WO2023087647A1 - Microphone mems et son procédé de fabrication - Google Patents

Microphone mems et son procédé de fabrication Download PDF

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Publication number
WO2023087647A1
WO2023087647A1 PCT/CN2022/094592 CN2022094592W WO2023087647A1 WO 2023087647 A1 WO2023087647 A1 WO 2023087647A1 CN 2022094592 W CN2022094592 W CN 2022094592W WO 2023087647 A1 WO2023087647 A1 WO 2023087647A1
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WO
WIPO (PCT)
Prior art keywords
diaphragm
backplane
substrate
forming
mems microphone
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PCT/CN2022/094592
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English (en)
Chinese (zh)
Inventor
冷华星
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无锡华润上华科技有限公司
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Publication of WO2023087647A1 publication Critical patent/WO2023087647A1/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
    • H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor

Definitions

  • the invention relates to the technical field of semiconductor devices, in particular to a MEMS microphone and a method for manufacturing the MEMS microphone.
  • Micro-Electro-Mechanical System (MEMS) devices are usually produced using integrated circuit manufacturing techniques. Silicon-based microphones have broad application prospects in hearing aids and mobile communication equipment.
  • An exemplary MEMS microphone structure is shown in Figure 1, with a deep silicon etch cavity on the backside of the die (DIE).
  • DIE backside of the die
  • the gas passes through the acoustic hole of the microphone and finally exits the device through the deep silicon etch cavity.
  • the manufacturing cost of the MEMS microphone structure with deep silicon etching cavity structure is relatively high.
  • a MEMS microphone comprising: a substrate; a back plate, disposed on the substrate; a plurality of support columns, disposed on the substrate; a diaphragm, disposed on the support columns, each of the support columns
  • the diaphragm is provided with air holes, and the diaphragm is penetrated by the air holes; wherein, the space between the diaphragm and the back plate without each of the support columns forms an airflow channel, the substrate directly below the backplane does not have a cavity, and the backplane and diaphragm form a capacitor.
  • a method for manufacturing a MEMS microphone comprising: forming a back plate on a substrate; forming a sacrificial layer on the back plate; patterning the sacrificial layer to form a plurality of support pillar filling holes; filling the holes in each support pillar forming support columns; forming a diaphragm directly in contact with each support column on the sacrificial layer, and air holes penetrating the diaphragm; removing the sacrificial layer outside the area surrounded by each support column; forming a The first welding pad on the upper surface of the backplane, and the second welding pad located on the upper surface of the diaphragm; removing the sacrificial layer inside the area surrounded by each of the supporting pillars.
  • Fig. 1 is a schematic diagram of an exemplary MEMS microphone structure
  • Fig. 2 is a schematic cross-sectional view of a MEMS microphone structure in an embodiment
  • Fig. 3 is a three-dimensional schematic diagram of a support column under the diaphragm in an embodiment
  • Fig. 4 is the flowchart of the manufacturing method of MEMS microphone in an embodiment
  • 5a to 5g are schematic cross-sectional views of the device structure in the process of manufacturing the MEMS microphone by the manufacturing method shown in FIG. 4 in an embodiment
  • FIG. 6 is a schematic cross-sectional view of a MEMS microphone structure in another embodiment
  • FIG. 7a to 7e are schematic cross-sectional views of the device structure in the process of manufacturing the MEMS microphone by the manufacturing method shown in FIG. 4 in another embodiment.
  • Embodiments of the invention are described herein with reference to cross-section illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the invention. As such, variations from the shapes shown are to be expected due to, for example, manufacturing techniques and/or tolerances. Thus, embodiments of the invention should not be limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle will, typically, have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from implanted to non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation was performed. Thus, the regions shown in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the invention.
  • P+ type simply represents P-type with heavy doping concentration
  • P-type represents medium P-type with doping concentration
  • P-type represents P-type with light doping concentration
  • N+ type represents N-type with heavy doping concentration
  • N-type represents N-type with medium doping concentration
  • N-type represents light-doped concentration Type N.
  • the MEMS microphone structure shown in Figure 1 requires the formation of deep silicon etch cavities.
  • Exemplary deep silicon etching chamber preparation methods include KOH (potassium hydroxide) wet etching and ICP (Inductively Coupled Plasma, inductively coupled plasma) dry etching, both of which are very expensive in terms of individual processing costs.
  • the depth of the deep silicon etch chamber depends on the thickness of the substrate, usually 400 microns.
  • the preparation of the process is usually to thin the wafer from the conventional thickness of 725 microns to 400 microns, and then perform deep silicon etching on the back to form a deep silicon etching cavity.
  • the wafer will become softer, and the warpage of the wafer will become larger, making it difficult to carry out subsequent backside lithography and etching, including wafer transportation and adsorption, which are prone to problems.
  • This thinned thickness restricts the height of the device after packaging (the thickness of the wafer is not less than 400 microns, resulting in a higher height of the device after packaging), and the cost of subsequent laser scribing cannot be reduced due to the thicker wafer.
  • This application removes the deep silicon etching cavity from the design, avoiding this cost.
  • the process can also realize the thinning of the wafer with the maximum thickness, and realize the thinnest substrate as possible.
  • FIG. 2 is a schematic cross-sectional structure diagram of a MEMS microphone in an embodiment. It is a capacitive MEMS microphone, including a substrate 110 , a back plate 130 , a support column 144 and a diaphragm 150 .
  • the backplane 130 is disposed on the substrate 110 .
  • Each support column 144 is disposed on the substrate 110 to support the diaphragm 150 .
  • the support columns 144 are distributed around the edge of the diaphragm 150 , as shown in FIG. 3 .
  • each support column 144 is transparently processed.
  • the diaphragm 150 and the back plate 130 form a flat plate capacitor, and the diaphragm 150 and the back plate 130 serve as the upper and lower plates of the capacitor respectively.
  • the air hole 151 is provided through the diaphragm 150 , and the airflow can pass through the diaphragm 150 through the air hole 151 and flow out from the side of the support post 144 (through the gap between the support post and other support posts). Since the sides are used as gas flow channels, no cavities (deep etch cavities) are provided on the substrate 110 directly below the back plate 130 .
  • the airflow with sound waves can enter from the air hole 151 and flow out from the airflow channel between the diaphragm 150 and the backplate 130, so the substrate 110 directly below the backplate 130 is not provided with a deep etching cavity, which can save etching.
  • the cost of etching to form a deep etch cavity because the substrate 110 under the back plate 130 is a solid structure without a cavity, the substrate 110 will not be too soft and warped if it is thinned to a very thin thickness, thereby reducing the scribing cost.
  • the material of the substrate 110 is Si. In other embodiments, the material of the substrate 110 may also be other semiconductors or semiconductor compounds, such as one of Ge, SiGe, SiC, SiO 2 or Si 3 N 4 .
  • FIG. 6 is a schematic cross-sectional view of a MEMS microphone structure in another embodiment.
  • the main difference between it and the embodiment shown in FIG. 2 is that, compared with the structure shown in FIG. 6, FIG. 2 adds a dielectric layer 142 disposed on the back plate 130 , one end of each supporting column 144 is in direct contact with the dielectric layer 142 , and the other end is in direct contact with the diaphragm 150 .
  • an insulating layer 120 is further provided between the substrate 110 and the backplane 130 .
  • the insulating layer 120 is used to insulate the substrate 110 and the backplane 130 from each other.
  • the material of the insulating layer 120 is silicon oxide, such as silicon dioxide.
  • the diaphragm 150 is a flexible film
  • the back plate 130 is a rigid film.
  • the vibrating membrane 150 is a layer of flexible film with tensile stress and conductivity, which can deform to a certain extent when the surrounding air vibrates, and forms a flat capacitor together with the back plate 130 as one pole of the flat capacitor. Since the substrate under the backplane 130 is not provided with a deep etching cavity, the backplane 130 is no longer separated from the substrate 110 (and the insulating layer 120 ), and the backplane 130 is fixed by the substrate 110 so that the diaphragm 150 is fixed when it vibrates.
  • the substrate 110 forms a good support for the back plate 130 , so it is no longer necessary to place a large stress on the back plate 130 to ensure that the diaphragm 150 remains stationary when it vibrates.
  • the diaphragm 150 is softer than the back plate 130 .
  • the air hole 151 is a circular air hole located in the middle of the diaphragm 150 .
  • a plurality of air holes 151 penetrating the vibrating membrane 150 can also be provided, and the air holes 151 can be in other shapes, such as oval, square or irregular patterns, and the specific shape and quantity of the air holes 151 can vary according to different devices. Depending on performance requirements.
  • each air hole 151 is located in the area surrounded by the orthographic projection of each supporting column 144 on the diaphragm 150 .
  • the diaphragm 150 and the back plate 130 are both conductive materials.
  • the diaphragm 150 and the back plate 130 may also be a composite layer structure including a conductive layer, such as one or more of the following materials: Si, Ge, SiGe, SiC, Al, W, Ti , or Al/W/Ti nitrides.
  • the material of the diaphragm 150 includes polysilicon.
  • the material of the backplane 130 includes polysilicon.
  • FIG. 2 is an example of some main structures of the MEMS microphone, and the MEMS microphone may have other structures besides the structures shown in the figure.
  • the diaphragm 150 has a circular cross section.
  • the cavity between the diaphragm 150 and the dielectric layer 142 is formed by releasing the sacrificial layer. During the release process, the sacrificial layer at the position of the cavity is corroded, thereby forming cavity. In one embodiment of the present application, the release of the sacrificial layer is accomplished by wet etching.
  • the etching solution for wet etching is BOE (Buffered Oxide Etch, buffered oxide etching solution), and the dielectric layer 142 and each support pillar 144 are made of materials resistant to corrosion by the buffered oxide etching solution.
  • the material of the dielectric layer 142 and each support pillar 144 is silicon nitride.
  • the MEMS microphone further includes a first solder pad 162 disposed on the upper surface of the back plate 130 , and a second solder pad 164 disposed on the upper surface of the diaphragm 150 .
  • both the first pad 162 and the second pad 164 are made of metal, the first pad 162 is electrically connected to the backplane 130, and the second pad 164 is electrically connected to the diaphragm 150 .
  • the first pad 162 and the second pad 164 can lead out the back plate 130 /diaphragm 150 when the MEMS microphone package is bonded.
  • Fig. 4 is the flowchart of the manufacturing method of MEMS microphone in an embodiment, comprises the following steps:
  • polysilicon may be deposited as the backplane 130 .
  • a step of forming an insulating layer 120 on the substrate 110 is also included.
  • Polysilicon is deposited on the insulating layer 120 .
  • the insulating layer 120 is formed by depositing silicon dioxide. In other embodiments, the insulating layer 120 may also be formed by thermal growth.
  • the material of the substrate 110 is Si. In other embodiments, the material of the substrate 110 may also be other semiconductors or semiconductor compounds, such as one of Ge, SiGe, SiC, SiO 2 or Si 3 N 4 .
  • a step of forming a dielectric layer 142 on the backplane 130 is also included.
  • the dielectric layer 142 is made of BOE corrosion resistant material.
  • silicon nitride can be deposited on the backplane 130, and then the silicon nitride layer can be patterned (specifically, a photoresist can be coated on the silicon nitride layer, and then a corresponding photoresist plate can be used to expose the photoresist. develop, and etch the silicon nitride layer, and then remove the photoresist), to obtain the dielectric layer 142 .
  • the dielectric layer 142 may not be provided, and the structure obtained after step S420 is as shown in FIG. 7 a .
  • silicon dioxide may be deposited on the backplane 130 and the dielectric layer 142 as the sacrificial layer 141 .
  • a photoresist is coated on the sacrificial layer 141, and then a corresponding photoresist is used to expose the photoresist for development, and the sacrificial layer 141 is etched, and then the photoresist is removed.
  • a support column filling hole 143 is formed at the position where the support column needs to be provided, as shown in FIG. 5c.
  • step S430 For the embodiment without the dielectric layer 142, the structure obtained after step S430 is as shown in FIG. 7b.
  • a material resistant to BOE corrosion is deposited on the surface of the wafer, and the material is filled into each support column filling hole 143 to form a support column, as shown in FIG. 5d.
  • the material resistant to BOE corrosion may be silicon nitride. Excess (ie, on sacrificial layer 141 ) silicon nitride may be removed after deposition.
  • step S440 For the embodiment without the dielectric layer 142, the structure obtained after step S440 is as shown in FIG. 7c.
  • polysilicon is deposited on the sacrificial layer 141, and then the deposited polysilicon is patterned to obtain a diaphragm 150, as shown in FIG. 5e.
  • a photoresist may be coated on the polysilicon, and then a corresponding photoresist is used to expose the photoresist for development, and the polysilicon is etched to obtain the diaphragm 150, and then the photoresist is removed.
  • An air hole 151 is formed at the center of the diaphragm 150 .
  • step S450 For the embodiment without the dielectric layer 142, the structure obtained after step S450 is as shown in FIG. 7d.
  • the sacrificial layer 141 outside each support pillar 144 is removed by an etching process, and the sacrificial layer 141 inside each support pillar 144 remains.
  • the remaining sacrificial layer 141 can block the air hole 151 at the bottom of the air hole 151, so as to prevent the pad material deposited in the subsequent process from filling through the air hole 151 (accumulating on the dielectric layer 142).
  • step S460 For the embodiment without the dielectric layer 142, the structure obtained after step S460 is as shown in FIG. 7e.
  • a metal layer is deposited, and then the first pad 162 on the upper surface of the backplane 130 and the first pad 162 on the upper surface of the diaphragm 164 are formed by pad (PAD) metal lithography and etching.
  • the second pad 164 refer to FIG. 5g.
  • the first pad 162 is electrically connected to the back plate 130
  • the second pad 164 is electrically connected to the diaphragm 150 .
  • the first pad 162 and the second pad 164 can lead out the back plate 130 /diaphragm 150 when the MEMS microphone package is bonded.
  • the sacrificial layer 141 inside the supporting pillars is removed by wet etching.
  • the remaining sacrificial layer 141 is released by BOE etching to obtain the structure shown in FIG. 2 .
  • step S480 is as shown in FIG. 6 .
  • a step of thinning the backside of the substrate 110 is also included to reduce the thickness of the substrate 110 to a required thickness.
  • the airflow with sound waves can enter from the air hole 151 and flow out from the airflow channel between the diaphragm 150 and the back plate 130, so the above manufacturing method is not directly under the back plate 130
  • the substrate 110 is provided with a deep etch cavity, which can save the cost of etching to form the deep etch cavity.
  • the substrate 110 under the back plate 130 is a solid structure without a cavity, the substrate 110 will not be too soft and warped if it is thinned to a very thin thickness, thereby reducing the scribing cost.
  • the diaphragm 150 is a flexible film
  • the back plate 130 is a rigid film.
  • the vibrating membrane 150 is a layer of flexible film with tensile stress and conductivity, which can deform to a certain extent when the surrounding air vibrates, and forms a flat capacitor together with the back plate 130 as one pole of the flat capacitor. Since the substrate under the backplane 130 is not provided with a deep etching cavity, the backplane 130 is no longer separated from the substrate 110 (and the insulating layer 120 ), and the backplane 130 is fixed by the substrate 110 so that it is fixed when the diaphragm 150 vibrates.
  • the substrate 110 forms a good support for the back plate 130 , so it is no longer necessary to place a large stress on the back plate 130 to ensure that the diaphragm 150 remains stationary when it vibrates.
  • the diaphragm 150 is softer than the back plate 130 .

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

Abstract

L'invention concerne un microphone MEMS et son procédé de fabrication. Le microphone MEMS comprend un substrat (110) ; une plaque arrière (130) disposée sur le substrat (110) ; une pluralité de colonnes de support (144) disposées sur le substrat (110) ; et une membrane (150) disposée sur les colonnes de support (144), chacune des colonnes de support (144) étant utilisée pour supporter la membrane (150) ; la membrane (150) est pourvue d'un trou d'air (151), et pénètre dans la membrane (150) ; un canal d'écoulement d'air est formé dans un espace situé entre la membrane (150) et la plaque arrière (130) et dépourvu de colonne de support (144) ; le substrat (110) situé directement sous la plaque arrière (130) n'est pas pourvu d'une cavité ; et la plaque arrière (130) et la membrane (150) forment un condensateur.
PCT/CN2022/094592 2021-11-16 2022-05-24 Microphone mems et son procédé de fabrication WO2023087647A1 (fr)

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CN202111354745.4 2021-11-16
CN202111354745.4A CN116137694A (zh) 2021-11-16 2021-11-16 Mems麦克风及其制造方法

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050152571A1 (en) * 2004-01-13 2005-07-14 Chao-Chih Chang Condenser microphone and method for making the same
WO2011068344A2 (fr) * 2009-12-01 2011-06-09 (주)세미로드 Microphone mems et procédé de fabrication associé
CN109987573A (zh) * 2019-04-02 2019-07-09 武汉耐普登科技有限公司 半导体结构及其制造方法
CN111405444A (zh) * 2020-03-20 2020-07-10 西人马（厦门）科技有限公司 一种振膜带孔的电容式麦克风及其制造方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050152571A1 (en) * 2004-01-13 2005-07-14 Chao-Chih Chang Condenser microphone and method for making the same
WO2011068344A2 (fr) * 2009-12-01 2011-06-09 (주)세미로드 Microphone mems et procédé de fabrication associé
CN109987573A (zh) * 2019-04-02 2019-07-09 武汉耐普登科技有限公司 半导体结构及其制造方法
CN111405444A (zh) * 2020-03-20 2020-07-10 西人马（厦门）科技有限公司 一种振膜带孔的电容式麦克风及其制造方法

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