CN114895072A - MEMS impact sensor and preparation method thereof - Google Patents
MEMS impact sensor and preparation method thereof Download PDFInfo
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- CN114895072A CN114895072A CN202210556860.8A CN202210556860A CN114895072A CN 114895072 A CN114895072 A CN 114895072A CN 202210556860 A CN202210556860 A CN 202210556860A CN 114895072 A CN114895072 A CN 114895072A
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- structure layer
- sensitive structure
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
- G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
- G01P15/12—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by alteration of electrical resistance
- G01P15/123—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by alteration of electrical resistance by piezo-resistive elements, e.g. semiconductor strain gauges
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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]
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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
- B81C1/00261—Processes for packaging MEMS devices
- B81C1/00269—Bonding of solid lids or wafers to the substrate
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B2201/00—Specific applications of microelectromechanical systems
- B81B2201/02—Sensors
- B81B2201/0264—Pressure sensors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
- G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
- G01P2015/0862—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with particular means being integrated into a MEMS accelerometer structure for providing particular additional functionalities to those of a spring mass system
Abstract
The invention provides an MEMS impact sensor and a preparation method thereof. The MEMS impact sensor comprises a top cover, a sensitive structure layer, a bottom plate and a bonding medium; the top cover is arranged above the sensitive structure layer, the sensitive structure layer comprises a piezoresistor, a metal lead, an elastic beam and a mass block, the bottom plate is arranged below the sensitive structure layer, the top cover and the sensitive structure layer, the bottom plate and the sensitive structure layer are bonded by media, and the bonding media not only ensure the bonding strength, but also provide movable gaps between the top cover and the sensitive structure layer, and between the bottom plate and the sensitive structure layer. The MEMS impact sensor can complete the whole process manufacturing only by two-step etching and two-step bonding after the doping of the resistor is completed, the process steps of the conventional impact sensor are greatly reduced, the MEMS impact sensor is a chip-level sealing structure, movable parts are protected by a top cover and a bottom plate, the sensor can be directly packaged by using a common plastic packaging process in the later period, and the MEMS impact sensor is high in applicability.
Description
Technical Field
The invention relates to the technical field of Micro-Electro-Mechanical Systems (MEMS), in particular to an MEMS impact sensor and a preparation method thereof.
Background
The MEMS impact sensor is an acceleration sensor for detecting impact signals, is widely applied to the occasions of collision measurement and impact vibration measurement, and has urgent demands and broad market. The existing MEMS impact sensor has complex process and high cost, and the application field of the MEMS impact sensor is greatly limited. In the prior art, due to the particularity of a sensitive structure, the manufacture of unequal-height structures such as a bonding anchor point, a damping gap, a dynamic gap, an elastic beam, a mass block and the like is usually completed by etching for multiple times, the complex process usually causes the reduction of the yield and the improvement of the cost, meanwhile, the traditional anodic bonding and silicon-silicon bonding have higher requirements on a bonding surface, the existence of micro defects often causes serious consequences to cause processing failure, BCB bonding has high tolerance on an interface, and part of a silicon structure can be replaced, so that the process is simplified, the product yield is improved, and the cost is reduced.
Disclosure of Invention
The embodiment of the invention provides an MEMS impact sensor and a preparation method thereof. The MEMS chip is manufactured by adopting an MEMS process, firstly, a Wheatstone bridge is manufactured on a monocrystalline silicon chip or an SOI chip through a piezoresistive process, metal interconnection is completed, processing of an elastic beam and a mass block is completed through a deep etching process, manufacturing of a top cover and a bottom plate is completed through BCB medium bonding, wafer level packaging is realized, and then chips are divided through scribing and lead electrodes are exposed. The invention adopts the following technical scheme:
the MEMS impact sensor comprises a top cover 1, a sensitive structure layer 4, a bottom plate 6 and a bonding medium 2; the top cover 1 is arranged above the sensitive structure layer 4, the sensitive structure layer 4 comprises a piezoresistor 9, a metal lead 3, an elastic beam 7 and a mass block 8, the bottom plate 6 is arranged below the sensitive structure 4, the top cover 1 and the sensitive structure layer 4, and the bottom plate 6 and the sensitive structure layer 4 are all bonded by adopting media, and the bonding media 2 not only ensure the bonding strength, but also provide movable gaps between the top cover 1 and the sensitive structure layer 4, and between the bottom plate 6 and the sensitive structure layer 4. The piezoresistor 9 of the sensitive structure layer 4 is implanted on the N-type substrate by ion implantationInto B + And (4) manufacturing particles, wherein the elastic beam 7 and the mass block 8 are manufactured by adopting a deep silicon etching process.
Further, the top cover and the bottom plate are made of semiconductor or insulator materials, including but not limited to one or a mixture of several of ceramics, sapphire, silicon, glass, epoxy resin, polyimide and the like.
Furthermore, the sensitive structure layer material is a monocrystalline silicon wafer or an SOI wafer.
Furthermore, the piezoresistor of the sensitive structure layer is implanted with B on the N-type substrate by ion implantation + And (4) preparing particles.
Furthermore, the elastic beam and the mass block of the sensitive structure layer are of equal thickness or unequal thickness structures.
Further, BCB glue is selected as the bonding medium, and BCB imaging is completed through photoetching.
Furthermore, the size of the top cover is smaller than that of the sensitive structure and the bottom plate, and the metal leads are exposed by scribing.
The invention provides an MEMS impact sensor and a preparation method thereof, and the process flow is as follows:
(1) ion implantation of B on silicon wafer or SOI wafer of N-type substrate + Manufacturing a piezoresistor by the particles;
(2) the piezoresistors are combined into a Wheatstone bridge through a metal lead and led out;
(3) photoetching and deep silicon etching are carried out to define the shapes and the thicknesses of the front surfaces of the elastic beam and the mass block;
(4) spin-coating BCB glue on the top cover and completing BCB imaging by using a photoetching process;
(5) the BCB bonding of the top cover and the sensitive structure is completed through a medium bonding process;
(6) the sensitive structure layer is thinned to the required thickness by CMP;
(7) photoetching and deep silicon etching are carried out to define the back shapes and the thicknesses of the elastic beam and the mass block;
(8) spin-coating BCB glue on a substrate and completing BCB patterning by using a photoetching process;
(9) the BCB bonding of the bottom plate and the sensitive structure is completed through a medium bonding process;
(10) and carrying out fractional scribing to complete chip separation and expose the top surface metal leads.
Further, the resistance value of the piezoresistor manufactured in the step (1) is 500 ohm to 5k ohm.
Further, the metal lead material produced in the step (2) includes, but is not limited to, aluminum, copper, titanium, gold, and the like.
Furthermore, the elastic beam and the mass block of the sensitive structure layer manufactured in the step (3) are of equal thickness or unequal thickness structures, the thickness of the elastic beam is 1-50 μm, and the thickness of the mass block is 5-500 μm.
Further, BCB glue is selected as the bonding medium in the step (4), BCB patterning is completed through photoetching, and the thickness is 2-50 μm.
Further, the thickness of the sensitive structure manufactured in the step (6) is 5-500 μm.
Further, the size of the top cover layer in the step (9) is smaller than that of the sensitive structure and the bottom plate, and the metal leads are exposed by scribing.
The invention has the beneficial effects that: the MEMS impact sensor and the preparation method thereof provided by the invention completely adopt MEMS technology and wafer-level processing, the impact sensor manufactured by the method can be manufactured in the whole process only by two-step etching and two-step bonding after doping resistors, the process steps of the conventional impact sensor are greatly reduced, the manufactured MEMS impact sensor is a chip-level sealing structure, movable components are protected by a top cover and a bottom plate, the packaging of the sensor can be directly completed by using a common plastic packaging technology in the later period, and the applicability is strong.
Drawings
FIG. 1 is a schematic side view of a MEMS impact sensor of the present invention;
FIGS. 2a to 2e illustrate the main fabrication process and method of a MEMS impact sensor according to the present invention;
in the figure, 1-top cover, 2-bonding medium, 3-metal lead, 4-sensitive structure layer, 6-bottom plate, 7-elastic beam, 8-mass block and 9-piezoresistor
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments and the accompanying drawings. Those skilled in the art will appreciate that the present invention is not limited to the drawings and the following examples.
Example 1
Referring to fig. 1, the invention provides an MEMS impact sensor, which is manufactured by an MEMS process, and includes firstly manufacturing a wheatstone bridge on a monocrystalline silicon wafer or an SOI wafer by a piezoresistive process, completing metal interconnection, completing processing of an elastic beam and a mass block by a deep etching process, completing manufacturing of a top cover and a bottom plate by BCB dielectric bonding, realizing wafer level packaging, and then dividing a chip by scribing and exposing a lead electrode. The invention adopts the following technical scheme:
the MEMS impact sensor comprises a top cover 1, a sensitive structure layer 4, a bottom plate 6 and a bonding medium 2; the top cover 1 is arranged above the sensitive structure layer 4, the sensitive structure layer 4 comprises a piezoresistor 9, a metal lead 3, an elastic beam 7 and a mass block 8, the bottom plate 6 is arranged below the sensitive structure layer 4, the top cover 1 and the sensitive structure layer 4, and the bottom plate 6 and the sensitive structure layer 4 are all bonded by adopting media, and the bonding media 2 not only ensure the bonding strength, but also provide movable gaps between the top cover 1 and the sensitive structure layer 4, and between the bottom plate 6 and the sensitive structure layer 4. The piezoresistor 9 of the sensitive structure layer 4 is implanted B on the N-type substrate by ion implantation + And (4) manufacturing particles, wherein the elastic beam 7 and the mass block 8 are manufactured by adopting a deep silicon etching process.
The MEMS impact sensor has the advantages of simple process structure, strong material adaptability, high yield and convenience for later-stage packaging and assembly.
Example 2
Referring to fig. 1, fig. 2a, 2b, 2c, 2d, and 2e, the present invention provides a method for manufacturing an MEMS impact sensor, which comprises the following steps:
(1) referring to FIG. 2a, ion implantation B is performed on a silicon wafer or SOI wafer 4 of an N-type substrate + The particle is used for manufacturing a piezoresistor 9 and is interconnected through a metal lead 3;
(2) referring to fig. 2b, photolithography and deep silicon etching define the shapes and thicknesses of the front surfaces of the elastic beam 7 and the mass block;
(3) referring to fig. 2c, a bonding medium 2BCB glue is spin-coated on the top cover 1, BCB patterning is completed by a photolithography process, and the top cover 1 and the sensitive structure layer 4 are bonded together by medium bonding;
(4) referring to fig. 2d, the sensitive structure layer 4 is thinned to a required thickness by using a CMP process, and then the back shapes and thicknesses of the elastic beam 7 and the mass block 8 are defined by using a photoetching and deep etching process;
(5) referring to fig. 2e, a bonding medium 2BCB glue is spin-coated on the bottom plate 6, BCB patterning is completed by a photolithography process, and the bottom plate 6 and the sensitive structure layer 4 are bonded together by medium bonding;
(6) referring to fig. 1, the fractional dicing completes the chip separation and exposes the top side metal leads 3.
The preparation method of the MEMS impact sensor provided by the embodiment has the advantages of simple process, good consistency, high precision and low cost, and is suitable for mass production.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. An MEMS impact sensor is characterized by comprising a top cover, a sensitive structure layer, a bottom plate and a bonding medium; the top cover is arranged above the sensitive structure layer, the sensitive structure layer comprises a piezoresistor, a metal lead, an elastic beam and a mass block, the bottom plate is arranged below the sensitive structure layer, the top cover and the sensitive structure layer and the bottom plate and the sensitive structure layer are bonded by adopting media, and the bonding media ensure the bonding strength and provide movable gaps between the top cover and the sensitive structure layer and between the bottom plate and the sensitive structure layer. The piezoresistor of the sensitive structure layer is implanted B on the N-type substrate by ion implantation + And (4) manufacturing particles, wherein the elastic beam and the mass block are manufactured by adopting a deep silicon etching process.
2. A MEMS impact sensor as claimed in claim 1 wherein said top cap and said base plate are of semiconductor or insulator materials including but not limited to ceramic, sapphire, silicon, glass, epoxy, polyimide, or any combination thereof.
3. The MEMS impact sensor of claim 1 wherein the sensitive structure layer is made of a single crystal silicon wafer or SOI wafer.
4. A MEMS impact sensor as claimed in claim 1, wherein said sensitive structure layer is 5 μm to 500 μm thick.
5. The MEMS impact sensor of claim 1 wherein the piezoresistors of the sensitive structure layer are implanted B on the N-type substrate using ion implantation + The particles are made to have a resistance of 500 to 5k ohms.
6. The MEMS impact sensor of claim 1 wherein the spring beam and the mass of the sensitive structure layer are of equal or unequal thickness, the spring beam having a thickness of 1 μm to 50 μm and the mass having a thickness of 5 μm to 500 μm.
7. The MEMS impact sensor of claim 1 wherein the bonding medium is BCB resist patterned by photolithography to a thickness of 2 μm to 50 μm.
8. The MEMS impact sensor of claim 1 wherein the top cover is smaller in size than the sensitive structural layer and the bottom plate, and metal leads are exposed by dicing.
9. A method of manufacturing a MEMS impact sensor as claimed in any one of claims 1 to 8, characterized by the steps of:
(1) ion implantation of B on silicon wafer or SOI wafer of N-type substrate + Manufacturing a piezoresistor by the particles;
(2) the piezoresistors are combined into a Wheatstone bridge through a metal lead and led out;
(3) photoetching and deep silicon etching are carried out to define the shapes and the thicknesses of the front surfaces of the elastic beam and the mass block;
(4) spin-coating BCB glue on the top cover and completing BCB imaging by using a photoetching process;
(5) the BCB bonding of the top cover and the sensitive structure layer is completed through a medium bonding process;
(6) the sensitive structure layer is thinned to the required thickness by CMP;
(7) photoetching and deep silicon etching are carried out to define the back shapes and the thicknesses of the elastic beam and the mass block;
(8) spin-coating BCB glue on a substrate and completing BCB patterning by using a photoetching process;
(9) the BCB bonding of the bottom plate and the sensitive structure is completed through a medium bonding process;
(10) and carrying out fractional scribing to complete chip separation and expose the top surface metal leads.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202210556860.8A CN114895072A (en) | 2022-05-20 | 2022-05-20 | MEMS impact sensor and preparation method thereof |
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| CN202210556860.8A CN114895072A (en) | 2022-05-20 | 2022-05-20 | MEMS impact sensor and preparation method thereof |
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2022
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Application publication date: 20220812 |