Fixed-fixed membrane of a microelectromechanical system microphone

Abstract

A fixed-fixed membrane for a microelectromechanical system (MEMS) microphone. In one embodiment, a MEMS acoustic sensor includes a substrate; a membrane parallel to the substrate; and at least one vent formed in the membrane, wherein the at least one vent is a curved opening in the membrane, and wherein the at least one vent is disposed substantially along a length of the membrane.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Application Serial No. 17 / 931783, filed September 13, 2022, entitled "Fixed-Fixed Membrane for Microelectromechanical System Microphone", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates generally to microelectromechanical systems (MEMS) devices, and more specifically to MEMS microphones. Background Technology

[0004] MEMS condenser microphones typically have a diaphragm that forms a variable capacitor with a backplate underneath. Receiving an audible signal causes the diaphragm to vibrate, generating a variable capacitance signal representing the audible signal. This variable capacitance signal can then be amplified, recorded, or otherwise transmitted to another electronic device.

[0005] MEMS microphone diaphragms are typically constructed as membranes consisting of one or more layers. These diaphragms are usually tensioned and fully clamped to, for example, a backplate. However, tensioned and fully clamped diaphragms can exhibit undesirable stiffness, resulting in low compliance and low average to maximum deflection. This, in turn, leads to lower-than-expected sensitivity. Therefore, techniques to improve the sensitivity of MEMS microphones are desired. Summary of the Invention

[0006] One or more aspects of this disclosure are generally directed to MEMS microphones and corresponding methods of use. For example, the MEMS microphone described herein may utilize a tensioned "fixed-fixed" membrane. As used herein, "fixed-fixed" refers to a membrane fixed to a substrate at opposite ends or edges without the use of springs or a fully clamped design. By another example, the MEMS microphone described herein may utilize curved vent slits that narrow the width of the membrane at its center relative to the fixed ends of the membrane, thereby eliminating and / or reducing wrinkling of the membrane.

[0007] By utilizing the fixed-fixed diaphragm described herein, various advantages can be achieved to improve the performance of MEMS microphones. These advantages include, but are not limited to, the following: Higher microphone sensitivity can be achieved, for example, due to higher average deflection, compared to a fully clamped design. The diaphragm described herein can be constructed using a wider variety of shapes, aspect ratio die sizes, etc., compared to existing diaphragms. Clamping force can be increased compared to spring-based designs, resulting in greater robustness. The length of the diaphragm can be defined by the vent holes, rather than by the undercut of oxides and / or other sacrificial materials in the sensing gap between the diaphragm and the backplate, thus reducing the impact of process variations. An elliptical curved vent hole shape can be used, with a beam width at the center smaller than at the edges, thereby reducing and / or eliminating diaphragm wrinkling. Other advantages are also possible.

[0008] In one aspect disclosed herein, a MEMS acoustic sensor includes a substrate, a membrane disposed parallel to the substrate, and at least one vent formed in the membrane. The at least one vent may be a curved and substantially linear opening in the membrane, and the at least one vent may be disposed substantially along the length of the membrane.

[0009] In another aspect disclosed herein, another MEMS acoustic sensor may include a substrate and a polygonal membrane attached to the substrate at a corresponding edge of the membrane. The membrane may have at least one vent hole, which may be a curved and substantially linear opening in the membrane.

[0010] In another aspect disclosed herein, the diaphragm for a MEMS microphone may include a first diaphragm portion configured to flex in response to receiving an acoustic signal. The diaphragm may also include a second diaphragm portion configured to be attached to a substrate. The diaphragm may further include a third diaphragm portion having at least one vent, wherein each of the at least one vent is a bent through-hole in the third diaphragm portion. Each of the at least one vent may have a corresponding generally elliptical hole located at a respective end of each of the at least one vents, and the diaphragm may have a rectangular shape.

[0011] Other embodiments and various examples, scenarios, and implementations are described in more detail below. The following description and accompanying drawings illustrate certain illustrative embodiments of this specification. However, these embodiments only indicate a few of the various ways in which the principles of this specification can be employed. Other advantages and novel features of the described embodiments will become apparent from the following description when considered in conjunction with the accompanying drawings. Attached Figure Description

[0012] Non-limiting embodiments of this disclosure are described with reference to the following accompanying drawings, in which the same reference numerals denote the same parts in the various views unless otherwise stated:

[0013] Figure 1A This is a top perspective view depicting a packaged microphone having a MEMS microphone die 16 configured according to various embodiments of the present disclosure.

[0014] Figure 1B It is a description Figure 1A The image shows a bottom perspective view of the packaged microphone.

[0015] Figure 1C It is a description of Figure 1A The image shows a cross-sectional view of a directional packaged microphone.

[0016] Figure 1D It is a cross-sectional view depicting a similarly packaged microphone with a bottom port.

[0017] Figure 2 This is a cross-sectional perspective view depicting an exemplary MEMS microphone according to various embodiments of the present disclosure.

[0018] Figure 3 This is a diagram depicting a fixed-fixed membrane for a MEMS microphone according to various embodiments of the present disclosure.

[0019] Figure 4 This is a cross-sectional view depicting the layers of a MEMS microphone diaphragm according to various embodiments of the present disclosure.

[0020] Figure 5 It is a description Figure 3 Top perspective view of a quarter section of the membrane shown.

[0021] Figure 6 This is an enlarged view depicting the end of a vent formed in a MEMS microphone diaphragm according to various embodiments of the present disclosure.

[0022] Figures 7A to 7C This is a diagram depicting various MEMS microphone diaphragm configurations that can be used according to various embodiments of the present disclosure. Detailed Implementation

[0023] Referring now to the accompanying drawings, various views of an exemplary MEMS microphone assembly are provided. It should be noted that the drawings are not drawn to scale, either within a single drawing or between different drawings.

[0024] Figure 1AA top perspective view of a packaged microphone 10 is schematically shown, which can be combined with a MEMS microphone die 16 configured according to various embodiments of the present disclosure (such as...). Figure 1C , 1D (As shown in the other dies discussed below). In a corresponding manner, Figure 1B A bottom perspective view of the same packaged microphone 10 is shown schematically.

[0025] Figures 1A to 1B The packaged microphone 10 shown has a package base 12 and a corresponding cover 14, forming an inner cavity containing a microphone die 16, and, if desired, also includes a separate microphone circuit chip 18 (dies 16 and 18 are in...). Figure 1C and 1D (Illustrated schematically and discussed below). In this embodiment, the cover 14 is a cavity cover having four walls that extend generally orthogonally from the top inner surface to form a cavity. In one embodiment, the cover 14 is formed of metal or other conductive material to shield the microphone die 16 from electromagnetic interference. The cover 14 is fixed to the top surface of a generally flat encapsulation base 12 to form an inner cavity.

[0026] The cover 14 also has an audio input port 20, which allows audio signals to enter the cavity. However, in an alternative embodiment, the audio port 20 is located in another location, such as through the encapsulation base 12 or through one of the sidewalls of the cover 14. The audio signal entering the cavity interacts with the microphone die 16 to generate an electrical signal, which, together with additional (external) components (such as a speaker and accompanying circuitry), produces an output audible signal corresponding to the input audible signal.

[0027] Figure 1B The bottom surface 22 of the package base 12 is shown, having a plurality of contacts 24 for electrically connecting (or physically connecting in some embodiments) the microphone die 16 to a substrate (such as a printed circuit board or other electrical interconnect device). The packaged microphone 10 can be used in any of a variety of applications. For example, the packaged microphone 10 can be used with mobile phones, landline telephones, computer equipment, video games, hearing aids, hearing instruments, biometric security systems, two-way radios, public address systems, and other signal conversion devices. Furthermore, the packaged microphone 10 can also be intended to be used as a speaker to generate an audible signal from electronic signals.

[0028] In some embodiments, Figure 1A and Figure 1BThe package base 12 shown can be a printed circuit board material, such as FR-4, or a pre-molded leadframe type package (also known as a "pre-molded package"). Other embodiments may use different package types, such as ceramic cavity packages. Therefore, the discussion of specific package types is for illustrative purposes only.

[0029] Figure 1C Schematic illustration of crossing Figure 1A A cross-sectional view of the packaged microphone 10 of the line CC. As shown and described above, the cover 14 and the base 12 form an inner cavity for housing the MEMS microphone die 16 and the electronics 18 for controlling and driving the microphone die 16. In an exemplary embodiment, the electronics are implemented as a second independent integrated circuit, such as an application-specific integrated circuit (ASIC) 18. However, other embodiments may form the MEMS microstructure and electronic circuitry on a single chip.

[0030] Adhesive or other fastening mechanisms secure the microphone die 16 and the ASIC die 18 to the base 12. Wiring electrically connects the microphone die 16 and the ASIC die 18 to contact pads (not shown) inside the package base 12 and to each other.

[0031] Although Figures 1A to 1C A top-port encapsulated microphone design is shown, but some embodiments place the input port in other locations, such as through base 12. For example, Figure 1D A schematic cross-sectional view of a similarly packaged microphone 10 is shown, wherein the microphone die 16 covers the input port, resulting in a large back volume. Other embodiments, not shown, position the microphone die 16 so that it does not cover the input port 20 passing through the base 12.

[0032] The discussion of microphones with specific packages is for illustrative purposes only. Therefore, regarding... Figures 1A to 1D The encapsulated microphone 10 discussed is not intended to limit all embodiments of this disclosure.

[0033] Next reference Figure 2 A cross-sectional perspective view of an exemplary MEMS microphone 200 is provided. Figure 2 As shown, the stationary portion of microphone 200 has a backplate 32, which, together with diaphragm 50, forms a variable capacitor. As those skilled in the art will know, the variable capacitor generates an electrical signal representing an input acoustic signal incident on diaphragm 50. For ease of operation, the backplate 32 may have multiple through-holes (also referred to herein as backplate holes or simply holes) that open into the back cavity. The shape, size, and configuration of the holes can optimize performance.

[0034] In one implementation method Figure 2The membrane 50 shown may be deposited on and / or otherwise coupled to other parts of the acoustic sensor below, such as the backplate 32, the substrate (e.g., referred to below). Figure 3 The substrate 60 described above, etc. According to the embodiment, the substrate can be positioned relative to the film 50 on either side of the back plate 32. Thus, for example, the substrate can be located between the back plate 32 and the film 50 (forming a film-substrate-back plate stack), or the substrate can be placed opposite the film 50 (forming a film-back plate-substrate stack).

[0035] Figure 2 The backplate 32 shown may be composed entirely or partially of polycrystalline silicon and / or another conductive material. By using a conductive material in the backplate, electrode patterning can be performed within the film 50 rather than on the backplate 32 and / or other parts of the acoustic sensor below (e.g., as shown in the following reference). Figure 3 (The person described). For example... Figure 2 As further shown, the film 50 can be composed of multiple layers, for example, three layers consisting of a conductive layer located between two non-conductive (e.g., silicon nitride) layers, except for the contact region 34 between the conductive portion of the backplate 32 and the film 50. See below for reference. Figure 4 A more detailed description of membrane 50 and its corresponding layers.

[0036] like Figure 2 As further shown, portions of the backplate 32 may have corresponding recesses 36 or other protrusions extending outward toward the diaphragm 50. In one embodiment, the height of the recess 36 may be determined to satisfy the mAOP associated with the microphone 200. Figure 2 As further shown, portions of the backplate 32 and / or membrane 50 may be attached to the handle (block) 40 used to manufacture the microphone 200.

[0037] Next reference Figure 3 A schematic diagram 300 is provided, depicting a fixed-fixed membrane 50 for a MEMS acoustic sensor (e.g., a MEMS microphone), also simply referred to herein as a membrane. For brevity, repeated descriptions of similar elements used in other embodiments described herein are omitted. See also... Figure 3 As shown in the following figures, it should be noted that the term "membrane" is used to describe structural elements equivalent to the vibrating membrane 30 described above. It should also be noted that when used to describe corresponding structures, the terms "membrane" and "vibrating membrane" can be based on the operational state of the structure. For example, the term "membrane" can be used to indicate that the corresponding structure is under tension, while the term "vibrating membrane" can be used to indicate that the same structure is in a static state (i.e., not under tension). However, it should also be noted that in some cases, the terms "membrane" and "vibrating membrane" can be used interchangeably herein.

[0038] As shown in schematic diagram 300, film 50 is attached to the underlying substrate 60 and / or another suitable device surface. The techniques by which film 50 can be attached to substrate 60 are described in more detail below. Although film 50 is shown attached to substrate 60 in Figure 300, it should be noted that in some embodiments, film 50 may not be directly attached to substrate 60. For example, film 50 may be attached to a backplane (e.g., as described above regarding...). Figure 2 The backplate 32 has an optional spacer material placed between the film 50 and the backplate. The backplate can then be attached to the substrate 60, with another optional spacer material placed between the backplate and the substrate 60. Other implementations are also possible.

[0039] As further shown in Figure 300, the membrane 50 can have a basically rectangular shape, that is, such that the perimeter of the membrane 50 has two longer sides and two shorter sides. The membrane 50 can also adopt other shapes, which will be referred to below. Figures 7A to 7C Some examples are described in more detail below. Membrane 50 may consist of one or more layers, for example, as will be referred to below. Figures 4 to 5 Each layer may be solid and / or have corresponding holes or other openings (e.g., as referred to above). Figure 2 The aperture 38 is used to adjust the low-frequency corner of the relevant acoustic sensor, improve airflow through the membrane 50, and / or for other purposes.

[0040] The membrane 50 shown in Figure 300 can conceptually be divided into three membrane portions. The first portion 302 of the membrane 50, also referred to herein as the sensing region or electrode, can be configured to sense the deflection of the membrane 50 in response to receiving an acoustic signal, for example, as described above regarding... Figures 1A to 1D As further shown in FIG300, the periphery of electrode 25 is defined by electrode trench 52 embedded in membrane 50. Electrode trench 52 may also terminate at electrical contact 54, which may be embedded and / or otherwise attached to substrate 60, backplate and / or other suitable surfaces, as will be described in further detail below.

[0041] In one embodiment, electrode 302 may be positioned as shown in FIG. 300, i.e., substantially at the center of membrane 50. This may be done, for example, to maximize the distance between electrode 302 and the edge of membrane 50, which in turn can improve acoustic sensitivity due to a higher capacitance change associated with the displacement of membrane 50 at the region of electrode 302. As further shown in FIG. 300, electrode 302 may exhibit curvature on one or more sides relative to the edge of membrane 50, for example, to follow the displacement profile of membrane 50 caused by vents 70 formed in the membrane, as described below. Regarding the example shown in FIG. 300, it should be noted that electrode 302 shown in FIG. 300 is for illustrative purposes only, and other electrode shapes and / or sizes may be implemented.

[0042] As further shown in FIG300, the second portion 304 of the membrane 50 may be configured to attach the membrane 50 to the substrate 60. In one embodiment, the second portion 304 of the membrane 50 may include anchors, adhesives, and / or any other suitable means for permanently attaching the membrane 50 to the substrate 60. In another embodiment, the size and / or shape of the membrane 50 may allow the second portion 304 of the membrane 50 to attach the edge of the membrane 50 to the substrate 60 while leaving a gap, such as an air gap, between the membrane 50 and the substrate 60 in the effective area of ​​the membrane 50 to facilitate full displacement of the membrane 50 in response to an acoustic signal.

[0043] In the embodiment shown in FIG. 300, the second portion 304 of the membrane 50 may extend along the entire periphery of the membrane 50, including all edges of the membrane 50. In an alternative embodiment, the second portion 304 of the membrane 50 may attach the membrane 50 to the substrate 60 along less than all edges of the membrane 50 (e.g., longer edges, shorter edges, etc.). In another alternative embodiment, the second portion 304 of the membrane 50 may be discontinuous along the periphery of the membrane 50, for example, such that the membrane 50 is attached to the substrate 60 at discrete points along the periphery of the membrane 50. Other embodiments are also possible.

[0044] As further shown in Figure 300, the third portion 306 of the membrane 50 includes at least one vent 70, which is an opening formed in the first portion 306 of the membrane 50 and is disposed substantially along the length of the membrane 50. In the example shown in Figure 300, the membrane 50 has two vents 70, each positioned along a corresponding edge of the longer side of the membrane 50. It should be noted that the vents 70 may be positioned relative to the membrane 50 in other ways, for example, along the shorter side of the membrane, along all sides of the membrane, etc. Refer below to... Figures 7A to 7C Alternative techniques for positioning the vent 70 within a rectangular membrane and for positioning the vent 70 within a non-rectangular membrane are described in more detail.

[0045] In the embodiment shown in FIG. 300, the vent 70 is a curved opening in the membrane 50. In the example shown in FIG. 300, the vent 70 is a semi-elliptical opening, that is, an opening exhibiting a curved shape forming part of an ellipse. These openings are also positioned such that the principal axis of the ellipse corresponding to the shape of the vent 70 is positioned along the edge of the membrane 50.

[0046] Because of the vent 70 shown in FIG. 300, the effective area of ​​the membrane 50 (e.g., the first portion 302 of the membrane 50) is a non-rectangular area, the width of which at the center of the first portion 302 is smaller than the width of the short edge of the membrane 50, which is attached to the short edge. When tension is applied to the short edge of the membrane 50, this causes the first portion 302 of the membrane 50 to take on a hammock-like shape, for example, the end of the first portion 302 is pulled open and the center of the first portion 301 is suspended. Furthermore, due to the curvature of the vent 70 shown in FIG. 300, wrinkling of the membrane 50 under tension can be reduced compared to embodiments using straight (non-curved) vents.

[0047] By using a diaphragm 50 with vents 70 as shown in Figure 300, the compliance of the diaphragm 50 can be improved, which in turn can improve the sensitivity of the acoustic sensor below. Furthermore, the vents 70 allow air to flow from the front to the rear of the acoustic sensor below, which can be used to make the diaphragm 50 function as a microphone and to set its corresponding low-frequency angle.

[0048] Now for reference Figure 4 It provides a depiction of a MEMS microphone diaphragm 50 (e.g. Figure 2 The diagram shows cross-sectional views of each layer of the membrane 50 shown. For brevity, repeated descriptions of similar elements used in other embodiments described herein have been omitted. Figure 4 As shown, the film 50 can typically consist of three layers, including a conductive layer 410 located between two non-conductive layers 420. In one embodiment, the conductive layer 410 can be made of polycrystalline silicon, and the non-conductive layer 420 can be made of silicon nitride. Other compositions are also possible.

[0049] Figure 4 The illustrated film 50 may include one or more electrode trenches 52, wherein the conductive (polysilicon) layer 410 is removed, leaving only a non-conductive (silicon nitride) layer 420 at the location of the trench 52. This can be achieved, for example, by electrically isolating the sensing region of the film 50 from the non-sensing region of the film 50.

[0050] like Figure 4 As further shown, the vent 70 formed in the membrane 50 can be a complete opening through the membrane 50, for example, such that all layers of the membrane 50 are removed at the location of the vent 70. As described above, for example, refer to Figure 3Completely removing the membrane material at the vent 70 position can improve the compliance of the membrane 50, thereby increasing the acoustic sensitivity by increasing the deflection of the sensing area of ​​the membrane 50.

[0051] Figure 5 Figure 500 shows a top perspective view of an example membrane having layers similar to those shown in Figure 400 (i.e., conductive layer 410 and non-conductive layer 420), wherein the top non-conductive layer 420 has been removed for illustrative purposes. It is noteworthy that, for simplicity, Figure 500 shows only a portion of the complete membrane, for example, a quarter of the membrane. As shown in Figure 500, the region of the membrane unrelated to the vent 70 or electrode trench 52 has the conductive layer 410 beneath the top non-conductive layer 420. Figure 500 further shows that all layers of the membrane are removed in the region of the vent 70, and no material corresponding to the conductive layer 410 is deposited in the region corresponding to the electrode trench 52, i.e., the trench 52 is entirely composed of the non-conductive layer 420.

[0052] Next, turn to Figure 6 Figure 600 provides an enlarged view of the end 610 of the vent 70 formed in the MEMS microphone diaphragm 50. For brevity, repeated descriptions of similar elements used in other embodiments described herein are omitted. More specifically, Figure 600 shows as follows: Figure 3 Figure 300 shows an enlarged view of the end portion of the vent 70. As shown in Figure 600, the vent 70 terminates at a generally elliptical (circular, elliptical, nearly elliptical, etc.) hole or opening 610. As further shown in Figure 600, the diameter of the opening 610 (e.g., large diameter, small diameter, etc.) can be larger than the width of the corresponding vent 70, for example, making the opening 610 at the end of the vent 70 wider than the vent 70 itself. As shown in Figure 600, by terminating the vent 70 with a larger opening 610, the mechanical stress applied to the end of the vent 70 can be distributed over a larger area (e.g., the area of ​​the opening 610), thereby increasing the stress tolerance of the membrane 50.

[0053] Although Figure 600 shows only a single opening 610 of a single vent 70, it should be noted that the opening 610 shown in Figure 600 can be placed at the respective ends of each vent 70 formed in a given membrane 50. Thus, for example, the vent 70 shown in Figure 300 can each terminate at both ends of the vent 70 at the opening 610 shown in Figure 600.

[0054] Next reference Figures 7A to 7CFigures 700, 702, and 704 are provided to depict various MEMS microphone diaphragm configurations. While the various examples above relate to specific examples of rectangular diaphragms, the diaphragms described herein can be any suitable polygon, such as quadrilaterals (e.g., squares, rectangles, etc.), hexagons, octagons, etc. For example, in Figure 7A In the example shown in Figure 700, a square membrane 710 can be used, wherein corresponding curved vent holes 70 can be provided along opposite sides of the membrane 710, for example, in the case of a rectangular membrane as described above. As further shown in Figure 700, additional straight vent holes 720 can be provided along the sides of the membrane 710 that are not related to the curved vent holes 70.

[0055] like Figure 7B In another example shown in Figure 702, the hexagonal membrane 712 may have three curved vents 70 positioned along the alternating edges of the membrane 712. Similarly, as... Figure 7C The octagonal membrane 714 shown in Figure 704 can have four curved vent holes 70, which are similarly positioned along the alternating edges of the membrane 714. In general, for a polygonal membrane with an even number of n edges, n / 2 vent holes 70 can be formed in the membrane and located on the alternating edges of the membrane, i.e., every other side of the membrane.

[0056] Throughout this specification, the terms "an embodiment" or "an embodiment" refer to a specific feature, structure, or characteristic associated with that embodiment being included in at least one implementation. Therefore, the phrases "in one embodiment" or "in one implementation" appearing in various places within this specification do not necessarily refer to the same embodiment. Furthermore, in one or more embodiments, specific features, structures, or characteristics may be combined in any suitable manner.

[0057] Furthermore, in this specification, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless otherwise stated or the context clearly indicates otherwise, "X uses A or B" is intended to mean any natural inclusive arrangement. That is, if X uses A; X uses B; or X uses both A and B, then in any of the above cases, "X uses A or B" is true. Additionally, the articles "a" and "an" used in this specification and figures should generally be interpreted as "one or more" unless otherwise stated or the context clearly indicates the singular form.

[0058] Furthermore, the terms “example” and “for example” are used herein to indicate that something is an instance or illustration. Any embodiment or design described herein as an “example” or associated with a “for example” clause is not necessarily to be construed as superior to other embodiments or designs. Rather, the terms “example” or “for example” are used to present concepts in a specific manner. Unless the context clearly indicates otherwise, the terms “first,” “second,” and “third,” etc., used in the claims and specification are for clarity only and do not necessarily indicate or imply any chronological order.

[0059] The foregoing includes examples of one or more embodiments of this disclosure. Of course, in order to describe these examples, it is impossible to describe every possible combination of components or methods, and it will be appreciated that many other combinations and arrangements of this embodiment are possible. Therefore, the embodiments disclosed and / or claimed herein are intended to include all such changes, modifications, and variations falling within the spirit and scope of the detailed description and the appended claims. Furthermore, if the word “comprising” is used in the detailed description or claims, it is intended to be inclusive in a manner similar to “comprising,” as “comprising” is interpreted as “including” when used as a transitional word in a claim.

Claims

1. A microelectromechanical system (MEMS) acoustic sensor, comprising: substrate; A membrane, parallel to the substrate and having at least four sides corresponding to the attachment edges of the membrane; as well as At least one vent is formed in the membrane, wherein a portion of the at least one vent is a curved opening in the membrane, wherein the at least one vent is disposed substantially along one side of the at least four sides of the membrane, wherein at least a portion of the at least one vent is curved, and wherein the main axis of the at least one vent is along the side of the membrane.

2. The microelectromechanical system acoustic sensor according to claim 1, wherein, The membrane has a rectangular shape.

3. The microelectromechanical system acoustic sensor according to claim 2, wherein, The at least one vent includes two vents, wherein the two vents are disposed substantially along the respective sides of the two longer sides of the at least four sides of the membrane.

4. The microelectromechanical system acoustic sensor according to claim 2, wherein, Each of the at least four sides of the membrane is attached to the substrate.

5. The microelectromechanical system acoustic sensor according to claim 1, wherein, The at least one vent includes at least two vents, wherein each of the at least two vents is curved, and wherein the main axis of the respective vent is along the respective side of the at least four sides of the membrane.

6. A microelectromechanical system (MEMS) acoustic sensor, comprising: substrate; The membrane is parallel to the substrate; as well as At least one vent is formed in the membrane, wherein a portion of the at least one vent is a curved opening in the membrane, wherein the at least one vent is disposed substantially along one side of the membrane, wherein each of the at least one vent has a first end and a second end opposite to the first end, and wherein each of the at least one vent includes a corresponding substantially elliptical hole located at the first end and the second end.

7. The microelectromechanical system acoustic sensor according to claim 6, wherein, The diameter of each of the basic elliptical holes is greater than the width of each of the at least one vent hole.

8. The microelectromechanical system acoustic sensor according to claim 6 further comprises: A backplate, parallel to the membrane, and covering at least a portion of the membrane.

9. The microelectromechanical system acoustic sensor according to claim 8, wherein, The substrate is located between the back plate and the membrane.

10. The microelectromechanical system acoustic sensor according to claim 8, wherein, The backplate is located between the substrate and the membrane.

11. A microelectromechanical system (MEMS) acoustic sensor, comprising: substrate; The membrane is parallel to the substrate; as well as At least one vent is formed in the membrane, wherein a portion of the at least one vent is a curved opening in the membrane, wherein the at least one vent is disposed substantially along one side of the membrane, wherein the membrane includes a sensing region comprising a polycrystalline silicon layer located between two silicon nitride layers, wherein the membrane also includes a non-sensing region, and wherein the sensing region and the non-sensing region are isolated by at least one of the two silicon nitride layers.

12. The microelectromechanical system acoustic sensor according to claim 11, wherein, At least a portion of the periphery of the sensing area has a curved shape.

13. A microelectromechanical system (MEMS) acoustic sensor, comprising: substrate; A membrane having a polygonal shape and having at least four sides corresponding to the edges of the membrane, attached to the substrate at the respective edges of the membrane, wherein the membrane has at least one vent hole, the at least one vent hole being a curved opening in the membrane, wherein at least a portion of the at least one vent hole is curved, and wherein the main axis of the at least one vent hole is along one side of the at least four sides of the membrane.

14. The microelectromechanical system acoustic sensor according to claim 13, wherein, The polygonal shape of the membrane is selected from the group consisting of quadrilateral, hexagonal and octagonal shapes.

15. The microelectromechanical system acoustic sensor according to claim 13, wherein, The at least one vent includes a plurality of vents, wherein a corresponding vent among the plurality of vents is positioned along alternating edges of the at least four sides of the membrane.

16. The microelectromechanical system acoustic sensor according to claim 13, wherein, Each of the at least one vent has a first end and a second end opposite to the first end, and wherein each of the at least one vent includes a corresponding generally elliptical hole located at the first end and the second end.

17. The microelectromechanical system acoustic sensor according to claim 16, wherein, The diameter of each of the basic elliptical holes is greater than the width of each of the at least one vent hole.

18. A diaphragm for a microelectromechanical system (MEMS) microphone, comprising: The first membrane portion is configured to flex in response to receiving an acoustic signal; The second membrane portion is configured to be attached to the substrate; as well as The third membrane portion has at least one vent, wherein each of the at least one vent is a curved through-hole in the third membrane portion, and wherein each of the at least one vent has a corresponding generally elliptical hole located at a corresponding end of each of the at least one vent.

19. The membrane according to claim 18, wherein, The corresponding vent of the at least one vent is at least partially semi-elliptical, and wherein the principal axis of the corresponding vent of the at least one vent is along the corresponding edge of the membrane.

20. The membrane according to claim 18, wherein, The diameter of each of the basic elliptical holes is greater than the width of each of the at least one vent hole.

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