WO2022048382A1 - Structure mems - Google Patents

Structure mems Download PDF

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Publication number
WO2022048382A1
WO2022048382A1 PCT/CN2021/110434 CN2021110434W WO2022048382A1 WO 2022048382 A1 WO2022048382 A1 WO 2022048382A1 CN 2021110434 W CN2021110434 W CN 2021110434W WO 2022048382 A1 WO2022048382 A1 WO 2022048382A1
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WO
WIPO (PCT)
Prior art keywords
electrode layer
mems structure
substrate
layer
piezoelectric
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Application number
PCT/CN2021/110434
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English (en)
Chinese (zh)
Inventor
李冠华
刘端
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安徽奥飞声学科技有限公司
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Publication of WO2022048382A1 publication Critical patent/WO2022048382A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R19/00—Electrostatic transducers
    • H04R19/01—Electrostatic transducers characterised by the use of electrets
    • H04R19/016—Electrostatic transducers characterised by the use of electrets for microphones

Definitions

  • the present application relates to the technical field of micro-electromechanical systems, and in particular, to a MEMS structure and a method for forming the same.
  • MEMS Micro-Electro-Mechanical Systems, that is, Micro-Electro-Mechanical Systems
  • microphones mainly include two types: capacitive and piezoelectric.
  • MEMS piezoelectric microphones are prepared by using micro-electromechanical system technology and piezoelectric thin-film technology. Due to the use of semiconductor planar technology and bulk silicon processing technologies, they are small in size, small in volume, and good in consistency. At the same time, compared with the condenser microphone, it has the advantages of no bias voltage, large operating temperature range, dustproof, waterproof, etc., but its sensitivity is relatively low, which restricts the development of MEMS piezoelectric microphones.
  • the present application proposes a MEMS structure, which can effectively improve the sensitivity.
  • a MEMS structure comprising:
  • the second part of the piezoelectric layer is formed above the second electrode layer
  • first electrode layer and the first part are symmetrical with the second part and the third electrode layer with the second electrode layer as a neutral plane.
  • the thickness of the middle region of the diaphragm is greater than the thickness of the peripheral region of the diaphragm, which is beneficial to release the stress at the connection between the piezoelectric layer and the substrate, and reduces the charge in the peripheral region and the middle region. and the resulting reduction in sensitivity.
  • the MEMS structure provided by the present application increases the sensitivity.
  • FIG. 1 shows a schematic perspective view of a MEMS structure provided according to some embodiments
  • FIG. 2 illustrates a cross-sectional perspective view of a MEMS structure provided in accordance with some embodiments
  • FIG. 3 illustrates a top view of a MEMS structure provided in accordance with some embodiments
  • FIG. 4 shows a schematic diagram of connection of electrode layers of a MEMS structure provided according to some embodiments
  • FIG. 5 shows the sensitivity frequency response curve of the MEMS structure in FIG. 1 .
  • a MEMS structure that can be used in sensors or actuators, such as microphones, speakers, hydrophones.
  • the MEMS structure may include a piezoelectric MEMS microphone that converts acoustic energy into electrical energy.
  • the MEMS structure includes a laminated substrate 10, a first electrode layer 20, a first portion 31 of a piezoelectric layer 30, a second electrode layer 40, a second portion 32 of the piezoelectric layer 30, and a third electrode layer 50 .
  • the substrate 10 has a cavity 11 .
  • the first electrode layer 20 is suspended in the cavity 11 .
  • the first portion 31 of the piezoelectric layer 30 is formed over the first electrode layer 20 and is connected to the substrate 10 .
  • the second electrode layer 40 is formed over the first portion 31 .
  • the second portion 32 of the piezoelectric layer 30 is formed over the second electrode layer 40 .
  • the third electrode layer 50 is formed over the second portion 32 .
  • the first electrode layer 20 and the first part 31 are symmetrical with the second part 32 and the third electrode layer 50 with the second electrode layer 40 as the neutral plane. In other words, the first electrode layer 20 and the first portion 31 are symmetrical in the thickness direction with respect to the second electrode layer 40 and the second portion 32 and the third electrode layer 50 .
  • the output voltage of the MEMS structure is improved by such a bimorph structure.
  • the MEMS structure further includes an isolation layer (not shown in the figure), and the isolation layer is formed at the position of the upper surface and the lower surface of the second electrode layer 40 .
  • isolation layers are formed at the locations of the upper surface of the first electrode layer 20 and the lower surface of the third electrode layer 50 . Providing the isolation layer can avoid short circuits between the first electrode layer 20 , the second electrode layer 40 and the third electrode layer 50 .
  • the top surface of the first electrode layer 20 is located below the top surface of the substrate 10
  • the bottom surface of the second electrode layer 40 is located above the top surface of the substrate 10
  • the vertical projection area of the first electrode layer 20 is located in the cavity 11 .
  • the second portion 32 is formed over the second electrode layer 40 and the first portion 31 .
  • the top surface of the peripheral region of the second portion 32 is lower than the top surface of the middle region of the second portion 32
  • the peripheral region of the second portion 32 is connected to the substrate 10
  • the third electrode layer 50 is formed in the middle region of the second portion 32 above.
  • the thickness of the middle region of the diaphragm is greater than the thickness of the peripheral region of the diaphragm, which is beneficial to release the stress at the connection between the piezoelectric layer 30 and the substrate 10 and reduce the charge neutralization in the peripheral region and the middle region. decreased sensitivity.
  • the MEMS structure provided by the present application increases the sensitivity.
  • the first electrode layer 20 , the second electrode layer 40 and the third electrode layer 50 have corresponding at least two equal divisions. In some embodiments, the first electrode layer 20 , the second electrode layer 40 and the third electrode layer 50 have corresponding 12 equal divisions.
  • the second electrode layer 40 is drawn out through a first wire (not shown in the figure) as a terminal of the MEMS structure .
  • the first electrode layer 20 and the third electrode layer 50 are connected, they are connected to the second electrode layer 40 in the second equal division.
  • the first equal division is adjacent to the second equal division, and multiple adjacent equal divisions are repeatedly connected.
  • the first electrode layer 20 and the third electrode layer 50 in the twelfth equal division are connected as another terminal of the MEMS structure. Through this electrode connection method, the output charge can be increased without changing the output voltage, thereby increasing the output energy of the MEMS structure.
  • the material of the substrate 10 includes the material of silicon or any suitable silicon-based compound or derivative (eg, silicon wafer, SOI, polysilicon on SiO2 /Si).
  • the substrate 10 may have various shapes, not limited to pentagons, hexagons, or other regular or irregular shapes.
  • the first electrode layer 20 may be formed by electron beam evaporation, magnetron sputtering process.
  • the first electrode layer 20 includes aluminum, gold, platinum, molybdenum, titanium, chromium and their composite films or other suitable materials.
  • the materials of the second electrode layer 40 and the third electrode layer 50 may be the same as or different from those of the first electrode layer 20 .
  • the piezoelectric layer 30 includes one or more layers of zinc oxide, aluminum nitride, organic piezoelectric films, lead zirconate titanate (PZT), perovskite piezoelectric films, or other suitable materials.
  • the piezoelectric layer 30 may be formed by a CVD process or a magnetron sputtering process or other suitable processes.
  • the cavity 11 may be formed by reactive ion etching or the like.
  • FIG. 5 represents the sensitivity frequency response curve for the specific dimensions and parameters of the structure shown in FIG. 1 .
  • the radius of the cavity 11 of the substrate 10 is 500 ⁇ m, and the radius of the center portion of the piezoelectric layer 30 and the electrode layer is 450 ⁇ m.
  • the thickness of the electrode layer is 100 nm, and the material is aluminum (Al).
  • the center thickness of the composite film is 1900 nm, and the edge thickness is 800 nm.
  • the piezoelectric material is aluminum nitride (AlN). It can be seen from the sensitivity frequency response curve that the sensitivity of the structure is above -42dB in the frequency range of 100-20000Hz, and it is very flat within 10kHz. This just gives a size parameter and material parameter, which can be adjusted at will according to different needs.
  • the thickness of the middle region of the diaphragm is greater than the thickness of the peripheral region of the diaphragm, thereby facilitating the connection between the release piezoelectric layer 30 and the substrate 10
  • the stress at the outer and middle regions reduces the chance of sensitivity reduction due to charge neutralization at the peripheral and intermediate regions.
  • the MEMS structure provided by the present application increases the sensitivity.

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

Abstract

La présente invention concerne une structure MEMS, comprenant : un substrat ayant une cavité; une première couche d'électrode qui est suspendue dans la cavité; une première partie d'une couche piézoélectrique formée au-dessus de la première couche d'électrode et connectée au substrat; une deuxième couche d'électrode formée au-dessus de la première partie; une deuxième partie de la couche piézoélectrique formée au-dessus de la deuxième couche d'électrode; et une troisième couche d'électrode formée au-dessus de la deuxième partie. La première couche d'électrode et la première partie sont symétriques par rapport à la deuxième partie et à la troisième couche d'électrode en prenant la deuxième couche d'électrode comme plan neutre. Dans la structure MEMS, l'épaisseur de la zone centrale d'une membrane est supérieure à l'épaisseur de la zone périphérique de la membrane, ce qui facilite la libération de la contrainte à l'endroit où la couche piézoélectrique est reliée au substrat et réduit la probabilité de réduction de la sensibilité causée par la neutralisation des charges dans la zone périphérique et la zone centrale.
PCT/CN2021/110434 2020-09-04 2021-08-04 Structure mems WO2022048382A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202010922526.0A CN111901736A (zh) 2020-09-04 2020-09-04 一种mems结构
CN202010922526.0 2020-09-04

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WO2022048382A1 true WO2022048382A1 (fr) 2022-03-10

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CN111901736A (zh) * 2020-09-04 2020-11-06 安徽奥飞声学科技有限公司 一种mems结构

Citations (6)

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US20150350792A1 (en) * 2008-06-30 2015-12-03 Karl Grosh Piezoelectric mems microphone
CN109319726A (zh) * 2017-07-31 2019-02-12 新加坡商格罗方德半导体私人有限公司 具有偏向控制的压电麦克风及其制造方法
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CN111146327A (zh) * 2019-12-25 2020-05-12 诺思(天津)微系统有限责任公司 单晶压电结构及其制造方法、单晶压电层叠结构的电子设备
CN111901736A (zh) * 2020-09-04 2020-11-06 安徽奥飞声学科技有限公司 一种mems结构
CN212324361U (zh) * 2020-09-04 2021-01-08 安徽奥飞声学科技有限公司 一种mems结构

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JP2010247295A (ja) * 2009-04-17 2010-11-04 Toshiba Corp 圧電ｍｅｍｓ素子及びその製造方法
JP6787553B2 (ja) * 2017-02-14 2020-11-18 新日本無線株式会社 圧電素子
CN110739931A (zh) * 2019-09-04 2020-01-31 深圳市汇芯通信技术有限公司 一种滤波器及其制备方法
CN110636421A (zh) * 2019-09-09 2019-12-31 安徽奥飞声学科技有限公司 一种mems结构及其制造方法
CN111017861A (zh) * 2019-10-14 2020-04-17 清华大学 基于逆压电效应的电容-悬臂梁微型式电场测量传感器件
CN110677795A (zh) * 2019-11-12 2020-01-10 安徽奥飞声学科技有限公司 一种mems结构

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150350792A1 (en) * 2008-06-30 2015-12-03 Karl Grosh Piezoelectric mems microphone
CN109319726A (zh) * 2017-07-31 2019-02-12 新加坡商格罗方德半导体私人有限公司 具有偏向控制的压电麦克风及其制造方法
CN111146327A (zh) * 2019-12-25 2020-05-12 诺思(天津)微系统有限责任公司 单晶压电结构及其制造方法、单晶压电层叠结构的电子设备
CN111146328A (zh) * 2019-12-31 2020-05-12 诺思(天津)微系统有限责任公司 单晶压电结构及具有其的电子设备
CN111901736A (zh) * 2020-09-04 2020-11-06 安徽奥飞声学科技有限公司 一种mems结构
CN212324361U (zh) * 2020-09-04 2021-01-08 安徽奥飞声学科技有限公司 一种mems结构

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