁振膜20的一对子振膜在外界的声压作用下会发生形变，并发生压电效应产生电信号输出。背腔11是基底10与压电悬臂梁振膜20形成的空腔，由于背腔11的存在，当同等声强作用于压电悬臂梁振膜20时，压电悬臂梁振膜20的振动位移大大提高，从而应变程度增强产生更多的电荷。第一子振膜21、第二子振膜22具有相同的形状，每一片子振膜具有至少一个固定在基座10上的固定端211、221，以及至少一个与另一片子振膜通过弹性伸缩件30连接的活动端212、222。上述弹性伸缩件30以及第一子振膜21、第二子振膜22与基底10连接的固定端对第一子振膜21、第二子振膜22形成一定的约束，使得第一子振膜21、第二子振膜22悬垂在基底10的背腔11上方，并使得两片第一子振膜21、第二子振膜22尽可能地处于同一平面上，以减小由于两片第一子振膜21、第二子振膜22本身的形变而造成的信噪比下降。此外，为了进一步提高信噪比，子振膜的活动端212、222的长度不小于固定端211、221的长度。
基底10的材料可以是硅材料等可以使用蚀刻工艺进行加工的材料，以能够在基底10的基材上蚀刻出背腔11。压电悬臂梁振膜20的材料是能够产生压电效应的陶瓷材料，如AlN、钙钛矿型氧化物等。压电悬臂梁振膜20的材料可以通过物理气相沉积等的方法沉积在基座上。
此时，压电悬臂梁振膜20仅有两片第一子振膜21、第二子振膜22的固定端211、221与基座10相连接，为了进一步提高压电悬臂梁振膜20的稳定性，在一个优选的实施例中，压电悬臂梁振膜20除了第一子振膜21、第二子振膜22的固定端211、221之外的与基座10邻接的部分，也使用弹性伸缩件30进行连接。在这个优选实施例中，压电悬臂梁振膜20的所有边都与基座10连接，能够进一步提高稳定性。
在一个实施例中，压电悬臂梁振膜20包括至少三层结构，分别包括沿振动方向包括依次层叠的第一电极片、压电膜片和第二电极片，所述第一电极片设置于所述压电悬臂梁振膜20靠近所述背腔11的一侧。更具体的，压电悬臂梁振膜20还可以是五层结构或多层结构。
在一个具体的实施例中，由图4(b)可知，弹性伸缩件30是柔软弹簧结构，其在连接基座10与压电悬臂梁振膜20以及连接两片第一子振膜21、第二子振膜22时，可以使得在悬臂梁发生翘曲时，弹簧跟压电悬臂梁振膜20一起形变，从而避免了产生如图4(a)所示的缝隙,从而提高麦克风的低频性能。
在一个具体的实施例中，由图1中的放大部分可知，作为弹性伸缩件30的柔软弹簧结构在第一子振膜21、第二子振膜22上蚀刻而成的镂空图样。具体地，镂空图样可以是回字形沟槽、万字纹形沟槽或者是菱花纹形沟槽。具体的，是通过光刻法在通过物理气相沉积等的方法沉积在基座上的压电悬臂梁振膜20上蚀刻出上述镂空图样。
在一种变化的实施例中，可以在一整片沉积好的压电悬臂梁振膜20上直接蚀刻出所需要的活动端212、222以及压电悬臂梁振膜20与基座10连接的部分。
本申请还提供了一种制作压电式麦克风的方法，包括以下步骤：
S1：在基底上沉积一层压电材料，使压电材料固定在基底材料上；
S2：在所述压电材料上分割出第一子振膜21和第二子振膜22，并使每一子振膜一端与基底10固定形成固定端，另一端形成自由的活动端，活动端的宽度不小于固定端的宽度。
在第一子振膜21、第二子振膜22上，通过柔性弹簧结构30使得所述第一子振膜21、第二子振膜22互相连接的边设为活动端212、222，与活动端212、222平行并固定在基底10上的边设为固定端。
S3：生成弹性伸缩件30，弹性伸缩件30一端连接着第一子振膜21的活动端212，另一端连接着第二子振膜22和/或基底10上。
S4：在基底材料上蚀刻出具有多边形形状的背腔11。
背腔11的形状决定了覆盖在基底10上的压电悬臂梁振膜20的形状，因此需要确保子振膜21、22的活动端212、222的长度不小于固定端211、221的长度。
在一个可选的实施例中，在步骤S3中，所述弹性伸缩件是所述压电悬臂梁振膜上的镂空图样。
下面结合图2列举具有不同背腔11形状的压电式麦克风100的各个不同的实施例，需要注意的是，下述具体实施例仅是为了具体地说明本申请的压电式麦克风100的结构，并不对本申请构成任何限定。
实施例1
参考图2（a），在一个具体的实施例中，一对具有相同形状的第一子振膜21、第二子振膜22形成的压电悬臂梁振膜20固定悬垂在基底10的具有八边形的形状的背腔11上方，以接收外部的声压，并将其转化为电信号。具体地，第一子振膜21、第二子振膜22的活动端212、222沿着背腔11的八边形的中轴线通过弹性伸缩件30互相连接，使得第一子振膜21、第二子振膜22连接形成压电悬臂梁振膜20，并且，第一子振膜21、第二子振膜22的固定端211、221位于八个边中与中轴线平行并且相对的两个边上，并与基底10固定相连。在本实施例中，第一子振膜21、第二子振膜22的活动端212、222的长度大于固定端211、221的长度，这使得压电悬臂梁振膜20在声压的作用下有较大的力矩，能够提高信噪比。
实施例2
参考图2（b），在一个具体的实施例中，一对具有相同形状的第一子振膜21、第二子振膜22形成的压电悬臂梁振膜20固定悬垂在基底10的具有六边形的形状的背腔11上方，以接收外部的声压，并将其转化为电信号。具体地，第一子振膜21、第二子振膜22的活动端212、222沿着六边形的中轴线通过弹性伸缩件30互相连接，使得第一子振膜21、第二子振膜22连接形成压电悬臂梁振膜20，并且，第一子振膜21、第二子振膜22的固定端211、221位于六个边中与中轴线平行并且相对的两个边上，并与基底10固定相连。在本实施例中，第一子振膜21、第二子振膜22的活动端212、222的长度不小于固定端211、221的长度，这使得压电悬臂梁振膜20在声压的作用下有较大的力矩，能够提高信噪比。
实施例3
参考图2（c），在一个具体的实施例中，一对具有相同形状的第一子振膜21、第二子振膜22形成的压电悬臂梁振膜20固定悬垂在基底10的具有十字型的形状的背腔11上方，以接收外部的声压，并将其转化为电信号。具体地，第一子振膜21、第二子振膜22的活动端212、222沿着十字型的中轴线通过弹性伸缩件30互相连接，使得第一子振膜21、第二子振膜22连接形成压电悬臂梁振膜20，并且，第一子振膜21、第二子振膜22的固定端211、221位于与十字型中轴线平行并且相对的两个边上，并与基底10固定相连。可见，在本实施例中，第一子振膜21、第二子振膜22的活动端212、222的长度不小于固定端211、221的长度，这使得压电悬臂梁振膜20在声压的作用下有较大的力矩，能够提高信噪比。
实施例4
参考图2（d），在一个具体的实施例中，一对具有相同形状的第一子振膜21、第二子振膜22形成的压电悬臂梁振膜20固定悬垂在基底10的具有正方形的形状的背腔11上方，以接收外部的声压，并将其转化为电信号。具体地，第一子振膜21、第二子振膜22的活动端212、222沿着正方形的中轴线通过弹性伸缩件30互相连接，使得第一子振膜21、第二子振膜22连接形成压电悬臂梁振膜20，并且，第一子振膜21、第二子振膜22的固定端211、221位于与正方形中轴线平行并且相对的两个边上，并与基底10固定相连。
在这个实施例中，压电悬臂梁振膜20除了第一子振膜21、第二子振膜22的固定端211、221之外的与基座10邻接的部分，也使用弹性伸缩件30进行连接。
在本实施例中，第一子振膜21、第二子振膜22的活动端212、222的长度大于固定端211、221的长度，这使得压电悬臂梁振膜20在声压的作用下有较大的力矩，能够提高信噪比。
以上实施例的各技术特征可以进行任意的组合，为使描述简介，未对上述实施例中的各个技术特征所以可能的组合都进行描述，然而，只要这些技术特征的组合不存在矛盾，可应当认为是本说明书记载的范围。最后，还需要说明的是，在本文中，诸如第一和第二等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括所述要素的过程、方法、物品或者设备中还存在另外的相同要素。
以上实施例仅表达了本申请的几种实施方式，其描述较为具体和详细，但并不能因此而理解为对本申请专利范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本申请构思的前提下，还可以做出若干变形和改进，这些都属于本申请的保护范围。因此，本申请的保护范围应以所附权利要求为准。

Claims (10)

1. 一种压电式麦克风，其包括具有背腔的基底以及固定在所述基底上方的压电悬臂梁振膜；所述压电悬臂梁振膜至少包括第一子振膜和第二子振膜，每一所述子振膜一端与所述基底固定形成固定端，另一端悬置于所述背腔上方形成与固定端连接的活动端，其特征在于，所述活动端的宽度不小于固定端的宽度，所述压电式麦克风还包括弹性伸缩件，所述弹性伸缩件一端连接着所述第一子振膜的活动端，另一端连接着第二子振膜和/或基底上。
2. 根据权利要求1所述的压电式麦克风，其特征在于：
所述背腔呈正方形，连接所述第一子振膜和所述第二子振膜的所述弹性伸缩件位于所述正方形的中轴线，并且与所述第一子振膜和所述第二子振膜的固定端平行。
3. 根据权利要求1所述的压电式麦克风，其特征在于：
所述背腔呈八边形，连接所述第一子振膜和所述第二子振膜的所述弹性伸缩端位于所述八边形的中轴线，并且与所述第一子振膜和所述第二子振膜的固定端平行。
4. 根据权利要求1所述的压电式麦克风，其特征在于：
所述背腔呈六边形，连接所述第一子振膜和所述第二子振膜的所述弹性伸缩端位于所述六边形的中轴线，并且与所述第一子振膜和所述第二子振膜的固定端平行。
5.根据权利要求1所述的压电式麦克风，其特征在于：
所述背腔呈十字形，连接所述第一子振膜和所述第二子振膜的所述弹性伸缩端位于所述十字形的中轴线，并且与所述第一子振膜和所述第二子振膜的固定端平行。
6. 根据权利要求1至5中任一项所述的压电式麦克风，其特征在于：所述弹性伸缩件是柔性弹簧结构。
7. 根据权利要求1至5中任一项所述的压电式麦克风，其特征在于：所述弹性伸缩件是所述压电悬臂梁振膜上的镂空图样。
8. 根据权利要求7所述的压电式麦克风，其特征在于：所述镂空图样包括回字形沟槽、万字纹形沟槽或者是菱花纹形沟槽。
9.一种制作压电式麦克风的方法，其特征在于：
包括以下步骤：
S1：在基底上沉积一层压电材料，使所述压电材料固定在所述基底材料上；
S2：在所述压电材料上分割出第一子振膜和第二子振膜，并使每一所述子振膜一端与所述基底固定形成固定端，另一端形成自由的活动端，所述活动端的宽度不小于固定端的宽度；
S3：生成弹性伸缩件，所述弹性伸缩件一端连接着所述第一子振膜的活动端，另一端连接着第二子振膜和/或基底上；
S4：在所述基底上蚀刻出具有多边形形状的背腔。
10. 根据权利要求9所述的制作方法，其特征在于：
在所述步骤S3中，所述弹性伸缩件是所述压电悬臂梁振膜上的镂空图样。
 
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