A directional microphone and a method of processing the same

Abstract

The application provides a directional microphone, which comprises a device substrate, a MEMS microphone sensor assembly, an intermediate plate, a top substrate and a MEMS comb mechanism; the MEMS microphone sensor assembly is fixed in the middle area of the top surface of the device substrate, the intermediate plate is covered on the device substrate and has an inner hole surrounding the MEMS microphone sensor assembly; the top substrate is covered on the intermediate plate and has a horizontal channel on the top surface and a lower end opening on the bottom surface, the horizontal channel is communicated with the inner hole through the lower end opening; the MEMS comb mechanism comprises a movable comb on the top surface of the device substrate and capable of controlled horizontal movement, the movable comb has an opening structure and a shielding structure; during the movement of the movable comb, the opening structure is communicated with the horizontal channel at different positions respectively. The directional microphone has good versatility based on the adjustable directional design of the microphone sensor assembly.

Description

Technical Field

[0001] This invention relates to the field of acoustic components technology, specifically to a directional microphone and its processing method. Background Technology

[0002] Conventional directional microphones are relatively large and typically have pickup holes at both ends of the diaphragm. They also require specially designed directional microphone housings to control the microphone's pickup direction by adjusting the phase difference of the sound reaching the diaphragm.

[0003] However, MEMS microphones are small in size and used in complex scenarios. If the pickup hole design of a conventional microphone is adopted, the structural changes of the mounting carrier of the MEMS microphone in practical applications will greatly affect the pickup direction of the MEMS microphone, and the directional control effect of the MEMS microphone cannot be guaranteed. Therefore, in order to expand the application scenarios of MEMS microphones, a new type of MEMS microphone needs to be designed with directional control as the goal. Summary of the Invention

[0004] This invention discloses a directional microphone that achieves an adjustable directional structure design based on a MEMS microphone sensor assembly. It has good versatility for complex application scenarios of small devices and is highly practical.

[0005] Accordingly, the present invention discloses a directional microphone, including a device substrate and a MEMS microphone sensor assembly, wherein the MEMS microphone sensor assembly is fixed in the central region of the top surface of the device substrate, and further includes:

[0006] An intermediate plate, covering the device substrate, has an inner hole surrounding the MEMS microphone sensor assembly;

[0007] The top substrate, which covers the middle plate, has a horizontal channel on the top surface and a lower end opening on the bottom surface, the horizontal channel communicating with the inner hole through the lower end opening;

[0008] MEMS comb mechanism, including movable comb teeth located on the top surface of the device substrate that are controlled to move horizontally, the movable comb teeth having an opening structure and a shielding structure;

[0009] During the controlled horizontal movement of the movable comb teeth, the opening structure is connected to the horizontal channel at different positions, or the opening structure is not connected to the horizontal channel, and the non-corresponding connected areas of the horizontal channel and the opening structure are covered by the shielding structure.

[0010] In an optional embodiment, the MEMS comb mechanism includes a silicon substrate located at the bottom, and the MEMS comb mechanism is fixed to the top substrate via the silicon substrate;

[0011] A channel perforation is formed with the projection shape of the horizontal channel on the silicon substrate as the outline, and the opening structure is connected to the horizontal channel through the channel perforation.

[0012] An optional embodiment further includes fixed comb teeth, which are machined on the top surface of the silicon substrate;

[0013] The movable comb teeth further include an anchor point structure, a deformation structure, a connecting structure, and a driving structure. The anchor point structure, the deformation structure, the connecting structure, and the driving structure are connected in sequence. The shielding structure and the opening structure are respectively disposed on the connecting structure.

[0014] The anchor point structure is fixed on the top surface of the silicon substrate. The position of the driving structure is matched with the fixed comb teeth. Based on the driving of the driving structure by the fixed comb teeth, the connecting structure moves on the top substrate. During the movement of the connecting structure, the deformable structure follows the elastic deformation with the anchor point structure as the fulcrum. The opening structure and the shielding structure move synchronously with the connecting structure.

[0015] In an optional embodiment, an annular shielding metal layer is provided on the inner hole sidewall of the intermediate plate, and a substrate shielding circuit layer is provided on the top substrate. The annular shielding metal layer and the substrate shielding circuit layer are electrically connected to form a shielding structure.

[0016] In an optional embodiment, a base electrode electrically connected to the MEMS microphone sensor assembly is disposed on the bottom surface of the device substrate.

[0017] In an optional embodiment, the MEMS comb mechanism has a driving electrode, which is led out to the bottom surface of the device substrate after passing through the top substrate, the middle plate and the device substrate in sequence.

[0018] In an optional embodiment, when an annular shielding metal layer is provided on the inner hole sidewall of the intermediate plate, a shielding electrode is provided on the bottom surface of the device substrate, which is led out from the annular shielding metal layer in sequence through the intermediate plate and the top substrate.

[0019] Accordingly, the present invention also discloses a method for manufacturing a directional microphone, used for manufacturing the directional microphone, comprising:

[0020] The entire board is processed to obtain multiple MEMS microphone sensor components arranged in an array on the device substrate, multiple internal holes arranged in an array on the intermediate board, and multiple MEMS comb mechanisms arranged in an array on the silicon substrate.

[0021] The intermediate plate is installed as a whole, and the intermediate plate is attached to the top surface of the device substrate plate through a first preset bonding process. The MEMS microphone sensor assembly on the device substrate plate is located in the corresponding inner hole of the intermediate plate plate.

[0022] The silicon substrate is assembled by bonding the silicon substrate to the top surface of the intermediate plate using a second preset bonding process. Each MEMS comb mechanism in the MEMS comb mechanism array is located above the corresponding inner hole of the inner hole array.

[0023] The device substrate and intermediate plate silicon substrate in their combined state are cut according to the array structure of the MEMS microphone sensor component array, the inner hole array, and the MEMS comb mechanism array to obtain the directional microphone.

[0024] In an optional implementation, each of the MEMS comb mechanisms is inspected prior to the individual unit cutting step.

[0025] In summary, the embodiments of the present invention provide a directional microphone and its processing method. By integrating a MEMS electrostatic comb driving mechanism in a three-layer stacked structure of a device substrate, an intermediate plate, and a top substrate, the horizontal displacement of the movable comb teeth is used to precisely control the connection position between the opening structure and the horizontal channel, thereby achieving rapid switching of the directional mode. The shielding structure composed of an annular shielding metal layer and a substrate shielding circuit layer can ensure the microphone's interference resistance. Attached Figure Description

[0026] Figure 1 This is a three-dimensional structural diagram of a directional microphone according to an embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of a half-section three-dimensional structure of a directional microphone according to an embodiment of the present invention.

[0028] Figure 3 This is a schematic diagram of the bottom surface structure of the device substrate of a directional microphone according to an embodiment of the present invention.

[0029] Figure 4 This is a three-dimensional structural diagram of the array structure according to an embodiment of the present invention. Detailed Implementation

[0030] To further illustrate the technical means and effects adopted by this application to achieve its intended purpose, the specific implementation methods, structures, features, and effects according to this application are described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0031] This invention provides a directional microphone. Essentially, the directional microphone includes a device substrate 1 and a MEMS microphone sensor assembly, which is fixed in the central region of the top surface of the device substrate 1. The device substrate 1, serving as the basic support platform for the entire microphone structure, is typically made of silicon or ceramic substrate materials.

[0032] Generally, a MEMS microphone sensor assembly includes a MEMS microphone and a processing chip 14, which are connected by gold wires to achieve electrical signal transmission. The MEMS microphone sensor assembly typically communicates with the outside world through the processing chip 14. Accordingly, to ensure reliable fixation of the MEMS microphone sensor assembly, the MEMS microphone (via the corresponding bracket 8) and the processing chip 14 are generally fixed to the device substrate 1 using epoxy resin adhesive or eutectic bonding, respectively. The pins of the processing chip 14 extend from the bottom surface of the device substrate 1. Typically, signal chips have two pins, corresponding to audio signal output and ground, respectively. The device substrate 1 has a precisely pre-drilled pickup hole 10 at the bonding position of the MEMS microphone. The diameter of this pickup hole 10 is typically 200 to 400 micrometers. External sound enters the MEMS microphone through the pickup hole 10 and effectively excites the bottom surface of the diaphragm 9, generating a capacitance change and thus achieving sound-to-electricity conversion.

[0033] Specifically, the microphone also includes an intermediate plate 2, which covers the device substrate 1 and has an inner hole surrounding the MEMS microphone sensor assembly. The intermediate plate 2 serves two main functions: one is to isolate the MEMS microphone sensor assembly from direct contact with the external environment, forming an acoustic resonant cavity and a protective cavity to prevent damage to the sensitive elements from external dust and moisture; the other is to provide a stable support platform for the subsequent stacked structure of the top substrate 3. The intermediate plate 2 is typically made of glass or silicon wafers, with a thickness controlled between 200 and 300 micrometers. Its inner hole size is designed to be 50 to 100 micrometers larger than the periphery of the MEMS microphone sensor assembly, ensuring assembly tolerance while forming effective acoustic isolation.

[0034] The microphone also includes a top substrate 3, which covers the intermediate plate 2 and has a horizontal channel 11 on the top surface and a lower opening 12 on the bottom surface. The horizontal channel 11 communicates with the inner hole through the lower opening 12. The horizontal channel 11 serves as the only path for external acoustic signals to enter the microphone, and its geometry and dimensions are precisely designed: the channel width is typically 30 to 200 micrometers, the depth is 50 to 150 micrometers, and the cross-section is rectangular or arc-shaped. On the one hand, the geometric parameters of the horizontal channel 11 determine the acoustic resonant frequency and damping characteristics of the microphone; on the other hand, by controlling the length of the horizontal channel 11 actually used by the upper opening (the opening structure 7 in the MEMS comb mechanism described later) and the lower opening 12, the phase delay of sound from the outside through the horizontal channel 11 to the top surface of the diaphragm 9 can be precisely controlled, thereby dynamically adjusting the phase difference of sound reaching both sides of the diaphragm 9. This is the core physical mechanism for achieving adjustable directivity.

[0035] The microphone also includes a MEMS comb mechanism, comprising movable comb teeth 6 that move horizontally under controlled conditions on the top surface of the device substrate 1. The movable comb teeth 6 have an opening structure 7 and a shielding structure 17. The geometry of the opening structure 7 can be rectangular, circular, fan-shaped, or elliptical, and its area occupies 40% to 80% of the cross-sectional area of ​​the horizontal channel 11. The shielding structure 17 is slightly larger than the width of the horizontal channel, ensuring complete coverage of the horizontal channel. During the controlled horizontal movement of the movable comb teeth 6, the opening structure 7 may communicate with the horizontal channel 11 at different positions, or it may not communicate with the horizontal channel 11. The non-corresponding communication areas between the horizontal channel 11 and the opening structure 7 are covered by the shielding structure 17. The horizontal movement step accuracy of the movable comb teeth 6 is approximately 0.5 micrometers, and the stroke is determined by the specific structure of the MEMS comb mechanism.

[0036] The core innovation of the directional microphone disclosed in this invention lies in combining MEMS electrostatic comb driving technology with acoustic channel adjustment function. By precisely controlling the position of sound entering the horizontal channel 11 through the in-plane movement of the movable comb 6, the acoustic path length of external sound reaching the diaphragm 9 can be effectively controlled, thereby controlling the phase difference of sound acting on the two sides of the diaphragm 9 and realizing the function of dynamic adjustment of microphone directionality. This design avoids the macroscopic mechanical movement or thermal driving method in traditional solutions and has significant advantages such as fast response speed, low power consumption and high reliability.

[0037] Because the MEMS comb mechanism is electrically adjustable, on the one hand, it can be calibrated and adjusted as needed before leaving the factory, depending on the differences in the carrier structure on which the directional microphone is installed, such as the differences in the application of the directional microphone on different mobile phones or the different positions of the application on the mobile phone circuit board; on the other hand, according to the real-time performance requirements of the carrier on which the directional microphone is installed, such as switching call mode, recording mode, noise reduction mode, etc., the directionality of the directional microphone can also be dynamically adjusted as needed to achieve intelligent sound field adaptation.

[0038] In a preferred embodiment of the present invention, the MEMS comb mechanism includes a silicon substrate 4 located at the bottom, and the MEMS comb mechanism is fixed to the top substrate 3 via the silicon substrate 4. A channel perforation is formed with the projection shape of the horizontal channel 11 on the silicon substrate 4 as its outline, and the opening structure 7 communicates with the horizontal channel 11 through the channel perforation. Specifically, in the prior art, the MEMS comb mechanism is generally processed using a silicon substrate 4 (the silicon substrate 4 is the top layer silicon of an SOI wafer) as the raw material, and is obtained through processes such as protection, etching, removal of the support layer, and doping. The relevant content of this processing technology can be referred to existing MEMS processing technologies.

[0039] It should be noted that, for clarity, the schematic diagrams of this embodiment only show a single set of teeth engaging for both the fixed teeth 5 and the movable teeth 6 in the MEMS comb mechanism. In actual implementation, the fixed teeth 5 and movable teeth 6 can achieve greater driving force through multiple sets of engagement. This requires setting the number of tooth pairs according to actual needs, typically using an array of 10 to 50 tooth pairs. Furthermore, since the MEMS comb mechanism has a silicon substrate 4 as its bottom layer, the perforated channels on the bottom layer of the silicon substrate 4, based on the contour of the horizontal channel 11, can serve as an extension of the horizontal channel 11, thereby ensuring the functional realization of the directional microphone in this embodiment.

[0040] In actual processing, the top substrate 3 and the silicon substrate 4 can actually be a single integrated structure. That is, the MEMS comb mechanism can be directly fabricated on the SOI top silicon layer of the top substrate 3 to simplify the process flow, reduce bonding interfaces, and improve overall reliability. Correspondingly, the horizontal channel and the channel via are essentially the same structure.

[0041] Specifically, the MEMS comb mechanism further includes fixed comb teeth 5, which are machined on the top surface of the silicon substrate 4. The movable comb teeth 6 further include an anchor point structure 13, a deformable structure 16, a connecting structure, and a driving structure 18, which are connected in sequence. The shielding structure 17 and the opening structure 7 are respectively disposed on the connecting structure.

[0042] In this embodiment of the invention, the anchor point structure 13 is fixed to the top surface of the silicon substrate 4, serving as the fulcrum for the movement of the entire movable comb tooth 6. The anchor point structure 13 is typically in the form of an anchor block, formed by deep reactive ion etching, and forms a strong mechanical connection with the silicon substrate 4.

[0043] The anchor structure 13 is connected to the connecting structure via the deformable structure 16. Specifically, the deformable structure 16 can be any one of a folded beam structure, a straight beam structure (as shown in the schematic diagram of the embodiment of the present invention), or an arc-shaped beam structure. The deformable structure 16 can provide a large amount of elastic deformation within a limited space while maintaining high mechanical stiffness, and can withstand 10 9 The folding beam structure can withstand more than 3 to 5 folds without fatigue failure; the beam width is 5 to 10 micrometers.

[0044] The connection structure can be designed according to the objects to be connected. In this embodiment of the invention, the connection structure needs to be connected to the deformable structure 16, the driving structure 18, the shielding structure 17, and the opening structure 7. Accordingly, in this embodiment of the invention, the connection structure is a long strip block structure. One end of the long strip block structure is connected to the deformable structure 16, and the other end can be used as the driving structure 18. The opening mechanism can be integrated into the long strip block structure, and the remaining part of the structure can be used as the shielding structure 17 to shield the channel perforation.

[0045] In this embodiment of the invention, the driving structure 18 is an electrode integrated into the elongated block structure of the connecting structure. In practical applications, to ensure sufficient driving force, the driving structure 18 is generally an interdigitated electrode array (a combination of multiple electrodes), forming an electrostatic capacitor structure with the fixed comb teeth 5. When a driving voltage is applied to the fixed comb teeth 5, the generated electrostatic attraction drives the driving structure 18 to move the connecting structure horizontally. The driving structure 18 is powered through an anchor point fixed on a silicon substrate. The power flows from the silicon substrate through the anchor point, the deformable structure 16, and the connecting structure before reaching the driving structure 18.

[0046] Depending on the location of the opening structure 7, directional control of the directional microphone can be achieved. Specifically, in terms of the mating state, the mating methods between the opening structure 7 and the channel perforation include:

[0047] 1. The opening structure 7 is connected to the channel perforation (i.e., the horizontal channel 11) at different positions. After sound enters the channel perforation from the outside through the opening structure 7, it travels the shortest distance to the lower opening 12 of the horizontal channel 11, then propagates in the inner hole and reaches the top surface of the diaphragm 9. The sound also reaches the bottom surface of the diaphragm 9 from the outside through the pickup hole 10. Taking the bottom surface of the diaphragm 9 as the front, when the phase of the sound reaching the top surface of the diaphragm 9 from the back is the same as the phase of the sound reaching the bottom surface of the diaphragm 9, the diaphragm 9 will not vibrate in response to the sound from the back due to pressure balance, thus realizing the function of frontal sound pickup. By adjusting the relative position of the opening structure 7 and the horizontal channel 11, the phase delay of the back sound wave can be precisely controlled, realizing continuous adjustment of multiple directional modes.

[0048] Second, the opening structure 7 is not connected to the channel perforation (i.e., the horizontal channel 11). In this case, sound cannot enter the inner hole through the horizontal channel 11; sound can only enter through the pickup hole 10. At this time, the directional microphone is in omnidirectional mode. In omnidirectional mode, the microphone has approximately the same sensitivity to sound from all directions.

[0049] Furthermore, in addition to mounting the MEMS comb mechanism, the intermediate plate 2 and top substrate 3 in this embodiment of the invention also serve an important function: replacing the protective housing of the original MEMS microphone sensor assembly. The protective housing generally possesses both physical and electromagnetic protection properties. Physical protection is achieved through the mechanical strength and sealing structure of the intermediate plate 2 and top substrate 3, while electromagnetic protection requires the installation of a corresponding equipotential bonding network (Faraday cage).

[0050] Specifically, an annular shielding metal layer 15 is provided on the inner wall of the intermediate plate 2, and a substrate shielding circuit layer is provided on the top substrate 3. The annular shielding metal layer 15 and the substrate shielding circuit layer are electrically connected to form a shielding structure, and the shielding structure is grounded as a whole. On the one hand, it can block external electromagnetic signals from entering the interior; on the other hand, it can effectively suppress the high-frequency electromagnetic interference generated by the comb drive from coupling to the microphone sensor assembly, avoiding drive noise contamination of the audio signal. The annular shielding metal layer 15 is made of copper or aluminum, with a thickness of 2 to 5 micrometers, and is deposited by magnetron sputtering or electroplating processes.

[0051] Figure 3 This is a schematic diagram of the bottom structure of the device substrate 1 of the directional microphone according to an embodiment of the present invention, which clearly shows the layout scheme of the electrode array.

[0052] Furthermore, considering the practical application of the entire directional microphone, it is generally necessary to integrate the electrodes that need to be connected to external power in the entire directional microphone onto the bottom surface of the device substrate 1 to facilitate the mounting and soldering of external circuits.

[0053] Specifically, a base electrode 22 electrically connected to the MEMS microphone sensor assembly is disposed on the bottom surface of the device substrate 1. The base electrodes 22 are led out from the processing chip 14 of the MEMS microphone sensor assembly through through-silicon vias or wire bonding, and the number of them is 2 to 4, including audio output, power supply, ground and clock signals, etc.

[0054] The MEMS comb mechanism has a driving electrode 23, which is led out to the bottom surface of the device substrate 1 after passing through the top substrate 3, the intermediate plate 2, and the device substrate 1 in sequence. The cross-substrate electrode connection can be achieved using TSV technology or wire bonding technology. Generally, the driving electrode 23 includes at least one forward driving electrode 23 and at least one reverse driving electrode 23, which are respectively connected to the fixed comb tooth 5 and the movable comb tooth 6, supporting bidirectional driving and position locking functions.

[0055] When an annular shielding metal layer 15 is provided on the inner hole sidewall of the intermediate plate 2, a shielding electrode 21 is provided on the bottom surface of the device substrate 1, extending sequentially from the annular shielding metal layer 15 through the intermediate plate 2 and the top substrate 3. The shielding electrode 21, the base electrode 22, and the driving electrode 23 are arranged in a regular array on the bottom surface of the device substrate 1 to facilitate bonding during external applications. In actual implementation, several fixing electrodes 24 for fixing and balancing pressure are also provided on the bottom surface of the device substrate 1.

[0056] Specifically, the processing method of the directional microphone in this embodiment of the invention is similar to that of most microelectronic components. Multiple directional microphones are first processed on the substrate material and then cut and divided to obtain a single directional microphone. This wafer-level processing method can greatly improve production efficiency and consistency.

[0057] Specifically, this invention discloses a method for manufacturing a directional microphone for mass production of the aforementioned microphone, comprising the following steps:

[0058] S101: Processing steps for the entire board

[0059] A MEMS microphone sensor array is fabricated on the device substrate 31, an internal aperture array is fabricated on the intermediate substrate 32, and a MEMS comb mechanism array is fabricated on the top substrate 33. Specifically, the device substrate uses an 8-inch silicon wafer with a resistivity of 0.01 to 0.02 Ω·cm. The intermediate substrate uses an 8-inch glass wafer with a thickness of 100 to 300 micrometers. The top substrate uses an 8-inch SOI wafer with a top silicon layer thickness of 30 to 40 micrometers. The entire substrate is fabricated using a standard MEMS process flow, including circuit protection, photolithography, etching, thin film deposition, and doping.

[0060] S102: Installation steps for the entire middle plate

[0061] The intermediate plate is bonded to the top surface of the device substrate using a first preset bonding process. Each MEMS microphone sensor assembly in the MEMS microphone sensor assembly array is located in a corresponding inner hole of the inner hole array. Optionally, the first preset bonding process is a combination of one or more of the following: anodic bonding, eutectic bonding, glass paste bonding, or polymer bonding. The anodic bonding process parameters are: voltage 1000V, temperature 400°C, and time 30 minutes; the polymer bonding process uses benzocyclobutene adhesive, with a curing temperature of 250°C and a time of 2 hours. The bonding process is performed in a Class 100 cleanroom environment, and the bonding alignment accuracy is required to be better than ±5 micrometers.

[0062] S103: Top substrate assembly steps

[0063] The top substrate is bonded to the top surface of the intermediate plate using a second pre-defined bonding process. Each MEMS comb tooth in the MEMS comb tooth array is located above the corresponding inner hole of the inner hole array. The second pre-defined bonding process may be the same as or different from the first pre-defined bonding process, preferably using polymer bonding to avoid the influence of high temperature on the MEMS comb tooth. After the adhesive cures, stress-relieving annealing is required at 150°C for 1 hour.

[0064] In steps S101 to S103, in addition to the mechanical bonding of the entire board structure, the bonding of electrical connection structures across the circuit boards is also involved. Specifically, the electrode connections on the two surfaces within the substrate and the electrode connections across two substrates can be achieved using processes such as TSV technology, wire bonding technology, or anisotropic conductive adhesive to ensure the reliable extraction of the driving electrode, shielding electrode, and signal electrode.

[0065] S104: Online Testing Procedures

[0066] After the silicon substrate assembly step and before the individual component cutting step, each MEMS comb mechanism is inspected. Inspection items include drive check, drive response time, alignment accuracy of the opening structure and horizontal channel, and the integrity of the shielding structure. Inspection uses a probe card to contact the drive electrodes, applying a test voltage of 5 to 10V at a frequency of 1kHz. Acceptable criteria are a drive response time of less than 1 millisecond, alignment deviation of less than 2 micrometers, and shielding rate greater than 99%.

[0067] Specifically, the inspection setup is implemented during the overall board processing stage, reducing repetitive operations such as loading / unloading and positioning when inspecting individual directional microphones, enabling rapid full-device inspection. The inspection primarily focuses on the MEMS comb mechanism. Since the driving electrodes of the MEMS comb mechanism need to be led out through an intermediate board to the device substrate, the first thing to check is whether the driving electrodes are properly connected. This is done by driving the MEMS comb mechanism through the driving electrodes led out from the device substrate; this can be inspected visually. Similarly, since the movement of the comb mechanism is visible, most inspections can be performed visually; however, performance-related control curves need to be plotted separately for each device, establishing a database of corresponding curves for driving voltage and acoustic performance.

[0068] S105: Single-unit cutting steps

[0069] Figure 4 This is a three-dimensional structural diagram of the array structure according to an embodiment of the present invention. The directional microphone is obtained by cutting the device substrate 31, the middle substrate 32, and the top substrate 33 in their combined state according to the array structure (the MEMS microphone sensor component array, the inner hole array, and the MEMS comb mechanism array). Specifically, the individual components are cut using laser cutting or deep reactive ion etching, with a cut width of 50 micrometers.

[0070] The single-unit cutting step is performed in a vacuum environment or an inert gas environment, wherein the vacuum level of the vacuum environment is less than 10 Pa, and the inert gas is nitrogen or argon. An inert environment prevents oxidation and contamination of the metal structure during the cutting process, ensuring the quality of the cut edges.

[0071] In summary, this invention provides a directional microphone and its manufacturing method. By integrating a MEMS electrostatic comb drive mechanism into a three-layer stacked structure of a device substrate, an intermediate board, and a top substrate, the horizontal displacement of the movable comb teeth precisely controls the connection position between the opening structure and the horizontal channel, enabling rapid switching of the directional mode. The shielding structure, composed of a ring-shaped shielding metal layer and a substrate shielding circuit layer, ensures the microphone's electromagnetic interference resistance. Through whole-board processing, online inspection, and wafer-level bonding processes, mass production with high yield is achieved, significantly reducing manufacturing costs and providing a high-performance, flexible, and adjustable microphone solution for small devices.

[0072] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A directional adjustable microphone, comprising a device substrate and a MEMS microphone sensor assembly, wherein the MEMS microphone sensor assembly is fixed in the central region of the top surface of the device substrate, characterized in that, Also includes: An intermediate plate, covering the device substrate, has an inner hole surrounding the MEMS microphone sensor assembly; The top substrate, which covers the middle plate, has a horizontal channel on the top surface and a lower end opening on the bottom surface, the horizontal channel communicating with the inner hole through the lower end opening; MEMS comb mechanism, including movable comb teeth located on the top surface of the device substrate that are controlled to move horizontally, the movable comb teeth having an opening structure and a shielding structure; During the controlled horizontal movement of the movable comb teeth, the opening structure is connected to the horizontal channel at different positions, or the opening structure is not connected to the horizontal channel, and the non-corresponding connected areas of the horizontal channel and the opening structure are covered by the shielding structure. The MEMS comb mechanism includes a silicon substrate at the bottom, and the MEMS comb mechanism is fixed to the top substrate through the silicon substrate; A channel perforation is formed with the projection shape of the horizontal channel on the silicon substrate as the outline, and the opening structure is connected to the horizontal channel through the channel perforation; The directional adjustable microphone also includes fixed comb teeth, which are machined on the top surface of the silicon substrate; The movable comb teeth further include an anchor point structure, a deformation structure, a connecting structure, and a driving structure. The anchor point structure, the deformation structure, the connecting structure, and the driving structure are connected in sequence. The shielding structure and the opening structure are respectively disposed on the connecting structure. The anchor point structure is fixed on the top surface of the silicon substrate. The position of the driving structure is matched with the fixed comb teeth. Based on the driving of the driving structure by the fixed comb teeth, the connecting structure moves on the top substrate. During the movement of the connecting structure, the deformable structure follows the elastic deformation with the anchor point structure as the fulcrum. The opening structure and the shielding structure move synchronously with the connecting structure.

2. The directional adjustable microphone as described in claim 1, characterized in that, An annular shielding metal layer is provided on the inner hole sidewall of the intermediate plate, and a substrate shielding circuit layer is provided on the top substrate. The annular shielding metal layer and the substrate shielding circuit layer are electrically connected to form a shielding structure.

3. The directional adjustable microphone as described in claim 1 or 2, characterized in that, The bottom surface of the device substrate is provided with a base electrode that is electrically connected to the MEMS microphone sensor assembly.

4. The directional adjustable microphone as described in claim 3, characterized in that, The MEMS comb mechanism has a driving electrode, which is led out to the bottom surface of the device substrate after passing through the top substrate, the middle plate and the device substrate in sequence.

5. The directional adjustable microphone as described in claim 4, characterized in that, When an annular shielding metal layer is provided on the inner hole sidewall of the intermediate plate, a shielding electrode is provided on the bottom surface of the device substrate, which is led out from the annular shielding metal layer in sequence through the intermediate plate and the top substrate.

6. A method for manufacturing a directional adjustable microphone, characterized in that, The processing for the directional adjustable microphone according to any one of claims 1 to 5 includes: The entire board is processed to obtain multiple MEMS microphone sensor components arranged in an array on the device substrate, multiple internal holes arranged in an array on the intermediate board, and multiple MEMS comb mechanisms arranged in an array on the silicon substrate. The intermediate plate is installed as a whole, and the intermediate plate is attached to the top surface of the device substrate plate through a first preset bonding process. The MEMS microphone sensor assembly on the device substrate plate is located in the corresponding inner hole of the intermediate plate plate. The silicon substrate is assembled by bonding the silicon substrate to the top surface of the intermediate plate using a second preset bonding process. Each MEMS comb mechanism in the MEMS comb mechanism array is located above the corresponding inner hole of the inner hole array. The device substrate and intermediate plate silicon substrate in their combined state are cut according to the array structure of the MEMS microphone sensor component array, the inner hole array, and the MEMS comb mechanism array to obtain the directional adjustable microphone.

7. The method for manufacturing a directional adjustable microphone as described in claim 6, characterized in that, Each of the MEMS comb mechanisms is inspected before the single-unit cutting step.

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