Capacitive MEMS microphone structure and method of manufacturing the same

Abstract

The application relates to a capacitive MEMS microphone structure and a manufacturing method thereof, which comprises a substrate, a diaphragm located above the substrate, a back plate located above the diaphragm, the back plate comprising an electrode area and a non-electrode area, a support located between the substrate and the back plate, used for supporting the diaphragm and the back plate, and an air gap located between the diaphragm, the back plate and the support; wherein the capacitive MEMS microphone structure further comprises a reinforcing frame for reinforcing the mechanical strength of the back plate, which is arranged on the surface of the back plate in the non-electrode area. The capacitive MEMS microphone structure of the application is provided with the reinforcing frame, which can improve the mechanical strength of the back plate, avoid crack damage caused by excessive local stress concentration, and help improve the performance and reliability of the capacitive MEMS microphone.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of microphones, in particular to a structure of a condenser MEMS microphone and a manufacturing method thereof. BACKGROUND

[0002] MEMS, full name Micro Electromechanical System, micro-electromechanical system. It refers to a high-tech device with a size of a few millimeters or even smaller, and its internal structure is generally in microns or even nanometers. It is an independent intelligent system. It is mainly composed of three parts of sensors, actuators (executors) and micro energy sources. Micro-electromechanical systems involve physics, semiconductors, optics, electronic engineering, chemistry, materials engineering, mechanical engineering, medicine, information engineering and biological engineering, etc. Various disciplines and engineering technologies; It opens up a broad use for intelligent systems, consumer electronics, wearable devices, smart homes, synthetic biology and microfluidic technology in the field of system biology technology. Common products include MEMS accelerometers, condenser MEMS microphones, micromotors, micropumps, microvibrators, MEMS pressure sensors, MEMS gyroscopes, MEMS humidity sensors, and integrated products thereof.

[0003] The microphone is to convert acoustic signals into electrical signals to enable audio signals to be processed. This acoustic-electric conversion can be achieved by different technologies, but the condenser microphone is the mainstream. The diaphragm in the condenser microphone moves with the acoustic signal, and this movement causes the capacitance to change, thereby generating an electrical signal.

[0004] The condenser MEMS microphone includes two electrode plates suspended on a fixed silicon substrate, one of which is a flexible and freely vibrating diaphragm, and the other is a non-vibrating back plate. This structure forms a variable capacitor. A fixed voltage is applied between the diaphragm and the back plate, and the sound wave enters the microphone through the bottom cavity, the incoming sound wave changes the air pressure, causing the diaphragm to vibrate, thereby changing the distance between the diaphragm and the back plate, and in turn changing the capacitance value. The size of the capacitance value change directly determines the size of the output voltage change (the level of sensitivity).

[0005] For a MEMS condenser microphone, the back plate is required to have high mechanical strength and a porous structure design that allows air to pass through. A higher ratio of porous design can effectively reduce air resistance, thereby improving the signal-to-noise ratio of the condenser MEMS microphone, but the disadvantage is that the effective sensing electrode area and the mechanical rigidity of the back plate are sacrificed, thereby affecting the sensitivity and distortion of the MEMS condenser microphone, causing unstable performance and reliability of the microphone. Balanced consideration is a major issue in the design of MEMS condenser microphones.

[0006] The present application is mainly designed to solve the problem of insufficient rigidity of the back plate affecting the acoustic performance and reliability. SUMMARY

[0007] Therefore, the present application aims to provide a capacitive MEMS microphone structure and a manufacturing method thereof, which can disperse stress, improve the mechanical strength of the back plate structure, solve the problem of cracks caused by high stress concentration, and help improve the performance and mechanical reliability of the capacitive MEMS microphone by arranging a reinforcing frame on the surface of the back plate in the capacitive MEMS microphone structure.

[0008] To achieve the above-mentioned purpose, in one aspect, the present application provides a capacitive MEMS microphone structure, which comprises, as one of the embodiments:

[0009] a substrate;

[0010] a diaphragm located above the substrate;

[0011] a back plate located above the diaphragm, the back plate comprising an electrode area and a non-electrode area;

[0012] a support located between the substrate and the back plate for supporting the diaphragm and the back plate;

[0013] an air gap located between the diaphragm, the back plate and the support;

[0014] wherein the capacitive MEMS microphone structure further comprises a reinforcing frame for reinforcing the mechanical strength of the back plate, the reinforcing frame being arranged on the surface of the back plate of the non-electrode area.

[0015] As one of the embodiments, the reinforcing frame is arranged on the lower surface of the back plate of the non-electrode area, the lower surface being the surface close to the air gap.

[0016] As one of the embodiments, the reinforcing frame is arranged on the upper surface of the back plate of the non-electrode area, the upper surface being the surface away from the air gap.

[0017] As one of the embodiments, a second sound hole is arranged on the back plate.

[0018] As one of the embodiments, a plurality of first sound holes are arranged on the reinforcing frame, and a plurality of second sound holes corresponding to the first sound holes are arranged on the back plate area corresponding to the reinforcing frame, the first sound holes, the second sound holes and the air gap being sequentially communicated.

[0019] As one of the embodiments, the first acoustic hole is in any one of a circular shape, an elliptical shape, a honeycomb shape, a square shape, and a triangular or hexagonal shape.

[0020] As one of the embodiments, the reinforcing frame is connected to the side wall of the support near the air gap.

[0021] As one of the embodiments, the reinforcing frame surrounds the electrode region.

[0022] As one of the embodiments, the capacitive MEMS microphone structure further comprises an anchor region, which is connected between the diaphragm and the backplate and is located between the support and the air gap, for protecting the support when the air gap is formed.

[0023] As one of the embodiments, the reinforcing frame is distributed on the backplate and is located in the non-electrode region and surrounds the solid region between the second acoustic holes.

[0024] As one of the embodiments, the reinforcing frame is connected to the side wall of the anchor region near the air gap.

[0025] To achieve the above-mentioned purpose, another aspect of the present application further provides a manufacturing method of a capacitive MEMS microphone structure, as one of the embodiments, the method comprises the following steps:

[0026] providing a substrate, and forming a first sacrificial layer on the substrate;

[0027] forming a diaphragm on the first sacrificial layer, wherein the lower surface of the diaphragm is connected to the upper surface of the first sacrificial layer;

[0028] forming a second sacrificial layer on the first sacrificial layer, and covering the diaphragm;

[0029] patterning the second sacrificial layer to obtain a patterned through slot, for forming a reinforcing frame for strengthening the mechanical strength of the backplate;

[0030] forming a backplate conductive layer on the second sacrificial layer, and patterning the backplate conductive layer to form an electrode region of the backplate;

[0031] forming a backplate non-conductive layer on the second sacrificial layer, covering the electrode region of the backplate, and filling the patterned through slot to form a non-electrode region of the backplate and the reinforcing frame, wherein the reinforcing frame is connected to the surface of the non-electrode region of the backplate;

[0032] removing the sacrificial layer in a predetermined region between the backplate and the diaphragm, to form an air gap between the backplate and the diaphragm, and a support between the substrate and the backplate, for supporting the diaphragm and the backplate.

[0033] As one of the implementations, it further comprises: after the step of patterning the second sacrificial layer to obtain the patterned through slot, it further comprises: forming a third sacrificial layer, which covers the surface of the second sacrificial layer and the patterned through slot, for lifting the reinforcing frame.

[0034] As one of the implementations, it further comprises: forming an anchor area, which is connected between the diaphragm and the back plate and is located between the support and the air gap, for protecting the support when forming the air gap.

[0035] As one of the implementations, the reinforcing frame is connected to the side wall of the anchor area close to the air gap.

[0036] As one of the implementations, the reinforcing frame is arranged around the electrode area of the back plate.

[0037] As one of the implementations, a second sound hole is formed in the back plate, which is in sequence communicated with the first sound hole on the reinforcing frame and the air gap.

[0038] The first sound hole is formed through the patterned through slot.

[0039] As one of the implementations, it further comprises: forming a cavity in the substrate, which penetrates the substrate in the vertical direction.

[0040] As one of the implementations, it further comprises: removing the preset area of the first sacrificial layer to release the part of the diaphragm opposite to the cavity.

[0041] As one of the implementations, the position of the reinforcing frame is distributed on the back plate and is located in the non-electrode area, and is arranged around the solid area between the second sound holes, and the reinforcing frame is connected to the upper side wall of the anchor area.

[0042] The capacitive MEMS microphone structure and manufacturing method of the present application can provide excellent mechanical rigidity of the overall structure by setting the reinforcing frame, so that the structure can withstand high-strength external pressure test, and reduce and disperse internal stress concentration, thereby greatly reducing the risk of structural stress exceeding the breaking strength of the structure and material itself, and further structural collapse. Specifically, the back plate is divided into a non-electrode area on the periphery and an electrode area on the inner side, which can increase the sensing efficiency of the MEMS capacitive microphone. Therefore, the present application further sets a reinforcing frame on the surface of the non-electrode area of the back plate near the periphery. When the diaphragm of the MEMS microphone is affected by sound pressure, the setting of the reinforcing frame can greatly improve the mechanical rigidity of the back plate. Therefore, the present application can design a higher ratio of sound holes in the back plate area corresponding to the reinforcing frame to reduce air sound resistance, and without sacrificing too much mechanical rigidity of the back plate, causing the back plate to be excessively disturbed due to simultaneous sound pressure, and affecting the correctness of the acoustic signal acquisition. At the same time, in the electrode area of the back plate, the ratio of sound holes of the back plate can be reduced to increase the effective electrode area and increase the sensitivity of the MEMS capacitive microphone. Because of the setting of the reinforcing frame, it helps the back plate not to increase the ratio of nonlinear and asymmetric deformation due to the increase of the hole size, thereby increasing the acoustic distortion of the MEMS capacitive microphone. In addition, the setting of the reinforcing frame improves the structural rigidity, so the thickness of the back plate can also be directly reduced to reduce the air sound resistance. BRIEF DESCRIPTION OF DRAWINGS

[0043] The accompanying drawings, which are included to provide a further understanding of the present application and are incorporated in and constitute a part of this application, illustrate embodiments of the present application and serve to explain the present application. In the drawings:

[0044] Figure 1 The flowchart of the capacitive MEMS microphone manufacturing method provided by an embodiment of the present application.

[0045] Figures 2 to 11 The cross-sectional structure schematic diagram of each main step of the capacitive MEMS microphone manufactured in embodiment 1 of the present application.

[0046] Figure 12 The cross-sectional structure schematic diagram of the capacitive MEMS microphone structure of an embodiment of the present application.

[0047] Figure 13 The top view schematic diagram of the reinforcing frame of an embodiment of the present application. DETAILED DESCRIPTION

[0048] It should be understood that the specific embodiments described herein are merely intended to explain the present application, and are not intended to limit the present application.

[0049] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of the present application.

[0050] It should be noted that, unless otherwise defined, technical terms or scientific terms used in the present disclosure should be understood as their common meanings in the field of the present disclosure. The similar descriptions such as "first", "second" and the like in the present disclosure do not mean any sequence, number or importance, but are only used to distinguish different components. The similar words such as "include" or "contain" mean that the components or objects before the words cover the components or objects listed after the words and their equivalents, and do not exclude other components or objects.

[0051] In order to ensure that the following description of the embodiments of the present disclosure is clear and concise, the detailed description of known functions and known components is omitted in the present disclosure, and the description focuses on the inventive points of the present application.

[0052] It should be noted that the diagrams provided in the embodiments only schematically illustrate the basic inventive concept of the present application. Therefore, only the components related to the present application are shown in the drawings, not the number, shape and size of the components when actually implemented. The shape, number and proportion of each component can be arbitrarily changed when actually implemented, and the layout pattern of the components can be more complex.

[0053] In the prior art, a capacitive MEMS microphone generally includes a diaphragm, a back plate and a support. The back plate, especially the corner area where the back plate and the support are connected, is prone to crack and damage due to stress problems, resulting in poor performance and mechanical reliability of the capacitive MEMS microphone. In view of this problem, the present application is improved, and the corresponding embodiments will be described in detail below.

[0054] Embodiment 1

[0055] In this embodiment, a manufacturing method of a capacitive MEMS microphone structure is provided. Please refer to Figure 1 , Figure 1 The process flow chart of the manufacturing method of the capacitive MEMS microphone structure provided in an embodiment of the present application is shown in FIG. 1. As shown in the figure, the method includes the following steps: Figure 1

[0056] Step S11: providing a substrate.

[0057] Specifically, please refer to Figure 2 ​The substrate 200 can be a silicon substrate, a germanium substrate, a silicon-germanium substrate, a silicon carbide substrate, a silicon-on-insulator substrate, a germanium-on-insulator substrate, a glass substrate, a III-V compound substrate (e.g., a gallium nitride substrate or a gallium arsenide substrate), or another suitable substrate. In this embodiment, the substrate 200 is a silicon substrate, but the present disclosure is not limited thereto.

[0058] Step S12: forming a first sacrificial layer on the substrate.

[0059] Specifically, referring to Figure 2 The first sacrificial layer 310 is formed on the substrate 200 by chemical vapor deposition or another suitable method. The first sacrificial layer 310 is preferably made of silicon dioxide to insulate the diaphragm 400 formed later and to form a high selectivity etching ratio to avoid damaging the diaphragm 400. However, the material of the first sacrificial layer is not limited thereto and can include, for example, silicon nitride, a stack of silicon oxide and silicon nitride, or another suitable material, which can be selected as needed and is not limited herein.

[0060] As an example, after the first sacrificial layer is formed on the substrate, the method can further include step S121: patterning the first sacrificial layer to form a first annular through slot.

[0061] Specifically, referring to Figure 3 The first annular through slot 311 is formed by patterning the first sacrificial layer 310 by photolithography, etching, or another suitable process. The first annular through slot 311 is used to fill a non-conductive material of the back plate to form an anchor area later. The anchor area is used to connect and support the diaphragm and the back plate and to protect the support portion surrounding the air gap when the air gap is formed later.

[0062] It should be noted that the anchor area as a protection and support structure can also be formed in other ways, which are not limited herein. For example, the first annular through slot 311 is not separately formed, and the anchor area is defined by the original sacrificial layer, i.e., a portion of the sacrificial layer is reserved as the anchor area.

[0063] Step S13: forming a diaphragm on the first sacrificial layer, with a lower surface of the diaphragm connected to an upper surface of the first sacrificial layer.

[0064] Specifically, referring to Figure 4 The diaphragm 400 is formed on the first sacrificial layer 310. As shown, a diaphragm material layer is first formed by physical vapor deposition or another suitable method, and then the diaphragm 400 is obtained by patterning by photolithography and etching or another suitable process. The diaphragm 400 is a vibrating electrode of the capacitive MEMS microphone, and the diaphragm 400 can be made of polysilicon or another suitable elastic metal.

[0065] As an example, the diaphragm is formed on the first sacrificial layer, and then the step S131 of removing the diaphragm part corresponding to the first annular through slot is further included.

[0066] In particular, referring to Figure 4 , the anchor area is connected to the diaphragm, the back plate and the substrate as a support structure, and therefore, the corresponding part of each layer needs to be opened to fill the corresponding material, for example, the non-conductive material of the back plate to form the anchor area. Wherein, the anchor area can be formed in stages or at one time, which is not limited here.

[0067] It should be noted that the anchor area is an improvement on the support of the MEMS microphone in the prior art, which is essentially equivalent to part of the support, and an additional protective wall is added to the support, so that when the sacrificial layer in the predetermined area is removed to form an air gap and a support, a complete and stable support is formed.

[0068] Step S14: forming a second sacrificial layer, the second sacrificial layer is located on the first sacrificial layer and covers the diaphragm.

[0069] In particular, referring to Figure 5 , the second sacrificial layer 320 is formed on the first sacrificial layer 310 and covers the diaphragm 400. Wherein, the second sacrificial layer 320 is formed by chemical vapor deposition, physical vapor deposition or other suitable methods, and the material of the second sacrificial layer 320 can include silicon dioxide or other suitable materials. The material of the second sacrificial layer 320 can be the same as or different from the material of the first sacrificial layer 310, which is not limited here. However, as a preferred, the material of the second sacrificial layer 320 has a high selectivity etching ratio with the material of the diaphragm 400, so as to avoid damage to the diaphragm 400 in subsequent etching.

[0070] As an example, after step S14, it further includes: removing the part of the second sacrificial layer corresponding to the first annular through slot 311 to form an anchor area.

[0071] Step S15: forming a third sacrificial layer, the third sacrificial layer is located on the second sacrificial layer and covers the second sacrificial layer.

[0072] In particular, referring to Figure 6 , the third sacrificial layer 330 is formed on the second sacrificial layer 320. Wherein, the third sacrificial layer 330 is formed by chemical vapor deposition, physical vapor deposition or other suitable methods, and the material of the third sacrificial layer 330 can include silicon dioxide or other suitable materials. The material of the third sacrificial layer 330 can be the same as or different from the material of the second sacrificial layer 320, which is not limited here. However, as a preferred, the material of the third sacrificial layer 330 has a high selectivity etching ratio with the material of the diaphragm 400, so as to avoid damage to the diaphragm 400 in subsequent etching.

[0073] As an example, after step S15, further comprising: removing the part of the third sacrificial layer corresponding to the first annular through slot 311 to form an anchor region.

[0074] Step S16: patterning the third sacrificial layer to form a patterned through slot for forming a reinforcing frame to strengthen the mechanical strength of the backplate.

[0075] Specifically, as shown in Figure 7 , a patterned through slot 331 is formed on the peripheral part of the third sacrificial layer 330 by lithography, etching or other processes, and the patterned through slot 331 penetrates the third sacrificial layer 330, wherein the patterned through slot 331 can be in the form of a surrounding grid. The shape of the grid can be circular, oval, honeycomb, square, triangular, polygonal or any shape. The patterned through slot 331 is used to fill the backplate material to form a reinforcing frame.

[0076] As an example, after step S16, further comprising: further forming a blocking block groove in the third sacrificial layer.

[0077] Specifically, as shown in Figure 8 , a blocking block groove 332 is further formed in the third sacrificial layer by lithography, etching or other processes, wherein the blocking block groove 332 can penetrate the third sacrificial layer or not, which is not limited herein.

[0078] Step S17: forming a backplate conductive layer on the third sacrificial layer, and patterning the backplate conductive layer to form an electrode region of the backplate.

[0079] Specifically, as shown in Figure 8 , a backplate conductive layer is formed by physical vapor deposition or other suitable methods, covering the third sacrificial layer 330, and the relevant part is removed to obtain an electrode region 600. The electrode region 600 covers an area corresponding to the sensing area of the capacitive MEMS microphone, to form a capacitive structure with the diaphragm 400, that is, the effective capacitive area of the capacitive MEMS microphone. Then, the part of the backplate conductive layer corresponding to the area of the blocking block groove 332 is removed by lithography, etching or other processes, and the conductive material in the blocking block groove 332 is removed, and a third acoustic hole 610 is formed in the electrode region 600. The material of the backplate conductive layer can include polysilicon or other suitable materials.

[0080] Step S18: forming a backplate non-conductive layer on the third sacrificial layer, covering the electrode region of the backplate and filling the patterned through slot to form a non-electrode region of the backplate and a reinforcing frame, and the reinforcing frame is connected to the surface of the non-electrode region of the backplate.

[0081] Specifically, as shown in Figure 9As shown, by first depositing a non-conductive material by chemical vapor deposition, physical vapor deposition or other suitable method to form a backplate non-conductive layer, the backplate non-conductive layer covers the top surface and side surface of the third sacrificial layer 330, and fills into the patterned through slot 331 to form a reinforcing frame 500, and forms a backplate non-electrode region 700, the bottom of the reinforcing frame 500 protrudes into the air gap 900 (see Figure 11 ). The material of the backplate non-conductive layer can use insulating material or other suitable material. Of course, the non-electrode region 700 and the reinforcing frame 500 of the backplate can also be formed separately, or the reinforcing frame 500 can be formed when the non-electrode region 700 of the backplate is formed, which is not limited here. After the reinforcing frame 500 is formed, the first sound hole 510 is also formed, that is, after the corresponding sacrificial layer in the reinforcing frame 500 is removed in the subsequent process, the first sound hole 510 is formed, that is, the reinforcing frame 500 has a plurality of first sound holes 510 (see Figure 11 )。

[0082] It should be noted that the non-electrode region 700 of the backplate and the electrode region 600 of the backplate are essentially different layers of the backplate, that is, the conductive layer and the non-conductive layer of the backplate, but in the technical solution of the present application, the area of the backplate non-conductive layer is larger than that of the backplate conductive layer, that is, in the air gap range, the backplate conductive layer does not necessarily exist in the area of the backplate non-conductive layer, that is, the backplate conductive layer is located in the middle region of the air gap, and at both ends of the backplate conductive layer, that is, the surface of the backplate non-conductive layer corresponding to the two ends of the air gap is provided with the reinforcing frame 500. Of course, the reinforcing frame 500 can also extend to the middle region according to different setting modes of the backplate electrode region 500.

[0083] As an example, the backplate non-conductive layer also covers the first annular through slot and the region corresponding to the first annular through slot on different layers to form an anchor region.

[0084] For details, please refer to Figure 9The backplate non-conductive layer covers the first annular through slot 311 and the regions on the diaphragm 400, the second sacrificial layer 320 and the third sacrificial layer 330 corresponding to the first annular through slot to form the anchor region 800. That is, when the backplate non-conductive layer is formed, the non-conductive material is filled into the first annular through slot 311 and the regions on the diaphragm 400, the second sacrificial layer 320 and the third sacrificial layer 330 corresponding to the first annular through slot to form the anchor region 800. The anchor region 800 connects the substrate 200, the diaphragm 400 and the backplate 700, and the backplate 700 covers the anchor region 800. Of course, the anchor region 800 can be formed in stages or filled at one time, which is not limited herein. That is, when the anchor region 800 is formed, holes are formed on each sacrificial layer, and the mechanical layer is used to provide electrical connection. It is worth noting that when the reinforcing frame 500 and the anchor region 800 are formed, a single mask can be used, or different masks can be used to form the reinforcing frame 500 and the anchor region 800.

[0085] Please refer to Figure 10 In the embodiment, the second acoustic hole 710 is also formed in the backplate non-electrode region 700, and the second acoustic hole 710 on the backplate non-electrode region corresponding to the backplate electrode region 600, the third acoustic hole 610 in the backplate electrode region 600 and the air gap are sequentially communicated. The second acoustic hole 710 on the backplate non-electrode region 700 corresponding to the reinforcing frame 500 is sequentially communicated with the first acoustic hole 510 on the reinforcing frame 500 and the air gap.

[0086] As an example, when the backplate non-conductive layer is formed, the backplate non-conductive material is also filled into the blocking block groove 332 to constitute the blocking block 720 connected with the lower surface of the backplate non-electrode region 700, which is used to prevent the diaphragm 400 from adhering to the electrode region 600 of the backplate.

[0087] In the embodiment, please refer to Figure 11 Further, chemical mechanical polishing or other suitable processes can be used to thin the substrate 200, and deep reactive ion etching or other suitable processes can be used to form the cavity 210 in the substrate 200, and the cavity 210 penetrates the substrate 200 in the vertical direction.

[0088] As an example, the first sacrificial layer 310 between the substrate 210 and the diaphragm 400 is also removed inside the anchor region 800.

[0089] Finally, in the structure release at the end of the process, the second sacrificial layer and the third sacrificial layer in the structure operation region are removed, and the inner wall of the reinforcing frame 500 and the part surrounded by the anchor region 800 are removed to obtain the air gap 900 between the backplate non-electrode region 700 and the diaphragm 400.

[0090] It should be noted that in embodiments without anchor region 800, the air gap 900 between the backplate non-electrode region 700 and the diaphragm 400, along with the brackets 300 on either side of the air gap, is formed by removing the second and third sacrificial layers from the structural operating area (i.e., the pre-set area). Without the protection of anchor region 800, brackets 300 are easily damaged when removing the sacrificial layers.

[0091] In this embodiment, the reinforcement frame 500 is formed on one side of the back plate non-electrode area 700 and is located in the air gap 900 between the diaphragm 400 and the back plate non-electrode area 700, with the bottom protruding from the air gap 900.

[0092] As an example, the reinforcement frame 500 is connected to the inner sidewall of the anchor area 800 .

[0093] Specifically, please refer to Figure 12 In this embodiment, the reinforcement frame 500 is connected to the inner wall of the anchor area 800 to better achieve support and enhance stability.

[0094] It should be noted that the technical solution of the present invention can also remove the anchor area 800, that is, it does not include the anchor area 800. The anchor area 800 is actually to protect the integrity of the bracket 300 when the second sacrificial layer and the third sacrificial layer in the structural operation area are removed to form the air gap 900 and the bracket 300 on both sides of the air gap 900. When there is no anchor area 800, the reinforcement frame can be directly connected to the bracket 300. Figure 12 The connection lines are shown to better illustrate that the reinforcement frame is connected to the anchor area 800, or is formed as one piece. Compared with using a sacrificial layer as a bracket, the anchor area 800 and the reinforcement frame are formed as one piece, and the mechanical structure is more stable.

[0095] In this embodiment, when forming the reinforcement frame 500, a first sound hole 510 is formed on the reinforcement frame 500 to allow sound waves to enter. The shape of the first sound hole 510 is circular, elliptical, honeycomb, square, triangle, polygonal or any other shape.

[0096] Specifically, please refer to Figure 13 , Figure 13 FIG. 1 shows a top view of a reinforcement frame according to an embodiment. Figure 11 As shown, the backplane material is filled into the patterned through-grooves 331 to form a reinforcement frame 500, on which a first sound hole 510 is formed. In this embodiment, the reinforcement frame is an integral structure disposed around the backplane electrode region 600. Of course, in other embodiments, the reinforcement frame can also be disposed discontinuously around the backplane electrode region 600.

[0097] Thus, according to the method, a capacitive MEMS microphone structure is manufactured. By arranging the reinforcing frame 500 on the surface of the non-electrode area of the back plate in the capacitive MEMS microphone structure, stress can be dispersed, the mechanical strength of the back plate structure is improved, the problem of cracks caused by high stress concentration is solved, and the performance and mechanical reliability of the capacitive MEMS microphone are improved.

[0098] Embodiment 2

[0099] The embodiment provides another method for manufacturing a capacitive MEMS microphone structure. The difference between the method for manufacturing the capacitive MEMS microphone structure provided by the embodiment and the method for manufacturing the capacitive MEMS microphone structure provided by Embodiment 1 is that the step of forming the reinforcing frame is different, specifically, steps S4, S5 and S6 in Embodiment 1 are changed, and thus the common parts refer to Embodiment 1. Specifically, the embodiment comprises the following steps:

[0100] Step S21: providing a substrate;

[0101] Step S22: forming a first sacrificial layer on the substrate;

[0102] Step S23: forming a diaphragm on the first sacrificial layer, wherein the lower surface of the diaphragm is connected to the upper surface of the first sacrificial layer;

[0103] Step S24: forming a second sacrificial layer on the first sacrificial layer and covering the diaphragm;

[0104] Step S25: patterning the second sacrificial layer to obtain a patterned through slot, so as to form a reinforcing frame for reinforcing the mechanical strength of the back plate;

[0105] Step S26: forming a third sacrificial layer covering the surface of the second sacrificial layer and the patterned through slot, so as to elevate the reinforcing frame;

[0106] Step S27: forming a back plate conductive layer on the third sacrificial layer, and patterning the back plate conductive layer to form an electrode area of the back plate;

[0107] Step S28: forming a back plate non-conductive layer on the third sacrificial layer, covering the electrode area of the back plate, and filling the patterned through slot to form a non-electrode area of the back plate and the reinforcing frame, wherein the reinforcing frame is connected to the surface of the non-electrode area of the back plate;

[0108] Step S29: removing the sacrificial layer in a predetermined area between the back plate and the diaphragm to form an air gap between the back plate and the diaphragm, and a support between the substrate and the back plate for supporting the diaphragm and the back plate.

[0109] Specifically, the third sacrificial layer in Embodiment 1 and Embodiment 2 are both to lift the position of the reinforcing frame, but in two different ways. In this embodiment, a patterned through slot is formed in the second sacrificial layer, the patterned through slot penetrates the second sacrificial layer, then the third sacrificial layer is formed, the third sacrificial layer covers the surface of the second sacrificial layer and the patterned through slot, that is, a complete third sacrificial layer is laid on the second sacrificial layer, for the patterned through slot part, the corresponding third sacrificial layer is laid on the surface of the patterned through slot, thereby lifting the height of the surface of the second sacrificial layer and the patterned through slot, so as to lift the height of the formed reinforcing frame when the reinforcing frame is formed. The method in Embodiment 1 is essentially equivalent to one layer of sacrificial layer, that is, the second sacrificial layer and the third sacrificial layer are one layer, that is, the patterned through slot is not penetrated, for example, the thickness of one layer is made to be the thickness of the second sacrificial layer plus the thickness of the third sacrificial layer.

[0110] It should be noted that this embodiment only describes the reinforcing frame part, and the anchor area step formed by improving the support can refer to Embodiment 1.

[0111] Embodiment 3

[0112] This embodiment provides another method for manufacturing a capacitive MEMS microphone structure. The difference between this embodiment and the method for manufacturing a capacitive MEMS microphone structure provided in Embodiment 1 is that step S5 of forming a third sacrificial layer on the second sacrificial layer and covering the diaphragm is omitted. That is, all the steps after step S5 are directly performed on the second sacrificial layer.

[0113] Embodiment 1 is a relatively preferred method, which essentially lifts the position of the reinforcing frame by adding one more layer of sacrificial layer. Of course, the same lifting effect can also be achieved by using multiple layers and increasing the thickness of a single layer. However, when multiple layers are used, different materials can be used to facilitate related operations. For specific steps, please refer to the related step descriptions in Embodiment 1.

[0114] Embodiment 4

[0115] This embodiment provides a capacitive MEMS microphone structure. Please refer to Figure 12 , which shows a cross-sectional structure schematic diagram of a capacitive MEMS microphone structure. As Figure 12 shown, the capacitive MEMS microphone structure includes:

[0116] a substrate 200;

[0117] a diaphragm 400 located above the substrate 200;

[0118] a back plate located above the diaphragm 400, the back plate including an electrode area 600 and a non-electrode area 700;

[0119] A support 300 is located between the substrate 200 and the non-electrode region 700 of the back plate, and is used to support the diaphragm 400 and the back plate;

[0120] A gas gap 900 is located between the diaphragm 400, the non-electrode region 700 of the back plate, and the support 300;

[0121] The capacitive MEMS microphone structure further comprises a reinforcing frame 500 for reinforcing the mechanical strength of the back plate, the reinforcing frame 500 being located in the gas gap 900 and arranged on the side of the non-electrode region 700 close to the gas gap 900.

[0122] As an example, the reinforcing frame 500 is arranged around the electrode region 600.

[0123] As an example, a plurality of third sound holes 610 are arranged on the electrode region 600.

[0124] As an example, a plurality of second sound holes 710 are arranged on the non-electrode region 700.

[0125] As an example, a plurality of first sound holes 510 are arranged on the reinforcing frame 500.

[0126] As an example, the third sound holes 610 on the electrode region 600 are in communication with the second sound holes 710 on the corresponding region of the non-electrode region 700 and the gas gap 900.

[0127] As an example, the first sound holes 510 on the reinforcing frame 500 are in any one of a circular shape, an elliptical shape, a honeycomb shape, a square shape, or a triangular shape.

[0128] Specifically, the first sound holes 510 on the reinforcing frame 500 can be in any one of a circular shape, an elliptical shape, a honeycomb shape, a square shape, or a triangular shape, or even any other shape, which is not limited herein. It should be noted that the first sound holes 510 can be realized by the graphic through slot 331 mentioned in Embodiment 1, or by other suitable processes.

[0129] As an example, the reinforcing frame 500 is in a surrounding mesh shape.

[0130] Specifically, the reinforcing frame 500 is in a surrounding mesh shape, i.e. the reinforcing frame 500 is arranged around the electrode region 600 on the non-electrode region, wherein the mesh shape can be formed by the first sound holes 510 on the reinforcing frame 500.

[0131] As an example, the side of the non-electrode region 700 close to the diaphragm 400 is connected with a blocking block 720, and the lower surface of the blocking block 720 protrudes from the side of the electrode region 600 close to the diaphragm 400.

[0132] As an example, an anchor region 800 is connected between the substrate 200 and the backplate, and is located between the support 300 and the air gap 900, for protecting the support 300 when forming the air gap 900.

[0133] As an example, the anchor region 800 is made of the same material as the non-electrode region 700.

[0134] Specifically, the anchor region 800 can be dug in each layer independently, and then filled with backplate material or other materials, or can be dug at one time. The anchor region is connected to the substrate 200, and is made of the same material as the backplate 700, so that the structure release can be better, and the complete and stable support 300 can be formed.

[0135] As an example, the reinforcing frame 500 is connected to the side wall of the anchor region 800 close to the air gap 900.

[0136] As an example, the capacitive MEMS microphone structure can be manufactured by the method described in Embodiment 1, or can be manufactured by other suitable methods, which should not excessively limit the protection scope of the present application. The specific description of each structure is referred to the foregoing embodiments, and will not be described here.

[0137] It should be noted that the non-electrode region 700 is the backplate region without a conductive electrode, and the electrode region 600 is the backplate region with a conductive electrode, as shown in Figure 12 , that is, part of the surface region of the backplate close to the air gap 900.

[0138] In summary, the capacitive MEMS microphone structure of the present application can provide excellent mechanical strength of the overall structure by setting the reinforcing frame for strengthening the mechanical strength of the backplate, so that the structure can withstand high-strength external pressure test, and reduce and disperse internal stress concentration, thereby greatly reducing the risk that the structure stress exceeds the damage strength of the structure and the material itself, and further collapsing the structure. In addition, the setting of the reinforcing frame can also help the backplate not to increase the rate of nonlinear and asymmetric deformation due to the increase in the size of the acoustic hole, resulting in acoustic distortion of the capacitive MEMS microphone. In addition, since the setting of the reinforcing frame improves the rigidity of the structure, the thickness of the backplate (non-conductive layer of the backplate) can also be directly reduced to reduce the air acoustic resistance.

[0139] Embodiment 5

[0140] Another capacitive MEMS microphone structure of the embodiment of the present application is different from Embodiment 4 in that the setting position of the reinforcing frame 500 is changed in the present embodiment. Specifically, please refer to Figure 12 , the capacitive microphone structure in the present embodiment comprises:

[0141] a substrate 200;

[0142] a diaphragm 400 located above the substrate 200;

[0143] a back plate located above the diaphragm 400, the back plate comprising an electrode area 600 and a non-electrode area 700;

[0144] a support 300 located between the substrate 200 and the non-electrode area 700 of the back plate, for supporting the diaphragm 400 and the back plate;

[0145] an air gap 900 located between the diaphragm 400, the back plate, and the support 300;

[0146] In the capacitive MEMS microphone structure, a reinforcing frame 500 is arranged on the non-electrode area 700 of the back plate, for reinforcing the mechanical strength of the back plate.

[0147] Specifically, the specific description of the common parts of the present embodiment can refer to the foregoing embodiments, which will not be described here. It should be noted that in other embodiments, the reinforcing frame can be arranged on both sides (two surfaces) of the non-electrode area of the back plate, that is, the embodiments 4 and 5 are combined.

[0148] In other embodiments, the reinforcing frame structure of the present application can also be used in a capacitive MEMS microphone structure with a single diaphragm and a double back plate, to reinforce the mechanical strength of the back plate, avoid cracks in the part that is easily affected by stress concentration, and help to improve the performance and mechanical reliability of the capacitive MEMS microphone.

[0149] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. A capacitive MEMS microphone structure, characterized in that: include: substrate; a diaphragm, the diaphragm being located above the substrate; A back plate, the back plate is located above the diaphragm, and the back plate includes an electrode area and a non-electrode area; a bracket, the bracket being located between the substrate and the back plate and being used to support the diaphragm and the back plate; an air gap, the air gap being located between the diaphragm, the back plate, and the bracket; The capacitive MEMS microphone structure further includes a reinforcement frame for enhancing the mechanical strength of the back plate, wherein the reinforcement frame is arranged on the surface of the back plate in the non-electrode area, the reinforcement frame is arranged around the electrode area, and the reinforcement frame is connected to the side wall of the bracket close to the air gap; The reinforcement frame is provided with a plurality of first sound holes, and the back plate area corresponding to the reinforcement frame is provided with a plurality of second sound holes corresponding to the first sound holes, and the first sound holes, the second sound holes and the air gap are connected in sequence.

2. The capacitive MEMS microphone structure according to claim 1, characterized in that: The reinforcement frame is arranged on the lower surface of the back plate in the non-electrode area, and the lower surface is a side close to the air gap.

3. The capacitive MEMS microphone structure according to claim 1, wherein: The reinforcement frame is arranged on the upper surface of the back plate in the non-electrode area, and the upper surface is a side away from the air gap.

4. The capacitive MEMS microphone structure according to claim 3, characterized in that: The shape of the first sound hole is any one of circular, elliptical, honeycomb, square, triangular or hexagonal.

5. The capacitive MEMS microphone structure according to claim 1, wherein: The capacitive MEMS microphone structure further includes an anchor region connected between the substrate and the back plate and located between the support and the air gap, so as to protect the support when the air gap is formed.

6. The capacitive MEMS microphone structure according to claim 5, characterized in that: The reinforcement frame is connected to a side wall of the anchor area close to the air gap.

7. A method for manufacturing a capacitive MEMS microphone structure, characterized in that: The following steps are involved: providing a substrate, and forming a first sacrificial layer on the substrate; forming a diaphragm on the first sacrificial layer, wherein the lower surface of the diaphragm is connected to the upper surface of the first sacrificial layer; forming a second sacrificial layer, wherein the second sacrificial layer is located on the first sacrificial layer and covers the diaphragm; Patterning the second sacrificial layer to obtain patterned through grooves for forming a reinforcement frame for enhancing the mechanical strength of the backplane; forming a backplane conductive layer on the second sacrificial layer, and patterning the backplane conductive layer to form an electrode region of the backplane, wherein the reinforcement frame is disposed around the electrode region of the backplane; forming a backplane non-conductive layer on the second sacrificial layer, covering the electrode area of ​​the backplane and filling the patterned through-grooves to form the non-electrode area of ​​the backplane and the reinforcement frame, wherein the reinforcement frame is connected to the surface of the non-electrode area of ​​the backplane; Removing a sacrificial layer in a predetermined area between the back plate and the diaphragm to form an air gap between the back plate and the diaphragm, and a bracket between the substrate and the back plate for supporting the diaphragm and the back plate; forming an anchoring area connected between the diaphragm and the back plate and located between the bracket and the air gap, so as to protect the bracket when the air gap is formed, and the reinforcement frame being connected to a side wall of the anchoring area close to the air gap; It also includes forming a second sound hole in the back plate, wherein the second sound hole is connected with the first sound hole on the reinforcement frame and the air gap in sequence; wherein the first sound hole is formed by the graphic through groove.

8. The method for manufacturing a capacitive MEMS microphone structure according to claim 7, wherein: After the step of patterning the second sacrificial layer to obtain the patterned through-grooves, the method further includes: forming a third sacrificial layer, wherein the third sacrificial layer covers the surfaces of the second sacrificial layer and the patterned through-grooves to elevate the reinforcement frame.

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