WO2020133312A1

WO2020133312A1 - Mems sound sensor, mems microphone, and electronic device

Info

Publication number: WO2020133312A1
Application number: PCT/CN2018/125215
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: CN110574396B; CN110574396A

Abstract

A MEMS sound sensor, comprising: a substrate and a first sound sensing unit and a second sound sensing unit arranged on the substrate; the first sound sensing unit is used for detecting sound by means of at least one of air sound pressure change and mechanical vibration, and the first sound sensing unit comprises: a first back plate arranged above the substrate; a first diaphragm arranged opposite the first back plate, a gap being formed between same and the first back plate; the first diaphragm and the first back plate constitute a capacitive structure; and a first connecting column, a second end of the first connecting column being fixedly connected to the first back plate in order to secure and support the first diaphragm on the first back plate; at least one mass block is arranged on the edge area of the first diaphragm, a gap being formed between the mass block and the first back plate.

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. And the sensitivity of the traditional MEMS sound sensor is low, which cannot meet the user's use requirements.

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 first sound sensing unit and the The second 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 The first backplane is disposed above the substrate; the substrate is provided with a first backhole to expose a portion of the first backplane; the first diaphragm is disposed opposite to the first backplane and is There is a gap between the first backplate; the first diaphragm and the first backplate form a capacitive structure; and the first connecting post includes a first end and a second end oppositely arranged; the first The first end of the connecting post is electrically connected to the middle region of the first diaphragm; the second end of the first connecting post is fixedly connected to the first backplane; to fix and support the first diaphragm On the first backplane; wherein, an edge region of the first diaphragm is provided with at least one mass; there is a gap between the mass and 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 6 are cross-sectional views of the first sound sensor unit in the second to sixth embodiments.

7 is a schematic structural view of a first 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

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 the vibration of bones such as ear bones or other solids caused by sound or mechanical external force as an example. 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.

By integrating the first sound sensing unit 200 and the second sound sensing unit 300 on the same substrate 110, the above MEMS sound sensor has a smaller product volume compared to the independently provided structure, which is beneficial to realize the product miniaturization. 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 substrate 110, a first back plate 210, a first diaphragm 220, and a first connecting post 230. Among them, the first back hole 112 is formed on the substrate 110. The first back plate 210 may also be referred to as a back plate. The first back plate 210 is disposed above the substrate 110 and is fixed by the substrate 110. And part of the area of the substrate 110 is exposed by the first back hole 112. The first diaphragm 220 is disposed opposite to the first back plate 210, and the first diaphragm 220 is disposed on the side of the first back plate 210 away from the substrate 110. A gap 20 is formed between the first diaphragm 220 and the first back plate 210. 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 first connecting post 230 includes a first end 230a and a second end 230b disposed oppositely. The first end 230a is connected to the middle region of the first diaphragm 220 and is electrically connected to the first diaphragm 220. The second end 230b is fixedly connected to the first backplane 210. The first connecting post 230 is connected to the first back plate 210 through the second end 230b, so as to fix and support the first diaphragm 220 on the first back plate 210. The first diaphragm 220 is fixedly supported on the first back plate 210 through the first connecting post 230, so that the edge area around the first diaphragm 220 does not need other fixing structures to support and fix it, that is, the first diaphragm The edge region of 220 is completely separated from other structures in the entire MEMS sensor, 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. There is a gap d between the mass 222 and the first back plate 210, so that external airflow can enter the gap 20 between the first diaphragm 220 and the first back plate 210 through the gap.

When the sound pressure changes the air pressure, the air will enter the gap 10 between the first back plate 210 and the first diaphragm 220 through the gap d between the mass 222 and the first back plate 210, so that the first vibration The membrane 220 vibrates under the action of the air pressure or sound pressure, or the change in air pressure below the first diaphragm 220 directly pushes the first diaphragm 220 to cause the first diaphragm 220 to vibrate, which in turn causes the capacitance structure to change in capacitance, which Sound wave detection. 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 air pressure or sound pressure causes the vibration of the first diaphragm 220, since the mass region 222 is provided in the edge area of the first diaphragm 220, even a small change in air pressure can generate a large torque, thereby making the first diaphragm 220 generates relatively obvious vibration, which greatly improves the sensitivity of the first sound sensing unit 200. Among them, the gap d between the mass 222 and the first back plate 210 can be set as needed to minimize the damping effect that exists when air enters and exits the gap 20, and to ensure that there is no gap between the mass 222 and the first back plate 210. It is easy to cause adhesion problems due to static electricity or external forces.

When the first sound sensing unit 200 is in direct or indirect contact with bones that conduct sound (such as ear bones, vocal cords, etc.) (usually the side where the first diaphragm 220 is located close to the ear bones), due to the corresponding bones Mechanical vibration occurs, which causes 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.

In the above first sound sensing unit 200, since air can directly enter the gap d between the mass 222 and the first back plate 210, the vibration of the first diaphragm 220 is caused or the vibration of the first diaphragm 220 is caused by mechanical vibration. Therefore, the first back plate 210 and the first diaphragm 220 may not have sound holes, so that the electrode area in the first back plate 210 is larger, which ensures that the first sound sensor unit 200 has a high capacitance change, which further improves Sensitivity of the detection process. At the same time, by adopting the structure of the first sound sensing unit 200 in this embodiment, the first backplane 210 does not need to be cut to release the mass 222, so that the first backplane 210 has a full-face structure, which in turn makes the entire first A sound sensing unit 200 has a relatively high capacitance change. Furthermore, the first diaphragm 220 covers the effective area of the first back plate 210, which is also a full-face structure with a larger area, so that a mass 222 with a larger mass can be formed, and the entire first sound sensor The unit 200 has a higher capacitance change, so that the entire MEMS sound sensor has a higher sensitivity.

In an embodiment, a sound hole 216 is defined in the first back plate 210, as shown in FIG. By opening the sound hole 216 in the first back plate 210, the airflow can enter the gap 20 through the sound hole 216 to reduce the damping effect. In this embodiment, the sound hole 216 is provided in an area on the first back plate 210 close to the first connecting post 230, and the sound hole 216 is not provided below the area where the mass 222 is located. In an embodiment, the sound hole 216 may also be disposed in an area close to the mass 222, as shown in FIG. 2. It can be understood that the sound hole 216 may also be provided on the entire area of the first back plate 210 exposed to the first back hole 112, as shown in FIG. 3. FIG. 4 is a cross-sectional view of the first sound sensing unit 200 in another embodiment. In this embodiment, the first back plate 210 is not provided with sound holes, and only the first diaphragm 220 is provided with sound holes 226. The acoustic hole 226 is opened in the area between the mass 222 and the first connecting post 230 on the first diaphragm 220. In other embodiments, the first back plate 210 and the first diaphragm 220 may be provided with sound holes at the same time, as shown in FIGS. 5 and 6. At this time, no sound hole needs to be formed on the entire first back plate 210.

In an embodiment, the mass 222 includes a first part. The first part is formed on the side of the first diaphragm 220 facing the first back plate 210. The first part of the first part facing the first diaphragm 220 is also provided with a first anti-adhesion portion 224. There is a gap d between the first anti-adhesion portion 224 and the first back plate 210. In an embodiment, the gap d may be small enough so that the capacitance structure formed by the first back plate 210 and the first diaphragm 220 has a high capacitance change, thereby making the first sound sensing unit 200 have a very high sensitivity . Specifically, the first anti-adhesion portion 224 may be a convex structure, as shown in FIG. 1. The first part, the first anti-adhesion part 224 and the material layer where the first diaphragm 220 is located are formed in the same process step, and the first part and the first anti-adhesion part 224 are formed by an etching process, that is, the first part and the first anti-adhesion part The portion 224 is made of the same material as the first diaphragm 220 and has an integrated structure.

In an embodiment, the mass 222 may further include a second part (not shown in the figure). The second portion is formed on the side of the first diaphragm 220 away from the first back plate 210, that is, is disposed opposite to the first portion. By adding the second part, a mass with greater mass can be obtained to improve the sensitivity. The second part may be formed on the first diaphragm 220 through additional exposure, development, and etching processes after the first diaphragm 220 is formed. The second part and the first diaphragm 220 have the same material, and form an integral structure with the first diaphragm 220. The quality of the mass block 222 can be adjusted, so as to achieve the quality adjustment of the entire mass block 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 an embodiment, the substrate 110 may be a silicon substrate directly. It can be understood that the substrate 110 may also be other substrate structures, such as an SOI substrate. In this embodiment, the first backplane 210 includes a first conductive layer 212 and a protective layer 214. The protective layer 214 includes a first protective layer 214 a and a second protective layer 214 b that are sequentially stacked on the substrate 110. The first protective layer 214a is connected to the substrate 110 through the first insulating layer 120. The first conductive layer 212 is a patterned layer to form a first backplane electrode and an electrode extraction area of the first diaphragm. The first insulating layer 120 may be a dielectric oxide layer, such as silicon dioxide. The first protective layer 214a and the second protective layer 214b cover the first conductive layer 212, as shown in FIG. The first protective layer 214a and the second protective layer 214b are passivation layers. By covering the first conductive layer 212, the corrosive gas in the air of the coated first conductive layer 212 can be ensured, and A bad environment such as a leakage between the first back plate 210 and the first diaphragm 220 under a humid environment. For the protective layer 214, silicon nitride (silicon nitride) or silicon-rich silicon nitride (si-rich silicon nitride) may be used. In an embodiment, the surface of the protective layer 214 must be or processed to be non-hydrophilic, that is, the surfaces of the protective layer 214 are all 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.

In this embodiment, the first conductive layer 212 is a patterned conductive layer. The first conductive layer 212 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 212 and the first diaphragm 220 are both polysilicon (polySi). Specifically, the first conductive layer 212 includes a back plate electrode and a diaphragm extraction region (not shown in the figure) that are separated from each other. The back plate electrode is used as one electrode of the capacitor, and the first diaphragm 220 is used as another electrode of the capacitor. The two form a capacitor structure. The diaphragm lead-out area is connected to the second end 230b of the first connecting post 230 to lead the electrode where the first diaphragm 220 is located. At this time, the first sound sensing unit 200 further includes a second insulating layer 130, a back electrode extraction electrode 242, and a diaphragm extraction electrode 244. The second insulating layer 130 is disposed on the second protective layer 214b. Both the second insulating layer 130 and the first insulating layer 120 may be dielectric oxide layers, for example, prepared by using silicon dioxide. The back plate electrode extraction electrode 242 is formed on the second insulating layer 130, and penetrates the entire second insulating layer 130 and the second protective layer 214b and is connected to the back plate electrode in the first conductive layer 212 to extract the back plate electrode. The diaphragm extraction electrode 244 is also formed on the second insulating layer 130, and penetrates the entire second insulating layer 130 and the second protective layer 214b and is connected to the diaphragm extraction region in the second conductive layer 210. In this embodiment, a backplane pad 246 and a diaphragm pad 248 are further formed on the first sound sensor unit 200, as shown in FIG. The back plate pad 246 is formed on the back plate electrode extraction electrode 242, and the diaphragm pad 248 is formed on the diaphragm extraction electrode 244, respectively to electrically connect the back plate electrode and the first diaphragm 220 to the outside.

In an embodiment, the material layers where the first diaphragm 220, the mass 222, the back electrode extraction electrode 242, the diaphragm extraction electrode 244, and the conductive layer in the first connection post 230 are all formed in the same process step, That is, the materials of the conductive layer in the first diaphragm 220, the mass 222, the back plate electrode extraction electrode 242, the diaphragm extraction electrode 244, and the first connection post 230 are the same. In this embodiment, the conductive layers in the first diaphragm 220, the mass 222, the backplane electrode extraction electrode 242, the diaphragm extraction electrode 244, and the first connection post 230 are all formed through the same polysilicon deposition process step. Specifically, the second insulating layer 130 is formed on the first backplane 210 first, and then the second insulating layer 130 is etched to form a layer corresponding to the backplane electrode extraction electrode 242, the diaphragm extraction electrode 244, and the first connection post 230 After penetrating the area, the entire surface is filled with material to form a complete material layer. Due to the need to fill the previously etched grooves, the thickness of the conductive layer formed at this time is thicker, and the conductive layer formed such as polysilicon material needs to be formed by CMP (Chemical, Mechanical Polishing process) or silicon etching process The layer is etched to the desired thickness of the first diaphragm 220. Next, the material layer is etched to form a first diaphragm 220, a back electrode extraction electrode 242, and a diaphragm extraction electrode 244 which are independent of each other. In an embodiment, the first vibrating film 220 may adopt single crystal silicon, polycrystalline silicon, silicon nitride, silicon-rich silicon nitride, silicon germanium compound, metal, or the like. Among them, the metal may be aluminum, aluminum-copper alloy, platinum and gold. Therefore, any one of the foregoing materials may be used for the material layer. 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 edge area of the first diaphragm 220 is completely isolated from other areas of the entire first sound sensing unit 200, that is, the first diaphragm 220 is completely fixed and supported by the first connecting post 230 without borrowing The other fixing structure fixes the periphery of the first diaphragm 220. The periphery of the 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 first backplane have better conductivity.

In one embodiment, a finite layer 150 is disposed on the first insulating layer 120 on the side close to the first back hole 112. The limiting layer 150 is an etch stop layer, and can be made of the same material as the protective layer 214, for example, silicon nitride. By setting the limit layer 150, it is possible to accurately control the removal position and removal amount of the silicon oxide material in the material layer under the first back plate 210, that is, the first insulating layer 120 (also referred to as a sacrificial layer) to determine the engraving End point of eclipse. By precisely controlling the removal position and amount of the oxide silicon material in the first insulating layer 120 under the first backplane 210, strict control of product performance can be achieved, such as the rigidity of the first backplane 210 Control can further improve product yield. In the traditional first back hole etching process, it is usually necessary to control the etching time to control the etching end point. This process has many variables and influencing factors, which leads to the final product performance can not meet the use requirements. In this case, the etching end point can be directly determined according to the position passing through the limiting layer 150, so that the above-mentioned problem can be effectively solved.

In an embodiment, the first diaphragm 220 includes a plurality of diaphragms 228 that move independently of each other, as shown in FIG. 7. In this embodiment, the first diaphragm 220 includes four symmetrically distributed diaphragms 228, and each diaphragm 228 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 228, the sensitivity during the vibration detection process can be further improved. In an embodiment, at least two of the diaphragms 228 on the first diaphragm 220 have different structures, that is, they are asymmetrically distributed. At this time, masses 222 are provided on different diaphragms 228, and the masses 222 on each diaphragm 228 may be the same or different. It is set to the frequency detection range corresponding to the diaphragm 228, for example, the frequency detection range is 20Hz-20KHz For example, the first diaphragm 220 may be provided with a first diaphragm corresponding to a low frequency, a second diaphragm corresponding to an intermediate frequency, and a third diaphragm corresponding to a high frequency, so that the first diaphragm can be used To achieve low-frequency detection 100Hz ~ 1KHz frequency detection, the second module to achieve 1KHz ~ 10KHz frequency detection, and the third diaphragm to achieve 10KHz ~ 20KHz frequency detection. In other embodiments, different diaphragms 228 correspond to different frequency bands, so that the first sound sensing unit 200 has a wider frequency band detection range, and meets user detection requirements for multiple frequency bands.

In an embodiment, an insulating layer is provided between the diaphragms 228 to achieve electrical insulation between the diaphragms 228, so that the diaphragms 228 can independently detect the sound of the corresponding frequency band. Each diaphragm 228 is led out to the corresponding diaphragm extraction electrode 244 on the first back plate 210 through the first connection post 230 to be connected to the corresponding pad through the diaphragm extraction electrode 244. 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 244 to lead each diaphragm 228 to the corresponding pad, That is, at this time, each diaphragm 228 has independent circuit paths. In other embodiments, each diaphragm 228 may also be led out using the same circuit path. In this case, the diaphragm 228 responsible for sensing the corresponding frequency band forms a capacitance with the first backplane to generate a variable capacitance change signal, so that the ASIC chip processes the change signal accordingly. For the diaphragm 228 in other frequency bands, the capacitance change signal is small, and the ASIC does not process it at this time.

In an embodiment, the first end 230a of the first connecting post 230 and the first diaphragm 220 are integrally formed, so there is no impedance problem, so there is no need to add a corresponding impedance matching structure, and the overall conductive performance it is good. Moreover, the two are integrally formed so that the first diaphragm 220 and the first connecting post 230 have a relatively reliable connection relationship, which is sufficient to resist external mechanical impact.

In one embodiment, part of the material of the second end 230b is embedded in the first conductive layer 212 of the first backplane 210. The second end 230b is electrically connected to the diaphragm lead-out area in the first conductive layer 212 in the first backplane 210, so that the first connecting post 230 can conduct the electrode where the first diaphragm 220 is located through the diaphragm lead-out area Lead out. The at least partial material embedding of the second end 230b means that a part of the layer structure on the first connection pillar 230 is embedded in the first conductive layer 212 or all layer structures on the first connection pillar 230 are embedded in the first conductive layer 212. In this embodiment, the first connection pillar 230 may be embedded inside or penetrate the first conductive layer 212. Therefore, the second end 230b of the first connection pillar 230 may be partially not embedded, but partially embedded in the first conductive layer 212 or embedded and penetrate the first conductive layer 212. The second ends 230b of the first connecting posts 230 may all be embedded, but partially embedded in the first conductive layer 212, and the rest are embedded in and penetrate the first conductive layer 212. It can be understood that the second end 230b of the first connecting post 230 may also be embedded in the first conductive layer 212 or all of the first conductive layer 212 may penetrate through the first conductive layer 212. 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 is fixedly supported on the first back plate 210 by embedding the first back plate 210. Since the first connecting post 230 is embedded in the first backplane 210, the first connecting post 230 has a vertical joint area and a horizontal joint area with the first backplane 210, that is, the first connecting post 230 and the first backplane are increased The joint area between 210 has better mechanical connection strength, which can improve the performance of the first diaphragm 220 against mechanical impact forces such as blow and drop resistance, rolling, and roller testing. In addition, no other fixing structure is needed around the first diaphragm 220 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 the traditional first sound sensor unit 200, the mechanical sensitivity of the first diaphragm is susceptible to the residual stress of the semiconductor process, and individual first sound sensor units 200 are prone to variations, resulting in a decrease in sensitivity consistency and even a first vibration. The uneven distribution of membrane stress causes the possibility of bi-stable deformation, which makes the acoustic performance of the final MEMS microphone unstable in use, 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 back plate 210 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 first diaphragm (diaphragm) and does not resist the external mechanical impact force. In addition, the first diaphragm 220 in this application has no peripheral fixed point or fixed point (diaphragm), that is, the periphery of the first diaphragm is completely cut. This design can release the residual stress caused by the semiconductor process and greatly improve the first The performance consistency and manufacturability of the sound sensing unit 200 relax the manufacturing tolerance tolerance of the manufacturing, and make 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 first connecting post 230 in this embodiment is embedded in the first back plate 210 to fix and support the first diaphragm 220 on the first back plate 210 is not limited to the structure shown in FIG. 1 and can also be applied For example, in the first sound sensing unit 200 having dual first back plates or dual first diaphragms.

In one embodiment, there is one first connecting post 230. Specifically, the first connecting post 230 is located in 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 edge region of 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 conductive layer 212 embedded in the first connection pillar 230 is greater than or equal to one-third of the thickness of the first conductive layer 212, so that the first connection pillar 230 has The vertical bonding area and the horizontal bonding area increase the bonding area between the first connecting post 230 and the first backing plate 210, thereby ensuring the ability of the first backing plate 210 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 third 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 third insulating layer 232 and the second conductive layer 234 projected on the first back plate 210, that is, their top views are all ring structures. The number of layers of the third insulating layer 232 and the second conductive layer 234 can be set according to need. Generally, the third insulating layer 232, the second conductive layer 234, the third insulating layer 232, etc. are arranged in order from the center of the first connecting post 230 Up to the outermost second conductive layer 234. In the embodiment shown in FIG. 1, the second conductive layer 234 and the third insulating layer 232 are both two layers. Among them, the third insulating layer 232 is prepared in the same process as the second insulating layer 130 above the substrate 110 during the preparation. In this embodiment, they are named as the second insulating layer 130 and the Three insulating layer 232. Therefore, the materials of the second insulating layer 130 and the third 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 first diaphragm 220 and is electrically connected. The second end of the second conductive layer 234 is embedded in the first conductive layer 212. The second end of the second conductive layer 234 may be embedded inside the first conductive layer 212, or may be embedded in and penetrate the first conductive layer 212. In this embodiment, the materials of the first diaphragm 220, the second conductive layer 234, and the first conductive layer 212 are the same, for example, all are polysilicon. Therefore, when the second conductive layer 234 is embedded in the first conductive layer 212, it is an embedding of the same material, which 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 conductive layer 212, and its embedding depth is greater than or equal to one third of the thickness of the first conductive layer 212 and less than the thickness of the first conductive layer 212. The second end of the second type conductive layer is embedded in and penetrates the entire first conductive layer 212. 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, the second conductive layers 234 are all second-type conductive layers.

In an embodiment, the third insulating layer 232 can also be embedded inside the first conductive layer 212, thereby further increasing the bonding area of the first connecting post 230 and the first backplane 210, and improving the connection of the first connecting post 230 to the first backplane The mechanical strength of 210. The third insulating layer 232 does not embed and penetrate the first conductive layer 212, that is, the embedded depth of the third insulating layer 232 is greater than one third of the thickness of the first conductive layer 212 and less than the thickness of the first conductive layer 212. When the third insulating layer 232 is embedded and penetrates the first conductive layer 212, when the first insulating layer 120 (for example, silicon dioxide) is released, the material of the third insulating layer 232 will be attacked, causing the penetration of the first insulating layer 232 The material of the third insulating layer 232 of a backplane 210 is etched and does not exist.

In an embodiment, a protrusion 218 is formed on the side of the first back plate 210 away from the first diaphragm 220. The protrusion 218 is formed integrally with the first back plate 210, that is, the two are an integral structure. The second type conductive layer on the first connecting post 230 will extend into the protrusion 218, thereby further increasing the bonding area of the first connecting post 230 and the first back plate 210, and improving the mechanism for connecting the first diaphragm 220 strength. The second type conductive layer extends into the protrusion 218. The protrusion 218 surrounds the portion of the second type conductive layer that extends into this area. In this embodiment, the protrusion 218 has a full-face structure from a bottom view. In other embodiments, when the first connecting post 230 is square, the protrusion 218 may also be a hollow square structure, or a whole surface structure. The thickness of the protrusion 218 may not be limited. In this case, the first insulating layer 120 is first formed on the substrate 110 and then the first conductive layer 212 is formed on the first insulating layer 120. If the protrusion 218 needs to be formed, the first insulating layer 120 needs to be etched before the first conductive layer 212 is formed to form a corresponding groove structure, and then the entire conductive layer structure is formed on the first insulating layer 120 Thus, the first conductive layer 212 having the raised structure is formed. By forming the protrusion 218 directly on the first backplane 210, the rigidity of the first backplane 210 can be improved to a certain extent.

In an embodiment, the first connecting post 230 further includes a bearing portion (not shown). The bearing portion is connected to the side of the first back plate 210 away from the first diaphragm 220. The bearing portion 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 back plate 210 can provide a horizontal force to achieve the fixing of the first diaphragm 220, and the increase of the bearing portion can increase the horizontal contact area with the first back plate 210, can The support force in the vertical direction is 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 pillar 230 is located within the edge of the bearing portion, so there can be a greater tolerance of alignment errors during the preparation process, the process is better, and will not appear It is difficult to align the crack or etch.

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. The substrate 110 is provided with a second back hole 114 to expose the second back plate 310. The second connecting post 330 includes a first end 330a and a second end 330b that are oppositely arranged. The first end 330a and the second diaphragm 320 are integrally formed. The second end 330b is connected to the middle region of the second backplate 310 and electrically connected to the second diaphragm 320. The second connecting post 330 is connected to the second back plate 310 through the second end 330b, so as to fix and support the second diaphragm 320 on the second back plate 310. The edge area around the second diaphragm 320 does not require 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 an embodiment, in order to achieve electrical insulation between the first sound sensing unit 200 and the second sound sensing unit 300, an insulating isolation layer may be provided between the first back plate 210 and the second back plate 310 410, to achieve electrical isolation between the first backplane 210 and the second backplane 310. At the same time, an isolation groove 420 may be provided between the first diaphragm 220 and the second diaphragm 320 to achieve electrical isolation between the first diaphragm 220 and the second diaphragm 320.

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 324 formed by a slit, as shown in FIG. 8. When external sound pressure or air pressure is applied to the second diaphragm 320, the elastic structure 324 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 324 is in Closed. Specifically, there are multiple elastic structures 324. The plurality of elastic structures 324 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 324 is formed by a slit formed in the second diaphragm 320 in an “Ω” shape. In an embodiment, the elastic structure 324 formed by the “Ω”-shaped slit includes a fixed portion 324b and a moving portion 324a. Among them, the head of the moving portion 324a is semicircular. The width of the fixing portion 324b is smaller than the width of the moving portion 324a, so that the elastic structure 324 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 324a 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 324 is formed on the second diaphragm 320. There are a plurality of slits 324, and the arc length of the slits 324 arranged closer to the center of the second diaphragm 320 is shorter. The plurality of slits 324 are distributed on a circumference centered on the center of the second diaphragm 320. The orientations of the slits 324 on the two adjacent rings are the same, that is, they are located in the same sector area. In other embodiments, the plurality of slits 324 may make the arc length of the slits 324 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 326 composed of pleats. The elastic structure 326 extends along the direction 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 326 is shown in FIG. 12. The elastic structure 326 is an uneven structure formed on the second diaphragm 320 and integrated 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 328 formed by a slit. The elastic structure 328 is located in the central area of the second diaphragm 320. The elastic structure 328 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 328 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.

No opening is required in the second back plate 310 to release the mass, but a sound hole 312 is provided. The other structure of the second backplane 310 may be the same as that of the first backplane 210, and both are provided with a diaphragm extraction electrode and a backplane electrode to lead the corresponding electrode 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 an embodiment, a plurality of second anti-adhesive portions (dimple stoppers) 322 are formed on a surface of the second diaphragm 320 close to the second back plate 310. The plurality of second anti-adhesion portions 322 and the second diaphragm 320 have an integrated structure. Each second anti-adhesion portion 322 extends along the second diaphragm 320 in the direction of the second back plate 310 and does not contact the second back plate 310. The second anti-adhesion portion 322 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 MEMS sound sensor Stability and 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.

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 first sound sensing unit is electrically isolated from the second sound sensing unit;

Wherein, the first sound sensing unit is used to detect sound through at least one of air sound pressure change and mechanical vibration, and the first sound sensing unit includes a first back plate, which is disposed above the substrate; The substrate is provided with a first back hole to expose a partial area of the first back plate; a first diaphragm is disposed opposite to the first back plate and has a gap with the first back plate; The first diaphragm and the first backplate form a capacitive structure; and the first connecting post includes first and second ends disposed oppositely; the first end of the first connecting post and the first vibrating The middle region of the membrane is electrically connected; the second end of the first connecting post is fixedly connected to the first backplane; to fix and support the first diaphragm on the first backplane; wherein, At least one mass is provided in the edge region of the first diaphragm; there is a gap between the mass and the first backplate.
The MEMS acoustic sensor according to claim 1, wherein at least one of the first diaphragm and the first back plate is formed with an acoustic hole.
The MEMS acoustic sensor according to claim 1, 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 3, 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 ~1KHz; the frequency detection range of the second diaphragm is 1KHz~10KHz; the frequency detection range of the third diaphragm is 10KHz~20KHz.
The MEMS acoustic sensor according to claim 1, wherein the mass includes a first part; the first part is disposed on a side of the first diaphragm facing the first back plate; the first part There is a gap with the first backplane.
The MEMS acoustic sensor according to claim 5, wherein a first anti-adhesion portion is provided on a surface of the first portion facing the first backplane; the first anti-adhesion portion and the first backplane There is a gap between them.
The MEMS acoustic sensor according to claim 5, wherein the mass further includes a second part; the second part is disposed on a side of the first diaphragm away from the first backplate.
The MEMS sound sensor according to any one of claims 1 to 7, wherein the second sound sensing unit includes:

A second backplane is provided on the substrate, and a second back hole is opened on the substrate to expose a part of the second backplane;

A second diaphragm disposed opposite to the second backplate and having a gap with the second backplate; the second diaphragm and the second backplate constitute a capacitor structure; and

The second connecting post includes a first end and a second end that are oppositely arranged; the first end of the second connecting post is electrically connected to the middle region of the second diaphragm; the second of the second connecting post At least part of the material of the end is embedded in the back plate to fix and support the second diaphragm on the second back plate.
The MEMS acoustic sensor according to claim 8, 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 post and the second connecting post are formed in the same process.
The MEMS sound sensor according to claim 8, wherein the edge region of the first diaphragm is completely separated from other structures in the MEMS sound sensor; the edge region of the second diaphragm is separated from the MEMS The other structures in the sound sensor are completely separated.
The MEMS acoustic sensor according to claim 8, wherein a plurality of second anti-adhesion portions are formed on a surface of the second diaphragm facing the second backplane; the second anti-adhesion portions are along The second diaphragm extends toward the second backplate and does not contact the second backplate.
The MEMS acoustic sensor according to claim 8, wherein the first backplane and the second backplane each include a first protective layer and a patterned first conductive layer stacked in sequence on the substrate And a second protective layer; the first protective layer is connected to the substrate through a first insulating layer; the second protective layer is disposed on the first protective layer and covers the first conductive layer; the first connection At least part of the material at the second end of the pillar is embedded in the first conductive layer of the first backplane; at least part of the material at the second end of the second connection pillar is embedded in the first conductive layer of the second backplane.
The MEMS acoustic sensor according to claim 12, wherein a limiting layer is provided in the first insulating layer, and the limiting layer is used to define a position under the first backplane and the second backplane The removal position and removal amount of the material layer during the etching process.
The MEMS sound sensor according to claim 12, wherein the first conductive layer includes a back plate electrode and the diaphragm extraction area separated from each other; the first sound sensing unit and the second sound Each sensing unit includes a backplane electrode extraction electrode and a diaphragm extraction electrode; the backplane electrode extraction electrode and the diaphragm extraction electrode are disposed on the second protective layer through a second insulating layer; the backplate electrode The lead-out electrode penetrates the second insulating layer and the second protective layer and is connected to the corresponding backplane electrode; the diaphragm lead-out electrode penetrates the second insulating layer and the second protective layer and is connected to the corresponding vibration The membrane lead-out area is connected; the diaphragm lead-out area is electrically connected to the second end of the corresponding connecting post.
The MEMS acoustic sensor according to claim 14, wherein the first diaphragm, the second diaphragm, the mass, the backplate electrode extraction electrode and the diaphragm extraction electrode are located The material layer is formed in the same process step.
The MEMS acoustic sensor according to claim 12, wherein the first connection pillar and the second connection pillar each include a second conductive layer and a third insulating layer spaced apart from each other; the second conductive layer The first end of is formed integrally with the corresponding diaphragm; the second end of the second conductive layer is embedded in the corresponding first conductive layer.
The MEMS acoustic sensor according to claim 16, wherein the second conductive layer includes at least one conductive layer of a first type conductive layer and a second type conductive layer; The two ends are embedded in the corresponding first conductive layer; the second end of the second type conductive layer is embedded in and penetrates the corresponding first conductive layer.
The MEMS acoustic sensor according to claim 17, wherein at least one of the first backplane and the second backplane forms a protrusion on a side close to the substrate; the second type conductive layer The second end extends into the corresponding protrusion.
The MEMS acoustic sensor according to claim 17, 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 16 to 19, wherein the first end of the third insulating layer is connected to the first protective layer; the second end of the third insulating layer is embedded in the In the first conductive layer.
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 acoustic sensor according to claim 21, 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 22, wherein there are a plurality of second connection posts; the plurality of 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 uses claims 1 to 23 Any of the described MEMS sound sensors.
The MEMS microphone according to claim 24, 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 24, 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 24, further comprising an encapsulating housing; the encapsulating 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 24 to 27.