CN113970655B - MEMS accelerometer and forming method thereof - Google Patents
MEMS accelerometer and forming method thereof Download PDFInfo
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- CN113970655B CN113970655B CN202111588756.9A CN202111588756A CN113970655B CN 113970655 B CN113970655 B CN 113970655B CN 202111588756 A CN202111588756 A CN 202111588756A CN 113970655 B CN113970655 B CN 113970655B
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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
- B81B7/02—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
- B81C1/00349—Creating layers of material on a substrate
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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
- B81C1/00388—Etch mask forming
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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
- B81C1/00436—Shaping materials, i.e. techniques for structuring the substrate or the layers on the substrate
- B81C1/00523—Etching material
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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
Abstract
The invention relates to a MEMS accelerometer and a forming method thereof, wherein the MEMS accelerometer comprises: a substrate; the proof mass is elastically connected to the substrate; the top fixed electrode is arranged on one side of the proof mass block, which is far away from the substrate; the bottom fixed electrode is arranged on one side of the proof mass block, which is far away from the top fixed electrode; the top fixed electrode and the proof mass block form a first capacitor, the bottom fixed electrode and the proof mass block form a second capacitor, and the first capacitor and the second capacitor form a differential capacitor. According to the technical scheme, the differential capacitance is used for measuring the Z-axis acceleration only by one substrate, and the equivalent function which can be achieved by at least two substrates in the related technology is achieved, so that the structure of the MEMS accelerometer is simplified, and the manufacturing process cost is reduced; because the top fixed electrode is arranged above the proof mass block, and the bottom fixed electrode is arranged below the proof mass block, the generated differential capacitance value is increased, the sensitivity is improved, and the requirement on a signal processing circuit is reduced.
Description
Technical Field
The invention relates to the technical field of micro-electro-mechanical systems, in particular to a micro-electro-mechanical system (MEMS) accelerometer and a forming method thereof.
Background
An inertial sensor is a device that is capable of sensing and/or generating motion. An inertial sensor is a device that includes a microelectromechanical system. Such MEMS devices include accelerometers capable of sensing acceleration. Accelerometers are one of the main devices of inertial navigation and guidance systems. Compared with traditional mechanical and optical sensors, the MEMS sensor has the advantages of low cost, small volume and low power consumption, and can be integrated with an integrated circuit.
MEMS sensors are widely used in the fields of consumer electronics, industrial manufacturing, medical electronics, automotive electronics, aerospace, and military. MEMS sensors have great potential for development and commercial value. The operating principle of MEMS accelerometers is the inertial effect. When the object is moved, the suspended microstructure is affected by inertial forces, and the change of the accelerometer signal is proportional to the linear acceleration. MEMS accelerometers are mainly classified into capacitive type, piezoresistive type, piezoelectric type, optical type, and the like according to the detection mode. Meanwhile, the capacitive detection method used in the MEMS accelerometer is widely applied in industry mainly because of the simple structure and the compatibility of the working mode and the semiconductor technology. MEMS chips can be manufactured by semiconductor manufacturing methods and can have the single or multiple device compositions described above. The acceleration can be measured in a number of ways using capacitive methods. One of the methods is to use a differential capacitor formed by two capacitors and arranged in such a way that when subjected to acceleration, one of the capacitance values increases and the other decreases, which allows to increase the variation value of the capacitance and to improve the measurement accuracy.
However, in the related art, there are some technical difficulties in manufacturing a MEMS accelerometer having differential capacitance to measure acceleration along a Z-axis perpendicular to a substrate plane. In order to produce the differential capacitance, it is necessary to use an additional substrate and apply electrodes thereon, and also to perform an operation of connecting the substrates, which results in a great increase in cost and difficulty in manufacturing such a structure.
Disclosure of Invention
The invention aims to provide the MEMS accelerometer, which has the advantages of reducing the manufacturing process cost, increasing the generated differential capacitance value, improving the sensitivity, reducing the requirement on a signal processing circuit and having better applicability.
In order to achieve the purpose, the invention adopts the following technical scheme:
a MEMS accelerometer, comprising:
a substrate;
a proof mass elastically connected to the substrate;
the top fixed electrode is arranged on one side of the proof mass, which is far away from the substrate;
the bottom fixed electrode is arranged on one side, away from the top fixed electrode, of the proof mass;
the top fixed electrode and the proof mass form a first capacitor, the bottom fixed electrode and the proof mass form a second capacitor, and the first capacitor and the second capacitor form a differential capacitor.
Preferably, the top fixed electrodes are provided in plurality, and each top fixed electrode is arranged on one side of the proof mass away from the substrate; the bottom fixed electrodes are arranged in a plurality, and each bottom fixed electrode is arranged on one side, away from the top fixed electrode, of the proof mass block.
Preferably, eight top fixed electrodes are arranged, and two top fixed electrodes are arranged at intervals along each side edge part of the proof mass; eight bottom fixed electrodes are arranged at intervals along the center of the proof mass block;
or the number of the bottom fixed electrodes is four, the number of the top fixed electrodes is four, and each top fixed electrode and each corner end of the proof mass block are correspondingly arranged.
Preferably, the proof mass has a plurality of through holes formed therethrough in a thickness direction thereof.
Preferably, the top fixed electrode is formed with a plurality of slots penetrating along a thickness direction thereof.
Preferably, the MEMS accelerometer further includes a first signal line disposed on the substrate, and a second signal line disposed at an interval from the first signal line, the first signal line is disposed along a side edge of the proof mass and electrically connected to the top fixed electrode, and the second signal line is electrically connected to the bottom fixed electrode.
Preferably, the MEMS accelerometer further comprises a fixed anchor disposed on a side surface of the substrate facing the proof mass, and an elastic suspension disposed in connection with the fixed anchor, wherein the proof mass is elastically connected to the fixed anchor through the elastic suspension.
Preferably, the number of the fixing anchors is four, each fixing anchor comprises a first anchor portion arranged on the substrate and a second anchor portion arranged on the first anchor portion, the second anchor portion penetrates through the inspection mass block, the number of the elastic suspensions is four, and each second anchor portion is connected with each elastic suspension in a one-to-one correspondence manner.
The invention also provides a method for forming the MEMS accelerometer, which comprises the following steps:
depositing a polycrystalline silicon film on a substrate, obtaining a first structural layer with a bottom fixed electrode after photoetching and etching drawing, depositing a phosphorosilicate glass layer on the first structural layer, annealing, and etching an anchor hole to obtain a first sacrificial layer;
depositing a polycrystalline silicon film and a phosphorosilicate glass layer on the first sacrificial layer, annealing, photoetching, etching and drawing to obtain a second structural layer with a part of top fixed electrode and a proof mass block, depositing the phosphorosilicate glass layer on the second structural layer, annealing, and etching the anchor hole to obtain a second sacrificial layer;
and depositing a polycrystalline silicon thin film and a phosphorosilicate glass layer on the second sacrificial layer, annealing, and performing photoetching and etching drawing to obtain a third structural layer with another part of top fixed electrodes.
Preferably, before obtaining the first structural layer, the method further comprises: depositing a silicon nitride layer on the substrate; after obtaining the third structural layer, the method further includes: and removing the first sacrificial layer and the second sacrificial layer.
Compared with the prior art, the invention has the beneficial effects that:
according to the MEMS accelerometer provided in the technical scheme, the proof mass is elastically connected to the substrate, the top fixed electrode is arranged on one side, away from the substrate, of the proof mass, and the bottom fixed electrode is arranged on one side, away from the top fixed electrode, of the proof mass, so that a first capacitor is formed based on the top fixed electrode and the proof mass, a second capacitor is formed based on the bottom fixed electrode and the proof mass, a differential capacitor is formed between the first capacitor and the second capacitor, the differential capacitor can be used for measuring the Z-axis acceleration only by one substrate, the equivalent function which can be achieved by at least two substrates in the related technology is achieved, the structure of the MEMS accelerometer is simplified, and the manufacturing process cost is reduced; meanwhile, the top fixed electrode is arranged above the proof mass block, and the bottom fixed electrode is arranged below the proof mass block, so that the generated differential capacitance value is increased, the sensitivity is improved, the requirement on a signal processing circuit is reduced, and the method has better applicability.
Drawings
FIG. 1 is a schematic view of a MEMS accelerometer according to one embodiment of the present invention;
FIG. 2 is a schematic view of the MEMS accelerometer of FIG. 1 having a bottom fixed electrode;
FIG. 3 is a schematic cross-sectional view taken along line A-A of FIG. 1;
FIG. 4 is a schematic cross-sectional view taken along line B-B of FIG. 1;
FIG. 5 is a schematic diagram of the MEMS accelerometer reflecting the direction of the sensing signal under the action of acceleration according to the embodiment of the invention;
FIG. 6 is a schematic view of a MEMS accelerometer according to another embodiment of the present invention;
FIG. 7 is a schematic topological diagram of a MEMS accelerometer according to yet another embodiment of the present invention;
FIG. 8 is a schematic diagram of a MEMS accelerometer with an alternative resilient suspension;
FIG. 9 is a schematic view of a first structural layer and a substrate;
FIG. 10 is a schematic view of a first structural layer, a first sacrificial layer and a substrate;
FIG. 11 is a schematic view of a first structural layer, a first sacrificial layer, a second structural layer and a substrate;
FIG. 12 is a schematic view of a first structural layer, a first sacrificial layer, a second structural layer, a second sacrificial layer and a substrate;
fig. 13 is a schematic view of a first structural layer, a first sacrificial layer, a second structural layer, a second sacrificial layer, a third structural layer, and a substrate.
Description of the symbols of the drawings:
1. a substrate; 2. a proof mass; 21. a through hole; 3. a top fixed electrode; 31. a slot; 32. a through hole; 4. the bottom is fixed with an electrode; 5. a first signal line; 6. fixing an anchor; 61. a first anchor portion; 62. a second anchor portion; 7. an elastic suspension; 100. a first structural layer; 110. a first sacrificial layer; 200. a second structural layer; 210. a second sacrificial layer; 300. a third structural layer; 400. and (4) an anchor hole.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Referring to fig. 1 and 8, an embodiment of the invention provides a MEMS accelerometer, including: the device comprises a substrate 1, a proof mass 2, a top fixed electrode 3, a bottom fixed electrode 4, a first signal wire 5, a second signal wire, a fixed anchor 6 and an elastic suspension 7.
The proof mass 2 is elastically connected to the substrate 1; the top fixed electrode 3 is arranged on one side of the proof mass 2 away from the substrate 1; the bottom fixed electrode 4 is arranged on one side of the proof mass 2 far away from the top fixed electrode 3; the top fixed electrode 3 and the proof mass 2 form a first capacitor, the bottom fixed electrode 4 and the proof mass 2 form a second capacitor, and the first capacitor and the second capacitor form a differential capacitor.
It should be noted that in the present embodiment, the substrate 1 may include any suitable substrate 1 material known in the art, for example, a semiconductor material silicon or any other semiconductor material or non-semiconductor material, such as glass, plastic, metal or ceramic, and if desired, the substrate 1 may include an integrated circuit fabricated thereon; the proof mass 2 is a fully symmetric structure, and the proof mass 2, the top fixed electrodes 3 and the bottom fixed electrodes 4 may each comprise any suitable material known in the art, such as polysilicon or any other semiconductor material, and may have the same or different thickness of about a few microns to 100 microns, such as about 2 microns to 10 microns; the gap between proof mass 2 and top stationary electrode 3, and the gap between proof mass 2 and bottom stationary electrode 4 are each independently selected from about a few microns to about ten microns, such as, but not limited to, about 1 micron to about 10 microns.
As shown in fig. 5, one non-limiting MEMS accelerometer of the present invention operates on the following principle: defining the direction vertical to the upper surface of the substrate 1 as a Z-axis direction, the direction close to the upper surface of the substrate 1 as a negative direction, and the direction far away from the upper surface of the substrate 1 as a positive direction; if a linear acceleration in the negative direction is applied to the MEMS accelerometer in the Z-axis direction, the proof mass 2 is subjected to an inertial force, which moves the proof mass 2 upward, thereby reducing the gap between the top fixed electrode 3 and the proof mass 2, changing the first capacitance value, increasing the gap between the bottom fixed electrode 4 and the proof mass 2, changing the second capacitance value, and changing the value of the differential capacitance; if the MEMS accelerometer is applied a positive linear acceleration along the Z axis, the proof mass 2 will be subjected to inertial forces that move the proof mass 2 downward, increasing the gap between the top fixed electrode 3 and the proof mass 2 and decreasing the gap between the bottom fixed electrode 4 and the proof mass 2, thereby changing the value of the differential capacitance, the change in the value of the differential capacitance being proportional to the magnitude of the acceleration along the Z axis.
As can be seen from the above, by the top fixed electrode 3 disposed above the proof mass 2 and the bottom fixed electrode 4 disposed below the proof mass 2, when there is Z-axis acceleration, one capacitance increases and the other capacitance decreases, and combining them into a differential capacitance increases the differential capacitance by two times, which improves the sensitivity and reduces the requirements for the signal processing circuit; under the condition that only one substrate 1 is arranged, the top fixed electrode 3 and the proof mass block 2 form a first capacitor, the bottom fixed electrode 4 and the proof mass block 2 form a second capacitor, the first capacitor and the second capacitor form a differential capacitor, the additional substrate 1 is not needed to be additionally arranged, the fact that the differential capacitor is used for measuring Z-axis acceleration can be achieved, the equivalent function that at least two substrates 1 can reach in the related technology is achieved, meanwhile, only one layer of proof mass block 2 needs to be arranged, the proof mass block 2 is arranged between the bottom fixed electrode 4 and the top fixed electrode 3, the differential capacitor can be formed, the structure of the MEMS accelerometer is greatly simplified, and the manufacturing process cost is reduced.
It should be noted that one or more top fixed electrodes 3 may be provided, and may be adjusted according to design requirements, and each top fixed electrode 3 is disposed on one side of the proof mass 2 away from the substrate 1; one or more bottom fixed electrodes 4 are arranged and can be adjusted according to design requirements, and each bottom fixed electrode 4 is arranged on one side, away from the top fixed electrode 3, of the proof mass block 2; the first signal lines 5 and the second signal lines are both arranged on the substrate 1, the first signal lines 5 and the second signal lines are arranged at intervals, the first signal lines 5 are arranged along the side edges of the proof mass 2, the first signal lines 5 can be arranged into one or more, each top fixed electrode 3 is fixedly arranged on each first signal line 5 and is electrically connected with each first signal line 5, and of course, one first signal line 5 can also be electrically connected with a plurality of top fixed electrodes 3; the second signal line is electrically connected to the bottom fixed electrode 4, and the second signal line is not shown in the figure.
Fig. 1-2, wherein in one embodiment, eight top fixed electrodes 3 are provided, two top fixed electrodes 3 are provided at intervals along each side edge portion of the proof mass 2, eight first signal lines 5 are provided, and each first signal line 5 is electrically connected to each top fixed electrode 3 in a one-to-one correspondence; eight bottom fixed electrodes 4 are arranged and are arranged at intervals along the center of the proof mass block 2.
Specifically, four bottom fixed electrodes 4 are arranged along the length direction of the proof mass block 2, four bottom fixed electrodes 4 are arranged along the width direction of the proof mass block 2, the bottom fixed electrodes 4 arranged along the length direction of the proof mass block 2 and the bottom fixed electrodes 4 arranged along the length direction of the proof mass block 2 are adjacently arranged, and when the thickness of a lower layer affects the design of an upper structure layer, the arrangement mode of the bottom fixed electrodes 4 is adopted, so that the texture of the structure layer above the bottom fixed electrodes 4 is as small as possible; the first signal line 5 and the second signal line are used for transmitting signals and the like of capacitance value change, the first signal line 5 transmits a first capacitance signal, and the second signal line transmits a second capacitance signal, so that the Z-axis acceleration is measured.
In the present embodiment, a plurality of slots 31 are formed through the top fixed electrode 3 along the thickness direction thereof, and the removal of the sacrificial layer is facilitated at the final stage of the process flow through the slots 31.
Referring to fig. 6, in another embodiment, the difference from the previous embodiment is that, in the present embodiment, there are four bottom fixed electrodes 4, four top fixed electrodes 3 corresponding to the corner ends of the proof mass 2, four first signal lines 5, and ninety degrees or approximately ninety degrees of each first signal line 5.
Specifically, a plurality of slots 31 are formed in the portion of the top fixed electrode 3 corresponding to the first signal line 5, a plurality of through holes 32 are formed in the portion of the top fixed electrode 3 corresponding to the proof mass 2, and the through holes 32 and the slots 31 cooperate with each other to facilitate the removal of the sacrificial layer at the final stage of the process flow; in this embodiment, wherever proof mass 2 moves, the differential capacitance will be reduced or increased by twice the capacitance formed by only top fixed electrodes 3 and proof mass 2, or the capacitance formed by only bottom fixed electrodes 4 and proof mass 2; meanwhile, the number of the bottom fixed electrodes 4 can be reduced, and the cost is reduced.
As a preferred embodiment, as shown in fig. 1 and 6, the proof mass 2 is formed with a plurality of through holes 21 penetrating through the proof mass in the thickness direction, and the through holes 21 are not only provided to facilitate the removal of the sacrificial layer in the final stage of the process flow, but also to reduce the dissipation force through the plurality of through holes 21, and when there is Z-axis acceleration, the air moves better through the plurality of through holes 21, so that the displacement of the proof mass 2 is increased, which means that the change of the differential capacitance is larger, further increasing the sensitivity of measuring the Z-axis acceleration.
In other embodiments, as shown in figure 7, the proof mass 2 is not provided with through holes 21, in which case the damping force is increased and the MEMS accelerometer needs to be packaged in a vacuum.
In order to elastically connect the proof mass 2 to the substrate 1, the fixed anchor 6 is arranged on the surface of the substrate 1 on the side facing the proof mass 2, the elastic suspension 7 is connected with the fixed anchor 6, the proof mass 2 is elastically connected to the fixed anchor 6 through the elastic suspension 7, and then the proof mass 2 is elastically connected to the substrate 1 through the fixed anchor 6, because the acceleration along the plane direction (X axis and Y axis) of the substrate 1 does not influence the change of the differential capacitance value, the fixed anchor 6 is arranged, so that the proof mass 2 can be better ensured not to move along the axes under the action of inertia force; it should be noted that the number of the fixing anchors 6 and the elastic suspensions 7 can be adjusted according to design requirements.
Specifically, as shown in fig. 1, four fixing anchors 6 are provided, each fixing anchor 6 is disposed at a position near the middle of each side edge portion of the proof mass 2, so that the proof mass 2 is uniformly stressed, and simultaneously, it is more favorable for limiting displacement of the proof mass 2 along the X-axis and Y-axis directions, each fixing anchor 6 includes a first anchor portion 61 disposed on the substrate 1, and a second anchor portion 62 disposed on the first anchor portion 61, the second anchor portion 62 is inserted into the proof mass 2, four elastic suspensions 7 are provided, each second anchor portion 62 is connected to each elastic suspension 7 in a one-to-one correspondence manner, two elastic suspensions 7 are disposed along the length direction of the proof mass 2, and the other two elastic suspensions 7 are disposed along the width direction of the proof mass 2; wherein, the fixing anchor 6 comprises a first anchor part 61 and a second anchor part 62 which form a two-layer structure; in addition, the top fixed electrode 3 has a two-layer structure, and the proof mass 2, the bottom fixed electrode 4, the elastic suspension 7 and the first signal line 5 are all of one-layer structure.
One or more elastic beams are arranged in each elastic suspension 7, the number of the elastic beams in one or more elastic suspensions 7 can be different, please refer to fig. 8, the elastic suspension 7 can also be arranged in other forms, in this case, the length of the elastic beam is longer to reduce the flexibility coefficient of the elastic suspension 7.
9-13, embodiments of the present invention further provide a method for forming the MEMS accelerometer, comprising the steps of:
depositing a silicon nitride layer on the substrate 1; in particular, in order to reduce the influence of the electric field generated by other MEMS electrostatic and microelectronic devices on the substrate 1, doping techniques such as doping with phosphorus may be used, and if an n-type silicon substrate 1 is used, a phosphosilicate Glass (PSG) layer is used as a doping source in a standard diffusion furnace. After removing the PSG layer, a 0.6 μm Low-stress silicon nitride layer is deposited as an electrical isolation layer on the substrate 1 by Low Pressure Chemical Vapor Deposition (LPCVD), not shown in the figure.
As shown in fig. 9, a polysilicon thin film is deposited by Low Pressure Chemical Vapor Deposition (LPCVD), patterned by photolithography, which includes coating a wafer with a photoresist, exposing the photoresist with an appropriate mask, developing the exposed photoresist to create a desired etching mask to subsequently transfer the pattern into an underlying layer, and, after patterning the photoresist, etching in a plasma etching system to obtain a first structural layer 100, wherein the first structural layer 100 includes eight first signal lines 5, eight bottom fixed electrodes 4, and four first anchor portions 61 disposed on a substrate 1.
As shown in fig. 10, a phosphosilicate glass layer is deposited on the first structural layer 100 by a Low Pressure Chemical Vapor Deposition (LPCVD) method, annealed at 1050 ℃ for 1 hour in argon, and etched by Reactive Ion Etching (RIE) after photolithography and patterning are applied to obtain an anchor hole 400, and a first sacrificial layer 110 is obtained, in which a fixed anchor 6, an elastic suspension 7, and the like may be disposed in the anchor hole 400.
As shown in fig. 11, a polysilicon film is deposited on the first sacrificial layer 110, a phosphosilicate glass (PSG) layer with a thickness of 200 nm is deposited on the polysilicon film, the polysilicon film is doped with phosphorus from above and below the PSG layer by annealing at 1050 ℃ for 1 hour, the annealing is also used for significantly reducing the net stress of the polysilicon film, the polysilicon film and the PSG layer are patterned by photolithography using a designed mask to obtain a second structural layer 200, and the PSG layer is etched to generate a hard mask for subsequently etching the polysilicon film. The hard mask is more resistant to chemical etching of the polysilicon than the photoresist and ensures better pattern transfer into the polysilicon. After etching the polysilicon film, the photoresist is stripped off, and the remaining oxide hard mask is removed by RIE, wherein the second structural layer 200 includes a portion of the top fixed electrode 3, the proof mass 2, four second anchor portions 62 and four elastic suspensions 7, and each of the second anchor portions 62 is connected to each of the elastic suspensions 7 in a one-to-one correspondence manner.
As shown in fig. 12, a phosphosilicate glass layer is deposited on the second structure layer 200 and annealed, and a Reactive Ion Etching (RIE) anchor hole 400 is performed after applying a photolithography mapping, resulting in the second sacrificial layer 210.
As shown in fig. 13, a polysilicon thin film and a 200 nm thick phosphosilicate glass (PSG) layer are deposited on the second sacrificial layer 210, the PSG layer serves as an etching mask and a doping source for the polysilicon thin film, and the substrate 1 is annealed at 1050 ℃ for 1 hour to dope the polysilicon thin film and reduce the residual film stress. The polysilicon film is lithographically patterned. The PSG layer and the polysilicon film are etched by plasma and RIE processes, and then the photoresist is stripped and the mask oxide is removed, resulting in a third structural layer 300, wherein the third structural layer 300 comprises another portion of the top fixed electrode 3.
Removing the first sacrificial layer 110 and the second sacrificial layer 210 to release the structural layer of the MEMS accelerometer, the method of removing the first sacrificial layer 110 and the second sacrificial layer 210 is as follows: this is achieved by immersing the substrate 1 in a 49% hydrofluoric acid (HF) bath at 25 ℃ for 2 minutes. Then placed in distilled water and alcohol for 2 minutes, respectively, to reduce blocking, and placed in an oven at 110 ℃ for at least 10 minutes.
The MEMS accelerometer forming method provided by the invention ensures that the MEMS accelerometer with the differential capacitor is manufactured in one process flow, the differential capacitor is formed without using an extra substrate 1 with an electrode, and a plurality of or a plurality of layers of proof masses 2 are not required to be arranged, so that the operation times of the subsequent forming process are greatly reduced, and the manufacturing cost is obviously reduced; in addition, the manufacturing method of the semiconductor can also be adopted in the manufacturing of the MEMS accelerometer, so that the manufacturing cost of the MEMS accelerometer is further reduced.
The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereby, and any insubstantial changes and substitutions made by those skilled in the art based on the present invention are within the protection scope of the present invention.
Claims (8)
1. A MEMS accelerometer, comprising:
a substrate (1);
a proof mass (2) elastically connected to the substrate (1);
the array substrate comprises a plurality of top fixed electrodes (3), wherein each top fixed electrode (3) is arranged on one side, away from the substrate (1), of the proof mass block (2), eight top fixed electrodes (3) are arranged, and two top fixed electrodes (3) are arranged along each side edge of the proof mass block (2) at intervals;
the bottom fixed electrodes (4) are arranged on one side, away from the top fixed electrode (3), of the proof mass block (2), eight of the bottom fixed electrodes (4) are arranged, and the bottom fixed electrodes are arranged at intervals along the center of the proof mass block (2);
the device also comprises a fixed anchor (6) arranged on one side surface of the substrate (1) facing the proof mass (2), and an elastic suspension (7) connected with the fixed anchor (6), wherein the proof mass (2) is elastically connected to the fixed anchor (6) through the elastic suspension (7);
the top fixed electrode (3) and the proof mass block (2) form a first capacitor, the bottom fixed electrode (4) and the proof mass block (2) form a second capacitor, and the first capacitor and the second capacitor form a differential capacitor, so that the differential capacitor can be used for measuring the Z-axis acceleration by using the substrate (1) only.
2. The MEMS accelerometer according to claim 1, wherein there are four bottom fixed electrodes (4) and four top fixed electrodes (3), each top fixed electrode (3) being arranged in correspondence with each corner end of the proof mass (2).
3. The MEMS accelerometer according to claim 1, wherein the proof mass (2) has a plurality of through holes (21) formed therethrough in a thickness direction thereof.
4. The MEMS accelerometer according to claim 1, wherein the top fixed electrode (3) has a plurality of slots (31) formed through it in its thickness direction.
5. The MEMS accelerometer according to claim 1, further comprising a first signal line (5) disposed on the substrate (1), and a second signal line disposed spaced apart from the first signal line (5), the first signal line (5) being disposed along a side edge of the proof mass (2) and electrically connected to the top fixed electrode (3), the second signal line being electrically connected to the bottom fixed electrode (4).
6. The MEMS accelerometer according to claim 1, wherein there are four anchor anchors (6), each anchor (6) comprising a first anchor portion (61) disposed on the substrate (1) and a second anchor portion (62) disposed on the first anchor portion (61), the second anchor portion (62) being disposed through the proof mass (2), and wherein there are four elastic suspensions (7), each second anchor portion (62) being disposed in one-to-one correspondence with each elastic suspension (7).
7. A method for forming the MEMS accelerometer of claim 1, comprising the steps of:
depositing a polycrystalline silicon film on a substrate (1), obtaining a first structural layer (100) with a bottom fixed electrode (4) after photoetching and etching drawing, depositing a phosphorosilicate glass layer on the first structural layer (100), annealing, and etching an anchor hole (400) to obtain a first sacrificial layer (110);
depositing a polycrystalline silicon thin film and a phosphorosilicate glass layer on the first sacrificial layer (110), annealing, photoetching and etching drawing to obtain a second structural layer (200) with a part of the top fixed electrode (3) and the proof mass (2), depositing the phosphorosilicate glass layer on the second structural layer (200), annealing, etching the anchor hole (400) to obtain a second sacrificial layer (210);
and depositing a polycrystalline silicon thin film and a phosphorosilicate glass layer on the second sacrificial layer (210), annealing, and performing photoetching and etching mapping to obtain a third structural layer (300) with another part of the top fixed electrode (3).
8. The method of forming a MEMS accelerometer according to claim 7, wherein prior to obtaining the first structural layer (100), the method further comprises: depositing a silicon nitride layer on the substrate (1); after obtaining the third structural layer (300), the method further comprises: removing the first sacrificial layer (110) and the second sacrificial layer (210).
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Citations (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6196067B1 (en) * | 1998-05-05 | 2001-03-06 | California Institute Of Technology | Silicon micromachined accelerometer/seismometer and method of making the same |
| CN101089625A (en) * | 2007-07-12 | 2007-12-19 | 上海交通大学 | Metal capacitance microaccelerator |
| CN101644718A (en) * | 2009-07-02 | 2010-02-10 | 中国科学院声学研究所 | Capacitive acceleration sensor with acoustic cavity |
| CN101786593A (en) * | 2010-01-18 | 2010-07-28 | 北京大学 | Processing method of differential type high-precision accelerometer |
| CN101881785A (en) * | 2010-06-22 | 2010-11-10 | 吉林大学 | Four-folding beam variable area differential capacitance structure micro-acceleration sensor and manufacture method thereof |
| JP2012088083A (en) * | 2010-10-15 | 2012-05-10 | Rohm Co Ltd | Capacitance type acceleration sensor |
| CN104459203A (en) * | 2014-12-25 | 2015-03-25 | 歌尔声学股份有限公司 | Z-axis structure in accelerometer and triaxial accelerometer |
| CN104569491A (en) * | 2015-01-30 | 2015-04-29 | 歌尔声学股份有限公司 | Z-axis structure of accelerometer and production method of Z-axis structure |
| CN106290984A (en) * | 2015-06-23 | 2017-01-04 | 美国亚德诺半导体公司 | There is the Z-axis accelerometer of the most wasteful compensation |
| CN107991510A (en) * | 2016-10-26 | 2018-05-04 | 恩智浦美国有限公司 | Static friction detection and recovery in MEMS devices |
| CN108344881A (en) * | 2018-02-10 | 2018-07-31 | 中国工程物理研究院电子工程研究所 | A kind of sensitive structure of closed loop micro-acceleration gauge |
| US10473687B1 (en) * | 2017-05-12 | 2019-11-12 | National Technology & Engineering Solutions Of Sandia, Llc | High sensitivity single-axis MEMS accelerometer with bilateral flexures |
| CN112225170A (en) * | 2020-12-09 | 2021-01-15 | 杭州麦新敏微科技有限责任公司 | MEMS device and forming method thereof |
| CN113494908A (en) * | 2020-03-19 | 2021-10-12 | 华为技术有限公司 | MEMS inertial sensor, inertial measurement unit and inertial navigation system |
| CN113624991A (en) * | 2021-08-17 | 2021-11-09 | 美新半导体（无锡）有限公司 | Z-axis accelerometer |
| CN113702665A (en) * | 2021-10-27 | 2021-11-26 | 杭州麦新敏微科技有限责任公司 | MEMS accelerometer and forming method thereof |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7934423B2 (en) * | 2007-12-10 | 2011-05-03 | Invensense, Inc. | Vertically integrated 3-axis MEMS angular accelerometer with integrated electronics |
| US20140260617A1 (en) * | 2013-03-14 | 2014-09-18 | Agency For Science Technology And Research (A*Star) | Fully differential capacitive architecture for mems accelerometer |
-
2021
- 2021-12-23 CN CN202111588756.9A patent/CN113970655B/en active Active
Patent Citations (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6196067B1 (en) * | 1998-05-05 | 2001-03-06 | California Institute Of Technology | Silicon micromachined accelerometer/seismometer and method of making the same |
| CN101089625A (en) * | 2007-07-12 | 2007-12-19 | 上海交通大学 | Metal capacitance microaccelerator |
| CN101644718A (en) * | 2009-07-02 | 2010-02-10 | 中国科学院声学研究所 | Capacitive acceleration sensor with acoustic cavity |
| CN101786593A (en) * | 2010-01-18 | 2010-07-28 | 北京大学 | Processing method of differential type high-precision accelerometer |
| CN101881785A (en) * | 2010-06-22 | 2010-11-10 | 吉林大学 | Four-folding beam variable area differential capacitance structure micro-acceleration sensor and manufacture method thereof |
| JP2012088083A (en) * | 2010-10-15 | 2012-05-10 | Rohm Co Ltd | Capacitance type acceleration sensor |
| CN104459203A (en) * | 2014-12-25 | 2015-03-25 | 歌尔声学股份有限公司 | Z-axis structure in accelerometer and triaxial accelerometer |
| CN104569491A (en) * | 2015-01-30 | 2015-04-29 | 歌尔声学股份有限公司 | Z-axis structure of accelerometer and production method of Z-axis structure |
| CN106290984A (en) * | 2015-06-23 | 2017-01-04 | 美国亚德诺半导体公司 | There is the Z-axis accelerometer of the most wasteful compensation |
| CN107991510A (en) * | 2016-10-26 | 2018-05-04 | 恩智浦美国有限公司 | Static friction detection and recovery in MEMS devices |
| US10473687B1 (en) * | 2017-05-12 | 2019-11-12 | National Technology & Engineering Solutions Of Sandia, Llc | High sensitivity single-axis MEMS accelerometer with bilateral flexures |
| CN108344881A (en) * | 2018-02-10 | 2018-07-31 | 中国工程物理研究院电子工程研究所 | A kind of sensitive structure of closed loop micro-acceleration gauge |
| CN113494908A (en) * | 2020-03-19 | 2021-10-12 | 华为技术有限公司 | MEMS inertial sensor, inertial measurement unit and inertial navigation system |
| CN112225170A (en) * | 2020-12-09 | 2021-01-15 | 杭州麦新敏微科技有限责任公司 | MEMS device and forming method thereof |
| CN113624991A (en) * | 2021-08-17 | 2021-11-09 | 美新半导体（无锡）有限公司 | Z-axis accelerometer |
| CN113702665A (en) * | 2021-10-27 | 2021-11-26 | 杭州麦新敏微科技有限责任公司 | MEMS accelerometer and forming method thereof |
Non-Patent Citations (4)
| Title |
|---|
| 《A 3-D Parallel-Plate MEMS Accelerometer with a Gold Proof Mass》;Daisuke Yamane;《2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS)》;20190131;全文 * |
| 《Development of a novel GaAs micromachined accelerometer based on resonant tunneling diodes》;Bo Li;《Sensors and Actuators A: Physical》;20080516;全文 * |
| 《Z轴完全差分电容式加速度传感器设计分析》;许高斌;《微纳电子技术》;20121215;全文 * |
| 《面外轴向检测MEMS加速度计研究现状》;马智康;《飞控与探测》;20210925;全文 * |
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