CN113727265A

CN113727265A - Capacitive MEMS microphone structure and manufacturing method thereof

Info

Publication number: CN113727265A
Application number: CN202110860300.7A
Authority: CN
Inventors: 庄红红
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-07-28
Filing date: 2021-07-28
Publication date: 2021-11-30

Abstract

The invention relates to a capacitance type MEMS microphone structure and a manufacturing method thereof, comprising the following steps: a substrate; the vibrating diaphragm is positioned above the substrate; the back plate is positioned above the vibrating diaphragm and comprises an electrode area and a non-electrode area; the support is positioned between the substrate and the back plate and used for supporting the vibrating diaphragm and the back plate; the air gap is positioned among the vibrating diaphragm, the back plate and the bracket; the capacitive MEMS microphone structure further comprises a reinforcing frame for reinforcing the mechanical strength of the back plate, and the reinforcing frame is arranged on the surface of the back plate of the non-electrode area. The reinforcing frame is arranged in the structure of the capacitive MEMS microphone, so that the mechanical strength of the back plate can be improved, the crack damage caused by over-concentration of local stress can be avoided, and the performance and the reliability of the capacitive MEMS microphone can be improved.

Description

Capacitive MEMS microphone structure and manufacturing method thereof

Technical Field

The invention relates to the technical field of microphones, in particular to a capacitive MEMS microphone structure and a manufacturing method thereof.

Background

MEMS, Micro electro mechanical System. The device is a high-tech device with the size of several millimeters or even smaller, the internal structure of the device is generally in the micrometer or even nanometer level, and the device is an independent intelligent system. The device mainly comprises a sensor, an actuator and a micro-energy source. The micro electro mechanical system relates to a plurality of subjects and engineering technologies such as physics, semiconductor, optics, electronic engineering, chemistry, material engineering, mechanical engineering, medicine, information engineering, biological engineering and the like; the method develops wide application in the fields of synthetic biology and microfluidic technology of intelligent systems, consumer electronics, wearable equipment, smart homes, system biotechnology and the like. Common products include MEMS accelerometers, capacitive MEMS microphones, micro-motors, micro-pumps, micro-vibrators, MEMS pressure sensors, MEMS gyroscopes, MEMS humidity sensors, and the like, as well as integrated products thereof.

Microphones convert acoustic signals into electrical signals to enable processing of audio signals. Such acoustic-electric conversion can be realized by different technologies, but a condenser microphone is the mainstream. The membrane in a condenser microphone moves with the acoustic signal, and this movement causes a change in capacitance, which in turn generates an electrical signal.

The capacitor type MEMS microphone comprises two electrode plates suspended on a fixed silicon substrate, wherein one electrode plate is a vibrating diaphragm capable of flexibly and freely vibrating, and the other electrode plate is a non-vibrating back plate. This structure forms a variable capacitance. Fixed voltage is exerted between vibrating diaphragm and backplate, and the sound wave gets into the microphone through the cavity of bottom, and the sound wave of afferent changes atmospheric pressure, causes the vibrating diaphragm vibration, therefore changes the distance between vibrating diaphragm and the backplate, and then changes the capacitance value, and the size of capacitance value variation volume then the size of direct decision its output voltage variation volume (the height of sensitivity).

For the MEMS condenser microphone, the design of the upper back plate requires a higher mechanical strength and a porous structure design allowing air to pass through, and the higher ratio of the porous design can effectively reduce the air acoustic 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, and causing the unstable performance and reliability of the microphone. Balancing considerations are a major issue in MEMS condenser microphone design.

The invention is mainly designed aiming at the problem that the rigidity of the backboard is insufficient to influence the acoustic performance and the reliability.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a capacitive MEMS microphone structure and a method for manufacturing the same, in which a reinforcement frame is disposed in a corresponding area on a surface of a backplate in the capacitive MEMS microphone structure, so as to disperse stress, improve mechanical strength of the backplate structure, solve problems such as cracks caused by high stress concentration, and contribute to improving performance and mechanical reliability of the capacitive MEMS microphone.

To achieve the above object, an aspect of the present invention provides a capacitive MEMS microphone structure, which includes, as an embodiment:

a substrate;

a diaphragm positioned above the substrate;

the back plate is positioned above the vibrating diaphragm and comprises an electrode area and a non-electrode area;

a support located between the substrate and the backplate for supporting the diaphragm and the backplate;

an air gap between the diaphragm, the backplate, and the bracket;

the capacitive MEMS microphone structure further comprises a reinforcing frame for reinforcing the mechanical strength of the back plate, and the reinforcing frame is arranged on the surface of the back plate of the non-electrode area.

In one embodiment, the reinforcing frame is disposed on a lower surface of the back plate of the non-electrode region, where the lower surface is a surface close to the air gap.

In one embodiment, the reinforcing frame is disposed on an upper surface of the back plate of the non-electrode region, where the upper surface is a surface away from the air gap.

In one embodiment, a second sound hole is disposed on the back plate.

As an implementation manner, a plurality of first sound holes are formed in the reinforcing frame, a plurality of second sound holes corresponding to the first sound holes are formed in a back plate area corresponding to the reinforcing frame, and the first sound holes, the second sound holes and the air gaps are sequentially communicated.

As one embodiment, the shape of the first sound hole is any one of a circle, an ellipse, a honeycomb, a square, and a triangle or a hexagon.

In one embodiment, the reinforcing frame is connected to the side wall of the bracket near the air gap.

In one embodiment, the reinforcing frame is disposed around the electrode region.

As one embodiment, the condenser MEMS microphone structure further includes an anchor region connected between the diaphragm 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.

In one embodiment, the reinforcing frame is distributed on the back plate and located in the non-electrode area, and surrounds the solid area between the second sound holes.

In one embodiment, the reinforcing frame is connected to the side wall of the anchoring zone adjacent to the air gap.

In order to achieve the above object, another aspect of the present invention further provides a method for manufacturing a capacitive MEMS microphone structure, which includes the following steps:

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

forming a vibrating diaphragm on the first sacrificial layer, wherein the lower surface of the vibrating diaphragm is connected with the upper surface of the first sacrificial layer;

forming a second sacrificial layer, wherein the second sacrificial layer is positioned on the first sacrificial layer and covers the vibrating diaphragm;

patterning the second sacrificial layer to obtain a patterned through groove for forming a reinforcing frame for reinforcing the mechanical strength of the back plate;

forming a back plate conducting layer on the second sacrificial layer, and patterning the back plate conducting layer to form an electrode area of a back plate;

forming a back plate non-conductive layer on the second sacrificial layer, covering the electrode area of the back plate and filling the pattern through grooves to form the non-electrode area of the back plate and the reinforcing frame, wherein the reinforcing frame is connected with the surface of the non-electrode area of the back plate;

and removing the sacrificial layer in a preset area between the back plate and the vibrating diaphragm to form an air gap between the back plate and the vibrating diaphragm and a bracket between the substrate and the back plate and used for supporting the vibrating diaphragm and the back plate.

As one of the implementation modes, the method further comprises the following steps: after the step of patterning the second sacrificial layer to obtain the patterned through groove, the method further comprises: and forming a third sacrificial layer, wherein the third sacrificial layer covers the second sacrificial layer and the surface of the pattern through groove so as to be used for lifting the reinforcing frame.

As one of the implementation modes, the method further comprises the following steps: and forming an anchor area, wherein the anchor area is connected between the diaphragm and the back plate and is positioned between the support and the air gap so as to protect the support when the air gap is formed.

In one embodiment, the reinforcing frame is disposed around the electrode region of the back plate.

As one embodiment, a second sound hole is formed in the back plate, and the second sound hole is sequentially communicated with the first sound hole on the reinforcing frame and the air gap;

wherein the first acoustic port is formed through the patterned through-groove.

As one of the implementation modes, the method further comprises the following steps: a cavity is formed in the substrate, the cavity penetrating the substrate in a vertical direction.

As one of the implementation modes, the method further comprises the following steps: and removing a preset area of the first sacrificial layer to release the part of the diaphragm opposite to the cavity.

In one embodiment, the reinforcing frame is distributed on the back plate and located on the non-electrode area, surrounds the solid area between the second sound holes, and is connected with the upper side wall of the anchor area.

According to the capacitive MEMS microphone structure and the manufacturing method thereof, the reinforcing frame is arranged, so that the excellent mechanical rigidity of the whole structure can be provided, the structure can bear a high-strength external pressure test, and the internal stress concentration is reduced and dispersed, so that the risk that the structural stress exceeds the damage strength of the structure and the material per se, and further the structure is collapsed is greatly reduced. The back plate is divided into a peripheral non-electrode area and an inner electrode area, so that the sensing efficiency of the MEMS capacitive microphone can be improved, and therefore, a reinforcing frame is additionally arranged on the surface, close to the peripheral non-electrode area, of the back plate. Meanwhile, in the electrode area of the back plate, the sound hole ratio of the back plate can be reduced to improve the effective electrode area so as to increase the sensitivity of the MEMS capacitive microphone, and the arrangement of the reinforcing frame helps the back plate not to increase the nonlinear and asymmetric deformation ratio of the back plate due to the increase of the size of the hole, so that the acoustic distortion of the MEMS capacitive microphone is increased.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:

fig. 1 is a schematic flow chart of a method for manufacturing a capacitive MEMS microphone according to an embodiment of the present invention.

Fig. 2 to 11 are schematic cross-sectional structure diagrams of main steps of manufacturing a capacitive MEMS microphone according to embodiment 1 of the present invention.

Fig. 12 is a schematic cross-sectional view of a capacitive MEMS microphone structure according to an embodiment of the invention.

Fig. 13 is a schematic top view of a reinforcing frame according to an embodiment of the invention.

Detailed Description

It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the scope of the present invention.

It is to be noted that unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The description herein of "first," "second," and the like, does not denote any order, quantity, or importance, but rather the description is used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items.

To ensure the following description of the embodiments of the present disclosure is clear and concise, a detailed description of known functions and known components may be omitted from the present disclosure, and the description will focus on the inventive points of the present disclosure.

It should be noted that the illustrations provided in the present embodiment are only for illustrating the basic inventive concept of the present invention in a schematic manner. Therefore, the components related to the present invention are only shown in the drawings, and not drawn according to the number, shape and size of the components in actual implementation, the type, number and ratio of the components in actual implementation may be changed at will, and the layout of the components may be more complicated.

In the prior art, a condenser MEMS microphone generally includes a diaphragm, a back plate and a support, wherein the back plate, especially a corner region 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 condenser MEMS microphone. The present invention is improved in view of the above problems, and the following description will explain the present invention in detail with reference to the corresponding examples.

Example 1

Referring to fig. 1, fig. 1 is a process flow diagram of a method for manufacturing a capacitive MEMS microphone structure according to an embodiment of the present invention. As shown in fig. 1, the method comprises the steps of:

step S11, a substrate is provided.

Specifically, referring to fig. 2, the substrate 200 is used to provide a process platform for forming the capacitive MEMS microphone structure, and the substrate may be a silicon substrate, a 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-based substrate), or other suitable substrate. In the present embodiment, the substrate 200 is a silicon substrate, but is not limited thereto.

Step S12 is to form a first sacrificial layer on the substrate.

Specifically, referring to fig. 2, a first sacrificial layer 310 is formed on a substrate 200 by using a chemical vapor deposition (cvd) or other suitable methods, and the material of the first sacrificial layer 310 is preferably silicon dioxide, so as to form an insulation with a diaphragm 400 formed later and form a high selective etching ratio, so as to avoid damage to the diaphragm 400. However, the material of the first sacrificial layer is not limited thereto, and may also include, for example, silicon nitride, or a stack of silicon oxide and silicon nitride, or other suitable materials, which may be specifically selected according to the needs, and is not limited herein.

As an example, forming a first sacrificial layer on the substrate may further include patterning the first sacrificial layer to form a first annular through trench S121.

Specifically, referring to fig. 3, the first sacrificial layer 310 is patterned by photolithography, etching or other suitable processes to form a first annular through-slot 311 for subsequently filling the non-conductive material of the backplate to form an anchor region for connecting and supporting the diaphragm and the backplate and for protecting the portion of the support surrounding the air gap when the air gap is subsequently formed.

It should be understood that the anchor region may be formed in other ways as a protection and support structure, and is not limited herein. For example, according to the prior art, instead of separately forming the first annular through-slot 311, the original sacrificial layer is used to define the anchor region, i.e., a part of the sacrificial layer is reserved as the anchor region.

Step S13, a diaphragm is formed on the first sacrificial layer, and the lower surface of the diaphragm is connected with the upper surface of the first sacrificial layer.

Specifically, referring to fig. 4, a diaphragm 400 is formed on the first sacrificial layer 310. As shown, a layer of diaphragm material is formed by physical vapor deposition or other suitable methods, and then patterned by photolithography and etching to obtain the diaphragm 400. The diaphragm 400 is used as a vibration electrode of the MEMS condenser microphone, and the material of the diaphragm 400 may include polysilicon or other metals with elasticity.

As an example, after a diaphragm is formed on the first sacrificial layer, the method further includes step S131: and removing the diaphragm part corresponding to the first annular through groove.

In particular, referring to fig. 4, the anchor region serves as a support structure for the diaphragm, backplate, and substrate, and therefore, the corresponding portion of each layer needs to be perforated to be filled with a corresponding material, such as a backplate non-conductive material, to form the anchor region. The anchor region may be formed in stages or may be formed at one time, which is not limited herein.

It should be noted that the anchor area is an improvement of the support of the MEMS microphone in the prior art, and is substantially equivalent to a part of the support, that is, a protection wall is additionally provided to the support, so that when the air gap and the support are formed by removing the sacrificial layer in the predetermined area, a complete and stable support is formed.

And step S14, forming a second sacrificial layer, wherein the second sacrificial layer is positioned on the first sacrificial layer and covers the diaphragm.

Specifically, referring to fig. 5, a second sacrificial layer 320 is formed, and the second sacrificial layer 320 is located on the first sacrificial layer 310 and covers the diaphragm 400. 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 may include silicon dioxide or other suitable materials. The material of the second sacrificial layer 320 may be the same as or different from the material of the first sacrificial layer 310, and is not limited herein. However, as an optimization, a higher selective etching ratio is provided between the material of the second sacrificial layer 320 and the material of the diaphragm 400, so as to avoid damage to the diaphragm 400 during subsequent etching.

As an example, after step S14, the method further includes: and removing a part of the second sacrificial layer corresponding to the first annular through groove 311 to form an anchor region.

Step S15: and forming a third sacrificial layer which is positioned on the second sacrificial layer and covers the second sacrificial layer.

Specifically, referring to fig. 6, a third sacrificial layer 330 is formed, and the third sacrificial layer 330 is located on the second sacrificial layer 320. 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 may include silicon dioxide or other suitable materials. The material of the third sacrificial layer 330 may be the same as or different from the material of the second sacrificial layer 320, and is not limited herein. However, as an optimization, a higher selective etching ratio is provided between the material of the third sacrificial layer 330 and the material of the diaphragm 400, so as to avoid damage to the diaphragm 400 during subsequent etching.

As an example, after step S15, the method further includes: and removing a part of the third sacrificial layer corresponding to the first annular through groove 311 to form an anchor region.

Step S16: and patterning the third sacrificial layer to obtain a patterned through groove for forming a reinforcing frame for reinforcing the mechanical strength of the back plate.

Specifically, referring to fig. 7, a pattern through groove 331 is formed at a peripheral portion of the third sacrificial layer 330 by processes such as photolithography and etching, the pattern through groove 331 penetrates through the third sacrificial layer 330, wherein the pattern through groove 331 may be in a surrounding grid shape. The shape of the mesh may be circular, oval, honeycomb, square, triangular, polygonal or any shape, and the through grooves 331 are used for subsequent filling of the back plate material to form the reinforcing frame.

As an example, after step S16, the method further includes: further forming a barrier recess in the third sacrificial layer.

Specifically, referring to fig. 8, a blocking recess 332 is further formed in the third sacrificial layer by photolithography, etching, and other processes, wherein the blocking recess 332 may or may not penetrate through the third sacrificial layer, and is not limited herein

Step S17: and 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.

Specifically, referring to fig. 8, a conductive material is deposited by physical vapor deposition or other suitable method to form a backplane conductive layer covering the third sacrificial layer 330, and the relevant portion is removed to obtain the electrode region 600. The covered area of the electrode area 600 corresponds to the sensing area of the capacitive MEMS microphone to form a capacitance structure with the diaphragm 400, that is, the effective capacitance area of the capacitive MEMS microphone, and then the portion of the conductive layer of the backplate corresponding to the barrier recess 332 is removed by photolithography, etching, and other processes, the conductive material in the barrier recess 332 is removed, and a third acoustic hole 610 is formed in the electrode area 600, wherein the conductive layer of the backplate may include polysilicon or other suitable materials.

And step S18, forming a non-conductive layer of the back plate on the third sacrificial layer, and covering the electrode area of the back plate and the filling pattern through grooves to form a non-electrode area of the back plate and a reinforcing frame, wherein the reinforcing frame is connected with the surface of the non-electrode area of the back plate.

Specifically, as shown in fig. 9, a backplane non-conductive layer is formed by first depositing a non-conductive material by cvd, pvd or other suitable methods, the backplane non-conductive layer covers the top and side surfaces of the third sacrificial layer 330, fills the patterned through-slots 331 to form a reinforcing frame 500, and forms a backplane non-electrode area 700, wherein the bottom of the reinforcing frame 500 protrudes into the air gap 900 (see fig. 11). The material of the non-conductive layer of the back plate may be an insulating material or other suitable material. Of course, the non-electrode region 700 of the back plate and the reinforcing frame 500 may be formed separately, or the reinforcing frame 500 may be formed when the non-electrode region 700 of the back plate is formed, which is not limited herein. After the reinforcing frame 500 is formed, which corresponds to the formation of the first sound holes 510, i.e., after the reinforcing frame 500 is formed, the first sound holes 510 are formed after the corresponding sacrificial layers in the reinforcing frame are subsequently removed, i.e., the reinforcing frame 500 has a plurality of first sound holes 510 (see fig. 11).

It should be noted that the non-electrode area 700 of the back plate and the electrode area 600 of the back plate are substantially different layers of the back plate, that is, the conductive layer and the non-conductive layer of the back plate, but in the technical solution of the present application, the area of the non-conductive layer of the back plate is larger than the area of the conductive layer of the back plate, that is, in the range of the air gap, the area of the non-conductive layer of the back plate does not necessarily have the conductive layer of the back plate, that is, the conductive layer of the back plate is located in the middle area of the air gap, and the reinforcing frames 500 are disposed on the surfaces of the non-conductive layers of the back plate corresponding to the two ends of the conductive layer of the back plate, that is, the two ends of the air gap. Of course, the reinforcing frame 500 may extend to the middle region according to different arrangement of the electrode regions 500 of the back plate.

As an example, the backplate non-conductive layer also covers the first annular channel and an area on a different layer corresponding to the first annular channel to form an anchor region.

Specifically, referring to fig. 9, the non-conductive layer of the backplate covers the first annular through groove 311 and the areas of the diaphragm 400, the second sacrificial layer 320, and the third sacrificial layer 330 corresponding to the first annular through groove to form the anchor region 800. That is, when forming the non-conductive layer of the backplate, the non-conductive material is filled in the first annular through groove 311 and the areas of the diaphragm 400, the second sacrificial layer 320, and the third sacrificial layer 330 corresponding to the first annular through groove to form the anchor area 800. Anchor region 800 connects substrate 200, diaphragm 400, and backplate 700, with backplate 700 covering anchor region 800. Of course, the anchor region 800 may be formed by filling in stages or may be formed by filling in one step, which is not limited herein. That is, anchor regions 800 are formed, i.e., holes are cut in each sacrificial layer, posts are formed on the substrate for the mechanical layer, and are used to provide electrical connections. It is noted that, when forming the reinforcement frame 500 and the anchor region 800, a single mask may be used, or different masks may be used to form the reinforcement frame 500 and the anchor region 800.

Referring to fig. 10, in the present embodiment, a second sound hole 710 is further formed in the back plate non-electrode region 700, and the second sound hole 710 on the back plate non-electrode region corresponding to the back plate electrode region 600, and a third sound hole 610 and an air gap in the back plate electrode region 600 are sequentially communicated. The second sound holes 710 of the back plate non-electrode region 700 corresponding to the reinforcing frame 500 are sequentially communicated with the first sound holes 510 of the reinforcing frame 500 and the air gap.

As an example, when the back plate non-conductive layer is formed, the back plate non-conductive material is further filled into the barrier groove 332 to form a barrier 720 connected to the lower surface of the back plate non-electrode region 700, for preventing the diaphragm 400 from being adhered to the electrode region 600 of the back plate.

In this embodiment, referring to fig. 11, the method may further include thinning the substrate 200 by chemical mechanical polishing or other suitable processes, and forming the cavity 210 in the substrate 200 by deep reactive ion etching or other suitable processes, wherein the cavity 210 penetrates the substrate 200 in a vertical direction.

Illustratively, the method further includes removing the first sacrificial layer 310 between the substrate 210 and the diaphragm 400 and inside the anchor region 800.

Finally, in the final structure release process, the second sacrificial layer and the third sacrificial layer in the structure operation region are removed, including the inner sidewalls of the reinforcing frame 500 and the portion surrounded by the anchor region 800, to obtain an air gap 900 between the backplate non-electrode region 700 and the diaphragm 400.

It should be noted that in the embodiment where the anchor region 800 is not formed, the air gap 900 between the backplate non-electrode region 700 and the diaphragm 400 and the support 300 on both sides of the air gap are obtained by removing the second sacrificial layer and the third sacrificial layer in the structural operation region (i.e. the predetermined region). There is no protection of the anchor region 800 and damage to the stent 300 is likely to occur when the associated sacrificial layer is removed.

In this embodiment, the reinforcing frame 500 is formed on one side of the backplate non-electrode region 700, and is located in the air gap 900 between the diaphragm 400 and the backplate non-electrode region 700, and the bottom of the reinforcing frame protrudes from the air gap 900.

As an example, the reinforcing frame 500 is connected with an inner sidewall of the anchor region 800.

Specifically, referring to fig. 12, in the present embodiment, the reinforcing frame 500 is connected to the inner sidewall of the anchor area 800 to better support and strengthen the stability.

It should be noted that, according to the technical solution of the present invention, the anchor region 800 may also be removed, that is, the anchor region 800 is not included, and the anchor region 800 is substantially used to protect the integrity of the support 300 when the second sacrificial layer and the third sacrificial layer of the structure operation region are removed to form the air gap 900 and the support 300 on both sides of the air gap 900. The reinforcing frame may be directly connected to the support frame 300 without the anchor areas 800, as better illustrated in fig. 12 for the connecting lines, or may be integrally formed, and mechanically more stable than when the anchor areas 800 and the reinforcing frame are integrally formed using a sacrificial layer as a support.

In this embodiment, when the reinforcing frame 500 is formed, the first sound holes 510 are formed on the reinforcing frame 500 to allow sound waves to enter, and the first sound holes 510 are circular, oval, honeycomb, square, triangular, polygonal, or any shape.

Specifically, referring to fig. 13, fig. 13 is a top view of a reinforcing frame according to an embodiment. As shown in fig. 11, the back plate material is filled into the patterned through recesses 331 to form a reinforcing frame 500 having first sound holes 510 formed thereon. In this embodiment, the reinforcing frame is disposed around the backplane electrode region 600 as an integral structure, but may be disposed discontinuously around the backplane electrode region 600 in other embodiments.

Therefore, the capacitive MEMS microphone structure manufactured according to the method can disperse stress, improve the mechanical strength of the back plate structure, solve the problems of cracks and the like caused by high stress concentration and is beneficial to improving the performance and the mechanical reliability of the capacitive MEMS microphone by arranging the reinforcing frame 500 on the surface of the non-electrode area of the back plate in the capacitive MEMS microphone structure.

Example 2

The present embodiment provides another method for manufacturing a capacitive MEMS microphone structure, which is different from the method for manufacturing a capacitive MEMS microphone structure provided in embodiment 1 in that steps of forming a reinforcing frame are different, specifically, steps S4, S5, and S6 in embodiment 1 are changed, so that reference is made to embodiment 1 in common, and the present embodiment specifically includes:

step S21, providing a substrate;

step S22, forming a first sacrificial layer on the substrate;

step S23, forming a vibrating diaphragm on the first sacrificial layer, wherein the lower surface of the vibrating diaphragm is connected with the upper surface of the first sacrificial layer;

step S24, forming a second sacrificial layer, wherein the second sacrificial layer is positioned on the first sacrificial layer and covers the diaphragm;

step S25, patterning the second sacrificial layer to obtain a pattern through groove for forming a reinforcing frame for reinforcing the mechanical strength of the backboard;

step S26, forming a third sacrificial layer, wherein the third sacrificial layer covers the second sacrificial layer and the surface of the graphic through groove to be used for lifting the reinforcing frame;

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;

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 pattern through grooves to form the non-electrode area of the back plate and the reinforcing frame, wherein the reinforcing frame is connected with the surface of the non-electrode area of the back plate;

and S29, removing the sacrificial layer in the preset area between the backboard and the vibrating diaphragm to form an air gap between the backboard and the vibrating diaphragm and a bracket between the substrate and the backboard for supporting the vibrating diaphragm and the backboard.

Specifically, the third sacrificial layer in embodiments 1 and 2 is to raise the position of the reinforcing frame, but two different ways are used, in this embodiment, a patterned through groove is obtained by patterning in the second sacrificial layer, the patterned through groove penetrates through the second sacrificial layer, and then a third sacrificial layer is formed, the third sacrificial layer covers the surfaces of the second sacrificial layer and the patterned through groove, that is, a complete third sacrificial layer is laid on the second sacrificial layer, and for the patterned through groove portion, the corresponding third sacrificial layer is recessed and laid on the surface of the patterned through groove, so that the heights of the second sacrificial layer and the surface of the patterned through groove are raised, so that the height of the formed reinforcing frame is raised when the reinforcing frame is formed. The method in embodiment 1 is substantially equivalent to a sacrificial layer, that is, the second sacrificial layer and the third sacrificial layer are one layer, that is, a patterning is performed on one layer, only the through grooves of the patterning do not penetrate through the through grooves, for example, a thickness of one layer is equal to a thickness of the second sacrificial layer and the third sacrificial layer.

It should be noted that this embodiment only describes the reinforcing frame portion, and please refer to embodiment 1 for the step of improving the anchor region additionally formed on the bracket.

Example 3

The present embodiment provides a method for manufacturing a capacitive MEMS microphone structure, which is different from the method for manufacturing a capacitive MEMS microphone structure provided in embodiment 1 in that step S5 is omitted: and forming a third sacrificial layer, wherein the third sacrificial layer is positioned on the second sacrificial layer and covers the diaphragm. That is, all the step processes after step S5 are directly performed on the second sacrificial layer.

Embodiment 1 is a better way, and the position of the reinforcing frame is substantially raised by adding one more sacrificial layer, and of course, the same raising effect can be achieved by multiple layers and increasing the thickness of a single layer, but different materials can be used for multiple layers, so that the related operation is convenient. The specific steps are described with reference to the steps related to example 1.

Example 4

Referring to fig. 12, a schematic cross-sectional structure of a capacitive MEMS microphone structure is shown. As shown in fig. 12, the capacitive MEMS microphone structure includes:

a substrate 200;

a diaphragm 400, the diaphragm 400 being located above the substrate 200;

a back plate positioned above the diaphragm 400, the back plate including an electrode region 600 and a non-electrode region 700;

a support 300, the support 300 being located between the substrate 200 and the non-electrode region 700 of the backplate, for supporting the diaphragm 400 and the backplate;

an air gap 900, wherein the air gap 900 is located between the diaphragm 400, the non-electrode area 700 of the back plate and the bracket 300;

the capacitive MEMS microphone structure further includes a reinforcing frame 500 for reinforcing the mechanical strength of the backplate, wherein the reinforcing frame 500 is located in the air gap 900 and is disposed on a surface of the non-electrode region 700 close to the air gap 900.

As an example, the reinforcing frame 500 is disposed around the electrode region 600.

As an example, the electrode region 600 is provided with a plurality of third sound holes 610.

As an example, the non-electrode region 700 is provided with a plurality of second sound holes 710.

As an example, the reinforcement frame 500 is provided with a plurality of first sound holes 510.

As an example, the third sound hole 610 of the electrode region 600 communicates with the second sound hole 710 and the air gap 900 of the corresponding region of the non-electrode region 700.

As an example, the first sound hole 510 on the reinforcing frame 500 has any one of a circular, oval, honeycomb, square, or triangular shape.

Specifically, the shape of the first sound hole 510 on the reinforcing frame 500 may be circular, oval, honeycomb, square, or triangular, or even any arbitrary shape, which is not limited herein. It should be noted that the first sound hole 510 may be implemented by the patterned through slot 331 mentioned in embodiment 1, or may be implemented by other suitable processes.

As an example, the reinforcing frame 500 has a surrounding grid shape.

Specifically, the reinforcing frame 500 has a surrounding grid shape, that is, the reinforcing frame 500 is disposed around the electrode region 600 at the non-electrode region, wherein the grid shape may be formed by the first sound holes 510 on the reinforcing frame 500.

As an example, a stopper 720 is connected to a side of the non-electrode region 700 close to the diaphragm 400, and a lower surface of the stopper 720 protrudes from a side of the electrode region 600 close to the diaphragm 400.

Illustratively, an anchor region 800 is further included, the anchor region 800 being coupled between the substrate 200 and the backplane and between the bracket 300 and the air gap 900 for protecting the bracket 300 when the air gap 900 is formed.

As an example, the anchor region 800 is the same material as the non-electrode region 700.

Specifically, the anchor area 800 may be drilled separately at each level, subsequently filled with a backing material or other material, or may be drilled at one time. The anchor region is attached to the substrate 200 and is formed of the same material as the backplate 700 for better structural release and complete and stable support 300.

By way of example, the reinforcement frame 500 is coupled to the sidewalls of the anchor region 800 adjacent the air gap 900.

By way of example, the capacitive MEMS microphone structure may be manufactured by the method described in embodiment 1, and may also be manufactured by other suitable methods, which should not unduly limit the scope of the present invention. The detailed description of each structure refers to the foregoing embodiments, and is not repeated herein.

Note that the non-electrode region 700 is a region of the back plate where no conductive electrode is disposed, and the electrode region 600 is a region of the back plate where the conductive electrode is disposed, as shown in fig. 12, that is, a partial surface region of a side of the back plate near the air gap 900.

In summary, the reinforcement frame for reinforcing the mechanical strength of the back plate of the capacitive MEMS microphone structure of the present invention can provide excellent mechanical strength of the entire structure, so that the structure can withstand high-strength external pressure tests, and internal stress concentration is reduced and dispersed, thereby greatly reducing the risk of structural stress exceeding the breakdown strength of the structure and the material itself, and further the structure collapse. And the arrangement of the reinforcing frame can also help the back plate not to increase the nonlinear and asymmetric deformation ratio of the back plate due to the enlargement of the size of the sound hole, so that the acoustic distortion of the capacitive MEMS microphone is caused. In addition, because the arrangement of the reinforcing frame improves the structural rigidity, the thickness of the back plate (the non-conductive layer of the back plate) can be directly reduced to reduce the air acoustic resistance.

Example 5

A difference from embodiment 4 in another structure of a capacitive MEMS microphone according to an embodiment of the present invention is that the position of the reinforcing frame 500 is changed in this embodiment. Specifically, referring to fig. 12, the condenser microphone structure of the present embodiment includes:

a substrate 200;

a diaphragm 400, the diaphragm 400 being located above the substrate 200;

an air gap 900, the air gap 900 being located between the diaphragm 400, the backplate, and the bracket 300;

the capacitive MEMS microphone structure further includes a reinforcing frame 500 for enhancing the mechanical strength of the back plate, and the reinforcing frame is disposed on a surface of the non-electrode area 700 away from the air gap 900.

Specifically, for detailed descriptions of common parts of this embodiment, refer to the foregoing embodiments, which are not repeated herein. It should be noted that in other embodiments, reinforcing frames may be provided on both sides (both sides) of the non-electrode region of the back sheet, i.e., in combination with embodiments 4 and 5.

In other embodiments, the reinforcing frame structure of the present invention may also be used in a single-diaphragm, dual-backplate capacitive MEMS microphone structure to enhance the mechanical strength of the backplate, prevent cracks from occurring in the portion of the backplate that is susceptible to stress concentration, and help to improve the performance and mechanical reliability of the capacitive MEMS microphone.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. 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

1. A capacitive MEMS microphone structure, comprising:

a substrate;

a diaphragm positioned above the substrate;

an air gap between the diaphragm, the backplate, and the bracket;

2. The capacitive MEMS microphone structure of claim 1, wherein the reinforcing frame is disposed on a lower surface of the back plate of the non-electrode region, the lower surface being a surface close to the air gap.

3. The capacitive MEMS microphone structure of claim 1, wherein the stiffener frame is disposed on an upper surface of the backplate of the non-electrode region, the upper surface being a side away from the air gap.

4. A capacitive MEMS microphone structure as claimed in any one of claims 1 to 3, wherein the reinforcing frame is provided with a plurality of first sound holes, a backplate area corresponding to the reinforcing 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 gaps are sequentially communicated.

5. The capacitive MEMS microphone structure of claim 4, wherein the first acoustic aperture has a shape of any one of a circle, an ellipse, a honeycomb, a square, and a triangle or a hexagon.

6. A capacitive MEMS microphone structure as claimed in claim 1 wherein the stiffening frame is disposed around the electrode region.

7. The capacitive MEMS microphone structure of claim 1, wherein the stiffener frame is connected to a sidewall of the standoff near the air gap.

8. A capacitive MEMS microphone structure as claimed in claim 1, further comprising an anchor region connected between the substrate and the backplate and between the standoff and the air gap for protecting the standoff when the air gap is formed.

9. The capacitive MEMS microphone structure of claim 8, wherein the reinforcement frame is connected to a sidewall of the anchor region proximate the air gap.

10. A manufacturing method of a capacitance type MEMS microphone structure is characterized by comprising the following steps:

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

11. The method of fabricating a capacitive MEMS microphone structure as defined by claim 10 wherein the step of patterning the second sacrificial layer to obtain patterned through trenches further comprises: and forming a third sacrificial layer, wherein the third sacrificial layer covers the second sacrificial layer and the surface of the pattern through groove so as to be used for lifting the reinforcing frame.

12. The method of manufacturing a capacitive MEMS microphone structure as claimed in claim 10 or 11, further comprising: and forming an anchor area, wherein the anchor area is connected between the diaphragm and the back plate and is positioned between the support and the air gap so as to protect the support when the air gap is formed.

13. A method of fabricating a capacitive MEMS microphone structure as claimed in claim 12 wherein the stiffening frame is connected to the side wall of the anchor region proximate the air gap.

14. A method of fabricating a capacitive MEMS microphone structure as claimed in claim 10 wherein the stiffener frame is disposed around the electrode regions of the backplate.

15. The method of manufacturing a condenser MEMS microphone structure according to claim 10, further comprising forming a second sound hole in the back plate, the second sound hole being sequentially communicated with the first sound hole of the reinforcing frame and the air gap;

wherein the first acoustic port is formed through the patterned through-groove.