CN116996822A - MEMS transducer and method of manufacturing the same - Google Patents
MEMS transducer and method of manufacturing the same Download PDFInfo
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- CN116996822A CN116996822A CN202210437624.4A CN202210437624A CN116996822A CN 116996822 A CN116996822 A CN 116996822A CN 202210437624 A CN202210437624 A CN 202210437624A CN 116996822 A CN116996822 A CN 116996822A
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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
- H04R19/04—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
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R7/00—Diaphragms for electromechanical transducers; Cones
- H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
- H04R7/04—Plane diaphragms
- H04R7/06—Plane diaphragms comprising a plurality of sections or layers
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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
- H04R7/00—Diaphragms for electromechanical transducers; Cones
- H04R7/16—Mounting or tensioning of diaphragms or cones
- H04R7/18—Mounting or tensioning of diaphragms or cones at the periphery
-
- 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
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2231/00—Details of apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor covered by H04R31/00, not provided for in its subgroups
- H04R2231/001—Moulding aspects of diaphragm or surround
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2231/00—Details of apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor covered by H04R31/00, not provided for in its subgroups
- H04R2231/003—Manufacturing aspects of the outer suspension of loudspeaker or microphone diaphragms or of their connecting aspects to said diaphragms
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Multimedia (AREA)
- Manufacturing & Machinery (AREA)
- Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
Abstract
The present invention relates to a MEMS transducer and a method of manufacturing the same, the MEMS transducer comprising: a vibrating diaphragm; the support structure is arranged opposite to the vibrating diaphragm and comprises a first conductive material; the connecting structure comprises a second conductive material and is used for realizing the mechanical and electrical connection between the vibrating diaphragm and the supporting structure; the backboard is arranged opposite to the vibrating diaphragm, and the backboard is not connected with the supporting structure, so that insulation and stress isolation between the backboard and the supporting structure are realized; the first electrode is arranged on the supporting structure and is electrically connected with the vibrating diaphragm through the supporting structure and the connecting structure; the second electrode is arranged on the backboard and is electrically connected with the backboard; the periphery of the vibrating diaphragm is provided with a gap belt, so that the vertical vibration of the vibrating diaphragm is not limited due to the fact that other structures are connected around the vibrating diaphragm. The change of the capacitance signal is more linear when the vibrating diaphragm vibrates, and the total harmonic distortion of the transducer can be reduced. And the edge area of the vibrating diaphragm is effectively utilized to vibrate, parasitic capacitance is reduced, and the sensitivity and the signal-to-noise ratio of the transducer can be improved.
Description
Technical Field
The invention relates to the technical field of semiconductor devices, in particular to an MEMS transducer and a manufacturing method of the MEMS transducer.
Background
Microelectromechanical systems (Micro-Electro-Mechanical System, MEMS) devices are typically produced using integrated circuit fabrication techniques. A transducer is a device capable of converting electric energy and acoustic energy into each other, and a microphone is a common transducer. The silicon-based microphone has wide application prospect in the fields of hearing aids, mobile communication equipment and the like. MEMS microphone chips have been studied for over 20 years, during which many types of microphone chips have been developed, among which there are piezoresistive, piezoelectric, capacitive, etc., and capacitive MEMS microphones are most widely used.
The diaphragm of the exemplary capacitive MEMS microphone is fixed around, and when sound pressure acts on the diaphragm, the diaphragm deforms in an arc shape, that is, the central area of the diaphragm deforms more (closer or farther from the back plate), and the edge area deforms less, so that the linearity of the microphone output of the diaphragm structure is poor.
Disclosure of Invention
Based on this, it is necessary to provide a MEMS transducer having a good linearity and a method of manufacturing the same.
A MEMS transducer comprising: a vibrating diaphragm; the support structure is arranged opposite to the vibrating diaphragm and comprises a first conductive material; the connecting structure comprises a second conductive material and is used for realizing mechanical connection and electrical connection between the vibrating diaphragm and the supporting structure; the backboard is arranged opposite to the vibrating diaphragm, the backboard is not connected with the supporting structure so as to realize insulation and stress isolation with the supporting structure, and a cavity is formed between the backboard and the vibrating diaphragm; the first electrode is arranged on the supporting structure and is electrically connected with the vibrating diaphragm through the supporting structure and the connecting structure; the second electrode is arranged on the backboard and is electrically connected with the backboard; the first electrode and the second electrode are used for transmitting capacitance signals formed between the vibrating diaphragm and the backboard; the periphery of the vibrating diaphragm is provided with a gap belt, so that the vertical vibration of the vibrating diaphragm is not limited by structures other than the vibrating diaphragm which are connected with the periphery of the vibrating diaphragm.
Above-mentioned MEMS transducer, the space area is around the vibrating diaphragm, and consequently the vertical vibration of vibrating diaphragm can not be fixed by the structure of being connected all around, and the vibrating diaphragm is the same in the middle of no matter when vibrating or distance between marginal area and the backplate, therefore the capacitance signal change has more linearity when vibrating the vibrating diaphragm, can reduce the total harmonic distortion of transducer. And because the edge area of the vibrating diaphragm can not be fixed by the structures connected around, the edge area of the vibrating diaphragm is effectively utilized to vibrate, parasitic capacitance is reduced, the sensitivity and the signal-to-noise ratio of the transducer can be improved, and the product performance is improved. And because the MEMS transducer reduces the total harmonic distortion, a functional module for reducing the total harmonic distortion is not required to be additionally arranged in an ASIC (Application Specific Integrated Circuit ), the complexity of circuit design can be reduced, and the cost is effectively reduced.
In one embodiment, the back plate is formed with an acoustic port extending through the back plate and communicating to the cavity.
In one embodiment, the MEMS transducer is a capacitive MEMS microphone that further includes a substrate and a back cavity formed in the substrate.
In one embodiment, the diaphragm is positioned above the backplate and support structure.
The back cavity is sequentially communicated with the sound hole, the cavity and the gap belt.
In one embodiment, the MEMS transducer further comprises a support layer, the backplate and support structure being located above the diaphragm, the support layer being for supporting the backplate and support structure.
In one embodiment, the back cavity communicates sequentially with the void band, cavity, and acoustic hole.
In one embodiment, the connecting structure is connected to the diaphragm at a position located at the center of the diaphragm.
In one embodiment, the support structure comprises a first support beam extending from one side of the orthographic projection of the diaphragm onto the backplate to the other side of the orthographic projection, the first support beam being connected to the first electrode and the connection structure.
In one embodiment, the diaphragm is a circular thin film.
In one embodiment, the support structure and the back plate are the same layer of film, separated by a void space between the back plate and the support structure.
In one embodiment, the MEMS transducer further comprises a substrate, and an insulating layer on the substrate, wherein the diaphragm is disposed on the insulating layer, or the back plate and the support structure are disposed on the insulating layer.
In one embodiment, the back plate is provided with a plurality of anti-adhesion structures on one surface facing the vibrating diaphragm.
In one of the embodiments, the support structure has elasticity so that it can follow the vibration of the diaphragm under the influence of sound pressure.
A method of manufacturing a MEMS transducer, comprising: obtaining a substrate with a first sacrificial layer formed on a first surface; the first sacrificial layer is made of insulating materials; forming a vibrating diaphragm on the first sacrificial layer and a gap belt positioned around the vibrating diaphragm; forming a second sacrificial layer on the diaphragm; the second sacrificial layer is made of insulating materials; patterning the second sacrificial layer to form a connecting structure hole with the bottom extending to the vibrating diaphragm; the shape of the connecting structure hole is the same as that of the connecting structure; depositing a conductive material in the connection structure hole and on the second sacrificial layer; patterning the conductive material to form the connection structure, the back plate, the support structure, a void between the back plate and the support structure, and an acoustic hole through the back plate; the gap groove is used for realizing insulation and stress isolation between the backboard and the supporting structure; forming a first electrode and a second electrode; the first electrode is formed on the supporting structure, the first electrode is electrically connected with the vibrating diaphragm through the supporting structure and the connecting structure, the second electrode is formed on the backboard, and the second electrode is electrically connected with the backboard; patterning the substrate to form a back cavity; etching the first sacrificial layer and the second sacrificial layer, removing the second sacrificial layer between the back plate and the vibrating diaphragm and between the supporting structure and the vibrating diaphragm to form a cavity, removing the first sacrificial layer below the vibrating diaphragm and below the gap band, and taking the rest of the second sacrificial layer as a supporting layer for supporting the back plate and the supporting structure.
A method of manufacturing a MEMS transducer, comprising: obtaining a substrate with a first sacrificial layer formed on a first surface; the first sacrificial layer is made of insulating materials; forming a conductive layer on the first sacrificial layer; patterning the conductive layer to form a back plate, a support structure, a void groove between the back plate and the support structure, and an acoustic hole penetrating through the back plate; the gap groove is used for realizing insulation and stress isolation between the backboard and the supporting structure; forming a second sacrificial layer over the backplate and support structure; the second sacrificial layer is made of insulating materials; patterning the second sacrificial layer to form a connecting structure hole with the bottom extending to the supporting structure, a first electrode hole with the bottom extending to the supporting structure and a second electrode hole with the bottom extending to the backboard; the shape of the connecting structure hole is the same as that of the connecting structure; depositing a conductive material in the connection structure hole and on the second sacrificial layer; patterning the conductive material to form a vibrating diaphragm, the connecting structure and a gap belt positioned around the vibrating diaphragm; forming a first electrode in the first electrode hole, and forming a second electrode in the second electrode hole; the first electrode is electrically connected with the vibrating diaphragm through the supporting structure and the connecting structure, and the second electrode is electrically connected with the backboard; patterning the substrate to form a back cavity; and corroding the first sacrificial layer and the second sacrificial layer, removing the first sacrificial layer between the back plate and the back cavity and between the supporting structure and the back cavity, removing the second sacrificial layer between the back plate and the vibrating diaphragm and between the supporting structure and the vibrating diaphragm to form a cavity, and taking the rest of the second sacrificial layer as a supporting layer for supporting the vibrating diaphragm.
According to the manufacturing method of the MEMS transducer, the gap strips are formed around the vibrating diaphragm, so that the vertical vibration of the vibrating diaphragm cannot be fixed by the structures connected around, the distance between the middle area and the back plate and the distance between the edge area and the back plate are the same when the vibrating diaphragm vibrates, the capacitance signal change is more linear when the vibrating diaphragm vibrates, and the total harmonic distortion of the transducer can be reduced. And because the edge area of the vibrating diaphragm can not be fixed by the structures connected around, the edge area of the vibrating diaphragm is effectively utilized to vibrate, parasitic capacitance is reduced, the sensitivity and the signal-to-noise ratio of the transducer can be improved, and the product performance is improved. And the MEMS transducer obtained by the manufacturing method of the MEMS transducer reduces the total harmonic distortion, and a functional module for reducing the total harmonic distortion is not required to be additionally arranged in the ASIC, so that the complexity of circuit design can be reduced, and the cost is effectively reduced.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments or the conventional techniques of the present application, the drawings required for the descriptions of the embodiments or the conventional techniques will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to the drawings without inventive effort for those skilled in the art.
FIG. 1 is a schematic diagram illustrating deformation of an exemplary capacitive MEMS microphone when an acoustic pressure is applied to a diaphragm;
FIG. 2 is a cross-sectional view of a MEMS transducer in one embodiment;
FIG. 3 is a top view of a MEMS transducer in one embodiment;
FIG. 4 is a schematic illustration of the structure of FIG. 2 as the diaphragm vibrates;
FIGS. 5a and 5b are schematic structural views of the connection structure in two different embodiments, respectively;
FIG. 6 is a cross-sectional view of a MEMS transducer in another embodiment;
FIG. 7 is a top view of a MEMS transducer in another embodiment;
FIG. 8 is a schematic view of the structure of FIG. 6 when the diaphragm is vibrating;
FIG. 9 is a flow chart of a method of manufacturing a MEMS transducer in one embodiment;
FIG. 10 is a flow chart of a method of manufacturing a MEMS transducer in another embodiment.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
It will be understood that when an element is referred to as being "fixed to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like are used herein for illustrative purposes only. When an element or layer is referred to as being "on," "adjacent," "connected to," or "coupled to" another element or layer, it can be directly on, adjacent, connected, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, a, b, c, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
The terms "comprises," "comprising," and/or "including," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
Embodiments of the invention are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the invention, such that variations of the illustrated shapes due to, for example, manufacturing techniques and/or tolerances are to be expected. Thus, embodiments of the present invention should not be limited to the particular shapes of the regions illustrated herein, but rather include deviations in shapes that result, for example, from manufacturing techniques. For example, an implanted region shown as a rectangle typically has rounded or curved features and/or implant concentration gradients at its edges rather than a binary change from implanted to non-implanted regions. Also, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface over which the implantation is performed. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the invention.
Fig. 1 shows a schematic diagram of deformation of an exemplary capacitive MEMS microphone when sound pressure is applied to a diaphragm. Wherein the broken line is the shape outline of the deformed vibrating diaphragm, it can be seen that the deformation of the central area of the vibrating diaphragm is larger (closer to the backboard) and the deformation of the edge area is smaller because the supporting layers around and around the vibrating diaphragm are rigidly connected. The linearity of the microphone output of the vibrating diaphragm structure is poor; in addition, the deformation amount of the vibrating diaphragm in the edge area is small, so that the vibrating diaphragm is not effectively utilized, and the sensitivity of the microphone is low.
FIG. 2 is a cross-sectional view of a MEMS transducer in one embodiment, and FIG. 3 is a top view of the MEMS transducer in one embodiment. The MEMS transducer of fig. 2 and 3 is a capacitive MEMS microphone, and includes a diaphragm 132, a backplate 150, a support structure 152, a connection structure 156, a first electrode 162, and a second electrode 164. The diaphragm 132 is disposed opposite to the back plate 150, and a cavity is formed between the back plate 150 and the diaphragm 132. In the embodiment shown in fig. 2 and 3, the diaphragm 132 is disposed below the backplate 150. The support structure 152 is also disposed opposite the diaphragm 132, the diaphragm 132 being connected to the support structure 152 by a connection structure 156. Moreover, the diaphragm 132, the connection structure 156 and the support structure 152 all include conductive materials, such that the diaphragm 132 is electrically connected to the support structure 152 through the connection structure 156. The diaphragm 132, the connection structure 156, and the support structure 152 may be a composite film layer made of a conductive material and a nonconductive material, or may be a film layer made of a conductive material alone. The periphery of the diaphragm 132 is formed with a gap band 131, so that the vertical vibration of the diaphragm 132 is not limited by the connection of other structures around the diaphragm. The vertical vibration of the diaphragm 132 may be in a direction toward or away from the cavity. The back plate 150 is not connected to the support structure 152, thereby providing insulation and stress isolation between the back plate 150 and the support structure 152. In the embodiment shown in fig. 3, the back plate 150 is separated from the support structure 152 by a void slot 153. The first electrode 162 is disposed on the supporting structure 152, and in fig. 2 and 3 is disposed on an upper surface of the supporting structure 152, and the first electrode 162 is electrically connected to the diaphragm 132 through the supporting structure 152 and the connecting structure 156. The second electrode 164 is disposed on the back plate 150, and in fig. 2 and 3 is disposed on the upper surface of the back plate 150 and electrically connected to the back plate 150. The first electrode 162 and the second electrode 164 are used for transmitting capacitance signals formed between the diaphragm 132 and the backplate 150.
In the MEMS transducer, the gap strips 131 are formed around the diaphragm 132, so that the vertical vibration of the diaphragm 132 is not fixed by the structure connected around, referring to fig. 4 (the structure bent upwards in fig. 4 is the supporting structure 152), the distance between the middle or edge area of the diaphragm 132 and the back plate 150 is the same during vibration, and therefore the capacitance signal variation is more linear during vibration of the diaphragm 132, and the total harmonic distortion of the transducer can be reduced. And because the edge area of the vibrating diaphragm 132 can not be fixed by the structure connected around, the edge area of the vibrating diaphragm 132 is effectively utilized to vibrate, parasitic capacitance is reduced, the sensitivity and the signal-to-noise ratio of the transducer can be improved, and the product performance is improved. And because the MEMS transducer reduces the total harmonic distortion, a functional module for reducing the total harmonic distortion is not required to be additionally arranged in an ASIC (Application Specific Integrated Circuit ), the complexity of circuit design can be reduced, and the cost is effectively reduced.
In the embodiment shown in fig. 2 and 3, the back plate 150 and the support structure 152 are provided on the support layer 140, and the support layer 140 is used to support the back plate 150 and the support structure 152. In one embodiment of the present application, the support layer 140 is a structure of the MEMS transducer that remains after the sacrificial layer is released during the fabrication, and is made of an insulating material, specifically, a silicon oxide material, such as silicon dioxide.
In the embodiment shown in fig. 2 and 3, the connection structure 156 is connected to the diaphragm 132 at a position at the center of the diaphragm. In the embodiment shown in fig. 2, the connection structure 156 is a single connection post. In other embodiments, the connection structure 156 may be configured in other shapes. Fig. 5a and 5b are schematic structural views of the connecting structure 156 in two different embodiments, respectively. In the embodiment shown in fig. 5a, the connection structure 156 is inclined, similar to a tripod structure, and the common end of each inclined column is disposed on the support structure 152, and the other end of each inclined column is distributed around the center of the diaphragm. The connecting structure 156 can improve the structural strength of the diaphragm 132, so that the diaphragm 132 is smoother, and the linearity of capacitance change is better, but the manufacturing difficulty is required to be considered in actual production. In the embodiment shown in fig. 5b, the connection structure 156 consists of at least two thinner connection posts located near the center of the diaphragm.
The support structure 152 may include at least one beam structure. Referring to fig. 3, in this embodiment, the support structure 152 includes a first support beam connected to the first electrode 162 and the connection structure 156, the first support beam extending from one side of the orthographic projection of the diaphragm 132 onto the backplate 150 to the other side of the orthographic projection. The middle part of the first supporting beam is suspended above the cavity, and both ends of the first supporting beam are arranged on the supporting layer 140.
In the embodiment shown in fig. 3, the back plate 150 is provided with a plurality of anti-adhesion structures 158 on a side facing the diaphragm 132. Referring to fig. 4, the back plate may remain motionless while the diaphragm vibrates, and thus the diaphragm may move toward the back plate while vibrating. The anti-adhesion structure 158 may serve to prevent adhesion between the backplate 150 and the diaphragm 132. In the embodiment shown in fig. 3, the anti-adhesion structure 158 is a protrusion toward the diaphragm 132.
In one embodiment of the present application, the backplate 150 is formed with an acoustic hole 151 that extends through the backplate 150 and communicates to the cavity between the backplate 150 and the diaphragm 132, and sound waves can be conducted through the acoustic hole 151 to the diaphragm 132. The acoustic port 151 may have one or more. In one embodiment of the application, the acoustic holes 151 are evenly distributed over the backplate 150; in other embodiments, the acoustic holes 151 may also be unevenly distributed. In one embodiment of the application, the support structure 152 is also provided with acoustic holes 151 extending through the support structure 152. Acoustic holes 151 are formed in both the backplate 150 and the support structure 152 to facilitate sacrificial release of the sacrificial material to ensure formation of the cavity.
In one embodiment of the application, diaphragm 132 is a circular membrane; in other embodiments, the diaphragm 132 may have other shapes, such as square, diamond, star, irregular, etc.
In one embodiment of the present application, the diaphragm 132 is made of polysilicon. In one embodiment of the application, the diaphragm 132 may be a flexible film or a rigid film.
In one embodiment of the present application, the support structure 152 is the same film layer as the back plate 150, separated by a void space 153 between the back plate 150 and the support structure 152. Although the supporting structure 152 is made of the same material as the back plate 150 and is made of a rigid material, the supporting structure 152 still has elasticity due to the thin structural beams of the supporting structure 152, and the sound pressure can make the diaphragm 132 drive the supporting structure 152 to vibrate.
In one embodiment of the present application, the first electrode 162 and the second electrode 164 are made of conductive metal, and are used for wire bonding, and are electrically connected to an ASIC (Application Specific Integrated Circuit ) or a Printed Circuit Board (PCB) through wire bonding.
In the embodiment shown in fig. 2 and 3, the MEMS transducer is alsoIncluding a substrate 110 and a back cavity 111 formed in the substrate 110. The back cavity 111 is in turn connected to the void band 131, the cavity (between the backplate 150 and the diaphragm 132) and the acoustic hole 151. In one embodiment of the present application, the material of the substrate 110 is Si; in other embodiments, the material of the substrate 110 may also be other semiconductors or semiconductor compounds, such as Ge, siGe, siC, siO 2 Or Si (or) 3 N 4 One of them.
In the embodiment shown in fig. 2 and 3, an insulating layer 120 is further provided on the substrate 110. The material of the insulating layer 120 may be silicon oxide, such as silicon dioxide. A conductive layer 134 is further formed between the insulating layer 120 and the supporting layer 140, and the conductive layer 134 and the diaphragm 132 are the same layer, so that the manufacturing process can be simplified. The conductive layer 134 is separated from the diaphragm 132 by a gap band 131.
In the embodiment shown in fig. 2 and 3, the outer 360 degrees of the diaphragm 132 are the gap strips 131, and it is also understood that the diaphragm 132 is suspended between the cavity and the back cavity 111 by the connection structure 156 and the support structure 152. In other embodiments, the gap band 131 may not be 360 degrees, i.e., the diaphragm 132 may be adhered to the outer conductive layer 134 by a small amount, and the diaphragm 132 may be able to move in the vertical direction with respect to the conductive layer 134. It is also understood that the diaphragm 132 is suspended between the cavity and the back cavity 111 by a small amount of adhesion between the diaphragm 132 and the outer conductive layer 134, and by the connection structure 156 and the support structure 152.
Fig. 6 is a cross-sectional view of a MEMS transducer in another embodiment, and fig. 7 is a top view of the MEMS transducer in another embodiment.
The MEMS transducer of fig. 6 and 7 is a capacitive MEMS microphone, comprising a diaphragm 232, a backplate 250, a support structure 252, a connection structure 256, a first electrode 262, and a second electrode 264. The diaphragm 232 is disposed opposite the backplate 250, and a cavity is formed between the backplate 250 and the diaphragm 232. In the embodiment shown in fig. 6 and 7, the diaphragm 232 is disposed over the backplate 250. The support structure 252 is also disposed opposite the diaphragm 232, the diaphragm 232 being connected to the support structure 252 by a connection structure 256. And the diaphragm 232, the connection structure 256 and the support structure 252 all comprise conductive materials, such that the diaphragm 232 is electrically connected to the support structure 252 through the connection structure 256. The diaphragm 232, the connection structure 256, and the support structure 252 may be a composite film layer made of a conductive material and a nonconductive material, or may be a film layer made of a conductive material alone. The periphery of the diaphragm 232 is formed with a gap band 231 so that the vertical vibration of the diaphragm 232 is not limited by the connection of other structures around the diaphragm. The back plate 250 is not connected to the support structure 252, thereby providing insulation and stress isolation of the back plate 250 from the support structure 252. In the embodiment shown in fig. 3, the back plate 250 is separated from the support structure 252 by a void groove 253. The first electrode 262 is disposed on the support structure 252, and in fig. 6 and 7 is disposed on an upper surface of the support structure 252, and the first electrode 262 is electrically connected to the diaphragm 232 through the support structure 252 and the connection structure 256. The second electrode 264 is disposed on the back plate 250, and in fig. 6 and 7 is disposed on the upper surface of the back plate 250 and electrically connected to the back plate 250. The first electrode 262 and the second electrode 264 are used to transmit capacitive signals formed between the diaphragm 232 and the backplate 250.
In the MEMS transducer, the space band 231 is formed around the diaphragm 232, so that the vertical vibration of the diaphragm 232 is not fixed by the structure connected around, referring to fig. 8 (the structure bent upwards in fig. 8 is the support structure 252), the distance between the middle or edge area of the diaphragm 232 and the back plate 250 is the same during vibration, and therefore the capacitance signal variation is more linear during vibration of the diaphragm 232, and the total harmonic distortion of the transducer can be reduced. And because the edge area of the vibrating diaphragm 232 can not be fixed by the structures connected around, the edge area of the vibrating diaphragm 232 is effectively utilized to vibrate, parasitic capacitance is reduced, the sensitivity and the signal to noise ratio of the transducer can be improved, and the product performance is improved.
In the embodiment shown in fig. 6 and 7, the location where the connection structure 256 is connected to the diaphragm 232 is located in the center of the diaphragm.
The support structure 252 may include at least one beam structure. Referring to fig. 7, in this embodiment, the support structure 252 includes a first support beam connected to the first electrode 262 and the connection structure 256, the first support beam extending from one side of the orthographic projection of the diaphragm 232 onto the backplate 250 to the other side of the orthographic projection.
In the embodiment shown in fig. 6, the diaphragm 232 has a plurality of anti-adhesion structures 238 on a side facing the backplate 250. Referring to fig. 8, the back plate may remain motionless while the diaphragm vibrates, and thus the diaphragm may move toward the back plate while vibrating. The provision of the anti-adhesion mechanism 238 may serve to prevent adhesion of the backplate 250 to the diaphragm 232. In the embodiment shown in fig. 6, the anti-adhesion structure 238 is a protrusion toward the back plate 250.
In one embodiment of the present application, the backplate 250 is formed with an acoustic hole 251 that extends through the backplate 250 and communicates to the cavity between the backplate 250 and the diaphragm 232, through which acoustic waves can be conducted to the diaphragm 232. The acoustic port 251 may have one or more. In one embodiment of the application, the acoustic holes 251 are evenly distributed over the backplate 250; in other embodiments, the acoustic holes 251 may also be unevenly distributed. In one embodiment of the application, the support structure 252 is also provided with acoustic holes 251 extending through the support structure 252. Acoustic holes 251 are formed in both the back plate 250 and the support structure 252 to facilitate sacrificial release of the sacrificial material, ensuring the formation of the cavity.
In one embodiment of the application, diaphragm 232 is a circular thin film; in other embodiments, the diaphragm 232 may have other shapes, such as square, diamond, star, irregular, etc.
In one embodiment of the present application, the diaphragm 232 is made of polysilicon.
In one embodiment of the application, the support structure 252 is the same film layer as the back plate 250, separated by a void space 253 between the back plate 250 and the support structure 252. Although the supporting structure 252 is made of the same material as the back plate 250 and is made of a rigid material, the supporting structure 252 still has elasticity due to the thin structural beams of the supporting structure 252, and the vibration membrane 232 can be driven to vibrate by the sound pressure.
In the embodiment shown in fig. 6 and 7, the MEMS transducer further comprises a substrate 210 and a back cavity 211 formed in the substrate 210. The back cavity 211 communicates sequentially with the acoustic port 251, the cavity (between the backplate 250 and the diaphragm 232) and the interstitial band 231. In one embodiment of the present application, the material of the substrate 210 is Si; in other embodiments, the material of the substrate 210 may also be other semiconductors orCompounds of semiconductors, e.g. Ge, siGe, siC, siO 2 Or Si (or) 3 N 4 One of them.
In the embodiment shown in fig. 6 and 7, an insulating layer 220 is further provided on the substrate 210. The material of the insulating layer 220 may be a silicon oxide material, such as silicon dioxide. The back plate 250 and the support structure 252 are disposed on the insulating layer 220. The back plate 250 also has a support layer 240 formed thereon. In one embodiment of the present application, the support layer 240 is a structure of the MEMS transducer that remains after the sacrificial layer is released during fabrication, and is made of an insulating material, specifically, silicon oxide, such as silicon dioxide. The support layer 240 is also formed with a conductive layer 234. The conductive layer 234 is the same layer as the diaphragm 232 and is separated from the diaphragm 232 by a gap band 231 between the conductive layer 234 and the diaphragm 232. In one embodiment of the application, conductive layer 234 is the structure that is etched and left over by diaphragm 232.
The application correspondingly provides a manufacturing method of the MEMS transducer. FIG. 9 is a flow chart of a method of manufacturing a MEMS transducer in an embodiment that may be used to manufacture the MEMS transducer shown in FIGS. 2 and 3, comprising the steps of:
s110, obtaining a substrate with a first sacrificial layer formed on the first surface.
In one embodiment of the application, the material of the substrate is Si; in other embodiments, the substrate material may also be other semiconductors or semiconductor compounds, such as Ge, siGe, siC, siO 2 Or Si (or) 3 N 4 One of them. The first sacrificial layer is made of an insulating material, and may be specifically silicon oxide, for example, silicon dioxide. The first sacrificial layer may be formed by thermal oxidation.
S120, forming a vibrating diaphragm and a gap band around the vibrating diaphragm on the first sacrificial layer.
In one embodiment of the application, a conductive material is deposited on the first sacrificial layer and then patterned to form a diaphragm and a band of voids around the diaphragm. In one embodiment of the application, polysilicon is deposited on the first sacrificial layer and then lithographically and etched to form the diaphragm and the band of voids around the diaphragm.
S130, forming a second sacrificial layer on the diaphragm.
The second sacrificial layer is made of insulating material, and can be silicon oxide, such as silicon dioxide. In one embodiment of the application, silicon dioxide may be deposited as a second sacrificial layer on the diaphragm by a Chemical Vapor Deposition (CVD) process.
And S140, patterning the second sacrificial layer to form a connecting structure hole with the bottom extending to the vibrating diaphragm.
The shape of the connecting structure hole is the same as that of a connecting structure to be formed later. In one embodiment of the application, the connection structure holes are formed by photolithography and etching.
And S150, depositing conductive materials in the connecting structure holes and on the second sacrificial layer.
A conductive material is deposited as a back plate that fills the connection structure holes. In one embodiment of the application, the conductive material is rigid polysilicon. The softness of the polysilicon can be adjusted by adjusting the stress of the polysilicon film, the main methods for adjusting the stress are adjusting the temperature, pressure and the like of polysilicon deposition, and the stress can be adjusted by ion implantation of the polysilicon after the polysilicon deposition and annealing of the deposited polysilicon.
S160, patterning the conductive material to form a connecting structure, a back plate, a supporting structure, a gap groove and an acoustic hole.
Patterning the conductive material deposited in step S150, the remaining conductive material forming a connection structure, a back plate, a support structure, a void slot between the back plate and the support structure, and an acoustic hole through the back plate. The void slots are used to provide insulation and stress isolation between the back plate and the support structure. The acoustic holes may have one or more. In one embodiment of the application, the sound holes are evenly distributed on the back plate; in other embodiments, the acoustic holes may also be unevenly distributed. In other embodiments, the support structure is also provided with acoustic holes through the support structure.
And S170, forming a first electrode and a second electrode.
The first electrode is formed on the supporting structure and is electrically connected with the vibrating diaphragm through the supporting structure and the connecting structure; the second electrode is formed on the backboard and is electrically connected with the backboard. In one embodiment of the application, the first and second electrodes are formed by depositing a conductive metal on the backplate and the support structure, and then patterning (e.g., by photolithography and etching) the conductive metal.
S180, patterning the substrate to form a back cavity.
In one embodiment of the application, the back cavity is formed by back side lithography and etching of the substrate. The first sacrificial layer is used as an etching stop layer for back cavity etching. The substrate may also be thinned prior to back side lithography.
S190, releasing the sacrificial layer.
And corroding the first sacrificial layer and the second sacrificial layer to remove the first sacrificial layer below the vibrating diaphragm and below the gap belt, so that the second sacrificial layers between the back plate and the vibrating diaphragm and between the supporting structure and the vibrating diaphragm are removed to form cavities, and the rest of the second sacrificial layers are used as supporting layers for supporting the back plate and the supporting structure. The acoustic holes act as transmission channels for the corrosive agents when released by the sacrificial layer.
According to the manufacturing method of the MEMS transducer, the gap strips are formed around the vibrating diaphragm, so that the vertical vibration of the vibrating diaphragm cannot be fixed by the structures connected around, the distance between the middle area and the back plate and the distance between the edge area and the back plate are the same when the vibrating diaphragm vibrates, the capacitance signal change is more linear when the vibrating diaphragm vibrates, and the total harmonic distortion of the transducer can be reduced. And because the edge area of the vibrating diaphragm can not be fixed by the structures connected around, the edge area of the vibrating diaphragm is effectively utilized to vibrate, parasitic capacitance is reduced, the sensitivity and the signal-to-noise ratio of the transducer can be improved, and the product performance is improved. And the MEMS transducer obtained by the manufacturing method reduces the total harmonic distortion, and a functional module for reducing the total harmonic distortion is not required to be additionally arranged in the ASIC, so that the complexity of circuit design can be reduced, and the cost is effectively reduced.
FIG. 10 is a flow chart of a method of manufacturing a MEMS transducer in another embodiment that may be used to manufacture the MEMS transducer of FIGS. 6 and 7, comprising the steps of:
s210, obtaining a substrate with a first sacrificial layer formed on the first surface.
In one embodiment of the application, the material of the substrate is Si; in other embodiments, the substrate material may also be other semiconductors or semiconductor compounds, such as Ge, siGe, siC, siO 2 Or Si (or) 3 N 4 One of them. The first sacrificial layer is made of an insulating material, and may be specifically silicon oxide, for example, silicon dioxide. The first sacrificial layer may be formed by thermal oxidation.
S220, forming a conductive layer on the first sacrificial layer.
In one embodiment of the application, a conductive material is deposited on the first sacrificial layer to form a conductive layer. In one embodiment of the application, the conductive material is rigid polysilicon.
And S230, patterning the conductive layer to form a backboard, a supporting structure, a gap groove and an acoustic hole.
Patterning the conductive layer, the remaining conductive layer forming the back plate and the support structure, and simultaneously forming a void between the back plate and the support structure, and an acoustic hole through the back plate. The void slots are used to provide insulation and stress isolation between the back plate and the support structure. The acoustic holes may have one or more. In one embodiment of the application, the sound holes are evenly distributed on the back plate; in other embodiments, the acoustic holes may also be unevenly distributed. In other embodiments, the support structure is also provided with acoustic holes through the support structure.
And S240, forming a second sacrificial layer on the backboard and the support structure.
The second sacrificial layer is made of insulating material, and can be silicon oxide, such as silicon dioxide. In one embodiment of the application, silicon dioxide may be deposited as a second sacrificial layer on the diaphragm by a Chemical Vapor Deposition (CVD) process.
S250, patterning the second sacrificial layer to form a connecting structure hole, a first electrode hole and a second electrode hole.
The connection structure holes whose bottoms extend to the support structure, the first electrode holes whose bottoms extend to the support structure, and the second electrode holes whose bottoms extend to the back plate may be formed by photolithography and etching. The shape of the connecting structure hole is the same as that of a connecting structure to be formed later.
And S260, depositing conductive materials in the connecting structure holes and on the second sacrificial layer.
In one embodiment of the application, polysilicon is deposited as a conductive material to fill the connection structure holes; the cross-sectional area of the first electrode hole and the second electrode hole is larger than that of the connecting structure hole, and polysilicon is filled into the first electrode hole and the second electrode hole.
S270, patterning the conductive material to form a vibrating diaphragm, a connecting structure and a gap belt around the vibrating diaphragm.
And photoetching and etching the conductive material deposited in the step S260 to form a vibrating diaphragm and a gap band around the vibrating diaphragm, and etching and removing the conductive material in the first electrode hole and the second electrode hole.
S280, forming a first electrode and a second electrode.
The first electrode is formed on the supporting structure and is electrically connected with the vibrating diaphragm through the supporting structure and the connecting structure; the second electrode is formed on the backboard and is electrically connected with the backboard. In one embodiment of the application, the first and second electrodes are formed by depositing a conductive metal on the backplate and the support structure, and then patterning (e.g., by photolithography and etching) the conductive metal.
S290, patterning the substrate to form a back cavity.
In one embodiment of the application, the back cavity is formed by back side lithography and etching of the substrate. The first sacrificial layer is used as an etching stop layer for back cavity etching. The substrate may also be thinned prior to back side lithography.
S292, releasing the sacrificial layer.
And corroding the first sacrificial layer and the second sacrificial layer, removing the first sacrificial layer between the back plate and the back cavity and between the supporting structure and the back cavity, removing the second sacrificial layer between the back plate and the vibrating diaphragm and between the supporting structure and the vibrating diaphragm to form a cavity, and taking the rest of the second sacrificial layer as a supporting layer for supporting the vibrating diaphragm. The acoustic holes act as transmission channels for the corrosive agents when released by the sacrificial layer.
According to the manufacturing method of the MEMS transducer, the gap strips are formed around the vibrating diaphragm, so that the vertical vibration of the vibrating diaphragm cannot be fixed by the structures connected around, the distance between the middle area and the back plate and the distance between the edge area and the back plate are the same when the vibrating diaphragm vibrates, the capacitance signal change is more linear when the vibrating diaphragm vibrates, and the total harmonic distortion of the transducer can be reduced. And because the edge area of the vibrating diaphragm can not be fixed by the structures connected around, the edge area of the vibrating diaphragm is effectively utilized to vibrate, parasitic capacitance is reduced, the sensitivity and the signal-to-noise ratio of the transducer can be improved, and the product performance is improved.
It should be understood that, although the steps in the flowcharts of the present application are shown in order as indicated by the arrows, these steps are not necessarily performed in order as indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least a portion of the steps in the flowcharts of this application may include a plurality of steps or stages that are not necessarily performed at the same time but may be performed at different times, the order in which the steps or stages are performed is not necessarily sequential, and may be performed in rotation or alternately with at least a portion of the steps or stages in other steps or others.
In the description of the present specification, reference to the terms "some embodiments," "other embodiments," "desired embodiments," and the like, means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.
The technical features of the above embodiments may be arbitrarily combined, and for brevity, all of the possible combinations of the technical features of the above embodiments are not described, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the claims. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.
Claims (10)
1. A MEMS transducer comprising:
a vibrating diaphragm;
the support structure is arranged opposite to the vibrating diaphragm and comprises a first conductive material;
the connecting structure comprises a second conductive material and is used for realizing mechanical connection and electrical connection between the vibrating diaphragm and the supporting structure;
the backboard is arranged opposite to the vibrating diaphragm, the backboard is not connected with the supporting structure so as to realize insulation and stress isolation with the supporting structure, and a cavity is formed between the backboard and the vibrating diaphragm;
The first electrode is arranged on the supporting structure and is electrically connected with the vibrating diaphragm through the supporting structure and the connecting structure;
the second electrode is arranged on the backboard and is electrically connected with the backboard; the first electrode and the second electrode are used for transmitting capacitance signals formed between the vibrating diaphragm and the backboard;
the periphery of the vibrating diaphragm is provided with a gap belt, so that the vertical vibration of the vibrating diaphragm is not limited by structures other than the vibrating diaphragm which are connected with the periphery of the vibrating diaphragm.
2. The MEMS transducer of claim 1 wherein the diaphragm is located above the backplate and support structure; or (b)
The MEMS transducer further comprises a supporting layer, wherein the back plate and the supporting structure are arranged on the supporting layer, the back plate and the supporting structure are positioned above the vibrating diaphragm, and the supporting layer is used for supporting the back plate and the supporting structure.
3. A MEMS transducer as claimed in claim 1 or 2, wherein the connection structure is connected to the diaphragm at a location centrally located in the diaphragm.
4. A MEMS transducer as claimed in claim 1 or 2, wherein the support structure comprises a first support beam extending from one side of the orthographic projection of the diaphragm onto the backplate to the other side of the orthographic projection, the first support beam being connected to the first electrode and the connection structure.
5. A MEMS transducer as claimed in claim 1 or 2, wherein the support structure is resilient so as to follow the vibration of the diaphragm.
6. A MEMS transducer as claimed in claim 1 or claim 2 wherein the support structure is the same layer of film as the backplate, separated by a void slot between the backplate and support structure.
7. A MEMS transducer as claimed in claim 1 or claim 2 wherein the backplate is formed with an acoustic aperture extending through the backplate and communicating to the cavity.
8. The MEMS transducer of claim 7, wherein the MEMS transducer is a capacitive MEMS microphone further comprising a substrate and a back cavity formed in the substrate, the back cavity in communication with the void band, cavity, and acoustic aperture in sequence or in communication with the acoustic aperture, cavity, and void band in sequence.
9. A method of manufacturing a MEMS transducer, comprising:
obtaining a substrate with a first sacrificial layer formed on a first surface; the first sacrificial layer is made of insulating materials;
forming a vibrating diaphragm on the first sacrificial layer and a gap belt positioned around the vibrating diaphragm;
forming a second sacrificial layer on the diaphragm; the second sacrificial layer is made of insulating materials;
Patterning the second sacrificial layer to form a connecting structure hole with the bottom extending to the vibrating diaphragm; the shape of the connecting structure hole is the same as that of the connecting structure;
depositing a conductive material in the connection structure hole and on the second sacrificial layer;
patterning the conductive material to form the connection structure, the back plate, the support structure, a void between the back plate and the support structure, and an acoustic hole through the back plate; the gap groove is used for realizing insulation and stress isolation between the backboard and the supporting structure;
forming a first electrode and a second electrode; the first electrode is formed on the supporting structure, the first electrode is electrically connected with the vibrating diaphragm through the supporting structure and the connecting structure, the second electrode is formed on the backboard, and the second electrode is electrically connected with the backboard;
patterning the substrate to form a back cavity;
etching the first sacrificial layer and the second sacrificial layer, removing the second sacrificial layer between the back plate and the vibrating diaphragm and between the supporting structure and the vibrating diaphragm to form a cavity, removing the first sacrificial layer below the vibrating diaphragm and below the gap band, and taking the rest of the second sacrificial layer as a supporting layer for supporting the back plate and the supporting structure.
10. A method of manufacturing a MEMS transducer, comprising:
obtaining a substrate with a first sacrificial layer formed on a first surface; the first sacrificial layer is made of insulating materials;
forming a conductive layer on the first sacrificial layer;
patterning the conductive layer to form a back plate, a support structure, a void groove between the back plate and the support structure, and an acoustic hole penetrating through the back plate; the gap groove is used for realizing insulation and stress isolation between the backboard and the supporting structure;
forming a second sacrificial layer over the backplate and support structure; the second sacrificial layer is made of insulating materials;
patterning the second sacrificial layer to form a connecting structure hole with the bottom extending to the supporting structure, a first electrode hole with the bottom extending to the supporting structure and a second electrode hole with the bottom extending to the backboard; the shape of the connecting structure hole is the same as that of the connecting structure;
depositing a conductive material in the connection structure hole and on the second sacrificial layer;
patterning the conductive material to form a vibrating diaphragm, the connecting structure and a gap belt positioned around the vibrating diaphragm;
forming a first electrode in the first electrode hole, and forming a second electrode in the second electrode hole; the first electrode is electrically connected with the vibrating diaphragm through the supporting structure and the connecting structure, and the second electrode is electrically connected with the backboard;
Patterning the substrate to form a back cavity;
and corroding the first sacrificial layer and the second sacrificial layer, removing the first sacrificial layer between the back plate and the back cavity and between the supporting structure and the back cavity, removing the second sacrificial layer between the back plate and the vibrating diaphragm and between the supporting structure and the vibrating diaphragm to form a cavity, and taking the rest of the second sacrificial layer as a supporting layer for supporting the vibrating diaphragm.
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| CN118138971B (en) * | 2024-05-10 | 2024-06-28 | 地球山(苏州)微电子科技有限公司 | Sound production unit and manufacturing method thereof |
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| CN118138971B (en) * | 2024-05-10 | 2024-06-28 | 地球山(苏州)微电子科技有限公司 | Sound production unit and manufacturing method thereof |
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