WO2020133334A1

WO2020133334A1 - Mems sound sensor, mems microphone and electronic device

Info

Publication number: WO2020133334A1
Application number: PCT/CN2018/125301
Authority: WO
Inventors: 何宪龙; 谢冠宏; 邱士嘉
Original assignee: 共达电声股份有限公司
Priority date: 2018-12-29
Filing date: 2018-12-29
Publication date: 2020-07-02
Also published as: CN110603818A; CN110603818B

Abstract

Disclosed is an MEMS sound sensor, comprising: a substrate; and a first sound sensing unit and a second sound sensing unit arranged on the substrate, wherein the first sound sensing unit is used for detecting a sound by means of at least one of an air sound pressure change and a mechanical vibration; the first sound sensing unit comprises a first back plate, and a first vibration diaphragm arranged opposite the first back plate and with a gap between same and the first back plate; the first vibration diaphragm and the first back plate form a capacitance structure; the substrate is provided with a first back hole to expose the first vibration diaphragm, and a first connecting post to hang the first vibration diaphragm on the first back plate; an edge area of the first vibration diaphragm is provided with at least one mass block; and the first back plate is provided with an opening.

Description

MEMS sound sensor, MEMS microphone and electronic equipment

Technical field

The invention relates to the technical field of microphones, in particular to a MEMS sound sensor and its preparation method, MEMS microphone and electronic equipment.

Background technique

MEMS (Micro-Electro-Mechanical System) microphone is an electric energy transducer manufactured based on MEMS technology, which has the advantages of small size, good frequency response characteristics and low noise. With the miniaturization of electronic devices, MEMS microphones are more and more widely used in these devices. The MEMS sound sensor is a key device in the MEMS microphone, and its performance directly affects the performance of the entire MEMS microphone. Traditional MEMS sound sensors can only work in scenes with low environmental noise. Once the environmental noise increases, the desired sound cannot be detected, and other sensors need to be added to work, which is not conducive to miniaturization of products.

Summary of the invention

According to various embodiments of the present application, a MEMS sound sensor, a MEMS microphone, and an electronic device are provided.

A MEMS sound sensor includes: a substrate; a first sound sensing unit provided on the substrate; and a second sound sensing unit provided on the substrate; the second sound sensing unit and the The first sound sensing unit is electrically isolated; wherein the first sound sensing unit is used to detect sound through at least one of air sound pressure change and mechanical vibration; the first sound sensing unit includes a first A back plate, which is arranged on the substrate through a first insulating layer, and a first diaphragm is arranged opposite to the first back plate and has a gap with the first back plate; the first diaphragm and The first back plate forms a capacitor structure, and a first back hole is formed on the substrate to expose the first diaphragm and the first connecting post, including a first end and a second end that are oppositely arranged; The first end of a connecting post is fixedly connected to the first backplane, and the second end of the first connecting post is electrically connected to the middle region of the first diaphragm to suspend the first diaphragm On the first backplane; the edge region of the first diaphragm is provided with at least one mass; the first backplane is provided with an opening; the opening is used to expose the mass to make the There is a gap between the mass and the first backplane, or the opening serves as an acoustic hole on the first backplane.

A MEMS microphone includes a printed circuit board, a MEMS sound sensor provided on the printed circuit board, and an integrated circuit provided on the printed circuit board; the MEMS microphone uses the MEMS as described in any of the foregoing embodiments Sound sensor.

An electronic device includes a device body and a MEMS microphone provided on the device body; the MEMS microphone uses the MEMS microphone as described above.

The details of one or more embodiments of the application are set forth in the drawings and description below. Other features, objects, and advantages of this application will become apparent from the description, drawings, and claims.

BRIEF DESCRIPTION

In order to more clearly explain the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some embodiments of the present application. For those of ordinary skill in the art, without paying any creative work, drawings of other embodiments can be obtained based on these drawings.

FIG. 1 is a cross-sectional view of the MEMS sound sensor in the first embodiment.

2 to 4 are cross-sectional views of the first sound sensor unit in the second to fourth embodiments.

5 is a schematic diagram of forming a second sub-portion in a mass in an embodiment.

6 is a cross-sectional view of the first sound sensing unit in the fifth embodiment.

7 is a schematic structural view of a second diaphragm in the first embodiment.

8 is a partial schematic view of the second diaphragm in the second embodiment.

9 is a schematic diagram of the elastic structure in FIG. 8 in an open state.

10 to 11 are partial schematic diagrams of the second diaphragm in the third and fourth embodiments.

12 is a cross-sectional view of the pleated structure in FIG. 11.

13 is a partial schematic view of the second diaphragm in the fifth embodiment.

14 is a schematic structural view of a MEMS microphone in an embodiment.

15 is a schematic structural diagram of a MEMS microphone in another embodiment.

detailed description

In order to make the purpose, technical solutions and advantages of the present application more clear, the following describes the present application in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

In the description of this application, it should be understood that the terms "center", "lateral", "upper", "lower", "left", "right", "vertical", "horizontal", "top", " The "orientation", "inner", and "outer" orientations are based on the orientations or positional relations shown in the drawings, only for the convenience of describing the application and simplifying the description, rather than indicating or implying the device or The element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application. In addition, it should be noted that when an element is referred to as being "formed on another element", it may be directly connected to another element or there may be a center element at the same time. When an element is considered to be "connected" to another element, it can be directly connected to another element or there can be centered elements at the same time. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present.

FIG. 1 is a schematic structural diagram of a MEMS sound sensor in an embodiment. FIG. 1 is a schematic structural diagram of a MEMS sound sensor in an embodiment. The MEMS sound sensor can also be called a MEMS sensor or a MEMS chip. The MEMS sound sensor includes a substrate 110, a first sound sensing unit 200 formed on the substrate 110, and a second sound sensing unit 300 formed on the substrate 110. The first sound sensing unit 200 and the second sound sensing unit 300 are electrically insulated from each other. The first sound sensing unit 200 can be used to detect sound by at least one of air sound pressure change and mechanical vibration, that is, the first sound sensor unit 200 can perform changes in air sound pressure caused by sound Sound detection can be achieved through detection, and sound detection can also be achieved through vibration caused by sound or mechanical external force. It can be understood that the vibration referred to in this case is exemplified by vibration of bones such as ear bones or other solids caused by sound or mechanical external force. The second sound sensing unit 300 may adopt the structure of a conventional MEMS sound sensor, or may adopt the same structure as the first sound sensing unit 200. In this embodiment, the second sound sensing unit 300 is used to realize sound detection through changes in air sound pressure.

The above MEMS sound sensor integrates two sound sensing units, so the two sound sensor units can work at the same time in the sound detection process, so that the sound detection and recognition can be performed according to the detection results of the two, with high accuracy. In addition, in this embodiment, the first sound sensing unit 200 can detect sound according to mechanical vibration in addition to detecting sound through changes in air sound pressure. Therefore, when the environmental noise is large, the MEMS sound sensor can be placed close to the human ear bones or vocal cords and other solid materials, so as to detect the sound by detecting the vibration caused by the speaking process. When the environmental noise is small, and is not close to the human ear bones or vocal cords and other solid materials, the change of air sound pressure can be detected and output by the first sound sensing unit 200 and the second sound sensing unit 300, at this time The integrated chip that processes the sound signal can calculate and process the sound output by the two according to a predetermined algorithm, thereby obtaining a more ideal sound signal and improving the signal-to-noise ratio of the entire device.

The above-mentioned MEMS sound sensor integrates the first sound sensing unit 200 and the second sound sensing unit 300 on the same substrate, which has a smaller product volume compared to the independently arranged structure, which is conducive to achieving a small product Change. In an embodiment, the first sound sensing unit 200 and the second sound sensing unit 300 are integrally formed during the manufacturing process, and both use a MEMS manufacturing process, thereby simplifying the entire production process and greatly improving production efficiency.

In this embodiment, the first insulating layer 120 is formed on the substrate 110. The first sound sensing unit 200 includes a first back plate 210, a first diaphragm 220, and a first connecting post 230. The first back plate 210 may also be referred to as a back plate. The first backplane 210 is disposed on the first insulating layer 120. The first diaphragm 220 is disposed opposite to the first back plate 210, and a gap 20 is formed between the two. The gap 20 is not filled with other substances and is an air gap. The first diaphragm 220 and the first back plate 210 constitute a capacitor structure. In this embodiment, the shape of the first diaphragm 220 is not particularly limited. For example, the first diaphragm 220 may have a circular shape, a square shape, or the like. The substrate 110 is provided with a first back hole 112 to expose the first diaphragm 220. The first connecting post 230 includes a first end 230a and a second end 230b disposed oppositely. The first end 230a is fixedly connected to the first backplane 210. The second end 230b is connected to the middle region of the first diaphragm 220, and is electrically connected to the first diaphragm 220. The first connecting post 230 is connected to the first diaphragm 220 through the second end 230b, thereby suspending the first diaphragm 220 on the back plate. The edge area around the first diaphragm 220 after being suspended does not need other fixing structures to support and fix it, so that the sensitivity of the entire first diaphragm 220 can be greatly improved to meet people's use requirements. In this embodiment, the edge region of the first diaphragm 220 is provided with at least one mass 222. In this case, the edge area is relative to the middle area, that is, the edge area is an area away from the first connecting post 230. In this embodiment, an opening 22 is provided in the area of the first backplane 210 corresponding to the mass 222 to expose and release the mass 222 and to allow a gap 24 between the mass 222 and the first backplane 210.

In an embodiment, the substrate 110 may be a silicon substrate directly. It can be understood that the substrate 110 may also be other base structures, such as an SOI base. The first insulating layer 110 may be a dielectric oxide layer, such as silicon dioxide. The substrate 110 is also formed with a material layer 130 formed when preparing the first diaphragm 220 and a dielectric oxide layer 140 for isolating the material layer 130 and the substrate 110. The first vibrating film 220 may adopt single crystal silicon, polycrystalline silicon, silicon nitride, silicon-rich silicon nitride, silicon germanium compound (SiGe), metal, or the like. Among them, the metal may be aluminum (Al), aluminum-copper alloy (AlCu), platinum (Pt), gold (Au), and the like. Therefore, the material layer 130 may also use any one of the foregoing materials. When the first diaphragm 220 uses silicon nitride or silicon-rich silicon nitride as a material, a layer of conductive material needs to be added as an electrode of the first diaphragm 220. In this embodiment, the first diaphragm 220 is completely isolated from the substrate 110, that is, the first diaphragm 220 is completely suspended and connected by the first connecting post 230 without borrowing other fixing structures to the periphery of the first diaphragm 220 To be fixed. The periphery of the suspended first diaphragm 220 is suspended, which can release residual stress, so that the first diaphragm 220 has higher sensitivity. In one embodiment, the first diaphragm 220 is doped or ion implanted as necessary. The doping may be N-type doping or P-type doping, so that the first diaphragm 220 has better conductivity. In an embodiment, when the conductive layer in the first backplane 210 uses polysilicon or silicon-germanium compound, doping or ion implantation is also required to make the backplane have better conductivity.

For the first sound sensing unit 200, when sound changes the sound pressure of the air, the air will pass through the opening 22 on the first back plate 210 and enter the first back plate 210 and the first diaphragm 220 through the gap 24 In the gap 20 between them, so that the first diaphragm 220 vibrates under the action of the air pressure or sound pressure, or the change of the air pressure below the first diaphragm 220 directly pushes the first diaphragm 220 to make the first diaphragm 220 vibrate , The capacitance structure will produce varying capacitance to achieve the detection of sound waves. The changed capacitance signal can be processed through an ASIC (Application Specific Integrated Circuit) integrated circuit (IC) chip and the electrical signal after the acoustoelectric conversion is output. When the capacitance changes due to air pressure or sound pressure, since the mass area 222 is provided in the edge area of the first diaphragm 220, even a small change in air pressure can generate a large torque, which makes the first diaphragm 220 produce a more obvious Vibration greatly improves the sensitivity of the first sound sensing unit 200. In addition, since air can enter directly through the opening 22 and enter the gap 24 between the mass 222 and the first back plate 210 to cause vibration of the first diaphragm 220, the first back plate 210 may not have sound holes, thereby The area of the electrodes in the first backplane 210 is larger, which ensures that the first sound sensing unit 200 has a high capacitance change, which further improves the sensitivity of the detection process. The gap 24 between the mass 222 and the first back plate 210 can be set as needed to reduce the damping effect that exists when air enters and exits the gap 20 as much as possible.

When the first sound sensing unit 200 directly or indirectly comes into contact with bones (such as ear bones, vocal cords, etc.) that conduct sounds (usually the side where the first diaphragm 220 is located close to the ear bones), due to the corresponding The bones will mechanically vibrate, which will cause the first diaphragm 220 to vibrate. Since the mass region 222 is provided in the edge area of the first diaphragm 220, even a small mechanical vibration can cause the vibration of the first diaphragm 220 to realize the detection of the sound, that is, the first sound sensing unit 200 has high sensitivity. The first sound sensing unit 200 in this embodiment can work as a vibration sensor, so that when the user is in a noisy environment, it can be brought into contact with the human body's sound conduction tissue (such as the ear bones). The vibration of the solid material realizes the detection of sound, and the entire detection process will not be disturbed by environmental noise, so that the entire first sound sensing unit 200 has a high signal-to-noise ratio.

The mass 222 in the first diaphragm 220 includes at least one of a first part 222a and a second part 222b. The first portion 222a is formed on the upper surface of the first diaphragm 220, and the second portion 222b is formed on the lower surface of the first diaphragm 220. In this case, the side of the first diaphragm 220 facing the first back plate 210 is an upper surface, and the side away from the first back plate 210 is a lower surface. The mass block 222 may be selectively set according to needs, for example, only the first part 222a or the second part 222b is set, or may be set at the same time. The quality of the first part 222a and the second part 222b can be adjusted, so as to achieve the quality adjustment of the entire mass 222, and thus the adjustment of the sensing frequency band of the entire MEMS vibration sensor. In this embodiment, the frequency detection range of the first sound sensing unit 200 is 20 Hz to 20 KHz. In FIG. 1, the mass 222 includes both the first part 222a and the second part 222b.

In one embodiment, the first backplane 210 includes a first conductive layer 214 and a protective layer covering the first conductive layer 214. Specifically, referring to FIG. 1, the first backplane 210 includes a first protective layer 216, a first conductive layer 214, and a second protective layer 212 that are sequentially stacked. The first protective layer 216 is located on the side of the first back plate 210 close to the first diaphragm 220. The first conductive layer 214 is a patterned layer. The second protective layer 212 is formed on the first protective layer 216 and completely covers the first conductive layer 214, that is, the first conductive layer 214 is surrounded by the first protective layer 216 and the second protective layer 212. The opening 22 penetrates the entire first protective layer 216 and the second protective layer 212, thereby transmitting external sound signals to the gap 20 through the gap 24, and causing the first diaphragm 220 to vibrate; or the external sound signal is transmitted by the first diaphragm The lower part of 220 passes through the gap 20 and then passes through the opening 22. Both the first protective layer 216 and the second protective layer 212 are passivation layers, ensuring that the first conductive layer 214 provided in the two layers can be isolated from corrosive gases in the air, and can avoid the first A leakage between the back plate 210 and the first diaphragm 220. The first protective layer 216 and the second protective layer 212 may be silicon nitride (silicon nitride) or silicon-rich silicon nitride (si-rich silicon nitride). In an embodiment, the surfaces of the first protective layer 216 and the second protective layer 212 must be or processed to be non-hydrophilic, that is, the surfaces of the first protective layer 216 and the second protective layer 212 are both non-hydrophilic surfaces . For example, if a very thin silicon oxide material is not completely removed, it will be attached to the protective layer, which will also cause the protective layer to be hydrophilic (hydrophilic); or the protective layer silicon nitride (silicon nitride), silicon rich Silicon nitride (si-rich silicon nitride) itself has a certain degree of hydrophilicity after the semiconductor process is completed. At this time, we can do anti-stiction coating on the MEMS sensor to change the surface characteristics of the protective layer so that It becomes a non-hydrophilic surface.

The patterned first conductive layer 214 includes a back plate electrode 214a and a diaphragm extraction electrode 214b. The first conductive layer 214 may be a polysilicon layer, a silicon germanium compound (SiGe) layer, or a metal layer. The metal of the metal layer may be aluminum (Al), aluminum-copper alloy (AlCu), platinum (Pt), gold (Au), or the like. In this embodiment, the materials of the first conductive layer 214 and the first diaphragm 220 are both polysilicon (polySi). The first sound sensor unit 200 is further formed with a backplane pad 242 and a diaphragm pad 244, as shown in FIG. 1. The back plate pad 242 is formed on the back plate electrode 214a, and the diaphragm pad 244 is formed on the diaphragm extraction electrode 214b, so as to realize electrical connection between the back plate electrode and the first diaphragm 220 and the outside, respectively.

In an embodiment, the first portion 222a of the mass 222 and the first conductive layer 214 of the first backplane 210 are formed in the same process step, that is, by pairing the first insulating layer 120 formed above the first diaphragm 220 And the first protective layer 216 is etched until the first diaphragm 220 is stopped, and then the conductive layer is filled (for example, filled with polysilicon) to form the conductive layer for preparing the first part 222a and the first back plate 210 in one piece. Due to the need to fill the previously etched grooves, the thickness of the conductive layer formed at this time is thick, and the formed conductive layer needs to be etched to the CMP (Chemical Mechanical Mechanical Polishing process) or silicon etching process The thickness of the desired backplane electrode. At this time, the first portion 222a and the first conductive layer 214 are an integrated structure, and an opening 22 needs to be formed in the back plate electrode layer through an etching process to separate the first conductive layer 214 from the first portion 222a, thereby forming a mass 222 The gap 24 between the first back plate 210. The gap 24 can be customized, and the gap 24 is large, which can reduce the air damping. In an embodiment, a conductive layer can also be generated according to the thickness of the first portion 222a of the mass 222, and then the conductive layer is etched to the thickness of the back plate electrode, and the first portion 222a is separated from the first back plate 210 Come. At this time, the height of the first portion 222a may be lower than the plane where the conductive layer is located, as shown in FIG. 2. In other embodiments, in addition to the opening 22 formed on the first back plate 210, an acoustic hole 218 may be formed, as shown in FIG. 3, so that the air damping may be further reduced.

In one embodiment, the second portion 222b and the first diaphragm 220 are formed in the same process step. Specifically, before forming the first diaphragm 220, the dielectric oxide layer 140 in the corresponding region is partially etched, or completely etched or even etched onto the silicon substrate of the substrate 110. The end point of the etching process may be determined according to the quality of the second part 222b. After the etching is completed, a material layer for preparing the first vibrating film 220 is formed above the substrate 110, and the etched area is filled during the forming process, thereby forming first vibrators each having the second portion 222b膜220。 The film 220.

In another embodiment, the second portion 222b includes a first sub-portion 222b1 and a second sub-portion 222b2, as shown in FIG. The first sub-portion 222b1 is the same as the method for forming the second portion 222b in the previous embodiment, and is formed in the same process step as the first diaphragm 220. The second sub-portion 222b2 is obtained by etching the substrate 110, see FIG. 5. Specifically, the substrate 110 is etched with a mask plate that defines the shape of the mass 222, and a bump 10 having a mass shape is formed at a corresponding position on the substrate 110, and then the entire area where the first diaphragm 220 is located is performed. The etching is performed synchronously until the dielectric oxide layer 140 is etched to stop the etching, thereby forming the second sub-portion 222b2 of the mass 222. The second sub-portion 222b2 and the first sub-portion 222b1 as well as the first diaphragm 220 and the first portion 222a form an integral body. At this time, the mass 222 has a larger mass and is located in the edge area, so that the entire first sound sensing unit 200 has high sensitivity.

In an embodiment, the mass 222 formed in the first sound sensing unit 200 includes only the second portion 222b. That is, in this embodiment, the upper surface of the first diaphragm 220 does not need to form a mass, and the first back plate 210 does not need to have an opening for the exposed mass. At this time, the opening 22 formed in the first back plate 210 serves as the sound hole of the first back plate 210 to reduce the damping, as shown in FIG. 6.

In an embodiment, the first diaphragm 220 includes a plurality of diaphragms 224 that move independently of each other, as shown in FIG. 7. 7 is a schematic diagram of the structure of the diaphragm. In this embodiment, the first diaphragm 220 includes four symmetrically distributed diaphragms 224, and each diaphragm 224 has the same structure, that is, the same mass 222 is formed thereon. By setting the first diaphragm 220 as a plurality of independently moving diaphragms 224, the sensitivity in the vibration detection process can be further improved. In an embodiment, at least two of the diaphragms 224 on the first diaphragm 220 have different structures, that is, they are asymmetrically distributed. At this time, masses 222 are provided on different diaphragms 224, and the masses 222 on each diaphragm 224 may be the same or different. It is set to the frequency detection range corresponding to the diaphragm 224, for example, the frequency detection range is 20Hz～20KHz. For example, a first diaphragm corresponding to low frequency, a second diaphragm corresponding to intermediate frequency, and a third diaphragm corresponding to high frequency may be provided in the first diaphragm 220, so that the first diaphragm of low frequency may be used to Realize the frequency detection of 100Hz～1KHz, the second module realizes the frequency detection of 1KHz～10KHz, and the third diaphragm realizes the frequency detection of 10KHz～20KHz. In other embodiments, different diaphragms 224 correspond to different frequency bands, so that the first sound sensing unit 200 has a wider frequency band detection range, and meets the user's detection requirements for multiple frequency bands.

In an embodiment, an insulating layer is provided between the diaphragms 224 to achieve electrical insulation between the diaphragms 224, so that the diaphragms 224 can independently detect the sound of the corresponding frequency band. Each diaphragm 224 is led out to the corresponding diaphragm extraction electrode 214b on the first back plate 210 through the first connection post 230, so as to be connected to the corresponding pad through the diaphragm extraction electrode 214b. At this time, the first connecting post 230 also includes a plurality of mutually insulated lead-out areas, and the first back plate 210 is also provided with a plurality of diaphragm lead-out electrodes 214b to lead each diaphragm 224 to the corresponding pad, That is, at this time, each diaphragm 224 has independent circuit paths. In other embodiments, each diaphragm 224 may also be led out using the same circuit path. In this case, the diaphragm 224 responsible for sensing the corresponding frequency band forms a capacitance with the first backplane 210 to generate a variable capacitance change signal, so that the ASIC chip processes the change signal accordingly. For the diaphragm 224 in other frequency bands, the capacitance change signal is small, and the ASIC does not process it at this time.

In an embodiment, part of the material of the second end 230b is embedded in the first diaphragm 220. The second end 230b is electrically connected to the first diaphragm 220, so that the first connecting post 230 can lead out the electrode where the first diaphragm 220 is located through the diaphragm extraction electrode 214b. At least partial material embedding of the second end 230b means that a part of the layer structure on the first connecting post 230 is embedded in the first diaphragm 220 or all the layer structures on the first connecting post 230 are embedded in the first diaphragm 220. In this embodiment, the first connecting post 230 may be embedded inside the first diaphragm 220 or embedded in and penetrate the first diaphragm 220. Therefore, the second end 230b of the first connecting post 230 may be partially not embedded, but partially embedded in or penetrate through the first diaphragm 220. The second ends 230b of the first connecting post 230 may all be embedded, but partially embedded in the first diaphragm 220, and the rest are embedded in and penetrate the first diaphragm 220. It can be understood that the second end 230b of the first connecting post 230 may also be completely embedded in the first diaphragm 220 or may be completely embedded and penetrate the first diaphragm 220. In this embodiment, the shape, structure, and number of the first connecting posts 230 are not particularly limited. For example, the cross section of the first connecting post 230 may be circular, rectangular, elliptical, semi-circular, etc., as long as it can play a role of supporting and hanging. In this case, the first connecting post 230 is cylindrical for example. The number of the first connecting posts 230 may be one or more than two. The number of the first connecting posts 230 can also be determined according to the size of the first sound sensing unit 200, for example, as the size of the first sound sensing unit 200 increases, the number of the first connecting posts 230 is increased or the A cross-sectional area of the connecting post 230 and so on.

In the above first sound sensing unit 200, the first connecting post 230 suspends the first diaphragm 220 on the first back plate 210 by embedding the first diaphragm 220, so as to realize the first diaphragm 220 and the first back plate 210 Relatively fixed between. Since the first connecting post 230 is embedded in the first diaphragm 220, the first connecting post 230 has a vertical bonding area and a horizontal bonding area with the first diaphragm 220, that is, the first connecting post 230 and the first diaphragm are increased The joint area between 220 has better mechanical connection strength, so that the performance of the first diaphragm 220 against mechanical impact force such as blow and drop resistance, rolling, roller test and the like can be improved. In addition, no other fixing structure is needed to support and fix the first vibrating membrane 220 around the suspension, so that the sensitivity of the entire first vibrating membrane 220 can be greatly improved to meet people's use requirements.

In traditional MEMS sound sensors, the mechanical sensitivity of the diaphragm is susceptible to the residual stress of the semiconductor process. Individual MEMS sound sensors are prone to variability, resulting in decreased sensitivity consistency, and even uneven distribution of diaphragm stress, causing instability (bi- The possibility of deformation occurs, which makes the final MEMS microphone acoustic performance unstable, even exceeding the specifications. The first sound sensing unit 200 in this application can have a high mechanical strength, can improve the resistance to various mechanical impact forces, and utilize the suspension type to strengthen the bonding strength of the first connecting post 230 and the first diaphragm 220 In this way, the first diaphragm 220 can freely conform to the external mechanical impact force, so that the first diaphragm 220 becomes a flexible diaphragm and does not resist the external mechanical impact force. In addition, the first diaphragm 220 in this application has no peripheral fixed points or fixed points (diaphragm anchors), that is, the periphery of the diaphragm is completely cut. This design can release the residual stress caused by the semiconductor process and greatly improve the first sound transmission. The performance consistency and manufacturability of the sensing unit 200 relaxes the manufacturing tolerance tolerance of the manufacturing and makes the manufacturing yield higher. In other embodiments, some spring-like connection structures may also be provided around the first diaphragm 220 to connect with the substrate 110. It can be understood that the structure in which the connecting post 230 in this embodiment is embedded in the first diaphragm 220 so as to suspend the first diaphragm 220 to the first back plate 210 is not limited to the structure shown in FIG. In the first sound sensing unit 200 with double back plates or double diaphragms.

In one embodiment, there is one first connecting post 230. Specifically, the first connecting post 230 is located at the center of the first diaphragm 220. The first diaphragm 220 is circular, and the first connecting post 230 is a cylinder, that is, the central axis of the first connecting post 230 intersects the center of the circle of the first diaphragm 220. By setting the first connecting post 230 to be symmetrical about the center of the first diaphragm 220, the sound pressure can be generated from the opening 22 or the first diaphragm 220 into the gap 20 to produce the most symmetrical pressure acting on the first diaphragm 220 To improve the sensitivity of the first diaphragm 220.

In an embodiment, there may be multiple first connecting posts 230. The plurality of first connecting posts 230 are distributed symmetrically with respect to the center of the first diaphragm 220, so that the first diaphragm 220 is uniformly stressed throughout. For example, there may be four first connecting posts 230, symmetrically distributed around the center of the first diaphragm 220. In an embodiment, the plurality of first connecting posts 230 are all disposed within a half of the distance from the center of the first diaphragm 220 to the edge, thereby ensuring good support performance for the first diaphragm 220 And ensure that the first diaphragm 220 has high sensitivity.

In an embodiment, the depth of the first connecting post 230 embedded in the first diaphragm 220 is greater than or equal to one-third of the thickness of the first diaphragm 220, so that the first connecting post 230 has the same thickness as the first diaphragm 220. The vertical bonding area and the horizontal bonding area, that is, the bonding area between the first connecting post 230 and the first diaphragm 220 is increased, thereby ensuring the ability of the first diaphragm 220 and the first connecting post 230 to resist external mechanical impact It is stronger and meets the performance requirements of the first diaphragm 220 against mechanical impact forces such as blow and drop resistance, rolling and roller testing.

Referring to FIG. 1, in this embodiment, the first connection pillar 230 includes a second insulating layer 232 and a second conductive layer 234 that are spaced apart from each other. Since the first connection pillar 230 is a cylinder, the shapes of the second insulating layer 232 and the second conductive layer 234 projected on the first diaphragm 220, that is, their top views are all ring-shaped structures. The number of layers of the second insulating layer 232 and the second conductive layer 234 can be set as needed, usually from the center of the first connecting post 230 to the second insulating layer 232, the second conductive layer 234, the second insulating layer 232... Up to the outermost second conductive layer 234. In the embodiment shown in FIG. 1, the second conductive layer 234 and the second insulating layer 232 are both two layers. Among them, the second insulating layer 232 is prepared in the same process as the first insulating layer 120 above the substrate 110 during the preparation. In this embodiment, they are named as the first insulating layer 120 and the Second insulating layer 232. Therefore, the materials of the first insulating layer 120 and the second insulating layer 232 are the same, and both are dielectric oxide layers.

The first end of the second conductive layer 234 is formed integrally with the diaphragm extraction electrode 214b and is electrically connected. The second end of the second conductive layer 234 is embedded in the first diaphragm 220. The second end of the second conductive layer 234 may be embedded inside the first diaphragm 220, or may be embedded in and penetrate the first diaphragm 220. In this embodiment, the materials of the first diaphragm 220, the second conductive layer 234, and the first conductive layer 214 are the same, for example, all are polysilicon. Therefore, the embedding of the same material when the second conductive layer 234 is embedded in the first diaphragm 220 will not cause an impedance problem, so there is no need to add a corresponding impedance matching structure, and the overall conductive performance is better.

The second conductive layer 234 may include two types, that is, include a first type conductive layer and a second type conductive layer. Wherein, the second end of the first-type conductive layer is embedded in the first diaphragm 220, and its embedding depth is greater than or equal to one third of the thickness of the first diaphragm 220 and less than the thickness of the first diaphragm 220. The second end of the second type conductive layer is embedded in and penetrates the entire first diaphragm 220. The second conductive layers 234 in the first connection pillar 230 may all be the first type conductive layers or all the second type conductive layers. It can be understood that the second conductive layer 234 in the first connection pillar 230 may also include the first type conductive layer and the second type conductive layer at the same time. In FIG. 1, all the second conductive layers 234 include the first type conductive layer and the second type conductive layer. In FIG. 6, all second conductive layers 234 are second-type conductive layers.

In an embodiment, the second insulating layer 232 can also be embedded inside the first diaphragm 220, thereby further increasing the bonding area of the first connecting post 230 and the first diaphragm 220, and improving the connection of the first connecting post 230 to the first diaphragm The mechanical strength of 220. The second insulating layer 232 does not embed and penetrate the first diaphragm 220, that is, the embedded depth of the second insulating layer 232 is greater than one third of the thickness of the first diaphragm 220 and less than the thickness of the first diaphragm 220. When the second insulating layer 232 is embedded and penetrates the first diaphragm 220, when the dielectric oxide layer 140 (for example, silicon oxide) is released, the material of the second insulating layer 232 will be attacked, causing the first insulating layer 232 to penetrate The material of the second insulating layer 232 of the diaphragm 220 is etched and does not exist.

In this embodiment, both the first protective layer 216 and the second protective layer 212 are made of silicon-rich silicon nitride. Using this dielectric material to wrap the first conductive layer 214 on the first backplane 210 and the second conductive layer 234 in the first connection post 230 can prevent charges from remaining outside the first connection post 230 and the first backplane Below 210. If there is residual charge, the first sound sensor unit 200 cannot have normal charge stored on the two electrode plates. At this time, the first sound sensor unit 200 cannot work normally, and the sensitivity may decrease, or even exceed the specifications.

In an embodiment, a protrusion 224 is formed on the side of the first diaphragm 220 away from the first back plate 210. The protrusion 224 is formed integrally with the first diaphragm 220, that is, the two are an integral structure. The second type conductive layer on the first connecting post 230 extends into the protrusion 224, thereby further increasing the bonding area of the first connecting post 230 and the first diaphragm 220, and improving the mechanical strength of the diaphragm connection. The second type conductive layer extends into the protrusion 224. The protrusion 224 surrounds the portion of the second type conductive layer that extends into this area. In FIG. 1, the protrusion 224 is a hollow ring structure when viewed from the bottom. In other embodiments, when the first connecting post 230 is square, the protrusion 224 may also be a hollow square structure, or the entire surface structure is shown in FIG. 6. The thickness of the protrusion 224 may not be limited. Specifically, before forming the first diaphragm 220, the formed dielectric oxide layer 140 is partially etched, or completely etched or even etched onto the silicon substrate of the substrate 110. Since the area corresponding to the side of the first diaphragm 220 away from the first back plate 210 is eventually etched to form the first back hole 112, the thickness of the protrusion 224 does not affect the overall performance. After the etching is completed, a material layer for preparing the first diaphragm 220 is formed above the substrate 110, and the etched area is filled during the forming process, thereby forming first diaphragms each having the protrusion 224 220. By forming the protrusion 224 directly on the first diaphragm 220, the rigidity of the first diaphragm 220 can be improved to a certain extent.

In an embodiment, the first connecting post 230 further includes a bearing portion 236, as shown in FIG. The carrying portion 236 is connected to the side of the first diaphragm 220 away from the first back plate 210. The bearing portion 236 is connected to at least a part of the second-type conductive layer in the first connecting post 230 to form a rivet structure. The first connecting post 230 embedded in the first diaphragm 220 can provide a horizontal force to fix the first diaphragm 220, and the increase of the bearing portion 236 can increase the horizontal contact area with the first diaphragm 220. The support force in the vertical direction can be increased, so that the support force is provided in both directions, so that the support strength of the first connecting post 230 is stronger, and the stability of the first diaphragm 220 is better. During the preparation process, the edge of the second conductive layer 234 in the first connection post 230 is located within the edge of the bearing portion 236, so there can be a greater tolerance of alignment errors during the preparation process, the process is better to do, will not There is a problem that the cracking or etching is difficult to align.

In an embodiment, the second sound sensing unit 300 includes a second back plate 310, a second diaphragm 320, and a second connecting post 330. The second backplane 310 is disposed on the first insulating layer 120. The second diaphragm 320 is disposed opposite to the second back plate 310, and a gap is formed between the two. The second diaphragm 320 and the second backplate 310 constitute a capacitor structure. In this embodiment, the shape of the second diaphragm 320 is also not particularly limited. For example, the second diaphragm 320 may have a circular shape, a square shape, or the like. The substrate 110 is provided with a second back hole 114 to expose the second diaphragm 320. The second connecting post 330 includes a first end 330a and a second end 330b that are oppositely arranged. The first end 330a is fixedly connected to the second backplane 310. The second end 330b is connected to the middle region of the first diaphragm 220, and is electrically connected to the second diaphragm 320. The second connecting post 330 is connected to the second diaphragm 320 through the second end 330b, thereby suspending the second diaphragm 320 on the second back plate 310. The edge area around the second diaphragm 320 after being suspended does not need other fixing structures to support and fix it, so that the sensitivity of the entire second diaphragm 320 can be greatly improved to meet people's use requirements. In this embodiment, a plurality of sound holes 312 are formed on the second back plate 310.

In this embodiment, the second sound sensing unit 300 and the first sound sensing unit 200 are prepared synchronously. That is, the first backplane 210 and the second backplane 310 are prepared in the same process, the first diaphragm 220 and the second diaphragm 320 are prepared in the same process, and the first connecting post 230 and the second connection The pillar 330 is prepared in the same process. It can be understood that each structure obtained in the same process has the same material.

In this embodiment, the second diaphragm 320 in the second sound sensing unit 300 is not provided with a mass, and the other structure is the same as the first diaphragm 220. In other embodiments, the second diaphragm 320 may also be provided with a stress relief unit (not shown) as needed. The stress relief unit may be disposed in an area within half of the distance from the center to the edge of the second diaphragm 320, so that it has a better stress relief effect. After the stress relief unit completes the stress relief on the second diaphragm 320, it can adjust the rigidity of the entire second diaphragm 320, thereby reducing the residual stress that may be caused by the second connecting post 330 embedded in the second diaphragm 320, and avoiding The second diaphragm 320 deforms and warps. In an embodiment, the stress relief unit can also release the sound pressure or air pressure, so as to avoid damage to the second diaphragm 320 under the effect of large sound pressure or air pressure. The stress relief unit may include an elastic structure. Specifically, when stress or external sound pressure or air pressure is applied to the second diaphragm 320, the elastic structure may be deformed, thereby releasing the stress or releasing the sound pressure or air pressure, thereby avoiding deformation of the second diaphragm 320 Warped. Specifically, the stress relief unit is an elastic structure formed by a slit, or an elastic structure formed by pleats.

In an embodiment, the stress relief unit is an elastic structure 322 formed by a gap, as shown in FIG. 8. When external sound pressure or air pressure is applied to the second diaphragm 320, the elastic structure 322 is in an open state, as shown in FIG. 9; when no external sound pressure or air pressure is applied to the second diaphragm 320, the elastic structure 322 is in Closed. Specifically, there are multiple elastic structures 322. The plurality of elastic structures 322 are distributed in an annular interval around the center of the second diaphragm 320, that is, around the second connecting post 330. Each elastic structure 322 is formed by a slit formed in the second diaphragm 320 in the shape of "Ω". In one embodiment, the elastic structure 322 formed by the “Ω”-shaped slit includes a fixed portion 322b and a moving portion 322a. Among them, the head of the moving portion 322a is semicircular. The width of the fixing portion 322b is smaller than the width of the moving portion 322a, so that the elastic structure 322 is easier to be opened by force, which is more conducive to the release of stress and the release of sound pressure. In other embodiments, the moving part 322a may also be a square or other suitable figure.

In another embodiment, the elastic structure is formed by an arc-shaped slit opened on the second diaphragm 320. Each slit has the same bending direction. The curvature of each slit may be the same or different. FIG. 10 is a partial schematic view of the diaphragm in the second embodiment. In the embodiment, an elastic structure formed by arc-shaped slits 322 is formed on the second diaphragm 320. There are a plurality of slits 322, and the arc length of the slits 322 arranged closer to the center of the second diaphragm 320 is shorter. The plurality of slits 322 are distributed on a circumference centered on the center of the second diaphragm 320. The orientations of the slits 322 on two adjacent rings are the same, that is, they are located in the same sector area. In other embodiments, the plurality of slits 322 may also make the arc length of the slits 322 arranged closer to the center of the second diaphragm 320 longer, so that the elastic structure has higher diaphragm sensitivity. In other embodiments, the slits on the two adjacent rings are not in the same orientation, and are located at different positions, thereby adjusting the rigidity of the second diaphragm 320 while achieving stress relief.

FIG. 11 is a partial schematic view of the diaphragm in the fourth embodiment. In this embodiment, the stress relief unit is an elastic structure 324 composed of pleats. The elastic structure 324 extends from the center of the second diaphragm 320 to the edge of the second diaphragm 320 and surrounds the area where the second connecting post 330 is located. The specific structure of the elastic structure 324 is shown in FIG. 12. The elastic structure 324 is a concave-convex structure formed on the second diaphragm 320 and integral with the second diaphragm 320.

In an embodiment, there are a plurality of second connecting posts 330, as shown in FIG. 13. 13 is a schematic diagram of the structure of the diaphragm in the fifth embodiment. In this embodiment, the stress relief unit on the second diaphragm 320 further includes an elastic structure 326 formed by a slit. The elastic structure 326 is located in the central area of the second diaphragm 320. The elastic structure 326 includes a first opening and closing structure 510 and a second opening and closing structure 520 connected to each other and having the same rotating shaft 530. The first opening-closing structure 510 and the second opening-closing structure 520 are regions formed by and forming corresponding slits on the diaphragm. In an embodiment, the area of the first opening-closing structure 510 is larger than the area of the second opening-closing structure 520, that is, the rotating shaft 530 at this time is an asymmetric torsion axis, so that the elastic structure 326 is affected by air pressure or sound pressure It is easy to blow the first opening-closing structure 510 so that the first opening-closing structure 510 rotates around the rotating shaft 530 to release the air pressure, so as to relieve the large sound pressure, so that the sound pressure impact pressure has a faster release path. In another embodiment, the area of the first opening-closing structure 510 is equal to the area of the second opening-closing structure 520, that is, the rotation axis 530 at this time is a symmetric torsion axis.

There is no need to open an opening in the second back plate 310 to release the mass, and the other structure of the second back plate 310 with the sound hole 312 can be the same as the first back plate 210, and are provided with a diaphragm extraction electrode and a back plate electrode to connect the corresponding The electrode is led to the corresponding pad. The structure of the second connecting post 330 and the manner in which the second connecting post 330 is embedded in the second diaphragm 320 can be set by referring to the setting of the first connecting post 230 in the first sound sensing unit 200. Referring to FIG. 1, in this embodiment, the structures of the first connecting post 230 and the second connecting post 330 are the same, and the manner of embedding into the diaphragm is the same.

In one embodiment, a plurality of dimples (stoppers) 314 are formed on a surface of the second back plate 310 close to the second diaphragm 320. The plurality of spacers 314 and the protective layer in the second backplane 310 are an integral structure. Each spacer 314 extends along the second back plate 310 in the direction of the second diaphragm 320 and does not contact the second diaphragm 320. The spacer 314 can prevent the second backing plate 310 and the second diaphragm 320 from being deformed under external pressure and cannot stick to each other (sticking or stiction), thereby further improving the stability and stability of the MEMS sound sensor. reliability.

An embodiment of the present application further provides a MEMS microphone, as shown in FIG. 14. The MEMS microphone includes a printed circuit board 610 and a MEMS sound sensor 620 and an integrated circuit 630 provided on the printed circuit board 610. The integrated circuit 630 may also be called an ASIC chip. Wherein, the MEMS sound sensor 620 uses the MEMS microphone described in any of the foregoing embodiments. This case does not specifically limit the structure of the MEMS microphone. In this embodiment, both the first sound sensing unit and the second sound sensing unit in the MEMS sound sensor 620 are connected to the same integrated circuit 630, and signal processing and output are realized through the same integrated circuit 630, which is beneficial to reduce Reduce the size of the entire product to achieve product miniaturization.

In an embodiment, the MEMS microphone is packaged using a flip chip, that is, both the MEMS sound sensor 620 and the integrated circuit 630 are integrated on the printed circuit board 610 using a flip chip process. Specifically, the MEMS sound sensor 620 and the integrated circuit 630 are directly connected to the pads on the printed circuit board 610 by not bonding wires. For example, in this case, the MEMS sound sensor 620 and the integrated circuit 630 are connected to the printed circuit board 610 through the solder ball 640, so as to realize the electrical connection between the MEMS sound sensor 620 and the integrated circuit 630 and the printed circuit board 610. By adopting this flip-chip process, the noise problem caused by wire bonding can be avoided, so that the entire MEMS microphone has a high signal-noise ratio (SNR). It can be understood that, in order to enhance the stability of the connection between the MEMS sound sensor 620 and the integrated circuit 630 and the printed circuit board 610, other fixing methods may also be added to further fix it, for example, by using encapsulant.

The above-mentioned MEMS microphone also includes a package case 650. The package case 650 and the printed circuit board 610 cooperate with each other to form a receiving space for receiving the MEMS sound sensor 620 and the integrated circuit 630. A perforation 652 for the air flow to pass through is provided in the region of the package case 650 near the MEMS sound sensor 620. In another embodiment, a through hole 612 may also be formed on the printed circuit board 610, as shown in FIG. 15.

When the above MEMS microphone is not in contact with solid materials such as ear bones or vocal cords, both the first sound sensing unit and the second sound sensing unit can detect sound according to changes in air sound pressure, and the integrated circuit 630 detects both The information is processed to obtain the desired result. When the MEMS microphone is in contact with a solid substance that causes sound, such as ear bones or vocal cords, the first sound sensing unit can detect sound by detecting vibration, and the second sound sensing unit can detect sound according to air pressure To achieve sound detection, the integrated circuit 630 can process according to the detection results of the two to obtain a more ideal processing result, thereby improving the sensitivity of the entire MEMS microphone and making it have a higher signal-to-noise ratio. When the MEMS sound sensor is in contact with a solid substance, the side where the printed circuit board 610 is located is close to the ear bone or other solid substance, so that the first diaphragm is very close to the vibration source (Figure 14 to Figure 15, the arrow indicates vibration Source), the entire conduction path is short, which greatly enhances the effectiveness of the sensor signal under the flip-chip structure, so that the MEMS microphone has a high signal-to-noise ratio.

An embodiment of the present application further provides an electronic device, including a device body and a MEMS microphone provided on the device body. The MEMS microphone is prepared by using the MEMS sound sensor described in any of the foregoing embodiments. The electronic device may be a mobile phone, digital camera, notebook computer, personal digital assistant, MP3 player, hearing aid, TV, telephone, conference system, wired headset, wireless headset, voice recorder, recording device, wire controller, etc.

It can be understood that the dimensions of all the drawings in this case do not represent actual proportions, and are merely schematic diagrams, and do not constitute a limitation on this solution.

The technical features of the above-mentioned embodiments can be arbitrarily combined. To simplify the description, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, All should be considered within the scope of this description.

The above-mentioned embodiments only express several implementations of the present application, and their descriptions are more specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that, for those of ordinary skill in the art, without departing from the concept of the present application, a number of modifications and improvements can also be made, which all fall within the protection scope of the present application. Therefore, the protection scope of the patent of this application shall be subject to the appended claims.

Claims

A MEMS sound sensor, including:

Substrate

A first sound sensing unit provided on the substrate; and

A second sound sensing unit provided on the substrate; the second sound sensing unit is electrically isolated from the first sound sensing unit;

The first sound sensing unit is used to detect sound through at least one of air sound pressure change and mechanical vibration; the first sound sensing unit includes

The first backplane is disposed on the substrate through the first insulating layer,

A first diaphragm is disposed opposite to the first backplate and has a gap with the first backplate; the first diaphragm and the first backplate form a capacitor structure, and the substrate is provided with The first back hole to expose the first diaphragm, and

The first connecting post includes a first end and a second end that are oppositely arranged; the first end of the first connecting post is fixedly connected to the first backplane, and the second end of the first connecting post is The middle region of the first diaphragm is electrically connected to suspend the first diaphragm on the first backplane;

At least one mass is provided in an edge area of the first diaphragm; an opening is provided in the first backplane; the opening is used to expose the mass so that the mass and the first backplane There is a gap between them, or the opening serves as a sound hole on the first backplane.
The MEMS acoustic sensor according to claim 1, wherein the mass includes at least one of a first part and a second part; the first part is formed on the first diaphragm toward the first One side of the back plate; the second portion is formed on the side of the first diaphragm facing away from the first back plate.
The MEMS acoustic sensor according to claim 2, wherein the mass includes at least the first portion, and the opening is used to expose the mass and form one of the mass and the first backplane The gap between.
The MEMS sound sensor according to claim 3, wherein a sound hole is further formed on the first backplane.
The MEMS acoustic sensor according to claim 2, wherein the mass includes only the first portion, and the opening serves as a sound hole formed on the first back plate.
The MEMS acoustic sensor according to claim 2, wherein the first backplane includes a conductive layer and a protective layer covering the conductive layer; the first portion and the conductive layer of the first backplane are located The material layer is formed in the same process step.
The MEMS acoustic sensor according to claim 2, wherein the second layer and the material layer where the first diaphragm is located are formed in the same process step; or

The second part includes a first sub-part and a second sub-part; the first sub-part and the material layer where the first diaphragm is located are formed in the same process step; the second sub-part is formed by The substrate is etched.
The MEMS acoustic sensor according to claim 2, wherein the first diaphragm includes a plurality of diaphragms that move independently of each other; each of the diaphragms is provided with at least one mass; the diaphragm The mass of is set to the frequency detection range corresponding to the diaphragm.
The MEMS acoustic sensor according to claim 8, wherein the first diaphragm includes at least a first diaphragm, a second diaphragm, and a third diaphragm; the frequency detection range of the first diaphragm is 100 Hz to 1 KHz; the frequency detection range of the second diaphragm is 1 KHz to 10 KHz; the frequency detection range of the third diaphragm is 10 KHz to 20 KHz.
The MEMS acoustic sensor according to claim 1, wherein at least part of the material of the second end of the first connecting post is embedded in the first diaphragm and electrically connected to the first diaphragm to connect the The first diaphragm is suspended on the first backplane.
The MEMS sound sensor according to any one of claims 1 to 10, wherein the second sound sensing unit includes:

The second backplane is provided on the substrate through the first insulating layer; the second backplane is provided with sound holes;

A second diaphragm, which is opposite to the second backplate and has a gap with the second backplate; the second diaphragm and the second backplate constitute a capacitor structure; and the substrate is provided with The second back hole to expose the second diaphragm; and

A second connecting post, including a first end and a second end that are oppositely arranged; the first end of the second connecting post is fixedly connected to the second backplane; the second end of the second connecting post is at least partially The material is embedded in the second diaphragm and electrically connected to the second diaphragm to suspend the second diaphragm on the second backplane.
The MEMS acoustic sensor according to claim 11, wherein the first backplate and the second backplate are formed in the same process; the first diaphragm and the second diaphragm are in the same It is formed in a process; the first connecting pillar and the second connecting pillar are formed in the same process.
The MEMS acoustic sensor according to claim 11, wherein the first diaphragm is completely separated from the substrate; the second diaphragm is completely separated from the substrate.
The MEMS acoustic sensor according to claim 11, wherein a plurality of spacers are formed on a side of the second backplane facing the second diaphragm; the spacers are oriented along the second backplane The second diaphragm extends without contacting the second diaphragm.
The MEMS acoustic sensor according to claim 11, wherein the first backplane and the second backplane each include a first protective layer and a patterned first conductive layer that are sequentially stacked on the diaphragm Layer and a second protective layer; the second protective layer is disposed on the first protective layer and covers the first conductive layer; the opening and the acoustic hole penetrate the first protective layer and the second protection Floor;

The first conductive layer includes a back plate electrode and a diaphragm lead-out electrode that are separated from each other; both the first connection post and the second connection post include a second conductive layer and a second insulating layer that are spaced apart from each other; The first end of the second conductive layer is formed integrally with the corresponding diaphragm lead-out electrode; the second end of the second conductive layer is embedded in or embedded in and penetrates the corresponding diaphragm.
The MEMS acoustic sensor according to claim 15, wherein the second conductive layer includes at least one conductive layer of a first type conductive layer and a second type conductive layer; Two ends are embedded in the diaphragm; the second end of the second type conductive layer is embedded in and penetrates the corresponding diaphragm.
The MEMS acoustic sensor according to claim 16, wherein at least one of the first diaphragm and the second diaphragm has a protrusion formed on a surface close to the substrate; the second type The second end of the conductive layer extends into the corresponding protrusion.
The MEMS sound sensor according to claim 16, wherein at least one of the first connection post and the second connection post further includes a bearing portion; the bearing portion is at least partially conductive with the second type The second end of the layer is connected.
The MEMS acoustic sensor according to any one of claims 15 to 18, wherein the first end of the second insulating layer is connected to the first protective layer; the second end of the second insulating layer is embedded in correspondence Inside the diaphragm.
The MEMS acoustic sensor according to claim 11, wherein a stress relief unit is provided on the second diaphragm; the stress relief unit is disposed at a half of the distance from the center to the edge of the second diaphragm An area within one of the; the stress relief unit is used to release the stress generated on the second diaphragm, and release the sound pressure or air pressure.
The MEMS sound sensor according to claim 20, wherein the stress relief unit includes an elastic structure; the elastic structure is an elastic structure formed by a slit or an elastic structure with wrinkles;

When the elastic structure is an elastic structure formed by a slit, when an external sound pressure or air pressure is applied to the second diaphragm, the elastic structure is in an open state; when no external sound pressure or air pressure is applied to the When the second diaphragm is on, the elastic structure is in a closed state;

When the elastic structure is an elastic structure with wrinkles, the elastic structure extends in a direction from the center of the second diaphragm to the edge of the second diaphragm and surrounds the second connecting post.
The MEMS acoustic sensor according to claim 21, wherein there are a plurality of second connection posts; a plurality of the second connection posts are symmetrically distributed about the center of the second diaphragm; the slits The formed elastic structure includes a first opening and closing structure and a second opening and closing structure that are connected to each other and have the same rotation axis; the area of the first opening and closing structure is larger than the area of the second opening and closing structure, and the rotation axis is asymmetric A torsion axis; or the area of the first opening and closing structure is equal to the area of the second opening and closing structure, and the rotation axis is a symmetrical torsion axis.
A MEMS microphone, including a printed circuit board, a MEMS sound sensor provided on the printed circuit board, and an integrated circuit provided on the printed circuit board; characterized in that the MEMS microphone adopts claims 1-22 Any of the described MEMS sound sensors.
The MEMS microphone according to claim 23, wherein the first sound sensing unit and the second sound sensing unit in the MEMS sound sensor are both connected to the integrated circuit.
The MEMS microphone according to claim 23, wherein the MEMS sound sensor and the integrated circuit are integrated on the printed circuit board using a flip-chip process.
The MEMS microphone according to claim 23, further comprising a package housing; the package housing and the printed circuit board cooperate with each other to form a housing for accommodating the MEMS sound sensor and the integrated circuit Space; at least one of the package housing and the printed circuit board is provided with a perforation for air flow in an area close to the MEMS sound sensor.
An electronic device includes a device body and a MEMS microphone provided on the device body; characterized in that the MEMS microphone adopts the MEMS microphone according to any one of claims 23 to 26.