CN115164861B - MEMS gyroscope and preparation method thereof - Google Patents
MEMS gyroscope and preparation method thereof Download PDFInfo
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
- G01C19/5607—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using vibrating tuning forks
- G01C19/5621—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using vibrating tuning forks the devices involving a micromechanical structure
-
- 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]
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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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C3/00—Assembling of devices or systems from individually processed components
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
- G01C19/5705—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using masses driven in reciprocating rotary motion about an axis
- G01C19/5712—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using masses driven in reciprocating rotary motion about an axis the devices involving a micromechanical structure
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
- G01C19/5719—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using planar vibrating masses driven in a translation vibration along an axis
- G01C19/5733—Structural details or topology
- G01C19/5755—Structural details or topology the devices having a single sensing mass
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- Radar, Positioning & Navigation (AREA)
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- Gyroscopes (AREA)
Abstract
The invention provides a MEMS gyroscope and a preparation method thereof, wherein the MEMS gyroscope comprises a base, a first electrode layer, a second electrode layer, a supporting beam and a mass block; the first electrode layer and the second electrode layer are respectively arranged on the first surface of the base; the support beam is arranged on the first surface of the base; the mass block is arranged at one end of the supporting beam, which is far away from the base, and the projection of the mass block on the base covers the first electrode layer and part of the second electrode layer; comb tooth units are arranged on the mass block and correspond to the first electrode layer; in a driving mode, the first electrode layer and the comb tooth units form a parallel comb tooth capacitor structure; in the detection mode, the second electrode layer and the mass block form a parallel plate capacitor structure. The invention has the technical effects of simple structure, small coupling error caused by the processing technology and improved zero offset stability.
Description
Technical Field
The invention belongs to the technical field of MEMS gyroscopes, and particularly relates to an MEMS gyroscope and a preparation method thereof.
Background
The MEMS gyroscope utilizes the Golgi effect in mechanics, the mass block is subjected to constant amplitude vibration along the driving direction under the action of driving force, when external angular velocity is input, the Golgi force is generated, the mass block is excited to vibrate along the detection direction under the action of the Golgi force, and the amplitude of the detection direction can be read out through a capacitance detection technology, so that the conversion from the angular velocity to an electrical signal is realized. MEMS gyroscopes are becoming a viable alternative to expensive and cumbersome traditional gyroscopes due to their particular advantages of miniaturization, low cost, high reliability, mass production, and integrated circuit compatible integration, and are widely used in many applications ranging from military to civilian applications, such as intelligent robots, computer gaming industries, microsatellites, unmanned aerial vehicles, operating platforms, guided guns, and missiles.
Common MEMS gyroscopes include frame-type, tuning fork, butterfly wing, etc. The butterfly-type MEMS gyroscope has been widely used and studied because of its simple structure, high sensitivity, high precision and long service life. The current common butterfly wing type MEMS gyroscope mainly comprises a structure consisting of a suspension beam, a support beam and a plurality of mass blocks, wherein at least three beam structures are needed in the structure, and the zero bias stability of the gyroscope is reduced due to coupling errors caused by the process of manufacturing a plurality of beam structures.
Disclosure of Invention
The invention aims at solving at least one of the technical problems existing in the prior art and provides a novel technical scheme of an MEMS gyroscope and a preparation method thereof.
According to a first aspect of the present invention there is provided a MEMS gyroscope comprising:
the device comprises a base, a first electrode layer and a second electrode layer, wherein the first electrode layer and the second electrode layer are respectively arranged on the first surface of the base;
the support beam and the mass block are arranged on the first surface of the base; the mass block is arranged at one end of the supporting beam, which is far away from the base, and the projection of the mass block on the base covers the first electrode layer and part of the second electrode layer; comb tooth units are arranged on the mass block and correspond to the first electrode layer;
in a driving mode, the first electrode layer and the comb tooth units form a parallel comb tooth capacitor structure so as to drive the mass block and the supporting beam to perform torsional vibration in a horizontal plane;
in a detection mode, the second electrode layer and the mass block form a parallel plate capacitor structure; when the external angular velocity is input, the mass block and the supporting beam perform bending vibration in a vertical plane, and the parallel plate capacitor structure can detect the amplitude of the bending vibration.
Optionally, the base includes a substrate and an insulating layer;
the insulating layer covers the surface of the substrate, and the first electrode layer, the second electrode layer and the supporting beam are all arranged on the insulating layer.
Optionally, the support beam is arranged between the support beam and the insulating layer, and the support beam is arranged in the middle of the insulating layer.
Optionally, the first electrode layer includes multiunit positive drive electrode and negative drive electrode that mutually support, positive drive electrode includes a plurality of first broachs, negative drive electrode includes a plurality of second broachs, just first broach with the second broach is crisscross to be set up each other.
Optionally, the first electrode layer includes two sets of positive driving electrodes and negative driving electrodes that cooperate with each other, and the two sets of positive driving electrodes and negative driving electrodes that cooperate with each other are symmetrically distributed along a central axis of the support beam.
Optionally, the second electrode layer includes a positive detection electrode and a negative detection electrode; the positive detection electrode and the negative detection electrode are symmetrically distributed along the central axis of the supporting beam.
Optionally, the thickness of the first electrode layer and the second electrode layer is 100nm-500nm, and the thickness of the mass block is 1 μm-20 μm.
Optionally, the materials of the first electrode layer and the second electrode layer are at least one of Ti, au, cu, pt respectively.
According to a second aspect of the present invention, there is provided a method for manufacturing a MEMS gyroscope as described above, comprising the steps of:
step 100, forming an insulating layer in the substrate, forming a base and a supporting beam on the top of the substrate in an etching manner, and exposing the insulating layer;
step 200, preparing a first electrode layer and a second electrode layer on the insulating layer;
step 300, covering protective layers on the surfaces of the insulating layer, the first electrode layer and the second electrode layer;
step 400, covering a sacrificial layer on the surface of the protective layer;
step 500, preparing a mass block on the surface of the sacrificial layer, and etching a plurality of through holes distributed at intervals on the mass block to form comb tooth units;
and 600, sequentially removing the sacrificial layer and the protective layer to obtain the MEMS gyroscope.
Optionally, etching and removing the sacrificial layer with hydrofluoric acid solution, and etching and removing the protective layer with phosphoric acid solution.
The invention has the technical effects that:
in the present embodiment, the MEMS gyroscope operates in two modes, namely a drive mode and a detection mode. In a driving mode, the first electrode layer and the comb tooth units form a parallel comb tooth capacitor structure so as to drive the mass block and the supporting beam to perform torsional vibration in a horizontal plane; in the detection mode, the second electrode layer and the mass block form a parallel plate capacitor structure; when the external angular velocity is input, the mass block and the supporting beam perform bending vibration in a vertical plane, and the parallel plate capacitor structure can detect the amplitude of the bending vibration. Therefore, the torsional vibration in the horizontal plane and the bending vibration in the vertical plane realize decoupling between the driving mode and the detecting mode of the MEMS gyroscope, and meanwhile, the amplitude of the bending vibration in the vertical plane is read out through the differential capacitance generated by the parallel plate capacitor structure, so that the conversion from angular velocity to electric signal is realized.
The MEMS gyroscope realizes a parallel plate capacitor structure by utilizing one supporting beam and one mass block, has a simple structure, has small coupling error caused by a processing technology, and improves zero offset stability. In addition, the MEMS gyroscope adopts a parallel comb capacitor structure to drive and a parallel plate capacitor structure to realize differential capacitance detection, the driving mode is torsional vibration of the supporting beam in a horizontal plane, the detection mode is bending vibration of the supporting beam in a vertical plane, and good decoupling is realized.
In addition, the MEMS gyroscope has the advantages of reasonable structural design, small size, high precision, good consistency, easiness in batch manufacturing, low cost and the like.
Drawings
FIG. 1 is a top view of a MEMS gyroscope according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a first electrode layer and a second electrode layer of a MEMS gyroscope according to an embodiment of the present invention;
FIG. 3 is a cross-sectional view taken along the line A-A in FIG. 1;
FIG. 4 is a schematic diagram of an insulating layer of a MEMS gyroscope according to an embodiment of the present invention;
FIG. 5 is a schematic view of a substrate and support beams of a MEMS gyroscope according to an embodiment of the invention;
FIG. 6 is a schematic diagram of a first electrode layer of a MEMS gyroscope according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a passivation layer of a MEMS gyroscope according to an embodiment of the invention;
FIG. 8 is a schematic diagram of a sacrificial layer of a MEMS gyroscope according to an embodiment of the present invention;
FIG. 9 is a schematic diagram of a MEMS gyroscope mass according to an embodiment of the present invention;
FIG. 10 is a schematic view of a through hole of a MEMS gyroscope proof mass according to an embodiment of the present invention;
FIG. 11 is a schematic diagram of removing a sacrificial layer of a MEMS gyroscope according to an embodiment of the invention.
In the figure: 1. a substrate; 2. an insulating layer; 3. a support beam; 4. a substrate; 5. a first electrode layer; 51. a positive drive electrode; 52. a negative drive electrode; 6. a mass block; 61. a through hole; 62. comb tooth units; 71. a positive detection electrode; 72. a negative detection electrode; 8. a protective layer; 9. and a sacrificial layer.
Detailed Description
Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application unless it is specifically stated otherwise.
Reference will now be made in detail to embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functionality throughout. The embodiments described below by referring to the drawings are exemplary only for the purpose of explaining the present application and are not to be construed as limiting the present application. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.
The features of the terms "first", "second", and the like in the description and in the claims of this application may be used for descriptive or implicit inclusion of one or more such features. In the description of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more. Furthermore, in the description and claims, "and/or" means at least one of the connected objects, and the character "/", generally means that the associated object is an "or" relationship.
In the description of the present application, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," etc. indicate orientations or positional relationships based on the orientations or positional relationships illustrated in the drawings, are merely for convenience in describing the present application and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be configured and operated in a particular orientation, and therefore should not be construed as limiting the present application.
In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art in a specific context.
As shown in fig. 1 to 11, according to a first aspect of the present invention, there is provided a MEMS gyroscope including a base, a first electrode layer 5, a second electrode layer, a support beam 3, and a mass 6. The base is used for fixing the supporting beam 3 and ensuring the stability of fixing the supporting beam 3. The support beams 3 are used to support the mass 6.
Specifically, the first electrode layer 5 and the second electrode layer are respectively disposed on the first surface of the base; the support beam 3 is arranged on the first surface of the base; the mass block 6 is arranged at one end of the supporting beam 3 away from the base, and the projection of the mass block 6 on the base covers the first electrode layer 5 and part of the second electrode layer.
It should be noted that, in general, the projection of the mass 6 onto the base completely covers the first electrode layer 5, so that the driving force is as symmetrical as possible. The projected portion of the mass 6 on the base covers the second electrode layer, reducing cross sensitivity due to the variation of the area of the detection area facing.
Further specifically, the mass block 6 is provided with comb-teeth units 62, and the comb-teeth units 62 correspond to the first electrode layer 5. Wherein, a plurality of spaced elongated through holes 61 may be etched on the mass block 6, and non-etched portions between the plurality of adjacent through holes 61 form comb teeth units 62.
The MEMS gyroscope works in two modes:
in the driving mode, the first electrode layer 5 and the comb teeth unit 62 form a parallel comb teeth capacitor structure to drive the mass block 6 and the support beam 3 to perform torsional vibration in a horizontal plane.
In the detection mode, the second electrode layer and the mass block 6 form a parallel plate capacitor structure; when an external angular velocity is input, the mass block 6 and the supporting beam 3 perform bending vibration in a vertical plane, and the parallel plate capacitor structure can detect the amplitude of the bending vibration.
Therefore, after the driving voltage is applied to the first electrode layer 5, a plurality of groups of tangential electrostatic driving forces are generated by the parallel comb capacitor structure, the supporting beam 3 is acted by torsional moment, and the supporting beam 3 and the mass block 6 do torsional vibration in the horizontal plane, so that the driving mode of the MEMS gyroscope is excited; after the external angular velocity omega along the vertical direction is input, the coriolis force is generated based on the coriolis effect, the supporting beam 3 is acted by the bending moment, and the supporting beam 3 and the mass block 6 do bending vibration in the vertical plane, so that the detection mode of the MEMS gyroscope is excited. The vibration amplitude of the detection mode is read out by the differential capacitance generated by the parallel plate capacitor structure, so that the detection of the diagonal speed is realized.
In the present embodiment, the MEMS gyroscope operates in two modes, namely a drive mode and a detection mode. In the driving mode, the first electrode layer 5 and the comb teeth unit 62 form a parallel comb teeth capacitor structure so as to drive the mass block 6 and the supporting beam 3 to perform torsional vibration in a horizontal plane; in the detection mode, the second electrode layer and the mass block 6 form a parallel plate capacitor structure; when the external angular velocity is input, the mass block 6 and the supporting beam 3 perform bending vibration in a vertical plane, and the parallel plate capacitor structure can detect the amplitude of the bending vibration. Therefore, the torsional vibration in the horizontal plane and the bending vibration in the vertical plane realize decoupling between the driving mode and the detecting mode of the MEMS gyroscope, and meanwhile, the amplitude of the bending vibration in the vertical plane is read out through the differential capacitance generated by the parallel plate capacitor structure, so that the conversion from angular velocity to electric signal is realized.
The MEMS gyroscope realizes a parallel plate capacitor structure by utilizing the supporting beam 3 and the mass block 6, has simple structure, small coupling error caused by a processing technology and improves zero offset stability. In addition, the MEMS gyroscope adopts a parallel comb capacitor structure to drive and a parallel plate capacitor structure to realize differential capacitance detection, the driving mode is torsional vibration of the supporting beam 3 in a horizontal plane, the detection mode is bending vibration of the supporting beam 3 in a vertical plane, and good decoupling is realized.
In addition, the MEMS gyroscope has the advantages of reasonable structural design, small size, high precision, good consistency, easiness in batch manufacturing, low cost and the like.
Optionally, the base comprises a substrate 1 and an insulating layer 2;
the insulating layer 2 covers the surface of the substrate 1, and the first electrode layer 5, the second electrode layer, and the support beam 3 are all disposed on the insulating layer 2.
In the above embodiment, the insulating layer 2 covers the surface of the substrate 1, and the first electrode layer 5, the second electrode layer, and the support beam 3 are provided on the insulating layer 2, so that the insulation between the first electrode layer 5, the second electrode layer, and the support beam 3 and the substrate 1 can be preferably achieved.
Optionally, the MEMS gyroscope further comprises a substrate 4, the substrate 4 is disposed between the support beam 3 and the insulating layer 2, and the substrate 4 is located in the middle of the insulating layer 2. The substrate 4 is used for realizing firm mechanical connection between the support beam 3 and the insulating layer 2, and effectively preventing the support beam 3 from falling off from the insulating layer 2. Meanwhile, the substrate 4 serves as a transition layer, and deformation of the support beam 3 due to thermal mismatch between the insulating layer 2 and the support beam 3 is preferably reduced.
Optionally, the first electrode layer 5 includes a plurality of groups of positive driving electrodes 51 and negative driving electrodes 52 that are mutually matched, the positive driving electrodes 51 include a plurality of first comb teeth, the negative driving electrodes 52 include a plurality of second comb teeth, and the first comb teeth and the second comb teeth are mutually staggered. This helps to form a plurality of parallel comb capacitor structures between the first electrode layer 5 and the comb unit 62, which are capable of generating a plurality of sets of tangential electrostatic driving forces, thereby driving the mass 6 and the support beam 3 to perform torsional vibrations in a horizontal plane.
Alternatively, referring to fig. 2, the first electrode layer 5 includes two sets of mutually matched positive driving electrodes 51 and negative driving electrodes 52, and the two sets of mutually matched positive driving electrodes 51 and negative driving electrodes 52 are symmetrically distributed along the central axis of the support beam 3, that is, the electrode located at the outermost side is the positive driving electrode 51, and the electrode located at the inner side is the negative driving electrode 52. This enables the first electrode layer 5 to form two parallel comb capacitor structures in cooperation with the comb unit 62, and to generate two sets of symmetrical tangential electrostatic driving forces, so that the mass 6 and the support beam 3 can be stably driven to perform torsional vibration in a horizontal plane.
Alternatively, the second electrode layer includes a positive detection electrode 71 and a negative detection electrode 72; the positive detection electrode 71 and the negative detection electrode 72 are symmetrically distributed along the central axis of the support beam 3.
In the above embodiment, the dc drive voltage and the ac drive voltage having the same amplitude and the opposite phase are applied to the two positive drive electrodes 51 and the two negative drive electrodes 52 at the same time, and the ac detection voltage having the same amplitude and the opposite phase is applied to the positive detection electrode 71 and the negative detection electrode 72. The parallel comb capacitor structure not only can well drive the mass block 6 and the supporting beam 3 to perform torsional vibration in the horizontal plane in a driving mode, but also can detect the amplitude of the bending vibration in a detecting mode.
Alternatively, the thickness of the first electrode layer 5 and the second electrode layer is 100nm-500nm, and the thickness of the mass 6 is 1 μm-20 μm. The parallel comb capacitor structure and the parallel flat capacitor structure can be well guaranteed, the size of the MEMS gyroscope can be effectively reduced, and the miniature design of the MEMS gyroscope is realized.
Optionally, the materials of the first electrode layer 5 and the second electrode layer are at least one of Ti, au, cu, pt respectively. This helps to ensure the stability of the function of the first electrode layer 5 and the second electrode layer.
According to a second aspect of the present invention, there is provided a method for manufacturing a MEMS gyroscope, see fig. 3 to 11, for manufacturing the MEMS gyroscope described above, comprising the steps of:
at step 100, an insulating layer 2 is formed inside a substrate 1. For example, a 300 μm thick SOI (Silicon on Insulator, silicon on insulator substrate 1) wafer is selected, the bottom silicon layer of the SOI wafer is used as substrate 1, and the buried oxide layer of the SOI wafer is used as insulator layer 2, thereby facilitating the simplification of the formation of the susceptor.
A base 4 and a support beam 3 are formed on top of the substrate 1 by means of etching and the insulating layer 2 is exposed.
For example, a support beam 3 having a height of 5 μm and a substrate 4 having a thickness of 1 μm are formed in the top silicon layer of the SOI sheet by photolithography and RIE (Reactive Ion Etching ).
Step 200, a first electrode layer 5 and a second electrode layer are prepared on the insulating layer 2.
For example, cr having a thickness of 20nm and Au having a thickness of 180nm were prepared as the first electrode layer 5 and the second electrode layer on the insulating layer 2 by photolithography and magnetron sputtering.
In step 300, the surfaces of the insulating layer 2, the first electrode layer 5 and the second electrode layer are covered with the protective layer 8.
For example, a silicon nitride protective layer having a thickness of 1 μm is prepared on the upper surface of the insulating layer 2 and the outer surfaces of the first electrode layer 5 and the second electrode layer by means of photolithography and PECVD (Plasma Enhanced Chemical Vapor Deposition ) for protecting the insulating layer 2 when the sacrificial layer 9 is removed.
And 400, covering the surface of the protective layer 8 with a sacrificial layer 9.
For example, a silicon oxide layer having a thickness of 5 μm is prepared on the upper surface of the prepared silicon nitride protective layer 8 by means of photolithography and PECVD (Plasma Enhanced Chemical Vapor Deposition, plasma-enhanced chemical vapor deposition), the silicon oxide layer serving as the sacrificial layer 9.
Step 500 of preparing a mass 6 on the surface of the sacrificial layer 9, for example, preparing heavily doped polysilicon as the mass 6 on the upper surface of the prepared sacrificial layer 9 by photolithography and in situ doped LPCVD (Low Pressure Chemical Vapor Deposition ); and a plurality of through holes 61 are etched on the mass block 6 at intervals to form comb teeth units 62;
and 600, sequentially removing the sacrificial layer 9 and the protective layer 8 to obtain the MEMS gyroscope. For example, the sacrificial layer 9 is etched and removed from the side and the through hole 61 with a hydrofluoric acid solution.
The MEMS gyroscope is manufactured by adopting the manufacturing method of the MEMS gyroscope, the process is simple, the MEMS gyroscope with better performance can be manufactured quickly, so that the accurate measurement of the angular velocity is realized, meanwhile, the decoupling between the driving mode and the detection mode of the MEMS gyroscope is realized by torsional vibration in the horizontal plane and bending vibration in the vertical plane, the coupling error caused by the processing process is small, and the zero offset stability is improved; meanwhile, the bending vibration amplitude in the vertical plane is read out through the differential capacitance generated by the parallel plate capacitor structure, so that the conversion from angular velocity to electric signal is realized.
Alternatively, the sacrificial layer 9 is etched and removed using a hydrofluoric acid solution, and the protective layer 8 is etched and removed using a phosphoric acid solution. This can remove the sacrificial layer 9 and the protective layer 8 well, and the removal process can protect the substrate 1 well with high safety.
In a specific embodiment, the material of the substrate 1 is monocrystalline silicon, with a thickness of 200-1000 μm. The material of the insulating layer 2 is silicon dioxide, and the thickness is 1-10 mu m. Referring to fig. 1 to 3, a base 4 is provided at the center of the upper surface of the insulating layer 2, and is the same material as the substrate 1 in thickness of 1-10 μm. Meanwhile, the support beam 3 is provided in the center of the upper surface of the base 4, and is the same as the substrate 1 in thickness of 1-10 μm. The material of the mass block 6 is doped polysilicon. The method is beneficial to ensuring the stability of the functions of the MEMS gyroscope and simultaneously beneficial to realizing the miniaturized design of the MEMS gyroscope and reducing the cost.
It is to be understood that the above embodiments are merely illustrative of the application of the principles of the present invention, but not in limitation thereof. Various modifications and improvements may be made by those skilled in the art without departing from the spirit and substance of the invention, and are also considered to be within the scope of the invention.
Claims (8)
1. A MEMS gyroscope, comprising:
the device comprises a base, a first electrode layer and a second electrode layer, wherein the first electrode layer and the second electrode layer are respectively arranged on the first surface of the base;
the support beam and the mass block are arranged on the first surface of the base; the mass block is arranged at one end of the supporting beam, which is far away from the base, and the projection of the mass block on the base covers the first electrode layer and part of the second electrode layer; comb tooth units are arranged on the mass block and correspond to the first electrode layer;
the first electrode layer comprises a plurality of groups of positive driving electrodes and negative driving electrodes which are matched with each other, the positive driving electrodes comprise a plurality of first comb teeth, the negative driving electrodes comprise a plurality of second comb teeth, and the first comb teeth and the second comb teeth are arranged in a staggered manner;
the second electrode layer comprises a positive detection electrode and a negative detection electrode; the positive detection electrode and the negative detection electrode are symmetrically distributed along the central axis of the supporting beam;
in a driving mode, the first electrode layer and the comb tooth units form a parallel comb tooth capacitor structure so as to drive the mass block and the supporting beam to perform torsional vibration in a horizontal plane;
in a detection mode, the second electrode layer and the mass block form a parallel plate capacitor structure; when the external angular velocity is input, the mass block and the supporting beam perform bending vibration along the vertical plane, and the parallel plate capacitor structure can detect the amplitude of the bending vibration.
2. The MEMS gyroscope of claim 1, wherein the pedestal comprises a substrate and an insulating layer;
the insulating layer covers the surface of the substrate, and the first electrode layer, the second electrode layer and the supporting beam are all arranged on the insulating layer.
3. The MEMS gyroscope of claim 2, further comprising a substrate disposed between the support beam and the insulating layer, and the substrate is located in a middle of the insulating layer.
4. The MEMS gyroscope of claim 1, wherein the first electrode layer includes two sets of cooperating positive and negative drive electrodes, and wherein the two sets of cooperating positive and negative drive electrodes are symmetrically distributed along a central axis of the support beam.
5. The MEMS gyroscope of claim 1, wherein the first electrode layer and the second electrode layer each have a thickness of 100nm-500nm, and the mass has a thickness of 1 μιη -20 μιη.
6. The MEMS gyroscope of claim 1, wherein the material of the first electrode layer and the second electrode layer are each at least one of Ti, au, cu, pt.
7. A method for preparing a MEMS gyroscope according to any of claims 1-6, comprising the steps of:
step 100, forming an insulating layer in the substrate, forming a base and a supporting beam on the top of the substrate in an etching manner, and exposing the insulating layer;
step 200, preparing a first electrode layer and a second electrode layer on the insulating layer;
step 300, covering protective layers on the surfaces of the insulating layer, the first electrode layer and the second electrode layer;
step 400, covering a sacrificial layer on the surface of the protective layer;
step 500, preparing a mass block on the surface of the sacrificial layer, and etching a plurality of through holes distributed at intervals on the mass block to form comb tooth units;
and 600, sequentially removing the sacrificial layer and the protective layer to obtain the MEMS gyroscope.
8. The method of manufacturing a MEMS gyroscope of claim 7, wherein the sacrificial layer is etched and removed using a hydrofluoric acid solution and the protective layer is etched and removed using a phosphoric acid solution.
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