Microphone, micro-electro-mechanical system acoustic sensor and method of manufacturing the same

Abstract

The micro-electro-mechanical system acoustic sensor includes a silicon substrate, an insulating layer arranged above the silicon substrate, two first electrode layers arranged above the insulating layer and spaced apart from each other, and two second electrode layers arranged above the first electrode layers and connected to the corresponding first electrode layers through at least one support. The second electrode layer and part of the insulating layer and the first electrode layer form a sound flow channel with an inlet. The second electrode layer has a front section adjacent to the inlet and a rear section. The front section is opposite to the outer surface of the sound flow channel and forms a first arc surface expanding along a sound flow direction of the sound flow channel. The rear section is opposite to the outer surface of the sound flow channel, continuously extends from the surface of the first arc surface, and forms a second arc surface narrowing along the sound flow direction.

Description

Technical Field

[0001] This application relates to an acoustic device, and more particularly to a microphone, a microelectromechanical system acoustic sensor, and a method for manufacturing the same, which are used in the field of acoustics. Background Technology

[0002] There are many types of microphones, such as dynamic, condenser, ribbon, and carbon fiber microphones. Furthermore, in mobile devices, such as mobile phones, electret condenser microphones and microelectromechanical system (MEMS) microphones are the most common. MEMS microphones utilize semiconductor processes to manufacture tiny mechanical components, employing semiconductor techniques such as deposition and selective etching of material layers to create the microphone's acoustic sensors.

[0003] Please refer to Figures 8A to 8F This is a schematic diagram of the manufacturing method of the acoustic sensor of a conventional microphone. It can be divided into many complex steps in sequence, including a conductive electrode layer step, a first air-gap oxide layer step, a second air-gap oxide layer step, a polysilicon backplate step, a metal layer step, and a backside silicon etching step to fabricate a diaphragm.

[0004] Specifically, in the conductive electrode layer step, a substrate 91 is provided, and an insulating layer 92 and an electrode layer 93 are formed on the substrate 91. Next, in the first air gap oxide layer step and the second air gap oxide layer step, a first oxide layer 94 and a second oxide layer 95 are formed, respectively. Subsequently, in the polysilicon backplane step, a polysilicon backplane layer 96 is formed on the second oxide layer 95, and in the metal layer step, a first metal layer 97 is formed on the polysilicon backplane layer 96.

[0005] Please refer to Figure 8E As shown, in the metal layer step, several through holes H are formed on the polysilicon backplane layer 96 and the first metal layer 97 respectively, and etching solution is poured into the through holes H to etch the first oxide layer 94 and the second oxide layer 95.

[0006] However, because the opening size of the through-hole H is generally small, the etching solution cannot easily flow in and out, resulting in insufficient etching of the first oxide layer 94 and the second oxide layer 95, causing the polysilicon backplane layer 96 to connect with the electrode layer 93; or it may cause over-etching, resulting in etching to the insulating layer 92 and the electrode layer 93, or even causing the electrode layer 93 to break during use due to insufficient thickness caused by over-etching. Therefore, the above-mentioned conventional microphone acoustic sensor manufacturing method is prone to poor etching precision control, which affects the sensitivity of the acoustic sensor, and has problems such as complicated procedures and poor product yield.

[0007] In view of this, it is necessary to provide a microphone, a microelectromechanical system acoustic sensor, and a method for manufacturing the same, in order to solve the above-mentioned problems. Summary of the Invention

[0008] To address the problems in the prior art, this application discloses a microelectromechanical system acoustic sensor that can increase the amplitude of electrode vibration caused by a sound source.

[0009] This application also discloses a microphone that has the above-mentioned microelectromechanical system acoustic sensor.

[0010] This application further discloses a method for manufacturing a microelectromechanical system acoustic sensor, which can simplify the manufacturing process and improve the manufacturing yield at the same time.

[0011] On one hand, an embodiment of this application proposes a microelectromechanical system acoustic sensor, characterized in that it includes: a silicon substrate; at least one insulating layer disposed above the silicon substrate; two first electrode layers disposed above the insulating layer and spaced apart from each other; and two second electrode layers disposed above the first electrode layers, each second electrode layer having at least one support member connecting a corresponding first electrode layer, the second electrode layer, together with a portion of the insulating layer and the first electrode layers, forming an acoustic flow channel, the acoustic flow channel having an inlet, the second electrode layer having a front section adjacent to the inlet and a rear section, the front section facing away from the outer surface of the acoustic flow channel and forming a gradually expanding first arc surface along the acoustic flow direction of the acoustic flow channel, the rear section facing away from the outer surface of the acoustic flow channel, extending continuously from the surface of the first arc surface and forming a gradually contracting second arc surface along the acoustic flow direction.

[0012] In another aspect, an acoustic sensor for a microelectromechanical system (MEMS) according to an embodiment of this application is characterized by comprising: a silicon substrate; at least one insulating layer disposed above the silicon substrate; two first electrode layers disposed above the insulating layer and spaced apart from each other; and two second electrode layers disposed above the first electrode layers, each second electrode layer having at least one support member connecting a corresponding first electrode layer, the second electrode layer, together with a portion of the insulating layer and the first electrode layers, forming an acoustic flow channel, the acoustic flow channel having an inlet, the second electrode layer having a front section adjacent to the inlet and a rear section, the front section facing the inner surface of the acoustic flow channel and forming a gradually expanding first arc surface along the acoustic flow direction of the acoustic flow channel, the rear section facing the inner surface of the acoustic flow channel, extending continuously from the surface of the first arc surface and forming a gradually contracting second arc surface along the acoustic flow direction.

[0013] Preferably, the first electrode layer is composed of at least one electrode layer, the number of electrode layers is equal to the number of supports of the second electrode layer, and the cross-sectional area of ​​the electrode layer is not less than the cross-sectional area of ​​the support.

[0014] Preferably, the second electrode layer has two supports, and the supports have a through hole between them.

[0015] Preferably, the junction of the front section and the rear section is located at the center of the support member that is relatively close to the inlet.

[0016] Preferably, the silicon substrate is made of silicon, silicon germanium, silicon carbide, glass substrate, or a III-V compound substrate.

[0017] Preferably, the insulating layer is made of silicon oxide, silicon nitride, silicon oxynitride, a dielectric material with a dielectric constant between 2.5 and 3.9, or a dielectric material with a dielectric constant less than 2.5.

[0018] Preferably, both the first electrode layer and the second electrode layer are made of conductive material.

[0019] Preferably, the conductive material is a metal, a metal compound, or a semiconductor material doped with ions.

[0020] On the other hand, an embodiment of this application proposes a microphone, characterized in that it includes: a housing having a first stack area, a second stack area, and a third stack area, the second stack area being located between the first stack area and the third stack area, the first stack area, the second stack area, and the third stack area together forming an accommodating space, the housing having a sound hole; a aforementioned microelectromechanical system acoustic sensor located within the accommodating space, the entrance of the acoustic flow channel facing the sound hole; and an integrated circuit chip electrically connected to the microelectromechanical system acoustic sensor and located within the accommodating space.

[0021] Preferably, the second stack area has a perforation radially toward the accommodating space to form the sound hole.

[0022] Preferably, the third stack area has a through hole axially facing the accommodating space to form the sound hole.

[0023] In another aspect, the present application provides a method for manufacturing a microelectromechanical system (MEMS) acoustic sensor, characterized by comprising: providing a substrate; forming at least one insulating layer on the substrate; forming two first electrode layers on the insulating layer, the first electrode layers being spaced apart from each other; disposing a first sacrificial layer on the insulating layer and the first electrode layers, and forming at least one first groove on the first sacrificial layer above the first electrode layers, the first grooves exposing at least a portion of the top surface of the first electrode layers; disposing a second sacrificial layer on the first sacrificial layer and the first grooves, forming two second grooves spaced apart on the second sacrificial layer, and connecting the second grooves to at least one corresponding first groove to form two groove spaces; filling the groove spaces with a material to form two second electrode layers; and removing all the first and second sacrificial layers, and forming an acoustic flow channel between the first electrode layers and the second electrode layers.

[0024] Preferably, the substrate includes a silicon base layer, the material of which is silicon, silicon germanium, silicon carbide, glass substrate, or group III-V compound semiconductor.

[0025] Preferably, the first sacrificial layer and the second sacrificial layer respectively comprise silicon nitride, silicon oxide, and thick photoresist.

[0026] Preferably, the insulating layer is made of silicon oxide, silicon nitride, silicon oxynitride, a low dielectric constant material with a dielectric constant of 2.5 to 3.9, or an ultra-low dielectric constant material with a dielectric constant of less than 2.5.

[0027] Preferably, the first electrode layer is made of metals, metal compounds, or semiconductor materials doped with ions, such as gold, nickel, platinum, palladium, iridium, titanium, chromium, tungsten, aluminum, or copper.

[0028] Preferably, the material forming the second electrode layer is a charged polymer material or a conductive polymer material.

[0029] Preferably, the second electrode layer is formed by processes such as electroforming, injection molding, or 3D printing.

[0030] Preferably, an over-etching method is used to connect the second groove with at least one corresponding first groove to form the groove space.

[0031] Preferably, the etching method for over-etching and removing all the first and second sacrificial layers is a dry etching process or a wet etching process.

[0032] Preferably, all sidewalls forming the groove space are perpendicular to the insulating layer.

[0033] Preferably, the groove space is formed and each sidewall is away from the acoustic flow channel. A first arc surface that gradually expands along the acoustic flow direction of the acoustic flow channel is formed. Then, a second arc surface that gradually narrows is formed by continuously extending from the surface of the first arc surface. After removing all the first sacrificial layers and the second sacrificial layers, a wing-shaped second electrode layer is formed.

[0034] The microphone, microelectromechanical system acoustic sensor, and manufacturing method described in this application have the following characteristics: achieving the effects of improved sensitivity and high directivity. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a side view of the microelectromechanical system acoustic sensor of the first embodiment provided in this application;

[0037] Figure 2 This is a top view of the microelectromechanical system acoustic sensor of the first embodiment provided in this application;

[0038] Figure 3 This is a top view of the microelectromechanical system acoustic sensor of the second embodiment provided in this application;

[0039] Figure 4 This is a side view of the microelectromechanical system acoustic sensor according to the third embodiment provided in this application;

[0040] Figure 5 This is a top view of the microelectromechanical system acoustic sensor of the third embodiment provided in this application;

[0041] Figure 6 This is a side view of the microphone provided in this application;

[0042] Figure 7 This is a state diagram showing the direction of sound flow when the microphone provided in this application is in use;

[0043] Figures 8A to 8F This is a side cross-sectional view of the manufacturing method of the acoustic sensor of a conventional microphone;

[0044] Figure 9A , Figure 9D , Figure 9G , Figure 9I and Figure 9K This is a side cross-sectional view of the manufacturing method of the microelectromechanical system acoustic sensor provided in this application;

[0045] Figure 9B , Figure 9E , Figure 9H , Figure 9J and Figure 9L This is a front cross-sectional view of the method for manufacturing the acoustic sensor for a microelectromechanical system provided in this application;

[0046] Figure 9C This is a perspective view of the method for manufacturing a microelectromechanical system acoustic sensor provided in this application, with a first photomask covering the first sacrificial layer;

[0047] Figure 9F This is a perspective view of the method for manufacturing a microelectromechanical system acoustic sensor provided in this application, with a second photomask covering the second sacrificial layer;

[0048] Figure 9M This is a perspective view of another embodiment of the method for manufacturing a microelectromechanical system acoustic sensor provided in this application. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0050] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0051] Please refer to Figure 1 This is a side view of a first embodiment of the microelectromechanical system acoustic sensor provided in this application, including: a silicon substrate 1, at least one insulating layer 2, two first electrode layers 3 and two second electrode layers 4. The insulating layer 2 is disposed above the silicon substrate 1, the first electrode layers 3 are disposed above the insulating layer 2, and the second electrode layers 4 are respectively disposed above the first electrode layers 3.

[0052] In this embodiment, the material of the silicon substrate 1 can be silicon (Si), silicon germanium (SiGe), silicon carbide (SiC), glass substrate, or group III-V compound semiconductor (e.g., gallium nitride (GaN) or gallium arsenide (GaAs)).

[0053] The insulating layer 2 is disposed above the silicon substrate 1. In this embodiment, the insulating layer 2 can be formed of silicon oxide, silicon nitride, silicon oxynitride, or other dielectric materials. The dielectric material can be a low dielectric constant material (dielectric constant falling between 2.5 and 3.9) or an ultra-low dielectric constant material (dielectric constant less than 2.5).

[0054] In this embodiment, the first electrode layer 3 may be made of a conductive material such as a metal, a metal compound, or a semiconductor material doped with ions. The first electrode layers 3 are respectively disposed above the insulating layer 2 and are spaced apart and aligned with each other.

[0055] In this embodiment, the second electrode layer 4 can also be made of conductive materials such as metal, metal compound, or semiconductor material doped with ions. The second electrode layer 4 is disposed above the first electrode layer 3, wherein the second electrode layer 4 has at least one support member 41 connected to the corresponding first electrode layer 3.

[0056] Please refer to Figure 2 This is a top view of a first embodiment of the microelectromechanical system acoustic sensor provided in this application. The two first electrode layers 3, a portion of the insulating layer 2, and the second electrode layer 4 together form an acoustic flow channel C1. The acoustic flow channel C1 has an inlet E1 and an outlet E2 at its two ends. The second electrode layer 4 has a front section 4a adjacent to the inlet E1 and a rear section 4b adjacent to the outlet E2. The front section 4a faces away from the outer surface of the acoustic flow channel C1 and forms a gradually expanding first arc surface along the acoustic flow direction D of the acoustic flow channel C1. The rear section 4b faces away from the outer surface of the acoustic flow channel C1, extends continuously from the surface of the first arc surface, and forms a gradually narrowing second arc surface along the acoustic flow direction D. On the other hand, the front section 4a and the rear section 4b each face the inner surface of the acoustic flow channel C1 and can be formed as a plane or a curved surface, but are not limited thereto.

[0057] Please continue reading. Figure 1 The second electrode layer 4 can have one or more support members 41. When there are multiple support members 41, there is a through hole H between any two support members 41. For example, when there are two support members 41, there is a through hole H between the support members 41, and the junction of the front segment 4a and the rear segment 4b is located at the center of the support member 41 that is closer to the inlet E1.

[0058] Please refer to Figure 3 This is a top view of a second embodiment of the microelectromechanical system acoustic sensor provided in this application. Compared to the first embodiment, the front segment 4a faces the inner surface of the acoustic flow channel C1 and forms a gradually expanding first arc surface along the acoustic flow direction D of the acoustic flow channel C1. The rear segment 4b faces the inner surface of the acoustic flow channel C1, extends continuously from the surface of the first arc surface, and forms a gradually narrowing second arc surface along the acoustic flow direction D. On the other hand, the front segment 4a and the rear segment 4b each face away from the outer surface of the acoustic flow channel C1 and can form a plane or a curved surface, but are not limited thereto.

[0059] Please refer to Figure 4 , 5 The images show a side view and a top view of a third embodiment of the microelectromechanical system acoustic sensor provided in this application. Compared to the first embodiment, the first electrode layer 3 is composed of at least one electrode layer 3', the number of electrode layers 3' is equal to the number of support members 41 of the second electrode layer 4, and the cross-sectional area of ​​the electrode layer 3' is not less than the cross-sectional area of ​​the support member 41. For example, when the number of support members 41 of each of the second electrode layers 4 is two, the total number of electrode layers 3' is four.

[0060] In the above embodiment, by forming an expanding arc surface in the front section 4a of the second electrode layer 4 and a contracting arc surface in the rear section 4b of the second electrode layer 4, when the sound source passes through, the second electrode layer 4 can be made to sway relative to each other, causing the spacing between the two electrode layers 4 to change, thereby changing the capacitance value, and causing the sound source to eventually converge to the tail end of the second electrode layer 4.

[0061] Please refer to Figure 6 The following is a side view of the microphone provided in this application, including: a housing 5, the aforementioned microelectromechanical system acoustic sensor, and an integrated circuit chip 6, wherein the microelectromechanical system acoustic sensor and the integrated circuit chip 6 are respectively disposed inside the housing 5.

[0062] The housing 5 has a first stacking area 5a, a second stacking area 5b, and a third stacking area 5c, with the second stacking area 5b located between the first stacking area 5a and the third stacking area 5c. The first stacking area 5a, the second stacking area 5b, and the third stacking area 5c together form an accommodating space S1. In this embodiment, the first stacking area 5a can be made of a conductive material or a printed circuit board, and the second stacking area 5b and the third stacking area 5c can be made of various plastics, metals, ceramics, bakelite, fiberglass, or other ceramic materials. Furthermore, the second stacking area 5b and the third stacking area 5c can be designed to be separate from each other or integrally formed.

[0063] The housing 5 has a sound hole 51 and a sound exhaust hole 52. The sound hole 51 allows external sound to enter the accommodating space S1, and the sound exhaust hole 52 exhausts sound from inside the housing 5 to prevent echoes from occurring within the housing 5 and thus affecting the microphone's performance. In this embodiment, according to the sound flow direction D of the sound flow channel C1, a through hole is radially formed from the second stack area 5b toward the accommodating space S1, penetrating the left and right surfaces of the corresponding second stack area 5b to form the sound hole 51, with the sound hole 51 facing the entrance E1 of the sound flow channel C1.

[0064] In another embodiment, a through hole can be axially formed in the third stack area 5c toward the accommodating space S1, penetrating the upper and lower surfaces of the corresponding third stack area 5c to form the sound hole 51, with the sound hole 51 facing the entrance E1 of the acoustic flow channel C1. It is worth noting that in this embodiment, the orientation of the microelectromechanical system acoustic sensor must be such that the entrance E1 of the acoustic flow channel C1 faces the third stack area 5c, so that the formed sound hole 51 can face the entrance E1.

[0065] On the other hand, another through hole can be radially formed from the second stack area 5b toward the accommodating space S1, penetrating the left and right surfaces of the corresponding second stack area 5b to form the sound exhaust hole 52; or another through hole can be axially formed from the third stack area 5c toward the accommodating space S1, penetrating the upper and lower surfaces of the corresponding third stack area 5c to form the sound exhaust hole 52. Preferably, the sound exhaust hole 52 is located on the opposite side of the sound hole 51.

[0066] Please refer to Figure 7This diagram illustrates the sound flow direction during the use of the microphone provided in this application. When the microphone is in use, the sound source enters the accommodating space S1 through the sound hole 51. A portion of the sound source passes through the sound flow channel C1, while another portion travels along the outer surface of the second electrode layer 4, propagating away from the sound hole 51. Furthermore, the sound sources propagating along the outer surface of the second electrode layer 4 ultimately converge at the tail end of the second electrode layer 4 (the portion of the rear section 4b furthest from the front section 4a). Consequently, the outer surface of the second electrode layer 4, compared to the inner surface, experiences a faster airflow speed and lower pressure, allowing the second electrode layer 4 to vibrate relatively, thereby improving the sensitivity and high directivity of the microelectromechanical system acoustic sensor provided in this application.

[0067] Please refer to Figures 9A to 9M The images show a side view, a front view, and a perspective view of the manufacturing method of the microelectromechanical system acoustic sensor provided in this application.

[0068] exist Figure 9A , 9B In this embodiment, a substrate 10 is provided. The thickness of the substrate 10 is between 400 micrometers (μm) and 500 micrometers, but is not limited thereto. Specifically, the substrate 10 includes a silicon substrate, the material of which may be silicon (Si), silicon germanium (SiGe), silicon carbide (SiC), a glass substrate, or a III-V compound semiconductor (e.g., gallium nitride (GaN) or gallium arsenide (GaAs)).

[0069] At least one insulating layer 20 is formed on the substrate 10. In this embodiment, the number of insulating layers 20 is a single layer, and the thickness of the insulating layer 20 is between 300 nanometers (nm) and 600 nanometers, but is not limited thereto. The insulating layer 20 may be formed of silicon oxide, silicon nitride, silicon oxynitride, or other dielectric materials. The dielectric material may be a low dielectric constant material (dielectric constant falling between 2.5 and 3.9) or an ultra-low dielectric constant material (dielectric constant less than 2.5).

[0070] Specifically, the insulating layer 20 can be deposited on the substrate 10 through a deposition process, which can be an atomic layer deposition (ALD), a chemical vapor deposition (CVD), a plasma chemical vapor deposition (PECVD), a molecular beam epitaxy (MBE), or a liquid phase epitaxy (LPE), but is not limited thereto.

[0071] exist Figure 9BIn this embodiment, two first electrode layers 30 are formed above the insulating layer 20. The first electrode layers 30 are arranged at intervals and have a first thickness T1. In this embodiment, the first thickness T1 can be between 300 nanometers and 600 nanometers. Specifically, the first electrode layers 30 can be made of conductive materials such as metals, metal compounds, or semiconductor materials doped with ions, such as gold (Au), nickel (Ni), platinum (Pt), palladium (Pd), iridium (Ir), titanium (Ti), chromium (Cr), tungsten (W), aluminum (Al), or copper (Cu), but are not limited thereto. Furthermore, a conductive material layer can be deposited and formed above the insulating layer 20 through processes such as evaporation, sputtering, chemical vapor deposition (CVD), physical vapor deposition (PVD), electroplating, electroforming, or atomic layer deposition.

[0072] Next, a patterning process is performed on the conductive material layer. For example, a photolithography process can be used, in which photoresist is coated on the surface of the conductive material layer, and then photomask, exposure, development and etching processes are applied to form the first electrode layer 30.

[0073] On the other hand, the conductive material layer can be etched through an etching process such as a dry etching process or a wet etching process. For example, the dry etching process can be an inductively coupled plasma etching (ICP), a reactive ion etching (RIE), a neutron beam etching (NBE), or an electron cyclotron resonance etching (ECR).

[0074] exist Figure 9C , 9D In 9E, a first sacrificial layer 40 is disposed above the insulating layer 20 and the first electrode layer 30. The first sacrificial layer 40 has a second thickness T2. In this embodiment, the first sacrificial layer 40 may contain semiconductor materials such as silicon nitride, silicon oxide and thick photoresist. The second thickness T2 may be between 1 micrometer and 10 micrometers.

[0075] After the first sacrificial layer 4 is laid out, photoresist (not shown in the figure) can be directly applied over the first sacrificial layer 40, and then covered with a first photomask M1. After exposure and development, the photoresist at the positions where at least one first groove G1 is to be formed above the first electrode layer 30 is cleared, and the first sacrificial layer 40 is subjected to the above-described etching process. Then, the remaining photoresist is removed, so that the first sacrificial layer 40 forms the first groove G1 above the first electrode layer 30, and exposes at least a portion of the top surface of the first electrode layer 30. Furthermore, the result of the patterning process of the first sacrificial layer 40 can be as follows: Figure 9D and 9E As shown. The number of first grooves G1 located above the first electrode layer 30 is two, but not limited to this.

[0076] exist Figure 9F , 9G In step 9H, a second sacrificial layer 50 is disposed above the first sacrificial layer 40 and the first groove G1. Two second grooves G2 are formed on the second sacrificial layer 50 at intervals, and the second grooves G2 are respectively connected to at least one corresponding first groove G1 to form a two-groove space S2. The second sacrificial layer 50 has a third thickness T3. In this embodiment, the second sacrificial layer 50 may also contain semiconductor materials such as silicon nitride, silicon oxide and thick photoresist. The third thickness T3 may be between 5 micrometers and 10 micrometers. Furthermore, all sidewalls forming the groove space S2 may be substantially perpendicular to the insulating layer 20.

[0077] Specifically, during the deployment of the second sacrificial layer 50, a portion of the second sacrificial layer 50 is filled into the first groove G1. Subsequently, photoresist can be directly applied over the second sacrificial layer 50, and then a second photomask M2 is placed on top. Furthermore, after development, the photoresist at the location where the second groove G2 will be formed is cleared, and the aforementioned etching process is performed to form the second groove G2. Finally, the location of the second groove G2 is etched using an over-etching method, so that the first groove G1 is connected to the corresponding second groove G2, thereby forming the two-groove space S2. It is worth noting that the result of the second sacrificial layer 50 after the patterning process can be as follows: Figure 9G and 9H As shown.

[0078] It is worth noting that in other embodiments, after adjusting the thickness of the first sacrificial layer 40, only the first sacrificial layer 40 can be formed, and the second groove G2 and the first groove G1 can be formed sequentially with the second photomask M2 and the first photomask M1 to form the groove space S2. In other words, it is not necessary to form the second sacrificial layer 50 separately.

[0079] exist Figure 9I and 9J In this embodiment, the material used to form the electrode layer can be filled into the tank space S2 through processes such as vapor deposition, sputtering, electroplating, electroforming, injection molding, or 3D printing to form two second electrode layers 60. In this embodiment, the material used to form the second electrode layer 60 can be made of conductive materials such as metals, metal compounds, or semiconductor materials doped with ions, such as gold (Au), nickel (Ni), platinum (Pt), palladium (Pd), iridium (Ir), titanium (Ti), chromium (Cr), tungsten (W), aluminum (Al), or copper (Cu). It can also be a charged polymer material (such as electret) or a conductive polymer material, but is not limited thereto.

[0080] exist Figure 9K , 9L In the aforementioned etching process, all the first sacrificial layers 40 and 50 are removed, and an acoustic flow channel C2 is formed between the first electrode layer 30 and the second electrode layer 60. The acoustic flow channel C2 is used to position the sound hole of a microphone. This completes the fabrication of the microelectromechanical system (MEMS) acoustic sensor of the present invention. It is worth noting that in the fabrication method of the MEMS acoustic sensor of the present invention, a photomask is used for each of the formation of the first electrode layer 30, the first sacrificial layer 40, and the second sacrificial layer 50. That is, in this embodiment, at least three photomasks are used in total, which has the advantages of fewer photomasks, fewer process steps, and improved process yield.

[0081] exist Figure 9MIn another embodiment, the sidewalls forming the groove spaces S2 and facing the acoustic flow channel C2 are generally perpendicular to the insulating layer 20, and the sidewalls forming the groove spaces S2 and facing away from the acoustic flow channel C2 can each form a gradually expanding first arc surface along the acoustic flow direction Z of the acoustic flow channel C2, and then continuously extend from the surface of the first arc surface to form a gradually contracting second arc surface. By filling the groove spaces S2 with the material forming the electrode layers, and then removing all the first sacrificial layers 40 and 50, a wing-shaped second electrode layer 60 can be formed. Thus, the outer surface of the second electrode layer 60, compared to the inner surface, has a faster airflow velocity and lower pressure, allowing the second electrode layer 60 to relatively oscillate, thereby improving the sensitivity and high directivity of the finished microelectromechanical system acoustic sensor.

[0082] The microelectromechanical system acoustic sensor manufacturing method described in this application uses an etching solution to remove all the first sacrificial layer 40 and the second sacrificial layer 50 during the aforementioned etching process, making it easier for the etching solution to flow in and out and less likely to remain there. Furthermore, the thickness of the first sacrificial layer 40 and the second sacrificial layer 50 can be adjusted in advance so that the second electrode layer 60 will not be too thin due to over-etching after the etching process, which would make it prone to breakage. This achieves the effects of simplifying the manufacturing process and extending the service life of the finished product.

[0083] As stated above, the microphone, microelectromechanical system acoustic sensor, and manufacturing method thereof described in this application can achieve the effects of improving sensitivity and having high directivity.

[0084] It is understood that the foregoing embodiments are merely illustrative examples of the present invention. Provided that the technical features do not conflict, the structure is not contradictory, and the purpose of the invention is not violated, the technical solutions of the various embodiments can be arbitrarily combined and used.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A microelectromechanical system acoustic sensor, characterized in that, include: A silicon substrate; At least one insulating layer is disposed above the silicon substrate; Two first electrode layers are respectively disposed above the insulating layer and are aligned with each other at intervals; and Two second electrode layers are respectively disposed above the first electrode layer. The second electrode layer has at least one support member connected to the corresponding first electrode layer. The second electrode layer, together with part of the insulating layer and the first electrode layer, forms an acoustic flow channel. The acoustic flow channel has an inlet. The second electrode layer has a front section and a rear section adjacent to the inlet. The front section faces away from the outer surface of the acoustic flow channel and forms a gradually expanding first arc surface along the acoustic flow direction of the acoustic flow channel. The rear section faces away from the outer surface of the acoustic flow channel, extends continuously from the surface of the first arc surface, and forms a gradually contracting second arc surface along the acoustic flow direction.

2. A microelectromechanical system acoustic sensor, characterized in that, include: A silicon substrate; At least one insulating layer is disposed above the silicon substrate; Two first electrode layers are respectively disposed above the insulating layer and are aligned with each other at intervals; and Two second electrode layers are respectively disposed above the first electrode layer. Each second electrode layer has at least one support member connected to the corresponding first electrode layer. The second electrode layer, together with a portion of the insulating layer and the first electrode layer, forms an acoustic flow channel. The acoustic flow channel has an inlet. The second electrode layer has a front section and a rear section adjacent to the inlet. The front section faces the inner surface of the acoustic flow channel and forms a gradually expanding first arc surface along the acoustic flow direction of the acoustic flow channel. The rear section faces the inner surface of the acoustic flow channel, extends continuously from the surface of the first arc surface, and forms a gradually contracting second arc surface along the acoustic flow direction.

3. The microelectromechanical system acoustic sensor as described in claim 1 or 2, characterized in that, The first electrode layer is composed of at least one electrode layer, the number of electrode layers is equal to the number of supports of the second electrode layer, and the cross-sectional area of ​​the electrode layer is not less than the cross-sectional area of ​​the support.

4. The microelectromechanical system acoustic sensor as described in claim 1 or 2, characterized in that, The second electrode layer has two supports, and there is a through hole between the supports.

5. The microelectromechanical system acoustic sensor as described in claim 4, characterized in that, The junction between the front section and the rear section is the center position of the support member located relatively close to the inlet in the support member.

6. The microelectromechanical system acoustic sensor as described in claim 1 or 2, characterized in that, The silicon substrate is made of silicon, silicon germanium, silicon carbide, glass substrate, or group III-V compound semiconductor.

7. The microelectromechanical system acoustic sensor as described in claim 1 or 2, characterized in that, The insulating layer is made of silicon oxide, silicon nitride, silicon oxynitride, a dielectric material with a dielectric constant between 2.5 and 3.9, or a dielectric material with a dielectric constant less than 2.

5.

8. The microelectromechanical system acoustic sensor as described in claim 1 or 2, characterized in that, Both the first electrode layer and the second electrode layer are made of conductive materials.

9. The microelectromechanical system acoustic sensor as described in claim 8, characterized in that, The conductive material is a metal, a metal compound, or a semiconductor material doped with ions.

10. A microphone, characterized in that, include: A housing having a first stack area, a second stack area and a third stack area, the second stack area being located between the first stack area and the third stack area, the first stack area, the second stack area and the third stack area together forming an accommodating space, the housing having a sound hole; A microelectromechanical system acoustic sensor as described in any one of claims 1 to 9, located within the accommodating space, wherein the entrance of the acoustic flow channel faces the sound hole; and An integrated circuit chip is electrically connected to the acoustic sensor of the microelectromechanical system and is located within the accommodating space.

11. The microphone as claimed in claim 10, characterized in that, The second stack area has a perforation radially extending toward the accommodating space to form the sound hole.

12. The microphone as claimed in claim 10, characterized in that, The third stack area has a through hole axially facing the accommodating space to form the sound hole.

13. A method for manufacturing an acoustic sensor for a microelectromechanical system, characterized in that, include: Provide a substrate; At least one insulating layer is formed on the substrate; Two first electrode layers are formed above the insulating layer, and the first electrode layers are arranged at intervals between each other. A first sacrificial layer is disposed above the insulating layer and the first electrode layer, and the first sacrificial layer forms at least one first groove above the first electrode layer, the first groove exposing at least a portion of the top surface of the first electrode layer; A second sacrificial layer is disposed above the first sacrificial layer and the first groove, and two second grooves are formed on the second sacrificial layer at intervals, and the second grooves are respectively connected to at least one corresponding first groove to form a two-groove space; A material is filled into the tank space to form two second electrode layers; and all the first and second sacrificial layers are removed, and an acoustic flow channel is formed between the first and second electrode layers. The sidewalls of the formed groove spaces are perpendicular to the insulating layer and the sidewalls of the formed groove spaces are away from the acoustic flow channel. A first arc surface is formed along the acoustic flow direction of the acoustic flow channel, and a second arc surface is formed by continuously extending from the surface of the first arc surface. After removing all the first sacrificial layers and the second sacrificial layers, a wing-shaped second electrode layer is formed.

14. The method for manufacturing a microelectromechanical system acoustic sensor as described in claim 13, characterized in that, The substrate includes a silicon base layer, the material of which is silicon, silicon germanium, silicon carbide, glass substrate, or group III-V compound semiconductor.

15. The method for manufacturing a microelectromechanical system acoustic sensor as described in claim 13, characterized in that, The first sacrificial layer and the second sacrificial layer respectively comprise silicon nitride, silicon oxide and thick photoresist.

16. The method for manufacturing a microelectromechanical system acoustic sensor as described in claim 13, characterized in that, The insulating layer is a dielectric material consisting of silicon oxide, silicon nitride, silicon oxynitride, or a dielectric material with a dielectric constant between 2.5 and 3.9, or a dielectric material with a dielectric constant less than 2.

5.

17. The method for manufacturing a microelectromechanical system acoustic sensor as described in claim 13, characterized in that, The first electrode layer is made of a metal, a metal compound, or a semiconductor material doped with ions.

18. The method for manufacturing a microelectromechanical system acoustic sensor as described in claim 13, characterized in that, The material forming the second electrode layer is a charged polymer material or a conductive polymer material.

19. The method for manufacturing a microelectromechanical system acoustic sensor as described in claim 13, characterized in that, The second electrode layer is formed by electroforming, injection molding, or 3D printing.

20. The method for manufacturing a microelectromechanical system acoustic sensor as described in claim 13, characterized in that, An over-etching method is used to connect the second groove with at least one corresponding first groove to form the groove space.

21. The method for manufacturing a microelectromechanical system acoustic sensor as described in claim 20, characterized in that, The etching method for over-etching and removing all the first and second sacrificial layers is either a dry etching process or a wet etching process.

22. The method for manufacturing a microelectromechanical system acoustic sensor as described in claim 13, characterized in that, All sidewalls forming the groove space are perpendicular to the insulating layer.

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