CN115474115A - Two-dimensional vector microphone - Google Patents
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- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
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- H04R1/08—Mouthpieces; Microphones; Attachments therefor
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- H—ELECTRICITY
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- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R3/00—Circuits for transducers, loudspeakers or microphones
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Abstract
The embodiment of the application provides a two-dimensional vector microphone, includes: the device comprises a wafer, a first pickup structure and a second pickup structure; first pickup structure and second pickup structure set up the both sides on the thickness direction of wafer respectively, perhaps, first pickup structure with second pickup structure sets up the ascending homonymy of thickness direction of wafer, first pickup structure extends along the first direction, and second pickup structure extends along the second direction, first direction and second direction quadrature, and first pickup structure includes two at least parallel arrangement's thermal resistance line, and second pickup structure includes two at least parallel arrangement's thermal resistance line. The embodiment of the application provides a two-dimensional vector microphone, has good two-dimensional pickup effect.
Description
The present application claims priority from chinese patent application having application number 202110647715.6, entitled "two-dimensional vector microphone", filed by the chinese patent office at 10/06/2021, the entire contents of which are incorporated herein by reference.
Technical Field
The application relates to the technical field of microphones, in particular to a two-dimensional vector microphone.
Background
A Vector microphone, i.e., an Acoustic Vector Sensor (AVS), is a device that converts an Acoustic signal into an electrical signal. The vector microphone comprises a hot-wire vector microphone, sound field information is obtained by detecting the particle vibration velocity, and the vector microphone has the advantages of high signal-to-noise ratio, simplicity in processing and the like.
At present, a hot-wire vector microphone can only realize one-dimensional detection, and a mode of realizing a single-chip two-dimensional vector microphone in the related art is to combine two one-dimensional vector microphones which are respectively used for detecting sound field information in two directions so as to realize two-dimensional detection.
However, when two one-dimensional vector microphones are combined, not only the overall space of the microphones is doubled, but also there is a problem of structural crosstalk between the two one-dimensional vector microphones, which affects the mutually orthogonal directivities of the sensors.
Disclosure of Invention
The embodiment of the application provides a two-dimensional vector microphone, has good two-dimensional pickup effect.
The embodiment of the application provides a two-dimensional vector microphone, includes: the device comprises a wafer, a first sound pickup structure and a second sound pickup structure; first pickup structure and second pickup structure set up the both sides on the thickness direction of wafer respectively, perhaps, first pickup structure with second pickup structure sets up the ascending homonymy of thickness direction of wafer, first pickup structure extends along the first direction, and second pickup structure extends along the second direction, first direction and second direction quadrature, and first pickup structure includes two at least parallel arrangement's thermal resistance line, and second pickup structure includes two at least parallel arrangement's thermal resistance line.
The embodiment of the application provides a two-dimensional vector microphone, through the one-dimensional vector pickup structure that is used for two directions pickups of processing respectively in the positive and negative both sides of wafer, perhaps, the one-dimensional vector pickup structure that is used for two directions pickups of same face (positive or reverse side) processing of wafer to realize the two-dimensional vector pickup structure of integration on the single chip, can effectively promote the SNR of device, and eliminate the influence each other of two orientation pickups.
In a possible embodiment, the wafer includes a supporting body, ends of the first sound pickup structure and the second sound pickup structure are fixed on the supporting body, a hollow area is formed inside the supporting body, the hollow area penetrates through a thickness direction of the wafer, and at least a part of lengths of the first sound pickup structure and the second sound pickup structure faces the hollow area.
Due to the arrangement of the hollow-out area, no wafer material is arranged between the thermal resistance line of the first pickup structure and the thermal resistance line of the second pickup structure, air exists, thermal coupling between the first pickup structure and the second pickup structure is facilitated, thermal fields formed by the front and back hot lines are mutually enhanced, and the signal to noise ratio of the device can be effectively improved.
In a possible implementation manner, the wafer comprises a supporting body, ends of the first sound pickup structure and the second sound pickup structure are fixed on the supporting body, two sides of the supporting body in the thickness direction are respectively provided with a concave part, and at least partial lengths of the first sound pickup structure and the second sound pickup structure are arranged to face the concave parts.
The arrangement of the concave part can provide a space for sound wave vibration on one hand, and can prevent the thermal resistance line from clinging to the surface of the wafer to cause heat loss on the other hand, namely, the arrangement is beneficial to the heat to be locally positioned in the air.
In a possible implementation manner, when the first sound pickup structure and the second sound pickup structure are respectively arranged on two sides of the wafer in the thickness direction, the two-dimensional vector microphone further comprises a circuit board, a first package shell and a second package shell; the circuit board is provided with an opening, the wafer is embedded in the opening, and the first sound pickup structure and the second sound pickup structure are respectively exposed at two sides of the circuit board;
be provided with first leading hole on the first encapsulation casing, first leading hole intercommunication first encapsulation casing two relative sides, the second leading hole has been seted up on the second encapsulation casing, second leading hole intercommunication second encapsulation casing two relative sides, first encapsulation casing and second encapsulation casing set up the both sides at the circuit board respectively, first leading hole extends along the second direction, the second leading hole extends along the first direction, first pickup structure is located the center in first leading hole, second pickup structure is located the center in second leading hole.
The two-dimensional vector microphone that this application embodiment provided, two pickup structures set up respectively at the tow sides of wafer, can match the encapsulation better, accomplish under the encapsulation of small-size, the SNR gain is bigger.
In one possible embodiment, the first encapsulation housing and the second encapsulation housing have the same structure, and the first encapsulation housing and the second encapsulation housing are fixedly connected.
The first packaging shell and the second packaging shell are identical in structure, production cost can be reduced, and the first packaging shell and the second packaging shell are fixedly connected so as to guarantee reliability of the packaging structure.
In one possible embodiment, the center of the first pickup structure and the center of the second pickup structure coincide in a thickness direction of the wafer.
The centers of directivity of the first sound pickup structure and the second sound pickup structure coincide, so that the directivity consistency of the two-dimensional vector microphone is better than that of the related art adopting the combination of two one-dimensional vector microphones.
In a possible implementation manner, when the first sound pickup structure and the second sound pickup structure are respectively disposed on two sides of the wafer in the thickness direction, the distance between the first sound pickup structure and the second sound pickup structure in the thickness direction of the wafer is greater than 0um and less than or equal to 500um.
When first pickup structure with second pickup structure sets up when the ascending homonymy of thickness direction of wafer, first pickup structure with second pickup structure is in the interval in the thickness direction of wafer is zero.
The distance between the first pickup structure and the second pickup structure in the thickness direction of the wafer influences the overall structural strength of the microphone, the thermal coupling between the two-dimensional pickup structures, the signal-to-noise ratio and other performances.
In one possible implementation mode, the first sound pickup structure comprises three thermal resistance lines, the three thermal resistance lines are divided into a heating line and two sensitive lines, and the two sensitive lines are respectively arranged on two sides of the heating line; the second sound pickup structure comprises three thermal resistance lines which are divided into a heating line and two sensitive lines, and the two sensitive lines are respectively arranged on two sides of the heating line.
The pickup structure of three-wire formula compares two wire systems, and sensitivity is more difficult impaired.
In one possible embodiment, the width of the sensitive wire is smaller than the width of the heating wire.
The width of the heating wire can be larger than that of the sensitive wire, so that the heating power of the heating wire is improved, and the detection sensitivity of the sensitive wire is improved.
In a possible implementation manner, the first sound pickup structure comprises a plurality of thermal resistance lines, and the thermal resistance lines are divided into a heating line and a plurality of sensitive lines which are respectively arranged at two sides of the heating line; the second pickup structure comprises a plurality of thermal resistance lines which are divided into a heating line and a plurality of sensitive lines which are respectively arranged at two sides of the heating line.
And a larger number of sensitive lines are arranged, so that the detection precision of the microphone is improved.
The embodiment of the application provides a two-dimensional vector microphone, one-dimensional vector pickup structure that is used for two directions pickups is processed respectively through the tow sides at the wafer, realizes integrated two-dimensional vector pickup structure on the single chip, and the SNR of arbitrary one dimension in the two-dimensional vector pickup structure is all higher than the SNR of solitary one-dimensional vector microphone, can effectively promote the SNR of device promptly, eliminates the influence each other of two orientation pickups. In addition, the two-dimensional vector microphone provided by the embodiment of the application can be better matched and packaged, so that the signal-to-noise ratio gain is larger; and the centers of the two-dimensional directivities are superposed, so that the consistency of the two-dimensional directivities is better, and the advantages of mature and simple processing technology, high process reliability and the like are achieved.
The embodiment of the present application further provides a two-dimensional vector microphone, including: the wafer, first pickup structure and second pickup structure set up the homonymy in the wafer thickness direction, and first pickup structure includes the first thermal resistance line of two at least relative settings, and first pickup structure is used for receiving the incident sound wave in the third direction, and second pickup structure includes the second thermal resistance line of two at least relative settings, and second pickup structure is used for receiving the incident sound wave in the fourth direction, third direction and fourth direction quadrature.
The two-dimensional vector microphone that this application embodiment provided, through the one-dimensional vector pickup structure that is used for two directions pickups of same face (openly or in the aspect) processing at the wafer, realize integrated two-dimensional vector pickup structure on the single chip, the SNR of arbitrary one dimension in the two-dimensional vector pickup structure, it is higher than the SNR of solitary one-dimensional vector microphone all, can effectively promote the SNR of device promptly, eliminate the influence each other of two orientation pickups.
In a possible embodiment, the wafer includes a supporting body, ends of the first sound pickup structure and the second sound pickup structure are fixed on the supporting body, a hollow area or a recess is formed inside the supporting body, the hollow area or the recess penetrates through a thickness direction of the wafer, and at least a part of lengths of the first sound pickup structure and the second sound pickup structure is disposed in the hollow area or the recess.
The arrangement of the hollow-out part and the concave part can provide space for sound wave vibration on one hand, and on the other hand, the heat dissipation caused by the fact that the thermal resistance line is tightly attached to the surface of the wafer can be avoided, namely, the heat is favorably localized in the air.
In a possible embodiment, the center of the first sound pick-up structure coincides with the center of the second sound pick-up structure.
The centers of directivity of the first sound pickup structure and the second sound pickup structure coincide, so that the directivity consistency of the two-dimensional vector microphone is better than that of the related art adopting the combination of two one-dimensional vector microphones.
In one possible embodiment, the method further comprises: the cross heating wire divides the surface of the wafer into a first quadrant, a second quadrant, a third quadrant and a fourth quadrant which are arranged anticlockwise, two target first thermal resistance wires in the two oppositely arranged first thermal resistance wires are respectively positioned in the first quadrant and the third quadrant, and two target second thermal resistance wires in the two oppositely arranged second thermal resistance wires are respectively positioned in the second quadrant and the fourth quadrant.
Can carry out even comprehensive heating through cross heater wire to first pickup structure and second pickup structure.
In one possible implementation mode, the first thermal resistance line and the second thermal resistance line are sensitive lines, and the width of the sensitive lines is smaller than or equal to the width of the cross heating line.
The width of the heating wire can be larger than that of the sensitive wire so as to improve the heating power of the heating wire and improve the detection sensitivity of the sensitive wire.
Drawings
Fig. 1 is a schematic structural diagram of a two-dimensional vector microphone according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of a first sound pickup structure according to an embodiment of the present application;
FIG. 3 is a schematic illustration of a static temperature field distribution of a first pickup configuration provided by an embodiment of the present application;
fig. 4 is a schematic diagram illustrating a dynamic temperature field distribution of a first sound pickup structure according to an embodiment of the present application;
fig. 5 is a schematic diagram of a hot-line structure of a two-dimensional vector microphone according to an embodiment of the present application;
fig. 5a is a schematic diagram of a hot-line structure of a two-dimensional vector microphone according to an embodiment of the present application;
fig. 6 is a schematic diagram of a package structure of a two-dimensional vector microphone according to an embodiment of the present application;
FIG. 7 is a corresponding exploded view of FIG. 6;
FIG. 8 is a graph illustrating a distribution of thermal fields in a YZ cross-section when only the first sound pickup structure is provided according to an embodiment of the present disclosure;
FIG. 9 is a graph of thermal field distribution across a YZ cross-section of a two-dimensional vector microphone provided by an embodiment of the present application;
fig. 10 is a schematic structural diagram of a two-dimensional vector microphone according to an embodiment of the present application;
fig. 11a is a schematic diagram of a hot-line distribution of a two-dimensional vector microphone according to an embodiment of the present application;
fig. 11b is a schematic diagram illustrating another hot-line distribution of a two-dimensional vector microphone according to an embodiment of the present application;
fig. 12 is a schematic structural diagram of a two-dimensional vector microphone according to an embodiment of the present application;
fig. 13 is a schematic diagram of a hot-line structure of a two-dimensional vector microphone according to an embodiment of the present application.
Description of reference numerals:
100-a wafer; 11-a support body; 12-a hollowed-out area; 13-a recess; 21-a first sound pick-up structure; 211 — a first thermal resistance line; 22-a second sound pick-up structure; 221-a second thermal resistance line; 20-thermal resistance line; 201-a heating wire; 202-sensitive line; 300-a circuit board; 41-a first package housing; 411-first sound guide hole; 42-a second package housing; 421-a second sound guide hole; 400-a third direction; 500-fourth orientation; 600-cross heating wire.
Detailed Description
Compared with an omnidirectional microphone, a microphone array and a traditional directional microphone, the sound vector microphone technology has the characteristics of good frequency and space consistency, strong noise suppression capability, good remote sound pickup effect and the like for sound signal collection, and is an important technical direction of the sound pickup technology of the intelligent terminal.
Current vector microphone research mainly includes paddle vector microphones, ciliated vector microphones, and hot-wire vector microphones. The former two modes are still in the research stage at present, and the seesaw type vector microphone has the problems of poor frequency response consistency and the like, and the ciliated vector microphone has the problems of large process difficulty, poor realizability and the like. The hot-wire vector microphone is already applied to industrial measurement and has the advantages of high signal-to-noise ratio, simplicity in processing and the like.
The hot-wire vector microphone can only realize one-dimensional detection generally, and can comprise at least two hot-resistance wires which are arranged in parallel and have a certain distance. The working principle of the hot wire type vector microphone is that when sound waves are incident on the thermal resistance wires, forced convection heat transfer is formed by reciprocating motion of medium particles (air, water and the like), heat of one thermal resistance wire is transferred to the other thermal resistance wire, the temperature of the thermal resistance wires is changed, the resistance values of the thermal resistance wires are changed, and vector information of the vibration speed of the medium particles can be obtained by detecting the change of the resistance values. The hot-wire vector microphone directly measures the particle vibration velocity of a medium sound field and has 8-shaped directivity independent of frequency.
However, the hot-wire vector microphone can only realize one-dimensional detection generally, and a mode for realizing a single-chip two-dimensional vector microphone in the related art is to combine two one-dimensional vector microphones, where the two one-dimensional vector microphones are respectively used to detect sound field information in two directions to realize two-dimensional detection. After two one-dimensional vector microphones are combined, two-dimensional sound pickup is realized by external assembly, the whole space of the microphones is doubled, the defects of poor consistency, complex assembly, large volume and the like are caused, the problem of structural crosstalk cannot be avoided between the two one-dimensional vector microphones, sound waves incident in one direction enter the vector microphones for detecting the other direction through scattering, so that signals which should not exist are generated, and the sensitivity and the directional characteristic of the sensors are influenced.
Based on the above problem, the embodiment of the application provides a two-dimensional vector microphone, through the one-dimensional vector pickup structure that is used for two directions pickups of processing respectively in the positive and negative both sides of wafer, perhaps, through the one-dimensional vector pickup structure that is used for two directions pickups of same face (positive or reverse) processing at the wafer, thereby realize the two-dimensional vector pickup structure of integration on the single chip, can effectively promote the SNR of device, eliminate the influence each other of two directions pickups, and possess advantages such as processing is simple and the uniformity height.
The two-dimensional vector microphone provided by the present application is described in detail below with reference to the drawings and specific embodiments.
Fig. 1 is a schematic structural diagram of a two-dimensional vector microphone according to an embodiment of the present disclosure. Referring to fig. 1, a two-dimensional vector microphone according to an embodiment of the present disclosure may include a wafer 100, a first sound pickup structure 21, and a second sound pickup structure 22, where the first sound pickup structure 21 and the second sound pickup structure 22 may be respectively disposed on two sides of the wafer 100 in a thickness direction. The first sound pickup structure 21 may extend along a first direction and the second sound pickup structure 22 may extend along a second direction, the first and second directions being orthogonal.
The thickness direction of the wafer 100 is the Z direction in the drawing, and the first direction and the second direction are the X direction and the Y direction, respectively.
The wafer 100 may be, for example, a silicon wafer, and the thickness of the silicon wafer is not particularly limited in this embodiment, and may be, for example, greater than 0um and less than or equal to 500um. The sound pickup direction of the first sound pickup structure 21 is the vibration velocity of the medium particles vertical to the first direction, namely the vibration velocity of the medium particles in the second direction (Y direction); the sound pickup direction of the second sound pickup structure 22 is the vibration velocity of the medium particles perpendicular to the second direction, i.e., the vibration velocity of the medium particles in the first direction (X direction).
The first sound pickup structure 21 may include at least two thermal resistance lines 20 arranged in parallel, the second sound pickup structure 22 may include at least two thermal resistance lines 20 arranged in parallel, the thermal resistance lines 20 of the first sound pickup structure 21 are arranged in parallel and have a certain distance, and the thermal resistance lines 20 of the second sound pickup structure 22 are arranged in parallel and have a certain distance.
Fig. 2 is a schematic structural diagram of a first sound pickup structure according to an embodiment of the present application. Referring to fig. 2, in a possible embodiment, the first sound pickup structure 21 may include three thermal resistance lines 20, the three thermal resistance lines 20 are arranged in parallel and have a certain distance, a middle thermal resistance line 20 is used as a heating line 201, two thermal resistance lines 20 are respectively arranged on the left and right sides of the heating line 201 and are used as sensing lines 202, the heating line 201 is used for self-heating, and the sensing lines 202 are used for detecting temperature changes. The arrows in fig. 2 point to the incident direction of the acoustic wave, which is perpendicular to the extending direction of the thermal resistance line 20, and after the acoustic wave is incident, the reciprocating motion of the medium particles forms forced convection heat transfer, which causes the temperature of the two sensitive lines 202 to change.
Fig. 3 is a schematic diagram of a static temperature field distribution of a first pickup structure according to an embodiment of the present application, where an abscissa represents a position coordinate of the first pickup structure in a second direction, and an ordinate represents a temperature. Referring to fig. 3, in the second direction, the overall trend of the temperature is first increasing and then decreasing, with the temperature being highest at the heater wire 201. Since the heat transfer efficiency between the heating wire 201 and the sensing wire 202 is higher than that between the heating wire 201 and the air, the temperature has two higher peaks at the two sensing wires 202, which are lower than the peak of the temperature at the heating wire 201.
After the sound wave is incident, the reciprocating motion of the medium particles forms forced convection heat transfer, the heat of one sensitive line 202 is transferred to the other sensitive line 202, the temperature of the two sensitive lines 202 is changed oppositely, the resistance value of each sensitive line is changed, and the vibration velocity vector information of the medium particles can be obtained by detecting the change of the resistance value. Fig. 4 is a schematic diagram of a dynamic temperature field distribution of a first sound pickup structure according to an embodiment of the present application. Referring to fig. 4, when the sound wave is incident in the direction of the solid arrow in the figure, the temperature of the sensitive line 202 near the incident direction of the sound wave decreases, and the temperature of the sensitive line 202 far from the incident direction of the sound wave increases.
Assuming that the sound wave is a direct current signal, i.e. the frequency f =0, the temperature change Δ T (0) of the sensitive line 202 can be calculated by using the following formula:
where i represents an imaginary number, f represents frequency, v represents particle vibration velocity, P represents power applied to the heater wire 201, k represents thermal conductivity of the medium, ly represents length of the thermal resistance line, D represents thermal diffusivity of the medium, a represents a distance between the sensitive line 202 and the heater wire 201, and γ represents euler constant (0.577).
When the frequency of the acoustic wave is not 0, the temperature change Δ T (f) of the sensitive line 202 can be calculated by the following formula:
wherein, deltaT (0) is calculated by a formula I, f d Refers to the coefficient of influence of air on heat transfer, f hc Refers to the coefficient of influence of the material of the thermal resistance wire itself (e.g., heat capacity, wire length, etc.) on the thermal conduction. f. of d And f hc The following formula can be used for calculation:
wherein k is air The heat conductivity coefficient of air is represented, L represents the line length of a heat resistance line, h represents the thickness of the heat resistance line, rho represents density, cp represents constant pressure specific heat capacity, air represents air, and sensor represents the heat resistance line.
The above-mentioned sound pickup structure can be connected in the sound pickup detection circuit, and the temperature change Δ T (f) of the sensitive wire 202 will cause the resistance change of the sensitive wire 202, thereby bringing about the change of the output voltage in the sound pickup detection circuit. By detecting the change of the output voltage, the vibration velocity vector information of the medium mass points can be obtained, so that the information such as the incident direction, the frequency and the like of sound waves can be judged, and sound pickup is realized.
Fig. 5 is a schematic diagram of a hot-line structure of a two-dimensional vector microphone according to an embodiment of the present application. Referring to fig. 1 and 5, the first sound pickup structure 21 and the second sound pickup structure 22 are respectively disposed on two planes (XY planes) parallel to each other, an extending direction of the first sound pickup structure 21 is orthogonal to an extending direction of the second sound pickup structure 22, and a center of the first sound pickup structure 21 and a center of the second sound pickup structure 22 coincide in a thickness direction of the wafer 100, that is, the first sound pickup structure 21 and the second sound pickup structure 22 are aligned in a center in a Z direction. The centers of the directivity of the first sound pickup structure 21 and the second sound pickup structure 22 coincide, and therefore the directivity consistency of the two-dimensional vector microphone is better than that of the related art in which two one-dimensional vector microphones are combined.
The first sound pickup structure 21 and the second sound pickup structure 22 have a distance in the thickness direction of the wafer 100, and the distance may be in a range greater than 0um and less than or equal to 500um. In a possible embodiment the first sound pick-up structure 21 and the second sound pick-up structure 22 are spaced between 50-200 um.
Not only here, fig. 5a is a schematic diagram of a hot-wire structure of a two-dimensional vector microphone according to an embodiment of the present disclosure, and referring to fig. 5a, in the two-dimensional vector microphone according to the embodiment of the present disclosure, the first sound collecting structure 21 and the second sound collecting structure 22 may also be disposed on the same side in the thickness direction of the wafer 100, for example, the front side of the wafer 100 or the back side of the wafer 100, and at this time, a distance between the first sound collecting structure 21 and the second sound collecting structure 22 in the thickness direction of the wafer 100 is zero. The extending direction of the first sound pickup structure 21 is orthogonal to the extending direction of the second sound pickup structure 22, and the center of the first sound pickup structure 21 coincides with the center of the second sound pickup structure 22. Illustratively, as shown in fig. 5a, the first sound pickup structure 21 includes a heating wire 201 and two sensing wires 202 located at two sides of the heating wire 201, the second sound pickup structure 22 includes a heating wire 201 and two sensing wires 202 located at two sides of the heating wire 201, after the first sound pickup structure 21 and the second sound pickup structure 22 are orthogonal, the heating wire 201 of the first sound pickup structure 21 and the heating wire 201 of the second sound pickup structure 22 are in a cross shape for self-heating ambient air, and the orthogonal sensing wires 202 located at four quadrants of the cross-shaped heating wire 201 are used for detecting temperature. It should be noted that an insulating member is required to be disposed at a contact position between the sensing wire 202 and the heating wire 201 to prevent direct heat conduction between the sensing wire 202 and the heating wire 201. At this time, the sound pickup directions of the first sound pickup structure 21 and the second sound pickup structure 22 after being orthogonal are indicated by hollow arrows in fig. 5a, and can be understood as a 45 degree direction and a 135 degree direction with the cross-shaped heating wire as a coordinate axis. The centers of directivity of the first sound pickup structure 21 and the second sound pickup structure 22 coincide, and therefore, the directivity consistency of the two-dimensional vector microphone is better than that of the related art in which two one-dimensional vector microphones are combined.
The embodiment of the application provides a two-dimensional vector microphone sets up first pickup structure and second pickup structure respectively through the tow sides at a wafer, perhaps sets up first pickup structure and second pickup structure at the same face of a wafer, is used for realizing the pickup in two directions respectively to the two-dimensional vector pickup of single-chip has been realized, compared in the correlation technique that adopts two one-dimensional vector microphones to combine, the volume that two-dimensional vector microphone occupy is littleer.
In addition, two dimension vector microphone structures that this application embodiment provided, two pickup structures can set up respectively at the tow sides of wafer, are favorable to two pickup structures independent encapsulation respectively to can avoid taking place to crosstalk between two pickup structures. The following provides a package structure of a two-bit vector microphone structure according to an embodiment of the present application with reference to specific drawings.
Fig. 6 is a schematic view of a package structure of a two-dimensional vector microphone according to an embodiment of the present application, and fig. 7 is an exploded schematic view corresponding to fig. 6. Referring to fig. 6 and 7, the two-dimensional vector microphone provided by the embodiment of the present application may further include a circuit board 300, a first package case 41, and a second package case 42.
The circuit board 300 may be provided with an opening, the wafer 100 may be embedded in the opening, and the first sound pickup structure 21 and the second sound pickup structure 22 on the front and back sides of the wafer 100 are respectively exposed on the two sides of the circuit board 300. The first packaging case 41 and the second packaging case 42 may be respectively disposed on two sides of the circuit board 300, the first packaging case 41 may be covered outside the first sound pickup structure 21, and the second packaging case 42 may be covered outside the second sound pickup structure 22.
The first enclosure 41 is provided with a first sound guiding hole 411, the first sound guiding hole 411 is communicated with two opposite side surfaces of the first enclosure 41, the second enclosure 42 is provided with a second sound guiding hole 421, and the second sound guiding hole 421 is communicated with two opposite side surfaces of the second enclosure 42. After the first and second package cases 41 and 42 are assembled, the extending direction of the first sound guide hole 411 is the second direction, and the extending direction of the second sound guide hole 421 is the first direction.
The first package housing 41 may be made of resin or the like through an integral molding process, the second package housing 42 may also be made of resin or the like through an integral molding process, the first package housing 41 and the second package housing 42 may have the same structure, and the package structure may be implemented only by ensuring that the first sound guide hole 411 and the second sound guide hole 421 are oriented differently during assembly, so as to reduce the production cost.
First leading sound hole 411 and second leading sound hole 421's structure is the same, and first leading sound hole 411 is whole to regard as two tubaeform through-holes that set up dorsad and to communicate the back formation, and the cross-section of the trompil of first leading sound hole 411 reduces from the casing outside to inside gradually to realize the effect of good collection sound.
The two-dimensional vector microphone provided in the embodiment of the present application may be assembled in a process that, first, the first sound pickup structure 21 and the second sound pickup structure 22 are fabricated on the front and back surfaces of the wafer 100; then, the wafer 100 is connected in the circuit board 300, so that the first sound pickup structure 21 and the second sound pickup structure 22 are respectively exposed at two sides of the circuit board 300; the first packaging shell 41 and the second packaging shell 42 are respectively covered outside the first sound pickup structure 21 and the second sound pickup structure 22, so that the extending direction of the first sound guiding hole 411 is perpendicular to the extending direction of the first sound pickup structure 21, and the extending direction of the second sound guiding hole 421 is perpendicular to the extending direction of the second sound pickup structure 22; finally, the first and second package cases 41 and 42 are fixed by bonding or the like.
In one aspect, the first package body 41 and the second package body 42 may 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 side and the back side of the wafer 100, the first sound collecting structure 21 can detect the sound waves incident from the second direction through the first sound guiding hole 411, the second sound collecting structure 22 can detect the sound waves incident from the first direction through the second sound guiding hole 421, and the sound waves at the two sides do not cross each other, so that the sensitivity of the two-dimensional vector microphone can be improved.
According to the two-dimensional vector microphone provided by the embodiment of the application, the two pickup structures are respectively arranged on the front side and the back side of the wafer, so that the two pickup structures can be better matched and packaged, and the signal-to-noise ratio is higher under the condition of small-size packaging. Illustratively, a sensitivity increase of about 12dB can be achieved with an overall size of the package structure of 1 inch.
In one possible embodiment, with continued reference to fig. 1, the wafer 100 may include a supporting body 11, ends of the first sound-collecting structure 21 and the second sound-collecting structure 22 are fixed on the supporting body 11, a hollow area 12 is opened on an inner side of the supporting body 11, and at least a part of lengths of the first sound-collecting structure 21 and the second sound-collecting structure 22 are disposed to face the hollow area 12. The hollowed-out area 12 can be formed by laser processing.
In the embodiment shown in fig. 1, the inside of the wafer 100 is hollowed out, and the hollowed-out area brings a particle vibration velocity along the thickness direction of the wafer 100, that is, a plane in which the particle motion direction is perpendicular to the first direction and the second direction, and the particle vibration velocity is not detected by the first sound collecting structure 21 and the second sound collecting structure 22, so that the directional characteristic of the two-dimensional vector microphone is not affected.
The supporting body 11 may be set as a rectangular frame structure, the two ends of the first sound pickup structure 21 may be connected to two opposite frames of the rectangular frame structure, and are disposed at the middle points of the frames, and the two ends of the second sound pickup structure 22 may be connected to two other opposite frames of the rectangular frame structure, and are disposed at the middle points of the frames. With this arrangement, it is ensured that the first sound collecting structure 21 and the second sound collecting structure 22 are orthogonal and the centers thereof coincide with each other in the thickness direction of the wafer 100.
The hollow area 12 may also be rectangular, and the arrangement of the hollow area 12 can reduce the overall weight of the wafer 100, and on the other hand, air exists instead of the wafer material between the thermal resistance line of the first sound pickup structure 21 and the thermal resistance line of the second sound pickup structure 22, thereby facilitating the thermal coupling between the first sound pickup structure 21 and the second sound pickup structure 22, and improving the detection sensitivity. The principle of thermal coupling of the first sound pick-up structure 21 and the second sound pick-up structure 22 is explained below with reference to a thermal field profile.
Fig. 8 is a graph of distribution of thermal fields in a YZ cross-section when only the first sound pickup structure is disposed according to an embodiment of the present application, where in fig. 8, an abscissa represents a position in the second direction and an ordinate represents a temperature. Referring to fig. 8, in the second direction, the overall trend of the temperature is first increasing and then decreasing, the temperature is highest at the heating line 201, and the slope of the curve is the largest at the heating line 201.
Fig. 9 is a graph of thermal field distribution in YZ cross section of a two-dimensional vector microphone provided by an embodiment of the present application, wherein the lower curve is the curve in fig. 8 for comparison. Referring to fig. 9, since the first sound pickup structure 21 and the second sound pickup structure 22 are thermally coupled, that is, temperatures in two dimensions can be mutually superposed, the temperature at the sensitive line 202 is higher, and the temperature fluctuation range is larger after sound waves are incident, so that the resistance value change is more obvious, and the signal-to-noise ratio of any dimension in the two-dimensional vector microphone is higher than that of a single one-dimensional vector microphone.
In a specific example, the length of the thermal resistance lines 20 of the first sound pickup structure 21 and the second sound pickup structure 22 is 1mm, the distance between two adjacent thermal resistance lines 20 is 60um, the line width of the thermal resistance line 20 is 2um, and the thickness of the thermal resistance line 20 is 0.3um. When the distance between the first sound pickup structure 21 and the second sound pickup structure 22 in the thickness direction of the wafer 100 is 300um, there is a thermally coupled two-dimensional vector microphone, and a sensitivity improvement of 1.2dB can be achieved compared to a one-dimensional vector microphone. When the distance between the first sound pickup structure 21 and the second sound pickup structure 22 in the thickness direction of the wafer 100 is 100um, there is a thermally coupled two-dimensional vector microphone, and a 3dB sensitivity improvement can be achieved compared to a one-dimensional vector microphone.
Fig. 10 is a schematic structural diagram of a two-dimensional vector microphone according to an embodiment of the present application. Referring to fig. 10, in another possible implementation, the wafer 100 includes a supporting body 11, ends of the first sound pickup structure 21 and the second sound pickup structure 22 are fixed on the supporting body 11, two sides of the supporting body 11 in the thickness direction are respectively provided with a recess 13, and at least part of the length of the first sound pickup structure 21 and the second sound pickup structure 22 is arranged facing the recess 13.
Similarly, compared to the embodiment provided in fig. 1, in this embodiment, the supporting body 11 may be configured as a rectangular frame structure, two ends of the first sound collecting structure 21 may be respectively connected to two opposite frames of the rectangular frame and are disposed at the middle point of the frames, and two ends of the second sound collecting structure 22 may be respectively connected to two other opposite frames of the rectangular frame and are disposed at the end points of the frames. With this arrangement, it is ensured that the first sound collecting structure 21 and the second sound collecting structure 22 are orthogonal and the centers thereof coincide with each other in the thickness direction of the wafer 100.
The concave portion 13 may also be rectangular, the concave portion 13 may be formed by a downward depression of the surface of the wafer 100 by a certain depth, and the arrangement of the concave portion 13 may provide a space for the sound wave vibration on the one hand, and may prevent the thermal resistance wire 20 from being attached to the surface of the wafer 100 to cause heat dissipation on the other hand, that is, it is beneficial for the heat generated by the thermal resistance wire 20 to be localized in the air.
The two-dimensional vector microphone provided by the embodiment of the present application is also applicable to the package structures provided in fig. 6 and 7, and since there is no hollow inside the wafer 100, there is no particle vibration velocity along the thickness direction of the wafer 100, and thus there is no influence on the directional characteristics of the two-dimensional vector microphone.
In the above embodiment of the present application, the thermal resistance wire 20 may be a metal wire, and may be made of doped silicon, a metal material (platinum Pt, nickel Ni, ti, al, etc.), or a multi-layer composite material (W/Ti/Pt, al/Si, etc.). In the embodiment provided in fig. 1 and 10, the sound pickup structure is a three-wire structure, that is, the sound pickup structure includes a heating wire 201 and a sensing wire 202 disposed on two sides of the heating wire 201, and widths of the heating wire 201 and the sensing wire 202 may be the same, or a width of the heating wire 201 may be greater than a width of the sensing wire 202, it is understood that the heating wire 201 has a wider width, which may ensure a heating power of the heating wire 201, and the sensing wire 202 has a narrower width, which may improve a temperature change rate, thereby improving a detection sensitivity.
In other possible embodiments, the sound pickup structure may also be a two-wire structure or a multiple-wire structure. Fig. 11a is a schematic diagram of a distribution of hot lines of a two-dimensional vector microphone according to an embodiment of the present application. Referring to fig. 11a, the sound pickup structure may be a two-wire structure, that is, the sound pickup structure includes two thermal resistance wires 20 arranged in parallel and having a certain distance, and the two thermal resistance wires 20 may be used as a heating wire and a sensing wire at the same time. Fig. 11b is a schematic diagram of another hot line distribution of a two-dimensional vector microphone according to an embodiment of the present application. Referring to fig. 11b, the sound pickup structure may be a multi-wire structure, one heating wire 201 is located in the middle, and a plurality of sensitive wires 202 are respectively disposed on two sides of the heating wire 201 to improve the detection accuracy.
The embodiment of the application provides a two-dimensional vector microphone, one-dimensional vector pickup structure that is used for two directions pickups is processed respectively through the positive and negative both sides at the wafer, perhaps, one-dimensional vector pickup structure that is used for two directions pickups is processed through same face (positive or reverse side) at the wafer, realize integrated two-dimensional vector pickup structure on the single chip, the SNR of arbitrary one dimension in the two-dimensional vector pickup structure, it is higher than the SNR of solitary one-dimensional vector microphone all, can effectively promote the SNR of device promptly, eliminate the influence each other of two orientation pickups. In addition, the two-dimensional vector microphone provided by the embodiment of the application can be better matched and packaged, so that the signal-to-noise ratio gain is larger; and the centers of the two-dimensional directivities are overlapped, the consistency of the two-dimensional directivities is better, and the method has the advantages of mature and simple processing technology, high process reliability and the like.
Fig. 12 is a schematic structural diagram of a two-dimensional vector microphone provided in an embodiment of the present application, and referring to fig. 12, the two-dimensional vector microphone provided in the embodiment of the present application includes: wafer 100, first sound pick-up structure 21 and second sound pick-up structure 22 set up the homonymy on the wafer thickness direction.
The first sound pickup structure 21 includes at least two first heat resistance lines 211 arranged oppositely, the first sound pickup structure 21 is used for receiving incident sound waves in a third direction, the second sound pickup structure 22 includes at least two second heat resistance lines 221 arranged oppositely, and the second sound pickup structure 22 is used for receiving incident sound waves in a fourth direction, wherein the third direction is orthogonal to the fourth direction.
It is understood that fig. 12 can be regarded as a modification of fig. 5a, namely, the sensitive wires 202 in the four quadrants of the cross-shaped heating wire 201 in fig. 5a intersect and are connected into a right-angled whole, in which case, two sensitive wires 202 in the first quadrant are connected and electrically conducted, and the second, third and fourth quadrants are also the same. The two-dimensional vector microphone shown in fig. 12 can facilitate Micro-Electro-Mechanical System (MEMS) processing compared to fig. 5 a.
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 the right-angle shape shown in fig. 12, for example, the first thermal resistance line 211 and the second thermal resistance line 221 may be chamfered at a right angle, or the first thermal resistance line 211 and the second thermal resistance line 221 are directly arranged in an arc shape, only the first sound pickup structure 21 needs to be ensured to receive the incident sound wave in the third direction, the second sound pickup structure 22 needs to be ensured to receive the incident sound wave in the fourth direction, and the third direction is ensured to be orthogonal to the fourth direction, where the shapes of the first thermal resistance line 211 and the second thermal resistance line 221 are not limited.
Similar to the structure of the crystal 100 in fig. 1 and 10, the wafer 100 in fig. 12 may include a supporting body, ends of the first sound pickup structure 21 and the second sound pickup structure 22 are fixed on the supporting body, a hollow area or a recess is formed inside the supporting body, the hollow area or the recess penetrates through a thickness direction of the wafer, and at least a part of lengths of the first sound pickup structure 21 and the second sound pickup structure 22 is disposed in the hollow area or the recess, so as to provide a space for sound wave vibration, and on the other hand, prevent the first thermal resistance line 211 and the second thermal resistance line 221 from clinging to the surface of the wafer 100 to cause heat dissipation, that is, facilitate the heat to be localized in the air. With continued reference to fig. 12, to enhance directional consistency of the two-dimensional vector microphones, the center of the first sound pickup structure 21 and the center of the second sound pickup structure 22 may be arranged to coincide.
Fig. 13 is a schematic diagram of a hot wire structure of a two-dimensional vector microphone according to an embodiment of the present disclosure, referring to fig. 13, based on fig. 12, the two-dimensional vector microphone further includes a cross heating wire 600, the cross heating wire 600 divides the surface of the wafer 100 into a first quadrant, a second quadrant, a third quadrant, and a fourth quadrant that are arranged counterclockwise, two target first thermal resistance wires 211 of the two oppositely disposed first thermal resistance wires 211 are respectively located in the first quadrant and the third quadrant, two target second thermal resistance wires 221 of the two oppositely disposed second thermal resistance wires 221 are respectively located in the second quadrant and the fourth quadrant, and the cross heating wire 600 can comprehensively and uniformly heat the first thermal resistance wires 211 and the second thermal resistance wires 221.
In some embodiments of the present application, the first thermal resistance line 211 and the second thermal resistance line 221 are sensitive lines, and the widths of the first thermal resistance line 211 and the second thermal resistance line 221 are smaller than the width of the cross heating line 600, so that the heating power of the cross heating line 600 can be increased, and the detection sensitivity of the first thermal resistance line 211 and the second thermal resistance line 221 can be improved.
The two-dimensional vector microphone that this application embodiment provided, through the one-dimensional vector pickup structure that is used for two directions pickups of same face (openly or in the aspect) processing at the wafer, realize integrated two-dimensional vector pickup structure on the single chip, the SNR of arbitrary one dimension in the two-dimensional vector pickup structure, it is higher than the SNR of solitary one-dimensional vector microphone all, can effectively promote the SNR of device promptly, eliminate the influence each other of two orientation pickups.
Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the embodiments of the present application, and are not limited thereto; although the embodiments of the present application have been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.
Claims (15)
1. A two-dimensional vector microphone, comprising: the device comprises a wafer, a first pickup structure and a second pickup structure;
the first sound pickup structure and the second sound pickup structure are respectively arranged on two sides of the wafer in the thickness direction, or the first sound pickup structure and the second sound pickup structure are arranged on the same side of the wafer in the thickness direction;
first pickup structure extends along first direction, second pickup structure extends along the second direction, first direction with the second direction quadrature, first pickup structure includes two at least parallel arrangement's thermal resistance line, second pickup structure includes two at least parallel arrangement's thermal resistance line.
2. The two-dimensional vector microphone of claim 1, wherein the wafer includes a supporting body, ends of the first and second sound pickup structures are fixed to the supporting body, a hollow area is formed inside the supporting body, the hollow area penetrates through a thickness direction of the wafer, and at least a part of lengths of the first and second sound pickup structures face the hollow area.
3. The two-dimensional vector microphone of claim 1, wherein the wafer comprises a support body, ends of the first sound pickup structure and the second sound pickup structure are fixed on the support body, two sides of the support body in the thickness direction are respectively provided with a recess, and at least part of the length of the first sound pickup structure and the second sound pickup structure is arranged to face the recess.
4. The two-dimensional vector microphone according to claim 2 or 3, wherein when the first sound pickup structure and the second sound pickup structure are respectively disposed on both sides in a thickness direction of the wafer, the two-dimensional vector microphone further includes a circuit board, a first package case, and a second package case; an opening is formed in the circuit board, the wafer is embedded into the opening, and the first sound pickup structure and the second sound pickup structure are exposed on two sides of the circuit board respectively;
be provided with first leading hole on the first encapsulation casing, first leading hole intercommunication two relative sides of first encapsulation casing, the second leading hole has been seted up on the second encapsulation casing, second leading hole intercommunication two relative sides of second encapsulation casing, first encapsulation casing with second encapsulation casing sets up respectively the both sides of circuit board, first leading hole along the second direction extends, second leading hole along the first direction extends, first pickup structure is located the center in first leading hole, second pickup structure is located the center in second leading hole.
5. A two-dimensional vector microphone according to claim 4, wherein the first and second encapsulating shells are identical in structure, and wherein the first and second encapsulating shells are fixedly connected.
6. A two-dimensional vector microphone according to any of claims 1-5, wherein a center of the first pickup structure and a center of the second pickup structure coincide in a thickness direction of the wafer.
7. The two-dimensional vector microphone of claim 6, wherein when the first sound pickup structure and the second sound pickup structure are respectively disposed on two sides of the wafer in the thickness direction, a distance between the first sound pickup structure and the second sound pickup structure in the thickness direction of the wafer is greater than 0um and less than or equal to 500 um;
when first pickup structure with second pickup structure sets up when the ascending homonymy of thickness direction of wafer, first pickup structure with second pickup structure is in the interval in the thickness direction of wafer is zero.
8. The two-dimensional vector microphone according to any one of claims 1 to 7, wherein the first pickup structure comprises three thermal resistance lines, the three thermal resistance lines are divided into a heating line and two sensing lines, and the two sensing lines are respectively disposed on two sides of the heating line; the second pickup structure comprises three thermal resistance lines which are divided into a heating line and two sensitive lines, and the two sensitive lines are respectively arranged on two sides of the heating line.
9. The two-dimensional vector microphone of claim 8, wherein the width of the sensitive line is less than or equal to the width of the heater line.
10. The two-dimensional vector microphone according to any one of claims 1 to 7, wherein the first pickup structure includes a plurality of thermal resistance lines, and the plurality of thermal resistance lines are divided into a heating line and a plurality of sensitive lines respectively disposed on both sides of the heating line; the second pickup structure comprises a plurality of thermal resistance lines, and the thermal resistance lines are divided into a heating line and a plurality of sensitive lines which are respectively arranged on two sides of the heating line.
11. A two-dimensional vector microphone, comprising: the device comprises a wafer, a first sound pickup structure and a second sound pickup structure;
the first sound pickup structure and the second sound pickup structure are arranged on the same side of the wafer in the thickness direction;
the first pickup structure comprises at least two first thermal resistance lines which are oppositely arranged, the first pickup structure is used for receiving incident sound waves in a third direction, the second pickup structure comprises at least two second thermal resistance lines which are oppositely arranged, the second pickup structure is used for receiving the incident sound waves in a fourth direction, and the third direction is orthogonal to the fourth direction.
12. The two-dimensional vector microphone of claim 11, wherein the wafer comprises a supporting body, ends of the first sound pickup structure and the second sound pickup structure are fixed on the supporting body, a hollow area or a recess is formed inside the supporting body, the hollow area or the recess penetrates through a thickness direction of the wafer, and at least a part of lengths of the first sound pickup structure and the second sound pickup structure are disposed in the hollow area or the recess.
13. A two-dimensional vector microphone according to any of claims 11-12, wherein the center of the first pickup structure coincides with the center of the second pickup structure.
14. A two-dimensional vector microphone according to any of claims 11-13, further comprising: a cross heater wire;
the cross heating wire divides the surface of the wafer into a first quadrant, a second quadrant, a third quadrant and a fourth quadrant which are arranged anticlockwise;
two target first thermal resistance lines of the two oppositely arranged first thermal resistance lines are respectively positioned in the first quadrant and the third quadrant, and two target second thermal resistance lines of the two oppositely arranged second thermal resistance lines are respectively positioned in the second quadrant and the fourth quadrant.
15. The two-dimensional vector microphone according to claim 14, wherein the first thermal resistance line and the second thermal resistance line are both sensitive lines, and the width of the sensitive lines is equal to or less than the width of the cross heating line.
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| CN2021106477156 | 2021-06-10 | ||
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| JP2009250928A (en) * | 2008-04-10 | 2009-10-29 | Nippon Hoso Kyokai <Nhk> | Mems type thermal beam type particle velocity detection element, its manufacturing method, and acoustic sensor |
| CN107917750B (en) * | 2016-10-08 | 2020-06-26 | 北京大学 | MEMS (micro-electromechanical system) thermal type acoustic particle sensor |
| CN109916499A (en) * | 2019-03-20 | 2019-06-21 | 曲阜师范大学 | A kind of two dimensional optical fiber vector microphone that " 8 " word directive property is orthogonal probe |
| CN111220257B (en) * | 2020-01-16 | 2022-04-08 | 江苏物联网研究发展中心 | Acoustic particle velocity reactor and manufacturing method thereof |
| CN111829646B (en) * | 2020-07-27 | 2022-06-28 | 中国电子科技集团公司第三研究所 | Particle vibration velocity sensor with wide response frequency band |
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