CN117376796B - Method for preparing micro electromechanical microphone - Google Patents
Method for preparing micro electromechanical microphone Download PDFInfo
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- CN117376796B CN117376796B CN202311676803.4A CN202311676803A CN117376796B CN 117376796 B CN117376796 B CN 117376796B CN 202311676803 A CN202311676803 A CN 202311676803A CN 117376796 B CN117376796 B CN 117376796B
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- 229910001218 Gallium arsenide Inorganic materials 0.000 description 2
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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
-
- 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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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Manufacturing & Machinery (AREA)
- Pressure Sensors (AREA)
Abstract
The invention provides a preparation method of a micro-electromechanical microphone, which comprises the following steps: selecting a substrate, and preparing a first baffle structure on a first surface of the substrate; preparing a vibrating diaphragm structure on one side of the first baffle structure, which is away from the substrate, wherein orthographic projection of the periphery of the vibrating diaphragm structure to the first baffle falls on the first baffle; preparing a second baffle structure at intervals on one side of the vibrating diaphragm structure, which is away from the first baffle, wherein the second baffle structure is connected with the first baffle structure, and the orthographic projection of the second baffle structure to the vibrating diaphragm structure at least partially falls on the periphery of the vibrating diaphragm structure; preparing a back plate structure at intervals on one side of the second baffle structure, which is away from the vibrating diaphragm structure, wherein the back plate structure comprises a plurality of acoustic through holes; and etching a second surface of the substrate opposite to the first surface to form a back cavity structure. Compared with the related art, the preparation method of the micro-electromechanical microphone aims at improving the freedom degree of the vibrating diaphragm to improve the sensitivity of the micro-electromechanical microphone and the structural strength of the vibrating diaphragm structure.
Description
Technical Field
The invention relates to the technical field of microphones, in particular to a preparation method of a micro-electromechanical microphone.
Background
With the development of wireless communication, the requirements of users on the call quality of mobile phones are increasing, and the design of a microphone as a voice pick-up device of the mobile phone directly affects the call quality of the mobile phone.
Because Micro-Electro-mechanical System (MEMS) technology has the characteristics of miniaturization, easy integration, high performance, low cost and the like, the MEMS microphone is favored in the industry, and the MEMS microphone is widely applied to the current mobile phone; in addition to the low noise design required in the high performance MEMS microphone, the high sensitivity MEMS microphone design is also an important factor that must be considered in the current design. In the prior art, the MEMS microphone adopts the design of four cantilever beams, so that the vibrating diaphragm can obtain larger degree of freedom, and further, the sensitivity is very high.
However, in the aforementioned MEMS microphone design, in the collision of the diaphragm with the substrate or the back plate under the reliability test, the narrower cantilever beam is the weak point of fracture of the diaphragm. Based on this, it is necessary to provide a new method for manufacturing a microelectromechanical microphone, so as to improve the structural strength of the diaphragm while improving the degree of freedom of the diaphragm.
Disclosure of Invention
The invention aims to overcome the technical problems and provide a preparation method of a micro-electromechanical microphone, which can improve the structural strength of a vibrating diaphragm while improving the freedom degree of the vibrating diaphragm.
In order to achieve the above object, an embodiment of the present invention provides a method for manufacturing a microelectromechanical microphone, including the following steps:
selecting a substrate, and depositing a first oxide layer on a first surface of the substrate;
patterning a first oxide layer, wherein the first oxide layer comprises a plurality of first connecting through holes;
depositing a first silicon nitride layer on the surface of the first oxide layer until the first connecting through hole is filled, and patterning the first silicon nitride layer to form a first baffle structure;
depositing a second oxide layer on the surface of the first baffle structure, and patterning the second oxide layer, wherein the second oxide layer comprises a second connecting through hole;
depositing a first polysilicon layer on the surface of the second oxide layer until the second connecting through hole is filled, patterning the first polysilicon layer to form a vibrating diaphragm structure, wherein orthographic projection of the periphery of the vibrating diaphragm structure to the first baffle plate falls on the first baffle plate;
depositing and patterning a third oxide layer on the surface of the vibrating diaphragm structure to expose at least part of the first baffle;
depositing a second silicon nitride layer on the surface of the third oxide layer, and patterning the second silicon nitride layer to form a second baffle structure, wherein the second baffle structure is connected with the first baffle structure, and orthographic projection of the second baffle structure to the vibrating diaphragm structure at least partially falls on the periphery of the vibrating diaphragm structure;
depositing a fourth oxide layer on the surface of the second baffle structure, depositing a backboard material layer on the surface of the fourth oxide layer, and patterning the backboard material layer to form a backboard structure, wherein the backboard structure comprises a plurality of acoustic through holes;
etching the substrate on the back to form a back cavity structure corresponding to the middle main body area of the back plate structure;
and removing the third oxide layer and the fourth oxide layer through the acoustic through hole, and removing the first oxide layer and the second oxide layer above the back cavity structure through the back cavity structure.
Further, patterning the first oxide layer includes etching a first connection via in a ring shape along an edge of the first oxide layer at a position of the first oxide layer near the edge.
Further, the number of the first connection through holes is plural, and the plural first connection through holes are sequentially arranged at intervals along the direction from the center portion to the edge portion of the first oxide layer.
Further, patterning the second oxide layer includes etching a second connection via at a location of the second oxide layer near the edge.
Further, the part of the first polysilicon layer, which fills the second connecting through hole, is an extraction electrode of the vibrating diaphragm structure.
Further, depositing the first oxide layer comprises sequentially depositing a first sub-oxide layer and a second sub-oxide layer, wherein the deposition thickness of the second sub-oxide layer is larger than that of the first sub-oxide layer.
Further, the ratio of the thickness of the second sub-oxide layer to the thickness of the first sub-oxide layer is 2 to 5.
Further, forming the back cavity structure includes thinning and etching the substrate from the second surface of the substrate.
Further, depositing the back plate material layer includes sequentially depositing a third silicon nitride layer and a second polysilicon layer.
Compared with the related art, the preparation method of the micro-electromechanical microphone provided by the invention has the advantages that the first baffle structure and the second baffle structure are respectively arranged at the two ends of the vibrating diaphragm structure along the vibrating direction, so that the displacement of the vibrating diaphragm structure in the vibrating direction is limited by the first baffle structure and the second baffle structure, the possibility that the vibrating diaphragm structure reaches the fracture stress is further reduced, and the structural strength of the vibrating diaphragm structure is further improved.
Drawings
For a clearer description of the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments will be briefly introduced below, it being obvious that the drawings in the description below are only some embodiments of the present invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art, wherein:
FIG. 1 is a schematic diagram of a MEMS microphone according to an embodiment of the invention;
FIG. 2 is a flow chart of a method for fabricating a MEMS microphone according to one embodiment of the present invention;
fig. 3a to 3o are schematic views of a microelectromechanical microphone manufacturing process according to an embodiment of the invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1, a microelectromechanical microphone 100 manufactured by the manufacturing method of the present invention includes a substrate 10 and a capacitive system 20 disposed on the substrate 10 and electrically connected to the substrate 10.
The substrate 10 is preferably made of a semiconductor material, such as silicon, and has a back cavity 101, a first surface 10A and a second surface 10B opposite to the first surface 10A, and accordingly, in the following description of the embodiment of the present invention, the first surface 10A represents the upper surface direction and the second surface 10B represents the lower surface direction. Wherein the back cavity 101 may be formed by a bulk silicon process or dry etching.
The capacitive system 20 comprises a vibrating diaphragm 21, a backboard 22 opposite to the vibrating diaphragm 21, and a first baffle plate 23 and a second baffle plate 24 respectively arranged on the lower side and the upper side of the vibrating diaphragm 21, wherein the vibrating diaphragm 21 comprises an electrode lead-out part 103, the vibrating diaphragm 21 is connected with the first baffle plate 23 through the electrode lead-out part 103, the rest part of the vibrating diaphragm 21 is arranged at intervals with the first baffle plate 23 in the vibration direction X, and the vibrating diaphragm 21 and the second baffle plate 24 are arranged at intervals in the vibration direction X. In this way, the diaphragm 21 is only connected to the first baffle 23 through the electrode lead-out portion 103, so that the rest positions of the diaphragm 21 are not connected to other components in the vibration direction X, so as to improve the release degree of the diaphragm 21, and the diaphragm 21 has a great degree of freedom in the vibration direction X, so that the sensitivity of the mems microphone 100 is improved.
In these embodiments of the present application, the electrode lead-out portion 103 is a lead-out electrode of the diaphragm 21.
Meanwhile, projections between the peripheral edge part of the diaphragm 21 and the first baffle plate 23 and between the peripheral edge part of the diaphragm 21 and the second baffle plate 24 in the vibration direction X overlap, so that the diaphragm 21 is limited by the first baffle plate 23 and the second baffle plate 24 when the diaphragm 21 vibrates, the possibility that the diaphragm 21 is displaced to reach the fracture stress is reduced, and the risk of fracture of the diaphragm 21 due to overlarge displacement in the vibration process is reduced, so that the structural strength of the diaphragm 21 is improved.
When the mems microphone 100 is powered on, the diaphragm 21 and the backplate 22 will carry charges with opposite polarities, so as to form a capacitor, and when the diaphragm 21 vibrates under the action of sound waves, the distance between the backplate 22 and the diaphragm 21 will change, so that the capacitance of the capacitive system 20 will change, and further convert the sound wave signals into electrical signals, thereby realizing the corresponding functions of the mems microphone 100.
In these embodiments of the present invention, the cross section of the diaphragm 21 along the direction perpendicular to the vibration direction X may be, but is not limited to, rectangular or circular.
The first barrier 23 and the second barrier 24 may be composed of or may include a semiconductor material such as silicon. Such as germanium, silicon carbide, gallium nitride, indium gallium nitride, indium gallium arsenide, indium gallium zinc oxide, or other elemental and/or compound semiconductors (e.g., III-V compound semiconductors such as gallium arsenide or indium phosphide, or II-VI compound semiconductors, or ternary compound semiconductors, or quaternary compound semiconductors). May also consist of or may include at least one of: metals, dielectric materials, piezoelectric materials, piezoresistive materials, and ferroelectric materials. Or may be made of a dielectric material such as silicon nitride.
In some embodiments of the present invention, the first baffle 23, the second baffle 24 and the back plate 22 may be integrally formed.
Referring to fig. 3a to 3o, a flowchart of a method for manufacturing a microelectromechanical microphone 100 as shown in fig. 1 or 2 according to an embodiment of the present invention is shown, and the method specifically includes the following steps.
Step S1, selecting a substrate 10, and preparing a first baffle 23 structure on a first surface 10A of the substrate 10, including the following sub-steps:
s11, selecting a substrate 10, and depositing a first oxide layer 231 on the first surface 10A of the substrate 10, as shown in fig. 3 a.
The substrate 10 is, for example, a semiconductor silicon substrate, but may be another semiconductor substrate, such as: germanium, silicon carbide, gallium nitride, indium gallium nitride, indium gallium arsenide, indium gallium zinc oxide, or other elemental and/or compound semiconductors (e.g., III-V compound conductors such as gallium arsenide or indium phosphide) germanium or gallium nitride, and the like.
The first oxide layer 231 is, for example, silicon dioxide, and may be formed by a conventional process such as thermal oxidation, vapor deposition, or the like.
In some embodiments, depositing the first oxide layer 231 may include sequentially depositing a first sub-oxide layer 2311 and a second sub-oxide layer 2312, wherein a deposition thickness of the second sub-oxide layer 2312 is greater than a deposition thickness of the first sub-oxide layer 2311.
Illustratively, in some embodiments, the ratio of the thickness of the second sub-oxide 2312 to the thickness of the first sub-oxide 2311 may be set to 2 to 5, for example, the thickness of the second sub-oxide 2312 may be set to 3 times or 4 times the thickness of the first sub-oxide 2311.
S12, patterning the first oxide layer 231, such that the first oxide layer 231 includes a plurality of first connection holes 104, as shown in fig. 3 b.
In this step, the first connection via 104 exposes a portion of the first surface 10A of the substrate 10 to the first oxide layer 231 to contact the first silicon nitride layer 232 in the subsequent deposition process, so as to form a connection conductive structure.
In some embodiments of the present invention, the first connection via 104 having a ring shape may be etched along the edge of the first oxide layer 231 at a position near the edge of the first oxide layer 231. Wherein the edge position of the first oxide layer 231 refers to an edge position on a plane parallel to the first surface 10A of the substrate 10; the first connection hole 104 having a ring shape means that the first connection hole 104 has a ring shape in a cross-sectional shape parallel to the first surface 10A of the substrate 10, similar to the outer contour of the first oxide layer 231.
Preferably, in some embodiments, the number of the first connection holes 104 may be set to be plural, and the plural first connection holes 104 are disposed at intervals along the central portion of the first oxide layer 231 to one side in the direction of the edge portion. To improve the contact area between the subsequently deposited first silicon nitride layer 232 and the substrate 10, and to improve the structural consistency between the first silicon nitride layer 232 and the substrate 10.
S13, depositing a first silicon nitride layer 232 on the surface of the first oxide layer 231 until the first connection hole 104 is filled, and patterning the first silicon nitride layer 232 to form the first baffle 23 structure, as shown in fig. 3 d.
The first silicon nitride layer 232 is patterned such that the first silicon nitride layer 232 is processed into a ring-shaped first barrier 23 structure.
Step S2, preparing a diaphragm 21 structure on a side of the first baffle 23 structure facing away from the substrate 10, including the following sub-steps:
s21, depositing a second oxide layer 211 on the surface of the first baffle 23 structure, and patterning the second oxide layer 211, where the second oxide layer 211 includes a second connection via 2111, as shown in fig. 3 e.
In some embodiments, patterning the second oxide layer 211 may include etching the second connection via 2111 at a position near the edge of the second oxide layer 211.
S22, depositing a first polysilicon layer 212 on the surface of the second oxide layer 211 until the second connection via 2111 is filled, and patterning the first polysilicon layer 212 to form the diaphragm 21 structure. The orthographic projection of the periphery of the diaphragm 21 to the first baffle 23 falls on the first baffle 23, as shown in fig. 3f to 3 g.
In these embodiments of the present invention, the portion of the first polysilicon layer 212 filled into the second connection hole 2111 is the connection position between the subsequent diaphragm 21 and the first baffle 23, and in some embodiments, the second connection hole 2111 may be disposed at a position along the periphery of the second oxide layer 211, so as to reduce the number of connection points between the diaphragm 21 and other components, so as to release the diaphragm 21 more, so that the diaphragm 21 obtains more degrees of freedom in the vibration direction, and further improves the sensitivity of the microelectromechanical microphone 100.
Illustratively, in some embodiments, the portion of the structure of the diaphragm 21 corresponding to the second connection hole 2111 may be an electrode lead-out structure of the diaphragm 21, so as to simultaneously connect the diaphragm 21 to the electrical conductor.
Meanwhile, the orthographic projection of the periphery of the vibrating diaphragm 21 structure to the first baffle plate 23 falls on the first baffle plate 23, and the first baffle plate 23 can be utilized to provide limit for the vibrating diaphragm 21 at one side of the vibrating direction X of the vibrating diaphragm 21, so that the vibrating diaphragm 21 cannot excessively displace at the side, the possibility that the vibrating diaphragm 21 structure reaches fracture stress is further reduced, and the structural strength of the vibrating diaphragm 21 structure is further improved.
Step S3, preparing a second baffle 24 structure at intervals on one side of the diaphragm 21 structure facing away from the first baffle 23, including the following sub-steps:
s31, a third oxide layer 241 is deposited and patterned on the surface of the structure of the diaphragm 21 to expose at least part of the first baffle 23, as shown in FIG. 3 h.
S32, depositing a second silicon nitride layer 242 on the surface of the third oxide layer 241, and patterning the second silicon nitride layer 242 to form a second baffle 24 structure, wherein the second baffle 24 structure is connected with the first baffle 23 structure, and the orthographic projection of the second baffle 24 structure to the diaphragm 21 structure at least partially falls on the periphery of the diaphragm 21 structure, as shown in FIG. 3 i.
The structure of the second baffle 24 is structurally connected with the first baffle 23, which means that when the second silicon nitride layer 242 is deposited, the second silicon nitride layer 242 can be contacted with a part of the first baffle 23 exposed in the step S31, and when the second silicon nitride layer 242 is patterned later, a part of the second silicon nitride layer 242 contacted with the first baffle 23 is reserved, so that the structure of the first baffle 23 and the second baffle 24 in an integral way improves the structural consistency and the structural reliability of the microelectromechanical microphone 100.
The orthographic projection of the second baffle 24 structure to the vibrating diaphragm 21 structure falls at least partially at the periphery of the vibrating diaphragm 21 structure, and the structure of the second baffle 24 is similar to that of the first baffle 23, and is an annular structure corresponding to the periphery of the vibrating diaphragm 21, and the second baffle 24 is used for providing limit for the vibrating diaphragm 21 at the other side of the vibrating diaphragm 21 along the vibration direction X, so that the overlarge displacement of the vibrating diaphragm 21 at one side close to the second baffle 24 in the vibration process is reduced, the possibility that the vibrating diaphragm 21 structure reaches fracture stress is further reduced, and the structural strength of the vibrating diaphragm 21 structure is further improved.
Step S4, preparing a back plate 22 structure at intervals on a side of the second baffle 24 structure facing away from the diaphragm 21 structure, where the back plate 22 structure includes a plurality of acoustic through holes 102, and includes the following substeps:
s41, depositing a fourth oxide layer 221 on the surface of the second baffle 24 structure, depositing a back plate material layer 222 on the surface of the fourth oxide layer 221, and patterning the back plate material layer 222 to form a back plate 22 structure, wherein the back plate 22 structure comprises a plurality of acoustic through holes 102, as shown in FIG. 3j to FIG. 3 m.
Wherein depositing the backplate material layer 222 includes sequentially depositing a third silicon nitride layer 2221 and a second polysilicon layer 2222.
The acoustic through hole 102 penetrates the third silicon nitride layer 2221 and the second polysilicon layer 2222 in the vibration direction X of the diaphragm 21.
Step S5, etching the second surface 10B of the substrate 10 opposite to the first surface 10A to form the back cavity 101 structure, includes the following sub-steps:
s51, back etching the substrate 10 to form a back cavity 101 structure corresponding to the middle body region of the structure of the back plate 22, as shown in fig. 3 n.
Illustratively, in some embodiments, the second surface 10B of the substrate 10 may be thinned using a polishing process, and then the second surface 10B of the substrate 10 is patterned and etched to form the back cavity 101 region, with the etch stopping at the first oxide layer 231.
S52, the third oxide layer 241 and the fourth oxide layer 221 are removed through the acoustic via 102, and the first oxide layer 231 and the second oxide layer 211 above the back cavity 101 are removed through the back cavity 101, as shown in fig. 3 o.
Illustratively, the first oxide layer 231, the second oxide layer 211, the third oxide layer 241, and the fourth oxide layer 221 may be removed using a BOE solution or an HF vapor phase etching technique.
While the invention has been described with respect to the above embodiments, it should be noted that modifications can be made by those skilled in the art without departing from the inventive concept, and these are all within the scope of the invention.
Claims (9)
1. A method for manufacturing a microelectromechanical microphone, comprising the steps of:
selecting a substrate, and depositing a first oxide layer on a first surface of the substrate;
patterning the first oxide layer, wherein the first oxide layer comprises a plurality of first connecting through holes;
depositing a first silicon nitride layer on the surface of the first oxide layer until the first connecting through hole is filled, and patterning the first silicon nitride layer to form a first baffle structure;
depositing a second oxide layer on the surface of the first baffle structure, and patterning the second oxide layer, wherein the second oxide layer comprises a second connecting through hole;
depositing a first polysilicon layer on the surface of the second oxide layer until the second connecting through hole is filled, and patterning the first polysilicon layer to form a vibrating diaphragm structure, wherein orthographic projection of the periphery of the vibrating diaphragm structure to the first baffle plate falls on the first baffle plate;
depositing and patterning a third oxide layer on the surface of the vibrating diaphragm structure to expose at least part of the first baffle;
depositing a second silicon nitride layer on the surface of the third oxide layer, and patterning the second silicon nitride layer to form a second baffle structure, wherein the second baffle structure is connected with the first baffle structure, and the orthographic projection of the second baffle structure to the vibrating diaphragm structure at least partially falls on the periphery of the vibrating diaphragm structure;
depositing a fourth oxide layer on the surface of the second baffle structure, depositing a backboard material layer on the surface of the fourth oxide layer, and patterning the backboard material layer to form a backboard structure, wherein the backboard structure comprises a plurality of acoustic through holes;
etching the substrate on the back surface to form a back cavity structure corresponding to the middle main body area of the back plate structure;
and removing the third oxide layer and the fourth oxide layer through the acoustic through hole, and removing the first oxide layer and the second oxide layer above the back cavity structure through the back cavity structure.
2. The method of claim 1, wherein patterning the first oxide layer includes etching the first connection via in a ring shape along an edge of the first oxide layer at a position near the edge of the first oxide layer.
3. The method for manufacturing a microelectromechanical microphone according to claim 2, characterized in that the number of the first connecting holes is plural, and the plural first connecting holes are sequentially arranged at intervals along the direction from the center portion to the edge portion of the first oxide layer.
4. The method of claim 1, wherein patterning the second oxide layer includes etching the second connection via at a location of the second oxide layer near an edge.
5. The method of claim 4, wherein the portion of the first polysilicon layer that fills the second connection via is an extraction electrode of the diaphragm structure.
6. The method of claim 1, wherein depositing the first oxide layer comprises sequentially depositing a first sub-oxide layer and a second sub-oxide layer, the second sub-oxide layer having a deposition thickness greater than a deposition thickness of the first sub-oxide layer.
7. The method of claim 6, wherein a ratio of a thickness of the second sub-oxide layer to a thickness of the first sub-oxide layer is 2 to 5.
8. The method of claim 1, wherein forming the back cavity structure comprises thinning and etching the substrate from the second surface of the substrate.
9. The method of claim 1, wherein depositing the backplate material layer comprises sequentially depositing a third silicon nitride layer and a second polysilicon layer.
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| CN202311676803.4A CN117376796B (en) | 2023-12-08 | 2023-12-08 | Method for preparing micro electromechanical microphone |
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| CN202311676803.4A CN117376796B (en) | 2023-12-08 | 2023-12-08 | Method for preparing micro electromechanical microphone |
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| CN117376796B true CN117376796B (en) | 2024-02-06 |
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Citations (18)
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