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CN114910665B - Micromechanical detection structure with low noise and design method - Google Patents

Micromechanical detection structure with low noise and design method Download PDF

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Publication number
CN114910665B
CN114910665B CN202110177420.7A CN202110177420A CN114910665B CN 114910665 B CN114910665 B CN 114910665B CN 202110177420 A CN202110177420 A CN 202110177420A CN 114910665 B CN114910665 B CN 114910665B
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mechanical
detection structure
mass
sensitivity
micromechanical detection
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CN114910665A (en
Inventor
丁士东
张卫
郑奕挺
胡越发
宗艳波
张志勇
盛百城
王宁
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China Petroleum and Chemical Corp
Sinopec Research Institute of Petroleum Engineering
CETC 13 Research Institute
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China Petroleum and Chemical Corp
Sinopec Research Institute of Petroleum Engineering
CETC 13 Research Institute
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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
    • 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
    • B81B7/0058—Packages or encapsulation for protecting against damages due to external chemical or mechanical influences, e.g. shocks or vibrations
    • 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]
    • 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
    • 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

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Computer Hardware Design (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Pressure Sensors (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

The invention provides a design method of a micromechanical detection structure with low noise, which comprises the first step of respectively determining mechanical Brownian noise affecting the micromechanical detection structure and influence parameters of sensitivity, the second step of selecting a change parameter to be changed and a change strategy aiming at the change parameter from the influence parameters on the principle of reducing the mechanical Brownian noise and guaranteeing the sensitivity to be unchanged or increased, and the third step of carrying out processing technology improvement according to the change strategy when processing the micromechanical detection structure by considering the influence of different processing technologies. The wafer packaging method can be used for packaging the wafer under normal pressure, avoids the complexity and high cost of vacuum packaging, and improves the reliability of the device. In addition, mechanical Brownian noise of the accelerometer can be greatly reduced and the overall performance of the sensor can be improved on the premise of ensuring that important indexes such as sensitivity and the like are unchanged.

Description

Micromechanical detection structure with low noise and design method
Technical Field
The invention relates to the technical field of MEMS sensors, in particular to a micromechanical detection structure with low noise and a design method.
Background
The flat capacitive micromechanical accelerometer is one of the most widely used inertial measurement devices, and the detection device mainly consists of a micromechanical detection structure and a signal conditioning circuit. The micromechanical detection structure realizes the conversion from acceleration signals to response displacement signals, and the signal conditioning circuit converts the displacement signals into electric signals and processes and outputs the electric signals.
Compared with the traditional accelerometer, the flat-plate capacitance accelerometer has larger initial capacitance, can obtain higher detection sensitivity, has the advantages of small volume, light weight, low cost, low power consumption, high reliability, high integration level and the like due to the adoption of an MEMS micro-machining process, and is widely applied to the fields of consumer electronics, automotive electronics, general aviation, vehicle control and the like.
Signal noise is one of the key factors affecting accelerometer application, and excessive signal noise can reduce the detection accuracy and signal-to-noise ratio of the sensor, affecting the overall performance thereof. With the increase of application demands, the accelerometer is developed towards low noise and high precision, so that an effective method is required to reduce signal noise and improve detection precision.
The signal noise mainly originates from circuit noise and mechanical Brownian noise of a sensitive structure, wherein the circuit noise can be optimized through a low-noise signal conditioning circuit, the mechanical Brownian noise is the noise floor of the sensor, and the damping effect of Brownian motion originating from gas molecules on the accelerometer cannot be reduced through a method for improving the sensitivity of the sensor or processing the circuit signal, so that the signal noise of the accelerometer is reduced, and the key is to reduce the mechanical Brownian noise of the sensitive structure.
In order to reduce mechanical Brownian noise, the prior art generally adopts a vacuum packaging method to reduce the damping effect of air on the accelerometer, but for vacuum packaging of micro devices, the process is complex and the cost is high. In addition, the vacuum packaging is difficult to maintain constant vacuum degree for a long time, so that the sensor performance drifts along with the increase of the service time, the reliability of the sensor is reduced, and the research and development of a low-cost and high-reliability method for reducing the mechanical Brownian noise of the accelerometer are of great significance.
Therefore, the invention provides a micromechanical detection structure with low noise and a design method.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, provides a micromechanical detection structure with low noise and a design method, and aims to effectively reduce signal noise of an accelerometer and improve the overall performance of a sensor through a process technology.
To solve the above-mentioned problems of the prior art, the present invention provides a method for designing a micromechanical detection structure with low noise, the method comprising the steps of:
Determining influence parameters for influencing mechanical Brownian noise and sensitivity of a micromechanical detection structure respectively;
Selecting a change parameter to be changed and a change strategy aiming at the change parameter from the influence parameters by taking the principle of reducing mechanical Brownian noise and ensuring that the sensitivity is unchanged or increased;
and thirdly, considering the influence of different processing technologies, and improving the processing technology according to the change strategy when the micromechanical detection structure is processed.
According to one embodiment of the invention, the mechanical Brownian noise of a micromechanical detection structure is determined by the following formula:
Wherein a noise represents mechanical Brownian noise, K B represents Boltzmann constant, T represents absolute temperature, c represents damping coefficient, m represents sensitive structure mass, and r c represents the position of the mass center of the sensitive structure away from the rotating shaft.
According to one embodiment of the invention, the sensitivity of the micromechanical detection structure is determined by the following formula:
Wherein, S represents sensitivity, C 0 represents initial capacitance value, S 1 represents distance between electrode and rotating shaft, S 2 represents electrode width, d represents plate capacitance gap, m represents sensitive structure mass, k represents structural rigidity, and r c represents position of mass center of sensitive structure from rotating shaft.
According to one embodiment of the present invention, the first step specifically includes the following steps:
Determining a damping coefficient, the mass of the sensitive structure and the position of the mass center of the sensitive structure from the rotating shaft as influence parameters for influencing the mechanical Brownian noise according to a mechanical Brownian noise calculation expression of the micromechanical detection structure;
and determining the position of the mass center of the sensitive structure from the rotating shaft as an influence parameter for influencing the sensitivity according to the sensitivity calculation expression of the micromechanical detection structure.
According to an embodiment of the present invention, the step two specifically includes the following steps:
selecting the position of the centroid of the sensitive structure away from the rotating shaft as the change parameter;
and increasing the position of the mass center of the sensitive structure from the rotating shaft as the change strategy.
According to an embodiment of the present invention, the third step specifically includes the following steps:
For the bulk silicon processing technology, the damping holes do not need to be processed on the eccentric mass block when the micromechanical detection structure is processed, and the damping holes with the first size grade only need to be processed on the symmetrical mass block comprising the left electrode and the right electrode.
According to an embodiment of the present invention, the third step specifically includes the following steps:
For the surface machining process, when the micro-mechanical detection structure is machined, damping holes of a second size class are required to be machined in the eccentric mass block, and damping holes of a third size class are required to be machined in the symmetrical mass block comprising the left electrode and the right electrode.
According to one embodiment of the invention, the second size class of damping holes is smaller than the third size class of damping holes.
According to an embodiment of the present invention, the third step specifically includes the following steps:
under different processing conditions, the design principle of the minimum dimension of the damping hole on the eccentric mass is to ensure that the oxide layer under the sensitive structure is completely released.
Under different processing conditions, the design principle of the maximum size of the damping holes on the symmetrical mass blocks is that the integral strength of the structure is not influenced and the initial capacitance value is not influenced.
According to another aspect of the present invention, there is also provided a micromechanical detection structure with low noise, characterized in that it is designed by the method according to any of the above.
The micromechanical detection structure with low noise and the design method provided by the invention can be used for wafer packaging under normal pressure, so that the complexity and high cost of vacuum packaging are avoided, and the reliability of the device is improved. In addition, mechanical Brownian noise of the accelerometer can be greatly reduced and the overall performance of the sensor can be improved on the premise of ensuring that important indexes such as sensitivity and the like are unchanged.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate the invention and together with the embodiments of the invention, serve to explain the invention, without limitation to the invention. In the drawings:
FIG. 1 shows a flow chart of a method of designing a micromechanical detection structure with low noise according to an embodiment of the present invention;
FIG. 2 shows a flow chart of a method of determining change parameters and change policies according to one embodiment of the invention;
FIG. 3 shows a schematic diagram of a Z-axis detection structure in the prior art, and
Fig. 4 shows a schematic diagram of a Z-axis detection structure according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the following embodiments of the present invention will be described in further detail with reference to the accompanying drawings.
FIG. 1 shows a flow chart of a method of designing a micromechanical detection structure with low noise according to one embodiment of the present invention.
As in fig. 1, in step S101, influence parameters that affect mechanical brown noise and sensitivity of the micromechanical detection structure are determined, respectively.
As shown in fig. 1, in step S102, on the principle of reducing mechanical brown noise and ensuring that the sensitivity is unchanged or increased, a change parameter that needs to be changed and a change strategy for the change parameter are selected from the influence parameters.
As shown in fig. 1, in step S103, in consideration of the influence of different processing processes, processing process improvement is performed according to a change strategy when processing the micromechanical detection structure.
The object of the present application is to propose a micromechanical detection structure with low noise, therefore, it is necessary to consider the influencing factors that influence the mechanical Brownian noise.
In one embodiment, for a Z-axis flat capacitive accelerometer, a "teeterboard" configuration is typically employed, which is simple and easy to manufacture. For a "teeterboard" accelerometer, the mechanical Brownian noise of a micromechanical detection structure is determined by the following formula:
Wherein a noise represents mechanical Brownian noise, K B represents Boltzmann constant, T represents absolute temperature, c represents damping coefficient, m represents sensitive structure mass, and r c represents the position of the mass center of the sensitive structure away from the rotating shaft.
As can be seen from the formula (1), the factors determining the magnitude of the mechanical brown noise include boltzmann constant K B, absolute temperature T, damping coefficient c, mass m of the sensitive structure, and distance of mass center of the sensitive structure from the rotating shaft position r c. The boltzmann constant K B and the absolute temperature T are constant at normal temperature and normal pressure.
Thus, to reduce mechanical Brownian noise, the structural damping c can be reduced, the sensitive structure mass m can be increased, or the sensitive structure centroid distance from the pivot location r c can be increased. However, increasing the mass m of the sensitive structure increases the structural area, resulting in an increase in the structural damping c, so that the most effective way to reduce the mechanical Brownian noise is to increase the center of mass of the sensitive structure from the rotational axis position r c.
Sensitivity is one of the most important indicators for evaluating accelerometer performance, and in one embodiment, for a "see-saw" Z-axis accelerometer, the sensitivity of the micromechanical detection structure is determined by the following formula:
Wherein, S represents sensitivity, C 0 represents initial capacitance value, S 1 represents distance between electrode and rotating shaft, S 2 represents electrode width, d represents plate capacitance gap, m represents sensitive structure mass, k represents structural rigidity, and r c represents position of mass center of sensitive structure from rotating shaft.
In formula (2), the initial capacitance value C 0, the electrode-to-spindle distance s 1, the electrode width s 2, and the structural rigidity k are determined by design, the plate capacitance gap d is determined by the machining process, and the sensitivity can be improved by increasing the sensitive structure mass m and the sensitive structure centroid distance r c under the condition that other parameters are kept unchanged.
By comparing the formulas (1) and (2), the mechanical Brownian noise can be effectively reduced on the premise of ensuring the unchanged sensitivity by increasing the distance between the mass center of the sensitive structure and the rotating shaft position r c.
In step S103, the method further comprises that for the bulk silicon processing technology, the damping holes do not need to be processed on the eccentric mass block when the micromechanical detection structure is processed, and only the damping holes with the first size grade need to be processed on the symmetrical mass block comprising the left electrode and the right electrode.
In step S103, the method further comprises the step of processing damping holes of a second size level on the eccentric mass block and processing damping holes of a third size level on the symmetrical mass block comprising the left electrode and the right electrode when the micro-mechanical detection structure is processed for the surface processing technology.
Specifically, the second size class of damping holes is smaller than the third size class of damping holes.
In step S103, the method further comprises the step of designing the damping hole on the eccentric mass according to the minimum dimension design principle under different processing conditions so as to ensure that the oxide layer under the sensitive structure is completely released.
In step S103, the design principle of the maximum size of the damping holes on the symmetrical mass blocks under different processing conditions is that the integral strength of the structure is not affected and the initial capacitance value is not affected. Although the larger orifice will have some effect on the initial capacitance C 0, the capacitance edge effect around the orifice will compensate the capacitance, and in addition, the initial capacitance C 0 may be compensated in advance during design.
By processing damping holes of different sizes, the mass m of the sensitive structure is slightly reduced, but the distance between the mass center of the sensitive structure and the rotating shaft position r c is greatly increased, and the product of the mass m of the sensitive structure and the distance between the mass center of the sensitive structure and the rotating shaft position rc is also obviously increased.
In addition, due to the manufacture of the damping hole, the damping effect of gas molecules on the accelerometer can be obviously reduced, and the damping coefficient c can be greatly reduced. As can be seen from formulas (1) and (2), by adjusting the above parameters, the mechanical brown noise a noise of the accelerometer can be significantly reduced, and the sensitivity S can be further improved and optimized.
In summary, the structural parameters are adjusted by processing the damping holes with different sizes on the sensitive structure of the accelerometer, so that the mechanical Brownian noise of the accelerometer can be obviously reduced and the overall performance of the sensor can be improved on the premise of ensuring that main performance parameters such as sensitivity and the like are unchanged.
In addition, the micromechanical detection structure designed according to the design method can be used for wafer encapsulation under normal pressure, so that the complexity and high cost of vacuum encapsulation are avoided, the reliability of the device is improved, and the micromechanical detection structure has the advantages of simple principle, convenience in processing, low cost, high reliability and the like.
FIG. 2 shows a flow chart of a method of determining change parameters and change policies according to one embodiment of the invention.
As shown in fig. 2, in step S201, the damping coefficient, the mass of the sensitive structure, and the position of the centroid of the sensitive structure from the rotation axis are determined as the influence parameters affecting the mechanical brown noise according to the mechanical brown noise calculation expression of the micromechanical detection structure.
Specifically, as can be seen from equation (1), the damping coefficient c, the mass m of the sensitive structure, and the distance between the center of mass of the sensitive structure and the axis of rotation r c can affect the magnitude of mechanical Brownian noise. Reducing the structural damping c, increasing the sensitive structure mass m, or increasing the sensitive structure centroid distance from the pivot location r c can reduce mechanical Brownian noise.
As shown in fig. 2, in step S202, the centroid position of the sensitive structure from the rotation axis is determined as an influence parameter affecting the sensitivity according to the sensitivity calculation expression of the micromechanical detection structure.
Specifically, as can be seen from equation (2), the mass m of the sensitive structure and the distance r c between the centroid of the sensitive structure and the axis of rotation can affect the sensitivity. Increasing the mass m of the sensitive structure and the distance between the mass center of the sensitive structure and the rotating shaft r c can improve the sensitivity.
As shown in fig. 2, in step S203, the position of the centroid of the sensitive structure from the rotation axis is selected as a change parameter.
As shown in fig. 2, in step S204, the sensitive structure centroid distance from the pivot location is increased as a change strategy.
Specifically, as can be seen from the combination of the formula (1) and the formula (2), the principle of reducing mechanical Brownian noise and guaranteeing the sensitivity to be unchanged or increased is that the position of the centroid of the sensitive structure away from the rotating shaft is selected as a change parameter, and the position of the centroid of the sensitive structure away from the rotating shaft is increased as a change strategy.
Fig. 3 shows a schematic diagram of a Z-axis detection structure in the prior art.
As shown in fig. 3, the Z-axis detecting structure in the prior art includes an eccentric mass portion and a symmetrical mass portion, and the center of mass of the entire Z-axis detecting structure is located in the symmetrical mass region, and the electrodes 1 and 2 are respectively arranged on the left and right sides of the symmetrical mass.
The mechanical Brownian noise of the Z-axis detection structure in the prior art is large, the detection precision and the signal-to-noise ratio of the sensor can be reduced, and the overall performance of the sensor is affected.
Fig. 4 shows a schematic diagram of a Z-axis detection structure according to an embodiment of the present invention.
As shown in fig. 4, the Z-axis detection structure (a micromechanical detection structure with low noise) provided by the present application includes an eccentric mass block portion and a symmetrical mass block portion, wherein the center of mass of the entire Z-axis detection structure is located in the eccentric mass block region, and the electrodes 1 and 2 are respectively arranged on the left and right sides of the symmetrical mass block. Damping holes are formed in the eccentric mass block and the symmetrical mass block, and the damping holes in the eccentric mass block are smaller than those in the symmetrical mass block.
As shown in FIG. 4, the Z-axis detection structure provided by the invention has the advantages that damping holes with different sizes are processed at different positions of the sensitive structure, so that the distance between the mass center of the sensitive structure and the rotating shaft is increased, the damping effect of gas molecules on the sensitive structure is obviously reduced under the comprehensive influence of the damping holes, and the mechanical Brownian noise of the accelerometer can be obviously reduced under the premise of ensuring that main performance parameters such as sensitivity and the like are unchanged by adjusting the parameters.
The invention also provides a micromechanical detection structure with low noise, designed by the method according to any of the above (see fig. 4).
In summary, the micromechanical detection structure with low noise and the design method provided by the invention can be used for wafer packaging under normal pressure, so that the complexity and high cost of vacuum packaging are avoided, and the reliability of the device is improved. In addition, mechanical Brownian noise of the accelerometer can be greatly reduced and the overall performance of the sensor can be improved on the premise of ensuring that important indexes such as sensitivity and the like are unchanged.
It is to be understood that the disclosed embodiments are not limited to the specific structures, process steps, or materials disclosed herein, but are intended to extend to equivalents of these features as would be understood by one of ordinary skill in the relevant arts. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.
Reference in the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrase "one embodiment" or "an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.
Although the embodiments of the present invention are disclosed above, the embodiments are only used for the convenience of understanding the present invention, and are not intended to limit the present invention. Any person skilled in the art can make any modification and variation in form and detail without departing from the spirit and scope of the present disclosure, but the scope of the present disclosure is still subject to the scope of the appended claims.

Claims (9)

1. A method of designing a micromechanical detection structure with low noise, the method comprising the steps of:
determining influence parameters for influencing mechanical Brownian noise and sensitivity of a micromechanical detection structure respectively, wherein the micromechanical detection structure adopts a seesaw structure;
Selecting a change parameter to be changed and a change strategy aiming at the change parameter from the influence parameters by taking the principle of reducing mechanical Brownian noise and ensuring that the sensitivity is unchanged or increased;
Step three, considering the influence of different processing technologies, and improving the processing technology according to the change strategy when the micromechanical detection structure is processed;
The first step specifically comprises the following steps:
Determining a damping coefficient, the mass of the sensitive structure and the position of the mass center of the sensitive structure from the rotating shaft as influence parameters for influencing the mechanical Brownian noise according to a mechanical Brownian noise calculation expression of the micromechanical detection structure;
and determining the position of the mass center of the sensitive structure from the rotating shaft as an influence parameter for influencing the sensitivity according to the sensitivity calculation expression of the micromechanical detection structure.
2. The method of designing a micromechanical detection structure with low noise according to claim 1, characterized in that the mechanical brown noise of the micromechanical detection structure is determined by the following formula:
Wherein a noise represents mechanical Brownian noise, K B represents Boltzmann constant, T represents absolute temperature, c represents damping coefficient, m represents sensitive structure mass, and r c represents the position of the mass center of the sensitive structure away from the rotating shaft.
3. The method of designing a micromechanical detection structure with low noise according to claim 1, characterized in that the sensitivity of the micromechanical detection structure is determined by the following formula:
Wherein, S represents sensitivity, C 0 represents initial capacitance value, S 1 represents distance between electrode and rotating shaft, S 2 represents electrode width, d represents plate capacitance gap, m represents sensitive structure mass, k represents structural rigidity, and r c represents position of mass center of sensitive structure from rotating shaft.
4. The method for designing a micro-mechanical inspection structure with low noise according to claim 1, wherein the second step comprises the following steps:
selecting the position of the centroid of the sensitive structure away from the rotating shaft as the change parameter;
and increasing the position of the mass center of the sensitive structure from the rotating shaft as the change strategy.
5. The method for designing a micro-mechanical inspection structure with low noise according to claim 1, wherein the third step comprises the following steps:
For the bulk silicon processing technology, the damping holes do not need to be processed on the eccentric mass block when the micromechanical detection structure is processed, and the damping holes with the first size grade only need to be processed on the symmetrical mass block comprising the left electrode and the right electrode.
6. The method for designing a micro-mechanical inspection structure with low noise according to claim 1, wherein the third step comprises the following steps:
For the surface machining process, when the micro-mechanical detection structure is machined, damping holes of a second size class are required to be machined in the eccentric mass block, and damping holes of a third size class are required to be machined in the symmetrical mass block comprising the left electrode and the right electrode.
7. The method of claim 6, wherein the second size class of damping holes is smaller than the third size class of damping holes.
8. The method for designing a micro-mechanical inspection structure with low noise according to claim 1, wherein the third step comprises the following steps:
Under different processing conditions, the design principle of the minimum size of the damping hole on the eccentric mass is that the oxide layer under the sensitive structure can be completely released;
Under different processing conditions, the design principle of the maximum size of the damping holes on the symmetrical mass blocks is that the integral strength of the structure is not influenced and the initial capacitance value is not influenced.
9. Micromechanical detection structure with low noise, characterized in that it is designed by a method according to any of claims 1-8.
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