CN215453268U - MEMS microphone - Google Patents

Abstract

The utility model provides an MEMS microphone, which comprises a substrate, a vibrating diaphragm, an insulating isolation layer, a back electrode, a back plate material layer and a plurality of sound holes, wherein the vibrating diaphragm is arranged on the substrate; a cavity penetrating through the substrate is formed in the substrate; the vibrating diaphragm is fixed on the substrate through a bracket, and a folding structure and an air leakage hole penetrating through the vibrating diaphragm are formed in the vibrating diaphragm; the insulating isolation layer extends to the upper part of the vibrating diaphragm from the surface of the substrate and is spaced from the vibrating diaphragm, and a plurality of back electrode blocking blocks are formed on the lower surface of the insulating isolation layer; the back electrode is positioned on the upper surface of the insulating isolation layer; the back plate material layer is positioned above the back electrode and extends outwards to the surface of the insulating isolation layer; the sound holes penetrate through the back plate material layer, the back electrode and the insulating isolation layer, and correspond to the cavities up and down. The utility model can effectively avoid the adsorption and bonding of the conductive particles falling between the vibrating diaphragm and the back electrode, can effectively avoid the short circuit failure of the device, and is beneficial to improving the performance and yield of the MEMS microphone.

Description

MEMS microphone

Technical Field

The utility model relates to the field of micro-electro-mechanical devices, in particular to an MEMS microphone.

Background

Microphones are energy conversion devices that convert sound signals into electrical signals, and can be generally classified into electret microphones (ECM microphones) and MEMS microphones. Currently, the MEMS microphone is replacing the conventional ECM microphone by virtue of advantages of small volume, high sensitivity, and the like, and is widely applied to terminal products such as mobile phones, notebook computers, smart speakers, earphones, and the like.

The MEMS microphone is a microphone made by using a Micro Electro Mechanical System (MEMS), and the MEMS converts vibration caused by external sound into an electrical signal, and outputs the electrical signal through a back-end circuit. MEMS components build a movable diaphragm and a fixed back-pole structure on a semiconductor wafer such that it forms a capacitor. The sound pressure wave can cause the movement of the diaphragm, so that the relative distance is changed, and capacitance change is brought, an ASIC chip contained in the sound pressure wave is used as an audio amplifier, the capacitance change of the MEMS is converted into an electric signal, and finally the chip is protected through packaging and the signal is led out.

If conductive particles fall on the cavity between the vibrating diaphragm and the back electrode, the vibrating diaphragm and the back electrode are likely to be attached in an adsorption manner, and then the short circuit failure of the device is caused. In order to reduce the failure possibility, the utility model provides an improvement scheme through long-term research.

SUMMERY OF THE UTILITY MODEL

In view of the above disadvantages of the prior art, an object of the present invention is to provide a MEMS microphone, which is used to solve the problems that if conductive particles fall on a cavity between a diaphragm and a back electrode, the diaphragm and the back electrode are easily attached to each other, and thus a device is short-circuited and fails.

To achieve the above and other related objects, the present invention provides a MEMS microphone, which is fabricated by a method comprising:

providing a substrate, and growing a first sacrificial layer on the substrate;

forming a groove corresponding to the diaphragm in the first sacrificial layer, wherein the diaphragm comprises a folding structure and a bracket positioned on the outer side of the folding structure;

forming a vibrating diaphragm material layer on the first sacrificial layer, wherein the vibrating diaphragm material layer fills the groove to form a vibrating diaphragm;

forming a gas release hole in the vibrating diaphragm material layer, wherein the first sacrificial layer is exposed out of the gas release hole;

forming a second sacrificial layer, wherein the second sacrificial layer covers the vibrating diaphragm and the air release hole;

forming a groove corresponding to the back pole blocking block in the second sacrificial layer;

forming an insulating isolation layer on the surface of the second sacrificial layer, wherein the insulating isolation layer covers the second sacrificial layer and extends to the surface of the substrate;

forming a back electrode material layer, wherein the back electrode material layer covers the insulating isolation layer;

etching the back pole material layer to form a plurality of sound holes in the back pole material layer, wherein the insulation isolation layer is exposed out of the sound holes;

forming a back plate material layer, wherein the back plate material layer covers the back electrode material layer, the sound holes and the insulating isolation layer;

etching the back plate material layer and the insulating isolation layer corresponding to the sound holes until the second sacrificial layer is exposed in the sound holes;

forming a cavity penetrating through the substrate in the substrate, wherein the cavity corresponds to the sound hole up and down;

and etching the first sacrificial layer and the second sacrificial layer to release the folding structure, the bracket and the air release hole.

Optionally, before forming the cavity penetrating through the substrate in the substrate, the method further includes a step of thinning the substrate, and then forming the cavity in the thinned substrate.

Optionally, the first sacrificial layer and the second sacrificial layer are made of silicon oxide, and the thickness of the second sacrificial layer is greater than that of the first sacrificial layer.

Optionally, the material of diaphragm includes polycrystalline silicon, the hole of disappointing is a plurality of, and a plurality of holes of disappointing are located between beta structure and the support.

Optionally, the method further includes forming a cutting street on the periphery of the diaphragm while forming the air-release hole in the diaphragm, where the cutting street exposes the first sacrificial layer, and then forming the cutting street on the periphery of the diaphragm while forming the groove corresponding to the back pole blocking block in the second sacrificial layer and exposing the substrate.

Optionally, the insulating isolation layer and the backplane material layer are both made of silicon nitride.

Optionally, the thickness of the insulating isolation layer is smaller than the thickness of the backplane material layer.

More optionally, the thickness of the insulating isolation layer is 200nm to 500 nm.

The MEMS microphone provided by the utility model comprises:

a substrate having a cavity formed therein that extends through the substrate;

the vibrating diaphragm is fixed on the substrate through a support, and a folding structure and an air leakage hole penetrating through the vibrating diaphragm are formed in the vibrating diaphragm;

the insulating isolation layer extends to the upper part of the vibrating diaphragm from the surface of the substrate and is spaced from the vibrating diaphragm, and a plurality of back electrode blocking blocks are formed on the lower surface of the insulating isolation layer;

the back electrode is positioned on the upper surface of the insulating isolation layer;

the back plate material layer is positioned above the back pole and extends outwards to the surface of the insulating isolation layer;

the sound holes penetrate through the back plate material layer, the back electrode and the insulating isolation layer, and correspond to the cavities up and down.

Optionally, the shape of the insulating isolation layer includes any one of a circle and a polygon.

As described above, the MEMS microphone of the present invention has the following advantageous effects: according to the utility model, through the optimized design, the insulating isolation layer is formed on the lower surface of the back electrode and is spaced from the vibrating diaphragm, so that even if conductive impurity particles exist in the gap between the vibrating diaphragm and the insulating isolation layer, the vibrating diaphragm and the back electrode cannot be adsorbed and attached together due to the isolation spacing of the insulating isolation layer, the short circuit failure of a device can be effectively avoided, and the performance and yield of the MEMS microphone can be improved.

Drawings

Fig. 1 is a schematic diagram showing an exemplary cross-sectional structure of a MEMS microphone in the prior art.

Fig. 2 to 18 are schematic cross-sectional views of MEMS microphones of the present invention in various steps of manufacturing.

Description of the element reference numerals

11-a substrate; 12-a first sacrificial layer; 13-a groove; 13 a-a first groove; 13 b-a second groove; 14-a diaphragm; 141-a folded structure; 142-a scaffold; 143-a layer of diaphragm material; 15-air escape holes; 16-a second sacrificial layer; 17-back pole barrier; 18-an insulating isolation layer; 19-a layer of back electrode material; 20-a sound hole; 21-a layer of backplane material; 22-a back plate; 23-a cavity; 24-cutting a channel; 25-a back pole; 31-a diaphragm; 32-a back pole; 33-a back plate; 34-stop block.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The utility model is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. As in the detailed description of the embodiments of the present invention, the cross-sectional views illustrating the device structures are not partially enlarged in general scale for convenience of illustration, and the schematic views are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.

For convenience in description, spatial relational terms such as "below," "beneath," "below," "under," "over," "upper," and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these terms of spatial relationship are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Further, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

In the context of this application, a structure described as having a first feature "on" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed in between the first and second features, such that the first and second features may not be in direct contact.

It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated. In order to keep the drawings as concise as possible, not all features of a single figure may be labeled in their entirety.

Fig. 1 illustrates a partial cross-sectional structural diagram of a MEMS microphone commonly known in the prior art. The MEMS microphone comprises a vibrating diaphragm 31 and a back electrode 32 which is positioned above the vibrating diaphragm 31 and is separated from the vibrating diaphragm 31 by a cavity, a back plate 33 is arranged above the back electrode 32, a blocking block 34 is formed on the lower surface of the back plate 33, and the blocking block 34 penetrates through the back electrode 32 downwards. I.e. in the solution shown in fig. 1, there is no separation of other material layers (other than air) between the back electrode 32 and the diaphragm 31. Because the diaphragm 31 and the back electrode 32 are both made of conductive materials, and the gap between the diaphragm 31 and the back electrode 32 is small, if conductive impurities fall in the cavity between the diaphragm 31 and the back electrode 32, the impurities are likely to adhere to the surface of the diaphragm 31 and/or the back electrode 32 due to electrostatic adsorption, and further the diaphragm 31 and the back electrode 32 adhere to each other, which may cause the performance of the device to be reduced, and in severe cases, even cause the short circuit failure of the device. In order to reduce the failure possibility, the utility model provides an improvement scheme through long-term research.

Specifically, the utility model provides a MEMS microphone, and a preparation method thereof comprises the following steps:

providing a substrate 11, and growing a first sacrificial layer 12 on the substrate 11, wherein the structure obtained in the step is shown in fig. 2; the material of the substrate 11 includes, but is not limited to, one or more combinations of silicon, germanium, silicon on insulator, silicon carbide, sapphire, etc., the material of the first sacrificial layer 12 includes, but is not limited to, one or more combinations of insulating materials such as silicon oxide, silicon oxynitride, etc., the method for forming the first sacrificial layer 12 may depend on the materials of the substrate 11 and the first sacrificial layer 12, including, but not limited to, any one of vapor deposition, thermal oxidation, coating, etc., for example, when the substrate 11 is a silicon wafer, a silicon oxide layer may be grown on the silicon wafer as the first sacrificial layer 12 by thermal oxidation, and the thickness of the first sacrificial layer 12 is preferably 1-2 μm;

forming a groove 13 corresponding to the diaphragm 14 in the first sacrificial layer 12, wherein the diaphragm 14 includes a folded structure 141 and a support 142 located outside the folded structure 141, and the structure obtained by this step can be referred to fig. 3 and 4; the method for forming the groove includes, but is not limited to, an etching method, the groove may include a first groove 13a corresponding to the support 142 and a second groove 13b corresponding to the folding structure 141, the second groove 13b penetrates through the first sacrificial layer 12 until the substrate 11 is exposed, and the first groove 13a does not penetrate through the first sacrificial layer 12, that is, the first groove 13a and the second groove 13b have different depths, so that the first groove 13a and the second groove 13b may be successively formed by step etching, and the first groove 13a and the second groove 13b are plural;

forming a diaphragm material layer 143 on the first sacrificial layer 12, wherein the diaphragm material layer 143 fills the groove to form the diaphragm 14, and since the first groove 13a and the second groove 13b with different depths are formed in the previous step, the folded structure 141 with the concave-convex surface and the support 142 are formed through conformal filling in the previous step, and the structure obtained in the previous step is as shown in fig. 5; in this step, the diaphragm material layer 143 is preferably a multi-choice polysilicon layer, and the method for forming the diaphragm material layer 143 is preferably a vapor deposition method; the material of the diaphragm 14 fills the first groove 13a to form the bracket 142 of the diaphragm 14, so as to mount the diaphragm 14 on the substrate 11, and the sacrificial layer material inside the bracket 142 is wrapped by the bracket 142, so that the sacrificial layer material cannot be etched in the subsequent etching process to play a role in supporting the diaphragm 14; the material of the diaphragm 14 fills the second groove 13b to form a folded structure 141 of the diaphragm 14, and the upper and lower surfaces of the folded structure 141 are in concave-convex interval distribution, which is helpful to improve the stress distribution of the diaphragm and improve the stability and the sensitivity of the device;

forming a gas release hole 15 in the diaphragm material layer 143, wherein the first sacrificial layer 12 is exposed from the gas release hole 15; the method for forming the air-release hole 15 includes, but is not limited to, photolithography, the air-release hole 15 is preferably located at the outer side of the folded structure 141 (i.e. the direction away from the center of the structure layer), and in this step, it is preferable to form a cutting channel 24 at the periphery of the diaphragm 14 at the same time as the air-release hole 15 is formed, and the cutting channel 24 exposes the first sacrificial layer 12, and this step results in the structure shown in fig. 6; the air release hole 15 is preferably located in the middle of the folding structure 141 and the bracket 142, and is preferably located above the substrate 11 correspondingly;

forming a second sacrificial layer 16, wherein the second sacrificial layer 16 covers the diaphragm 14 and the air release hole 15; in the case where the scribe line 24 is formed, the second sacrificial layer 16 will also cover the scribe line 24, and the resulting structure is shown in fig. 7; the material of the second sacrificial layer 16 is preferably the same as that of the first sacrificial layer 12, for example, silicon oxide, and the method for forming the second sacrificial layer 16 is preferably vapor deposition; the thickness of the second sacrificial layer 16 determines the separation of the diaphragm 14 and the subsequently formed back electrode 25, and therefore the thickness of the second sacrificial layer 16 is preferably greater than the thickness of the first sacrificial layer 12, such as 2-4 microns (inclusive, unless otherwise specified herein, where a range of values is intended, inclusive);

forming a plurality of grooves corresponding to the back electrode barrier 17 in the second sacrificial layer 16 by using an etching method, for example, 2 or more than 2 grooves, the grooves having a distance from the diaphragm 14, and the structure obtained by this step is shown in fig. 8; this step may be followed by forming the cutting channel 24 exposing the substrate 11 on the periphery of the diaphragm 14 by using, but not limited to, an etching method, so as to obtain the structure shown in fig. 9;

forming an insulating isolation layer 18 on the surface of the second sacrificial layer 16 by using a vapor deposition method including but not limited to, the insulating isolation layer 18 covering the second sacrificial layer 16 (the insulating isolation layer 18 fills the groove corresponding to the back electrode barrier 17 to form the back electrode barrier 17 on the lower surface of the insulating isolation layer 18, and the back electrode barrier 17 can prevent the adhesion of the back electrode 25 and the diaphragm 14) and extending to the surface of the substrate 11, and the structure obtained by this step is shown in fig. 10; the insulating isolation layer 18, as the name implies, is a structural layer formed of an insulating material, which functions to isolate the diaphragm 14 from the subsequently formed back electrode 25; the insulating isolation layer 18 includes, but is not limited to, a silicon nitride layer;

forming a back electrode material layer 19 by using a vapor deposition method including but not limited to, the back electrode material layer 19 covering the insulating isolation layer 18, and the structure obtained by the step is shown in fig. 11; the material of the back electrode material layer 19 is preferably polysilicon;

etching the back electrode material layer 19 to form a plurality of sound holes 20 in the back electrode material layer 19 to obtain a back electrode 25, or forming a plurality of sound holes 20 penetrating through the back electrode 25 in the back electrode 25, exposing the insulating isolation layer 18 from the plurality of sound holes 20, where the structure obtained in this step is shown in fig. 12;

forming a back plate material layer 21 by using a vapor deposition method including but not limited to, the back plate material layer 21 covering the back electrode material layer 19, the sound holes 20 and the insulating isolation layer 18, and obtaining a structure as shown in fig. 13; the layer of backplane material 21 includes, but is not limited to, a layer of silicon nitride;

etching the back plate material layer 21 and the insulating isolation layer 18 corresponding to the sound holes 20 until the second sacrificial layer 16 is exposed in the sound holes 20, and the structure obtained by the step is shown in fig. 14; in one example, to simplify the step as much as possible, the material of the backplane material layer 21 and the insulating isolation layer 18 are preferably the same, so that the sound holes 20 can be released only by one-step etching, and cylindrical holes with similar upper and lower openings can be obtained after one-step etching; meanwhile, the same material of the back plate material layer 21 and the insulating isolation layer 18 is also beneficial to reducing the stress distribution between the two structural layers, so that the back plate material layer 21 can be better grown on the surface of the insulating isolation layer 18; the sound holes 20 are generally plural, such as 3 and more, and the plural sound holes 20 are uniformly spaced above the corresponding cavities 23, and an exemplary top view structure thereof is shown in fig. 15; of course, in other examples, the back plate material layer 21 and the insulating isolation layer 18 may be etched in sequence to form the acoustic holes 20, and the back plate material layer 21 and the insulating isolation layer 18 may also be prepared from different materials (for example, the back plate material layer 21 is a silicon oxynitride layer, the insulating isolation layer 18 is a silicon nitride layer, or the back plate material layer 21 is a silicon nitride layer, and the insulating isolation layer 18 is a silicon oxynitride layer);

forming a cavity 23 penetrating through the substrate 11 in the substrate 11 by using a dry etching method, wherein the cavity 23 corresponds to the sound hole 20 up and down; before the cavity 23 is formed, the substrate 11 may be thinned, the obtained structure is shown in fig. 16, and the structure after etching to obtain the cavity 23 is shown in fig. 17;

the first sacrificial layer 12 and the second sacrificial layer 16 are removed by wet etching, but not limited to, to release the folded structure 141, the support 142 and the air release hole 15, and the structure of the resulting MEMS microphone is shown in fig. 18.

The material and thickness of the insulating isolation layer have a significant impact on device performance and must therefore be carefully designed. If thickness undersize then be difficult to play better isolation, nevertheless if thickness is too big, then can lead to and the vibrating diaphragm between the clearance undersize, lead to the device performance inefficacy equally easily, the utility model discloses the people discovers after a large amount of experiments, the insulating isolation layer is the silicon nitride layer better, and the silicon nitride layer has better mechanical strength than insulating materials such as silicon oxide, the thickness of insulating isolation layer is preferably 200nm ~ 500nm, the thickness of insulating isolation layer is preferably less than the thickness of backplate material layer.

According to the utility model, through the optimized design, the insulating isolation layer is formed on the lower surface of the back electrode and is spaced from the vibrating diaphragm, so that even if conductive impurity particles exist in the gap between the vibrating diaphragm and the insulating isolation layer, the vibrating diaphragm and the back electrode cannot be adsorbed and attached together due to the isolation spacing of the insulating isolation layer, the short circuit failure of a device can be effectively avoided, and the yield of the MEMS microphone can be improved.

Fig. 18 shows a MEMS microphone according to the present invention, which can be prepared by any of the methods described above, and the description of the MEMS microphone can be incorporated herein in its entirety. Specifically, the MEMS microphone includes:

a substrate 11, where a cavity 23 (which may be defined as a first cavity) is formed in the substrate 11, and the substrate 11 includes, but is not limited to, any one or more of a silicon substrate, a germanium-silicon substrate, a silicon carbide substrate, and the like;

a diaphragm 14, wherein the diaphragm 14 is fixed on the substrate 11 through a support 142, a plurality of folding structures 141 and air release holes 15 penetrating through the diaphragm 14 are formed in the diaphragm 14, and preferably, the air release holes 15 are located between the folding structures 141 and the support 142, and a sacrificial layer material such as silicon oxide is provided on the inner side of the support 142;

the insulating isolation layer 18 extends from the surface of the substrate 11 to the upper side of the vibrating diaphragm 14, and is spaced from the vibrating diaphragm 14, and includes a vertical spacing and a horizontal spacing (the spacing may be referred to as a second cavity for being distinguished from a cavity in the substrate, and the first cavity is communicated with the second cavity through an air leakage hole), a plurality of back pole blocking blocks 17 are formed on the lower surface of the insulating isolation layer 18, and the back pole blocking blocks 17 protrude out of the lower surface of the insulating isolation layer; the insulating isolation layer 18 is preferably made of a silicon nitride layer, and the thickness is preferably 200 nm-500 nm; the shape of the insulating isolation layer 18 includes any one of a circle and a polygon (such as a regular hexagon, a regular octagon, etc.);

a back electrode 25 disposed on the upper surface of the insulating isolation layer 18, wherein the material of the back electrode 25 includes but is not limited to polysilicon;

a back plate material layer 21 located above the back electrode 25 and extending outward to the surface of the insulating isolation layer 18;

the sound holes 20 penetrate through the back plate material layer 21, the back electrode 25 and the insulating isolation layer 18 until the sound holes are communicated with the second cavity, the sound holes 20 vertically correspond to the cavity 23, and the sound holes can be uniformly distributed above the corresponding cavity at intervals.

As an example, the MEMS microphone further includes a cut-off channel 24, which is located at the periphery of the diaphragm 14 and exposes the substrate 11.

For a more detailed description of the MEMS microphone, please refer to the description of the foregoing preparation method, and for the sake of brevity, the description is omitted.

The MEMS microphone provided by the utility model can effectively avoid the attachment of the back electrode and the vibrating diaphragm caused by the conductive particles and avoid the short circuit failure of devices.

In summary, the present invention provides a MEMS microphone, including: a substrate having a cavity formed therein that extends through the substrate; the vibrating diaphragm is fixed on the substrate through a support, and a folding structure and an air leakage hole penetrating through the vibrating diaphragm are formed in the vibrating diaphragm; the insulating isolation layer extends to the upper part of the vibrating diaphragm from the surface of the substrate and is spaced from the vibrating diaphragm, and a plurality of back electrode blocking blocks are formed on the lower surface of the insulating isolation layer; the back electrode is positioned on the upper surface of the insulating isolation layer; the back plate material layer is positioned above the back pole and extends outwards to the surface of the insulating isolation layer; the sound holes penetrate through the back plate material layer, the back electrode and the insulating isolation layer, and correspond to the cavities up and down. According to the utility model, through the optimized design, the insulating isolation layer is formed on the lower surface of the back electrode and is spaced from the vibrating diaphragm, so that even if conductive impurity particles exist in the gap between the vibrating diaphragm and the insulating isolation layer, the vibrating diaphragm and the back electrode cannot be adsorbed and attached together due to the isolation spacing of the insulating isolation layer, the short circuit failure of a device can be effectively avoided, and the performance and yield of the MEMS microphone can be improved. Therefore, the utility model effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the utility model. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims (10)

1. A MEMS microphone, comprising:

a substrate having a cavity formed therein that extends through the substrate;

the vibrating diaphragm is fixed on the substrate through a support, and a folding structure and an air leakage hole penetrating through the vibrating diaphragm are formed in the vibrating diaphragm;

the insulating isolation layer extends to the upper part of the vibrating diaphragm from the surface of the substrate and is spaced from the vibrating diaphragm, and a plurality of back electrode blocking blocks are formed on the lower surface of the insulating isolation layer;

the back electrode is positioned on the upper surface of the insulating isolation layer;

the back plate material layer is positioned above the back pole and extends outwards to the surface of the insulating isolation layer;

the sound holes penetrate through the back plate material layer, the back electrode and the insulating isolation layer, and correspond to the cavities up and down.

2. The MEMS microphone of claim 1, wherein the shape of the insulating isolation layer includes any one of a circle and a polygon.

3. The MEMS microphone of claim 1, wherein the plurality of air-release holes are located between the folded structure and the support.

4. The MEMS microphone of claim 1, wherein the layer of backplate material comprises a layer of silicon nitride.

5. The MEMS microphone of claim 1, wherein the insulating isolation layer comprises a silicon nitride layer.

6. The MEMS microphone of claim 1, wherein the diaphragm comprises a polysilicon diaphragm.

7. The MEMS microphone of claim 1, further comprising a dicing street, the dicing street located at a periphery of the diaphragm, the dicing street revealing the substrate.

8. The MEMS microphone of claim 1, wherein the substrate comprises any one of a silicon substrate, a germanium substrate, a silicon germanium substrate, and a silicon carbide substrate.

9. The MEMS microphone of claim 1, wherein the insulating isolation layer has a thickness less than a thickness of the layer of backplate material.

10. The MEMS microphone of any of claims 1-9, wherein the insulating isolation layer has a thickness of 200nm to 500 nm.

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