CN109036910B - Method for manufacturing micro-mechanical universal switch - Google Patents
Method for manufacturing micro-mechanical universal switch Download PDFInfo
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- CN109036910B CN109036910B CN201810871365.XA CN201810871365A CN109036910B CN 109036910 B CN109036910 B CN 109036910B CN 201810871365 A CN201810871365 A CN 201810871365A CN 109036910 B CN109036910 B CN 109036910B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H11/00—Apparatus or processes specially adapted for the manufacture of electric switches
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H35/00—Switches operated by change of a physical condition
- H01H35/14—Switches operated by change of acceleration, e.g. by shock or vibration, inertia switch
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Abstract
The invention discloses a manufacturing method of a micro-mechanical universal switch, which comprises the following steps: the SOI wafer comprises a thick silicon layer, a silicon dioxide insulating layer and a thin silicon layer from top to bottom; the manufacturing method comprises the following steps: manufacturing a layer of metal on the upper surface of the thick silicon layer through an electroplating process to be used as a moving electrode; manufacturing the mass block and the spiral spring beam in the thick silicon layer through a deep silicon etching process; etching a plurality of release holes in the thin silicon layer by a deep silicon etching process, and taking the formed hollow structure as a substrate; processing the silicon dioxide insulating layer by a hydrofluoric acid etching process, and releasing the mass block and the spiral spring beam to form a movable structure; processing fixed electrodes with different heights on the upper surface of the sealing cap layer; and aligning the processed SOI wafer with the sealing cap layer for hot-pressing bonding packaging. The micro-mechanical switch obtained by the manufacturing method realizes universal triggering within the axial range of 0-90 degrees.
Description
Technical Field
The invention belongs to the technical field of micro-machining, and particularly relates to a manufacturing method of a micro-mechanical universal switch.
Background
An inertia switch designed and manufactured on the basis of Micro-Electro-Mechanical System (MEMS) technology has the advantages of small volume, light weight, easiness in integration, mass production and the like, and has wide application prospects in the fields of automobile airbags, freight monitoring, airplane safety seat ejection triggering, ammunition launching, fuse detonation and the like. The physical model of the micro-mechanical inertial switch is a spring mass inertial system, which is generally divided into a trigger type and a locking type, wherein the former requires to be automatically opened after being closed, and the latter requires not to be opened after being closed. When the triggered inertial switch is impacted by acceleration, the mass block supported by the spring is used as a moving electrode to generate displacement opposite to the direction of the acceleration under the action of the inertial force until the mass block touches a fixed electrode to form an electric closed loop, and then the mass block is automatically separated under the action of the restoring force of the spring to complete the on-off action of the switch.
The micromechanical switch obtained by the traditional micromechanical switch manufacturing method, such as patent CN102693865A, is a metal spring mass structure manufactured by LIGA or UV-LIGA process. Because of the electroforming process, the problems of large stress and flatness are easily generated, so the thickness of the mass block cannot be large, and if a large inertial mass is needed, the area of the mass block needs to be increased. The metal used in the process is mostly nickel or nickel alloy, and the metal is sensitive to a magnetic field and is easy to be magnetized, so that the metal is easy to be interfered by the magnetic field to cause the switch to be accidentally closed; in addition, under the action of service treatment and recoil, the metal spring and the electrode are easy to generate plastic deformation after being impacted and collided, so that the acceleration threshold value of the switch is changed.
Disclosure of Invention
Aiming at the defects of the traditional micro-mechanical switch in the manufacturing method, the invention aims to solve the problems that the existing micro-mechanical switch is easy to generate larger stress and flatness by using an electroforming process in the manufacturing method, so that the thickness of a mass block cannot be very large, and the used metal is mostly nickel or nickel alloy, is sensitive to a magnetic field and is easy to be magnetized, so that the switch is easy to be interfered by the magnetic field to be accidentally closed; in addition, the spring and the electrode are easy to generate plastic deformation after being impacted and collided, thereby causing the technical problem that the acceleration threshold value of the switch is changed.
To achieve the above object, the present invention provides a method of manufacturing a micro-mechanical gimbal switch, the micro-mechanical gimbal switch comprising: the device comprises a device layer, a substrate and a sealing cap, wherein the upper part and the lower part of the device layer are respectively provided with the substrate and the sealing cap to form a sandwich structure; the device layer includes: the mass block is supported on the frame through the spiral spring beam, and the mass block is plated with metal to serve as a moving electrode; the sealing cap comprises: the electrode comprises a radial electrode, an axial electrode and an arc electrode; the radial electrodes are distributed around the mass block, the axial electrodes are positioned below the mass block, and the arc electrodes are positioned in the arc connecting direction of the radial electrodes and the axial electrodes; when the mass block is subjected to external radial acceleration, the moving electrode is contacted with the radial electrode, and the switch is closed; when the mass block is subjected to external axial acceleration, the moving electrode is contacted with the axial electrode, and the switch is closed; when the mass block forms a certain included angle with the axial direction and the radial direction respectively under the external acceleration direction, the moving electrode is contacted with the arc-shaped electrode, and the switch is closed; the substrate comprises a porous hollow structure and is distributed above the mass block and the spiral spring beam, the device layer and the substrate are processed on an SOI wafer, and the SOI wafer respectively comprises a thick silicon layer, a silicon dioxide insulating layer and a thin silicon layer from top to bottom; the manufacturing method of the micro-mechanical universal switch comprises the following steps:
manufacturing a layer of metal on the upper surface of the thick silicon layer through an electroplating process to serve as the moving electrode;
manufacturing the mass block and the spiral spring beam in the thick silicon layer through a deep silicon etching process;
etching a plurality of release holes in the thin silicon layer by a deep silicon etching process, and taking the formed hollow structure as the substrate;
processing the silicon dioxide insulating layer through a hydrofluoric acid etching process, and releasing the mass block and the spiral spring beam to form a movable structure;
manufacturing a seed layer of a fixed electrode on the upper surface of the sealing cap layer through a stripping process, wherein the fixed electrode comprises a radial electrode, an axial electrode and an arc electrode;
processing fixed electrodes with different heights and the same material by using a step electroplating process;
and aligning the processed SOI wafer with the sealing cap layer, and performing hot-pressing bonding packaging to finally manufacture the micro-mechanical universal switch.
Optionally, the thick silicon layer has a thickness of 300 μm to 1000 μm, the thin silicon layer has a thickness of 50 μm to 200 μm, and the silicon dioxide insulating layer has a thickness of 1 μm to 5 μm.
Optionally, the capping layer is made of silicon or glass and has a thickness of 300 μm to 500 μm.
Optionally, the spiral spring beam comprises four identical spiral beams, one end of each spiral beam is connected with the mass block, the other end of each spiral beam is connected with the frame, and the spirals of each beam are circumferentially distributed at intervals of 90 degrees.
Optionally, the radial electrode includes a circular ring structure formed by four convex metal arc structures on the sealing cap, is circumferentially distributed around the mass block at intervals of 90 degrees, and maintains a contact gap of 10 μm to 50 μm with the mass block.
Optionally, the axial electrode comprises a raised metal disc-like structure on the cap, located below the mass and maintaining a contact gap of 10 μm to 50 μm with the mass.
Optionally, the radial electrode and the axial electrode are both fixed electrodes, the metal materials used are the same, the thickness of the radial electrode is larger than that of the axial electrode, and the connecting portion of the radial electrode and the connecting portion of the axial electrode are arc-shaped electrodes formed by the same metal materials.
Optionally, the fixed electrode is manufactured by: determining a seed layer pattern of a radial electrode and a seed layer pattern of an axial electrode, wherein the seed layer patterns of the radial electrode and the seed layer patterns of the axial electrode are not conducted; the electroplating process starts from the seed layer pattern of the radial electrode, and generates an arc-shaped plating layer structure by electroplating towards the side direction of the seed layer pattern of the axial electrode while the plating layer thickness is gradually increased; with the continuous electroplating, the thickness of the plating layer is continuously increased, so that the arc-shaped plating layer structure is connected with the seed layer pattern of the axial electrode; the seed layer pattern of the axial electrode and the seed layer pattern of the radial electrode form an electroplating loop to start electroplating, because the time for starting electroplating is different, the heights of electroplating coating structures formed on the seed layer pattern of the radial electrode and the seed layer pattern of the axial electrode are different, and an arc-shaped coating structure exists between the seed layer pattern of the radial electrode and the seed layer pattern of the axial electrode; the electroplating coating structure on the radial electrode seed layer pattern is used as a radial electrode, the electroplating coating structure on the axial electrode seed layer pattern is used as an axial electrode, and the arc-shaped coating structure is used as an arc-shaped electrode.
Optionally, the beam width of the helical beam is 20 μm to 100 μm; the height of the spiral spring beam is the same as the thickness of the mass block and is 300-1000 μm.
Optionally, when the micro-mechanical universal switch is subjected to acceleration impact, the mass supported by the spiral spring beam can generate displacement opposite to the acceleration direction relative to the frame;
when the displacement of the mass block tends to the substrate and collides with the substrate, the hollowed-out structure has lower rigidity so as to deform, and kinetic energy generated by impact is converted into elastic potential energy, so that the mass block and the spiral spring beam are protected from being damaged under large impact.
Optionally, when the micro-mechanical universal switch is subjected to acceleration impact, the mass supported by the spiral spring beam can generate displacement opposite to the acceleration direction relative to the frame;
when the mass block is displaced downwards, the moving electrode on the mass block is in collision contact with the axial electrode on the sealing cap, so that a circuit loop is formed, and the switch is closed;
when the mass block generates displacement towards the peripheral direction, the moving electrode on the mass block collides and contacts with the radial electrode on the sealing cap to form a loop, and the switch is closed;
through the structural rigidity design of the spiral spring beam and the mass block and the matching of the gap distance between the moving electrode of the mass block and the radial electrode and the axial electrode, the micromechanical universal switch can have the same closing acceleration threshold value in the radial direction and the axial direction;
when the mass block generates displacement in the direction forming a certain included angle with the axial direction and the radial direction, the moving electrode on the mass block collides and contacts with the arc-shaped electrode at the connecting part of the radial electrode and the axial electrode on the sealing cap to form a loop, and the switch is closed;
the curvature radius of the arc step corresponding to the arc electrode and the gap distance parameter design of the mass block moving electrode are matched with the rigidity of the spiral spring beam and the mass block system in the direction, so that the micromechanical universal switch can have the same closed acceleration threshold value in the hemispherical direction, and universal triggering is realized.
In summary, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:
(1) the invention is based on SOI wafer and utilizes bulk silicon technology to manufacture the mass block and the spring structure of the micro-mechanical universal switch, so as to obtain thicker inertia mass block.
(2) The invention converts the impact energy into the elastic potential energy through the hollow structure manufactured on the thin silicon layer of the SOI wafer, so that the micro-mechanical switch has higher overload resistance.
(3) The invention synchronously obtains radial electrodes and axial electrodes with different thicknesses and arc step electrodes at the connection part of the radial electrodes and the axial electrodes through a step electroplating process; through the design of the gap distance between the micro-mechanical switch and the mass moving electrode and the rigidity of the matched spring mass block system in all directions, the micro-mechanical switch realized by the manufacturing method has the same acceleration threshold value in any direction in a hemispherical surface, namely the micro-mechanical switch has the same threshold value in the range of 0-90 degrees in the axial direction, and universal triggering is realized.
Drawings
FIG. 1 is a flow chart of a micro-mechanical universal switch SOI wafer processing process provided by an embodiment of the invention;
FIG. 2 is a schematic diagram of a step electroplating process used in a process of manufacturing a micro-mechanical gimbal switch according to an embodiment of the present invention;
FIG. 3 is a flow chart of a micro-mechanical gimbal switch cap step electroplating process provided by an embodiment of the invention;
FIG. 4 is a cross-sectional view of the overall structure of a micro-mechanical gimbal switch provided by an embodiment of the present invention after packaging;
fig. 5 is a diagram of a verification object of a micro-mechanical universal switch step electroplating process provided by the embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and two embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The working principle of the micro-mechanical universal switch is as follows: when the micro-mechanical universal switch is subjected to acceleration impact, the mass block supported by the spring generates displacement opposite to the acceleration direction relative to the frame. When the displacement of the mass block tends to the substrate and collides with the impact protection structure, the hollowed-out structure has lower rigidity so as to deform, and kinetic energy generated by impact is converted into elastic potential energy, so that the mass block and the spring are protected from being damaged under large impact. When the mass body is displaced along the axial direction and tends to the sealing cap, the movable electrode on the mass body is in collision contact with the fixed electrode on the sealing cap, so that a circuit loop, namely an opening and a closing are formed. The fixed electrode comprises a radial electrode, an axial electrode and an arc electrode, and when the mass block is impacted and generates displacement larger than a threshold value within the axial 0-90 degrees, the switch is closed, so that the universal triggering function is realized.
In one example, the present invention provides a micro-machined gimbal switch comprising a device layer, a substrate, and a cap, the device layer comprising: a proof mass, a helical spring beam, and a frame, the substrate comprising: an impact protection structure, said closure cap comprising: radial electrodes, axial electrodes, and arc electrodes.
The upper and lower parts of the device layer are a substrate and a sealing cap to form a micro-mechanical universal switch with a sandwich structure. The mass block is of a cylindrical structure and is supported on the frame by the spiral spring beam, and a layer of metal is plated on the upper surface of the mass block to serve as a moving electrode. The spiral spring beam comprises four identical spiral beams, the width of each beam can be 20-100 mu m, one end of each beam is connected with the mass block, the other end of each beam is connected with the frame, and the beams are circumferentially distributed at intervals of 90 degrees. The height of the spiral spring beam is the same as the thickness of the mass block, and can be 300-1000 μm; the impact protection structure comprises a porous hollow structure on the substrate and is distributed below the mass block structure and the spring structure.
Wherein the spiral spring beam may be referred to as a spring for short.
The radial electrode comprises a circular structure consisting of four sections of metal arc structures protruding on the sealing cap, is circumferentially distributed around the mass block at intervals of 90 degrees and keeps a certain contact gap with the mass block; the gap may be 10 μm to 50 μm.
The axial electrode comprises a metal disc-shaped structure protruding from the sealing cap, is positioned below the mass block and keeps a certain contact gap with the mass block; the gap may be 10 μm to 50 μm.
The radial electrode and the axial electrode are both fixed electrodes, the used metal materials are the same, the thickness of the radial electrode is larger than that of the axial electrode, the connecting parts of the radial electrode and the axial electrode are arc steps formed by the same metal, and the arc steps are used as arc electrodes.
When the micro-mechanical universal switch is subjected to acceleration impact, the mass block supported by the spring generates displacement opposite to the acceleration direction relative to the frame. When the displacement of the mass block tends to the substrate and collides with the impact protection structure, the hollowed-out structure has lower rigidity so as to deform, and kinetic energy generated by impact is converted into elastic potential energy, so that the mass block and the spring are protected from being damaged under large impact. When the mass block moves along the axial direction and tends to the sealing cap, the moving electrode on the mass block is in collision contact with the axial fixed electrode on the sealing cap, so that a circuit loop, namely an opening and closing state, is formed. When the mass block generates radial displacement, the moving electrode on the mass block collides and contacts with the radial fixed electrode on the sealing cap to form a loop, and the switch is closed. Through the structural rigidity design of the spring and the mass block and the matching of the gap distance between the moving electrode and the radial and axial fixed electrodes of the mass block, the switch can have the same closing acceleration threshold value in the radial direction and the axial direction.
When the mass block generates displacement in the direction forming a certain included angle with the axial direction and the radial direction, the moving electrode on the mass block collides and contacts with the metal arc step at the joint of the radial electrode and the axial electrode on the sealing cap to form a loop, and the switch is closed. Through the design of parameters such as the curvature radius of the arc-shaped step, the gap distance between the arc-shaped step and the moving electrode of the mass block and the like, the rigidity of the spring and the mass block system in the direction is matched, so that the micro-mechanical switch has the same closed acceleration threshold value in the hemispherical direction, and universal triggering is realized.
The invention provides a manufacturing method of a micro-mechanical universal switch. The spring and mass block mechanism of the micro-mechanical inertial switch obtained by the manufacturing method can obtain a larger inertial mass block in a smaller area through bulk silicon process processing based on an SOI wafer; enabling the inertial switch to have the same collision acceleration threshold value in a forward hemispherical surface of the carrier through a step electroplating process; and the flexible structure is manufactured on the back surface of the device to realize the structure overload protection under large impact load.
Specifically, the device layer and the substrate are processed on an SOI wafer, which includes, from top to bottom, a thick silicon layer, a silicon dioxide insulating layer, and a thin silicon layer, respectively. The specific manufacturing method of the micromechanical universal switch provided by the invention comprises the following steps:
1) and cleaning the SOI wafer.
2) The metal moving electrode of the micro-mechanical universal switch is manufactured on the upper surface of the thick silicon layer of the SOI wafer through an electroplating process, and the thickness of the electrode is 1-10 mu m.
3) And manufacturing a mass block and a spring structure of the micro-mechanical universal switch on the thick silicon layer of the SOI wafer by a deep silicon etching process.
4) And etching a release hole on the thin silicon layer of the SOI wafer by a deep silicon etching process, and taking the formed hollow structure as an impact overload protection mechanism of the micro-mechanical universal switch.
5) And (3) processing the silicon dioxide insulating layer of the SOI wafer by a hydrofluoric acid etching process to release the movable structure of the micro-mechanical universal switch.
6) And cleaning the surface of the sealing cap layer.
7) And manufacturing a seed layer of the metal fixed electrode of the micro-mechanical universal switch on the upper surface of the sealing cap layer by a stripping process, wherein the thickness of the seed layer is 100nm-500 nm.
8) And processing metal fixed electrodes with different heights but the same material by using a step electroplating process.
9) And aligning the processed SOI structure with the sealing cap layer to carry out hot-pressing bonding packaging, and finally manufacturing the micro-mechanical universal switch chip.
The thickness of the thick silicon layer of the SOI wafer is 300-1000 μm, the thickness of the thin silicon layer is 50-200 μm, and the thickness of the middle insulating layer is 1-5 μm.
The capping layer material comprises silicon or glass, and the thickness of the capping layer material is 300-500 μm.
The metal materials of the moving electrode and the fixed electrode can be gold, copper and tin.
Wherein, the step electroplating process principle: different patterns defined by the metal seed layer have different time for connecting with the electroplating loop, so that structures with different heights are generated in the same electroplating process. Firstly, a seed layer pattern of an electric loop is connected, under the condition of no constraint of photoresist, side electroplating can be generated while the pattern thickness is increased by electroplating; when metal generated by the lateral electroplating contacts the peripheral seed layer pattern, the peripheral pattern starts electroplating, but the thickness of an electroplating layer formed by the peripheral pattern is smaller than that of the pattern which starts electroplating at first; after the electroplating process is finished, the electroplated coating presents electrode structures with different heights, the electrode structures with different heights are connected through the arc-shaped coating structure, and the height difference of the coating between different patterns can be controlled by controlling the distance between the patterns of the seed layer.
To further illustrate the method for manufacturing the micro-mechanical gimbal switch provided by the embodiment of the present invention, the present invention will be further described in detail with reference to the accompanying drawings.
FIG. 1 is a flow chart of a micromechanical gimbal switch SOI wafer processing process. The thickness of the thick silicon layer 1 of the SOI wafer with the diameter of 100mm is 500 μm, the thickness of the thin silicon layer 2 is 50 μm, and the thickness of the silicon dioxide insulating layer 3 is 2 μm. The processing of the SOI wafer comprises: the metal moving electrode 401 and the packaging pad 402 are processed on the upper surface of the thick silicon layer 1 by a process of manufacturing a seed layer and then electroplating. Then, deep silicon etching processing is carried out on the thick silicon layer 1 to form a mass block 101 and a spring 102 of the micro-mechanical universal switch; and then, deep silicon etching processing is carried out on the thin silicon layer 2 to form the hollow-out structure 201. And finally, etching part of the structure of the insulating layer 3 by using a hydrofluoric acid etching process, and finally releasing the mass block 101 and the spring 102 to form a movable structure.
FIG. 2 is a schematic diagram of a step plating process used in the fabrication of a micro-machined gimbal switch. A seed layer pattern structure 501 forming an electroplating loop, and a seed layer pattern 502 not conducting to form a loop. The electroplating process begins with pattern 501 and produces an arc-shaped plating structure 503 by electroplating laterally while the plating thickness is gradually increased. As the electroplating continues, the thickness of the plating layer increases continuously, resulting in the connection of the arc-shaped structure 503 with the seed layer pattern 502; the seed layer pattern 502 forms an electroplating loop to start electroplating because the electroplating starts at different times, and the finally formed electroplating plating structures 501 and 502 have different heights and an arc-shaped plating structure 503 exists between the two. Specifically, the electroplating coating structures 501 and 502 and the arc-shaped coating structure 503 can be used as a radial electrode, an axial electrode and an arc-shaped electrode, respectively. As shown in fig. 3.
FIG. 3 is a flow chart of a micro-mechanical gimbal switch cap step electroplating process. The material of the sealing cap 6 is glass. Seed layers 701 and 702 of the fixed plate are fabricated on the cap 6 by a Physical Vapor Deposition (PVD) process and a lift-off process to encapsulate the pad seed layer 801 and the electrical lead pads 901. The seed layer is 40nm chromium and 200nm gold. When the fixed plate seed layer 701 is connected to an electroplating loop and then an electroplating process is started, the plating layer appears in the vertical direction and the lateral direction of the fixed plate seed layer 701, and a mountain-shaped plating layer structure 7011 is formed. As the plating continues, the plating structure 7011 is conducted to the seed layer structure 702 of the fixed plate, so that the structure 702 that has not been previously connected to the plating loop starts to be plated, and a new plating structure 7021 is formed. Similarly, a plating structure 8011 is formed at the package pad and a plating 9011 is formed at the electrical lead pad.
As shown in fig. 3, the metal electrodes obtained by electroplating on the seed layers 701 and 702 correspond to the radial electrode and the axial electrode, respectively. The arc step of the hill-shaped coating structure 7011 corresponds to the arc electrode. The radial electrode and the axial electrode prepared by the step electroplating process have different thicknesses, and an arc electrode is arranged between the radial electrode and the axial electrode.
Fig. 4 is a cross-sectional view of the overall structure of the micro-mechanical gimbal switch after packaging. After aligning the processed SOI wafer and the processed sealing cap through a Finetech packaging machine, carrying out gold-gold hot-pressing bonding in a cavity of the packaging machine, and packaging to form mechanical fixed connection and electrical interconnection.
FIG. 5 is a sample image of the patterned structure subjected to the step plating process observed in a scanning electron microscope, in which the lower plating layer is about 5 μm thick and the upper plating layer is about 30 μm thick. It can be known that metal layers of different thicknesses can be prepared by a step plating process.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (8)
1. A method of manufacturing a micromechanical gimbal switch, characterized in that the micromechanical gimbal switch comprises: the device comprises a device layer, a substrate and a sealing cap, wherein the upper part and the lower part of the device layer are respectively provided with the substrate and the sealing cap to form a sandwich structure; the device layer includes: the mass block is supported on the frame through the spiral spring beam, and the upper surface of the mass block is plated with metal to serve as a moving electrode; the sealing cap comprises: the electrode comprises a radial electrode, an axial electrode and an arc electrode; the radial electrodes are distributed around the mass block, the axial electrodes are positioned below the mass block, and the arc electrodes are positioned in the arc connecting direction of the radial electrodes and the axial electrodes; when the mass block is subjected to external radial acceleration, the moving electrode is contacted with the radial electrode, and the switch is closed; when the mass block is subjected to external axial acceleration, the moving electrode is contacted with the axial electrode, and the switch is closed; when the mass block forms a certain included angle with the axial direction and the radial direction respectively under the external acceleration direction, the moving electrode is contacted with the arc-shaped electrode, and the switch is closed; the substrate comprises a porous hollow structure and is distributed above the mass block and the spiral spring beam, the device layer and the substrate are processed on an SOI wafer, and the SOI wafer respectively comprises a thick silicon layer, a silicon dioxide insulating layer and a thin silicon layer from top to bottom; the manufacturing method of the micromechanical universal switch comprises the following steps:
manufacturing a layer of metal on the upper surface of the thick silicon layer through an electroplating process to serve as the moving electrode;
manufacturing the mass block and the spiral spring beam in the thick silicon layer through a deep silicon etching process;
etching a plurality of release holes in the thin silicon layer by a deep silicon etching process, and taking the formed hollow structure as the substrate;
processing the silicon dioxide insulating layer through a hydrofluoric acid etching process, releasing the mass block and the spiral spring beam, and enabling the mass block and the spiral spring beam to form a movable structure;
manufacturing a seed layer of a fixed electrode on the upper surface of the sealing cap layer through a stripping process, wherein the fixed electrode comprises a radial electrode, an axial electrode and an arc electrode;
processing fixed electrodes with different heights and the same material by using a step electroplating process;
aligning the processed SOI wafer with the sealing cap layer to perform hot-pressing bonding packaging, and finally manufacturing the micro-mechanical universal switch;
when the micro-mechanical universal switch is impacted by acceleration, the mass block supported by the spiral spring beam can generate displacement opposite to the direction of the acceleration relative to the frame;
when the displacement of the mass block tends to the substrate and collides with the hollow structure, the hollow structure has lower rigidity so as to deform, and kinetic energy generated by impact is converted into elastic potential energy, so that the mass block and the spiral spring beam are protected from being damaged under large impact;
the fixed electrode is manufactured by the following method:
determining a seed layer pattern of a radial electrode and a seed layer pattern of an axial electrode, wherein the seed layer patterns of the radial electrode and the seed layer patterns of the axial electrode are not conducted;
the electroplating process starts from the seed layer pattern of the radial electrode, and generates an arc-shaped plating layer structure by electroplating towards the side direction of the seed layer pattern of the axial electrode while the plating layer thickness is gradually increased;
with the continuous electroplating, the thickness of the plating layer is continuously increased, so that the arc-shaped plating layer structure is connected with the seed layer pattern of the axial electrode;
the seed layer pattern of the axial electrode and the seed layer pattern of the radial electrode form an electroplating loop to start electroplating, because the time for starting electroplating is different, the heights of electroplating coating structures formed on the seed layer pattern of the radial electrode and the seed layer pattern of the axial electrode are different, and an arc-shaped coating structure exists between the seed layer pattern of the radial electrode and the seed layer pattern of the axial electrode; the electroplating coating structure on the radial electrode seed layer pattern is used as a radial electrode, the electroplating coating structure on the axial electrode seed layer pattern is used as an axial electrode, and the arc-shaped coating structure is used as an arc-shaped electrode.
2. A method of manufacturing a micromechanical gimbal switch according to claim 1, characterized in that the thickness of the thick silicon layer is 300 μ ι η -1000 μ ι η, the thickness of the thin silicon layer is 50 μ ι η -200 μ ι η, and the thickness of the silicon dioxide insulating layer is 1 μ ι η -5 μ ι η.
3. A method of fabricating a micromechanical gimbal switch as claimed in claim 1, wherein said capping layer is made of silicon or glass and has a thickness of 300 μm to 500 μm.
4. A method of fabricating a micromechanical gimbal switch according to claim 1, characterized in that the helical spring beams comprise four identical helical beams, each of which is connected at one end to the mass and at the other end to the frame, the helices of each beam being circumferentially spaced by 90 degrees.
5. The method according to claim 1, wherein the radial electrodes comprise a circular ring structure formed by four segments of metal arc structures protruding from the cap, are circumferentially distributed around the mass block at intervals of 90 degrees, and maintain a contact gap of 10 μm to 50 μm with the mass block.
6. A method of manufacturing a micro-mechanical gimbal switch as claimed in claim 1, wherein the axial electrode comprises a raised metal disk-like structure on the cap, located below the proof mass and maintaining a contact gap of 10 μm-50 μm with the proof mass.
7. A method of fabricating a micromechanical gimbal switch as claimed in claim 1, wherein the radial electrodes and the axial electrodes are fixed electrodes and are made of the same metal material, the radial electrodes have a greater thickness than the axial electrodes, and the connecting portions are arc electrodes made of the same metal material.
8. The method of any of claims 1 to 7, wherein when the mass is displaced downward, the moving electrode of the mass collides with the axial electrode of the cap to form a circuit loop, and the switch is closed;
when the mass block generates displacement towards the peripheral direction, the moving electrode on the mass block collides and contacts with the radial electrode on the sealing cap to form a loop, and the switch is closed;
through the structural rigidity design of the spiral spring beam and the mass block and the matching of the gap distance between the moving electrode of the mass block and the radial electrode and the axial electrode, the micromechanical universal switch can have the same closing acceleration threshold value in the radial direction and the axial direction;
when the mass block generates displacement in the direction forming a certain included angle with the axial direction and the radial direction, the moving electrode on the mass block collides and contacts with the arc-shaped electrode at the connecting part of the radial electrode and the axial electrode on the sealing cap to form a loop, and the switch is closed;
the curvature radius of the arc step corresponding to the arc electrode and the gap distance parameter design of the mass block moving electrode are matched with the rigidity of the spiral spring beam and the mass block system in the direction, so that the micromechanical universal switch can have the same closed acceleration threshold value in the hemispherical direction, and universal triggering is realized.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810871365.XA CN109036910B (en) | 2018-08-02 | 2018-08-02 | Method for manufacturing micro-mechanical universal switch |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810871365.XA CN109036910B (en) | 2018-08-02 | 2018-08-02 | Method for manufacturing micro-mechanical universal switch |
Publications (2)
| Publication Number | Publication Date |
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