A silicon resonant pressure sensor and its online calibration method

Abstract

The present invention discloses a silicon resonant pressure sensor, which includes a resonant layer, a substrate layer and a cover plate layer. A resonant beam is provided on the resonant layer, and first calibration capacitors are provided at both ends of the resonant beam. A second calibration capacitor matching the first calibration capacitor is provided at one end of the cover plate layer close to the resonant layer; the present invention also discloses an on-line calibration method for a silicon resonant pressure sensor, which includes steps S1-S4. In the present invention, the first calibration capacitor and the second calibration capacitor form a calibration capacitor pair. Applying a DC voltage across the calibration capacitor pair can form an electrostatic force between the first calibration capacitor and the second calibration capacitor, which is convenient for simulating the calibration function of the pressure controller, realizing the on-line calibration function of the silicon resonant pressure sensor inside the whole machine system, and avoiding the adverse effects on cost and time caused by replacing the sensor or disassembling and recalibrating the whole machine system.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor microelectromechanical systems, and particularly to a silicon resonant pressure sensor and an on-line calibration method thereof. Background Art

[0002] With the development of microelectromechanical technology, MEMS silicon resonant pressure sensors are widely used in fields such as aerospace, industrial control, and meteorological measurement due to their characteristics of high precision, high stability, batch manufacturability, small size, and low power consumption. A silicon resonant pressure sensor usually consists of a pressure-sensitive diaphragm and a resonator. When an external pressure acts on the sensitive diaphragm, the sensitive diaphragm will deflect and deform, causing a change in the stiffness of the resonator on the diaphragm, and ultimately resulting in a change in the resonant frequency of the resonator. Thus, the magnitude of the external pressure value is obtained by detecting the change in the resonant frequency.

[0003] However, silicon resonant pressure sensors usually exhibit time drift phenomena due to factors such as processing thermal stress and packaging stress, resulting in a decrease in their measurement accuracy over time. At this time, in order to make the silicon resonant pressure sensor meet the high-precision measurement requirements, the method of "replacing the new pressure sensor or removing the sensor from the installation component or the whole machine system, and externally connecting a high-precision pressure controller to recalibrate and restore the accuracy, and then reinstalling after the accuracy is restored" is usually adopted. However, this method requires the shutdown of the whole machine system of the sensor and is extremely cumbersome. Especially for a complex system with hundreds or thousands of pressure sensor arrays, the workload is extremely large, time-consuming, and costly, and frequent replacement is likely to cause damage to the installation components of the pressure sensor, seriously reducing the work efficiency. Summary of the Invention

[0004] In view of the above deficiencies of the prior art, the present invention provides a silicon resonant pressure sensor with high calibration efficiency and an on-line calibration method thereof.

[0005] To achieve the above invention object, the technical solution adopted by the present invention is as follows:

[0006] In the first aspect, a silicon resonant pressure sensor is provided, which includes:

[0007] A resonant layer, on which a resonant beam is provided. On both sides of the resonant beam, a first detection comb tooth and a second detection comb tooth are respectively provided. On both sides of the resonant beam, driving comb teeth are provided. At both ends of the resonant beam, first calibration capacitors are provided;

[0008] A substrate layer, at both ends of which pressure-sensitive diaphragms for sensing external pressure are provided. On the pressure-sensitive diaphragms, silicon islands connected to the resonant beam are provided;

[0009] The cover plate layer is arranged at one end of the resonant layer away from the substrate layer, and a second calibration capacitor matching the first calibration capacitor is arranged at one end of the cover plate layer close to the resonant layer.

[0010] The beneficial effects of adopting the above technical solution are as follows: The first calibration capacitor and the second calibration capacitor form a calibration capacitor pair. By applying a DC voltage across the two ends of the calibration capacitor pair, an electrostatic force can be formed between the first calibration capacitor and the second calibration capacitor, which is convenient for simulating the calibration function of the pressure controller, realizing the on-line calibration function of the silicon resonant pressure sensor inside the whole machine system, and avoiding the adverse effects on cost and time caused by replacing the sensor or disassembling and recalibrating the whole machine system; among them, the magnitude of the DC voltage corresponds to the magnitude of the electrostatic force, which is beneficial to obtaining the corresponding electrostatic force by changing the magnitude of the DC voltage.

[0011] After the driving comb teeth, the first detection comb teeth and the second detection comb teeth are externally connected with a DC voltage, the resonant beam will make a reciprocating motion at its own resonant frequency under the action of the electrostatic force of the driving comb teeth, and will cause a change in the capacitance distance between the first detection comb teeth and the second detection comb teeth. By detecting the change value of this capacitance distance, the resonant frequency of the resonant beam can be obtained.

[0012] The pressure-sensitive diaphragm senses the external pressure. Under the action of the external pressure, the pressure-sensitive diaphragm drives the silicon island to rotate and displace, causing the resonant beam connected to the silicon island to compress towards the middle, resulting in a change in the stiffness of the resonant beam, and thus changing the resonant frequency of the resonant beam. That is, the magnitude of the external pressure can be obtained through the resonant beam frequency detected by the first detection comb teeth and the second detection comb teeth.

[0013] Further, a first electrode, a second electrode and a third electrode are arranged at one end of the cover plate layer away from the resonant layer; the first electrode is electrically connected to the driving comb teeth, which is convenient for the driving comb teeth to externally connect a DC voltage through the first electrode; the second electrode is electrically connected to the second calibration capacitor, which is convenient for the second calibration capacitor to externally connect a DC voltage through the second electrode; the third electrode is electrically connected to the first detection comb teeth and the second detection comb teeth, which is convenient for the first detection comb teeth and the second detection comb teeth to externally connect a DC voltage through the third electrode.

[0014] Further, the number of the first electrodes is equal to the number of the driving comb teeth, the number of the second electrodes is equal to the number of the second calibration capacitors, and the number of the third electrodes is equal to the sum of the number of the first detection comb teeth and the second detection comb teeth, so that the first electrode is connected to the driving comb teeth one by one, the second electrode is connected to the second calibration capacitor one by one, and the third electrode is connected to the first detection comb teeth or the second detection comb teeth one by one, avoiding interference between the driving comb teeth, the second calibration capacitor, the first detection comb teeth and the second detection comb teeth.

[0015] Further, the cover plate layer is a glass cover plate layer, and a plurality of through holes are provided on the cover plate layer. Metal coatings are respectively provided in the plurality of through holes for electrically connecting the first electrode to the driving comb teeth, the second electrode to the second calibration capacitor, and the third electrode to the first detection comb teeth and the second detection comb teeth; the metal coatings electrically connect the first electrode to the driving comb teeth, the second electrode to the second calibration capacitor, and the third electrode to the first detection comb teeth and the second detection comb teeth; in addition, the glass cover plate layer is an insulator, so that the first electrode, the second electrode, and the third electrode can only be energized through the metal coatings.

[0016] Further, a groove for providing a deformation space for the resonant beam is provided at one end of the cover plate layer close to the resonant layer.

[0017] In a second aspect, the present solution also provides an on-line calibration method for a silicon resonant pressure sensor, including the following steps:

[0018] S1: Use a pressure controller to output m standard pressure loads P1, P2, ···, P m to the pressure-sensitive diaphragm, and record the resonant frequencies f1, f2, ···, f m output by the resonant beam at this time;

[0019] S2: Turn off the pressure controller, connect a DC voltage to the second electrode, and adjust the DC voltage so that the resonant frequencies f1', f2', ···, f m ' output by the resonant beam are equal to the resonant frequencies f1, f2, ···, f m output by the resonant beam in step S1, and record the magnitudes V1, V2, ···, V m of the external DC voltages;

[0020] S3: When the silicon resonant pressure sensor exhibits a time drift phenomenon, adjust the external DC voltage to V1, V2, ···, V m , and record the resonant frequencies f1", f2", ···, f m ";

[0021] S4: According to the standard pressure loads P1, P2, ···, P m and the resonant frequencies f1", f2", ···, f m ", calculate the fitting coefficients K1, K2, ···, K m :

[0022]

[0023] where K i is the i-th fitting coefficient. Description of the Drawings

[0024] Figure 1It is a schematic structural diagram of a silicon resonant pressure sensor;

[0025] Figure 2 is Figure 1 exploded view of;

[0026] Figure 3 It is a schematic structural diagram of the resonant layer in this solution;

[0027] Figure 4 It is a schematic structural diagram of the substrate layer in this solution;

[0028] Figure 5 is Figure 4 rear view of;

[0029] Figure 6 It is a schematic working principle diagram of the silicon resonant pressure sensor;

[0030] Figure 7 It is a schematic working principle diagram of the silicon resonant pressure sensor during on-line calibration;

[0031] Among them, 1. Second calibration capacitor, 2. First calibration capacitor, 3. Driving comb teeth, 4. First detection comb teeth, 5. Second detection comb teeth, 6. Resonant beam, 7. Silicon island, 8. Cover layer, 9. Resonant layer, 10. Substrate layer, 11. First electrode, 12. Second electrode, 13. Third electrode, 14. Pressure-sensitive diaphragm. Specific embodiments

[0032] The following describes the specific embodiments of the present invention to facilitate those skilled in the art of this technology to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art of this technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are within the scope of protection.

[0033] As Figures 1-5 shown, this solution provides a silicon resonant pressure sensor, which includes:

[0034] A resonant layer 9, on which a resonant beam 6 is provided. On both sides of the resonant beam 6, a first detection comb tooth 4 and a second detection comb tooth 5 are respectively provided. On both sides of the resonant beam 6, driving comb teeth 3 are provided. At both ends of the resonant beam 6, first calibration capacitors 2 are provided;

[0035] A substrate layer 10, at both ends of which pressure-sensitive diaphragms 14 for sensing external pressure are provided. On the pressure-sensitive diaphragm 14, a silicon island 7 connected to the resonant beam 6 is provided;

[0036] The cover plate layer 8 is provided at one end of the resonant layer 9 away from the substrate layer 10, and a second calibration capacitor 1 matching the first calibration capacitor 2 is provided at one end thereof close to the resonant layer 9.

[0037] As Figure 7 shown, the first calibration capacitor 2 and the second calibration capacitor 1 form a calibration capacitor pair. Applying a DC voltage across the calibration capacitor pair can form an electrostatic force between the first calibration capacitor 2 and the second calibration capacitor 1, which facilitates simulating the calibration function of the pressure controller, realizes the online calibration function of the silicon resonant pressure sensor inside the whole machine system, and avoids the adverse effects on cost and time caused by replacing the sensor or disassembling and recalibrating the whole machine system; among them, the magnitude of the DC voltage corresponds to the magnitude of the electrostatic force, which is conducive to obtaining the corresponding electrostatic force by changing the magnitude of the DC voltage.

[0038] After the driving comb teeth 3, the first detection comb teeth 4, and the second detection comb teeth 5 are externally connected with a DC voltage, the resonant beam 6 will reciprocate back and forth at its own resonant frequency under the action of the electrostatic force of the driving comb teeth 3, and will cause a change in the capacitance distance between the first detection comb teeth 4 and the second detection comb teeth 5. By detecting the change value of this capacitance distance, the resonant frequency of the resonant beam 6 can be obtained;

[0039] As Figure 6 shown, the pressure-sensitive diaphragm 14 senses the external pressure. Under the action of the external pressure, the pressure-sensitive diaphragm 14 receives a load acting towards the resonant layer 9 and drives the silicon island 7 to rotate and displace, so that the resonant beam 6 connected to the silicon island 7 is compressed towards the middle under the action of the radial compressive stress σ, resulting in a change in the stiffness of the resonant beam 6, thereby changing the resonant frequency of the resonant beam 6. That is, the magnitude of the external pressure can be obtained through the frequency of the resonant beam 6 detected by the first detection comb teeth 4 and the second detection comb teeth 5.

[0040] During implementation, it is preferably that a first electrode 11, a second electrode 12, and a third electrode 13 are provided at one end of the cover plate layer 8 away from the resonant layer 9; the first electrode 11 is electrically connected to the driving comb teeth 3, which facilitates the driving comb teeth 3 to be externally connected with a DC voltage through the first electrode 11; the second electrode 12 is electrically connected to the second calibration capacitor 1, which facilitates the second calibration capacitor 1 to be externally connected with a DC voltage through the second electrode 12; the third electrode 13 is electrically connected to the first detection comb teeth 4 and the second detection comb teeth 5, which facilitates the first detection comb teeth 4 and the second detection comb teeth 5 to be externally connected with a DC voltage through the third electrode 13.

[0041] In one embodiment of the present invention, the number of the first electrodes 11 is equal to the number of the driving comb teeth 3, the number of the second electrodes 12 is equal to the number of the second calibration capacitors 1, and the number of the third electrodes 13 is equal to the sum of the number of the first detection comb teeth 4 and the number of the second detection comb teeth 5, so that the first electrodes 11 are connected to the driving comb teeth 3 one by one, the second electrodes 12 are connected to the second calibration capacitors 1 one by one, and the third electrodes 13 are connected to the first detection comb teeth 4 or the second detection comb teeth 5 one by one, thus avoiding interference among the driving comb teeth 3, the second calibration capacitors 1, the first detection comb teeth 4 and the second detection comb teeth 5.

[0042] In design, it is preferred that the cover layer 8 is a glass cover layer in this solution. A plurality of through holes are provided on the cover layer 8, and metal coatings for electrically connecting the first electrodes 11 to the driving comb teeth 3, the second electrodes 12 to the second calibration capacitors 1, and the third electrodes 13 to the first detection comb teeth 4 and the second detection comb teeth 5 are respectively provided in the plurality of through holes; the metal coatings electrically connect the first electrodes 11 to the driving comb teeth 3, the second electrodes 12 to the second calibration capacitors 1, and the third electrodes 13 to the first detection comb teeth 4 and the second detection comb teeth 5; in addition, the glass cover layer is an insulator, so that the first electrodes 11, the second electrodes 12 and the third electrodes 13 can only be electrified through the metal coatings; wherein, the through holes are TGV glass through holes, and the metal coatings can be made by electroplating process.

[0043] During implementation, it is preferred that a groove for providing a deformation space for the resonant beam 6 is provided at one end of the cover layer 8 close to the resonant layer 9 in this solution.

[0044] This solution also provides an on-line calibration method for a silicon resonant pressure sensor, including the following steps: [[ID=ID=10]]

[0045] S1: Before the silicon resonant pressure sensor is installed, use a pressure controller to output m standard pressure loads P1, P2, ···, P m to the pressure-sensitive diaphragm 14, and record the resonant frequencies f1, f2, ···, f m output by the resonant beam 6 at this time;

[0046] S2: Turn off the pressure controller, connect a DC voltage to the second electrode 12, and adjust the DC voltage to make the resonant frequencies f1', f2', ···, f m ' output by the resonant beam 6 equal to the resonant frequencies f1, f2, ···, f m output by the resonant beam 6 in step S1, and record the magnitudes V1, V2, ···, V m of the external DC voltage at this time;

[0047] S3: When the silicon resonant pressure sensor shows a time drift phenomenon, adjust the external DC voltage to V1, V2, ···, V m, record the resonant frequencies f1”, f2”, ···, f output by the resonant beam 6 at this time m ”;

[0048] S4: According to the standard pressure loads P1, P2, ···, P m and the resonant frequencies f1”, f2”, ···, f m ”, calculate the fitting coefficients K1, K2, ···, K m :

[0049]

[0050] wherein, K i is the i-th fitting coefficient.

[0051] The traditional calibration method requires removing the silicon resonant pressure sensor from the whole machine system and then using a pressure controller for calibration; while in this solution, a DC voltage is externally connected to the second electrode 12 to form an electrostatic force between the first calibration capacitor 2 and the second calibration, and different magnitudes of DC voltages correspond to different electrostatic forces, so as to simulate the standard pressure output of the pressure controller through the electrostatic force, avoid removing the silicon resonant sensor, and achieve online calibration.

Claims

1. A silicon resonant pressure sensor, characterized in that, Comprising: A resonant layer (9) with a resonant beam (6) disposed thereon. On both sides of the resonant beam (6), a first detection comb (4) and a second detection comb (5) are respectively arranged. On both sides of the resonant beam (6), drive combs (3) are arranged. At both ends of the resonant beam (6), first calibration capacitors (2) are arranged. A substrate layer (10) with pressure-sensitive diaphragms (14) for sensing external pressure arranged at both ends thereof. On the pressure-sensitive diaphragms (14), silicon islands (7) connected to the resonant beam (6) are arranged. A cover layer (8) disposed at an end of the resonant layer (9) away from the substrate layer (10). At an end of the cover layer (8) close to the resonant layer (9), a second calibration capacitor (1) matching the first calibration capacitor (2) is arranged.

2. The silicon resonant pressure sensor according to claim 1, wherein, At an end of the cover layer (8) away from the resonant layer (9), a first electrode (11), a second electrode (12) and a third electrode (13) are arranged. The first electrode (11) is electrically connected to the drive comb (3), the second electrode (12) is electrically connected to the second calibration capacitor (1), and the third electrode (13) is electrically connected to the first detection comb (4) and the second detection comb (5).

3. The silicon resonant pressure sensor according to claim 2, wherein The number of the first electrodes (11) is equal to the number of the drive combs (3), the number of the second electrodes (12) is equal to the number of the second calibration capacitors (1), and the number of the third electrodes (13) is equal to the sum of the numbers of the first detection comb (4) and the second detection comb (5).

4. The silicon resonant pressure sensor according to claim 2, wherein The cover layer (8) is a glass cover layer, and a plurality of through holes are arranged on the cover layer (8). Metal coatings for electrically connecting the first electrode (11) to the drive comb (3), the second electrode (12) to the second calibration capacitor (1), and the third electrode (13) to the first detection comb (4) and the second detection comb (5) are respectively arranged in the plurality of through holes.

5. The silicon resonant pressure sensor according to claim 1, characterized in that, At an end of the cover layer (8) close to the resonant layer (9), a groove for providing a deformation space for the resonant beam (6) is arranged.

6. An on-line calibration method for the silicon resonant pressure sensor according to any one of claims 1-5, characterized in that, Comprising the following steps: S1: Output m standard pressure loads P1, P2, ···, P by using a pressure controller m to the pressure-sensitive diaphragm (14), and record the resonant frequencies f1, f2, ···, f output by the resonant beam (6) at this time m ; S2: Turn off the pressure controller, connect DC voltage to the second electrode (12), and adjust the DC voltage so that the resonance frequencies f1 ’ , f2 ’ , ···, f m ’ output by the resonance beam (6) are equal to the resonance frequencies f1, f2, ···, f m output by the resonance beam (6) in step S1, and record the magnitudes of the external DC voltages V1, V2, ···, V m ; S3: When the silicon resonant pressure sensor shows a time drift phenomenon, adjust the external DC voltage to V1, V2, ···, V m , and record the resonant frequencies f1”, f2”, ···, f m ”; S4: According to the standard pressure loads P1, P2, ···, P m and the resonant frequencies f1”, f2”, ···, f m ”, calculate the fitting coefficients K1, K2, ···, K m : Among them, K i is the i-th fitting coefficient.

Images