CN114199323B - Monolithic integrated MEMS differential pressure flowmeter and preparation method thereof - Google Patents
Monolithic integrated MEMS differential pressure flowmeter and preparation method thereof Download PDFInfo
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- CN114199323B CN114199323B CN202111503329.6A CN202111503329A CN114199323B CN 114199323 B CN114199323 B CN 114199323B CN 202111503329 A CN202111503329 A CN 202111503329A CN 114199323 B CN114199323 B CN 114199323B
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- differential pressure
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
- G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
- B81B7/02—Microstructural systems; Auxiliary parts of microstructural devices or systems containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS]
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00023—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems without movable or flexible elements
- B81C1/00047—Cavities
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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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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
Abstract
The invention provides a monolithic integrated MEMS differential pressure flowmeter and a preparation method thereof. The monolithic integrated MEMS differential pressure flowmeter of the present invention comprises: the MEMS differential pressure sensor comprises an MEMS differential pressure chip, a restrictor and an electrode signal interface, wherein a stress sensing film, a piezoresistive stress sensitive bridge and a stress cavity are integrated in the MEMS differential pressure chip; the throttler and the MEMS differential pressure chip are integrated, a plurality of function holes are distributed on the throttler, and stress difference is generated between the front section and the rear section of the throttler when fluid passes through the function holes. The monolithic integrated MEMS differential pressure flowmeter of the invention simultaneously realizes the design and preparation of the MEMS differential pressure chip, the throttler and the electrode signal interface on the same silicon chip, compared with the traditional differential pressure flowmeter, the monolithic integrated MEMS differential pressure flowmeter not only avoids the influence of noise and size caused by the integration of the MEMS differential pressure chip and the throttler, but also effectively utilizes the original measurement advantages of the differential pressure flowmeter, so that the device has the characteristics of high integration level, low cost and small volume.
Description
The technical field is as follows:
the invention belongs to the technical field of microelectronic sensors, and relates to a monolithic integrated MEMS differential pressure flowmeter and a preparation method thereof.
The background art comprises the following steps:
metering is the eye of industrial processes, and flow rates, which are important physical quantities of industrial processes, need to be accurately measured. Particularly for accurate measurement of medium and small flow, the market puts higher demands on the portability, the cost performance and the application range of the flowmeter. The differential pressure type flowmeter is one of the flow measuring instrument families, and becomes a flow measuring instrument which is most widely applied in the flow measuring field due to the advantages of low cost and high precision. According to different detection element forms, the differential pressure flowmeter can be divided into a plurality of subtype flowmeters, wherein the porous balance flowmeter is used as an energy-saving type flowmeter, compared with the traditional orifice plate flowmeter, the flow field balance can be adjusted to an ideal state to the maximum extent, and the permanent pressure loss caused under the condition of the same measurement condition and without reducing the pressure difference is smaller. In addition, the flowmeter has low requirement on a straight pipe section, has higher range ratio and precision grade, and is commonly used for large-scale flow measurement in industrial production.
However, the existing porous balance flowmeter has the defects of large integral size, incapability of integrating the pressure taking device with the porous throttle, poor installation portability and the like. With the rapid development of semiconductor technology, the size of components is greatly reduced, the cost is greatly reduced, and the process integration level is greatly improved. The porous balance flowmeter is integrated with the differential pressure sensor based on the MEMS technology, so that the cost is reduced, the product integration degree and the portability are improved, the original advantages of the porous balance flowmeter can be kept, the porous balance flowmeter can be applied to measurement of medium and small flows, and the porous balance flowmeter has a good application prospect in the Internet of things containing intelligent household appliances.
The invention content is as follows:
the invention aims to provide a monolithic integrated MEMS differential pressure flowmeter structure, which integrates a restrictor and an MEMS differential pressure chip into a whole and has the characteristics of small volume, low cost and easy installation.
The invention further aims to provide a preparation method of the monolithic integrated MEMS differential pressure flowmeter.
The technical solution of the invention is as follows: a monolithic integrated MEMS differential pressure flowmeter comprises an MEMS differential pressure chip, a restrictor and an electrode signal interface; the MEMS differential pressure chip is positioned at the central position of the whole structure of the flowmeter and comprises a stress sensing film, a piezoresistive stress sensitive bridge and a stress cavity, wherein the stress sensing film is positioned at the central position of the MEMS differential pressure chip; the throttler and the MEMS differential pressure chip are integrated and are processed and prepared on the same silicon chip, a plurality of function holes are formed in the throttler and distributed on the outer circumference with the MEMS differential pressure chip as the center, and when fluid passes through the function holes, the front section and the rear section of the throttler generate stress difference; the electrode signal interfaces are positioned on two sides of the flowmeter structure and used for transmitting stress signals.
The MEMS differential pressure chip, the throttleer and the electrode signal interface are all prepared on monocrystalline silicon.
According to the monolithic integrated MEMS differential pressure flowmeter, when fluid passes through, the function holes in the restrictor enable the front end and the rear end of the restrictor to generate stress difference, the stress sensing film located in the center of the restrictor senses stress change, and the piezoresistive stress sensing bridge converts the stress change into a voltage signal and finally transmits the voltage signal to the electrode signal interface.
The preparation method of the monolithic integrated MEMS differential pressure flowmeter comprises the following steps:
1. photoetching a stress cavity on the back of the silicon wafer;
2. mechanically thinning the front side of the silicon wafer to form a stress induction film;
3. oxidation to form SiO on the upper layer of stress-induced film 2 Photoetching a piezoresistive pattern;
4. ion implantation is carried out, and a P-area, a P + area and an n + area are formed respectively;
5. photoetching the marked position on the front surface of the silicon wafer, and sputtering metal to corrode to form an electrode;
6. etching the marked position on the front surface of the silicon wafer to form a function hole;
7. and (6) scribing.
The invention has the advantages and positive effects that:
the monolithic integrated MEMS differential pressure flowmeter simultaneously realizes the design and preparation of an MEMS differential pressure chip, a restrictor and an electrode signal interface on the same silicon chip. Compared with the traditional differential pressure flowmeter, the differential pressure flowmeter has the advantages of avoiding the influence of noise and size caused by the integration of an MEMS differential pressure chip and a restrictor, effectively utilizing the original measurement advantages of the differential pressure flowmeter, and enabling devices to have the characteristics of high integration level, low cost and small size.
Drawings
Fig. 1 is a schematic structural view of a monolithic integrated MEMS differential pressure flowmeter of the present invention. Wherein (a) is a top view and (b) is a central axial sectional view of the figure (a).
Fig. 2 (a) to (g) illustrate the main fabrication process of the monolithic MEMS differential pressure flow meter according to the present invention.
In the figure:
1-silicon chip, 2-MEMS differential pressure chip, 3-electrode signal interface, 4-restrictor function hole, 5-stress induction film, 6-piezoresistive stress sensitive bridge and 7-stress cavity
Detailed Description
Example 1: monolithic integrated MEMS differential pressure flowmeter structure
Fig. 1 is a schematic diagram of a monolithic integrated MEMS differential pressure flow meter. The MEMS differential pressure chip comprises an MEMS differential pressure chip 2, an electrode signal interface 3 and a restrictor function hole 4. The MEMS differential pressure chip 2, the electrode signal interface 3 and the throttler function hole 4 are processed and prepared on the same silicon chip 1. The MEMS differential pressure chip 2 is arranged at the center of the flowmeter structure and consists of a stress induction film 5, a piezoresistive stress sensitive bridge 6 and a stress cavity 7. The stress sensing film 5 is positioned at the center of the MEMS differential pressure chip 2, a stress cavity 7 is arranged below the stress sensing film 5, and the piezoresistive stress sensitive bridge 6 is distributed around the stress sensing film 5. The throttle function holes 4 are distributed on the outer circumference of the MEMS differential pressure chip 2 and used for generating stress difference. Electrode signal interfaces 3 are located on both sides of the flow meter structure.
Example 2: method for preparing monolithic integrated MEMS differential pressure flowmeter
Fig. 2 shows the main fabrication process of the monolithic integrated MEMS differential pressure flow meter.
1. Photoetching a stress cavity on the back surface of the silicon wafer, as shown in FIG. 2 (a);
2. mechanically thinning the front surface of the silicon wafer to form a stress induction film as shown in fig. 2 (b);
3. oxidation of the upper layer of the stress-induced film to form silicon dioxide (SiO) 2 ) Photoetching a piezoresistive pattern, as shown in FIG. 2 (c);
4. injecting boron ions B + to form a P-region;
5. removing photoresist by a dry method, carrying out third photoetching, and injecting boron ions B + to form a P + region;
6. removing photoresist conventionally, performing fourth photoetching, and implanting phosphorus ions P & lt- & gt to form an n & lt + & gt region, as shown in FIG. 2 (d);
7. dry photoresist removing and wet etching of SiO 2 Forming an isolation layer by thermal oxidation;
8. sputtering metallic Al with a thickness of 1 μm, as shown in FIG. 2 (e);
9. photoetching a lead, corroding Al, growing a passivation layer, and photoetching to form an electrode, as shown in FIG. 2 (f);
10. and etching the marked positions on the front surface of the silicon wafer to form functional holes, as shown in FIG. 2 (g).
11. And (6) scribing.
The monolithic integrated MEMS differential pressure flowmeter prepared by the method has the specific internal structure design that: the center position is MEMS differential pressure chip 2, throttler function hole 4 distributes in MEMS differential pressure chip 2 outer circumference position, electrode signal interface 3 is in the both sides of flowmeter structure. The MEMS differential pressure chip 2 internally comprises a stress sensing film 5 and a piezoresistive stress sensitive bridge 6, and a stress cavity 7 is positioned below the stress sensing film 5. The flow direction of the flow meter signals is as follows: after electrification, when fluid in a pipeline flows through the monolithic integrated MEMS differential pressure flowmeter, the front and rear stress of the pipeline is changed by the restrictor function hole 4, the stress sensing film 5 senses stress change, and the piezoresistive stress sensing bridge 6 converts the stress change into a voltage signal and outputs the voltage signal to the electrode signal interface 3.
Claims (8)
1. A monolithic integrated MEMS differential pressure flowmeter is characterized by comprising an MEMS differential pressure chip, a restrictor and an electrode signal interface; the MEMS differential pressure chip comprises a stress sensing film, a piezoresistive stress sensing bridge and a stress cavity, wherein the stress sensing film is located at the center of the MEMS differential pressure chip, the piezoresistive stress sensing bridge is located around the stress sensing film, the stress cavity is arranged below the stress sensing film, function holes of the throttler are distributed on the outer circumference of the MEMS differential pressure chip and used for generating stress difference, electrode signal interfaces are located on two sides of a flowmeter structure, and the MEMS differential pressure chip, the throttler and the electrode signal interfaces are designed and processed on the same silicon chip.
2. The monolithically integrated MEMS differential pressure flow meter of claim 1, wherein the MEMS differential pressure die is centrally located within the overall structure of the flow meter.
3. The monolithically integrated MEMS differential pressure flowmeter of claim 1, wherein the piezoresistive stress sensitive bridges have symmetrically distributed resistances.
4. The monolithically integrated MEMS differential pressure flow meter of claim 1, wherein the stress cavity is trapezoidal in structure, concentrating stress on the stress inducing membrane.
5. The monolithic integrated MEMS differential pressure flowmeter of claim 1, wherein the choke function holes are distributed on the outer circumference centered on the MEMS differential pressure chip, and the number of choke function holes is greater than or equal to 2 according to the application environment requirements.
6. The monolithic integrated MEMS differential pressure flow meter according to claim 1, wherein the MEMS differential pressure chip is connected to the electrode signal interface via metal for signal transmission.
7. A method for preparing a monolithic integrated MEMS differential pressure flowmeter according to claim 1, comprising the steps of, in order:
(1) Photoetching and etching a stress cavity on the back of the silicon wafer;
(2) Mechanically thinning the front side of the silicon chip to form a stress induction film;
(3) Oxidation to produce SiO on the upper layer of stress-induced film 2 Photoetching a piezoresistive pattern;
(4) Ion implantation is carried out to form a P-area, a P + area and an n + area respectively;
(5) Photoetching the marked position on the front surface of the silicon wafer, and sputtering metal to corrode to form an electrode;
(6) Etching the marked position on the front surface of the silicon wafer to form a function hole;
(7) And (6) scribing.
8. The method of claim 7, wherein the step (2) mechanically thins the silicon wafer to form a stress-induced film having a thickness of hundreds of nanometers.
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| CN114199323B true CN114199323B (en) | 2022-11-29 |
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| IL246980B (en) * | 2014-02-01 | 2022-09-01 | Ezmems Ltd | Chip device for monitoring and regulating fluid flow, and methods of manufacture thereof |
| EP3095754B1 (en) * | 2015-05-22 | 2018-10-10 | Amphenol Thermometrics, Inc. | Low pressure sensor and flow sensor |
| JP6652479B2 (en) * | 2016-10-14 | 2020-02-26 | 株式会社フジクラ | Differential pressure detecting element and flow rate measuring device |
| DE102017214786A1 (en) * | 2017-08-23 | 2019-02-28 | Infineon Technologies Ag | MEMS sensors, methods of providing same, and methods of measuring a fluid component |
| CN108254031B (en) * | 2017-12-28 | 2020-07-10 | 上海工程技术大学 | Differential pressure type gas micro-flow sensor and manufacturing method thereof |
| CN110095212A (en) * | 2018-01-30 | 2019-08-06 | 盾安传感科技有限公司 | A kind of MEMS pressure sensor chip and preparation method |
| CN110542498A (en) * | 2019-09-06 | 2019-12-06 | 重庆大学 | MEMS strain differential pressure sensor and manufacturing method thereof |
| CN112212926B (en) * | 2020-08-07 | 2022-04-08 | 北京协同创新研究院 | Flow measurement method based on porous throttling and MEMS pressure sensor |
| CN214121293U (en) * | 2020-11-23 | 2021-09-03 | 北京协同创新研究院 | Pressure taking device of porous balance flowmeter |
| CN214748203U (en) * | 2021-03-15 | 2021-11-16 | 青岛芯笙微纳电子科技有限公司 | High-performance MEMS flow sensor |
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