MEMS microphone and method of manufacturing the same

Abstract

The application discloses a MEMS microphone and a manufacturing method thereof. The MEMS microphone comprises a substrate, a first supporting layer, a diaphragm layer, a second supporting layer and a back plate layer. The substrate has a first cavity in the middle part. The first supporting layer is located on the substrate and has a second cavity in the middle part. The diaphragm layer is located on the supporting layer and comprises a movable part. The thickness of the middle part of the movable part is smaller than that of the edge part of the diaphragm layer. The second supporting layer is located on the diaphragm layer and has a third cavity in the middle part. The movable part is located between the second cavity and the third cavity. The back plate layer is located on the second supporting layer. The MEMS microphone has good sensitivity and mechanical performance.

Description

TECHNICAL FIELD

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

[0002] A MEMS (Micro Electro Mechanical System) microphone mainly comprises a diaphragm and a back plate, and has a gap between the diaphragm and the back plate. When sound acts on the diaphragm, the diaphragm will vibrate and deform, the gap between the diaphragm and the back plate will change, and the capacitance value between the diaphragm and the back plate will change, so that the change of the capacitance value can be converted into an electrical signal output.

[0003] The sensitivity of the MEMS microphone is negatively related to the thickness of the diaphragm, that is, under the condition that other conditions remain unchanged, the thinner the thickness of the diaphragm, the higher the sensitivity of the MEMS microphone. At present, the diaphragm of the MEMS microphone is usually a layer with uniform thickness arranged on a support layer with a cavity. In order to achieve high sensitivity, the thickness of the diaphragm is usually set to be very small, which reduces the mechanical properties (such as mechanical strength, etc.) of the diaphragm. Under the condition of large vibration and large sound pressure, the diaphragm is easy to break, causing the microphone to fail.

[0004] Therefore, improvements need to be made to at least partially solve the above problems. SUMMARY

[0005] A series of simplified concepts are introduced in the summary section, which will be further described in detail in the specific embodiment section. The summary section of the present application does not mean to attempt to limit the key features and necessary technical features of the claimed technical solution, and even less to determine the protection scope of the claimed technical solution.

[0006] In order to at least partially solve the above problems, according to the first aspect of the present application, a MEMS microphone is provided, comprising:

[0007] a substrate, the substrate having a first cavity in the middle part;

[0008] a first support layer located on the substrate, the first support layer having a second cavity in the middle part;

[0009] a diaphragm layer located on the support layer, the diaphragm layer comprising a movable part, the thickness of the middle part of the movable part being smaller than the thickness of the edge part of the movable part;

[0010] a second support layer located on the diaphragm layer, the second support layer having a third cavity in the middle part, wherein the middle part of the movable part is located between the second cavity and the third cavity;

[0011] a back plate layer, the back plate layer being on the second support layer.

[0012] Exemplarily, the middle portion of the movable part has a groove, the groove being on a side of the movable part facing the substrate and / or on a side of the movable part facing the back plate layer.

[0013] Exemplarily, the diaphragm layer further comprises a support part;

[0014] The support part is annular, extends from an edge portion of the movable part to the substrate and is in the second cavity, and an outer sidewall surface of the support part is attached to an inner sidewall surface of the first support layer.

[0015] Exemplarily, a side of the support part facing the substrate is attached to the substrate.

[0016] Exemplarily, a material of the substrate comprises silicon.

[0017] A material of the first support layer comprises silicon oxide.

[0018] A material of the diaphragm layer comprises single crystal silicon or polycrystalline silicon.

[0019] A material of the second support layer comprises silicon oxide.

[0020] A material of the back plate layer comprises polycrystalline silicon.

[0021] According to a second aspect of the present application, a manufacturing method of a MEMS microphone is provided, which comprises:

[0022] providing a substrate;

[0023] forming a first support layer on the substrate;

[0024] forming a diaphragm layer, wherein the diaphragm layer comprises a movable part, a middle portion of the movable part has a thickness smaller than that of an edge portion of the movable part;

[0025] forming a second support layer on the diaphragm layer, and forming a back plate layer on the second support layer;

[0026] forming a first cavity in a middle portion of the substrate, forming a second cavity in a middle portion of the first support layer, and forming a third cavity in a middle portion of the second support layer, wherein the middle portion of the diaphragm layer is between the second cavity and the third cavity.

[0027] Exemplarily, the diaphragm layer further comprises a support part;

[0028] The support portion is annular, extends from the edge portion of the movable portion to the substrate and is located in the second cavity, and the outer sidewall surface of the movable portion is attached to the inner sidewall surface of the first support layer.

[0029] Exemplarily, the forming the diaphragm layer comprises:

[0030] An annular groove is formed on the first support layer near the edge;

[0031] A first diaphragm layer is deposited on the first support layer, covering the upper surface of the first support layer and filling the annular groove;

[0032] An intermediate portion of the first diaphragm layer is etched to form a first recess;

[0033] A second diaphragm layer with the same thickness is deposited on the first diaphragm layer and in the first recess, wherein the first diaphragm layer and the second diaphragm layer are made of the same material, the first diaphragm layer and the second diaphragm layer on the first support layer together form the movable portion, the upper side of the intermediate portion of the movable portion has a second recess, and the first diaphragm layer located in the annular groove is the support portion.

[0034] Exemplarily, the forming the third cavity in the second support layer comprises:

[0035] The back plate layer is etched to form a plurality of through holes penetrating through the back plate layer;

[0036] The second support layer is etched through the through holes to form the third cavity in the middle portion of the second support layer and expose the second recess.

[0037] Exemplarily, the forming the diaphragm layer comprises:

[0038] An annular groove is formed on the first support layer near the edge;

[0039] A third diaphragm layer is deposited on the first support layer, filling the annular groove and covering the upper surface of the first support layer;

[0040] An intermediate portion of the third diaphragm layer is etched to form a third recess and expose the first support layer;

[0041] A first support layer is deposited in the third recess to fill the third recess;

[0042] depositing a fourth diaphragm layer on the third diaphragm layer and the first support layer in the third groove, wherein the third diaphragm layer and the fourth diaphragm layer are made of the same material, and the third diaphragm layer and the fourth diaphragm layer on the first support layer together form the movable part, the lower side of the middle part of the movable part has a fourth groove, and the third diaphragm layer in the annular groove is the support part.

[0043] Exemplarily, the annular groove penetrates the first support layer.

[0044] The second cavity formed in the middle part of the first support layer includes:

[0045] The first support layer inside the annular groove is etched to form the second cavity, and the first support layer in the third groove is etched to expose the fourth groove.

[0046] Exemplarily, the material of the substrate includes silicon.

[0047] The material of the first support layer includes silicon oxide.

[0048] The material of the diaphragm layer includes single crystal silicon or polycrystalline silicon.

[0049] The material of the second support layer includes silicon oxide.

[0050] The material of the back plate layer includes polycrystalline silicon.

[0051] According to the MEMS microphone and the manufacturing method thereof, the thickness of the middle part of the movable part of the diaphragm layer of the MEMS microphone is configured to be smaller than the thickness of the edge part, the thinner middle part thickness can make the MEMS microphone have higher sensitivity, and the thicker edge part thickness can guarantee the mechanical performance (such as mechanical strength, etc.) of the diaphragm layer, so that the diaphragm layer is not easy to break in the case of large vibration and large sound pressure. BRIEF DESCRIPTION OF DRAWINGS

[0052] The following drawings of the present application are hereby incorporated into this application as part of the present application for understanding the present application. The embodiments of the present application and their descriptions shown in the drawings are used to explain the devices and principles of the present application. In the drawings,

[0053] Figure 1 It is a structural schematic diagram of a conventional MEMS microphone;

[0054] Figure 2 It is a structural schematic diagram of a MEMS microphone according to an embodiment of the present application;

[0055] Figures 3A-3K It is Figure 2a cross-sectional view of a structure formed by a related step of a manufacturing method of a MEMS microphone in the

[0056] Figure 4 a structure diagram of a MEMS microphone according to another embodiment of the present application;

[0057] Figure 5 a structure diagram of a MEMS microphone according to another embodiment of the present application;

[0058] Figures 6A-6L a structure diagram of a MEMS microphone according to another embodiment of the present application; Figure 5 a cross-sectional view of a structure formed by a related step of a manufacturing method of a MEMS microphone in the

[0059] Figure 7 a structure diagram of a MEMS microphone according to another embodiment of the present application.

[0060] BRIEF DESCRIPTION OF DRAWINGS

[0061] 10 - substrate, 11 - support layer, 12 - diaphragm layer, 13 - support layer, 14 - back plate layer, 15 - cavity, 16 - cavity, 17 - cavity;

[0062] 100 - substrate, 110 - first cavity, 200 - first support layer, 201 - annular groove, 210 - second cavity, 300 - diaphragm layer, 300' - diaphragm layer, 300A - diaphragm layer, 300B - diaphragm layer, 301 - first diaphragm layer, 302 - recess, 303 - second diaphragm layer, 304 - third diaphragm layer, 305 - recess, 306 - fourth diaphragm layer, 310 - movable portion, 310' - movable portion, 320 - support portion, 330 - recess, 340 - recess, 350 - connecting portion, 400 - second support layer, 410 - third cavity, 500 - back plate layer, 510 - through hole. DETAILED DESCRIPTION

[0063] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the application. However, it will be apparent to one skilled in the art that the application can be practiced without one or more of these specific details. In other instances, well-known features have not been described in detail to the extent that they would obscure the understanding of the application.

[0064] It is to be understood that the application can assume various alternative forms of embodiment, and it is not to be limited to the examples described herein. Rather, the embodiments are provided as illustrative examples so that a thorough and complete disclosure of the application can be conveyed fully and completely to those skilled in the art. In the drawings, the size and relative sizes of layers and regions can be exaggerated for clarity. Like reference numerals refer to like elements throughout.

[0065] It should be understood that, although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, "a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present application.

[0066] Spatially relative terms, such as "beneath", "below", "lower", "under", "above", "upper" and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and / or operation in addition to the orientations depicted in the figures.

[0067] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0068] Embodiments of the application are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the application. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and / or tolerances, are to be expected. Thus, embodiments of the application should not be construed as limited to the particular shapes of the regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. The regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the application.

[0069] Reference is made to the drawings Figure 1 A conventional MEMS microphone is exemplarily described.

[0070] The MEMS microphone includes a substrate 10, a support layer 11 provided on the substrate, a diaphragm layer 12 provided on the support layer 11, a support layer 13 provided on the diaphragm layer 12, and a back plate layer 14 provided on the support layer 13. A cavity 15 is provided in the substrate 10, a cavity 16 is provided in the support layer 11, and a cavity 17 is provided in the support layer 13.

[0071] The back electrode layer 14 and the diaphragm layer 12 are respectively applied with voltages, so that the two layers are electrically different and carry electric charges, forming a capacitor structure. According to the formula of the capacitor of parallel electrode plates: C = εA / d (wherein ε is the dielectric coefficient, A is the overlapping area of the two electrode plates, and d is the distance between the two capacitor plates), it can be known that the distance between the two capacitor plates changes, which changes the capacitance value. Therefore, when the sound wave acts on the diaphragm layer 12 to cause the diaphragm layer 12 to vibrate and deform, the distance between the diaphragm layer 12 and the back electrode layer 14 changes, which changes the capacitance value, and the change of the capacitance value can be converted into an electric signal output.

[0072] It is known to those skilled in the art that the sensitivity of the MEMS microphone is negatively related to the thickness of the diaphragm layer 12, that is, under the condition that other conditions remain unchanged, the thinner the diaphragm layer 12 is, the higher the sensitivity of the MEMS microphone is. The diaphragm layer 12 is a layer with uniform thickness arranged on the support layer 11 with the cavity 16. In order to achieve high sensitivity, the thickness of the diaphragm layer 12 is usually set to be very small, which reduces the mechanical properties (such as mechanical strength, etc.) of the diaphragm layer 12. In the case of large vibration and large sound pressure, the diaphragm layer 12 is easy to break, causing the microphone to fail.

[0073] In view of the deficiencies of the conventional MEMS microphone, the present application provides a MEMS microphone, which comprises a substrate, a first support layer, a diaphragm layer, a second support layer, and a back electrode layer. The middle part of the substrate has a first cavity. The first support layer is arranged on the substrate, and the middle part of the first support layer has a second cavity. The diaphragm layer is arranged on the support layer, and the diaphragm layer comprises a movable part (the movable part is the part of the diaphragm layer that can elastically vibrate). The thickness of the middle part of the movable part is less than the thickness of the edge part of the movable part. The second support layer is arranged on the diaphragm layer, and the middle part of the second support layer has a third cavity. The middle part of the movable part is located between the second cavity and the third cavity. The back electrode layer is arranged on the second support layer.

[0074] According to the MEMS microphone of the present application, the thickness of the middle part of the diaphragm layer is configured to be less than the thickness of the edge part. The thinner thickness of the middle part can make the MEMS microphone have higher sensitivity. The thicker thickness of the edge part can guarantee the mechanical properties (such as mechanical strength, etc.) of the diaphragm layer, so that the diaphragm layer is not easy to break in the case of large vibration and large sound pressure.

[0075] Reference is made to the accompanying drawings Figure 2 , the accompanying drawings Figures 3A-3K The MEMS microphone and the manufacturing method thereof according to an embodiment of the present application are exemplarily described. The MEMS microphone comprises a substrate 100, a first support layer 200, a diaphragm layer 300, a second support layer 400, and a back electrode layer 500.

[0076] In the embodiments of the present application, the substrate 100 is a silicon substrate, and the material of the substrate 100 is silicon. In some other embodiments, the material of the substrate 100 can also be one or more of germanium, silicon germanium, silicon carbide, silicon nitride, or other suitable substrate materials. The first cavity 110 is arranged in the middle of the substrate 100. The first cavity 110 can be configured to gradually increase in cross-sectional area from the side away from the first support layer 200 to the side toward the first support layer 200. In some other embodiments, the first cavity 110 can be configured to remain unchanged in cross-sectional area from the side away from the first support layer 200 to the side toward the first support layer 200. The skilled person can make the necessary settings according to the needs.

[0077] In the embodiments of the present application, the material of the first support layer 200 includes but is not limited to silicon oxide. The first support layer 200 is arranged on the substrate 100 and at the edge of the substrate 100. The first support layer 200 includes an outer sidewall and an inner sidewall. The inner sidewall is the sidewall of the first support layer 200 on the side toward the central axis thereof, and the outer sidewall is the sidewall of the first support layer 200 on the side away from the central axis thereof. The first support layer 200 has a second cavity 210 in the middle thereof, i.e., the area enclosed by the inner sidewall of the first support layer 200 is the second cavity 210. In the top-down view (i.e., the view from the top to the bottom), the area of the second cavity 210 can be greater than the area of the side of the first cavity 110 toward the first support layer 200. Figure 2 In the view from the top to the bottom, the area of the second cavity 210 can be greater than the area of the side of the first cavity 110 toward the first support layer 200.

[0078] In the embodiments of the present application, the material of the diaphragm layer 300 includes but is not limited to single crystal silicon or polycrystalline silicon. The diaphragm layer 300 includes a movable portion 310, a support portion 320 and a connecting portion 350. The movable portion 310 and the connecting portion 350 are located between the first support layer 200 and the second support layer 400. The movable portion 310 is the part of the diaphragm layer 300 that can elastically vibrate. The connecting portion 350 surrounds the movable portion 310 in the circumferential direction and is connected to the first support layer 200 and the second support layer 400 (connected to one of the first support layer 200 and the second support layer 400, or connected to both of them). The upper side (i.e., the side facing the back plate layer 500) of the middle part of the movable portion 310 has a groove 330. The groove 330 is arranged such that the thickness of the middle part of the movable portion 310 is smaller than the thickness of the edge part thereof. It should be noted that the middle part herein can refer to the central part of the movable portion 310, i.e., the central axis of the groove 330 coincides with the central axis of the movable portion 310. In some embodiments, the middle part herein can refer to the part near the central part of the movable portion 310, i.e., the central axis of the groove 330 can be close to but not coincide with the central axis of the movable portion 310. The support portion 320 is annular, extends from the edge part of the movable portion 310 to the substrate 100 and is located in the second cavity 210. The outer side wall surface of the support portion 320 is in contact with the inner side wall surface of the first support layer 200. It should be noted that the annular shape herein is the shape of the support portion 320 in the top view, which can refer to a circular ring shape or a ring shape formed by a closed polygon. In the embodiments of the present application, the end of the support portion 320 away from the movable portion 310 is in contact with the substrate 100. In other embodiments, the end of the support portion 320 away from the movable portion 310 can have the first support layer 200 therebetween and not be in contact with the substrate 100. The support portion 320 can function as a reinforcing rib, which can effectively improve the mechanical properties (such as mechanical strength) of the diaphragm layer 300, so that the diaphragm layer 300 is not easy to break under the condition of large vibration and large sound pressure.

[0079] In the embodiments of the present application, the material of the second support layer 400 includes but is not limited to silicon oxide. The second support layer 400 is used to support the back plate layer 500 and to insulate the diaphragm layer 300 and the back plate layer 500 from each other. The second support layer 400 is located on the diaphragm layer 300. The middle part of the second support layer 400 has a third cavity 410. The movable portion 310 is located between the second cavity 210 and the third cavity 410. When elastically vibrating, the movable portion 310 can deform towards the second cavity 210 or the third cavity 410. The central axes of the middle part of the movable portion 310, the second cavity 210 and the third cavity 410 can be on a straight line.

[0080] In the embodiments of the present application, the material of the back plate layer 500 includes but is not limited to polysilicon. In some embodiments, the material of the back plate layer 500 can include silicon nitride and polysilicon, that is, the back plate can be provided with at least two layers, one of which is a silicon nitride layer and the other of which is a polysilicon layer. The back plate layer 500 is provided with a plurality of through holes 510 penetrating the back plate layer 500, and the through holes 510 are used to etch the second support layer 400 to form the third cavities 410 on the second support layer 400.

[0081] Referring to the accompanying drawings Figures 3A-3K To Figure 2 The manufacturing method of the MEMS microphone in the embodiment of the present application includes the following steps:

[0082] S100: providing a substrate 100.

[0083] Specifically, referring to the accompanying drawings Figure 3A The substrate 100 may, for example, be a silicon substrate.

[0084] S110: forming a first support layer 200 on the substrate 100.

[0085] Specifically, referring to the accompanying drawings Figure 3B A first support layer 200 with uniform thickness is deposited on the substrate 100, and the first support layer 200 may, for example, be a silicon oxide layer. It should be noted that the specific method of deposition mentioned in the present application can be chemical vapor deposition (CVD), physical vapor deposition (PVD), or other suitable deposition methods known to those skilled in the art, and those skilled in the art can select the corresponding deposition method according to the deposited material.

[0086] S120: forming a diaphragm layer 300. The diaphragm layer 300 includes a movable portion 310 and a connecting portion 350 located on the first support layer 200, and a support portion 320 extending from the first support layer 200 to the substrate 100, and the upper side of the middle portion of the movable portion 310 has a groove 302, so that the thickness of the middle portion of the movable portion 310 is less than the thickness of the edge portion of the movable portion 310.

[0087] Specifically, referring to the accompanying drawings Figures 3C-3F Step S120 specifically includes:

[0088] S121: forming an annular groove 201 on the first support layer 200 near the edge.

[0089] Specifically, the annular groove 201 can be formed on the first support layer 200 near the edge by etching. The specific etching method mentioned in the present application can be dry etching or wet etching, and the person skilled in the art can select the corresponding etching method according to the material to be etched. In the embodiment of the present application, the annular groove 201 penetrates the first support layer 200 to expose the substrate 100.

[0090] S122: depositing a first diaphragm layer 301 on the first support layer 200, the first diaphragm layer 301 covering the upper surface of the first support layer 200 and filling the annular groove 201. Wherein the upper surface of the first diaphragm layer 301 after deposition is a plane. It should be noted that in some embodiments, after depositing the first diaphragm layer 301, the upper surface of the first diaphragm layer 301 can be planarized to make the upper surface of the first diaphragm layer 301 a plane (for example, when the depth of the annular groove 201 is relatively deep, the upper surface of the first diaphragm layer 301 is usually planarized). The specific method of planarization can be chemical-mechanical planarization (CMP) or other suitable planarization process, which can be selected by the person skilled in the art as needed.

[0091] S123: etching the middle part of the first diaphragm layer 301 to form a groove 302. Wherein the groove 302 is completely located on the upper side of the first support layer 200 inside the annular groove 201. In the embodiment of the present application, the depth of the groove 302 is consistent with the thickness of the first diaphragm layer 301 on the first support layer 200. In some embodiments, the depth of the groove 302 can be less than the thickness of the first diaphragm layer 301 on the first support layer 200.

[0092] S124: depositing a second diaphragm layer 303 of the same thickness on the first diaphragm layer 301 and in the groove 302. Wherein the first diaphragm layer 301 and the second diaphragm layer 303 are made of the same material, for example, both can be single crystal silicon or polycrystalline silicon. The first diaphragm layer 301 located on the first support layer 200 (i.e. the part of the first diaphragm layer 301 located above the first support layer 200) and the second diaphragm layer 303 together form a movable part 310 and a connecting part 350. The upper side of the middle part of the movable part 310 has a groove 330, so the thickness of the middle part is less than that of the edge part. The first diaphragm layer 301 located in the annular groove 201 (i.e. the part of the first diaphragm layer 301 located in the annular groove 201) is a support part 320.

[0093] S130: forming a second support layer 400 on the diaphragm layer 300, and forming a back plate layer 500 on the second support layer 400.

[0094] Specifically, referring to FIG. 4, the second support layer 400 can be formed on the diaphragm layer 300. The second support layer 400 can be made of a material with a high elastic modulus, such as silicon, silicon dioxide, silicon nitride, aluminum, etc. The second support layer 400 can be formed by deposition, etching, etc. Figure 3GStep S130 includes:

[0095] S131: A second support layer 400 is deposited on the diaphragm layer 300. The second support layer 400 can be made of silicon oxide, filling the grooves 330 on the diaphragm layer 300, and its upper surface is planar. It should be noted that in some embodiments, after depositing the second support layer 400, its upper surface can be planarized to make it planar (e.g., when the grooves 330 are deep). The planarization can be chemical mechanical planarization or other suitable planarization processes, which can be selected by those skilled in the art as needed. It should be noted that at this stage, the second support layer 400 does not yet have a third cavity 410 in the middle.

[0096] S132: Deposit a back electrode layer 500 on the second support layer 400. The back electrode layer 500 can be made of polycrystalline silicon.

[0097] S140: A first cavity 110 is formed in the middle of the substrate 100, a second cavity 210 is formed in the middle of the first support layer 200, and a third cavity 410 is formed in the middle of the second support layer 400, wherein the middle portion of the diaphragm layer 300 is located between the second cavity 210 and the third cavity 410. It should be noted that the specific order in which the first cavity 110, the second cavity 210, and the third cavity 410 are formed can be flexibly chosen by those skilled in the art; generally, it is only necessary to ensure that the second cavity 210 is formed after the first cavity 110.

[0098] See appendix Figures 3H-3K Step S140 includes:

[0099] S141: A third cavity 410 is formed in the middle of the second support layer 400.

[0100] Specifically, see Appendix Figure 3H , 3I First, the back electrode layer 500 is etched to form multiple through holes 510 penetrating the back electrode layer 500. The through holes 510 expose the second support layer 400, allowing it to be etched through the through holes 510. Then, the second support layer 400 is etched through the through holes 510 to form a third cavity 410 in the middle of the second support layer 400, exposing the groove 330. Specifically, etching solution can be injected through the through holes 510 to remove the middle portion of the second support layer 400, forming the third cavity 410. Additionally, the second support layer 400 in the groove 330 is removed, exposing the groove 330.

[0101] S142: A first cavity 110 is formed in the middle of the substrate 100.

[0102] Specifically, refer to the attached Figure 3J The middle part of the substrate 100 can be etched using a Deep Reactive Ion Etching (DRIE) process to form the first cavity 110.

[0103] S143: Forming a second cavity 210 in the middle part of the first support layer 200.

[0104] Specifically, refer to the attached Figure 3I The middle part of the first support layer 200 can be etched by injecting etching liquid through the first cavity 110 to form the second cavity 210. In the embodiment of the present application, since the annular groove 201 penetrates through the first support layer 200, the etching liquid removes the first support layer 200 inside the annular groove 201 to form the second cavity 210. It should be noted that the second cavity 210 here includes the annular groove 201 and the space inside the annular groove 201. The first support layer 200 inside the annular groove 201 is removed, and the second cavity 210 is completely formed. The movable part 310 is located between the second cavity 210 and the third cavity 410.

[0105] In the embodiment of the present application, the third cavity 410 is formed first, then the first cavity 110 is formed, and finally the second cavity 210 is formed. In some other embodiments, the step S142 can be performed first to form the first cavity 110, then the back plate layer 500 is etched to form a plurality of through holes 510 penetrating through the back plate layer 500, and finally the first support layer 200 and the second support layer 400 are etched at the same time to form the second cavity 210 and the third cavity 410. The second support layer 400 in the groove 330 is removed when the second support layer 400 in the groove 330 is etched, and the groove 330 is exposed. That is, the first cavity 110 can be formed first, and then the second cavity 210 and the third cavity 410 are formed at the same time. It should be noted that the specific order of forming the first cavity 110, the second cavity 210 and the third cavity 410 is not limited to the above embodiment, and those skilled in the art can select flexibly according to the needs. Generally, it only needs to meet the requirement that the second cavity 210 is formed after the first cavity 110.

[0106] Refer to the attached Figure 4 A MEMS microphone according to another embodiment of the present application is exemplarily described. The MEMS microphone includes a substrate 100, a first support layer 200, a diaphragm layer 300A, a second support layer 400 and a back plate layer 500.

[0107] The attached Figure 4 The structure of the substrate 100, the first support layer 200, the second support layer 400 and the back plate layer 500 in the MEMS microphone shown in the attached Figure 2The MEMS microphone shown in FIG. 1 is basically the same as the MEMS microphone shown in FIG. 3, and thus will not be described again. Figure 4 The MEMS microphone shown in FIG. 1 is basically the same as the MEMS microphone shown in FIG. 3, and thus will not be described again. Figure 2 The difference between the MEMS microphone shown in FIG. 1 and the MEMS microphone shown in FIG. 3 is the diaphragm layer 300A, and thus will not be described again. Figure 4 The diaphragm layer 300A in FIG. 1 only includes the movable part 310 and the connecting part 350 in the diaphragm layer 300 in FIG. 3, i.e., it does not have the support part 320.

[0108] The MEMS microphone shown in FIG. 1 is basically the same as the MEMS microphone shown in FIG. 3, and thus will not be described again. Figure 4 The manufacturing method of the MEMS microphone shown in FIG. 1 includes the following steps:

[0109] S100’: providing a substrate 100.

[0110] S110’: forming a first support layer 200 on the substrate 100.

[0111] S120’: forming a diaphragm layer 300A, wherein the diaphragm layer 300A includes a movable part 310, and the thickness of the middle part of the movable part 310 is less than the thickness of the edge part thereof.

[0112] S130’: forming a second support layer 400 on the diaphragm layer 300A, and forming a back plate layer 500 on the second support layer 400.

[0113] S140’: forming a first cavity 110 in the middle of the substrate 100, forming a second cavity 210 in the middle of the first support layer 200, and forming a third cavity 410 in the middle of the second support layer 400, wherein the movable part 310 is located between the second cavity 210 and the third cavity 410.

[0114] The steps S100’, S110’, S130’, and S140’ are basically the same as the steps S100, S110, S130, and S140 in the above-described embodiments, and thus will not be described again.

[0115] For the step S120’, it specifically includes:

[0116] S121’: depositing a first diaphragm layer 301 with uniform thickness on the first support layer 200, and the first diaphragm layer 301 covers the upper surface of the first support layer 200.

[0117] S122’: etching the middle part of the first diaphragm layer 301 to form a groove 302, wherein the depth of the groove 302 is consistent with the thickness of the first diaphragm layer 301 on the first support layer 200. In some embodiments, the depth of the groove 302 can be less than the thickness of the first diaphragm layer 301 on the first support layer 200.

[0118] S123: A second diaphragm layer 303 of the same thickness is deposited on the first diaphragm layer 301 and in the groove 302. The first diaphragm layer 301 and the second diaphragm layer 303 are made of the same material, for example, both can be monocrystalline silicon or polycrystalline silicon. The first diaphragm layer 301 and the second diaphragm layer 303 together form the movable part 310 and the connecting part 350 (i.e., diaphragm layer 300A). The upper side of the middle portion of the movable part 310 has a groove 330, therefore the thickness of the middle portion is less than the thickness of its edge portions.

[0119] See attached document Figure 5 Appendix Figures 6A-6L A MEMS microphone and its manufacturing method according to another embodiment of this application will be described by way of example. The MEMS microphone includes a substrate 100, a first support layer 200, a diaphragm layer 300', a second support layer 400, and a back electrode layer 500.

[0120] Appendix Figure 5 The structure and attachments of the substrate 100, first support layer 200, second support layer 400, and back electrode layer 500 in the MEMS microphone shown are as follows. Figure 2 The MEMS microphones shown are basically the same, so they will not be described again here. Figure 4 The diaphragm layer 300' in the MEMS microphone shown in the figure and the attached Figure 2 The difference in the diaphragm layer 300 of the MEMS microphone shown is that... Figure 4 The upper side (i.e. the side facing the back electrode layer 500) of the movable part 310' in the diaphragm layer 300' shown in the figure is flat, and the lower side (i.e. the side facing the substrate 100) of the movable part 310' has a groove 340. Therefore, the groove 340 is provided such that the thickness of the middle part of the movable part 310' is less than the thickness of its edge part.

[0121] See attached document Figures 6A-6L right Figure 5 The manufacturing method of the MEMS microphone is illustrated by way of example, and the manufacturing method includes the following steps:

[0122] S200: Provides substrate 100.

[0123] Specifically, see Appendix Figure 6A The substrate 100 may be, for example, a silicon substrate.

[0124] S210: A first support layer 200 is formed on the substrate 100.

[0125] Specifically, see Appendix Figure 6B A first support layer 200 of uniform thickness is deposited on the substrate 100. The first support layer 200 may be, for example, a silicon oxide layer.

[0126] S220: forming a diaphragm layer 300'. The diaphragm layer 300' includes a movable portion 310' and a connecting portion 350 on the first support layer 200, and a support portion 320 extending from the first support layer 200 to the substrate 100. The movable portion 310' has a groove 340 on the lower side of the middle portion, so that the thickness of the middle portion of the movable portion 310' is smaller than the thickness of the edge portion of the movable portion 310'.

[0127] Specifically, referring to the accompanying drawings, Figures 6C-6G The step S220 specifically includes:

[0128] S221: forming a ring-shaped groove 201 on the first support layer 200 near the edge.

[0129] Specifically, the ring-shaped groove 201 can be formed on the first support layer 200 near the edge by etching. In the embodiments of the present application, the ring-shaped groove 201 penetrates the first support layer 200 to expose the substrate 100.

[0130] S222: depositing a third diaphragm layer 304 on the first support layer 200, the third diaphragm layer 304 covering the upper surface of the first support layer 200 and filling the ring-shaped groove 201. The upper surface of the deposited third diaphragm layer 304 is a plane. It should be noted that in some embodiments, after depositing the third diaphragm layer 304, the upper surface of the third diaphragm layer 304 can be planarized to make the upper surface of the third diaphragm layer 304 a plane (for example, when the depth of the ring-shaped groove 201 is relatively deep, it is usually necessary to planarize the upper surface of the third diaphragm layer 304). The specific way of planarization can be chemical mechanical planarization or other suitable planarization process, which can be selected as needed by those skilled in the art.

[0131] S223: etching the middle portion of the third diaphragm layer 304 to form a groove 305 and expose the first support layer 200. The groove 305 is completely located on the upper side of the first support layer 200 inside the ring-shaped groove 201. In the embodiments of the present application, the depth of the groove 305 is consistent with the thickness of the third diaphragm layer 304 on the first support layer 200.

[0132] S224: depositing a first support layer 201 in the groove 305 to fill the groove 305. It should be noted that depositing the first support layer 201 here refers to depositing the same material (for example, silicon oxide) as the first support layer 200 to form the first support layer 201. In the embodiment of the present application, the first support layer 201 deposited in the groove 305 completely fills the groove 305, and the upper surface of the first support layer 201 is flush with the upper surface of the third diaphragm layer 304. In some other embodiments, the first support layer 201 can partially fill the groove 305, that is, there can be a certain distance between the upper surface of the first support layer 201 deposited in the groove 305 and the upper surface of the third diaphragm layer 304.

[0133] S225: depositing a fourth diaphragm layer 306 on the third diaphragm layer 304 and the first support layer 201 located in the groove 305. The third diaphragm layer 304 and the fourth diaphragm layer 306 are made of the same material, for example, both can be single crystal silicon or polycrystalline silicon. The third diaphragm layer 304 and the fourth diaphragm layer 306 located on the first support layer 200 together form the movable part 310' and the connecting part 350, and the lower side of the middle part of the movable part 310' has a groove 340 (the groove 340 is filled by the first support layer 201). The third diaphragm layer 304 located in the annular groove 201 is the support part 320. In the embodiment of the present application, the upper surface of the deposited fourth diaphragm layer 306 is a plane. In some embodiments, after depositing the fourth diaphragm layer 306, the upper surface of the fourth diaphragm layer 306 can be planarized to make the upper surface of the fourth diaphragm layer 306 a plane. In some embodiments, when the first support layer 201 partially fills the groove 305, the same thickness of the fourth diaphragm layer 306 can be deposited on the third diaphragm layer 304 and the first support layer 201 located in the groove 305, so that the upper side and the lower two sides of the middle part of the formed movable part 310' have grooves.

[0134] S230: forming a second support layer 400 on the diaphragm layer 300', and forming a back plate layer 500 on the second support layer 400.

[0135] Specifically, referring to FIG. 4, the step S230 includes: Figure 6H

[0136] S231: depositing a second support layer 400 on the diaphragm layer 300'. The material of the second support layer 400 can be silicon oxide, and the upper surface thereof is a plane. In some embodiments, when the upper side of the middle part of the movable part 310' has a groove, the second support layer 400 fills the groove, and the upper surface thereof is a plane. Specifically, after depositing the second support layer 400, the upper surface of the second support layer 400 can be planarized to make the upper surface of the second support layer 400 a plane.

[0137] ​S232: depositing a back plate layer 500 on the second support layer 400. The material of the back plate layer 500 can be polysilicon.

[0138] S240: forming a first cavity 110 in the middle of the substrate 100, forming a second cavity 210 in the middle of the first support layer 200, and forming a third cavity 410 in the middle of the second support layer 400, wherein the movable part 310' is located between the second cavity 210 and the third cavity 410. It should be noted that the specific order of forming the first cavity 110, the second cavity 210, and the third cavity 410 can be flexibly selected by those skilled in the art, and generally only needs to meet the requirement that the second cavity 210 is formed after the first cavity 110.

[0139] Referring to FIG. 2B, Figures 6I-6L S240 includes:

[0140] S241: forming the third cavity 410 in the middle of the second support layer 400.

[0141] Specifically, referring to FIG. 2B, Figure 6I 、 6J First, the back plate layer 500 is etched to form a plurality of through holes 510 penetrating the back plate layer 500. The through holes 510 are arranged such that the second support layer 400 is exposed, so that the second support layer 400 can be etched. Then, the second support layer 400 is etched through the through holes 510 to form the third cavity 410 in the middle of the second support layer 400. Specifically, etching liquid can be injected through the through holes 510 to remove the middle part of the second support layer 400 to form the third cavity 410. In some embodiments, when the upper side of the middle part of the movable part 310' has a groove, the second support layer 400 in the groove is removed to expose the groove.

[0142] S242: forming the first cavity 110 in the middle of the substrate 100.

[0143] Specifically, referring to FIG. 2B, Figure 6K Deep reactive ion etching (DRIE) can be used to etch the middle part of the substrate 100 to form the first cavity 110.

[0144] S243: forming the second cavity 210 in the middle of the first support layer 200.

[0145] Specifically, referring to FIG. 2B, Figure 6LEtching solution can be injected through the first cavity 110 to etch the middle portion of the first support layer 200 to form the second cavity 210, and to etch the first support layer 201 located in the groove 340 to expose the groove 340. In this embodiment, since the annular groove 201 penetrates the first support layer 200, the etching solution will remove the first support layer 200 located inside the annular groove 201 to form the second cavity 210. It should be noted that the second cavity 210 here includes the annular groove 201 and the space inside the annular groove 201. The second cavity 210 is only fully formed after the first support layer 200 inside the annular groove 201 is removed. The middle portion of the diaphragm layer 300' is located between the second cavity 210 and the third cavity 410.

[0146] In this embodiment, the third cavity 410 is formed first, then the first cavity 110 is formed, and finally the second cavity 210 is formed. In other embodiments, step S242 can be performed first to form the first cavity 110, then the back electrode layer 500 is etched to form multiple through holes 510 penetrating the back electrode layer 500, and finally, the first support layer 200 and the second support layer 400 are etched simultaneously to form the second cavity 210 and the third cavity 410. When etching the first support layer 200, the first support layer 201 in the groove 340 is removed to expose the groove 340. That is, the first cavity 110 can be formed first, and then the second cavity 210 and the third cavity 410 can be formed simultaneously. It should be noted that the specific order of forming the first cavity 110, the second cavity 210 and the third cavity 410 is not limited to the above embodiments. Those skilled in the art can choose flexibly according to needs. Generally, it is only necessary to ensure that the second cavity 210 is formed after the first cavity 110.

[0147] See attached document Figure 7 An exemplary description is provided for a MEMS microphone according to another embodiment of this application. The MEMS microphone includes a substrate 100, a first support layer 200, a diaphragm layer 300B, a second support layer 400, and a back electrode layer 500.

[0148] Appendix Figure 7 The structure and attachments of the substrate 100, first support layer 200, second support layer 400, and back electrode layer 500 in the MEMS microphone shown are as follows. Figure 5 The MEMS microphones shown are basically the same, so they will not be described again here. Figure 7 The MEMS microphone shown in the image is accompanied by... Figure 5 The difference in the MEMS microphone shown is the diaphragm layer 300B, with... Figure 7 The diaphragm layer 300B in the middle only includes the attached Figure 5 The movable part 310' and the connecting part 350 in the diaphragm layer 300', that is, it does not have a support part 320.

[0149] Appendix Figure 7 The manufacturing method of the MEMS microphone shown includes the following steps:

[0150] S200': Provides a substrate 100.

[0151] S210': A first support layer 200 is formed on the substrate 100.

[0152] S220': Forming a diaphragm layer 300B, wherein the diaphragm layer 300B includes a movable portion 310', the thickness of the middle portion of the movable portion 310' is less than the thickness of its edge portion.

[0153] S230': A second support layer 400 is formed on the diaphragm layer 300B, and a back electrode layer 500 is formed on the second support layer 400.

[0154] S240': A first cavity 110 is formed in the middle of the substrate 100, a second cavity 210 is formed in the middle of the first support layer 200, and a third cavity 410 is formed in the middle of the second support layer 400, wherein the movable part 310' is located between the second cavity 210 and the third cavity 410.

[0155] Steps S200', S210', S230' and S240' are basically the same as steps S200, S210, S230 and S240 in the above embodiments, and will not be described again here.

[0156] For step S220', it specifically includes:

[0157] S221': A third diaphragm layer 304 of uniform thickness is deposited on the first support layer 200, and the third diaphragm layer 304 covers the upper surface of the first support layer 200.

[0158] S222': The middle portion of the third diaphragm layer 304 is etched to form a groove 305 and expose the first support layer 200. In this embodiment, the depth of the groove 305 is the same as the thickness of the third diaphragm layer 304 on the first support layer 200.

[0159] S223: depositing a first support layer 201 in the groove 305 to fill the groove 305. It should be noted that depositing the first support layer 201 here means depositing the same material (e.g. silicon oxide) as the first support layer 200 to form the first support layer 201. In the embodiment of the present application, the first support layer 201 deposited in the groove 305 completely fills the groove 305, and the upper surface of the first support layer 201 is flush with the upper surface of the third diaphragm layer 304. In some other embodiments, the first support layer 201 can partially fill the groove 305, i.e. there can be a certain distance between the upper surface of the first support layer 201 deposited in the groove 305 and the upper surface of the third diaphragm layer 304.

[0160] S224': depositing a fourth diaphragm layer 306 on the third diaphragm layer 304 and the first support layer 201 located in the groove 305. The third diaphragm layer 304 and the fourth diaphragm layer 306 are made of the same material, e.g. single crystal silicon or polycrystalline silicon. The third diaphragm layer 304 and the fourth diaphragm layer 306 located on the first support layer 200 together form a movable portion 310' and a connecting portion 350 (i.e. the diaphragm layer 300B), and the middle portion of the movable portion 310' has a groove 340 on the lower side. In the embodiment of the present application, the upper surface of the deposited fourth diaphragm layer 306 is a plane. In some embodiments, after depositing the fourth diaphragm layer 306, the upper surface of the fourth diaphragm layer 306 can be planarized to make the upper surface of the fourth diaphragm layer 306 a plane. In some embodiments, when the first support layer 201 partially fills the groove 305, the same thickness of the fourth diaphragm layer 306 can be deposited on the third diaphragm layer 304 and the first support layer 201 located in the groove 305, so that the upper side and the lower two sides of the middle portion of the formed movable portion 310' have grooves.

[0161] Although the example embodiments have been described with reference to the drawings, it will be understood that the example embodiments are merely illustrative and are not intended to limit the scope of the present application. Various changes and modifications can be made thereto by those of ordinary skill in the art without departing from the scope and spirit of the present application. All such changes and modifications are intended to be included within the scope of the present application as defined by the appended claims.

[0162] In several embodiments provided by the present application, it should be understood that the disclosed devices and methods can be implemented in other manners. For example, the above-described device embodiments are merely illustrative, and the division of units can be changed. For example, multiple units or components can be combined or integrated into another device, or some features can be ignored or not implemented.

[0163] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the application can be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0164] Similarly, it is to be understood that the embodiments of the present application can be used in the exact form disclosed herein, or with minor modifications, and the present application is not limited to the exact form disclosed herein. It is also to be understood that the features of the present application can be combined, exchanged or removed and that the scope of the application is not limited to the exact construction described herein. Similarly, it should be understood that, in the description of example embodiments of the application, various features of the application are sometimes grouped together in a single embodiment, figure, or description of related features. This should not be understood as reflecting an intention that the application requires more features than are explicitly recited in each claim. Rather, it will be understood that claims may

[0165] Those skilled in the art will appreciate that all features described herein (including all accompanying claims, abstract and drawings), and steps of any method or procedure so disclosed, can be combined in any combination, except where features are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) can be replaced by alternative features serving the same, equivalent or a similar purpose, unless expressly stated otherwise.

[0166] Further, those skilled in the art will appreciate that the features of the different embodiments can be combined in any combination, provided such combinations are not mutually exclusive, and such combinations are within the scope of the application and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.

[0167] It is noted that the foregoing examples have been provided merely for the purposes of illustration and are not intended to limit the application of the application. Other examples and modifications will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. Therefore, the scope and spirit of the application should be judged in terms of the claims, which follow.

Claims

1. A method of manufacturing a MEMS microphone, characterized by, The method comprises: providing a substrate; forming a first support layer on the substrate; forming a diaphragm layer on the first support layer, wherein the diaphragm layer comprises a movable portion, a middle portion of the movable portion has a thickness smaller than that of an edge portion of the movable portion; forming a second support layer on the diaphragm layer, and forming a back plate layer on the second support layer; forming a first cavity in a middle portion of the substrate, a second cavity in a middle portion of the first support layer, and a third cavity in a middle portion of the second support layer, wherein the movable portion is located between the second cavity and the third cavity; wherein the diaphragm layer further comprises a support portion; the support portion is annular, extends from the edge portion of the movable portion to the substrate and is located in the second cavity, and an outer sidewall surface of the support portion is attached to an inner sidewall surface of the first support layer; wherein the forming of the diaphragm layer comprises: forming an annular groove on the first support layer near the edge; depositing a third diaphragm layer on the first support layer, the third diaphragm layer fills the annular groove and covers an upper surface of the first support layer; etching a middle portion of the third diaphragm layer to form a third groove and expose the first support layer; depositing a first support layer in the third groove to fill the third groove, wherein an upper surface of the first support layer is flush with an upper surface of the third diaphragm layer; depositing a fourth diaphragm layer on the third diaphragm layer and the first support layer located in the third groove, wherein the third diaphragm layer and the fourth diaphragm layer are made of the same material, the third diaphragm layer and the fourth diaphragm layer located on the first support layer together form the movable portion, a lower side of a middle portion of the movable portion has a fourth groove, and the third diaphragm layer located in the annular groove is the support portion.

2. The manufacturing method according to claim 1, wherein: the annular groove penetrates through the first support layer; the forming of the second cavity in the middle portion of the first support layer comprises: etching the first support layer located inside the annular groove to form the second cavity, and etching the first support layer located in the third groove to expose the fourth groove.

3. The manufacturing method according to claim 1 or 2, wherein: a material of the substrate comprises silicon; a material of the first support layer comprises silicon oxide; a material of the diaphragm layer comprises single crystal silicon or polycrystalline silicon; a material of the second support layer comprises silicon oxide; a material of the back plate layer comprises polycrystalline silicon.

Images