WO2023165144A1 - 无漂移湿度传感器及校准方法 - Google Patents

无漂移湿度传感器及校准方法 Download PDF

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WO2023165144A1
WO2023165144A1 PCT/CN2022/126889 CN2022126889W WO2023165144A1 WO 2023165144 A1 WO2023165144 A1 WO 2023165144A1 CN 2022126889 W CN2022126889 W CN 2022126889W WO 2023165144 A1 WO2023165144 A1 WO 2023165144A1
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moisture
sensitive material
humidity sensor
humidity
sensor unit
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PCT/CN2022/126889
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English (en)
French (fr)
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於广军
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上海申矽凌微电子科技股份有限公司
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Priority claimed from CN202210197835.5A external-priority patent/CN114705725A/zh
Priority claimed from CN202210196787.8A external-priority patent/CN114705724A/zh
Application filed by 上海申矽凌微电子科技股份有限公司 filed Critical 上海申矽凌微电子科技股份有限公司
Priority to US18/284,556 priority Critical patent/US20240175833A1/en
Publication of WO2023165144A1 publication Critical patent/WO2023165144A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/048—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance for determining moisture content of the material
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/045—Circuits
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G01N27/223—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance for determining moisture content, e.g. humidity
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G01N27/223—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance for determining moisture content, e.g. humidity
    • G01N27/225—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance for determining moisture content, e.g. humidity by using hygroscopic materials
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G01N27/226—Construction of measuring vessels; Electrodes therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G01N27/228—Circuits therefor

Definitions

  • the invention relates to the technical field of humidity sensors, in particular to a drift-free humidity sensor and a calibration method.
  • Humidity sensors are widely used in indoor temperature and humidity monitoring, smart home, white goods, security, agriculture and many other fields, playing a huge role.
  • the realization principle of the humidity sensor includes resistive type, capacitive type, mass weighing type, wet and dry bulb type, etc. Due to the advantages of capacitive and resistive humidity sensors, which are easy to be compatible with CMOS processes, have good linearity, and a wide humidity range (0-100% RH), the temperature and humidity sensor chips use these two implementation methods, and the capacitive type is the most widely used.
  • the US9696272B2 patent proposes a method of adjusting the sampling frequency to improve the drift characteristics; the US4793175 patent proposes the use of inorganic substances as humidity-sensitive materials to resist drift; at the same time, there are also a large number of documents that propose improved polymer structures to improve this a question.
  • the object of the present invention is to provide a drift-free humidity sensor and a calibration method.
  • a drift-free humidity sensor provided according to the present invention includes: a first humidity sensor unit, a second humidity sensor unit, and an analysis and processing unit, the first humidity sensor unit includes a first measurement electrode, and a humidity sensor covering the first measurement electrode.
  • the first humidity-sensitive material on the second humidity sensor unit includes a second measurement electrode, and the second humidity-sensitive material covered on the second measurement electrode, the first humidity sensor unit and the second humidity sensor unit.
  • the maximum humidity drifts of the humidity sensor units are different, and the analysis and processing unit corrects and outputs the measured values of the first humidity sensor unit and the second humidity sensor unit.
  • the first measurement electrode includes a first measurement positive electrode and a first measurement negative electrode, and interdigital electrodes are arranged on the first measurement positive electrode and the first measurement negative electrode;
  • the second measuring electrode is composed of a second measuring positive pole and a second measuring negative pole, and interdigitated electrodes are arranged on the second measuring positive pole and the second measuring negative pole,
  • the interdigitated electrodes are arranged in a staggered manner.
  • first measuring electrode and the second measuring electrode are capacitive electrodes; or, the first measuring electrode and the second measuring electrode are resistive electrodes.
  • first measuring electrode and the second measuring electrode are capacitive electrodes, a passivation layer is provided between one side of the first measuring electrode and the first moisture-sensitive material, and the first measuring electrode A dielectric layer and a substrate silicon wafer are sequentially arranged on the other surface of the first measuring electrode and the substrate silicon wafer, and the dielectric layer is filled between the first measuring electrode and the substrate silicon wafer;
  • a passivation layer is provided between one side of the second measuring electrode and the second moisture-sensitive material, and a dielectric layer and a substrate silicon wafer are sequentially arranged on the other two surfaces of the second measuring electrode, and the dielectric layer is filled in the first 2 between the measuring electrode and the substrate silicon wafer.
  • the first measuring electrode and the second measuring electrode are resistive electrodes
  • the first humidity-sensitive material is arranged on one side of the first measuring electrode
  • the other surface of the first measuring electrode is arranged in sequence a dielectric layer and a substrate silicon wafer, and the dielectric layer is filled between the first measuring electrode and the substrate silicon wafer;
  • the second humidity-sensitive material is arranged on one side of the second measuring electrode, and the other side of the second measuring electrode is provided with a dielectric layer and a substrate silicon chip in sequence, and the dielectric layer is filled between the second measuring electrode and the substrate silicon wafer. between slices.
  • the first moisture-sensitive material and the second moisture-sensitive material are photosensitive moisture-sensitive materials or non-photosensitive moisture-sensitive materials
  • the first moisture-sensitive material and the second moisture-sensitive material Processing methods include:
  • the pattern is obtained by direct photolithography
  • the processing method includes:
  • Step S1.1 Spin-coat a non-photosensitive moisture-sensitive material on the passivation layer of the first measurement electrode and the second measurement electrode and cure it, then spin-coat a photoresist on the non-photosensitive moisture-sensitive material, and photolithography The required pattern is then processed by dry etching, and finally the photoresist is removed to complete the processing of a moisture-sensitive material;
  • Step S1.2 Spin-coat the photosensitive moisture-sensitive material, pattern it by photolithography, and cure the photosensitive moisture-sensitive material to obtain another moisture-sensitive material;
  • the processing method includes:
  • Step S2.1 Spin-coat the first moisture-sensitive material on the passivation layer of the two measuring electrodes and cure it, and the thickness of the first moisture-sensitive material is more than twice the sum of the width and margin of the interdigital electrodes, Then spin-coat photoresist on the first photosensitive moisture-sensitive material, and photoetch out the required pattern, then process through the process of dry etching, finally remove the photoresist, and complete the processing of the first moisture-sensitive material;
  • Step S2.2 Spin-coat the second moisture-sensitive material and cure it, then spin-coat photoresist on the second moisture-sensitive material, and photoetch the desired pattern, and process it by dry etching to keep the first
  • the second moisture-sensitive material attached to the moisture-sensitive material is finally removed to complete the processing of the second moisture-sensitive material.
  • the first moisture-sensitive material and the second moisture-sensitive material are photosensitive moisture-sensitive materials; or any one of the first moisture-sensitive material and the second moisture-sensitive material is non-photosensitive sexual moisture-sensitive material, another kind is photosensitive moisture-sensitive material;
  • the processing method of described first moisture-sensitive material and described second moisture-sensitive material comprises:
  • the pattern is obtained by direct photolithography
  • the processing method is:
  • Step S3.1 Spin-coat a non-photosensitive moisture-sensitive material on the first measuring electrode and the second measuring electrode and cure it, then spin-coat a photoresist on the non-photosensitive moisture-sensitive material, and photoetch the desired pattern, Then process through dry etching, and finally remove the photoresist to complete the processing of a moisture-sensitive material;
  • Step S3.2 Spin-coat the photosensitive moisture-sensitive material, pattern it by photolithography, and cure the photosensitive moisture-sensitive material to obtain another moisture-sensitive material;
  • the processing method includes:
  • Step S4.1 Spin-coat the first non-photosensitive moisture-sensitive material on the first measurement electrode and the second measurement electrode and cure, then spin-coat photoresist on the non-photosensitive moisture-sensitive material, and photoetch out the required Graphics, and then processed by dry etching, and finally remove the photoresist to complete the processing of a moisture-sensitive material;
  • Step S4.2 Spin-coat the second non-photosensitive moisture-sensitive material, then spin-coat the photoresist, pattern it by photolithography, and then use alkaline developer (TMAH) to etch the photoresist while developing
  • TMAH alkaline developer
  • the second non-photosensitive material is used to cure the second moisture-sensitive material after removing the photoresist to obtain another moisture-sensitive material
  • the humidity sensor adopts a differential sampling structure, wherein the first humidity sensor unit includes a first sensing subunit and a second sensing subunit, and the second humidity sensor unit includes a third sensing subunit unit and the fourth sensing subunit.
  • Step S1 Obtain the relationship between the maximum humidity drift characteristics of the first humidity sensor unit and the second humidity sensor unit and the ambient humidity, and calculate the maximum drift difference between the first humidity sensor unit and the second humidity sensor unit;
  • Step S2 performing regression fitting on the humidity sensitive capacitance value or humidity sensitive resistance value of the first humidity sensor unit and the second humidity sensor unit and the measured RH value to obtain a first fitting equation and a second fitting equation;
  • Step S3 Obtain the humidity values of the first humidity sensor unit and the second humidity sensor unit under a certain humidity environment, and calculate the actual humidity difference between the first humidity sensor unit and the second humidity sensor unit, and compare the actual humidity difference with the maximum Drift difference analogy;
  • Step S4 making an analogy between the actual humidity difference between the first humidity sensor unit and the second humidity sensor unit, the relationship between the maximum drift characteristic of the first humidity sensor unit and the ambient humidity, and the relationship between the maximum humidity drift characteristic of the second humidity sensor unit and the ambient humidity, Obtain the humidity drift of the first humidity sensor unit and the humidity drift of the second humidity sensor unit under the current humidity environment;
  • Step S5 According to the first fitting equation and the second fitting equation, and the humidity drift of the first humidity sensor unit and the humidity drift of the second humidity sensor unit in step S4, respectively establish equations about the real humidity value RH ;
  • Step S6 According to the equation of the real humidity value RH in step S5, establish the second-order equation of the first humidity sensor unit about RH and the second-order equation of the second humidity sensor unit about RH;
  • Step S7 According to the difference of the second-order equation of the first humidity sensor unit with respect to RH and the second-order equation of the second humidity sensor unit with respect to RH, the weights are respectively applied to complete the calibration process.
  • the maximum drift of the first humidity sensor unit and the second humidity sensor unit is obtained through an 85° C. 85% RH test, or through a 120° C. 100% RH HAST test.
  • the weight is assigned according to 1:1; when the difference If the value exceeds the set value, the sensing unit with higher confidence is selected as the main sensing unit and assigned a higher weight.
  • FIG. 1 is a schematic diagram of interdigital capacitance in a humidity sensor according to one embodiment of the present invention
  • Fig. 2 is a schematic cross-sectional view of a moisture-sensitive material in a humidity sensor according to an embodiment of the present invention
  • FIG. 3 is a sectional view of the first humidity sensor unit of the capacitive sensor according to one embodiment of the present invention.
  • FIG. 4 is a sectional view of a second humidity sensor unit of a capacitive sensor according to one embodiment of the present invention.
  • Figure 5 is a cross-sectional view of the first humidity sensor unit when two kinds of non-photosensitive moisture-sensitive materials are used in one of the embodiments of the present invention
  • FIG. 6 is a cross-sectional view of a resistive sensor in one embodiment of the present invention.
  • FIG. 7 is a schematic diagram of interdigital capacitance of a humidity sensor with a differential sampling structure according to one embodiment of the present invention.
  • FIG. 8 is a flowchart of a humidity sensor calibration method according to one embodiment of the present invention.
  • the first measuring electrode 101 The second measuring electrode 102
  • the first measurement positive electrode 1011 The second measurement positive electrode 1021
  • the first measurement negative pole 1012 The second measurement negative pole 1022
  • the first moisture sensitive material 201 The second moisture sensitive material 202
  • the first sensing subunit 111 The second sensing subunit 112
  • the third sensing subunit 113 The fourth sensing subunit 114
  • Planar humidity sensors including capacitive humidity sensors and resistive humidity sensors, generally set interdigitated structures on silicon wafers or ASIC chips, and then coat a layer of humidity-sensitive material on the interdigital electrodes to realize the detection of humidity-sensitive capacitance .
  • the back-end circuit detection is generally divided into single-ended structure and differential structure.
  • the single-ended structure samples a single electrode
  • the differential structure samples two symmetrical electrodes.
  • a drift-free humidity sensor comprising: a first humidity sensor unit, a second humidity sensor unit and an analysis and processing unit, the first humidity sensor unit includes The first measuring electrode 101, and the first humidity sensitive material 201 covered on the first measuring electrode 101, the second humidity sensor unit includes the second measuring electrode 102, and the first humidity sensitive material 201 covering the second measuring electrode 102
  • Two humidity-sensitive materials 202, the maximum humidity drift of the first humidity sensor unit and the second humidity sensor unit are different, and the analysis and processing unit corrects the measured values of the first humidity sensor unit and the second humidity sensor unit and output.
  • the first measuring electrode 101 includes a first measuring positive pole 1011 and a first measuring negative pole 1012, and interdigital electrodes 212 are arranged on the first measuring positive pole 1011 and the first measuring negative pole 1012;
  • the second measuring electrode 102 is composed of a second measuring positive pole 1021 and a second measuring negative pole 1022, and an interdigital electrode 212 is arranged on the second measuring positive pole 1021 and the second measuring negative pole 1022, so The interdigital electrodes 212 are arranged in a staggered manner.
  • the first measuring electrode 101 and the second measuring electrode 102 are capacitive electrodes; or, the first measuring electrode 101 and the second measuring electrode 102 are resistive electrodes.
  • a passivation layer 211 is arranged between one side of the first measurement electrode 101 and the first moisture-sensitive material 201, and a dielectric layer 213 and a substrate silicon wafer 214 are arranged in sequence on the other side of the first measurement electrode 101, and the dielectric The layer 213 is filled between the first measurement electrode 101 and the substrate silicon wafer 214 .
  • a passivation layer 211 is arranged between one side of the second measurement electrode 102 and the second moisture-sensitive material 202, and a dielectric layer 213 and a substrate silicon wafer 214 are sequentially arranged on the other two sides of the second measurement electrode 102. , and the dielectric layer 213 is filled between the second measurement electrode 102 and the substrate silicon wafer 214 .
  • the first moisture-sensitive material 201 and the second moisture-sensitive material 202 are photosensitive moisture-sensitive materials or non-photosensitive moisture-sensitive materials, and the processing methods of the first moisture-sensitive material 201 and the second moisture-sensitive material 202 are according to The difference in materials is divided into the following situations:
  • the pattern is obtained by direct photolithography
  • the processing method includes:
  • Step S1.1 Spin-coat a non-photosensitive moisture-sensitive material on the passivation layer 211 of the first measurement electrode 101 and the second measurement electrode 102 and cure it, then spin-coat a photoresist on the non-photosensitive moisture-sensitive material, and Photolithographically produce the required pattern, then process it through dry etching process, and finally remove the photoresist to complete the processing of a moisture-sensitive material;
  • Step S1.2 Spin-coat the photosensitive moisture-sensitive material, pattern it by photolithography, and cure the photosensitive moisture-sensitive material to obtain another moisture-sensitive material;
  • the processing method includes:
  • Step S2.1 Spin-coat the first moisture-sensitive material 201 on the passivation layer 211 of the two measuring electrodes and cure, then spin-coat photoresist on the first photosensitive moisture-sensitive material, and photoetch out the required Graphics, and then processed by dry etching, and finally remove the photoresist, and complete the processing of the first moisture-sensitive material 201;
  • Step S2.2 Spin-coat the second moisture-sensitive material 202 and cure it, then spin-coat photoresist on the second photosensitive moisture-sensitive material, and photoetch out the required pattern, and process it by dry etching, The second photosensitive moisture-sensitive material attached to the first photosensitive moisture-sensitive material is retained, and finally the photoresist is removed to complete the processing of the second moisture-sensitive material 202 .
  • the problem will become complicated, and the method for processing the first moisture-sensitive material 201 remains unchanged, but if the dry method is also adopted Etching processes the second moisture sensitive material 202, so because dry etching does not have any selectivity for the first moisture sensitive material 201 and the second moisture sensitive material 202, cause the second moisture sensitive material in the area outside the second humidity sensor unit to be removed At 202, the thickness loss of the first humidity sensitive material 201 in the first humidity sensor unit area also occurs due to over-etching. However, inevitably, we do not necessarily need to remove the second moisture-sensitive material 202 on the first moisture-sensitive material 201 . Referring to FIG.
  • the second humidity-sensitive material 202 may remain on the first sensing unit, so that conflicts in process integration are greatly reduced. But this scheme needs to guarantee a premise, the thickness of the first moisture-sensitive material 201 will be greater than the sum of the aluminum strip line width and side spacing of interdigital electrode 212 more than 1 time, the electric field line of capacitor will not have or only have pole like this A small amount will pass through the second moisture-sensitive material 202 , as shown in FIG. 5 , reducing the crosstalk between the first moisture-sensitive material 201 and the second moisture-sensitive material 202 .
  • the resistive electrode will be described in detail below.
  • described first moisture-sensitive material 201 is arranged on one side of first measurement electrode 101, and the other side of described first measurement electrode 101 is provided with dielectric layer 213 and substrate silicon chip 214 successively, and dielectric layer 213 It is filled between the first measurement electrode 101 and the substrate silicon wafer 214 .
  • the second moisture-sensitive material 202 is arranged on one side of the second measuring electrode 102, and the other side of the second measuring electrode 102 is provided with a dielectric layer 213 and a substrate silicon wafer 214 in sequence, and the dielectric layer 213 is filled in the second Between the measurement electrode 102 and the substrate silicon wafer 214 .
  • the first moisture-sensitive material 201 and the second moisture-sensitive material 202 are photosensitive moisture-sensitive materials; or any one of the first moisture-sensitive material 201 and the second moisture-sensitive material 202 is a non-photosensitive moisture-sensitive material , the other is a photosensitive moisture-sensitive material; the processing methods of the first moisture-sensitive material 201 and the second moisture-sensitive material 202 include:
  • the pattern is obtained by direct photolithography
  • the processing method is:
  • Step S3.1 Spin-coat the non-photosensitive moisture-sensitive material on the first measuring electrode 101 and the second measuring electrode 102 and cure it, then spin-coat photoresist on the non-photosensitive moisture-sensitive material, and photoetch out the required Graphics, and then processed by dry etching, and finally remove the photoresist to complete the processing of a moisture-sensitive material;
  • Step S3.2 Spin-coat the photosensitive moisture-sensitive material, pattern it by photolithography, and cure the photosensitive moisture-sensitive material to obtain another moisture-sensitive material;
  • the processing method includes:
  • Step S4.1 Spin-coat the first non-photosensitive moisture-sensitive material on the first measurement electrode 101 and the second measurement electrode 102 and cure it, then spin-coat photoresist on the non-photosensitive moisture-sensitive material, and photoetch out The required pattern is then processed by dry etching, and finally the photoresist is removed to complete the processing of a moisture-sensitive material;
  • Step S4.2 Spin-coat the second non-photosensitive moisture-sensitive material, then spin-coat photoresist, pattern it by photolithography, and then use alkaline developer (TMAH) to etch the photoresist while developing
  • TMAH alkaline developer
  • the second non-photosensitive material is used to cure the second moisture-sensitive material after removing the photoresist to obtain another moisture-sensitive material
  • the first moisture-sensitive material and the second moisture-sensitive material are stacked on the interdigital electrode at the same time, the first moisture-sensitive layer and the second moisture-sensitive layer will form a parallel relationship, and the measured humidity-sensitive resistance will be the first
  • the first humidity-sensitive material and the second humidity-sensitive material cannot both be used Non-photosensitive moisture sensitive material.
  • the capacitive electrodes since the crossing height of the electric field lines is limited, it is allowed to stack the first moisture-sensitive material and the second moisture-sensitive material. At this time, it is satisfied that the thickness of the first humidity-sensitive material 201 is more than 1 times the sum of the aluminum strip line width and side spacing of the interdigital electrodes 212 .
  • the above is a solution for a humidity sensor with a single-ended structure. If the ASIC circuit adopts a differential sampling structure, the first humidity sensor unit and the second humidity sensor unit at the sensor device end also need to be designed in the form of a differential pair. Referring to Fig.
  • the subunit 111 includes a first subunit anode 1111 and a first subunit anode 1112;
  • the second sensing subunit 112 includes a second subunit anode 1121 and a second subunit anode 1122;
  • the third sensing subunit 113 includes a third subunit The subunit anode 1131 and the third subunit anode 1132 ;
  • the fourth sensing subunit 114 includes a fourth subunit anode 1141 and a fourth subunit anode 1142 .
  • the first humidity sensor unit and the second humidity sensor unit required by one or more embodiments of the present invention can be obtained by combining any two sensing subunits.
  • the first humidity sensor unit is composed of the first sensing subunit 111 and the fourth sensing subunit 114
  • the second humidity sensor unit is composed of the second sensing subunit 112 Combined with the third sensing subunit 113.
  • the subsequent application of moisture-sensitive materials it is consistent with the previous scheme.
  • One embodiment of the present invention discloses a humidity sensor calibration method.
  • the analysis and processing unit receives the results measured by the first humidity sensor unit and the second humidity sensor unit, it performs error calculation on the two results, and finally generates an accurate humidity value. value, the specific calibration process refers to Figure 8, including the following steps:
  • Step S1 Obtain the relationship between the maximum humidity drift characteristics of the first humidity sensor unit and the second humidity sensor unit and the ambient humidity, and calculate the maximum drift difference between the first humidity sensor unit and the second humidity sensor unit.
  • the relationship between the maximum humidity drift characteristics of the first humidity sensor unit and the second humidity sensor unit and the environmental humidity is studied respectively.
  • the general regression relationship can be expressed by the first-order equation about the environmental humidity. As shown in formulas 1 and 2.
  • the maximum drift can be accelerated aging for a certain period of time, such as 85 °C 85% RH test, or HAST test, so that the drift of the sensor can be stabilized.
  • the humidity drift value is small at low humidity
  • the drift value is medium at medium humidity
  • the drift value is the largest at high humidity, showing a correlation with the humidity of the current test environment.
  • Some polymeric materials also exhibit good linear drift over the full humidity range, ie zero first order term.
  • RH_Drift max_A ⁇ RH+a (1)
  • ⁇ RH_Drift max ( ⁇ - ⁇ )RH+(ba) (3)
  • Step S2 Perform regression fitting on the capacitance values of the first humidity sensor unit and the second humidity sensor unit and the measured RH value to obtain a first fitting equation and a second fitting equation.
  • the first humidity sensor unit and the second humidity sensor unit are calibrated to establish a corresponding relationship of "environmental humidity—humidity capacitance or humidity resistance—ADC digital quantity—reading humidity value".
  • the second-order fitting can meet the accuracy requirements of most sensors, as shown in equations 4 and 5; of course, according to the design capabilities of digital circuits or the requirements of sensor devices, regression fitting such as third-order or above can be used.
  • the first humidity sensor unit and the second humidity sensor unit will be able to independently measure their respective humidity values.
  • Step S3 Obtain the humidity values of the first humidity sensor unit and the second humidity sensor unit under a certain humidity environment, and calculate the actual humidity difference between the first humidity sensor unit and the second humidity sensor unit, and compare the actual humidity difference with the maximum Drift difference analog.
  • the first humidity sensor unit and the second humidity sensor unit When in a certain ambient humidity RH, the first humidity sensor unit and the second humidity sensor unit will read two humidity values of RH A and RH B respectively, at this time we get the difference between the two, as shown in formula 6 :
  • Step S4 making an analogy between the actual humidity difference between the first humidity sensor unit and the second humidity sensor unit, the relationship between the maximum drift characteristic of the first humidity sensor unit and the ambient humidity, and the relationship between the maximum humidity drift characteristic of the second humidity sensor unit and the ambient humidity, The humidity drift of the first humidity sensor unit and the humidity drift of the second humidity sensor unit in the current humidity environment are obtained.
  • Equation 6 Comparing Equation 6 with Equation 1 or Equation 2, we can obtain the humidity drift of sensing units A and B under the current humidity environment, as shown in Equations 7 and 8, respectively.
  • Step S5 According to the first fitting equation and the second fitting equation, and the humidity drift of the first humidity sensor unit and the humidity drift of the second humidity sensor unit in step S4, respectively establish equations about the real humidity value RH .
  • equations about the real humidity value RH can be established, as shown in formulas 9 and 10.
  • Step S6 According to the equation of the real humidity value RH in step S5, a second-order equation of the first humidity sensor unit with respect to RH and a second-order equation of the second humidity sensor unit with respect to RH are established.
  • Equation 9 and Equation 10 the second-order equation about RH can be obtained, and the two equations can obtain the value about the real RH, as shown in Equations 11 and 12.
  • the drift rates of sensing unit A and sensing unit B are equivalent, then the RH values obtained by sensing unit A and B should be equal, and any value can be taken.
  • it is difficult to have such an ideal situation in reality such as individual differences of the same material, differences in drift rates of different materials, etc., need to increase discrimination to increase the credibility of the data.
  • RH_real A f A (RH A ,RH B ) (11)
  • RH_real B f B (RH A ,RH B ) (12)
  • Step S7 According to the difference of the second-order equation of the first humidity sensor unit with respect to RH and the second-order equation of the second humidity sensor unit with respect to RH, the weights are respectively applied to complete the calibration process.
  • ⁇ and ⁇ can be 0.5; when the difference between the two When the value exceeds the set threshold, the sensing unit with higher confidence is taken as the main sensing unit and assigned a higher weight; in this way, we can finally get a humidity sensor with no drift in the whole life cycle.
  • the present invention has the following beneficial effects:
  • the humidity sensor of the present invention can effectively solve the problem of drift of general capacitive humidity sensors or resistive humidity sensors;
  • the calibration method of the present invention compensates and corrects the actual measured values of the first humidity sensor unit and the second humidity sensor unit, thereby realizing drift-free humidity measurement, and the implementation cost of this solution is relatively low.

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Abstract

一种无漂移湿度传感器及校准方法，该湿度传感器包括：第一湿度传感器单元和第二湿度传感器单元，第一湿度传感器单元包括第一测量电极（101），第一测量电极（101）上覆盖有第一湿敏材料（201），第二湿度传感器单元包括第二测量电极（102），第二测量电极（102）上覆盖有第二湿敏材料（202），第一湿度传感器单元和第二湿度传感器单元的最大湿度漂移不同。该湿度传感器能够有效解决一般的电容式湿度传感器或电阻式湿度传感器漂移的问题。

Description

无漂移湿度传感器及校准方法 技术领域
本发明涉及湿度传感器技术领域，具体地，涉及一种无漂移湿度传感器及校准方法。
背景技术
湿度传感器广泛应用在室内温湿度监控，智能家居，白色家电，安防，农业等诸多领域，发挥了巨大作用。湿度传感器的实现原理有电阻式，电容式，质量称量式，干湿球式等。由于电容式和电阻式湿度传感器易于CMOS工艺兼容，线性度好，湿度量程宽(0-100％RH)等优势，因此温湿度传感器芯片多用这两种实现方式，其中电容式使用最广泛。
然而采用聚合物作为湿敏材料的传感器，不论其采用电容式，电阻式，或者是压敏式等，由于聚合物的固有特性，必然会形成化学吸附水汽，且难以脱附，产生湿度漂移，尤其是高温高湿环境下，聚合物的长链空间位置膨胀，其湿度漂移特性更加明显。
为了解决湿度传感器的漂移特性，US9696272B2专利提出调节采样频率的方法来改善漂移特性；US4793175专利提出采用无机物作为湿敏材料的方案，抵抗漂移；同时也有大量文献提出改进的聚合物结构来改善这一问题。
发明内容
针对现有技术中的缺陷，本发明的目的是提供一种无漂移湿度传感器及校准方法。
根据本发明提供的一种无漂移湿度传感器，包括：第一湿度传感器单元、第二湿度传感器单元以及分析处理单元，所述第一湿度传感器单元包括第一测量电极，以及覆盖在第一测量电极上的第一湿敏材料，所述第二湿度传感器单元包括第二测量电极，以及覆盖在所述第二测量电极上的第二湿敏材料，所述第一湿度传感器单元和所述第二湿度传感器单元的最大湿度漂移不同，所述分析处理单元对第一湿度传感器单元和第二湿 度传感器单元的测量值进行校正并输出。
进一步地，所述第一测量电极包括第一测量正极和第一测量负极，所述第一测量正极和第一测量负极上均设置有叉指电极；
所述第二测量电极由第二测量正极和第二测量负极组合而成，所述第二测量正极和第二测量负极上均设置有叉指电极，
所述叉指电极呈交错设置。
进一步地，所述第一测量电极和所述第二测量电极为电容型电极；或者，所述第一测量电极和所述第二测量电极为电阻型电极。
进一步地，所述第一测量电极和所述第二测量电极为电容型电极，在所述第一测量电极的一面与第一湿敏材料之间设置有钝化层，所述第一测量电极的另一面上依次设置有介质层和衬底硅片，且介质层填充在第一测量电极与衬底硅片之间；
所述第二测量电极的一面与第二湿敏材料之间设置有钝化层，所述第二测量电极的另二面上依次设置有介质层和衬底硅片，且介质层填充在第二测量电极与衬底硅片之间。
进一步地，所述第一测量电极和所述第二测量电极为电阻型电极，所述第一湿敏材料设置在第一测量电极的一面，所述第一测量电极的另一面上依次设置有介质层和衬底硅片，且介质层填充在第一测量电极与衬底硅片之间；
所述第二湿敏材料设置在第二测量电极的一面，所述第二测量电极的另一面上依次设置有介质层和衬底硅片，且介质层填充在第二测量电极与衬底硅片之间。
进一步地，针对电容式电极，所述第一湿敏材料和第二湿敏材料为光敏性湿敏材料或非光敏性湿敏材料，所述第一湿敏材料和所述第二湿敏材料的加工方法包括：
-若第一湿敏材料和第二湿敏材料均为光敏性湿敏材料，采用直接光刻的方式得到图形；
-若第一湿敏材料或第二湿敏材料中的一个为非光敏湿敏材料，加工方法包括：
步骤S1.1：在第一测量电极和第二测量电极的钝化层上旋涂非光敏湿敏材料并固化，然后在非光敏性湿敏材料上旋涂光刻胶，并光刻出所需的图形，再通过干法蚀刻的工艺加工，最后去除光刻胶，完成一种湿敏材料的加工；
步骤S1.2：旋涂光敏性湿敏材料，通过光刻的方式图形化，并固化光敏性湿敏材料，得到另一种湿敏材料；
-若第一湿敏材料和第二湿敏材料均为非光敏性湿敏材料，加工方法包括：
步骤S2.1：在两个测量电极的钝化层上旋涂第一湿敏材料并固化，且所述第一湿敏 材料的厚度大于一倍以上叉指电极的宽度和边距之和，然后在第一光敏性湿敏材料上旋涂光刻胶，并光刻出所需的图形，再通过干法蚀刻的工艺加工，最后去除光刻胶，完成第一湿敏材料的加工；
步骤S2.2：旋涂第二湿敏材料并固化，然后在第二湿敏材料上旋涂光刻胶，并光刻出所需的图形，在通过干法蚀刻的工艺加工，保留第一湿敏材料上附着的第二湿敏材料，最后去除光刻胶，完成第二湿敏材料的加工。
进一步地，针对电阻式电极，所述第一湿敏材料和第二湿敏材料为光敏性湿敏材料；或所述第一湿敏材料和第二湿敏材料中的任意一种为非光敏性湿敏材料，另一种为光敏性湿敏材料；所述第一湿敏材料和所述第二湿敏材料的加工方法包括：
-若第一湿敏材料和第二湿敏材料均为光敏性湿敏材料，采用直接光刻的方式得到图形；
-若第一湿敏材料或第二湿敏材料中的一个为非光敏湿敏材料，加工方法为：
步骤S3.1：在第一测量电极和第二测量电极上旋涂非光敏湿敏材料并固化，然后在非光敏性湿敏材料上旋涂光刻胶，并光刻出所需的图形，再通过干法蚀刻的工艺加工，最后去除光刻胶，完成一种湿敏材料的加工；
步骤S3.2：旋涂光敏性湿敏材料，通过光刻的方式图形化，并固化光敏性湿敏材料，得到另一种湿敏材料；
-若第一湿敏材料和第二湿敏材料均为非光敏性湿敏材料，加工方法包括：
步骤S4.1：在第一测量电极和第二测量电极上旋涂第一非光敏湿敏材料并固化，然后在非光敏性湿敏材料上旋涂光刻胶，并光刻出所需的图形，再通过干法蚀刻的工艺加工，最后去除光刻胶，完成一种湿敏材料的加工；
步骤S4.2：旋涂第二非光敏性湿敏材料，然后再旋涂光刻胶，通过光刻的方式图形化，接着利用碱性显影液(TMAH)在光刻胶显影的同时，腐蚀第二非光敏性材料，去除光刻胶后对第二湿敏材料固化，得到另一种湿敏材料；
进一步地，所述湿度传感器采用差分式采样结构，其中，所述第一湿度传感器单元包括第一传感子单元和第二传感子单元，所述第二湿度传感器单元包括第三传感子单元和第四传感子单元。
根据本发明一个或多个实施例提供的一种湿度传感器的校准方法，包括以下步骤：
步骤S1：获取第一湿度传感器单元和第二湿度传感器单元的湿度最大漂移特性与环境湿度的关系，计算第一湿度传感器单元和第二湿度传感器单元的最大漂移差值；
步骤S2：将第一湿度传感器单元和第二湿度传感器单元的湿敏电容值或湿敏电阻值与实测RH值进行回归拟合，得到第一拟合方程和第二拟合方程；
步骤S3：获取某一湿度环境下，第一湿度传感器单元和第二湿度传感器单元的湿度值，并计算第一湿度传感器单元和第二湿度传感器单元的实际湿度差，并将实际湿度差与最大漂移差值类比；
步骤S4：将第一湿度传感器单元和第二湿度传感器单元的实际湿度差与第一湿度传感器单元最大漂移特性与环境湿度的关系以及第二湿度传感器单元湿度最大漂移特性与环境湿度的关系类比，得到当前湿度环境下第一湿度传感器单元的湿度漂移量，以及第二湿度传感器单元的湿度漂移量；
步骤S5：根据第一拟合方程和第二拟合方程，以及步骤S4中的第一湿度传感器单元的湿度漂移量，第二湿度传感器单元的湿度漂移量，分别建立关于真实湿度值RH的方程；
步骤S6：根据步骤S5中的真实湿度值RH的方程，建立第一湿度传感器单元关于RH的二阶方程以及第二湿度传感器单元关于RH的二阶方程；
步骤S7：根据第一湿度传感器单元关于RH的二阶方程以及第二湿度传感器单元关于RH的二阶方程的差值分别权重，完成校正流程。
进一步地，所述第一湿度传感器单元和第二湿度传感器单元的最大漂移通过85℃85％RH试验，或者通过120℃100％RH的HAST试验进行获取。
进一步地，所述步骤S7中，当第一湿度传感器单元关于RH的二阶方程以及第二湿度传感器单元关于RH的二阶方程的差值小于设定值，按照1:1分配权重；当差值超过设定值，取其中置信度更高的传感单元作为主传感单元，分配更高的权重。
附图说明
通过阅读参照以下附图对非限制性实施例所作的详细描述，本发明的其它特征、目的和优点将会变得更明显：
图1为本发明其中一个实施例的湿度传感器中叉指电容示意图；
图2为本发明其中一个实施例的湿度传感器中湿敏材料截面示意图；
图3为本发明其中一个实施例的电容式传感器第一湿度传感器单元剖视图；
图4为本发明其中一个实施例的电容式传感器第二湿度传感器单元剖视图；
图5为本发明其中一个实施例的中采用两种非光敏性湿敏材料时第一湿度传感 器单元的剖视图；
图6为本发明其中一个实施例的中电阻式传感器的剖视图；
图7为本发明其中一个实施例的差分式采样结构湿度传感器叉指电容示意图；
图8为本发明其中一个实施例的湿度传感器校准方法流程图。
附图标记说明：
第一测量电极101                               第二测量电极102
第一测量正极1011                              第二测量正极1021
第一测量负极1012                              第二测量负极1022
第一湿敏材料201                               第二湿敏材料202
钝化层211                                     介质层213
叉指电极212                                   衬底硅片214
第一传感子单元111                             第二传感子单元112
第三传感子单元113                             第四传感子单元114
第一子单元正极1111                            第一子单元负极1112
第二子单元正极1121                            第二子单元负极1122
第三子单元正极1131                            第三子单元负极1132
第四子单元正极1141                            第四子单元负极1142
具体实施方式
下面结合具体实施例对本发明进行详细说明。以下实施例将有助于本领域的技术人员进一步理解本发明，但不以任何形式限制本发明。应当指出的是，对本领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干变化和改进。这些都属于本发明的保护范围。
平面式湿度传感器，包括电容式湿度传感器和电阻式湿度传感器，一般在硅片或者ASIC晶片上设置叉指结构，接着在叉指电极上涂敷一层湿敏材料，进而实现湿敏电容的检测。而后端的电路检测一般分为单端结构和差分结构，单端结构采样的是单个电极，差分结构采样的是两个对称的电极。
本发明的一个或多个实施例公开一种无漂移湿度传感器，参照图1和图2，包括：第一湿度传感器单元、第二湿度传感器单元以及分析处理单元，所述第一湿度传感器单元包括第一测量电极101，以及覆盖在第一测量电极101上的第一湿敏材料201，所述 第二湿度传感器单元包括第二测量电极102，以及覆盖在所述第二测量电极102上的第二湿敏材料202，所述第一湿度传感器单元和所述第二湿度传感器单元的最大湿度漂移不同，所述分析处理单元对第一湿度传感器单元和第二湿度传感器单元的测量值进行校正并输出。
参照图3，第一测量电极101包括第一测量正极1011和第一测量负极1012，所述第一测量正极1011和第一测量负极1012上均设置有叉指电极212；
参照图4，所述第二测量电极102由第二测量正极1021和第二测量负极1022组合而成，所述第二测量正极1021和第二测量负极1022上均设置有叉指电极212，所述叉指电极212呈交错设置。
所述第一测量电极101和所述第二测量电极102为电容型电极；或者，所述第一测量电极101和所述第二测量电极102为电阻型电极。
下面针对采用电容性电极的情况进行详细说明。
在第一测量电极101的一面与第一湿敏材料201之间设置有钝化层211，所述第一测量电极101的另一面上依次设置有介质层213和衬底硅片214，且介质层213填充在第一测量电极101与衬底硅片214之间。
在所述第二测量电极102的一面与第二湿敏材料202之间设置有钝化层211，所述第二测量电极102的另二面上依次设置有介质层213和衬底硅片214，且介质层213填充在第二测量电极102与衬底硅片214之间。
所述第一湿敏材料201和第二湿敏材料202为光敏性湿敏材料或非光敏性湿敏材料，所述第一湿敏材料201和所述第二湿敏材料202的加工方法根据材料的不同分为以下几种情形：
-若第一湿敏材料201和第二湿敏材料202均为光敏性湿敏材料，采用直接光刻的方式得到图形；
-若第一湿敏材料201或第二湿敏材料202中的一个为非光敏性湿敏材料，加工方法包括：
步骤S1.1：在第一测量电极101和第二测量电极102的钝化层211上旋涂非光敏性湿敏材料并固化，然后再非光敏性湿敏材料上旋涂光刻胶，并光刻出所需的图形，再通过干法蚀刻的工艺加工，最后去除光刻胶，完成一种湿敏材料的加工；
步骤S1.2：旋涂光敏性湿敏材料，通过光刻的方式图形化，并固化光敏性湿敏材料，得到另一种湿敏材料；
-若第一湿敏材料201和第二湿敏材料202均为非光敏性湿敏材料，加工方法包括：
步骤S2.1：在两个测量电极的钝化层211上旋涂第一湿敏材料201并固化，然后在第一光敏性湿敏材料上旋涂光刻胶，并光刻出所需的图形，再通过干法蚀刻的工艺加工，最后去除光刻胶，完成第一湿敏材料201的加工；
步骤S2.2：旋涂第二湿敏材料202并固化，然后在第二光敏性湿敏材料上旋涂光刻胶，并光刻出所需的图形，在通过干法蚀刻的工艺加工，保留第一光敏性湿敏材料上附着的第二光敏性湿敏材料，最后去除光刻胶，完成第二湿敏材料202的加工。
当第一湿敏材料201和第二湿敏材料202均为非光敏性湿敏材料时，问题将变得复杂，加工第一湿敏材料201的方法仍然不变，但是，如果同样采用干法刻蚀加工第二湿敏材料202，那么因为干法刻蚀对于第一湿敏材料201和第二湿敏材料202没有任何选择性，导致去除第二湿度传感器单元以外区域的第二湿敏材料202时，第一湿度传感器单元区域内的的第一湿敏材料201因为过刻蚀，也会发生厚度损失。然而，幸运的是，我们并不一定需要去除第一湿敏材料201上的第二湿敏材料202。参照图5，即第一传感单元上可以保留第二湿敏材料202，这样在工艺集成上就大大减少了冲突。但是这种方案需要保证一个前提，第一湿敏材料201的厚度要大于1倍以上的叉指电极212的铝条线宽和边间距之和，这样电容器的电场线将不会或仅有极少量会穿过第二湿敏材料202，如图5所示，降低第一湿敏材料201和第二湿敏材料202之间的串扰。
下面对电阻性电极进行详细说明。
参照图6，所述第一湿敏材料201设置在第一测量电极101的一面，所述第一测量电极101的另一面上依次设置有介质层213和衬底硅片214，且介质层213填充在第一测量电极101与衬底硅片214之间。
所述第二湿敏材料202设置在第二测量电极102的一面，所述第二测量电极102的另一面上依次设置有介质层213和衬底硅片214，且介质层213填充在第二测量电极102与衬底硅片214之间。
所述第一湿敏材料201和第二湿敏材料202为光敏性湿敏材料；或所述第一湿敏材料201和第二湿敏材料202中的任意一种为非光敏性湿敏材料，另一种为光敏性湿敏材料；所述第一湿敏材料201和所述第二湿敏材料202的加工方法包括：
-若第一湿敏材料201和第二湿敏材料202均为光敏性湿敏材料，采用直接光刻的方式得到图形；
-若第一湿敏材料201或第二湿敏材料202中的一个为非光敏湿敏材料，加工方法 为：
步骤S3.1：在第一测量电极101和第二测量电极102上旋涂非光敏湿敏材料并固化，然后在非光敏性湿敏材料上旋涂光刻胶，并光刻出所需的图形，再通过干法蚀刻的工艺加工，最后去除光刻胶，完成一种湿敏材料的加工；
步骤S3.2：旋涂光敏性湿敏材料，通过光刻的方式图形化，并固化光敏性湿敏材料，得到另一种湿敏材料；
-若第一湿敏材料201和第二湿敏材料202均为非光敏性湿敏材料，加工方法包括：
步骤S4.1：在第一测量电极101和第二测量电极102的上旋涂第一非光敏湿敏材料并固化，然后在非光敏性湿敏材料上旋涂光刻胶，并光刻出所需的图形，再通过干法蚀刻的工艺加工，最后去除光刻胶，完成一种湿敏材料的加工；
步骤S4.2：旋涂第二非光敏性湿敏材料，然后再旋涂光刻胶，通过光刻的方式图形化，接着利用碱性显影液(TMAH)在光刻胶显影的同时，腐蚀第二非光敏性材料，去除光刻胶后对第二湿敏材料固化，得到另一种湿敏材料；
针对电阻式电极，若在叉指电极上同时堆叠覆盖第一湿敏材料和第二湿敏材料，第一湿敏层和第二湿敏层形成并联关系，测量的湿敏电阻将是第一湿敏材料和第二湿敏材料综合的结果，从而对湿度测量单元的结果产生影响，因此在加工电阻式电极上的湿敏材料时，第一湿敏材料和第二湿敏材料不能均采用非光敏性湿敏材料。然而，针对电容式电极，由于电场线的穿越高度有限，因此允许出现第一湿敏材料和第二湿敏材料堆叠的情形出现。此时满足第一湿敏材料201的厚度大于1倍以上的叉指电极212的铝条线宽和边间距之和。
以上是针对单端结构的湿度传感器的方案，如果ASIC电路采用的是差分式采样结构，对于传感器件端的第一湿度传感器单元和第二湿度传感器单元也需要设计成差分对的形式。参照图7，其中包括第一传感子单元111，第二传感子单元112，第三传感子单元113为第三传感单元以及第四传感子单元114；其中，第一传感子单元111包括第一子单元正极1111和第一子单元负极1112；第二传感子单元112包括第二子单元正极1121和第二子单元负极1122；第三传感子单元113包括第三子单元正极1131和第三子单元负极1132；第四传感子单元114包括第四子单元正极1141和第四子单元负极1142。对于本发明一个或多个实施例所需的第一湿度传感器单元和第二湿度传感器单元，其可以由任意两个传感子单元进行组合得到。但是由于实际版图需要较高的匹配，一般来说，第一湿度传感器单元由第一传感子单元111和第四传感子单元114组合，第二湿度传感 器单元由第二传感子单元112和第三传感子单元113组合。在后续涂敷湿敏材料时同前述方案一致。
本发明其中一个实施例公开一种湿度传感器校准方法，分析处理单元在接收到第一湿度传感器单元和第二湿度传感器单元所测量的结果时，对两个结果进行误差计算，最终生成准确的湿度值，具体的校准过程参照图8，包括以下步骤：
步骤S1：获取第一湿度传感器单元和第二湿度传感器单元的湿度最大漂移特性与环境湿度的关系，计算第一湿度传感器单元和第二湿度传感器单元的最大漂移差值。
首先，通过小批量的试验数据，分别研究出第一湿度传感器单元和第二湿度传感器单元的湿度最大漂移特性与环境湿度的关系，其通用性回归关系可以用关于环境湿度的一阶方程表示，如式1和2表示。最大漂移可以通过诸如85℃85％RH试验，或者HAST试验等进行加速老化一定时间，使传感器的漂移达到稳定。通常来说，测试时，低湿下湿度漂移值较小，中湿时漂移值中等，高湿时漂移值最大，呈现出与当前测试环境湿度的相关性。部分聚合物材料也会表现出良好的全湿度量程下的线性漂移，即一阶项为0。我们将第一湿度传感器单元和第二湿度传感器单元的最大漂移值作差，得到式3，作为后续的参比量。
RH_Drift max_A＝αRH+a    (1)
RH_Drift max_B＝βRH+b     (2)
ΔRH_Drift max＝(β-α)RH+(b-a)     (3)
步骤S2：将第一湿度传感器单元和第二湿度传感器单元的电容值与实测RH值进行回归拟合，得到第一拟合方程和第二拟合方程。
将第一湿度传感器单元和第二湿度传感器单元进行校准，建立起“环境湿度——湿度电容或湿度电阻——ADC数字量——读取湿度值”的对应关系。一般来说二阶拟合能满足大多数的传感器的精度的需求，如式4和5所示；当然根据数字电路的设计能力或传感器件的需求，可以采用诸如三阶以上的回归拟合。完成该步骤后，第一湿度传感器单元和第二湿度传感器单元将能独立测得各自的湿度值。
Figure PCTCN2022126889-appb-000001
Figure PCTCN2022126889-appb-000002
步骤S3：获取某一湿度环境下，第一湿度传感器单元和第二湿度传感器单元的湿度值，并计算第一湿度传感器单元和第二湿度传感器单元的实际湿度差，并将实际湿度差与最大漂移差值类比。
当处在某一环境湿度RH时，第一湿度传感器单元和第二湿度传感器单元将分别读出RH A和RH B两个湿度值，此时我们得到两者的差值，如式6所示：
ΔRH＝RH B-RH A       (6)
步骤S4：将第一湿度传感器单元和第二湿度传感器单元的实际湿度差与第一湿度传感器单元最大漂移特性与环境湿度的关系以及第二湿度传感器单元湿度最大漂移特性与环境湿度的关系类比，得到当前湿度环境下第一湿度传感器单元的湿度漂移量，以及第二湿度传感器单元的湿度漂移量。
将式6与式1或者式2进行类比，我们可以得到当前湿度环境下传感单元A和B的湿度漂移量，分别如式7和8所示。
Figure PCTCN2022126889-appb-000003
Figure PCTCN2022126889-appb-000004
步骤S5：根据第一拟合方程和第二拟合方程，以及步骤S4中的第一湿度传感器单元的湿度漂移量，第二湿度传感器单元的湿度漂移量，分别建立关于真实湿度值RH的方程。
根据式4、5实测的RH值和7、8的漂移补偿值能够分别建立关于真实湿度值RH的方程，如式9和10所示。
RH＝RH A-RH_Drift A   (9)
RH＝RH B-RH_Drift B    (10)
步骤S6：根据步骤S5中的真实湿度值RH的方程，建立第一湿度传感器单元关于RH的二阶方程以及第二湿度传感器单元关于RH的二阶方程。
根据式9和式10，均能得到关于RH的二阶方程，两个方程都能求出关于真实RH的值，如式11和12所示。理论上如果传感单元A和传感单元B的漂移速率相当，那么传感单元A和B求出的RH值应该相等，取任意一个值均可。但是实际很难有这样的理想状况，诸如同种材料的个体差异，不同材料的漂移速率差异等问题，需要增加判别，以增加数据的可信度。
RH_real A＝f A(RH A,RH B)    (11)
RH_real B＝f B(RH A,RH B)    (12)
步骤S7：根据第一湿度传感器单元关于RH的二阶方程以及第二湿度传感器单元关于RH的二阶方程的差值分别权重，完成校正流程。
最后，我们对传感单元A和B求出的真实RH值进行权重分配，当两者之间的 差值小于某一设定阈值时，γ和δ可以取0.5；当两者之间的差值超过设定阈值时，取其中置信度更高的传感单元作为主传感单元，分配更高的权重；这样我们最终可以得到全生命周期无漂移的湿度传感器。
RH＝γRH_real A+δRH_real B(13)
在本申请的描述中，需要理解的是，术语“上”、“下”、“前”、“后”、“左”、“右”、“竖直”、“水平”、“顶”、“底”、“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。
与现有技术相比，本发明具有如下的有益效果：
1、本发明的湿度传感器能够有效解决一般电容湿度传感器或电阻式湿度传感器漂移的问题；
2、针对不同材料的湿敏材料采用相应的加工方法，适用性较高；
3、本发明的校准方法对第一湿度传感器单元和第二湿度传感器单元的实测值进行补偿校正，实现了无漂移的湿度测量，且本方案实现成本较低。
以上对本发明的具体实施例进行了描述。需要理解的是，本发明并不局限于上述特定实施方式，本领域技术人员可以在权利要求的范围内做出各种变化或修改，这并不影响本发明的实质内容。在不冲突的情况下，本申请的实施例和实施例中的特征可以任意相互组合。

Claims (11)

  1. 一种无漂移湿度传感器，其特征在于，包括：第一湿度传感器单元、第二湿度传感器单元以及分析处理单元，所述第一湿度传感器单元包括第一测量电极(101)，以及覆盖在第一测量电极(101)上的第一湿敏材料(201)，所述第二湿度传感器单元包括第二测量电极(102)，以及覆盖在所述第二测量电极(102)上的第二湿敏材料(202)，所述第一湿度传感器单元和所述第二湿度传感器单元的最大湿度漂移不同，所述分析处理单元对第一湿度传感器单元和第二湿度传感器单元的测量值进行校正并输出。
  2. 根据权利要求1所述的无漂移湿度传感器，其特征在于：所述第一测量电极(101)包括第一测量正极(1011)和第一测量负极(1012)，所述第一测量正极(1011)和第一测量负极(1012)上均设置有叉指电极(212)；
    所述第二测量电极(102)由第二测量正极(1021)和第二测量负极(1022)组合而成，所述第二测量正极(1021)和第二测量负极(1022)上均设置有叉指电极(212)，
    所述叉指电极(212)呈交错设置。
  3. 根据权利要求1所述的无漂移湿度传感器，其特征在于：所述第一测量电极(101)和所述第二测量电极(102)为电容型电极；或者，所述第一测量电极(101)和所述第二测量电极(102)为电阻型电极。
  4. 根据权利要求3所述的无漂移湿度传感器，其特征在于：所述第一测量电极(101)和所述第二测量电极(102)为电容型电极，在所述第一测量电极(101)的一面与第一湿敏材料(201)之间设置有钝化层(211)，所述第一测量电极(101)的另一面上依次设置有介质层(213)和衬底硅片(214)，且介质层(213)填充在第一测量电极(101)与衬底硅片(214)之间；
    所述第二测量电极(102)的一面与第二湿敏材料(202)之间设置有钝化层(211)，所述第二测量电极(102)的另二面上依次设置有介质层(213)和衬底硅片(214)，且介质层(213)填充在第二测量电极(102)与衬底硅片(214)之间。
  5. 根据权利要求3所述的无漂移湿度传感器，其特征在于：所述第一测量电极(101)和所述第二测量电极(102)为电阻型电极，所述第一湿敏材料(201)设置在第一测量电极(101)的一面，所述第一测量电极(101)的另一面上依次设置有介质层(213)和衬底硅片(214)，且介质层(213)填充在第一测量电极(101)与衬底硅片(214)之间；
    所述第二湿敏材料(202)设置在第二测量电极(102)的一面，所述第二测量电极(102)的另一面上依次设置有介质层(213)和衬底硅片(214)，且介质层(213)填充在第二测量电极(102)与衬底硅片(214)之间。
  6. 根据权利要求4所述的无漂移湿度传感器，其特征在于：所述第一湿敏材料(201)和第二湿敏材料(202)为光敏性湿敏材料或非光敏性湿敏材料，所述第一湿敏材料(201)和所述第二湿敏材料(202)的加工方法包括：
    -若第一湿敏材料(201)和第二湿敏材料(202)均为光敏性湿敏材料，采用直接光刻的方式得到图形；
    -若第一湿敏材料(201)或第二湿敏材料(202)中的一个为非光敏湿敏材料，加工方法包括：
    步骤S1.1：在第一测量电极(101)和第二测量电极(102)的钝化层(211)上旋涂非光敏湿敏材料并固化，然后在非光敏性湿敏材料上旋涂光刻胶，并光刻出所需的图形，再通过干法蚀刻的工艺加工，最后去除光刻胶，完成一种湿敏材料的加工；
    步骤S1.2：旋涂光敏性湿敏材料，通过光刻的方式图形化，并固化光敏性湿敏材料，得到另一种湿敏材料；
    -若第一湿敏材料(201)和第二湿敏材料(202)均为非光敏性湿敏材料，加工方法包括：
    步骤S2.1：在两个测量电极的钝化层(211)上旋涂第一湿敏材料(201)并固化，且所述第一湿敏材料(201)的厚度大于一倍以上叉指电极(212)的宽度和边距之和，然后在第一光敏性湿敏材料上旋涂光刻胶，并光刻出所需的图形，再通过干法蚀刻的工艺加工，最后去除光刻胶，完成第一湿敏材料(201)的加工；
    步骤S2.2：旋涂第二湿敏材料(202)并固化，然后在第二湿敏材料(202)上旋涂光刻胶，并光刻出所需的图形，在通过干法蚀刻的工艺加工，保留第一湿敏材料(201)上附着的第二湿敏材料(202)，最后去除光刻胶，完成第二湿敏材料(202)的加工。
  7. 根据权利要求5所述的无漂移湿度传感器，其特征在于：所述第一湿敏材料(201)和第二湿敏材料(202)为光敏性湿敏材料；或所述第一湿敏材料(201)和第二湿敏材料(202)中的任意一种为非光敏性湿敏材料，另一种为光敏性湿敏材料；所述第一湿敏材料(201)和所述第二湿敏材料(202)的加工方法包括：
    -若第一湿敏材料(201)和第二湿敏材料(202)均为光敏性湿敏材料，采用直接光刻的方式得到图形；
    -若第一湿敏材料(201)或第二湿敏材料(202)中的一个为非光敏湿敏材料，加工方法为：
    步骤S3.1：在第一测量电极(101)和第二测量电极(102)上旋涂非光敏湿敏材料并固化，然后在非光敏性湿敏材料上旋涂光刻胶，并光刻出所需的图形，再通过干法蚀刻的工艺加工，最后去除光刻胶，完成一种湿敏材料的加工；
    步骤S3.2：旋涂光敏性湿敏材料，通过光刻的方式图形化，并固化光敏性湿敏材料，得到另一种湿敏材料；
    -若第一湿敏材料(201)和第二湿敏材料(202)均为非光敏性湿敏材料，加工方法包括：
    步骤S4.1：在第一测量电极(101)和第二测量电极(102)上旋涂第一非光敏湿敏材料并固化，然后在非光敏性湿敏材料上旋涂光刻胶，并光刻出所需的图形，再通过干法蚀刻的工艺加工，最后去除光刻胶，完成一种湿敏材料的加工；
    步骤S4.2：旋涂第二非光敏性湿敏材料，然后再旋涂光刻胶，通过光刻的方式图形化，接着利用碱性显影液(TMAH)在光刻胶显影的同时，腐蚀第二非光敏性材料，去除光刻胶后对第二湿敏材料固化，得到另一种湿敏材料；
  8. 根据权利要求1所述的无漂移湿度传感器，其特征在于：所述湿度传感器采用差分式采样结构，其中，所述第一湿度传感器单元包括第一传感子单元(111)和第二传感子单元(112)，所述第二湿度传感器单元包括第三传感子单元(113)和第四传感子单元(114)。
  9. 一种湿度传感器的校准方法，基于权利要求1-8任一项所述的无漂移湿度传感器，其特征在于，包括以下步骤：
    步骤S1：获取第一湿度传感器单元和第二湿度传感器单元的湿度最大漂移特性与环境湿度的关系，计算第一湿度传感器单元和第二湿度传感器单元的最大漂移差值；
    步骤S2：将第一湿度传感器单元和第二湿度传感器单元的湿敏电容值或湿敏电阻值与实测RH值进行回归拟合，得到第一拟合方程和第二拟合方程；
    步骤S3：获取某一湿度环境下，第一湿度传感器单元和第二湿度传感器单元的湿度值，并计算第一湿度传感器单元和第二湿度传感器单元的实际湿度差，并将实际湿度差与最大漂移差值类比；
    步骤S4：将第一湿度传感器单元和第二湿度传感器单元的实际湿度差与第一湿度传感器单元最大漂移特性与环境湿度的关系以及第二湿度传感器单元湿度最大漂移特性 与环境湿度的关系类比，得到当前湿度环境下第一湿度传感器单元的湿度漂移量，以及第二湿度传感器单元的湿度漂移量；
    步骤S5：根据第一拟合方程和第二拟合方程，以及步骤S4中的第一湿度传感器单元的湿度漂移量，第二湿度传感器单元的湿度漂移量，分别建立关于真实湿度值RH的方程；
    步骤S6：根据步骤S5中的真实湿度值RH的方程，建立第一湿度传感器单元关于RH的二阶方程以及第二湿度传感器单元关于RH的二阶方程；
    步骤S7：根据第一湿度传感器单元关于RH的二阶方程以及第二湿度传感器单元关于RH的二阶方程的差值分别权重，完成校正流程。
  10. 根据权利9所述的一种湿度传感器的校准方法，其特征在于：所述第一湿度传感器单元和第二湿度传感器单元的最大漂移通过85℃85％RH试验，或者通过120℃100％RH的HAST试验进行获取。
  11. 根据权利9所述的一种湿度传感器的校准方法，其特征在于：所述步骤S7中，当第一湿度传感器单元关于RH的二阶方程以及第二湿度传感器单元关于RH的二阶方程的差值小于设定值，按照1:1分配权重；当差值超过设定值，取其中置信度更高的传感单元作为主传感单元，分配更高的权重。
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