MEMS microphone and preparation method thereof

Abstract

The embodiment of the invention relates to the technical field of semiconductor devices, and discloses an MEMS microphone and a preparation method thereof, and the MEMS microphone comprises the components of a substrate which defines a cavity; the anchoring part is arranged above the base; the vibrating membrane is provided with a beam structure, the beam structure is fixed above the anchoring part, so that the vibrating membrane covers the cavity, and the vibrating membrane and the base are arranged at an interval; the inner edge of one side, close to the vibrating diaphragm, of the substrate is provided with a chamfer. The inner edge of the side, close to the vibrating membrane, of the substrate is arranged to be the chamfer, when the vibrating membrane bends towards one side of the substrate due to vibration, the vibrating membrane can be prevented from impacting the substrate through the chamfer, or when the vibrating membrane impacts the substrate, the contact area between the vibrating membrane and the substrate is increased, stress concentration is avoided, and therefore the risk that the vibrating membrane is damaged is reduced. Therefore, the probability of failure of the MEMS microphone due to damage of the vibrating diaphragm can be reduced, and the robustness of the MEMS microphone is enhanced.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of semiconductor devices, and in particular to a MEMS microphone and a method for manufacturing the same. Background Art

[0002] Micro-Electro-Mechanical System (MEMS) is a miniature sensor or actuator made on the basis of semiconductor materials using microelectronics and micromachining technology. MEMS microphone is a type of micro-electromechanical system. Compared with traditional electret condenser microphones, MEMS microphones have better acoustic performance, higher signal-to-noise ratio, better consistent sensitivity and lower power consumption. MEMS microphones have been widely used in smart phones, laptops and other fields to provide higher voice quality.

[0003] A MEMS microphone includes a back plate and a diaphragm that are arranged opposite to each other, which together form a variable capacitor. When the sound waves cause changes in air pressure, the moving structure of the MEMS microphone, such as the diaphragm, bends as the air pressure changes, causing the capacitance value of the variable capacitor to change. Existing MEMS microphones are prone to structural damage and device failure due to defects in their structural design, resulting in weak robustness of the MEMS microphone.

[0004] Therefore, there is an urgent need in the art for a design that can enhance the robustness of a MEMS microphone. Summary of the invention

[0005] An object of the embodiments of the present invention is to provide a MEMS microphone and a method for manufacturing the same, which can overcome the problem of weak robustness of existing MEMS microphones.

[0006] In order to solve the above technical problems, a first aspect of an embodiment of the present invention provides a MEMS microphone, including:

[0007] The base forms a cavity; the anchor is arranged above the base; the vibration membrane has a beam structure, and the beam structure is fixed above the anchor so that the vibration membrane covers the cavity and is spaced apart from the base; wherein the inner edge of the base on the side close to the vibration membrane is provided with a chamfer.

[0008] Optionally, the substrate is provided with a plurality of step portions in a direction from the vibration membrane toward the substrate, and at least an inner edge of the step portion closest to the vibration membrane is chamfered.

[0009] Optionally, the heights of the plurality of step portions increase gradually from the vibration membrane toward the substrate.

[0010] Optionally, the inner edge of each step portion is chamfered.

[0011] Optionally, from the direction from the vibration membrane toward the substrate, the widths of the plurality of step portions gradually increase in the direction from the edge of the vibration membrane toward the center of the vibration membrane.

[0012] Optionally, the chamfer is a round chamfer.

[0013] Optionally, the radius of the rounded corner is R, and satisfies the following relationship: 0<R≤π / 2.

[0014] Optionally, the radius of the rounded corner is R, and satisfies the following relationship: π / 6≤R≤π / 2.

[0015] Optionally, the radius of the rounded corner is R, and satisfies the following relationship: π / 4≤R≤π / 2.

[0016] Optionally, the chamfer is an oblique chamfer.

[0017] A second aspect of an embodiment of the present invention provides a method for preparing the above-mentioned MEMS microphone, comprising:

[0018] Providing a substrate, the substrate comprising a first area and a second area surrounding the first area;

[0019] Etching a groove in the first area of ​​the substrate, and etching the inner edge of the opening of the groove into a chamfer;

[0020] Filling a sacrificial layer in the groove and planarizing the sacrificial layer;

[0021] forming a vibration membrane on the sacrificial layer;

[0022] The substrate is etched in a region corresponding to the groove to form a cavity.

[0023] Compared with the related art, the embodiment of the present invention sets the inner edge of the substrate close to the diaphragm as a chamfer. When the diaphragm bends toward the substrate due to vibration, the chamfer can prevent the diaphragm from hitting the substrate, or increase the contact area between the two when the diaphragm hits the substrate, avoid stress concentration, and thus reduce the risk of diaphragm damage. In this way, the probability of MEMS microphone failure due to diaphragm damage can be reduced, and the robustness of the MEMS microphone can be enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0025] Figure 1 is a schematic top view of a partial structure of a MEMS microphone according to a first embodiment of the present invention;

[0026] Figure 2 yes Figure 1 A schematic cross-sectional view of the MEMS microphone structure along line AA';

[0027] Figure 3 yes Figure 2 A magnified schematic diagram of the middle A area;

[0028] Figure 4 It is a schematic diagram of stress distribution at the contact edge of the vibrating membrane when a sharp edge is set;

[0029] Figure 5 is a schematic diagram of stress distribution at the contact edge of the vibration membrane when an edge of a step portion having an extension width of 5 μm and a chamfer is provided;

[0030] Figure 6 is a schematic diagram of stress distribution at the contact edge of the vibration membrane when an edge of a step portion having an extension width of 7 μm and a chamfer is provided;

[0031] Figure 7 is a schematic diagram of stress distribution at the contact edge of the vibration membrane when an edge of a step portion having an extension width of 8 μm and a chamfer is provided;

[0032] Figure 8 is a schematic diagram of stress distribution at the contact edge of the vibration membrane when an edge of a step portion having an extension width of 10 μm and a chamfer is provided;

[0033] Fig. 9 is a flow chart of a method for preparing a MEMS microphone provided by the present invention;

[0034] Fig.10a is a schematic diagram of a structure in which a groove is formed on a substrate;

[0035] Fig.10b is a schematic diagram of a structure in which a first sacrificial layer is filled in a groove;

[0036] Fig.10c is a schematic diagram of the structure of the planarized first sacrificial layer;

[0037] Fig.10d is a schematic diagram of a structure in which a second sacrificial layer is formed on a substrate;

[0038] Fig.10e is a schematic diagram of a structure in which a vibration membrane is arranged on the second sacrificial layer;

[0039] Fig.10f is a schematic diagram of a structure in which a third sacrificial layer is provided on the vibration membrane;

[0040] Figure 10gis a schematic diagram of a structure in which a back plate is arranged on the third sacrificial layer;

[0041] Fig.10h Schematic diagram of the structure of a MEMS microphone formed after etching the substrate and sacrificial layer. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, it can be understood by those skilled in the art that in the embodiments of the present invention, many technical details are provided to enable readers to better understand the present invention. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present invention can be implemented.

[0043] In the embodiments of the present invention, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific direction, or to be constructed and operated in a specific direction.

[0044] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those skilled in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0045] In addition, the terms "installed", "set", "provided with", "opened", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, "plurality" means two or more.

[0047] In some MEMS microphones, the vibrating membrane has a beam structure and is fixed to an anchor through the beam structure, thereby covering the cavity of the substrate in the MEMS microphone. A back plate is also provided on the vibrating membrane, and there is a gap between the vibrating membrane and the back plate to form a variable capacitor. When the MEMS microphone is working, the vibrating membrane vibrates under the influence of sound pressure, and bends during vibration to change the capacitance value of the variable capacitor. However, since there is no support between the beam structure and the substrate, during the vibration of the vibrating membrane, the beam structure not only serves as a stress concentration point for bending deformation, but also repeatedly hits the edge of the substrate and continues to be stressed, making the vibrating membrane extremely vulnerable to damage. Generally speaking, the stress at the contact point between the vibrating membrane and the substrate can be reduced by increasing the width of the beam structure, but this will result in a decrease in the sensitivity of the device; alternatively, the edge of the substrate can be brought closer to the anchor to reduce the stress at the contact point, but this will cause the anchor to be stressed, resulting in an increased risk of failure.

[0048] The purpose of the present invention is to reduce the stress between the vibration membrane and the edge of the substrate without changing the configuration of the vibration membrane and without adding other structures, thereby reducing the risk of damage to the vibration membrane and making the MEMS microphone robust.

[0049] An embodiment of the present invention provides a MEMS microphone, comprising: a substrate, which encloses a cavity; an anchor, which is arranged above the substrate; a vibration membrane, which has a beam structure, and the beam structure is fixed above the anchor, so that the vibration membrane covers the cavity and is spaced apart from the substrate; wherein the inner edge of the substrate on a side close to the vibration membrane is provided with a chamfer.

[0050] Another embodiment of the present invention provides a method for preparing the above-mentioned MEMS microphone, comprising: providing a substrate, the substrate comprising a first area and a second area surrounding the first area; etching a groove in the first area of ​​the substrate, and etching the inner edge of the opening of the groove into a chamfer; filling a sacrificial layer in the groove and flattening the sacrificial layer; forming a vibration membrane on the sacrificial layer; and etching the substrate in an area corresponding to the groove to form a cavity.

[0051] The core of this embodiment is to set the inner edge of the substrate close to the diaphragm as a chamfer. When the diaphragm bends toward the substrate due to vibration, the chamfer can prevent the diaphragm from hitting the substrate, or increase the contact area between the two when the diaphragm hits the substrate, avoid stress concentration, and thus reduce the risk of diaphragm damage. In this way, the probability of MEMS microphone failure due to diaphragm damage can be reduced, and the robustness of the MEMS microphone can be enhanced.

[0052] The implementation details of the MEMS microphone of this embodiment are described in detail below. The following content is only provided for easy understanding of the implementation details and is not necessary for implementing this solution.

[0053] See also Figures 1 to 3 The substrate 101 of the MEMS microphone 100 of this embodiment is set to be annular, such as a square ring or a circular ring, and the substrate 101 encloses a cavity 1011, which runs through 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 substrates that meet design requirements.

[0054] The anchor 102 is disposed on the substrate 101 . For example, there are a plurality of anchors 102 . The plurality of anchors 102 are disposed on the substrate 101 at intervals around the axis of the substrate 101 . The anchor 102 may be made of silicon nitride or silicon dioxide.

[0055] The vibration membrane 103 has a beam structure 1031 and a vibration part 1032. The beam structure 1031 and the vibration part 1032 may be formed integrally. The number of the beam structures 1031 may be the same as the number of the anchors 102. The vibration membrane 103 fixes the beam structures 1031 to the anchors 102 one by one, so that the vibration part 1032 covers the cavity 1011, and there is a gap between the vibration membrane 103 and the substrate 101.

[0056] Generally speaking, when the diaphragm 103 bends due to vibration, the beam structure 1031 is subjected to stress and collides with the edge 1012 of the substrate 101. Since the edge of the conventional substrate is a right-angle edge, the beam structure 1031 is prone to stress concentration during the collision, resulting in damage to the diaphragm 103. In the present invention, the edge 1012 is chamfered to increase 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 to increase the contact area between the beam structure 1031 and the edge 1012, the stress generated by the collision can be effectively dispersed, the risk of damage to the beam structure 1031 is reduced, and the robustness of the MEMS microphone 100 is enhanced.

[0057] In some embodiments, the inner wall of the substrate 101 is provided with a plurality of steps 1013 in the direction from the vibration membrane 103 toward the substrate 101. At least the edge 1012a of the step 1013 closest to the vibration membrane 103 is chamfered. By providing a plurality of steps 1013, the contact points between the beam structure 1031 and the substrate 101 are increased, and the stress generated when the beam structure 1031 collides with the substrate 101 can be further dispersed, avoiding stress concentration, and making the MEMS microphone 100 more robust.

[0058] It should be noted that the width of each step portion 1013 gradually increases in the direction from the vibration membrane 103 to the substrate 101. In other words, the further away the step portion 1013 is from the vibration membrane 103, the closer its edge is to the center position of the vibration portion 1032, and in the direction from the vibration membrane 103 to the substrate 101, the size of each step portion 1013 is larger than the previous step portion 1013.

[0059] In some embodiments, the heights of different steps 1013 gradually increase in the direction from the vibrating membrane 103 toward the substrate 101. When the vibrating membrane 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 vibrating membrane 103 gradually decreases, and the amplitude of the bending deformation also gradually decreases. In particular, at the position with the beam structure 1031, due to the effect of the beam structure 1031, the amplitude of the bending deformation of the vibrating membrane 103 is small. Therefore, the height of the step portion 1013 near the edge of the vibrating membrane 103 is set to be smaller, while the height of the step portion 1013 far from the edge of the vibrating membrane 103 is set to be larger. In this way, when the vibrating membrane 103 is affected by the sound pressure, it can be ensured that the vibrating membrane 103 falls on each step portion 1013 at the same time to disperse the stress on the vibrating membrane 103. When the pressure on the vibrating membrane 103 increases, the effect of the above setting is particularly significant.

[0060] In some embodiments, the widths of different steps 1013 in the direction from the edge of the vibration membrane 103 to its center position are also configured so that when the pressure on the vibration membrane 103 increases, the vibration membrane 103 can fall on each step 1013 at the same time.

[0061] See again Figure 2 and Figure 3 , the step portion 1013 is used as three for explanation. Among them, the step portions arranged in sequence from the edge of the vibration membrane 103 to its center position are the first step portion 1013a, the second step portion 1013b and the third step portion 1013c, the interval between the first step portion 1013a and the vibration membrane 103 can be the height H1 of the anchor 102, the height of the first step portion 1013a is H2, then the interval between the second step portion 1013b and the vibration membrane 103 is H1+H2, the height of the second step portion 1013b is H3, then the interval between the third step portion 1013c and the vibration membrane 103 is H1+H2+H3, and the height of the third step portion 1013c is H4. In some embodiments, H2<H3<H4 may be satisfied.

[0062] In addition, the width of the portion of the first step portion 1013a that exceeds the anchor 102 is S1, the width of the portion of the second step portion 1013b that exceeds the anchor 102 is S2, and the width of the portion of the third step portion 1013c that exceeds the anchor 102 is S3. Among them, S1<S2<S3, and the difference ΔS1 between S2 and S1 and the difference ΔS2 between S3 and S2 can be ΔS1<ΔS2, or ΔS1=ΔS2, or ΔS1>ΔS2.

[0063] It is understandable that the specific number of step portions 1013, the specific heights of different step portions 1013, the specific widths of different step portions 1013, and the differences between the heights and the widths of different step portions 1013 can be specifically set according to different MEMS microphones, which will not be elaborated here.

[0064] In some embodiments, in order to save processing steps and reduce manufacturing difficulty, the edge of the step portion 1013 farthest from the vibration membrane 103 may not be set as a chamfer, but maintained at a right angle. Take the third step portion 1013c as an example. At this time, the edge of the third step portion 1013c is relatively sharp for the vibration membrane 103. In order to prevent the vibration membrane 103 from being deeply sunk into the edge of the third step portion 1013c and damaged by excessive pressure, the value of H3 / ΔS2 needs to be set large enough. In this way, when the vibration membrane 103 is subjected to a large pressure and bends and deforms toward the substrate 101, the edge of the second step portion 1013b can well block the vibration membrane 103, reduce the amplitude of the vibration membrane 103 continuing to deform, and prevent the vibration membrane 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 vibration membrane 103, it is difficult for the vibration membrane 103 to hit the edge of the third step portion 1013c. Therefore, when manufacturing the third step portion 1013c, the specific position of its edge within a certain range will not have a significant impact on the device. Specifically, there are usually errors in the actual manufacturing process, but in the above design, whether the edge position of the third step portion 1013c exceeds or is less than a certain range of the predetermined position, such as ±10μm, it will not affect the effectiveness of the device.

[0065] In some other embodiments, the edge of each step portion 1013 is configured as a chamfer. This configuration can further enhance the robustness of the MEMS microphone 100.

[0066] Optionally, the chamfers set at the edges of the step portion 1013 are oblique chamfers or round chamfers. The round chamfers are preferably used. Compared with oblique chamfers, the round chamfers can increase the contact area between the two when the vibration membrane 103 hits the substrate 101, and because the round chamfers do not have edges, stress concentration on the vibration membrane 103 can be further avoided. Of course, oblique chamfers and round chamfers can also be set at the same time, that is, the chamfers of some edges of the step portions 1013 are set as oblique chamfers, while the chamfers of some edges of the step portions 1013 are set as round chamfers.

[0067] In some embodiments, the radius of the fillet is R, and 0<R≤π / 2. When the radius of the fillet is π / 2, the end surface of the step portion 1013 facing the cavity 1011 is perpendicular to the extension plane of the vibration membrane 103. At this time, it is less difficult to form a fillet, which is conducive to processing and manufacturing. When the radius of the fillet 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 radius of the fillet is π / 2, this design can further increase the contact area between the vibration membrane 103 and the substrate 101 when the vibration membrane 103 is deformed. For a step portion 1013 having a specific height, when the radius of the rounded chamfer is smaller, the length of the inclined surface will be longer, thereby making the width of the step portion 1013 larger. Therefore, the radius of the rounded chamfer can be set to R=π / 4 or R=π / 3. At this time, the design requirement of increasing the contact area between the vibration membrane 103 and the substrate 101 when it is deformed can be taken into account while effectively limiting the width of the step portion 1013.

[0068] It can be seen that when the radius of the fillet is set to 0<R≤π / 6, the contact area between the vibration membrane 103 and the substrate 101 when it 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 vibration membrane 103 and the substrate 101 when it 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, especially when R=π / 2, the processing difficulty of the fillet can be well reduced.

[0069] It should be noted that the radians of the rounded chamfers of different step portions 1013 may be different or the same, and may be specifically set according to the actual requirements of the device, which will not be elaborated here.

[0070] When the edge of the step portion 1013 is set to be a chamfer, the angle formed between the inclined surface forming the chamfer and the top surface of the step portion 1013 facing the vibration membrane 103 can also be set according to actual conditions, for example, it can be set to 120°, 135°, 150° or other sizes, which will not be elaborated here.

[0071] See also Figures 4 to 8 , under a pressure of 50 kPa, the stress magnitude at the contact point between the beam structure 1031 and the step portion 1013 when different numbers of step portions 1013 are provided, and the stress magnitude at the contact point between the beam structure 1031 and the step portion 1013 when the width difference between the two step portions 1013 is different. Among them, Figure 4 A schematic diagram of stress at the contact point between the beam structure 1031 and the step portion 1013 when a step portion 1013 is provided and no chamfer is provided; Figure 5 A schematic diagram of stress at the contact point between the beam structure 1031 and the step portion 1013 when two chamfered step portions 1013 are provided and the width difference between the two step portions 1013 is 5 μm; Figure 6 A schematic diagram of stress at the contact point between the beam structure 1031 and the step portion 1013 when two chamfered step portions 1013 are provided and the width difference between the two step portions 1013 is 7 μm; Figure 7 A schematic diagram of stress at the contact point between the beam structure 1031 and the step portion 1013 when two chamfered step portions 1013 are provided and the width difference between the two step portions 1013 is 8 μm; Figure 8 A schematic diagram of stress at the contact point between the beam structure 1031 and the step portion 1013 when two chamfered step portions 1013 are provided and the width difference between the two step portions 1013 is 10 μm.

[0072] 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, since the width of the second step portion is smaller than the width of the first step portion, it cannot effectively support the deformed vibration membrane 103, so the stress at the contact point between the vibration membrane 103 and the substrate 101 is still very large. When the width difference between the two step portions 1013 is 7 μm, both step portions 1013 can effectively support the deformed vibration membrane 103, so the stress at the contact point between the vibration membrane 103 and the substrate 101 is significantly reduced, and the reduction range is about 10%. When the width difference between the two step portions 1013 is 8 μm, since the width difference between the two step portions 1013 is further increased, the supporting effect of the second step portion after the vibration membrane 103 is deformed is more significant, so the maximum stress at the stress concentration point is increased compared to when the width difference is 7 μm. When the width difference between the two step portions 1013 is 10 μm, the vibration membrane 103 is mainly supported by the second step portion after deformation, and the supporting effect of the first step portion is significantly reduced. Therefore, the maximum stress at the stress concentration point is roughly equivalent to that when there is only one step portion 1013.

[0073] See also Fig. 9 A second embodiment of the present invention provides a method for preparing the above-mentioned MEMS microphone 100, comprising:

[0074] S100. Providing a substrate, the substrate comprising a first region and a second region surrounding the first region;

[0075] S200. Etching a groove in the first region of the substrate, etching the inner edge of the opening of the groove into a chamfer;

[0076] S300. Filling a sacrificial layer in the groove and planarizing the sacrificial layer;

[0077] S400. forming a vibration membrane on the sacrificial layer;

[0078] S500 . Etching the substrate in a region corresponding to the groove to form a cavity.

[0079] See also Figure 10a to Figure 10h , for S100. Provide a substrate 101, the substrate 101 includes a first area FA and a second area SA surrounding the first area FA. Specifically, on the substrate 101, the first area FA and the second area SA are divided according to the requirements, the second area SA is arranged around the first area FA, and the first area FA corresponds to the cavity 1011 formed subsequently.

[0080] For S200, a groove 1014 is etched in the first area FA of the substrate 101, and the inner edge of the opening of the groove 1014 is etched into a chamfer. Specifically, the groove 1014 is etched in the first area FA by etching methods such as photolithography, and a chamfer, such as an oblique chamfer or a round chamfer, is formed at the edge of the groove 1014 by global dry etching.

[0081] Further, more grooves can be etched at the bottom of the groove 1014 as needed, and the opening of the subsequently etched groove is smaller than the bottom area of ​​the groove 1014, thereby forming a stepped groove. After the stepped groove is formed, global dry etching can be continued to etch a round chamfer at the edge of each step portion 1013 of the stepped groove.

[0082] For S300, fill the first sacrificial layer 140 in the groove and planarize the first sacrificial layer 140. Specifically, fill the stepped groove with silicon dioxide or other available materials, and after the first sacrificial layer 140 is cured, remove the portion of the first sacrificial layer 140 that exceeds the upper surface of the substrate 101, so that the first sacrificial layer 140 is flush with the upper surface of the substrate 101.

[0083] Regarding S400 , the vibration film 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 vibration film 103 is formed on the second sacrificial layer 150 .

[0084] For S500, the substrate 101 is etched in the area corresponding to the groove 1014 to form a cavity 1011. Specifically, etching is performed from the bottom surface of the substrate 101 to penetrate the substrate 101 to form the cavity 1011, and the first sacrificial layer 140 and part of the second sacrificial layer 150 are removed at the same time. The second sacrificial layer 150 located outside the first area FA is used as an anchor 102 to fix the vibration membrane 103.

[0085] It can be understood that after forming the vibration membrane 103 and before forming the cavity 1011, the method for preparing the MEMS microphone 100 further includes:

[0086] S600. A third sacrificial layer 160 is disposed on the vibrating membrane 103, and a back plate 104 is formed on the third sacrificial layer 160. Specifically, a plurality of through holes are etched on the vibrating membrane 103, and the third sacrificial layer 160 is used to fill the through holes and cover the vibrating membrane 103, and then the surface of the third sacrificial layer 160 is flattened. Then, a 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, etching is performed from the bottom surface of the substrate 101 to remove part of the substrate 101, all of the first sacrificial layer, part of the second sacrificial layer 150, and part of the third sacrificial layer 160.

[0087] The MEMS microphone and the preparation method thereof provided in the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above implementation methods is only used to help understand the ideas of the present invention. There may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A MEMS microphone, characterized in that: include: The base encloses a cavity; An anchoring member, disposed above the base; A vibration membrane having a beam structure, wherein the beam structure is fixed above the anchor, so that the vibration membrane covers the cavity and is spaced apart from the substrate; Wherein, an inner edge of a side of the substrate close to the vibration membrane is provided with a chamfer.

2. The MEMS microphone according to claim 1, characterized in that: The base is provided with a plurality of step portions in a direction from the vibration membrane toward the base, and at least an inner edge of the step portion closest to the vibration membrane is chamfered.

3. The MEMS microphone according to claim 2, characterized in that: The heights of the plurality of step portions gradually increase from the vibration film toward the base.

4. The MEMS microphone according to claim 2, characterized in that: The inner edge of each step portion is chamfered.

5. The MEMS microphone according to claim 2, characterized in that: The plurality of step portions have widths that gradually increase in a direction from an edge of the diaphragm toward a center of the diaphragm, from the diaphragm toward the base.

6. The MEMS microphone according to any one of claims 1 to 5, characterized in that: The chamfer is a round chamfer.

7. The MEMS microphone according to claim 6, characterized in that: The radius of the fillet is R, and satisfies the following relationship: 0＜R≤π / 2。 8. The MEMS microphone according to claim 6, characterized in that: The radius of the fillet is R, and satisfies the following relationship: π / 6≤R≤π / 2。 9. The MEMS microphone according to claim 6, characterized in that: The radius of the fillet is R, and satisfies the following relationship: π / 4≤R≤π / 2。 10. The MEMS microphone according to any one of claims 1 to 5, characterized in that: The chamfer is an oblique chamfer.

11. A method for preparing the MEMS microphone according to claim 1, characterized in that: include: Providing a substrate, the substrate comprising a first area and a second area surrounding the first area; Etching a groove in the first area of ​​the substrate, and etching the inner edge of the opening of the groove into a chamfer; Filling a sacrificial layer in the groove and planarizing the sacrificial layer; forming a vibration membrane on the sacrificial layer; The substrate is etched in a region corresponding to the groove to form a cavity.

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