WO2021248512A1 - 一种压电式mems麦克风 - Google Patents

一种压电式mems麦克风 Download PDF

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Publication number
WO2021248512A1
WO2021248512A1 PCT/CN2020/096294 CN2020096294W WO2021248512A1 WO 2021248512 A1 WO2021248512 A1 WO 2021248512A1 CN 2020096294 W CN2020096294 W CN 2020096294W WO 2021248512 A1 WO2021248512 A1 WO 2021248512A1
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WIPO (PCT)
Prior art keywords
piezoelectric
electrode layer
scribe groove
diaphragm
groove
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PCT/CN2020/096294
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English (en)
French (fr)
Inventor
段炼
张睿
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瑞声声学科技(深圳)有限公司
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Publication of WO2021248512A1 publication Critical patent/WO2021248512A1/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
    • H04R19/00—Electrostatic transducers
    • 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

Definitions

  • the utility model relates to the technical field of electro-acoustic conversion, in particular to a piezoelectric MEMS microphone.
  • Piezoelectric MEMS microphones have many advantages over traditional capacitive MEMS microphones, including dust and water resistance, and higher maximum output sound pressure (AOP). Limited by the existing sputtering process of piezoelectric materials, piezoelectric films generally have stress, and the stress distribution is uneven, which is difficult to control. The existence of this residual stress leads to the inevitable warpage and deformation of the diaphragm.
  • the prior art piezoelectric MEMS microphone usually breaks the entire piezoelectric diaphragm along a specific direction to form several single-ended fixed cantilever beam structures.
  • the design of the cantilever beam can improve the residual stress to a certain extent.
  • This breaking of the piezoelectric diaphragm into a cantilever beam structure will reduce the signal-to-noise ratio of the microphone and affect the acoustic performance of the piezoelectric microphone.
  • the purpose of the present invention is to provide a piezoelectric MEMS microphone, which can solve the problem that the cantilever beam structure in the prior art reduces the signal-to-noise ratio of the microphone.
  • the technical solution of the utility model provides a piezoelectric MEMS microphone, including: a base with a back cavity and a piezoelectric vibrating membrane fixed on the base and suspended in the back cavity, the piezoelectric vibrating membrane It includes a first electrode layer, a piezoelectric material layer, and a second electrode layer that are sequentially stacked in a thickness direction.
  • the first electrode layer is provided with a first scribe groove along the thickness direction, and the second electrode layer is along the thickness direction.
  • a second scribe groove is formed, the first scribe groove and the second scribe groove are separated by the piezoelectric material layer and are not connected to each other, and the first scribe groove penetrates the first electrode layer ,
  • the second scribe groove is in communication with the back cavity.
  • the first scribe groove and/or the second scribe groove are arranged symmetrically along the axial direction of the piezoelectric diaphragm.
  • the first scribe groove and/or the second scribe groove include a radial groove extending from the center of the piezoelectric diaphragm toward the edge of the piezoelectric diaphragm.
  • the first scribe groove and/or the second scribe groove include a circumferential groove extending along the circumferential direction of the piezoelectric diaphragm.
  • At least two of the circumferential grooves are arc-shaped, are spaced apart from each other, and are enclosed in a ring shape.
  • At least two of the radial grooves are spaced apart from each other and are collinear.
  • the piezoelectric diaphragm includes a vibrating part directly facing the back cavity and an edge fixing part extending from the periphery of the vibrating part and fixed to the base; the first scribe groove and the The second scribe groove is opened in the vibrating part.
  • the base includes a wall surrounding the back cavity and a support portion fixed in the back cavity, the support portion is connected to and supports the piezoelectric diaphragm, the piezoelectric diaphragm It comprises an anchoring part fixedly supported by the piezoelectric vibrating membrane and a cantilever beam extending from the edge of the anchoring part, and the cantilever beam is suspended in the back cavity.
  • the orthographic projection of the support portion on the piezoelectric diaphragm does not fall into the first scribe groove and the second scribe groove.
  • the piezoelectric MEMS microphone provided by the utility model includes a base with a back cavity and a piezoelectric vibrating membrane fixed on the base and suspended in the back cavity.
  • the piezoelectric vibrating membrane includes the edge A first electrode layer, a piezoelectric material layer, and a second electrode layer are sequentially stacked in the thickness direction, the first electrode layer is provided with a first scribe groove along the thickness direction, and the second electrode layer is provided with a second scribe groove along the thickness direction
  • the first scribe groove and the second scribe groove are separated by a piezoelectric material layer and are not connected to each other, the first scribe groove penetrates the first electrode layer, and the second scribe groove communicates with the back cavity.
  • a first scribe groove is opened on the first electrode layer of the piezoelectric diaphragm
  • a second scribe groove is opened on the second electrode layer of the piezoelectric diaphragm, which can reduce the residual stress on the piezoelectric diaphragm and cause the piezoelectric vibration
  • the membrane is warped, while maintaining the structural integrity of the piezoelectric diaphragm, effectively avoiding the loss of signal-to-noise ratio, and ensuring the performance of the piezoelectric MEMS microphone.
  • Figure 1 is a perspective view of a piezoelectric MEMS microphone provided by an embodiment of the utility model
  • FIG. 2 is a schematic cross-sectional structure diagram of the piezoelectric MEMS microphone provided by the embodiment of FIG. 1 along the line A-A;
  • FIG. 3 is a schematic cross-sectional view of the piezoelectric diaphragm of the piezoelectric MEMS microphone shown in FIG. 1 along the line A'-A';
  • FIG. 4 is a schematic structural diagram of a piezoelectric MEMS microphone with circumferential grooves according to another embodiment of the present invention.
  • FIG. 5 is a schematic structural diagram of a piezoelectric MEMS microphone with circumferential grooves and radial grooves according to another embodiment of the present invention.
  • Fig. 6 is a perspective view of a piezoelectric MEMS microphone provided by another embodiment of the present invention.
  • FIG. 7 is a schematic cross-sectional structure diagram of the piezoelectric MEMS microphone provided by the embodiment of FIG. 6 along the line B-B;
  • FIG. 8 is a schematic structural diagram of a piezoelectric MEMS microphone with circumferential grooves and radial grooves according to another embodiment of the present invention.
  • the technical solution of the present invention provides a piezoelectric MEMS microphone
  • the piezoelectric MEMS microphone includes: a base 10 with a back cavity 12 and a piezoelectric diaphragm 20 fixed to the base 10 and suspended in the back cavity 12, the piezoelectric diaphragm 20 includes the edge
  • the first electrode layer 21, the piezoelectric material layer 22, and the second electrode layer 23 are sequentially stacked in the thickness direction.
  • the first electrode layer 21 is provided with a first scribe groove 211 along the thickness direction
  • the second electrode layer 23 is provided along the thickness direction.
  • the second scribe groove 231, the first scribe groove 211 and the second scribe groove 231 are separated by the piezoelectric material layer 22 and are not connected to each other, the first scribe groove 211 penetrates the first electrode layer 21, and the second scribe groove 231 is connected to the back The cavity 12 is in communication.
  • the microphone disclosed by the utility model is a piezoelectric MEMS microphone. Compared with the traditional condenser microphone, it has the advantages of dustproof, waterproof and higher maximum output sound pressure.
  • the piezoelectric microphone is installed through the piezoelectric diaphragm 20. Under the action of sound pressure, it vibrates up and down, and the piezoelectric material layer 22 in the piezoelectric diaphragm 20 generates electric charges, and the generated electric charges are collected by effective electrodes and converted into voltage signals to be transmitted to related circuits; however, piezoelectric
  • the piezoelectric diaphragm 20 of the microphone adopts the sputtering deposition process of the piezoelectric material layer 22.
  • the piezoelectric MEMS microphone includes: a base 10 with a back cavity 12 and a piezoelectric diaphragm 20.
  • the piezoelectric diaphragm 20 is fixed and suspended above the back cavity 12 to achieve the effect of sound pressure.
  • the piezoelectric diaphragm 20 is fixed to the supporting portion 13 in the back cavity 12 of the base 10 or the surrounding wall 11 of the base 10 surrounding the back cavity 12.
  • the piezoelectric diaphragm 20 is a diaphragm obtained by processing an electrode layer and a piezoelectric material layer 22.
  • the structure is divided (from top to bottom) and includes: a first electrode layer 21, a piezoelectric material layer 22, The second electrode layer 23, wherein the second electrode layer 23 is fixedly connected to the part of the base 10, and further, a first scribe groove 211 penetrating the thickness of the first electrode layer 21 is opened in the thickness direction of the first electrode layer 21, And in the thickness direction of the second electrode layer 23, a second scribe groove 231 penetrating the thickness of the second electrode layer 23 is opened.
  • the first scribe groove 211 and the second scribe groove 231 are separated by the piezoelectric material layer 22, so that the first scribe There is no penetration between the groove 211 and the second scribe groove 231.
  • a part of the second electrode layer 23 is fixedly connected to the base 10, so the second scribe groove 231 is in communication with the back cavity 12.
  • a first scribe groove 211 is opened in the first electrode layer 21, and a second scribe groove 231 is opened in the second electrode layer 23, which can reduce the influence of residual stress and reduce the diaphragm Warping occurs, and at the same time, because the first electrode layer 21 and the second electrode layer 23 maintain partial integrity, the piezoelectric MEMS microphone passes through the wall 11 of the base 10 surrounding the back cavity 12 or the support in the back cavity 12
  • the portion 13 collects the charge of the piezoelectric diaphragm 20 to achieve the greatest collection of signals generated by the piezoelectric effect, which can ensure a better signal-to-noise ratio and improve the acoustic performance of the microphone, such as low-frequency attenuation, sensitivity, and resonance peaks.
  • the first scribe groove 211 and/or the second scribe groove 231 are symmetrically arranged along the axial direction of the piezoelectric diaphragm 20. Specifically, when the first scribe grooves 211 are opened on the first electrode layer 21, a plurality of scribe grooves may be opened, and these scribe grooves are symmetrical along the axial direction of the piezoelectric diaphragm 20 (which can be understood as the first electrode layer 21).
  • the second scribe groove 231 when the second scribe groove 231 is opened on the second electrode layer 23, multiple scribe grooves can be opened, and the multiple scribe grooves on the second electrode layer 23 are along the piezoelectric diaphragm 20 (which can be understood as the first The two electrode layers 23) are arranged symmetrically in the axial direction; by defining the position structure of the grooves on the first electrode layer 21 and the second electrode layer 23, the grooves can be opened in the first electrode layer 21 and the second electrode layer. On the second electrode layer 23, the effect of residual stress on the deformation and warpage of the piezoelectric diaphragm 20 is minimized.
  • the sputtering process parameters for forming the piezoelectric diaphragm 20 or diaphragm are changed or adjusted, the direction and size of the residual stress distribution in the diaphragm will be different.
  • the position, angle, and size of the first scribe groove 211 and/or the second scribe groove 231 can be optimized according to actual conditions.
  • the first scribe groove 211 and/or the second scribe groove 231 include a radial groove 2111 extending from the center of the piezoelectric diaphragm 20 toward the edge of the piezoelectric diaphragm 20.
  • the first scribe groove 211 includes a radial groove 2111.
  • the radial groove 2111 is a scribe groove opened from the center of the first electrode layer 21 of the piezoelectric diaphragm 20 toward the edge of the first electrode layer 21.
  • the electro-diaphragm 20 is a circular diaphragm, and the position of the radial groove 2111 can be a part of any diameter direction passing through the center of the first electrode layer 21; in the same way, the second scribe groove 231 also includes the radial groove 2111
  • the radial groove 2111 is a scribe groove opened from the center of the second electrode layer 23 of the piezoelectric diaphragm 20 toward the edge of the second electrode layer 23.
  • the positions of the first scribe groove 211 and the second scribe groove 231 on the piezoelectric diaphragm 20 are limited, specifically the positions in the radial direction of the first electrode layer 21 and the second electrode layer 23, respectively, to prevent The residual stress causes deformation and warping in the radial direction of the piezoelectric diaphragm 20.
  • the first scribe groove 211 and/or the second scribe groove 231 include a circumferential groove 2112 extending along the circumferential direction of the piezoelectric diaphragm 20.
  • the first scribe groove 211 includes a circumferential groove 2112, which is a scribe groove opened along the axial direction of the first electrode layer 21 of the piezoelectric diaphragm 20, and the position of the scribe groove may be the first Any part of an electrode layer 21 in any axial direction;
  • the second scribe groove 231 includes a circumferential groove 2112, which extends from the center of the second electrode layer 23 of the piezoelectric diaphragm 20 toward the second electrode
  • the positions of the first scribe groove 211 and the second scribe groove 231 on the piezoelectric diaphragm 20 are limited by this embodiment, specifically the first electrode layer 21 and the second electrode
  • the position of the layer 23 in the axial direction is to prevent residual stress from causing deformation and warping in the
  • the first scribe groove 211 and/or the second scribe groove 231 includes a radial groove 2111 and a circumferential groove 2112, the radial groove 2111 and the circumferential groove 2112 are spaced apart Set at the middle position of the piezoelectric diaphragm 20. Due to differences in the direction and size of the residual stress distribution in the diaphragm, a radial groove 2111 and a circumferential groove 2112 are opened in the middle of the first electrode layer 21 and the second electrode layer 23 of the piezoelectric diaphragm 20 to maximize the reduction. The effect of residual stress on the deformation and warpage of the piezoelectric diaphragm 20.
  • the first scribe groove 211 may include a plurality of circumferential grooves 2112, for example, the first scribe groove includes four circumferential grooves 2112.
  • the first scribe groove 211 of this embodiment includes at least two circumferential grooves 2112, and the two circumferential grooves 2112 are arc-shaped opened on the first electrode layer 21, and the two circumferential grooves 2112 are spaced apart from each other.
  • the second scoring groove 231 may also include two circumferential grooves 2112, and the two circumferential grooves 2112 are arc-shaped and spaced apart from each other to form a ring shape and open in the second electrode layer 23.
  • At least two radial grooves 2111 are spaced apart from each other and are collinear.
  • the first scribe groove 211 is formed on the first electrode layer 21 of the piezoelectric diaphragm 20
  • the first scribe groove is a radial groove 2111.
  • it can be directed toward the piezoelectric vibration along the center of the piezoelectric diaphragm 20
  • Two radial grooves 2111 are spaced apart in the same radial direction of the edge direction of the membrane 20. It can be understood that the positions of the two radial grooves 2111 are collinear and located at any diameter passing through the center of the first electrode layer 21, as shown in FIG.
  • the radial grooves include 21111 and 21112; in the same way, two radial grooves 2111 are spaced apart from the center of the second electrode layer 23 toward the edge of the piezoelectric diaphragm 20.
  • the position 2111 is collinear at any diameter passing through the center of the second electrode layer 23.
  • the piezoelectric diaphragm 20 includes a vibrating portion 20' directly opposite to the back cavity 12, and an edge fixed extending from the periphery of the vibrating portion 20' and fixed to the base 10 Part 20";
  • the first scribe groove 211 and the second scribe groove 231 are opened in the vibrating part.
  • the part of the piezoelectric diaphragm 20 directly opposite to the back cavity 12 is the vibration part 20', and the self-vibration part 20
  • the part where the periphery extends and is fixed on the base 10 is the edge fixing part 20", in which the first scribe groove 211 and the second scribe groove 231 are opened in the vibration part 20 of the piezoelectric diaphragm 20 to avoid piezoelectric vibration
  • the vibrating part of the membrane 20 is deformed and warped due to the influence of residual stress, which affects the acoustic performance of the piezoelectric MEMS microphone.
  • the base 10 includes a wall 11 that encloses the back cavity 12 and a support portion 13 fixed in the back cavity 12, and the support portion 13 is connected to and supports the pressure
  • the electric diaphragm 20 includes an anchor portion 20 a fixedly supported by the piezoelectric diaphragm 20 and a cantilever beam 20 b extending from the edge of the anchor portion 20 a.
  • the cantilever beam 20 b is suspended in the back cavity 12.
  • the support portion 13 is usually located at the center of the back cavity 12; further, the cantilever beam 20b is suspended above the back cavity 12 of the base 10, so that the piezoelectric diaphragm 20 has better mobility, Vibrate up and down under the action of pressure, with high sensitivity.
  • the orthographic projection of the support portion 13 on the piezoelectric diaphragm 20 does not fall into the first scribe groove 211 and the second scribe groove 231.
  • the first scribe groove 211 includes a radial groove 2111 and a circumferential groove 2111.
  • the groove 2112 wherein the radial groove 2111 includes: a first radial groove 21111 and a second radial groove 21112, the first radial groove 21111 and the second radial groove 21112 are spaced apart and collinear, and the circumferential groove 2112 is opened At the edge of the first electrode layer 21; the second scribe groove 231 opened on the second electrode layer 23 of the piezoelectric diaphragm 20 is consistent with the position, size, structure, etc. of the first scribe groove 211 of the first electrode layer 21.
  • the projection of the support portion 13 in the thickness direction of the piezoelectric diaphragm 20 is staggered from the first scribe groove 211 and the second scribe groove 231, that is, the orthographic projection of the support portion 13 on the piezoelectric diaphragm 20 does not fall into The first scribe groove 211 and the second scribe groove 231; through the structure definition of the piezoelectric diaphragm 20 of this embodiment, the influence of residual stress on the piezoelectric diaphragm 20 can be reduced, and at the same time, the partial structure of the piezoelectric diaphragm 20 can be ensured Integrity, prevents loss of signal-to-noise ratio, and improves the sensitivity and acoustic performance of the piezoelectric diaphragm 20.
  • the piezoelectric MEMS microphone provided by the utility model includes a base 10 with a back cavity 12 and a piezoelectric diaphragm 20 fixed to the base 10 and suspended in the back cavity 12.
  • the piezoelectric diaphragm 20 includes a The first electrode layer 21, the piezoelectric material layer 22, and the second electrode layer 23 are stacked in sequence.
  • the first electrode layer 21 is provided with a first scribe groove 211 along the thickness direction
  • the second electrode layer 23 is provided with a second electrode layer along the thickness direction.
  • Scribe groove 231 the first scribe groove 211 and the second scribe groove 231 are separated by the piezoelectric material layer 22 and are not connected to each other, the first scribe groove 211 penetrates the first electrode layer 21, the second scribe groove 231 and the back cavity 12 Connected.
  • a first scribe groove 211 is formed on the first electrode layer 21 of the piezoelectric diaphragm 20, and a second scribe groove 231 is opened on the second electrode layer 23 of the piezoelectric diaphragm 20, which can reduce the size of the piezoelectric diaphragm 20.
  • the residual stress caused by the piezoelectric diaphragm 20 warps, while maintaining part of the structural integrity of the piezoelectric diaphragm 20, effectively avoiding the loss of signal-to-noise ratio, and ensuring the performance of the piezoelectric MEMS microphone.
  • the method of scribing grooves in the piezoelectric diaphragm 20 is not limited to the above embodiments.
  • the breakdown and symmetry of the specific diaphragm are determined by the stress of the actual diaphragm.
  • the existence form of the diaphragm and the actual shape of the diaphragm are determined.
  • the analysis method also needs to be adjusted accordingly, such as the position, angle, and size of the axial or radial fracture.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)

Abstract

本实用新型提供了一种压电式MEMS麦克风，包括：具有背腔的基座及固定于基座并悬置于背腔的压电振膜，压电振膜包括沿厚度方向依次层叠设置的第一电极层、压电材料层及第二电极层，第一电极层沿厚度方向开设有第一划槽，所述第二电极层沿厚度方向开设有第二划槽，第一划槽与第二划槽划槽由压电材料层分隔且互不连通，第一划槽贯穿第一电极层，第二划槽与背腔连通。本方案在压电振膜的第一电极层开设第一划槽，及在压电振膜的第二电极层开设第二划槽，以减小压电振膜的残余应力，同时保持压电振膜的部分结构完整性，有效避免信噪比损失，保障了压电式MEMS麦克风的性能。

Description

一种压电式MEMS麦克风 技术领域
本实用新型涉及电声转换技术领域，尤其涉及一种压电式MEMS麦克风。
 背景技术
压电式MEMS麦克风相比于传统的电容式MEMS麦克风具有很多优势，包括防尘性和防水性，较高的最大输出声压（AOP）等。受限于压电材料现有的溅射工艺，压电薄膜普遍存在应力，且应力分布不均匀, 较难以控制, 而这一残余应力的存在导致膜片不可避免发生翘曲和形变。
现有技术的压电式MEMS麦克风通常将整片的压电振膜沿着特定方向进行贯穿破分，形成若干个单端固定的悬臂梁结构，该悬臂梁的设计可以一定程度上改善残余应力对膜片形变的影响，但是,这种将压电振膜破分为悬臂梁结构会降低麦克风的信噪比,影响了压电式麦克风的声学性能。
因此，有必要提供一种新的压电式麦克风。
 技术问题
本实用新型的目的在于提供一种压电式MEMS麦克风，可以解决现有技术中的悬臂梁结构会降低麦克风的信噪比的问题。
 技术解决方案
本实用新型的技术方案提供一种压电式MEMS麦克风，包括：具有背腔的基座及固定于所述基座并悬置于所述背腔的压电振膜，所述压电振膜包括沿厚度方向依次层叠设置的第一电极层、压电材料层及第二电极层，第一电极层沿所述厚度方向开设有第一划槽，所述第二电极层沿所述厚度方向开设有第二划槽，所述第一划槽与所述第二划槽所述划槽由所述压电材料层分隔且互不连通，所述第一划槽贯穿所述第一电极层，所述第二划槽与所述背腔连通。
可选的，所述第一划槽和/或所述第二划槽沿所述压电振膜的轴向对称设置。
可选的，所述第一划槽和/或所述第二划槽包括自所述压电振膜的中心朝所述压电振膜的边缘延伸的径向槽。
可选的，所述第一划槽和/或所述第二划槽包括沿所述压电振膜的周向延伸的周向槽。
可选的，至少两个所述周向槽呈弧形且相互间隔设置并围成环状。
可选的，至少两个所述径向槽相互间隔设置且共线。
可选的，所述压电振膜包括与所述背腔正对的振动部以及自所述振动部周缘延伸并固定于所述基座的边缘固定部；所述第一划槽及所述第二划槽开设于所述振动部。
可选的，所述基座包括围成所述背腔的围壁以及固定于所述背腔内的支撑部，所述支撑部连接并支撑所述压电振膜，所述压电振膜包括由所述压电振膜固定支撑的锚定部以及由所述锚定部边缘延伸形成的悬臂梁，所述悬臂梁悬置于所述背腔。
可选的，所述支撑部在所述压电振膜上的正投影未落入所述第一划槽及所述第二划槽内。
 有益效果
本实用新型的有益效果在于：本实用新型提供的压电式MEMS麦克风，包括：具有背腔的基座及固定于基座并悬置于背腔的压电振膜，压电振膜包括沿厚度方向依次层叠设置的第一电极层、压电材料层及第二电极层，第一电极层沿厚度方向开设有第一划槽，所述第二电极层沿厚度方向开设有第二划槽，第一划槽与第二划槽划槽由压电材料层分隔且互不连通，第一划槽贯穿第一电极层，第二划槽与背腔连通。本方案在压电振膜的第一电极层开设第一划槽，及在压电振膜的第二电极层开设第二划槽，可减小压电振膜上的残余应力造成压电振膜翘曲，同时保持压电振膜的部分结构完整性，有效避免信噪比损失，保障了压电式MEMS麦克风的性能。
 附图说明
图1为本实用新型的实施例提供的压电式MEMS麦克风的立体图；
图2为图1的实施例提供的压电式MEMS麦克风沿A-A线的剖面结构示意图；
图3为图1所示的压电式MEMS麦克风的压电振膜沿A’-A’线的剖视结构示意图；
图4为本实用新型的另一实施例提供的具有周向槽的压电式MEMS麦克风的结构示意图；
图5为本实用新型的又一实施例提供的具有周向槽及径向槽的压电式MEMS麦克风的结构示意图；
图6为本实用新型的另一实施例提供的压电式MEMS麦克风的立体图；
图7为图6实施例提供的压电式MEMS麦克风沿B-B线的剖面结构示意图；
图8为本实用新型的另一实施例提供的具有周向槽及径向槽的压电式MEMS麦克风的结构示意图。
 本发明的实施方式
下面结合附图和实施方式对本实用新型作进一步说明。
为了解决现有技术中的悬臂梁结构会降低麦克风的信噪比的技术问题，本实用新型的技术方案提供一种压电式MEMS麦克风；
参考图1至图3，该压电式MEMS麦克风包括：具有背腔12的基座10及固定于基座10并悬置于背腔12的压电振膜20，压电振膜20包括沿厚度方向依次层叠设置的第一电极层21、压电材料层22及第二电极层23，第一电极层21沿厚度方向开设有第一划槽211，第二电极层23沿厚度方向开设有第二划槽231，第一划槽211与第二划槽231划槽由压电材料层22分隔且互不连通，第一划槽211贯穿第一电极层21，第二划槽231与背腔12连通。
本实用新型公开的麦克风为压电式MEMS麦克风，相对于传统的电容式麦克风具有：防尘、防水及较高的最大输出声压等优势，该压电式麦克风是通过压电振膜20在声压的作用下进行上下振动，而压电振膜20中的压电材料层22产生电荷，而产生的电荷被有效电极收集，并转换为电压信号，以传递到相关电路；然而，压电式麦克风的压电振膜20是通过压电材料层22的溅射沉积工艺，在该压电材料层22溅射沉积的过程中一般存在应力或梯度应力等残余应力，该残余应力会使得压电振膜20发声形变，进而对压电式麦克风的性能造成影响，为了使得最大程度释放残余应力，本实用新型对压电式MEMS麦克风及其压电振膜20进行设计。具体的，该压电式MEMS麦克风包括：具有背腔12的基座10及压电振膜20，将压电振膜20固定并悬置在背腔12上方，以实现在声压的作用下进行上下振动，优选的，将压电振膜20与基座10背腔12内的支撑部13或围成背腔12的基座10的围壁11进行固定。
参阅图3，该压电振膜20为利用电极层和压电材料层22进行加工得到的振膜，在结构划分（自上而下）包括：第一电极层21、压电材料层22、第二电极层23，其中，第二电极层23与基座10的部位固定连接，进一步的，在第一电极层21的厚度方向上开设贯穿第一电极层21厚度的第一划槽211，及在第二电极层23的厚度方向上开设贯穿第二电极层23厚度的第二划槽231，第一划槽211与第二划槽231通过压电材料层22进行分隔，使得第一划槽211与第二划槽231之间是不贯通的。结合图1-3所示，第二电极层23的部分部位与基座10的固定连接，所以第二划槽231与背腔12连通的。需要说明的是，当压电材料层22沉积工艺中产生的应力在膜片加工工艺中被释放出来时，压电振膜20上仍存在残余应力，通过对压电振膜20第一电极层21和第二电极层23分别进行部分划分，如在第一电极层21开设第一划槽211，在第二电极层23开设第二划槽231，可降低残余应力的影响，减小膜片发生翘曲，同时，由于第一电极层21及第二电极层23保持部分完整性，使得压电式MEMS麦克风通过围成背腔12的基座10的围壁11或背腔12内的支撑部13收集压电振膜20的电荷，以实现最大程度的收集压电效应产生的信号，可确保较优的信噪比，提升麦克风声学性能，如低频衰减、灵敏度及谐振峰等。
在实施例中，第一划槽211和/或第二划槽231沿压电振膜20的轴向对称设置。具体的，在第一电极层21上开设第一划槽211时，可开设多个划槽，这些划槽沿着压电振膜20（可理解为第一电极层21）的轴向呈对称设置；同理，在第二电极层23上开设第二划槽231时，可开设多个划槽，第二电极层23上的多个划槽沿着压电振膜20（可理解为第二电极层23）的轴向呈对称设置；通过上述对第一电极层21划槽及第二电极层23划槽的位置结构限定，可使得划槽等均开设在第一电极层21和第二电极层23上，以最大化降低残余应力对压电振膜20形变和翘曲的影响。需要注意的是，当形成压电振膜20或膜片的溅射工艺参数发生变化或调整，膜片内残余应力分布的方向、大小都会出现差异，因此，在对压电振膜20的第一电极层21及第二电极层23进行开设划槽时，第一划槽211和/或第二划槽231的位置、角度、尺寸可以根据实际情况进行优化。
参阅图1，在本实施例中，第一划槽211和/或第二划槽231包括自压电振膜20的中心朝压电振膜20的边缘延伸的径向槽2111。优选的，第一划槽211包含径向槽2111，该径向槽2111为自压电振膜20的第一电极层21的中心朝第一电极层21的边缘方向开设的划槽，由于压电振膜20为圆形的膜片，该径向槽2111的位置可为通过第一电极层21圆心的任意直径方向上的部分部位；同理，第二划槽231也包含径向槽2111，该径向槽2111为自压电振膜20的第二电极层23的中心朝第二电极层23的边缘方向开设的划槽。通过本实施例对压电振膜20上的第一划槽211及第二划槽231的位置进行限定，具体分别为第一电极层21、第二电极层23的径向上的位置，以防止残余应力在压电振膜20的径向上造成形变、翘曲的现象。
参阅图4，在本实用新型的另一实施例中，第一划槽211和/或第二划槽231包括沿压电振膜20的周向延伸的周向槽2112。优选的，第一划槽211包括周向槽2112，该周向槽2112为沿着压电振膜20的第一电极层21的轴向上开设的划槽，该划槽的位置可为第一电极层21的任一轴向上的任意部分部位；第二划槽231包含周向槽2112，该周向槽2112为自压电振膜20的第二电极层23的中心朝第二电极层23的边缘方向开设的划槽；通过本实施例对压电振膜20上的第一划槽211及第二划槽231的位置进行限定，具体分别为第一电极层21、第二电极层23的轴向上的位置，以防止残余应力在压电振膜20的轴向上造成形变、翘曲的现象。
参阅图5，在本实用新型的又一实施例中，第一划槽211和/或第二划槽231包括径向槽2111及周向槽2112，该径向槽2111与周向槽2112间隔设置于压电振膜20的中部位置。由于膜片内残余应力分布的方向、大小都会出现差异，在压电振膜20的第一电极层21及第二电极层23的中部开设径向槽2111及周向槽2112，以最大化降低残余应力对压电振膜20形变和翘曲的影响。
参阅图4，在本实施例中，至少两个周向槽2112呈弧形且相互间隔设置并围成环状。具体的，第一划槽211可包含多个周向槽2112，如第一划槽包含4个周向槽2112。优选的，本实施例的第一划槽211包含至少两个周向槽2112，这两个周向槽2112呈弧形开设于第一电极层21，且两个周向槽2112之间相互间隔设置围成环状，以最大化降低残余应力对压电振膜20的第一电极层21的轴向上造成形变、翘曲的现象。同理，第二划槽231也可以包含两个周向槽2112，这两个周向槽2112呈弧形且相互间隔设置围成环状开设于第二电极层23。通过本实施例对第一划槽211及第二划槽231的位置、结构的限定，可降低残余应力对压电振膜20轴向上造成形变、翘曲的现象。
参阅图6，在本实用新型的另一实施例中，至少两个径向槽2111相互间隔设置且共线。具体的，在压电振膜20的第一电极层21开设第一划槽211时，第一划槽为径向槽2111，优选的，可沿着压电振膜20的中心朝压电振膜20边缘方向的同一径向上间隔开设两个径向槽2111，可以理解的是，这两个径向槽2111的位置为共线位于通过第一电极层21圆心的任一直径，如图9和图10中，径向槽包括21111和21112；同理，在第二电极层23的中心朝压电振膜20边缘方向的径向上间隔开设两个径向槽2111，这两个径向槽2111位置为共线位于通过第二电极层23圆心的任意直径。通过上述对多个径向槽2111相互间隔及共线的设置，第一划槽211和/或第二划槽231的位置及尺寸也可以根据实际情况进行优化，以最大化降低残余应力对压电振膜20的影响。
参阅图1至图3，在本实用新型的实施例中，压电振膜20包括与背腔12正对的振动部20’以及自振动部20’周缘延伸并固定于基座10的边缘固定部20’’；第一划槽211及第二划槽231开设于振动部。具体的，由于该压电式麦克风是通过压电振膜20在声压的作用下进行上下振动，而压电振膜20中的压电材料层22产生电荷，因此，为了防止压电振膜20由于残余应力造成的形变、翘曲，进而影响了压电振膜20的上下振动，优选的，以背腔12正对的压电振膜20部位为振动部20’，以自振动部20’周缘延伸并固定在基座10部位为边缘固定部20’’，其中，在压电振膜20的振动部20’开设的第一划槽211及第二划槽231，以避免压电振膜20的振动部由于残余应力的影响发生形变、翘曲的现象，影响压电式MEMS麦克风的声学性能。
参阅图6至图7，在本实用新型的另一实施例中，基座10包括围成背腔12的围壁11以及固定于背腔12内的支撑部13，支撑部13连接并支撑压电振膜20，压电振膜20包括由压电振膜20固定支撑的锚定部20a以及由锚定部20a边缘延伸形成的悬臂梁20b，悬臂梁20b悬置于背腔12。具体的，将压电振膜20安装固定在基座10上时，由于压电振膜20需要根据实际基座10的结构采用不同的安装方式。优选的，该支撑部13通常位于背腔12的中心位置；进一步的，悬臂梁20b悬置在基座10的背腔12上方，使得压电振膜20具有较好的机动性，在外部声压的作用下进行上下振动，具有较高的灵敏度。
参阅图7及图8，在另一实施例中，支撑部13在压电振膜20上的正投影未落入第一划槽211及第二划槽231内。具体的，与图6-7所示的实施例相比，以压电振膜20的第一电极层21上的第一划槽为例，第一划槽211包括径向槽2111及周向槽2112，其中，径向槽2111包括：第一径向槽21111和第二径向槽21112，第一径向槽21111与第二径向槽21112之间隔设置且共线，周向槽2112开设于第一电极层21的边缘部位；压电振膜20的第二电极层23上开设的第二划槽231与第一电极层21的第一划槽211的位置、尺寸、结构等一致。进一步的，支撑部13在压电振膜20的厚度方向上的投影与第一划槽211及第二划槽231是错开的，即支撑部13在压电振膜20的正投影未落入第一划槽211及第二划槽231；通过本实施例的压电振膜20的结构限定，可降低残余应力对压电振膜20的影响，同时，确保压电振膜20的部分结构完整性，防止信噪比损失，提高压电振膜20的灵敏度及声学性能。
本实用新型提供的压电式MEMS麦克风，包括：具有背腔12的基座10及固定于基座10并悬置于背腔12的压电振膜20，压电振膜20包括沿厚度方向依次层叠设置的第一电极层21、压电材料层22及第二电极层23，第一电极层21沿厚度方向开设有第一划槽211，第二电极层23沿厚度方向开设有第二划槽231，第一划槽211与第二划槽231划槽由压电材料层22分隔且互不连通，第一划槽211贯穿第一电极层21，第二划槽231与背腔12连通。本方案在压电振膜20的第一电极层21开设第一划槽211，及在压电振膜20的第二电极层23开设第二划槽231，可减小压电振膜20上的残余应力造成压电振膜20翘曲，同时保持压电振膜20的部分结构完整性，有效避免信噪比损失，保障了压电式MEMS麦克风的性能。
本实用新型提供的压电式MEMS麦克风，其中，对于在压电振膜20开设划槽的方式不限于以上实施方式，具体的膜片的破分以及对称性等要由实际的膜片的应力的存在形式和实际膜片的形状来决定，事实上，当形成压电膜片的溅射工艺参数发生变化或者调整，膜片内残余应力分布的方向，大小都会出现差异，因此膜片的破分方法也需要做出对应的调整，比如轴向或者径向破分的位置，角度，破分尺寸等，当中具体设计应该由有限元仿真和实际测试结果进行设计优化。凡是在振膜结构上添加轴向或者径向的破分(非贯穿整个膜片)，且以减小残余应力的影响为目的的设计，均在本专利保护范围之内。
以上所述的仅是本实用新型的实施方式，在此应当指出，对于本领域的普通技术人员来说，在不脱离本实用新型创造构思的前提下，还可以做出改进，但这些均属于本实用新型的保护范围。

Claims (9)

  1. 一种压电式MEMS麦克风，包括：具有背腔的基座及固定于所述基座并悬置于所述背腔的压电振膜，其特征在于，所述压电振膜包括沿厚度方向依次层叠设置的第一电极层、压电材料层及第二电极层，第一电极层沿所述厚度方向开设有第一划槽，所述第二电极层沿所述厚度方向开设有第二划槽，所述第一划槽与所述第二划槽所述划槽由所述压电材料层分隔且互不连通，所述第一划槽贯穿所述第一电极层，所述第二划槽与所述背腔连通。
  2. 根据权利要求1所述的压电式MEMS麦克风，其特征在于，所述第一划槽和/或所述第二划槽沿所述压电振膜的轴向对称设置。
  3. 根据权利要求1所述的压电式MEMS麦克风，其特征在于，所述第一划槽和/或所述第二划槽包括自所述压电振膜的中心朝所述压电振膜的边缘延伸的径向槽。
  4. 根据权利要求1-3任一项所述的压电式MEMS麦克风，其特征在于，所述第一划槽和/或所述第二划槽包括沿所述压电振膜的周向延伸的周向槽。
  5. 根据权利要求4所述的压电式MEMS麦克风，其特征在于，至少两个所述周向槽呈弧形且相互间隔设置并围成环状。
  6. 根据权利要求3所述的压电式MEMS麦克风，其特征在于，至少两个所述径向槽相互间隔设置且共线。
  7. 根据权利要求1所述的压电式MEMS麦克风，其特征在于，所述压电振膜包括与所述背腔正对的振动部以及自所述振动部周缘延伸并固定于所述基座的边缘固定部；所述第一划槽及所述第二划槽开设于所述振动部。
  8. 根据权利要求1所述的压电式MEMS麦克风，其特征在于，所述基座包括围成所述背腔的围壁以及固定于所述背腔内的支撑部，所述支撑部连接并支撑所述压电振膜，所述压电振膜包括由所述压电振膜固定支撑的锚定部以及由所述锚定部边缘延伸形成的悬臂梁，所述悬臂梁悬置于所述背腔。
  9. 根据权利要求8所述的压电式MEMS麦克风，其特征在于，所述支撑部在所述压电振膜上的正投影未落入所述第一划槽及所述第二划槽内。
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