CN117303307A - MEMS device and manufacturing method thereof - Google Patents
MEMS device and manufacturing method thereof Download PDFInfo
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- CN117303307A CN117303307A CN202311348658.7A CN202311348658A CN117303307A CN 117303307 A CN117303307 A CN 117303307A CN 202311348658 A CN202311348658 A CN 202311348658A CN 117303307 A CN117303307 A CN 117303307A
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 33
- 239000000758 substrate Substances 0.000 claims abstract description 163
- 238000005530 etching Methods 0.000 claims abstract description 8
- 238000000034 method Methods 0.000 claims description 32
- 230000008569 process Effects 0.000 claims description 10
- 229910021421 monocrystalline silicon Inorganic materials 0.000 claims description 9
- 230000000903 blocking effect Effects 0.000 claims description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 6
- 229910052760 oxygen Inorganic materials 0.000 claims description 6
- 239000001301 oxygen Substances 0.000 claims description 6
- 238000005468 ion implantation Methods 0.000 claims description 5
- 238000000137 annealing Methods 0.000 claims description 3
- 230000035945 sensitivity Effects 0.000 abstract description 11
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 14
- 229920005591 polysilicon Polymers 0.000 description 10
- 230000000149 penetrating effect Effects 0.000 description 7
- 235000012431 wafers Nutrition 0.000 description 6
- 239000002245 particle Substances 0.000 description 4
- 238000000708 deep reactive-ion etching Methods 0.000 description 3
- 239000007772 electrode material Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 229920002120 photoresistant polymer Polymers 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 239000013081 microcrystal Substances 0.000 description 2
- 229910052814 silicon oxide Inorganic materials 0.000 description 2
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- 229910000530 Gallium indium arsenide Inorganic materials 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- KXNLCSXBJCPWGL-UHFFFAOYSA-N [Ga].[As].[In] Chemical compound [Ga].[As].[In] KXNLCSXBJCPWGL-UHFFFAOYSA-N 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000001312 dry etching Methods 0.000 description 1
- 238000000605 extraction Methods 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
- 230000010354 integration Effects 0.000 description 1
- 238000004377 microelectronic Methods 0.000 description 1
- 238000005459 micromachining Methods 0.000 description 1
- 238000001259 photo etching Methods 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
- B81C1/00158—Diaphragms, membranes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
- B81B7/02—Microstructural systems; Auxiliary parts of microstructural devices or systems containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS]
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00023—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems without movable or flexible elements
- B81C1/00047—Cavities
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00436—Shaping materials, i.e. techniques for structuring the substrate or the layers on the substrate
- B81C1/005—Bulk micromachining
- B81C1/00507—Formation of buried layers by techniques other than deposition, e.g. by deep implantation of elements
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00436—Shaping materials, i.e. techniques for structuring the substrate or the layers on the substrate
- B81C1/00523—Etching material
- B81C1/00531—Dry etching
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00436—Shaping materials, i.e. techniques for structuring the substrate or the layers on the substrate
- B81C1/00523—Etching material
- B81C1/00539—Wet etching
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- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Computer Hardware Design (AREA)
- Micromachines (AREA)
Abstract
The invention provides a MEMS device and a manufacturing method thereof. The manufacturing method of the MEMS device comprises the following steps: providing a substrate; forming a buried layer in the substrate, wherein a preset distance is reserved between the buried layer and the top surface of the substrate, and the substrate above the buried layer is used as a vibrating diaphragm; etching the substrate from the back side of the substrate and stopping at the surface of the buried layer to form a back cavity in the substrate; and removing at least part of the buried layer through the back cavity to form a first cavity, wherein the first cavity releases the vibrating diaphragm to be close to the surface of the back cavity. Therefore, the vibrating diaphragm and the substrate are of an integrated structure, the probability of vibrating diaphragm layering can be reduced, the reliability of the MEMS device can be improved, and the sensitivity of the MEMS device can be improved. The MEMS device comprises a substrate, a back cavity, a first cavity and a diaphragm, wherein the substrate of the MEMS device is provided with the first cavity and the back cavity, the first cavity is positioned in the substrate, the back cavity is positioned on one side of the first cavity close to the back surface of the substrate and is communicated with the first cavity, the part of the top of the substrate spans over the first cavity, and the part of the top of the substrate spans over the first cavity is used as the diaphragm of the MEMS device.
Description
Technical Field
The invention relates to the technical field of micro-electromechanical systems, in particular to an MEMS device and a manufacturing method thereof.
Background
MEMS (Micro-Electro-Mechanical System) devices refer to components fabricated using microelectronics and micromachining techniques that offer the advantages of miniaturization, integration, intelligence, multiple functions, and low cost.
Fig. 1 to 8 are schematic views showing a step structure of a method for manufacturing a MEMS device according to the prior art. The manufacturing method of the MEMS device comprises the following steps: as shown in fig. 1, a first oxide layer 102 is formed on a top surface of a substrate 101; as shown in fig. 2, a polysilicon diaphragm 103 is formed on the first oxide layer 102; as shown in fig. 3, a second oxide layer 104 is formed on the polysilicon diaphragm 103, and the second oxide layer 104 covers the exposed first oxide layer 102; as shown in fig. 4, a third oxide layer 105 is formed on the second oxide layer 104, the third oxide layer 105 covering the second oxide layer 104; as shown in fig. 4, a back electrode conductive layer 106 is formed on the third oxide layer 105; as shown in fig. 5, a back electrode insulating layer 107 is formed on the back electrode conductive layer 106, a portion of the back electrode conductive layer 106 is exposed from the back electrode insulating layer 107 side, and a release hole 107a exposing the third oxide layer 105 is formed in the back electrode insulating layer 107; as shown in fig. 5, a part of the third oxide layer 105 and a part of the second oxide layer 104 are removed, exposing a part of the polysilicon diaphragm 103; as shown in fig. 6, a first conductive layer 108 is formed on the exposed polysilicon diaphragm 103, and a second conductive layer 109 is formed on the exposed back electrode conductive layer 106; as shown in fig. 7, the substrate 101 is etched from the back surface of the substrate 101 to form a back cavity 101a, the back cavity 101a penetrating the substrate 101; as shown in fig. 8, the polysilicon diaphragm 103 is released by removing part of the first oxide layer 102, part of the second oxide layer 104, and part of the third oxide layer 105 through the back cavity 101a and the release hole 107 a.
The MEMS device manufactured by the manufacturing method of the MEMS device has the following problems: because the diaphragm is made of polysilicon, the polysilicon diaphragm has high residual stress and poor consistency, so that the sensitivity of the diaphragm is lower, and the sensitivity of the MEMS device is lower; the fixation of the polysilicon diaphragm 103 and the oxide layer depends on the binding force between the film layers, so that the polysilicon diaphragm 103 and the oxide layer are easy to delaminate when the MEMS device bears larger pressure, and the reliability of the MEMS device is affected.
Disclosure of Invention
An object of the present invention is to provide a MEMS device and a method of manufacturing the same, which can improve sensitivity and reliability of the MEMS device.
In order to achieve the above object, an aspect of the present invention provides a method for manufacturing a MEMS device, including: providing a substrate; forming a buried layer in the substrate, wherein a preset distance is reserved between the buried layer and the top surface of the substrate, and the substrate above the buried layer is used as a vibrating diaphragm; etching the substrate from the back side of the substrate and stopping at the surface of the buried layer to form a back cavity in the substrate; and removing at least part of the buried layer through the back cavity to form a first cavity, wherein the first cavity releases the vibrating diaphragm to be close to the surface of the back cavity.
Optionally, the method for forming the buried layer in the substrate includes: and implanting oxygen into the substrate through an ion implantation process, and annealing the substrate to form the buried layer.
Optionally, in the step of forming a buried layer in the substrate, a width of the buried layer is smaller than a width of the substrate.
Optionally, the method for manufacturing the MEMS device further includes: forming a sacrificial layer on the top surface of the substrate after forming a buried layer in the substrate and before forming a back cavity in the substrate, wherein the sacrificial layer covers the area where the buried layer is located; forming a back electrode conductive layer on the sacrificial layer; and forming a back electrode insulating layer on the back electrode conducting layer, wherein the back electrode insulating layer covers part of the back electrode conducting layer, the other part of the back electrode conducting layer is exposed out of the side edge of the back electrode insulating layer, a plurality of release holes are formed in the back electrode insulating layer, and the release holes penetrate through the back electrode insulating layer and expose out of the sacrificial layer.
Optionally, the method for manufacturing the MEMS device further includes: after a back cavity in the substrate is formed, part of the sacrificial layer is removed through the plurality of release holes, a second cavity is formed between the back electrode conductive layer and the vibrating diaphragm, and the second cavity releases the vibrating diaphragm away from the surface of the back cavity.
Optionally, the method for forming the sacrificial layer on the top surface of the substrate includes: forming a first sacrificial layer on the top surface of the substrate, wherein the first sacrificial layer covers the top surface of the substrate; forming a first groove in the first sacrificial layer, wherein the bottom surface of the first groove is positioned on the top surface of the substrate; and forming a second sacrificial layer on the first sacrificial layer, wherein the second sacrificial layer covers the first sacrificial layer and forms a second groove at the position of the first groove.
Optionally, in the step of forming a back electrode insulating layer on the back electrode conductive layer, the back electrode insulating layer fills up the second groove, and a portion of the back electrode insulating layer, which is filled up with the second groove, is used as a blocking piece, and the blocking piece prevents the vibrating diaphragm from contacting the back electrode conductive layer in the vibrating process of the vibrating diaphragm.
Optionally, the method for manufacturing the MEMS device further includes: removing a portion of the sacrificial layer from a top surface side of the substrate after forming a back electrode insulating layer on the back electrode conductive layer and before forming a back cavity in the substrate, exposing a portion of the top surface of the substrate; and forming a first conductive layer on the back electrode conductive layer exposed from the side edge of the back electrode insulating layer, and forming a second conductive layer on the exposed top surface of the substrate, wherein the first conductive layer is electrically connected with the back electrode conductive layer, and the second conductive layer is electrically connected with the vibrating diaphragm.
Optionally, the substrate is made of monocrystalline silicon.
In another aspect of the present invention, there is provided a MEMS device, the MEMS device including a substrate, the substrate having a first cavity therein and a back cavity, the first cavity being located inside the substrate, the back cavity being located on a side of the first cavity near a back surface of the substrate, the back cavity penetrating the first cavity and the back cavity penetrating the back surface of the substrate, a portion of a top of the substrate spanning over the first cavity, and a portion of the top of the substrate spanning over the first cavity serving as a diaphragm of the MEMS device.
In the MEMS device and the manufacturing method thereof provided by the invention, a buried layer is formed in a substrate, a preset distance is reserved between the buried layer and the top surface of the substrate, the substrate above the buried layer is used as a vibrating diaphragm, then the substrate is etched from one side of the back surface of the substrate and stops on the surface of the buried layer, a back cavity positioned in the substrate is formed, at least part of the buried layer is removed through the back cavity to form a first cavity, and the vibrating diaphragm is released by the first cavity to be close to the surface of the back cavity. Therefore, a part of the top of the substrate is used as the vibrating diaphragm, or the vibrating diaphragm and the substrate are of an integrated structure, compared with a structure that the vibrating diaphragm is arranged between oxide layers, the probability of layering of the vibrating diaphragm can be reduced, and the reliability of the MEMS device is improved. In addition, as the structures of the monocrystalline silicon wafers are orderly arranged and have long-range order, and the small particles are orderly arranged in the polycrystalline silicon, the crystal boundaries are arranged among the small particles, and the defects of microcrystals and impurities exist, compared with the polycrystalline silicon, the residual stress of the monocrystalline silicon wafers is small and the consistency is good; the substrate is made of monocrystalline silicon, and the substrate part is used as the vibrating diaphragm, so that the obtained vibrating diaphragm has small residual stress and good consistency, the sensitivity of the vibrating diaphragm is high, and the sensitivity of the MEMS device can be further improved.
Drawings
Fig. 1 to 8 are schematic views showing a step structure of a method for manufacturing a MEMS device according to the prior art.
Fig. 9 is a flowchart of a method for manufacturing a MEMS device according to an embodiment of the present invention.
Fig. 10 to 19 are schematic views illustrating a step structure of a method for manufacturing a MEMS device according to an embodiment of the invention.
Reference numerals illustrate:
(fig. 1 to 8) 101-substrate; 101 a-a back cavity; 102-a first oxide layer; 103-vibrating diaphragm; 104-a second oxide layer; 105-a third oxide layer; 106-a back electrode conductive layer; 107-a back electrode insulating layer; 107 a-a release hole; 108-a first conductive layer; 109-a second conductive layer;
(fig. 10 to 19) 201-substrate; 201 a-a diaphragm; 201 b-a first via; 201 c-back cavity; 202-a buried layer; 203-a first sacrificial layer; 203 a-a first groove; 204-a second sacrificial layer; 204 a-a second groove; 205-a back electrode conductive layer; 206-a back electrode insulating layer; 206 a-a release hole; 206 b-a blocking block; 207-a first conductive layer; 208-a second conductive layer; 209-a first cavity; 210-a second cavity.
Detailed Description
The MEMS device and the method for fabricating the same according to the present invention are described in further detail below with reference to the accompanying drawings and specific examples. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for convenience and clarity in aiding in the description of embodiments of the invention.
In order to improve the sensitivity and reliability of the MEMS device, the present embodiment provides a MEMS device and a method for manufacturing the same.
Fig. 9 is a flowchart of a method for manufacturing a MEMS device according to an embodiment of the present invention. As shown in fig. 9, the method for manufacturing the MEMS device provided in this embodiment includes:
step S1, providing a substrate;
s2, forming a buried layer in the substrate, wherein a preset distance is reserved between the buried layer and the top surface of the substrate, and the substrate above the buried layer is used as a vibrating diaphragm;
step S3, etching the substrate from the back side of the substrate and stopping at the surface of the buried layer to form a back cavity in the substrate; and
and S4, removing at least part of the buried layer through the back cavity to form a first cavity, and releasing the vibrating diaphragm from the first cavity to be close to the surface of the back cavity.
It should be understood that, although the steps in the flowchart of fig. 9 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least a portion of the steps in fig. 9 may include a plurality of steps or stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of the execution of the steps or stages is not necessarily sequential, but may be performed in rotation or alternately with at least a portion of the steps or stages in other steps or other steps.
Fig. 10 to 19 are schematic views illustrating a step structure of a method for manufacturing a MEMS device according to an embodiment of the invention. The method of manufacturing the MEMS device of the present embodiment will be described below with reference to fig. 9 and 10 to 19.
As shown in fig. 10, step S1 is performed to provide a substrate 201, the substrate 201 having a top surface and a back surface facing opposite directions.
As shown in fig. 11, step S2 is performed to form a buried layer 202 in a substrate 201 with a predetermined distance between the buried layer 202 and the top surface of the substrate 201, with the substrate above the buried layer 202 as a diaphragm 201a.
In this embodiment, the predetermined distance between the buried layer 202 and the top surface of the substrate 201 may be 400nm to 800nm, or the thickness of the diaphragm 201a may be 400nm to 800nm, but is not limited thereto.
In this embodiment, the method for forming the buried layer 202 in the substrate 201 may be: oxygen is implanted into the substrate 201 by an ion implantation process (IMP), and the substrate 201 is annealed, and the implanted oxygen diffuses during the annealing to form the buried layer 202. Illustratively, oxygen may be implanted into the substrate 201 from a top surface side of the substrate 201, such that the depth of the ion implantation is relatively shallow; oxygen may be injected into the substrate 201 from the rear surface side of the substrate 201, so that the influence of the ion implantation process on the diaphragm 201a can be avoided. In other embodiments, buried layers may also be formed in the substrate by other methods known in the art.
Referring to fig. 11, the width (W) of the buried layer 202 may be smaller than the width of the substrate 201, so that the buried layer 202 may be subsequently removed while stopping on the surface of the substrate 201 without cutting through the substrate, thereby facilitating control of the process. Illustratively, the buried layer 202 may have a thickness (D) of 0.8 μm to 2 μm, but is not limited thereto.
In this embodiment, the substrate 201 is a monocrystalline silicon wafer, and the monocrystalline silicon wafer structures are orderly arranged and have long-range order, so that when the portion of the substrate 201 is used as the diaphragm 201a, the residual stress of the diaphragm 201a is small and the consistency is good, so that the sensitivity of the diaphragm 201a is high, and the sensitivity of the MEMS device can be improved. In other embodiments, the substrate 201 may also be a germanium substrate, a silicon carbide substrate, a gallium arsenide substrate, an indium gallium arsenide substrate, or the like.
Illustratively, the buried layer 202 may be a silicon oxide layer.
As shown in fig. 12, a first through hole 201b is formed in the diaphragm 201a, the first through hole 201b exposing the buried layer 202.
Specifically, a patterned photoresist layer may be formed on the top surface of the substrate 201, where the patterned photoresist layer defines a formation position of the first through hole 201b, and then, with the patterned photoresist layer as a mask, the diaphragm 201a is etched and stopped on the surface of the buried layer 202, so as to form the first through hole 201b penetrating through the diaphragm 201a. The number of the first through holes 201b in the diaphragm 201a may be plural.
Next, a sacrificial layer is formed on the top surface of the substrate 201, the sacrificial layer covering the region where the buried layer 202 is located. As shown in fig. 13 and 14, the sacrificial layer may include a first sacrificial layer 203 and a second sacrificial layer 204 stacked.
Specifically, as shown in fig. 13, a first sacrificial layer 203 is formed on the top surface of a substrate 201, the first sacrificial layer 203 covering the top surface of the substrate 201; forming a first groove 203a in the first sacrificial layer 203 by adopting photoetching and etching processes, wherein the bottom surface of the first groove 203a is positioned on the top surface of the substrate 201; as shown in fig. 14, a second sacrificial layer 204 is formed on the first sacrificial layer 203, the second sacrificial layer 204 conformally covering the first sacrificial layer 203 and forming a plurality of second grooves 204a at the positions of the plurality of first grooves 203 a.
Illustratively, the materials of the first sacrificial layer 203 and the second sacrificial layer 204 may be the same, for example, both are silicon oxide layers.
As shown in fig. 15, a back electrode conductive layer 205 is formed on the sacrificial layer.
Specifically, a back electrode material layer may be formed on the second sacrificial layer 204, where the back electrode material layer covers the second sacrificial layer 204; the back electrode material layer is then patterned to form a back electrode conductive layer 205. Illustratively, the material of the back electrode conductive layer 205 includes, but is not limited to, polysilicon. As shown in fig. 15, the back electrode conductive layer 205 has a window therein corresponding to the position of the second groove 204a.
As shown in fig. 16, a back electrode insulating layer 206 is formed on the back electrode conductive layer 205, the back electrode insulating layer 206 covers a part of the back electrode conductive layer 205 and another part of the back electrode conductive layer 205 is exposed from a side edge of the back electrode insulating layer 206, the back electrode insulating layer 206 further has a plurality of release holes 206a, and the release holes 206a penetrate through the back electrode insulating layer 206 and expose the second sacrificial layer 204. Illustratively, the material of the back electrode insulating layer 206 includes, but is not limited to, silicon nitride.
Referring to fig. 16, the back electrode insulating layer 206 fills the second groove 204a, and a portion of the back electrode insulating layer 206 filled with the second groove 204a is used as a blocking block 206b, where the blocking block 206b prevents the diaphragm 201a from contacting the back electrode conductive layer 205 during the vibration of the diaphragm 201a.
Note that, as shown in fig. 13, the etching of the first sacrificial layer 203 to form the plurality of first grooves 203a may stop on the top surface of the substrate 201, so that the depth uniformity of the first grooves 203a is good, and as shown in fig. 14, the depth uniformity of the second grooves 204a formed on the first grooves 203a is also good, and as shown in fig. 16, the height uniformity of the barrier blocks 206b formed in the second grooves 204a is also good.
Referring to fig. 16, the back electrode insulating layer 206 also exposes an edge portion on the side of the second sacrificial layer 204, and after the back electrode insulating layer 206 is formed, a portion of the second sacrificial layer 204 and the first sacrificial layer 203 are removed from the top surface side of the substrate 201, exposing a portion of the top surface of the substrate 201.
Next, as shown in fig. 17, a first conductive layer 207 is formed on the back electrode conductive layer 205 exposed from the side of the back electrode insulating layer 206, and a second conductive layer 208 is formed on the exposed top surface of the substrate 201, the first conductive layer 207 being electrically connected to the back electrode conductive layer 205, the second conductive layer 208 being electrically connected to the substrate 201 to be electrically connected to the diaphragm 201a, whereby extraction of the diaphragm 201a is achieved. In some embodiments, the first conductive layer 207 may also cover the sidewalls of its adjacent back electrode insulation layer 206 and extend to cover a portion of the back electrode insulation layer 206 surface; the second conductive layer 208 may cover sidewalls of the adjacent first sacrificial layer 203, second sacrificial layer 204, and back electrode insulating layer 206 and extend to cover a portion of the surface of the back electrode insulating layer 206.
As shown in fig. 18, step S3 is performed to etch the substrate 201 from the back surface side of the substrate 201 and stop on the surface of the buried layer 202, forming a back cavity 201c in the substrate 201.
In this application, referring to fig. 18, the back cavity 201c does not penetrate through the substrate 201, the back cavity 201c corresponds to the buried layer 202, and the width of the back cavity 201c is smaller than the width of the buried layer 202. In other embodiments, the width of the back cavity 201c may be equal to or greater than the width of the buried layer 202.
Illustratively, the substrate 201 may be etched using a deep reactive ion etching process (Deep Reactive Ion Etching, abbreviated as DRIE, one of the dry etching processes) or other suitable etching process to form the back cavity 201c.
As shown in fig. 19, step S4 is performed, where at least a portion of the buried layer 202 is removed through the back cavity 201c to form a first cavity 209, and the first cavity 209 exposes a surface of the diaphragm 201a near the back cavity 201c to release the surface of the diaphragm 201a near the back cavity 201c. After step S4 is performed, the diaphragm 201a spans over the first cavity 209.
Referring to fig. 19, in this embodiment, the entire buried layer 202 may be removed and stopped on the inner surface of the substrate 201, and the first cavity 209 may be formed at the position of the buried layer 202. In other embodiments, the central region of the buried layer 202 may also be removed while the edge regions of the buried layer 202 remain.
While step S4 is being performed, a portion of the second sacrificial layer 204 and a portion of the first sacrificial layer 203 may be removed through the plurality of release holes 206a in the backplate insulating layer 206, forming a second cavity 210 between the backplate conductive layer 205 and the diaphragm 201a, the second cavity 210 releasing the diaphragm 201a away from the surface of the backplate cavity 201c.
Illustratively, the entire film layer including the substrate 201 and the upper portion thereof may be immersed in an etching solution to remove the buried layer 202, a portion of the second sacrificial layer 204, and a portion of the first sacrificial layer 203 to form the first cavity 209 and the second cavity 210.
The embodiment also provides a MEMS device which can be manufactured by the manufacturing method of the MEMS device.
Referring to fig. 19, the MEMS device provided in this embodiment includes a substrate 201, where the substrate 201 has a first cavity 209 and a back cavity 201c, the first cavity 209 is located inside the substrate 201, the back cavity 201c is located on a side of the first cavity 209 near the back of the substrate 201, the back cavity 201c penetrates through the first cavity 209 and the back cavity 201c penetrates through the back of the substrate 201, and a portion of the top of the substrate 201 spans over the first cavity 209, and a portion of the top of the substrate 201 spanning over the first cavity 209 is used as a diaphragm 201a of the MEMS device.
In this embodiment, the first cavity 209 releases the diaphragm 201a near the surface of the back cavity 201 c; the first cavity 209 is formed by removing the buried layer within the substrate 201. In the present embodiment, the width of the first cavity 209 is larger than the width of the back cavity 201c, but is not limited thereto. In other embodiments, the width of the first cavity 209 may be equal to or less than the width of the back cavity 201c.
The diaphragm 201a may have a first through hole 201b penetrating the diaphragm 201a, and the number of the first through holes 201b may be plural.
The MEMS device may further comprise a sacrificial layer and a back electrode conductive layer 205.
The sacrificial layer is located on the top surface of the substrate 201, and the sacrificial layer may include a first sacrificial layer 203 located on the top surface of the substrate 201 and a second sacrificial layer 204 located on the first sacrificial layer 203.
The back electrode conductive layer 205 is located on the second sacrificial layer 204, and a second cavity 210 is located between the back electrode conductive layer 205 and the diaphragm 201a, and the second cavity 210 penetrates through the second sacrificial layer 204 and the first sacrificial layer 203 and releases the diaphragm 201a away from the surface of the back cavity 201c.
The MEMS device may further comprise a back electrode insulating layer 206, the back electrode insulating layer 206 being located on the back electrode conductive layer 205 and covering a portion of the back electrode conductive layer 205, another portion of the back electrode conductive layer 205 protruding from a side of the back electrode insulating layer.
The back electrode insulating layer 206 further has a blocking block 206b penetrating the back electrode conductive layer 205 and protruding into the second cavity 210, the blocking block 206b preventing the diaphragm 201a from contacting the back electrode conductive layer 205 during vibration of the diaphragm 201a.
The back electrode insulating layer 20 further has a plurality of release holes 206a penetrating the second cavity 210. Illustratively, the MEMS device of the present embodiment is a MEMS microphone, and the release hole 206a and the first through hole 201b in the diaphragm 201a are both air holes of the device.
A first conductive layer 207 is formed on the back electrode conductive layer 205 protruding from a side of the back electrode insulating layer 206, and the first conductive layer 207 is electrically connected to the back electrode conductive layer 205.
A portion of the top surface of the substrate 201 is located outside the second cavity 210 and extends beyond the sides of the first sacrificial layer 203 and the second sacrificial layer 204, and a second conductive layer 208 is formed on the top surface of the substrate located outside the second cavity 210 and extends beyond the sides of the first sacrificial layer 203 and the second sacrificial layer 204, and the second conductive layer 208 is electrically connected to the diaphragm 201a.
In the MEMS device and the method for manufacturing the same provided in this embodiment, the buried layer 202 is formed in the substrate 201, a predetermined distance is provided between the buried layer 202 and the top surface of the substrate 201, the substrate 201 above the buried layer 202 is used as the diaphragm 201a, then the substrate is etched from the back side of the substrate 201 and stopped on the surface of the buried layer 202, a back cavity 201c located in the substrate 201 is formed, then at least part of the buried layer 202 is removed through the back cavity 201c to form the first cavity 209, and the diaphragm 201a is released by the first cavity 209 to be close to the surface of the back cavity 201c. In this way, the part of the top of the substrate 201 is used as the diaphragm 201a, or the diaphragm 201a and the substrate 201 are in an integrated structure, compared with the structure that the diaphragm is arranged between oxide layers, the probability of layering of the diaphragm 201a can be reduced, and the reliability of the MEMS device can be improved. In addition, as the structures of the monocrystalline silicon wafers are orderly arranged and have long-range order, and the small particles are orderly arranged in the polycrystalline silicon, the crystal boundaries are arranged among the small particles, and the defects of microcrystals and impurities exist, compared with the polycrystalline silicon, the residual stress of the monocrystalline silicon wafers is small and the consistency is good; in the invention, the part of the substrate 201 is used as the vibrating diaphragm 201a, so that the obtained vibrating diaphragm 201a has small residual stress and good consistency, the sensitivity of the vibrating diaphragm 201a is high, and the sensitivity of the MEMS device can be further improved.
It should be noted that, in the present description, the differences between the parts described in the following description and the parts described in the previous description are emphasized, and the same or similar parts are referred to each other.
The foregoing description is only illustrative of the preferred embodiments of the present invention, and is not intended to limit the scope of the claims, and any person skilled in the art may make any possible variations and modifications to the technical solution of the present invention using the method and technical content disclosed above without departing from the spirit and scope of the invention, so any simple modification, equivalent variation and modification made to the above embodiments according to the technical matter of the present invention fall within the scope of the technical solution of the present invention.
Claims (10)
1. A method of fabricating a MEMS device, comprising:
providing a substrate;
forming a buried layer in the substrate, wherein a preset distance is reserved between the buried layer and the top surface of the substrate, and the substrate above the buried layer is used as a vibrating diaphragm;
etching the substrate from the back side of the substrate and stopping at the surface of the buried layer to form a back cavity in the substrate; and
and removing at least part of the buried layer through the back cavity to form a first cavity, and releasing the vibrating diaphragm from the first cavity to be close to the surface of the back cavity.
2. The method of fabricating a MEMS device of claim 1, wherein the method of forming a buried layer within the substrate comprises: and implanting oxygen into the substrate through an ion implantation process, and annealing the substrate to form the buried layer.
3. The method of fabricating a MEMS device according to claim 1, wherein in the step of forming a buried layer within the substrate, a width of the buried layer is smaller than a width of the substrate.
4. The method of fabricating a MEMS device according to claim 1, further comprising:
forming a sacrificial layer on the top surface of the substrate after forming a buried layer in the substrate and before forming a back cavity in the substrate, wherein the sacrificial layer covers the area where the buried layer is located;
forming a back electrode conductive layer on the sacrificial layer; and
and forming a back electrode insulating layer on the back electrode conducting layer, wherein the back electrode insulating layer covers part of the back electrode conducting layer, the other part of the back electrode conducting layer is exposed out of the side edge of the back electrode insulating layer, a plurality of release holes are formed in the back electrode insulating layer, and the release holes penetrate through the back electrode insulating layer and are exposed out of the sacrificial layer.
5. The method of fabricating a MEMS device according to claim 4, further comprising:
after a back cavity in the substrate is formed, part of the sacrificial layer is removed through the plurality of release holes, a second cavity is formed between the back electrode conductive layer and the vibrating diaphragm, and the second cavity releases the vibrating diaphragm away from the surface of the back cavity.
6. The method of fabricating a MEMS device according to claim 4, wherein the method of forming a sacrificial layer on the top surface of the substrate comprises:
forming a first sacrificial layer on the top surface of the substrate, wherein the first sacrificial layer covers the top surface of the substrate;
forming a first groove in the first sacrificial layer, wherein the bottom surface of the first groove is positioned on the top surface of the substrate; and
a second sacrificial layer is formed on the first sacrificial layer, the second sacrificial layer covers the first sacrificial layer and a second groove is formed at the position of the first groove.
7. The method of manufacturing a MEMS device according to claim 6, wherein in the step of forming a back electrode insulating layer on the back electrode conductive layer, the back electrode insulating layer fills the second recess, and a portion of the back electrode insulating layer that fills the second recess serves as a blocking piece that prevents the diaphragm from contacting the back electrode conductive layer during vibration of the diaphragm.
8. The method of fabricating a MEMS device according to claim 4, further comprising:
removing a portion of the sacrificial layer from a top surface side of the substrate after forming a back electrode insulating layer on the back electrode conductive layer and before forming a back cavity in the substrate, exposing a portion of the top surface of the substrate; and
and forming a first conductive layer on the back electrode conductive layer exposed from the side edge of the back electrode insulating layer, and forming a second conductive layer on the exposed top surface of the substrate, wherein the first conductive layer is electrically connected with the back electrode conductive layer, and the second conductive layer is electrically connected with the vibrating diaphragm.
9. The method of manufacturing a MEMS device as claimed in any one of claims 1 to 8, wherein the substrate is made of monocrystalline silicon.
10. The MEMS device is characterized by comprising a substrate, wherein a first cavity and a back cavity are arranged in the substrate, the first cavity is positioned in the substrate, the back cavity is positioned on one side, close to the back surface of the substrate, of the first cavity, the back cavity is communicated with the first cavity, the back cavity penetrates through the back surface of the substrate, a part of the top of the substrate spans over the first cavity, and the part of the top of the substrate spans over the first cavity is used as a vibrating diaphragm of the MEMS device.
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| CN202311348658.7A CN117303307A (en) | 2023-10-18 | 2023-10-18 | MEMS device and manufacturing method thereof |
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| CN202311348658.7A CN117303307A (en) | 2023-10-18 | 2023-10-18 | MEMS device and manufacturing method thereof |
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| CN117303307A true CN117303307A (en) | 2023-12-29 |
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