Micro electro mechanical system microphone, alloy sealing layer preparation method and electronic equipment

Abstract

The invention discloses a micro electro mechanical system microphone, an alloy sealing layer preparation method and electronic equipment. The MEMS microphone comprises a back electrode and a first vibrating diaphragm, the first vibrating diaphragm and the back electrode are spaced, and the first vibrating diaphragm is provided with a through hole; and the alloy sealing layer is filled in the through hole so as to seal the through hole. The through hole of the first vibrating diaphragm is sealed by the alloy sealing layer, and the alloy sealing layer can fully release stress, so that the problem of fracture failure caused by stress concentration is avoided.

Description

Technical Field

[0001] This invention relates to the field of electronic equipment technology, and more specifically, to a microelectromechanical microphone, a method for preparing an alloy sealing layer, and an electronic device. Background Technology

[0002] In related technologies, for dual-diaphragm microphones, after releasing the sacrificial layer through the release hole of the upper diaphragm, the release hole of the upper diaphragm generally needs to be sealed to reduce the acoustic damping and noise of the MEMS and improve the signal-to-noise ratio (SNR) of the device. Currently, the vias are generally sealed by passivating multilayer thin films of SiO2 / SiNx. However, this film has poor conformal coverage and is not dense at the sealing point, easily forming... Figure 1 The defects shown cause stress concentration, making them prone to cracking.

[0003] Therefore, a new technical solution is needed to solve the above-mentioned technical problems. Summary of the Invention

[0004] One objective of this invention is to provide a new technical solution for a microelectromechanical microphone.

[0005] According to a first aspect of the present invention, a microelectromechanical microphone is provided. The microelectromechanical microphone includes:

[0006] A back electrode and a first diaphragm, the first diaphragm being spaced apart from the back electrode, and the first diaphragm having through holes; and

[0007] An alloy sealing layer is filled into the through hole to seal it.

[0008] Optionally, the alloy sealing layer protrudes from one end of the through hole.

[0009] Optionally, the portion of the alloy sealing layer protruding from the through hole is hemispherical.

[0010] Optionally, the alloy sealing layer comprises at least two metals selected from Al, Ge, Au, In, Si, Sn, Ag, and Cu.

[0011] Optionally, the alloy sealing layer comprises an Al-Ge alloy.

[0012] Optionally, the first diaphragm has a first surface suitable for depositing the alloy sealing layer, and the angle between the inner wall of the through hole and the first surface is an obtuse angle.

[0013] Optionally, the angle between the inner wall of the through hole and the first surface is 95° to 120°.

[0014] Optionally, an alloy adhesion layer is further provided between the alloy sealing layer and the first diaphragm.

[0015] Optionally, it also includes a second diaphragm, wherein a sealed cavity is formed between the first diaphragm and the second diaphragm, and the sealed cavity is filled with a gas with a viscosity coefficient less than that of air.

[0016] According to a second aspect of the present invention, a method for preparing an alloy sealing layer for a microelectromechanical microphone is provided, the method comprising:

[0017] An alloy layer is deposited at one end of the first diaphragm, and the alloy layer is capable of filling the through-hole;

[0018] The alloy layer is patterned to remove excess alloy layer from the surface of the first diaphragm;

[0019] The alloy layer is subjected to liquid phase alloying treatment;

[0020] The liquid phase alloy is cooled to solidify it, thereby forming an alloy sealing layer.

[0021] Optionally, the step of depositing an alloy layer at one end of the first diaphragm, wherein the alloy layer is capable of filling the through-hole, comprises:

[0022] Multiple metal layers are sequentially deposited at one end of the first diaphragm, the metal layers including at least two of Al, Ge, Au, In, Si, Sn, Ag and Cu.

[0023] Optionally, the metal layer includes a Ge layer and an Al layer disposed sequentially, wherein the thickness of the Ge layer is T1 and the thickness of the Al layer is T2, satisfying T1 = (0.59~1)T2.

[0024] Optionally, the thickness of the deposited alloy layer is greater than the inner diameter of the through-hole.

[0025] Optionally, an alloy adhesion layer is deposited between the first diaphragm and the alloy sealing layer.

[0026] Optionally, a sealed cavity is formed between the first diaphragm and the second diaphragm;

[0027] The deposition of an alloy layer at one end of the first diaphragm, wherein the alloy layer is capable of filling the through-hole, includes:

[0028] The alloy layer is provided with an air filling hole, which is connected to the through hole, allowing gas with a viscosity coefficient less than that of air to be filled into the sealed cavity through the air filling hole.

[0029] Optionally, the inner diameter of the air inlet is greater than or equal to 10 nm.

[0030] Optionally, after the gas is filled into the sealed cavity, the alloy layer is subjected to a first liquid phase alloying treatment, thereby sealing the gas filling hole.

[0031] Optionally, after the alloy layer undergoes a first liquid phase alloying treatment, the liquid phase alloy is cooled and solidified, and then the solidified alloy layer is patterned to remove excess alloy layer from the surface of the first diaphragm.

[0032] Optionally, after patterning the alloy layer, a second liquid phase alloying treatment is performed on the alloy layer to form an alloy sealing layer.

[0033] According to another aspect of the present invention, an electronic device is provided. This electronic device includes the microelectromechanical microphone of the above embodiment.

[0034] One technical advantage of this application is that the through hole of the first diaphragm is sealed by an alloy sealing layer, which can release stress more fully, thereby avoiding the problem of cracking and failure due to stress concentration.

[0035] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0036] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0037] Figure 1 This is a diagram of existing technology.

[0038] Figure 2 This is a partial structural schematic diagram of the first diaphragm according to an embodiment of the present invention.

[0039] Figure 3 This is a partial structural schematic diagram of the first diaphragm according to another embodiment of the present invention.

[0040] Figure 4 This is a partial structural schematic diagram of the first diaphragm according to another embodiment of the present invention.

[0041] Figure 5 This is a partial structural schematic diagram of the first diaphragm according to another embodiment of the present invention.

[0042] Figure 6 This is a partial structural schematic diagram of the first diaphragm according to another embodiment of the present invention.

[0043] Figure 7 This is a partial structural schematic diagram of a microelectromechanical microphone according to an embodiment of the present invention.

[0044] Figure 8 This is a partial structural schematic diagram of a microelectromechanical microphone according to another embodiment of the present invention.

[0045] Figure 9 This is a partial structural schematic diagram of a microelectromechanical microphone according to another embodiment of the present invention.

[0046] Figure 10 This is a flowchart of a method for preparing an alloy sealing layer according to an embodiment of the present invention.

[0047] Figure label:

[0048] 1. First diaphragm; 11. Through hole; 12. First surface; 2. Alloy sealing layer; 21. Air inlet; 3. Second diaphragm; 4. Sealing cavity; 5. Back electrode; 6. Support; 7. Substrate; 8. Ge layer; 9. Al layer; 10. Support column. Detailed Implementation

[0049] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0050] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0051] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0052] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0053] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0054] According to one embodiment of this application, a microelectromechanical microphone is provided. For example... Figures 2 to 9 As shown, the microelectromechanical microphone includes a back electrode 5 and a first diaphragm 1, which is spaced apart from the back electrode 5. The first diaphragm 1 has a through hole 11. The microphone also includes an alloy sealing layer 2, which fills the through hole 11 to seal it.

[0055] In this example, the through-hole 11 on the first diaphragm 1 can be used to release the sacrificial layer. After the sacrificial layer is released, the through-hole 11 is sealed to form a low-pressure / vacuum sealed cavity 4 between the first diaphragm 1 and the second diaphragm 3. This reduces the acoustic damping and noise of the microelectromechanical microphone and improves the signal-to-noise ratio (SNR) of the device. The through-hole 11 of the first diaphragm 1 is sealed by an alloy sealing layer 2. The alloy sealing layer 2 can release stress more effectively, thereby avoiding the problem of cracking failure due to stress concentration.

[0056] In this example, an alloy layer is deposited on the surface of the first diaphragm 1, allowing it to fill the through-hole 11. The layer is then patterned to remove excess alloy. The alloy is then liquefied at high temperature, completely filling the through-hole 11 and improving its sealing effect. When the temperature drops to room temperature, the alloy maintains its shape, and stress is sufficiently released, forming the alloy sealing layer 2.

[0057] Alternatively, multiple metal layers can be deposited sequentially on the surface of the first diaphragm 1, filling the via 11. Then, the surface is patterned to remove excess metal layers. The multiple metal layers are then formed into a liquid-phase alloy (or transient liquid-phase alloy) at a high temperature (e.g., the alloy eutectic temperature or the melting point of the first metal layer material) to achieve complete filling and low-stress coverage of the via 11.

[0058] The patterning process includes photolithography and etching, which can be determined by those skilled in the art according to the actual situation, and no specific limitations are made here.

[0059] In this example, the first diaphragm 1 and the back electrode 5 are spaced apart, with a certain gap between them, forming a capacitor structure. Figures 7 to 9 As shown, the first diaphragm 1 has a through hole 11, which is sealed by an alloy sealing layer 2. The first diaphragm 1 is disposed at one end of the support portion 6, the back electrode 5 is mounted on the support portion 6, and the second diaphragm 3 is disposed on the support portion 6, with the back electrode 5 located between the first diaphragm 1 and the second diaphragm 3. The back electrode 5 can form a capacitor structure with the first diaphragm 1 and the second diaphragm 3 respectively. The support portion 6 is made of insulating material, which not only provides support but also ensures insulation between the two diaphragms and the back electrode 5.

[0060] In one example, such as Figure 2 As shown, the alloy sealing layer 2 protrudes from one end of the through hole 11. The alloy sealing layer 2 is positioned to protrude from one end of the through hole 11, that is, it protrudes from the end of the first diaphragm 1 that is away from the sealing cavity 4, thereby ensuring that the through hole 11 is completely filled to improve the sealing effect.

[0061] In this example, such as Figure 2As shown, the portion of the alloy sealing layer 2 protruding from the through hole 11 is hemispherical. One part of the alloy sealing layer 2 fills the through hole 11, while the other part protrudes from the through hole 11. The hemispherical structure of the protruding portion of the alloy sealing layer 2 effectively avoids stress concentration.

[0062] It should be noted that when multiple metal layers are deposited on the surface of the first diaphragm 1 and liquid-phase alloying is performed, the designed alloy composition is uniformly distributed in the alloy body. In a vacuum environment (e.g., at a pressure below 100 Pa), the upper and lower liquid surfaces naturally form curved / spherical surfaces under the action of alloy surface tension. When the temperature drops to room temperature, the alloy maintains its shape, and the stress is fully released, resulting in a low-stress microspherical surface coverage.

[0063] like Figure 3 As shown, in this example, during the sequential deposition of multiple metal layers, the metal layers have vacancy defects on both the upper and lower sides of the via 11. After liquid phase alloying treatment, as... Figure 2 As shown, vacancy defects can be filled.

[0064] In one example, the alloy sealing layer 2 comprises at least two metals selected from Al, Ge, Au, In, Si, Sn, Ag, and Cu.

[0065] like Figure 3 As shown, in this example, the sealing alloy layer comprises Ge and Al, and the alloy sealing layer 2 comprises an Al-Ge alloy. Specifically, a Ge layer 8 can be deposited first on the first surface 12 of the first diaphragm 1, and then an Al layer 9 can be deposited on the surface of the Ge layer 8. The Ge layer 8 and Al layer 9 are then patterned to remove excess Ge layer 8 and Al layer 9. Liquid-phase alloying is then performed in a vacuum environment (pressure below 100 Pa) at a temperature of approximately 420°C, thereby forming a Ge-Al liquid-phase alloy between the Ge layer 8 and Al layer 9.

[0066] In this example, other alloys could be Au-Sn alloys (liquid phase alloying temperature approximately 280℃), Au-In alloys (liquid phase alloying temperature approximately 156℃), Sn-Ag alloys (liquid phase alloying temperature approximately 221℃), Cu-Sn alloys (liquid phase alloying temperature approximately 231℃), etc. A relatively accurate alloy eutectic temperature can be achieved by adjusting the thickness ratio of each metal layer during deposition.

[0067] Of course, the composition of the alloy sealing layer 2 is not limited to the above embodiments. For example, it can also be Au-Sn plus Sn-Ag, etc. Those skilled in the art can determine it according to the actual situation, and no specific limitation is made here.

[0068] In this example, when depositing multiple metal layers sequentially, the metal layer with the higher melting point can be deposited first at the bottom. This is to avoid the upper metal layer having a higher melting point, which would cause the temperature to become too high, resulting in the lower metal layer melting and preventing the two metal layers from being directly liquid-phase alloyed without being patterned.

[0069] In this example, the deposition techniques include PVD (physical vapor deposition, evaporation, sputtering, etc.) and PECVD (plasma-enhanced chemical vapor deposition, etc.). During the deposition process, the gas pressure must be kept below 100 Pa after the sealed cavity 4 cools to room temperature. Al deposition is mainly performed using PVD. Subsequent patterning etching can employ high-precision dry etching (such as RIE, reactive ion etching, etc.) to allow for a smaller diameter of the protrusion in the alloy sealing layer 2, for example, 1 micrometer or even submicrometer diameter.

[0070] In one example, an alloy adhesion layer is also provided between the alloy sealing layer 2 and the first diaphragm 1.

[0071] In this example, before depositing the metal layer, an alloy adhesion layer can be deposited on the surface of the first diaphragm 1 to ensure that the subsequently deposited metal layer is stably adhered to the first diaphragm 1 and to prevent the metal layer from falling off.

[0072] For example, the alloy adhesion layer can be Cr, Ni, Ti, etc. PVD deposition can be performed using evaporation, which can reduce the amount of material entering the sealed cavity 4. Patterning can be done using dry etching methods such as RIE or IBE ion beam etching, or wet etching can also be used.

[0073] Of course, the material of the alloy adhesion layer can be selected according to the specific material of the metal layer, so as to ensure stable adhesion of the metal layer. Those skilled in the art can determine it according to the actual situation, and no specific limitation is made here.

[0074] It should be noted that when the alloy sealing layer 2 is an Al-Ge alloy, the Ge layer 8 is deposited first. The Ge layer 8 can be directly adhered to the surface of the first diaphragm 1, or an adhesion layer can be omitted.

[0075] In one example, such as Figure 2 As shown, the first diaphragm 1 has a first surface 12, which is suitable for depositing the alloy sealing layer 2, and the angle between the inner wall of the through hole 11 and the first surface 12 is an obtuse angle.

[0076] like Figure 2 and Figure 7As shown, in this example, the first diaphragm 1 has a first surface 12 on the side facing away from the sealing cavity 4. An alloy sealing layer 2 is deposited on the first surface 12 and can fill the through-hole 11. Let α be the angle between the inner wall of the through-hole 11 and the first surface 12, where α is an obtuse angle. That is, the first diaphragm 1 has a second surface on the side facing away from the first surface 12, and the inner diameter of the through-hole 11 gradually decreases from the first surface 12 to the second surface. The alloy sealing layer 2 enters from the end with the larger opening of the through-hole 11, so that the alloy sealing layer 2 can be deposited at the bottom of the through-hole 11, thereby improving the sealing effect of the through-hole 11.

[0077] In this example, the deposition near the second surface of the via 11 can be improved by selecting an alloy with a smaller atomic weight to increase the mean free path of atoms during deposition, or by using sputtering with better sidewall coverage to deposit an adhesion layer, thereby reducing or even eliminating vacancy defects at the bottom of the via 11.

[0078] In one example, the angle between the inner wall of the through hole 11 and the first surface 12 is 95° to 120°.

[0079] like Figure 2 As shown, in this example, the value of α can be selected from 95° to 120°, so as to ensure that the alloy sealing layer 2 can be deposited to the bottom of the through hole 11 to improve the sealing effect of the through hole 11, while avoiding the through hole 11 having too large a diameter, which would result in a large vacancy defect in the upper part of the alloy layer when depositing the alloy layer.

[0080] In one example, such as Figures 7 to 9 As shown, the microelectromechanical microphone also includes a second diaphragm 3, and a sealed cavity 4 is formed between the first diaphragm 1 and the second diaphragm 3. The sealed cavity 4 is filled with a gas with a viscosity coefficient less than that of air.

[0081] like Figures 7 to 9 As shown, in this example, the first diaphragm 1 and the second diaphragm 3 are respectively disposed on opposite sides of the support portion 6. A sealed cavity 4 can be formed between the first diaphragm 1 and the second diaphragm 3, and the sealed cavity 4 is filled with a gas with a viscosity coefficient lower than that of air. By filling the sealed cavity 4 with a gas with a viscosity coefficient lower than that of air, the acoustic impedance of the two diaphragms relative to the back electrode 5 can be greatly reduced, thereby reducing the noise of the microelectromechanical microphone. At the same time, using a low-viscosity gas for filling allows the pressure in the sealed cavity 4 to be consistent with the pressure of the external environment, avoiding the diaphragm deflection problem caused by pressure difference and ensuring the performance of the microphone.

[0082] Among them, the gas with a viscosity coefficient less than that of air is at least one of isobutane, propane, propylene, H2, ethane, ammonia, acetylene, ethyl chloride, ethylene, CH3Cl, methane, SO2, H2S, chlorine, CO2, N2O, and N2.

[0083] like Figure 7 As shown, a support column 10 can be connected between the first diaphragm 1 and the second diaphragm 3 to support the two diaphragms. Figure 8 and Figure 9 As shown, when the sealed cavity 4 is filled with a gas whose viscosity coefficient is less than that of air, the pressure difference between the sealed cavity 4 and the outside decreases, or the pressure between the sealed cavity 4 and the outside becomes equal, maintaining balance. The diaphragm will not bulge or collapse. This reduces the need for the support pillar 10 between the two diaphragms, or even eliminates the need for the support pillar 10, thereby improving the sensitivity of the microelectromechanical microphone and ensuring its acoustic performance.

[0084] In one example, such as Figures 2 to 9 As shown, the microelectromechanical microphone also includes a substrate 7, with a back cavity in the central region of the substrate 7. A second diaphragm 3 is disposed on the substrate 7, and the second diaphragm 3 and the substrate 7 are insulated from each other. For example, an insulating layer of a material such as silicon dioxide is provided between the second diaphragm 3 and the substrate 7.

[0085] In one example, the through hole 11 on the first diaphragm 1 of this application can also be sealed with a low melting point glass material, such as a glass material with a melting point of about 300°C.

[0086] According to another embodiment of this application, a method for preparing the alloy sealing layer 2 of a microelectromechanical microphone is provided, the method comprising:

[0087] An alloy layer is deposited at one end of the first diaphragm 1, and the alloy layer is capable of filling the through hole 11;

[0088] The alloy layer is patterned to remove excess alloy layer from the surface of the first diaphragm 1;

[0089] The alloy layer is subjected to liquid phase alloying treatment;

[0090] The liquid phase alloy layer is cooled to solidify it, thereby forming the alloy sealing layer 2.

[0091] In this example, an alloy layer is deposited at one end of the first diaphragm 1, and the alloy layer is capable of filling the via 11. An alloy layer is deposited on the first surface 12 of the first diaphragm 1, and the alloy layer is capable of filling the via 11. Multiple metal layers can be sequentially deposited on the first surface 12 to form the alloy layer, and the metal layers include at least two of Al, Ge, Au, In, Si, Sn, Ag, and Cu.

[0092] For example, the metal layer includes a Ge layer 8 and an Al layer 9 sequentially disposed, wherein the thickness of the Ge layer 8 is T1 and the thickness of the Al layer 9 is T2, satisfying T1 = (0.59~1)T2. The Ge layer 8 is deposited first on the first surface 12, and then the Al layer 9 is deposited on the surface of the Ge layer 8. The thicknesses of the Ge layer 8 and the Al layer 9 satisfy T1 = (0.59~1)T2, so that during subsequent liquid phase alloying treatment, the Al layer 9 can completely form a liquid phase alloy with the Ge layer 8, avoiding any remaining Al layer 9 forming an aluminum film on the outermost layer. T1 can be equal to 0.59T2, 0.6T2, 0.7T2, 0.8T2, 0.9T2, or 1.0T2, etc.

[0093] Of course, other metal layers can also be deposited sequentially, such as Au-Sn layers, Au-In layers, Sn-Ag layers, Cu-Sn layers, Au-Sn-Au-In layers, etc. Those skilled in the art can decide according to the actual situation, and no specific limitation is made here.

[0094] Alternatively, an alloy material can be deposited directly on the first surface 12, and the alloy material can fill into the through hole 11.

[0095] In this example, the thickness of the deposited alloy layer is greater than the inner diameter of the through-hole 11. This greater thickness allows the alloy layer to fully fill the through-hole 11, ensuring a tight seal. Specifically, when the alloy material is directly deposited, the alloy layer thickness is greater than the inner diameter of the through-hole 11. When multiple metal layers are deposited sequentially, the total thickness of the multiple metal layers is greater than the inner diameter of the through-hole 11.

[0096] For example, when depositing the Ge-Al layer 9, the total thickness of the Ge-Al layer 9 is greater than the inner diameter of the via 11. Specifically, the inner diameter of the via 11 can be 0.3 μm, the thickness of the Ge layer 8 is 0.3 μm, the thickness of the Al layer 9 is 0.51 μm, and the Ge layer 8 is approximately 0.59 times the thickness of the Al layer 9.

[0097] In this example, an alloy adhesion layer is deposited between the first diaphragm 1 and the alloy sealing layer 2. Before depositing the metal layer, the alloy adhesion layer can be deposited on the surface of the first diaphragm 1 to ensure that the subsequently deposited metal layer adheres stably to the first diaphragm 1 and prevents the metal layer from falling off.

[0098] For example, the alloy adhesion layer can be Cr, Ni, Ti, etc. PVD deposition can be performed using evaporation, which can reduce the amount of material entering the sealed cavity 4. Patterning can be done using dry etching methods such as RIE or IBE ion beam etching, or wet etching can also be used.

[0099] Of course, the material of the alloy adhesion layer can be selected according to the specific material of the metal layer, so as to ensure stable adhesion of the metal layer. Those skilled in the art can determine it according to the actual situation, and no specific limitation is made here.

[0100] like Figure 3 As shown, in this example, the alloy layer is patterned to remove excess alloy layer from the surface of the first diaphragm 1. After the alloy layer is deposited onto the first surface 12, it is patterned to remove excess alloy layer. This allows for more thorough stress release during subsequent liquid phase alloying, and the portion of the alloy sealing layer 2 protruding from the through hole 11 can be hemispherical, effectively preventing stress concentration.

[0101] In this example, such as Figure 3 As shown, after multiple metal layers are sequentially deposited on the surface of the first diaphragm 1, the multiple metal layers are then patterned.

[0102] The patterning process includes photolithography and etching, which can be determined by those skilled in the art according to the actual situation, and no specific limitations are made here.

[0103] In this example, the alloy layer undergoes liquid-phase alloying. Multiple metal layers are deposited on the surface of the first diaphragm 1. During liquid-phase alloying, the designed alloy composition is uniformly distributed within the alloy layer. In a vacuum environment (e.g., pressure below 100 Pa), the upper and lower liquid surfaces naturally form curved / spherical surfaces under the action of alloy surface tension. When the temperature drops to room temperature, the alloy maintains its shape, and stress is sufficiently released, resulting in a low-stress microspherical surface coverage.

[0104] like Figure 3 As shown, in this example, during the sequential deposition of multiple metal layers, the metal layers have vacancy defects on both the upper and lower sides of the via 11. After liquid phase alloying treatment, as... Figure 2 As shown, vacancy defects can be filled.

[0105] In this example, after liquid phase alloying, the liquid phase alloy is cooled to solidify it, thereby forming the alloy sealing layer 2.

[0106] In one example, a sealed cavity 4 is formed between the first diaphragm 1 and the second diaphragm 3; the deposition of an alloy layer at one end of the first diaphragm 1, and the alloy layer being able to fill the through hole 11, includes: the alloy layer having an air inlet 21, the air inlet 21 being connected to the through hole 11, and a gas with a viscosity coefficient less than that of air being able to be filled into the sealed cavity 4 through the air inlet 21.

[0107] like Figures 7 to 9As shown, in this example, when the through hole 11 on the first diaphragm 1 is sealed, a sealed cavity 4 can be formed between the first diaphragm 1 and the second diaphragm 3.

[0108] like Figure 4 As shown, an alloy layer is deposited at one end of the first diaphragm 1, and the alloy layer can fill the through hole 11. During the deposition of the alloy layer, an inflation hole 21 is formed in the alloy layer along the thickness direction at the position corresponding to the through hole 11. The inflation hole 21 is connected to the through hole 11, and a gas with a viscosity coefficient less than that of air can be filled into the sealed cavity 4 through the inflation hole 21. For example, at least one gas selected from isobutane, propane, propylene, H2, ethane, ammonia, acetylene, ethyl chloride, ethylene, CH3Cl, methane, SO2, H2S, chlorine, CO2, N2O, and N2 can be filled into the cavity.

[0109] In this example, the inner diameter of the inflation hole 21 is greater than or equal to 10 nm. The alloy layer is close to but not sealed, and the inner diameter of the inflation hole 21 is greater than or equal to 10 nm, ensuring that the air permeability inside and outside the sealed cavity 4 is sufficiently high to improve the efficiency of gas filling and ensure high production capacity in the subsequent gas sealing process. For example, the inner diameter of the inflation hole 21 can be 10 nm, 11 nm, or 12 nm, etc., which can be determined by those skilled in the art according to the actual situation, and is not specifically limited here.

[0110] In this example, the pressure of the low viscosity gas is set as Po*Teut / Troom, where Po = 1 ATM is atmospheric pressure, Teut is the melting point of the alloy, and Troom is room temperature (in Kelvin).

[0111] In this example, a low-viscosity gas at one atmosphere can be filled into the sealed cavity 4, thereby balancing the gas pressure inside and outside the sealed cavity 4 and thus avoiding the need to place the support column 10 between the first diaphragm 1 and the second diaphragm 3.

[0112] In one example, after the gas is filled into the sealed cavity 4, the alloy layer is subjected to a first liquid phase alloying treatment, thereby sealing the gas filling hole 21.

[0113] like Figure 4 and Figure 5 As shown, after filling the sealed cavity 4 with a low-viscosity gas, the alloy layer undergoes a first liquid-phase alloying treatment to seal the gas filling hole 21. Because the pore size of the gas filling hole 21 is small during alloy layer deposition, the alloy liquid surface will naturally seal the pore under the action of surface tension after the alloy layer melts, and can completely fill the through hole 11.

[0114] In one example, such as Figure 6As shown, after the alloy layer undergoes a first liquid phase alloying treatment, the liquid phase alloy is cooled and solidified. Then, the solidified alloy layer is patterned to remove excess alloy layer from the surface of the first diaphragm 1.

[0115] After patterning the alloy layer, a second liquid-phase alloying treatment is performed on the alloy layer to form a shape as shown. Figure 2 The alloy sealing layer 2 is shown. A second liquid-phase alloying treatment is performed on the alloy layer in a vacuum environment (e.g., pressure below 100 Pa). Under the action of the alloy surface tension, the upper and lower liquid surfaces naturally form curved / spherical surfaces. When the temperature drops to room temperature, the alloy maintains its shape, and the stress is fully released, resulting in a low-stress microspherical surface coverage.

[0116] It should be noted that if the sealing cavity 4 is directly patterned after ensuring a sufficiently low viscosity coefficient, impurities may enter the sealing cavity 4 through the air filling hole 21. Therefore, the alloy layer is first subjected to a first liquid phase alloying treatment to seal the air filling hole 21.

[0117] like Figure 10 As shown, when a gas with a viscosity coefficient less than that of air needs to be filled into the sealed cavity, the preparation method of the alloy sealing layer 2 includes:

[0118] S100. An alloy layer is deposited at one end of the first diaphragm 1, and the alloy layer is capable of filling the through hole 11. The alloy layer is provided with an inflation hole 21, which is connected to the through hole 11. When depositing the alloy layer at one end of the first diaphragm 1, an inflation hole 21 is reserved in the alloy layer at the position corresponding to the through hole 11, and the inflation hole 21 is connected to the through hole 11.

[0119] S200. A gas with a viscosity coefficient less than that of air is introduced into the sealed cavity 4 through the inflation port 21. The inflation port 21 is connected to the through hole 11 so that the gas with a viscosity coefficient less than that of air can be introduced into the sealed cavity 4 through the inflation port 21. For example, the sealed cavity 4 is filled with a low viscosity gas at 1 atmosphere.

[0120] S300. The alloy layer undergoes a first liquid-phase alloying treatment to seal the gas filling holes. After filling the sealing cavity 4 with a low-viscosity gas, the alloy layer undergoes a first liquid-phase alloying treatment. Because the pore size of the gas filling holes 21 reserved during alloy layer deposition is small, the alloy liquid surface will naturally seal the holes under the action of surface tension after the alloy layer melts, thus achieving complete filling and sealing of the through holes 11.

[0121] S400. The liquid phase alloy is cooled and cured, and then the cured alloy layer is patterned to remove excess alloy layer from the surface of the first diaphragm 1. The first liquid phase alloying treatment can seal the air inlet 21. The liquid phase alloy can be cooled to room temperature, cured into an alloy layer, and then the cured alloy layer is patterned to remove excess alloy layer from the surface of the first diaphragm 1.

[0122] S500. The alloy layer undergoes a second liquid-phase alloying treatment, and after cooling, an alloy sealing layer is formed. Since the patterning process removes the excess alloy layer on the surface of the first diaphragm 1, the alloy layer is subjected to a second liquid-phase alloying treatment. This allows the liquefied alloy to naturally form a curved / spherical surface under the action of surface tension. After cooling and solidification, an alloy sealing layer is formed, which helps to reduce stress concentration.

[0123] According to another embodiment of this application, an electronic device is provided. This electronic device includes a microelectromechanical microphone (MEMS) of the above embodiment. The MEMS microphone includes a back electrode 5 and a first diaphragm 1, the first diaphragm 1 being spaced apart from the back electrode 5. The first diaphragm 1 has a through-hole 11; and an alloy sealing layer 2, the alloy sealing layer 2 filling the through-hole 11 to seal it. The through-hole 11 on the first diaphragm 1 can be used to release a sacrificial layer. After the sacrificial layer is released, the through-hole 11 is sealed, forming a low-pressure / vacuum sealed cavity 4 between the first diaphragm 1 and the second diaphragm 3. This reduces the acoustic damping and noise of the MEMS microphone, improving the signal-to-noise ratio (SNR) of the device. The through-hole 11 of the first diaphragm 1 is sealed by the alloy sealing layer 2, which can effectively release stress, thus avoiding the problem of cracking failure due to stress concentration, thereby improving the reliability of the electronic device.

[0124] In this example, the electronic device can be a mobile phone, tablet computer, Bluetooth headset, or smart speaker, etc. Those skilled in the art can determine the appropriate device based on the specific circumstances, and no specific limitations are made here.

[0125] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0126] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A microelectromechanical microphone, characterized in that, include: A back electrode (5) and a first diaphragm (1), the first diaphragm (1) being spaced apart from the back electrode (5), and a through hole (11) being provided on the first diaphragm (1); and An alloy sealing layer (2) is filled in the through hole (11) to seal the through hole (11).

2. The microelectromechanical microphone according to claim 1, characterized in that, The alloy sealing layer (2) protrudes from one end of the through hole (11).

3. The microelectromechanical microphone according to claim 2, characterized in that, The portion of the alloy sealing layer (2) that protrudes from the through hole (11) is hemispherical.

4. The microelectromechanical microphone according to claim 1, characterized in that, The alloy sealing layer (2) comprises at least two metals selected from Al, Ge, Au, In, Si, Sn, Ag and Cu.

5. The microelectromechanical microphone according to claim 1, characterized in that, The alloy sealing layer (2) comprises an Al-Ge alloy.

6. The microelectromechanical microphone according to claim 1, characterized in that, The first diaphragm (1) has a first surface (12) which is suitable for depositing the alloy sealing layer (2), and the angle between the inner wall of the through hole (11) and the first surface (12) is an obtuse angle.

7. The microelectromechanical microphone according to claim 6, characterized in that, The angle between the inner wall of the through hole (11) and the first surface (12) is 95° to 120°.

8. The microelectromechanical microphone according to claim 1, characterized in that, An alloy adhesion layer is also provided between the alloy sealing layer (2) and the first diaphragm (1).

9. The microelectromechanical microphone according to claim 1, characterized in that, It also includes a second diaphragm (3), and a sealed cavity (4) is formed between the first diaphragm (1) and the second diaphragm (3), and the sealed cavity (4) is filled with a gas with a viscosity coefficient less than that of air.

10. A method for preparing an alloy sealing layer for a microelectromechanical microphone, characterized in that, include: An alloy layer is deposited at one end of the first diaphragm (1), and the alloy layer is capable of filling the through hole (11); The alloy layer is patterned to remove excess alloy layer from the surface of the first diaphragm (1); The alloy layer is subjected to liquid phase alloying treatment; The liquid phase alloy is cooled to solidify it, thereby forming an alloy sealing layer (2).

11. The method for preparing the alloy sealing layer of the microelectromechanical microphone according to claim 10, characterized in that, The deposition of an alloy layer at one end of the first diaphragm (1), wherein the alloy layer is capable of filling the through hole (11), includes: Multiple metal layers are sequentially deposited at one end of the first diaphragm (1), the metal layers including at least two of Al, Ge, Au, In, Si, Sn, Ag and Cu.

12. The method for preparing the alloy sealing layer of the microelectromechanical microphone according to claim 11, characterized in that, The metal layer includes a Ge layer (8) and an Al layer (9) arranged sequentially, wherein the thickness of the Ge layer (8) is T1 and the thickness of the Al layer (9) is T2, satisfying T1 = (0.59~1)T2.

13. The method for preparing the alloy sealing layer of the microelectromechanical microphone according to claim 10, characterized in that, The thickness of the deposited alloy layer is greater than the inner diameter of the through hole (11).

14. The method for preparing the alloy sealing layer of the microelectromechanical microphone according to claim 10, characterized in that, An alloy adhesion layer is deposited between the first diaphragm (1) and the alloy sealing layer (2).

15. The method for preparing the alloy sealing layer of the microelectromechanical microphone according to claim 10, characterized in that, A sealed cavity (4) is formed between the first diaphragm (1) and the second diaphragm (3); The deposition of an alloy layer at one end of the first diaphragm (1), wherein the alloy layer is capable of filling the through hole (11), includes: The alloy layer is provided with an air filling hole (21), which is connected to the through hole (11); A gas with a viscosity coefficient less than that of air is filled into the sealed cavity (4) through the filling hole (21).

16. The method for preparing the alloy sealing layer of the microelectromechanical microphone according to claim 15, characterized in that, The inner diameter of the air inlet (21) is greater than or equal to 10 nm.

17. The method for preparing the alloy sealing layer of the microelectromechanical microphone according to claim 15, characterized in that, After the gas is filled into the sealed cavity (4), the alloy layer is subjected to a first liquid phase alloying treatment, thereby sealing the gas filling hole (21).

18. The method for preparing the alloy sealing layer of the microelectromechanical microphone according to claim 17, characterized in that, After the alloy layer is subjected to the first liquid phase alloying treatment, the liquid phase alloy is cooled and solidified, and then the solidified alloy layer is patterned to remove the excess alloy layer on the surface of the first diaphragm (1).

19. The method for preparing the alloy sealing layer of the microelectromechanical microphone according to claim 18, characterized in that, After the alloy layer is patterned, it is then subjected to a second liquid phase alloying treatment to form an alloy sealing layer.

20. An electronic device, characterized in that, Including the microelectromechanical microphone as described in any one of claims 1 to 9.

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