WO2020133352A1

WO2020133352A1 - Mems sound sensor, mems microphone, and electronic device

Info

Publication number: WO2020133352A1
Application number: PCT/CN2018/125351
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: CN110603819B; CN110603819A

Abstract

An MEMS sound sensor, for use in detecting sound by means of at least one of air sound pressure change and mechanical vibration. The MEMS sound sensor comprises: a back plate; a diaphragm opposite to the back plate and having a gap with the back plate, the diaphragm and the back plate constituting a capacitor structure; and a connecting post, comprising a first end and a second end opposite to each other, the first end of the connecting post being fixedly connected to the back plate, and the second end of the connecting post being electrically connected to a middle region of the diaphragm to suspend the diaphragm on the back plate. An edge area of the diaphragm is provided with at least one mass block; the back plate is provided with an opening; the opening is used for exposing the mass block so as to form a gap between the mass block and the back plate, or the opening is used as a sound hole on the 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. The sensitivity of the traditional MEMS sound sensor is low and 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 for detecting sound through at least one of air sound pressure change and mechanical vibration, the MEMS sound sensor includes:

Backplane

A diaphragm, which is disposed opposite to the back plate and has a gap with the back plate; the diaphragm and the back plate form a capacitor structure; and

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

Wherein, at least one mass is provided in the edge area of the diaphragm; an opening is provided on the back plate; the opening is used to expose the mass so that the mass exists between the mass and the back plate The gap, or the opening serves as an acoustic hole on the back plate.

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 is a cross-sectional view of the MEMS sound sensor in the second embodiment.

3 is a cross-sectional view of the MEMS sound sensor in the third embodiment.

4 is a cross-sectional view of the MEMS sound sensor in the fourth embodiment.

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 MEMS sound sensor in the fifth embodiment.

7 is a schematic diagram of the structure of the diaphragm in an embodiment.

FIG. 8 is a schematic structural diagram of a MEMS microphone in an embodiment.

9 is a schematic structural view of a MEMS microphone in another embodiment.

10 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. The MEMS sound sensor can also be called a MEMS sensor or a MEMS chip. The MEMS sound sensor is used to detect sound through at least one of air sound pressure change and mechanical vibration, that is, the MEMS sound sensor can detect sound air pressure change caused by sound, or by Vibration caused by sound or mechanical external force to achieve sound detection. 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 MEMS sound sensor includes a back plate 100, a diaphragm 200, and a connecting post 300. The back plate 100 may also be referred to as a back plate. The diaphragm 200 is disposed opposite to the back plate 100, and a gap 10 is formed between the two. The gap 10 is not filled with other substances and is an air gap. The diaphragm 200 and the back plate 100 constitute a capacitor structure. In this embodiment, the shape of the diaphragm 200 is not particularly limited. For example, the diaphragm 200 may have a circular shape, a square shape, or the like. The connecting post 300 includes a first end 300a and a second end 300b disposed oppositely. The first end 300a is fixedly connected to the backplane 100. The second end 300b is connected to the middle region of the diaphragm 200, and is electrically connected to the diaphragm 200. The connecting post 300 is connected to the diaphragm 200 through the second end 300b, thereby suspending the diaphragm 200 on the back plate. The edge area around the diaphragm 200 after being suspended does not need other fixing structures to support and fix it, so that the sensitivity of the entire diaphragm 200 can be greatly improved to meet people's use requirements. In this embodiment, at least one mass 210 is provided in the edge area of the diaphragm 200. In this case, the edge area is relative to the middle area, that is, the edge area is an area away from the connecting post 300. In this embodiment, an opening 110 is provided in the area of the back plate 100 corresponding to the mass 210 to expose and release the mass 210, and a gap 112 exists between the mass 210 and the back plate 100.

When sound changes the sound pressure of the air, the air will pass through the opening 110 on the back plate 100 and enter the gap 10 between the back plate 100 and the diaphragm 200 through the gap 112, so that the diaphragm 200 is at this air pressure or sound. Vibration occurs under the effect of pressure, or a change in air pressure below the diaphragm 200 directly pushes the diaphragm 200 to cause the diaphragm 200 to vibrate, and the capacitor structure will generate a changed capacitance to detect 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 210 is provided in the edge area of the diaphragm 200, even a small air pressure change can generate a large torque, thereby causing the diaphragm 200 to generate more obvious vibration, greatly Improve the sensitivity of MEMS sound sensor. Moreover, since air can enter directly through the opening 110 and enter the gap 112 between the mass 210 and the back plate 100 to cause vibration of the diaphragm 200, the back plate 100 may not have an acoustic hole, thereby making the back plate 100 The large electrode area ensures that the MEMS sound sensor has a high capacitance change, which further improves the sensitivity of the detection process. Among them, the gap 112 between the mass 210 and the back plate 100 can be set as needed to minimize the damping effect that exists when air enters and exits the gap 10.

When the above MEMS sound sensor directly or indirectly comes into contact with bones that conduct sound (such as ear bones, vocal cords, etc.) (usually the side where the diaphragm 200 is located close to the ear bones), the corresponding bones will mechanically vibrate during speech. The mechanical vibration causes the diaphragm 200 to vibrate. Since the mass region 210 is provided in the edge area of the diaphragm 200, even a small mechanical vibration can cause the vibration of the diaphragm 200 to realize the detection of the sound, that is, the MEMS sound sensor has high sensitivity. The MEMS sound sensor 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), by detecting the solid matter caused by the person when speaking Vibration realizes the detection of sound, and the entire detection process will not be disturbed by environmental noise, so that the entire MEMS sound sensor has a high signal-to-noise ratio.

Referring to FIG. 1, in an embodiment, the above MEMS sound sensor further includes a substrate 410 and a first insulating layer 430. The substrate 410 may be a silicon substrate directly. It can be understood that the substrate 410 may also be other base structures, such as an SOI base. A back hole 412 is formed on the substrate 410 so as to expose the lower surface of the diaphragm 200. The first insulating layer 430 is used to achieve insulation between the backplane 100 and the substrate 410 while fixing the backplane 100 on the substrate 410. The first insulating layer 430 surrounds the diaphragm 200. The first insulating layer 430 may be a dielectric oxide layer, such as silicon dioxide. A material layer 440 formed when the diaphragm 200 is prepared and a dielectric oxide layer 420 for isolating the material layer 440 and the substrate 410 are also formed on the substrate 410. The diaphragm 200 may be made of 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, any one of the foregoing materials may be used for the material layer 440. When the diaphragm 200 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 diaphragm 200. In this embodiment, the diaphragm 200 is completely isolated from the substrate 410, that is, the diaphragm 200 is completely suspended and connected by the connecting post 300, without using other fixing structures to fix the periphery of the diaphragm 200. The periphery of the suspended diaphragm 200 is suspended, which can release residual stress, so that the diaphragm 200 has higher sensitivity. In one embodiment, the diaphragm 200 is doped or ion implanted as necessary. The doping may be N-type doping or P-type doping, so that the diaphragm 200 has better conductivity. In one embodiment, when the conductive layer in the backplane 100 uses polysilicon or silicon-germanium compound, doping or ion implantation is also required to make the backplane have better conductivity.

The mass 210 in the diaphragm 200 includes at least one of the first part 212 and the second part 214. Among them, the first portion 212 is formed on the upper surface of the diaphragm 200 and the second portion 214 is formed on the lower surface of the diaphragm 200. In this case, the side of the diaphragm 200 facing the back plate 100 is the upper surface, and the side away from the back plate 100 is the lower surface. The mass block 210 may be selectively set according to needs, for example, only the first part 212 or the second part 214 may be set, or may be set at the same time. The quality of the first part 212 and the second part 214 can be adjusted, so as to achieve the quality adjustment of the entire mass 210, and thus the adjustment of the sensing frequency band of the entire MEMS vibration sensor. In this embodiment, the frequency detection range of the MEMS sound sensor is 20 Hz to 20 KHz. In FIG. 1, the mass 210 includes both the first part 212 and the second part 214.

In one embodiment, the backplane 100 includes a first conductive layer 130 and a protective layer covering the first conductive layer 130. Specifically, referring to FIG. 1, the backplane 100 includes a first protective layer 120, a first conductive layer 130 and a second protective layer 140 that are sequentially stacked. The first protective layer 120 is located on the side of the back plate 100 close to the diaphragm 200. The first conductive layer 130 is a patterned layer. The second protective layer 140 is formed on the first protective layer 120 and completely covers the first conductive layer 130, that is, the first conductive layer 130 is surrounded by the first protective layer 120 and the second protective layer 140. The opening 110 penetrates the entire first protective layer 120 and the second protective layer 140, so that the external sound signal is transmitted to the gap 10 through the gap 112, and the diaphragm 200 vibrates; or the external voice signal passes through the diaphragm 200 After passing through the gap 10, it then passes through the opening 110. Both the first protective layer 120 and the second protective layer 140 are passivation layers, ensuring that the first conductive layer 130 disposed in the two layers can be isolated from corrosive gases in the air, and can avoid backing in bad environments such as humid environments Leakage between the board 100 and the diaphragm 200. The first protective layer 120 and the second protective layer 140 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 120 and the second protective layer 140 must be or processed to be non-hydrophilic, that is, the surfaces of the first protective layer 120 and the second protective layer 140 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 130 includes a back plate electrode 132 and a lead-out electrode 134 of the diaphragm 200. The first conductive layer 130 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 130 and the diaphragm 200 are both polysilicon (polySi). A backplane pad 510 and a diaphragm pad 520 are also formed on the MEMS sound sensor, as shown in FIG. 1. The back plate pad 510 is formed on the back plate electrode 132, and the diaphragm pad 520 is formed on the extraction electrode 134, so as to realize the electrical connection between the back plate electrode and the diaphragm 200 and the outside, respectively.

In an embodiment, the first portion 212 of the mass 210 and the first conductive layer 130 of the backplane 100 are formed in the same process step, that is, by protecting the first insulating layer 430 and the first protection formed above the diaphragm 200 The layer 120 is etched until the diaphragm 200 is stopped, and then the conductive layer is filled (for example, filled with polysilicon) to form the conductive layer for preparing the first part 212 and the back plate 100 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 212 and the first conductive layer 130 are an integral structure, and an opening 110 needs to be formed in the back plate electrode layer through an etching process to separate the first conductive layer 130 from the first portion 212, and then form the mass 210 and The gap 112 between the back plates 100. The gap 112 can be customized, and the gap 112 is large, which can reduce air damping. In an embodiment, the conductive layer may be generated according to the thickness of the first portion 212 of the mass 210, and then the conductive layer is etched to the thickness of the back plate electrode, and the first portion 212 is separated from the back plate 100. At this time, the height of the first portion 212 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 110 formed on the back plate 100, an acoustic hole 150 may be formed, as shown in FIG. 3, so that the air damping may be further reduced.

In one embodiment, the second portion 214 and the diaphragm 200 are formed in the same process step. Specifically, before forming the diaphragm 200, the dielectric oxide layer 420 in the corresponding region is partially etched, or completely etched or even etched onto the silicon substrate of the substrate 410. The end point of the etching process can be determined according to the quality of the second part 214. After the etching is completed, a material layer for preparing the diaphragm 200 is formed above the substrate 410, and the etching area is filled during the forming process, thereby forming the diaphragm 200 each having the second portion 214.

In another embodiment, the second part 214 includes a first sub-part 214a and a second sub-part 214b, as shown in FIG. The first sub-portion 214a is the same as the method for forming the second portion 214 in the previous embodiment, and is formed in the same process step as the diaphragm 200. The second sub-portion 214b is obtained by etching the substrate 410, see FIG. 5. Specifically, the substrate 410 is etched with a mask plate that defines the shape of the mass 210, and a protrusion 414 having a mass shape is formed on the corresponding position on the substrate 410, and then the entire region of the diaphragm 200 is etched synchronously The etching stops until the dielectric oxide layer 420 is etched, thereby forming the second sub-portion 214b of the mass 210. The second sub-part 214b and the first sub-part 214a and the diaphragm 200 and the first part 212 form an integral body. At this time, the mass 210 has a larger mass and is located in the edge area, thereby making the entire MEMS sound sensor have higher sensitivity .

In an embodiment, the mass 210 formed in the MEMS sound sensor includes only the second part 214. That is, in this embodiment, the upper surface of the diaphragm 200 does not need to form a mass, and there is no need to provide an opening for the exposed mass on the back plate 100. At this time, the opening 110 formed in the back plate 100 serves as the sound hole of the back plate 100 to reduce the damping, as shown in FIG. 6.

In an embodiment, the diaphragm 200 includes a plurality of diaphragms 220 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 diaphragm 200 includes four symmetrically distributed diaphragms 220, and each diaphragm 220 has the same structure, that is, the same mass 210 is formed thereon. By setting the diaphragm 200 as a plurality of independently moving diaphragms 220, the sensitivity in the vibration detection process can be further improved. In an embodiment, at least two of the diaphragms 220 on the diaphragm 200 have different structures, that is, they are asymmetrically distributed. At this time, the masses 210 are set on different diaphragms 220, and the masses 210 on each diaphragm 220 may be the same or different. It is set to the frequency detection range corresponding to the diaphragm 220, for example, the frequency detection range is 20Hz～20KHz. For example, the diaphragm 200 may be provided with a first diaphragm corresponding to low frequency, a second diaphragm corresponding to intermediate frequency, and a third diaphragm corresponding to high frequency, so that the first diaphragm of low frequency may be used to achieve 100 Hz ～1KHz frequency detection, the second module to realize the frequency detection of 1KHz～10KHz, and the third diaphragm realizes the frequency detection of 10KHz～20KHz. In other embodiments, different diaphragms 220 correspond to different frequency bands, so that the MEMS sound sensor 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 220 to achieve electrical insulation between the diaphragms 220, so that the diaphragms 220 can independently detect the sound of the corresponding frequency band. Each diaphragm 220 is led out to the corresponding lead-out electrode 134 on the back plate 100 through the connecting post 300 to be connected to the corresponding pad through the lead-out electrode 134. At this time, the connecting post 300 also includes a plurality of mutually insulated lead-out areas, and a plurality of lead-out electrodes 134 are also provided in the back plate 100 to lead each diaphragm 220 to the corresponding pad, that is, each film at this time The slice 220 has mutually independent circuit paths. In other embodiments, each diaphragm 220 may also be led out using the same circuit path. In this case, the membrane 220 responsible for sensing the corresponding frequency band forms a capacitance with the backplane 100 to generate a variable capacitance change signal, so that the ASIC chip processes the change signal accordingly. For the diaphragm 220 of other frequency bands, the capacitance change signal is small, and the ASIC does not process it at this time.

In one embodiment, part of the material of the second end 300b is embedded in the diaphragm 200. The second end 300b is electrically connected to the diaphragm 200, so that the connecting post 300 can lead out the electrode where the diaphragm 200 is located through the extraction electrode 134. The at least partial material embedding of the second end 300b means that a part of the layer structure on the connecting post 300 is embedded in the diaphragm 200 or all the layer structures on the connecting post 300 are embedded in the diaphragm 200. In this embodiment, the connecting post 300 may be embedded inside the diaphragm 200 or embedded in and penetrate the diaphragm 200. Therefore, the second end 300b of the connecting post 300 may be partially not embedded, but partially embedded in the diaphragm 200 or may be embedded in and penetrate the diaphragm 200. The second ends 300b of the connecting post 300 may all be embedded, but part of them are embedded in the diaphragm 200, and the rest are embedded in and penetrate the diaphragm 200. It can be understood that the second end 300 b of the connecting post 300 may also be completely embedded in the diaphragm 200 or completely embedded in and penetrate the diaphragm 200. In this embodiment, the shape, structure, and number of the connecting posts 300 are not particularly limited. For example, the cross section of the connecting column 300 may be circular, rectangular, elliptical, semicircular, etc., as long as it can play a role of supporting and hanging. In this case, the connection column 300 is cylindrical as an example. The number of connecting posts 300 may be one, or two or more. The number of the connecting posts 300 can also be determined according to the size of the MEMS sound sensor. For example, as the size of the MEMS sound sensor increases, the number of the connecting posts 300 is increased or the cross-sectional area of the connecting posts 300 is adjusted.

In the above MEMS sound sensor, the connecting post 300 suspends the diaphragm 200 on the back plate 100 by embedding the diaphragm 200, so as to achieve relative fixing between the diaphragm 200 and the back plate 100. Since the connecting post 300 is embedded in the diaphragm 200, the connecting post 300 has a vertical bonding area and a horizontal bonding area with the diaphragm 200, that is, the bonding area between the connecting post 300 and the diaphragm 200 is increased, and it has better mechanical properties. The connection strength can improve the performance of the diaphragm 200 against mechanical impact forces such as blowing and falling, rolling, and roller testing. In addition, there is no need for other fixing structures to support and fix the vibrating membrane 200 around the suspension, so that the sensitivity of the entire vibrating membrane 200 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 MEMS sound sensor in this application can have a high mechanical strength and can improve the resistance to various mechanical impact forces. The suspension type is used to strengthen the coupling strength of the connecting post 300 and the diaphragm 200, so that the diaphragm 200 can freely Complying with the external mechanical impact force, the diaphragm 200 becomes a flexible diaphragm and does not resist the external mechanical impact force. In addition, the diaphragm 200 of the present application has no peripheral fixed points or fixed points (diaphragm), which means that the periphery of the diaphragm is completely cut. This design can release the residual stress caused by the semiconductor process and greatly improve the performance of the MEMS sound sensor. Performance and manufacturability, relax manufacturing tolerance tolerance of manufacturing, and make manufacturing yield higher. In other embodiments, some spring-like connection structures may also be provided around the diaphragm 200 to connect with the substrate 410. It can be understood that the structure in which the connecting post 300 in this embodiment is embedded in the diaphragm 200 to suspend the diaphragm 200 to the back plate 100 is not limited to the structure shown in FIG. 1, and can also be applied to other structures such as having a double back plate or double Diaphragm MEMS sound sensor.

In one embodiment, there are one connecting post 300. Specifically, the connecting post 300 is located at the center of the diaphragm 300. Wherein, the diaphragm 200 is circular, and the connecting post 300 is a cylinder, that is, the central axis of the connecting post 300 intersects the center of the circle of the diaphragm 200. By setting the connecting post 300 to be symmetrical about the center of the diaphragm 200, the sound pressure can be generated from the opening 110 or the diaphragm 200 into the gap 10 to generate the most symmetrical pressure acting on the diaphragm 200 to improve the sensitivity of the diaphragm 200 .

In an embodiment, there may be multiple connecting posts 300. The plurality of connecting pillars 300 are symmetrically distributed about the center of the diaphragm 200, so that the force of the diaphragm 200 is uniform everywhere. For example, there may be four connecting posts 300, symmetrically distributed around the center of the diaphragm 200. In an embodiment, a plurality of connecting posts 300 are all disposed within a half of the distance from the center of the diaphragm 200 to the edge, so as to ensure better support performance for the diaphragm 200 and ensure that the diaphragm 200 has Higher sensitivity.

In an embodiment, the depth of the embedded diaphragm 200 in the connecting post 300 is greater than or equal to one-third of the thickness of the diaphragm 200, so that the connecting post 300 has a vertical bonding area and a horizontal bonding area with the diaphragm 200, that is, The joint area between the connecting column 300 and the diaphragm 200 is increased to ensure that the diaphragm 200 and the connecting column 300 are more resistant to external mechanical shocks, and meet the anti-blow and anti-dropping, rolling and roller resistance of the diaphragm 200 Test the performance requirements of mechanical impact forces.

Referring to FIG. 1, in this embodiment, the connection pillar 300 includes a second insulating layer 310 and a second conductive layer 320 that are spaced apart from each other. Since the connecting post 300 is a cylinder, the shapes of the second insulating layer 310 and the second conductive layer 320 projected on the diaphragm 200, that is, their top views are all ring structures. The number of layers of the second insulating layer 310 and the second conductive layer 320 can be set as needed, usually from the center of the connecting post 300 are the second insulating layer 310, the second conductive layer 320, the second insulating layer 310... until the most The second conductive layer 320 of the outer layer. In the embodiment shown in FIG. 1, the second conductive layer 320 and the second insulating layer 310 are both two layers. Among them, the second insulating layer 310 is prepared in the same process as the first insulating layer 430 above the substrate 410 during the preparation. In this embodiment, the first insulating layer 430 and the Second insulating layer 310. Therefore, the materials of the first insulating layer 430 and the second insulating layer 310 are the same, and both are dielectric oxide layers.

The first end of the second conductive layer 320 is integrally formed with the extraction electrode 134 and electrically connected. The second end of the second conductive layer 320 is embedded in the diaphragm 200. The second end of the second conductive layer 320 may be embedded in the diaphragm 200 or may be embedded in and penetrate the diaphragm 200. In this embodiment, the materials of the diaphragm 200, the second conductive layer 320, and the first conductive layer 130 are the same, for example, all are polysilicon. Therefore, when the second conductive layer 320 is embedded in the diaphragm 200, 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 320 may include two types, that is, includes 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 diaphragm 200, and its embedding depth is greater than or equal to one-third of the thickness of the diaphragm 200 and less than the thickness of the diaphragm 200. The second end of the second type conductive layer is embedded in and penetrates the entire diaphragm 200. The second conductive layers 320 in the connection pillar 300 may all be the first type conductive layers or all the second type conductive layers. It can be understood that the second conductive layer 320 in the connection pillar 300 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 320 include the first type conductive layer and the second type conductive layer. In FIG. 6, all the second conductive layers 320 are the second type conductive layers.

In an embodiment, the second insulating layer 310 can also be embedded inside the diaphragm 200, thereby further increasing the bonding area of the connecting post 300 and the diaphragm 200, and improving the mechanical strength of the connecting post 300 connecting the diaphragm 200. The second insulating layer 310 does not embed and penetrate the diaphragm 200, that is, the embedded depth of the second insulating layer 310 is greater than one third of the thickness of the diaphragm 200 and less than the thickness of the diaphragm 200. When the second insulating layer 310 is embedded and penetrates the diaphragm 200, when the dielectric oxide layer 420 (for example, silicon oxide) is released, the material of the second insulating layer 310 will be attacked, causing the penetration of the diaphragm 200 The material of the second insulating layer 310 is etched and does not exist.

In an embodiment, the connecting pillar 300 further includes a third protective layer (not shown) disposed at the outermost periphery. The first end of the third protective layer is formed integrally with the first protective layer 120, and the second end of the third protective layer is connected to or embedded in the diaphragm 200. Adding a third protective layer can increase the bonding area of the diaphragm 200 and the connecting post 300, thereby improving the mechanical strength of the connection. The third protective layer and the first protective layer 120 have the same material, and both can be silicon nitride or silicon-rich silicon nitride. In this embodiment, the first protective layer 120, the second protective layer 140, and the third protective layer are all silicon-rich silicon nitride. Using such a dielectric material to enclose the first conductive layer 130 on the backplane 100 and the second conductive layer 320 in the connection post 300 can prevent charges from remaining outside the connection post 300 and under the backplane 100. If there is residual charge, the MEMS sound sensor cannot have normal charge stored on the two electrode plates. At this time, the MEMS sound sensor cannot work normally, and the sensitivity will decrease, or even exceed the specifications.

In one embodiment, a protrusion 230 is formed on the side of the diaphragm 200 away from the back plate 100. The protrusion 230 is integrally formed with the diaphragm 200, that is, the two are an integral structure. The second type conductive layer on the connecting post 300 extends into the protrusion 230, thereby further increasing the joint area of the connecting post 300 and the diaphragm 200, and improving the mechanical strength of the diaphragm connection. The second type conductive layer extends into the protrusion 230. The protrusion 230 surrounds the portion of the second type conductive layer extending into this area. In Fig. 1, the protrusion 230 is a hollow ring-shaped structure when viewed from the bottom. In other embodiments, when the connecting post 300 is square, the protrusion 230 may also be a hollow square structure, or the entire surface structure is shown in FIG. 6. The thickness of the protrusion 230 may not be limited. Specifically, before forming the diaphragm 200, the formed dielectric oxide layer 420 is partially etched, or completely etched or even etched onto the silicon substrate of the substrate 410. Since the corresponding area on the side of the diaphragm 200 away from the back plate 100 will be etched to form a back hole 412, the thickness of the protrusion 230 will not affect the overall performance. After the etching is completed, a material layer for preparing the diaphragm 200 is formed above the substrate 410, and the etched area is filled during the forming process, thereby forming the diaphragm 200 each having the protrusion 230. By forming the protrusion 230 directly on the diaphragm 200, the rigidity of the diaphragm 200 can be improved to a certain extent.

In an embodiment, the connecting post 300 further includes a bearing 340, as shown in FIG. The bearing portion 340 is connected to the side of the diaphragm 200 away from the back plate 100. The bearing portion 340 is connected to at least a part of the second-type conductive layer in the connecting post 300 to form a rivet structure. The connection column 300 embedded in the diaphragm 200 can provide a horizontal force to achieve the fixing of the diaphragm 200, and the increase of the bearing portion 340 can increase the horizontal contact area with the diaphragm 200, which can increase the vertical The supporting force makes the supporting force in two directions, so that the supporting strength of the connecting column 300 is stronger, and the stability of the diaphragm 200 is better. During the manufacturing process, the edge of the second conductive layer 320 in the connecting post 300 is located within the edge of the carrying portion 340, so there can be a greater tolerance of alignment errors during the manufacturing process, the process is better, and there will be no peeling Cracking or etching is difficult to align.

In an embodiment, the above MEMS sound sensor can be used as an acceleration sensor to detect acceleration. Specifically, the external force acting on the mass 210 can be detected according to the capacitance change of the MEMS sound sensor, so that the current acceleration can be calculated according to the mass of the mass 210. By using the above MEMS sound sensor as an acceleration sensor, the MEMS sound sensor can be multi-functionalized, and has a simpler structure than the conventional comb-shaped acceleration sensor, and the diaphragm 200 and the back plate 100 are the entire surface Structure, with extremely high capacitance.

An embodiment of the present application further provides a MEMS microphone, as shown in FIG. 8. 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 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. In this embodiment, neither the package case 650 nor the printed circuit board 610 is provided with a through hole for air flow to pass through. At this time, the above-mentioned MEMS microphone is used for detecting sound and converting it into an electrical signal output by detecting vibration of bones (such as ear bones) or solid substances caused during speech. At this time, the side where the printed circuit board 610 is located is close to the ear bones or other solid substances, so that the diaphragm 200 is very close to the vibration source (the arrows in FIG. 8 to FIG. 10 indicate the vibration source), the entire conduction path is short, Greatly enhance the effectiveness of the sensor signal under the flip-chip structure, so that the MEMS microphone has a higher signal-to-noise ratio.

In other embodiments, a perforation 652 for the airflow to pass through may also be provided in the area of the package housing 650 near the MEMS sound sensor 620, as shown in FIG. 9. In other embodiments, a through hole 612 may also be directly formed on the printed circuit board 610, as shown in FIG. At this time, the MEMS sound sensor 620 in the MEMS microphone can perform sound detection according to the change in capacitance caused by the change in sound pressure or air pressure, and can also perform sound detection according to the change in capacitance caused by vibration. The integrated circuit 630 may process the detected signal according to a preset algorithm and output it.

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.

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 for detecting sound through at least one of air sound pressure change and mechanical vibration, the MEMS sound sensor includes:

Backplane

A diaphragm, which is disposed opposite to the back plate and has a gap with the back plate; the diaphragm and the back plate form a capacitor structure; and

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

In the edge area of the diaphragm, at least one mass is provided; the back plate is provided with an opening; the opening is used to expose the mass so that there is a gap between the mass and the back plate Or the opening serves as a sound hole on the back plate.
The MEMS acoustic sensor according to claim 1, further comprising a substrate and a first insulating layer; the back plate is disposed above the substrate and is insulated from the substrate by the first insulating layer; the A back hole is provided on the substrate to expose the diaphragm; the diaphragm is completely separated from the substrate.
The MEMS acoustic sensor according to claim 2, wherein the mass includes at least one of a first part and a second part; the first part is formed on a side of the diaphragm facing the back plate ; The second part is formed on a side of the diaphragm facing away from the back plate.
The MEMS acoustic sensor according to claim 3, wherein the mass includes at least the first portion, and the opening is used to expose the mass and form a gap between the mass and the back plate gap.
The MEMS sound sensor according to claim 4, wherein a sound hole is further provided on the back plate.
The MEMS sound sensor according to claim 3, wherein the mass includes only the first portion, and the opening serves as a sound hole opened on the back plate.
The MEMS acoustic sensor according to claim 3, wherein the back plate includes a conductive layer and a protective layer covering the conductive layer; the material layer where the first portion and the conductive layer of the back plate are located is Formed in the same process step.
The MEMS acoustic sensor according to claim 3, wherein the second layer and the material layer where the 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 diaphragm is located are formed in the same process step; the second sub-part is performed by Etched.
The MEMS acoustic sensor according to claim 2, wherein the diaphragm includes a plurality of diaphragms that move independently of each other; each diaphragm is provided with at least one mass; the mass on the diaphragm The block is set to the frequency detection range corresponding to the diaphragm.
The MEMS sound sensor according to claim 9, wherein the 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 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 9, wherein each diaphragm in the diaphragm has a different frequency detection range.
The MEMS acoustic sensor according to claim 1, wherein at least part of the material of the second end of the connecting post is embedded in the diaphragm and electrically connected to the diaphragm to suspend the diaphragm The backplane.
The MEMS acoustic sensor according to claim 1, wherein the backplane includes a first protective layer, a patterned first conductive layer, and a second protective layer that are sequentially stacked on the diaphragm; the second protection A layer is provided on the first protective layer and covers the first conductive layer; the opening penetrates the first protective layer and the second protective layer;

The first conductive layer includes a back plate electrode and a lead-out electrode of the diaphragm separated from each other; the connecting post includes a second conductive layer and a second insulating layer spaced apart from each other; the first of the second conductive layer The end is integrally formed with the lead-out electrode; the second end of the second conductive layer is embedded in or penetrates through the diaphragm.
The MEMS acoustic sensor according to claim 13, 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 diaphragm.
The MEMS acoustic sensor according to claim 14, wherein an integrated protrusion is formed on a side of the diaphragm away from the back plate; the second end of the second type conductive layer extends to the Raised inside.
The MEMS acoustic sensor according to claim 14, wherein the connecting post further includes a bearing portion; the bearing portion is connected to at least a portion of the second end of the second-type conductive layer.
The MEMS acoustic sensor according to any one of claims 13 to 16, 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 the Said inside the diaphragm.
The MEMS acoustic sensor according to any one of claims 13 to 16, wherein the connecting post further includes a third protective layer disposed at the outermost periphery; the first end of the third protective layer and the first The protective layer is formed integrally; the second end of the third protective layer is connected to or embedded in the diaphragm.
The MEMS acoustic sensor according to any one of claims 1 to 18, wherein the MEMS acoustic sensor serves as an acceleration sensor.
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 1-19 Any of the described MEMS sound sensors.
The MEMS microphone according to claim 20, 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 20, 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;

Neither the package housing nor the printed circuit board has a perforation through which air flow passes, or at least one of the package housing and the printed circuit board is opened in an area close to the MEMS sound sensor There are perforations for the air to pass through.
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 20-22.