WO2024087998A1 - 压电mems换能器及其加工方法、封装结构及电子设备 - Google Patents

压电mems换能器及其加工方法、封装结构及电子设备 Download PDF

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WO2024087998A1
WO2024087998A1 PCT/CN2023/121667 CN2023121667W WO2024087998A1 WO 2024087998 A1 WO2024087998 A1 WO 2024087998A1 CN 2023121667 W CN2023121667 W CN 2023121667W WO 2024087998 A1 WO2024087998 A1 WO 2024087998A1
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region
piezoelectric
layer
diaphragm
electrode layer
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PCT/CN2023/121667
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English (en)
French (fr)
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邹泉波
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潍坊歌尔微电子有限公司
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Publication of WO2024087998A1 publication Critical patent/WO2024087998A1/zh

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  • the present application belongs to the technical field of semiconductor devices. Specifically, the present application relates to a piezoelectric MEMS transducer and a processing method thereof, a packaging structure and an electronic device.
  • Piezoelectric MEMS transducer uses the bending vibration of micro-film to transmit and receive ultrasonic waves. It is an ultrasonic transducer based on the piezoelectric energy conversion mechanism.
  • a piezoelectric MEMS transducer generally includes a substrate layer, a support layer and a structural layer.
  • the structural layer and the support layer form a vibrating film. After the substrate layer is partially etched, a back cavity corresponding to the vibrating film is formed under the support layer.
  • the structural layer is supported by the support layer and suspended above the back cavity.
  • the structural layer generally includes a substrate and a piezoelectric layer.
  • the thickness and mechanical strength of the substrate are higher than those of the piezoelectric layer, a larger voltage is required to drive the structural layer to vibrate, and most of the voltage is consumed on the substrate.
  • the purpose of the embodiments of the present application is to provide a new technical solution for a piezoelectric MEMS transducer and a processing method thereof, a packaging structure, and an electronic device.
  • a piezoelectric MEMS transducer comprising: a substrate having a back cavity disposed thereon; and
  • a diaphragm the diaphragm is arranged on the substrate and covers the back cavity, and the diaphragm includes a piezoelectric layer;
  • the diaphragm includes a first area and a second area, the second area is arranged on at least one side of the first area, the first area and the second area are staggered in a first direction, and the first area and the second area are spaced apart in a second direction, wherein the first direction is a height direction of the MEMS transducer, and the second direction is perpendicular to the first direction;
  • One end of the first region and the second region is fixedly connected to the substrate, and one end of the two regions away from the substrate is connected to each other;
  • a first electrode layer is disposed on two opposite surfaces of the first region, and a second electrode layer is disposed on two opposite surfaces of the second region.
  • the first region and the second region expand and contract in opposite directions.
  • the first region and the second region have the same polarization direction, and the first electrode layer and the second electrode layer are connected to opposite voltages.
  • a first gap is provided between the first area and the second area, and the first gap penetrates the diaphragm and is connected to the back cavity.
  • the diaphragm further includes a middle region, and ends of the first region and the second region away from the substrate are connected through the middle region.
  • the diaphragm includes a plurality of membrane petals, a second gap is provided between any two adjacent membrane petals, and the second gap passes through the middle region and is connected to the back cavity.
  • the number of the membrane petals is four;
  • Each of the membrane petals is triangular, and the four membrane petals are symmetrically arranged in pairs to form a rectangular piezoelectric cantilever membrane; or,
  • Each of the membrane petals is fan-shaped, and four of the membrane petals are combined to form a circular piezoelectric cantilever membrane.
  • a substrate is provided, a first production area is formed on the periphery of the substrate with the middle area as a reference, and a second production area is formed outside the first production area; wherein the first production area and the second production area having different height positions on the same side of the substrate;
  • the piezoelectric layer comprising a first region corresponding to the first production region and a second region corresponding to the second production region, and combining the first electrode layer in the first region and combining the second electrode layer in the second region;
  • Another first electrode layer is formed on the surface of the first region away from the sacrificial layer, and another second electrode layer is formed on the surface of the second region away from the sacrificial layer; the piezoelectric layer, the first electrode layer and the second electrode layer form a diaphragm, the diaphragm is etched to form a plurality of membrane petals, and a first gap is formed between the first region and the second region of each membrane petal;
  • a back cavity is formed on a side of the substrate away from the diaphragm, and a sacrificial layer corresponding to the back cavity is removed to obtain a piezoelectric MEMS transducer.
  • a packaging structure comprising a back plate and a housing disposed on the back plate, and the piezoelectric MEMS transducer according to the first aspect;
  • the back plate is provided with a back sound hole, and the back sound hole is communicated with the back cavity.
  • the shell is provided with a sound hole.
  • an electronic device comprising the packaging structure described in the third aspect.
  • the piezoelectric MEMS transducer provided by the present application omits the substrate in the diaphragm structure, and the diaphragm only includes a single piezoelectric layer, wherein the piezoelectric layer includes a first region and a second region having different heights in the height direction of the piezoelectric MEMS transducer.
  • the present application can achieve the performance that can only be achieved by using double-layer PE and three-layer electrodes in the piezoelectric microphone in the prior art by only setting a single-layer piezoelectric layer structure, and greatly reduces the voltage required to drive the piezoelectric MEMS transducer.
  • FIG1 is a schematic diagram of the overall structure of a piezoelectric MEMS transducer provided in an embodiment of the present application
  • FIG2 is a second schematic diagram of the overall structure of a piezoelectric MEMS transducer provided in an embodiment of the present application
  • FIG3 is a third schematic diagram of the overall structure of the piezoelectric MEMS transducer provided in an embodiment of the present application.
  • FIG4 is one of the overall structural schematic diagrams of the diaphragm provided in the embodiment of the present application.
  • FIG5 is a second schematic diagram of the overall structure of the diaphragm provided in an embodiment of the present application.
  • Fig. 6 is a cross-sectional view along the A-A' direction of Fig. 4;
  • Fig. 7 is a cross-sectional view along the B-B' direction of Fig. 4;
  • FIG8 is a side view of a diaphragm provided in an embodiment of the present application.
  • FIG9 is a schematic diagram of the structure of a diaphragm after deformation provided by an embodiment of the present application.
  • FIG10 is a schematic diagram of a processing method provided in an embodiment of the present application.
  • FIG11 is one of the schematic diagrams of the packaging structure provided in an embodiment of the present application.
  • FIG12 is a second schematic diagram of a packaging structure provided in an embodiment of the present application.
  • FIG. 13 is a third schematic diagram of the packaging structure provided in an embodiment of the present application.
  • the present application discloses a piezoelectric MEMS transducer, which is a type of MEMS device that uses the forward and reverse piezoelectric effects of piezoelectric materials to vibrate the diaphragm, thereby transmitting or receiving ultrasonic signals.
  • a piezoelectric MEMS transducer When it is used to transmit ultrasonic waves, it is an actuator; when it is used to receive ultrasonic waves, it is a sensor.
  • piezoelectric MEMS transducers include microphones, bulk acoustic wave filters (BAW Filters), micro-speakers, piezoelectric micromachined ultrasonic transducers (PMUT, Piezoelectric Micromachined Ultrasonic Transducers), etc.
  • the present application discloses a piezoelectric MEMS transducer, comprising a substrate 1, on which a back cavity 11 is disposed; and a diaphragm 2, which is disposed on the substrate 1 and covers the back cavity 11, and comprises a piezoelectric layer 21;
  • the piezoelectric layer 21 includes a first region 211 and a second region 212, wherein the second region 212 is arranged on at least one side of the first region, the first region 211 and the second region 212 are staggered in a first direction, and the first region 211 and the second region 212 are spaced apart in a second direction, wherein the first direction is a height direction of the piezoelectric MEMS transducer, and the second direction is perpendicular to the first direction;
  • One end of the first region 211 and the second region 212 are fixedly connected to the substrate 1, and one end of the two regions away from the substrate 1 are connected to each other;
  • the first electrode layer 22 is disposed on two opposite surfaces of the first region 211
  • the second electrode layer is disposed on two opposite surfaces of the second region 212 .
  • the piezoelectric MEMS transducer 6 includes a substrate 1 and a diaphragm 2, wherein a middle region 210 of the substrate 1 is partially etched to form a back cavity 11, the diaphragm 2 is suspended above the back cavity 11, and the back cavity 11 is arranged below the diaphragm 2 and corresponds to the diaphragm 2, that is, the diaphragm 2 Cover the back cavity 11.
  • the diaphragm 2 includes a piezoelectric layer 21, and the piezoelectric layer 21 includes a first region 211 and a second region 212.
  • the second region 212 is disposed on at least one side of the first region 211. That is, the second region 212 can be disposed on one side of the first region 211, or on both sides of the first region 211.
  • One end of the first region 211 and the second region 212 is fixedly connected to the substrate 1 , and one end of the first region 211 and the second region 212 away from the substrate 1 is connected to each other, thereby ensuring the synchronous movement of the diaphragm 2 in the first region 211 and the second region 212 .
  • the second region 212 is disposed on both sides of the first region 211, the left ends of the first region 211 and the second region 212 are connected to the substrate 1, and the left ends of the first region 211 and the second region 212 are fixed ends.
  • the right ends of the first region 211 and the second region 212 are connected to each other, and the right ends of the first region 211 and the second region 212 are free ends.
  • the first area 211 and the second area 212 are staggered in the first direction, and the first direction is the height direction of the piezoelectric MEMS transducer.
  • the height direction of the piezoelectric MEMS transducer is also the vibration direction of the diaphragm 2, that is, the vertical direction in Figure 1.
  • the first area 211 and the second area 212 have different heights.
  • the first area 211 and the second area 212 are located in two planes in the vibration direction of the diaphragm 2.
  • the height of the first area 211 may be greater than the height of the second area 212, that is, the first area 211 may be a convex structure.
  • the height of the first area 211 may be less than the height of the second area 212, that is, the first area 211 may be a concave structure.
  • the first region 211 is a recessed structure, and the height of the first region 211 in this direction is smaller than the height of the second region 212. In other words, the distance between the first region 211 and the substrate 1 is smaller than the distance between the second region 212 and the substrate 1.
  • the first area 211 and the second area 212 are spaced apart in the second direction, wherein the first direction is the height direction of the piezoelectric MEMS transducer, and the second direction is perpendicular to the first direction.
  • the second direction can be any direction perpendicular to the vibration direction of the diaphragm 2.
  • a gap is provided between the first area 211 and the second area 212.
  • the size of the gap can be set according to actual needs.
  • the diaphragm 2 structure provided in this application includes only one piezoelectric layer 21 at each position.
  • the first electrode layer 22 is respectively disposed on two opposite surfaces of the first region 211, and the second electrode layer 23 is respectively disposed on two opposite surfaces of the second region 212.
  • the first electrode layer 22 is provided with two layers, and the two layers of the first electrode layer 22 are formed on two surfaces of the piezoelectric layer 21 and cover the first region 211.
  • the second electrode layer 23 is formed on two surfaces of the piezoelectric layer 21 and covers the second region 212.
  • the diaphragm 2 generally includes a substrate and a piezoelectric layer 21.
  • the thickness and mechanical strength of the substrate are higher than those of the piezoelectric layer 21, when the piezoelectric MEMS transducer 6 is used as a driver, a larger voltage is required to drive the diaphragm 2 to vibrate, and most of the voltage is consumed on the substrate.
  • the piezoelectric MEMS transducer 6 provided in the present application omits the substrate, thereby reducing the loss of driving voltage on the substrate, and reducing the driving voltage required to drive the diaphragm 2 to vibrate when controlling the MEMS transducer as a driver, thereby matching the voltage that can be achieved by the current ASIC chip, thereby improving the competitiveness of the piezoelectric MEMS transducer 6 and reducing the limitations of the piezoelectric MEMS transducer 6 in its development process due to the excessive driving voltage required.
  • the drivers of existing chips are made of lead piezoelectric material PZT thin film, electrodes and patterning on the base layer (such as Si or PolySi) of the MEMS diaphragm 2, and the sensitivity of general inner ear applications can be achieved by using a driver ASIC with a maximum voltage of about 30V.
  • the restrictions on PZT lead materials in RoHS have become increasingly strict, and the compatibility with IC/CMOS processes is poor.
  • the piezoelectric layer 21 can select AlN piezoelectric material compatible with CMOS technology, which is expected to promote the industrialization of lead-free AlN.
  • the one-layer piezoelectric layer 21 structure provided in the present application greatly reduces the problems of uneven diaphragm 2, inconsistent performance, and yield loss caused by stress and dispersion of the single-layer piezoelectric layer during processing.
  • the manufacturing process of the single-layer piezoelectric layer 21 is simpler than the double-layer structure of the prior art, and the stress gradient is easy to control, which has competitive advantages in performance and consistency, and is lower in cost.
  • the diaphragm is composed of a substrate and a piezoelectric layer. Since the substrate and the piezoelectric layer are made of different materials, when the temperature changes, the substrate and the piezoelectric layer expand and contract to different degrees, resulting in the diaphragm structure being greatly affected by temperature.
  • the first region 211 and the second region 212 of the piezoelectric layer 21 are designed to be symmetrically distributed along the thickness direction of the piezoelectric layer 21, and the first region 211 and the second region 212 of the piezoelectric layer 21 are made of the same material. Therefore, when the ambient temperature changes, the structure of the piezoelectric layer 21 changes little, that is, the piezoelectric MEMS transducer 6 is less sensitive to the ambient temperature and can still maintain structural stability when the ambient temperature changes.
  • the first region 211 and the second region 212 expand and contract in opposite directions.
  • the first region 211 and the second region 212 When a voltage is applied to the piezoelectric layer 21, the first region 211 and the second region 212 have opposite expansion and contraction directions.
  • the expansion and contraction direction of the piezoelectric layer 21 depends on the polarization direction and the direction of the applied electric field. Specifically, to make the expansion and contraction directions of the first region 211 and the second region 212 of the piezoelectric layer 21 opposite, in one case, the polarization directions of the first region 211 and the second region 212 are the same, and the directions of the electric fields applied by the first electrode layer 22 and the second electrode layer 23 are opposite. In one case, the polarization directions of the first region 211 and the second region 212 are opposite, and the directions of the electric fields applied by the first electrode layer 22 and the second electrode layer 23 are the same.
  • the polarization directions of the first region 211 and the second region 212 are the same;
  • the first electrode layer 22 and the second electrode layer 23 are connected to opposite voltages.
  • the arrows in FIG6 and FIG7 are the directions of applied voltages, and the arrow in FIG8 is the direction of movement of the piezoelectric layer 21 under the action of voltage. It can be seen from the figure that voltages in opposite directions are applied to the first electrode layer 22 and the second electrode layer 23.
  • the downward arrow in the first region 211 in FIG6 indicates that the first electrode layer 22 applies a negative voltage to the piezoelectric layer 21 of the first region 211
  • the upward arrow in the second region 212 indicates that the second electrode layer 23 applies a positive voltage to the piezoelectric layer 21 of the second region 212.
  • the piezoelectric layers 21 of the first region 211 and the second region 212 are both made of materials with negative piezoelectric coefficients, such as AlN materials, and the polarization directions of the piezoelectric layers 21 of the first region 211 and the second region 212 are controlled to be the same.
  • the second region 212 contracts, that is, it moves in the direction indicated by the arrow in the second region 212.
  • the first region 211 expands, that is, it moves in the direction indicated by the arrow in the first region 211 in FIG8, so that the free end of the diaphragm 2 moves upward.
  • the free end is a concept relative to the fixed end, and the end of the diaphragm 2 fixedly connected to the substrate 1 is the fixed end, that is, the left end shown in FIG8.
  • the right end of the diaphragm 2 shown in FIG8 is the free end, and the diaphragm 2 at the free end is suspended.
  • first electrode layer 22 and the second electrode layer 23 are electrically connected to an external power supply, respectively, and the first electrode layer 22 and the second electrode layer 23 are independently connected to the power supply.
  • the first electrode layer 22 and the second electrode layer 23 in the present application are relatively independent, so the two can be electrically connected to form a differential signal output to improve the sensitivity, signal-to-noise ratio SNR, and acoustic overload point AOP and other important performances of the piezoelectric MEMS transducer 6.
  • FIG9 is a simplified schematic diagram of the diaphragm 2 after deformation.
  • H is the deformation of the first region 211 of the piezoelectric layer, that is, the first region of the piezoelectric layer Amplitude of 211;
  • R is the radius of curvature of the piezoelectric layer of the first region 211 after deformation
  • d is the distance between the piezoelectric layers of the first region 211 and the second region 212;
  • ⁇ is the arc of the piezoelectric layer of the first region 211/the second region 212 after deformation
  • ⁇ is the difference in piezoelectric layer strain between the first region 211 and the second region 212;
  • L1 is the length of the piezoelectric layer in the first region 211
  • L2 is the length of the piezoelectric layer in the second region 212 .
  • a first gap 213 is disposed between the first area 211 and the second area 212 .
  • the first gap 213 penetrates the diaphragm 2 and communicates with the back cavity 11 .
  • a first gap 213 is disposed between the first region 211 and the second region 212, and is used to separate the first region 211 from the second region 212 of the piezoelectric layer 21, so that the fixed ends (i.e., the left ends of FIG. 5 ) of the piezoelectric layer 21 in the first region 211 and the second region 212 are respectively fixedly connected to the substrate 1, while the free ends (i.e., the right ends of FIG. 5 ) of the piezoelectric layer 21 in the first region 211 and the second region 212 are connected via the middle region 210.
  • the present application sets a first gap 213 between the first region 211 and the second region 212 so that when the first region 211 and the second region 212 of the piezoelectric layer 21 are deformed, the first region 211 and the second region 212 of the piezoelectric layer 21 reduce the reaction force between each other, so that the two cooperate to achieve the deformation of the free end (the right end of FIG.
  • the piezoelectric layer 21 that is, the vibration of the diaphragm 2, thereby improving the sensitivity and accuracy of the vibration of the diaphragm 2, and thereby improving the sensitivity, signal-to-noise ratio SNR, and acoustic overload point AOP and other important performances of the piezoelectric MEMS transducer 6.
  • the diaphragm 2 further includes a middle region 210 , and the first region 211 and the second region 212 are connected at one end away from the substrate 1 through the middle region 210 .
  • the middle area 210 is the range corresponding to the center position of the diaphragm 2 , and the size of the middle area 210 can be adjusted according to actual needs.
  • the first area 211 and the second area 212 are integrally connected through the middle area 210 .
  • the diaphragm 2 includes a plurality of membrane petals 3 , and a second gap 24 is provided between any two adjacent membrane petals 3 .
  • the second gap 24 passes through the middle region 210 and is connected to the back cavity 11 .
  • the diaphragm 2 in the present application includes a plurality of membrane petals 3.
  • the membrane petals 3 are cut from the diaphragm 2, and a second gap 24 is set between any two adjacent membrane petals 3.
  • the second gap 24 passes through the middle area 210 and is connected to the back cavity 11.
  • the second gap 24 runs through the second electrode layer 23, the piezoelectric layer 21 and the first electrode layer 22.
  • the membrane petals 3 are provided in four numbers;
  • Each of the membrane petals 3 is triangular, and the four membrane petals 3 are symmetrically arranged in pairs to form a rectangular piezoelectric cantilever membrane; or,
  • Each of the membrane petals 3 is fan-shaped, and four of the membrane petals 3 enclose a circular piezoelectric cantilever membrane.
  • the diaphragm 2 is configured as a rectangle as a whole, and the diaphragm 2 includes four diaphragm petals 3 , each of which is triangular in shape.
  • the diaphragm 2 is configured as a circular shape as a whole, and the diaphragm 2 includes four diaphragm petals 3 , each of which is fan-shaped.
  • a second gap 24 is formed between adjacent membrane petals 3 , and a first gap 213 is formed between the first area 211 and the second area 212 of each membrane petal 3 .
  • the present application also discloses a processing method for the piezoelectric MEMS transducer as described above, wherein FIG10 mainly shows the processing process of the first region 211.
  • the processing method disclosed in the present application includes the following steps:
  • the substrate 1 is made of Si or PolySi.
  • RIE or wet etching can be used to etch into silicon to form a recessed first production area 214, and the second production area is formed outside the first production area 214.
  • a LOCOS process is used, that is, local oxidation is performed on the substrate 1, and masked by SiO2 / Si3N4 , and then SiO2 / Si3N4 is removed, so as to form a recessed first production area 214, and the second production area is formed outside the first production area 214.
  • the sacrificial layer 4 may be made of, for example, SiO 2 .
  • the piezoelectric layer 21 including a first area 211 corresponding to the first production area 214 and a second area 212 corresponding to the second production area, and combining the first electrode layer 22 in the first area 211, and combining the second electrode layer 23 in the second area 212.
  • the piezoelectric layer 21 may be made of AlN or PZT.
  • the materials of the first electrode layer 22 and the second electrode layer 23 are selected according to the material of the piezoelectric layer 21 .
  • the piezoelectric layer 21 is made of AlN
  • the first electrode layer 22 and the second electrode layer 23 are made of molybdenum
  • the piezoelectric layer 21 is made of PZT material
  • the first electrode layer 22 and the second electrode layer 23 are made of platinum.
  • first electrode layer 22 is formed on the surface of the first region 211 away from the sacrificial layer 4
  • second electrode layer 23 is formed on the surface of the second region 212 away from the sacrificial layer 4.
  • the piezoelectric layer 21, the two layers of the first electrode layer 22 and the second electrode layer 23 form a diaphragm 2.
  • a plurality of second gaps 24 are etched on the diaphragm 2 as needed, thereby separating the diaphragm 2 into a plurality of membrane petals 3.
  • each membrane petal 3 is etched to form a first gap 213, and the first gap 213 separates the first region 211 from the second region 212.
  • the back cavity 11 can be obtained by photolithography and DRIE etching through the silicon substrate 1.
  • the sacrificial layer 4 is removed by RIE dry etching and wet etching.
  • the present application also discloses a packaging structure, comprising a back plate 7, a housing 8 disposed on the back plate 7, and the piezoelectric MEMS transducer 6 as described above; wherein,
  • the back plate 7 is provided with a back sound hole 71 , and the back sound hole 71 is communicated with the back cavity 11 .
  • the piezoelectric MEMS transducer 6 is placed on the back plate 7, and a back sound hole 71 is provided on the back plate 7.
  • the back sound hole 71 is connected to the back cavity 11 to facilitate the transmission of sound.
  • the housing 8 is arranged on the periphery of the piezoelectric MEMS transducer 6 and connected to the back plate 7 to protect the piezoelectric MEMS transducer 6.
  • the housing 8 is provided with a sound hole 81 .
  • the sound hole 81 may be disposed on a side of the housing 8 opposite to the first gap 213.
  • the sound hole 81 may also be disposed on a side wall of the housing 8. The present application does not limit the location of the sound hole 81.
  • two piezoelectric MEMS transducers 6 are provided in the embodiment of the present application, and the two piezoelectric MEMS transducers 6 are electrically and acoustically connected in parallel, which can improve the consistency between the multiple piezoelectric MEMS transducers 6 .
  • piezoelectric MEMS transducers 6 may be provided.
  • the present application does not limit the number of piezoelectric MEMS transducers 6 . It is only necessary to electrically and acoustically connect multiple piezoelectric MEMS transducers 6 in parallel.
  • the present application also provides an electronic device, comprising the packaging structure as described above.
  • the electronic device may be a head-mounted display device, a smart watch, a mobile phone, etc.

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Abstract

本申请实施例公开了一种压电MEMS换能器及其加工方法、封装结构及电子设备，压电MEMS换能器包括衬底以及振膜，所述振膜包括压电层，所述压电层包括第一区域以及第二区域，所述第二区域设置在所述第一区域的至少一侧，所述第一区域与所述第二区域在第一方向上错位设置，且所述第一区域与第二区域在第二方向上间隔设置，其中第一方向为所述压电MEMS换能器的高度方向，所述第二方向与所述第一方向垂直；所述第一区域相对的两个表面上分别设有第一电极层，所述第二区域相对的两个表面上分别设有第二电极层。本申请实施例的一个技术效果在于通过设置一种省略基板且采用单层压电层的振膜，极大降低了驱动压电MEMS换能器所需的电压。

Description

压电MEMS换能器及其加工方法、封装结构及电子设备
本公开要求于2022年10月27日提交中国专利局，申请号为202211326526.X，申请名称为“压电MEMS换能器及其加工方法、封装结构及电子设备”的中国专利申请的优先权，其全部内容通过引用结合在本公开中。
技术领域
本申请属于半导体器件技术领域，具体地，本申请涉及一种压电MEMS换能器及其加工方法、封装结构及电子设备。
背景技术
压电MEMS换能器利用微薄膜的弯曲振动发射和接收超声波，是基于压电能量转换机理的一种超声换能器。
现有技术中，压电MEMS换能器一般包括衬底层、支撑层和结构层，结构层和支撑层组成振动薄膜，衬底层部分刻蚀后在支撑层下方形成与振动薄膜相对应的背腔，结构层由支撑层承载并且悬置于背腔之上。其中，结构层一般包括基板以及压电层，使用时，通过对压电层施加驱动电压，根据逆压电效应，压电层发生伸缩并带动基板发生形变，从而实现结构层整体的振动。
但是，由于基板的厚度以及机械强度均高于压电层，因此驱动结构层振动需要较大的电压，且大部分电压消耗在基板上。
发明内容
本申请实施例的目的是提供一种压电MEMS换能器及其加工方法、封装结构及电子设备的新技术方案。
根据本申请实施例的第一方面，提供了一种压电MEMS换能器，包括 衬底，所述衬底上设置有背腔；以及
振膜，所述振膜设置于所述衬底上且覆盖所述背腔，所述振膜包括压电层；
所述振膜包括第一区域以及第二区域，所述第二区域设置在所述第一区域的至少一侧，所述第一区域与所述第二区域在第一方向上错位设置，且所述第一区域与所述第二区域在第二方向上间隔设置，其中第一方向为所述MEMS换能器的高度方向，所述第二方向与所述第一方向垂直；
所述第一区域及所述第二区域的一端与所述衬底固定连接，且二者远离所述衬底的一端相互连接；
所述第一区域相对的两个表面上分别设有第一电极层，所述第二区域相对的两个表面上分别设有第二电极层。
可选地，在对所述压电MEMS换能器施加电压的情况下，所述第一区域及所述第二区域的伸缩方向相反。
可选地，所述第一区域及所述第二区域的极化方向相同，所述第一电极层与所述第二电极层连接的电压相反。
可选地，所述第一区域与第二区域之间设置有第一间隙，所述第一间隙贯穿所述振膜且与所述背腔连通。
可选地，所述振膜还包括中部区域，所述第一区域及所述第二区域远离所述衬底的一端通过所述中部区域连接。
可选地，所述振膜包括多个膜瓣，任两个相邻的所述膜瓣之间设置有第二间隙，所述第二间隙穿过所述中部区域且与所述背腔连通。
可选地，所述膜瓣设置为四个；
每个所述膜瓣呈三角形，且四个所述膜瓣两两对称设置形成矩形压电悬臂膜；或者，
每个所述膜瓣呈扇形，且四个所述膜瓣围合形成圆形压电悬臂膜。
根据本申请实施例的第二方面，还提供了一种用于第一方面所述的压电MEMS换能器的加工方法，包括以下步骤：
提供衬底，以中部区域为基准在其周侧形成第一制作区，在所述第一制作区的外侧形成第二制作区；其中，所述第一制作区与所述第二制作区 在所述衬底的同一侧具有不同的高度位置；
在所述衬底上形成牺牲层，并在所述牺牲层的表面分别制作第一层的第一电极层及第二电极层，所述第一电极层位于第一制作区内，所述第二电极层位于第二制作区内；
在所述牺牲层上形成压电层，所述压电层包括与所述第一制作区对应的第一区域及与所述第二制作区对应的第二区域，并使所述第一电极层结合在所述第一区域，所述第二电极层结合在所述第二区域；
在所述第一区域背离所述牺牲层的表面制作另一层所述的第一电极层，及在所述第二区域背离所述牺牲层的表面制作另一层所述第二电极层；压电层、第一电极层及第二电极层形成振膜，刻蚀所述振膜形成多个膜瓣，并在每个膜瓣的第一区域与第二区域之间形成第一间隙；
在两层所述第一电极层及第二电极层的表面分别形成焊盘；
在所述衬底背离所述振膜的一侧形成背腔，并去除背腔对应的牺牲层，得到压电MEMS换能器。
根据本申请实施例的第三方面，还提供了一种封装结构，包括背板以及设置于所述背板上的外壳，以及第一方面所述的压电MEMS换能器；其中，
所述背板开设有背声孔，所述背声孔与所述背腔连通。
可选地，所述外壳开设有声孔。
根据本申请实施例的第四方面，还提供了一种电子设备，包括第三方面所述的封装结构。
本申请实施例的一个技术效果在于：
本申请提供的压电MEMS换能器，振膜结构中省略了基板，振膜仅包括单层压电层，其中压电层包括在压电MEMS换能器的高度方向上具有不同的高度的第一区域以及所述第二区域。本申请仅通过设置单层压电层结构，即可实现现有技术中压电麦克风中用双层PE、三层电极才能实现的性能，并且极大降低了驱动压电MEMS换能器所需的电压。
通过以下参照附图对本申请的示例性实施例的详细描述，本申请的其它特征及其优点将会变得清楚。
附图说明
被结合在说明书中并构成说明书的一部分的附图示出了本申请的实施例，并且连同其说明一起用于解释本申请的原理。
图1为本申请实施例提供的压电MEMS换能器的整体结构示意图之一；
图2为本申请实施例提供的压电MEMS换能器的整体结构示意图之二；
图3为本申请实施例提供的压电MEMS换能器的整体结构示意图之三；
图4为本申请实施例提供的振膜的整体结构示意图之一；
图5为本申请实施例提供的振膜的整体结构示意图之二；
图6为图4沿A-A’方向的剖视图；
图7为图4沿B-B’方向的剖视图；
图8为本申请实施例提供的振膜的侧视图；
图9为本申请实施例提供的振膜发生形变后的结构示意图；
图10为本申请实施例提供的加工方法示意图；
图11为本申请实施例提供的封装结构示意图之一；
图12为本申请实施例提供的封装结构示意图之二；
图13为本申请实施例提供的封装结构示意图之三。
附图标记说明：
1、衬底；11、背腔；2、振膜；21、压电层；210、中部区域；211、
第一区域；212、第二区域；213、第一间隙；214、第一制作区；22、第一电极层；23、第二电极层；24、第二间隙；3、膜瓣；4、牺牲层；5、焊盘；6、压电MEMS换能器；7、背板；71、背声孔；8、外壳；81、声孔。
具体实施方式
现在将参照附图来详细描述本申请的各种示例性实施例。应注意到：除非另外具体说明，否则在这些实施例中阐述的部件和步骤的相对布置、数字表达式和数值不限制本申请的范围。
以下对至少一个示例性实施例的描述实际上仅仅是说明性的，决不作为对本申请及其应用或使用的任何限制。
对于相关领域普通技术人员已知的技术、方法和设备可能不作详细讨论，但在适当情况下，所述技术、方法和设备应当被视为说明书的一部分。
在这里示出和讨论的所有例子中，任何具体值应被解释为仅仅是示例性的，而不是作为限制。因此，示例性实施例的其它例子可以具有不同的值。
应注意到：相似的标号和字母在下面的附图中表示类似项，因此，一旦某一项在一个附图中被定义，则在随后的附图中不需要对其进行进一步讨论。
本申请公开了一种压电MEMS换能器，是一类通过压电材料的正逆压电效应使振膜振动，从而发射或者接收超声波信号的MEMS器件。其中，当其用于发射超声波时，它是一个执行器；当其用于接收超声波时，它是一个传感器。例如，压电MEMS换能器包括麦克风、体声波滤波器(BAW Filter)、微型扬声器(micro-speaker)、压电微机械超声换能器(PMUT，Piezoelectric Micromachined Ultrasonic Transducers)等。
参照图1-图9，本申请公开了一种压电MEMS换能器，包括衬底1，所述衬底1上设置有背腔11；以及振膜2，所述振膜2设置于所述衬底1上且覆盖所述背腔11，所述振膜2包括压电层21；
所述压电层21包括第一区域211以及第二区域212，所述第二区域212设置在所述第一区域的至少一侧，所述第一区域211与所述第二区域212在第一方向上错位设置，且所述第一区域211与所述第二区域212在第二方向上间隔设置，其中第一方向为所述压电MEMS换能器的高度方向，所述第二方向与所述第一方向垂直；
所述第一区域211及所述第二区域212的一端与所述衬底1固定连接，且二者远离所述衬底1的一端相互连接；
所述第一区域211相对的两个表面上分别设有第一电极层22，所述第二区域212相对的两个表面上分别设有第二电极层。
参照图1，本申请实施例中，压电MEMS换能器6包括衬底1以及振膜2，其中，衬底1的中部区域210部分刻蚀后形成背腔11，振膜2悬置于背腔11之上，背腔11设置于振膜2下方且与振膜2相对应，也即振膜2 覆盖背腔11。
请继续参照图1，振膜2包括压电层21，压电层21包括第一区域211以及第二区域212。第二区域212设置在第一区域211的至少一侧。也就是说，第二区域212例如可以设置在第一区域211的一侧，第二区域212也可以例如设置在第一区域211的两侧。
第一区域211及第二区域212的一端与衬底1固定连接，第一区域211及第二区域212的远离衬底1的一端相互连接。从而保证振膜2在第一区域211及第二区域212的同步运动。
具体来说，本申请的一种实施例中，参照图2-图3，第二区域212设置于第一区域211的两侧，第一区域211及第二区域212的左端与衬底1连接，第一区域211与第二区域212的左端为固定端。第一区域211与第二区域212的右端相互连接，第一区域211与第二区域212的右端为自由端。
本申请实施例中，所述第一区域211与所述第二区域212在第一方向上错位设置，第一方向为所述压电MEMS换能器的高度方向。其中，压电MEMS换能器的高度方向也即振膜2的振动方向，也即图1中的竖直方向。也就是说，在该方向上，第一区域211与第二区域212具有不同的高度。第一区域211与第二区域212在振膜2的振动方向上位于两个平面。具体来说，第一区域211的高度可以大于第二区域212的高度，也即第一区域211可以为凸起结构。第一区域211的高度可以小于第二区域212的高度，也即第一区域211可以为凹陷结构。
本申请一种实施例中，参照图4-图8，第一区域211为凹陷结构，第一区域211在该方向上的高度小于第二区域212的高度，换言之，第一区域211与衬底1之间的距离小于第二区域212与衬底1之间的距离。
本申请实施例中，第一区域211与所述第二区域212在第二方向上间隔设置，其中第一方向为压电MEMS换能器的高度方向，第二方向与第一方向垂直。也就是说，第二方向可以是与振膜2的振动方向垂直的任意方向。在第二方向上，第一区域211与第二区域212之间设置有间隙。当然，该间隙的尺寸可以根据实际需要进行设置。
参照图4，第一区域211与第二区域212在衬底1上的投影不发生重叠。换言之，在第二区域212所在平面上，第一区域211对应的位置为镂空设置。本申请中提供的振膜2结构在各个位置处均只包括一层压电层21。
所述第一区域211相对的两个表面上分别设有第一电极层22，所述第二区域212相对的两个表面上分别设有第二电极层23。也就是说，第一电极层22设置有两层，两层第一电极层22形成于压电层21的两个表面并覆盖第一区域211。第二电极层23形成于压电层21的两个表面并覆盖第二区域212。
现有技术中，振膜2一般包括一层基板以及一层压电层21。但是，由于基板的厚度以及机械强度均高于压电层21，因此当压电MEMS换能器6作为驱动器时，驱动振膜2振动需要较大的电压，且大部分电压消耗在基板上。
本申请提供的压电MEMS换能器6，一方面，由于省略了基板，从而减少了驱动电压在基板上的损耗，降低了控制MEMS换能器作为驱动器时驱动振膜2振动所需的驱动电压，从而可以匹配目前的ASIC芯片所能达到的电压，提高了压电MEMS换能器6的竞争力，减少了需要的驱动电压过大对压电MEMS换能器6发展过程中的限制。
具体来说，在执行器(如微型扬声器)方面，现有芯片的驱动器都是在MEMS振膜2的基层(如Si或PolySi)上制作铅压电材料PZT薄膜、电极并图形化，采用最高约30V的驱动ASIC即可达到一般内耳应用的灵敏度。但是，近年来PZT有铅材料在RoHS方面的限制越来越严，且与IC/CMOS工艺兼容性差。
但是与CMOS技术兼容的AlN压电材料直接用来替代PZT尚有难度。主要是因为AlN材料的压电系数d31太低，AlN材料比PZT低约2个数量级(典型数值，AlN：d31＝-3.5pV/m，∈33＝10∈0；而PZT-5R类d31＝-200pV/m，∈33＝2000∈0)。所以AlN压电材料制成压电MEMS换能器需要采用要求更高的驱动电压(如超过数百伏特，
S11＝d31*Vdrive/Tpe，其中S11为面内应变，d31为压电系数，Vdrive是压电层厚度方向上的驱动电压)，功耗计算公式如下：
P＝πf*C*Vpp2
＝πf*(∈33*Area/Tpe)*(S11*Tpe/d31)2
＝πf*Area*Tpe*S12*∈33/d312
因此，本申请提供的压电MEMS换能器6所需的驱动电压、功率均大幅减小，因此压电层21可以选择与CMOS技术兼容的AlN压电材料，有望推动无铅AlN的产业化。
另一方面，相比现有技术中振膜2所采用的两层结构，本申请提供的一层压电层21结构，单层压电层在加工过程中由于应力及分散性造成的振膜2不平、性能不一致以及良率损失等问题大幅减小。在传感器(如麦克风)方面，单层压电层21的制作工艺比现有技术的双层结构更加简单，且应力梯度易控，在性能及一致性方面具有竞争优势，且成本更低。
除此之外，现有技术中振膜由基板与压电层组成，由于基板与压电层采用不同的材料，因此在温度改变时，基板与压电层发生热胀冷缩的程度不同，从而导致振膜结构受温度影响较大。而本申请中将压电层21的第一区域211及第二区域212，设计在沿压电层21的厚度方向对称分布，且压电层21的第一区域211及第二区域212采用同一材料。因此在环境温度发生改变时，压电层21的结构变化小，也即压电MEMS换能器6对环境温度敏感度低，在环境温度改变时仍然可以保持结构的稳定。
可选地，在对所述压电MEMS换能器6施加电压的情况下，所述第一区域211及所述第二区域212的伸缩方向相反。
在对压电层21施加电压的情况下，第一区域211及第二区域212的伸缩方向相反。其中，压电层21的伸缩方向取决于极化方向以及施加的电场方向。具体来说，要使压电层21的第一区域211及第二区域212的伸缩方向相反，一种情形下，第一区域211与第二区域212的极化方向相同，第一电极层22与第二电极层23施加的电场方向相反。一种情形下，第一区域211与第二区域212的极化方向相反，第一电极层22与第二电极层23施加的电场方向相同。
本申请实施例中，所述第一区域211及所述第二区域212的极化方向相同；
所述第一电极层22与所述第二电极层23连接的电压相反。
参照图6-图8，其中，图6及图7中的箭头方向为施加的电压方向，图8中的箭头方向为压电层21在电压作用下的移动方向。根据图示可知对第一电极层22与第二电极层23施加方向相反的电压。
具体来说，图6中第一区域211内向下的箭头指第一电极层22对第一区域211的压电层21施加负电压，第二区域212内向上的箭头指第二电极层23对第二区域212的压电层21施加正电压。参照图8，本申请一种实施例中，第一区域211及第二区域212的压电层21均采用压电系数为负的材料例如AlN材料，并控制第一区域211及第二区域212的压电层21的极化方向相同，此时在电压作用下，第二区域212发生收缩，也即第二区域212内的箭头所示的方向移动。第一区域211发生膨胀，也即沿图8中第一区域211内的箭头所示的方向移动，从而振膜2的自由端向上移动。其中，自由端为相对固定端的概念，振膜2与衬底1固定连接的一端为固定端，也即图8所示的左端。图8所示的振膜2的右端为自由端，自由端的振膜2悬空设置。
需要说明的是，第一电极层22与第二电极层23分别与外界电源电连接，第一电极层22与第二电极层23独立与电源连接。相比现有技术中，两层压电层21之间的电极共享，本申请中第一电极层22与第二电极层23相对独立，因此二者可以电学连接成差分信号输出，以提升压电MEMS换能器6的灵敏度、信噪比SNR、和声学过载点AOP等重要性能。
图9为振膜2发生形变后的简化示意图。参照图9，可以根据以下公式计算振膜2的振幅：
H＝R(1-cos(θ))＝Rθ2/2；
θ＝L1/R＝L2/(R+d)；
(R+d)θ-Rθ＝L1∈；
R＝d/∈；
H＝L12∈/(2d)。
其中：H为压电层的第一区域211的形变量，也即压电层的第一区域 211的振幅；
R为第一区域211的压电层发生形变后的曲率半径；
d为第一区域211与第二区域212的压电层之间的距离；
θ为第一区域211/第二区域212的压电层发生形变后的弧度；
∈为第一区域211与第二区域212的压电层应变差异；
L1为第一区域211的压电层的长度，L2为第二区域212的压电层的长度。
具体来说，例如压电层21采用PZT材料，施加的电压为±2.5V/um，L1＝200um，d＝1um，∈＝1e-3，此时H＝20um。
又例如，压电层21采用AlN材料，施加的电压为±15V/um，L1＝300um，d＝0.5um，∈＝1e-4，此时H＝9um。
本申请实施例中，所述第一区域211与第二区域212之间设置有第一间隙213，所述第一间隙213贯穿所述振膜2且与所述背腔11连通。
参照图4-图7，第一间隙213设置于第一区域211与第二区域212之间，用于将压电层21的第一区域211与第二区域212分隔开，使得第一区域211与第二区域212的压电层21的固定端(也即图5的左端)分别与衬底1固定连接，而第一区域211与第二区域212的压电层21的自由端(图5的右端)之间通过中部区域210连接。
参照图8，当压电层21的极化方向相同，且对压电层21的第一区域211与第二区域212施加方向相反的电压时，压电层21的第一区域211发生膨胀，压电层21的第二区域212发生收缩。本申请通过在第一区域211与第二区域212之间设置第一间隙213，使得压电层21的第一区域211及第二区域212发生形变时，压电层21的第一区域211与第二区域212减少相互之间的反作用力，使得二者共同配合实现压电层21的自由端(图5的右端)的形变，也即振膜2的振动，提高振膜2振动的灵敏性及精确度，进而提升压电MEMS换能器6的灵敏度、信噪比SNR、和声学过载点AOP等重要性能。
本申请实施例中，所述振膜2还包括中部区域210，所述第一区域211及所述第二区域212远离所述衬底1的一端通过所述中部区域210连接。
其中，参照图2-图3，中部区域210为振膜2的中心位置对应的范围，中部区域210的范围大小可以根据实际需求进行调整。第一区域211与第二区域212通过中部区域210实现一体连接。
本申请实施例中，所述振膜2包括多个膜瓣3，任两个相邻的所述膜瓣3之间设置有第二间隙24，所述第二间隙24穿过所述中部区域210且与所述背腔11连通。
当振膜2面积过大时，一整块振膜2的面内应力过大，影响振膜2的振动效率及灵敏度。因此本申请中的振膜2包括多个膜瓣3。
其中，膜瓣3由振膜2切割而成，任意两个相邻的膜瓣3之间设置有第二间隙24，第二间隙24穿过中部区域210且与背腔11连通，第二间隙24贯穿第二电极层23、压电层21以及第一电极层22。
本申请实施例中，所述膜瓣3设置为四个；
每个所述膜瓣3呈三角形，且四个所述膜瓣3两两对称设置形成矩形压电悬臂膜；或者，
每个所述膜瓣3呈扇形，且四个所述膜瓣3围合形成圆形压电悬臂膜。
也就是说，参照图2，振膜2整体设置为矩形，振膜2包括四个膜瓣3，每个膜瓣3呈三角形。
或者参照图3，振膜2整体设置为圆形，振膜2包括四个膜瓣3，每个膜瓣3呈扇形。
其中，相邻的膜瓣3之间形成有第二间隙24，每个膜瓣3的第一区域211与第二区域212之间形成有第一间隙213。
本申请还公开了一种用于如上所述的压电MEMS换能器的加工方法，其中图10主要展示了第一区域211的加工过程。本申请公开的加工方法包括以下步骤：
S1，提供衬底1，参照图10，以中部区域210为基准在其周侧形成第一制作区214，在所述第一制作区214的外侧形成第二制作区(图10中未示出)；其中，所述第一制作区214与所述第二制作区在所述衬底1的同一侧具有不同的高度位置。如图10所示，第一制作区214的高度低于第二制作区的高度。
其中，衬底1采用Si或者PolySi。在形成第一区域211时，可以采用RIE或湿法蚀刻到硅中，形成凹陷的第一制作区214，第一制作区214的外侧形成第二制作区。或者采用LOCOS工艺，也即在衬底1上进行局部氧化，并由SiO2/Si3N4掩蔽，然后再去除SiO2/Si3N4，从而形成凹陷的第一制作区214，第一制作区214的外侧形成第二制作区。
S2，在所述衬底1上形成牺牲层4，并在所述牺牲层4的表面分别制作出第一层的第一电极层22及第二电极层23，其中，如图10所示，所述第一电极层22位于所述第一制作区214内。所述第二电极层23位于所述第二制作区内(图10中未示出)。其中，牺牲层4可以采用例如SiO2。
S3，在所述牺牲层4上形成压电层21，所述压电层21包括与所述第一制作区214对应的第一区域211及与所述第二制作区对应的第二区域212，并使所述第一电极层22结合在所述第一区域211，所述第二电极层23结合在所述第二区域212。
压电层21可以采用AlN或PZT材料。第一电极层22及第二电极层23的材料根据压电层21材料进行选择。
例如当压电层21采用AlN时，第一电极层22及第二电极层23采用的钼；当压电层21采用PZT材料时，第一电极层22及第二电极层23采用铂。
S4，在所述第一区域211背离所述牺牲层4的表面制作另一层所述第一电极层22，及在所述第二区域212背离所述牺牲层4的表面制作另一层所述第二电极层23。压电层21、两层第一电极层22以及第二电极层23形成振膜2。根据需要在振膜2上刻蚀形成多个第二间隙24，从而将振膜2分隔为多个膜瓣3。此外，对每个膜瓣3进行刻蚀形成第一间隙213，第一间隙213将第一区域211与第二区域212分隔开。
S5，在两层第一电极层22的表面形成焊盘。同时，如图10所示，在两层所述第二电极层23的表面形成焊盘5。
S6，在所述衬底1背离所述压电层21的一侧形成背腔11，并去除背腔11对应的牺牲层4，得到压电MEMS换能器6。
其中，可以采用光刻和DRIE蚀刻穿过硅衬底1得到背腔11。可以采 用RIE干法蚀刻和湿法蚀刻去除牺牲层4。
本申请还公开了一种封装结构，包括背板7以及设置于所述背板7上的外壳8，以及如上所述的压电MEMS换能器6；其中，
所述背板7开设有背声孔71，所述背声孔71与所述背腔11连通。
参照图11-图13，压电MEMS换能器6放置于背板7上，背板7上开设有背声孔71，背声孔71与背腔11连通，便于实现声音的传输。外壳8罩设于压电MEMS换能器6的外周，且与背板7连接，实现对压电MEMS换能器6的保护。
本申请实施例中，所述外壳8开设有声孔81。
参照图11，声孔81可以设置于外壳8与第一间隙213相对的一侧。当然，参照图12，声孔81也可以设置于外壳8的侧壁。本申请对声孔81的开设位置不做限定。
需要说明的是，参照图13，本申请实施例中设置有两个压电MEMS换能器6，且两个压电MEMS换能器6之间通过电学及声学方式并联，可以提高多个压电MEMS换能器6之间的一致性。
当然，压电MEMS换能器6还可以设置有三个或更多，本申请对压电MEMS换能器6的数量不做限定，只需将多个压电MEMS换能器6进行电学及声学方式的并联即可。
本申请还提供了一种电子设备，包括如上所述的封装结构。
其中，电子设备可以为头戴显示设备、智能手表、手机等。
虽然已经通过例子对本申请的一些特定实施例进行了详细说明，但是本领域的技术人员应该理解，以上例子仅是为了进行说明，而不是为了限制本申请的范围。本领域的技术人员应该理解，可在不脱离本申请的范围和精神的情况下，对以上实施例进行修改。本申请的范围由所附权利要求来限定。

Claims (11)

  1. 一种压电MEMS换能器，其特征在于，包括：
    衬底(1)，所述衬底(1)上设置有背腔(11)；以及
    振膜(2)，所述振膜(2)设置于所述衬底(1)上且覆盖所述背腔(11)，所述振膜(2)包括压电层(21)；
    所述压电层(21)包括第一区域(211)以及第二区域(212)，所述第二区域(212)设置在所述第一区域(211)的至少一侧，所述第一区域(211)与所述第二区域(212)在第一方向上错位设置，且所述第一区域(211)与所述第二区域(212)在第二方向上间隔设置，其中第一方向为所述压电MEMS换能器的高度方向，所述第二方向与所述第一方向垂直；
    所述第一区域(211)及所述第二区域(212)的一端与所述衬底(1)固定连接，且二者远离所述衬底(1)的一端相互连接；
    所述第一区域(211)相对的两个表面上分别设有第一电极层(22)，所述第二区域(212)相对的两个表面上分别设有第二电极层(23)。
  2. 根据权利要求1所述的压电MEMS换能器，其特征在于，在对所述压电MEMS换能器(6)施加电压的情况下，所述第一区域(211)及所述第二区域(212)的伸缩方向相反。
  3. 根据权利要求1所述的压电MEMS换能器，其特征在于，所述第一区域(211)及所述第二区域(212)的极化方向相同；
    所述第一电极层(21)与所述第二电极层(22)连接的电压相反。
  4. 根据权利要求1所述的压电MEMS换能器，其特征在于，所述第一区域(211)与第二区域(212)之间设置有第一间隙(213)，所述第一间隙(213)沿厚度方向贯穿所述振膜(2)且与所述背腔(11)连通。
  5. 根据权利要求1所述的压电MEMS换能器，其特征在于，所述振膜(2)还包括中部区域(210)，所述第一区域(211)及所述第二区域(212)远离所述衬底(1)的一端通过所述中部区域(210)连接。
  6. 根据权利要求5所述的压电MEMS换能器，其特征在于，所述振膜(2)包括多个膜瓣(3)，任两个相邻的所述膜瓣(3)之间设置有第二间 隙(24)，所述第二间隙(24)穿过所述中部区域(210)且与所述背腔(11)连通。
  7. 根据权利要求6所述的压电MEMS换能器，其特征在于，所述膜瓣(3)设置为四个；
    每个所述膜瓣(3)呈三角形，且四个所述膜瓣(3)两两对称设置形成矩形压电悬臂膜；或者，
    每个所述膜瓣(3)呈扇形，且四个所述膜瓣(3)围合形成圆形压电悬臂膜。
  8. 一种压电MEMS换能器的加工方法，其特征在于，包括以下步骤：
    提供衬底(1)，以中部区域(210)为基准在其周侧形成第一制作区(214)，在所述第一制作区(214)的外侧形成第二制作区；其中，所述第一制作区(214)与所述第二制作区在所述衬底(1)的同一侧具有不同的高度位置；
    在所述衬底(1)上形成牺牲层(4)，并在所述牺牲层(4)的表面分别制作第一层的第一电极层(22)及第二电极层(23)，所述第一电极层(22)位于所述第一制作区(214)内，所述第二电极层(22)位于所述第二制作区内；
    在所述牺牲层(4)上形成压电层(21)，所述压电层(21)包括与所述第一制作区(214)对应的第一区域(211)及与所述第二制作区对应的第二区域(212)，并使所述第一电极层(22)结合在所述第一区域(211)，所述第二电极层(23)结合在所述第二区域(212)；
    在所述第一区域(211)背离所述牺牲层(4)的表面制作另一层所述第一电极层(22)，及在所述第二区域(212)背离所述牺牲层(4)的表面制作另一层所述第二电极层(23)，压电层(21)、第一电极层(22)及第二电极层(23)形成振膜(2)，刻蚀所述振膜(2)形成多个膜瓣(3)，并在每个膜瓣(3)的第一区域(211)与第二区域(212)之间形成第一间隙(213)；
    在两层所述第一电极层(22)及第二电极层(23)的表面分别形成焊盘(5)；
    在所述衬底(1)背离所述振膜(2)的一侧形成背腔(11)，并去除背腔(11)对应的牺牲层(4)，得到压电MEMS换能器(6)。
  9. 一种封装结构，其特征在于，包括背板(7)以及设置于所述背板(7)上的外壳(8)，以及权利要求1-7任意一项所述的压电MEMS换能器(6)；其中，
    所述背板(7)开设有背声孔(71)，所述背声孔(71)与所述背腔(11)连通。
  10. 根据权利要求9所述的封装结构，其特征在于，所述外壳(8)开设有声孔(81)。
  11. 一种电子设备，其特征在于，包括权利要求9-10任一项所述的封装结构。
PCT/CN2023/121667 2022-10-27 2023-09-26 压电mems换能器及其加工方法、封装结构及电子设备 WO2024087998A1 (zh)

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Citations (4)

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Publication number Priority date Publication date Assignee Title
CN108419189A (zh) * 2018-01-15 2018-08-17 美律电子(深圳)有限公司 压电传感器
CN210609696U (zh) * 2019-09-09 2020-05-22 安徽奥飞声学科技有限公司 一种mems结构
CN212086492U (zh) * 2020-07-03 2020-12-04 安徽奥飞声学科技有限公司 一种mems结构
JP2021197513A (ja) * 2020-06-17 2021-12-27 新日本無線株式会社 圧電素子

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108419189A (zh) * 2018-01-15 2018-08-17 美律电子(深圳)有限公司 压电传感器
CN210609696U (zh) * 2019-09-09 2020-05-22 安徽奥飞声学科技有限公司 一种mems结构
JP2021197513A (ja) * 2020-06-17 2021-12-27 新日本無線株式会社 圧電素子
CN212086492U (zh) * 2020-07-03 2020-12-04 安徽奥飞声学科技有限公司 一种mems结构

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