MEMS Microphone and Its Manufacturing Method

Abstract

The present invention discloses a MEMS microphone and a manufacturing method thereof. The method includes: sequentially forming a first isolation layer, a diaphragm, and a second isolation layer on a substrate; sequentially forming a first protective layer, a backplate electrode, and a second protective layer on the second isolation layer; forming a release hole penetrating through the first protective layer, the backplate electrode, and the second protective layer; forming a sound cavity penetrating through the substrate; releasing the diaphragm via the sound cavity and the release hole; and forming a groove on the first isolation layer, and the diaphragm conformally covers the surface of the first isolation layer to form a spring structure at the position of the groove. In the etching step of releasing the diaphragm, the present invention uses the first protective layer and the second protective layer to protect the backplate electrode, so that the backplate electrode is not corroded when the diaphragm is released, improving the performance and reliability of the device. And by forming a spring structure on the diaphragm, the stress of the diaphragm is effectively released, improving the sensitivity of the MEMS microphone.

Description

Technical Field

[0001] The present invention belongs to the technical field of micromicrophones, and more specifically, relates to a MEMS microphone and a manufacturing method thereof. Background Art

[0002] A MEMS microphone is a capacitive microphone manufactured using semiconductor technology. A MEMS microphone is a MEMS (Micro-Electro-Mechanical System) device manufactured using micromachining technology. Due to the advantages of small size, high sensitivity, and good compatibility with existing semiconductor technologies, MEMS microphones are increasingly widely used in mobile terminals such as mobile phones. The structure of a MEMS microphone includes a diaphragm and a backplate electrode that face each other, and the two are respectively connected to corresponding electrodes via conductive channels. An isolation layer is also included between the diaphragm and the backplate electrode. The isolation layer is used to separate the diaphragm and the backplate electrode, and a cavity is formed therein to provide the vibration space required for the diaphragm.

[0003] In existing MEMS microphones, silicon nitride is used as the material for the backplate electrode. The silicon nitride layer has good rigidity and can obtain good acoustic performance. However, in the case where the design spacing between the diaphragm and the backplate electrode is small, during the step of wet-etching the isolation layer to form a cavity and during the application of the MEMS microphone, adhesion is likely to occur between the diaphragm and the backplate electrode, resulting in device failure and a reduction in the yield rate. The adhesion of microstructures in MEMS microphones has become the main reason for the rejection of finished products during the micromachining and application processes of MEMS microphones, severely restricting the development and industrial application of MEMS microphones.

[0004] As a further improved method, a method of HF acid vapor fumigation is used to remove a part of the isolation layer to form a cavity. However, HF vapor fumigation will corrode the backplate electrode, resulting in device failure and a reduction in the yield rate.

[0005] There is an expectation to further improve the manufacturing method of MEMS microphones to improve the yield rate and the reliability of device performance. Summary of the Invention

[0006] The object of the present invention is to provide a MEMS microphone and a manufacturing method thereof, wherein a protective layer is formed on the surfaces of the backplate electrodes facing each other, so as to protect the backplate electrodes during the etching step of releasing the diaphragm, and after releasing the diaphragm, a monolayer organic film is formed at least on the exposed surface of the diaphragm, thereby improving the yield rate and the reliability of device performance.

[0007] According to one aspect of the present invention, there is provided a method for manufacturing a MEMS microphone, comprising: sequentially forming a first isolation layer, a diaphragm, and a second isolation layer on a substrate; sequentially forming a first protective layer, a backplate electrode, and a second protective layer on the second isolation layer; forming a release hole penetrating through the first protective layer, the backplate electrode, and the second protective layer; forming an acoustic cavity penetrating through the substrate; releasing the diaphragm via the acoustic cavity and the release hole; and further comprising, between the steps of forming the first isolation layer and the diaphragm: forming a groove on the surface of the first isolation layer, the diaphragm conformally covering the surface of the first isolation layer, and forming a spring structure at the position of the groove.

[0008] Preferably, in the step of releasing the diaphragm, a part of the first isolation layer is removed via the acoustic cavity, and a part of the second isolation layer is removed via the release hole, so as to expose a first surface and a second surface of the diaphragm that are opposite to each other.

[0009] Preferably, in the step of releasing the diaphragm, HF acid is used as an etchant, the diaphragm is used as a stop layer, and the first protective layer and the second protective layer are used to protect the backplate electrode.

[0010] Preferably, after the step of releasing the diaphragm, at least a monolayer organic film is formed on the exposed surface of the diaphragm.

[0011] Preferably, it further comprises: forming at least one additional film of a metal oxide film or a silicon oxide film on the surface of the monolayer organic film, the additional film and the monolayer organic film forming a stacked structure.

[0012] Preferably, in the step of releasing the diaphragm, a cavity is formed between the first protective layer and the diaphragm.

[0013] Preferably, the monolayer organic film covers the external surface of the MEMS microphone and the internal surface communicating with the external environment.

[0014] Preferably, in the step of forming the monolayer organic film, the monolayer organic film covers the exposed surface of the first protective layer in the cavity.

[0015] Preferably, the diaphragm and the backplate electrode are respectively composed of doped polysilicon.

[0016] Preferably, each of the first protective layer and the second protective layer is composed of any one selected from silicon nitride, boron nitride, and silicon carbide.

[0017] Preferably, the spring structure of the diaphragm is a concentric annular corrugated part or a spiral corrugated part.

[0018] Preferably, the concentric annular spring structure includes 1 to 6 circular rings.

[0019] Preferably, the spiral spring structure includes at least one spiral thread that radiates outward from the middle part of the diaphragm.

[0020] Preferably, it further includes: forming a reinforcing rib at the peripheral part of the diaphragm.

[0021] Preferably, the reinforcing rib of the diaphragm is a radial strip beam or a parapet structure located at the peripheral part.

[0022] Preferably, it further includes: forming a discontinuous area in a partial area of the peripheral part of the diaphragm.

[0023] Preferably, a plurality of protrusions are formed on the surface of the first protective layer facing the diaphragm to prevent adhesion between the backplate electrode and the diaphragm.

[0024] Preferably, between the steps of forming the backplate electrode and the second protective layer, it further includes: patterning the backplate electrode.

[0025] Preferably, it further includes: forming a first conductive channel that passes through the second protective layer, the first protective layer, and the second isolation layer to reach the surface of the diaphragm in the area where a part of the backplate electrode is removed by patterning; and forming a second conductive channel that passes through the second protective layer to reach the surface of the backplate electrode in the area where another part of the backplate electrode is retained by patterning.

[0026] Preferably, the monomolecular layer organic film is composed of any one of organosilane and organosiloxane.

[0027] Preferably, the backplate electrode is formed above the movable area of the diaphragm, and the area of the backplate electrode is less than or equal to the area of the movable area of the diaphragm.

[0028] Preferably, the area of the backplate electrode is less than or equal to the minimum cross-sectional area of the acoustic cavity.

[0029] Preferably, the radius of the minimum cross-section of the acoustic cavity is 385 μm to 415 μm.

[0030] Preferably, the thicknesses of the first protective layer and the second protective layer are different.

[0031] Preferably, the thickness of the first protective layer is 800 Å to 1500 Å, and the thickness of the second protective layer is 0.1 μm to 1.0 μm.

[0032] Preferably, the materials of the first protective layer and the second protective layer are different.

[0033] According to another aspect of the present invention, there is provided a MEMS microphone, comprising: a first isolation layer, a diaphragm, and a second isolation layer sequentially formed on a substrate; a first protective layer, a backplate electrode, and a second protective layer sequentially formed on the second isolation layer; a release hole penetrating through the first protective layer, the backplate electrode, and the second protective layer; a cavity penetrating through the second isolation layer, the cavity being in communication with the release hole; a sound cavity penetrating through the substrate and the first isolation layer; and a spring structure provided on the surface of the diaphragm, and a first surface and a second surface of the diaphragm opposite to each other are respectively exposed through the cavity and the sound cavity.

[0034] Preferably, it further comprises a monolayer organic film covering at least the exposed surface of the diaphragm.

[0035] Preferably, during the vibration of the diaphragm, the sound cavity and the release hole serve as air flow channels.

[0036] Preferably, it further comprises at least one additional film of a metal oxide film or a silicon oxide film on the surface of the monolayer organic film, and the additional film and the monolayer organic film form a laminated structure.

[0037] Preferably, the monolayer organic film covers the outer surface of the MEMS microphone and the inner surface communicating with the external environment.

[0038] Preferably, the monolayer organic film covers the exposed surface of the first protective layer in the cavity.

[0039] Preferably, the diaphragm and the backplate electrode are respectively composed of doped polysilicon.

[0040] Preferably, each of the first protective layer and the second protective layer is composed of any one selected from a silicon nitride layer, a boron nitride layer, and a silicon carbide layer, and the materials of the first protective layer and the second protective layer are different.

[0041] Preferably, the spring structure of the diaphragm is a concentric annular corrugated portion or a spiral corrugated portion.

[0042] Preferably, the concentric annular spring structure includes 1 to 6 circular rings.

[0043] Preferably, the spiral spring structure includes at least one spiral line radiating outward from the middle portion of the diaphragm.

[0044] Preferably, it further comprises: forming a reinforcing rib on the peripheral portion of the diaphragm.

[0045] Preferably, the reinforcing ribs of the diaphragm are radially strip-shaped beams or parapet structures located in the peripheral part.

[0046] Preferably, it further includes: forming a discontinuous region in a partial area of the peripheral part of the diaphragm.

[0047] Preferably, it further includes: a first conductive channel passing through the second protective layer, the first protective layer, and the second isolation layer to reach the surface of the diaphragm; and a second conductive channel passing through the second protective layer to reach the surface of the backplate electrode.

[0048] Preferably, the monolayer organic film is composed of any one of an organosilane layer and an organosiloxane layer.

[0049] Preferably, a plurality of protrusions are formed on the surface of the first protective layer facing the diaphragm to prevent adhesion between the backplate electrode and the diaphragm.

[0050] Preferably, the backplate electrode is formed above the movable area of the diaphragm, and the area of the backplate electrode is less than or equal to the area of the movable area of the diaphragm.

[0051] Preferably, the area of the backplate electrode is less than or equal to the minimum cross-sectional area of the sound cavity.

[0052] Preferably, the area of the backplate electrode is 70% - 100% of the movable area.

[0053] Preferably, the diaphragm further includes an intermediate part and a peripheral part connected by the spring structure, and the movable area of the diaphragm includes the area of the intermediate part and the area of the spring structure.

[0054] Preferably, the radius of the minimum cross-section of the sound cavity is 385 microns - 415 microns.

[0055] Preferably, the thickness of the backplate electrode is 0.3 microns - 1.0 microns.

[0056] Preferably, the thicknesses of the first protective layer and the second protective layer are different.

[0057] Preferably, the thickness of the first protective layer is 800 Å - 1500 Å, and the thickness of the second protective layer is 0.1 microns - 1.0 microns.

[0058] Preferably, the thickness of the monolayer organic film layer is 1 nm - 10 nm.

[0059] The manufacturing method of the MEMS microphone according to the embodiment of the present invention. In the etching step of releasing the diaphragm of the present invention, the backplate electrode is protected by the first protective layer and the second protective layer, so that the backplate electrode is not corroded when the diaphragm in the device structure is released, improving the performance and reliability of the device. And by forming a groove on the surface of the first isolation layer between the steps of forming the first isolation layer and the diaphragm, the diaphragm conformally covers the surface of the first isolation layer to form a spring structure at the position of the groove.

[0060] Further, the spring structure of the diaphragm is a concentric annular corrugated part or a spiral corrugated part, and the spring structure of the diaphragm effectively releases the stress of the diaphragm, improving the sensitivity of the MEMS microphone.

[0061] In a preferred embodiment, after releasing the diaphragm, at least a monolayer organic film is formed on the exposed surface of the diaphragm. By utilizing the hydrophobicity and low surface adhesion of the monolayer organic film, the adhesion between the diaphragm and the backplate electrode can be effectively reduced or prevented, thereby improving the yield and the reliability of the device performance. The monolayer organic film does not cause obvious adverse effects on the electrical performance of the MEMS microphone, thus meeting the device performance requirements.

[0062] MEMS microphone

[0063] In a preferred embodiment, in the etching step of releasing the diaphragm, the formed release holes and the acoustic cavity are used as the supply channels for the reaction gas, so that the reaction gas can easily enter the internal cavity of the MEMS microphone. Therefore, the monolayer organic film can be formed on the internal surface of the MEMS microphone to form a high-quality anti-adhesion layer.

[0064] In a preferred embodiment, by making the area of the backplate electrode less than or equal to the area of the movable region of the diaphragm, the influence of the parasitic capacitance that makes no contribution to the sensitivity of the MEMS microphone can be reduced. Even in the presence of process fluctuations, since the backplate only needs to be aligned with the movable region of the diaphragm, it is easy to align the two, so the invalid capacitance component is removed from the detection signal, and the sensitivity of the detection signal is only related to the effective capacitance component, thereby improving the sensitivity of the MEMS microphone.

[0065] In a preferred embodiment, by making the area of the backplate electrode less than or equal to the cross-sectional area of the acoustic cavity, the problem of the reliability decline of the MEMS microphone caused by process fluctuations in mass production is avoided, improving the overall performance of the product.

[0066] In a preferred embodiment, the materials of the first protective layer and the second protective layer are different, and the corrosion resistance of the backplate electrode can be improved.

[0067] In a preferred embodiment, the diaphragm also includes reinforcing ribs located at the peripheral portion of the diaphragm, which can improve the elastic properties of the diaphragm, control the vibration area, improve the elastic coefficient of the membrane structure, and improve the resonant frequency of the mechanical structure to meet the performance design requirements of the MEMS microphone.

[0068] In a preferred embodiment, part of the peripheral area of ​​the diaphragm is a discontinuous area. The discontinuous area of ​​the diaphragm and the upper and lower dielectric layers cannot form a capacitor structure, thereby reducing the parasitic capacitance that is detrimental to the sensitivity of the microphone. At the same time, the discontinuous area can release part of the diaphragm stress, effectively improving the sensitivity of the diaphragm.

[0069] MEMS microphone Further, each step of the method is compatible with existing semiconductor processes, especially CMOS processes, and therefore can be used for large-scale and low-cost production. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0071] Figure 1 is a schematic flow chart of a method for manufacturing a MEMS microphone according to an embodiment of the present invention;

[0072] Figures 2 to 14 is a schematic cross-sectional view of a device corresponding to each step in a method for manufacturing a MEMS microphone according to an embodiment of the present invention;

[0073] Figure 15a A schematic structural diagram of a diaphragm of a MEMS microphone according to an embodiment of the present invention is shown; Figure 15b A schematic structural diagram of another diaphragm of a MEMS microphone according to an embodiment of the present invention is shown;

[0074] Figure 16a A schematic structural diagram of a diaphragm of a MEMS microphone according to another embodiment of the present invention is shown; Figure 16b A schematic structural diagram of another diaphragm of a MEMS microphone according to another embodiment of the present invention is shown;

[0075] Figure 17a A schematic structural diagram of a diaphragm of a MEMS microphone according to another embodiment of the present invention is shown; Figure 17b A schematic structural diagram of another diaphragm of a MEMS microphone according to yet another embodiment of the present invention is shown. DETAILED DESCRIPTION

[0076] Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. In the respective drawings, the same elements are denoted by the same or similar reference numerals. For the sake of clarity, the various parts in the drawings are not drawn to scale.

[0077] The present invention can be presented in various forms, and some examples will be described below.

[0078] Figure 1 As shown, the manufacturing method of the MEMS microphone according to this embodiment may include the following steps.

[0079] In step S01, a first isolation layer 102 is formed on a substrate 101, as Figure 2 shown.

[0080] In this embodiment, the substrate 101 is, for example, a <100>-oriented silicon wafer substrate. Optionally, the substrate is doped with N-type. The first isolation layer is, for example, a silicon oxide layer. For example, a silicon oxide layer is formed on the substrate 101 by thermal oxidation or chemical vapor deposition (CVD) as the first isolation layer 102.

[0081] A part of the first isolation layer 102 will serve as a sacrificial layer for forming a part of the acoustic cavity under the diaphragm, and also the thickness of the first isolation layer 102 is used to define the spacing between the diaphragm and the substrate. The thickness of the first isolation layer 102 is, for example, 0.5 micrometers to 2 micrometers.

[0082] In step S02, a wavy groove 131 is formed on the surface of the first isolation layer 102, as Figure 3 shown.

[0083] In this embodiment, a resist layer is formed on the surface of the first isolation layer 102, and a pattern including openings is formed in the resist layer by photolithography. Using the resist layer as a mask, the exposed portion of the first isolation layer 102 is removed by a selective etchant. By controlling the etching time, this etching can stop at a predetermined depth of the first isolation layer 102. After etching, the resist layer can be removed by ashing or dissolution in a solvent.

[0084] The groove 131 opens on the surface of the first isolation layer 102 and extends downward. Viewed from the surface of the first isolation layer 102, the shape of the groove 131 is a concentric ring shape, for example, including 1 to 6 nested circular rings. Viewed from the cross-section of the first isolation layer 102, the shape of the groove 131 is a substantially trapezoidal or V-shaped with a bottom surface size smaller than the opening surface size. The depth of the groove 131 is, for example, 0.5 micrometers to 0.8 micrometers. Preferably, the opening surface of the groove 131 forms a smooth curved surface with the surface of the first isolation layer 102. The groove 131 is used to define the spring structure of the diaphragm to be formed in the subsequent steps.

[0085] In step S03, a conformal diaphragm 104 is formed on the first isolation layer 102, as Figure 4 shown.

[0086] In this embodiment, the diaphragm 104 is composed of, for example, doped polysilicon. For example, polysilicon is deposited on the first isolation layer 102 by Low Pressure Chemical Vapor Deposition (LPCVD), and the deposition temperature is, for example, 570 degrees Celsius to 630 degrees Celsius, thereby forming the diaphragm 104. The first part of the diaphragm 104 covers the surface of the first isolation layer 102, and the second part continuously and conformally covers the bottom surface and side walls of the groove 131, thereby forming the spring structure 103. The thickness of the diaphragm 104 is, for example, 0.3 micrometers to 1 micrometer, preferably 0.4 micrometers. The first part of the diaphragm 104 includes an intermediate part 104a and a peripheral part 104c, and the spring structure 103 connects the intermediate part 104a and the peripheral part 104c. The intermediate part 104a of the diaphragm 104 and the spring structure 103 constitute the movable area of the diaphragm 104.

[0087] In this embodiment, both the intermediate part 104a and the peripheral part 104c of the diaphragm 104 are flat surfaces, and the spring structure 103 of the diaphragm 104 is a concentric annular corrugated part. In an alternative embodiment, the spring structure 103 of the diaphragm 104 is a spiral corrugated part (as Figure 15a , 15b shown). In these two embodiments, Figure 15a the threads of the spring structure are dense, and the curvature radius of the spiral threads does not change with position. Figure 15b the threads of the spring structure are sparse, and the curvature radius of the spiral threads changes with position. These two embodiments can be selected according to the requirements of actual applications. Compared with the diaphragm with a flat surface, the diaphragm 104 with a spring structure formed on its surface can improve the elastic characteristics of the diaphragm, can control the vibration area, improve the elastic coefficient of the membrane structure, and meet the performance design requirements of the MEMS microphone. In an alternative embodiment, the intermediate part of the diaphragm 104 is recessed downward, and the depth of the downward recess of the intermediate part is the same as the depth of the spiral threads of the spring structure. In a preferred embodiment, the curvature radius of each spiral thread is the same. In an alternative embodiment, the spring structure is located throughout the diaphragm 104, that is, the intermediate part and the peripheral part of the diaphragm 104 are provided with a spring structure. The stress of the diaphragm is effectively released, and the sensitivity of the MEMS microphone is improved.

[0088] Preferably, wirings connected to the diaphragm 104 can also be formed in this step. For example, a polysilicon layer is patterned by lithography and etching steps, so that different regions of the polysilicon layer are respectively formed into patterns of the diaphragm and the wirings.

[0089] In a preferred embodiment, the diaphragm 104 further includes reinforcing ribs formed in the peripheral portion 104c (as Figure 16a , 16b shown). As Figure 16a shown, the reinforcing ribs 1041 of the diaphragm 104 are, for example, radially bar-shaped beams or parapet structures located in the peripheral portion 104c. The parapet structure includes a plurality of annular sections. The plurality of annular sections have the same radius and the morphology of the annular section is rectangular wave-shaped. In an alternative embodiment, the diaphragm 104 further includes reinforcing ribs 1042 formed in the peripheral portion 104c (as Figure 16b shown). The reinforcing ribs 1042 of the diaphragm 104 include a plurality of annular sections. The plurality of annular sections have the same radius and there are arcs at the corners of the annular sections, trapezoidal waves with inclination, sine waves, and so on. Compared with the diaphragm 104 with a flat surface, the diaphragm 104 with a spring structure 104b and reinforcing ribs formed on the surface can improve the elastic characteristics of the diaphragm, can control the vibration area, improve the elastic coefficient of the membrane structure, improve the resonance frequency of the mechanical structure, and meet the performance design requirements of the MEMS microphone. In a preferred embodiment, the reinforcing ribs formed by the diaphragm 104 in the peripheral portion 104c are parapet structures. The parapet structures include a plurality of annular sections. The plurality of annular sections can include at least two of rectangular wave-shaped, arcs at the corners of the annular sections, trapezoidal waves with inclination or sine waves.

[0090] In a preferred embodiment, some regions of the peripheral portion 104c of the diaphragm 104 are discontinuous regions (as Figure 17a , 17b shown). As Figure 17a shown, the edge of the peripheral portion of the diaphragm 104 is discontinuous. Specifically, the edge of the peripheral portion 104c is serrated, and a plurality of notches 1043 of the serration form a discontinuous region. In an alternative embodiment, as Figure 17b shown, the discontinuous region of the peripheral portion 104c of the diaphragm 104 includes a hollowed-out structure. Specifically, the hollowed-out structure includes a plurality of through holes 1044. The through holes 1044 are circular, trapezoidal or polygonal. Among them, in this embodiment, the through holes 1044 are in a shape similar to a sector. The plurality of through holes 1044 are formed in a cross-arrangement in the peripheral portion region of the diaphragm 104. Further, the shape of the diaphragm 104 is a sunflower shape. More specifically, the edge of the diaphragm 104 is connected by a plurality of arc edges. In step S04, a second isolation layer 105 is formed on the diaphragm 104, as Figure 5 shown.

[0091] In this embodiment, the second isolation layer 105 is, for example, a silicon oxide layer. For example, a silicon oxide layer is formed on the diaphragm 104 by means of Low Pressure Chemical Vapor Deposition (LPCVD) or Plasma Enhanced Chemical Vapor Deposition (PECVD) as the second isolation layer 105.

[0092] A part of the second isolation layer 105 will serve as a sacrificial layer for forming a cavity above the diaphragm 104, and the thickness of the second isolation layer 105 is also used to define the spacing between the diaphragm and the backplate electrode. The thickness of the second isolation layer 105 is selected according to the electrical and acoustic performance of the MEMS microphone, for example, it is 2 micrometers to 4 micrometers.

[0093] In step S05, a first protective layer 106 is formed on the second isolation layer 105, as Figure 6 shown.

[0094] The first protective layer 106 is composed of, for example, any one of silicon nitride, boron nitride, and silicon carbide. In this embodiment, the first protective layer 106 is, for example, a boron nitride layer. For example, a boron nitride layer is formed on the second isolation layer 105 by means of hot-wire assisted Plasma Enhanced Chemical Vapor Deposition (PECVD), where N 2 , H 2 , and B 2 diluted by H 2 H 6 are used as reaction gases, the substrate temperature is 400 degrees Celsius to 500 degrees Celsius, and the reaction pressure is about 100 Pa. The thickness of the first protective layer 106 is, for example, 800 angstroms to 1500 angstroms.

[0095] In a preferred embodiment, before step S05, a resist layer is further formed on the surface of the second isolation layer 105, and a pattern including openings is formed in the resist layer by a photolithography process. Using the resist layer as a mask, the exposed portion of the second isolation layer 105 is removed by a selective etchant to form openings. By controlling the etching time, the etching can stop at a predetermined depth of the second isolation layer 105. After the etching, the resist layer can be removed by ashing or dissolution in a solvent. The openings are open on the surface of the second isolation layer 105 and extend downward. When observed from the surface of the second isolation layer 105, the shape of the openings is a plurality of circular holes, a plurality of square holes, or a plurality of triangular holes. When observed from the cross-section of the second isolation layer 105, the shape of the openings is a substantially trapezoidal or V-shaped with a bottom surface size smaller than the opening surface size. The diameter of the openings is, for example, 0.5 micrometers to 1.5 micrometers, and the depth is, for example, 0.5 micrometers to 1.5 micrometers. The openings are used to define protrusions that will be formed in subsequent steps to prevent the adhesion of the backplate electrode. Then, in step S05, a first protective layer 106 is formed on the second isolation layer 105, and the first protective layer 106 fills the openings on the surface of the second isolation layer 104, thereby correspondingly forming protrusions. The shape of the protrusions is consistent with the shape of the openings, such as any one of the following: a pyramid, a prism, or a cylinder. The diameter of the protrusions is, for example, 0.5 micrometers to 1.5 micrometers, and the depth is, for example, 0.5 micrometers to 1.5 micrometers.

[0096] In step S06, a backplate electrode 107 is formed on the first protective layer 106, as Figure 7 shown.

[0097] In this embodiment, the backplate electrode 107 is a conductive layer, for example, composed of doped polysilicon. For example, a doped polysilicon layer is formed on the first protective layer 106 by low-pressure chemical vapor deposition (LPCVD). Then, photolithography and etching steps are used to pattern the polysilicon layer to form the pattern of the backplate electrode 107. Further, the temperature for depositing the backplate electrode 107 is between 570 °C and 630 °C, and the thickness of the backplate electrode 107 is 0.3 micrometers to 1.0 micrometers. In a preferred embodiment, the area of the backplate electrode 107 is less than or equal to the area of the movable region of the diaphragm 104. More preferably, the area of the backplate electrode 107 is 70% to 100% of the movable region of the diaphragm 104. By making the area of the backplate electrode 107 less than or equal to the area of the movable region of the diaphragm, the invalid capacitance component is removed from the detection signal, so that the sensitivity of the detection signal is only related to the effective capacitance component, thereby improving the sensitivity of the MEMS microphone.

[0098] In step S07, a second protective layer 108 is formed on the backplate electrode 107, as Figure 8 shown.

[0099] The second protective layer 108 is composed of, for example, any one of silicon nitride, boron nitride, and silicon carbide. In this embodiment, the second protective layer 108 is, for example, a boron nitride layer. For example, a boron nitride layer with a film thickness of 0.1 micrometer to 1.0 micrometers is formed on the backplate electrode 107 by hot-wire assisted plasma enhanced chemical vapor deposition (PECVD) or by using low-pressure chemical vapor deposition (LPCVD). Among them, with N 2 、H 2 、and B 2 diluted by H 2 H 6 as the reaction gas, the substrate temperature is 400 degrees Celsius to 500 degrees Celsius, and the reaction pressure is about 100 Pa. The thickness of the second protective layer 108 is, for example, 0.1 micrometer to 1.0 micrometers. Among them, the first protective layer 106, the backplate electrode 107, and the second protective layer 108 constitute the backplate structure.

[0100] Since the backplate electrode 107 is patterned, the first part of the second protective layer 108 is formed on the surface of the backplate electrode 107, and the second part is formed on the surface of the first protective layer 106.

[0101] In step S08, a plurality of channel holes 132 are formed that respectively reach the surfaces of the diaphragm 104 and the backplate electrode 107, as Figure 9 shown.

[0102] In this embodiment, a resist layer is formed on the surface of the second protective layer 108, and a pattern including openings is formed in the resist layer by photolithography. Using the resist layer as a mask, a selective etchant is used to form a plurality of channel holes 132. Due to the selectivity of the etchant, this etching uses the diaphragm 104 and the backplate electrode 107 as the stop layers. In the first part region of the second protective layer 108, this etching removes the part of the second protective layer 108 exposed through the mask opening to form a channel hole 132 reaching the backplate electrode 107. In the second part region of the second protective layer 108, this etching sequentially removes the parts of the second protective layer 108, the first protective layer 106, and the second isolation layer 105 exposed through the mask opening from top to bottom to form a channel hole 132 reaching the diaphragm 104. After the etching, the resist layer can be removed by ashing or dissolution in a solvent.

[0103] Alternatively, due to the above-mentioned patterning step of the backplate electrode 107, the second part of the second protective layer 108 is in direct contact with the corresponding part of the first protective layer 106. At least one channel hole 132 starts from the surface of the second part of the second protective layer 108 and extends through the second protective layer 108, the first protective layer 106, and the second isolation layer 105 to the diaphragm 104 below the backplate electrode 107.

[0104] In step S09, a plurality of conductive channels 110 are formed that respectively reach the surfaces of the diaphragm 104 and the backplate electrode 107, as Figure 10 shown.

[0105] In this embodiment, the conductive channels 110 are composed of a conductive material, such as any one selected from aluminum, gold, silver, copper, nickel, titanium, chromium, or their alloys. The aluminum alloy for the conductive channels 110, for example, includes an aluminum-silicon alloy (1% by weight of silicon), and the titanium alloy includes titanium nitride. For example, by means of sputtering or evaporation, a metal layer is formed on the surface of the second protective layer 108. The thickness of the metal layer is, for example, 1 to 2 microns, and it fills a plurality of channel holes 132.

[0106] A resist layer is formed on the surface of the metal layer, and a pattern including openings is formed in the resist layer using a photolithography process. Using the resist layer as a mask, the exposed portions of the metal layer are removed using a selective etchant. Due to the selectivity of the etchant, the etching stops at the second protective layer 108. After etching, the resist layer can be removed by ashing or dissolution in a solvent.

[0107] In the first partial region of the second protective layer 108, at least one conductive channel 110 passes through the second protective layer 108 to reach the backplate electrode 107. In the second partial region of the second protective layer 108, at least one channel hole 110 sequentially passes through the second protective layer 108, the first protective layer 106, and the second isolation layer 105 to reach the diaphragm 104.

[0108] Alternatively, due to the patterning steps of the above-mentioned backplate electrode 107 and conductive channels 110, among the plurality of conductive channels 110, at least one conductive channel 110 extends to the diaphragm 104 and is spaced apart from the backplate electrode 107.

[0109] In step S10, a release hole 122 is formed that penetrates the second protective layer 108, the backplate electrode 107, and the first protective layer 106, as Figure 11 shown.

[0110] In this embodiment, a resist layer is formed on the surface of the second protective layer 108, and a pattern including openings is formed in the resist layer using a photolithography process. Using the resist layer as a mask, the exposed portions of the second protective layer 108, the backplate electrode 107, and the first protective layer 106 are removed using a selective etchant, thereby forming the release hole 122. Due to the selectivity of the etchant, the second isolation layer 105 serves as a stop layer. After etching, the resist layer can be removed by ashing or dissolution in a solvent.

[0111] This step, for example, uses a dedicated deep trench etching machine to form the release hole 122.

[0112] In step S11, an acoustic cavity 121 penetrating the substrate 101 is formed below the diaphragm 104, as Figure 12 shown.

[0113] In this embodiment, the thickness of the substrate 101 is reduced to a designed value by a chemical mechanical planarization or thinning process. For example, the first surface and the second surface of the substrate 101 opposite to each other are respectively used to form the above-mentioned first isolation layer 102 and as a free surface, and the second surface is polished to reduce the thickness of the substrate 101. Then, a resist layer is formed on the second surface of the substrate 101, and a pattern including an opening is formed in the resist layer by a photolithography process. Using the resist layer as a mask, the exposed portion of the substrate 101 is removed by a selective etchant, thereby forming the acoustic cavity 121. In this embodiment, the acoustic cavity is a square opening. Alternatively, it can also be a trapezoidal or inverted trapezoidal opening. Due to the selectivity of the etchant, the first isolation layer 102 serves as a stop layer. After etching, the resist layer can be removed by ashing or dissolution in a solvent.

[0114] In a preferred embodiment, the area of the backplate electrode 107 is less than or equal to the minimum cross-sectional area of the acoustic cavity 121. More preferably, the area of the backplate electrode 107 is less than the minimum cross-sectional area of the acoustic cavity 121. It should be noted that when the opening of the acoustic cavity 121 is square, the cross-sectional areas obtained by the acoustic cavity at different horizontal planes are the same, and this unique cross-sectional area is the minimum cross-sectional area of the acoustic cavity 121. When the opening of the acoustic cavity 121 is an inverted trapezoid or a trapezoid, the cross-sectional area of the acoustic cavity 121 at the first surface or the second surface of the substrate 101 is the smallest. In some embodiments, the radius of its minimum cross-section is 385 microns to 415 microns.

[0115] In step S12, a part of the first isolation layer 102 is removed via the acoustic cavity 121, and a part of the second isolation layer 105 is removed via the release hole 122 to release the diaphragm 104, as Figure 13 shown.

[0116] In this embodiment, for example, HF acid is used as an etchant, and the acoustic cavity 121 and the release hole 122 formed in the above steps are used as the entry channels of the etchant. The first protective layer 106 and the second protective layer 108 respectively serve as the protective films of the backplate electrode 107, so that the backplate electrode 107 is not etched in this etching step. In this embodiment, a material resistant to HF corrosion is used to form the backplate electrode of the MEMS microphone with a multi-layer structure, where the first protective layer and the second protective layer serve as the insulating protective films of the backplate polycrystalline layer in the MEMS microphone, so that when the sacrificial oxide film in the device structure is released by HF acid vapor fumigation, the backplate electrode 107 is still not etched, improving the performance and reliability of the device.

[0117] By means of HF acid vapor fumigation or HF acid wet etching, a part of the first isolation layer 102 and the second isolation layer 105 is removed respectively, so that a part of the first surface and the second surface of the diaphragm 104 facing each other is exposed again, thus releasing the diaphragm 104. After removing a part of the first isolation layer 102, the acoustic cavity 121 extends from the second surface of the substrate 101 to the second surface of the diaphragm 104. After removing a part of the second isolation layer 105, a cavity 123 is formed between the first protective layer 106 and the first surface of the diaphragm 104. The release hole 122 communicates with the cavity 123 with each other, providing an air flow channel during the vibration of the diaphragm 104.

[0118] In this step, the spring structure 103 of the diaphragm 104 is also exposed to the acoustic cavity 121 and the cavity 123.

[0119] In a preferred embodiment, it further includes step S13. In step S13, a monomolecular organic film 112 is formed on the exposed surface of the diaphragm 104, thus forming the MEMS microphone 100, as Figure 14 shown.

[0120] In this embodiment, the acoustic cavity 121 and the release hole 122 formed by the above steps are used as the supply channels of the reaction gas, and a monomolecular organic film 112 is formed on the exposed surface of the diaphragm 104 by chemical vapor deposition. In a preferred embodiment, the monomolecular organic film 112 covers the exposed external surface of the MEMS microphone 100 and the internal surface communicating with the external environment.

[0121] The monomolecular organic film 112 is composed of, for example, any one selected from organosilanes or organosiloxanes, and the thickness is, for example, 1 nanometer to 10 nanometers. The monomolecular organic film 112 has hydrophobic properties and low surface adhesion. Therefore, it can not only achieve the purpose of anti-adhesion, but also does not affect the device performance, thus improving the reliability of the device.

[0122] In a preferred embodiment, the MEMS microphone 100 further includes at least one additional film forming a laminated structure with the monomolecular organic film 122. The additional film is, for example, a metal oxide film or a silicon oxide film. Atomic layer deposition (ALD) equipment can be used to deposit AL 2 O 3 and TiO 2 and other metal oxide films, and the thickness of the film is controlled within 1 nanometer to 3 nanometers. A silicon oxide film can be deposited by using molecule vapor deposition (MVD) equipment, and the thickness of the film is controlled within 1 nanometer to 3 nanometers each.

[0123] The structure of the MEMS microphone manufactured by the above method is asFigure 14 as shown

[0124] The MEMS microphone 100 includes: a first isolation layer 102, a diaphragm 104, and a second isolation layer 105 sequentially formed on a substrate 101; a first protective layer 106, a backplate electrode 107, and a second protective layer 108 sequentially formed on the second isolation layer 105; a release hole 122 penetrating through the first protective layer 106, the backplate electrode 107, and the second protective layer 108; a cavity 123 penetrating through the second isolation layer 105, and the cavity 123 communicates with the release hole 122; a sound cavity 121 penetrating through the substrate 101 and the first isolation layer 102; the first surface and the second surface of the diaphragm 104 facing each other are exposed through the cavity 123 and the sound cavity 121. The first isolation layer 102 and the second isolation layer 105 clamp the peripheral portion of the diaphragm 104.

[0125] The diaphragm 104 includes a spring structure 103. The diaphragm 104 further includes an intermediate portion 104a and a peripheral portion 104c connected by the spring structure 103. During the vibration of the diaphragm 104, the sound cavity 121 and the release hole 122 serve as air flow channels. In this embodiment, the spring structure 103 of the diaphragm 104 is a concentric annular corrugated portion, and the concentric annular spring structure includes 1 to 6 circular rings. In an alternative embodiment, the spring structure 103 of the diaphragm 104 is a spiral corrugated portion. Further, the spiral spring structure includes at least one spiral line that radiates outward from the intermediate portion of the diaphragm.

[0126] In a preferred embodiment, the diaphragm 104 further includes reinforcing ribs located at the peripheral portion, for example, radial strip beams or parapet structures located at the peripheral portion. Further, the parapet structure includes a plurality of annular cross-sections, and the morphology of the annular cross-sections is rectangular wave-shaped. Alternatively, the reinforcing ribs include a plurality of annular cross-sections, and the shape of the corners of the plurality of annular cross-sections is a circular arc or an inclined trapezoidal wave or a sine wave. The backplate electrode includes a reinforcing structure in the shape of a protrusion or a groove. Further, the reinforcing structure is, for example, a radial strip beam or a parapet structure. Further, the parapet structure includes a plurality of annular cross-sections, and the morphology of the annular cross-sections is rectangular wave-shaped. Alternatively, the reinforcing ribs include a plurality of annular cross-sections, and the shape of the corners of the plurality of annular cross-sections is a circular arc or an inclined trapezoidal wave or a sine wave.

[0127] In a preferred embodiment, a partial region of the diaphragm 104 is a discontinuous region. Further, the edge of the peripheral portion of the diaphragm 104 is discontinuous. Further, the edge of the peripheral portion is serrated, and a plurality of notches of the serration form a discontinuous region. In an alternative embodiment, the discontinuous region of the peripheral portion of the diaphragm 104 includes a hollowed-out structure. Further, the hollowed-out structure includes a plurality of through holes, and the through holes are polygonal, circular, or trapezoidal.

[0128] The diaphragm 104 and the backplate electrode 107 are each composed of doped polysilicon. Each of the first protective layer 106 and the second protective layer 108 is composed of any one of a silicon nitride layer, a boron nitride layer, and a silicon carbide layer. Among them, the first protective layer 106, the backplate electrode 107, and the second protective layer 108 constitute the backplate structure.

[0129] Furthermore, it further includes a monolayer organic film 112 that at least covers the exposed surface of the diaphragm 104. Further still, the monolayer organic film 112 also covers the exposed surface of the first protective layer 106 in the cavity 123, and the monolayer organic film 112 covers the outer surface of the MEMS microphone and the inner surface communicating with the external environment. The monolayer organic film 112 is composed of any one of an organosilane layer and an organosiloxane layer.

[0130] The MEMS microphone 100 further includes a plurality of conductive channels 110. Among the plurality of conductive channels 110, the first conductive channel passes through the second protective layer 108, the first protective layer 106, and the second isolation layer 105 to reach the surface of the diaphragm 104, and the second conductive channel passes through the second protective layer 108 to reach the surface of the backplate electrode 107.

[0131] In a preferred embodiment, the area of the backplate electrode 107 is less than or equal to the minimum cross-sectional area of the acoustic cavity 121. More preferably, the area of the backplate electrode is less than the minimum cross-sectional area of the acoustic cavity, avoiding the problem of the reliability decline of the MEMS microphone caused by process fluctuations in mass production and improving the overall performance of the product. It should be noted that when the opening of the acoustic cavity 121 is square, the cross-sectional areas obtained at different horizontal planes of the acoustic cavity are the same, and this unique cross-sectional area is the minimum cross-sectional area of the acoustic cavity 121. When the opening of the acoustic cavity 121 is an inverted trapezoid or a trapezoid, the cross-sectional area of the acoustic cavity 121 at the first surface or the second surface of the substrate 101 is the smallest. In some embodiments, the radius of its minimum cross-section is 385 microns to 415 microns.

[0132] In a preferred embodiment, the MEMS microphone 100 further includes at least one additional film that forms a stacked structure with the monolayer organic film 122. The additional film is, for example, a metal oxide film or a silicon oxide film. Atomic layer deposition (ALD) equipment can be used to deposit AL 2 O 3 and TiO 2 and other metal oxide films, and the thickness of the film is controlled within 1 nanometer to 3 nanometers. A silicon oxide film can be deposited using molecular vapor deposition (MVD) equipment, and the thickness of the film is each controlled within 1 nanometer to 3 nanometers.

[0133] In a preferred embodiment, a plurality of protrusions are formed on the surface of the first protective layer 106 facing the diaphragm 104 to prevent adhesion between the backplate electrode 107 and the diaphragm 104.

[0134] In a preferred embodiment, the movable region of the diaphragm 104 includes the region of the middle portion 104a and the region of the spring structure 103, and the movable region of the diaphragm 104 corresponds to a part of the backplate electrode 107. Further, the backplate electrode 107 is formed above the movable region of the diaphragm 104, and the area of the backplate electrode 107 is less than or equal to the area of the movable region of the diaphragm 104. In a preferred embodiment, the area of the backplate electrode 107 is less than the area of the movable region of the diaphragm 104. More preferably, the area of the backplate electrode 107 is 70% to 100% of the area of the movable region of the diaphragm 104. By adopting that the area of the backplate electrode 107 is less than or equal to the area of the movable region of the diaphragm, the invalid capacitance component is removed from the detection signal, so that the sensitivity of the detection signal is only related to the effective capacitance component, thereby improving the sensitivity of the MEMS microphone. MEMS microphone

[0135] As described above, the embodiments according to the present invention do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the above description. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can make good use of the present invention and its modified use based on the present invention. The protection scope of the present invention should be defined by the scope of the claims of the present invention.

Claims

1. A method for manufacturing a MEMS microphone, wherein, comprising: successively forming a first isolation layer, a diaphragm, and a second isolation layer on a substrate; successively forming a first protective layer, a backplate electrode, and a second protective layer on the second isolation layer, a first portion of the second protective layer being formed on the surface of the backplate electrode, and a second portion of the second protective layer being formed on the surface of the first protective layer; forming a release hole penetrating through the first protective layer, the backplate electrode, and the second protective layer; forming a sound cavity penetrating through the substrate; releasing the diaphragm via the sound cavity and the release hole; and between the steps of forming the first isolation layer and the diaphragm, further comprising: forming a groove on the surface of the first isolation layer, the diaphragm conformally covering the surface of the first isolation layer, and forming a spring structure at the position of the groove.

2. The method according to claim 1, wherein, in the step of releasing the diaphragm, a portion of the first isolation layer is removed via the sound cavity, and a portion of the second isolation layer is removed via the release hole, thereby exposing a first surface and a second surface of the diaphragm that are opposite to each other.

3. The method according to claim 2, wherein, in the step of releasing the diaphragm, HF acid is used as an etchant, the diaphragm is used as a stop layer, and the first protective layer and the second protective layer are used to protect the backplate electrode.

4. The method according to claim 1, wherein, after the step of releasing the diaphragm, further comprising: forming a monolayer organic film at least on the exposed surface of the diaphragm.

5. The method according to claim 4, wherein, further comprising: forming at least one additional film of a metal oxide film or a silicon oxide film on the surface of the monolayer organic film, the additional film and the monolayer organic film forming a stacked structure.

6. The method according to claim 4, wherein, in the step of releasing the diaphragm, a cavity is formed between the first protective layer and the diaphragm.

7. The method according to claim 6, wherein, the monolayer organic film covers the external surface of the MEMS microphone and the internal surface communicating with the external environment.

8. The method according to claim 7, wherein, in the step of forming the monolayer organic film, the monolayer organic film covers the exposed surface of the first protective layer in the cavity.

9. The method according to claim 1, wherein, the diaphragm and the backplate electrode are respectively composed of doped polysilicon.

10. The method according to claim 1, wherein, each of the first protective layer and the second protective layer is composed of any one selected from silicon nitride, boron nitride, and silicon carbide.

11. The method according to claim 1, wherein, the spring structure of the diaphragm is a concentric annular corrugated portion or a helical corrugated portion.

12. The method according to claim 11, wherein, the concentric annular spring structure includes 1 to 6 circular rings.

13. The method according to claim 11, wherein, The spiral spring structure includes at least one spiral thread that radiates outward from the middle part of the diaphragm.

14. The method according to claim 1, wherein, further comprising: forming reinforcing ribs at the peripheral part of the diaphragm.

15. The method according to claim 14, wherein, the reinforcing ribs of the diaphragm are radial strip beams or parapet structures located at the peripheral part.

16. The method according to claim 1, wherein, further comprising: forming a discontinuous area in a partial area of the peripheral part of the diaphragm.

17. The method according to claim 1, wherein, forming a plurality of protrusions on the surface of the first protective layer facing the diaphragm to prevent adhesion between the backplate electrode and the diaphragm.

18. The method according to claim 1, wherein, between the steps of forming the backplate electrode and the second protective layer, further comprising: patterning the backplate electrode.

19. The method according to claim 18, wherein, further comprising: forming a first conductive channel that penetrates through the second protective layer, the first protective layer, and the second isolation layer to reach the surface of the diaphragm in the area where a part of the backplate electrode is removed by patterning; and forming a second conductive channel that penetrates through the second protective layer to reach the surface of the backplate electrode in the area where another part of the backplate electrode is retained by patterning.

20. The method according to claim 4, wherein, the monomolecular layer organic film is composed of any one of organosilane and organosiloxane.

21. The method according to claim 1, wherein, the backplate electrode is formed above the movable area of the diaphragm, and the area of the backplate electrode is less than or equal to the area of the movable area of the diaphragm.

22. The method according to claim 1, wherein, the area of the backplate electrode is less than or equal to the minimum cross-sectional area of the acoustic cavity.

23. The method according to claim 22, wherein, the radius of the minimum cross-section of the acoustic cavity is 385 microns to 415 microns.

24. The method according to claim 1, wherein, the thicknesses of the first protective layer and the second protective layer are different.

25. The method according to claim 24, wherein, the thickness of the first protective layer is 800 angstroms to 1500 angstroms, and the thickness of the second protective layer is 0.1 micron to 1.0 micron.

26. The method according to claim 1, wherein, the materials of the first protective layer and the second protective layer are different.

27. A MEMS microphone, wherein, comprising: a first isolation layer, a diaphragm, and a second isolation layer formed in sequence on a substrate; a first protective layer, a backplate electrode, and a second protective layer formed in sequence on the second isolation layer, a first part of the second protective layer is formed on the surface of the backplate electrode, and a second part of the second protective layer is formed on the surface of the first protective layer; a release hole penetrating through the first protective layer, the backplate electrode, and the second protective layer; a cavity penetrating through the second isolation layer, and the cavity is communicated with the release hole; A sound cavity penetrating through the substrate and the first isolation layer; and A spring structure is disposed on the surface of the diaphragm, and a first surface and a second surface of the diaphragm opposite to each other are respectively exposed through the cavity and the sound cavity.

28. The MEMS microphone according to claim 27, wherein, further comprising: A monolayer organic film covering at least the exposed surface of the diaphragm.

29. The MEMS microphone according to claim 28, wherein, further comprising at least one additional film of a metal oxide film or a silicon oxide film on the surface of the monolayer organic film, and the additional film and the monolayer organic film form a stacked structure.

30. The MEMS microphone according to claim 28, wherein, The monolayer organic film covers the outer surface of the MEMS microphone and the inner surface communicating with the external environment.

31. The MEMS microphone according to claim 28, wherein, The monolayer organic film covers the exposed surface of the first protective layer in the cavity.

32. The MEMS microphone according to claim 27, wherein, The diaphragm and the back plate electrode are respectively composed of doped polysilicon.

33. The MEMS microphone according to claim 27, wherein, Each of the first protective layer and the second protective layer is composed of any one selected from a silicon nitride layer, a boron nitride layer, and a silicon carbide layer, and the materials of the first protective layer and the second protective layer are different.

34. The MEMS microphone according to claim 27, wherein, The spring structure of the diaphragm is a concentric annular corrugated part or a spiral corrugated part.

35. The MEMS microphone according to claim 34, wherein, The concentric annular spring structure includes 1 to 6 circular rings.

36. The MEMS microphone according to claim 34, wherein, The spiral spring structure includes at least one spiral line that radiates outward from the middle part of the diaphragm.

37. The MEMS microphone according to claim 27, wherein, further comprising: Forming a reinforcing rib in the peripheral part of the diaphragm.

38. The MEMS microphone according to claim 37, wherein, The reinforcing rib of the diaphragm is a radial strip beam or a parapet structure located in the peripheral part.

39. The MEMS microphone according to claim 27, wherein, further comprising: Forming a discontinuous region in a partial area of the peripheral part of the diaphragm.

40. The MEMS microphone according to claim 27, wherein, further comprising: A first conductive channel passing through the second protective layer, the first protective layer, and the second isolation layer to reach the surface of the diaphragm; and A second conductive channel passing through the second protective layer to reach the surface of the back plate electrode.

41. The MEMS microphone according to claim 28, wherein, The monolayer organic film is composed of any one of an organosilane layer and an organosiloxane layer.

42. The MEMS microphone according to claim 27, wherein, A plurality of protrusions are formed on the surface of the diaphragm facing the first protective layer to prevent adhesion between the backplate electrode and the diaphragm.

43. The MEMS microphone according to claim 27, wherein, the backplate electrode is formed above the movable area of the diaphragm, and the area of the backplate electrode is less than or equal to the area of the movable area of the diaphragm.

44. The MEMS microphone according to claim 27, wherein, the area of the backplate electrode is less than or equal to the minimum cross-sectional area of the acoustic cavity.

45. The MEMS microphone according to claim 43, wherein, the area of the backplate electrode is 70% - 100% of the movable area.

46. The MEMS microphone according to claim 43, wherein, the diaphragm further includes an intermediate portion and a peripheral portion connected by the spring structure, and the movable area of the diaphragm includes the area of the intermediate portion and the area of the spring structure.

47. The MEMS microphone according to claim 44, wherein, the radius of the minimum cross-section of the acoustic cavity is 385 microns - 415 microns.

48. The MEMS microphone according to claim 27, wherein, the thickness of the backplate electrode is 0.3 microns - 1.0 microns.

49. The MEMS microphone according to claim 27, wherein, the thicknesses of the first protective layer and the second protective layer are different.

50. The MEMS microphone according to claim 49, wherein, the thickness of the first protective layer is 800 angstroms - 1500 angstroms, and the thickness of the second protective layer is 0.1 microns - 1.0 microns.

51. The MEMS microphone according to claim 28, wherein, the thickness of the monolayer organic film layer is 1 nanometer - 10 nanometers.

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