CN114501266B - Single-fulcrum differential structure anti-vibration interference chip and microphone with same - Google Patents
Single-fulcrum differential structure anti-vibration interference chip and microphone with same Download PDFInfo
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- CN114501266B CN114501266B CN202210064159.4A CN202210064159A CN114501266B CN 114501266 B CN114501266 B CN 114501266B CN 202210064159 A CN202210064159 A CN 202210064159A CN 114501266 B CN114501266 B CN 114501266B
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 21
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R19/00—Electrostatic transducers
- H04R19/005—Electrostatic transducers using semiconductor materials
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R19/00—Electrostatic transducers
- H04R19/04—Microphones
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
- H04R2201/003—Mems transducers or their use
Abstract
The invention discloses a single-pivot differential structure anti-vibration interference chip and a microphone with the same, wherein the chip sequentially comprises an upper cover plate, an acoustic sensitive structure layer, a cavity structure layer and a substrate from top to bottom; the acoustic sensitive structure layer comprises two acoustic sensitive elements which are symmetrically distributed on two sides of the supporting element, and damping holes are formed in the two acoustic sensitive elements; the cavity structure layer comprises two lower electrodes which are distributed at intervals, the two lower electrodes are in one-to-one correspondence with the two acoustic sensitive elements and are oppositely arranged to form two capacitors, and the two acoustic sensitive elements are simultaneously used as upper electrodes of the two capacitors respectively; the upper cover plate is hollowed out corresponding to the position of one acoustic sensor to form an acoustic transmission hole, and the position corresponding to the other acoustic sensor is implemented as an acoustic barrier. The deformation of the two acoustic sensitive elements is identical under the action of vibration interference, so that the capacitance variation of the two capacitors is identical, and after differential output, the output signal is zero, thereby realizing the purpose of vibration interference resistance.
Description
Technical Field
The invention relates to the technical field of micro-electromechanical technology, in particular to a single-pivot differential structure vibration interference resistant chip and a microphone with the same.
Background
Acoustic propagation theory shows that the lower the frequency of the acoustic wave, the less attenuation in the atmosphere and the farther the propagation distance. Thus, to detect a distant target, the frequency at which the acoustic microphone detector detects the target sound wave is typically below kHz.
The current commercial MEMS (Micro-Electro-Mechanical System) microphone is mainly designed for human voice signals, the working frequency band is 20 Hz-20000 Hz, and the existing commercial microphone is used as a detection device, so that the problems of high-frequency band resource waste and low-frequency resource shortage exist. On the other hand, the working bandwidth and the sensitivity of the sensor are two performances which are mutually restricted, and the sensitivity of the microphone is low due to the overlarge working bandwidth, so that the existing commercial MEMS microphone cannot meet the requirement of remote acoustic detection. In addition, during detection, the microphone is often installed on a platform such as a vehicle and an unmanned aerial vehicle and used outdoors, the faced environment is complex and changeable, the low-frequency vibration interference can be inevitably caused, the conventional commercial microphone does not have the anti-vibration interference capability, and the acoustic performance of the microphone can be seriously affected. For atmospheric detection, the acoustic signal of a distant target is very weak, and the electrical signal generated by the low-frequency vibration interference signal of the surrounding environment of the detector may be larger than the electrical signal generated by the sound wave, so that the acoustic signal of the distant target is difficult to detect, and particularly when the frequency of the low-frequency vibration interference signal is close to or equal to the frequency of the acoustic signal of the detected target, the signal generated by the vibration interference signal is difficult to separate from the signal generated by the target sound wave.
The Chinese published application patent (application No. 202110893662.6) discloses that at least two air release valves which are uniformly distributed are arranged on a diaphragm of the MEMS microphone chip, the air release valves comprise movable parts and pores, the pores have a stepped section, and the number of steps of the stepped section is one or more.
The Chinese published application patent No. 202110867544.8 discloses an MEMS microphone chip with a dustproof structure and a manufacturing method thereof, wherein the MEMS microphone chip comprises a substrate and a back cavity penetrating along the upper and lower directions, a capacitor is formed by a vibrating diaphragm, a back plate and a vibrating gap between the vibrating diaphragm and the back plate on the same side of the substrate, an air release valve is arranged on the vibrating diaphragm, and the periphery of the air release valve is provided with the dustproof structure.
The Chinese published application patent microphone and the manufacturing method thereof, application number 202110767002.3 discloses a microphone which comprises a substrate of a cavity, a vibrating diaphragm above the substrate, a backboard arranged at intervals with the vibrating diaphragm, backboard electrodes and extraction electrodes. The vibrating diaphragm is provided with a plurality of silicon oxide layers, and the projection of the extraction electrode on the vibrating diaphragm is at least partially overlapped with the plurality of silicon oxide layers.
The Chinese published application patent No. 202110728000.3 discloses a MEMS microphone, which comprises a packaging structure formed by a shell and a substrate, wherein an MEMS chip is arranged in the packaging structure, the MEMS chip comprises a substrate, a vibrating diaphragm and a back electrode, the vibrating diaphragm is arranged on the substrate, the substrate comprises a connecting column and a central column positioned in the connecting column, the connecting column and the central column form a back hole on the substrate, and a through hole is arranged on the vibrating diaphragm positioned above the central column; and a limiting part for limiting the upward movement of the vibrating diaphragm is arranged on the back, the central column is used for limiting the upward movement range of the vibrating diaphragm, and the limiting part and the central column are used for limiting the displacement of the vibrating diaphragm under the action of external sound pressure.
To sum up, the existing microphone is generally characterized in that the periphery of a single diaphragm structure is fixedly supported on a cavity, the diaphragm can deform under the action of inertia force to output voltage signals, and the acoustic performance of the microphone can be affected by vibration interference. The working frequency of the microphone with the structure can reach 20000Hz, and the application requirement of atmospheric detection on low-frequency sound wave signals can not be met.
Disclosure of Invention
Aiming at the technical problems, the invention aims to provide a single-pivot differential structure anti-vibration interference chip and a microphone with the chip, so as to realize the purpose of anti-vibration interference.
The technical scheme of the invention is as follows:
one of the purposes of the invention is to provide a single-fulcrum differential structure anti-vibration interference chip, which comprises an upper cover plate, an acoustic sensitive structure layer, a cavity structure layer and a substrate from top to bottom in sequence; wherein,
the acoustic sensing structure layer comprises two acoustic sensing elements symmetrically distributed on two sides of the supporting element, damping holes are formed in the two acoustic sensing elements, and a metal bonding pad is further arranged on the acoustic sensing structure layer;
the cavity structure layer comprises two lower electrodes which are distributed at intervals, the two lower electrodes are in one-to-one correspondence with the two acoustic sensitive elements and are oppositely arranged to form two capacitors, and the two acoustic sensitive elements are simultaneously used as upper electrodes of the two capacitors respectively;
the upper cover plate is hollowed out corresponding to the position of one acoustic sensing element to form an acoustic transmission hole, and the position corresponding to the other acoustic sensing element is implemented as an acoustic barrier part;
the substrate is composed of an oxide layer and a silicon layer which are stacked up and down.
Preferably, the opposite ends of the two acoustic sensitive elements are rigidly connected by two connecting beams symmetrical with respect to the supporting element, the two connecting beams and the supporting element are respectively connected by a torsion beam, and the extending directions of the two torsion beams are along the rotation axis directions of the two acoustic sensitive elements.
Preferably, the acoustic sensing structure layer and the cavity structure layer further comprise a first frame arranged at the periphery of the two acoustic sensing elements and the periphery of the two lower electrodes;
the metal bonding pad comprises an upper electrode bonding pad, two lower electrode bonding pads and a substrate layer bonding pad which are arranged on the first frame at the periphery of the acoustic sensitive structural element, and an electrode leading-out end is arranged on the substrate layer bonding pad;
an isolation groove is formed in the first frame at the periphery of the lower electrode, the positions of the isolation groove correspond to the upper electrode bonding pad and the lower electrode bonding pad, a first lead hole is formed in the isolation groove, and a silicon bonding pad corresponding to the upper electrode bonding pad and the lower electrode bonding pad is arranged in the isolation groove;
the oxide layer is provided with a second lead hole corresponding to the first lead hole position;
the two lower electrodes and the supporting element are connected with the silicon bonding pads in the corresponding isolation grooves through silicon leads.
Preferably, the upper cover plate further includes a second frame, and the width of the second frame is smaller than that of the first frame, so that the upper electrode pad, the lower electrode pad and the substrate layer pad on the first frame around the periphery of the acoustic sensor are located at the outer side of the second frame.
Preferably, the sound transmission hole is formed in the second frame, and the sound barrier is a plate-shaped sound barrier plate formed in the second frame at a side corresponding to the sound transmission hole.
Preferably, the first frame and the second frame may be a unitary frame structure.
Preferably, the area of each of the acoustic sensing elements is larger than the area of its corresponding lower electrode.
Preferably, the resistivity of the acoustic sensitive structure layer and the cavity structure layer is less than or equal to 0.01The resistivity of the substrate layer is 1-10->。
Preferably, the oxide layer has a thickness of 2 μm.
It is still another object of the present invention to provide a microphone including the single-pivot differential structure anti-vibration interference chip as described in any one of the above.
Compared with the prior art, the invention has the advantages that:
according to the single-pivot differential structure anti-vibration interference chip, the two acoustic sensitive elements with the same structure are symmetrically arranged, the sound transmission hole is formed in the upper portion of one acoustic sensitive element, and the sound baffle is arranged in the upper portion of the other acoustic sensitive element, so that differential detection output of sound signals is achieved, but deformation of the two acoustic sensitive elements is identical under the action of vibration interference, therefore, capacitance variation of the two capacitors is identical, after differential output, output signals are zero, and the purpose of anti-vibration interference is achieved.
Drawings
The invention is further described below with reference to the accompanying drawings and examples:
fig. 1 is a schematic diagram of a package structure of an anti-vibration and interference chip with a single-pivot differential structure according to an embodiment of the present invention;
fig. 2 is a schematic diagram of an explosion structure of an anti-vibration interference chip with a single-pivot differential structure according to an embodiment of the present invention;
FIG. 3 is a schematic cross-sectional view of a single-pivot differential structure anti-vibration chip according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of an upper cover plate of an anti-vibration interference chip with a single-pivot differential structure according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of an acoustic sensitive structure layer of an anti-vibration and interference chip with a single-pivot differential structure according to an embodiment of the present invention
Fig. 6 is a schematic structural diagram of a cavity structure layer of a single-pivot differential structure anti-vibration interference chip according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of a substrate of a single-pivot differential structure anti-vibration interference chip according to an embodiment of the present invention;
FIG. 8 is a first-order modal analysis result diagram of a microphone chip according to an embodiment of the invention;
FIG. 9 is a graph showing the second-order modal analysis result of a microphone chip according to an embodiment of the invention;
FIG. 10 is an acoustic simulation model of a microphone chip according to an embodiment of the invention;
FIG. 11 is a graph showing the displacement response of an acoustic sensitive structure layer when the amplitude of an acoustic wave is 1Pa and the frequency is 1000Hz during frequency domain analysis of a microphone chip according to an embodiment of the present invention;
FIG. 12 is a graph showing the displacement response of the microphone according to the embodiment of the present invention, when the amplitude of the vibration disturbance in the Z direction (i.e., the vertical direction shown in the figure) is 1g and the frequency is 1000 Hz;
FIG. 13 is a graph showing the displacement response of the microphone according to the embodiment of the present invention when the amplitude of the vibration disturbance in the X direction (i.e., the left-right direction shown in the figure) is 1g and the frequency is 1000 Hz;
fig. 14 is a graph showing a displacement response of a microphone according to an embodiment of the present invention, when the amplitude of vibration disturbance in the Y direction (i.e., the front-rear direction shown in the figure) is 1g and the frequency is 1000 Hz.
Wherein: 1. an upper cover plate; 11. an acoustic baffle; 12. a sound-transmitting hole; 13. a second frame; 2. a metal pad; 21. a lower electrode pad; 22. an upper electrode pad; 23. a lower electrode pad; 24. a substrate layer pad; 25. an electrode lead-out terminal; 3. an acoustically sensitive structural layer; 31. a first anchor point; 32. a torsion beam; 33. a connecting beam; 34. an acoustic sensor; 35. a damping hole; 36. an acoustic sensor; 37. a first frame a; 4. a cavity structural layer; 41. a lower electrode; 41. a lower electrode; 42. a silicon lead; 43. a silicon pad; 44. a first lead hole; 45. an isolation groove; 46. a second anchor point; 47. a first frame b; 5. an oxide layer; 51. a second lead hole; 6. a substrate layer; 7. a support element.
Detailed Description
The objects, technical solutions and advantages of the present invention will become more apparent by the following detailed description of the present invention with reference to the accompanying drawings. It should be understood that the description is only illustrative and is not intended to limit the scope of the invention. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the present invention.
Examples:
referring to fig. 1 to 7, a single-pivot differential structure anti-vibration interference chip in an embodiment of the present invention sequentially includes an upper cover plate 1, an acoustic sensitive structure layer 3, a cavity structure layer 4 and a substrate from top to bottom. The acoustic sensor layer 3 is composed of two acoustic sensors 34 and 36 symmetrically distributed on both sides of the support element 7, and damping holes 35 are formed in both acoustic sensors, namely, the acoustic sensor 34 and the acoustic sensor 3 6. The cavity structure layer 4 includes two lower electrodes 41 spaced apart from each other, and the two lower electrodes 41 are in one-to-one correspondence with and opposite to two acoustic sensing elements, that is, the acoustic sensing element 34 and the acoustic sensing element 36, so as to form two capacitors, and the two acoustic sensing elements, that is, the acoustic sensing element 34 and the acoustic sensing element 36, are simultaneously respectively used as upper electrodes of the two capacitors. The upper cover plate 1 is hollowed out to form the sound-transmitting hole 12 corresponding to the position of one of the acoustic sensors, specifically the acoustic sensor 36, and is implemented as a sound barrier corresponding to the position of the other acoustic sensor, specifically the acoustic sensor 34. The substrate is composed of an oxide layer 5 and a silicon layer 6 stacked one on top of the other.
When sound waves at a distance are transmitted to the microphone, due to the effect of the sound barrier part, the sound pressure received by the acoustic sensor 34 with the sound barrier part above is far smaller than the sound pressure received by the acoustic sensor 36 without the sound barrier part above, the upper electrode of the capacitor rotates under the effect of the sound pressure difference, so that the capacitance of one capacitor is reduced, the capacitance of the other capacitor is increased, and the change of the capacitance is converted into the change of voltage through the tone-tuning conditioning circuit, so that the conversion from sound wave signals to electric signals is realized.
Since vibration disturbance is an inertial force, when the microphone is disturbed by vibration, both acoustic sensitive elements of the microphone are affected by the vibration. Because the two acoustic sensing elements, namely the acoustic sensing element 34 and the acoustic sensing element 36, are symmetrically distributed and have the same structure, the deformation of the two acoustic sensing elements, namely the acoustic sensing element 34 and the acoustic sensing element 36, is the same under the action of vibration interference, therefore, the capacitance variation of the two capacitors is the same, and after differential output, the output signal is zero, so that the purpose of resisting vibration interference is realized.
According to some embodiments of the invention, the acoustically-sensitive structure layer is fabricated from a device layer of an SOI sheet that is P-type (semiconductor) and has a resistivity of less than or equal to 0.01. The cavity structure layer is processed from the device layer of another SOI sheet, the device layer of the SOI sheet is also P-type, and the resistivity is less than or equal to 0.01->. The thickness of the oxide layer 5 of the substrate in the chip may be chosen to be 2 μm. The silicon layer 6 of the substrate in the chip is alsoP-type, resistivity is selected to be 1-10->。
When the microphone device of the embodiment of the invention is acted by sound waves, the sound pressure of the acoustic sensing element 36 of the soundless baffle 11 right above is far greater than the sound pressure of the acoustic sensing element 34 of the soundless baffle 11 right above, and the two acoustic sensing elements, namely the acoustic sensing element 34 and the acoustic sensing element 36, are twisted under the action of the sound pressure difference, so that the capacitance of the two capacitors is changed. Assume that the initial capacitance of the two capacitors is C 0 Capacitor capacitance reduction with sound baffle 11 above when exposed to sound wavesThe capacitor capacitance of the upper silence mask 11 increases +.>Then the differential variation of the microphone capacitance is 2 +.>The conversion from the sound wave signal to the electric signal is realized through the C-V conversion circuit, and when the sound wave signal is interfered by vibration, the two capacitors have the same change and no signal is output.
According to some preferred embodiments of the present invention, the facing ends of the two acoustic sensors, namely acoustic sensor 34 and acoustic sensor 36, are rigidly connected by two connecting beams 33 symmetrical with respect to the support element 7, the two connecting beams 33 and the support element 7 being connected by one torsion beam 32, respectively, the two torsion beams 32 extending in the direction of the axis of rotation of the two acoustic sensors, namely acoustic sensor 34 and acoustic sensor 3 6. Specifically, as shown in fig. 5, two acoustic sensing elements, that is, the acoustic sensing element 34 and the acoustic sensing element 36 are plates with a plurality of damping holes 35 formed in the middle, the two plates are symmetrically arranged left and right, a first anchor point 31 (the first anchor point 31 is a square block in the drawing) is arranged in the middle of the two plates, the left and right sides of the first anchor point 31 are not connected with the two acoustic sensing elements, that is, the acoustic sensing element 34 and the acoustic sensing element 36 on two sides, that is, are provided with a space, a strip-shaped connecting strip extending in the front-back direction, that is, the torsion beam 32 is respectively connected on the front and back sides of the first anchor point 31, and the outer ends of the two torsion beams 32, that is, the front end of the torsion beam 32 on the front side as shown in fig. 5 and the rear end of the torsion beam 32 are respectively connected with a connecting block, that is, the connecting beam 33 is respectively connected with the left and right ends of the two connecting beams 33 respectively rigidly with the two acoustic sensing elements, that is, the acoustic sensing element 34 and the end of the acoustic sensing element 36, so as to form a long unit composed of an upper electrode. When sound waves are transmitted to the microphone, the two acoustic transducers rotate up and down around the two torsion beams 32 and the first anchor point 31 due to the action of the sound pressure difference, that is, the axes of the acoustic transducers, that is, the acoustic transducers 34 and the acoustic transducers 36, actually refer to the two torsion beams 32 or the extension line of the torsion beams 32, that is, a straight line extending in the front-rear direction passing through the two torsion beams 32 and the first anchor point 31 as shown in fig. 5. The upper electrode, the connecting beam 33, the torsion beam 32, and the first anchor point 31 are an equipotential body. Preferably, in the embodiment of the present invention, the first anchor point 31, the two torsion beams 32, the two connection beams 33, and the two acoustic sensors, that is, the acoustic sensor 34 and the acoustic sensor 36 are integrally formed.
According to some embodiments of the present invention, the acoustic sensing structure layer 3 and the cavity structure layer 4 further comprise a first frame provided at the periphery of the two acoustic sensing elements, i.e. the acoustic sensing element 34 and the acoustic sensing element 36, and at the periphery of the two lower electrodes 41. For convenience of description and distinction, as shown in fig. 5 and 6, the first frames of the peripheries of the acoustic sensor 34 and the acoustic sensor 36 are described as a first frame a 37, the first frames of the peripheries of the two lower electrodes 41 are described as a first frame b 47, and in practice, the first frame a 37 and the first frame b 47 are actually an integral frame structure. An upper electrode pad 22, a lower electrode pad (reference numerals 21 and 23 in the figure) and a substrate layer pad 24 are formed on the first frame a 37, and an electrode lead-out terminal 25 is provided on the substrate layer pad 24, the electrode lead-out terminal 25 being metal in a substrate layer lead hole, it being possible to realize the arrangement of the pad of the substrate layer 6 to the device surface through a metal lead. Isolation grooves 45 are provided in the first frame b 47 at positions corresponding to the upper electrode pads 22 and the lower electrode pads (reference numerals 21 and 23 in the figure) and first lead holes 44 are provided at positions corresponding to the metal 25, and silicon pads 43 (specifically, including upper electrode silicon pads corresponding to the upper electrode pads 22 and lower electrode silicon pads corresponding to the lower electrode pads) corresponding to the upper electrode pads 22 are provided in the isolation grooves 45. As shown in fig. 7, the oxide layer 5 is provided with a second lead hole 51 at a position corresponding to the first lead hole 44, and the first lead hole 44 and the second lead hole 51 each correspond to a metal lead (not shown) on the substrate layer 6. Both the lower electrodes 41 and the second anchor points 46 are connected to the silicon pads 43 in the corresponding isolation trenches 45 through the silicon leads 42. Specifically, as shown in fig. 5, the number of upper electrode pads 22 is one, the number of lower electrode pads is two, and two lower electrode pads (reference numerals 21 and 23 in the figure) are located on both left and right sides of the upper electrode pad 22 and are provided on the first frame a 37. As shown in fig. 6, the number of upper electrode silicon pads is one, the number of lower electrode silicon pads is two, and the two lower electrode silicon pads are located on the left and right sides of the upper electrode silicon pad and are all distributed on the first frame b 47. As shown in fig. 6, the two lower electrodes 41 are arranged at a left-right interval, and a second anchor point 46 is further arranged between the two lower electrodes 41, and the second anchor point 46 and the first anchor point 31 together form the supporting element 7. The two lower electrodes 41 are connected to the lower electrode silicon pads in the corresponding two isolation trenches 45 through silicon leads 42, and the second anchor points 46 are connected to the upper electrode silicon pads in the corresponding isolation trenches 45 through silicon leads 42.
According to some embodiments of the present invention, the upper cover plate 1 further includes a second frame 13, and the width of the second frame 13 is smaller than that of the first frame such that the upper electrode pad 22, the lower electrode pad (reference numerals 21 and 23 in the drawings), and the substrate layer pad 24 on the first frame a 37 are located outside the second frame 13. As shown in fig. 4, the front side of the second frame 13 falls on the front side of the first frame and is located at the rear ends of the upper electrode pad 22, the lower electrode pad (reference numerals 21 and 23 in the drawing) and the substrate layer pad 24. The purpose of this design is to facilitate the placement of the upper electrode pad 22, lower electrode pads (numbered 21 and 23 in the figure), and substrate layer pad 24. As an alternative embodiment, the first frame and the second frame 13 may be an integral structure, which is convenient for processing and production, and can reduce processing steps and processing cost.
According to some embodiments of the present invention, the sound-transmitting hole 12 is formed in the second frame 13, specifically, as shown in fig. 4, at the right end of the second frame 13, and the sound-blocking portion is a plate-shaped sound-blocking plate 11 formed in the second frame 13 on the side corresponding to the sound-transmitting hole 12, that is, on the left side of the sound-transmitting hole 12 as shown in fig. 4.
According to some preferred embodiments of the present invention, the area of each acoustic sensing element is larger than the area of its corresponding lower electrode 41. When the microphone is disturbed by vibration in the X/Y direction, the capacitance of the two capacitors does not change since the area of the lower electrode 41 is smaller than that of the upper electrode. The purpose of vibration resistance can be achieved.
In order to verify the feasibility of the microphone chip structure provided by the embodiment of the invention, a three-dimensional model of the microphone device is established. The first-order modal analysis result is shown in fig. 8, the natural frequency is 2367.4+2260.6i Hz, the modal shape is that the acoustic sensitive structure rotates around the axis (expressed by the Y axis) where the front and back directions are shown, the capacitance of one capacitor is increased, the capacitance of the other capacitor is reduced, and the requirement of capacitance difference when the acoustic wave is detected is met. The second-order modal analysis result is shown in fig. 9, the natural frequency is 10430+10.127i Hz, the second-order natural frequency is 4.4 times of the first-order natural frequency, cross coupling of the structure can be effectively avoided, and lower off-axis sensitivity of the sensitive structure is ensured.
An acoustic simulation model of the microphone device as shown in fig. 10, the surroundings of the microphone device are air. In the frequency domain analysis, when the amplitude of the sound wave is set to be 1Pa and the frequency is set to be 1000Hz, the displacement response of the acoustic sensitive structure layer is shown in fig. 11 (the scaling ratio is 200000), and as can be seen from fig. 11, the microphone device of the embodiment of the invention can realize the detection of the sound wave signal, extract the capacitance variation of the two capacitors and obtain the total capacitance variation by difference as 0.0347fF. When the microphone device is disturbed by vibration having an amplitude of 1g in the vertical direction (expressed by the Z direction) and a frequency of 1000Hz as shown in fig. 12, the displacement response of the microphone frequency domain analysis is as shown in fig. 12 (scaling 300000), and the capacitance variation amounts of the two capacitors are extracted and differentiated to obtain a total capacitance variation amount of 0.000016fF. When the microphone device is disturbed by vibration having an amplitude of 1g in the left-right direction (expressed by the X direction) and a frequency of 1000Hz as shown in fig. 13, the displacement response of the microphone device in the frequency domain analysis is as shown in fig. 13 (scaling of 100000), and the capacitance variation amounts of the two capacitors are extracted and differentiated to obtain a total capacitance variation amount of 0.00037fF. When the microphone is disturbed by vibration having an amplitude of 1g in the front-rear direction (expressed by Y direction) and a frequency of 1000Hz as shown in fig. 14, the displacement response of the microphone device in the frequency domain analysis is as shown in fig. 14 (scaling ratio is 40000000), and the capacitance variation amounts of the two capacitors are extracted and differentiated to obtain a total capacitance variation amount of 0.0000012fF. In summary, the capacitance variation generated when the microphone structure provided by the embodiment of the invention is interfered by vibration is far smaller than the capacitance variation generated when the microphone structure is interfered by sound wave signals. Therefore, the purpose of anti-vibration interference can be achieved.
Referring to fig. 1 to 14, the embodiment of the present invention further provides a microphone including the low-frequency anti-vibration interference chip of the above embodiment. The chip of the above embodiment is at least beneficial to the chip of the above embodiment, and detailed description thereof is omitted.
It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explanation of the principles of the present invention and are in no way limiting of the invention. Accordingly, any modification, equivalent replacement, improvement, etc. made without departing from the spirit and scope of the present invention should be included in the scope of the present invention. Furthermore, the appended claims are intended to cover all such changes and modifications that fall within the scope and boundary of the appended claims, or equivalents of such scope and boundary.
Claims (10)
1. The single-fulcrum differential structure anti-vibration interference chip is characterized by comprising an upper cover plate, an acoustic sensitive structure layer, a cavity structure layer and a substrate from top to bottom in sequence; wherein,
the acoustic sensing structure layer comprises two acoustic sensing elements symmetrically distributed on two sides of the supporting element, damping holes are formed in the two acoustic sensing elements, and a metal bonding pad is further arranged on the acoustic sensing structure layer;
the cavity structure layer comprises two lower electrodes which are distributed at intervals, the two lower electrodes are in one-to-one correspondence with the two acoustic sensitive elements and are oppositely arranged to form two capacitors, and the two acoustic sensitive elements are simultaneously used as upper electrodes of the two capacitors respectively;
the upper cover plate is hollowed out corresponding to the position of one acoustic sensing element to form an acoustic transmission hole, and the position corresponding to the other acoustic sensing element is implemented as an acoustic barrier part;
the substrate is composed of an oxide layer and a silicon layer which are stacked up and down.
2. The single-pivot differential structure anti-vibration interference chip according to claim 1, wherein the facing ends of the two acoustic sensitive elements are rigidly connected by two connecting beams symmetrical with respect to the supporting element, the two connecting beams and the supporting element are respectively connected by a torsion beam, and the extending directions of the two torsion beams are along the rotation axis directions of the two acoustic sensitive elements.
3. The single-pivot differential structure anti-vibration interference chip of claim 1 or 2, wherein the acoustic sensitive structure layer and the cavity structure layer further comprise a first frame provided at the periphery of the two acoustic sensitive elements and the periphery of the two lower electrodes;
the metal bonding pad comprises an upper electrode bonding pad, two lower electrode bonding pads and a substrate layer bonding pad which are arranged on the first frame at the periphery of the acoustic sensitive element, and an electrode leading-out end is arranged on the substrate layer bonding pad;
an isolation groove is formed in the first frame at the periphery of the lower electrode, the positions of the isolation groove correspond to the upper electrode bonding pad and the lower electrode bonding pad, a first lead hole is formed in the isolation groove, and a silicon bonding pad corresponding to the upper electrode bonding pad and the lower electrode bonding pad is arranged in the isolation groove;
the oxide layer is provided with a second lead hole corresponding to the first lead hole position;
the two lower electrodes and the supporting element are connected with the silicon bonding pads in the corresponding isolation grooves through silicon leads.
4. The single-pivot differential structure anti-vibration interference chip of claim 3 wherein the upper cover plate further comprises a second rim having a width smaller than the width of the first rim such that the upper electrode pad, lower electrode pad and substrate layer pad on the first rim at the periphery of the acoustic sensor are located outside the second rim.
5. The single-pivot differential structure anti-vibration interference chip as defined in claim 4, wherein the sound-transmitting hole is formed in the second frame, and the sound-blocking portion is a plate-shaped sound-blocking plate formed in the second frame at a side corresponding to the sound-transmitting hole.
6. The single-pivot differential structure anti-vibration interference chip of claim 4 or 5, wherein the first and second rims are a unitary rim structure.
7. The single-pivot differential structure anti-vibration interference chip of claim 1 wherein each of said acoustic sensing elements has an area greater than an area of its corresponding lower electrode.
8. The single-pivot differential structure anti-vibration interference chip of claim 1, wherein the resistivity of the acoustic sensitive structure layer and the cavity structure layer is less than or equal to 0.01 Ω -cm, and the resistivity of the substrate layer is 1-10 Ω -cm.
9. The single-pivot differential structure anti-vibration interference chip of claim 1, wherein the oxide layer has a thickness of 2 μm.
10. A microphone comprising a single-pivot differential structure anti-vibration interference chip as claimed in any one of claims 1 to 9.
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