Microelectromechanical system microphone

Abstract

The present application provides a kind of micro electro mechanical system microphone, comprising: substrate, with first cavity;One dielectric layer is arranged on the substrate, with the first side of the substrate and the second side opposite to the first side, wherein the dielectric layer has the second cavity corresponding to the first cavity;Diaphragm is located in the second cavity, including joint area, sensing area and elastic structure, wherein the joint area is connected with the dielectric layer, the sensing area includes peripheral area and central area, the peripheral area is connected with the central area by the elastic structure, the elastic structure has first gap on the side close to central area, the elastic structure has second gap on the side close to peripheral area;And first back plate is arranged on the dielectric layer, located on the second side of the dielectric layer, wherein the first back plate includes a plurality of acoustic holes communicated with the second cavity, wherein the vibration efficiency of the sound radiation of the diaphragm is greater than or equal to 50%.

Description

Technical Field

[0001] This invention relates to a microelectromechanical system (MEMS) microphone. Background Technology

[0002] Microelectromechanical System (MEMS) microphones are commonly used devices in electronic devices for sensing acoustic signals (such as voice signals in communication). The function of a MEMS microphone in sensing acoustic signals is based on the influence of air pressure on a diaphragm from an acoustic signal of a certain frequency. This diaphragm vibrates in accordance with the frequency and amplitude of the acoustic signal, resulting in a change in capacitance. This capacitance change is sensed and output by a circuit, and then the acoustic signal is converted into an electrical signal for subsequent applications in peripheral electronic devices.

[0003] Therefore, by changing the shape characteristics of the diaphragm, such as diaphragm thickness, diaphragm size, and spring width, the sensing performance of a microelectromechanical system (MEMS) microphone can be effectively improved. Summary of the Invention

[0004] This invention provides a microelectromechanical system (MEMS) microphone, comprising: a substrate having a first cavity; a dielectric layer disposed on the substrate, having a first side connected to the substrate and a second side opposite to the first side, wherein the dielectric layer has a second cavity corresponding to the first cavity; a diaphragm located within the second cavity, including a bonding region, a sensing region, and an elastic structure, wherein the bonding region is connected to the dielectric layer, the sensing region includes a peripheral region and a central region, the peripheral region and the central region are connected by the elastic structure, the elastic structure has a first gap on the side near the central region, and the elastic structure has a second gap on the side near the peripheral region; and a first backplate disposed on the dielectric layer, located on the second side of the dielectric layer, wherein the first backplate includes a plurality of sound holes communicating with the second cavity, and wherein the vibration efficiency of the diaphragm's sound radiation is greater than or equal to 50%.

[0005] According to an embodiment of the present invention, a microelectromechanical system microphone is provided, wherein the following relationship is satisfied:

[0006] , where r is the outer radius of the peripheral region and w is the width of the elastic structure in the radial direction of the diaphragm.

[0007] According to an embodiment of the present invention, when the thickness of the diaphragm ranges from 0.7 μm to 1.3 μm, the following relationship is satisfied: if 350 μm ≤ D ≤ 450 μm, then w ≥ 3.7 μm; or if 450 μm ≤ D ≤ 650 μm, then w ≥ 16.4 μm; or if 650 μm ≤ D ≤ 950 μm, then w ≥ 23.5 μm; or if 950 μm ≤ D ≤ 1200 μm, then w ≥ 33.3 μm, where D is the outer diameter of the peripheral region (twice the outer radius r of the peripheral region), and w is the width of the elastic structure in the radial direction of the diaphragm.

[0008] According to an embodiment of the present invention, when the thickness of the diaphragm is in the range of 1.3 μm to 1.9 μm, the following relationship is satisfied: if 650 μm ≤ D ≤ 950 μm, then w ≥ 19 μm; or if 950 μm ≤ D ≤ 1200 μm, then w ≥ 40 μm, where D is the outer diameter of the peripheral region and w is the width of the elastic structure in the radial direction of the diaphragm.

[0009] According to an embodiment of the present invention, when the thickness of the diaphragm is in the range of 1.9 μm to 2.6 μm, the following relationship is satisfied: if 650 μm ≤ D ≤ 950 μm, then w ≥ 21 μm; or if 950 μm ≤ D ≤ 1250 μm, then w ≥ 29.4 μm, where D is the outer diameter of the peripheral region and w is the width of the elastic structure in the radial direction of the diaphragm.

[0010] According to an embodiment of the present invention, there are multiple elastic structures, and the multiple elastic structures are symmetrical with respect to the central region.

[0011] According to an embodiment of the present invention, the first gap is either straight or curved in the circumferential direction of the diaphragm.

[0012] According to an embodiment of the present invention, the second gap is either straight or curved in the circumferential direction of the diaphragm.

[0013] According to an embodiment of the present invention, the distance between the diaphragm and the first backplate is 2.8 to 5.5 micrometers.

[0014] According to an embodiment of the present invention, the bonding region is located between the substrate and the dielectric layer.

[0015] According to an embodiment of the present invention, the dielectric layer is provided with a sidewall facing the second cavity, and the sidewall surrounds the second cavity.

[0016] According to an embodiment of the invention, the bonding region is in contact with the sidewall of the dielectric layer.

[0017] According to an embodiment of the present invention, the microelectromechanical system microphone further includes: a second back plate, the second back plate being disposed on the opposite side of the first back plate with respect to the diaphragm, wherein the second back plate includes a plurality of second sound holes connected to a second cavity.

[0018] According to an embodiment of the present invention, the vertical distance between the diaphragm and the first back plate is a first spacing, and the vertical distance between the diaphragm and the second back plate is a second spacing. The first spacing ranges from 1.6 μm to 3.6 μm, and the second spacing ranges from 1.6 μm to 3.6 μm.

[0019] According to an embodiment of the present invention, the first spacing is equal to the second spacing.

[0020] According to an embodiment of the present invention, the first spacing is not equal to the second spacing.

[0021] Based on the above, by changing the shape characteristics of the diaphragm, such as diaphragm thickness, diaphragm size, and spring width, the sensing performance of the microelectromechanical system microphone can be effectively improved. Attached Figure Description

[0022] When with attachment Figure 1 When reading this invention, the various aspects thereof can be best understood from the following detailed description. It is worth noting that, in accordance with industry standard practice, the various features are not drawn to scale. In fact, for clarity of discussion, the dimensions of the various features may be increased or decreased arbitrarily.

[0023] Figure 1 This is a schematic diagram of a microelectromechanical system microphone according to an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of a diaphragm according to an embodiment of the present invention;

[0025] Figure 3 This is a simulated numerical relationship between spring width and diaphragm efficiency for different diaphragm diameters when the diaphragm thickness is 0.8 μm, according to an embodiment of the present invention.

[0026] Figure 4 This is a simulated numerical relationship between spring width and diaphragm efficiency for different diaphragm diameters when the diaphragm thickness is 1.6 μm, according to an embodiment of the present invention.

[0027] Figure 5 This is a simulated numerical relationship between spring width and diaphragm efficiency for different diaphragm diameters when the diaphragm thickness is 2.4 μm, according to an embodiment of the present invention.

[0028] Figure 6 This is a schematic diagram of a microelectromechanical system microphone according to an embodiment of the present invention;

[0029] Figure 7 This is a schematic diagram of a microelectromechanical system microphone according to an embodiment of the present invention. Detailed Implementation

[0030] The following detailed description, in conjunction with the accompanying drawings, provides examples of embodiments, but these embodiments are not intended to limit the scope of the invention. Furthermore, the component dimensions in the accompanying drawings are for illustrative purposes and do not represent actual component size proportions. Moreover, although terms such as "first," "second," etc., are used herein to describe different components and / or membranes, these components and / or membranes should not be limited by these terms. Rather, these terms are used only to distinguish one component or membrane from another. Therefore, the first component or membrane discussed below may be referred to as the second component or membrane without departing from the teachings of the embodiments. For ease of understanding, similar components will be designated with the same symbols in the following description.

[0031] In the description of embodiments of the present invention, different examples may use repeated reference numerals and / or words. These repeated numerals or words are for simplification and clarity purposes and are not intended to limit the relationship between the various embodiments and / or appearance structures. Furthermore, if the following description of the invention describes forming a first feature on or above a second feature, it indicates that it includes embodiments where the formed first feature and the second feature are in direct contact, and also includes embodiments where an additional feature is formed between the first feature and the second feature, such that the first feature and the second feature may not be in direct contact. For ease of understanding, similar components will be referred to by the same symbols in the following description.

[0032] Figure 1 This is a schematic diagram of a microelectromechanical system microphone according to an embodiment of the present invention. Figure 2 This is a schematic diagram of a diaphragm according to an embodiment of the present invention.

[0033] Please refer to this first. Figure 1 The microelectromechanical system microphone 100 includes: a substrate 102, a dielectric layer 108, a diaphragm 112, and a first backplate 114.

[0034] The substrate 102 has a first cavity 104 for allowing gas to flow in. In some embodiments, the substrate 102 is made of silicon. In some embodiments, the openings at both ends of the first cavity 104 are of equal size. In some embodiments, the gas inlet surface of the first cavity 104 ( Figure 1 The opening at the bottom is smaller than the opening at the other end.

[0035] A dielectric layer 108 is disposed on a substrate 102, having a first side 108A in contact with the substrate 102 and a second side 108B opposite to the first side 108A. The dielectric layer 108 has a second cavity 110 corresponding to the first cavity 104. In some embodiments, the dielectric layer 108 is made of silicon dioxide or a material with similar properties; this disclosure is not limited thereto. In some embodiments, the openings at both ends of the second cavity 110 are of equal size. In some embodiments, the opening of the second cavity 110 adjacent to the first cavity 104 is smaller than the opening of the second cavity 110 away from the first cavity 104. In some embodiments, the opening of the second cavity 110 adjacent to the first cavity 104 is larger than the opening of the second cavity 110 away from the first cavity 104.

[0036] like Figure 1 As shown, an oxide layer 106 is also included between the substrate 102 and the dielectric layer 108 to protect the surface of the substrate 102 or to electrically isolate the diaphragm 112 from the substrate 102. In some embodiments, the oxide layer 106 is an amorphous silicon dioxide thin film.

[0037] To illustrate the structure of diaphragm 112, please also refer to... Figure 1 and Figure 2 ,in Figure 2 This is a schematic diagram of a diaphragm according to an embodiment of the present invention.

[0038] The diaphragm 112 is located within the second cavity 110. Specifically, in Figure 1 In this embodiment, the diaphragm 112 is located between the substrate 102 and the dielectric layer 108. In other embodiments, the diaphragm 112 may be disposed in other areas of the second cavity 110 as needed, and this disclosure is not limited thereto.

[0039] In some embodiments, the diaphragm 112 is made of polycrystalline silicon. In some embodiments, the thickness 112d of the diaphragm 112 is 0.8 to 3.0 micrometers (μm), preferably 1.6 to 2.4 micrometers. In other embodiments, the thickness of the diaphragm 112 may also be other values, and this disclosure is not limited thereto.

[0040] Specifically, by using a diaphragm 112 with a larger thickness, such as 0.8 to 3.0 micrometers, the rigidity of the diaphragm 112 can be increased. The main displacement of the diaphragm 112 is driven by the elastic structure 58 described below. The thicker the diaphragm 112, the more consistent the displacement of the diaphragm itself when sensing sound pressure, thus improving the sensing efficiency.

[0041] The diaphragm 112 includes a bonding region 50, a sensing region 52, and an elastic structure 58. The bonding region 50 is in contact with the dielectric layer 108 to fix the diaphragm 112 onto the dielectric layer 108. In this embodiment, the bonding region 50 is located between the substrate 102 and the dielectric layer 108.

[0042] The sensing area 52 includes a peripheral area 54 and a central area 56. The peripheral area 54 and the central area 56 are connected by an elastic structure 58. Specifically, the sensing area 52 is used to sense air vibrations transmitted by the first cavity 104 to sense sound pressure.

[0043] like Figure 2 As shown, there are multiple elastic structures 58, which are symmetrical about the center of the central region 56. The elastic structures 58 are arranged sequentially in a clockwise or counter-clockwise direction relative to the center of the central region 56. Specifically, the number of elastic structures 58 is related to the thickness 112d of the diaphragm 112. The greater the thickness 112d of the diaphragm 112, the fewer the number of elastic structures 58. Furthermore, the number of elastic structures 58 is also related to the diameter of the diaphragm 112. The larger the diameter of the diaphragm 112, the more elastic structures 58 are present.

[0044] The elastic structure 58 has a first gap 60 on the side near the central region 56 and a second gap 62 on the side near the peripheral region 54. The first gap 60 and the second gap 62 are connected by a connecting portion 64. Therefore, the elastic structure 58 defined by the first gap 60, the second gap 62, and the connecting portion 64 is also called a cantilever spring. In addition to increasing the ability of the diaphragm 112 to sense air vibrations, the elastic structure 58 also makes the diaphragm 112 vibrate easily without easily breaking or damaging it. The first gap 60, the second gap 62, and the connecting portion 64 are formed by etching.

[0045] like Figure 2 As shown, the first gap 60 has a straight shape in the circumferential direction of the diaphragm 112. However, in other embodiments, the first gap 60 may also have a curved shape in the circumferential direction. For example... Figure 2 As shown, the second gap 62 has a straight shape in the circumferential direction of the diaphragm 112. However, in other embodiments, the second gap 62 may also have a curved shape in the circumferential direction. Therefore, the shape of the elastic structure 58 can be more flexible in design.

[0046] In this embodiment, as Figure 1As shown, the widths 60w of the first gap 60 and 62w of the second gap 62 are determined according to the minimum width of the manufacturing process or the requirements for venting or depressurization, depending on the process conditions, but are not limited thereto. In some embodiments, the widths 60w of the first gap 60 and 62w of the second gap 62 are the same. In some embodiments, the width 60w of the first gap 60 is greater than the width 62w of the second gap 62. In some embodiments, the widths 60w of the first gap 60 and 62w of the second gap 62 are greater than or equal to 1 / 3 of the thickness of the diaphragm 112. In some embodiments, the widths 60w of the first gap 60 and 62w of the second gap 62 are both less than or equal to 1.5 micrometers. In some embodiments, the first gap 60 and the second gap 62 can also serve as vent holes or pressure relief holes for the diaphragm 112, allowing air pressure or sound pressure to enter the second cavity 110 through the first gap 60 and the second gap 62 and dissipate from the sound hole 116.

[0047] like Figure 2 As shown, the first gap 60 and the second gap 62 are connected by a connecting portion 64. Both the first gap 60 and the second gap 62 have a rounded corner 68 on the side not connected to the connecting portion 64. The gap at the rounded corner 68 is slightly larger than the first gap 60 and the second gap 62, so that the elastic structure 58 generates less stress at the rounded corner during displacement deformation, thereby improving reliability. In some embodiments, the gap at the rounded corner 68 can be at least 1 micrometer in diameter, depending on the manufacturing process, but is not limited thereto.

[0048] In order to enable the diaphragm 112 to respond better to air vibrations, in this embodiment of the invention, the vibration efficiency of the sound radiation of the diaphragm 112 is greater than or equal to 50%.

[0049] In an ideal situation, when subjected to air vibration, the displacement of all positions of an ideal diaphragm is at its maximum. At this point, the volume of air that the ideal diaphragm can push is equivalent to the case where the vibration efficiency of the sound radiation from the ideal diaphragm is 1.

[0050] However, the actual diaphragm must be fixed in place to generate vibration, for example in Figure 2In this configuration, the diaphragm 112 is connected to the dielectric layer 108 via a bonding region 50. Therefore, when air vibrates the diaphragm 112, the bonding region 50 does not vibrate; only the peripheral region 54, the elastic structure 58, and the central region 56 vibrate in response to air vibration. When the diaphragm 112 vibrates, the area near the bonding region 50 (e.g., the peripheral region 54) experiences smaller displacement, while the area farther from the bonding region 50 (e.g., the central region 56) experiences larger displacement. Therefore, by integrating all the displacements of the peripheral region 54, the elastic structure 58, and the central region 56, the volume of air propelled by the peripheral region 54, the elastic structure 58, and the central region 56 can be calculated, yielding the vibration efficiency of the sound radiation from the diaphragm 112. When the vibration efficiency of the sound radiation is 50%, it is equivalent to the volume of air propelled by the diaphragm 112 being 50% of the volume of air propelled by an ideal diaphragm of the same area.

[0051] When the air vibrates the diaphragm 112, the vibration of the diaphragm 112 mainly occurs in the central region 56. The larger the area of ​​the central region 56, the more effectively it can react to the air vibration.

[0052] On the other hand, the elastic structure 58 and the peripheral region 54 are used to cause the central region 56 to be displaced. Therefore, the width of the elastic structure 58 will significantly affect the elastic coefficient of the elastic structure and affect the amplitude of the central region 56.

[0053] Therefore, a balance must be struck between the area of ​​the central region 56 and the area of ​​the elastic structure 58 plus the area of ​​the peripheral region 54 in order to optimize the vibration efficiency of the sound radiation of the diaphragm 112.

[0054] This invention defines the following relationship:

[0055] ,

[0056] Where r is the outer radius of the peripheral region 54, and w is the width of the elastic structure 58 in the radial direction of the diaphragm 112, as shown below. Figure 2 As shown in the above formula, since the width of the peripheral region 54 is generally between 0-25 μm, which is much smaller than the width w of the elastic structure 58 in the radial direction of the diaphragm 112, the width of the peripheral region 54 can be ignored.

[0057] Generally, the width of the peripheral region 54 is much smaller than the width of the elastic structure 58 in the radial direction of the diaphragm 112. Therefore, the width of the elastic structure 58 in the radial direction of the diaphragm 112 is used here to replace the total width of the elastic structure 58 plus the peripheral region 54. And (rw) is equivalent to the radius of the central region 56.

[0058] Based on the above relationship, it can be seen that in the diaphragm 112 of the present invention, the area of ​​the central region 56 must be at least 50% of the sum of the area of ​​the peripheral region 54, the elastic structure 58, and the central region 56, in order to ensure the area of ​​the central region 56.

[0059] According to the simulation results, when the diaphragm 112 meets this condition, the vibration efficiency of the sound radiation of the diaphragm 112 is greater than or equal to 50%.

[0060] To enable the diaphragm 112 to respond better to air vibrations, the width 58w of the elastic structure 58 and the thickness 112d of the diaphragm 112 must be within a certain range to maintain high sound conversion efficiency and ensure sufficient rigidity of the diaphragm 112. Therefore, when the diaphragm 112 has different thickness ranges, the outer diameter D of the peripheral region 54 and the width w of the elastic structure 58 in the radial direction of the diaphragm 112 better satisfy the following relationship.

[0061] When the thickness 112d of the diaphragm 112 ranges from 0.7μm to 1.3μm, the following relationship is satisfied: if 350μm ≤ D ≤ 450μm, then w ≥ 3.7μm; or if 450μm ≤ D ≤ 650μm, then w ≥ 16.4μm; or if 650μm ≤ D ≤ 950μm, then w ≥ 23.5μm; or if 950μm ≤ D ≤ 1200μm, then w ≥ 33.3μm.

[0062] When the thickness 112d of the diaphragm 112 is in the range of 1.3μm to 1.9μm, the following relationship is satisfied: if 650μm ≤ D ≤ 950μm, then w ≥ 19μm; or if 950μm ≤ D ≤ 1200μm, then w ≥ 40μm.

[0063] When the thickness 112d of the diaphragm 112 ranges from 1.9μm to 2.6μm, the following relationship is satisfied: if 650μm ≤ D ≤ 950μm, then w ≥ 21μm; or if 950μm ≤ D ≤ 1250μm, then w ≥ 29.4μm.

[0064] Figure 3 , Figure 4 and Figure 5 The figures shown are simulated numerical relationships between spring width and diaphragm efficiency for different diaphragm diameters when the diaphragm thickness is 0.8 μm, 1.6 μm, and 2.4 μm, respectively, according to embodiments of the present invention.

[0065] exist Figure 3 In the simulation, when the diaphragm thickness is 0.8 μm, the numerical relationship between spring width and diaphragm efficiency was plotted for different diaphragm diameters (440 μm, 540 μm, 750 μm, 1050 μm). Figure 4 In the simulation, when the diaphragm thickness is 1.6 μm, the numerical relationship between spring width and diaphragm efficiency was plotted for different diaphragm diameters (540 μm, 750 μm, and 1050 μm). Figure 5 In the simulation, when the diaphragm thickness is 1.6 μm, the simulated numerical relationship between spring width and diaphragm efficiency is shown for different diaphragm diameters (750 μm and 1050 μm).

[0066] like Figure 3 As shown, the larger the spring width, the greater the vibration efficiency of the diaphragm in sound radiation. Through numerical simulation, the relationship between different spring widths and the vibration efficiency of the diaphragm in sound radiation can be obtained. Then, by linear regression, the minimum spring width required when the vibration efficiency of the diaphragm in sound radiation is above 50% can be calculated. Figure 4 and Figure 5 Similar results were also shown.

[0067] For example, in Figure 3 In the study, when the diaphragm thickness is 0.8 μm and the diaphragm diameter is 440 μm, 540 μm, 750 μm, and 1050 μm, respectively, the minimum spring width required for the diaphragm to achieve a sound radiation vibration efficiency of over 50% is 3.7 μm, 16.4 μm, 26.2 μm, and 33.3 μm, respectively.

[0068] For example, in Figure 4 In the study, when the diaphragm thickness is 1.6 μm and the diaphragm diameter is 540 μm, 750 μm, and 1050 μm, the minimum spring width required for the diaphragm to achieve a sound radiation vibration efficiency of over 50% is 3.7 μm, 11.6 μm, and 57.8 μm, respectively.

[0069] For example, in Figure 5 In the case of a diaphragm with a thickness of 2.4 μm and diaphragm diameters of 750 μm and 1050 μm, the minimum required spring widths for a sound radiation vibration efficiency of 22.5 μm and 29.4 μm are respectively when the diaphragm thickness is 2.4 μm and the diaphragm diameters are 750 μm and 1050 μm.

[0070] Please return to Figure 1 The microelectromechanical system (MEMS) microphone 100 also includes a first backplate 114 disposed on a dielectric layer 108 and located on the second side 108B of the dielectric layer 108. The first backplate 114 includes a plurality of acoustic holes 116 communicating with the second cavity 110. Air entering through the first cavity 104, after causing the diaphragm 112 to vibrate, can exit the MEMS microphone 100 through the acoustic holes 116. In some embodiments, the first backplate 114 is made of polycrystalline silicon, but is not limited thereto.

[0071] In some embodiments, the distance d between the diaphragm 112 and the first backplate 114 is 2.8 to 5.5 micrometers, so that there is sufficient space between the diaphragm 112 and the first backplate 114 to allow the diaphragm 112 to vibrate.

[0072] The first backplate 114 also includes a protrusion 119 disposed on the surface of the first backplate 114 facing the diaphragm 112, so as to prevent the first backplate 114 and the diaphragm 112 from sticking to each other.

[0073] The microelectromechanical system microphone 100 also includes a protective layer 118 disposed above the first backplate 114 and between the conductive structures 120A and 120B to protect the surface of the first backplate 114. In some embodiments, the protective layer 118 is made of silicon nitride, but is not limited thereto.

[0074] The microelectromechanical system microphone 100 also includes multiple conductive structures 120A, 120B, and 120C for transmitting electrical signals generated by the vibration of the diaphragm 112. Figure 1 In the illustrated embodiment, conductive structure 120A can serve as a bias pad, electrically connected to the diaphragm 112, and can provide bias voltage to the diaphragm 112. Conductive structure 120B, electrically connected to the first backplate 114, can serve as a sensing output pad to transmit the electrical signals generated by the diaphragm 112. Conductive structure 120C can serve as a grounding pad. The number and configuration of conductive structures 120A, 120B, and 120C can be adjusted according to actual needs and are not limited thereto.

[0075] Figure 6 This is a schematic diagram of a microelectromechanical system microphone according to an embodiment of the present invention. Figure 6 The microelectromechanical system microphone 100B shown is Figure 1 Similar to the microelectromechanical system microphone 100 shown, the difference lies in that the dielectric layer 108 has a sidewall 130 facing the second cavity 110, and the sidewall 130 surrounds the second cavity 110. The sidewall 130 provides sufficient support for the dielectric layer 108, allowing the wet etching process to be performed for a longer time, so as to avoid the dielectric layer 108 collapsing due to the etching solution etching the dielectric layer, thereby affecting the structural stability of the second cavity 110 and the first backplate 114.

[0076] In some embodiments, the bonding region 50 is connected to the sidewall 130 of the dielectric layer 108.

[0077] In some embodiments, the sidewall 130 may be made of polycrystalline silicon, silicon nitride, or a composite structure of polycrystalline silicon and silicon nitride. This disclosure is not limited thereto.

[0078] In some embodiments, the sidewall 130 is further provided with a protective layer (not shown) to protect the sidewall 130.

[0079] Figure 7 This is a schematic diagram of a microelectromechanical system microphone according to an embodiment of the present invention.

[0080] Figure 7 The microelectromechanical system microphone 100C shown is Figure 1 Similar to the microelectromechanical system microphone 100 shown, the difference is that the microelectromechanical system microphone 100E also includes a second back plate 140, which is disposed on the opposite side of the first back plate 114 with respect to the diaphragm 112. The diaphragm 112 is located between the first back plate 114 and the second back plate 140.

[0081] The second back plate 140 includes a plurality of second acoustic holes 144 connected to the second cavity 110, for allowing air passing through the first cavity 104 to enter the diaphragm 112 through the second acoustic holes 144.

[0082] The second backplate 140 also includes a protective layer 142 disposed on both sides of the second backplate 140 to protect one or both sides of the second backplate 140. In some embodiments, the protective layer 142 is made of silicon nitride, but is not limited thereto.

[0083] In this embodiment, the diaphragm 112 also includes a protrusion 113 disposed on the surface of the diaphragm 112 facing the second back plate 140, so as to prevent the second back plate 140 and the diaphragm 112 from sticking to each other during the manufacturing process or use.

[0084] In addition, the microelectromechanical system microphone 100 also includes multiple conductive structures 120A, 120B, 120C, and 120D. Conductive structure 120A can serve as a bias pad, electrically connected to the diaphragm 112, and can provide bias to the diaphragm 112. Conductive structure 120B is electrically connected to the first backplate 114, and conductive structure 120D is electrically connected to the second backplate 140, serving as a sensing output pad for measuring the output voltage between the first backplate 114 and the second backplate 140. Conductive structure 120C can serve as a grounding pad. The number and configuration of conductive structures 120A, 120B, 120C, and 120D can be adjusted according to actual needs and are not limited thereto.

[0085] like Figure 7 As shown, when the microelectromechanical system microphone 100C has a first back plate 114 and a second back plate 140, the vertical distance between the diaphragm 112 and the first back plate 114 is the first spacing d1, and the vertical distance between the diaphragm 112 and the second back plate 140 is the second spacing d2. The range of the first spacing d1 is between 1.6μm and 3.6μm, and the range of the second spacing d2 is between 1.6μm and 3.6μm.

[0086] In some embodiments, the first spacing d1 and the second spacing d2 are equal. In other embodiments, the first spacing d1 and the second spacing d2 are not equal. The invention is not limited thereto.

[0087] In summary, this invention can effectively improve the sensing performance of a microelectromechanical system (MEMS) microphone by changing the shape characteristics of the diaphragm, such as diaphragm thickness, diaphragm size, and spring width.

Claims

1. A microelectromechanical system (MEMS) microphone, characterized in that, include: The substrate has a first cavity; A dielectric layer is disposed on the substrate and has a first side in contact with the substrate and a second side opposite to the first side, wherein the dielectric layer has a second cavity corresponding to the first cavity; A diaphragm, located within the second cavity, includes a bonding region, a sensing region, and an elastic structure. The bonding region is in contact with the dielectric layer. The sensing region includes a peripheral region and a central region. The peripheral region and the central region are connected by the elastic structure. The elastic structure has a first gap on the side near the central region and a second gap on the side near the peripheral region. A first backplate is disposed on the dielectric layer and located on the second side of the dielectric layer, wherein the first backplate includes a plurality of acoustic holes communicating with the second cavity. The vibration efficiency of the sound radiation from the diaphragm is greater than or equal to 50%.

2. The microelectromechanical system microphone according to claim 1, characterized in that, The following relationship must be satisfied: ， Where r is the outer radius of the peripheral region, and w is the width of the elastic structure in the radial direction of the diaphragm.

3. The microelectromechanical system microphone according to claim 2, characterized in that, When the thickness of the diaphragm is in the range of 0.7 μm to 1.3 μm, the following relationship is satisfied: If 350μm ≤ D ≤ 450μm, then w ≥ 3.7μm; or If 450μm ≤ D ≤ 650μm, then w ≥ 16.4μm; or If 650μm ≤ D ≤ 950μm, then w ≥ 23.5μm; or If 950μm ≤ D ≤ 1200μm, then w ≥ 33.3μm. Where D is the outer diameter of the peripheral region, and w is the width of the elastic structure in the radial direction of the diaphragm.

4. The microelectromechanical system microphone according to claim 2, characterized in that, When the thickness of the diaphragm is in the range of 1.3 μm to 1.9 μm, the following relationship is satisfied: If 650μm ≤ D ≤ 950μm, then w ≥ 19μm; or If 950μm ≤ D ≤ 1200μm, then w ≥ 40μm. Where D is the outer diameter of the peripheral region, and w is the width of the elastic structure in the radial direction of the diaphragm.

5. The microelectromechanical system microphone according to claim 2, characterized in that, When the thickness of the diaphragm is in the range of 1.9 μm to 2.6 μm, the following relationship is satisfied: If 650μm ≤ D ≤ 950μm, then w ≥ 21μm; or If 950μm ≤ D ≤ 1250μm, then w ≥ 29.4μm, Where D is the outer diameter of the peripheral region, and w is the width of the elastic structure in the radial direction of the diaphragm.

6. The microelectromechanical system microphone according to claim 1, characterized in that, The elastic structure comprises multiple structures, and the multiple elastic structures are symmetrical about the center region.

7. The microelectromechanical system microphone according to claim 1, characterized in that, The first gap has a straight or curved shape in the circumferential direction of the diaphragm.

8. The microelectromechanical system microphone according to claim 1, characterized in that, The second gap has a straight or curved shape in the circumferential direction of the diaphragm.

9. The microelectromechanical system microphone according to claim 1, characterized in that, The distance between the diaphragm and the first backplate is 2.8 to 5.5 micrometers.

10. The microelectromechanical system microphone according to claim 1, characterized in that, The bonding region is located between the substrate and the dielectric layer.

11. The microelectromechanical system microphone according to claim 1, characterized in that, The dielectric layer has a sidewall facing the second cavity, and the sidewall surrounds the second cavity.

12. The microelectromechanical system microphone according to claim 11, characterized in that, The bonding region is in contact with the sidewall of the dielectric layer.

13. The microelectromechanical system microphone according to claim 1, characterized in that, Also includes: A second backplate is disposed on the opposite side of the first backplate with respect to the diaphragm, wherein the second backplate includes a plurality of second acoustic holes connected to the second cavity.

14. The microelectromechanical system microphone according to claim 13, characterized in that, The vertical distance between the diaphragm and the first back plate is the first spacing, and the vertical distance between the diaphragm and the second back plate is the second spacing. The first spacing is between 1.6 μm and 3.6 μm, and the second spacing is between 1.6 μm and 3.6 μm.

15. The microelectromechanical system microphone according to claim 14, characterized in that, The first spacing is equal to the second spacing.

16. The microelectromechanical system microphone according to claim 14, characterized in that, The first spacing is not equal to the second spacing.

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