MEMS microphone and manufacturing method therefor

Abstract

Embodiments of the present invention relate to the technical field of semiconductor devices. Disclosed are a MEMS microphone and a manufacturing method therefor. The MEMS microphone comprises: a substrate, which defines a cavity; anchoring members provided on the substrate; and a diaphragm provided with beam structures, wherein the beam structures are fixed on the anchoring members, such that the diaphragm covers the cavity and is spaced apart from the substrate, and inner edges of the side of the substrate close to the diaphragm is provided with chamfers. In the present invention, the inner edges of the side of the substrate close to the diaphragm are provided with chamfers, and when the diaphragm bends towards the substrate side due to vibration, the provision of the chamfers can prevent the diaphragm from colliding with the substrate, or increase the contact area between the diaphragm and the substrate when the diaphragm collides with the substrate, thereby avoiding stress concentration, reducing the risk of damage to the diaphragm. In this way, the probability of failure of the MEMS microphone due to damage to the diaphragm can be reduced, and the robustness of the MEMS microphone can be enhanced.

Description

MEMS microphone and manufacturing method thereof

[0001] This application claims priority from US patent application No. US 18890691, filed on September 19, 2024, which is incorporated by reference in its entirety. TECHNICAL FIELD

[0002] Embodiments of the present application relate to the technical field of semiconductor devices, and in particular to a MEMS microphone and manufacturing method thereof. BACKGROUND

[0003] Micro-Electro-Mechanical System (MEMS) is a micro sensor or actuator made of semiconductor materials using microelectronic technology and micromachining technology. MEMS microphone is a kind of micro machine system, compared with the traditional electret condenser microphone, it has better acoustic performance, higher signal-to-noise ratio, better consistent sensitivity and lower power consumption. MEMS microphone has been widely used in smart phones, notebook computers and other fields to provide higher voice quality. TECHNICAL PROBLEM

[0004] The MEMS microphone includes a back plate and a diaphragm arranged opposite to each other, which form a variable capacitor. The moving structure of the MEMS microphone, such as the diaphragm, bends with the change of air pressure when the sound wave causes the change of air pressure, so that the capacitance value of the variable capacitor changes. The existing MEMS microphone has defects in structural design, which is easy to cause structural damage and lead to device failure, resulting in weak robustness of the MEMS microphone.

[0005] Therefore, there is an urgent need in the art for a design that can enhance the robustness of the MEMS microphone. TECHNICAL SOLUTION

[0006] Embodiments of the present application provide a MEMS microphone, comprising: a substrate surrounding a cavity; an anchor arranged above the substrate; a diaphragm having a beam structure, the beam structure being fixed above the anchor, so that the diaphragm covers the cavity and is arranged spaced apart from the substrate; wherein the inner edge of the side of the substrate close to the diaphragm is provided with a chamfer.

[0007] Optionally, from the direction of the diaphragm towards the substrate, the substrate is provided with a plurality of stepped portions, and the inner edge of at least the stepped portion closest to the diaphragm is chamfered.

[0008] Optionally, from the direction of the diaphragm towards the substrate, the height of the plurality of stepped portions increases.

[0009] Optionally, an inner edge of each of the step portions is chamfered.

[0010] Optionally, the width of the plurality of step portions gradually increases from the edge of the diaphragm towards the center of the diaphragm in a direction from the diaphragm towards the substrate.

[0011] Optionally, the chamfer is a round chamfer.

[0012] Optionally, the round chamfer has a radius R, and satisfies the following relationship: 0 < R ≤ π / 2.

[0013] Optionally, the round chamfer has a radius R, and satisfies the following relationship: π / 6 ≤ R ≤ π / 2.

[0014] Optionally, the round chamfer has a radius R, and satisfies the following relationship: π / 4 ≤ R ≤ π / 2.

[0015] Optionally, the chamfer is an inclined chamfer.

[0016] A second aspect of the embodiments of the present application provides a method for manufacturing the above-mentioned MEMS microphone, comprising:

[0017] providing a substrate, the substrate comprising a first region and a second region surrounding the first region;

[0018] etching a groove in the first region of the substrate, and chamfering an inner edge of an opening of the groove;

[0019] filling a sacrificial layer in the groove, and planarizing the sacrificial layer;

[0020] forming a diaphragm on the sacrificial layer;

[0021] etching the substrate in a region corresponding to the groove to form a cavity. Advantages

[0022] The present application has the advantage that the inner edge of the substrate near the diaphragm is chamfered, so that when the diaphragm bends towards the substrate due to vibration, the diaphragm can be prevented from colliding with the substrate, or the contact area between the diaphragm and the substrate is increased when the diaphragm collides with the substrate, so that stress concentration is avoided, thereby reducing the risk of damage to the diaphragm. In this way, the probability of failure of the MEMS microphone due to damage to the diaphragm can be reduced, and the robustness of the MEMS microphone can be enhanced. BRIEF DESCRIPTION OF DRAWINGS

[0023] One or more embodiments are illustrated by way of example in the figures that are part of this disclosure and which are illustrative, but not restrictive, of the present embodiments, wherein elements having the same reference numbers designate corresponding elements and in which: the figures are not to scale.

[0024] Fig. 1 is a schematic plan view of a partial structure of a MEMS microphone according to a first embodiment of the present application;

[0025] Fig. 2 is a schematic sectional view of the MEMS microphone structure of Fig. 1 taken along the line AA';

[0026] Fig. 3 is a schematic enlarged view of the region A of Fig. 2;

[0027] Fig. 4 is a schematic view of stress distribution of a diaphragm contacting an edge when the edge is provided with a sharp edge;

[0028] Fig. 5 is a schematic view of stress distribution of a diaphragm contacting an edge when the edge is provided with a step portion having a chamfered corner and an extension width of 5 μm;

[0029] Fig. 6 is a schematic view of stress distribution of a diaphragm contacting an edge when the edge is provided with a step portion having a chamfered corner and an extension width of 7 μm;

[0030] Fig. 7 is a schematic view of stress distribution of a diaphragm contacting an edge when the edge is provided with a step portion having a chamfered corner and an extension width of 8 μm;

[0031] Fig. 8 is a schematic view of stress distribution of a diaphragm contacting an edge when the edge is provided with a step portion having a chamfered corner and an extension width of 10 μm;

[0032] Fig. 9 is a flowchart of a method of manufacturing a MEMS microphone according to the present application;

[0033] Fig. 10a is a schematic view of a structure in which a groove is formed in a substrate;

[0034] Fig. 10b is a schematic view of a structure in which a first sacrificial layer is filled in the groove;

[0035] Fig. 10c is a schematic view of a structure in which the first sacrificial layer is planarized;

[0036] Fig. 10d is a schematic view of a structure in which a second sacrificial layer is formed on the substrate;

[0037] Fig. 10e is a schematic view of a structure in which a diaphragm is provided on the second sacrificial layer;

[0038] Fig. 10f is a schematic view of a structure in which a third sacrificial layer is provided on the diaphragm;

[0039] Fig. 10g is a schematic view of a structure in which a back plate is provided on the third sacrificial layer;

[0040] Fig. 10h is a schematic view of a structure of a MEMS microphone formed after etching the substrate and the sacrificial layers. Embodiments of the present application

[0041] In order to make the purposes, technical solutions, and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below with reference to the drawings. However, it should be understood by those skilled in the art that, in the embodiments of the present application, many technical details are presented in order to make the present application better understood by the readers. However, the technical solutions claimed by the present application can be implemented even without these technical details and based on various changes and modifications of the following embodiments.

[0042] In some MEMS microphones, a diaphragm has a beam structure and is fixed to an anchor through the beam structure, thereby covering a cavity of a substrate in the MEMS microphone, and a back plate is further arranged on the diaphragm, and the diaphragm and the back plate have a gap therebetween to form a variable capacitor. When the MEMS microphone is in operation, the diaphragm vibrates under the influence of sound pressure, and the diaphragm bends during the vibration to change the capacitance value of the variable capacitor. However, since there is no support between the beam structure and the substrate, the beam structure not only acts as a stress concentration point of the bending deformation during the vibration of the diaphragm, but also repeatedly hits the edge of the substrate to continue to bear stress, thereby making the diaphragm extremely vulnerable to damage. Generally, the stress at the contact point of the diaphragm and the substrate can be reduced by increasing the width of the beam structure, but this will cause the sensitivity of the device to decrease; or the edge of the substrate can be made to approach the anchor to reduce the stress at the contact point, but this will cause the anchor to bear stress, thereby increasing the risk of failure.

[0043] The present application aims to reduce the stress between the diaphragm and the edge of the substrate without changing the configuration of the diaphragm and without adding other structures, thereby reducing the risk of damage to the diaphragm and making the MEMS microphone have robust robustness.

[0044] One embodiment of the present application provides a MEMS microphone, comprising: a substrate surrounding a cavity; an anchor arranged above the substrate; a diaphragm having a beam structure, the beam structure being fixed above the anchor, so that the diaphragm covers the cavity and is arranged in a spaced-apart manner with the substrate; wherein an inner edge of a side of the substrate close to the diaphragm is provided with a chamfer.

[0045] Another embodiment of the present application provides a method for manufacturing the above-mentioned MEMS microphone, comprising: providing a substrate, the substrate comprising a first region and a second region surrounding the first region; etching a groove in the first region of the substrate, and etching the inner edge of the opening of the groove as a chamfer; filling a sacrificial layer in the groove and planarizing the sacrificial layer; forming a diaphragm on the sacrificial layer; etching the substrate in the region corresponding to the groove to form a cavity.

[0046] The core of the embodiment is that the inner edge of the substrate close to the diaphragm is chamfered, when the diaphragm bends towards the substrate side due to vibration, the diaphragm can be prevented from colliding with the substrate by setting the chamfer, or the contact area between the diaphragm and the substrate is increased when the diaphragm collides with the substrate, so as to avoid stress concentration, thereby reducing the risk of diaphragm damage. In this way, the probability of failure of the MEMS microphone due to diaphragm damage can be reduced, and the robustness of the MEMS microphone can be enhanced.

[0047] The implementation details of the MEMS microphone of the present embodiment will be specifically described below. The following implementation details are provided for the convenience of understanding, and are not essential for implementing the present solution.

[0048] Referring to FIGS. 1-3, the substrate 101 of the MEMS microphone 100 of the present embodiment is arranged in a ring shape, for example, a square ring shape or a circular ring shape, and the substrate 101 encloses a cavity 1011 that penetrates the substrate 101 and serves as a vibration space of the MEMS microphone 100. Optionally, the substrate 101 can be a single crystal silicon substrate or other substrate that meets the design requirements.

[0049] The anchor 102 is arranged on the substrate 101, for example, a plurality of anchors 102 are arranged on the substrate 101 at intervals around the axis of the substrate 101, wherein the anchor 102 can be made of silicon nitride or silicon dioxide.

[0050] The diaphragm 103 has a beam structure 1031 and a vibration part 1032, which can be formed integrally. The number of beam structures 1031 can be the same as the number of anchors 102, and the diaphragm 103 is fixed to the anchor 102 one by one through the beam structure 1031, so that the vibration part 1032 covers the cavity 1011, and the diaphragm 103 and the substrate 101 have a spacing therebetween.

[0051] Generally, when the diaphragm 103 bends due to vibration, the beam structure 1031 is stressed and collides with the edge 1012 of the substrate 101. Since the edge of the conventional substrate is a right-angled edge, the beam structure 1031 is prone to stress concentration when colliding, which leads to damage of the diaphragm 103. In the present application, the edge 1012 is chamfered, which increases the distance between the beam structure 1031 and the edge 1012. When the diaphragm 103 bends, the beam structure 1031 will not easily collide with the edge 1012. Even if the beam structure 1031 collides with the edge 1012, since the edge 1012 is chamfered, the contact area between the beam structure 1031 and the edge 1012 is increased, which can effectively disperse the stress generated by the collision, reduce the risk of damage to the beam structure 1031, and enhance the robustness of the MEMS microphone 100.

[0052] In some embodiments, the inner wall of the base 101 is provided with a plurality of stepped portions 1013 in the direction from the diaphragm 103 to the base 101. Among them, the edge 1012 of at least the stepped portion 1013 closest to the diaphragm 103 is provided as a chamfer. By providing a plurality of stepped portions 1013, the contact points between the beam structure 1031 and the base 101 are increased, which can further disperse the stress generated by the beam structure 1031 when colliding with the base 101, avoid the occurrence of stress concentration, and make the MEMS microphone 100 have more robust robustness.

[0053] It should be noted that the width of each stepped portion 1013 gradually increases in the direction from the diaphragm 103 to the base 101. In other words, the farther the stepped portion 1013 is from the diaphragm 103, the closer its edge is to the center position of the vibrating portion 1032, and the size of each stepped portion 1013 is greater than the previous stepped portion 1013 in the direction from the diaphragm 103 to the base 101.

[0054] In some embodiments, the height of different stepped portions 1013 gradually increases in the direction from the diaphragm 103 to the base 101. When the diaphragm 103 vibrates, the center position of the vibrating portion 1032 is most affected by the sound pressure, and the amplitude of its bending deformation is also the largest. From the center position to the edge position, the effect of the sound pressure on the diaphragm 103 gradually decreases, and the amplitude of the bending deformation also gradually decreases, especially at the position with the beam structure 1031, due to the effect of the beam structure 1031, the bending deformation amplitude of the diaphragm 103 is smaller. Therefore, the height of the stepped portion 1013 near the edge of the diaphragm 103 is set to be smaller, and the height of the stepped portion 1013 far from the edge of the diaphragm 103 is set to be larger. In this way, when the diaphragm 103 is affected by the sound pressure, it can be ensured that the diaphragm 103 falls on each stepped portion 1013 at the same time to disperse the stress on the diaphragm 103. The effect of the above setting is particularly significant when the pressure on the diaphragm 103 increases.

[0055] In some embodiments, the width of different stepped portions 1013 is also configured in the direction from the edge of the diaphragm 103 to its center position, so that when the pressure on the diaphragm 103 increases, the diaphragm 103 can fall on each stepped portion 1013 at the same time.

[0056] Again, referring to FIG. 2 and FIG. 3, three stepped portions 1013 are described. The stepped portions arranged in sequence from the edge of the diaphragm 103 to the center position of the diaphragm 103 are the first stepped portion 1013a, the second stepped portion 1013b and the third stepped portion 1013c. The interval between the first stepped portion 1013a and the diaphragm 103 can be the height H1 of the anchor 102, the height of the first stepped portion 1013a can be H2, the interval between the second stepped portion 1013b and the diaphragm 103 can be H1+H2, the height of the second stepped portion 1013b can be H3, the interval between the third stepped portion 1013c and the diaphragm 103 can be H1+H2+H3, and the height of the third stepped portion 1013c can be H4. In some embodiments, H2

[0057] Also, the width of the portion of the first stepped portion 1013a beyond the anchor 102 can be S1, the width of the portion of the second stepped portion 1013b beyond the anchor 102 can be S2, and the width of the portion of the third stepped portion 1013c beyond the anchor 102 can be S3. Wherein, S1

[0058] It can be understood that the specific number of stepped portions 1013, the specific height of different stepped portions 1013, the specific width of different stepped portions 1013, and the height difference between different stepped portions 1013 and the width difference between different stepped portions 1013 can be specifically set according to different MEMS microphones, which will not be described here.

[0059] In some embodiments, the edge of the step portion 1013 farthest from the diaphragm 103 can not be chamfered but kept as a right angle for the sake of saving processing steps and reducing manufacturing difficulty. Take the third step portion 1013c as an example. In this case, the edge of the third step portion 1013c is relatively sharp to the diaphragm 103. In order to avoid the diaphragm 103 being damaged by being deeply sunk into the edge of the third step portion 1013c under excessive pressure, the value of H3 / AS2 needs to be set large enough. In this way, when the diaphragm 103 is deformed by bending towards the substrate 101 under a large pressure, the edge of the second step portion 1013b can well block the diaphragm 103 and reduce the deformation amplitude of the diaphragm 103, so as to avoid the diaphragm 103 from hitting the edge of the third step portion 1013c. In this case, since the first step portion 1013a and the second step portion 1013b well block and reduce the deformation amplitude of the diaphragm 103, the diaphragm 103 is difficult to hit the edge of the third step portion 1013c, and thus the specific position of the edge of the third step portion 1013c will not significantly affect the device within a certain range. Specifically, there are usually errors in the actual manufacturing process, and in the above design, no matter whether the edge of the third step portion 1013c is located beyond or less than the predetermined position within a certain range, for example, ±10 pm, the effectiveness of the device will not be affected.

[0060] In some other embodiments, the edge of each step portion 1013 is chamfered. In this way, the robustness of the MEMS microphone 100 can be further enhanced.

[0061] Optionally, the chamfer provided at the edge of the step portion 1013 is a bevel chamfer or a round chamfer. For example, the chamfer is a round chamfer. Compared with the bevel chamfer, the round chamfer can not only increase the contact area between the diaphragm 103 and the substrate 101 when the diaphragm 103 hits the substrate 101, but also further avoid stress concentration of the diaphragm 103 due to the absence of edges. Of course, the bevel chamfer and the round chamfer can also be provided at the same time, that is, the chamfer of the edge of some step portions 1013 is provided as a bevel chamfer, and the chamfer of the edge of some step portions 1013 is provided as a round chamfer.

[0062] In some embodiments, the circular chamfer corresponds to an arc of R, where 0 < R ≤ π / 2. When the arc of the circular chamfer is π / 2, the end surface of the step portion 1013 facing the cavity 1011 is perpendicular to the extension plane of the diaphragm 103, and in this case, the difficulty of forming the circular chamfer is relatively small, which is conducive to processing and manufacturing. When the arc of the circular chamfer is less than π / 2, for example, R = π / 12 or R = π / 6, the end surface of the step portion 1013 facing the cavity 1011 is an inclined surface. Compared with the case where the arc of the circular chamfer is π / 2, this design can further increase the contact area between the diaphragm 103 and the base 101 when the diaphragm 103 is deformed. For a step portion 1013 with a certain height, when the arc of the circular chamfer is small, the length of the inclined surface is relatively long, and thus the width of the step portion 1013 is relatively large. Therefore, the arc of the circular chamfer can be set to R = π / 4 or R = π / 3, in which case the design requirement of increasing the contact area between the diaphragm 103 and the base 101 when the diaphragm 103 is deformed can be met, while the width of the step portion 1013 is effectively limited.

[0063] It can be seen that when the arc of the circular chamfer is set to 0 < R ≤ π / 6, the contact area between the diaphragm 103 and the base 101 when the diaphragm 103 is deformed can be greatly increased at the edge of the step portion 1013; when π / 6 < R ≤ π / 3, the contact area between the diaphragm 103 and the base 101 when the diaphragm 103 is deformed can be increased, while the width of the step portion 1013 can be effectively controlled; when π / 3 < R ≤ π / 2, the width of the step portion 1013 can be well controlled, and in particular when R = π / 2, the difficulty of processing the circular chamfer can be well reduced.

[0064] It should be noted that the arcs of the circular chamfers of different step portions 1013 can be different or the same, and the specific setting can be made according to the actual requirements of the device, which will not be described here.

[0065] When the edge of the step portion 1013 is provided with a bevel chamfer, the included angle between the bevel surface forming the bevel chamfer and the top surface of the step portion 1013 facing the diaphragm 103 can also be set according to the actual situation, for example, it can be set to 120°, 135°, 150° or other sizes, which will not be described here.

[0066] Referring to FIGS. 4-8, FIGS. 4-8 show the stress at the contact point between the beam structure 1031 and the step portion 1013 when the number of step portions 1013 is different, and the stress at the contact point between the beam structure 1031 and the step portion 1013 when the width difference between two step portions 1013 is different, under a pressure of 50 kPa. FIG. 4 is a schematic diagram of the stress at the contact point between the beam structure 1031 and the step portion 1013 when one step portion 1013 is provided and no chamfer is provided. FIG. 5 is a schematic diagram of the stress at the contact point between the beam structure 1031 and the step portion 1013 when two step portions 1013 with chamfers are provided and the width difference between the two step portions 1013 is 5 µm. FIG. 6 is a schematic diagram of the stress at the contact point between the beam structure 1031 and the step portion 1013 when two step portions 1013 with chamfers are provided and the width difference between the two step portions 1013 is 7 µm. FIG. 7 is a schematic diagram of the stress at the contact point between the beam structure 1031 and the step portion 1013 when two step portions 1013 with chamfers are provided and the width difference between the two step portions 1013 is 8 µm. FIG. 8 is a schematic diagram of the stress at the contact point between the beam structure 1031 and the step portion 1013 when two step portions 1013 with chamfers are provided and the width difference between the two step portions 1013 is 10 µm.

[0067] It can be seen that when two step portions 1013 are provided and the width difference between the two step portions 1013 is 5 µm, the width of the second step portion is less than the width of the first step portion, and thus the second step portion cannot effectively support the deformed diaphragm 103, and thus the stress at the contact point between the diaphragm 103 and the substrate 101 is still large. When the width difference between the two step portions 1013 is 7 µm, both of the two step portions 1013 can effectively support the deformed diaphragm 103, and thus the stress at the contact point between the diaphragm 103 and the substrate 101 is significantly reduced, by about 10%. When the width difference between the two step portions 1013 is 8 µm, the width difference between the two step portions 1013 is further increased, and thus the support of the second step portion on the deformed diaphragm 103 is more significant, and thus the maximum stress at the stress concentration point is increased compared to when the width difference between the two step portions 1013 is 7 µm. When the width difference between the two step portions 1013 is 10 µm, the deformed diaphragm 103 is mainly supported by the second step portion, and the support of the first step portion is significantly reduced, and thus the maximum stress at the stress concentration point is substantially the same as when only one step portion 1013 is provided.

[0068] Referring to FIG. 9, a second embodiment of the present application provides a method for manufacturing the MEMS microphone 100 described above, comprising:

[0069] Step S100. Providing a substrate, the substrate comprising a first region and a second region surrounding the first region;

[0070] Step S200. Etching a recess in the first region of the substrate, and etching the inner edge of the opening of the recess as a chamfer;

[0071] Step S300. Filling a sacrificial layer in the recess, and planarizing the sacrificial layer;

[0072] Step S400. Forming a diaphragm on the sacrificial layer;

[0073] Step S500. Etching the substrate in the region corresponding to the recess to form a cavity.

[0074] Referring to FIGS. 10a-10h, for S100, a substrate 101 is provided, which includes a first region FA and a second region SA surrounding the first region FA. Specifically, the first region FA and the second region SA are defined on the substrate 101 as needed, the second region SA is arranged around the first region FA, and the first region FA corresponds to a subsequently formed cavity 1011.

[0075] For S200, a recess 1014 is etched in the first region FA of the substrate 101, and the inner edge of the opening of the recess 1014 is etched as a chamfer. Specifically, the recess 1014 is etched at the first region FA by an etching method such as photolithography, and a global dry etching is used to form a chamfer, such as a bevel chamfer or a round chamfer, at the edge of the recess 1014.

[0076] Further, more recesses can be etched at the bottom of the recess 1014 as needed, and the subsequently etched recesses have an opening smaller than the area of the bottom of the recess 1014, thereby forming a stepped recess. After the stepped recess is formed, a round chamfer can be etched at the edge of each step portion 1013 of the stepped recess by a global dry etching.

[0077] For S300, a first sacrificial layer 140 is filled in the recess, and the first sacrificial layer 140 is planarized. Specifically, the above-mentioned stepped recess is filled with silicon dioxide or other available materials, and after the first sacrificial layer 140 is solidified, the portion of the first sacrificial layer 140 protruding above the upper surface of the substrate 101 is removed, so that the first sacrificial layer 140 is flush with the upper surface of the substrate 101.

[0078] For S400, the diaphragm 103 is formed on the anchor 102. Specifically, a second sacrificial layer 150 is formed on the first sacrificial layer 140, and after the second sacrificial layer 150 is solidified, the diaphragm 103 is formed on the second sacrificial layer 150.

[0079] For S500, the substrate 101 is etched in the region corresponding to the groove 1014 to form the cavity 1011. Specifically, the substrate 101 is etched from the bottom surface of the substrate 101 through the substrate 101 to form the cavity 1011, while removing the first sacrificial layer 140 and part of the second sacrificial layer 150, and the second sacrificial layer 150 outside the first area FA is fixed as the anchor 102 to the vibrating diaphragm 103.

[0080] It can be understood that, after the vibrating diaphragm 103 is formed and before the cavity 1011 is formed, the method for manufacturing the MEMS microphone 100 further comprises:

[0081] S600. A third sacrificial layer 160 is arranged on the vibrating diaphragm 103, and then the back plate 104 is formed on the third sacrificial layer 160. Specifically, a plurality of through holes are etched on the vibrating diaphragm 103, and then the third sacrificial layer 160 is used to fill the through holes and cover the vibrating diaphragm 103, and then the surface of the third sacrificial layer 160 is planarized. Then the back plate 104 of the MEMS microphone 100 is formed on the third sacrificial layer 160, and a plurality of through holes are etched on the back plate 104. Finally, the substrate 101 is etched from the bottom surface of the substrate 101 to remove part of the substrate 101, the first sacrificial layer, part of the second sacrificial layer 150, and part of the third sacrificial layer 160.

[0082] It should be noted that those skilled in the art can understand that, in the embodiments of the present application, many technical details are proposed in order to enable the reader to better understand the present application. However, the technical solutions claimed by the present application can be realized even without these technical details and various changes and modifications based on the above embodiments. The division of the above embodiments is for the convenience of description, and should not constitute any limitation on the specific implementation mode of the present application. The embodiments can be combined and referred to each other without contradiction.

Claims

1.A MEMS microphone, comprising: a substrate defining a cavity; an anchor disposed above the substrate; a diaphragm having a beam structure fixed above the anchor, the diaphragm covering the cavity and being spaced apart from the substrate; wherein an inner edge of a side of the substrate close to the diaphragm is chamfered. 2.The MEMS microphone of claim 1, wherein the substrate is provided with a plurality of steps from the diaphragm towards the substrate, and at least an inner edge of the step closest to the diaphragm is chamfered. 3.The MEMS microphone of claim 2, wherein heights of the plurality of steps increase from the diaphragm towards the substrate. 4.The MEMS microphone of claim 2, wherein an inner edge of each of the steps is chamfered. 5.The MEMS microphone of claim 2, wherein widths of the plurality of steps increase from the diaphragm towards the substrate in a direction from an edge of the diaphragm towards a center of the diaphragm. 6.The MEMS microphone of any one of claims 1-5, wherein the chamfer is a round chamfer. 7.The MEMS microphone of claim 6, wherein the round chamfer has a radius R, and satisfies the following relationship: 0＜R≤π / 2。 8.The MEMS microphone of claim 6, wherein the round chamfer has a radius R, and satisfies the following relationship: π / 6≤R≤π / 2。 9.The MEMS microphone of claim 6, wherein the round chamfer has a radius R, and satisfies the following relationship: π / 4≤R≤π / 2。 10.The MEMS microphone of any one of claims 1-5, wherein the chamfer is an inclined chamfer. 11.A method of manufacturing the MEMS microphone of claim 1, comprising: providing a substrate, the substrate comprising a first region and a second region surrounding the first region; etching a recess in the first region of the substrate, and chamfering an inner edge of an opening of the recess; filling a sacrificial layer in the recess, and planarizing the sacrificial layer; forming a diaphragm on the sacrificial layer; etching the substrate in a region corresponding to the recess to form a cavity.

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