CN113347540A - Diaphragm, MEMS microphone chip and manufacturing method thereof - Google Patents
Diaphragm, MEMS microphone chip and manufacturing method thereof Download PDFInfo
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- CN113347540A CN113347540A CN202110893662.6A CN202110893662A CN113347540A CN 113347540 A CN113347540 A CN 113347540A CN 202110893662 A CN202110893662 A CN 202110893662A CN 113347540 A CN113347540 A CN 113347540A
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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
- H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
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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
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Abstract
The invention provides a diaphragm, an MEMS microphone chip and a manufacturing method thereof, wherein at least two air release valves which are uniformly distributed are arranged on a diaphragm body, and each air release valve comprises a movable part and a pore; the aperture has a stepped cross-section, and the "number of steps" of the stepped cross-section is one or more. According to the technical scheme disclosed by the invention, the air release valve with the step-shaped pore section is arranged, so that the air release valve can be opened when being impacted violently to play a role in quickly releasing pressure, and the damping of the pore to air can be increased when the air release valve is not opened, so that the low-frequency response of the MEMS microphone chip is improved; in addition, due to the adoption of the stepped structure, the sensitivity of low-frequency response to the size deviation of the pore is reduced, so that the process precision requirement can be reduced, and the yield and the consistency of products are improved.
Description
Technical Field
The invention belongs to the technical field of electroacoustic devices, and particularly relates to a diaphragm, an MEMS microphone chip and a manufacturing method thereof.
Background
MEMS (Micro-Electro-Mechanical systems) microphones are receiving attention due to their advantages of high sensitivity, low power consumption, flat frequency response, etc., and are becoming the mainstream of the microphone market today. The MEMS chip is an important component in the MEMS microphone, and the working principle is as follows: the vibrating diaphragm vibrates under the action of sound waves, so that the distance between the vibrating diaphragm and the back plate is changed, the capacitance is changed, and sound wave signals are converted into electric signals.
When the MEMS chip is severely impacted by blowing, dropping, etc., the diaphragm is easily broken and damaged due to excessive pressure, thereby causing the failure of the whole MEMS microphone. In response to this problem, it is usually selected to provide a release valve on the diaphragm to achieve the purpose of releasing the pressure quickly. The air release valve is opened when the sound pressure or the airflow changes sharply, so that the pressures on the upper side and the lower side of the vibrating diaphragm can be well balanced. But under normal conditions, the low frequency response of the MEMS microphone drops due to the undersampled air of the rectangular aperture in the pressure relief valve, and the extent of the drop is closely related to the aperture size. Therefore, the pressure relief effect and the degree of low frequency drop are contradictory, which not only requires balancing the size/number of the pressure relief junction valve, but also has a strict requirement on the process precision.
The foregoing is merely provided to assist in understanding the technical solutions of the present application and is not intended to be a disclaimer of the prior art.
Disclosure of Invention
In view of the above-mentioned prior art, an object of the present invention is to provide a diaphragm, an MEMS microphone chip and a method for manufacturing the same, in which the diaphragm is provided with an improved air release valve, and the diaphragm is opened to release pressure when being subjected to a severe impact, and the air damping is ensured to improve low-frequency response in normal application, thereby achieving better mechanical and electroacoustic performance.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the utility model provides a diaphragm, includes the vibrating diaphragm body, be provided with release valve on the vibrating diaphragm body, its characterized in that: the air release valve comprises a connecting end connected with the vibrating diaphragm body and a movable part separated from the connecting end, stepped step edges are arranged on the outer peripheral edge of the movable part and/or the vibrating diaphragm body, the movable part or the movable part is adjacent to the step edges between the vibrating diaphragm body and the movable part in a staggered mode to form a step sample platform, holes are formed between the staggered step edges, and the vertical cross section of each hole is stepped.
It can be understood that the periphery of the movable part of the air release valve and the adjacent structure are provided with pores, and the cross section of each pore is in a step shape. Correspondingly, the stepped section of the pore has a platform similar to a stepped multi-stage structure, at least one platform is arranged between two surfaces of the diaphragm, and one platform and the two surfaces of the diaphragm jointly form a two-stage step.
Alternatively,
the ladder-like platforms are one or more. That is, the "step number" of the cross section of the pore is two or more.
Alternatively,
the number of the air release valves is at least two, and the air release valves are uniformly distributed on the periphery of the diaphragm;
the shape of the vertical projection of the pore in different air escape valves is the same.
Optionally, the shape of the diaphragm is circular or other centrosymmetric patterns, and the material of the diaphragm is doped polysilicon or other flexible conductive thin films with tensile stress.
Optionally, the shape of the pores includes, but is not limited to, flower-type, cross-type, V-type, U-type.
Further, the present invention discloses an MEMS microphone chip made by using the above diaphragm, including:
the substrate is provided with a back cavity which penetrates along the vertical direction;
the vibrating diaphragm is arranged on one side of the substrate at intervals, and at least part of the vibrating diaphragm is arranged above the back cavity in a vibrating manner;
the back plate is arranged on one side of the vibrating diaphragm, which is far away from the substrate, at intervals; the back plate is also provided with a plurality of through holes which are arranged at intervals and penetrate through the back plate along the vertical direction;
the vibration gap is arranged between the vibrating diaphragm and the back plate and is positioned above the back cavity;
the vibrating diaphragm, the back plate and the vibrating gap together form a capacitor structure;
the sacrificial layer is positioned between the vibrating diaphragm and the back plate and positioned outside the vibrating gap;
the insulating layer is positioned between the vibrating diaphragm and the edge part of the substrate;
at least one of the electrodes is electrically connected with the back plate, and at least one of the electrodes is electrically connected with the vibrating diaphragm through part of the back plate;
the vibrating diaphragm is the diaphragm, and the air escape valve on the vibrating diaphragm body is communicated with the back cavity and the vibration gap.
Alternatively,
the shape of the vibrating diaphragm is a centrosymmetric pattern, and the vibrating diaphragm is made of a flexible conductive film with tensile stress. The flexible conductive film includes, but is not limited to, doped polysilicon.
Alternatively,
the backplane is a rigid conductive film including, but not limited to: a doped polysilicon layer is attached on/under the silicon nitride, and a metal layer is attached on/under the silicon nitride.
Alternatively,
contact holes are formed in the sacrificial layer, part of the back plate extends to the diaphragm through the surfaces of the contact holes, and the cross-sectional shape of the contact holes includes but is not limited to one of a rectangle, a trapezoid and an inverted trapezoid.
Alternatively,
the cross-sectional shape of the back cavity and the vibration gap includes, but is not limited to, one of a rectangle, a trapezoid, and an inverted trapezoid.
Alternatively,
the shape of the through hole includes but is not limited to one or more combinations of circle, polygon and flower.
Further, the invention discloses a manufacturing method of the MEMS microphone chip, which comprises the following steps:
s1: providing a substrate, and forming an insulating layer on the substrate;
s2: forming a vibrating diaphragm with a step-shaped air escape valve on the insulating layer;
s3: forming a sacrificial layer on the vibrating diaphragm, and partially etching a contact hole;
s4: forming a back plate on the sacrificial layer, etching a plurality of through holes locally, and connecting part of the back plate with the vibrating diaphragm through the contact holes;
s5: forming an electrode on the back plate;
s6: and forming a back cavity inwards on the lower surface of the substrate, releasing part of the sacrificial layer to form a vibration gap, and finishing the manufacture of the MEMS microphone chip.
Further, in the above-mentioned case,
in S2, the method for forming a diaphragm with a stepped release valve specifically includes the following steps:
s2-1: forming a first material layer on the vibrating diaphragm, and locally etching a first groove;
s2-2: forming a first transition layer on the first groove and the partial surface of the first material layer close to the first groove;
s2-3: and forming a second material layer on the surfaces of the first material layer and the first transition layer, and locally etching a second groove on the second material layer.
It should be noted that, by the above method, an air release valve with two steps may be formed, and the first material layer and the second material layer together form the diaphragm.
Alternatively to this, the first and second parts may,
and repeating S2-2 to S2-3 to form the air escape valve with a plurality of step-shaped platforms. Thus, the air release valve with a plurality of steps can be formed.
Alternatively to this, the first and second parts may,
in S1, the substrate is a semiconductor substrate with double-side polishing, the semiconductor substrate includes but is not limited to one of a silicon substrate, a germanium substrate and a silicon carbide substrate; the insulating layer is made of silicon oxide.
Alternatively to this, the first and second parts may,
in S2, the diaphragm, the first material layer, and the second material layer are made of doped polysilicon or other flexible conductive films with tensile stress, and the first transition layer is made of silicon oxide.
Alternatively to this, the first and second parts may,
in S3, the material of the sacrificial layer is silicon oxide, and the cross-sectional shape of the contact hole includes, but is not limited to, one of a rectangle, a trapezoid, and an inverted trapezoid.
Alternatively to this, the first and second parts may,
at S4, the back plate is made of a rigid conductive film, which includes but is not limited to: a doped polysilicon layer is attached to the upper part/lower part of the silicon nitride, and a metal layer is attached to the upper part/lower part of the silicon nitride; the shape of the through hole is one or the combination of a plurality of circular shapes, polygonal shapes and flower shapes.
Alternatively to this, the first and second parts may,
in S5, the electrode is made of one or more of titanium, tungsten, chromium, platinum, aluminum, and gold.
Alternatively to this, the first and second parts may,
in S6, the cross-sectional shapes of the back cavity and the vibration gap include, but are not limited to, one of a rectangle, a trapezoid, and an inverted trapezoid.
As described above, according to the diaphragm and the MEMS microphone chip disclosed by the present invention, by providing the air release valve having the step-shaped cross section of the aperture, the diaphragm can be opened when being subjected to a severe impact, thereby playing a role of rapidly releasing the pressure, and the damping of the aperture to the air can be increased when the diaphragm is not in the opened state, thereby ensuring the low-frequency sensitivity of the MEMS microphone, i.e., improving the low-frequency response of the MEMS microphone chip. In addition, due to the adoption of the stepped structure, the sensitivity of low-frequency response to the size deviation of the pore is reduced, so that the process precision requirement can be reduced, and the yield and the consistency of products are improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.
Fig. 1 is a partial cross-sectional view of a conventional diaphragm in a normal condition, i.e., a state where a release valve is not opened.
Fig. 2 is a partial cross-sectional view of a conventional diaphragm showing the opening of a release valve when the diaphragm is impacted.
Fig. 3 is a schematic partial cross-sectional view of a diaphragm provided in embodiment 1 of the present invention.
Fig. 4 is a schematic partial cross-sectional view of a diaphragm provided in embodiment 2 of the present invention.
Fig. 5 is a schematic cross-sectional view of a MEMS microphone chip according to embodiment 3 of the present invention.
Fig. 6 is a flowchart of a method for manufacturing a MEMS microphone chip according to embodiment 4 of the present invention.
Fig. 7a to 7i are diagrams illustrating specific process steps of an MEMS microphone chip according to embodiment 4 of the present invention.
In the figure: 10. a substrate; 11. a back cavity; 20. an insulating layer; 30. a diaphragm body; 31. a first material layer; 32. a second material layer; 33. a gas release valve; 331. a pore; 332. a movable portion; 41. a first groove; 42. a second groove; 51. a first transition layer; 52. a sacrificial layer; 53. a vibration gap; 60. a back plate; 61. a through hole; 70. and an electrode.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.
It should be noted that the directional indications (such as up, down, left, and right … …) in the embodiment of the present invention are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture, and if the specific posture is changed, the directional indication is changed accordingly. In addition, the descriptions related to "first", "second", etc. in the present invention are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature.
Example 1: the embodiment provides a diaphragm, including diaphragm body 30, as shown in fig. 3, be provided with run-off valve 33 on the diaphragm body 30, run-off valve 33 includes the link of being connected with diaphragm body 30 and the movable part 332 that leaves the link, the outer peripheral edge of movable part 332 and the last ladder edge that has the echelonment of diaphragm body 30, adjacent the crisscross setting of ladder edge between movable part 332 or movable part 332 and the diaphragm body 30 forms ladder appearance platform, forms hole 331 between the ladder edge of crisscross setting, hole 331 vertical section is the echelonment. I.e. the aperture 331 has a stepped cross-section.
As shown in fig. 3, in the present embodiment, there is one step-like platform. That is, the "step number" of the cross section of the aperture 331 is two.
Specifically, the shape of the diaphragm body 30 is circular or other centrosymmetric patterns, and the material of the diaphragm body 30 is doped polysilicon or other flexible conductive films with tensile stress; in the embodiment of the present invention, the diaphragm body 30 is circular, and the material is doped polysilicon.
Specifically, the number of the air release valves 33 is at least two, and the air release valves are uniformly distributed on the periphery of the diaphragm body 30; in the embodiment of the present invention, the number of the air escape valves 33 is eight. The shape of the vertical projection of the aperture 331 in different air escape valves 33 is the same or different; the number of the step-like platforms in different relief valves 33 is the same or different.
Specifically, the shape of the aperture 331 includes, but is not limited to, flower type, cross type, V type, U type, and the plurality of apertures 331 are the same or different in shape; in the embodiment of the present invention, the plurality of apertures 331 are all shaped in a flower pattern.
Example 2: as shown in fig. 4, in the present embodiment, the stepped platform is multiple. That is, the "step number" of the cross section of the aperture 331 is plural. The rest of this example is the same as example 1.
In embodiment 1 of the present invention, as shown in fig. 3, the "step number" of the cross section of the aperture 331 is two; in embodiment 2 of the present invention, as shown in fig. 4, the "step number" of the cross section of the aperture 331 is three.
It should be noted that, referring to fig. 1-2, the aperture 331 of the conventional release valve 33 is generally rectangular, and although such release valve 33 can be opened to release the pressure when being impacted severely, under normal conditions, that is, when the release valve 33 is in the non-open state, the rectangular aperture 331 has too little damping to the air, which may cause the low-frequency response of the MEMS microphone to drop seriously. In contrast, the stepped aperture 331 provided in the embodiment of the present invention can increase the air damping under normal conditions, thereby improving the low frequency response of the MEMS microphone.
Example 3: as shown in fig. 5, the present invention also provides a MEMS microphone chip, including:
a substrate 10 provided with a back chamber 11 penetrating in an up-down direction;
the vibrating diaphragm body 30 is arranged on one side of the substrate 10 at intervals, and at least part of the vibrating diaphragm body 30 is arranged above the back cavity 11 in a vibrating manner;
the back plate 60 is arranged at one side of the diaphragm body 30 away from the substrate 10 at intervals; one or more through holes 61 arranged at intervals are also arranged in the back plate 60, and the through holes 61 penetrate through the back plate 60 along the vertical direction;
a vibration gap 53 disposed between the diaphragm body 30 and the back plate 60 and above the back cavity 11;
the diaphragm body 30, the back plate 60 and the vibration gap 53 together form a capacitor structure;
a sacrificial layer 52 located between the diaphragm body 30 and the back plate 60 and outside the vibration gap 53;
an insulating layer 20 located between the diaphragm body 30 and the edge portion of the substrate 10;
and at least one of the electrodes 70 is electrically connected to the back plate 60, and at least one of the electrodes is electrically connected to the diaphragm body 30 through a part of the back plate 60.
Specifically, the MEMS microphone chip adopts the MEMS diaphragm described in embodiment 1, the MEMS diaphragm includes a diaphragm body 30, and the air release valve 33 on the diaphragm body 30 communicates with the back cavity 11 and the vibration gap 53.
Specifically, the shape of the diaphragm body 30 is a centrosymmetric pattern, and the material of the diaphragm body 30 is doped polysilicon or other flexible conductive thin films with tensile stress.
Specifically, the back plate 60 employs rigid conductive films, including but not limited to: a doped polysilicon layer attached to/under silicon nitride, and a metal layer attached to/under silicon nitride, in the embodiment of the present invention, the back plate 60 is a doped polysilicon layer attached to/under silicon nitride.
Specifically, the shape of the through hole 61 includes, but is not limited to, one or more combinations of circles, polygons, flower shapes; in the embodiment of the present invention, the shape of the through-hole 61 is a regular hexagon.
Specifically, a contact hole is formed in the sacrificial layer 52, and a portion of the back plate 60 extends to the diaphragm body 30 through the surface of the contact hole, and the cross-sectional shape of the contact hole includes, but is not limited to, one of a rectangle, a trapezoid, and an inverted trapezoid; in an embodiment of the present invention, the cross-sectional shape of the contact hole is rectangular.
Specifically, the cross-sectional shapes of the back cavity 11 and the vibration gap 53 include, but are not limited to, one of a rectangle, a trapezoid, and an inverted trapezoid; in the embodiment of the present invention, the cross-sectional shapes of the back cavity 11 and the vibration gap 53 are both rectangular.
Example 4: referring to fig. 6, the present invention further provides a method for manufacturing the MEMS microphone chip, including the steps of:
s1: providing a substrate 10, and forming an insulating layer 20 on the substrate 10, as shown in fig. 7 a;
specifically, the substrate 10 is a semiconductor substrate polished on both sides, including but not limited to one of a silicon substrate, a germanium substrate, and a silicon carbide substrate; in the embodiment of the present invention, the substrate 10 is a single crystal silicon substrate polished on both sides.
Specifically, the material of the insulating layer 20 is silicon oxide, and can be formed by thermal oxidation, low-pressure chemical vapor deposition, and plasma chemical vapor deposition; in the embodiment of the present invention, the insulating layer 20 is formed by a thermal oxidation method.
S2: forming a diaphragm body 30 with a step-shaped air release valve 33 on the insulating layer 20, as shown in fig. 7 b-7 d;
further, the method for forming the diaphragm body 30 with the stepped air release valve 33 includes the following steps:
s2-1: forming a first material layer 31 on the diaphragm body 30, and partially etching a first groove 41, as shown in fig. 7 b;
s2-2: forming a first transition layer 51 on the first groove 41 and a portion of the surface of the first material layer 31 near the first groove 41, as shown in fig. 7 c;
s2-3: a second material layer 32 is formed on the surfaces of the first material layer 31 and the first transition layer 51, and a second groove 42 is partially etched in the second material layer 32, as shown in fig. 7 d.
It should be noted that, by the above method, the air release valve 33 with two steps can be formed, and the first material layer 31 and the second material layer 32 together form the diaphragm body 30; repeating S2-2 to S2-3, the air escape valve 33 with multiple steps can be formed.
Specifically, the material of the diaphragm body 30, the first material layer 31 and the second material layer 32 is doped polysilicon or other flexible conductive films with tensile stress; in the embodiment of the present invention, the material of the diaphragm body 30 is doped polysilicon, and is formed by a combination of methods such as low pressure chemical vapor deposition, ion implantation, annealing, and the like.
Specifically, the first groove 41 and the second groove 42 have a rectangular cross section and are formed by a deep reactive ion etching method.
Specifically, the material of the first transition layer 51 is silicon oxide, and can be formed by a low-pressure chemical vapor deposition method or a plasma chemical vapor deposition method; in an embodiment of the present invention, the first transition layer 51 is formed by a plasma chemical vapor deposition method.
S3: forming a sacrificial layer 52 on the diaphragm body 30, and partially etching a contact hole, as shown in fig. 7 e;
specifically, the material of the sacrificial layer 52 is silicon oxide, and may be formed by a low pressure chemical vapor deposition method or a plasma chemical vapor deposition method, and the contact hole may be formed by an ion beam etching method or a reactive ion etching method, and its cross-sectional shape includes, but is not limited to, one of a rectangle, a trapezoid, and an inverted trapezoid; in the embodiment of the present invention, the sacrificial layer 52 is formed by a plasma chemical vapor deposition method, and the contact hole having a rectangular cross section is formed by a reactive ion etching method.
S4: forming a back plate 60 on the sacrificial layer 52, and partially etching a plurality of through holes 61, and connecting part of the back plate 60 to the diaphragm body 30 through the contact holes, as shown in fig. 7 f;
specifically, the back plate 60 employs rigid conductive films, including but not limited to: a doped polysilicon layer is attached on/under the silicon nitride, a metal layer is attached on/under the silicon nitride, and the shape of the through hole 61 includes but is not limited to one or more combinations of circle, polygon and flower; in an embodiment of the present invention, the back plate 60 is formed by attaching a doped polysilicon layer under silicon nitride, wherein the doped polysilicon layer is formed by a combination of low pressure chemical vapor deposition, ion implantation, annealing, etc., the silicon nitride layer is formed by plasma chemical vapor deposition, and the through holes 61 are in the shape of regular hexagons and are formed by a combination of reactive ion etching and deep reactive ion etching methods.
S5: forming an electrode 70 on the back plate 60, as shown in fig. 7 g;
specifically, the electrode 70 is made of one or more of titanium, tungsten, chromium, platinum, aluminum, and gold, and is formed by a lift-off process, or by a method of sputtering or evaporation followed by etching; in an embodiment of the present invention, the material of the electrode 70 is chrome/gold, formed by a lift-off process.
It is easy to understand that the electrode 70 needs to be connected to the conductive layer of the backplate 60 (in the embodiment of the present invention, the conductive layer of the backplate 60 is doped polysilicon), and only the non-conductive layer on the backplate 60 (in the embodiment of the present invention, the non-conductive layer of the backplate 60 is silicon nitride) at the corresponding position needs to be etched before the electrode 70 is formed, which is not described herein again in detail.
S6: forming a back cavity 11 inward on the lower surface of the substrate 10, releasing part of the sacrificial layer 52, forming a vibration gap 53, and completing the fabrication of the MEMS microphone chip, as shown in fig. 7 h-7 i;
specifically, the cross-sectional shapes of the back cavity 11 and the vibration gap 53 include, but are not limited to, one of a rectangle, a trapezoid, and an inverted trapezoid; in the embodiment of the present invention, the cross-sectional shapes of the back cavity 11 and the vibration gap 53 are both rectangular, wherein the back cavity 11 is formed by a deep reactive ion etching method, and the vibration gap 53 is formed by a BOE wet etching method.
In summary, the diaphragm and the MEMS microphone chip disclosed by the present invention, by providing the air release valve with the step-shaped pore cross section, not only can be opened when being subjected to a severe impact to play a role in releasing pressure quickly, but also can increase the damping of the pore to air when not in an open state, thereby ensuring the low frequency sensitivity of the MEMS microphone, i.e. improving the low frequency response of the MEMS microphone chip. In addition, due to the adoption of the stepped structure, the sensitivity of low-frequency response to the size deviation of the pore is reduced, so that the process precision requirement can be reduced, and the yield and the consistency of products are improved.
Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (10)
1. The utility model provides a diaphragm, includes the vibrating diaphragm body, be provided with release valve on the vibrating diaphragm body, its characterized in that: the air release valve comprises a connecting end connected with the vibrating diaphragm body and a movable part separated from the connecting end, stepped step edges are arranged on the outer peripheral edge of the movable part and/or the vibrating diaphragm body, the movable part or the movable part is adjacent to the step edges between the vibrating diaphragm body and the movable part in a staggered mode to form a step sample platform, holes are formed between the staggered step edges, and the vertical cross section of each hole is stepped.
2. A diaphragm according to claim 1, wherein:
the ladder-like platforms are one or more.
3. A diaphragm according to claim 2, wherein:
the number of the air release valves is at least two, and the air release valves are uniformly distributed on the periphery of the diaphragm body;
the shape of the vertical projection of the pore in different air escape valves is the same.
MEMS microphone chip which characterized in that: the method comprises the following steps:
the substrate is provided with a back cavity which penetrates along the vertical direction;
the vibrating diaphragm is arranged on one side of the substrate at intervals, and at least part of the vibrating diaphragm is arranged above the back cavity in a vibrating manner;
the back plate is arranged on one side of the vibrating diaphragm, which is far away from the substrate, at intervals; and the number of the first and second groups,
the vibration gap is arranged between the vibrating diaphragm and the back plate and is positioned above the back cavity;
the vibrating diaphragm, the back plate and the vibrating gap together form a capacitor structure;
the diaphragm of any one of claims 1 to 3, wherein the air release valve on the diaphragm body is connected to the back cavity and the vibration gap.
5. The MEMS microphone chip of claim 4, wherein: further comprising:
the sacrificial layer is positioned between the vibrating diaphragm and the back plate and positioned outside the vibrating gap;
the insulating layer is positioned between the vibrating diaphragm and the edge part of the substrate;
at least one of the electrodes is electrically connected with the back plate, and at least one of the electrodes is electrically connected with the vibrating diaphragm through part of the back plate;
the back plate is also provided with a plurality of through holes which are arranged at intervals and penetrate through the back plate along the vertical direction.
6. The MEMS microphone chip of claim 5, wherein:
the shape of the vibrating diaphragm is a centrosymmetric pattern, and the vibrating diaphragm is made of a flexible conductive film with tensile stress;
the back plate is a rigid conductive film, and the conductive film is a doped polycrystalline silicon layer attached to the upper part/lower part of silicon nitride or a metal layer attached to the upper part/lower part of the silicon nitride;
a contact hole is formed in the sacrificial layer, part of the back plate extends to the vibrating diaphragm through the surface of the contact hole, and the cross section of the contact hole is in one of a rectangular shape, a trapezoidal shape and an inverted trapezoidal shape;
the cross-sectional shapes of the back cavity and the vibration gap are one of a rectangle, a trapezoid and an inverted trapezoid.
The manufacturing method of the MEMS microphone chip is characterized by comprising the following steps: the method comprises the following steps:
s1: providing a substrate, and forming an insulating layer on the substrate;
s2: forming a vibrating diaphragm with a step-shaped air escape valve on the insulating layer;
s3: forming a sacrificial layer on the vibrating diaphragm, and partially etching a contact hole;
s4: forming a back plate on the sacrificial layer, etching a plurality of through holes locally, and connecting part of the back plate with the vibrating diaphragm through the contact holes;
s5: forming an electrode on the back plate;
s6: and forming a back cavity inwards on the lower surface of the substrate, releasing part of the sacrificial layer to form a vibration gap, and finishing the manufacture of the MEMS microphone chip.
8. The method of manufacturing a MEMS microphone chip according to claim 7, wherein:
in S2, the method for forming a diaphragm with a stepped release valve specifically includes the following steps:
s2-1: forming a first material layer on the vibrating diaphragm, and locally etching a first groove;
s2-2: forming a first transition layer on the first groove and the partial surface of the first material layer close to the first groove;
s2-3: and forming a second material layer on the surfaces of the first material layer and the first transition layer, and locally etching a second groove on the second material layer.
9. The method of manufacturing a MEMS microphone chip according to claim 8, wherein:
and repeating S2-2 to S2-3 to form the air escape valve with a plurality of step-shaped platforms.
10. The method of manufacturing a MEMS microphone chip according to claim 8, wherein:
in S1, the substrate is a semiconductor substrate with two polished sides, and the semiconductor substrate is one of a silicon substrate, a germanium substrate and a silicon carbide substrate; the insulating layer is made of silicon oxide;
in S2, the diaphragm, the first material layer, and the second material layer are made of a flexible conductive film having a tensile stress, the flexible conductive film is doped polysilicon, and the first transition layer is made of silicon oxide;
in S3, the sacrificial layer is made of silicon oxide, and the cross-sectional shape of the contact hole is one of rectangular, trapezoidal, and inverted trapezoidal;
in S4, the back plate is a rigid conductive film, and the conductive film is a doped polysilicon layer or a metal layer attached to the upper/lower portion of silicon nitride; the shape of the through hole is one or a combination of a plurality of circular shapes, polygonal shapes and flower shapes;
s5, the electrode is made of one or more of titanium, tungsten, chromium, platinum, aluminum and gold;
in S6, the cross-sectional shapes of the back cavity and the vibration gap are one of a rectangle, a trapezoid, and an inverted trapezoid.
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| US20220256292A1 (en) * | 2021-02-11 | 2022-08-11 | Knowles Electronics, Llc | Mems die with a diaphragm having a stepped or tapered passage for ingress protection |
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| US20190028814A1 (en) * | 2017-05-15 | 2019-01-24 | Goertek Inc. | Mems microphone |
| CN212259332U (en) * | 2020-05-19 | 2020-12-29 | 苏州敏芯微电子技术股份有限公司 | Vibrating diaphragm and micro-electro-mechanical system microphone |
| CN112383871A (en) * | 2021-01-15 | 2021-02-19 | 中芯集成电路制造(绍兴)有限公司 | Microphone component and manufacturing method thereof |
| CN112672262A (en) * | 2021-03-16 | 2021-04-16 | 山东新港电子科技有限公司 | MEMS chip with double-back-plate structure, manufacturing method thereof and MEMS microphone |
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| US20190028814A1 (en) * | 2017-05-15 | 2019-01-24 | Goertek Inc. | Mems microphone |
| CN212259332U (en) * | 2020-05-19 | 2020-12-29 | 苏州敏芯微电子技术股份有限公司 | Vibrating diaphragm and micro-electro-mechanical system microphone |
| CN112383871A (en) * | 2021-01-15 | 2021-02-19 | 中芯集成电路制造(绍兴)有限公司 | Microphone component and manufacturing method thereof |
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| US20220256292A1 (en) * | 2021-02-11 | 2022-08-11 | Knowles Electronics, Llc | Mems die with a diaphragm having a stepped or tapered passage for ingress protection |
| US11716578B2 (en) * | 2021-02-11 | 2023-08-01 | Knowles Electronics, Llc | MEMS die with a diaphragm having a stepped or tapered passage for ingress protection |
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