MEMS microphone and manufacturing method thereof

Abstract

The invention discloses an MEMS microphone and a manufacturing method thereof. The MEMS microphone comprises a first microphone structure and a second microphone structure. The first microphone structure comprises a first vibrating diaphragm, a first back plate and a second vibrating diaphragm which are arranged at intervals from bottom to top, a first cavity is formed between the first vibrating diaphragm and the second vibrating diaphragm, and the first back plate is parallel to the first vibrating diaphragm and the second vibrating diaphragm and penetrates through the first cavity; the second microphone structure comprises a third vibrating diaphragm, a second backboard and a fourth vibrating diaphragm which are arranged at intervals from top to bottom, a second cavity is formed between the third vibrating diaphragm and the fourth vibrating diaphragm, and the second backboard is parallel to the third vibrating diaphragm and the fourth vibrating diaphragm and penetrates through the second cavity; and the common vibrating diaphragm is formed by directly bonding a second vibrating diaphragm and a fourth vibrating diaphragm. According to the MEMS microphone and the manufacturing method thereof provided by the invention, a microphone structure with three vibrating diaphragms and double backboards is formed by forming the common vibrating diaphragm, so that the performance of the MEMS microphone is improved, and the process difficulty of manufacturing the MEMS microphone is reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a MEMS microphone and a manufacturing method thereof. Background Art

[0002] Micro-Electro-Mechanical System (MEMS) technology is a high-tech that has developed rapidly in recent years. It uses advanced semiconductor manufacturing processes to achieve mass production of sensors, actuators and other devices. Compared with corresponding traditional devices, MEMS devices have very obvious advantages in size, power consumption, weight and price. In the market, the main application examples of MEMS devices include pressure sensors, accelerometers and silicon microphones.

[0003] A MEMS silicon microphone is an acoustic sensor that converts sound pressure into an analog signal. It includes a MEMS sensor and an ASIC circuit chip. Conventionally, the two can be electrically connected through a wire bonding process and placed in a single package. A MEMS sensor is a variable capacitor with a fixed back plate and a vibrating diaphragm. When sound pressure is applied to the MEMS sensor, the diaphragm can vibrate with the sound, thereby changing the distance between the back plate and the diaphragm, and thus changing the capacitance of the variable capacitor. The capacitance change is determined based on the sound wave parameters, which are converted into an analog signal and input into the ASIC for further analysis and processing.

[0004] In order to further improve the performance of MEMS silicon microphones, the following methods are currently adopted: First, the sensitivity and SNR are improved by increasing the size of the device, but this runs counter to the miniaturization direction of the device and is not conducive to the improvement of device integration; second, by designing a new silicon microphone structure model, differential signal output is achieved, thereby reducing noise to achieve high signal-to-noise ratio performance, but the new structure product process is complex and difficult to manufacture, which is not conducive to large-scale production and cost reduction of the product. Summary of the invention

[0005] A series of simplified concepts are introduced in the Summary of the Invention, which will be further described in detail in the Detailed Description of the Invention. The Summary of the Invention does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0006] The present invention provides a MEMS microphone, comprising a first microphone structure and a second microphone structure;

[0007] The first microphone structure includes a first diaphragm, a first back plate, and a second diaphragm spaced from bottom to top, wherein a first cavity is formed between the first diaphragm and the second diaphragm, and the first back plate is arranged in parallel with the first diaphragm and the second diaphragm and passes through the first cavity;

[0008] The second microphone structure comprises a third diaphragm, a second back plate and a fourth diaphragm spaced from top to bottom, wherein a second cavity is formed between the third diaphragm and the fourth diaphragm, and the second back plate is arranged in parallel with the third diaphragm and the fourth diaphragm and passes through the second cavity;

[0009] A common diaphragm is formed by directly bonding the second diaphragm and the fourth diaphragm.

[0010] Further, the first diaphragm, the first back plate, the common diaphragm, the second back plate and the third diaphragm respectively serve as a first electrode, a second electrode, a third electrode, a fourth electrode and a fifth electrode of the MEMS microphone.

[0011] Furthermore, a plurality of first support columns are provided in the first cavity, and both ends of the plurality of first support columns are respectively connected to the first diaphragm and the second diaphragm; a plurality of second support columns are provided in the second cavity, and both ends of the plurality of second support columns are respectively connected to the third diaphragm and the fourth diaphragm.

[0012] Furthermore, the plurality of first supporting columns are arranged perpendicularly to the first diaphragm and the second diaphragm and pass through the first cavity; the plurality of second supporting columns are arranged perpendicularly to the third diaphragm and the fourth diaphragm and pass through the second cavity.

[0013] Furthermore, a plurality of first sound holes are formed in the first back plate, and the plurality of first support columns pass through the first sound holes; a plurality of second sound holes are formed on the second back plate, and the plurality of second support columns pass through the second sound holes.

[0014] Furthermore, a first supporting portion is formed between the first diaphragm and the first back plate, a second supporting portion is formed between the second diaphragm and the first back plate, and the first diaphragm, the second diaphragm, the first supporting portion and the second supporting portion surround to form the first cavity; a third supporting portion is formed between the third diaphragm and the second back plate, a fourth supporting portion is formed between the fourth diaphragm and the second back plate, and the third diaphragm, the fourth diaphragm, the third supporting portion and the fourth supporting portion surround to form the second cavity.

[0015] Furthermore, the first microphone structure is formed on a first substrate, and a first isolation layer is formed between the first substrate and the first diaphragm.

[0016] The present invention also provides a MEMS microphone and a manufacturing method thereof, comprising:

[0017] A first microphone structure and a second microphone structure are obtained; wherein the first microphone structure includes a first diaphragm, a first back plate, and a second diaphragm spaced from bottom to top, wherein a first cavity is formed between the first diaphragm and the second diaphragm, and the first back plate is arranged in parallel with the first diaphragm and the second diaphragm and passes through the first cavity; the second microphone structure includes a second and a third diaphragm, a second back plate, and a fourth diaphragm spaced from top to bottom, wherein a second cavity is formed between the third diaphragm and the fourth diaphragm, and the second back plate is arranged in parallel with the third diaphragm and the fourth diaphragm and passes through the second cavity;

[0018] The second diaphragm is directly bonded to the fourth diaphragm to form a common diaphragm.

[0019] Further, the step of obtaining the first microphone structure and the second microphone structure includes:

[0020] Fabricating one or more of the first microphone structures on a first substrate; and,

[0021] One or more second microphone structures are fabricated on a second substrate.

[0022] Further, the step of manufacturing one or more of the first microphone structures on the first substrate includes:

[0023] forming a first diaphragm on the first substrate;

[0024] forming a first supporting layer on the first diaphragm;

[0025] forming a first backplane layer on the first supporting layer, patterning the first backplane layer to form the first backplane, wherein a plurality of first acoustic holes are formed in the first backplane;

[0026] forming a second supporting layer on the first backplane;

[0027] Etching the first supporting layer and the second supporting layer to form a plurality of first through holes penetrating the first supporting layer and the second supporting layer, wherein the plurality of first through holes pass through the plurality of first acoustic holes;

[0028] filling the plurality of first through holes to form a plurality of first support pillars;

[0029] forming a second diaphragm layer on the second supporting layer, patterning the second diaphragm layer to form the second diaphragm, wherein a plurality of diaphragm holes are formed on the second diaphragm;

[0030] The first supporting layer and the second supporting layer are etched to form the first cavity between the first diaphragm and the second diaphragm, the remaining portion of the first supporting layer forms a first supporting portion, and the remaining portion of the second supporting layer forms a second supporting portion.

[0031] Further, the step of manufacturing one or more of the second microphone structures on the second substrate includes:

[0032] forming a third diaphragm on the second substrate;

[0033] forming a third supporting layer on the third diaphragm;

[0034] forming a second backplane layer on the third supporting layer, patterning the second backplane layer to form the second backplane, wherein the second backplane has a plurality of second acoustic holes formed therein;

[0035] forming a fourth supporting layer on the second backplane;

[0036] Etching the third supporting layer and the fourth supporting layer to form a plurality of second through holes penetrating the third supporting layer and the fourth supporting layer, wherein the plurality of second through holes pass through the plurality of second acoustic holes;

[0037] filling the plurality of second through holes to form a plurality of second support pillars;

[0038] forming a fourth diaphragm layer on the fourth supporting layer, patterning the fourth diaphragm layer to form the fourth diaphragm, wherein a plurality of diaphragm holes are formed on the fourth diaphragm;

[0039] The third supporting layer and the fourth supporting layer are etched to form the second cavity between the third diaphragm and the fourth diaphragm, the remaining portion of the third supporting layer forms a third supporting portion, and the remaining portion of the fourth supporting layer forms a fourth supporting portion.

[0040] Furthermore, after the second diaphragm and the fourth diaphragm are directly bonded to form a common diaphragm, the method further includes the following steps:

[0041] removing the second substrate to expose the third diaphragm;

[0042] The first substrate is etched to expose a region of the first diaphragm corresponding to the first cavity.

[0043] According to the MEMS microphone and the manufacturing method thereof provided by the present invention, a first microphone structure and a second microphone structure with dual diaphragms and a single backplate are first manufactured, and then the diaphragm of the first microphone structure and the diaphragm of the second microphone structure are directly bonded to form a common diaphragm to form a microphone structure with three diaphragms and a double backplate, thereby improving the performance of the MEMS microphone and reducing the process difficulty of manufacturing the MEMS microphone. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The following drawings of the present invention are used to understand the present invention as part of the present invention. The embodiments of the present invention are shown in the drawings and the description thereof is used to explain the principle of the present invention.

[0045] In the attached figure:

[0046] Figure 1 A schematic diagram of the structure of a MEMS microphone according to an embodiment of the present invention;

[0047] Figure 2 is a flow chart of a method for manufacturing a MEMS microphone according to an embodiment of the present invention;

[0048] Figure 3 is a flow chart of a method for manufacturing a first microphone structure according to an embodiment of the present invention;

[0049] Figures 4A-4E is a cross-sectional schematic diagram of a structure obtained by sequentially implementing the manufacturing method of the first microphone structure according to an embodiment of the present invention;

[0050] Figure 5 FIG. 4 is a schematic cross-sectional view of a structure obtained by bonding a first microphone structure to a second microphone structure according to an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0052] It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0053] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to or coupled to other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to or directly coupled to other elements or layers, there may be no intervening elements or layers. It should be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part.

[0054] Spatially relative terms such as "under," "below," "below," "under," "above," "above," etc., may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, the spatially relative terms are intended to include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "on" the other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0055] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0056] In order to fully understand the present invention, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0057] In view of the above problems, the present invention provides a MEMS microphone, such as Figure 1 As shown, it includes a first microphone structure 110 and a second microphone structure 120;

[0058] The first microphone structure 110 includes a first diaphragm 111, a first back plate 112, and a second diaphragm 113 which are spaced from bottom to top, wherein a first cavity 114 is formed between the first diaphragm 111 and the second diaphragm 113, and the first back plate 112 is arranged parallel to the first diaphragm 111 and the second diaphragm 113 and passes through the first cavity 114;

[0059] The second microphone structure 120 includes a third diaphragm 121, a second back plate 122 and a fourth diaphragm 123 which are spaced apart from top to bottom, wherein a second cavity 124 is formed between the third diaphragm 121 and the fourth diaphragm 123, and the second back plate 122 is arranged in parallel with the third diaphragm 121 and the fourth diaphragm 123 and passes through the second cavity 124;

[0060] The common diaphragm 130 is formed by bonding the second diaphragm 113 and the fourth diaphragm 123 .

[0061] Exemplarily, a plurality of first support columns 115 are further disposed in the first cavity 114, and both ends of the plurality of first support columns 115 are respectively connected to the first diaphragm 111 and the second diaphragm 113. In one embodiment, the plurality of first support columns 115 are arranged perpendicular to the first diaphragm 111 and the second diaphragm 113 and pass through the first cavity 114.

[0062] Exemplarily, a plurality of second support columns 125 are further disposed in the second cavity 124, and both ends of the plurality of second support columns 125 are respectively connected to the third diaphragm 121 and the fourth diaphragm 123. In one embodiment, the plurality of second support columns 125 are arranged perpendicular to the third diaphragm 121 and the fourth diaphragm 123 and pass through the second cavity 124.

[0063] In one embodiment, a plurality of first sound holes are formed in the first back plate 112, and the plurality of first support columns 115 pass through the first sound holes, and the plurality of first support columns 115 do not contact the first back plate 112. A plurality of second sound holes are formed on the second back plate 122, and the plurality of second support columns 125 pass through the second sound holes, and the plurality of second support columns 125 do not contact the second back plate 122.

[0064] In one embodiment, a first supporting portion 116 is formed between the first diaphragm 111 and the first back plate 112 , and a second supporting portion 117 is formed between the second diaphragm 113 and the first back plate 112 . The first diaphragm 111 , the second diaphragm 113 , the first supporting portion 116 , and the second supporting portion 117 surround to form the first cavity 114 .

[0065] In one embodiment, a third supporting portion 126 is formed between the third diaphragm 121 and the second back plate 122, and a fourth supporting portion 127 is formed between the fourth diaphragm 123 and the second back plate 122. The third diaphragm 121, the fourth diaphragm 123, the third supporting portion 126 and the fourth supporting portion 127 surround to form the second cavity 124.

[0066] In one embodiment, the first microphone structure 110 is formed on a first substrate 101, and a first isolation layer 102 is formed between the first substrate 101 and the first diaphragm. The first substrate 101 and the first isolation layer 102 are only arranged in the area corresponding to the first supporting portion 116 and the second supporting portion 117, while the area corresponding to the first cavity 114 does not have the first substrate 101 and the first isolation layer 102.

[0067] In one embodiment, the pressure in the first cavity 114 and the second cavity 124 can be set as needed, for example, to a low pressure state or a vacuum state.

[0068] Exemplarily, the first diaphragm 111, the first back plate 112, the common diaphragm 130, the second back plate 122 and the third diaphragm 121 are respectively used as the first electrode P1, the second electrode P2, the third electrode P3, the fourth electrode P4 and the fifth electrode P5 of the MEMS microphone. When P1 / P3 / P5 are electrically connected, and P2 / P4 are electrically connected, a single-ended ultra-large capacitance output can be formed, which increases the capacitance area and effectively improves the sensitivity; P1 / P2 / P3 can output differential capacitance signals, and P3 / P4 / P5 can also form differential capacitance signals. The two differential capacitance signals are then superimposed, which can effectively improve the signal-to-noise ratio.

[0069] In the present invention, the common diaphragm 130 is formed by directly bonding the second diaphragm 113 and the fourth diaphragm 123. The first microphone structure 110 and the second microphone structure 120 of the dual-diaphragm single-backplate are face-to-face bonded to form a three-diaphragm / dual-backplate capacitive MEMS microphone structure with high sensitivity, small size, high signal-to-noise ratio (SNR) and excellent performance.

[0070] The present invention also provides a MEMS microphone and a method for manufacturing the same. Figure 2 As shown, the following steps are included:

[0071] Step S210: Acquire a first microphone structure and a second microphone structure; wherein the first microphone structure includes a first diaphragm, a first back plate, and a second diaphragm spaced from bottom to top, wherein a first cavity is formed between the first diaphragm and the second diaphragm, and the first back plate is arranged in parallel with the first diaphragm and the second diaphragm and passes through the first cavity; the second microphone structure includes a third diaphragm, a second back plate, and a fourth diaphragm spaced from top to bottom, wherein a second cavity is formed between the third diaphragm and the fourth diaphragm, and the second back plate is arranged in parallel with the third diaphragm and the fourth diaphragm and passes through the second cavity;

[0072] Step S220: directly bonding the second diaphragm and the fourth diaphragm to form a common diaphragm.

[0073] Exemplarily, the first microphone structure in step S210 is formed on a first substrate, and simultaneously one or more first microphone structures may be manufactured on the first substrate.

[0074] Exemplarily, the first substrate may be any suitable semiconductor substrate, such as a silicon substrate, and may also be at least one of the following materials: Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP or other III / V compound semiconductors, including multilayer structures composed of these semiconductor materials, or silicon on insulator (SOI), stacked silicon on insulator (SSOI), stacked silicon germanium on insulator (S-SiGeOI), silicon germanium on insulator (SiGeOI) and germanium on insulator (GeOI), or may also be double-sided polished silicon wafers (DSP), or may be ceramic substrates such as aluminum oxide, quartz or glass substrates, etc. In one embodiment, the first substrate is selected to have a crystal orientation of <100> of single crystal silicon.

[0075] Exemplarily, the distance between the first diaphragm and the second diaphragm and the distance between the third diaphragm and the fourth diaphragm may be the same or different.

[0076] In one embodiment, a first isolation layer is further formed on the first substrate. Specifically, the first isolation layer can be formed by a physical vapor deposition process or a chemical vapor deposition process. The first isolation layer includes but is not limited to a silicon oxide layer. The thickness of the first isolation layer ranges from 0.5 μm to 2 μm.

[0077] Reference Figure 3The step of manufacturing one or more of the first microphone structures on the first substrate comprises:

[0078] Step S310: forming a first diaphragm on the first substrate;

[0079] Step S320: forming a first supporting layer on the first diaphragm;

[0080] Step S330: forming a first backplane layer on the first supporting layer, and patterning the first backplane layer to form the first backplane, wherein a plurality of first acoustic holes are formed in the first backplane;

[0081] Step S340: forming a second supporting layer on the first backplane;

[0082] Step S350: etching the first supporting layer and the second supporting layer to form a plurality of first through holes penetrating the first supporting layer and the second supporting layer, wherein the plurality of first through holes pass through the plurality of first acoustic holes;

[0083] Step S360: filling the plurality of first through holes to form a plurality of first support columns;

[0084] Step S370: forming a second diaphragm layer on the second supporting layer, and patterning the second diaphragm layer to form the second diaphragm, wherein a plurality of diaphragm holes are formed on the second diaphragm;

[0085] Step S380: etching the first supporting layer and the second supporting layer to form the first cavity between the first diaphragm and the second diaphragm, with the remaining portion of the first supporting layer forming a first supporting portion and the remaining portion of the second supporting layer forming a second supporting portion.

[0086] Below, reference FIG. 4A to FIG. 4E The manufacturing method of the first microphone structure of the present invention is described in detail, wherein: FIG. 4A to FIG. 4E FIG. 1 is a schematic cross-sectional view of a structure obtained by sequentially implementing the manufacturing method of the first microphone structure according to an embodiment of the present invention.

[0087] First, execute step S310, such as Figure 4A As shown, a first diaphragm 411 is formed on the first substrate 401 .

[0088] In one embodiment, a layer of diaphragm material is deposited on the surface of the first isolation layer 402 by conventional semiconductor process methods to form a first diaphragm 411, which covers the first isolation layer 402. The material of the first diaphragm 411 includes but is not limited to doped polysilicon. The thickness of the first diaphragm 411 ranges from 0.2um to 1um.

[0089] In one embodiment, a conventional semiconductor process method for forming the first isolation layer 402 can be selected as needed, such as one of low pressure chemical vapor deposition (LPCVD), laser ablation deposition (LAD), and selective epitaxial growth (SEG) formed by chemical vapor deposition (CVD), physical vapor deposition (PVD), or atomic layer deposition (ALD), or one of low temperature chemical vapor deposition (LTCVD), rapid thermal chemical vapor deposition (RTCVD), and plasma enhanced chemical vapor deposition (PECVD). Here, the low pressure chemical vapor deposition (LPCVD) method is preferred.

[0090] Next, execute step S320, such as Figure 4B As shown, a first supporting layer 416 ′ is formed on the first diaphragm 411 .

[0091] In one embodiment, the first support layer 416' is formed on the first diaphragm 411 by conventional semiconductor process methods such as LPCVD or PECVD, and the first support layer 416' covers the first diaphragm 411. The material of the first support layer 416' includes but is not limited to silicon dioxide. The thickness of the first support layer 416' ranges from 1um to 3um.

[0092] Next, execute step S330, such as Figure 4B As shown, a first backplane layer is formed on the first supporting layer 416 ′, and the first backplane layer is patterned to form the first backplane 412 , in which a plurality of first acoustic holes are formed.

[0093] In one embodiment, a first backplane layer is formed on the surface of the first support layer 416' by conventional semiconductor process methods such as LPCVD or PECVD. The material of the first backplane layer includes but is not limited to doped polysilicon. Optionally, the first backplane layer can be a single-layer doped polysilicon layer, or a combination of a doped polysilicon layer and a passivation layer. Among them, the material of the passivation layer includes but is not limited to silicon nitride, silicon carbide, silicon oxynitride, etc. The first backplane layer can be patterned by a photolithography process to form the first backplane 412, which will not be repeated here. The thickness of the first backplane 412 ranges from 0.5um to 2um.

[0094] Next, execute step S340, such as Figure 4C As shown, a second supporting layer 417 ′ is formed on the first back plate 412 .

[0095] In one embodiment, the second support layer 417' is formed on the first back plate 412 by conventional semiconductor process methods such as LPCVD or PECVD, and the second support layer 417' covers the first back plate 412. The material of the second support layer 417' includes but is not limited to silicon dioxide. The thickness of the second support layer 417' ranges from 1um to 3um.

[0096] Next, execute step S350, such as Figure 4C As shown, the first supporting layer 416' and the second supporting layer 417' are etched to form a plurality of first through holes 415' penetrating the first supporting layer 416' and the second supporting layer 417', wherein the plurality of first through holes 415' pass through the plurality of first acoustic holes.

[0097] In one embodiment, the first support layer 416' and the second support layer 417' may be patterned by a photolithography process to form a plurality of first through holes 415' penetrating the first support layer 416' and the second support layer 417' until the first diaphragm 411 is exposed. It should be noted that the plurality of first through holes 415' pass through the plurality of first sound holes of the first back plate 412, so the first through holes 415' are not in contact with the first back plate 412.

[0098] Next, execute step S360, such as Figure 4D As shown, the plurality of first through holes 415 ′ are filled to form a plurality of first supporting columns 415 .

[0099] In one embodiment, a layer of material is deposited by conventional semiconductor processes such as LPCVD, and the plurality of first through holes 415' is completely filled, and then the surface material is removed by CMP process, the cut-off layer is the second support layer 417', and the remaining material is filled in the plurality of first through holes 415' to form a plurality of first support pillars (Pillar) 415. The first support pillars 415 can be conductive materials or non-conductive materials. The diameter size range of the first support pillars 415 is Φ0.5um to 3um.

[0100] Next, execute step S370, such as Figure 4D As shown, a second diaphragm layer is formed on the second supporting layer 417 ′, and the second diaphragm layer is patterned to form the second diaphragm 413 . A plurality of diaphragm holes are formed on the second diaphragm 413 .

[0101] In one embodiment, a layer of diaphragm material (i.e., second diaphragm layer) is deposited on the second support layer 417' and the first support column 415 by conventional semiconductor process methods such as LPCVD, and then the diaphragm material is patterned by photolithography to form a second diaphragm 413 having a plurality of diaphragm holes. The material of the second diaphragm 413 includes but is not limited to doped polysilicon. The thickness of the second diaphragm 413 ranges from 0.2um to 0.5um.

[0102] In one embodiment, the second diaphragm layer is patterned by a photolithography process. Specifically, a photoresist layer (not shown) having a diaphragm hole pattern is formed on the second diaphragm layer. The photoresist layer having the diaphragm hole pattern can be a photoresist formed by a spin coating process, and then formed by processes such as exposure, development, and cleaning. Then, the second diaphragm layer is etched using the photoresist layer having the diaphragm hole pattern as a mask, thereby forming a second diaphragm 413 having a plurality of diaphragm holes.

[0103] It should be noted that after forming the second diaphragm 413, it also includes the steps of depositing a layer of oxide film on the surface of the second diaphragm 413 by conventional semiconductor process methods such as LPCVD or PECVD, and grinding it to the second diaphragm 413 by CMP process to obtain a bonding surface with roughness that meets the requirements.

[0104] Next, execute step S380, such as Figure 4E As shown, the first supporting layer 416 ′ and the second supporting layer 417 ′ are etched to form the first cavity 414 between the first diaphragm 411 and the second diaphragm 413 , and the remaining portion of the first supporting layer forms the first supporting portion 416 , and the remaining portion of the second supporting layer forms the second supporting portion 417 .

[0105] In one embodiment, wet etching is used to form the first cavity 414. Specifically, the support layer is released by HF or BOE solution or Vapor HF, etc. Figure 4E The structure shown.

[0106] Exemplarily, the second microphone structure in step S210 is formed on a second substrate, and simultaneously one or more second microphone structures may be manufactured on the second substrate.

[0107] Exemplarily, the steps of manufacturing one or more second microphone structures on the second substrate include: forming a third diaphragm on the second substrate; forming a third supporting layer on the third diaphragm; forming a second backplate layer on the third supporting layer, patterning the second backplate layer to form the second backplate, and forming a plurality of second sound holes in the second backplate; forming a fourth supporting layer on the second backplate; etching the third supporting layer and the fourth supporting layer to form a plurality of second through holes penetrating the third supporting layer and the fourth supporting layer, and the plurality of second through holes pass through the plurality of second sound holes; filling the plurality of second through holes to form a plurality of second supporting columns; forming a fourth diaphragm layer on the fourth supporting layer, patterning the fourth diaphragm layer to form the fourth diaphragm, and forming a plurality of diaphragm holes on the fourth diaphragm; etching the third supporting layer and the fourth supporting layer to form the second cavity between the third diaphragm and the fourth diaphragm, and the remaining portion of the third supporting layer forms the third supporting portion, and the remaining portion of the fourth supporting layer forms the fourth supporting portion.

[0108] The specific process may refer to the steps of manufacturing one or more of the first microphone structures on the first substrate, which will not be described in detail here.

[0109] Next, step S220 is performed to directly bond the second diaphragm 413 of the first microphone structure obtained through the above steps to the fourth diaphragm 423 of the second microphone structure obtained to form a common diaphragm 430. Figure 5 shown.

[0110] In one embodiment, the pressure in the first cavity 414 and the second cavity can be set as needed, for example, to a low pressure state or a vacuum state.

[0111] After step S220, the method further includes the steps of removing the second substrate and the second isolation layer by CMP or the like until the third diaphragm 421 is exposed; and thinning the first substrate by CMP or the like, and then performing pad wiring by TSV process, and etching the first substrate and the first isolation layer by back etching process to expose the first diaphragm corresponding to the first cavity. Figure 1 The MEMS microphone device structure shown.

[0112] Exemplarily, the first diaphragm 111, the first back plate 112, the common diaphragm 130, the second back plate 122 and the third diaphragm 121 are respectively used as the first electrode P1, the second electrode P2, the third electrode P3, the fourth electrode P4 and the fifth electrode P5 of the MEMS microphone. When P1 / P3 / P5 are electrically connected, and P2 / P4 are electrically connected, a single-ended ultra-large capacitance output can be formed, which increases the capacitance area and effectively improves the sensitivity; P1 / P2 / P3 can output differential capacitance signals, and P3 / P4 / P5 can also form differential capacitance signals. The two differential capacitance signals are then superimposed, which can effectively improve the signal-to-noise ratio.

[0113] The key steps of the method for manufacturing the semiconductor device of the present invention have been introduced so far. A plurality of other process steps may be required for the complete device preparation, which will not be described one by one here.

[0114] It is worth mentioning that the order of the above steps is only an example. Under the premise of no conflict, the order of the above steps can also be swapped or performed alternately.

[0115] According to the MEMS microphone and the manufacturing method thereof provided by the present invention, a first microphone structure and a second microphone structure with dual diaphragms and a single backplate are first manufactured, and then the diaphragm of the first microphone structure and the diaphragm of the second microphone structure are directly bonded to form a common diaphragm to form a microphone structure with three diaphragms and a double backplate, thereby improving the performance of the MEMS microphone and reducing the process difficulty of manufacturing the MEMS microphone.

[0116] The present invention has been described by the above embodiments, but it should be understood that the above embodiments are only for the purpose of example and description, and are not intended to limit the present invention to the scope of the described embodiments. In addition, it can be understood by those skilled in the art that the present invention is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the scope of the protection claimed by the present invention. The protection scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A MEMS microphone, characterized in that: including a first microphone structure and a second microphone structure; The first microphone structure includes a first diaphragm, a first back plate, and a second diaphragm spaced from bottom to top, wherein a first cavity is formed between the first diaphragm and the second diaphragm, and the first back plate is arranged in parallel with the first diaphragm and the second diaphragm and passes through the first cavity; The second microphone structure comprises a third diaphragm, a second back plate and a fourth diaphragm spaced from top to bottom, wherein a second cavity is formed between the third diaphragm and the fourth diaphragm, and the second back plate is arranged in parallel with the third diaphragm and the fourth diaphragm and passes through the second cavity; A common diaphragm is formed by directly bonding the second diaphragm and the fourth diaphragm.

2. The MEMS microphone according to claim 1, wherein: The first diaphragm, the first back plate, the common diaphragm, the second back plate and the third diaphragm respectively serve as a first electrode, a second electrode, a third electrode, a fourth electrode and a fifth electrode of the MEMS microphone.

3. The MEMS microphone according to claim 1, wherein: A plurality of first support columns are also provided in the first cavity, and both ends of the plurality of first support columns are respectively connected to the first diaphragm and the second diaphragm; a plurality of second support columns are also provided in the second cavity, and both ends of the plurality of second support columns are respectively connected to the third diaphragm and the fourth diaphragm.

4. The MEMS microphone according to claim 3, characterized in that The plurality of first supporting columns are arranged perpendicularly to the first diaphragm and the second diaphragm and pass through the first cavity; the plurality of second supporting columns are arranged perpendicularly to the third diaphragm and the fourth diaphragm and pass through the second cavity.

5. The MEMS microphone according to claim 3, characterized in that: A plurality of first sound holes are formed in the first back plate, and the plurality of first support columns pass through the first sound holes; a plurality of second sound holes are formed on the second back plate, and the plurality of second support columns pass through the second sound holes.

6. The MEMS microphone according to claim 1, wherein: A first supporting portion is formed between the first diaphragm and the first back plate, a second supporting portion is formed between the second diaphragm and the first back plate, and the first diaphragm, the second diaphragm, the first supporting portion and the second supporting portion surround to form the first cavity; a third supporting portion is formed between the third diaphragm and the second back plate, a fourth supporting portion is formed between the fourth diaphragm and the second back plate, and the third diaphragm, the fourth diaphragm, the third supporting portion and the fourth supporting portion surround to form the second cavity.

7. The MEMS microphone according to claim 1, wherein: The first microphone structure is formed on a first substrate, and a first isolation layer is formed between the first substrate and the first diaphragm.

8. A MEMS microphone and a method for manufacturing the same, characterized in that: include: A first microphone structure and a second microphone structure are obtained; wherein the first microphone structure includes a first diaphragm, a first back plate, and a second diaphragm spaced from bottom to top, wherein a first cavity is formed between the first diaphragm and the second diaphragm, and the first back plate is arranged in parallel with the first diaphragm and the second diaphragm and passes through the first cavity; the second microphone structure includes a second and a third diaphragm, a second back plate, and a fourth diaphragm spaced from top to bottom, wherein a second cavity is formed between the third diaphragm and the fourth diaphragm, and the second back plate is arranged in parallel with the third diaphragm and the fourth diaphragm and passes through the second cavity; The second diaphragm is directly bonded to the fourth diaphragm to form a common diaphragm.

9. The manufacturing method according to claim 8, characterized in that: The step of acquiring the first microphone structure and the second microphone structure comprises: Fabricating one or more of the first microphone structures on a first substrate; and, One or more second microphone structures are fabricated on a second substrate.

10. The manufacturing method according to claim 9, characterized in that: The step of manufacturing one or more of the first microphone structures on the first substrate comprises: forming a first diaphragm on the first substrate; forming a first supporting layer on the first diaphragm; forming a first backplane layer on the first supporting layer, patterning the first backplane layer to form the first backplane, wherein a plurality of first acoustic holes are formed in the first backplane; forming a second supporting layer on the first backplane; Etching the first supporting layer and the second supporting layer to form a plurality of first through holes penetrating the first supporting layer and the second supporting layer, wherein the plurality of first through holes pass through the plurality of first acoustic holes; filling the plurality of first through holes to form a plurality of first support pillars; forming a second diaphragm layer on the second supporting layer, patterning the second diaphragm layer to form the second diaphragm, wherein a plurality of diaphragm holes are formed on the second diaphragm; The first supporting layer and the second supporting layer are etched to form the first cavity between the first diaphragm and the second diaphragm, the remaining portion of the first supporting layer forms a first supporting portion, and the remaining portion of the second supporting layer forms a second supporting portion.

11. The manufacturing method according to claim 9, characterized in that: The step of manufacturing one or more of the second microphone structures on the second substrate comprises: forming a third diaphragm on the second substrate; forming a third supporting layer on the third diaphragm; forming a second backplane layer on the third supporting layer, patterning the second backplane layer to form the second backplane, wherein the second backplane has a plurality of second acoustic holes formed therein; forming a fourth supporting layer on the second backplane; Etching the third supporting layer and the fourth supporting layer to form a plurality of second through holes penetrating the third supporting layer and the fourth supporting layer, wherein the plurality of second through holes pass through the plurality of second acoustic holes; filling the plurality of second through holes to form a plurality of second support pillars; forming a fourth diaphragm layer on the fourth supporting layer, patterning the fourth diaphragm layer to form the fourth diaphragm, wherein a plurality of diaphragm holes are formed on the fourth diaphragm; The third supporting layer and the fourth supporting layer are etched to form the second cavity between the third diaphragm and the fourth diaphragm, the remaining portion of the third supporting layer forms a third supporting portion, and the remaining portion of the fourth supporting layer forms a fourth supporting portion.

12. The manufacturing method according to claim 10, characterized in that: After directly bonding the second diaphragm and the fourth diaphragm to form a common diaphragm, the method further includes the following steps: removing the second substrate to expose the third diaphragm; The first substrate is etched to expose a region of the first diaphragm corresponding to the first cavity.

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