CN114578094B - High overload torsion type silicon micro accelerometer and preparation method thereof - Google Patents
High overload torsion type silicon micro accelerometer and preparation method thereof Download PDFInfo
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- CN114578094B CN114578094B CN202210211524.XA CN202210211524A CN114578094B CN 114578094 B CN114578094 B CN 114578094B CN 202210211524 A CN202210211524 A CN 202210211524A CN 114578094 B CN114578094 B CN 114578094B
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 99
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 99
- 239000010703 silicon Substances 0.000 title claims abstract description 99
- 238000002360 preparation method Methods 0.000 title abstract description 13
- 238000000034 method Methods 0.000 claims description 51
- 230000008569 process Effects 0.000 claims description 48
- 238000005530 etching Methods 0.000 claims description 38
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 30
- 238000001259 photo etching Methods 0.000 claims description 15
- 235000012239 silicon dioxide Nutrition 0.000 claims description 15
- 239000000377 silicon dioxide Substances 0.000 claims description 15
- 238000001039 wet etching Methods 0.000 claims description 9
- 238000001514 detection method Methods 0.000 claims description 5
- 238000005516 engineering process Methods 0.000 claims description 3
- 238000005498 polishing Methods 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 230000007774 longterm Effects 0.000 abstract description 4
- 230000008901 benefit Effects 0.000 description 4
- 230000003139 buffering effect Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 238000001312 dry etching Methods 0.000 description 3
- 230000009467 reduction Effects 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
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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
- G01P15/125—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 capacitive pick-up
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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
- B81B7/0032—Packages or encapsulation
- B81B7/0045—Packages or encapsulation for reducing stress inside of the package structure
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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
- B81C1/00642—Manufacture or treatment of devices or systems in or on a substrate for improving the physical properties of a device
- B81C1/0065—Mechanical properties
- B81C1/00666—Treatments for controlling internal stress or strain in MEMS structures
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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
- B81C3/00—Assembling of devices or systems from individually processed components
- B81C3/001—Bonding of two components
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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
- B81B2201/0228—Inertial sensors
- B81B2201/0235—Accelerometers
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- Microelectronics & Electronic Packaging (AREA)
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Abstract
The invention discloses a high-overload torsion pendulum type silicon micro-accelerometer and a preparation method thereof. The invention can greatly reduce the bonding stress of the wafer level, improve the overload resistance of the silicon micro-accelerometer, ensure the service life and long-term reliability of the product, improve the bonding smoothness between the silicon sensitive structure and the electrode layer, improve the consistency of the capacitance gap and have higher processing precision.
Description
Technical Field
The invention relates to a silicon microsensor technology, in particular to a high overload torsion pendulum type silicon micro accelerometer and a preparation method thereof.
Background
The MEMS silicon micro-accelerometer is mainly manufactured by a micro-mechanical surface processing technology, and has the advantages of small volume, low cost, mass processing and the like; has wide application prospect in the fields of military industries such as inertial navigation, tactical missiles, aerospace and the like, the industrial fields such as rail transit, unmanned aerial vehicles, wind power generation and the like, the commercial fields such as biomedical and automobile electronics and the like. With the market of MEMS silicon micro-accelerometers, the reliability requirements of the silicon micro-accelerometer products are higher and higher, such as overload resistance and wide range requirements. However, the current common overload resistance of the domestic mature mass-produced MEMS silicon micro-accelerometer is less than 10000g, and the vibration acceleration sensing requirements of the guided explosive and the rail transit are difficult to meet.
Disclosure of Invention
The invention aims to solve the technical problems: aiming at the problems in the prior art, the invention provides the high overload torsion type silicon micro accelerometer and the preparation method thereof, which can greatly reduce the bonding stress of a wafer level, improve the overload resistance of the silicon micro accelerometer, ensure the service life and long-term reliability of a product, improve the bonding flatness between a silicon sensitive structure and an electrode layer, improve the consistency of a capacitance gap and have higher processing precision
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention provides a high overload torsion pendulum type silicon micro-accelerometer, which comprises an SO I electrode structure layer and a silicon sensitive structure, wherein three electrostatic capacitance areas and corresponding lead plates are arranged on the SO I electrode structure layer, the silicon sensitive structure comprises a mass block, a bonding block and a supporting beam, wherein the bonding block and the supporting beam are formed by etching the middle part of the mass block, the bonding block is different in mass at two sides and is arranged opposite to the three electrostatic capacitance areas in a gap manner to form a planar capacitance structure, the bonding block is connected with the mass block through the supporting beam, and the bonding block is connected with the SO I electrode structure layer through bonding anchor points in a bonding manner, SO that bonding planes of the bonding block and the SO I electrode structure layer are arranged in a suspended manner.
Optionally, two through open slots formed by etching process are arranged in the middle of the mass block, the openings of the two open slots are mutually opposite, so that the inner area of the open slot and the middle connecting part with opposite openings form a bonding block, a supporting beam is respectively formed between the open edges at two sides of the two open slots, and the supporting beams at two sides are symmetrically arranged.
Alternatively, the support beams on the two sides are symmetrically arranged relative to the central axes of the three electrostatic capacity regions, and the axes of the two support beams are perpendicular to the central axes of the three electrostatic capacity regions.
Optionally, the middle part of SO I electrode structure layer is equipped with a plurality of first bonding anchor points that the protrusion was arranged, the middle part of bonding piece is equipped with a plurality of second bonding anchor points that the protrusion was arranged, first bonding anchor point and second bonding anchor point one-to-one and bonding connection make bonding piece and the unsettled arrangement of bonding plane of SO I electrode structure layer both, just the center of the sensitive structure of silicon aligns with the central point of a plurality of first bonding anchor points on the SO I electrode structure layer.
Optionally, the first bonding anchor is disposed on a surface of a middle electrostatic capacitance region among the three electrostatic capacitance regions, and a height of the first bonding anchor is higher than the three electrostatic capacitance regions.
Optionally, among the lead pads corresponding to the three electrostatic capacitance areas of the SO I electrode structure layer, the lead pad corresponding to the electrostatic capacitance area located in the middle is used as a ground electrode, and the lead pad corresponding to the electrostatic capacitance area located at both ends is used as a detection electrode.
Optionally, the number of the first bonding anchor points and the second bonding anchor points is four, the four second bonding anchor points are symmetrically distributed about a central axis of the mass block, and the four first bonding anchor points are symmetrically distributed about central axes of three electrostatic capacitance areas on the SO I electrode structure layer.
Optionally, a plurality of first bonding anchor points protruding are arranged in the middle of the SO I electrode structure layer, and the bonding blocks are respectively connected with the plurality of first bonding anchor points in a bonding way, SO that the bonding blocks and the bonding planes of the SO I electrode structure layer are arranged in a hanging way.
Optionally, a plurality of second bonding anchor points which are arranged in a protruding mode are arranged in the middle of the bonding block, and the bonding block is respectively connected with the SO I electrode structure layer in a bonding mode through the second bonding anchor points, SO that bonding planes of the bonding block and the SO I electrode structure layer are arranged in a hanging mode.
The invention also provides a preparation method of the high overload torsion type silicon micro-accelerometer, which comprises the following steps:
a) Preparing a first SO I silicon wafer and a second SO I wafer for processing;
b) Processing a capacitance gap of a planar capacitance structure between an SO I electrode structure layer and a silicon sensitive structure on a first SO I silicon wafer through a deep silicon etching process;
c) Processing three electrostatic capacitance areas of the SO I electrode structure layer on the first SO I wafer through a photoetching process and a deep silicon etching process;
d) Etching a first bonding anchor point on a static capacitance area positioned in the middle of three static capacitance areas through a photoetching process and a deep silicon etching process on a first SO I wafer;
e) Epitaxially producing a silicon dioxide layer on the first SO I wafer;
f) Removing a silicon dioxide layer on the surface of the SO I electrode structure layer on the first SO I wafer through a photoetching process and a wet etching process;
g) Bonding the first SO I wafer and the second SO I wafer which are processed with the SO I electrode structure layer structure together in a bonding mode;
h) Removing the silicon layer on the back surface of the second SO I wafer by a polishing reduction method;
i) On the bonded second SO I wafer, reducing the silicon dioxide oxide layer in the area corresponding to the groove on one side of the mass block by a specified depth through a photoetching process;
j) Processing the pattern of the silicon sensitive structure on the bonded second SO I wafer through a photoetching process and a wet etching process;
k) Etching the pattern of the silicon sensitive structure to a designated depth on the bonded second SO I wafer through a deep silicon etching process;
l) on the bonded second SO I wafer, completely removing silicon dioxide in the corresponding area of the groove on the mass block through a wet etching process;
m) on the second SO I wafer after bonding, continuing to adopt a deep silicon etching process, completely etching the outer frames of the support beam and the silicon sensitive structure to form open grooves, and etching the grooves on the mass block to a specified depth SO as to enable the mass sizes on two sides of the mass block to be different;
n) continuously removing the silicon dioxide layer on the surface by adopting a deep silicon etching process on the second SO I wafer after bonding.
Compared with the prior art, the invention has the following advantages:
1. the silicon sensitive structure comprises a mass block, a bonding block and a supporting beam, wherein the bonding block and the supporting beam are formed by etching the middle part of the mass block, the bonding block is connected with the SO I electrode structure layer through bonding anchor points in a bonding way, SO that bonding planes of the bonding block and the SO I electrode structure layer are arranged in a hanging way, and the bonding anchor points are arranged in a smart way, SO that the bonding stress generation at the bonding anchor points and the supporting beam is avoided due to the advantage of low stress of bonding connection, and the wafer-level bonding stress is greatly reduced; and as each bonding plane is suspended, the bonding plane deforms downwards to play a role of buffering under the condition of high overload, so that the shock resistance of a sensitive structure can be improved, the overload resistance of the silicon micro-accelerometer can be effectively improved, and the service life and long-term reliability of the product are effectively ensured.
2. The silicon sensitive structure comprises the mass block, the bonding block and the supporting beam, wherein the bonding block and the supporting beam are formed by etching the middle part of the mass block, the bonding block is connected with the SOI electrode structure layer through the bonding anchor point in a bonding way, so that the bonding planes of the bonding block and the SOI electrode structure layer are arranged in a hanging way, the bonding anchor point layout is skillfully designed, the bonding flatness between the silicon sensitive structure and the SOI electrode structure layer is improved to a great extent, the consistency of capacitance gaps is improved, and the processing precision is higher.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic perspective view of a high-overload swing type silicon micro-accelerometer according to an embodiment of the invention.
Fig. 2 is a schematic perspective view of a front side of a silicon sensor structure according to a first embodiment of the present invention.
Fig. 3 is a schematic perspective view of a back side of a silicon sensitive structure according to a first embodiment of the present invention.
Fig. 4 is a schematic perspective view of an SOI electrode structure layer according to a first embodiment of the present invention.
Fig. 5 is a partial schematic structural view of the section A-A of fig. 2.
FIG. 6 is a schematic diagram showing the intermediate structure of the product in the preparation method according to the first embodiment of the present invention.
Legend reference numerals illustrate: 1. an SOI electrode structure layer; 11. an electrostatic capacitance region; 12. a lead pad; 13. a first bonding anchor; 2. a silicon sensitive structure; 21. a mass block; 211. a groove; 22. a bonding block; 221. a second bonding anchor; 23. a support beam; 24. an open slot.
Detailed Description
Embodiment one:
as shown in fig. 1, fig. 2, fig. 3 and fig. 4, the embodiment provides a high overload torsion pendulum type silicon micro-accelerometer, which comprises an SO I electrode structure layer 1 and a silicon sensitive structure 2, wherein three electrostatic capacitance areas 11 and corresponding lead plates 12 are arranged on the SO I electrode structure layer 1, the silicon sensitive structure 2 comprises a mass block 21, a bonding block 22 and a supporting beam 23, the bonding blocks 22 and the supporting beam 23 are formed by etching the middle part of the mass block 21, the two sides of the mass block 21 are different in mass size and are arranged opposite to the three electrostatic capacitance areas 11 in a clearance manner to form a plane capacitance structure, the bonding block 22 is connected with the mass block 21 through the supporting beam 23, and bonding anchor points are used for bonding connection between the bonding block 22 and the SO I electrode structure layer 1, SO that bonding planes of the bonding block 22 and the SO I electrode structure layer 1 are arranged in a suspended manner. By skillfully designing the layout of the bonding anchor points, the bonding connection has the advantage of low stress, so that the generation of direct bonding stress at the bonding anchor points and the supporting beam is avoided, and the wafer-level bonding stress is greatly reduced; and as each bonding plane is suspended, the bonding plane deforms downwards to play a role of buffering under the condition of high overload, so that the shock resistance of the sensitive structure can be improved, the overload resistance (the overload resistance can reach more than 15000 g) of the silicon micro-accelerometer can be effectively improved, and the service life and long-term reliability of the product are effectively ensured. Moreover, through the ingenious design of the layout of the bonding anchor points, the bonding flatness between the silicon sensitive structure and the SO I electrode structure layer is improved to a large extent, SO that the consistency of capacitance gaps is improved, and the processing precision is higher.
The difference in mass size on both sides of the mass block 21 is a known basic element for realizing detection, and the difference in mass size on both sides of the mass block 21 can be realized by partially or totally different grooves, holes and shapes on both sides of the mass block 21. For example, referring to fig. 2, in this embodiment, a groove 211 is formed on one side of the mass 21 to make the mass on two sides of the mass 21 different, and it is preferable that the groove 211 has a symmetrical structure and is symmetrical about the Y axis (the reference symbol a in fig. 2 indicates the X axis). The side with the grooves 211 and the side with the raw grooves 211 are bilaterally symmetrical with respect to the center points of the support beam 23 and the mass 21. Specifically, the recess 211 is square in the present embodiment, but needless to say, the shape of the recess 211 is not limited to the square shown in fig. 2 for the purpose of achieving the mass size on both sides of the mass 21.
Referring to fig. 2, in this embodiment, two through open slots 24 formed by etching process are provided in the middle of the mass block 21, and the openings of the two open slots 24 are arranged opposite to each other so that the inner region of the open slot 24 and the middle connecting portion with opposite openings form a bonding block 22, and two support beams 23 are respectively formed between the open edges of two sides of the two open slots 24, and the support beams 23 on two sides are symmetrically arranged. The inner areas of the two open grooves 24 and the middle connecting parts with opposite openings form the I-shaped bonding blocks 22, so that the relative flatness of the silicon sensitive structure 2 and the SOI electrode structure layer 1 during low-stress bonding can be improved, and the capacitance gaps formed by the two open grooves are more consistent after the low-stress bonding. It should be noted that, referring to fig. 2, the open slot 24 is a C-shaped slot, but the "C" of the C-shaped slot expresses a non-closed structure to form the bonding block 22 and the supporting beam 23 in the middle of the mass 21, so the "C" is not limited to a specific font, and thus the inner area of the single C-shaped slot may be a rounded rectangular structure as shown in fig. 2, or may be a circular, oval or other irregularly shaped structure.
As shown in fig. 2 and 4, the support beams 23 on both sides in the present embodiment are symmetrically arranged with respect to the central axes of the three electrostatic capacity regions 11 (as shown in fig. 4 b), and the axes of the two support beams 23 (as shown in fig. 2 a) are perpendicular to the central axes of the three electrostatic capacity regions 11.
As shown in fig. 5, the cross section of the support beam 23 in this embodiment is rectangular, which corresponds to the use of a dry etching process. The cross section of the support beam 23 is not limited to the rectangular shape shown in fig. 5, and other etching processes may be employed as needed to prepare a more complex cross-sectional shape of the support beam 23, preferably requiring the support beam 23 to be symmetrical in structure and symmetrical about the Y-axis and coincident with the symmetry axis.
Referring to fig. 2, 3 and 4, in this embodiment, a plurality of first bonding anchor points 13 arranged in a protruding manner are provided at the middle part of the SOI electrode structure layer 1, a plurality of second bonding anchor points 221 arranged in a protruding manner are provided at the middle part of the bonding block 22, the first bonding anchor points 13 and the second bonding anchor points 221 are in one-to-one correspondence and are connected in a bonding manner, so that the bonding block 22 and the bonding plane of the SOI electrode structure layer 1 are arranged in a suspended manner, and the center of the silicon sensitive structure 2 is aligned with the center points of the plurality of first bonding anchor points 13 on the SOI electrode structure layer 1. Due to the adoption of the bonding anchor points which are arranged in a protruding mode in two layers of the first bonding anchor point 13 and the second bonding anchor point 221, when bonding planes of the bonding block 22 and the SOI electrode structure layer 1 are arranged in a hanging mode, on one hand, the hanging height range is larger, on the other hand, the etching processing amount of the two layers of the first bonding anchor point 13 and the second bonding anchor point 221 is smaller, the hanging height is divided into the two parts of the first bonding anchor point 13 and the second bonding anchor point 221 (the higher the processing height is, the larger the error is, the bonding flatness between the silicon sensitive structure and the SOI electrode structure layer is affected, the poor consistency of capacitance gaps is caused, the bonding flatness between the silicon sensitive structure and the SOI electrode structure layer can be effectively improved, the consistency of capacitance gaps is improved, and the processing precision is higher.
Referring to fig. 4, in this embodiment, the first bonding anchor 13 is disposed on the surface of the middle electrostatic capacitance region 11 among the three electrostatic capacitance regions 11, and the height of the first bonding anchor 13 is higher than that of the three electrostatic capacitance regions 11, so that the height of the first bonding anchor 13 can be divided into two parts of the heights of the first bonding anchor 13 and the middle electrostatic capacitance region 11 (the higher the processing height is, the larger the error is, so that the bonding flatness between the silicon sensitive structure and the SOI electrode structure layer is affected, and the uniformity of the capacitance gap is poor), so that the bonding flatness between the silicon sensitive structure and the SOI electrode structure layer can be effectively improved, and the uniformity of the capacitance gap is improved, and the processing precision is higher.
Referring to fig. 4, among the lead pads 12 corresponding to the three electrostatic capacity regions 11 of the SOI electrode structure layer 1 in the present embodiment, the lead pad 12 corresponding to the electrostatic capacity region 11 located in the middle serves as a ground electrode, and the lead pads 12 corresponding to the electrostatic capacity regions 11 located at both ends serve as detection electrodes. When the mass block 21 is overloaded, the difference of the mass values at the two sides of the mass block 21 causes the capacitance of the corresponding electrostatic capacitance region 11 to change, so that a corresponding detection signal can be obtained. Referring to fig. 4, in this embodiment, the SOI electrode structure layer 1 is located on the same side of the three electrostatic capacitance regions 11 and each leads out one lead pad 12 (such that the lead pads 12 are distributed on one side), and the three lead pads 12 are arranged in axisymmetric with respect to the center line of the SOI electrode structure layer 1/the axes of the two support beams 23 (as shown in fig. 2 a).
Referring to fig. 3 and 4, in the present embodiment, the number of the first bonding anchor points 13 and the second bonding anchor points 221 is four, and the four second bonding anchor points 221 are symmetrically distributed about the central axis of the mass 21, and the four first bonding anchor points 13 are symmetrically distributed about the central axes of the three electrostatic capacitance regions 11 on the SOI electrode structure layer 1. The number of the first bonding anchor points 13 and the second bonding anchor points 221 is four, the opening grooves 24 are combined to form C-shaped grooves, the inner areas of the two C-shaped grooves and the middle connecting parts with opposite openings form the structure of the bonding block 22 in the shape of an I, the relative flatness of the silicon sensitive structure 2 and the SOI electrode structure layer 1 during low-stress bonding can be further improved, and after the low-stress bonding, the capacitance gaps formed by the silicon sensitive structure 2 and the SOI electrode structure layer 1 are more consistent. Meanwhile, when the overall structure is high in overload impact, the supporting center areas of the four bonding anchor points can play a role in buffering, and the overload resistance index of the product can be greatly improved.
In the present embodiment, the first bonding anchor 13 and the second bonding anchor 221 are both square, have equal areas, and are axisymmetric about the X-axis (the axial direction of the support beam 23) and the Y-axis (the axial direction perpendicular to the support beam 23). It should be noted that, the first bonding anchor 13 and the second bonding anchor 221 are not limited to square, and bonding anchors of other shapes may be used. Similarly, the number of the first bonding anchor points 13 and the second bonding anchor points 221 is not limited to four, and may be set according to practical needs, and it is preferable that the four second bonding anchor points 221 on the silicon sensitive structure 2 are symmetrically distributed about the central axis of the support beam 23 and the mass block 23, and the first bonding anchor points 13 in the middle of the SO I electrode structure layer 1 are symmetrically distributed about the central axis of the electrostatic capacitance region 11.
The embodiment provides a preparation method of the high overload torsion type silicon micro-accelerometer, which comprises the following steps:
a) Preparing a first SO I silicon wafer and a second SO I wafer for processing;
b) Processing a capacitance gap of a planar capacitance structure between the SO I electrode structure layer 1 and the silicon sensitive structure 2 on a first SO I silicon wafer through a deep silicon etching process;
c) On the first SO I wafer, continuing to process the three electrostatic capacitance areas 11 of the SO I electrode structure layer 1 through a photolithography process and a deep silicon etching process;
d) Continuing to etch a first bonding anchor point 13 on the electrostatic capacitance region 11 positioned in the middle among the three electrostatic capacitance regions 11 through a photoetching process and a deep silicon etching process on the first SO I wafer;
e) Epitaxially producing a silicon dioxide layer on the first SO I wafer;
f) Removing a silicon dioxide layer on the surface of the SO I electrode structure layer 1 on the first SO I wafer through a photoetching process and a wet etching process;
g) Bonding the first SO I wafer and the second SO I wafer which are processed to form the structure of the SO I electrode structure layer 1 together in a bonding mode;
h) Removing the silicon layer on the back surface of the second SO I wafer by a polishing reduction method;
i) On the bonded second SO I wafer, reducing the silicon dioxide oxide layer in the corresponding area of the groove 211 on one side of the mass block 21 by a specified depth through a photoetching process;
j) Processing the pattern of the silicon sensitive structure 2 on the bonded second SO I wafer through a photoetching process and a wet etching process;
k) Etching the pattern of the silicon sensitive structure 2 to a designated depth on the bonded second SO I wafer through a deep silicon etching process;
l) on the bonded second SO I wafer, completely removing silicon dioxide in the area corresponding to the groove 211 on the mass block 21 through a wet etching process;
m) on the second SO I wafer after bonding, continuing to adopt a deep silicon etching process, completely etching the support beam 23 and the outer frame of the silicon sensitive structure 2 to form an open slot 24, and etching the grooves 211 on the mass block 21 to a specified depth SO that the mass sizes of the two sides of the mass block 21 are different;
n) continuously removing the silicon dioxide layer on the surface by adopting a deep silicon etching process on the second SO I wafer after bonding.
The structures in the corresponding states of the steps a to n are respectively shown in the sub-graphs a to n in fig. 6, and after the structure of the sub-graph n in fig. 6 is obtained, the redundant parts around the structure are removed, so that the high overload torsion pendulum type silicon micro-accelerometer in the embodiment can be obtained. The preparation method of the high overload swing type silicon micro-accelerometer adopts dry etching to prepare the high overload swing type silicon micro-accelerometer, can be formed by a set of mask photoetching dry etching, can greatly reduce the area of devices, can realize high-quality, high-precision and large-batch processing, improves consistency and reduces production cost; meanwhile, the damage force of high-load impact to the structure can be effectively buffered, and the service life and reliability of the product are effectively ensured.
Embodiment two:
the present embodiment is basically the same as the first embodiment, and the main difference is that the implementation manner of the "bonding plane suspension arrangement of the bonding block 22 and the SO I electrode structure layer 1" is different. In this embodiment, the middle part of the SO I electrode structure layer 1 is provided with a plurality of first bonding anchor points 13 arranged in a protruding manner, and the bonding blocks 22 are respectively connected with the plurality of first bonding anchor points 13 in a bonding manner, SO that the bonding planes of the bonding blocks 22 and the SO I electrode structure layer 1 are arranged in a suspended manner; i.e. no additional bond anchors are required on the bond block 22 to simplify the structure of the silicon sensitive structure 2. The preparation method is adaptively adjusted according to the structural change, so that the preparation of the high overload torsion pendulum type silicon micro-accelerometer with the changed structure can be realized.
Embodiment III:
the present embodiment is basically the same as the first embodiment, and the main difference is that the implementation manner of the "bonding plane suspension arrangement of the bonding block 22 and the SO I electrode structure layer 1" is different. In this embodiment, the middle part of the bonding block 22 is provided with a plurality of second bonding anchor points 221 that are arranged in a protruding manner, and the bonding block 22 is respectively connected with the SO I electrode structure layer 1 in a bonding manner through the second bonding anchor points 221, SO that the bonding planes of the bonding block 22 and the SO I electrode structure layer 1 are arranged in a suspended manner. I.e. no additional bonding anchor points are arranged on the SO I electrode structure layer 1 to simplify the structure of the SO I electrode structure layer 1. The preparation method is adaptively adjusted according to the structural change, so that the preparation of the high overload torsion pendulum type silicon micro-accelerometer with the changed structure can be realized.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above examples, and all technical solutions belonging to the concept of the present invention belong to the protection scope of the present invention. It should be noted that modifications and adaptations to the present invention may occur to one skilled in the art without departing from the principles of the present invention and are intended to be within the scope of the present invention.
Claims (9)
1. The utility model provides a high overload torsion pendulum-type silicon micro-accelerometer, its characterized in that includes SOI electrode structure layer (1) and silicon sensitive structure (2), be equipped with three electrostatic capacitance region (11) and its corresponding lead plate (12) on SOI electrode structure layer (1), silicon sensitive structure (2) include mass piece (21) and bonding piece (22) and supporting beam (23) that the middle part etching of mass piece (21) formed, mass piece (21) both sides quality is different and with three electrostatic capacitance region (11) relative clearance arrangement form plane capacitance structure, bonding piece (22) link to each other with mass piece (21) through supporting beam (23), link to each other through bonding anchor bonding between bonding piece (22) and SOI electrode structure layer (1) and make bonding piece (22) and SOI electrode structure layer (1) bonding plane unsettled the arrangement of both sides, the middle part of mass piece (21) is equipped with two and adopts etching technology formed, opening groove (24) that run through of two opening grooves (24) are arranged relatively makes opening groove (24) and two both sides of opening groove (23) and two opposite opening groove (23) and two opening groove that form the opening between the two opposite edge of opening groove (23) and the opening groove that are formed respectively.
2. The high overload torsion pendulum type silicon micro accelerometer according to claim 1, wherein the supporting beams (23) on two sides are symmetrically arranged relative to the central axes of the three electrostatic capacitance areas (11), and the axes of the two supporting beams (23) are perpendicular to the central axes of the three electrostatic capacitance areas (11).
3. The high overload torsional pendulum type silicon micro accelerometer according to claim 1, wherein a plurality of first bonding anchor points (13) which are arranged in a protruding mode are arranged in the middle of the SOI electrode structure layer (1), a plurality of second bonding anchor points (221) which are arranged in a protruding mode are arranged in the middle of the bonding block (22), the first bonding anchor points (13) and the second bonding anchor points (221) are in one-to-one correspondence and are connected in a bonding mode, the bonding block (22) and the bonding plane of the SOI electrode structure layer (1) are arranged in a hanging mode, and the center of the silicon sensitive structure (2) is aligned with the center point of the plurality of first bonding anchor points (13) on the SOI electrode structure layer (1).
4. A high overload torsion pendulum type silicon micro-accelerometer according to claim 3, wherein the first bonding anchor (13) is arranged on the surface of the electrostatic capacitance region (11) located in the middle among the three electrostatic capacitance regions (11), and the height of the first bonding anchor (13) is higher than the three electrostatic capacitance regions (11).
5. A high overload torsion pendulum type silicon micro-accelerometer according to claim 3, wherein, of the lead pads (12) corresponding to the three electrostatic capacitance regions (11) of the SOI electrode structure layer (1), the lead pad (12) corresponding to the electrostatic capacitance region (11) located in the middle is used as a ground electrode, and the lead pads (12) corresponding to the electrostatic capacitance regions (11) located at both ends are used as detection electrodes.
6. The high overload torsional pendulum type silicon micro accelerometer according to claim 5, wherein the number of the first bonding anchor points (13) and the second bonding anchor points (221) is four, the four second bonding anchor points (221) are symmetrically distributed about the central axis of the mass block (21), and the four first bonding anchor points (13) are symmetrically distributed about the central axis of the three electrostatic capacitance regions (11) on the SOI electrode structure layer (1).
7. A high overload torsion pendulum type silicon micro-accelerometer according to any one of claims 1 to 3, wherein the middle part of the SOI electrode structure layer (1) is provided with a plurality of first bonding anchor points (13) which are arranged in a protruding way, and the bonding blocks (22) are respectively connected with the plurality of first bonding anchor points (13) in a bonding way so that bonding planes of the bonding blocks (22) and the SOI electrode structure layer (1) are arranged in a hanging way.
8. A high overload torsion pendulum type silicon micro accelerometer according to any one of claims 1 to 3, wherein a plurality of second bonding anchor points (221) which are arranged in a protruding manner are arranged at the middle part of the bonding block (22), and the bonding block (22) is respectively connected with the SOI electrode structure layer (1) in a bonding manner through the second bonding anchor points (221) so that the bonding planes of the bonding block (22) and the SOI electrode structure layer (1) are arranged in a suspending manner.
9. A method of making a high overload torsion pendulum type silicon micro-accelerometer according to any one of claims 1 to 6, comprising:
a) Preparing a first SOI silicon wafer and a second SOI wafer for processing;
b) Processing a capacitance gap of a planar capacitance structure between an SOI electrode structure layer (1) and a silicon sensitive structure (2) on a first SOI silicon wafer through a deep silicon etching process;
c) On the first SOI wafer, continuing to process three electrostatic capacitance areas (11) of the SOI electrode structure layer (1) through a photoetching process and a deep silicon etching process;
d) Continuing to etch a first bonding anchor point (13) on the electrostatic capacitance region (11) positioned in the middle among the three electrostatic capacitance regions (11) through a photoetching process and a deep silicon etching process on the first SOI wafer;
e) Epitaxially producing a silicon dioxide layer on the first SOI wafer;
f) Removing a silicon dioxide layer on the surface of an SOI electrode structure layer (1) on a first SOI wafer through a photoetching process and a wet etching process;
g) Bonding the first SOI wafer and the second SOI wafer which are processed with the SOI electrode structure layer (1) structure together in a bonding mode;
h) Removing the silicon layer on the back surface of the second SOI wafer by a polishing reducing method;
i) On the bonded second SOI wafer, reducing the silicon dioxide oxide layer in the area corresponding to the groove (211) on one side of the mass block (21) by a specified depth through a photoetching process;
j) Processing the pattern of the silicon sensitive structure (2) on the bonded second SOI wafer through a photoetching process and a wet etching process;
k) Etching the pattern of the silicon sensitive structure (2) to a designated depth on the bonded second SOI wafer through a deep silicon etching process;
l) on the second SOI wafer after bonding, completely removing silicon dioxide in the corresponding area of the groove (211) on the mass block (21) through a wet etching process;
m) continuing to adopt a deep silicon etching process on the second SOI wafer after bonding, completely etching the support beam (23) and the outer frame of the silicon sensitive structure (2) to form an open slot (24), and etching the grooves (211) on the mass block (21) to a specified depth so as to enable the mass sizes at two sides of the mass block (21) to be different;
n) continuously adopting a deep silicon etching process to remove the silicon dioxide layer on the surface on the second SOI wafer after bonding.
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