CN114705724A - No-drift humidity sensor - Google Patents
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Abstract
The invention provides a drift-free humidity sensor, comprising: first humidity transducer unit and second humidity transducer unit, first humidity transducer unit includes first measuring electrode, it has first humidity sensitive material to cover on the first measuring electrode, second humidity transducer unit includes second measuring electrode, it has second humidity sensitive material to cover on the second measuring electrode, first humidity transducer unit with the maximum humidity drift of second humidity transducer unit is different. The humidity sensor can effectively solve the problem of drifting of a common capacitance type humidity sensor or resistance type humidity sensor; the corresponding processing method is adopted for the humidity sensitive materials of different materials, so that the applicability is high; through the correction algorithm, the measurement accuracy is improved.
Description
Technical Field
The invention relates to the technical field of humidity sensors, in particular to a drift-free humidity sensor.
Background
The humidity sensor is widely applied to indoor temperature and humidity monitoring, smart home, white appliances, security protection, agriculture and other fields, and plays a great role. The realization principle of the humidity sensor comprises a resistance type, a capacitance type, a mass weighing type, a dry-wet ball type and the like. Because the capacitance type and resistance type humidity sensors are easy to be compatible with a CMOS (complementary metal oxide semiconductor) process, have good linearity, wide humidity range (0-100% RH) and the like, the temperature and humidity sensor chip has multiple purposes, wherein the capacitance type is most widely used.
However, the sensor using the polymer as the humidity-sensitive material, no matter whether it is of a capacitive type, a resistive type, or a pressure-sensitive type, due to the inherent characteristics of the polymer, will inevitably form chemisorption water vapor, and is difficult to desorb, and humidity drift is generated, especially in a high-temperature and high-humidity environment, the long-chain spatial position of the polymer expands, and the humidity drift characteristic thereof is more obvious.
To address the drift characteristics of humidity sensors, US9696272B2 proposes a method of adjusting the sampling frequency to improve the drift characteristics; US4793175 patent proposes the use of inorganic substances as moisture sensitive materials, resistant to drift; there is also a large body of literature that suggests improved polymer structures to ameliorate this problem.
Disclosure of Invention
In view of the defects in the prior art, the present invention provides a drift-free humidity sensor and a calibration method thereof.
According to the present invention, there is provided a drift-free humidity sensor comprising: first humidity sensor unit, second humidity sensor unit and analysis and processing unit, first humidity sensor unit includes first measuring electrode to and cover the first humidity sensitive material on first measuring electrode, second humidity sensor unit includes second measuring electrode, and cover second humidity sensitive material on the second measuring electrode, first humidity sensor unit with the maximum humidity drift of second humidity sensor unit is different, analysis and processing unit rectifies and exports the measured value of first humidity sensor unit and second humidity sensor unit.
Preferably, the first measuring electrode comprises a first measuring positive electrode and a first measuring negative electrode, and interdigital electrodes are arranged on the first measuring positive electrode and the first measuring negative electrode;
the second measuring electrode is formed by combining a second measuring positive electrode and a second measuring negative electrode, interdigital electrodes are arranged on the second measuring positive electrode and the second measuring negative electrode,
the interdigital electrodes are arranged in a staggered manner.
Preferably, the first and second measuring electrodes are capacitance type electrodes; alternatively, the first and second measuring electrodes are resistive electrodes.
Preferably, the first measuring electrode and the second measuring electrode are capacitance type electrodes, a passivation layer is arranged between one surface of the first measuring electrode and the first humidity sensitive material, a dielectric layer and a substrate silicon wafer are sequentially arranged on the other surface of the first measuring electrode, and the dielectric layer is filled between the first measuring electrode and the substrate silicon wafer;
a passivation layer is arranged between one surface of the second measuring electrode and the second humidity-sensitive material, a dielectric layer and a substrate silicon wafer are sequentially arranged on the other surface of the second measuring electrode, and the dielectric layer is filled between the second measuring electrode and the substrate silicon wafer.
Preferably, the first measuring electrode and the second measuring electrode are resistance type electrodes, the first humidity sensitive material is arranged on one surface of 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 dielectric layer is filled between the first measuring electrode and the substrate silicon wafer;
the second humidity-sensitive material is arranged on one surface of the second measuring electrode, a dielectric layer and a substrate silicon wafer are sequentially arranged on the other surface of the second measuring electrode, and the dielectric layer is filled between the second measuring electrode and the substrate silicon wafer.
Preferably, for the capacitive electrode, the first humidity sensitive material and the second humidity sensitive material are photosensitive humidity sensitive materials or non-photosensitive humidity sensitive materials, and the processing method of the first humidity sensitive material and the second humidity sensitive material comprises the following steps:
-if the first and second moisture sensitive materials are both photosensitive moisture sensitive materials, obtaining a pattern by direct lithography;
-if one of the first or second moisture sensitive material is a non-photosensitive moisture sensitive material, the processing method comprises:
step S1.1: spin-coating a non-photosensitive humidity-sensitive material on the passivation layers of the first measuring electrode and the second measuring electrode, curing, then spin-coating a photoresist on the non-photosensitive humidity-sensitive material, photoetching a required pattern, processing by a dry etching process, and finally removing the photoresist to finish processing the humidity-sensitive material;
step S1.2: spin-coating a photosensitive moisture-sensitive material, patterning in a photoetching mode, and curing the photosensitive moisture-sensitive material to obtain another moisture-sensitive material;
-if the first and second moisture sensitive materials are both non-photosensitive moisture sensitive materials, the processing method comprises:
step S2.1: spin-coating a first humidity-sensitive material on the passivation layers of the two measuring electrodes and curing, wherein the thickness of the first humidity-sensitive material is more than one time of the sum of the width and the edge distance of the interdigital electrode, then spin-coating a photoresist on the first humidity-sensitive material, photoetching to obtain a required pattern, processing by a dry etching process, and finally removing the photoresist to complete the processing of the first humidity-sensitive material;
step S2.2: spin-coating a second humidity-sensitive material and curing, then spin-coating a photoresist on the second humidity-sensitive material, photoetching a required pattern, processing by a dry etching process, reserving the second humidity-sensitive material attached to the first humidity-sensitive material, and finally removing the photoresist to finish processing the second humidity-sensitive material.
Preferably, for the resistive electrode, the first and second moisture-sensitive materials are photosensitive moisture-sensitive materials; or any one of the first humidity-sensitive material and the second humidity-sensitive material is a non-photosensitive humidity-sensitive material, and the other one is a photosensitive humidity-sensitive material; the method of processing the first and second moisture-sensitive materials comprises:
-if the first and second moisture sensitive materials are both photosensitive moisture sensitive materials, obtaining a pattern by direct lithography;
-if one of the first or second moisture sensitive material is a non-photosensitive moisture sensitive material, processing by:
step S3.1: spin-coating a non-photosensitive moisture-sensitive material on the first measuring electrode and the second measuring electrode, curing, then spin-coating a photoresist on the non-photosensitive moisture-sensitive material, photoetching to obtain a required pattern, processing by a dry etching process, and finally removing the photoresist to finish processing the moisture-sensitive material;
step S3.2: spin-coating a photosensitive moisture-sensitive material, patterning in a photoetching mode, and curing the photosensitive moisture-sensitive material to obtain another moisture-sensitive material;
-if the first and second moisture sensitive materials are both non-photosensitive moisture sensitive materials, the processing method comprises:
step S4.1: spin-coating a first non-photosensitive humidity-sensitive material on the first measuring electrode and the second measuring electrode, curing, then spin-coating a photoresist on the non-photosensitive humidity-sensitive material, photoetching to obtain a required pattern, processing by a dry etching process, and finally removing the photoresist to finish processing the humidity-sensitive material;
step S4.2: spin-coating a second non-photosensitive humidity-sensitive material, then spin-coating a photoresist, patterning in a photoetching mode, corroding the second non-photosensitive material while developing the photoresist by using alkaline developing solution (TMAH), and curing the second humidity-sensitive material after removing the photoresist to obtain another humidity-sensitive material;
preferably, the humidity sensor adopts a differential sampling structure, wherein the first humidity sensor unit comprises a first sensing subunit and a second sensing subunit, and the second humidity sensor unit comprises a third sensing subunit and a fourth sensing subunit.
Compared with the prior art, the invention has the following beneficial effects:
1. the humidity sensor can effectively solve the problem of drifting of a common capacitance humidity sensor or a resistance-type humidity sensor;
2. the corresponding processing method is adopted for the humidity sensitive materials of different materials, and the applicability is high.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a schematic diagram of the interdigital capacitor of the humidity sensor of the present invention;
FIG. 2 is a schematic cross-sectional view of a humidity sensitive material in the humidity sensor of the present invention;
FIG. 3 is a cross-sectional view of a first humidity sensor cell of the capacitive sensor of the present invention;
FIG. 4 is a cross-sectional view of a second humidity sensor unit of the capacitive sensor of the present invention;
FIG. 5 is a cross-sectional view of a first humidity sensor unit in the present invention using two non-photosensitive humidity-sensitive materials;
FIG. 6 is a cross-sectional view of a resistive sensor according to the present invention;
FIG. 7 is a schematic diagram of interdigital capacitance of a humidity sensor with a differential sampling structure according to the present invention;
FIG. 8 is a flow chart of a method for calibrating a humidity sensor according to the present invention.
Description of reference numerals:
first measuring electrode 101 and second measuring electrode 102
First positive measurement electrode 1011 and second positive measurement electrode 1021
First measuring cathode 1012 and second measuring cathode 1022
First moisture sensitive material 201 second moisture sensitive material 202
Interdigitated electrode 212 substrate silicon wafer 214
Second subcell positive 1121 and second subcell negative 1122
Third subcell positive electrode 1131 third subcell negative electrode 1132
Fourth subcell positive electrode 1141 fourth subcell negative electrode 1142
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
A planar humidity sensor comprises a capacitance humidity sensor and a resistance humidity sensor, an interdigital structure is generally arranged on a silicon wafer or an ASIC wafer, and then a layer of humidity-sensitive material is coated on an interdigital electrode, so that the detection of a humidity-sensitive capacitor is realized. And the circuit detection at the rear end is generally divided into a single-ended structure and a differential structure, wherein the single-ended structure samples a single electrode, and the differential structure samples two symmetrical electrodes.
The invention discloses a drift-free humidity sensor, which comprises the following components in parts by weight with reference to fig. 1 and 2: the humidity sensor comprises a first humidity sensor unit, a second humidity sensor unit and an analysis processing unit, wherein the first humidity sensor unit comprises a first measuring electrode 101 and a first humidity-sensitive material 201 covered on the first measuring electrode 101, the second humidity sensor unit comprises a second measuring electrode 102 and a second humidity-sensitive material 202 covered on the second measuring electrode 102, the maximum humidity drift of the first humidity sensor unit and the maximum humidity drift of the second humidity sensor unit are different, and the analysis processing unit corrects and outputs the measured values of the first humidity sensor unit and the second humidity sensor unit.
Referring to fig. 3, the first measuring electrode 101 includes a first positive measuring electrode 1011 and a first negative measuring electrode 1012, and the first positive measuring electrode 1011 and the first negative measuring electrode 1012 are both provided with the interdigital electrode 212;
referring to fig. 4, the second measurement electrode 102 is formed by combining a second positive measurement electrode 1021 and a second negative measurement electrode 1022, the interdigital electrodes 212 are disposed on both the second positive measurement electrode 1021 and the second negative measurement electrode 1022, and the interdigital electrodes 212 are disposed in an interlaced manner.
The first measuring electrode 101 and the second measuring electrode 102 are capacitance type electrodes; alternatively, the first measuring electrode 101 and the second measuring electrode 102 are resistance type electrodes.
The following is a detailed description of the case of using capacitive electrodes.
A passivation layer 211 is arranged between one surface of the first measuring electrode 101 and the first humidity-sensitive material 201, a dielectric layer 213 and a substrate silicon wafer 214 are sequentially arranged on the other surface of the first measuring electrode 101, and the dielectric layer 213 is filled between the first measuring electrode 101 and the substrate silicon wafer 214.
A passivation layer 211 is arranged between one surface of the second measuring electrode 102 and the second humidity-sensitive material 202, a dielectric layer 213 and a substrate silicon wafer 214 are sequentially arranged on the other surface of the second measuring electrode 102, and the dielectric layer 213 is filled between the second measuring electrode 102 and the substrate silicon wafer 214.
The first humidity-sensitive material 201 and the second humidity-sensitive material 202 are photosensitive humidity-sensitive materials or non-photosensitive humidity-sensitive materials, and the processing methods of the first humidity-sensitive material 201 and the second humidity-sensitive material 202 are divided into the following situations according to the difference of the materials:
if the first humidity-sensitive material 201 and the second humidity-sensitive material 202 are both photosensitive humidity-sensitive materials, obtaining a pattern by direct photolithography;
if one of the first or second moisture- sensitive materials 201, 202 is a non-photosensitive moisture-sensitive material, the processing method comprises:
step S1.1: spin-coating a non-photosensitive moisture-sensitive material on the passivation layer 211 of the first measuring electrode 101 and the second measuring electrode 102 and curing, then spin-coating a photoresist on the non-photosensitive moisture-sensitive material, photoetching to obtain a required pattern, processing by a dry etching process, and finally removing the photoresist to complete the processing of the moisture-sensitive material;
step S1.2: spin-coating a photosensitive moisture-sensitive material, patterning in a photoetching mode, and curing the photosensitive moisture-sensitive material to obtain another moisture-sensitive material;
-if the first and second moisture sensitive materials 201, 202 are both non-photosensitive moisture sensitive materials, the processing method comprises:
step S2.1: spin-coating a first humidity-sensitive material 201 on the passivation layer 211 of the two measuring electrodes and curing, then spin-coating a photoresist on the first humidity-sensitive material, photoetching to obtain a required pattern, processing by a dry etching process, and finally removing the photoresist to complete the processing of the first humidity-sensitive material 201;
step S2.2: spin-coating the second humidity-sensitive material 202 and curing, then spin-coating a photoresist on the second photosensitive humidity-sensitive material, and photo-etching a desired pattern, and processing by dry etching to retain the second photosensitive humidity-sensitive material attached to the first photosensitive humidity-sensitive material, and finally removing the photoresist to complete the processing of the second humidity-sensitive material 202.
When the first humidity-sensitive material 201 and the second humidity-sensitive material 202 are both non-photosensitive humidity-sensitive materials, the problem becomes complicated and the method of processing the first humidity-sensitive material 201 remains unchanged, but if the second humidity-sensitive material 202 is also processed by dry etching, thickness loss of the first humidity-sensitive material 201 in the region of the first humidity sensor unit also occurs due to over-etching when the second humidity-sensitive material 202 in the region other than the second humidity sensor unit is removed because the dry etching does not have any selectivity to the first humidity-sensitive material 201 and the second humidity-sensitive material 202. Fortunately, however, we do not necessarily need to remove the second moisture-sensitive material 202 on the first moisture-sensitive material 201. Referring to fig. 5, the second humidity sensitive material 202 may remain on the first sensing unit, which greatly reduces conflicts in process integration. However, this solution needs to ensure that the thickness of the first humidity-sensitive material 201 is more than 1 times the sum of the line width and the edge distance of the aluminum strips of the interdigital electrodes 212, so that no or only a very small amount of the electric field lines of the capacitor will pass through the second humidity-sensitive material 202, as shown in fig. 5, thereby reducing the crosstalk between the first humidity-sensitive material 201 and the second humidity-sensitive material 202.
The resistive electrode will be described in detail below.
Referring to fig. 6, the first humidity-sensitive material 201 is disposed on one side of the first measuring electrode 101, a dielectric layer 213 and a substrate silicon wafer 214 are sequentially disposed on the other side of the first measuring electrode 101, and the dielectric layer 213 is filled between the first measuring electrode 101 and the substrate silicon wafer 214.
The second humidity-sensitive material 202 is arranged on one surface of the second measuring electrode 102, a dielectric layer 213 and a substrate silicon wafer 214 are sequentially arranged on the other surface of the second measuring electrode 102, and the dielectric layer 213 is filled between the second measuring electrode 102 and the substrate silicon wafer 214.
The first humidity-sensitive material 201 and the second humidity-sensitive material 202 are photosensitive humidity-sensitive materials; or any one of the first humidity-sensitive material 201 and the second humidity-sensitive material 202 is a non-photosensitive humidity-sensitive material, and the other one is a photosensitive humidity-sensitive material; the method of processing the first moisture sensitive material 201 and the second moisture sensitive material 202 comprises:
if the first humidity-sensitive material 201 and the second humidity-sensitive material 202 are both photosensitive humidity-sensitive materials, obtaining a pattern by direct photolithography;
if one of the first or second moisture sensitive material 201, 202 is a non-photosensitive moisture sensitive material, the processing is:
step S3.1: spin-coating a non-photosensitive humidity-sensitive material on the first measuring electrode 101 and the second measuring electrode 102, curing, then spin-coating a photoresist on the non-photosensitive humidity-sensitive material, photoetching a required pattern, processing by a dry etching process, and finally removing the photoresist to finish processing the humidity-sensitive material;
step S3.2: spin-coating a photosensitive moisture-sensitive material, patterning in a photoetching mode, and curing the photosensitive moisture-sensitive material to obtain another moisture-sensitive material;
-if the first and second moisture sensitive materials 201, 202 are both non-photosensitive moisture sensitive materials, the processing method comprises:
step S4.1: a first non-photosensitive humidity-sensitive material is spin-coated on the first measuring electrode 101 and the second measuring electrode 102 and is solidified, then photoresist is spin-coated on the non-photosensitive humidity-sensitive material, a required pattern is photoetched, and finally the photoresist is removed through dry etching process processing, so that the processing of the humidity-sensitive material is completed;
step S4.2: spin-coating a second non-photosensitive humidity-sensitive material, then spin-coating a photoresist, patterning in a photoetching mode, corroding the second non-photosensitive material while developing the photoresist by using alkaline developing solution (TMAH), and curing the second humidity-sensitive material after removing the photoresist to obtain another humidity-sensitive material;
for the resistance-type electrode, if the first humidity-sensitive material and the second humidity-sensitive material are stacked and covered on the interdigital electrode at the same time, the first humidity-sensitive layer and the second humidity-sensitive layer form a parallel connection relation, the measured humidity-sensitive resistance is a comprehensive result of the first humidity-sensitive material and the second humidity-sensitive material, and therefore the result of the humidity measuring unit is influenced, and therefore when the humidity-sensitive material on the resistance-type electrode is processed, the first humidity-sensitive material and the second humidity-sensitive material cannot both adopt non-photosensitive humidity-sensitive materials. However, for capacitive electrodes, stacking of the first and second moisture sensitive materials is allowed to occur due to the limited height of penetration of the electric field lines. At this time, the sum of the line width and the edge distance of the aluminum strips of the interdigital electrode 212, in which the thickness of the first humidity-sensitive material 201 is more than 1 time, is satisfied.
The above is a solution for the humidity sensor with 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 sensing device end also need to be designed in the form of differential pair. Referring to fig. 7, the first sensing subunit 111, the second sensing subunit 112, and the third sensing subunit 113 are a third sensing unit and a fourth sensing subunit 114; the first sensing subunit 111 includes a first subunit positive electrode 1111 and a first subunit negative electrode 1112; the second sensing subunit 112 includes a second subunit positive electrode 1121 and a second subunit negative electrode 1122; the third sensing subunit 113 includes a third subunit positive electrode 1131 and a third subunit negative electrode 1132; the fourth sensing sub-unit 114 includes a fourth sub-unit positive electrode 1141 and a fourth sub-unit negative electrode 1142. For the first humidity sensor unit and the second humidity sensor unit required by the present invention, they can be combined by any two sensing subunits. However, since the actual layout needs higher matching, generally speaking, the first humidity sensor unit is combined by the first sensing subunit 111 and the fourth sensing subunit 114, and the second humidity sensor unit is combined by the second sensing subunit 112 and the third sensing subunit 113. In accordance with the previous protocol when the moisture sensitive material is subsequently applied.
The invention discloses a drift-free humidity sensor correction method, wherein an analysis processing unit carries out error calculation on two results when receiving the results measured by a first humidity sensor unit and a second humidity sensor unit, and finally generates an accurate humidity value, and the specific calibration process refers to FIG. 8, and the method comprises the following steps:
step S1: and acquiring 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 calculating the maximum drift difference value of the first humidity sensor unit and the second humidity sensor unit.
Firstly, through a small batch of test data, the relationship between the maximum humidity drift characteristic of the first humidity sensor unit and the maximum humidity drift characteristic of the second humidity sensor unit and the ambient humidity is respectively researched, and the universal regression relationship can be expressed by a first-order equation related to the ambient humidity, such as equations 1 and 2. The maximum drift can be accelerated for a period of time, such as by 85% RH testing at 85 deg.C, or HAST testing, to stabilize the drift of the sensor. Generally, the humidity drift value under low humidity is small, the drift value under medium humidity is medium, and the drift value under high humidity is maximum, and shows a correlation with the current test environmental humidity. Some polymeric materials also exhibit good linear drift over the full humidity range, i.e., a first order term of 0. The maximum drift values of the first humidity sensor unit and the second humidity sensor unit are subtracted to obtain formula 3, which is used as a subsequent reference.
RH_Driftmax_A＝αRH+a (1)
RH_Driftmax_B＝βRH+b (2)
ΔRH_Driftmax＝(β-α)RH+(b-a) (3)
Step S2: and performing regression fitting on the capacitance values of the first humidity sensor unit and the second humidity sensor unit and the actually-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, and a corresponding relation of 'environment humidity-humidity capacitance or humidity resistance-ADC digital quantity-read humidity value' is established. In general, the second order fit can satisfy most of the requirements of the sensor on accuracy, as shown in formulas 4 and 5; of course, regression fitting such as more than three orders may be used depending on the design capability of the digital circuit or the requirements of the sensing device. After this step is completed, the first humidity sensor unit and the second humidity sensor unit can independently measure the respective humidity values.
Step S3: the method comprises the steps of obtaining humidity values of a first humidity sensor unit and a second humidity sensor unit in a certain humidity environment, calculating actual humidity difference of the first humidity sensor unit and the second humidity sensor unit, and comparing the actual humidity difference with a maximum drift difference value.
When the humidity sensor unit is at a certain environmental humidity RH, the first humidity sensor unit and the second humidity sensor unit respectively read out RHAAnd RHBTwo humidity values, at which time we obtain the difference between them, as shown in equation 6:
ΔRH＝RHB-RHA (6)
step S4: and comparing the actual humidity difference between the first humidity sensor unit and the second humidity sensor unit with the relationship between the maximum drift characteristic of the first humidity sensor unit and the ambient humidity and the relationship between the maximum drift characteristic of the second humidity sensor unit and the ambient humidity to obtain the humidity drift amount of the first humidity sensor unit and the humidity drift amount of the second humidity sensor unit under the current humidity environment.
By analogy between formula 6 and formula 1 or formula 2, we can obtain the humidity drift amounts of the sensing units a and B under the current humidity environment, as shown in formulas 7 and 8, respectively.
Step S5: equations regarding the true humidity values RH are respectively established based on the first fitted equation and the second fitted equation, and the humidity drift amounts of the first humidity sensor unit and the second humidity sensor unit in step S4.
The measured RH values according to equations 4, 5 and the drift compensation values of 7, 8 can establish equations for the true humidity value RH, as shown in equations 9 and 10, respectively.
RH＝RHA-RH_DriftA (9)
RH＝RHB-RH_DriftB (10)
Step S6: from the equation of the true humidity value RH in step S5, a second order equation of the first humidity sensor cell with respect to RH and a second order equation of the second humidity sensor cell with respect to RH are established.
From both equations 9 and 10, a second order equation for RH can be obtained, and both equations can find the value for true RH, as shown in equations 11 and 12. Theoretically, if the drift rates of the sensing unit a and the sensing unit B are equivalent, the RH values obtained by the sensing units a and B should be equal, and any value can be used. However, it is difficult to find ideal conditions such as individual differences of the same material, drift rate differences of different materials, and the like, and it is necessary to add discrimination to increase the reliability of data.
RH_realA＝fA(RHA,RHB) (11)
RH_realB＝fB(RHa,RHB) (12)
Step S7: and respectively weighting the difference values of the second order equation of the first humidity sensor unit relative to the RH and the second order equation of the second humidity sensor unit relative to the RH to finish the correction process.
Finally, weighting distribution is carried out on the real RH values obtained by the sensing units A and B, and when the difference value between the two values is smaller than a set threshold value, gamma and delta can be 0.5; when the difference between the two exceeds a set threshold, taking the sensing unit with higher confidence coefficient as a main sensing unit, and distributing higher weight; thus, the humidity sensor without drift in the whole life cycle can be obtained finally.
RH＝γRH_realA+δRH_realB (13)
In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (8)
1. A drift-free humidity sensor, comprising: the humidity sensor comprises a first humidity sensor unit, a second humidity sensor unit and an analysis processing unit, wherein the first humidity sensor unit comprises a first measuring electrode (101) and a first humidity-sensitive material (201) covered on the first measuring electrode (101), the second humidity sensor unit comprises a second measuring electrode (102) and a second humidity-sensitive material (202) covered on the second measuring electrode (102), the maximum humidity drift of the first humidity sensor unit and the maximum humidity drift of the second humidity sensor unit are different, and the analysis processing unit corrects and outputs the measured values of the first humidity sensor unit and the second humidity sensor unit.
2. The drift-free humidity sensor of claim 1, wherein: the first measuring electrode (101) comprises a first measuring positive electrode (1011) and a first measuring negative electrode (1012), and interdigital electrodes (212) are arranged on the first measuring positive electrode (1011) and the first measuring negative electrode (1012);
the second measuring electrode (102) is formed by combining a second measuring positive electrode (1021) and a second measuring negative electrode (1022), the second measuring positive electrode (1021) and the second measuring negative electrode (1022) are both provided with interdigital electrodes (212),
the interdigital electrodes (212) are arranged in a staggered manner.
3. The drift-free humidity sensor of claim 1, wherein: the first measuring electrode (101) and the second measuring electrode (102) are capacitive electrodes; alternatively, the first measuring electrode (101) and the second measuring electrode (102) are resistive electrodes.
4. The drift-free humidity sensor of claim 3, wherein: the first measuring electrode (101) and the second measuring electrode (102) are capacitance type electrodes, a passivation layer (211) is arranged between one surface of the first measuring electrode (101) and the first humidity sensitive material (201), a dielectric layer (213) and a substrate silicon wafer (214) are sequentially arranged on the other surface of the first measuring electrode (101), and the dielectric layer (213) is filled between the first measuring electrode (101) and the substrate silicon wafer (214);
a passivation layer (211) is arranged between one surface of the second measuring electrode (102) and the second humidity-sensitive material (202), a dielectric layer (213) and a substrate silicon wafer (214) are sequentially arranged on the other surface of the second measuring electrode (102), and the dielectric layer (213) is filled between the second measuring electrode (102) and the substrate silicon wafer (214).
5. The drift-free humidity sensor of claim 3, wherein: the first measuring electrode (101) and the second measuring electrode (102) are resistance type electrodes, the first humidity sensitive material (201) is arranged on one surface of the first measuring electrode (101), a dielectric layer (213) and a substrate silicon wafer (214) are sequentially arranged on the other surface of the first measuring electrode (101), and the dielectric layer (213) is filled between the first measuring electrode (101) and the substrate silicon wafer (214);
the second humidity-sensitive material (202) is arranged on one surface of the second measuring electrode (102), a dielectric layer (213) and a substrate silicon wafer (214) are sequentially arranged on the other surface of the second measuring electrode (102), and the dielectric layer (213) is filled between the second measuring electrode (102) and the substrate silicon wafer (214).
6. The drift-free humidity sensor of claim 4, wherein: the first humidity sensitive material (201) and the second humidity sensitive material (202) are photosensitive humidity sensitive materials or non-photosensitive humidity sensitive materials, and the processing method of the first humidity sensitive material (201) and the second humidity sensitive material (202) comprises the following steps:
-if the first moisture sensitive material (201) and the second moisture sensitive material (202) are both photosensitive moisture sensitive materials, obtaining the pattern by direct lithography;
-if one of the first moisture sensitive material (201) or the second moisture sensitive material (202) is a non-photosensitive moisture sensitive material, the processing method comprises:
step S1.1: spin-coating a non-photosensitive humidity-sensitive material on the passivation layer (211) of the first measuring electrode (101) and the second measuring electrode (102) and curing, then spin-coating a photoresist on the non-photosensitive humidity-sensitive material, photoetching a required pattern, processing by a dry etching process, and finally removing the photoresist to finish the processing of the humidity-sensitive material;
step S1.2: spin-coating a photosensitive moisture-sensitive material, patterning in a photoetching mode, and curing the photosensitive moisture-sensitive material to obtain another moisture-sensitive material;
-if the first moisture sensitive material (201) and the second moisture sensitive material (202) are both non-photosensitive moisture sensitive materials, the processing method comprises:
step S2.1: a first humidity sensitive material (201) is spin-coated on a passivation layer (211) of two measuring electrodes and is solidified, the thickness of the first humidity sensitive material (201) is more than one time of the sum of the width and the margin of an interdigital electrode (212), then photoresist is spin-coated on the first photosensitive humidity sensitive material, a required pattern is photoetched, the photoresist is processed through a dry etching process, and finally the photoresist is removed, so that the processing of the first humidity sensitive material (201) is completed;
step S2.2: and spin-coating a second humidity-sensitive material (202) and curing, then spin-coating a photoresist on the second humidity-sensitive material (202), photoetching a required pattern, processing by a dry etching process, reserving the second humidity-sensitive material (202) attached to the first humidity-sensitive material (201), and finally removing the photoresist to finish processing the second humidity-sensitive material (202).
7. The drift-free humidity sensor of claim 5, wherein: the first humidity sensitive material (201) and the second humidity sensitive material (202) are photosensitive humidity sensitive materials; or any one of the first humidity-sensitive material (201) and the second humidity-sensitive material (202) is a non-photosensitive humidity-sensitive material, and the other one is a photosensitive humidity-sensitive material; the method of processing the first moisture sensitive material (201) and the second moisture sensitive material (202) comprises:
-if the first moisture sensitive material (201) and the second moisture sensitive material (202) are both photosensitive moisture sensitive materials, obtaining the pattern by direct lithography;
-if one of the first moisture sensitive material (201) or the second moisture sensitive material (202) is a non-photosensitive moisture sensitive material, processing by:
step S3.1: spin-coating a non-photosensitive humidity-sensitive material on a first measuring electrode (101) and a second measuring electrode (102) and curing, then spin-coating a photoresist on the non-photosensitive humidity-sensitive material, photoetching to obtain a required pattern, processing by a dry etching process, and finally removing the photoresist to finish processing the humidity-sensitive material;
step S3.2: spin-coating a photosensitive moisture-sensitive material, patterning in a photoetching mode, and curing the photosensitive moisture-sensitive material to obtain another moisture-sensitive material;
-if the first moisture sensitive material (201) and the second moisture sensitive material (202) are both non-photosensitive moisture sensitive materials, the processing method comprises:
step S4.1: a first non-photosensitive moisture-sensitive material is spin-coated on a first measuring electrode (101) and a second measuring electrode (102) and is cured, then photoresist is spin-coated on the non-photosensitive moisture-sensitive material, a required pattern is photoetched, the photoresist is removed through dry etching, and the processing of the moisture-sensitive material is completed;
step S4.2: spin-coating a second non-photosensitive moisture-sensitive material, then spin-coating a photoresist, patterning in a photoetching mode, etching the second non-photosensitive material while developing the photoresist by using alkaline developer (TMAH), removing the photoresist, and curing the second moisture-sensitive material to obtain the other moisture-sensitive material.
8. The drift-free humidity sensor of claim 1, wherein: the humidity sensor adopts a differential sampling structure, wherein the first humidity sensor unit comprises a first sensing subunit (111) and a second sensing subunit (112), and the second humidity sensor unit comprises a third sensing subunit (113) and a fourth sensing subunit (114).
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210196787.8A CN114705724A (en) | 2022-03-01 | 2022-03-01 | No-drift humidity sensor |
| PCT/CN2022/126889 WO2023165144A1 (en) | 2022-03-01 | 2022-10-24 | Drift-free humidity sensor and calibration method |
| US18/284,556 US20240175833A1 (en) | 2022-03-01 | 2022-10-24 | Drift-Free Humidity Sensor And Calibration Method Thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2023165144A1 (en) * | 2022-03-01 | 2023-09-07 | 上海申矽凌微电子科技股份有限公司 | Drift-free humidity sensor and calibration method |
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| WO2023165144A1 (en) * | 2022-03-01 | 2023-09-07 | 上海申矽凌微电子科技股份有限公司 | Drift-free humidity sensor and calibration method |
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