CN205067412U - Poroid electrode parallel -plate capacitive moisture sensor of going up of miniature quick response - Google Patents

Poroid electrode parallel -plate capacitive moisture sensor of going up of miniature quick response Download PDF

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Publication number
CN205067412U
CN205067412U CN201520417725.0U CN201520417725U CN205067412U CN 205067412 U CN205067412 U CN 205067412U CN 201520417725 U CN201520417725 U CN 201520417725U CN 205067412 U CN205067412 U CN 205067412U
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China
Prior art keywords
electrode
humidity
top electrode
poroid
sensitive film
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CN201520417725.0U
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Chinese (zh)
Inventor
周文和
王良璧
李耀亮
许凤
李建霞
王良成
何炫
成红娟
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Lanzhou Jiaotong University
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Lanzhou Jiaotong University
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Abstract

The utility model discloses a poroid electrode parallel -plate capacitive moisture sensor of going up of miniature quick response is poroid from top to bottom respectively and goes up electrode, PI humidity -sensitive film, dull and stereotyped bottom electrode, siO2 insulating layer and si basement, wherein, goes up the last electrode hole that the electrode was equipped with a plurality of marshallings, is equipped with 2 lower electrode lead holes on the PI humidity -sensitive film. During the preparation, at first rinse the silicon chip, the silicon chip oxidation forms the insulating layer, the coating by vaporization bottom electrode, and sour, the imineization of bottom electrode coating polyimide, the poroid figure phosphoric acid sculpture of electrode is gone up to electrode on the coating by vaporization, uses phosphoric acid sculpture electrode, plasma etching humidity -sensitive film to form the scribing way, uses the plasma etching humidity -sensitive film to form electrode lead hole down, section at last, argon welding, encapsulation. The beneficial effects of the utility model are that under the same condition, poroid upward electrode dew cell is gone up the electrode with the bars form and is compared, and response time can obtain maximum improvement.

Description

A kind of miniature quick response poroid top electrode parallel plate capacitor formula humidity-sensitive element
Technical field
The utility model belongs to moisture measurement and control technology field, relates to a kind of miniature quick response poroid top electrode parallel plate capacitor formula humidity-sensitive element.
Background technology
Moisture measurement and control closely correlate to social life, industrial and agricultural production etc.Some field, as respiratory disease diagnosis and treatment, fuel cell car etc., not only needs humidity-sensitive element to have the static characteristicss such as accurate, reliable, also requires that humidity-sensitive element can the transient changing of response measurement ambient humidity fast.The static characteristics of existing humidity-sensitive element is relatively better, but the dynamic perfromance of its marketable product unsatisfactory (usual tens seconds).
Now widely used palisade top electrode parallel plate capacitor formula humidity-sensitive element is many based on Si substrate and polyimide humidity-sensitive film (PI), polyimide (PI) macromolecule humidity-sensitive film is porous medium, can adsorbed gas, and specific inductive capacity is less, and the specific inductive capacity of aqueous vapor molecule is larger, when after aqueous vapor molecule in humidity-sensitive film absorption soft air, humidity-sensitive film DIELECTRIC CONSTANT ε sremarkable linear change, and correspond to the different concentration of humidity-sensitive film absorption aqueous vapor molecule.When ambient humidity becomes large suddenly, due to the reason of aqueous vapor molecular conecentration difference in environment and humidity-sensitive film, in environmental gas, aqueous vapor molecule enters humidity-sensitive film surface from the grid backlash of palisade top electrode, then the humidity-sensitive film region that top electrode grid tooth covers longitudinally is diffused to downwards with horizontal left and right, spread faster, the humidity-sensitive element response time is shorter.Can find out, under the same terms, palisade top electrode grid tooth narrower (overlay area is narrower) and humidity-sensitive film thinner, water vapor diffusion distance is shorter, then water vapor diffusion is faster, and the humidity-sensitive element response time is shorter; Vice versa.
In order to strengthen structure and the even charge distribution of palisade top electrode, palisade top electrode must arrange current-sharing bar, and current-sharing bar width is much larger than palisade top electrode grid facewidth degree, and area accounts for palisade top electrode total area 30%-40%.The existence of current-sharing bar adds the distance of water vapor diffusion, makes the effect improving humidity-sensitive element dynamic response time by pursuing too small palisade top electrode grid facewidth degree can not be obvious.So, the existence of palisade top electrode current-sharing bar constrains the further improvement of humidity-sensitive element dynamic response time.
Utility model content
The purpose of this utility model is to provide a kind of miniature quick response poroid top electrode parallel plate capacitor formula humidity-sensitive element, without the need to current-sharing bar, solve existing palisade top electrode parallel plate capacitor formula humidity-sensitive element must arrange account for top electrode total area significant proportion, wider top electrode current-sharing bar causes water vapor diffusion path long, making to improve the effect of humidity-sensitive element response time by reducing palisade top electrode grid tooth width method can not obvious problem.
The technical scheme that the utility model adopts is respectively poroid top electrode, PI humidity-sensitive film, dull and stereotyped bottom electrode, SiO from top to bottom 2insulation course and Si substrate, wherein, top electrode is provided with the top electrode hole of some marshallings, and PI humidity-sensitive film is provided with 2 bottom electrode fairleads.
Further, silicon chip is selected in described Si substrate, and described top electrode and bottom electrode are Mo-Al electrode.
Further, the aperture in described top electrode hole is 2 μm, and top electrode Kong Jian center minimum spacing is 4 μm.
Further, PI humidity-sensitive film thickness is 0.54 μm.
The beneficial effects of the utility model adopt poroid top electrode to substitute existing humidity-sensitive element palisade top electrode, without the need to upper electrode arrangement strengthening and the current-sharing bar of even charge distribution effect, make the diffusion path approximately equal of the aqueous vapor molecule being entered humidity-sensitive film by each hole of top electrode, and can reduce with the minimizing of pitch of holes, under the same terms, poroid top electrode humidity-sensitive element is compared with palisade top electrode humidity-sensitive element, and the response time can farthest be improved.
Accompanying drawing explanation
Fig. 1 poroid top electrode parallel plate capacitor formula humidity-sensitive element planimetric map;
Fig. 2 poroid top electrode parallel plate capacitor formula humidity-sensitive element structural representation;
Fig. 3 poroid top electrode parallel plate capacitor formula humidity-sensitive element fabrication processing figure;
Fig. 4 poroid top electrode parallel plate capacitor formula humidity-sensitive element top electrode pitch-row schematic diagram;
The poroid top electrode of Fig. 5 and palisade top electrode humidity-sensitive element dynamic perfromance comparison diagram.
Embodiment
Below in conjunction with embodiment, the utility model is described in detail.
The utility model poroid top electrode parallel plate capacitor formula humidity-sensitive element as depicted in figs. 1 and 2, is respectively poroid top electrode 2, PI humidity-sensitive film 4, dull and stereotyped bottom electrode 6, SiO from top to bottom 2insulation course 7 and Si substrate 8, Si substrate 8 can select silicon chip, top electrode 2 and bottom electrode 6 are Mo-Al electrode, wherein, poroid top electrode 2 is provided with the top electrode hole 3 of some marshallings, and the aperture in top electrode hole 3 is preferably 2 μm, and 3, top electrode hole center minimum spacing is preferably 4 μm, by 2 bottom electrode fairleads 5 that etching PI humidity-sensitive film 4 is formed, go between for argon welding bottom electrode.In the utility model, PI humidity-sensitive film 4 is applied through sol evenning machine silicon chip by the acid of pre-configured polyimide, then is formed through imidization, and its thickness obtains by controlling polyimide acid concentration, coating consumption and sol evenning machine rotations per minute, and preferred thickness is 0.54 μm.Adopt Mo-Al combination electrode to be the weldability being strengthened contact conductor by the molybdenum (Mo) that adhesiveness is stronger in the utility model, the use of aluminium electrode reduces humidity-sensitive element cost, and adds its life-span.When ambient humidity raises, aqueous vapor molecule 1 diffuses into PI humidity-sensitive film 4 through top electrode hole 3, and when ambient humidity reduces, aqueous vapor molecule 1 diffuses into environment from PI humidity-sensitive film 4 through top electrode hole 3.
The manufacture craft of the utility model parallel plate capacitor formula humidity-sensitive element as shown in Figure 3, first cleaning silicon chip, silicon chip forms insulation course, evaporation bottom electrode, the acid of bottom electrode coating polyimide, imidization, evaporation top electrode, the poroid figure phosphoric acid etching of top electrode, etch electrode by phosphoric acid, plasma etching humidity-sensitive film forms dicing lane, plasma etching PI humidity-sensitive film forms bottom electrode fairlead, finally section, argon welding, encapsulation.
The poroid top electrode of the utility model avoids palisade top electrode and considers the current-sharing bar that area ratio is large, width is wide that the narrow easy fracture of grid tooth and even charge distribute and arrange, each hole is made to enter the water diffusion path of humidity-sensitive film equal, under the prerequisite not increasing cost and process complexity, effectively can improve the response time of humidity-sensitive element.
A kind of poroid top electrode parallel plate capacitor formula humidity-sensitive element of the utility model, area 3mm × 3mm, top electrode active region area 2mm × 2mm, pitch-row as shown in Figure 4, its median pore diameter 2 μm, hole center distance S1=S2=4 μm, top electrode area 2.5mm 2; Through verification experimental verification, under all the other the same terms, the dynamic response time of the utility model poroid top electrode parallel plate capacitor formula humidity-sensitive element improves at least 30% than existing palisade top electrode parallel plate capacitor formula humidity-sensitive element.
Fig. 5 shows existing palisade top electrode humidity-sensitive element (area 3mm × 3mm, top electrode active region area 2mm × 2mm, wherein grid facewidth degree 2 μm, grid backlash width 2 μm, top electrode area 2.5mm 2, current-sharing bar width 50 μm, accounts for top electrode area ratio 40%) and the utility model humidity-sensitive element dynamic perfromance compare, wherein, it is 33.2%RH (MgCl that the dynamic Characteristic Data of palisade top electrode humidity-sensitive element derives from 25 DEG C from relative humidity 2saturated salt solution) to wet response test result to the relative humidity liter that is 75.8%RH (NaCl saturated salt solution), dynamic characteristic test is based on saturated salt solution method, equilibration time is 5s, test duration is less than 10s, the dynamic Characteristic Data of poroid top electrode humidity-sensitive element derives from numerical simulation, in figure, ordinate is dimensionless capacitance, and horizontal ordinate is the time.
As seen from Figure 5, the response time of poroid top electrode humidity-sensitive element is obviously better than palisade top electrode humidity-sensitive element, especially later stage.
The above is only to better embodiment of the present utility model, not any pro forma restriction is done to the utility model, every any simple modification above embodiment done according to technical spirit of the present utility model, equivalent variations and modification, all belong in the scope of technical solutions of the utility model.

Claims (4)

1. a miniature quick response poroid top electrode parallel plate capacitor formula humidity-sensitive element, is characterized in that: be respectively poroid top electrode, PI humidity-sensitive film, dull and stereotyped bottom electrode, SiO from top to bottom 2insulation course and Si substrate, wherein, top electrode is provided with the top electrode hole of some marshallings, and PI humidity-sensitive film is provided with 2 bottom electrode fairleads.
2., according to a kind of miniature quick response poroid top electrode parallel plate capacitor formula humidity-sensitive element described in claim 1, it is characterized in that: silicon chip is selected in described Si substrate, described top electrode and bottom electrode are Mo-Al electrode.
3., according to a kind of miniature quick response poroid top electrode parallel plate capacitor formula humidity-sensitive element described in claim 1, it is characterized in that: the aperture in described top electrode hole is 2 μm, top electrode Kong Jian center minimum spacing is 4 μm.
4., according to a kind of miniature quick response poroid top electrode parallel plate capacitor formula humidity-sensitive element described in claim 1, it is characterized in that: PI humidity-sensitive film thickness is 0.54 μm.
CN201520417725.0U 2015-06-15 2015-06-15 Poroid electrode parallel -plate capacitive moisture sensor of going up of miniature quick response Expired - Fee Related CN205067412U (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104931546A (en) * 2015-06-15 2015-09-23 兰州交通大学 Rapid responding miniature capacitance type humidity-sensitive element with porous upper electrode and parallel board electrode
CN110494744A (en) * 2017-03-31 2019-11-22 三美电机株式会社 Humidity sensor

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104931546A (en) * 2015-06-15 2015-09-23 兰州交通大学 Rapid responding miniature capacitance type humidity-sensitive element with porous upper electrode and parallel board electrode
CN110494744A (en) * 2017-03-31 2019-11-22 三美电机株式会社 Humidity sensor

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CF01 Termination of patent right due to non-payment of annual fee
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Granted publication date: 20160302

Termination date: 20210615