CN117346947A - Resonant differential pressure sensor capable of realizing static pressure measurement and preparation method - Google Patents
Resonant differential pressure sensor capable of realizing static pressure measurement and preparation method Download PDFInfo
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- 230000003068 static effect Effects 0.000 title claims abstract description 47
- 238000009530 blood pressure measurement Methods 0.000 title claims abstract description 20
- 238000002360 preparation method Methods 0.000 title claims abstract description 11
- 230000035945 sensitivity Effects 0.000 claims abstract description 22
- 239000000758 substrate Substances 0.000 claims abstract description 15
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 6
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- 239000012212 insulator Substances 0.000 claims abstract description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 31
- 229910052710 silicon Inorganic materials 0.000 claims description 31
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- 238000002955 isolation Methods 0.000 claims description 5
- 230000008859 change Effects 0.000 claims description 4
- 239000002131 composite material Substances 0.000 claims description 4
- 229910021332 silicide Inorganic materials 0.000 claims description 4
- FVBUAEGBCNSCDD-UHFFFAOYSA-N silicide(4-) Chemical compound [Si-4] FVBUAEGBCNSCDD-UHFFFAOYSA-N 0.000 claims description 4
- 230000009471 action Effects 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 claims description 3
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- 230000002093 peripheral effect Effects 0.000 claims 1
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- 238000009461 vacuum packaging Methods 0.000 description 5
- 238000013461 design Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 230000005284 excitation Effects 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000010453 quartz Substances 0.000 description 3
- 230000003321 amplification Effects 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000005496 eutectics Effects 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- SBEQWOXEGHQIMW-UHFFFAOYSA-N silicon Chemical compound [Si].[Si] SBEQWOXEGHQIMW-UHFFFAOYSA-N 0.000 description 2
- YTAHJIFKAKIKAV-XNMGPUDCSA-N [(1R)-3-morpholin-4-yl-1-phenylpropyl] N-[(3S)-2-oxo-5-phenyl-1,3-dihydro-1,4-benzodiazepin-3-yl]carbamate Chemical compound O=C1[C@H](N=C(C2=C(N1)C=CC=C2)C1=CC=CC=C1)NC(O[C@H](CCN1CCOCC1)C1=CC=CC=C1)=O YTAHJIFKAKIKAV-XNMGPUDCSA-N 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
- B81C1/00158—Diaphragms, membranes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C3/00—Assembling of devices or systems from individually processed components
- B81C3/001—Bonding of two components
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L13/00—Devices or apparatus for measuring differences of two or more fluid pressure values
- G01L13/06—Devices or apparatus for measuring differences of two or more fluid pressure values using electric or magnetic pressure-sensitive elements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/12—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in capacitance, i.e. electric circuits therefor
- G01L9/125—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in capacitance, i.e. electric circuits therefor with temperature compensating means
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- General Physics & Mathematics (AREA)
- Measuring Fluid Pressure (AREA)
Abstract
The invention provides a resonance differential pressure sensor capable of realizing static pressure measurement and a preparation method thereof, wherein the differential pressure sensor comprises a cover plate structure, a silicon-on-insulator structure, namely an SOI structure and a pressure guiding structure from top to bottom; the SOI structure comprises a device layer, an oxygen buried layer and a substrate layer. The invention utilizes the beam-film integrated structure to have the effect of amplifying stress, improves the problem of small static pressure and differential pressure measurement sensitivity in the prior art, and solves the problems of large hysteresis, poor repeatability and poor precision caused by the small static pressure and differential pressure measurement sensitivity.
Description
Technical Field
The invention relates to the technical field of MEMS (micro electro mechanical systems) microsensors, in particular to a resonant differential pressure sensor capable of realizing static pressure measurement and a preparation method thereof.
Background
The differential pressure sensor is a sensor for measuring the pressure difference value at two ends, and is widely applied to the fields of aerospace, industrial control, medical electronics and the like. The pressure measuring device indirectly measures pressure by detecting the change of the resonant frequency of the resonator when the resonant differential pressure sensor works, has the characteristics of high resolution, good stability and high comprehensive precision, and is widely applied to the fields of medical electronics, industrial control, aerospace and the like. The core structure of a resonant differential pressure sensor is typically composed of a pressure sensitive membrane and a resonator fabricated on its surface. The pressure sensitive film is deformed under the action of differential pressure on two sides, so that the axial stress of the resonator fixed on the surface of the pressure sensitive film is changed, and finally the resonant frequency of the resonator is changed. The differential pressure value on both sides of the sensitive membrane can be measured indirectly by monitoring the resonance frequency change of the resonator.
Limited by the structural characteristics of the resonator, resonant differential pressure sensors require sealing the resonator in a high vacuum. The structural integrity of the pressure sensitive membrane is therefore limited, further resulting in a non-linear variation of frequency with differential pressure. To solve this problem, patent publication No. CN115215287a proposes "a method for designing and manufacturing a resonant differential pressure sensor based on a eutectic bonding process", in which a resonator is wrapped inside a sensitive film by a eutectic bonding method. Although the method improves the integrity of the sensitive film to a certain extent, the conversion efficiency between the axial stress of the resonator wrapped in the sensitive film and the differential pressure is low, and the problem of low sensitivity exists. The resonator is wrapped on the surface of the pressure sensitive film by using a resonance differential pressure sensor designed by self-aligned selective epitaxial growth and selective etching technology in the cross river of Japan. Although this method can improve the sensitivity of the differential pressure sensor to some extent, the effect of amplifying the stress of the beam-film integrated structure cannot be exerted. In addition, the technology has the problems that the silicon epitaxial growth is performed for a plurality of times under different conditions, the process is complex, the internal stress is large, the adhesion failure of the resonator is easy to cause in the selective corrosion process, the vibration direction is perpendicular to the diaphragm, the modal coupling is easy to occur, and the energy loss of the resonator is increased. Therefore, how to make the resonator to be a pressure sensitive film surface and complete vacuum packaging is a key to improve the core performances of the differential pressure sensor, such as sensitivity, hysteresis, repeatability, nonlinearity, and the like.
In addition, the influence of static pressure on the performance of a sensor in the differential pressure measurement process is of great importance, and how to realize high-precision measurement of the static pressure is a difficult problem faced by the current technology. In the current technical scheme, no solution of a high-precision static pressure sensor is proposed, but a static pressure sensitive mode is involved. For example, patent publication CN113686483a proposes "a resonant differential pressure sensor integrated with a temperature sensor and a method for manufacturing the same", in which static pressure and temperature compensation of the differential pressure sensor are achieved using three resonators and a temperature sensor scheme. Although the accuracy of differential pressure measurement can be improved to a certain extent, the static pressure sensitivity is extremely low due to the fact that the static pressure sensitive resonator is manufactured at the frame position, and therefore the compensation effect is limited. In addition, the technical scheme also has the problem that the size of the sensor chip is large, and can not meet the use requirement of the miniaturized differential pressure sensor in industrial application.
From the analysis, the existing resonant differential pressure sensor has the problems of small sensitivity, large hysteresis, poor repeatability, incapability of realizing static pressure measurement, complex process and the like.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides a resonant differential pressure sensor with static pressure measurement and a preparation method thereof. The technology utilizes the beam-film integrated structure to have the effect of stress amplification, improves the problem of small static pressure and differential pressure measurement sensitivity in the prior art, and solves the problems of large hysteresis, poor repeatability and poor precision caused by the small static pressure and differential pressure measurement sensitivity.
The invention provides a resonant differential pressure sensor capable of realizing static pressure measurement, which comprises a cover plate structure, a silicon-on-insulator structure, namely an SOI structure and a pressure guiding structure from top to bottom; the SOI structure comprises a device layer, an oxygen buried layer and a substrate layer.
The invention also provides a preparation method of the resonant differential pressure sensor capable of realizing static pressure measurement, which comprises the following specific steps:
a) Cleaning an SOI silicon wafer;
b) Etching a pressure sensitive film on a substrate layer of the SOI silicon wafer;
c) Etching a resonator, a lead and other device layer structures on a device layer of the SOI silicon wafer;
d) Releasing the resonator;
e) Cleaning a silicon wafer;
f) Silicon oxide grows on the upper surface and the lower surface of the silicon wafer;
g) Etching a cavity structure on a silicon wafer;
h) Bonding a silicon wafer with an SOI silicon wafer;
i) Removing redundant parts of the silicon wafer to form a cover plate structure;
j) Growing silicide in the isolation groove to form vacuum package;
k) Cleaning the glass sheet;
l) making a through hole in the glass sheet;
m) bonding the glass sheet to the bonded silicon-SOI composite sheet;
n) electrode preparation.
The invention has the beneficial effects that:
1) The beam-film integrated structure is adopted, and the resonators are all positioned on the surface of the pressure sensitive film, so that the sensitivity of the resonators is improved;
2) The design of the small packaging cover plate of the differential pressure resonator is adopted, so that the structural integrity of a sensitive film where the differential pressure resonator is positioned is ensured, and the influence of static pressure on differential pressure measurement is reduced;
3) The static pressure large cover plate design is adopted, so that the influence of differential pressure at the static pressure resonator on the measurement of static pressure is reduced;
4) By adopting a static pressure and differential pressure compound sensitive mode and a multi-resonator design, in-situ static pressure compensation and differential pressure compensation can be realized, and high-precision static pressure and differential pressure measurement can be realized;
5) The manufacturing stress of the sensor is reduced by adopting a silicon-silicon bonding process;
6) The vacuum packaging is realized by adopting a silicide deposition method, so that the vacuum packaging difficulty of silicon-silicon bonding is reduced.
Drawings
Fig. 1: schematic diagram of the overall structure of the sensor;
fig. 2: a sensor schematic diagram omitting a cover plate structure;
fig. 3: a cross-sectional view of the overall structure of the sensor;
fig. 4: differential pressure resonator sensitivity schematic;
fig. 5: a static pressure resonator sensitivity schematic;
fig. 6: schematic diagram of sensor processing process flow;
fig. 7: different layout diagrams of the overall structure of the sensor are shown.
Detailed Description
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a sensor multilayer structure. Top-down includes a cover plate structure, a silicon-on-insulator structure, i.e., SOI structure, and a voltage guiding structure 500. Wherein the cover structure comprises two small cover plates 101, 102 and one large cover plate 103, the soi structure comprises a device layer 200, a buried oxide layer 300 and a substrate layer 400.
Fig. 2 is a schematic diagram omitting the cover plate structure. On the device layer 200 of SOI structure, three resonators 210, 220 and 230 are fabricated. Wherein resonator 210 and resonator 220 have a greater differential pressure sensitivity and a lower static pressure sensitivity, and resonator 230 has a greater static pressure sensitivity and a smaller differential pressure sensitivity. Around each resonator corresponding to the resonators 210, 220 and 230 in turn, there are distributed bias electrodes 211, 221, 231, driving electrodes 212, 222, 232 and detection electrodes 213, 223, 233, wherein the positions of the driving electrodes and the detection electrodes can be exchanged. The driving electrode is connected with an alternating electric signal, the driving electrode and the resonator are closely spaced, and the opposite part between the driving electrode and the resonator can be regarded as a capacitor. Under the action of the drive electrode, the resonator operates at its own resonant frequency. Meanwhile, the capacitance between the resonator and the detection electrode on the other side changes, and the resonance frequency of the resonator is detected by the change of the capacitance. The resonator and its accompanying electrodes are fixed to the pressure sensitive film 401 of the substrate layer 400 by the buried oxide layer 300. With isolation trenches 240 extending through the device layer 200 between each set of resonators.
In operation, the resonant frequencies of the 3 resonators are subjected to pressure P on both sides of the sensitive film 1 、P 2 And the influence of temperature T, so that the resonant frequency and P can be established 1 、P 2 The relationship with T is as follows:
f1 F2, f3 are the resonant frequencies of the first, second and third resonators, respectively; f1 F2, F3 are polynomial functions of the first, second and third resonator frequencies and pressures P1, P2 and temperature T on both sides of the pressure sensitive membrane, respectively.
By function conversion, P can be obtained 1 、P 2 And T is related to the three resonant frequencies as follows:
g1 G2, G3 are compensation functions for the pressures P1, P2 and the temperature T on both sides of the pressure sensitive membrane.
Thus, the static pressure P can be obtained S Differential pressure P d The expression of temperature T is as follows:
fig. 3 is a cross-sectional view of the overall structure of the sensor. The three sets of resonators and their accompanying electrodes are secured to the pressure sensitive membrane 401 of the substrate layer 400 by the buried oxide layer 300. The pressure guiding structure 500 is provided with a through hole 501 at the center and is connected with the periphery of the substrate layer 400 except the pressure sensitive film in a sealing way. One end pressure of the differential pressure to be measured acts on the pressure sensitive membrane through the through holes 501 in the pressure guiding structure 500, and the other end pressure acts on the pressure sensitive membrane through the surfaces of the exposed device layer 200 and the three cover plates 101, 102 and 103. The corresponding resonators 210 and 220 under the small lids 101 and 102.
Resonators 210 and 220 are primarily acted upon by the resultant of the two side pressures for measuring differential pressure. Taking the cover plate 101 as an example, as shown in fig. 4. The cover plate 101 is provided with a smaller resonant cavity 121, the resonator can vibrate in the resonant cavity, and meanwhile, the designed cover plate is only slightly larger than the resonator, so that the integrity of a pressure sensitive film at the sensitive part of the resonator is ensured as much as possible. The resonator 210 is fabricated on the device layer 200, and is formed with a driving electrode 212 and a detecting electrode 213 on the left and right, and is connected to the pressure sensitive film 401 through the oxygen-buried layer 300, and the oxide layer under the resonator is removed through a release process, so that the resonator can vibrate in a resonant cavity formed by the cover and the substrate. Fig. 5 is a partial cross-sectional view of the resonator 230 location. The cover plate 103 is provided with a larger resonant cavity 123, so that the pressure applied by the upper surface of the cover plate 103 cannot act on the pressure sensitive film 401 and is mainly influenced by the pressure of the lower end, and therefore, the pressure sensitive film can be used for measuring static pressure.
FIG. 6 is a schematic diagram of a process flow for manufacturing a sensor. The SOI process involves the fabrication of the pressure sensitive film 401 portion on the substrate layer, the fabrication of resonator and electrode structures and the release of the resonator at the device layer 200. The cover plate process is mainly used for completing vacuum packaging of the resonator, on one hand, the resonator can be isolated from the outside, the influence of external pollutants and the like on the resonator is avoided, and on the other hand, the quality factor of the resonator can be improved by packaging the resonator in a vacuum-approaching environment, and the pressure guide structure process is mainly used for manufacturing the pressure guide structure. The method comprises the following specific steps:
a) Cleaning an SOI silicon wafer;
b) Etching a pressure sensitive film on a substrate layer of the SOI silicon wafer;
c) Etching a resonator, a lead and other device layer structures on a device layer of the SOI silicon wafer;
d) Releasing the resonator;
e) Cleaning a silicon wafer;
f) Silicon oxide grows on the upper surface and the lower surface of the silicon wafer;
g) Etching a cavity structure on a silicon wafer;
h) Bonding a silicon wafer with an SOI silicon wafer;
i) Removing redundant parts of the silicon wafer to form a cover plate structure;
j) Growing silicide in the isolation groove to form vacuum package;
k) Cleaning the glass sheet;
l) making a through hole in the glass sheet;
m) bonding the glass sheet to the bonded silicon-SOI composite sheet;
n) electrode preparation.
It should be noted that the etching process described above is a preferred scheme, and the actual process can be implemented by means of deep silicon reactive ion etching, wet etching, and the like. Steps h) to j) can be replaced by a silicon-silicon vacuum bonding process. Step j) may be replaced by a deposited metal. Step l) can be realized by mechanical punching, laser processing and sand blasting. The metal/composite metal deposited in step n) includes, but is not limited to, al, cr/Au, ti/Pt/Au, ni/Pd/Au, and the like.
The invention provides a static pressure and differential pressure compound sensitive resonant pressure sensor, which fully utilizes the stress amplification characteristic of a beam-film integrated structure, and improves the sensitivity of a resonator respectively through the design of cover plates with different sizes, so that the measurement of the static pressure and the differential pressure is synchronously realized. For the purpose of making the objects, technical solutions and advantages of the present technical solution more apparent, the present invention will be further described in detail below with reference to the accompanying drawings.
A resonance differential pressure sensor capable of realizing static pressure measurement and a preparation method thereof comprise the following steps:
1) The sensor comprises 2 differential pressure resonators and 1 static pressure resonator;
2) The differential pressure resonator is packaged by a small cover plate, and the static pressure resonator is packaged by a large cover plate;
3) The resonators are all positioned on the surface of the pressure sensitive film;
4) The differential pressure resonator has the advantages that as the cover plate is smaller, the pressures on the upper surface and the lower surface are distributed on the upper side and the lower side of the sensitive film during operation, and the influence of static pressure on differential pressure measurement is reduced;
5) The static pressure resonator has the advantages that as the cover plate is large, the upper surface pressure only acts on the surface of the large cover plate during working, and the influence on the pressure sensitive film is small, so that the deformation of the pressure sensitive film is mainly influenced by the lower surface pressure, and the influence of differential pressure on static pressure sensitivity is reduced;
6) The multi-resonator can realize in-situ static pressure and temperature compensation;
7) The vacuum packaging of the resonator is realized by adopting a silicon-silicon bonding mode;
8) The resonator is preferably driven and detected by electrostatic excitation and capacitance detection.
It should be noted that:
1) In the technical scheme, the cover plate can be replaced by a glass plate/quartz plate, the pressure guide structure can be made of a silicon wafer/quartz plate, and the SOI silicon wafer can be replaced by a cavity-SOI, multilayer silicon-silicon structure/quartz structure/glass structure;
2) The technical scheme is not aimed at a specific structure, and is suitable for the structure of the resonator which is familiar to the person skilled in the art at present, and comprises but is not limited to a long straight beam, an H-shaped beam, an annular beam and the like;
3) The electrostatic excitation/electrostatic detection of the resonator adopted in the technical scheme is a preferred scheme, and is suitable for the driving/detection modes which are commonly used by the person skilled in the art at present, including but not limited to electrostatic driving/capacitance detection, electrostatic driving/piezoresistive detection, electromagnetic driving/electromagnetic detection, electromagnetic driving/piezoresistive detection, electrothermal excitation/piezoresistive detection and the like;
4) In the technical scheme, the positions and the directions of the resonators on the pressure sensitive film can be distributed differently, and the resonators can be distributed at different angles with the pressure sensitive film;
5) In this technical solution, the position of the static pressure resonator cover is not limited to the edge or one side of the sensor, and may be located at different positions such as the center of the pressure sensitive film, as shown in fig. 7.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (8)
1. The resonant differential pressure sensor capable of realizing static pressure measurement is characterized by comprising a cover plate structure, a silicon-on-insulator structure, namely an SOI structure and a pressure guiding structure from top to bottom; the SOI structure comprises a device layer, an oxygen buried layer and a substrate layer.
2. The resonant differential pressure sensor of claim 1, wherein three resonators, namely a first resonator, a second resonator, and a third resonator, are fabricated on the device layer of the SOI structure; wherein the first resonator and the second resonator have a large differential pressure sensitivity and a small static pressure sensitivity, and the third resonator has a large static pressure sensitivity and a small differential pressure sensitivity; the first, second and third bias electrodes, the first, second and third drive electrodes, the first, second and third detection electrodes, the first, second and third bias electrodes, the first, second and third drive electrodes, the first, second and third detection electrodes form auxiliary electrodes of the resonators, alternating electric signals are communicated to the drive electrodes, and a capacitor is formed at the opposite part between the drive electrodes and the resonators; under the action of the driving electrode, the resonator works at the resonance frequency of the resonator; meanwhile, the capacitance between the resonator and the detection electrode at the other side is changed, and the resonance frequency of the resonator is detected through the change of the capacitance; the resonator and the auxiliary electrode thereof are fixed on the pressure sensitive film of the substrate layer through the oxygen burying layer; and there is an isolation trench between each set of resonators that extends through the device layer.
3. The resonant differential pressure sensor of claim 2, wherein in operation, 3 resonancesPressure P on two sides of pressure sensitive film of resonant frequency of resonator 1 、P 2 And the influence of temperature T, thus establishing the resonant frequency and the pressure P on both sides 1 、P 2 The relationship with temperature T is as follows:
f 1 ，f 2 ，f 3 the resonant frequencies of the first, second and third resonators, respectively; f (F) 1 ，F 2 ，F 3 The frequency of the first resonator, the second resonator and the third resonator are respectively equal to the pressure P on two sides of the pressure sensitive film 1 、P 2 And a polynomial function of temperature T;
by function conversion, P is obtained 1 、P 2 And T is related to the three resonant frequencies as follows:
G 1 ，G 2 ，G 3 for pressure P on both sides of the pressure-sensitive membrane 1 、P 2 And a compensation function for temperature T;
obtaining static pressure P S Differential pressure P d The expression of temperature T is as follows:
4. the resonant differential pressure sensor of claim 1, wherein the three sets of resonators and their accompanying electrodes are secured to the pressure sensitive membrane of the substrate layer by a buried oxide layer; the center of the pressure guide structure is provided with a through hole and is in sealing connection with the peripheral area of the substrate layer except the pressure sensitive film; one end pressure of the differential pressure to be measured acts on the pressure sensitive film through the through hole on the pressure guiding structure, and the other end pressure acts on the pressure sensitive film through the exposed device layer and the surfaces of the three cover plates; and the first resonator and the second resonator are respectively corresponding to the two small cover plates.
5. The resonant differential pressure sensor of claim 1, wherein the first and second resonators are subjected to a resultant of two side pressures for measuring differential pressure.
6. The resonant differential pressure sensor of claim 1, wherein the first small cover plate is provided with a smaller first resonant cavity, the first resonator can vibrate in the first resonant cavity, and the first small cover plate is only slightly larger than the first resonator; the first resonator is manufactured on the device layer, the left and right parts are a first driving electrode and a first detecting electrode, the first driving electrode and the first detecting electrode are connected together through the oxygen burying layer and the pressure sensitive film, and the oxygen burying layer below the first resonator is removed through a release process.
7. The resonant differential pressure sensor of claim 1, wherein the third resonator is affected by a lower end pressure for measuring static pressure.
8. A preparation method of a resonant differential pressure sensor capable of realizing static pressure measurement is characterized by comprising the following specific steps:
a) Cleaning an SOI silicon wafer;
b) Etching a pressure sensitive film on a substrate layer of the SOI silicon wafer;
c) Etching a resonator, a lead and other device layer structures on a device layer of the SOI silicon wafer;
d) Releasing the resonator;
e) Cleaning a silicon wafer;
f) Silicon oxide grows on the upper surface and the lower surface of the silicon wafer;
g) Etching a cavity structure on a silicon wafer;
h) Bonding a silicon wafer with an SOI silicon wafer;
i) Removing redundant parts of the silicon wafer to form a cover plate structure;
j) Growing silicide in the isolation groove to form vacuum package;
k) Cleaning the glass sheet;
l) making a through hole in the glass sheet;
m) bonding the glass sheet to the bonded silicon-SOI composite sheet;
n) electrode preparation.
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| CN202311296975.9A CN117346947A (en) | 2023-10-09 | 2023-10-09 | Resonant differential pressure sensor capable of realizing static pressure measurement and preparation method |
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| CN202311296975.9A CN117346947A (en) | 2023-10-09 | 2023-10-09 | Resonant differential pressure sensor capable of realizing static pressure measurement and preparation method |
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