WO2023216686A1 - 双振膜mems麦克风及其制造方法 - Google Patents

双振膜mems麦克风及其制造方法 Download PDF

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Publication number
WO2023216686A1
WO2023216686A1 PCT/CN2023/079374 CN2023079374W WO2023216686A1 WO 2023216686 A1 WO2023216686 A1 WO 2023216686A1 CN 2023079374 W CN2023079374 W CN 2023079374W WO 2023216686 A1 WO2023216686 A1 WO 2023216686A1
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Prior art keywords
diaphragm
insulating layer
backplane
hole
holes
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PCT/CN2023/079374
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English (en)
French (fr)
Inventor
缪建民
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迈感微电子(上海)有限公司
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Publication of WO2023216686A1 publication Critical patent/WO2023216686A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R19/00—Electrostatic transducers
    • H04R19/04—Microphones

Definitions

  • the present application relates to the field of microphone technology, for example, to a dual-diaphragm micro-electro-mechanical system (Micro-Electro-Mechanical System, MEMS) microphone and its manufacturing method.
  • MEMS Micro-Electro-Mechanical System
  • MEMS microphone is a kind of electric energy sound exchanger. As shown in Figure 1, it is a common MEMS microphone in related technologies.
  • the main structure of the MEMS microphone is composed of a diaphragm 2' and a back plate 1'.
  • the diaphragm 2' and the back plate The plates 1' are spaced at a certain distance to form an approximately parallel capacitor.
  • the capacitance between the diaphragm 2' and the back plate 1' will follow the relationship between the diaphragm 2' and the back plate.
  • the sound signal changes with the change of the distance between the boards 1', thereby converting the sound signal into an electrical signal, which is then amplified by an Application Specific Integrated Circuit (ASIC) circuit and output.
  • ASIC Application Specific Integrated Circuit
  • single-diaphragm single-backplane MEMS microphones can often only be achieved by increasing the area of the chip diaphragm.
  • the increase in the area of the chip diaphragm 2' will, on the one hand, reduce the vibration resistance of the diaphragm 2'. ability, it is easy to break the membrane, reducing the reliability of the diaphragm 2', resulting in a greatly increased probability of failure during use.
  • the packaging form will also cause the packaging form to be limited, making it difficult to use smaller-sized packaging forms, so the application market will Very restricted.
  • This application provides a dual-diaphragm MEMS microphone that improves the signal-to-noise ratio without increasing the diaphragm area.
  • a dual-diaphragm MEMS microphone includes a backplate unit, a first diaphragm, a second diaphragm and a plurality of link units.
  • the backplate unit is insulated and supported on the first diaphragm and the second diaphragm.
  • the back plate unit and the first diaphragm form a first variable capacitor
  • the back plate unit and the second diaphragm form a second variable capacitor
  • the back plate unit is provided with a plurality of Through holes, each connection unit is penetrated through a through hole, the plurality of through holes are arranged in one-to-one correspondence with the plurality of connection units, and the plurality of through holes and the plurality of connection units form a plurality of first Annular hole;
  • each connection unit consists of:
  • a plurality of connecting posts one end of each connecting post is connected to the side of the first diaphragm facing the second diaphragm;
  • a connecting block one end of the connecting block is connected to the side of the second diaphragm facing the first diaphragm, the connecting block is provided with an accommodating groove, and the notch of the accommodating groove faces the first diaphragm;
  • a connecting plate is configured to connect the connecting block and a plurality of connecting columns, and the accommodating groove and the connecting plate form an accommodating cavity;
  • the plurality of connecting posts, the connecting plate and the connecting block are all insulating structures.
  • This application provides a manufacturing method for a dual-diaphragm MEMS microphone, which reduces process difficulty and improves structural reliability.
  • a method of manufacturing a dual-diaphragm MEMS microphone including:
  • An underlying insulating layer is provided on the substrate, and a first diaphragm is deposited on the underlying insulating layer;
  • a first insulating layer is deposited on the first diaphragm, and a plurality of first through hole groups are etched on the first insulating layer.
  • Each first through hole group includes at least two first through holes arranged at intervals. ;
  • An intermediate conductive layer is deposited on the first backplane insulating layer, and a plurality of second through holes and a plurality of third through holes are etched on the intermediate conductive layer.
  • the plurality of third through holes are connected with the plurality of third through holes.
  • the first through hole group is set in one-to-one correspondence;
  • the positions corresponding to the plurality of second through holes are etched to form sound holes when the materials of the second backplane insulating layer and the first backplane insulating layer are deposited; the maximum outer edge is preset so that each group of first through hole groups A plurality of first through holes are located within the largest outer edge, and the second backplane insulating layer and the second backplane insulating layer are etched and deposited at the position of the first annular hole formed by each third through hole and the largest outer edge.
  • the material of the first backplane insulating layer, the material of the first backplane insulating layer and the material of the second backplane insulating layer in the first annular hole form a connecting plate;
  • a back cavity is etched on the substrate, a part of the first insulating layer and a part of the second insulating layer are released through the release hole, and a part of the underlying insulating layer is released through the back cavity , forming a dual-diaphragm MEMS microphone.
  • Figure 1 is a cross-sectional view of a MEMS microphone in the related art
  • Figure 2 is a cross-sectional view of a dual-diaphragm MEMS microphone provided by a specific embodiment of the present application;
  • Figure 3 is a cross-sectional view of a connection unit provided by a specific embodiment of the present application.
  • Figure 4 is a cross-sectional view of a substrate provided with an underlying insulating layer according to a specific embodiment of the present application
  • Figure 5 is a cross-sectional view of etching a first groove on the underlying insulating layer according to a specific embodiment of the present application
  • Figure 6 is a cross-sectional view of depositing the first diaphragm and filling the first groove to form the first wrinkle structure according to the specific embodiment of the present application;
  • Figure 7 is a cross-sectional view of a vent hole etched on the first diaphragm according to a specific embodiment of the present application.
  • Figure 8 is a cross-sectional view of the deposited first insulating layer provided by a specific embodiment of the present application.
  • Figure 9 is a cross-sectional view of etching a first through hole and a second groove on the first insulating layer according to a specific embodiment of the present application.
  • Figure 10 is a cross-sectional view of the deposited first backplane insulating layer provided by a specific embodiment of the present application.
  • Figure 11 is a cross-sectional view of a deposited intermediate conductive layer provided by a specific embodiment of the present application.
  • Figure 12 is a cross-sectional view of etching second through holes and third through holes on the intermediate conductive layer according to the specific embodiment of the present application;
  • Figure 13 is a cross-sectional view of a second backplane insulating layer deposited according to a specific embodiment of the present application.
  • Figure 14 is a cross-sectional view of etching the second backplane insulating layer and the first backplane insulating layer to form the acoustic hole and the first annular hole according to the specific embodiment of the present application;
  • Figure 15 is a cross-sectional view of depositing a second insulating material on the second backplane insulating layer according to a specific embodiment of the present application;
  • Figure 16 is a cross-sectional view after grinding the second insulating material according to the specific embodiment of the present application.
  • Figure 17 is a cross-sectional view of a deposited second insulating layer provided by a specific embodiment of the present application.
  • Figure 18 is a cross-sectional view of etching the fourth groove and the second annular hole in the second insulating layer according to the specific embodiment of the present application;
  • Figure 19 is a cross-sectional view of depositing the first insulating material according to the specific embodiment of the present application.
  • Figure 20 is a cross-sectional view of an annular support structure formed by etching the first insulating material according to the specific embodiment of the present application;
  • Figure 21 is a cross-sectional view of etching a third groove in the second insulating layer according to a specific embodiment of the present application.
  • Figure 22 is a cross-sectional view of a deposited second diaphragm provided by a specific embodiment of the present application.
  • Figure 23 is a cross-sectional view of a release hole etched in the second diaphragm according to a specific embodiment of the present application.
  • Figure 24 is a cross-sectional view of an etching back cavity provided by a specific embodiment of the present application.
  • FIG. 25 is a cross-sectional view of respectively releasing part of the underlying insulation layer, the first insulation layer and the second insulation layer according to the specific embodiment of the present application.
  • Ring-shaped support structure 3081. Second protruding structure; 309. Second diaphragm; 3091. Release hole; 3092. Second fold structure; 310.
  • the second insulating material 1. Connection unit; 11. Connection column; 12. Connection block; 121. Annular groove; 13. Connection plate; 14. Column; 15. Filling block; 2. Backplane unit.
  • connection should be understood in a broad sense.
  • it can be a fixed connection, a detachable connection, or an integral body.
  • It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be an internal connection between two elements or an interaction between two elements.
  • connection can be a fixed connection, a detachable connection, or an integral body.
  • It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be an internal connection between two elements or an interaction between two elements.
  • the term “above” or “below” a first feature on a second feature may include direct contact between the first and second features, or may also include the first and second features. Not in direct contact but through additional characteristic contact between them.
  • the terms “above”, “above” and “above” a first feature on a second feature include the first feature being directly above and diagonally above the second feature, or simply mean that the first feature is higher in level than the second feature.
  • “Below”, “under” and “under” the first feature is the second feature includes the first feature being directly below and diagonally below the second feature, or simply means that the first feature is less horizontally than the second feature.
  • the dual-diaphragm MEMS microphone includes a backplane unit 2, a first diaphragm 302, a second diaphragm 309 and multiple connection units 1 .
  • the back plate unit 2 is insulated and supported between the first diaphragm 302 and the second diaphragm 309 .
  • the back plate unit 2 and the first diaphragm 302 form a first variable capacitor.
  • the back plate unit 2 and the second diaphragm 309 form a first variable capacitor.
  • the backplane unit 2 is provided with a plurality of through holes. Each connection unit 1 is penetrated through a through hole.
  • the plurality of through holes are arranged in one-to-one correspondence with the plurality of connection units 1.
  • the plurality of through holes are connected to the plurality of connection units 1.
  • Each connection unit 1 forms a plurality of first annular holes 3062 so that there is a gap between the backplane unit 2 and the connection unit 1 .
  • the two diaphragms By arranging two diaphragms, namely the first diaphragm 302 and the second diaphragm 309, and the back plate unit 2, one of the two diaphragms is located on one side of the back plate unit 2, and the other diaphragm is located on the back plate. On the other side of the unit, the two diaphragms are connected through the connection unit 1, and form two approximately parallel differential capacitors with the backplane unit 2.
  • the dual-diaphragm MEMS microphone When the dual-diaphragm MEMS microphone receives a sound signal, the two diaphragms can vibrate together in the same direction and produce the same displacement, but the sum of the distances between the two diaphragms and the backplane unit 2 remains unchanged, achieving differential The output of the signal offsets the interference of the noise signal. Therefore, based on the single-diaphragm single-backplane MEMS microphone with the same chip area, the signal-to-noise ratio of the MEMS microphone can be improved by more than 3dB; or the same signal-to-noise ratio of the silicon microphone can be achieved. , the area of the diaphragm of the microphone of this application can be reduced by half, greatly reducing the chip area, thereby ensuring an improved signal-to-noise ratio without increasing the chip area, improving reliability during use, and facilitating packaging.
  • connection unit 1 includes a column 14, a connection block 12, a connection plate 13 and a plurality of connection columns. 11.
  • One end of the connecting post 11 is connected to the side of the first diaphragm 302 facing the second diaphragm 309; one end of the connecting block 12 is connected to the side of the second diaphragm 309 facing the first diaphragm 302.
  • the connecting block 12 has The receiving groove has the notch facing the first diaphragm 302; the connecting plate 13 connects the connecting block 12 and a plurality of connecting columns 11; the connecting column 11 is connected to the connecting block 12 through the connecting plate 13, and the connecting column 11 is connected to the first vibrating membrane 302.
  • the membrane 302 and the connection block 12 are connected to the second diaphragm 309, and the connection unit 1 passes through the back plate unit 2, so that the first diaphragm 302 and the second diaphragm 309 are connected through the connection unit 1.
  • the connecting posts 11 , the connecting plates 13 and the connecting blocks 12 are all insulating structures made of insulating materials. They can be made of the same insulating material, or can be made of different insulating materials.
  • the insulating materials used for the connecting posts 11 , the connecting plates 13 and the connecting blocks 12 can be determined according to the production process. In this embodiment, they can all be made of silicon nitride material.
  • the upright column 14, the connecting column 11, the connecting plate 13 and the connecting block 12 are all deposited and connected.
  • the deposition process if the outer diameter of the connecting pillar 11 is large, the sacrificial structure released at the outer periphery of the hole and other locations will be large and difficult to remove, resulting in a difficult process.
  • the structural connection will be unstable. . Therefore, in this embodiment, by arranging a plurality of connecting posts 11 with smaller outer diameters, it can not only meet the requirements of structural stability, but also reduce the process difficulty.
  • the receiving groove of the connecting block 12 and the connecting plate 13 form a receiving cavity; the upright column 14 fills the receiving cavity.
  • the deposition amount of the connecting block 12 can be reduced, which reduces the process difficulty during the production process without reducing the outer diameter of the connecting block 12, thereby improving the structural stability.
  • the plurality of connecting columns 11 are evenly distributed, the diameter of the cylinder is 1-4um, and the number is 3-5.
  • the connecting pillars 11 and the connecting plates 13 are formed through the deposition process of the backplane unit 2 .
  • the connecting block 12 has an annular groove 121.
  • the annular groove 121 is in the opposite direction to the notch of the accommodating groove.
  • the annular groove 121 is arranged around the wall of the accommodating groove. During deposition, During the process, it is very difficult to directly fill the connecting block 12 without forming the annular groove 121. Therefore, leaving the annular groove 121 can reduce the process difficulty.
  • the annular groove 121 is provided with a filling block 15, which is filled by depositing again.
  • connection unit 1 is similar to a "ding" shape, and the structure is more stable; for example, the filling block 15 is made of polysilicon material, and is formed when the second diaphragm 309 is deposited, thereby reducing process steps.
  • the pillar 14 is formed by depositing silicon oxide
  • the connection unit 1 is composed of three materials: silicon oxide, polysilicon, and silicon nitride.
  • the manufacturing process can be made as simple and practical as possible; on the other hand, the manufacturing process can be made as simple and practical as possible;
  • the reliability of the connection structure is ensured by the mutual cancellation of stresses between different materials, combined with the lightness and stability of the "ding" structure.
  • connection units 1 are evenly distributed in a ring shape.
  • the distance between two connection units 1 is 50-100um.
  • the dual-diaphragm MEMS microphone also includes a substrate 300 and an underlying insulating layer 301 disposed on the substrate 300 , and the first diaphragm 302 is disposed on the underlying insulating layer 301 ,
  • the substrate 300 has a circular back cavity 3001.
  • the substrate 300 is made of single crystal silicon and has a thickness of 300um-500um.
  • a first wrinkle structure 3022 is provided on the side of the first diaphragm 302 close to the underlying insulating layer 301 to reduce stress concentration; in this embodiment, the first diaphragm 302 is made of polysilicon. The thickness is 0.5um-1.5um, and the first wrinkle structure 3022 is provided on the edge of the first diaphragm 302 .
  • a venting structure is provided on the first diaphragm 302 as a venting channel, which can reduce vibration resistance during the vibration process; when packaging a dual-diaphragm MEMS microphone or dual-diaphragm MEMS When the microphone vibrates greatly and needs to balance the internal and external air pressure, the air pressure on both sides of the first diaphragm 302 can be quickly balanced through the vent structure, and the effect is better.
  • the venting structure includes a plurality of venting holes 3021 opened on the first diaphragm 302 , and the plurality of venting holes 3021 are arranged at intervals around the connection unit 1 .
  • the second diaphragm 309 is easily affected by various factors. For example, when the second diaphragm 309 is impacted by external high-voltage vibration, the edge portion of the second diaphragm 309 is subject to the greatest stress.
  • the second diaphragm 309 is An annular support structure 308 is also provided between the membrane 309 and the back plate unit 2 . The annular support structure 308 is supported on the outer edge of the second diaphragm 309 and the back plate unit 2 .
  • the second diaphragm 309 is made of polysilicon
  • the annular support structure 308 is made of silicon nitride.
  • the second diaphragm 309 and the annular support structure 308 form a composite structure of silicon nitride and polysilicon, and the annular support structure 308 utilizes It has good toughness and supports and protects the second diaphragm 309.
  • the overall thickness of the second diaphragm 309 and the annular support structure 308 is 1-2.5um; the annular support structure 308 is located on the outer edge and has a thickness of 0.5-1um.
  • the thickness of the second diaphragm 309 is 0.5-1.5um.
  • a second wrinkle structure 3092 is provided on the side of the second diaphragm 309 close to the backplane unit 2, which reduces stress concentration.
  • the second wrinkle structure 3092 is provided on the second diaphragm 309. The edge position of membrane 309.
  • a release structure is provided on the second diaphragm 309, which is used to release the sacrificial layer during the formation of the dual-diaphragm MEMS microphone.
  • the release structure includes a plurality of release holes 3091 opened on the second diaphragm 309. After forming a dual-diaphragm MEMS microphone, the release holes 3091 can act as a venting structure to improve the use effect; Exemplarily, a plurality of release holes 3091 Evenly distributed, the release holes 3091 are through holes with diameters ranging from 0.5um to 1um.
  • a second protruding structure 3081 is connected to the side of the second diaphragm 309 close to the backplane unit 2.
  • the second protruding structure 3081 is made of the same material as the annular support structure 308.
  • the second protruding structure 3081 Evenly distributed under the second diaphragm 309, it prevents the second diaphragm 309 from sticking to the backplane unit 2 during vibration, thereby improving the reliability of the second diaphragm 309.
  • the dual-diaphragm MEMS microphone also includes a first insulating layer 303 and a second insulating layer 307.
  • the first insulating layer 303 is supported between the first diaphragm 302 and the backplane unit 2
  • the second insulating layer 307 is supported between the second diaphragm 309 and the backplane unit 2 .
  • the backplane unit 2 includes a first backplane insulating layer 304, a second backplane insulating layer 306, and an intermediate conductive layer 305 disposed between the first backplane insulating layer 304 and the second backplane insulating layer 306.
  • the first backplane insulating layer 304 and the second backplane insulating layer 306 are made of the same insulating material and deposited separately.
  • the first backplane insulating layer 304 and the second backplane insulating layer 306 are both made of silicon nitride. Silicon nitride has high hardness and strength, making it difficult for the backplane unit 2 to serve as a fixed electrode. Deformation occurs, thereby improving the reliability of the structure.
  • the middle conductive layer 305 is made of polysilicon.
  • the thickness of the first backplane insulating layer 304 and the second backplane insulating layer 306 is 0.5-2um
  • the thickness of the middle conductive layer 305 is 0.3-1um
  • the thickness of the backplane unit 2 is uniform. Sound holes 3061 are distributed, and a first protruding structure 3041 is provided on the side of the backplane unit 2 close to the first diaphragm 302.
  • the first protruding structure 3041 is disposed on the first backplane insulating layer 304 to prevent the first vibration.
  • the membrane 302 sticks to the back plate unit 2 during vibration; for example, the first protruding structures 3041 are evenly distributed.
  • This embodiment also provides a method for manufacturing a dual-diaphragm MEMS microphone, as shown in Figures 4 to 25, including the following steps:
  • An underlying insulating layer 301 is provided on the substrate 300, and the first diaphragm 302 is deposited on the underlying insulating layer 301.
  • Each group of first through-hole groups includes at least two first through-hole groups arranged at intervals. Hole 3032.
  • the sound hole 3061 is formed by positionally etching the material used to deposit the second backplane insulating layer 306 and the first backplane insulating layer 304; the maximum outer edge is preset so that the plurality of first through holes 3032 of the first through hole group are located at the maximum outer edge.
  • the material when depositing the second backplane insulating layer 306 and the first backplane insulating layer 304 is etched at the position of the first annular hole 3062 formed by the third through hole 3052 and the largest outer edge. Inside the first annular hole 3062 The material of the first backplane insulating layer 304 and the material of the second backplane insulating layer 306 form the connecting plate 13 .
  • connection block 12 Fill the second annular hole 3072 with a first insulating material different from the material of the second insulating layer 307 to form the connection block 12.
  • S8 Deposit the second diaphragm 309 on the second insulating layer 307, and etch the release hole 3091 in the second diaphragm 309 along the thickness direction.
  • the first diaphragm 302, the first insulating layer 303, the first backplane insulating layer 304, the middle conductive layer 305, the second backplane insulating layer 306, and The second insulating layer 307 and the second diaphragm 309 form the above-mentioned dual-diaphragm MEMS microphone.
  • the first backplane insulating layer 304, the middle conductive layer 305 and the second backplane insulating layer 306 form the backplane unit 2.
  • the connecting column 11, the connecting plate 13, the upright column 14 and the connecting block 12 are formed in sequence to form the connecting unit 1, so that the connecting unit 1 passes through the back plate unit 2 to connect the first diaphragm 302 and the second diaphragm 309.
  • the "tripod"-shaped connection unit 1 formed by the connecting column 11, the upright 14, the connecting block 12 and the connecting plate 13 has a stable structure, which improves the structural stability of the dual-diaphragm MEMS microphone, and avoids connecting the unit 1 during the production process.
  • the structure is too large, resulting in a larger sacrificial structure, which reduces the process difficulty.
  • connection pillar 11 is formed by filling the first through hole 3032, which has a simple process and a reliable structure.
  • the dual-diaphragm MEMS microphone produced through the above process ensures an improved signal-to-noise ratio without increasing the chip area, improves reliability during use, and facilitates packaging.
  • the method before depositing and forming the first diaphragm 302 on the underlying insulating layer 301 , the method further includes: S100 , etching the first groove 3011 on the underlying insulating layer 301 , and depositing to form the first diaphragm 302 .
  • a diaphragm 302 simultaneously fills the first groove 3011 to form a first wrinkle structure 3022 to reduce stress concentration.
  • the method further includes: S101 , etching a plurality of vent holes 3021 on the first diaphragm 302 , by setting the vent holes 3021 , improve the use effect.
  • the first through hole group and the vent hole 3021 are arranged staggered.
  • the method further includes: S201, etching a plurality of second grooves 3031 on the first insulating layer 303, The second groove 3031 is staggered from the first through hole group.
  • the method also includes: S301: When depositing the first backplane insulating layer 304 on the first insulating layer 303, filling the second groove 3031 to form the first protrusion structure 3041.
  • the first protruding structure 3041 is formed on the second groove 3031.
  • the process is simple and the structure is reliable.
  • the formed first protrusion structure 3041 prevents the first diaphragm 302 from sticking to the backplane unit 2 during vibration, that is, preventing the first diaphragm 302 from sticking to the first backplane insulating layer 304. Together.
  • the material thickness of the second backplane insulating layer 306 deposited on the middle conductive layer 305 is the same as that of the first backplane insulating layer 304 deposited on the middle conductive layer 305. have the same thickness, making the backplane unit 2 symmetrical on both sides, and the structure is more stable.
  • the sound hole 3061 and the first annular hole 3062 are filled with the second insulating material 310 to facilitate the subsequent deposition of the second insulating layer 307.
  • the second backplane insulating layer 306 is polished through a chemical mechanical polishing process to facilitate subsequent deposition and improve structural reliability and structural accuracy.
  • the second insulating material 310 and the second insulating layer 307 are made of the same material, which is silicon oxide, to facilitate subsequent release.
  • the process further includes: S603 , etching a plurality of third grooves on the second insulating layer 307 3073, the third groove 3073 and the second annular hole 3072 are staggered.
  • the method also includes: S801: when depositing the second diaphragm 309 on the second insulation layer 307, filling the third groove 3073 to form a second wrinkle structure 3092.
  • the structure is reliable and the process is simple. Through the second pleat structure 3092, stress concentration is reduced.
  • the method further includes: S701.
  • a layer of first insulating material is deposited on 307, and the first insulating material is etched so that the first insulating material forms a ring-shaped support structure 308 and is disposed between the second insulating layer 307 and the outer edge of the second diaphragm 309.
  • the annular support structure 308 is supported on the second diaphragm 309 and the outer edge of the backplane unit 2 . Since the second diaphragm 309 is subject to vibration and impact, and the edge portion is subject to the greatest stress, the annular support structure 308 can support and protect the second diaphragm 309 .
  • the first insulating material is nitrided Silicon and silicon nitride materials have good toughness.
  • the method before etching the third groove 3073 on the second insulating layer 307 , the method further includes: S6031 , etching the fourth groove 3071 on the second insulating layer 307 .
  • the method further includes: S702: When depositing the first insulating material on the second insulating layer 307, filling the fourth groove 3071 to form the second protrusion structure 3081.
  • the second protrusion structure 3081 is formed on the fourth groove 3071, which has a reliable structure and a simple process; the second protrusion structure 3081 can prevent the second diaphragm 309 from sticking to the backplane unit 2 when it vibrates. Together, we improve reliability.
  • the connecting block 12 has annular grooves 121 , and the annular grooves 121 are spaced on the outer periphery of the column 14 .
  • the method further includes: S802: When depositing the second diaphragm 309 on the second insulating layer 307, filling the annular groove 121 to form the filling block 15.
  • connection block 12 Since it is difficult to deposit the surface of the connection block 12 to form a plane during the deposition process, an annular groove 121 is left on the connection block 12. Later, when the second diaphragm 309 is deposited, the annular groove 121 is filled to form the filling block 15. The process difficulty is reduced and the structural reliability is improved.

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

Abstract

本申请公开了一种双振膜MEMS麦克风及其制造方法，包括背板单元、第一振膜、第二振膜和多个连接单元，背板单元绝缘且支撑于第一振膜和第二振膜之间，背板单元开设有多个通孔，每个连接单元穿设于一个通孔，多个通孔与多个连接单元一一对应设置，多个通孔与多个连接单元形成多个第一环形孔；每个连接单元包括多个连接柱、连接块、连接板和立柱，每个连接柱的一端连接于第一振膜朝向第二振膜的一侧；连接块的一端连接于第二振膜朝向第一振膜的一侧，连接块设置有容纳槽，容纳槽的槽口朝向第一振膜；连接板设置为连接连接块和多个连接柱，容纳槽与连接板形成容纳腔；立柱填充于容纳腔。

Description

双振膜MEMS麦克风及其制造方法
本申请要求在2022年05月10日提交中国专利局、申请号为202210500461.X的中国专利申请的优先权，该申请的全部内容通过引用结合在本申请中。
技术领域
本申请涉及麦克风技术领域，例如涉及一种双振膜微机电***(Micro-Electro-Mechanical System，MEMS)麦克风及其制造方法。
背景技术
MEMS麦克风是一种电能换声器，如图1所示，为相关技术中常见的MEMS麦克风，该MEMS麦克风主要结构由一个振膜2＇和一个背板1＇构成，振膜2＇与背板1＇间隔一定的距离，形成一近似平行的电容器，当振膜2＇在声波的作用下产生振动时，振膜2＇与背板1＇间的电容会随着振膜2＇与背板1＇之间距离的变化而改变，从而将声音信号转变为电信号，再经过专用集成电路(Application Specific Integrated Circuit，ASIC)电路放大后输出。
虽然相关技术中的单振膜单背板MEMS麦克风制造工艺已经比较成熟，且通过设计和工艺优化，其信噪比(Signal to Interference plus Noise Ratio，SNR)可以达到68dB，但要在此基础上进一步提高信噪比，单振膜单背板MEMS麦克风往往只能通过增大芯片振膜面积的方式来实现，芯片振膜2＇面积的增大，一方面会降低振膜2＇的抗振能力，容易破膜，降低振膜2＇的可靠性，导致使用过程中的失效概率大大增加，另一方面也会导致封装形式受限，很难采用较小尺寸的封装形式，因而应用市场会受到很大限制。
发明内容
本申请提供一种双振膜MEMS麦克风，在不增大振膜面积的情况下提高信噪比。
本申请采用以下技术方案：
一种双振膜MEMS麦克风，包括背板单元、第一振膜、第二振膜和多个链接单元，所述背板单元绝缘且支撑于所述第一振膜和所述第二振膜之间，所述背板单元与所述第一振膜形成第一可变电容，所述背板单元与所述第二振膜形成第二可变电容，所述背板单元开设有多个通孔，每个连接单元穿设于一个通孔，所述多个通孔与所述多个连接单元一一对应设置，所述多个通孔与所述多个连接单元形成多个第一环形孔；每个连接单元包括：
多个连接柱，每个连接柱的一端连接于所述第一振膜朝向所述第二振膜的一侧；
连接块，连接块的一端连接于所述第二振膜朝向所述第一振膜的一侧，所述连接块设置有容纳槽，所述容纳槽的槽口朝向所述第一振膜；
连接板，设置为连接所述连接块和多个连接柱，所述容纳槽与所述连接板形成容纳腔；
立柱，填充于所述容纳腔；
所述多个连接柱、所述连接板及所述连接块均为绝缘结构。
本申请提供一种双振膜MEMS麦克风的制造方法，降低工艺难度，提高结构可靠性。
本申请采用以下技术方案：
一种双振膜MEMS麦克风的制造方法，包括：
衬底上设置有底层绝缘层，在所述底层绝缘层上沉积形成第一振膜；
在所述第一振膜上沉积第一绝缘层，在所述第一绝缘层上刻蚀多组第一通孔组，每组第一通孔组包括至少两个间隔设置的第一通孔；
在所述第一绝缘层上沉积第一背板绝缘层，并填充所述多组第一通孔组形成多个连接柱；
在所述第一背板绝缘层上沉积中间导电层，在所述中间导电层上刻蚀多个第二通孔和多个第三通孔，所述多个第三通孔与所述多组第一通孔组一一对应设置；
在所述中间导电层上沉积第二背板绝缘层，并在所述多个第二通孔和所述多个第三通孔上沉积所述第二背板绝缘层的材料，在所述多个第二通孔对应的位置蚀刻沉积所述第二背板绝缘层和所述第一背板绝缘层时的材料形成声孔；预设最大外缘，使每组第一通孔组的多个第一通孔均位于所述最大外缘内，在每个第三通孔与所述最大外缘形成的第一环形孔的位置刻蚀沉积所述第二背板绝缘层和所述第一背板绝缘层时的材料，所述第一环形孔内的所述第一背板绝缘层的材料和所述第二背板绝缘层的材料形成连接板；
在所述第二背板绝缘层上沉积第二绝缘层，在所述连接板对应位置蚀刻第二环形孔并在所述连接板上形成立柱；
在所述第二环形孔内填充与所述第二绝缘层材质不同的第一种绝缘材料形成连接块；
在所述第二绝缘层上沉积第二振膜，在所述第二振膜沿厚度方向蚀刻释放孔；
在所述衬底上刻蚀背腔，通过所述释放孔对所述第一绝缘层的一部分和所述第二绝缘层的一部分进行释放，通过所述背腔对底层绝缘层的一部分进行释放，形成双振膜MEMS麦克风。
附图说明
图1是相关技术中的MEMS麦克风的剖面图；
图2是本申请的具体实施方式提供的双振膜MEMS麦克风的剖面图；
图3是本申请的具体实施方式提供的连接单元的剖面图；
图4是本申请的具体实施方式提供的衬底上设置有底层绝缘层的剖面图；
图5是本申请的具体实施方式提供的在底层绝缘层上蚀刻第一凹槽的剖面图；
图6是本申请的具体实施方式提供的沉积第一振膜并填充第一凹槽形成第一褶皱结构的剖面图；
图7是本申请的具体实施方式提供的在第一振膜上刻蚀泄气孔的剖面图；
图8是本申请的具体实施方式提供的沉积第一绝缘层的剖面图；
图9是本申请的具体实施方式提供的在第一绝缘层上刻蚀第一通孔和第二凹槽的剖面图；
图10是本申请的具体实施方式提供的沉积第一背板绝缘层的剖面图；
图11是本申请的具体实施方式提供的沉积中间导电层的剖面图；
图12是本申请的具体实施方式提供的在中间导电层上刻蚀第二通孔和第三通孔的剖面图；
图13是本申请的具体实施方式提供的沉积第二背板绝缘层的剖面图；
图14是本申请的具体实施方式提供的蚀刻第二背板绝缘层和第一背板绝缘层形成声孔和第一环形孔的剖面图；
图15是本申请的具体实施方式提供的在第二背板绝缘层沉积第二种绝缘材料的剖面图；
图16是本申请的具体实施方式提供的研磨第二种绝缘材料后的剖面图；
图17是本申请的具体实施方式提供的沉积第二绝缘层的剖面图；
图18是本申请的具体实施方式提供的在第二绝缘层刻蚀第四凹槽和第二环形孔的剖面图；
图19是本申请的具体实施方式提供的沉积第一种绝缘材料的剖面图；
图20是本申请的具体实施方式提供的在第一种绝缘材料刻蚀形成环形支撑结构的剖面图；
图21是本申请的具体实施方式提供的在所述第二绝缘层刻蚀第三凹槽的剖面图；
图22是本申请的具体实施方式提供的沉积第二振膜的剖面图；
图23是本申请的具体实施方式提供的在第二振膜蚀刻释放孔的剖面图；
图24是本申请的具体实施方式提供的刻蚀背腔的剖面图；
图25是本申请的具体实施方式提供的分别释放部分底层绝缘层、第一绝缘层和第二绝缘层的剖面图。
图中：
1＇、背板；2＇、振膜；
300、衬底；3001、背腔；
301、底层绝缘层；3011、第一凹槽；
302、第一振膜；3021、泄气孔；3022、第一褶皱结构；
303、第一绝缘层；3031、第二凹槽；3032、第一通孔；
304、第一背板绝缘层；3041、第一突起结构；
305、中间导电层；3051、第二通孔；3052、第三通孔；
306、第二背板绝缘层；3061、声孔；3062、第一环形孔；
307、第二绝缘层；3071、第四凹槽；3072、第二环形孔；3073、第三凹槽；
308、环形支撑结构；3081、第二突起结构；
309、第二振膜；3091、释放孔；3092、第二褶皱结构；
310、第二种绝缘材料；
1、连接单元；11、连接柱；12、连接块；121、环形槽；13、连接板；14、
立柱；15、填充块；
2、背板单元。
具体实施方式
下面将结合附图对本申请实施例的技术方案做说明，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。
在本申请的描述中，除非另有明确的规定和限定，术语“相连”、“连接”、“固定”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或成一体；可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通或两个元件的相互作用关系。对于本领域的普通技术人员而言，可以视具体情况理解上述术语在本申请中的具体含义。
在本申请中，除非另有明确的规定和限定，第一特征在第二特征之“上”或之“下”可以包括第一和第二特征直接接触，也可以包括第一和第二特征不是直接接触而是通过它们之间的另外的特征接触。而且，第一特征在第二特征“之上”、“上方”和“上面”包括第一特征在第二特征正上方和斜上方，或仅仅表示第一特征水平高度高于第二特征。第一特征在第二特征“之下”、“下方”和“下面”包括第一特征在第二特征正下方和斜下方，或仅仅表示第一特征水平高度小于第二特征。
本实施例提供了一种双振膜MEMS麦克风，如图2和图3所示，双振膜MEMS麦克风包括背板单元2、第一振膜302、第二振膜309和多个连接单元1。背板单元2绝缘且支撑于第一振膜302和第二振膜309之间，背板单元2与第一振膜302形成第一可变电容，背板单元2与第二振膜309形成第二可变电容，背板单元2开设有多个通孔，每个连接单元1穿设于一个通孔，多个通孔与多个连接单元1一一对应设置，多个通孔与多个连接单元1形成多个第一环形孔3062，使背板单元2与连接单元1之间具有间隙。
通过设置两个振膜即第一振膜302和第二振膜309，以及背板单元2，两个振膜中的一个振膜位于背板单元2的一侧，另一个振膜位于背板单元的另一侧，两个振膜通过连接单元1相连，与背板单元2组成两个近似平行的差分电容器。当该双振膜MEMS麦克风接收到声音信号时，两个振膜可以向同一方向一起振动，产生相同的位移，但两个振膜与背板单元2间的距离之和保持不变，实现差分信号的输出，抵消掉噪声信号的干扰，因而可以在同样芯片面积的单振膜单背板MEMS麦克风的基础上，提高MEMS麦克风的信噪比3dB以上；或者实现同样的硅麦克风信噪比时，本申请麦克风的振膜的面积可以减少一半，大大减少了芯片面积，从而在保证提高信噪比的同时，不增加芯片面积，提高了使用过程中的可靠性，便于封装。
示例性的，连接单元1包括立柱14、连接块12、连接板13和多个连接柱 11，连接柱11的一端连接于第一振膜302朝向第二振膜309的一侧；连接块12的一端连接于第二振膜309朝向第一振膜302的一侧，连接块12具有容纳槽，容纳槽的槽口朝向第一振膜302；连接板13连接连接块12和多个连接柱11；连接柱11通过连接板13连接于连接块12，连接柱11连接于第一振膜302，连接块12连接于第二振膜309，连接单元1穿过背板单元2，从而实现了第一振膜302和第二振膜309通过连接单元1连接。
示例性的，连接柱11、连接板13及连接块12均为绝缘材料制成的绝缘结构，可以均采用相同的绝缘材料制成，也可以分别采用不同的绝缘材料制成。可根据生产工艺决定连接柱11、连接板13及连接块12采用的绝缘材料，本实施例中，可均采用氮化硅材料制成。在生产过程中，立柱14、连接柱11、连接板13及连接块12均通过沉积而成并连接。沉积过程中，如果连接柱11的外径较大，孔的外周边等位置产生被释放掉的牺牲结构较大，难以去除，导致工艺难度大，而外径较小，则导致结构连接不稳定。因此本实施例中，通过设置多个外径较小的连接柱11，既能满足结构稳定的要求，又能降低工艺难度。连接块12的容纳槽与连接板13形成容纳腔；立柱14填充于容纳腔。通过设置立柱14，能减少连接块12的沉积量，在生产过程中，降低工艺难度，且不会降低连接块12的外径，提高了结构稳定性。示例性的，多个连接柱11均匀分布，圆柱直径1-4um，数量为3-5个。本实施例中，连接柱11、连接板13均通过背板单元2沉积过程中而成。
可选地，如图3所示和图20所示，连接块12上具有环形槽121，环形槽121与容纳槽的槽口方向相反，环形槽121设置于容纳槽槽壁的四周，在沉积工艺过程中，在连接块12上不形成环形槽121而是直接填平的工艺难度较大，因此留有环形槽121可降低工艺难度，环形槽121内设置有填充块15，通过再次沉积填充形成，连接单元1整体结构类似于“鼎”型，结构更稳定；示例性的，填充块15由多晶硅材质制成，在沉积第二振膜309时形成填充块15，减少工艺步骤。
本实施例中，立柱14由氧化硅沉积形成，连接单元1由氧化硅、多晶硅和氮化硅三种材料复合而成，一方面可以使制造工艺尽可能地简单化、可实行化；另一方面，通过不同材料之间应力的相互抵消，结合“鼎”型结构的轻盈性和稳定性，从而保证了该连接结构的可靠性。
示例性的，如图2所示，多个通孔与多个连接单元1呈环状均匀分布，本实施例中，两个连接单元1之间的间距为50-100um。
可选地，如图2所示和图25所示，双振膜MEMS麦克风还包括衬底300和设置于衬底300上的底层绝缘层301，第一振膜302设置于底层绝缘层301上， 衬底300具有圆形背腔3001。本实施例中衬底300为单晶硅材质制成，厚度为300um-500um。
可选地，如图6所示，第一振膜302靠近底层绝缘层301的一侧设置有第一褶皱结构3022，以降低应力集中；本实施例中，第一振膜302采用多晶硅材质制成，厚度0.5um-1.5um，第一褶皱结构3022设置在第一振膜302的边缘部分。
可选地，如图7所示，第一振膜302上设置有泄气结构，作为泄气通道，在振动过程中，可以降低振动阻力；在对双振膜MEMS麦克风进行封装时或者双振膜MEMS麦克风发生较大振动等需要平衡内外气压情况时，第一振膜302两侧的气压可以通过泄气结构快速得到平衡，效果更好。可选地，泄气结构包括第一振膜302上开设的多个泄气孔3021，多个泄气孔3021间隔设置于连接单元1的四周。
充分考虑到第二振膜309容易受到多种因素的影响，例如第二振膜309在受到外部高压振动冲击时，第二振膜309边缘部分所受到的应力最大，可选地，第二振膜309和背板单元2之间还设置有环形支撑结构308，环形支撑结构308支撑设置于第二振膜309和背板单元2的外边缘。示例性的，第二振膜309由多晶硅制成，环形支撑结构308由氮化硅制成，第二振膜309与环形支持结构308形成氮化硅与多晶硅的复合结构，环形支撑结构308利用良好的韧性，对第二振膜309起支撑和保护作用，第二振膜309与环形支持结构308的总体厚度为1-2.5um；环形支撑结构308位于外边缘，厚度为0.5-1um，第二振膜309厚度为0.5-1.5um。
可选地，如图23所示，第二振膜309靠近背板单元2的一侧设置有第二褶皱结构3092，降低了应力集中，示例性的，第二褶皱结构3092设置于第二振膜309的边缘位置。
可选地，如图23所示，第二振膜309上开设有释放结构，在形成双振膜MEMS麦克风过程中，用于释放牺牲层。示例性的，释放结构包括第二振膜309上开设的多个释放孔3091，形成双振膜MEMS麦克风后，释放孔3091可以充当泄气结构，提高使用效果；示例性的，多个释放孔3091均匀分布，释放孔3091为直径为0.5um-1um不等的通孔。
可选地，如图19所示，第二振膜309靠近背板单元2的一侧连接有第二突起结构3081，第二突起结构3081与环形支撑结构308的材质相同，第二突起结构3081均匀分布于第二振膜309的下方，防止第二振膜309振动过程中与背板单元2粘在一起，提高了第二振膜309的可靠性。
可选地，如图2所示，双振膜MEMS麦克风还包括第一绝缘层303和第二绝缘层307，第一绝缘层303支撑设置于第一振膜302和背板单元2之间，第二绝缘层307支撑设置于第二振膜309和背板单元2之间。
可选地，背板单元2包括第一背板绝缘层304、第二背板绝缘层306和设置于第一背板绝缘层304与第二背板绝缘层306之间的中间导电层305。可选地，第一背板绝缘层304和第二背板绝缘层306由相同绝缘材料制成，分别沉积。本实施例中，第一背板绝缘层304和第二背板绝缘层306均由氮化硅材质制成，氮化硅具有较高的硬度和强度，使得背板单元2作为固定电极，不易发生变形，从而提高结构的可靠性。示例性的，中间导电层305由多晶硅制成。
示例性的，如图14所示，第一背板绝缘层304和第二背板绝缘层306的厚度均为0.5-2um，中间导电层305的厚度为0.3-1um，背板单元2上均匀分布有声孔3061，背板单元2靠近第一振膜302的一侧设置有第一突起结构3041，本实施例中第一突起结构3041设置于第一背板绝缘层304上，防止第一振膜302振动过程中与背板单元2粘在一起；示例性的，第一突起结构3041均匀分布。
本实施例还提供了一种双振膜MEMS麦克风的制造方法，如图4-图25所示，包括以下步骤：
S1、衬底300上设置有底层绝缘层301，在底层绝缘层301上沉积形成第一振膜302。
S2、在第一振膜302上沉积第一绝缘层303，在第一绝缘层303上刻蚀多组第一通孔组，每组第一通孔组包括至少两个间隔设置的第一通孔3032。
S3、在第一绝缘层303上沉积第一背板绝缘层304，并填充第一通孔3032形成连接柱11。
S4、在第一背板绝缘层304上沉积中间导电层305，在中间导电层305上刻蚀多个第二通孔3051和多个第三通孔3052，多个第三通孔3052与多组第一通孔组一一对应设置。
S5、在中间导电层305上沉积第二背板绝缘层306，并在第二通孔3051和第三通孔3052上沉积第二背板绝缘层306的材料，在第二通孔3051对应的位置蚀刻沉积第二背板绝缘层306和第一背板绝缘层304时的材料形成声孔3061；预设最大外缘，使第一通孔组的多个第一通孔3032均位于最大外缘内，在第三通孔3052与最大外缘形成的第一环形孔3062的位置刻蚀沉积第二背板绝缘层306和第一背板绝缘层304时的材料，第一环形孔3062内的第一背板绝缘层304的材料和第二背板绝缘层306的材料形成连接板13。
S6、在第二背板绝缘层306上沉积第二绝缘层307，在连接板13对应位置 蚀刻第二环形孔3072并在连接板13上形成立柱14。
S7、在第二环形孔3072内填充与第二绝缘层307材质不同的第一种绝缘材料形成连接块12。
S8、在第二绝缘层307上沉积第二振膜309，在第二振膜309沿厚度方向蚀刻释放孔3091。
S9、在衬底300上刻蚀背腔3001，通过释放孔3091对第一绝缘层303的一部分和第二绝缘层307的一部分进行释放，通过背腔3001对底层绝缘层301的一部分进行释放，形成双振膜MEMS麦克风。
通过上述过程，在衬底300和底层绝缘层301上依次形成了第一振膜302、第一绝缘层303、第一背板绝缘层304、中间导电层305、第二背板绝缘层306、第二绝缘层307及第二振膜309，形成了上述的双振膜MEMS麦克风，第一背板绝缘层304、中间导电层305及第二背板绝缘层306形成了背板单元2，还依次形成了连接柱11、连接板13、立柱14及连接块12，形成了连接单元1，使连接单元1穿过背板单元2连接了第一振膜302和第二振膜309，工艺过程简单，通过连接柱11、立柱14、连接块12及连接板13形成的“鼎”型连接单元1结构稳定，提高了双振膜MEMS麦克风的结构稳定性，且生产过程中，避免连接单元1的结构过大而产生较大的牺牲结构，降低了工艺难度。
通过填充第一通孔3032形成连接柱11，工艺简单，结构可靠。
通过上述工艺生产的双振膜MEMS麦克风，保证提高信噪比的同时，不增加芯片面积，提高了使用过程中的可靠性，便于封装。
可选地，如图5和图6所示，在底层绝缘层301上沉积形成第一振膜302之前，还包括：S100、在底层绝缘层301上刻蚀第一凹槽3011，沉积形成第一振膜302的同时填充第一凹槽3011形成第一褶皱结构3022，以降低应力集中。
可选地，如图7所示，在底层绝缘层301上沉积形成第一振膜302后，还包括：S101、在第一振膜302上刻蚀多个泄气孔3021，通过设置泄气孔3021，提高使用效果。第一通孔组与泄气孔3021错开设置。
可选地，如图9和图10所示，在第一振膜302上沉积第一绝缘层303后，还包括：S201、在第一绝缘层303上刻蚀多个第二凹槽3031，第二凹槽3031与第一通孔组错开设置。
所述方法还包括：S301、在第一绝缘层303上沉积第一背板绝缘层304时，填充第二凹槽3031形成第一突起结构3041。
通过设置第二凹槽3031，在第二凹槽3031上形成第一突起结构3041，工 艺简单，结构可靠，通过形成的第一突起结构3041，防止第一振膜302振动过程中与背板单元2粘在一起，即防止第一振膜302与第一背板绝缘层304粘在一起。
可选地，在中间导电层305上沉积第二背板绝缘层306时，主要保证中间导电层305上沉积的第二背板绝缘层306的材料的厚度，与第一背板绝缘层304沉积的厚度相同，使背板单元2两侧对称，结构更稳定。
可选地，如图14所示，在第二背板绝缘层306上沉积第二绝缘层307之前，还包括：
S601、在第二背板绝缘层306上沉积与第一背板绝缘层304和第二背板绝缘层306均不同材质的第二种绝缘材料310，使第二种绝缘材料310填充于声孔3061和第一环形孔3062。
S602、研磨绝缘材料使第二背板绝缘层306露出，并使第二背板绝缘层306与填充的第二种绝缘材料310呈平面结构。
通过第二种绝缘材料310填充声孔3061和第一环形孔3062，以便于后续沉积第二绝缘层307。示例性的，通过化学机械研磨工艺进行第二背板绝缘层306磨平，便于后续沉积，提高结构可靠性和结构精度。
可选的，第二种绝缘材料310与第二绝缘层307材料相同，均为氧化硅，便于后续进行释放。
可选地，如图21和图23所示，在第二背板绝缘层306上沉积第二绝缘层307之后，还包括：S603、在第二绝缘层307上刻蚀多个第三凹槽3073，第三凹槽3073与第二环形孔3072错开设置。
所述方法还包括：S801、在第二绝缘层307上沉积第二振膜309时，填充第三凹槽3073形成第二褶皱结构3092。
通过先形成第三凹槽3073，填充第三凹槽3073形成第二褶皱结构3092，结构可靠，工艺简单。通过第二褶皱结构3092，降低应力集中。
可选地，如图18和图19所示，所述方法还包括：S701、在第二环形孔3072内填充与第二绝缘层307材质不同的第一种绝缘材料时，在第二绝缘层307上沉积一层第一种绝缘材料，刻蚀第一种绝缘材料，使第一种绝缘材料呈环形支撑结构308设置于第二绝缘层307和第二振膜309的外边缘之间。
环形支撑结构308，支撑设置于第二振膜309和背板单元2的外边缘。由于第二振膜309会受到振动冲击作用，边缘部分所受的应力最大，环形支撑结构308能够对第二振膜309起到支撑和保护作用。可选的，第一种绝缘材料为氮化 硅，氮化硅材质具有良好的韧性。
可选地，如图18和图19所示，在第二绝缘层307上蚀刻第三凹槽3073之前，还包括：S6031、在第二绝缘层307上蚀刻第四凹槽3071。
可选地，所述方法还包括：S702、在第二绝缘层307上沉积第一种绝缘材料时，填充第四凹槽3071形成第二突起结构3081。
通过设置第四凹槽3071，在第四凹槽3071上形成第二突起结构3081，结构可靠，工艺简单；第二突起结构3081能够防止第二振膜309振动时，与背板单元2粘在一起，提高可靠性。
可选地，如图21和图22所示，连接块12上具有环形槽121，环形槽121间隔设置于立柱14的外周。
所述方法还包括：S802、在第二绝缘层307上沉积第二振膜309时，填充环形槽121形成填充块15。
由于沉积过程中，将连接块12的表面沉积形成平面的工艺难度较大，因此在连接块12上留有环形槽121，之后再沉积第二振膜309时填充环形槽121形成填充块15，降低了工艺难度，且提高了结构可靠性。

Claims (12)

  1. 一种双振膜微机电***MEMS麦克风，包括背板单元(2)、第一振膜(302)、第二振膜(309)和多个连接单元(1)，所述背板单元(2)绝缘且支撑于所述第一振膜(302)和所述第二振膜(309)之间，所述背板单元(2)与所述第一振膜(302)形成第一可变电容，所述背板单元(2)与所述第二振膜(309)形成第二可变电容，所述背板单元(2)开设有多个通孔，每个连接单元(1)穿设于一个通孔，所述多个通孔与所述多个连接单元(1)一一对应设置，所述多个通孔与所述多个连接单元(1)形成多个第一环形孔(3062)；每个连接单元(1)包括：
    多个连接柱(11)，每个连接柱(11)的一端连接于所述第一振膜(302)朝向所述第二振膜(309)的一侧；
    连接块(12)，所述连接块(12)的一端连接于所述第二振膜(309)朝向所述第一振膜(302)的一侧，所述连接块(12)设置有容纳槽，所述容纳槽的槽口朝向所述第一振膜(302)；
    连接板(13)，设置为连接所述连接块(12)和所述多个连接柱(11)，所述容纳槽与所述连接板(13)形成容纳腔；
    立柱(14)，填充于所述容纳腔；
    所述多个连接柱(11)、所述连接板(13)及所述连接块(12)均为绝缘结构。
  2. 根据权利要求1所述的双振膜MEMS麦克风，其中，所述连接块(12)上设置有环形槽(121)，所述环形槽(121)与所述容纳槽的槽口方向相反，所述环形槽(121)设置于所述容纳槽槽壁的四周，所述环形槽(121)内设置有填充块(15)。
  3. 一种双振膜MEMS麦克风的制造方法，包括：
    衬底(300)上设置有底层绝缘层(301)，在所述底层绝缘层(301)上沉积形成第一振膜(302)；
    在所述第一振膜(302)上沉积第一绝缘层(303)，在所述第一绝缘层(303)上刻蚀多组第一通孔组，每组第一通孔组包括至少两个间隔设置的第一通孔(3032)；
    在所述第一绝缘层(303)上沉积第一背板绝缘层(304)，并填充所述多组第一通孔组形成多个连接柱(11)；
    在所述第一背板绝缘层(304)上沉积中间导电层(305)，在所述中间导电层(305)上刻蚀多个第二通孔(3051)和多个第三通孔(3052)，所述多个第三通孔(3052)与所述多组第一通孔组一一对应设置；
    在所述中间导电层(305)上沉积第二背板绝缘层(306)，并在所述多个第二通孔(3051)和所述多个第三通孔(3052)上沉积所述第二背板绝缘层(306)的材料，在所述多个第二通孔(3051)对应的位置蚀刻沉积所述第二背板绝缘层(306)和所述第一背板绝缘层(304)时的材料形成声孔(3061)；预设最大外缘，使每组第一通孔组的多个第一通孔(3032)均位于所述最大外缘内，在每个第三通孔(3052)与所述最大外缘形成的第一环形孔(3062)的位置刻蚀沉积所述第二背板绝缘层(306)和所述第一背板绝缘层(304)时的材料，所述第一环形孔(3062)内的所述第一背板绝缘层(304)的材料和所述第二背板绝缘层(306)的材料形成连接板(13)；
    在所述第二背板绝缘层(306)上沉积第二绝缘层(307)，在所述连接板(13)对应位置蚀刻第二环形孔(3072)并在所述连接板(13)上形成立柱(14)；
    在所述第二环形孔(3072)内填充与所述第二绝缘层(307)材质不同的第一种绝缘材料形成连接块(12)；
    在所述第二绝缘层(307)上沉积第二振膜(309)，在所述第二振膜(309)沿厚度方向蚀刻释放孔(3091)；
    在所述衬底(300)上刻蚀背腔(3001)，通过所述释放孔(3091)对所述第一绝缘层(303)的一部分和所述第二绝缘层(307)的一部分进行释放，通过所述背腔(3001)对所述底层绝缘层(301)的一部分进行释放，形成双振膜MEMS麦克风。
  4. 根据权利要求3所述的双振膜MEMS麦克风的制造方法，在所述底层绝缘层(301)上沉积形成所述第一振膜(302)之前，还包括：
    在所述底层绝缘层(301)上刻蚀第一凹槽(3011)，沉积形成所述第一振膜(302)的同时填充所述第一凹槽(3011)形成第一褶皱结构(3022)。
  5. 根据权利要求3所述的双振膜MEMS麦克风的制造方法，在所述第一振膜(302)上沉积所述第一绝缘层(303)后，还包括：
    在所述第一绝缘层(303)上刻蚀多个第二凹槽(3031)，所述多个第二凹槽(3031)与所述多组第一通孔组错开设置；
    在所述第一绝缘层(303)上沉积所述第一背板绝缘层(304)时，填充所述多个第二凹槽(3031)形成多个第一突起结构(3041)。
  6. 根据权利要求3所述的双振膜MEMS麦克风的制造方法，其中，在所述中间导电层(305)上沉积所述第二背板绝缘层(306)时，所述中间导电层(305)上沉积的所述第二背板绝缘层(306)的材料的厚度与在所述第一绝缘层(303)上沉积的所述第一背板绝缘层(304)的材料的厚度相同。
  7. 根据权利要求3所述的双振膜MEMS麦克风的制造方法，在所述第二背板绝缘层(306)上沉积所述第二绝缘层(307)之前，还包括：
    在所述第二背板绝缘层(306)上沉积与所述第一背板绝缘层(304)和所 述第二背板绝缘层(306)均不同材质的第二种绝缘材料(310)，使所述第二种绝缘材料(310)填充于所述声孔(3061)和所述第一环形孔(3062)；
    研磨绝缘材料使所述第二背板绝缘层(306)露出，并使所述第二背板绝缘层(306)与填充的所述第二种绝缘材料(310)呈平面结构。
  8. 根据权利要求3所述的双振膜MEMS麦克风的制造方法，在所述第二背板绝缘层(306)上沉积所述第二绝缘层(307)之后，还包括：
    在所述第二绝缘层(307)上刻蚀多个第三凹槽(3073)，所述多个第三凹槽(3073)与所述第二环形孔(3072)错开设置；
    在所述第二绝缘层(307)上沉积所述第二振膜(309)时，填充所述多个第三凹槽(3073)形成第二褶皱结构(3092)。
  9. 根据权利要求8所述的双振膜MEMS麦克风的制造方法，其中，还包括：
    在所述第二环形孔(3072)内填充与所述第二绝缘层(307)材质不同的所述第一种绝缘材料时，在所述第二绝缘层(307)上沉积一层所述第一种绝缘材料，刻蚀所述第一种绝缘材料，使所述第一绝缘材料呈环形支撑结构(308)设置于所述第二绝缘层(307)和所述第二振膜(309)的外边缘之间。
  10. 根据权利要求9所述的双振膜MEMS麦克风的制造方法，在所述第二绝缘层(307)上蚀刻所述多个第三凹槽(3073)之前，还包括：
    在所述第二绝缘层(307)上蚀刻第四凹槽(3071)；
    在所述第二绝缘层(307)上沉积所述第一种绝缘材料时，填充所述第四凹槽(3071)形成第二突起结构(3081)。
  11. 根据权利要求3所述的双振膜MEMS麦克风的制造方法，其中，所述连接块(12)上设置有环形槽(121)，所述环形槽(121)间隔设置于所述立 柱(14)的外周，在所述第二绝缘层(307)上沉积所述第二振膜(309)时，填充所述环形槽(121)形成填充块(15)。
  12. 根据权利要求3所述的双振膜MEMS麦克风的制造方法，在所述底层绝缘层(301)上沉积形成第一振膜(302)后，还包括：在所述第一振膜(302)上刻蚀多个泄气孔(3021)，所述多个泄气孔(3021)与所述多组第一通孔组错开设置。
PCT/CN2023/079374 2022-05-10 2023-03-02 双振膜mems麦克风及其制造方法 WO2023216686A1 (zh)

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