阅读说明：本技术 微机电系统麦克风、麦克风单体及电子设备 (Micro-electro-mechanical system microphone, microphone monomer and electronic equipment ) 是由 邹泉波 邱冠勋 王喆 宋青林 于 2021-07-30 设计创作，主要内容包括：这里公开了一种微机电系统麦克风、麦克风单体及电子设备。该微机电系统麦克风包括：衬底；背极板,包括支撑结构；以及位于衬底和背极板之间的振膜,其中,所述支撑结构包括支撑部分和支撑电极,所述支撑部分用于支撑振膜的边缘,所述支撑电极与所支撑的振膜绝缘,以及其中,在未施加偏压的状态下,所述振膜是应力自由膜,以及在施加偏压的状态下,所述支撑电极通过静电作用将所述振膜的边缘钳制在所述支撑部分,以对所述振膜形成固支。(Disclosed herein are a micro electro mechanical system microphone, a microphone unit, and an electronic apparatus. The mems microphone includes: a substrate; a back plate comprising a support structure; and a diaphragm located between the substrate and the back plate, wherein the support structure includes a support portion for supporting an edge of the diaphragm, and a support electrode insulated from the supported diaphragm, and wherein, in a state where no bias voltage is applied, the diaphragm is a stress free film, and in a state where a bias voltage is applied, the support electrode clamps the edge of the diaphragm to the support portion by electrostatic action to form a solid support for the diaphragm.)

1. A microelectromechanical systems microphone, comprising:

a substrate;

a back plate comprising a support structure; and

a diaphragm positioned between the substrate and the backplate,

wherein the support structure comprises a support part for supporting an edge of the diaphragm and a support electrode insulated from the supported diaphragm, an

Wherein, in a state where no bias voltage is applied, the diaphragm is a stress free film, and in a state where a bias voltage is applied, the support electrode clamps an edge of the diaphragm to the support portion by electrostatic action to form a solid support for the diaphragm.

2. The mems microphone of claim 1, wherein the support portion comprises a plurality of support protrusions, and the support protrusions support the diaphragm in a biased state.

3. The mems microphone of claim 2, wherein the support electrodes are located in gaps between the support bumps, and the support bumps protrude relative to the support electrodes.

4. The mems microphone of claim 2, wherein the support protrusion has a gradually decreasing height in a direction from the center to the outside of the diaphragm.

5. The mems microphone of claim 2, wherein the gap gradually decreases in size in a direction from the center of the diaphragm toward the outside.

6. The mems microphone of claim 1, wherein the support electrode is coated with an insulating layer.

7. The mems microphone of claim 1, wherein the backplate comprises a support post located at a middle position of the diaphragm, and a protrusion height of the support post is greater than a protrusion height of the support portion.

8. The mems microphone of claim 7, wherein the support posts have a protrusion height such that a deflection of the diaphragm under an applied bias is equal to or greater than

9. A microphone cell comprising a cell housing, the mems microphone of claim 1, and an integrated circuit chip, wherein the mems microphone and integrated circuit chip are disposed in the cell housing.

10. An electronic device comprising the microphone cell of claim 9.

Technical Field

Embodiments disclosed herein relate to the field of Micro Electro Mechanical System (MEMS) microphone technology, and more particularly, to a MEMS microphone, a microphone unit, and an electronic device.

Background

In a mems microphone, a stress free film may be used as a diaphragm. Stress is an important uncertainty in the manufacturing process of mems microphones. The stress free film may eliminate this uncertainty, thereby improving the yield and/or manufacturing consistency of the mems microphone.

Fig. 1 shows a schematic diagram of a mems microphone with a stress free membrane as the diaphragm. The mems microphone as shown in fig. 1 includes a back plate 1 and a diaphragm 2. A back electrode 3 is provided in the back plate 1. Support protrusions 4 are provided at the edges of the back plate. The support protrusion 4 supports the diaphragm 2. The diaphragm 2 is a stress free film. The diaphragm 2 is supported on the support protrusion 4 in a simple manner. Therefore, stress generated during the manufacturing process is not accumulated in the diaphragm 2.

Fig. 2 shows that under an applied bias the diaphragm 2 bends and the dashed line 5 deviates from the initial position shown. As shown in fig. 2, since the edge of the diaphragm 2 as a stress free film is not fixed to the support boss 4, the size and thickness of the diaphragm 2 are limited. Furthermore, the acoustic properties of the stress free membrane are also limited compared to a diaphragm with fixed edges.

Disclosure of Invention

It is an object of the present disclosure to provide a new solution for a mems microphone.

According to a first aspect of the present disclosure, there is provided a mems microphone comprising: a substrate; a back plate comprising a support structure; and a diaphragm located between the substrate and the back plate, wherein the support structure includes a support portion for supporting an edge of the diaphragm, and a support electrode insulated from the supported diaphragm, and wherein, in a state where no bias voltage is applied, the diaphragm is a stress free film, and in a state where a bias voltage is applied, the support electrode clamps the edge of the diaphragm to the support portion by electrostatic action to form a solid support for the diaphragm.

According to a second aspect of the present disclosure, there is provided a microphone cell comprising a cell housing, a mems microphone according to an embodiment, and an integrated circuit chip, wherein the mems microphone and the integrated circuit chip are disposed in the cell housing.

According to a third aspect of the present disclosure, there is provided an electronic device including the microphone monomer according to the embodiment.

According to the embodiment of the disclosure, the overall performance of the stress-free diaphragm can be improved.

Other features of the present disclosure and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the disclosure and together with the description, serve to explain the principles of the disclosure.

FIG. 1 shows a schematic diagram of a MEMS microphone of the prior art.

FIG. 2 shows a schematic view of the MEMS microphone of FIG. 1 in a state with a bias applied.

Fig. 3 shows a schematic diagram of a diaphragm arranged in a clamped manner.

Fig. 4 shows a schematic view of a diaphragm arranged in a simply supported manner.

FIG. 5 shows a schematic diagram of a MEMS microphone in accordance with one embodiment.

FIG. 6 shows a schematic view of the MEMS microphone of FIG. 7 in a state with a bias applied.

FIG. 7 shows a schematic diagram of a MEMS microphone in accordance with another embodiment.

FIG. 8 shows a schematic view of the MEMS microphone of FIG. 7 in a state with a bias applied.

Fig. 9 is a schematic diagram of a microphone cell according to one embodiment of the present disclosure.

FIG. 10 is a schematic diagram of an electronic device according to one embodiment of the present disclosure.

Detailed Description

Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present disclosure unless specifically stated otherwise.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In the manufacturing process of the mems microphone, the stress generated in the diaphragm often causes inconsistency in the manufacturing of the diaphragm. Therefore, many people propose to use a stress free film as a diaphragm of a mems microphone. Stress free films can provide a number of excellent properties relative to stress films. For example, the stress free film may provide higher yield and higher manufacturing uniformity since the effects of stress may be removed.

However, at present, the application of stress free films is also somewhat limited. For example, the mechanical resonance frequencies fr and t/r of the free film due to stress²Proportionally, the size of the stress free film is limited for a given thickness (which may be determined by process capability), where t is the thickness of the stress free film and r is the radius of the stress free film.

In applications requiring a high signal-to-noise ratio SNR, a larger effective area diaphragm tends to be the most straightforward solution to reduce the acoustic noise of the diaphragm-backplate system, where the noise power is proportional to the inverse of the effective area of the diaphragm.

In this case, one possible way of applying the stress free membrane consists of arranging several diaphragm-backplate units side by side in one chip. This approach can significantly increase the size and cost of the microphone chip while reducing the yield and reliability of the microphone chip.

Here, the inventors propose to combine the advantages of the stress free film and the stress film to form the diaphragm. Specifically, the diaphragm is simply supported in a non-operating state, so that stress is not accumulated in the diaphragm. For example, the diaphragm is stress-free during manufacture and/or in the absence of an applied operating bias. Therefore, the yield, the consistency and the like of the vibrating diaphragm in the production process can be improved, and the stability of the vibrating diaphragm in a non-working state can also be improved to a certain extent. Under the working state of the vibrating diaphragm, the vibrating diaphragm is arranged in a fixed support mode, so that various advantages of the stress vibrating diaphragm are provided.

Fig. 3 shows a schematic diagram of a diaphragm arranged in a clamped manner. Fig. 4 shows a schematic view of a diaphragm arranged in a simply supported manner. Here, the diaphragm 13 is disc-shaped, the diameter of the diaphragm 13 is 2a, its thickness is t, and a uniform pressure p is exerted on the diaphragm 13.

As shown in fig. 3, the edges of the diaphragm 13 are clamped to the support bodies 11, 12 in a clamped manner. In the case shown in fig. 3, the maximum deflection Wc of the diaphragm 13 is pa⁴(ii)/64D, first order natural mechanical resonance frequency fr ═ (10.216/2 π) · (1/a)²)·√(D/ρt)。

As shown in fig. 4, the edges of the diaphragm 13 are clamped to the support bodies 14, 15 in a clamped manner. In the case shown in fig. 4, the maximum deflection Wc of the diaphragm 13 is (5+ v)/(1+ v) · (pa)⁴/64D), first order natural mechanical resonance frequency fr ═ (4.935/2 pi) · (1/a)²)·√(D/ρt)。

Here, D ═ Et³/12(1-v²) E is the Young's modulus of the diaphragm, v is the Poisson's ratio of the diaphragm, and ρ is the disc density of the diaphragm.

By comparing the two diaphragm arrangements in fig. 3 and fig. 4, it can be seen that, for the unstressed diaphragms of the same material and thickness, the resonant frequency of the diaphragm set by the clamped mode is about twice as high as the resonant frequency of the diaphragm set by the simply supported mode under the condition of the same radius. This means that the area of the diaphragm in the clamped mode can be up to twice the area of the diaphragm in the simply supported mode, while defining the same resonance frequency (related to the bandwidth of the mems microphone). This can effectively reduce noise. Furthermore, the mechanical sensitivity of a clamped diaphragm of twice the area is approximately comparable to that of a simply supported diaphragm. This ensures that the sensitivity is substantially unchanged and therefore the signal to noise ratio SNR is improved.

Embodiments herein are described below with reference to fig. 5-8.

FIG. 5 shows a schematic diagram of a MEMS microphone in accordance with one embodiment. FIG. 6 shows a schematic view of the MEMS microphone of FIG. 7 in a state with a bias applied.

As shown in fig. 5 and 6, the mems microphone includes: a substrate 20; back plates 21, 23 comprising support structures 24, 25, 26; and a diaphragm 22 located between the substrate 20 and the backplate 31. The back plate comprises an insulating layer 21 and a back electrode 23. The support structure comprises support portions 24, 25 and a support electrode 26. The support portions 24, 25 serve to support the edges of the diaphragm 22, and the support electrode 26 is insulated from the supported diaphragm 22.

As shown in fig. 5, in the unbiased state, the diaphragm 22 is a stress free film. In the biased state as shown in fig. 6, the support electrode 26 clamps the edge of the diaphragm 22 to the support portions 24, 25 by electrostatic action to form a solid support for the diaphragm.

Thus, the diaphragm 22 is a stress free membrane with no bias applied. In this way, yield of the diaphragm during manufacturing and/or reliability of the diaphragm during manufacturing/use may be improved. In addition, in the using process of the micro-electro-mechanical system microphone, stress cannot be accumulated on the diaphragm.

With the application of a bias voltage, the diaphragm 22 becomes fixed in a braced manner. A diaphragm 22 arranged in this manner may provide higher performance, e.g., improved signal-to-noise ratio, sensitivity, etc.

By clamping the diaphragm in a clamped manner by using static electricity at the edge portion of the diaphragm, the strength of the diaphragm can be increased while maintaining the excellent characteristics of the stress free film. On the premise of ensuring the same vibration film resonant frequency/bandwidth, the vibration film-back plate unit with a larger area can be manufactured. This is beneficial to reducing the noise of the MEMS microphone and improving the SNR. Furthermore, this may reduce the total Harmonic distortion thd (total Harmonic distortion) of the microphone and/or increase the dynamic range of the microphone, i.e. the acoustic Overload point aop (acoustic Overload point).

As shown in fig. 5, the back plate may be divided into two regions. The first region is a region corresponding to the back electrode 23. The second area is the support portion 24, 25, 26. The gap of the second region from the diaphragm 22 is much smaller than the gap of the first region from the diaphragm 22. The pull-in voltage (pull-in voltage) Vp2 of the second region is much smaller than the pull-in voltage VP1 of the first region, i.e., Vp2< < Vp 1. When the first region is operated under the normal bias voltage Vbias1, the bias voltage Vbias2 of the second region is larger than Vp2, thereby ensuring that the diaphragm is stably supported at the supporting part. Here, Vbias2 may be equal to Vbias1 (which share a bias voltage provided by a charge pump), thereby reducing the circuit complexity of the mems microphone.

The micro-electro-mechanical system microphone designed in the way can allow a stress free film with a larger area on the premise of not obviously increasing the useless chip area and the process difficulty and not sacrificing the frequency bandwidth, and is beneficial to reducing noise and improving the signal-to-noise ratio (SNR).

As shown in fig. 5 and 6, the support portion includes a plurality of support projections 24, 25. The support bosses 24, 25 support the diaphragm 22 in a state where a bias voltage is applied. The support electrode 26 is located in the gap between the support protrusions 24, 25. The support projections 24, 25 project relative to the support electrode 26. In this way, it is ensured that the diaphragm 22 does not contact the support electrode 26, thereby preventing the support electrode from short-circuiting with the diaphragm.

As shown in fig. 5, the protruding heights of the support protrusions 24, 25 gradually decrease in the direction of the diaphragm from the center toward the outer side. For example, the support protrusions 25 have a protrusion height smaller than that of the support protrusions 24. Thus, when an operating bias is applied, the supporting protrusion 24 provides a supporting force to the diaphragm 22, which is tilted outward away from the backplate 21, which is beneficial to prevent the diaphragm from adhering to the backplate, thereby improving the performance of the mems microphone.

In one embodiment, the size of the gap between the support protrusions 24, 25 gradually decreases in the direction of the diaphragm from the center to the outside. Thus, a more firm clamped support can be provided for the diaphragm.

In another embodiment, an insulating layer may be coated on the support electrode 26 to avoid accidental shorting of the support electrode 26 to the diaphragm 22.

FIG. 7 shows a schematic diagram of a MEMS microphone in accordance with another embodiment. FIG. 8 shows a schematic view of the MEMS microphone of FIG. 7 in a state with a bias applied. In the embodiment shown in fig. 7 and 8, the mems microphone comprises a substrate 30, back plates 31, 33 and a diaphragm 32. The back plate comprises an insulating layer 31 and a back electrode 33. A support portion is provided at the edge of the backplate. The support portion includes support projections 34, 35 and a support electrode 36. As previously described, the support portion supports the diaphragm 32 when an operating bias is applied.

In the embodiment of fig. 7 and 8, the backplate further comprises support posts 37 located at the middle of the diaphragm 32. The projecting height of the supporting columns 37 is larger than that of the supporting portions. Thus, when an operating bias is applied, the support posts 37 support the diaphragm 32 in the middle, and the support portions 34, 35, 36 clamp the edges of the diaphragm 32, thereby tightening the diaphragm 32. This is beneficial for increasing the diaphragm strength, allowing for larger area diaphragm designs to further improve the signal-to-noise ratio SNR and the acoustic overload point AOP of the microphone. For example, the support columns 37 have a protrusion height such that the deflection of the diaphragm 32 in the biased state is equal to or greater thanThe thickness of the diaphragm.

FIG. 9 illustrates a schematic diagram of a microphone cell in accordance with one embodiment disclosed herein.

As shown in fig. 9, the microphone unit 40 includes a unit housing 41, the mems microphone 42 described above, and an integrated circuit chip 43. A mems microphone 42 and an integrated circuit chip 43 are disposed in the unitary housing 41. The mems microphone 42 corresponds to an air inlet of the single body case 41. The mems microphone 42, the integrated circuit chip 43, and the circuitry in the cell housing 41 are connected by leads 44.

FIG. 10 shows a schematic diagram of an electronic device in accordance with one embodiment disclosed herein.

As shown in fig. 10, the electronic device 50 may include the microphone unit 51 shown in fig. 9. The electronic device 50 may be a cell phone, a tablet, a wearable device, etc.

Although some specific embodiments of the present disclosure have been described in detail by way of example, it should be understood by those skilled in the art that the foregoing examples are for purposes of illustration only and are not intended to limit the scope of the present disclosure.