CN112995870A - MEMS chip, processing method thereof and MEMS microphone - Google Patents
MEMS chip, processing method thereof and MEMS microphone Download PDFInfo
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- CN112995870A CN112995870A CN202110227551.1A CN202110227551A CN112995870A CN 112995870 A CN112995870 A CN 112995870A CN 202110227551 A CN202110227551 A CN 202110227551A CN 112995870 A CN112995870 A CN 112995870A
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- 238000003672 processing method Methods 0.000 title abstract description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 146
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 146
- 239000010703 silicon Substances 0.000 claims abstract description 146
- 239000000758 substrate Substances 0.000 claims abstract description 110
- 230000000149 penetrating effect Effects 0.000 claims abstract description 15
- 238000005530 etching Methods 0.000 claims description 45
- 238000000034 method Methods 0.000 claims description 18
- 230000008569 process Effects 0.000 claims description 14
- 239000012528 membrane Substances 0.000 claims description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 7
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 7
- 230000007423 decrease Effects 0.000 claims description 3
- 230000003247 decreasing effect Effects 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 10
- 238000010586 diagram Methods 0.000 description 6
- 239000013078 crystal Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 3
- BHEPBYXIRTUNPN-UHFFFAOYSA-N hydridophosphorus(.) (triplet) Chemical compound [PH] BHEPBYXIRTUNPN-UHFFFAOYSA-N 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000005380 borophosphosilicate glass Substances 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R19/00—Electrostatic transducers
- H04R19/04—Microphones
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
- H04R2201/003—Mems transducers or their use
Abstract
The invention discloses an MEMS chip, a processing method thereof and an MEMS microphone.A first channel penetrating through a first side and a second side of a silicon substrate is formed in a silicon substrate of the MEMS chip; the sacrificial layer is arranged on the first side of the silicon substrate, a second channel is formed in the sacrificial layer and communicated with the first channel to form a cavity, and the cavity is provided with a first opening located on one side, away from the silicon substrate, of the sacrificial layer and a second opening located on one side, away from the sacrificial layer, of the silicon substrate; the vibration film layer is arranged on one side of the sacrificial layer, which is far away from the silicon substrate, and covers the first opening of the cavity; the back plate is arranged on one side of the vibration film layer back to the sacrificial layer; the inner wall surface of the first channel is provided with a convex arm, so that the cavity is provided with a reduced section, a first section and a second section between the first opening and the second opening, and the cross section area of the cavity at the reduced section is smaller than that at the first opening and the second opening. The MEMS chip provided by the invention has a better resonance effect.
Description
Technical Field
The invention relates to the technical field of micro electro mechanical systems, in particular to an MEMS chip, a processing method thereof and an MEMS microphone.
Background
The MEMS chip mainly forms a parallel plate capacitor by a diaphragm structure and a back pole structure, and when the MEMS chip is in a working state, an acoustic signal passes through a back hole formed in the silicon substrate to enable the diaphragm to vibrate, so that the purpose of sound sensing is achieved. The back hole of the traditional MEMS chip is generally formed by deep silicon etching on a silicon substrate, grooves in various shapes can be obtained by utilizing the deep silicon etching, the etching speed is high, but the inner side wall of the groove formed by the deep silicon etching is generally vertical, and the sound sensing performance of the chip is still required to be further improved.
Disclosure of Invention
The invention mainly aims to provide an MEMS chip, a processing method thereof and an MEMS microphone, aiming at improving the sound sensing performance of the MEMS chip.
To achieve the above object, the present invention provides a MEMS chip, including:
the device comprises a silicon substrate, a first channel and a second channel, wherein the first side and the second side are oppositely arranged, and the first channel penetrates through the first side and the second side of the silicon substrate;
the sacrificial layer is arranged on the first side of the silicon substrate, a second channel is formed in the position, corresponding to the first channel, of the sacrificial layer, the second channel is communicated with the first channel to form a cavity penetrating through the silicon substrate and the sacrificial layer, and the cavity is provided with a first opening located on one side, away from the silicon substrate, of the sacrificial layer and a second opening located on one side, away from the sacrificial layer, of the silicon substrate;
the vibration film layer is arranged on one side of the sacrificial layer, which is far away from the silicon substrate, and covers the first opening of the cavity; and the number of the first and second groups,
the back plate is arranged on one side, back to the sacrificial layer, of the vibration film layer, and sound holes are formed in the back plate;
the inner wall surface of the first channel is provided with a convex arm, so that the cavity is provided with a reduced section between the first opening and the second opening, a first section between the reduced section and the first opening and a second section between the reduced section and the second opening, and the cross-sectional area of the cavity at the reduced section is smaller than that at the first opening and the second opening.
Optionally, the protruding arm is disposed on a side of the silicon substrate facing the sacrificial layer.
Optionally, the first section is a straight section.
Optionally, the second section is a straight section.
Optionally, the cross-sectional area of the cavity at the second section decreases gradually in a direction from the second opening to the first opening.
Optionally, the cavity has a straight section and an inclined section in the second section, the straight section is disposed adjacent to the convex arm, the cross-sectional area of the cavity in the straight section is the same as that of the cavity at the convex arm, the inclined section is disposed adjacent to the second opening, and the cross-sectional area of the inclined section is gradually reduced in a direction from the second opening to the first opening.
The invention also provides a processing method of the MEMS chip, which comprises the following steps:
providing an MEMS chip component, wherein the MEMS chip component comprises a silicon substrate, a vibrating membrane layer and a back plate which are sequentially stacked, a sound hole is formed in the back plate, the silicon substrate is provided with a first side facing the vibrating membrane layer and a second side departing from the vibrating membrane layer, a sacrificial layer is arranged between the vibrating membrane layer and the silicon substrate, and at least part of the first side of the silicon substrate is heavily doped silicon;
etching the silicon substrate from the second side of the silicon substrate by adopting a deep silicon etching process to form a reference hole penetrating through the first side and the second side of the silicon substrate;
etching the side wall of the reference hole by adopting an anisotropic etching process to form a first channel;
and etching the sacrificial layer to form a second channel communicated with the first channel so as to form a cavity penetrating through the silicon substrate and the sacrificial layer.
Optionally, the material of the sacrificial layer is silicon oxide.
Optionally, the silicon wafer crystalline phase of the silicon substrate is <100>, <110>, or <111 >.
The invention also provides a MEMS microphone, comprising a MEMS chip, the MEMS chip comprising:
the device comprises a silicon substrate, wherein a first channel penetrating through a first side and a second side of the silicon substrate is formed in the silicon substrate;
the sacrificial layer is arranged on the first side of the silicon substrate, a second channel is formed in the position, corresponding to the first channel, of the sacrificial layer, the second channel is communicated with the first channel to form a cavity penetrating through the silicon substrate and the sacrificial layer, and the cavity is provided with a first opening located on one side, away from the silicon substrate, of the sacrificial layer and a second opening located on one side, away from the sacrificial layer, of the silicon substrate;
the vibration film layer is arranged on one side of the sacrificial layer, which is far away from the silicon substrate, and covers the second opening of the cavity; and the number of the first and second groups,
the back pole plate is arranged on one side, back to the sacrificial layer, of the vibration film layer, and sound holes are formed in the back pole plate;
the inner wall surface of the first channel is provided with a convex arm, so that the cavity is provided with a reduced section between the first opening and the second opening, a first section between the reduced section and the first opening and a second section between the reduced section and the second opening, and the cross-sectional area of the cavity at the reduced section is smaller than that at the first opening and the second opening.
In the technical scheme provided by the invention, the MEMS chip comprises a silicon substrate, a sacrificial layer, a diaphragm layer and a back plate which are sequentially arranged, wherein a first channel is formed in the silicon substrate, a second channel is formed in the sacrificial layer, the first channel and the second channel jointly form a cavity which simultaneously penetrates through the silicon substrate and the sacrificial layer, a convex arm is arranged on the inner wall surface of the first channel, and the cavity is provided with a reduced section between a first opening and a second opening, a first section between the reduced section and the first opening and a second section between the reduced section and the second opening through the arrangement of the convex arm; therefore, the first section forms a buffer cavity, so that when an acoustic signal passes through the cavity to enable the diaphragm to vibrate, a better resonance effect is achieved, the sound sensing performance of the MEMS chip is improved, and the cross sectional area of the reduced section can be controlled by setting the protruding length of the protruding arm, so that the resonance frequency is adjusted, and the MEMS chip has better sound sensing performance.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other related drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a MEMS chip according to a first embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a cavity in the silicon substrate of FIG. 1 having a silicon wafer crystalline phase of <100 >;
FIG. 3 is a schematic structural diagram of a cavity in the silicon substrate of FIG. 1 having a silicon wafer crystalline phase of <110 >;
FIG. 4 is a structural diagram of a cavity in the silicon substrate of FIG. 1 having a silicon wafer crystalline phase of <111 >;
FIG. 5 is a schematic structural diagram of a MEMS chip provided by the present invention;
FIG. 6 is a schematic structural diagram of a MEMS chip according to a third embodiment of the present invention;
fig. 7 is a schematic flow chart of an embodiment of a processing method of a MEMS chip provided in the present invention.
The reference numbers illustrate:
| 100 | |
13 | Convex |
| 10 | |
131 | |
| 101 | |
20 | |
| 101a | |
30 | |
| 101b | |
40 | |
| 101c | |
41 | Sound hole |
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially. In addition, the meaning of "and/or" appearing throughout includes three juxtapositions, exemplified by "A and/or B" including either A or B or both A and B. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The back hole of the traditional MEMS chip is generally formed by deep silicon etching on a silicon substrate, grooves in various shapes can be obtained by utilizing the deep silicon etching, the etching speed is high, but the inner side wall of the groove formed by the deep silicon etching is generally vertical, and the sound sensing performance of the chip is still required to be further improved. Therefore, in order to improve the sound sensing performance of the conventional MEMS chip, the present invention provides a MEMS chip, which is used for a sound sensor such as a MEMS microphone, an ultrasonic sensor, and the like, preferably for a MEMS microphone, and fig. 1 to 3 are specific embodiments of the MEMS chip provided by the present invention.
Referring to fig. 1 to 3, in an embodiment provided by the present invention, a MEMS chip 100 includes a silicon substrate 10, a sacrificial layer 20, a diaphragm layer 30, and a back plate 40, where the silicon substrate 10 has a first side and a second side opposite to each other, and a first channel penetrating through the first side and the second side of the silicon substrate 10 is formed in the silicon substrate 10; the sacrificial layer 20 is arranged on a first side of the silicon substrate 10, a second channel is formed in a position, corresponding to the first channel, of the sacrificial layer 20, the second channel is communicated with the first channel to form a cavity 101 penetrating through the silicon substrate 10 and the sacrificial layer 20, and the cavity 101 is provided with a first opening located on a side, away from the silicon substrate 10, of the sacrificial layer 20 and a second opening located on a side, away from the sacrificial layer 20, of the silicon substrate 10; the vibration film layer 30 is arranged on one side of the sacrificial layer 20, which is far away from the silicon substrate 10, and covers a first opening of the cavity 101; the back plate 40 is arranged on one side of the vibration film layer 30 back to the sacrificial layer 20, and a sound hole 41 is formed in the back plate 40; wherein, the inner wall surface of the first channel is provided with a convex arm 13, so that the cavity 101 has a reduced section 101a between the first opening and the second opening, a first section 101b between the reduced section 101a and the first opening, and a second section 101c between the reduced section 101a and the second opening, and the cross-sectional area of the cavity 101 at the reduced section 101a is smaller than that at the first opening and the second opening.
In the technical scheme provided by the invention, the MEMS chip 100 includes a silicon substrate 10, a sacrificial layer 20, a diaphragm layer 30 and a back plate 40, which are sequentially arranged, a first channel is formed in the silicon substrate 10, a second channel is formed in the sacrificial layer 20, the first channel and the second channel jointly form a cavity 101 which simultaneously penetrates through the silicon substrate 10 and the sacrificial layer 20, a protruding arm 13 is arranged on an inner wall surface of the first channel, and the cavity 101 has a reduced section 101a between the first opening and the second opening, a first section 101b between the reduced section 101a and the first opening, and a second section 101c between the reduced section 101a and the second opening through the arrangement of the protruding arm 13; thus, the first section 101b forms a buffer cavity, so that when an acoustic signal passes through the cavity 101 to vibrate the diaphragm, a better resonance effect is achieved, the acoustic sensing performance of the MEMS chip 101 is improved, and by setting the protrusion length of the protruding arm 13, the size of the cross-sectional area of the reduced section 101a can be controlled, so as to adjust the resonance frequency, and thus the MEMS chip 100 has a better acoustic sensing performance.
The position of the protruding arm 13 in the first channel of the silicon substrate 10 is not limited, and is preferably disposed close to the sacrificial layer 20. Specifically, in the embodiment provided by the present invention, the protruding arm 13 is disposed on a side of the silicon substrate 10 facing the sacrificial layer 20. More specifically, the protruding arm 13 is formed by performing anisotropic etching on the silicon substrate 10, one side of the silicon substrate 10 close to the sacrificial layer is at least partially heavily doped silicon, and when the silicon substrate 10 is etched by using the anisotropic etching process, the etching is automatically stopped until the heavily doped silicon is located, so that the protruding arm 13 is formed in the first channel of the silicon substrate 10. In the actual processing process of the MEMS chip, a corresponding heavily doped silicon portion may be set in the silicon substrate 10 according to the preset parameter requirements such as the protrusion length of the protruding arm 13, or a silicon substrate having a heavily doped silicon portion with a preset shape may be selected. It should be noted that, it is the prior art in the field to realize the self-stop characteristic of anisotropic etching by using heavily doped silicon, and the specific doping manner is not limited and can be selected correspondingly according to the actual processing requirement.
The protruding arm 13 has a free end 131 far away from the inner sidewall of the first channel, and when the silicon substrate 10 is etched by using the anisotropic etching process, the etched surface formed after etching is different according to different silicon wafer crystal phases of the silicon substrate 10. Referring specifically to fig. 2 to 4, the inner sidewall of the first channel is provided with two protruding arms 13 extending opposite to each other, when the silicon substrate 10 has a silicon crystal phase of <100>, the specific structure of the cavity 101 is shown in fig. 2, the free end 131 of each protruding arm 13 forms an inclined surface gradually inclined inward (i.e., inclined toward the center line of the first channel) in the direction from the silicon substrate 10 toward the sacrificial layer 20, the inclined angle of the inclined surface is 54.74 °, and the portion of the first channel corresponding to the protruding arm 13 is formed with an inclined surface having the same inclined direction and angle as the inclined end 131 of the protruding arm 13. When the silicon substrate 10 has a silicon wafer crystal phase of <110>, the specific structure of the cavity 101 is shown in fig. 3, which is the same as the structure of the silicon substrate having a silicon wafer crystal phase of <100>, except that the slope angle of the slope formed by the free end 131 of the protruding arm 13 and the first channel is 35.26 °. When the silicon wafer crystal phase of the silicon substrate 10 is <111>, the specific structure of the cavity 101 is as shown in fig. 4, the inclination directions of the uppers formed by the free ends 131 of the two opposite extending convex arms 13 are opposite, the inclination angle is 70.9 °, and the inclined surface having the same inclination direction and angle as the free end 131 of the convex arm 13 is formed at the part of the first channel adjacent to the corresponding convex arm 13. It should be noted that, this embodiment is only an exemplary embodiment for illustrating the present technical solution, and is not intended to limit the present invention, and other more possible implementation forms may be possible while satisfying the basic requirement of the present technical solution, and are not exhaustive herein.
The first section 101b forms a buffer cavity, so that the acoustic signal can have a better resonance effect when passing through the cavity 101 to vibrate the diaphragm, as long as the cross-sectional area of the cavity 101 at the reduced section 101a is smaller than that at the first opening, and the first section 101b may be a straight section or an inclined section, and in the embodiment provided by the present invention, the first section 101b is a straight section. Thus, when the protruding arm 13 is disposed on one side of the silicon substrate 10 facing the sacrificial layer 20, the first segment 101b is formed in the sacrificial layer, the sacrificial layer 20 may be made of, for example, silicon oxide, and the sacrificial layer 20 is etched to form the first segment 101b, and the first segment 101b is a straight segment, which is more convenient for the preparation of the first segment 101b and can also have a better resonance effect.
Likewise, the specific shape of the second segment 101c is not limited, and may be a straight segment, an inclined segment, or both of an inclined segment and a straight segment. Referring to fig. 1, in the first embodiment of the MEMS chip 100 provided by the present invention, the second section 101c is a straight section, which is easier to process and mold. Referring to fig. 5, in a second embodiment of the MEMS chip 100 provided by the present invention, the second section 101c is an inclined section, specifically, the cross-sectional area of the cavity in the second section is gradually decreased in a direction from the second opening to the first opening, so that the cavity 101 is first decreased and then increased in a direction from the second opening to the first opening, and when an acoustic signal passes through the cavity 101 to vibrate the diaphragm, a better resonance effect is obtained. Referring to fig. 6, in a third embodiment of the MEMS chip 100 provided by the present invention, the second section 101c has both a straight section and an inclined section, in particular, the cavity 101 has a straight section and an inclined section at the second section 101c, the straight section being arranged adjacent to the protruding arm 13, and the cross-sectional area of the cavity 101 at the straight section is the same as its cross-sectional area at the protruding arm 13, the inclined section is arranged adjacent to the second opening, and the cross-sectional area of the inclined section gradually decreases in a direction from the second opening to the first opening, thus, in the direction from the second opening to the first opening, the cavity 101 is arranged to be first reduced and then increased, and a transition part is formed between the reduced part and the enlarged part, so that the resonance effect is further improved when the acoustic signal passes through the cavity 101 to vibrate the diaphragm.
Based on the specific structure of the MEMS chip 100 provided above, the present invention further provides a processing method of the MEMS chip 100, and fig. 7 shows an embodiment of the manufacturing method of the MEMS chip 100 provided in the present invention. Referring to fig. 7, in the present embodiment, the method for manufacturing the MEMS chip 100 includes the following steps:
step S10, providing an MEMS chip component, as shown in fig. 1, the MEMS chip component includes a silicon substrate 10, a diaphragm layer 30 and a back plate 40 stacked in sequence, the back plate 40 is provided with a sound hole 41, the silicon substrate 10 has a first side facing the diaphragm layer 30 and a second side facing away from the diaphragm layer 30, a sacrificial layer 20 is provided between the diaphragm layer 30 and the silicon substrate 10, and at least a part of the first side of the silicon substrate 10 is heavily doped silicon;
in step S10, the material of the sacrificial layer 20 may be thermal oxide grown silicon oxide, undoped silicon oxide (USG) deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD), phosphorous doped silicon oxide (PSG), boron phosphorous doped silicon oxide (BPSG), or any other suitable sacrificial material known in the art. At least part of the first side of the silicon substrate 10 is provided with heavily doped silicon, so that when the silicon substrate 10 is etched by adopting anisotropic etching, the etching stops automatically when the etching is carried out to the position of the heavily doped silicon, and a first channel is formed in the silicon substrate 10; after the silicon substrate 10 is etched to form the first channel, the sacrificial layer 20 may be etched to form a second channel, and the first channel and the second channel are communicated to form a cavity 101 simultaneously penetrating through the silicon substrate 10 and the sacrificial layer 20.
Step S20, etching the silicon substrate 10 from the second side of the silicon substrate 10 by using a deep silicon etching process to form a reference hole penetrating through the first side and the second side of the silicon substrate 10;
etching is carried out from the second side of the silicon substrate 10, firstly, the silicon substrate 10 is etched by adopting a deep silicon etching process to form a reference hole penetrating through the first side and the second side of the silicon substrate 10, the reference hole is a round hole, and the reference hole can be quickly obtained by adopting deep silicon etching.
Step S30, etching the side wall of the reference hole by adopting an anisotropic etching process to form a first channel;
then, the side wall of the reference hole is etched by adopting an anisotropic etching process, and when the side wall of the reference hole is etched to the position of the heavily doped silicon by utilizing the anisotropic etching and the self-stop characteristic thereof, the etching is stopped, so that a first channel is formed in the silicon substrate 10, a convex arm 13 is formed on the inner side wall of the first channel, and through the shape design of the heavily doped part in the silicon substrate 10 and the selection of the crystalline phase of the silicon wafer, the crystalline phase of the silicon wafer of the silicon substrate is <100>, <110> or <111>, so that different structures shown in fig. 2 to 4 can be correspondingly obtained. The silicon substrate 10 is subjected to deep silicon etching firstly to quickly obtain a circular reference hole, and then the side wall of the circular reference hole is subjected to anisotropic etching, so that the shapes and the sizes of the first channel and the convex arm 13 are controlled, the specific shape of the finally formed cavity 101 can be adjusted, the resonance frequency is adjusted, and a better resonance effect is realized.
And step S40, etching the sacrificial layer to form a second channel communicated with the first channel so as to form a cavity penetrating through the silicon substrate and the sacrificial layer.
After the etching of the silicon substrate 10 is completed, etching is performed on the sacrificial layer 20 and the position corresponding to the first channel of the silicon substrate 10, a second channel communicated with the first channel is formed in the sacrificial layer 20, and the second channel and the first channel jointly form a cavity 101 which penetrates from the second side of the silicon substrate 10 to the side, away from the silicon substrate 10, of the sacrificial layer 20. In the structure of the MEMS chip 100 provided in fig. 1, 5 and 6, the second channel forms the first section 101b of the cavity 101, the first channel is located on a side of the protruding arm 13 away from the sacrificial layer 20 to form the second section 101c of the cavity 101, the protruding arm 13 forms the reduced section 101a of the cavity 101, and by controlling the extension length and the end surface shape of the protruding arm 13, the size of the cross-sectional area of the cavity 101 at the reduced section 101a, the first section 101b and the second section 101c can be controlled to obtain a more excellent resonance effect, so as to improve the sound sensing performance of the MEMS chip to the greatest extent.
According to the preparation method of the MEMS chip 100, provided by the invention, the deep silicon etching process and the anisotropic etching process are combined, and the convex arm 13 is formed on the inner side wall of the cavity 101 of the MEMS chip 100 by utilizing the self-stop characteristic of the anisotropic etching, so that the shape and the size of the cavity 101 can be adjusted, a higher resonance effect is realized when an acoustic signal passes through the cavity 101 to enable a vibrating diaphragm to vibrate, and the sound sensing performance of the MEMS chip 100 is improved.
In addition, the invention also provides a MEMS microphone, which includes a MEMS chip 100, and the specific structure of the MEMS chip 100 refers to the above embodiments. It can be understood that, since the MEMS microphone of the present invention adopts all the technical solutions of all the embodiments, at least all the beneficial effects brought by the technical solutions of the embodiments are achieved, and are not described in detail herein.
The above is only a preferred embodiment of the present invention, and it is not intended to limit the scope of the invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall be included in the scope of the present invention.
Claims (10)
1. A MEMS chip, comprising:
the device comprises a silicon substrate, a first channel and a second channel, wherein the first side and the second side are oppositely arranged, and the first channel penetrates through the first side and the second side of the silicon substrate;
the sacrificial layer is arranged on the first side of the silicon substrate, a second channel is formed in the position, corresponding to the first channel, of the sacrificial layer, the second channel is communicated with the first channel to form a cavity penetrating through the silicon substrate and the sacrificial layer, and the cavity is provided with a first opening located on one side, away from the silicon substrate, of the sacrificial layer and a second opening located on one side, away from the sacrificial layer, of the silicon substrate;
the vibration film layer is arranged on one side of the sacrificial layer, which is far away from the silicon substrate, and covers the first opening of the cavity; and the number of the first and second groups,
the back plate is arranged on one side, back to the sacrificial layer, of the vibration film layer, and sound holes are formed in the back plate;
the inner wall surface of the first channel is provided with a convex arm, so that the cavity is provided with a reduced section between the first opening and the second opening, a first section between the reduced section and the first opening and a second section between the reduced section and the second opening, and the cross-sectional area of the cavity at the reduced section is smaller than that at the first opening and the second opening.
2. The MEMS chip of claim 1, wherein the protruding arm is disposed on a side of the silicon substrate facing the sacrificial layer.
3. The MEMS chip of claim 1, wherein the first segment is a straight segment.
4. The MEMS chip of claim 1, wherein the second section is a straight section.
5. The MEMS chip of claim 1, wherein the cavity has a cross-sectional area that gradually decreases at the second section in a direction from the second opening to the first opening.
6. The MEMS chip of claim 1 wherein the cavity has a straight section and an angled section in the second section, the straight section being disposed adjacent to the protruding arm and the cavity having the same cross-sectional area in the straight section as it does at the protruding arm, the angled section being disposed adjacent to the second opening and the angled section having a decreasing cross-sectional area in a direction from the second opening to the first opening.
7. A method for processing a MEMS chip as claimed in any one of claims 1 to 6, characterized in that it comprises the following steps:
providing an MEMS chip component, wherein the MEMS chip component comprises a silicon substrate, a vibrating membrane layer and a back plate which are sequentially stacked, a sound hole is formed in the back plate, the silicon substrate is provided with a first side facing the vibrating membrane layer and a second side departing from the vibrating membrane layer, a sacrificial layer is arranged between the vibrating membrane layer and the silicon substrate, and at least part of the first side of the silicon substrate is heavily doped silicon;
etching the silicon substrate from the second side of the silicon substrate by adopting a deep silicon etching process to form a reference hole penetrating through the first side and the second side of the silicon substrate;
etching the side wall of the reference hole by adopting an anisotropic etching process to form a first channel;
and etching the sacrificial layer to form a second channel communicated with the first channel so as to form a cavity penetrating through the silicon substrate and the sacrificial layer.
8. The method of processing the MEMS chip of claim 7, wherein the sacrificial layer is made of silicon oxide.
9. The method of processing the MEMS chip of claim 7 wherein the silicon wafer crystalline phase of the silicon substrate is <100>, <110>, or <111 >.
10. A MEMS microphone comprising a MEMS chip according to any one of claims 1 to 6.
Priority Applications (1)
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