CN103675041A - Multi-range interdigital capacitive humidity sensor - Google Patents
Multi-range interdigital capacitive humidity sensor Download PDFInfo
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- CN103675041A CN103675041A CN201310633521.6A CN201310633521A CN103675041A CN 103675041 A CN103675041 A CN 103675041A CN 201310633521 A CN201310633521 A CN 201310633521A CN 103675041 A CN103675041 A CN 103675041A
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Abstract
The invention relates to a multi-range interdigital capacitive humidity sensor which is characterized by comprising a plurality of connected sensor units, wherein each sensor unit comprises a pair of upper and lower interdigital electrodes; the lower electrodes and the upper electrodes penetrate through a SiO2 oxide layer and are arranged on the same surface of a silicon substrate; the interdigital parts of the upper electrodes and the interdigital parts of the lower electrodes are staggered in an interdigital shape; humidity-sensitive mediums are filled between the interdigital parts of the upper electrodes and the lower electrodes; aluminum strips are arranged above the upper electrodes and the lower electrodes and positioned between the interdigital parts of the upper electrodes and the lower electrodes; humidity-sensitive mediums are filled between the aluminum strips and the upper electrodes; a cavity is formed in the silicon substrate under the upper electrodes and the lower electrodes, so that the lower electrodes, the upper electrodes and the humidity-sensitive mediums between the interdigital parts of the lower electrodes and the upper electrodes directly make contact with air; the sensor units are connected in series through the aluminum strips. According to the multi-range interdigital capacitive humidity sensor, the sensitivity of a capacitive pressure sensor is improved and the measurement range of the capacitive pressure sensor is increased.
Description
Technical field
The present invention relates to a kind of multirange interdigital capacitor formula humidity sensor, especially a kind of multirange and with the capacitance type humidity sensor of CMOS process compatible, belong to MEMS device design and manufacturing technology field.
Background technology
Moisture measurement is a main application aspect of MEMS technology, and the detection of humidity and control technology have obtained widespread use.Such as military affairs, meteorology, agricultural, industry (particularly weaving, electronics, food), medical treatment, the aspects such as building and household electrical appliance need to strictly be monitored humidity, some occasion even needs humidity control and report to the police, such as air handling system, and greenhouse control system, warehouse monitoring system.To humidity detection, the needs of control have promoted the progress to humidity sensor.
Capacitive monolithic Integrated Humidity Sensor adopts aluminium interdigital structure, and interdigital structure humidity sensor capacitance type humidity sensor is a kind of multirange main Types of the micro-humidity sensor of silicon, and its ultimate principle is that humidity is changed to the variation that is converted to electric capacity.At interdigited capacitor and above resistor stripe, cover one deck humidity-sensitive medium layer-polyimide, relative humidity in external environment changes, the airborne vapour molecule of wet sensory material absorption/desorption, changes the specific inductive capacity of polyimide, thereby causes the change of interdigital capacitor value.Humicap value reduces.By capacitive detection circuit, just capacitance can be converted into voltage or current signal is exported.
The preparation of tradition humidity sensor all adopts MEMS Bulk micro machining, complex process, and processing cost is expensive, and is difficult to realize standardization.Conventional condenser pressure sensor chip major defect: (1) cannot make itself and CMOS process compatible, the CMOS technique of sensor chip is integrated is the trend of sensor research and development; (2) single range, can only test for a certain specific range ability, and it can not be used to greatest extent.
Summary of the invention
The object of the invention is to overcome the deficiencies in the prior art, a kind of multirange interdigital capacitor formula humidity sensor is provided, this transducer sensitivity is high, and range ability is large, and has improved manufacturability, low cost of manufacture.
According to technical scheme provided by the invention, described multirange interdigital capacitor formula humidity sensor, it is characterized in that: comprise a plurality of sensor units that link together, described sensor unit comprises top electrode and the bottom electrode of a pair of interdigitated, bottom electrode and top electrode are through SiO
2oxide layer is arranged on the same surface of silicon base, and the interdigital interdigitated that is of the interdigital and bottom electrode of top electrode is staggered, and between top electrode and bottom electrode interdigital, fills humidity sensitive medium; Above described top electrode and bottom electrode, aluminum strip is set, aluminum strip, between top electrode and bottom electrode interdigital, is filled humidity sensitive medium between aluminum strip and top electrode; In silicon base under described top electrode and bottom electrode, form cavity, the humidity sensitive medium of interdigital of bottom electrode, top electrode and bottom electrode and top electrode is directly contacted with air; Described sensor unit is cascaded by aluminum strip.
Described top electrode and bottom electrode comprise respectively two metal layers, between two metal layers, by tungsten plug, are connected.
Described top electrode and bottom electrode adopt metallic aluminium.
Described humidity sensitive medium is polyimide.
Described each sensor unit is connected to silicon base upper surface by press welding block respectively.
The interdigital area of described each sensor unit is different.
The invention has the beneficial effects as follows: rapidly, highly sensitive, output area is wide, high temperature resistant in sensor response of the present invention, and humidity hysteresis error is little, and temperature characterisitic and long-time stability are good; The present invention and CMOS technique are completely compatible, and utilize circuit technology processing formerly, aftertreatment technology after mode, guaranteed the integrality of CMOS technique and not being changed and interrupting of process sequences, be easy to realize the microminiaturized and intelligent of mass manufacture and sensor; The present invention has improved sensitivity and the measurement range of capacitance pressure transducer,, adopted six pressure transducers of different membrane areas to carry out the tonometric mode of segmentation, thereby by a sensor array, improve measurement range, made up the deficiency of single-sensor measurement range.
Accompanying drawing explanation
Fig. 1 is the vertical view of humidity sensor of the present invention.
Fig. 2 is the vertical view of sensor unit of the present invention.
Fig. 3 is the cut-open view of sensor unit of the present invention.
Sequence number in figure is: bottom electrode 1, top electrode 2, aluminum strip 3, humidity sensitive medium 7, silicon base 8, cavity 9, SiO
2oxide layer 10, press welding block 11, sensor unit 12, tungsten plug 13.
Embodiment
Below in conjunction with concrete accompanying drawing, the invention will be further described.
As shown in Figure 1, described multirange interdigital capacitor formula humidity sensor comprises six sensor units that link together 12; As shown in Figure 2 and Figure 3, described sensor unit 12 comprises top electrode 2 and the bottom electrode 1 of a pair of interdigitated, and bottom electrode 1 and top electrode 2 are through SiO
2oxide layer 10 is arranged on the same surface of silicon base 8, and the interdigital interdigitated that is of the interdigital and bottom electrode 1 of top electrode 2 is staggered, and between top electrode 2 and bottom electrode 1 interdigital, fills humidity sensitive medium 7; Above described top electrode 2 and bottom electrode 1, aluminum strip 3 is set, aluminum strip 3, between top electrode 2 and bottom electrode 1 interdigital, is filled humidity sensitive medium 7 between aluminum strip 3 and top electrode 2; In silicon base 8 under described top electrode 2 and bottom electrode 1, form cavity 9, the humidity sensitive medium 7 of bottom electrode 1, top electrode 2 and bottom electrode 1 and interdigital of top electrode 2 can directly contact with air; Described sensor unit 12 is cascaded by aluminum strip 3, and aluminum strip 3 can play the effect of accelerating dehumidification to the humidity sensitive medium 7 of interdigital of top electrode 2, bottom electrode 1;
As shown in Figure 3, described top electrode 2 and bottom electrode 1 comprise respectively two metal layers, between two metal layers, by tungsten plug 13, are connected;
Described top electrode 2 and bottom electrode 1 adopt metallic aluminium; Described humidity sensitive medium 7 is polyimide;
Described each sensor unit 12 is connected to silicon base 8 upper surfaces by press welding block 11 respectively, and the interdigital area of each sensor unit 12, quantity are different, can be respectively used to the moisture measurement of different range.
The method of preparing above-mentioned multirange interdigital capacitor formula humidity sensor, adopts following processing step:
(1) one deck SiO that grows in silicon base 8
2form SiO
2oxide layer 10, at SiO
2splash-proofing sputtering metal aluminium in oxide layer 10, and etching forms the first metal layer 14;
(2) adopt spin-coating method spin coating one deck polyimide, and etching filling tungsten plug 13, tungsten plug 13 is positioned on the first metal layer 14;
(3) splash-proofing sputtering metal aluminium, and be etched on the first metal layer 14 and form the second metal level 15, top electrode 2 and bottom electrode 1 obtained;
(4) adopt to carve painting method spin coating one deck polyimide, then splash-proofing sputtering metal aluminium, and etching forms aluminum strip 3 again, and aluminum strip 3 is between top electrode 2 and bottom electrode 1 interdigital;
(5) in the back side of silicon base 8 deposit one deck silicon nitride barrier, and etch corrosion window on 8 at the bottom of at the bottom of silicon, then utilize the anisotropic etch of silicon from the back side of silicon base 8 to SiO
2oxide layer 10 direction corrosion, the etchant solution of selecting is to SiO
2the corrosion rate of oxide layer 10 is the corrosion rate to silicon base 8 much smaller than this etchant solution, when silicon base 8 erodes to SiO
2during oxide layer 10 lower surface, first step corrosion finishes; Second step corrosion is by SiO
2oxide layer 10 is corroded to the lower surface of bottom electrode 1; After two step etch completes, in the silicon base 8 of bottom electrode 1 bottom, form cavity 9, and the humidity sensitive medium of interdigital of bottom electrode 1 and bottom electrode 1 can contact with air;
(6) last again by the silicon nitride barrier removal at 8 back sides at the bottom of silicon.
Multirange interdigital capacitor formula humidity sensor of the present invention is on the basis of conventional condenser pressure sensor chip structure, the capacitance type humidity sensor of employing based on standard CMOS technique also realized the set of a plurality of cell capacitance sensors, formed wide range capacitance pressure transducer, array, it has many-sided advantage, CMOS technology is the mainstream technology that current IC manufactures on the one hand, its process technology advanced person and ripe, codes and standards, once the device of developing success, can be mass; And CMOS MEMS is easily integrated by MEMS device and circuit monolithic; The present invention has adopted the capacitive pressure transducer unit of a plurality of different sizes to realize multirange on the other hand, and utilizes circuit technology processing formerly, aftertreatment technology after mode, guaranteed the integrality of CMOS technique and not being changed and interrupting of process sequences; And there is larger measurement range, higher sensitivity, lower temperature drift coefficient, firmer structure and lower power consumption etc.
When work, thereby the moisture in environment is changed two electric contrasted between solid dielectric specific inductive capacity by the humidity-sensitive medium absorption/desorption between two electrodes, produce corresponding capacitance variation, capacitance is along with humidity changes monotone variation, capacitance is mutually corresponding with humidity value, forms by humidity the sensing translation function to electric capacity.In a certain humidity situation, operative sensor unit is saturated, and that operative sensor unit is out of shape under this pressure condition is very little, now select suitable sensor unit as measuring unit, to realize certain sensitivity, adopting the sensor of design in this way can select between measurement range and sensitivity, has realized the intellectuality of sensor.
Claims (6)
1. a multirange interdigital capacitor formula humidity sensor, it is characterized in that: comprise a plurality of sensor units that link together (12), described sensor unit (12) comprises top electrode (2) and the bottom electrode (1) of a pair of interdigitated, and bottom electrode (1) and top electrode (2) are through SiO
2oxide layer (10) is arranged on the same surface of silicon base (8), and the interdigital interdigitated that is of the interdigital and bottom electrode (1) of top electrode (2) is staggered, and between top electrode (2) and bottom electrode (1) interdigital, fills humidity sensitive medium (7); Top at described top electrode (2) and bottom electrode (1) arranges aluminum strip (3), and aluminum strip (3) is positioned between top electrode (2) and bottom electrode (1) interdigital, between aluminum strip (3) and top electrode (2), fills humidity sensitive medium (7); The upper cavity (9) that forms of silicon base (8) under described top electrode (2) and bottom electrode (1), directly contacts the humidity sensitive medium (7) of bottom electrode (1), top electrode (2) and bottom electrode (1) and interdigital of top electrode (2) with air; Described sensor unit (12) is cascaded by aluminum strip (3).
2. multirange interdigital capacitor formula humidity sensor as claimed in claim 1, is characterized in that: described top electrode (2) and bottom electrode (1) comprise respectively two metal layers, between two metal layers, by tungsten plug (13), is connected.
3. multirange interdigital capacitor formula humidity sensor as claimed in claim 1, is characterized in that: described top electrode (2) and bottom electrode (1) adopt metallic aluminium.
4. multirange interdigital capacitor formula humidity sensor as claimed in claim 1, is characterized in that: described humidity sensitive medium (7) is polyimide.
5. multirange interdigital capacitor formula humidity sensor as claimed in claim 1, is characterized in that: described each sensor unit (12) is connected to silicon base (8) upper surface by press welding block (11) respectively.
6. multirange interdigital capacitor formula humidity sensor as claimed in claim 1, is characterized in that: the interdigital area of described each sensor unit (12) is different.
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Cited By (3)
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| CN104391015A (en) * | 2014-12-03 | 2015-03-04 | 东南大学 | Capacitive humidity sensor of integrated ultrasonic structure and preparation method of capacitive humidity sensor of integrated ultrasonic structure |
| CN105366626A (en) * | 2015-10-21 | 2016-03-02 | 苏州工业园区纳米产业技术研究院有限公司 | MEMS capacitance type humidity sensor and manufacturing method thereof |
| CN106247920A (en) * | 2016-07-07 | 2016-12-21 | 中国计量大学 | A kind of surface strain based on the sandwich interdigital capacitor of elastic substrates detection device |
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Application publication date: 20140326 |