CN113691916B - MEMS microphone and preparation method thereof - Google Patents
MEMS microphone and preparation method thereof Download PDFInfo
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- CN113691916B CN113691916B CN202111114623.8A CN202111114623A CN113691916B CN 113691916 B CN113691916 B CN 113691916B CN 202111114623 A CN202111114623 A CN 202111114623A CN 113691916 B CN113691916 B CN 113691916B
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- 238000002360 preparation method Methods 0.000 title abstract description 6
- 239000000758 substrate Substances 0.000 claims abstract description 59
- 239000000463 material Substances 0.000 claims abstract description 57
- 230000000903 blocking effect Effects 0.000 claims abstract description 35
- 238000000034 method Methods 0.000 claims description 28
- 239000007772 electrode material Substances 0.000 claims description 21
- 238000005530 etching Methods 0.000 claims description 18
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 230000000149 penetrating effect Effects 0.000 claims description 9
- 238000000227 grinding Methods 0.000 claims description 7
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims description 7
- 229920005591 polysilicon Polymers 0.000 claims description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 5
- 238000013022 venting Methods 0.000 claims description 5
- 238000000151 deposition Methods 0.000 claims description 4
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 3
- 238000000059 patterning Methods 0.000 claims description 3
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 3
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 3
- 238000012545 processing Methods 0.000 claims description 2
- 230000004888 barrier function Effects 0.000 claims 1
- 238000001514 detection method Methods 0.000 abstract description 4
- 230000035945 sensitivity Effects 0.000 abstract description 3
- 230000008569 process Effects 0.000 description 9
- 230000000694 effects Effects 0.000 description 8
- 230000002411 adverse Effects 0.000 description 6
- 238000005336 cracking Methods 0.000 description 4
- 238000005137 deposition process Methods 0.000 description 3
- 238000007740 vapor deposition Methods 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 229910000577 Silicon-germanium Inorganic materials 0.000 description 2
- LEVVHYCKPQWKOP-UHFFFAOYSA-N [Si].[Ge] Chemical compound [Si].[Ge] LEVVHYCKPQWKOP-UHFFFAOYSA-N 0.000 description 2
- 238000000231 atomic layer deposition Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000000206 photolithography Methods 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 2
- 229910010271 silicon carbide Inorganic materials 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- -1 SOI Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001312 dry etching Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 229910052732 germanium Inorganic materials 0.000 description 1
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000007517 polishing process Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 239000010980 sapphire Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000001039 wet etching Methods 0.000 description 1
Classifications
-
- 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
- H04R31/006—Interconnection of transducer parts
-
- 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
- H04R7/12—Non-planar diaphragms or cones
- H04R7/14—Non-planar diaphragms or cones corrugated, pleated or ribbed
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
- H04R2201/003—Mems transducers or their use
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Manufacturing & Machinery (AREA)
- Multimedia (AREA)
- Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
- Micromachines (AREA)
Abstract
The invention provides a MEMS microphone and a preparation method thereof. The microphone comprises a substrate, a back electrode and a back plate material layer, wherein a cavity is formed in the substrate; the vibrating diaphragm is arranged on the substrate, and a fold structure and a gas leakage hole are formed in the vibrating diaphragm; the back electrode is positioned above the vibrating diaphragm and is spaced from the vibrating diaphragm, and a plurality of sound holes are formed in the back electrode; the back plate material layer is positioned on the back electrode and extends outwards to the surface of the substrate, a plurality of openings, a plurality of back electrode blocking blocks and supporting columns are formed in the back plate material layer, the openings are exposed out of the sound holes in one-to-one correspondence, the supporting columns and the back electrode blocking blocks penetrate through the back electrode and extend downwards, and the supporting columns are connected with the vibrating diaphragm. The support column arranged between the back electrode and the vibrating diaphragm is arranged on the vibrating diaphragm, so that the MEMS microphone can be ensured to have high detection sensitivity, meanwhile, the local amplitude of the vibrating diaphragm is prevented from being too large, the vibrating diaphragm is prevented from being damaged, adhesion between the vibrating diaphragm and the back electrode is prevented, and the mechanical strength and the performance of the MEMS microphone are improved.
Description
Technical Field
The invention relates to the technical field of micro-electromechanical systems, in particular to an MEMS microphone and a preparation method thereof.
Background
With the rapid development of consumer electronics, the microphone industry has also grown vigorously. Microphones are widely used in consumer electronics, smart home and other fields, and are required for all devices with voice control functions. In recent years, conventional electret condenser microphones have been replaced by MEMS microphones due to the relatively cumbersome matching operation.
The MEMS microphone comprises a diaphragm capable of vibrating up and down and a fixed back electrode plate, the back electrode plate has excellent rigidity and is etched with sound holes, air circulation is allowed without deflection, the diaphragm can bend along with sound waves, the diaphragm moves relative to the back electrode plate to generate certain capacitance change, and the weak capacitance change is amplified and converted into an electric signal to be output through an ASIC chip connected with the MEMS microphone.
The conventional MEMS microphone structure is generally provided with a fold structure on the diaphragm 21, which is beneficial to increasing the vibration amplitude of the diaphragm under the condition of the same area, but the grooves of the fold structure can cause the back electrode 17 to grow along with the shape in the preparation process, so that the stress concentration in the area a indicated by the dashed line frame shown in fig. 1 may occur, and the situation such as crack damage may occur. In addition, when the vibration amplitude of the diaphragm is too large or conductive particles exist between the back of the diaphragm, the attraction between the diaphragm and the back electrode is easy to occur.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a MEMS microphone and a method for manufacturing the same, which are used for solving the problems that in the MEMS microphone in the prior art, when a corrugated structure is provided, stress concentration in a portion corresponding to the corrugated structure of a diaphragm is caused by the following growth of a back electrode during manufacturing, the back electrode is cracked, and when the amplitude of the diaphragm is too large or conductive particles exist between the back electrodes of the diaphragm, the suction of the diaphragm and the back electrode is easy to occur.
To achieve the above and other related objects, the present invention provides a method for manufacturing a MEMS microphone, comprising the steps of:
Providing a substrate, and forming a first sacrificial layer on the substrate;
Patterning the first sacrificial layer to form a first groove corresponding to the vibrating diaphragm;
forming a vibrating diaphragm material layer on the first sacrificial layer, wherein the vibrating diaphragm material layer fills the first groove to form a vibrating diaphragm, and the vibrating diaphragm comprises a fold structure and a bracket positioned on the outer side of the fold structure;
Forming a gas leakage hole in the vibrating diaphragm, wherein the gas leakage hole exposes the first sacrificial layer;
forming a second sacrificial layer by adopting a conformal deposition method, wherein the second sacrificial layer covers the vibrating diaphragm and the air leakage hole, and the upper surface of the formed second sacrificial layer is provided with a concave-convex structure corresponding to the fold structure of the vibrating diaphragm;
Grinding the second sacrificial layer to enable the upper surfaces of the second sacrificial layer to be flush;
etching to form a second groove corresponding to the back electrode blocking piece in the second sacrificial layer, wherein the depth of the second groove corresponding to the back electrode blocking piece is smaller than the height of the second sacrificial layer;
forming a back electrode material layer on the surface of the second sacrificial layer, wherein the back electrode material layer covers the second sacrificial layer and fills the second groove;
etching the back electrode material layer to form a back electrode, wherein a plurality of sound holes are formed in the back electrode, the second grooves of the corresponding back electrode blocking blocks are exposed in the back electrode, and the second sacrificial layer is exposed in the plurality of sound holes;
forming a back plate material layer, wherein the back plate material layer covers the back electrode material layer and fills the sound hole and the second groove;
Removing the backboard material layer correspondingly positioned in the sound hole until the second sacrificial layer is exposed in the sound hole, wherein backboard material filled in the second groove corresponding to the back electrode blocking block forms the back electrode blocking block, and the back electrode blocking block penetrates through the back electrode and extends downwards;
Forming a cavity in the substrate, the cavity penetrating through the substrate;
And etching the first sacrificial layer and the second sacrificial layer to release the vibrating diaphragm and the back electrode.
Optionally, before forming the cavity penetrating through the substrate in the substrate, a step of thinning the substrate is further included, and then the cavity is formed in the thinned substrate.
Optionally, the materials of the first sacrificial layer and the second sacrificial layer comprise silicon oxide.
Optionally, the thickness of the second sacrificial layer is greater than the thickness of the first sacrificial layer.
Optionally, the material of the diaphragm and the back electrode includes polysilicon.
Optionally, the plurality of air release holes and the support are all multiple, and a plurality of air release holes are located between the fold structure and the support.
Optionally, the method further includes forming a dicing channel around the periphery of the diaphragm while forming the air vent hole in the diaphragm, where the dicing channel exposes the first sacrificial layer, and then etching the corresponding material layers to expose the dicing channel in the process of processing the second sacrificial layer, the back electrode material layer, and the back plate material layer.
Optionally, the material of the back plate material layer includes silicon nitride, and the back plate material layer extends outwards to the surface of the substrate and has a distance from the diaphragm.
Optionally, in the process of etching the second groove of the corresponding back electrode blocking piece in the second sacrificial layer, a second groove of a corresponding support column is synchronously formed, wherein the second groove of the corresponding support column penetrates through the second sacrificial layer, a back plate material filled in the second groove of the corresponding support column subsequently forms the support column, the support column penetrates through the back electrode and extends downwards to be connected with the vibrating diaphragm, and the support column is located above the cavity.
The present invention also provides a MEMS microphone comprising:
a substrate having a cavity formed therein that penetrates the substrate;
the vibrating diaphragm is erected on the substrate through a bracket, and a fold structure and a venting hole penetrating through the vibrating diaphragm are formed in the vibrating diaphragm;
The back electrode is positioned above the vibrating diaphragm and is spaced from the vibrating diaphragm, and a plurality of sound holes are formed in the back electrode;
The back plate material layer is positioned on the back plate and extends outwards to the surface of the substrate, a plurality of openings, a plurality of back plate blocking blocks and supporting columns are formed in the back plate material layer, the sound holes are exposed in one-to-one correspondence of the openings, the supporting columns and the back plate blocking blocks penetrate through the back plate and extend downwards, and the supporting columns are connected with the vibrating diaphragm.
Optionally, the support column includes any one of a circular column and a polygonal column.
Optionally, the height of the back electrode blocking block is 1/4-3/4 of the distance between the back electrode and the vibrating diaphragm.
Optionally, the back electrode blocking block is not disposed above the fold structure.
Optionally, the fold structure is an annular structure and is wound around the periphery of the support column.
As described above, the MEMS microphone and the method for manufacturing the same of the present invention have the following advantageous effects: according to the invention, the second sacrificial layer is formed through conformal deposition, and then the second sacrificial layer is subjected to grinding treatment, so that the stress of the second sacrificial layer can be effectively released through grinding, and meanwhile, the upper surface of the second sacrificial layer is a horizontal plane, and adverse effects on subsequent processes, such as adverse effects such as cracks on the back electrode caused by overlarge local stress of a subsequent back electrode material layer, are avoided. Through set up the support column that is located between back of body utmost point and the vibrating diaphragm when setting up fold structure on the vibrating diaphragm, can ensure that MEMS microphone avoids vibrating diaphragm local amplitude too big when having very high detection sensitivity, avoid the vibrating diaphragm damaged and with take place the adhesion between the back of body utmost point, help improving mechanical strength and the performance of MEMS microphone.
Drawings
Fig. 1 shows an exemplary structural schematic diagram of a MEMS microphone in the prior art.
Fig. 2-16 show schematic cross-sectional structures of MEMS microphones provided by the present invention at various steps in the manufacturing process.
Description of element reference numerals
11. Substrate
111. Cavity cavity
12. First sacrificial layer
121, 121A,121b,121c first groove
13. Vibrating diaphragm
131. Fold structure
132. Support frame
133. Air leakage hole
13A layer of diaphragm material
14. Second sacrificial layer
141, 141A,141b second grooves
142. Concave-convex structure
15. Support column
16. Back electrode blocking block
17. Back electrode
171. Acoustic aperture
17A back electrode material layer
18. Backing material layer
181. Perforating the hole
19. Cutting path
21. Vibrating diaphragm
22. Backboard
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention. As described in detail in the embodiments of the present invention, the cross-sectional view of the device structure is not partially enlarged to a general scale for convenience of explanation, and the schematic drawings are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in actual fabrication.
For ease of description, spatially relative terms such as "under", "below", "beneath", "above", "upper" and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Furthermore, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers or one or more intervening layers may also be present.
In the context of the present application, a structure described as a first feature being "on" a second feature may include embodiments where the first and second features are formed in direct contact, as well as embodiments where additional features are formed between the first and second features, such that the first and second features may not be in direct contact.
It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex. In order to make the illustration as concise as possible, not all structures are labeled in the drawings.
In order to improve the detection accuracy of the MEMS microphone, a through hole or a fold structure is usually disposed on the diaphragm to improve the response of the diaphragm to external excitation, but this may cause damage to the diaphragm or the back electrode to be attracted due to excessive local amplitude. Meanwhile, during the manufacturing process, the local stress of the MEMS microphone may be excessively concentrated to affect the device performance. For this reason, the inventors have long studied and proposed an improvement scheme that helps to improve the mechanical strength of the microphone while maintaining the diaphragm fold structure.
Specifically, the invention provides a preparation method of an MEMS microphone, which comprises the following steps:
Providing a substrate 11, and forming a first sacrificial layer 12 on the substrate 11; the substrate 11 is preferably a semiconductor substrate 11, including but not limited to silicon, silicon germanium, silicon carbide, SOI, or sapphire, and the first sacrificial layer 12 is preferably but not limited to a silicon oxide layer, and the formation method includes but is not limited to an oxidation method and a vapor deposition method, and the structure obtained after this step is shown in fig. 2;
Patterning the first sacrificial layer 12 to form a first groove 121 corresponding to the diaphragm 13; the step may specifically include forming a first groove 121a corresponding to a fold structure of the diaphragm 13 by using a photolithography and etching process, and in the step, forming a first groove 121b corresponding to a diaphragm blocking piece in synchronization, that is, the blocking piece and the first grooves 121a and 121b corresponding to the fold structure may have the same depth, where the obtained structure is shown in fig. 3, and then continuing to etch the first sacrificial layer 12 by using photolithography and etching to obtain a first groove 121c corresponding to the bracket 132 and penetrating the first sacrificial layer 12, where the obtained structure is shown in fig. 4;
Forming a diaphragm material layer 13a on the first sacrificial layer 12, wherein the diaphragm material layer 13a fills the first groove 121 to form a diaphragm 13, and the diaphragm 13 includes a corrugated structure 131 and a support 132 located outside the corrugated structure 131 (a side away from the center is defined as an outside); the diaphragm material layer 13a is preferably a polysilicon layer, and the forming method preferably adopts a conformal deposition process such as atomic layer deposition, i.e. the deposited polysilicon layer is completely filled with the first groove 121 to form the diaphragm 13 including the fold structure 131, the blocking block and the bracket 132; the structure obtained after this step is shown in fig. 5;
Forming a venting hole 133 in the diaphragm 13 by an etching process, wherein the venting hole 133 exposes the first sacrificial layer 12; in this step, a dicing channel 19 may be etched on the periphery of the diaphragm 13, and the dicing channel 19 exposes the surface of the substrate 11; the structure obtained after this step is shown in FIG. 6;
Forming a second sacrificial layer 14 by adopting a conformal deposition process, wherein the second sacrificial layer 14 covers the diaphragm 13 and the air leakage hole 133; specifically, the second sacrificial layer 14 is preferably a silicon dioxide layer, and is preferably formed by adopting a conformal deposition process such as atomic layer deposition, so that the concave-convex structure 142 corresponding to the fold structure 131 of the diaphragm 13 is formed on the upper surface of the second sacrificial layer 14, and the obtained structure is as shown in fig. 7, and the thickness of the second sacrificial layer 14 is preferably greater than that of the first sacrificial layer 12, so as to ensure that a cavity with a certain volume is formed between the back electrode 17 and the diaphragm 13, which are formed subsequently; under the condition that the concave-convex structure 142 is correspondingly formed on the second sacrificial layer 14, then polishing treatment is performed, for example, a chemical mechanical polishing process can be adopted to planarize the second sacrificial layer 14, so that the concave-convex structure 142 is removed to enable the upper surface of the second sacrificial layer 14 to be a horizontal plane, and the stress of the second sacrificial layer 14 can be effectively released through chemical mechanical polishing, and meanwhile, the upper surface of the second sacrificial layer is enabled to be a horizontal plane, so that adverse effects on subsequent processes caused by cracking of the second sacrificial layer 14 due to overlarge local stress, such as adverse effects caused by cracking of a back electrode due to overlarge local stress of a subsequent back electrode material layer 17a, are avoided; the structure obtained after grinding is shown in figure 8;
Etching the second sacrificial layer 14 to form a second groove 141 corresponding to the back electrode stopper 16 by using an etching process, wherein the second groove 141b corresponding to the support column 15 penetrates through the second sacrificial layer 14 until the diaphragm 13 is exposed, and the depth of the second groove 141a corresponding to the back electrode stopper 16 is smaller than the height of the second sacrificial layer 14, for example, may be 1/4-3/4 of the thickness of the second sacrificial layer 14, preferably within 1/2; the structure obtained after this step is shown in fig. 9; this step may be followed by etching to reveal the scribe line 19, resulting in a structure as described in fig. 10;
Forming a back electrode material layer 17a on the surface of the second sacrificial layer 14, wherein the back electrode material layer 17a covers the second sacrificial layer 14 and fills the second groove 141; the back electrode material layer 17a is preferably but not limited to a polysilicon layer, and the forming method includes but is not limited to vapor deposition, and the structure obtained after this step is shown in fig. 11;
etching the back electrode material layer 17a to form a back electrode 17, wherein a plurality of sound holes 171 are formed in the back electrode 17, the second grooves 141 corresponding to the back electrode blocking blocks 16 and the supporting columns 15 are exposed in the back electrode 17 (i.e. the back electrode material layer 17a in the second grooves is removed), the plurality of sound holes 171 expose the second sacrificial layer 14, and the back electrode material on the dicing streets 19 can be removed at the same time; the structure obtained after this step is shown in fig. 12;
Forming a back plate material layer 18, wherein the back plate material layer 18 covers the back electrode material layer 17a and fills the sound holes 171 and the second grooves 141; the back plate material layer 18 is preferably a silicon nitride layer, and is formed by a vapor deposition method, which can extend to the surface of the substrate 11 but has a distance from the diaphragm 13; the structure obtained after this step is shown in fig. 13;
Removing the back plate material layer 18 corresponding to the sound holes 171 until the second sacrificial layer 14 is exposed in the sound holes 171 (which may also be described as forming a plurality of openings in the back plate material layer 18, the plurality of openings exposing the sound holes 171 in a one-to-one correspondence, or both being connected up and down, the openings in the back plate material layer 18 may also be considered as part of the sound holes 171), and if the second grooves of the corresponding support posts are formed before, in this step, the back plate material filled in the second grooves of the corresponding support posts 15 forms the support posts 15 (i.e., the support posts 15 and the back plate material layer 18 are integrally connected, or the support posts 15 extend downward from the back plate material layer 18 to below the back plate 17, the support posts 15 may contact the back plate 17), the back plate material filled in the second grooves of the corresponding back plate block 16 forms the back plate block 16, the back plate block 16 and the support posts 15 extend downward through the back plate 17, and the support posts 15 are connected to the diaphragm 13; the number of the back electrode stoppers 16 is preferably plural (but the back electrode stoppers 16 are preferably not disposed above the fold structures to avoid collision between the back electrode stoppers 16 and the corresponding fold structures due to excessive amplitude), the fold structures are uniformly distributed on opposite sides of the support columns 15, the fold structures are annular structures, and are wound around the periphery of the support columns 15, the support columns 15 may be circular columns or polygonal columns (such as quadrangles, pentagons, hexagons, etc., preferably circular from the aspect of technology, etc.), and the back plate material layer 18 at the position of the dicing street 19 may be etched synchronously during etching; the structure obtained after this step is shown in fig. 14;
Forming a cavity in the substrate 11 through the substrate 11, the support posts 15 previously formed being located above the cavity; specifically, the substrate 11 may be first subjected to back grinding and thinning, and then the cavity is formed in the thinned substrate 11 by adopting a dry etching process, and the resulting structure is shown in fig. 15;
Preferably, the first sacrificial layer 12 and the second sacrificial layer 14 are etched by wet etching to release the diaphragm 13 and the back electrode 17, and the structure obtained is shown in fig. 16, it can be seen that the diaphragm 13 is mounted on the substrate 11 through a bracket 132, the fold structure 131 is located above the cavity, the diaphragm 13 is spaced from the back plate material layer 18, and a plurality of blocking blocks (not labeled) are provided on the lower surface of the diaphragm 13, so as to avoid adhesion between the diaphragm 13 and the substrate 11.
As an example, the vent holes 133 and the brackets 132 are plural, and the vent holes 133 are located between the pleated structure 131 and the brackets 132.
The present invention also provides a MEMS microphone that can be manufactured based on any of the methods described above, so the foregoing is incorporated herein in its entirety. Specifically, as shown in fig. 16, the MEMS microphone includes:
A substrate 11, the substrate 11 having a cavity formed therein through the substrate 11;
the vibrating diaphragm 13 is erected on the substrate 11 through a bracket 132, a fold structure 131 and a vent hole 133 penetrating through the vibrating diaphragm 13 are formed in the vibrating diaphragm 13, and the fold structure 131 is preferably correspondingly positioned above the cavity;
A back electrode 17 located above the diaphragm 13 and spaced from the diaphragm 13, wherein a plurality of sound holes 171 are formed in the back electrode 17;
the backing material layer 18 is located on the back electrode 17 and extends outwards to the surface of the substrate 11, a plurality of openings, a plurality of back electrode blocking pieces 16 and supporting columns 15 are formed in the backing material layer 18, the openings expose the sound holes 171 in a one-to-one correspondence mode, the supporting columns 15 and the back electrode blocking pieces 16 penetrate through the back electrode 17 and extend downwards, and the supporting columns 15 are connected with the vibrating diaphragm 13. A plurality of auxiliary support columns (not shown) can be formed on the back plate material layer and are arranged at intervals with the support columns, and the auxiliary support columns also penetrate through the back electrode downwards and extend downwards, but the height of the auxiliary support columns is smaller than that of the support columns and are not connected with the vibrating diaphragm. Providing auxiliary support posts helps to further improve the mechanical strength of the MEMS microphone.
The support column 15 includes any one of a circular column and a polygonal column as an example.
As an example, the height of the back electrode blocking piece 16 is 1/4-3/4 of the distance between the back electrode 17 and the diaphragm 13, preferably within 1/2, and preferably, the back electrode blocking piece 16 is not disposed above the pleat 131.
As an example, the fold structure 131 is a ring structure, and is disposed around the periphery of the support column 15.
As an example, the diaphragm 13 and the back electrode 17 are both preferably polysilicon layers, and the back plate material layer 18 is preferably a polysilicon layer.
The MEMS microphone also comprises, as an example, a dicing street 19 located at the periphery of the diaphragm 13.
The substrate may be any one of a silicon substrate, a germanium substrate, an SOI substrate, a silicon germanium substrate, a silicon carbide substrate, and the like.
For further description of the MEMS microphone, reference is made to the foregoing, and for brevity, description is omitted.
In summary, the present invention provides a MEMS microphone and a method for manufacturing the same. The MEMS microphone comprises a substrate, a back electrode and a back plate material layer, wherein a cavity penetrating through the substrate is formed in the substrate; the vibrating diaphragm is erected on the substrate through a bracket, and a fold structure and a venting hole penetrating through the vibrating diaphragm are formed in the vibrating diaphragm; the back electrode is positioned above the vibrating diaphragm and is spaced from the vibrating diaphragm, and a plurality of sound holes are formed in the back electrode; the back board material layer is located on the back board and extends outwards to the surface of the substrate, a plurality of openings, a plurality of back pole blocking blocks and supporting columns are formed in the back board material layer, the sound holes are exposed in one-to-one correspondence of the openings, the supporting columns and the back pole blocking blocks penetrate through the back poles and extend downwards, and the supporting columns are connected with the vibrating diaphragm. According to the invention, after the second sacrificial layer is formed through conformal deposition, the second sacrificial layer is subjected to grinding treatment, so that the stress of the second sacrificial layer can be effectively released, the upper surface of the second sacrificial layer is a horizontal plane, and adverse effects on subsequent processes caused by cracking of the second sacrificial layer due to overlarge local stress, such as adverse effects such as cracking of a back electrode due to overlarge local stress of a subsequent back electrode material layer, are avoided. Through set up the support column that is located between back of body utmost point and the vibrating diaphragm when setting up fold structure on the vibrating diaphragm, can ensure that MEMS microphone avoids vibrating diaphragm local amplitude too big when having very high detection sensitivity, avoid the vibrating diaphragm damaged and with take place the adhesion between the back of body utmost point, help improving mechanical strength and the performance of MEMS microphone. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (10)
1. A method of manufacturing a MEMS microphone, comprising the steps of:
Providing a substrate, and forming a first sacrificial layer on the substrate;
Patterning the first sacrificial layer to form a first groove corresponding to the vibrating diaphragm;
forming a vibrating diaphragm material layer on the first sacrificial layer, wherein the vibrating diaphragm material layer fills the first groove to form a vibrating diaphragm, and the vibrating diaphragm comprises a fold structure and a bracket positioned on the outer side of the fold structure;
Forming a gas leakage hole in the vibrating diaphragm, wherein the gas leakage hole exposes the first sacrificial layer;
forming a second sacrificial layer by adopting a conformal deposition method, wherein the second sacrificial layer covers the vibrating diaphragm and the air leakage hole, and the upper surface of the formed second sacrificial layer is provided with a concave-convex structure corresponding to the fold structure of the vibrating diaphragm;
Grinding the second sacrificial layer to enable the upper surfaces of the second sacrificial layer to be flush;
etching to form a second groove corresponding to the back electrode blocking piece in the second sacrificial layer, wherein the depth of the second groove corresponding to the back electrode blocking piece is smaller than the height of the second sacrificial layer;
forming a back electrode material layer on the surface of the second sacrificial layer, wherein the back electrode material layer covers the second sacrificial layer and fills the second groove;
etching the back electrode material layer to form a back electrode, wherein a plurality of sound holes are formed in the back electrode, the second grooves of the corresponding back electrode blocking blocks are exposed in the back electrode, and the second sacrificial layer is exposed in the plurality of sound holes;
forming a back plate material layer, wherein the back plate material layer covers the back electrode material layer and fills the sound hole and the second groove;
Removing the backboard material layer correspondingly positioned in the sound hole until the second sacrificial layer is exposed in the sound hole, wherein backboard material filled in the second groove corresponding to the back electrode blocking block forms the back electrode blocking block, and the back electrode blocking block penetrates through the back electrode and extends downwards; forming a cavity in the substrate, the cavity penetrating through the substrate;
Etching the first sacrificial layer and the second sacrificial layer to release the vibrating diaphragm and the back electrode;
wherein, the back electrode blocking block is not arranged above the fold structure.
2. The method of claim 1, further comprising the step of thinning the substrate before forming a cavity in the substrate that extends through the substrate, and thereafter forming the cavity in the thinned substrate.
3. The method of claim 1, wherein the first and second sacrificial layers each comprise silicon oxide, and the second sacrificial layer has a thickness greater than the first sacrificial layer.
4. The method of claim 1, wherein the diaphragm and the back electrode are made of polysilicon, the plurality of vent holes and the support are all formed, and the plurality of vent holes are located between the corrugated structure and the support.
5. The method of claim 1, further comprising forming a dicing street on the periphery of the diaphragm while forming a vent hole in the diaphragm, wherein the dicing street exposes the first sacrificial layer, and wherein the step of etching the corresponding material layer to expose the dicing street is performed during the processing of the second sacrificial layer, the back electrode material layer, and the back plate material layer.
6. The method of claim 1, wherein the material of the back plate material layer comprises silicon nitride, and the back plate material layer extends outward to the surface of the substrate and has a distance from the diaphragm.
7. The method of any one of claims 1-6, further comprising simultaneously forming a second recess of a corresponding support post during etching the second recess of the corresponding back electrode stop in the second sacrificial layer, wherein the second recess of the corresponding support post penetrates the second sacrificial layer, a back plate material subsequently filled in the second recess of the corresponding support post forms the support post, the support post penetrates the back electrode and extends downward to connect with the diaphragm, and the support post is located above the cavity.
8. A MEMS microphone prepared by the method of any one of claims 1-7, comprising:
a substrate having a cavity formed therein that penetrates the substrate;
the vibrating diaphragm is erected on the substrate through a bracket, and a fold structure and a venting hole penetrating through the vibrating diaphragm are formed in the vibrating diaphragm;
The lower surface of the back electrode is a horizontal plane and is positioned above the vibrating diaphragm, the back electrode is spaced from the vibrating diaphragm, and a plurality of sound holes are formed in the back electrode;
The back plate material layer is positioned on the back plate and extends outwards to the surface of the substrate, a plurality of openings, a plurality of back plate blocking blocks and supporting columns are formed in the back plate material layer, the openings are in one-to-one correspondence to expose the sound holes, the supporting columns and the back plate blocking blocks penetrate through the back plate and extend downwards, and the supporting columns are connected with the vibrating diaphragm;
wherein, the back electrode blocking block is not arranged above the fold structure.
9. The MEMS microphone of claim 8, wherein the support post comprises any one of a circular post and a polygonal post.
10. The MEMS microphone of claim 8, wherein the height of the back-pole barrier is 1/4-3/4 of the back-pole-to-diaphragm spacing; the fold structure is an annular structure and is wound on the periphery of the support column.
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| CN114640933B (en) * | 2022-04-20 | 2024-03-29 | 瑶芯微电子科技(上海)有限公司 | MEMS microphone and preparation method thereof |
| CN217363312U (en) * | 2022-04-25 | 2022-09-02 | 瑞声声学科技(深圳)有限公司 | MEMS microphone |
| CN114598979B (en) * | 2022-05-10 | 2022-08-16 | 迈感微电子(上海)有限公司 | Double-diaphragm MEMS microphone and manufacturing method thereof |
| CN115209328A (en) * | 2022-07-05 | 2022-10-18 | 瑶芯微电子科技(上海)有限公司 | MEMS microphone |
| CN218387806U (en) * | 2022-08-26 | 2023-01-24 | 瑞声声学科技(深圳)有限公司 | Microphone chip and microphone |
| CN115867111A (en) * | 2022-11-21 | 2023-03-28 | 潍坊歌尔微电子有限公司 | Sensor chip, manufacturing method thereof, capacitive sensor and electronic device |
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