Resonance type flow field sensor with inertia force compensation structure and preparation method thereof

Abstract

The invention provides a resonance type flow field sensor with an inertia force compensation structure. The resonance type flow field sensor comprises a substrate; the double-end fixed tuning fork is fixed in the middle of the base; the cilium supporting structure is suspended on the base and is positioned at one end of the double-end fixed tuning fork; the comb tooth capacitors are arranged on the substrate and located on the two sides of the double-end fixed tuning fork; the cilia is arranged on the cilia supporting structure; one end of the micro lever is connected with the cilium supporting structure, and the other end is connected with one end of the double-end fixed tuning fork; and the inertia force compensation structure is suspended on the base, is symmetrically arranged relative to the double-end fixed tuning fork, is connected with one end of the double-end fixed tuning fork, and is positioned between the micro lever and the double-end fixed tuning fork. According to the sensor, the change of an air flow field is captured through the cilia on the sensor, the resonant frequency is detected through the capacitor, the flow velocity of the flow field can be obtained, the inertia force compensation structure can compensate interference of inertia force on an output result, and the sensor can still output stable flow velocity of the flow field when being interfered by the inertia force.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor sensors, and in particular, to a flow field sensor with an inertial force compensation structure and a preparation method thereof. Background Art

[0002] As an irreplaceable component for obtaining airflow information in many engineering scenarios, airflow sensors have received increasing attention in aerospace engineering, environmental engineering, sustainable energy development, meteorological research, gas monitoring systems and other fields. Especially for aircraft design, accurately measuring the flow velocity and direction of movement of the flow field in which the aircraft is located is the key to enhancing its operational safety, speed, comfort and fuel efficiency. Most existing MEMS flow field sensors do not consider the influence of inertial force on the sensor's measured results, and it is difficult to obtain accurate and stable output in actual environments. There are some examples of eliminating inertial force interference in traditional mechanical sensor systems. In 2021, Li Yingjun et al. from Jinan University proposed a shock wave piezoelectric pressure sensor with a self-compensating acceleration mechanism in "Mechanical Systems and Signal Processing" (1 Volume 150, March 2021, 107303). However, traditional mechanical sensors are usually large in size and have poor sensor consistency. There is no related airflow sensor with an inertial force compensation structure in the MEMS field. Summary of the invention

[0003] In response to the defects in the prior art, the purpose of this application is to provide a resonant sensor with an inertial force compensation structure. The cilia on the sensor capture the changes in the air flow field, and the resonant frequency is detected by capacitance to obtain the flow field velocity. At the same time, the inertial force compensation structure can compensate for the interference of the inertial force on the output result, so that the sensor can still output a stable flow field velocity when interfered by the inertial force.

[0004] In one aspect of the present application, a resonant flow field sensor having an inertial force compensation structure is provided, comprising: a substrate;

[0005] A double-ended fixed tuning fork fixed in the middle of the base;

[0006] A ciliary support structure is suspended on the base and located at one end of the double-ended fixed tuning fork;

[0007] A comb capacitor, arranged on the substrate and located on both sides of the double-ended fixed tuning fork;

[0008] Cilia, disposed on the ciliary support structure;

[0009] A micro lever, one end of which is connected to the ciliary support structure, and the other end of which is connected to one end of the double-ended fixed tuning fork;

[0010] The inertial force compensation structure is suspended on the base and symmetrically arranged relative to the double-ended fixed tuning fork. The inertial force compensation structure is connected to one end of the double-ended fixed tuning fork and is located between the micro-lever and one end of the double-ended fixed tuning fork.

[0011] Furthermore, it also includes an anchor block, which is arranged on the substrate;

[0012] A connecting beam, one end of which is connected to the anchor block, and the other end of which is connected to the ciliary support structure;

[0013] The connecting beam is suspended on the base through the anchor block;

[0014] The ciliary support structure is suspended on the base through the connecting beam.

[0015] Furthermore, the comb-tooth capacitors have multiple groups, which are symmetrically arranged on both sides of the double-ended fixed tuning fork and fixed on the base;

[0016] The comb teeth capacitor comprises detection comb teeth and driving comb teeth;

[0017] The detection comb teeth are close to one side of the double-ended fixed tuning fork, symmetrically arranged up and down, and located on the inner side of the comb teeth capacitor;

[0018] The driving comb teeth are arranged away from one side of the double-ended fixed tuning fork and are located outside the comb teeth capacitor.

[0019] Furthermore, the number of comb teeth of the detection comb teeth on both sides of the double-ended fixed tuning fork is different on the left and right sides, so as to form an initial capacitance difference between the comb teeth capacitances on both sides of the double-ended fixed tuning fork, and detect the vibration frequency of the double-ended fixed tuning fork in the X-axis direction to reflect the magnitude and direction of the flow field velocity in the Y-direction;

[0020] The number of the driving comb teeth on both sides of the double-ended fixed tuning fork is the same on the left and right sides, and is used to drive the resonator.

[0021] Furthermore, it also includes an electrode layer, which is arranged on the anchor block and located at the upper peripheral edge of the substrate; the electrode layer includes: a plurality of readout electrodes, which are respectively connected to the two ends of the detection comb teeth on both sides of the substrate, and are used to detect the readout of capacitance;

[0022] There are multiple electric field applying electrodes, which are respectively connected to one end of the driving comb teeth on both sides of the substrate and are used to apply an electric field;

[0023] There are multiple bias voltage electrodes, which are located above the anchor block and are used to provide a bias voltage.

[0024] Furthermore, the electrode layer is made by a Cr / Au metal sputtering process;

[0025] The Cr / Au metal sputtering process is to first sputter Cr metal and then sputter Au metal, so as to make Au metal better connected with silicon and prevent Au metal from falling off.

[0026] Furthermore, the ciliary support structure is provided with a plurality of concave holes, which are arranged at intervals on the circumferential wall of the upper surface of the ciliary support structure to reduce the mass of the ciliary support structure.

[0027] Further, the cilia are located at the center of the ciliary support structure;

[0028] The recessed holes are arranged on the upper surface of the ciliary support structure to surround the ciliary hairs.

[0029] Furthermore, the comb-tooth capacitor, the cilia support structure, the double-ended fixed tuning fork, and the connecting beam are made of conductive silicon;

[0030] The substrate is made of glass, and the anchor block is made of silicon;

[0031] The substrate and the anchor block are sutured by anode;

[0032] The cilia are made of SU-8 material.

[0033] A second aspect of the present application provides a method for preparing a resonant flow field sensor having an inertial force compensation structure, comprising:

[0034] The anchor block layer is formed by dry etching on the substrate or etching on the silicon wafer substrate, and then anodic bonding is performed to integrate the substrate and the anchor block layer, which specifically includes:

[0035] Step 1) spin coating photoresist and photolithography anchor block pattern;

[0036] Step 2) using the photoresist after photolithography as a mask, DRIE or wet etching to form anchor blocks, and then removing the photoresist;

[0037] Step 3) Anodic bonding the glass to the back side of the etched silicon wafer, or anodic bonding the back side of the silicon wafer to the front side of the etched glass;

[0038] Step 4) grinding the front side of the silicon wafer to a specific thickness;

[0039] Step 5) sputtering Cr and Au;

[0040] Step 6) Spin-coating photoresist and photolithography electrode pattern;

[0041] Step 7) using the photoresist after photolithography as a mask, etching Cr and Au, and removing the resist;

[0042] Step 8) Spin-coating photoresist and photolithography device main body pattern;

[0043] Step 9) using the photoresist after photolithography as a mask, DRIE etches out the device body and removes the resist;

[0044] Step 10) attaching SU-8 dry film;

[0045] Step 11) Photolithography of cilia pattern and degumming;

[0046] Step 12) laser slicing to finally obtain the sensor structure.

[0047] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0048] The present invention realizes an inertial force compensation structure through a simple process. Compared with a traditional flow velocity sensor without inertial force compensation, it can have a more stable output under the superposition input of the same inertial force and wind speed, which is more conducive to the stable operation of the sensor and the detection of weak flow velocity; at the same time, there is no need to introduce additional sensors to compensate for the inertial force, which also simplifies the extraction and processing process of effective signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0050] Figure 1 It is a schematic diagram of the three-dimensional structure of a resonant flow field sensor with an inertial force compensation structure in one embodiment of the present application.

[0051] Figure 2 It is a side view of a resonant flow field sensor in one embodiment of the present application.

[0052] Figure 3 Schematic diagram of the electrode layer and top view in one embodiment of the present application.

[0053] Figure 4 It is a partial enlarged view of a resonant flow field sensor in one embodiment of the present application.

[0054] Figure 5 This is a comparison chart of simulation results of the anti-inertial force interference capability of the front and rear sensors using the inertial force compensation structure in one embodiment of the present application.

[0055] Figure 6 Schematic diagram of a sensor closed-loop control system in one embodiment of the present application.

[0056] Figure 7 This is an exploded view of a resonant flow field sensor with an inertial force compensation structure in one embodiment of the present application.

[0057] In the figure: 1. Double-ended fixed tuning fork; 2. Base; 3. Cilia supporting structure; 4. Electrode layer; 4a. Readout electrode; 4b. Electric field applying electrode; 4c. Bias voltage electrode; 5. Comb tooth capacitor; 5a. Detection comb teeth; 5b. Drive comb teeth; 6. Inertial force compensation structure; 7. Cilia; 8. Micro lever; 9. Connecting beam; 10. Anchor block;. DETAILED DESCRIPTION

[0058] The present application is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements can also be made without departing from the concept of the present application. These all belong to the protection scope of the present application.

[0059] It should be understood that the terms "first", "second" and the like of the following embodiments are used to distinguish different objects, rather than to describe a specific order. The terms "include" and "comprise" used indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections. In the description of this specification, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal" and the like is based on the orientation or positional relationship shown in the accompanying drawings, only for the convenience of description and simplified description, rather than indicating or suggesting that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0060] Reference Figure 1 As shown, a resonant flow field sensor with an inertial force compensation structure according to an embodiment of the present application includes: a substrate 2; a double-ended fixed tuning fork 1, fixed in the middle of the substrate 2; a cilia support structure 3, suspended on the substrate 2, located at one end of the double-ended fixed tuning fork 1; a comb capacitor 5, arranged on the substrate 2, located on both sides of the double-ended fixed tuning fork 1; cilia 7, arranged on the cilia support structure 3; a micro-lever 8, one end of which is connected to the cilia support structure 3, and the other end of which is connected to one end of the double-ended fixed tuning fork 1; an inertial force compensation structure 6, suspended on the substrate 2, symmetrically arranged relative to the double-ended fixed tuning fork 1, the inertial force compensation structure 6 is connected to one end of the double-ended fixed tuning fork 1, and is located between the micro-lever 8 and one end of the double-ended fixed tuning fork 1.

[0061] The present application adds an inertial force compensation structure 6 to balance the influence of the inertial force on the double-ended fixed tuning fork 1 when it vibrates in the fluid. Under the same superimposed input of inertial force and wind speed, the output can be more stable, thereby improving the measurement accuracy and stability of the sensor. The flow field force exerted on the cilia 7 acts on one end of the double-ended fixed tuning fork 1 through the micro-lever 8, and the inertial force compensation structure 6 also acts on the same end of the double-ended fixed tuning fork 1. The two together affect the resonant frequency of the sensor, reduce the inertial force interference on the sensitive axis direction of the sensor, and enable the sensor to respond to flow field changes more accurately.

[0062] A double-ended fixed tuning fork 1 is fixed in the middle of the base 2, and a cilia support structure 3 is suspended on the base 2, and cilia 7 are installed on the cilia support structure 3. Comb capacitors 5 are set on both sides of the double-ended fixed tuning fork 1 to detect the vibration state of the double-ended fixed tuning fork 1; one end of the micro-lever 8 is connected to the cilia support structure 3, and the other end is connected to one end of the double-ended fixed tuning fork 1 to amplify the flow field signal felt by the cilia 7; in addition, an inertial force compensation structure 6 is suspended on the base 2, which is symmetrically arranged relative to the double-ended fixed tuning fork 1 and connected to one end of the double-ended fixed tuning fork 1, located between the micro-lever 8 and the connection point of the double-ended fixed tuning fork 1. Through precise design, the inertial force compensation structure 6 can offset the inertial force generated by the double-ended fixed tuning fork 1 during the vibration process, thereby optimizing the performance of the sensor.

[0063] Among them, one end of the double-ended fixed tuning fork 1 is suspended in the air and connected to one end of the inertial force compensation structure 6 , and the other end is fixed on the base 2 .

[0064] When the whole structure is subjected to inertial force, the inertial force compensation structure 6 exerts force on one end of the double-ended fixed tuning fork 1 under the influence of inertia, and the force is offset by the force exerted on one end of the double-ended fixed tuning fork 1 by the cilia 7 and its supporting structure through the micro lever 8, thereby achieving the effect of inertial force compensation. By reasonably configuring the mass and shape of the compensation structure, the detection sensitivity can be guaranteed while effectively reducing the interference of the device with inertial force.

[0065] like Figure 2 As shown, in some specific embodiments, it also includes an anchor block 10, which is arranged on the substrate 2; an electrode layer 4, which is arranged on the anchor block 10 and is located at the upper peripheral edge of the substrate 2; a connecting beam 9, one end of which is connected to the anchor block 10, and the other end is connected to the cilia support structure 3; the connecting beam 9 is suspended on the substrate 2 through the anchor block 10; the cilia support structure 3 is suspended on the substrate 2 through the connecting beam 9.

[0066] The present application sets an anchor block 10 on the base 2, and sets a connecting beam 9, one end of which is connected to the anchor block 10, and the other end is connected to the ciliary support structure 3, and the connecting beam 9 is suspended and fixed above the base 2 through the anchor block 10, thereby enhancing the stability and firmness of the structure, and the ciliary support structure is suspended on the base 2 through the connecting beam 9, which effectively isolates the direct contact between the ciliary support structure 3 and the base 2, thereby improving the service life.

[0067] In some specific embodiments, the comb tooth capacitor 5 has multiple groups, which are symmetrically arranged on both sides of the double-ended fixed tuning fork 1 and fixed on the base 2; the comb tooth capacitor 5 includes detection comb teeth 5a and driving comb teeth 5b; the detection comb teeth 5a are close to one side of the double-ended fixed tuning fork 1, symmetrically arranged up and down, and located on the inner side of the comb tooth capacitor 5; the driving comb teeth 5b are arranged on the side away from the double-ended fixed tuning fork 1, and are located on the outer side of the comb tooth capacitor 5.

[0068] By arranging the comb-tooth capacitor 5 on both sides of the double-ended fixed tuning fork 1, through the detection comb teeth 5a constituting the detection comb-tooth capacitor 5 and the driving comb teeth 5b constituting the driving capacitor, the differential capacitance of the comb-tooth capacitor 5 on the left and right sides of the double-ended fixed tuning fork 1 is used to detect the vibration frequency of the double-ended fixed tuning fork 1 in the X-axis direction to reflect the magnitude and direction of the flow field velocity in the Y direction, thereby improving the detection sensitivity, enhancing the anti-interference ability of the system, and enabling the magnitude and direction of the flow field velocity in the Y direction to be accurately reflected.

[0069] Specifically, the number of teeth of the detection comb teeth 5a on both sides of the double-ended fixed tuning fork 1 is different on the left and right, which is used to form an initial capacitance difference between the comb tooth capacitors 5 on both sides of the double-ended fixed tuning fork 1, and detect the vibration frequency of the double-ended fixed tuning fork 1 in the X-axis direction to reflect the size and direction of the flow field velocity in the Y direction; the number of teeth of the driving comb teeth 5b on both sides of the double-ended fixed tuning fork 1 is the same on the left and right, which is used to drive the resonator.

[0070] like Figure 4 As shown, the detection comb teeth 5a constituting the detection comb teeth capacitor 5 are located on the inner side and are symmetrically distributed up and down; the driving comb teeth 5b constituting the driving capacitor are located on the outer side; the left and right sides of the double-ended fixed tuning fork 1 are provided with detection comb teeth and driving comb teeth, wherein the number of driving comb teeth is the same on the left and right sides, and are used to drive the resonator; the number of detection comb teeth is different to form an initial capacitance difference, which is convenient for detection by the C / V conversion circuit, and is used to detect the magnitude and direction of the flow field velocity in the Y-axis direction.

[0071] During operation, an AC voltage that matches the resonant frequency of the device and a DC bias voltage that is much larger than the amplitude of the AC voltage are applied to the driving comb teeth 5b to generate an electrostatic driving force. The device vibrates under the drive of the electrostatic force and operates in a resonant state. The flow field in the Y direction acts on the cilia 7 to generate a force on them, and the force of the flow field is amplified by the micro lever 8 and finally acts on one end of the double-ended fixed tuning fork 1, causing the resonant frequency of the double-ended fixed tuning fork 1 to change. Figure 6 With the participation of the external phase-locked loop circuit described, the frequency of the AC drive signal also changes, so that the device works at a new resonant frequency. (That is, the device always works at the resonant frequency with the participation of the external phase-locked loop, and the input of the flow field will change this resonant frequency) By measuring the change in differential capacitance, the vibration frequency of the double-ended fixed tuning fork 1 can be accurately calculated, and then according to the preset corresponding relationship, the size and direction of the flow field velocity in the Y direction can be calculated, realizing real-time and accurate monitoring of the flow field velocity.

[0072] Among them, the comb-tooth capacitor 5, the cilia support structure 3, the double-ended fixed tuning fork 1, and the connecting beam 9 are made of conductive silicon.

[0073] The substrate 2 is made of glass, and the anchor block 10 is made of silicon. The substrate 2 and the anchor block 10 are anodic bonded, and the glass material can reduce the parasitic capacitance of the device and avoid the influence on the measurement.

[0074] The cilia 7 are made of SU-8 material and are located on the cilia support structure 3, wherein the cilia support structure 3 is provided with concave holes to reduce the mass of the support structure and reduce the influence of gravity on the sensor.

[0075] In the present application, the working mode includes capacitive sensing, specifically: when the cilia 7 is acted upon by an external force, it will produce a certain displacement, which acts on one end of the double-ended fixed tuning fork 1 through the micro-lever 8, causing its resonant frequency to change, and detecting the gap change frequency of the comb tooth capacitor 5 pair, thereby obtaining the change in the resonant frequency by measuring the comb tooth capacitor 5, and knowing the size and direction of the external force, that is, capacitive sensing.

[0076] like Figure 3 As shown, in some specific embodiments, it also includes an electrode layer 4, which is arranged on the anchor block 10 and is located at the upper peripheral edge of the substrate 2; the electrode layer 4 includes: a readout electrode 4a, which has a plurality of electrodes, which are respectively connected to the two ends of the detection comb teeth 5a on both sides of the substrate 2, for detecting the readout of the capacitance; an electric field applying electrode 4b, which has a plurality of electrodes, which are respectively connected to one end of the driving comb teeth 5b on both sides of the substrate 2, for applying an electric field; and a bias voltage electrode 4c, which has a plurality of electrodes, which are located above the anchor block 10 and are used to provide a bias voltage.

[0077] By arranging the electrode layer 4 at intervals above the four sides of the substrate 2 and rationally planning the spatial position of the substrate 2, the heat dissipation effect of the sensor is improved. At the same time, the electrode layer 4 is set as the readout electrode 4a of the detection capacitor, the electric field application electrode 4b of the driving capacitor and the main bias voltage electrode 4c, so as to achieve high integration and precise control of the sensor function, further improve the measurement accuracy and response speed, and provide a more reliable and efficient solution for flow field monitoring.

[0078] The electrode layer 4 is relatively thin and is disposed on the anchor block 10 , and the connecting beam 9 includes two connecting beams symmetrically disposed on the electrode layer 4 .

[0079] In some specific embodiments, the electrode layer 4 is made by a Cr / Au metal sputtering process; the Cr / Au metal sputtering process is to first sputter Cr metal and then sputter Au metal, so as to enable Au metal to better connect with silicon and prevent Au metal from falling off.

[0080] In some specific embodiments, the ciliary support structure 3 is provided with a plurality of concave holes, which are spaced apart on the circumferential wall of the upper surface of the ciliary support structure 3 to reduce the mass of the ciliary support structure 3 .

[0081] By providing a concave hole on the ciliary support structure 3 to reduce the mass of the support structure, the influence of this part of the inertial force on the sensor is reduced.

[0082] Specifically, the cilia 7 are located at the center of the cilia supporting structure 3 ; and the recessed holes are arranged around the cilia 7 on the upper surface of the cilia supporting structure 3 .

[0083] In the present application, the resonant frequency of the double-ended fixed tuning fork 1 is obtained in the following manner: the double-ended fixed tuning fork 1 is limited to the in-phase mode, and combined with the arrangement of the detection comb teeth on both sides of the double-ended fixed tuning fork 1, a pair of differential detection capacitors are formed, which are converted into voltage through a CV conversion circuit, and then AD is input into FPGA for frequency detection to realize the detection of flow field flow velocity.

[0084] The driving method of the double-ended fixed tuning fork 1 resonator is: combining the resonant frequency calculated by the digital phase-locked loop with the amplitude information given by the amplitude stabilization module, driving the DA through the FPGA, applying the alternating voltage to the driving comb teeth, and completing the closed-loop control of the resonator.

[0085] like Figure 6 As shown, specifically, the sensor needs the clock to work in a resonant state, and needs to obtain the sensor's resonant frequency in real time to infer the speed and direction of the input flow field. The sensor detection capacitor can obtain an AC voltage signal with the same resonant frequency after passing through the C / V conversion circuit. The amplitude of the signal reflects the sensor vibration amplitude. The closed-loop control system needs to lock the sensor's resonant frequency and maintain the sensor's vibration amplitude.

[0086] The details are as follows: On the one hand, the voltage signal after C / V conversion is converted into a voltage signal with the same resonant frequency of the sensor after passing through an amplifier and a comparator, and then input into the FPGA. The FPGA locks the frequency through an internal phase-locked loop, realizes the tracking of the resonant frequency, and outputs the drive signal frequency. On the other hand, the voltage generated by the C / V conversion circuit is converted into an analog signal through AD conversion and input into the FPGA. The amplitude stabilization module in the FPGA calculates the vibration amplitude of the device and gives the corresponding drive voltage amplitude. The frequency and amplitude of the drive signal are combined to generate the final AC drive signal. Finally, the signal is converted into an analog AC voltage through DA, and the AC voltage is loaded on the drive comb 5b to maintain the device stable at the resonant frequency and realize closed-loop control.

[0087] like Figure 7 As shown, the exploded diagram of the sensor of the present application forms a base layer through a base 2, forms an anchor point layer through an anchor block 10 arranged on the base 2, forms a floating structure layer by suspending a connecting beam 9 on the anchor block 10, and suspending a cilia support structure 3 on the base 2 through the connecting beam 9, forms an electrode layer 4 by arranging electrodes, and forms a cilia layer by cilia 7, so as to realize the planning and arrangement of each layer of the sensor and facilitate preparation.

[0088] Among them, the anchor block 10 on the substrate 2 forms an anchor layer, and there is no corresponding anchor layer under some floating structure layers, forming a suspended structure (ciliary support structure 3 and connecting beam 9, etc.), and the electrode layer 4 above the anchor layer is a metal material, and the ciliary layer, electrode layer, floating structure layer, anchor layer and substrate layer are connected to each other to form a complete sensor structure.

[0089] The second aspect of the present application provides a method for preparing a resonant flow field sensor having an inertial force compensation structure, comprising: forming an anchor block layer by dry etching on a substrate 2, or etching on a silicon wafer substrate 2, and then performing anodic bonding to integrate the substrate 2 and the anchor block layer, specifically comprising:

[0090] Step 1) spin coating photoresist and photolithography anchor block pattern;

[0091] Step 2) using the photoresist after photolithography as a mask, DRIE or wet etching to form the anchor block 10, and then removing the photoresist;

[0092] Step 3) Anodic bonding the glass to the back side of the etched silicon wafer, or anodic bonding the back side of the silicon wafer to the front side of the etched glass;

[0093] Step 4) grinding the front side of the silicon wafer to a specific thickness;

[0094] Step 5) sputtering Cr and Au;

[0095] Step 6) Spin-coating photoresist and photolithography electrode pattern;

[0096] Step 7) using the photoresist after photolithography as a mask, etching Cr and Au, and removing the resist;

[0097] Step 8) Spin-coating photoresist and photolithography device main body pattern;

[0098] Step 9) using the photoresist after photolithography as a mask, DRIE etches out the device body and removes the resist;

[0099] Step 10) attaching SU-8 dry film;

[0100] Step 11) Photolithography of cilia pattern and degumming;

[0101] Step 12) laser slicing to finally obtain the sensor structure.

[0102] The sensor structure is obtained by the above preparation method. After specific simulation, when the wind speed of the sensitive axis is -10m0m10m and the acceleration disturbance in the sensitive axis direction is ±g, Figure 5 As shown, the experimental data that can be obtained is that the change in the resonant frequency of the sensor having the inertial force compensation structure 6 caused by the inertial force input is one order of magnitude smaller than the change in the resonant frequency of the original structure.

[0103] The sensor of the present invention can eliminate inertial force interference at the detection end without the need for additional inertial force detection devices and data processing processes; it can output more stable and accurate wind speed when there are inclination angles and inertial force interference, which is conducive to the realization of a practical micro-flow velocity sensor.

[0104] The above describes the specific embodiments of the present application. It should be understood that the present application is not limited to the above specific embodiments, and those skilled in the art can make various modifications or variations within the scope of the claims, which does not affect the substantive content of the present application. The above preferred features can be used in any combination without conflicting with each other.

Claims

1. A resonant flow field sensor with an inertial force compensation structure, characterized in that: include: substrate; A double-ended fixed tuning fork fixed in the middle of the base; A ciliary support structure is suspended on the base and located at one end of the double-ended fixed tuning fork; A comb capacitor, arranged on the substrate and located on both sides of the double-ended fixed tuning fork; Cilia, disposed on the ciliary support structure; A micro lever, one end of which is connected to the ciliary support structure, and the other end of which is connected to one end of the double-ended fixed tuning fork; The inertial force compensation structure is suspended on the base and symmetrically arranged relative to the double-ended fixed tuning fork. The inertial force compensation structure is connected to one end of the double-ended fixed tuning fork and is located between the micro-lever and one end of the double-ended fixed tuning fork.

2. The resonant flow field sensor with inertial force compensation structure according to claim 1, characterized in that: Also included is an anchor block, disposed on the substrate; A connecting beam, one end of which is connected to the anchor block, and the other end of which is connected to the ciliary support structure; The connecting beam is suspended on the substrate through the anchor block, and the ciliary support structure is suspended on the substrate through the connecting beam.

3. The resonant flow field sensor with inertial force compensation structure according to claim 2, characterized in that: The comb-tooth capacitors have multiple groups, which are symmetrically arranged on both sides of the double-ended fixed tuning fork and fixed on the substrate; The comb teeth capacitor comprises detection comb teeth and driving comb teeth; The detection comb teeth are close to one side of the double-ended fixed tuning fork, symmetrically arranged up and down, and located on the inner side of the comb teeth capacitor; The driving comb teeth are connected to the detecting comb teeth, are arranged away from one side of the double-ended fixed tuning fork, and are located outside the comb teeth capacitor.

4. The resonant flow field sensor with inertial force compensation structure according to claim 3, characterized in that: The number of the detection comb teeth on both sides of the double-ended fixed tuning fork is different on the left and right sides, so as to form an initial capacitance difference between the comb teeth capacitance on both sides of the double-ended fixed tuning fork, detect the vibration frequency of the double-ended fixed tuning fork in the X-axis direction, so as to reflect the magnitude and direction of the flow field velocity in the Y-axis direction; The number of the driving comb teeth on both sides of the double-ended fixed tuning fork is the same on the left and right sides, and is used to drive the resonator.

5. The resonant flow field sensor with inertial force compensation structure according to claim 3, characterized in that: It also includes an electrode layer, which is arranged on the anchor block and located at the upper peripheral edge of the substrate; The electrode layer includes: a plurality of readout electrodes, which are respectively connected to the two ends of the detection comb teeth on both sides of the substrate, and are used for detecting the readout of capacitance; There are multiple electric field applying electrodes, which are respectively connected to one end of the driving comb teeth on both sides of the substrate and are used to apply an electric field; There are multiple bias voltage electrodes, which are located above the anchor block and are used to provide a bias voltage.

6. The resonant flow field sensor with inertial force compensation structure according to claim 5, characterized in that: The electrode layer is made by Cr / Au metal sputtering process; The Cr / Au metal sputtering process is to first sputter Cr metal and then sputter Au metal.

7. The resonant flow field sensor with inertial force compensation structure according to claim 1, characterized in that: The ciliary support structure is provided with a plurality of concave holes, which are arranged at intervals on the upper surface peripheral wall of the ciliary support structure to reduce the mass of the ciliary support structure.

8. The resonant flow field sensor with inertial force compensation structure according to claim 7, characterized in that: The cilium is located at the center of the ciliary support structure; The recessed holes are arranged on the upper surface of the ciliary support structure to surround the ciliary hairs.

9. The resonant flow field sensor with inertial force compensation structure according to claim 2, characterized in that: The comb-tooth capacitor, the cilia support structure, the double-ended fixed tuning fork, and the connecting beam are made of conductive silicon; The substrate is made of glass, and the anchor block is made of silicon; The substrate and the anchor block are sutured by anode; The cilia are made of SU-8 material.

10. A method for preparing a resonant flow field sensor with an inertial force compensation structure, characterized in that: include: The substrate and the anchor block layer are integrated by dry etching on the substrate or etching on the silicon wafer substrate, and then anodic bonding is performed, specifically comprising: Step 1) spin coating photoresist and photolithography anchor block pattern; Step 2) using the photoresist after photolithography as a mask, DRIE or wet etching to form anchor blocks, and then removing the photoresist; Step 3) Anodic bonding the glass to the back side of the etched silicon wafer, or anodic bonding the back side of the silicon wafer to the front side of the etched glass; Step 4) grinding the front side of the silicon wafer to a specific thickness; Step 5) sputtering Cr and Au; Step 6) Spin-coating photoresist and photolithography electrode pattern; Step 7) using the photoresist after photolithography as a mask, etching Cr and Au, and removing the resist; Step 8) Spin-coating photoresist and photolithography device main body pattern; Step 9) using the photoresist after photolithography as a mask, DRIE etches out the device body and removes the resist; Step 10) attaching SU-8 dry film; Step 11) Photolithography of cilia pattern and degumming; Step 12) laser slicing to finally obtain the sensor structure.

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