Two-dimensional vector microphone

Abstract

This application provides a two-dimensional vector microphone, including: a wafer, a first pickup structure, and a second pickup structure; the first pickup structure and the second pickup structure are respectively disposed on opposite sides of the wafer in the thickness direction, or the first pickup structure and the second pickup structure are disposed on the same side of the wafer in the thickness direction. The first pickup structure extends along a first direction, and the second pickup structure extends along a second direction. The first direction and the second direction are orthogonal. The first pickup structure includes at least two parallel thermal resistance lines, and the second pickup structure includes at least two parallel thermal resistance lines. This application provides a two-dimensional vector microphone with good two-dimensional sound pickup effect.

Description

[0001] This application claims priority to Chinese Patent Application No. 202110647715.6, filed on June 10, 2021, entitled "Two-Dimensional Vector Microphone", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of microphone technology, and more particularly to a two-dimensional vector microphone. Background Technology

[0003] A vector microphone, or acoustic vector sensor (AVS), is a device that converts sound signals into electrical signals. Vector microphones include hot-wire vector microphones, which obtain sound field information by detecting particle vibration velocity and have advantages such as high signal-to-noise ratio and simple manufacturing.

[0004] Currently, hot-wire vector microphones can only achieve one-dimensional detection. The way to achieve a single-chip two-dimensional vector microphone in related technologies is to combine two one-dimensional vector microphones. The two one-dimensional vector microphones are used to detect sound field information in two directions respectively to achieve two-dimensional detection.

[0005] However, combining two one-dimensional vector microphones not only doubles the overall space of the microphones, but also causes structural crosstalk between the two one-dimensional vector microphones, thus affecting the mutual orthogonality of the sensors. Summary of the Invention

[0006] This application provides a two-dimensional vector microphone with good two-dimensional sound pickup effect.

[0007] This application provides a two-dimensional vector microphone, including: a wafer, a first pickup structure, and a second pickup structure; the first pickup structure and the second pickup structure are respectively disposed on opposite sides of the wafer in the thickness direction, or the first pickup structure and the second pickup structure are disposed on the same side of the wafer in the thickness direction, the first pickup structure extends along a first direction, the second pickup structure extends along a second direction, the first direction and the second direction are orthogonal, the first pickup structure includes at least two parallel thermal resistance lines, and the second pickup structure includes at least two parallel thermal resistance lines.

[0008] This application provides a two-dimensional vector microphone. By processing one-dimensional vector pickup structures for pickup in two directions on both sides of the wafer, or processing one-dimensional vector pickup structures for pickup in two directions on the same side (front or back) of the wafer, a two-dimensional vector pickup structure can be integrated on a single chip, which can effectively improve the signal-to-noise ratio of the device and eliminate the mutual interference of pickup in two directions.

[0009] In one possible implementation, the wafer includes a support body, the ends of the first and second sound pickup structures are fixed to the support body, a hollow area is formed on the inner side of the support body, the hollow area extends through the thickness direction of the wafer, and at least a portion of the length of the first and second sound pickup structures faces the hollow area.

[0010] The hollowed-out area allows air to be present between the thermal resistance lines of the first and second pickup structures instead of being blocked by wafer material. This facilitates thermal coupling between the first and second pickup structures, and the thermal fields formed by the front and back thermal lines reinforce each other, which can effectively improve the signal-to-noise ratio of the device.

[0011] In one possible implementation, the wafer includes a support body, the ends of the first and second sound pickup structures are fixed to the support body, and recesses are respectively provided on both sides of the support body in the thickness direction. At least a portion of the length of the first and second sound pickup structures is disposed facing the recesses.

[0012] The recessed portion provides space for acoustic vibration and prevents heat loss caused by thermal resistance lines adhering closely to the wafer surface, thus allowing heat to be localized in the air.

[0013] In one possible implementation, when the first pickup structure and the second pickup structure are respectively disposed on both sides of the wafer in the thickness direction, the two-dimensional vector microphone further includes a circuit board, a first packaging housing, and a second packaging housing; the circuit board is provided with an opening, the wafer is embedded in the opening, and the first pickup structure and the second pickup structure are respectively exposed on both sides of the circuit board.

[0014] The first package housing has a first sound guide hole that connects two opposite sides of the first package housing. The second package housing has a second sound guide hole that connects two opposite sides of the second package housing. The first package housing and the second package housing are respectively disposed on both sides of the circuit board. The first sound guide hole extends along a second direction, and the second sound guide hole extends along a first direction. The first sound pickup structure is located at the center of the first sound guide hole, and the second sound pickup structure is located at the center of the second sound guide hole.

[0015] The two-dimensional vector microphone provided in this application embodiment has two pickup structures respectively set on the front and back sides of the wafer, which can better match the package and achieve a higher signal-to-noise ratio gain in a small package size.

[0016] In one possible implementation, the first and second packaging shells have the same structure and are fixedly connected.

[0017] The first and second packaging shells have the same structure, which can reduce production costs. The first and second packaging shells are fixedly connected to ensure the reliability of the packaging structure.

[0018] In one possible implementation, the center of the first pickup structure and the center of the second pickup structure coincide in the thickness direction of the wafer.

[0019] The directional centers of the first and second pickup structures coincide, so the two-dimensional vector microphone has better directional consistency compared to related technologies that combine two one-dimensional vector microphones.

[0020] In one possible implementation, when the first pickup structure and the second pickup structure are respectively disposed on both sides of the wafer in the thickness direction, the distance between the first pickup structure and the second pickup structure in the thickness direction of the wafer is greater than 0 μm and less than or equal to 500 μm.

[0021] When the first pickup structure and the second pickup structure are disposed on the same side of the wafer in the thickness direction, the distance between the first pickup structure and the second pickup structure in the thickness direction of the wafer is zero.

[0022] The spacing between the first and second pickup structures along the thickness of the wafer affects the overall structural strength of the microphone, the thermal coupling between the two-dimensional pickup structures, the signal-to-noise ratio, and other performance characteristics.

[0023] In one possible implementation, the first pickup structure includes three thermal resistance lines, which are divided into a heating line and two sensitive lines, with the two sensitive lines respectively disposed on both sides of the heating line; the second pickup structure includes three thermal resistance lines, which are divided into a heating line and two sensitive lines, with the two sensitive lines respectively disposed on both sides of the heating line.

[0024] A three-wire pickup structure is less prone to sensitivity loss compared to a two-wire structure.

[0025] In one possible implementation, the width of the sensing wire is smaller than the width of the heating wire.

[0026] The width of the heating wire can be greater than the width of the sensing wire to increase the heating power of the heating wire and improve the detection sensitivity of the sensing wire.

[0027] In one possible implementation, the first pickup structure includes multiple thermal resistance lines, which are divided into a heating line and multiple sensitive lines respectively disposed on both sides of the heating line; the second pickup structure includes multiple thermal resistance lines, which are divided into a heating line and multiple sensitive lines respectively disposed on both sides of the heating line.

[0028] Setting a larger number of sensitive lines helps improve the microphone's detection accuracy.

[0029] This application provides a two-dimensional vector microphone. By processing one-dimensional vector pickup structures for sound pickup in two directions on both sides of a wafer, a two-dimensional vector pickup structure is integrated on a single chip. The signal-to-noise ratio (SNR) of any dimension in the two-dimensional vector pickup structure is higher than that of a standalone one-dimensional vector microphone, effectively improving the device's SNR and eliminating the mutual interference between sound pickups in the two directions. Furthermore, the two-dimensional vector microphone provided in this application can be better packaged, resulting in a higher SNR gain; and the two-dimensional directivity centers coincide, leading to better directivity consistency. It also boasts advantages such as mature and simple processing technology and high process reliability.

[0030] This application embodiment also provides a two-dimensional vector microphone, including: a wafer, a first pickup structure and a second pickup structure, the first pickup structure and the second pickup structure are disposed on the same side in the thickness direction of the wafer, the first pickup structure includes at least two oppositely disposed first thermal resistance lines, the first pickup structure is used to receive incident sound waves in a third direction, the second pickup structure includes at least two oppositely disposed second thermal resistance lines, the second pickup structure is used to receive incident sound waves in a fourth direction, the third direction is orthogonal to the fourth direction.

[0031] The two-dimensional vector microphone provided in this application embodiment achieves the integration of a two-dimensional vector pickup structure on a single chip by processing a one-dimensional vector pickup structure for pickup in two directions on the same side (front or side) of the wafer. The signal-to-noise ratio of any dimension in the two-dimensional vector pickup structure is higher than that of a single one-dimensional vector microphone, which can effectively improve the signal-to-noise ratio of the device and eliminate the mutual interference of pickup in two directions.

[0032] In one possible implementation, the wafer includes a support body, the ends of the first and second sound pickup structures are fixed to the support body, and a hollow area or recess is provided on the inner side of the support body. The hollow area or recess extends through the thickness direction of the wafer, and at least a portion of the length of the first and second sound pickup structures is disposed in the hollow area or recess.

[0033] The design of the cutouts and recesses provides space for acoustic vibrations and prevents heat loss caused by thermal resistance lines being too close to the wafer surface, thus allowing heat to be localized in the air.

[0034] In one possible implementation, the center of the first pickup structure coincides with the center of the second pickup structure.

[0035] The directional centers of the first and second pickup structures coincide, so the two-dimensional vector microphone has better directional consistency compared to related technologies that combine two one-dimensional vector microphones.

[0036] In one possible implementation, it further includes: a cross-shaped heating line that divides the surface of the wafer into a first quadrant, a second quadrant, a third quadrant, and a fourth quadrant arranged counterclockwise; two of the two opposing first thermal resistance lines are located in the first quadrant and the third quadrant, respectively; and two of the two opposing second thermal resistance lines are located in the second quadrant and the fourth quadrant, respectively.

[0037] The first and second pickup structures can be heated evenly and comprehensively using the cross-shaped heating wires.

[0038] In one possible implementation, both the first thermal resistance line and the second thermal resistance line are sensitive lines, and the width of the sensitive line is less than or equal to the width of the cross heating line.

[0039] The width of the heating wire can be greater than the width of the sensing wire to increase the heating power of the heating wire and improve the detection sensitivity of the sensing wire. Attached Figure Description

[0040] Figure 1 A schematic diagram of the structure of a two-dimensional vector microphone provided in an embodiment of this application;

[0041] Figure 2 This is a schematic diagram of the structure of the first pickup structure provided in an embodiment of this application;

[0042] Figure 3 This is a schematic diagram of the static temperature field distribution of the first pickup structure provided in an embodiment of this application;

[0043] Figure 4 This is a schematic diagram of the dynamic temperature field distribution of the first pickup structure provided in an embodiment of this application;

[0044] Figure 5 A schematic diagram of the hot wire structure of a two-dimensional vector microphone provided in an embodiment of this application;

[0045] Figure 5a A schematic diagram of the hot wire structure of a two-dimensional vector microphone provided in an embodiment of this application;

[0046] Figure 6 A schematic diagram of the packaging structure of a two-dimensional vector microphone provided in an embodiment of this application;

[0047] Figure 7 for Figure 6 Corresponding explosion diagram;

[0048] Figure 8 A thermal field distribution curve on the YZ section is provided in an embodiment of this application when only the first pickup structure is provided;

[0049] Figure 9 A thermal field distribution curve on the YZ section of a two-dimensional vector microphone provided in an embodiment of this application;

[0050] Figure 10 A schematic diagram of another structure of a two-dimensional vector microphone provided in an embodiment of this application;

[0051] Figure 11a A schematic diagram of the heatline distribution of a two-dimensional vector microphone provided in an embodiment of this application;

[0052] Figure 11b A schematic diagram of another heatline distribution for a two-dimensional vector microphone provided in an embodiment of this application;

[0053] Figure 12 A schematic diagram of the structure of a two-dimensional vector microphone provided in an embodiment of this application;

[0054] Figure 13 This is a schematic diagram of the hot wire structure of a two-dimensional vector microphone provided in an embodiment of this application.

[0055] Explanation of reference numerals in the attached figures:

[0056] 100 - Wafer; 11 - Support body; 12 - Hollowed-out area; 13 - Recessed part; 21 - First sound pickup structure; 211 - First thermal resistance line; 22 - Second sound pickup structure; 221 - Second thermal resistance line; 20 - Thermal resistance line; 201 - Heating line; 202 - Sensitive line; 300 - Circuit board; 41 - First package housing; 411 - First sound guide hole; 42 - Second package housing; 421 - Second sound guide hole; 400 - Third direction; 500 - Fourth direction; 600 - Cross heating line. Detailed Implementation

[0057] Compared to omnidirectional microphones, microphone arrays, and traditional directional microphones, sound vector microphone technology has advantages such as good frequency and spatial consistency in sound signal acquisition, strong noise suppression capabilities, and good long-distance sound pickup effects, making it an important technological direction for sound pickup in smart terminals.

[0058] Current research on vector microphones mainly includes rocker vector microphones, filament vector microphones, and hot-wire vector microphones. The first two types are still in the research stage, and rocker vector microphones suffer from problems such as poor frequency response consistency, while filament vector microphones are difficult to manufacture and have poor feasibility. Hot-wire vector microphones, on the other hand, have been applied in industrial measurement and have advantages such as high signal-to-noise ratio and simple manufacturing.

[0059] Hot-wire vector microphones typically only enable one-dimensional detection. They typically consist of at least two thermally resistive wires arranged parallel to each other with a certain spacing. The working principle of a hot-wire vector microphone is as follows: when sound waves are incident on the thermally resistive wires, the reciprocating motion of the medium particles (air, water, etc.) creates forced convection heat transfer, transferring heat from one wire to the other. This causes a change in the temperature of the wires, resulting in a change in their respective resistance values. By detecting this change in resistance, vector information about the vibration velocity of the medium particles can be obtained. Hot-wire vector microphones directly measure the particle velocity of the medium's sound field and exhibit a figure-eight directivity independent of frequency.

[0060] However, hot-wire vector microphones generally only achieve one-dimensional detection. Related technologies implement single-chip two-dimensional vector microphones by combining two one-dimensional vector microphones. These two microphones are used to detect sound field information in two different directions, thus achieving two-dimensional detection. Combining two one-dimensional vector microphones requires external assembly to achieve two-dimensional sound pickup. This not only doubles the overall microphone space, leading to poor consistency, complex assembly, and large size, but also inevitably causes structural crosstalk between the two microphones. Sound waves incident from one direction can be scattered and enter the vector microphone detecting the other direction, generating unwanted signals and affecting the sensor's sensitivity and directional characteristics.

[0061] To address the aforementioned issues, this application provides a two-dimensional vector microphone. By processing one-dimensional vector pickup structures for sound pickup in two directions on both sides of the wafer, or by processing one-dimensional vector pickup structures for sound pickup in two directions on the same side (front or back) of the wafer, a two-dimensional vector pickup structure can be integrated on a single chip. This effectively improves the signal-to-noise ratio of the device, eliminates the mutual interference between sound pickup in two directions, and has the advantages of simple processing and high consistency.

[0062] The two-dimensional vector microphone provided in this application will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0063] Figure 1 This is a schematic diagram of a two-dimensional vector microphone provided in one embodiment of this application. (Reference) Figure 1 As shown, this application embodiment provides a two-dimensional vector microphone, which may include a wafer 100, a first pickup structure 21, and a second pickup structure 22. The first pickup structure 21 and the second pickup structure 22 may be respectively disposed on both sides of the wafer 100 in the thickness direction. The first pickup structure 21 may extend along a first direction, and the second pickup structure 22 may extend along a second direction. The first direction and the second direction are orthogonal.

[0064] It should be noted that the thickness direction of wafer 100 is the Z direction in the figure, and the first and second directions are the X and Y directions, respectively.

[0065] In this embodiment, wafer 100 can be, for example, a silicon wafer. The thickness of the silicon wafer is not specifically limited, but can be greater than 0 μm and less than or equal to 500 μm. The pickup direction of the first pickup structure 21 is perpendicular to the vibration velocity of the medium particles in the first direction, i.e., the vibration velocity of the medium particles in the second direction (Y direction); the pickup direction of the second pickup structure 22 is perpendicular to the vibration velocity of the medium particles in the second direction, i.e., the vibration velocity of the medium particles in the first direction (X direction).

[0066] The first pickup structure 21 may include at least two parallel thermal resistance lines 20, and the second pickup structure 22 may include at least two parallel thermal resistance lines 20. The thermal resistance lines 20 of the first pickup structure 21 are arranged side by side with a certain spacing, and the thermal resistance lines 20 of the second pickup structure 22 are arranged side by side with a certain spacing.

[0067] Figure 2 This is a schematic diagram of the first pickup structure provided in an embodiment of this application. (Reference) Figure 2 As shown, in one possible embodiment, the first pickup structure 21 may include three thermal resistance lines 20, which are arranged in parallel and have a certain spacing. The middle thermal resistance line 20 serves as a heating line 201, and a thermal resistance line 20 is arranged on each side of the heating line 201 as a sensitive line 202. The heating line 201 is used for self-heating, and the sensitive line 202 is used to detect temperature changes. Figure 2 The arrow in the diagram points to the direction of sound wave incidence. The direction of sound wave incidence is perpendicular to the extension direction of thermal resistance line 20. After the sound wave is incident, the reciprocating motion of the medium particles forms forced convection heat transfer, which will cause the temperature of the two sensitive lines 202 to change.

[0068] Figure 3 This is a schematic diagram of the static temperature field distribution of a first sound pickup structure according to an embodiment of this application, where the horizontal axis represents the position coordinates of the first sound pickup structure in the second direction, and the vertical axis represents the temperature. (Reference) Figure 3 As shown, in the second direction, the overall temperature trend is first increased and then decreased, with the highest temperature at heating wire 201. Since the heat transfer efficiency between heating wire 201 and sensing wire 202 is higher than that between heating wire 201 and air, the temperature has two higher peaks at the two sensing wires 202, which are lower than the temperature peak at heating wire 201.

[0069] When a sound wave is incident, the reciprocating motion of the medium particles forms forced convection heat transfer, transferring the heat from one sensitive line 202 to the other sensitive line 202, causing the temperatures of the two sensitive lines 202 to change in opposite directions, resulting in changes in their respective resistance values. By detecting the changes in resistance values, the velocity vector information of the medium particles can be obtained. Figure 4 This is a schematic diagram of the dynamic temperature field distribution of a first sound pickup structure provided in an embodiment of this application. (Reference) Figure 4 As shown, for example, when a sound wave is incident in the direction of the solid arrow in the figure, the temperature at the sensitive line 202 on the side closer to the direction of the sound wave incident will decrease, while the temperature at the sensitive line 202 on the side farther away from the direction of the sound wave incident will increase.

[0070] Assuming the sound wave is a DC signal, i.e., frequency f = 0, the temperature change ΔT(0) of the sensitive line 202 can be calculated using the following formula:

[0071]

[0072] Where i represents an imaginary number, f represents the frequency, v represents the particle velocity, P represents the power applied to the heating wire 201, k represents the thermal conductivity of the medium, ly represents the length of the thermal resistance wire, D represents the thermal diffusivity of the medium, a represents the distance between the sensitive wire 202 and the heating wire 201, and γ represents the Euler constant (0.577).

[0073] When the frequency of the sound wave is not 0, the temperature change ΔT(f) of the sensitive line 202 can be calculated using the following formula:

[0074]

[0075] Where △T(0) is calculated by formula 1, f d This refers to the coefficient of influence of air on heat conduction, f. hc This refers to the influence coefficient of the thermal resistance wire's own material (e.g., heat capacity, wire length, etc.) on heat conduction. d and f hc The following formula can be used for calculation:

[0076]

[0077]

[0078] Where, k air ρ represents the thermal conductivity of air, L represents the length of the thermal resistance line, h represents the thickness of the thermal resistance line, ρ represents the density, cp represents the specific heat capacity at constant pressure, air represents air, and sensor represents the thermal resistance line.

[0079] The aforementioned pickup structure can be connected in a pickup detection circuit. The temperature change ΔT(f) of the sensitive line 202 will cause a change in the resistance of the sensitive line 202, thereby causing a change in the output voltage in the pickup detection circuit. By detecting the change in output voltage, the vibration velocity vector information of the medium particles can be obtained, thereby determining the incident direction and frequency of the sound wave, and thus achieving sound pickup.

[0080] Figure 5 This is a schematic diagram of the hot wire structure of a two-dimensional vector microphone provided in one embodiment of this application. (Reference) Figure 1 and Figure 5 As shown, the first pickup structure 21 and the second pickup structure 22 are respectively disposed on two mutually parallel planes (XY planes). The extension direction of the first pickup structure 21 is orthogonal to the extension direction of the second pickup structure 22, and the center of the first pickup structure 21 and the center of the second pickup structure 22 coincide in the thickness direction of the wafer 100, that is, the centers of the first pickup structure 21 and the second pickup structure 22 are aligned in the Z direction. The directional centers of the first pickup structure 21 and the second pickup structure 22 coincide, therefore, compared with related technologies that combine two one-dimensional vector microphones, the two-dimensional vector microphone has better directional consistency.

[0081] The first pickup structure 21 and the second pickup structure 22 are spaced apart in the thickness direction of the wafer 100, and the spacing can be greater than 0 μm and less than or equal to 500 μm. In one possible embodiment, the spacing between the first pickup structure 21 and the second pickup structure 22 is between 50 and 200 μm.

[0082] This application does not end here. Figure 5a This is a schematic diagram of the hot wire structure of a two-dimensional vector microphone provided in an embodiment of this application, with reference to... Figure 5a As shown, in the two-dimensional vector microphone provided in this application embodiment, the first pickup structure 21 and the second pickup structure 22 can also be disposed on the same side of the wafer 100 in the thickness direction, such as the front or back side of the wafer 100. In this case, the distance between the first pickup structure 21 and the second pickup structure 22 in the thickness direction of the wafer 100 is zero. The extending direction of the first pickup structure 21 is orthogonal to the extending direction of the second pickup structure 22, and the center of the first pickup structure 21 coincides with the center of the second pickup structure 22. For example, as... Figure 5aAs shown, the first pickup structure 21 includes a heating wire 201 and two sensitive wires 202 located on both sides of the heating wire 201. The second pickup structure 22 includes a heating wire 201 and two sensitive wires 202 located on both sides of the heating wire 201. When the first pickup structure 21 and the second pickup structure 22 are orthogonal, the heating wires 201 of the first pickup structure 21 and the heating wires 201 of the second pickup structure 22 form a cross shape, which is used to self-heat the surrounding air. The orthogonal sensitive wires 202 located in the four quadrants of the cross-shaped heating wire 201 are used to detect temperature. It should be noted that an insulating material needs to be added at the contact point between the sensitive wire 202 and the heating wire 201 to prevent direct heat conduction between the sensitive wire 202 and the heating wire 201. At this time, the pickup direction of the orthogonal first pickup structure 21 and the second pickup structure 22 is... Figure 5a The direction indicated by the hollow arrow can be understood as the 45-degree and 135-degree directions with the cross-shaped heating line as the coordinate axis. The directional centers of the first pickup structure 21 and the second pickup structure 22 coincide. Therefore, compared with related technologies that combine two one-dimensional vector microphones, the two-dimensional vector microphone has better directional consistency.

[0083] The two-dimensional vector microphone provided in this application embodiment achieves sound pickup in two directions by setting a first sound pickup structure and a second sound pickup structure on the front and back sides of a wafer, or setting a first sound pickup structure and a second sound pickup structure on the same side of a wafer, respectively. This realizes two-dimensional vector sound pickup on a single chip. Compared with related technologies that combine two one-dimensional vector microphones, the two-dimensional vector microphone occupies a smaller volume.

[0084] Furthermore, the two-dimensional vector microphone structure provided in this application embodiment allows the two pickup structures to be respectively disposed on the front and back sides of the wafer, which facilitates the independent packaging of the two pickup structures, thereby avoiding crosstalk between the two pickup structures. The packaging structure of the two-dimensional vector microphone structure provided in this application embodiment is described below with reference to the specific accompanying drawings.

[0085] Figure 6 This is a schematic diagram of the packaging structure of a two-dimensional vector microphone provided in an embodiment of this application. Figure 7 for Figure 6 Corresponding explosion diagram. (Reference) Figure 6 and Figure 7 As shown, the two-dimensional vector microphone provided in this application embodiment may further include a circuit board 300, a first encapsulation housing 41, and a second encapsulation housing 42.

[0086] An opening can be provided on the circuit board 300, and the wafer 100 can be embedded in the opening. The first pickup structure 21 and the second pickup structure 22 on the front and back sides of the wafer 100 are exposed on both sides of the circuit board 300, respectively. The first packaging shell 41 and the second packaging shell 42 can be respectively provided on both sides of the circuit board 300. The first packaging shell 41 can cover the first pickup structure 21, and the second packaging shell 42 can cover the second pickup structure 22.

[0087] The first encapsulation housing 41 is provided with a first sound guide hole 411, which connects to two opposite sides of the first encapsulation housing 41. The second encapsulation housing 42 is provided with a second sound guide hole 421, which connects to two opposite sides of the second encapsulation housing 42. After the first encapsulation housing 41 and the second encapsulation housing 42 are assembled, the extension direction of the first sound guide hole 411 is the second direction, and the extension direction of the second sound guide hole 421 is the first direction.

[0088] The first encapsulation shell 41 can be made of resin or other materials through an integral molding process, and the second encapsulation shell 42 can also be made of resin or other materials through an integral molding process. The structures of the first encapsulation shell 41 and the second encapsulation shell 42 can be the same. The above-mentioned encapsulation structure can be achieved by ensuring that the orientation of the first sound guide hole 411 and the second sound guide hole 421 is different during assembly, thereby reducing production costs.

[0089] The first sound guide hole 411 and the second sound guide hole 421 have the same structure. The first sound guide hole 411 can be regarded as two horn-shaped through holes arranged in opposite directions connected together. The cross-section of the opening of the first sound guide hole 411 gradually decreases from the outside to the inside of the shell to achieve a good sound collection effect.

[0090] The assembly process of the two-dimensional vector microphone provided in this application embodiment can be as follows: First, a first pickup structure 21 and a second pickup structure 22 are fabricated on both sides of the wafer 100; then, the wafer 100 is connected to the circuit board 300, so that the first pickup structure 21 and the second pickup structure 22 are exposed on both sides of the circuit board 300; the first encapsulation housing 41 and the second encapsulation housing 42 are respectively covered outside the first pickup structure 21 and the second pickup structure 22, ensuring that the extension direction of the first sound guide hole 411 is perpendicular to the extension direction of the first pickup structure 21, and the extension direction of the second sound guide hole 421 is perpendicular to the extension direction of the second pickup structure 22; finally, the first encapsulation housing 41 and the second encapsulation housing 42 are fixed by means of bonding or the like.

[0091] On the one hand, the first packaging shell 41 and the second packaging shell 42 can protect the wafer 100, the first sound pickup structure 21 and the second sound pickup structure 22; on the other hand, the circuit board 300 separates the front and back sides of the wafer 100, the first sound pickup structure 21 can detect sound waves incident from the second direction through the first sound guide hole 411, and the second sound pickup structure 22 can detect sound waves incident from the first direction through the second sound guide hole 421. The sound waves on both sides do not interfere with each other, thus improving the sensitivity of the two-dimensional vector microphone.

[0092] The two-dimensional vector microphone provided in this application embodiment has two pickup structures respectively disposed on the front and back sides of the wafer, which can better match the package and achieve a higher signal-to-noise ratio gain in a small package size. For example, with the overall package size of 1 inch, a sensitivity improvement of approximately 12dB can be achieved.

[0093] In one possible implementation, continue to refer to Figure 1 As shown, the wafer 100 may include a support body 11, the ends of the first sound pickup structure 21 and the second sound pickup structure 22 are fixed to the support body 11, and a hollow area 12 is formed on the inner side of the support body 11. At least a portion of the length of the first sound pickup structure 21 and the second sound pickup structure 22 is positioned facing the hollow area 12. The hollow area 12 can be formed by laser processing.

[0094] It should be noted that, in Figure 1 In the embodiment shown, the interior of the wafer 100 is hollowed out. This hollowed-out area will bring about the particle vibration velocity along the thickness direction of the wafer 100. That is, the direction of the particle movement is perpendicular to the plane containing the first direction and the second direction. It will not be detected by the first pickup structure 21 and the second pickup structure 22, so it will not affect the directional characteristics of the two-dimensional vector microphone.

[0095] The supporting body 11 can be configured as a rectangular frame structure. The two ends of the first pickup structure 21 can be connected to two opposite sides of the rectangular frame and positioned at the midpoint of the sides. The two ends of the second pickup structure 22 can be connected to two other opposite sides of the rectangular frame and positioned at the midpoint of the sides. This configuration ensures that the first pickup structure 21 and the second pickup structure 22 are orthogonal and coincide in the center along the thickness direction of the wafer 100.

[0096] The hollowed-out area 12 can also be set as a rectangle. The hollowed-out area 12 reduces the overall weight of the wafer 100. Furthermore, it allows air to exist between the thermal resistance lines of the first pickup structure 21 and the second pickup structure 22, without wafer material obstruction. This facilitates thermal coupling between the first pickup structure 21 and the second pickup structure 22, improving detection sensitivity. The thermal coupling principle of the first pickup structure 21 and the second pickup structure 22 is explained below with reference to the thermal field distribution diagram.

[0097] Figure 8 This application provides a thermal field distribution curve on the YZ section when only the first pickup structure is provided, as an embodiment of the present application. Figure 8 In the graph, the horizontal axis represents the position in the second direction, and the vertical axis represents the temperature. (Reference) Figure 8 As shown, in the second direction, the overall trend of temperature is to first increase and then decrease, with the highest temperature at heating line 201 and the steepest slope of the curve at heating line 201.

[0098] Figure 9 A thermal field distribution curve on the YZ section of a two-dimensional vector microphone provided in an embodiment of this application, wherein the lower curve is... Figure 8 The curve in the image is used for comparison. (Reference) Figure 9 As shown, due to the thermal coupling between the first pickup structure 21 and the second pickup structure 22, the temperatures in the two dimensions can be superimposed on each other. The temperature at the sensitive line 202 is higher, and the temperature fluctuation range is larger after the sound wave is incident. Therefore, the resistance change is more obvious, making the signal-to-noise ratio of any dimension in the two-dimensional vector microphone higher than that of a single one-dimensional vector microphone.

[0099] In a specific example, the length of the thermal resistance line 20 of the first pickup structure 21 and the second pickup structure 22 is 1 mm, the spacing between two adjacent thermal resistance lines 20 is 60 μm, the linewidth of the thermal resistance line 20 is 2 μm, and the thickness of the thermal resistance line 20 is 0.3 μm. When the distance between the first pickup structure 21 and the second pickup structure 22 in the thickness direction of the wafer 100 is 300 μm, a thermally coupled two-dimensional vector microphone is present, which can achieve a sensitivity improvement of 1.2 dB compared to a one-dimensional vector microphone. When the distance between the first pickup structure 21 and the second pickup structure 22 in the thickness direction of the wafer 100 is 100 μm, a thermally coupled two-dimensional vector microphone is present, which can achieve a sensitivity improvement of 3 dB compared to a one-dimensional vector microphone.

[0100] Figure 10 This is a schematic diagram of another structure of a two-dimensional vector microphone provided in one embodiment of this application. (See reference...) Figure 10As shown, in another possible embodiment, the wafer 100 includes a support body 11, the ends of the first pickup structure 21 and the second pickup structure 22 are fixed on the support body 11, and recesses 13 are respectively provided on both sides of the support body 11 in the thickness direction. At least a portion of the length of the first pickup structure 21 and the second pickup structure 22 is disposed facing the recesses 13.

[0101] Similarly, compared to Figure 1 In the provided embodiment, the supporting body 11 can be configured as a rectangular frame structure. The two ends of the first pickup structure 21 can be respectively connected to two opposite sides of the rectangular frame and are located at the midpoint of the sides. The two ends of the second pickup structure 22 can be respectively connected to two other opposite sides of the rectangular frame and are located at the end points of the sides. This configuration ensures that the first pickup structure 21 and the second pickup structure 22 are orthogonal and coincide in the center along the thickness direction of the wafer 100.

[0102] The recess 13 can also be set as a rectangle. The recess 13 can be formed by recessing a certain depth from the surface of the wafer 100. The setting of the recess 13 can provide space for acoustic vibration on the one hand, and avoid the thermal resistance line 20 from being in close contact with the surface of the wafer 100, thus preventing heat loss. In other words, it is beneficial for the heat generated by the thermal resistance line 20 to be localized in the air.

[0103] The two-dimensional vector microphone provided in this application embodiment is also applicable to the above-mentioned... Figure 6 and Figure 7 The provided packaging structure, and since there are no cutouts inside the wafer 100, there are no particle velocities along the thickness direction of the wafer 100, thus having no effect on the directional characteristics of the two-dimensional vector microphone.

[0104] In the above embodiments of this application, the thermal resistance wire 20 can be a metal wire, and can be made of doped silicon, metallic materials (platinum Pt, nickel Ni, Ti, Al, etc.) or multilayer composite materials (W / Ti / Pt, Al / Si, etc.). Figure 1 and Figure 10 In the provided embodiment, the pickup structure is a three-wire structure, which includes a heating wire 201 and sensitive wires 202 disposed on both sides of the heating wire 201. The widths of the heating wire 201 and the sensitive wires 202 can be the same, or the width of the heating wire 201 can be greater than the width of the sensitive wire 202. It is easy to understand that a wider heating wire 201 can ensure the heating power of the heating wire 201, while a narrower sensitive wire 202 can increase the rate of temperature change, thereby improving the detection sensitivity.

[0105] In other possible implementations, the pickup structure may also be a two-wire structure or a multi-wire structure. Figure 11aThis is a schematic diagram of the heatsink distribution of a two-dimensional vector microphone provided in one embodiment of this application. (Reference) Figure 11a As shown, the pickup structure can be a two-wire structure, that is, it includes two parallel thermal resistance wires 20 with a certain spacing. The two thermal resistance wires 20 can be used as heating wires and sensitive wires at the same time. Figure 11b This is a schematic diagram of another heatline distribution for a two-dimensional vector microphone provided in one embodiment of this application. (See reference...) Figure 11b As shown, the pickup structure can be a multi-line structure, with a heating line 201 located in the middle and multiple sensitive lines 202 set on both sides of the heating line 201 to improve detection accuracy.

[0106] The two-dimensional vector microphone provided in this application integrates a two-dimensional vector pickup structure on a single chip by processing one-dimensional vector pickup structures for pickup in two directions on both sides of the wafer, or by processing one-dimensional vector pickup structures for pickup in two directions on the same side (front or back) of the wafer. The signal-to-noise ratio (SNR) of any dimension of the two-dimensional vector pickup structure is higher than that of a standalone one-dimensional vector microphone, effectively improving the device's SNR and eliminating the mutual interference between pickups in two directions. Furthermore, the two-dimensional vector microphone provided in this application can be better matched to the package, resulting in a greater SNR gain; and the two-dimensional directivity centers coincide, resulting in better two-dimensional directivity consistency, and it has the advantages of mature and simple processing technology and high process reliability.

[0107] This application also provides a two-dimensional vector microphone. Figure 12 This is a schematic diagram of a two-dimensional vector microphone provided in an embodiment of this application, with reference to... Figure 12 As shown, the two-dimensional vector microphone provided in this application embodiment includes: a wafer 100, a first pickup structure 21 and a second pickup structure 22, wherein the first pickup structure 21 and the second pickup structure 22 are disposed on the same side in the wafer thickness direction.

[0108] The first pickup structure 21 includes at least two oppositely arranged first thermal resistance lines 211, and the first pickup structure 21 is used to receive incident sound waves in the third direction. The second pickup structure 22 includes at least two oppositely arranged second thermal resistance lines 221, and the second pickup structure 22 is used to receive incident sound waves in the fourth direction, wherein the third direction is orthogonal to the fourth direction.

[0109] Understandable, Figure 12 Can be regarded as Figure 5a A variation, about to Figure 5a In the cross-shaped heating wire 201, the sensitive wires 202 in each of the four quadrants intersect and connect to form a right-angled whole. At this time, the two sensitive wires 202 in the first quadrant are connected and electrically conductive, and the same applies to the second, third, and fourth quadrants. Compared to Figure 5a , Figure 12 The two-dimensional vector microphone shown makes the fabrication of micro-electro-mechanical systems (MEMS) easier.

[0110] It should be noted that the shapes of the first thermal resistance line 211 and the second thermal resistance line 221 are not limited to those specified in the original text. Figure 12 The right-angled shapes shown can be represented by, for example, the first thermal resistance line 211 and the second thermal resistance line 221. The right angles can be chamfered, or the first thermal resistance line 211 and the second thermal resistance line 221 can be set as arcs. As long as the first pickup structure 21 can receive the incident sound wave in the third direction and the second pickup structure 22 can receive the incident sound wave in the fourth direction, and the third direction is orthogonal to the fourth direction, the shape of the first thermal resistance line 211 and the second thermal resistance line 221 is not restricted.

[0111] and Figure 1 and Figure 10 The structural setup of the medium crystal 100 is similar. Figure 12 The wafer 100 may include a support body. The ends of the first sound pickup structure 21 and the second sound pickup structure 22 are fixed to the support body. A hollow area or recess is formed on the inner side of the support body, extending through the thickness direction of the wafer. At least a portion of the length of the first sound pickup structure 21 and the second sound pickup structure 22 is disposed within the hollow area or recess. This provides space for sound wave vibration and prevents the first thermal resistance line 211 and the second thermal resistance line 221 from being in close contact with the surface of the wafer 100, thus preventing heat loss and allowing heat to be localized in the air. (Continue to refer to...) Figure 12 As shown, in order to enhance the directional consistency of the two-dimensional vector microphone, the center of the first pickup structure 21 and the center of the second pickup structure 22 can be set to coincide.

[0112] Figure 13 This is a schematic diagram of the hot wire structure of a two-dimensional vector microphone provided in an embodiment of this application, with reference to... Figure 13 As shown, in Figure 12 Based on this, the two-dimensional vector microphone also includes a cross heating line 600, which divides the surface of the wafer 100 into a first quadrant, a second quadrant, a third quadrant, and a fourth quadrant arranged counterclockwise. Two of the two opposing first thermal resistance lines 211 are located in the first quadrant and the third quadrant, respectively. Two of the two opposing second thermal resistance lines 221 are located in the second quadrant and the fourth quadrant, respectively. The cross heating line 600 can heat the first thermal resistance lines 211 and the second thermal resistance lines 221 comprehensively and uniformly.

[0113] In some embodiments of this application, the first thermal resistance line 211 and the second thermal resistance line 221 are sensitive lines, and the width of the first thermal resistance line 211 and the second thermal resistance line 221 is smaller than the width of the cross heating line 600, which can improve the heating power of the cross heating line 600 and improve the detection sensitivity of the first thermal resistance line 211 and the second thermal resistance line 221.

[0114] The two-dimensional vector microphone provided in this application embodiment achieves the integration of a two-dimensional vector pickup structure on a single chip by processing a one-dimensional vector pickup structure for pickup in two directions on the same side (front or side) of the wafer. The signal-to-noise ratio of any dimension in the two-dimensional vector pickup structure is higher than that of a single one-dimensional vector microphone, which can effectively improve the signal-to-noise ratio of the device and eliminate the mutual interference of pickup in two directions.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of this application, and are not intended to limit them; although the embodiments of this application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A two-dimensional vector microphone, characterized in that, include: Wafer, first pickup structure, and second pickup structure; The first sound pickup structure and the second sound pickup structure are respectively disposed on both sides of the wafer in the thickness direction, or the first sound pickup structure and the second sound pickup structure are disposed on the same side of the wafer in the thickness direction. The first pickup structure extends along a first direction, and the second pickup structure extends along a second direction. The first direction and the second direction are orthogonal. The first pickup structure includes at least two parallel thermal resistance lines, and the second pickup structure includes at least two parallel thermal resistance lines. The wafer includes a support body, and the ends of the first pickup structure and the second pickup structure are fixed to the support body; The inner side of the support body has a hollow area that extends through the thickness direction of the wafer. At least a portion of the length of the first and second sound pickup structures faces the hollow area. Alternatively, recesses are provided on both sides of the support body in the thickness direction, and at least a portion of the length of the first and second sound pickup structures faces the recesses.

2. The two-dimensional vector microphone according to claim 1, characterized in that, When the first pickup structure and the second pickup structure are respectively disposed on both sides of the wafer in the thickness direction, the two-dimensional vector microphone further includes a circuit board, a first packaging shell and a second packaging shell; the circuit board is provided with an opening, the wafer is embedded in the opening and the first pickup structure and the second pickup structure are respectively exposed on both sides of the circuit board; The first encapsulation housing is provided with a first sound guide hole, which connects two opposite sides of the first encapsulation housing. The second encapsulation housing is provided with a second sound guide hole, which connects two opposite sides of the second encapsulation housing. The first encapsulation housing and the second encapsulation housing are respectively disposed on both sides of the circuit board. The first sound guide hole extends along the second direction, and the second sound guide hole extends along the first direction. The first sound pickup structure is located at the center of the first sound guide hole, and the second sound pickup structure is located at the center of the second sound guide hole.

3. The two-dimensional vector microphone according to claim 2, characterized in that, The first and second packaging shells have the same structure and are fixedly connected.

4. The two-dimensional vector microphone according to any one of claims 1-3, characterized in that, The centers of the first and second pickup structures coincide in the thickness direction of the wafer.

5. The two-dimensional vector microphone according to claim 4, characterized in that, When the first pickup structure and the second pickup structure are respectively disposed on both sides of the wafer in the thickness direction, the distance between the first pickup structure and the second pickup structure in the thickness direction of the wafer is greater than 0 μm and less than or equal to 500 μm. When the first pickup structure and the second pickup structure are disposed on the same side of the wafer in the thickness direction, the distance between the first pickup structure and the second pickup structure in the thickness direction of the wafer is zero.

6. The two-dimensional vector microphone according to any one of claims 1-3 and 5, characterized in that, The first pickup structure includes three thermal resistance lines, which are divided into a heating line and two sensitive lines, with the two sensitive lines respectively disposed on both sides of the heating line; the second pickup structure includes three thermal resistance lines, which are divided into a heating line and two sensitive lines, with the two sensitive lines respectively disposed on both sides of the heating line.

7. The two-dimensional vector microphone according to claim 4, characterized in that, The first pickup structure includes three thermal resistance lines, which are divided into a heating line and two sensitive lines, with the two sensitive lines respectively disposed on both sides of the heating line; the second pickup structure includes three thermal resistance lines, which are divided into a heating line and two sensitive lines, with the two sensitive lines respectively disposed on both sides of the heating line.

8. The two-dimensional vector microphone according to claim 6, characterized in that, The width of the sensitive line is less than or equal to the width of the heating line.

9. The two-dimensional vector microphone according to claim 7, characterized in that, The width of the sensitive line is less than or equal to the width of the heating line.

10. The two-dimensional vector microphone according to any one of claims 1-3 and 5, characterized in that, The first pickup structure includes multiple thermal resistance lines, which are divided into a heating line and multiple sensitive lines respectively disposed on both sides of the heating line; the second pickup structure includes multiple thermal resistance lines, which are divided into a heating line and multiple sensitive lines respectively disposed on both sides of the heating line.

11. The two-dimensional vector microphone according to claim 4, characterized in that, The first pickup structure includes multiple thermal resistance lines, which are divided into a heating line and multiple sensitive lines respectively disposed on both sides of the heating line; the second pickup structure includes multiple thermal resistance lines, which are divided into a heating line and multiple sensitive lines respectively disposed on both sides of the heating line.

12. A two-dimensional vector microphone, characterized in that, include: Wafer, first pickup structure, and second pickup structure; The first pickup structure and the second pickup structure are disposed on the same side in the wafer thickness direction; The first pickup structure includes at least two opposing first thermal resistance lines, and the first pickup structure is used to receive incident sound waves in a third direction. The second pickup structure includes at least two opposing second thermal resistance lines, and the second pickup structure is used to receive incident sound waves in a fourth direction, wherein the third direction is orthogonal to the fourth direction. The wafer includes a support body, the ends of the first sound pickup structure and the second sound pickup structure are fixed on the support body, and a hollow area or a recess is provided on the inner side of the support body. The hollow area or the recess extends through the thickness direction of the wafer, and at least a portion of the length of the first sound pickup structure and the second sound pickup structure is disposed in the hollow area or the recess.

13. The two-dimensional vector microphone according to claim 12, characterized in that, The center of the first pickup structure coincides with the center of the second pickup structure.

14. The two-dimensional vector microphone according to claim 12 or 13, characterized in that, Also includes: Cross-shaped heating wire; The cross-shaped heating lines divide the surface of the wafer into a first quadrant, a second quadrant, a third quadrant, and a fourth quadrant arranged counterclockwise. Two of the at least two opposing first thermal resistance lines are located in the first quadrant and the third quadrant, respectively, and two of the at least two opposing second thermal resistance lines are located in the second quadrant and the fourth quadrant, respectively.

15. The two-dimensional vector microphone according to claim 14, characterized in that, Both the first thermal resistance line and the second thermal resistance line are sensitive lines, and the width of the sensitive line is less than or equal to the width of the cross heating line.

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