WO2020133352A1 - Capteur acoustique mems, microphone mems, et dispositif électronique - Google Patents

Capteur acoustique mems, microphone mems, et dispositif électronique Download PDF

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Publication number
WO2020133352A1
WO2020133352A1 PCT/CN2018/125351 CN2018125351W WO2020133352A1 WO 2020133352 A1 WO2020133352 A1 WO 2020133352A1 CN 2018125351 W CN2018125351 W CN 2018125351W WO 2020133352 A1 WO2020133352 A1 WO 2020133352A1
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WIPO (PCT)
Prior art keywords
diaphragm
mems
back plate
conductive layer
layer
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PCT/CN2018/125351
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English (en)
Chinese (zh)
Inventor
何宪龙
谢冠宏
邱士嘉
Original Assignee
共达电声股份有限公司
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Application filed by 共达电声股份有限公司 filed Critical 共达电声股份有限公司
Priority to PCT/CN2018/125351 priority Critical patent/WO2020133352A1/fr
Priority to CN201880028690.8A priority patent/CN110603819B/zh
Publication of WO2020133352A1 publication Critical patent/WO2020133352A1/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
    • H04R19/04—Microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
    • H04R2201/003—Mems transducers or their use

Definitions

  • the invention relates to the technical field of microphones, in particular to a MEMS sound sensor and its preparation method, MEMS microphone and electronic equipment.
  • MEMS Micro-Electro-Mechanical System
  • MEMS microphone is an electric energy transducer manufactured based on MEMS technology, which has the advantages of small size, good frequency response characteristics and low noise. With the miniaturization of electronic devices, MEMS microphones are more and more widely used in these devices.
  • the MEMS sound sensor is a key device in the MEMS microphone, and its performance directly affects the performance of the entire MEMS microphone. The sensitivity of the traditional MEMS sound sensor is low and cannot meet the user's use requirements.
  • a MEMS sound sensor a MEMS microphone, and an electronic device are provided.
  • a MEMS sound sensor for detecting sound through at least one of air sound pressure change and mechanical vibration includes:
  • a diaphragm which is disposed opposite to the back plate and has a gap with the back plate; the diaphragm and the back plate form a capacitor structure;
  • the connecting post includes a first end and a second end that are oppositely arranged; the first end of the connecting post is fixedly connected to the back plate; the second end of the connecting post is electrically connected to the middle region of the diaphragm To suspend the diaphragm on the backplane;
  • At least one mass is provided in the edge area of the diaphragm; an opening is provided on the back plate; the opening is used to expose the mass so that the mass exists between the mass and the back plate The gap, or the opening serves as an acoustic hole on the back plate.
  • a MEMS microphone includes a printed circuit board, a MEMS sound sensor provided on the printed circuit board, and an integrated circuit provided on the printed circuit board; the MEMS microphone uses the MEMS as described in any of the foregoing embodiments Sound sensor.
  • An electronic device includes a device body and a MEMS microphone provided on the device body; the MEMS microphone uses the MEMS microphone as described above.
  • FIG. 1 is a cross-sectional view of the MEMS sound sensor in the first embodiment.
  • FIG. 2 is a cross-sectional view of the MEMS sound sensor in the second embodiment.
  • FIG 3 is a cross-sectional view of the MEMS sound sensor in the third embodiment.
  • FIG. 4 is a cross-sectional view of the MEMS sound sensor in the fourth embodiment.
  • FIG. 5 is a schematic diagram of forming a second sub-portion in a mass in an embodiment.
  • FIG. 6 is a cross-sectional view of the MEMS sound sensor in the fifth embodiment.
  • FIG. 7 is a schematic diagram of the structure of the diaphragm in an embodiment.
  • FIG. 8 is a schematic structural diagram of a MEMS microphone in an embodiment.
  • FIG. 9 is a schematic structural view of a MEMS microphone in another embodiment.
  • FIG. 10 is a schematic structural diagram of a MEMS microphone in another embodiment.
  • FIG. 1 is a schematic structural diagram of a MEMS sound sensor in an embodiment.
  • the MEMS sound sensor can also be called a MEMS sensor or a MEMS chip.
  • the MEMS sound sensor is used to detect sound through at least one of air sound pressure change and mechanical vibration, that is, the MEMS sound sensor can detect sound air pressure change caused by sound, or by Vibration caused by sound or mechanical external force to achieve sound detection.
  • the vibration referred to in this case is exemplified by vibration of bones such as ear bones or other solids caused by sound or mechanical external force.
  • the MEMS sound sensor includes a back plate 100, a diaphragm 200, and a connecting post 300.
  • the back plate 100 may also be referred to as a back plate.
  • the diaphragm 200 is disposed opposite to the back plate 100, and a gap 10 is formed between the two.
  • the gap 10 is not filled with other substances and is an air gap.
  • the diaphragm 200 and the back plate 100 constitute a capacitor structure.
  • the shape of the diaphragm 200 is not particularly limited.
  • the diaphragm 200 may have a circular shape, a square shape, or the like.
  • the connecting post 300 includes a first end 300a and a second end 300b disposed oppositely. The first end 300a is fixedly connected to the backplane 100.
  • the second end 300b is connected to the middle region of the diaphragm 200, and is electrically connected to the diaphragm 200.
  • the connecting post 300 is connected to the diaphragm 200 through the second end 300b, thereby suspending the diaphragm 200 on the back plate.
  • the edge area around the diaphragm 200 after being suspended does not need other fixing structures to support and fix it, so that the sensitivity of the entire diaphragm 200 can be greatly improved to meet people's use requirements.
  • at least one mass 210 is provided in the edge area of the diaphragm 200.
  • the edge area is relative to the middle area, that is, the edge area is an area away from the connecting post 300.
  • an opening 110 is provided in the area of the back plate 100 corresponding to the mass 210 to expose and release the mass 210, and a gap 112 exists between the mass 210 and the back plate 100.
  • the air When sound changes the sound pressure of the air, the air will pass through the opening 110 on the back plate 100 and enter the gap 10 between the back plate 100 and the diaphragm 200 through the gap 112, so that the diaphragm 200 is at this air pressure or sound. Vibration occurs under the effect of pressure, or a change in air pressure below the diaphragm 200 directly pushes the diaphragm 200 to cause the diaphragm 200 to vibrate, and the capacitor structure will generate a changed capacitance to detect sound waves.
  • the changed capacitance signal can be processed through an ASIC (Application Specific Integrated Circuit) integrated circuit (IC) chip and the electrical signal after the acoustoelectric conversion is output.
  • ASIC Application Specific Integrated Circuit
  • the mass area 210 is provided in the edge area of the diaphragm 200, even a small air pressure change can generate a large torque, thereby causing the diaphragm 200 to generate more obvious vibration, greatly Improve the sensitivity of MEMS sound sensor.
  • the back plate 100 since air can enter directly through the opening 110 and enter the gap 112 between the mass 210 and the back plate 100 to cause vibration of the diaphragm 200, the back plate 100 may not have an acoustic hole, thereby making the back plate 100
  • the large electrode area ensures that the MEMS sound sensor has a high capacitance change, which further improves the sensitivity of the detection process.
  • the gap 112 between the mass 210 and the back plate 100 can be set as needed to minimize the damping effect that exists when air enters and exits the gap 10.
  • the above MEMS sound sensor directly or indirectly comes into contact with bones that conduct sound (such as ear bones, vocal cords, etc.) (usually the side where the diaphragm 200 is located close to the ear bones), the corresponding bones will mechanically vibrate during speech.
  • the mechanical vibration causes the diaphragm 200 to vibrate. Since the mass region 210 is provided in the edge area of the diaphragm 200, even a small mechanical vibration can cause the vibration of the diaphragm 200 to realize the detection of the sound, that is, the MEMS sound sensor has high sensitivity.
  • the MEMS sound sensor in this embodiment can work as a vibration sensor, so that when the user is in a noisy environment, it can be brought into contact with the human body's sound conduction tissue (such as the ear bones), by detecting the solid matter caused by the person when speaking Vibration realizes the detection of sound, and the entire detection process will not be disturbed by environmental noise, so that the entire MEMS sound sensor has a high signal-to-noise ratio.
  • the human body's sound conduction tissue such as the ear bones
  • the above MEMS sound sensor further includes a substrate 410 and a first insulating layer 430.
  • the substrate 410 may be a silicon substrate directly. It can be understood that the substrate 410 may also be other base structures, such as an SOI base.
  • a back hole 412 is formed on the substrate 410 so as to expose the lower surface of the diaphragm 200.
  • the first insulating layer 430 is used to achieve insulation between the backplane 100 and the substrate 410 while fixing the backplane 100 on the substrate 410.
  • the first insulating layer 430 surrounds the diaphragm 200.
  • the first insulating layer 430 may be a dielectric oxide layer, such as silicon dioxide.
  • a material layer 440 formed when the diaphragm 200 is prepared and a dielectric oxide layer 420 for isolating the material layer 440 and the substrate 410 are also formed on the substrate 410.
  • the diaphragm 200 may be made of single crystal silicon, polycrystalline silicon, silicon nitride, silicon-rich silicon nitride, silicon germanium compound (SiGe), metal, or the like.
  • the metal may be aluminum (Al), aluminum-copper alloy (AlCu), platinum (Pt), gold (Au), and the like. Therefore, any one of the foregoing materials may be used for the material layer 440.
  • the diaphragm 200 uses silicon nitride or silicon-rich silicon nitride as a material, a layer of conductive material needs to be added as an electrode of the diaphragm 200.
  • the diaphragm 200 is completely isolated from the substrate 410, that is, the diaphragm 200 is completely suspended and connected by the connecting post 300, without using other fixing structures to fix the periphery of the diaphragm 200.
  • the periphery of the suspended diaphragm 200 is suspended, which can release residual stress, so that the diaphragm 200 has higher sensitivity.
  • the diaphragm 200 is doped or ion implanted as necessary.
  • the doping may be N-type doping or P-type doping, so that the diaphragm 200 has better conductivity.
  • doping or ion implantation is also required to make the backplane have better conductivity.
  • the mass 210 in the diaphragm 200 includes at least one of the first part 212 and the second part 214.
  • the first portion 212 is formed on the upper surface of the diaphragm 200 and the second portion 214 is formed on the lower surface of the diaphragm 200.
  • the side of the diaphragm 200 facing the back plate 100 is the upper surface, and the side away from the back plate 100 is the lower surface.
  • the mass block 210 may be selectively set according to needs, for example, only the first part 212 or the second part 214 may be set, or may be set at the same time.
  • the quality of the first part 212 and the second part 214 can be adjusted, so as to achieve the quality adjustment of the entire mass 210, and thus the adjustment of the sensing frequency band of the entire MEMS vibration sensor.
  • the frequency detection range of the MEMS sound sensor is 20 Hz to 20 KHz.
  • the mass 210 includes both the first part 212 and the second part 214.
  • the backplane 100 includes a first conductive layer 130 and a protective layer covering the first conductive layer 130.
  • the backplane 100 includes a first protective layer 120, a first conductive layer 130 and a second protective layer 140 that are sequentially stacked.
  • the first protective layer 120 is located on the side of the back plate 100 close to the diaphragm 200.
  • the first conductive layer 130 is a patterned layer.
  • the second protective layer 140 is formed on the first protective layer 120 and completely covers the first conductive layer 130, that is, the first conductive layer 130 is surrounded by the first protective layer 120 and the second protective layer 140.
  • the opening 110 penetrates the entire first protective layer 120 and the second protective layer 140, so that the external sound signal is transmitted to the gap 10 through the gap 112, and the diaphragm 200 vibrates; or the external voice signal passes through the diaphragm 200 After passing through the gap 10, it then passes through the opening 110.
  • Both the first protective layer 120 and the second protective layer 140 are passivation layers, ensuring that the first conductive layer 130 disposed in the two layers can be isolated from corrosive gases in the air, and can avoid backing in bad environments such as humid environments Leakage between the board 100 and the diaphragm 200.
  • the first protective layer 120 and the second protective layer 140 may be silicon nitride (silicon nitride) or silicon-rich silicon nitride (si-rich silicon nitride).
  • the surfaces of the first protective layer 120 and the second protective layer 140 must be or processed to be non-hydrophilic, that is, the surfaces of the first protective layer 120 and the second protective layer 140 are both non-hydrophilic surfaces .
  • a very thin silicon oxide material is not completely removed, it will be attached to the protective layer, which will also cause the protective layer to be hydrophilic (hydrophilic); or the protective layer silicon nitride (silicon nitride), silicon rich Silicon nitride (si-rich silicon nitride) itself has a certain degree of hydrophilicity after the semiconductor process is completed.
  • silicon nitride silicon nitride
  • silicon rich Silicon nitride silicon rich Silicon nitride
  • the patterned first conductive layer 130 includes a back plate electrode 132 and a lead-out electrode 134 of the diaphragm 200.
  • the first conductive layer 130 may be a polysilicon layer, a silicon germanium compound (SiGe) layer, or a metal layer.
  • the metal of the metal layer may be aluminum (Al), aluminum-copper alloy (AlCu), platinum (Pt), gold (Au), or the like.
  • the materials of the first conductive layer 130 and the diaphragm 200 are both polysilicon (polySi).
  • a backplane pad 510 and a diaphragm pad 520 are also formed on the MEMS sound sensor, as shown in FIG. 1.
  • the back plate pad 510 is formed on the back plate electrode 132, and the diaphragm pad 520 is formed on the extraction electrode 134, so as to realize the electrical connection between the back plate electrode and the diaphragm 200 and the outside, respectively.
  • the first portion 212 of the mass 210 and the first conductive layer 130 of the backplane 100 are formed in the same process step, that is, by protecting the first insulating layer 430 and the first protection formed above the diaphragm 200
  • the layer 120 is etched until the diaphragm 200 is stopped, and then the conductive layer is filled (for example, filled with polysilicon) to form the conductive layer for preparing the first part 212 and the back plate 100 in one piece. Due to the need to fill the previously etched grooves, the thickness of the conductive layer formed at this time is thick, and the formed conductive layer needs to be etched to the CMP (Chemical Mechanical Mechanical Polishing process) or silicon etching process The thickness of the desired backplane electrode.
  • CMP Chemical Mechanical Mechanical Polishing process
  • the first portion 212 and the first conductive layer 130 are an integral structure, and an opening 110 needs to be formed in the back plate electrode layer through an etching process to separate the first conductive layer 130 from the first portion 212, and then form the mass 210 and The gap 112 between the back plates 100.
  • the gap 112 can be customized, and the gap 112 is large, which can reduce air damping.
  • the conductive layer may be generated according to the thickness of the first portion 212 of the mass 210, and then the conductive layer is etched to the thickness of the back plate electrode, and the first portion 212 is separated from the back plate 100. At this time, the height of the first portion 212 may be lower than the plane where the conductive layer is located, as shown in FIG. 2.
  • an acoustic hole 150 may be formed, as shown in FIG. 3, so that the air damping may be further reduced.
  • the second portion 214 and the diaphragm 200 are formed in the same process step. Specifically, before forming the diaphragm 200, the dielectric oxide layer 420 in the corresponding region is partially etched, or completely etched or even etched onto the silicon substrate of the substrate 410. The end point of the etching process can be determined according to the quality of the second part 214. After the etching is completed, a material layer for preparing the diaphragm 200 is formed above the substrate 410, and the etching area is filled during the forming process, thereby forming the diaphragm 200 each having the second portion 214.
  • the second part 214 includes a first sub-part 214a and a second sub-part 214b, as shown in FIG.
  • the first sub-portion 214a is the same as the method for forming the second portion 214 in the previous embodiment, and is formed in the same process step as the diaphragm 200.
  • the second sub-portion 214b is obtained by etching the substrate 410, see FIG. 5.
  • the substrate 410 is etched with a mask plate that defines the shape of the mass 210, and a protrusion 414 having a mass shape is formed on the corresponding position on the substrate 410, and then the entire region of the diaphragm 200 is etched synchronously The etching stops until the dielectric oxide layer 420 is etched, thereby forming the second sub-portion 214b of the mass 210.
  • the second sub-part 214b and the first sub-part 214a and the diaphragm 200 and the first part 212 form an integral body.
  • the mass 210 has a larger mass and is located in the edge area, thereby making the entire MEMS sound sensor have higher sensitivity .
  • the mass 210 formed in the MEMS sound sensor includes only the second part 214. That is, in this embodiment, the upper surface of the diaphragm 200 does not need to form a mass, and there is no need to provide an opening for the exposed mass on the back plate 100. At this time, the opening 110 formed in the back plate 100 serves as the sound hole of the back plate 100 to reduce the damping, as shown in FIG. 6.
  • the diaphragm 200 includes a plurality of diaphragms 220 that move independently of each other, as shown in FIG. 7.
  • 7 is a schematic diagram of the structure of the diaphragm.
  • the diaphragm 200 includes four symmetrically distributed diaphragms 220, and each diaphragm 220 has the same structure, that is, the same mass 210 is formed thereon.
  • the sensitivity in the vibration detection process can be further improved.
  • at least two of the diaphragms 220 on the diaphragm 200 have different structures, that is, they are asymmetrically distributed.
  • the masses 210 are set on different diaphragms 220, and the masses 210 on each diaphragm 220 may be the same or different. It is set to the frequency detection range corresponding to the diaphragm 220, for example, the frequency detection range is 20Hz ⁇ 20KHz.
  • the diaphragm 200 may be provided with a first diaphragm corresponding to low frequency, a second diaphragm corresponding to intermediate frequency, and a third diaphragm corresponding to high frequency, so that the first diaphragm of low frequency may be used to achieve 100 Hz ⁇ 1KHz frequency detection, the second module to realize the frequency detection of 1KHz ⁇ 10KHz, and the third diaphragm realizes the frequency detection of 10KHz ⁇ 20KHz.
  • different diaphragms 220 correspond to different frequency bands, so that the MEMS sound sensor has a wider frequency band detection range, and meets the user's detection requirements for multiple frequency bands.
  • an insulating layer is provided between the diaphragms 220 to achieve electrical insulation between the diaphragms 220, so that the diaphragms 220 can independently detect the sound of the corresponding frequency band.
  • Each diaphragm 220 is led out to the corresponding lead-out electrode 134 on the back plate 100 through the connecting post 300 to be connected to the corresponding pad through the lead-out electrode 134.
  • the connecting post 300 also includes a plurality of mutually insulated lead-out areas, and a plurality of lead-out electrodes 134 are also provided in the back plate 100 to lead each diaphragm 220 to the corresponding pad, that is, each film at this time
  • the slice 220 has mutually independent circuit paths.
  • each diaphragm 220 may also be led out using the same circuit path.
  • the membrane 220 responsible for sensing the corresponding frequency band forms a capacitance with the backplane 100 to generate a variable capacitance change signal, so that the ASIC chip processes the change signal accordingly.
  • the capacitance change signal is small, and the ASIC does not process it at this time.
  • part of the material of the second end 300b is embedded in the diaphragm 200.
  • the second end 300b is electrically connected to the diaphragm 200, so that the connecting post 300 can lead out the electrode where the diaphragm 200 is located through the extraction electrode 134.
  • the at least partial material embedding of the second end 300b means that a part of the layer structure on the connecting post 300 is embedded in the diaphragm 200 or all the layer structures on the connecting post 300 are embedded in the diaphragm 200.
  • the connecting post 300 may be embedded inside the diaphragm 200 or embedded in and penetrate the diaphragm 200.
  • the second end 300b of the connecting post 300 may be partially not embedded, but partially embedded in the diaphragm 200 or may be embedded in and penetrate the diaphragm 200.
  • the second ends 300b of the connecting post 300 may all be embedded, but part of them are embedded in the diaphragm 200, and the rest are embedded in and penetrate the diaphragm 200. It can be understood that the second end 300 b of the connecting post 300 may also be completely embedded in the diaphragm 200 or completely embedded in and penetrate the diaphragm 200.
  • the shape, structure, and number of the connecting posts 300 are not particularly limited.
  • the cross section of the connecting column 300 may be circular, rectangular, elliptical, semicircular, etc., as long as it can play a role of supporting and hanging.
  • the connection column 300 is cylindrical as an example.
  • the number of connecting posts 300 may be one, or two or more.
  • the number of the connecting posts 300 can also be determined according to the size of the MEMS sound sensor. For example, as the size of the MEMS sound sensor increases, the number of the connecting posts 300 is increased or the cross-sectional area of the connecting posts 300 is adjusted.
  • the connecting post 300 suspends the diaphragm 200 on the back plate 100 by embedding the diaphragm 200, so as to achieve relative fixing between the diaphragm 200 and the back plate 100. Since the connecting post 300 is embedded in the diaphragm 200, the connecting post 300 has a vertical bonding area and a horizontal bonding area with the diaphragm 200, that is, the bonding area between the connecting post 300 and the diaphragm 200 is increased, and it has better mechanical properties.
  • the connection strength can improve the performance of the diaphragm 200 against mechanical impact forces such as blowing and falling, rolling, and roller testing.
  • there is no need for other fixing structures to support and fix the vibrating membrane 200 around the suspension so that the sensitivity of the entire vibrating membrane 200 can be greatly improved to meet people's use requirements.
  • the mechanical sensitivity of the diaphragm is susceptible to the residual stress of the semiconductor process.
  • Individual MEMS sound sensors are prone to variability, resulting in decreased sensitivity consistency, and even uneven distribution of diaphragm stress, causing instability (bi- The possibility of deformation occurs, which makes the final MEMS microphone acoustic performance unstable, even exceeding the specifications.
  • the MEMS sound sensor in this application can have a high mechanical strength and can improve the resistance to various mechanical impact forces.
  • the suspension type is used to strengthen the coupling strength of the connecting post 300 and the diaphragm 200, so that the diaphragm 200 can freely Complying with the external mechanical impact force, the diaphragm 200 becomes a flexible diaphragm and does not resist the external mechanical impact force.
  • the diaphragm 200 of the present application has no peripheral fixed points or fixed points (diaphragm), which means that the periphery of the diaphragm is completely cut.
  • This design can release the residual stress caused by the semiconductor process and greatly improve the performance of the MEMS sound sensor. Performance and manufacturability, relax manufacturing tolerance tolerance of manufacturing, and make manufacturing yield higher.
  • some spring-like connection structures may also be provided around the diaphragm 200 to connect with the substrate 410. It can be understood that the structure in which the connecting post 300 in this embodiment is embedded in the diaphragm 200 to suspend the diaphragm 200 to the back plate 100 is not limited to the structure shown in FIG. 1, and can also be applied to other structures such as having a double back plate or double Diaphragm MEMS sound sensor.
  • the connecting post 300 is located at the center of the diaphragm 300.
  • the diaphragm 200 is circular
  • the connecting post 300 is a cylinder, that is, the central axis of the connecting post 300 intersects the center of the circle of the diaphragm 200.
  • connecting posts 300 there may be multiple connecting posts 300.
  • the plurality of connecting pillars 300 are symmetrically distributed about the center of the diaphragm 200, so that the force of the diaphragm 200 is uniform everywhere.
  • a plurality of connecting posts 300 are all disposed within a half of the distance from the center of the diaphragm 200 to the edge, so as to ensure better support performance for the diaphragm 200 and ensure that the diaphragm 200 has Higher sensitivity.
  • the depth of the embedded diaphragm 200 in the connecting post 300 is greater than or equal to one-third of the thickness of the diaphragm 200, so that the connecting post 300 has a vertical bonding area and a horizontal bonding area with the diaphragm 200, that is,
  • the joint area between the connecting column 300 and the diaphragm 200 is increased to ensure that the diaphragm 200 and the connecting column 300 are more resistant to external mechanical shocks, and meet the anti-blow and anti-dropping, rolling and roller resistance of the diaphragm 200 Test the performance requirements of mechanical impact forces.
  • the connection pillar 300 includes a second insulating layer 310 and a second conductive layer 320 that are spaced apart from each other. Since the connecting post 300 is a cylinder, the shapes of the second insulating layer 310 and the second conductive layer 320 projected on the diaphragm 200, that is, their top views are all ring structures. The number of layers of the second insulating layer 310 and the second conductive layer 320 can be set as needed, usually from the center of the connecting post 300 are the second insulating layer 310, the second conductive layer 320, the second insulating layer 310... until the most The second conductive layer 320 of the outer layer. In the embodiment shown in FIG.
  • the second conductive layer 320 and the second insulating layer 310 are both two layers.
  • the second insulating layer 310 is prepared in the same process as the first insulating layer 430 above the substrate 410 during the preparation.
  • the first insulating layer 430 and the Second insulating layer 310 are the same, and both are dielectric oxide layers.
  • the first end of the second conductive layer 320 is integrally formed with the extraction electrode 134 and electrically connected.
  • the second end of the second conductive layer 320 is embedded in the diaphragm 200.
  • the second end of the second conductive layer 320 may be embedded in the diaphragm 200 or may be embedded in and penetrate the diaphragm 200.
  • the materials of the diaphragm 200, the second conductive layer 320, and the first conductive layer 130 are the same, for example, all are polysilicon.
  • the second conductive layer 320 is embedded in the diaphragm 200, it is an embedding of the same material, which will not cause an impedance problem, so there is no need to add a corresponding impedance matching structure, and the overall conductive performance is better.
  • the second conductive layer 320 may include two types, that is, includes a first type conductive layer and a second type conductive layer. Wherein, the second end of the first type conductive layer is embedded in the diaphragm 200, and its embedding depth is greater than or equal to one-third of the thickness of the diaphragm 200 and less than the thickness of the diaphragm 200. The second end of the second type conductive layer is embedded in and penetrates the entire diaphragm 200.
  • the second conductive layers 320 in the connection pillar 300 may all be the first type conductive layers or all the second type conductive layers. It can be understood that the second conductive layer 320 in the connection pillar 300 may also include the first type conductive layer and the second type conductive layer at the same time. In FIG. 1, all the second conductive layers 320 include the first type conductive layer and the second type conductive layer. In FIG. 6, all the second conductive layers 320 are the second type conductive layers.
  • the second insulating layer 310 can also be embedded inside the diaphragm 200, thereby further increasing the bonding area of the connecting post 300 and the diaphragm 200, and improving the mechanical strength of the connecting post 300 connecting the diaphragm 200.
  • the second insulating layer 310 does not embed and penetrate the diaphragm 200, that is, the embedded depth of the second insulating layer 310 is greater than one third of the thickness of the diaphragm 200 and less than the thickness of the diaphragm 200.
  • the material of the second insulating layer 310 When the second insulating layer 310 is embedded and penetrates the diaphragm 200, when the dielectric oxide layer 420 (for example, silicon oxide) is released, the material of the second insulating layer 310 will be attacked, causing the penetration of the diaphragm 200 The material of the second insulating layer 310 is etched and does not exist.
  • the dielectric oxide layer 420 for example, silicon oxide
  • the connecting pillar 300 further includes a third protective layer (not shown) disposed at the outermost periphery.
  • the first end of the third protective layer is formed integrally with the first protective layer 120, and the second end of the third protective layer is connected to or embedded in the diaphragm 200. Adding a third protective layer can increase the bonding area of the diaphragm 200 and the connecting post 300, thereby improving the mechanical strength of the connection.
  • the third protective layer and the first protective layer 120 have the same material, and both can be silicon nitride or silicon-rich silicon nitride.
  • the first protective layer 120, the second protective layer 140, and the third protective layer are all silicon-rich silicon nitride.
  • Using such a dielectric material to enclose the first conductive layer 130 on the backplane 100 and the second conductive layer 320 in the connection post 300 can prevent charges from remaining outside the connection post 300 and under the backplane 100. If there is residual charge, the MEMS sound sensor cannot have normal charge stored on the two electrode plates. At this time, the MEMS sound sensor cannot work normally, and the sensitivity will decrease, or even exceed the specifications.
  • a protrusion 230 is formed on the side of the diaphragm 200 away from the back plate 100.
  • the protrusion 230 is integrally formed with the diaphragm 200, that is, the two are an integral structure.
  • the second type conductive layer on the connecting post 300 extends into the protrusion 230, thereby further increasing the joint area of the connecting post 300 and the diaphragm 200, and improving the mechanical strength of the diaphragm connection.
  • the second type conductive layer extends into the protrusion 230.
  • the protrusion 230 surrounds the portion of the second type conductive layer extending into this area.
  • the protrusion 230 is a hollow ring-shaped structure when viewed from the bottom.
  • the protrusion 230 when the connecting post 300 is square, the protrusion 230 may also be a hollow square structure, or the entire surface structure is shown in FIG. 6.
  • the thickness of the protrusion 230 may not be limited. Specifically, before forming the diaphragm 200, the formed dielectric oxide layer 420 is partially etched, or completely etched or even etched onto the silicon substrate of the substrate 410. Since the corresponding area on the side of the diaphragm 200 away from the back plate 100 will be etched to form a back hole 412, the thickness of the protrusion 230 will not affect the overall performance.
  • a material layer for preparing the diaphragm 200 is formed above the substrate 410, and the etched area is filled during the forming process, thereby forming the diaphragm 200 each having the protrusion 230.
  • the rigidity of the diaphragm 200 can be improved to a certain extent.
  • the connecting post 300 further includes a bearing 340, as shown in FIG.
  • the bearing portion 340 is connected to the side of the diaphragm 200 away from the back plate 100.
  • the bearing portion 340 is connected to at least a part of the second-type conductive layer in the connecting post 300 to form a rivet structure.
  • the connection column 300 embedded in the diaphragm 200 can provide a horizontal force to achieve the fixing of the diaphragm 200, and the increase of the bearing portion 340 can increase the horizontal contact area with the diaphragm 200, which can increase the vertical
  • the supporting force makes the supporting force in two directions, so that the supporting strength of the connecting column 300 is stronger, and the stability of the diaphragm 200 is better.
  • the edge of the second conductive layer 320 in the connecting post 300 is located within the edge of the carrying portion 340, so there can be a greater tolerance of alignment errors during the manufacturing process, the process is better, and there will be no peeling Cracking or etching is difficult to align.
  • the above MEMS sound sensor can be used as an acceleration sensor to detect acceleration.
  • the external force acting on the mass 210 can be detected according to the capacitance change of the MEMS sound sensor, so that the current acceleration can be calculated according to the mass of the mass 210.
  • the MEMS sound sensor can be multi-functionalized, and has a simpler structure than the conventional comb-shaped acceleration sensor, and the diaphragm 200 and the back plate 100 are the entire surface Structure, with extremely high capacitance.
  • An embodiment of the present application further provides a MEMS microphone, as shown in FIG. 8.
  • the MEMS microphone includes a printed circuit board 610 and a MEMS sound sensor 620 and an integrated circuit 630 provided on the printed circuit board 610.
  • the integrated circuit 630 may also be called an ASIC chip.
  • the MEMS sound sensor 620 uses the MEMS microphone described in any of the foregoing embodiments. This case does not specifically limit the structure of the MEMS microphone.
  • the MEMS microphone is packaged using a flip chip, that is, both the MEMS sound sensor 620 and the integrated circuit 630 are integrated on the printed circuit board 610 using a flip chip process.
  • the MEMS sound sensor 620 and the integrated circuit 630 are directly connected to the pads on the printed circuit board 610 by not bonding wires.
  • the MEMS sound sensor 620 and the integrated circuit 630 are connected to the printed circuit board 610 through the solder ball 640, so as to realize the electrical connection between the MEMS sound sensor 620 and the integrated circuit 630 and the printed circuit board 610.
  • the noise problem caused by wire bonding can be avoided, so that the entire MEMS microphone has a high signal-noise ratio (SNR).
  • SNR signal-noise ratio
  • the above-mentioned MEMS microphone also includes a package case 650.
  • the package case 650 and the printed circuit board 610 cooperate with each other to form a receiving space for receiving the MEMS sound sensor 620 and the integrated circuit 630.
  • neither the package case 650 nor the printed circuit board 610 is provided with a through hole for air flow to pass through.
  • the above-mentioned MEMS microphone is used for detecting sound and converting it into an electrical signal output by detecting vibration of bones (such as ear bones) or solid substances caused during speech.
  • the side where the printed circuit board 610 is located is close to the ear bones or other solid substances, so that the diaphragm 200 is very close to the vibration source (the arrows in FIG. 8 to FIG. 10 indicate the vibration source), the entire conduction path is short, Greatly enhance the effectiveness of the sensor signal under the flip-chip structure, so that the MEMS microphone has a higher signal-to-noise ratio.
  • a perforation 652 for the airflow to pass through may also be provided in the area of the package housing 650 near the MEMS sound sensor 620, as shown in FIG. 9.
  • a through hole 612 may also be directly formed on the printed circuit board 610, as shown in FIG.
  • the MEMS sound sensor 620 in the MEMS microphone can perform sound detection according to the change in capacitance caused by the change in sound pressure or air pressure, and can also perform sound detection according to the change in capacitance caused by vibration.
  • the integrated circuit 630 may process the detected signal according to a preset algorithm and output it.
  • An embodiment of the present application further provides an electronic device, including a device body and a MEMS microphone provided on the device body.
  • the MEMS microphone is prepared by using the MEMS sound sensor described in any of the foregoing embodiments.
  • the electronic device may be a mobile phone, digital camera, notebook computer, personal digital assistant, MP3 player, hearing aid, TV, telephone, conference system, wired headset, wireless headset, voice recorder, recording device, wire controller, etc.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
  • Pressure Sensors (AREA)

Abstract

L'invention concerne un capteur acoustique MEMS, destiné à être utilisé pour détecter un son au moyen d'un changement de pression sonore d'air et/ou d'une vibration mécanique. Le capteur acoustique MEMS comprend : une plaque arrière ; un diaphragme opposé à la plaque arrière et comprenant un espace avec la plaque arrière, le diaphragme et la plaque arrière constituant une structure de condensateur ; et une tige de connexion, comprenant une première extrémité et une seconde extrémité opposées l'une à l'autre, la première extrémité de la tige de connexion étant connectée de manière fixe à la plaque arrière, et la seconde extrémité de la tige de connexion étant électriquement connectée à une région centrale du diaphragme afin de suspendre le diaphragme sur la plaque arrière. Une zone de bord du diaphragme est pourvue d'au moins un bloc de masse ; la plaque arrière est pourvue d'une ouverture ; l'ouverture est utilisée pour exposer le bloc de masse de façon à former un espace entre le bloc de masse et la plaque arrière, ou l'ouverture est utilisée comme trou sonore sur la plaque arrière.
PCT/CN2018/125351 2018-12-29 2018-12-29 Capteur acoustique mems, microphone mems, et dispositif électronique WO2020133352A1 (fr)

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PCT/CN2018/125351 WO2020133352A1 (fr) 2018-12-29 2018-12-29 Capteur acoustique mems, microphone mems, et dispositif électronique
CN201880028690.8A CN110603819B (zh) 2018-12-29 2018-12-29 Mems声音传感器、mems麦克风及电子设备

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CN215918085U (zh) * 2020-07-02 2022-03-01 瑞声科技（南京）有限公司 压电超声换能器
WO2022140921A1 (fr) * 2020-12-28 2022-07-07 深圳市韶音科技有限公司 Capteur de vibrations

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