CN1210565C - Miniature humidity sensor - Google Patents
Miniature humidity sensor Download PDFInfo
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- CN1210565C CN1210565C CN 03131859 CN03131859A CN1210565C CN 1210565 C CN1210565 C CN 1210565C CN 03131859 CN03131859 CN 03131859 CN 03131859 A CN03131859 A CN 03131859A CN 1210565 C CN1210565 C CN 1210565C
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Abstract
The present invention relates to a miniature humidity sensor used for humidity signal sensing. The present invention is composed of a substrate, an oxidizing layer and a capacitor electrode, wherein the oxidizing layer is arranged on the substrate; the capacitor electrode is arranged above the oxidizing layer; a contact conductor is arranged on the capacitor electrode; the capacitor electrode is an electrode with the materials which are suitable for the standard CMOS processing technology; humidity sensing dielectric layers are arranged above the capacitor electrode and in the capacitor electrode; a silicon dioxide bar is arranged between the capacitor electrode and the oxidizing layer; a heating bar is arranged among the humidity sensing dielectric layers and the oxidizing layer; a heating bar leading wire is arranged on the heating bar. The present invention uses a parallel structure in an aluminum electrode comb shape, so a sensitive capacitance value is increased, the outside interference is eliminated, and the accuracy of the humidity sensor is improved. Polyimide is used as a humidity sensing medium, so the present invention has the advantages of high sensitivity, high linearity, good hysteresis loop performance, long-term reliability, etc.
Description
One, technical field
The present invention relates to a kind of micro mechanical sensor, relate in particular to a kind of miniature humidity sensor.
Two, background technology
Practical application mostly is traditional humidity sensor in the environment measuring at present, as dry bulb thermometer, dew-point hygrometer etc.There are following several shortcomings in these humidity sensors: the consistance of (1) like products is poor; (2) cost an arm and a leg; (3) volume is big; (4) linearity, hysteretic characteristic are poor, need sometimes in the measurement to table look-up.The electric capacity relative humidity sensor compatible mutually with CMOS (CMOS is a technical term well known in the art) technology is a kind of little humidity sensor, has that volume is little, price is low, the advantage of good product consistency.Nineteen ninety, H.Baltes (name) has proposed to utilize CMOS technology to make humidity sensor the earliest.This humidity sensor utilizes air as humidity-sensitive medium, since the influence of surface adsorption, all non-constant of the linearity and hysteretic characteristic, and precision is very low.And because the aluminium electrodes exposed is subjected to the corrosion of aqueous vapor easily in air, reliability is also poor.1991, Boltshauser (name) adopts the CMOS technology to add post-order process, utilize polyimide to make relative capacitive humidity sensor for humidity-sensitive medium, the electrode of this humidity sensor directly contacts polyimide absorption steam with polyimide can corrode the aluminium electrode afterwards, reliability is low, and long-term the use makes the attached impurity in surface be difficult to remove.2000, Uksong Kang (name) provided a kind of humidity sensor of high speed, and it is heat insulation to be used as the silicon dioxide and one deck sensitive electrode that have two-layer conduct to insulate on the polysilicon of heating in this structure, the heating weak effect; This structure more complicated can't be finished by the CMOS technology of standard.And electrodes exposed is in air, and for preventing the corrosion of water in air vapour, the selection of electrode is just restricted, and long-term reliability is poor.Some above humidity sensors can not satisfy long-term reliability and the short requirement of desorption time, are subject to the external environment influence.
Three, technology contents
Technical matters: the invention provides a kind of high-precision micro humidity sensor that can improve its reliability.
Technical scheme: the present invention is a kind of miniature humidity sensor that is used for the moisture signal sensing, by substrate 106, oxide layer 104, capacitance electrode 101 and 102 is formed, oxide layer 104 is located on the substrate 106, capacitance electrode 101 and 102 is located at oxide layer 104 tops, on capacitance electrode 101 and 102, be provided with contact conductor 1011 and 1021, this capacitance electrode 101 and 102 is suitable for the electrode of standard CMOS processing technology for its material, above capacitance electrode 101 and 102, reach and be provided with humidity-sensitive medium layer 107 therebetween, capacitance electrode 101 and 102 and oxide layer 104 between be provided with titanium dioxide silicon strip 105, between humidity-sensitive medium layer 107 and oxide layer 104, be provided with fire-bar 103, on fire-bar 103, be provided with fire-bar lead-in wire 1031 and 1032.
Technique effect: processing step of the present invention is simple, can utilize the CMOS technology manufacturing of standard, the precision height, and long-term reliability is good.Adopt aluminium electrode pectination parallel-connection structure can increase the sensitization capacitance value, the substrate reliable ground has been eliminated extraneous interference, improve the precision of humidity sensor.The deposit passivation layer can effectively prevent steam in the environment especially after the polyimide suction, and the vapour corrosion aluminium electrode in the polyimide has improved reliability.Utilize pectination polysilicon in parallel as heater circuit, homogeneous heating is effectively removed humidity sensor surface volatile impurity, makes the desorption time of humidity sensor shorter, has improved reliability equally.Polyimide is set, and the upper surface of oxidation bar is higher than the upper surface of polycrystalline bar, the edge effectiveness of minimizing aluminium electrode and silicon dioxide interlayer, the raising linearity, minimizing stray capacitance, thereby raising precision between capacitance electrode.Utilize polyimide as humidity-sensitive medium, it has highly sensitive, and the linearity, hysteretic characteristic are good, wait advantage reliably and with long-term, and structure setting of the present invention then makes it compatible mutually with the standard CMOS processing technology.
Four, description of drawings
Fig. 1 is a structural representation of the present invention.
Fig. 2 is a vertical view of the present invention.
Fig. 3 is a comb poles structural representation of the present invention.
Fig. 4 is a comb shape formula of the present invention polysilicon layer structural representation in parallel.Between the lower surface 1071 of humidity-sensitive medium layer 107 and oxide layer 104, be provided with fire-bar 103,
Five, specific embodiments
The present invention is a kind of miniature humidity sensor that is used for the moisture signal sensing, by substrate 106, oxide layer 104, capacitance electrode 101 and 102 is formed, oxide layer 104 is located on the substrate 106, capacitance electrode 101 and 102 is located at oxide layer 104 tops, on capacitance electrode 101 and 102, be provided with contact conductor 1011 and 1021, this capacitance electrode 101 and 102 is suitable for the electrode of standard CMOS processing technology for its material, above capacitance electrode 101 and 102, reach and be provided with humidity-sensitive medium layer 107 therebetween, humidity-sensitive medium layer 107 is a polyimide layer, capacitance electrode 101 and 102 and oxide layer 104 between be provided with titanium dioxide silicon strip 105, and the upper surface of titanium dioxide silicon strip 105 is higher than the lower surface 1071 of humidity-sensitive medium layer 107, between humidity-sensitive medium layer 107 and oxide layer 104, be provided with fire-bar 103, specifically, both fire-bar 103 can be located between the lower surface 1071 and oxide layer 104 of humidity-sensitive medium layer 107, also fire-bar 103 can be located between titanium dioxide silicon strip 105 and the oxide layer 104, on fire-bar 103, be provided with fire-bar lead-in wire 1031 and 1032, capacitance electrode 101 and 102 and humidity-sensitive medium layer 107 between be provided with passivation layer 108, between humidity-sensitive medium layer 107 and fire-bar 103, be provided with passivation layer 1081, the passivation layer 108 of present embodiment is a silicon nitride layer, this passivation layer 108 also can be made up of silicon dioxide layer and silicon nitride layer, silicon nitride layer is located at the top of silicon dioxide layer, capacitance electrode 101 and 102 is the aluminium electrode, capacitance electrode 101 and 102 can also be gold electrode or polysilicon electrode, capacitance electrode 101 and 102 is comb poles and is crisscross arranged, fire-bar 103 is a comb shape polysilicon layer in parallel, substrate 106 ground connection.Humidity-sensitive medium of the present invention is by the relative humidity variations of external environment, the airborne aqueous vapor molecule of absorption/desorption, make the specific inductive capacity of humidity-sensitive medium change, cause that the capacitance of humidity sensor changes, exist between relative humidity and the sensitization capacitance and determine relation.The humidity sensor capacitance increased when envionmental humidity raise, the corresponding minimizing of humidity sensor capacitance when envionmental humidity reduces, the humidity sensor output terminal connects peripheral circuit, the sensitization capacitance value is translated into through interface circuit can survey electric signal (as voltage, electric current), the present invention can adopt following technology to make: growth thin oxide layer 104 on silicon substrate, deposit polysilicon 103, and be photo-etched into the S type of pectination parallel connection, CVD method deposit silica 1 05, polysilicon 103 is exposed in photoetching, 1 micron aluminium of deposit, and be photo-etched into comb electrode 101,102 (carving the aluminium that removes on the polysilicon).Then deposit 108 is as passivation layer, and the photoetching passivation layer utilizes whirl coating to be coated with polyimide (107) about 1.5 micron thickness, and the thickness of polyimide after photoetching, the imidization (107) is about 1 micron.The pectination that the two-plate of humidity sensor (is example with the aluminium electrode), aluminum electrode plate bar shaped aluminium electrode wide 3 microns by 21 respectively, long 400 microns is formed, adjacent polar plate spacing is 4 microns.Heating polysilicon structure such as Fig. 2, polysilicon 203 adopts pectination S type in parallel structure, is beneficial to even heating, and every polysilicon strip (103) length is 450 microns, wide 3 microns, thickness is 3500 dusts, 14 polysilicon strips are connected in parallel respectively, series connection then, and all-in resistance is about 1.5K Ω, silicon nitride thickness as passivation layer 108 is 3000 dusts, in order to the aqueous vapor corrosion that prevents that aluminium electrode 101,102 from being adsorbed by polyimide 107, the thickness of polyimide 107 is about 1 micron.Aluminium electrode 109 ground connection are used for eliminating the influence of outer bound pair sensitization capacitance, and polysilicon strip is a heater circuit, aluminium electrode 101,102 output capacitance signals.The envionmental humidity measurement range is 0%RH~100%RH, and temperature range is-40 ℃~60 ℃.
Claims (5)
1, a kind of miniature humidity sensor that is used for the moisture signal sensing, by substrate (106), oxide layer (104), capacitance electrode (101,102) form, oxide layer (104) is located on the substrate (106), capacitance electrode (101,102) be located at oxide layer (104) top, at capacitance electrode (101,102) be provided with contact conductor (1011,1021), this capacitance electrode (101,102) be suitable for the electrode of standard CMOS processing technology for its material, it is characterized in that at capacitance electrode (101,102) top reaches and is provided with humidity-sensitive medium layer (107) therebetween, at capacitance electrode (101,102) and be provided with titanium dioxide silicon strip (105) between the oxide layer (104), between humidity-sensitive medium layer (107) and oxide layer (104), be provided with fire-bar (103), on fire-bar (103), be provided with fire-bar lead-in wire (1031,1032), capacitance electrode (101,102) be comb poles and being crisscross arranged, fire-bar (103) is a comb shape polysilicon layer in parallel, between humidity-sensitive medium layer (107) and fire-bar (103), be provided with passivation layer (1081), between capacitance electrode (101,102) and humidity-sensitive medium layer (107), be provided with passivation layer (108), substrate (106) ground connection, humidity-sensitive medium layer (107) is a polyimide layer.
2, miniature humidity sensor according to claim 1 is characterized in that passivation layer (108) is a silicon nitride layer.
3, miniature humidity sensor according to claim 1 is characterized in that passivation layer (108) by silicon dioxide layer, and silicon nitride layer is formed, and silicon nitride layer is located at the top of silicon dioxide layer.
4, miniature humidity sensor according to claim 1 is characterized in that capacitance electrode (101,102) is the aluminium electrode.
5, miniature humidity sensor according to claim 1 is characterized in that the upper surface of titanium dioxide silicon strip (105) is higher than the lower surface (1071) of humidity-sensitive medium layer (107).
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CN 03131859 CN1210565C (en) | 2003-06-12 | 2003-06-12 | Miniature humidity sensor |
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CN 03131859 CN1210565C (en) | 2003-06-12 | 2003-06-12 | Miniature humidity sensor |
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CN1210565C true CN1210565C (en) | 2005-07-13 |
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Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102243199A (en) * | 2011-04-20 | 2011-11-16 | 东南大学 | Relative humidity sensor of fast-response microelectronic mechanical system |
EP3062097A1 (en) * | 2015-02-27 | 2016-08-31 | EM Microelectronic-Marin SA | Moisture sensor with thermal module |
CN105158305A (en) * | 2015-10-23 | 2015-12-16 | 上海集成电路研发中心有限公司 | Method for manufacturing humidity sensor compatible with CMOS process |
CN105502282B (en) * | 2015-11-30 | 2017-05-31 | 上海集成电路研发中心有限公司 | A kind of manufacture method of MEMS humidity sensors |
US10336606B2 (en) * | 2016-02-25 | 2019-07-02 | Nxp Usa, Inc. | Integrated capacitive humidity sensor |
CN108489541B (en) * | 2018-03-21 | 2020-11-03 | 北京中硕众联智能电子科技有限公司 | Artificial skin and method for detecting pressure, temperature and humidity thereof |
CN108709585B (en) * | 2018-03-21 | 2020-12-29 | 北京中硕众联智能电子科技有限公司 | Artificial skin and method for detecting pressure, temperature and humidity and adjusting temperature of artificial skin |
CN110346423B (en) * | 2019-07-02 | 2021-05-04 | 杭州未名信科科技有限公司 | CMOS-MEMS humidity sensor |
CN113311031B (en) * | 2021-07-01 | 2024-08-13 | 北京航天微电科技有限公司 | Double-sided capacitive humidity sensor and preparation method thereof |
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