CN101408442A - Air mass flow sensor of silicone base thin-film structure - Google Patents
Air mass flow sensor of silicone base thin-film structure Download PDFInfo
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- CN101408442A CN101408442A CNA2008102117419A CN200810211741A CN101408442A CN 101408442 A CN101408442 A CN 101408442A CN A2008102117419 A CNA2008102117419 A CN A2008102117419A CN 200810211741 A CN200810211741 A CN 200810211741A CN 101408442 A CN101408442 A CN 101408442A
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- flow sensor
- heating resistor
- mass flow
- air mass
- insulation film
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Abstract
The invention relates to a mass air flow sensor with silica-based thin-film structure on the basis of the MEMS technique. The silica-based material 1 is covered with a layer of insulation film 2, the middle part of the whole structure is etched with a heat insulation cavity 5, and a heating resistance 3 and a resistance temperature detector 4 are arranged on the base material by one time by adopting the MEMS technique. For the arrangement, the heating resistance 3 is arranged on the insulation film 2 of the heat insulation cavity 5, and the resistance temperature detector is arranged on the insulation film on the silica-based material. By adopting the mass air flow sensor of the invention, a hot type mass air flow sensor which has high measuring precision, low power consumption, large measuring range, good consistency of measurement, low cost and constant temperature difference.
Description
Technical field
The present invention relates to a kind of air mass flow sensor that is applicable to the measured automobiles air input of engine by air, particularly, relate to a kind of air mass flow sensor of forming by silica-base film structure sensitive element.
Background technology
Usually, air mass flow sensor as the air input of engine by air of measured automobiles etc., measure air mass flow by the temperature difference of measuring heating resistor upstream resistance and downstream resistance, perhaps the temperature difference by control heating resistor and fluid is constant, measures the size of heating current and measures air mass flow.The mode constant by the temperature difference of control heating resistor and fluid is called the constant difference formula.
The hot type air mass flow sensor of constant difference formula is made up of a heating resistor and a temperature detecting resistance.Constant difference control is actually by one and keeps the ratio of the temperature difference of heating resistor and temperature detecting resistance and heating resistor constant with above-mentioned two resistance as the resistance bridge of key element.
Yet, the prerequisite that above-mentioned measuring principle is set up is that heating resistor and temperature detecting resistance have identical temperature-sensitivity coefficient, and the electric current by heating resistor on the electric bridge will be enough to make the resistance temperature designated value that raises, and the electric current by temperature detecting resistance then should be controlled at temperature detecting resistance is produced in the limit of heat.Prior art usually adopt two independently thermistor respectively as heating resistor and temperature detecting resistance, because the process batch problem be cannot say for sure to demonstrate,prove both and had identical temperature-sensitivity coefficient.And, for the loose requirement of coefficient of the different heat of two resistance, also be a contradiction.In addition, adopt two independently thermistor also make cost comparatively considerable, and consistance is difficult to guarantee.Owing to be subjected to the influence of temperature-sensitive resistive seal dress form, adopt the air mass flow sensor of two independent thermistors also to exist to improve measuring accuracy, can not reduce defectives such as power attenuation and measurement range be limited.
Summary of the invention
The object of the present invention is to provide and to improve measuring accuracy, reduce power attenuation, enlarge the hot type air mass flow sensor of measurement range and high conformity constant difference formula with low cost.
The invention is characterized in that in the silicon materials substrate adopt disposable formation heating resistor of MEMS technology and temperature detecting resistance, heating resistor is positioned at the insulation film zone that forms on the silicon base.Owing to adopt MEMS technology once to form heating resistor and temperature detecting resistance, can guarantee the temperature-sensitivity coefficient unanimity of the two well.Simultaneously,, can do very for a short time by the air mass flow sensor sensitive structure overall dimension that two resistance are formed owing to adopt after the MEMS technology, can a time processing hundreds of structure on same wafer, can guarantee the consistance between the different sensors.
The present invention is forming the insulation film of driving on heat insulation cavity in the silicon materials substrate, and heating resistor is processed on insulation film, make the energy that is applied on the heating resistor can be effectively converted into this ohmically heat, and seldom be lost on the base material, the coefficient thereby the heat that has effectively improved heating resistor is loose, it just can be raise under less power effect reach the temperature spot of appointment, improved measuring accuracy, reduce the power attenuation of air mass flow sensor, and enlarged measurement range.Temperature detecting resistance is directly processed on the insulating material on the silicon base material, and the diffusing relative heating resistor of coefficient of heat is much bigger, has avoided owing to self-heating influences measuring accuracy.
Description of drawings
Fig. 1 is the plane figure of the air mass flow sensor sensitive element that relates to of the embodiment of the invention.
Fig. 2 is an A-A sectional view among Fig. 1.
Fig. 3 is a B-B sectional view among Fig. 1.
Fig. 4 is the circuit control principle figure that is used for the foregoing description.
Embodiment
With reference to the accompanying drawings embodiments of the present invention are illustrated.
As Fig. 1, Fig. 2, shown in Figure 3, the air mass flow sensor that the embodiment of the invention relates to has adopted a kind of silica-base film sensitive structure based on MEMS technology.Described sensitive structure is made up of base material 1, insulation film 2, heating resistor 3, temperature detecting resistance 4, heat insulation cavity 5, temperature detecting resistance cabling 6, pressure welding pad 7.Base material 1 has adopted single crystal silicon material.Cover one deck insulation film 2 on it.At the zone line of whole sensitive structure, form heat insulation cavity 5 by etching technics, make this zone only be left only several microns insulation film 2 of a layer thickness.On insulation film 2, form heating resistor 3 by technologies such as deposition, photoetching, corrosion then.Because the existence of heat insulation cavity 5, insulation film 2 can only could be sent to heat on the base material 1 by cross conduction, because only several microns of the thickness of insulation film 2, so have very big thermal resistance.Because above-mentioned reason, be applied to the temperature that the energy overwhelming majority on the heating resistor 3 all is used to improve heating resistor self, therefore heating resistor 3 has the diffusing coefficient of very little heat, and its temperature is subjected to the influence of base material temperature, circuit temperature, environment temperature etc. all very little, has good stability.This makes the air mass flow sensor that adopts the embodiment of the invention to relate to can be operated under the less working current that compares, thereby has reached the purpose that reduces power attenuation.Simultaneously, owing to have the diffusing coefficient of very little heat, heating resistor on the air mass flow sensor sensitive structure that the embodiment of the invention relates to is easy to just can reach higher relatively temperature, thereby small air-flow is also had good sensitivity, has reached the purpose that improves measuring accuracy.
As shown in Figure 4, heating resistor 3, temperature detecting resistance 4, sampling resistor 8, the adjusting resistance 9 common resistance bridges of forming, operational amplifier 10 and Darlington transistor 11 are formed a current amplification circuit, in order to big heating current to be provided.According to the thermal diffusion principle, heating resistor 3 is relevant with the character of the temperature difference, flow rate of fluid and the fluid of fluid with heating resistor 3 by the heat of fluid removal.The mass rate of supposing fluid is q
m, the resistance of heating resistor 3 is R
h, heating resistor 3 is Δ T with the temperature difference of fluid, is I by the heater circuit on the heating resistor 3, then by deriving as can be known the mass rate q of fluid
mWith
Have functional relation, can be expressed as:
As can be seen from the above equation, only guaranteed
Be normal value, just can be by measuring the mass rate that heating current I measures fluid.Adopt circuit control loop as shown in Figure 4, have only when heating resistor 3 has identical temperature-sensitivity coefficient with temperature detecting resistance 4 just can guarantee
Be normal value.The sensitive structure of the air mass flow sensor that the practical example of the present invention relates to is in the technology implementation procedure, heating resistor 3 and temperature detecting resistance 4 are finished by MEMS technology is disposable, can guarantee well that the two has identical temperature-sensitivity coefficient, thereby have than adopting two independently high measuring accuracy of thermistor.
As shown in Figure 3, temperature detecting resistance 4 is positioned on the insulation film 2 above the base material 1, because silicon materials are good conductors of heat, and silicon materials closely are connected with insulation film 2, therefore, heat on the temperature detecting resistance 4 is easy to lead away by base material 1, and it self can not generated heat under certain function of current.This has also guaranteed the accuracy of measuring.Heat on the heating resistor 3 then is not easy to be transmitted on the temperature detecting resistance 4 owing to the existence of heat insulation cavity 5 and insulation film 2, avoided the interference between two resistance.
Claims (3)
1. air mass flow sensor of silicone base thin-film structure, it is characterized in that being provided with the heat insulation cavity that adopts MEMS technology to realize, insulation film, heating resistor, temperature detecting resistance at interior sensitive element on the silicon base material, described heating resistor is positioned to be driven on the insulation of the insulation film on the heat insulation cavity.
2. air mass flow sensor according to claim 1 is characterized in that described temperature detecting resistance is positioned on the insulation film on the silicon base material.
3. air mass flow sensor according to claim 1, it is characterized in that described heating resistor and temperature detecting resistance adopt MEMS technology in same substrate once property finish, guarantee that the two has identical temperature-sensitivity coefficient.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2008102117419A CN101408442A (en) | 2008-09-24 | 2008-09-24 | Air mass flow sensor of silicone base thin-film structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2008102117419A CN101408442A (en) | 2008-09-24 | 2008-09-24 | Air mass flow sensor of silicone base thin-film structure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101408442A true CN101408442A (en) | 2009-04-15 |
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| Application Number | Title | Priority Date | Filing Date |
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| CNA2008102117419A Pending CN101408442A (en) | 2008-09-24 | 2008-09-24 | Air mass flow sensor of silicone base thin-film structure |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102128655A (en) * | 2010-12-08 | 2011-07-20 | 苏州谷之道软件科技有限公司 | Automotive hot film air flow micro-electromechanical systems (MEMS) sensor with primary and secondary double cavity structure |
| CN106092234A (en) * | 2016-06-02 | 2016-11-09 | 苏州容启传感器科技有限公司 | Hollow out heat membrane type flow sensor with rectifier structure and preparation method thereof |
| CN107643421A (en) * | 2017-11-10 | 2018-01-30 | 苏州原位芯片科技有限责任公司 | Flow sensor based on MEMS, flow velocity measuring circuit and method |
| CN109141559A (en) * | 2018-08-29 | 2019-01-04 | 杭州电子科技大学 | A kind of wide range bimodulus thermal sensation bridge-type micro-flowmeter |
| CN110764031A (en) * | 2019-11-14 | 2020-02-07 | 中国原子能科学研究院 | Heating and RF Integrated Assembly for Optically Pumped Magnetometers |
| CN113029265A (en) * | 2021-02-09 | 2021-06-25 | 青岛芯笙微纳电子科技有限公司 | Vacuum heat-insulation MEMS flow sensor and manufacturing method thereof |
-
2008
- 2008-09-24 CN CNA2008102117419A patent/CN101408442A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102128655A (en) * | 2010-12-08 | 2011-07-20 | 苏州谷之道软件科技有限公司 | Automotive hot film air flow micro-electromechanical systems (MEMS) sensor with primary and secondary double cavity structure |
| CN106092234A (en) * | 2016-06-02 | 2016-11-09 | 苏州容启传感器科技有限公司 | Hollow out heat membrane type flow sensor with rectifier structure and preparation method thereof |
| CN106092234B (en) * | 2016-06-02 | 2019-05-10 | 苏州容启传感器科技有限公司 | Hollow out heat membrane type flow sensor with rectifier structure and preparation method thereof |
| CN107643421A (en) * | 2017-11-10 | 2018-01-30 | 苏州原位芯片科技有限责任公司 | Flow sensor based on MEMS, flow velocity measuring circuit and method |
| CN109141559A (en) * | 2018-08-29 | 2019-01-04 | 杭州电子科技大学 | A kind of wide range bimodulus thermal sensation bridge-type micro-flowmeter |
| CN110764031A (en) * | 2019-11-14 | 2020-02-07 | 中国原子能科学研究院 | Heating and RF Integrated Assembly for Optically Pumped Magnetometers |
| CN113029265A (en) * | 2021-02-09 | 2021-06-25 | 青岛芯笙微纳电子科技有限公司 | Vacuum heat-insulation MEMS flow sensor and manufacturing method thereof |
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Legal Events
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| C06 | Publication | ||
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| DD01 | Delivery of document by public notice |
Addressee: Hu Haiping Document name: Notification of before Expiration of Request of Examination as to Substance |
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| DD01 | Delivery of document by public notice |
Addressee: Beijing Shidai Lantian Optoelectronic Technology Co., Ltd. Document name: Notification that Application Deemed to be Withdrawn |
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| C02 | Deemed withdrawal of patent application after publication (patent law 2001) | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20090415 |