WO2011065507A1 - Humidity detection sensor - Google Patents

Humidity detection sensor Download PDF

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Publication number
WO2011065507A1
WO2011065507A1 PCT/JP2010/071175 JP2010071175W WO2011065507A1 WO 2011065507 A1 WO2011065507 A1 WO 2011065507A1 JP 2010071175 W JP2010071175 W JP 2010071175W WO 2011065507 A1 WO2011065507 A1 WO 2011065507A1
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Prior art keywords
humidity
region
moisture sensitive
sensitive film
detection sensor
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PCT/JP2010/071175
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French (fr)
Japanese (ja)
Inventor
澄人 森田
聡 和賀
崇 佐藤
英紀 牛膓
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アルプス電気株式会社
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Application filed by アルプス電気株式会社 filed Critical アルプス電気株式会社
Priority to CN201080040905.1A priority Critical patent/CN102549416B/en
Priority to JP2011543336A priority patent/JP5470512B2/en
Publication of WO2011065507A1 publication Critical patent/WO2011065507A1/en

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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
    • G01N27/22—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

Definitions

  • the present invention relates to a humidity detection sensor using a polymer moisture sensitive film as a dielectric.
  • Humidity detection sensors used for humidity change measurement include capacitive humidity detection sensors in which a polymer moisture sensitive film whose dielectric constant changes according to the amount of absorbed or released water is used as a dielectric.
  • the capacitive humidity detection sensor includes a sensor unit whose capacitance changes in accordance with the humidity, and a reference unit which holds a constant capacitance regardless of the humidity, and it is between the sensor unit and the reference unit. Convert the capacity difference into a voltage and output it.
  • the sensor unit and the reference unit have a laminated structure formed by sandwiching a polymer moisture sensitive film between a pair of electrodes and laminating a protective layer thereon. As such a humidity detection sensor, there is, for example, one described in Patent Document 1.
  • the polymer moisture sensitive film is exposed to expose the polymer moisture sensitive film of the sensor portion to the outside. It is necessary to partially remove the electrode formed above. In this case, it is conceivable to remove the electrode layer by dry etching such as milling after the electrode layer is formed on the polymer moisture sensitive film.
  • the sensitivity of the humidity detection sensor may vary.
  • the present invention has been made in view of the foregoing, and it is an object of the present invention to provide a parallel plate type humidity detection sensor free from variations in sensitivity.
  • the humidity detection sensor includes a substrate and a polymer moisture sensitive film provided on the substrate and having a dielectric constant that changes in accordance with the humidity sandwiched between a pair of electrodes, and the polymer moisture sensitive film is partially A sensor unit having a humidity sensitive region exposed to the outside, and a protective layer formed on at least the upper electrode of the pair of electrodes, wherein the pair of electrodes are in a region other than the humidity sensitive region. And a region having a polymer moisture sensitive film having a thickness substantially the same as the thickness of the polymer moisture sensitive film sandwiched therebetween, in the vicinity of the upper electrode.
  • the region having the polymeric moisture sensitive film having substantially the same thickness as the thickness of the polymeric moisture sensitive film sandwiched by the pair of electrodes is provided. It is possible to secure a path of a leaked electric field when an electric field is applied between the upper electrode and the lower electrode in the moisture sensitive film. As a result, the variation in sensitivity of the humidity detection sensor can be reduced.
  • the width of the region is a width including a leak region of a magnetic field between at least the pair of electrodes.
  • the electrode on the polymer moisture sensitive film is patterned by photolithography and etching.
  • the electrode on the polymer moisture sensitive film is constituted of a seed layer patterned by photolithography and etching, and a plating layer formed on the seed layer. Is preferred.
  • the substrate and the polymer moisture sensitive film provided on the substrate and whose dielectric constant changes according to the humidity are sandwiched between a pair of electrodes, and the polymer moisture sensitive film is a part A sensor portion having a humidity sensitive area exposed to the outside, and a protective layer formed on the upper electrode of at least the pair of electrodes, wherein the pair is formed in an area other than the humidity sensitive area Since a region having a polymer moisture sensitive film having a thickness substantially the same as the thickness of the polymer moisture sensitive film sandwiched between the electrodes is provided in the vicinity of the upper electrode, a parallel plate humidity detection sensor without variation in sensitivity is obtained. It can be realized.
  • FIG. 1 It is a block diagram showing composition of a humidity detection sensor concerning an embodiment of the invention. It is a top view which shows the sensor part and reference part of a humidity detection sensor concerning an embodiment of the invention.
  • (A), (b) is sectional drawing which shows the structure of the area
  • (A) to (e) are cross-sectional views for explaining a method of manufacturing the humidity detection sensor according to the embodiment of the present invention.
  • FIG. 1 is a block diagram showing a configuration of a humidity detection sensor according to an embodiment of the present invention.
  • the humidity detection sensor shown in FIG. 1 is a polymer film humidity sensor using a polymer moisture sensitive material whose dielectric constant changes in accordance with the amount of absorbed or released water.
  • the humidity detection sensor includes a sensor unit 20 having a capacitance C 20 that changes with humidity, a reference unit 30 that holds a constant capacitance C 30 regardless of humidity, and the sensor unit 20.
  • the circuit unit 40 is provided with a connection pad 40 a for connection to an external circuit.
  • An external circuit connected to the humidity detection sensor via the pad 40a detects a humidity change (relative humidity) from the output of the humidity detection sensor (voltage corresponding to the capacitance difference ⁇ C).
  • FIG. 2 is a plan view showing a sensor unit and a reference unit of the humidity detection sensor according to the embodiment of the present invention.
  • the right side is the sensor unit 20 and the left side is the reference unit 30.
  • the sensor unit 20 and the reference unit 30 have a structure in which a lower electrode, a polymer moisture sensitive film 54 and an upper electrode are stacked. That is, the sensor unit 20 and the reference unit 30 have a parallel plate structure in which a polymer moisture sensitive film whose dielectric constant changes according to humidity is sandwiched between a pair of electrodes (lower electrode and upper electrode).
  • the lower electrode 53 is formed on the substrate 51 with the thermal oxide film 52 interposed therebetween.
  • a polymer moisture sensitive film 54 whose dielectric constant changes according to humidity is formed on the lower electrode 53, and an upper electrode 55 is partially formed on the polymer moisture sensitive film 54.
  • a protective layer 56 for protecting the exposed upper electrode 55 is formed.
  • a plurality of openings 54 a for exposing the polymer moisture sensitive film 54 to the outside are formed in the moisture sensitive region A of the upper electrode 55 (a region where the polymer moisture sensitive film 54 is partially exposed to the outside).
  • the protective layer 56 is also provided with a plurality of openings for exposing the polymer moisture sensitive film 54 to the outside.
  • the openings 54a are arranged side by side at predetermined intervals in the left and right and up and down directions, and have a rectangular planar shape.
  • the number, planar shape and formation position of the openings 54a are arbitrary.
  • the present inventors can not remove only the upper electrode 55 if the upper electrode 55 is partially removed in the sensor part by milling, and the polymer moisture sensitive film 54 is also removed. I focused on things.
  • the thickness of the polymer moisture sensitive film 54 in the region (humidity region) where the upper electrode 55 does not exist becomes thin, that is, the polymer sandwiched between the lower electrode 53 and the upper electrode 55
  • the thickness of the moisture sensitive film 54 (the region other than the moisture sensitive region) is different from the thickness of the region where the upper electrode 55 is not present (the moisture sensitive region).
  • the thickness of the polymer moisture sensitive film in the region other than the moisture sensitive region is different from the thickness of the polymer moisture sensitive film in the moisture sensitive region as described above, that is, the polymer moisture sensitive film It has been found that the variation in the thickness of 54 (with the thickness distribution) causes variation in the sensitivity of the humidity detection sensor.
  • the polymer moisture sensitive film is actually scraped in the range of 85 nm to 115 nm in the wafer (the milling distribution is 10% of the total amount of milling) Become).
  • the capacity decreases by 41.2 fF when the polymer moisture sensitive film is scraped by 200 nm in the device design shown in FIG. 2, so the capacity changes by 6.18 fF with a film thickness change of 85 nm to 115 nm. It will be. Since the sensitivity (rate of change of capacitance) of the element is determined with respect to the element capacitance, the variation of 6.18 fF leads directly to the sensitivity variation. For example, when the element capacitance is 200 fF and the capacitance change rate is 20%, the sensitivity is 0.4 fF /%. In addition, when there is no variation in the amount of scraping of the polymer moisture sensitive film, the sensitivity will also be uniform.
  • the present inventors set a region having a polymer moisture sensitive film having substantially the same thickness as the thickness of the polymeric moisture sensitive film sandwiched between the pair of electrodes in the vicinity of the upper electrode.
  • the region that is, by providing a region in which the volume of the polymer moisture sensitive film is secured in the vicinity of the upper electrode, it has been found that the variation in the sensitivity of the humidity detection sensor can be suppressed.
  • the region having the polymeric moisture sensitive film having substantially the same thickness as the thickness of the polymeric moisture sensitive film sandwiched between the pair of electrodes
  • This area B is located near the upper electrode 55 of the area C.
  • the thickness D 3 of polymer humidity-sensitive film 54 is thinner.
  • the width W of the region B is preferably a width including a leakage region of the electric field between at least the pair of electrodes 53 and 55 (a region capable of securing a path of the leakage electric field).
  • the electrode material is patterned by photolithography and etching to form the upper electrode 55.
  • the electrode material is deposited to form a plating seed layer, and the plating seed layer is patterned by photolithography. Thereafter, electroplating is performed using the resist as a frame, and a plating layer is formed on the plating seed layer to form an upper electrode.
  • the plating seed layer protects the plating layer and is removed by etching in a wet process.
  • the lower electrode is formed on the substrate via the thermal oxide film.
  • a polymeric moisture-sensitive film is formed on the lower electrode so as to cover the entire lower electrode.
  • An upper electrode is formed on the polymer moisture sensitive film so as to cover the entire polymer moisture sensitive film.
  • a protective layer is formed on the entire reference portion 30 to protect the exposed upper electrode.
  • a substrate eg, a silicon substrate or the like whose surface is protected by an insulator can be used.
  • a material which comprises the lower electrode 52 and the upper electrode 55 Al, AlCu, Ta, Ti, NiFe, Ni etc. can be used, for example.
  • a material for forming the polymeric moisture sensitive film 54 polyimide or the like which can be easily patterned can be used.
  • the protective layer 56 for example, a silicon nitride (SiNx) film, an SiO 2 film, an Al 2 O 3 / SiO 2 laminated film, an SiO 2 / SiN laminated film, or the like can be used.
  • the lower electrode 21 is provided commonly to the sensor unit 20 and the reference unit 30.
  • a lower electrode wire is drawn out from a substantially middle position between the sensor unit 20 and the reference unit 30, and the lower electrode wire is connected to the electrode pad 40 a of the circuit unit 40.
  • the polymer moisture sensitive film 54 and the upper electrode 55 are separately provided in the sensor unit 20 and the reference unit 30.
  • the upper electrode wiring is provided on the upper electrode 55 to connect the upper electrode 55 and the electrode pad 40 a of the circuit unit 40.
  • the upper electrode wiring is a wiring pattern extending from the pair of upper electrodes 55 with a fixed width, and the width is adjusted so that parasitic capacitances generated in the sensor unit 20 and the reference unit 30 become the same. ing. Thus, it is possible to reduce variations in sensor capacitance C 20 and the reference capacitance C 30 due to parasitic capacitance.
  • the humidity detection sensor having the above configuration detects humidity as follows. First, in the sensor unit 20, the polymer moisture sensitive film 54 is exposed to the outside through the opening 54a in the moisture sensitive region A. For this reason, the amount of moisture absorbed or released in the polymer moisture sensitive film 54 changes in accordance with the humidity (the amount of water) in the atmosphere, and the dielectric constant ⁇ changes. Therefore, the capacitance C 20 between the lower electrode 53 and the upper electrode 55 changes. On the other hand, in the reference portion 30, the polymer moisture sensitive film 54 is not exposed to the outside, so the moisture content in the polymer moisture sensitive film 54 does not change even if the humidity (water content) in the atmosphere changes. Also ⁇ does not change.
  • a constant capacitance C 30 is held between the lower electrode 53 and the upper electrode 55. Then, by obtaining a capacitance difference between the electrostatic capacitance C 30 of the capacitance C 20 and the reference portion 30 of the sensor unit 20 may measure the changed capacitance (difference value) by humidity.
  • the present humidity detection sensor is configured to convert this difference value into a voltage and output it.
  • 4 (a) to 4 (e) are cross-sectional views for explaining the method of manufacturing the humidity detection sensor according to the embodiment of the present invention.
  • the silicon substrate 51 is thermally oxidized to form a thermal oxide film (SiO 2 film) 52.
  • the lower electrode 53 is formed on the thermal oxide film 52. That is, the lower electrode 53 is formed by depositing an electrode material on the entire surface of the silicon substrate 51 having the thermal oxide film 52, forming a resist layer thereon, patterning it as a mask, and etching the electrode material through the mask It forms by doing.
  • the lower electrode 53 is common to the sensor unit 20 and the reference unit 30. When the lower electrode 53 is formed, the wiring conductor of the circuit section 40 and the pad 40a are simultaneously formed.
  • the polymer moisture sensitive film 54 is formed on the lower electrode 53 in the sensor unit 20 and the reference unit 30 so as to cover the lower electrode 53. That is, the polymer moisture sensitive film 54 is formed by applying and curing a polymer material (for example, polyimide) on the entire surface of the silicon substrate 51, forming a resist layer thereon, patterning it as a mask, and using the mask It is formed by etching a polymer material. Alternatively, the polymeric moisture-sensitive film 54 is formed by forming a pattern by photolithography using a photosensitive polymeric material and curing the polymeric material. The polymeric moisture sensitive film 54 is individual in each of the sensor unit 20 and the reference unit 30.
  • a polymer material for example, polyimide
  • the upper electrode 55 is formed on the polymer moisture sensitive film 54 in the sensor unit 20 and the reference unit 30 so as to cover the polymer moisture sensitive film 54. That is, the upper electrode 55 is formed by depositing an electrode material on the entire surface of the silicon substrate 51, forming a resist layer thereon, patterning it as a mask, and etching the electrode material through the mask. Thus, the opening 55 a (width corresponding to the humidity sensitive region A + region B) is formed in the upper electrode 55.
  • the upper electrode 55 is individual in each of the sensor unit 20 and the reference unit 30.
  • the protective layer forming material is deposited on the entire humidity detection sensor to form the protective layer 56 on the sensor unit 20 and the reference unit 30.
  • the openings 56a and 54a are formed by anisotropic etching such as dry etching with the region (region B + region C) other than the moisture sensitive region A masked.
  • the humidity of the present invention having a region B having a thickness D 1 substantially equal thickness D 2 of the polymer humidity-sensitive film 54 of polymer humidity-sensitive film 54 which is sandwiched by a pair of electrodes 53 and 55 A detection sensor can be made.
  • variation in a sensitivity was investigated. The variation in sensitivity was measured by an LCR meter. As a result, the sensitivity variation was 6%, which was very small.
  • a humidity detection sensor was manufactured in the same manner as in the example except that the region B was not present in the vicinity of the upper electrode, that is, the upper electrode was partially removed by milling.
  • variation in a sensitivity was investigated like the Example. As a result, the sensitivity variation was 11%, which was very large.
  • the humidity detection sensor according to the present invention in the area other than the moisture sensitive area, the area having the polymer moisture sensitive film having substantially the same thickness as the thickness of the polymer moisture sensitive film sandwiched between the pair of electrodes. Since it is in the vicinity of the upper electrode, it is possible to secure a path of a leaked electric field when an electric field is applied between the upper electrode and the lower electrode in the polymer moisture sensitive film. As a result, the variation in sensitivity of the humidity detection sensor can be reduced. As described above, according to the present invention, it is possible to realize a parallel plate type humidity detection sensor with no sensitivity variation.
  • the present invention is not limited to the above embodiment, and can be implemented with appropriate modifications.
  • the humidity detection sensor provided with the sensor unit and the reference unit is described, the present invention is not limited to this, and the present invention is similarly applied to a humidity detection sensor composed of only the sensor unit. can do.
  • the materials, the arrangement position of each layer, the thickness, the size, the manufacturing method, and the like in the above-described embodiment can be appropriately changed and implemented.
  • the present invention can be implemented with appropriate modifications without departing from the scope of the present invention.

Abstract

Disclosed is a humidity detection sensor having a parallel flat plate shape in which there is no variability of sensitivity. The humidity detection sensor includes: a substrate (51); a sensor unit which has a humidity-sensitive region (A) wherein a humidity-sensitive polymer film (54) having a dielectric constant that varies in accordance with humidity is disposed on the substrate (51) and held between a pair of electrodes (53), (55), the humidity-sensitive polymer film (54) being partially exposed to the external environment; and a protective layer (56) which is formed at least on the upper electrode (55) of the pair of electrodes. The humidity detection sensor has a region (C) which includes a humidity-sensitive polymer film (54) of substantially the same thickness as the thickness of the humidity-sensitive polymer film (54) held between the pair of electrodes, and which is in the vicinity of the upper electrode (55), within the region (region (B) + region (C)) other than the humidity-sensitive region (A).

Description

湿度検出センサHumidity detection sensor
　本発明は、高分子感湿膜を誘電体とした湿度検出センサに関する。 The present invention relates to a humidity detection sensor using a polymer moisture sensitive film as a dielectric.
　湿度変化測定に用いられる湿度検出センサには、吸収又は放出した水分量に応じて誘電率が変化する高分子感湿膜を誘電体とした静電容量型の湿度検出センサがある。容量型湿度検出センサは、湿度に応じて静電容量が変化するセンサ部と、湿度によらず一定の静電容量を保持する基準部とを備えており、センサ部と基準部との間の容量差分を電圧に変換して出力する。センサ部及び基準部は、高分子感湿膜を一対の電極で挟持し、その上に保護層を積層してなる積層構造を有する。このような湿度検出センサとしては、例えば特許文献１に記載されているものがある。 Humidity detection sensors used for humidity change measurement include capacitive humidity detection sensors in which a polymer moisture sensitive film whose dielectric constant changes according to the amount of absorbed or released water is used as a dielectric. The capacitive humidity detection sensor includes a sensor unit whose capacitance changes in accordance with the humidity, and a reference unit which holds a constant capacitance regardless of the humidity, and it is between the sensor unit and the reference unit. Convert the capacity difference into a voltage and output it. The sensor unit and the reference unit have a laminated structure formed by sandwiching a polymer moisture sensitive film between a pair of electrodes and laminating a protective layer thereon. As such a humidity detection sensor, there is, for example, one described in Patent Document 1.
特開平６－１３８０７４号公報JP-A-6-138074
　上記湿度検出センサにおいて、高分子感湿膜を一対の電極で挟持する平行平板型の電極構造を採用する場合、センサ部の高分子感湿膜を外界に露出させるために、高分子感湿膜上に形成された電極を部分的に除去する必要がある。この場合、高分子感湿膜上に電極層を形成した後に、この電極層をミリング加工などのドライエッチング法で除去することが考えられる。 In the case of adopting the parallel plate type electrode structure in which the polymer moisture sensitive film is sandwiched between a pair of electrodes in the above humidity detection sensor, the polymer moisture sensitive film is exposed to expose the polymer moisture sensitive film of the sensor portion to the outside. It is necessary to partially remove the electrode formed above. In this case, it is conceivable to remove the electrode layer by dry etching such as milling after the electrode layer is formed on the polymer moisture sensitive film.
　しかしながら、高分子感湿膜上の電極層をミリングにより除去すると、その際に高分子感湿膜もミリングされてしまい、高分子感湿膜がミリングによる厚さ分布を持ってしまう。このように高分子感湿膜が厚さ分布を有すると、湿度検出センサの感度にばらつきが生じることとなる。 However, when the electrode layer on the polymer moisture sensitive film is removed by milling, the polymer moisture sensitive film is also milled at that time, and the polymer moisture sensitive film has a thickness distribution due to milling. As described above, when the polymer moisture sensitive film has a thickness distribution, the sensitivity of the humidity detection sensor may vary.
　本発明はかかる点に鑑みてなされたものであり、感度ばらつきのない平行平板型の湿度検出センサを提供することを目的とする。 The present invention has been made in view of the foregoing, and it is an object of the present invention to provide a parallel plate type humidity detection sensor free from variations in sensitivity.
　本発明の湿度検出センサは、基板と、前記基板上に設けられ、湿度に応じて誘電率が変化する高分子感湿膜を一対の電極で挟持し、前記高分子感湿膜が部分的に外界に露出する感湿領域を持つセンサ部と、少なくとも前記一対の電極のうちの上側の電極上に形成された保護層と、を具備し、前記感湿領域以外の領域において、前記一対の電極で挟持された高分子感湿膜の厚さと略同じ厚さの高分子感湿膜を有する領域を前記上側の電極の近傍に有することを特徴とする。 The humidity detection sensor according to the present invention includes a substrate and a polymer moisture sensitive film provided on the substrate and having a dielectric constant that changes in accordance with the humidity sandwiched between a pair of electrodes, and the polymer moisture sensitive film is partially A sensor unit having a humidity sensitive region exposed to the outside, and a protective layer formed on at least the upper electrode of the pair of electrodes, wherein the pair of electrodes are in a region other than the humidity sensitive region. And a region having a polymer moisture sensitive film having a thickness substantially the same as the thickness of the polymer moisture sensitive film sandwiched therebetween, in the vicinity of the upper electrode.
　この構成によれば、感湿領域以外の領域において、一対の電極で挟持された高分子感湿膜の厚さと略同じ厚さの高分子感湿膜を有する領域を設けているので、高分子感湿膜における、上部電極と下部電極との間に電界が印加されたときの漏れ電界のパスを確保することができる。その結果、湿度検出センサの感度のばらつきを小さくすることが可能となる。 According to this configuration, in the region other than the moisture sensitive region, the region having the polymeric moisture sensitive film having substantially the same thickness as the thickness of the polymeric moisture sensitive film sandwiched by the pair of electrodes is provided. It is possible to secure a path of a leaked electric field when an electric field is applied between the upper electrode and the lower electrode in the moisture sensitive film. As a result, the variation in sensitivity of the humidity detection sensor can be reduced.
　本発明の湿度検出センサにおいては、前記領域の幅は、少なくとも前記一対の電極間の磁界の漏れ領域を含む幅であることが好ましい。 In the humidity detection sensor according to the present invention, preferably, the width of the region is a width including a leak region of a magnetic field between at least the pair of electrodes.
　本発明の湿度検出センサにおいては、前記高分子感湿膜上の電極は、フォトリソグラフィー及びエッチングによりパターニングされてなることが好ましい。 In the humidity detection sensor of the present invention, it is preferable that the electrode on the polymer moisture sensitive film is patterned by photolithography and etching.
　本発明の湿度検出センサにおいては、前記高分子感湿膜上の電極は、フォトリソグラフィー及びエッチングによりパターニングされてなるシード層と、前記シード層上に形成されためっき層とで構成されていることが好ましい。 In the humidity detection sensor according to the present invention, the electrode on the polymer moisture sensitive film is constituted of a seed layer patterned by photolithography and etching, and a plating layer formed on the seed layer. Is preferred.
　本発明の湿度検出センサによれば、基板と、前記基板上に設けられ、湿度に応じて誘電率が変化する高分子感湿膜を一対の電極で挟持し、前記高分子感湿膜が部分的に外界に露出する感湿領域を持つセンサ部と、少なくとも前記一対の電極のうちの上側の電極上に形成された保護層と、を具備し、前記感湿領域以外の領域において、前記一対の電極で挟持された高分子感湿膜の厚さと略同じ厚さの高分子感湿膜を有する領域を前記上側の電極の近傍に有するので、感度ばらつきのない平行平板型の湿度検出センサを実現することができる。 According to the humidity detection sensor of the present invention, the substrate and the polymer moisture sensitive film provided on the substrate and whose dielectric constant changes according to the humidity are sandwiched between a pair of electrodes, and the polymer moisture sensitive film is a part A sensor portion having a humidity sensitive area exposed to the outside, and a protective layer formed on the upper electrode of at least the pair of electrodes, wherein the pair is formed in an area other than the humidity sensitive area Since a region having a polymer moisture sensitive film having a thickness substantially the same as the thickness of the polymer moisture sensitive film sandwiched between the electrodes is provided in the vicinity of the upper electrode, a parallel plate humidity detection sensor without variation in sensitivity is obtained. It can be realized.
本発明の実施の形態に係る湿度検出センサの構成を示すブロック図である。It is a block diagram showing composition of a humidity detection sensor concerning an embodiment of the invention. 本発明の実施の形態に係る湿度検出センサのセンサ部及び基準部を示す平面図である。It is a top view which shows the sensor part and reference part of a humidity detection sensor concerning an embodiment of the invention. （ａ），（ｂ）は、本発明の実施の形態に係る湿度検出センサの感湿領域以外の領域の構造を示す断面図である。(A), (b) is sectional drawing which shows the structure of the area | regions other than the moisture sensitivity area | region of the humidity detection sensor which concerns on embodiment of this invention. （ａ）～（ｅ）は、本発明の実施の形態に係る湿度検出センサの製造方法を説明するための断面図である。(A) to (e) are cross-sectional views for explaining a method of manufacturing the humidity detection sensor according to the embodiment of the present invention.
　以下、本発明の実施の形態について、添付図面を参照して詳細に説明する。
　図１は、本発明の実施の形態に係る湿度検出センサの構成を示すブロック図である。図１に示す湿度検出センサは、吸収又は放出した水分量に応じて誘電率が変化する高分子感湿材料を用いた高分子膜湿度センサである。この湿度検出センサは、基板１０上に、湿度によって静電容量Ｃ２０が変化するセンサ部２０と、湿度によらず一定の静電容量Ｃ３０を保持する基準部３０と、このセンサ部２０と基準部３０とに電気的に接続し、該センサ部２０と基準部３０との間の容量差分ΔＣ（＝Ｃ２０－Ｃ３０）を電圧に変換して外部回路に出力する回路部４０とを有している。 Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.
FIG. 1 is a block diagram showing a configuration of a humidity detection sensor according to an embodiment of the present invention. The humidity detection sensor shown in FIG. 1 is a polymer film humidity sensor using a polymer moisture sensitive material whose dielectric constant changes in accordance with the amount of absorbed or released water. The humidity detection sensor includes a sensor unit 20 having a capacitance C 20 that changes with humidity, a reference unit 30 that holds a constant capacitance C 30 regardless of humidity, and the sensor unit 20. And a circuit unit 40 which is electrically connected to the reference unit 30 and converts the capacitance difference ΔC (= C 20 -C 30 ) between the sensor unit 20 and the reference unit 30 into a voltage and outputs the voltage to an external circuit. Have.
　回路部４０には、外部回路との接続用パッド４０ａが設けられている。パッド４０ａを介して湿度検出センサに接続された外部回路において、湿度検出センサの出力（容量差分ΔＣに対応する電圧）から湿度変化（相対湿度）を検出する。 The circuit unit 40 is provided with a connection pad 40 a for connection to an external circuit. An external circuit connected to the humidity detection sensor via the pad 40a detects a humidity change (relative humidity) from the output of the humidity detection sensor (voltage corresponding to the capacitance difference ΔC).
　図２は、本発明の実施の形態に係る湿度検出センサのセンサ部及び基準部を示す平面図である。図２において、右側がセンサ部２０であり、左側が基準部３０である。センサ部２０及び基準部３０は、下部電極、高分子感湿膜５４及び上部電極が積層された構造を有する。すなわち、センサ部２０及び基準部３０は、湿度に応じて誘電率が変化する高分子感湿膜を一対の電極（下部電極及び上部電極）で挟持してなる平行平板構造を有する。 FIG. 2 is a plan view showing a sensor unit and a reference unit of the humidity detection sensor according to the embodiment of the present invention. In FIG. 2, the right side is the sensor unit 20 and the left side is the reference unit 30. The sensor unit 20 and the reference unit 30 have a structure in which a lower electrode, a polymer moisture sensitive film 54 and an upper electrode are stacked. That is, the sensor unit 20 and the reference unit 30 have a parallel plate structure in which a polymer moisture sensitive film whose dielectric constant changes according to humidity is sandwiched between a pair of electrodes (lower electrode and upper electrode).
　湿度により静電容量が変化するセンサ部２０においては、図３（ａ），（ｂ）に示すように、基板５１上に熱酸化膜５２を介して下部電極５３が形成されている。下部電極５３上には、湿度に応じて誘電率が変化する高分子感湿膜５４が形成されており、高分子感湿膜５４上には、部分的に上部電極５５が形成されている。さらに、図３（ｂ）に示すように、露出した上部電極５５を保護するための保護層５６が形成されている。上部電極５５の感湿領域Ａ（高分子感湿膜５４が部分的に外界に露出する領域）には、高分子感湿膜５４を外界に露出させる複数の開口部５４ａが形成されている。なお、保護層５６にも高分子感湿膜５４を外界に露出させる複数の開口部が形成されている。開口部５４ａは、図３(ｂ)に示すように、左右上下方向に所定間隔をあけて並設されており、平面矩形状をなしている。この開口部５４ａの数、平面形状及び形成位置は任意である。 In the sensor unit 20 in which the capacitance changes with humidity, as shown in FIGS. 3A and 3B, the lower electrode 53 is formed on the substrate 51 with the thermal oxide film 52 interposed therebetween. A polymer moisture sensitive film 54 whose dielectric constant changes according to humidity is formed on the lower electrode 53, and an upper electrode 55 is partially formed on the polymer moisture sensitive film 54. Furthermore, as shown in FIG. 3B, a protective layer 56 for protecting the exposed upper electrode 55 is formed. A plurality of openings 54 a for exposing the polymer moisture sensitive film 54 to the outside are formed in the moisture sensitive region A of the upper electrode 55 (a region where the polymer moisture sensitive film 54 is partially exposed to the outside). The protective layer 56 is also provided with a plurality of openings for exposing the polymer moisture sensitive film 54 to the outside. As shown in FIG. 3B, the openings 54a are arranged side by side at predetermined intervals in the left and right and up and down directions, and have a rectangular planar shape. The number, planar shape and formation position of the openings 54a are arbitrary.
　本発明者らは、センサ部において上部電極５５を部分的に除去する際に、ミリング加工を採用すると、上部電極５５のみを除去することができず、高分子感湿膜５４も除去してしまうことに着目した。ミリング加工を行うと、上部電極５５が存在しない領域（感湿領域）の高分子感湿膜５４の厚さが薄くなってしまう、すなわち、下部電極５３と上部電極５５とで挟持された高分子感湿膜５４（感湿領域以外の領域）の厚さと、上部電極５５が存在しない領域（感湿領域）の厚さとが異なってしまう。そして、本発明者らは、このように感湿領域以外の領域の高分子感湿膜の厚さと、感湿領域の高分子感湿膜の厚さとが異なると、すなわち、高分子感湿膜５４の厚さにばらつきが生じると（厚さ分布を持つと）、湿度検出センサの感度にばらつきが生じることを見出した。 The present inventors can not remove only the upper electrode 55 if the upper electrode 55 is partially removed in the sensor part by milling, and the polymer moisture sensitive film 54 is also removed. I focused on things. When the milling process is performed, the thickness of the polymer moisture sensitive film 54 in the region (humidity region) where the upper electrode 55 does not exist becomes thin, that is, the polymer sandwiched between the lower electrode 53 and the upper electrode 55 The thickness of the moisture sensitive film 54 (the region other than the moisture sensitive region) is different from the thickness of the region where the upper electrode 55 is not present (the moisture sensitive region). And, if the thickness of the polymer moisture sensitive film in the region other than the moisture sensitive region is different from the thickness of the polymer moisture sensitive film in the moisture sensitive region as described above, that is, the polymer moisture sensitive film It has been found that the variation in the thickness of 54 (with the thickness distribution) causes variation in the sensitivity of the humidity detection sensor.
　ここで、上部電極をミリング加工で部分的に除去する場合の感度のばらつきについて説明する。すなわち、高分子感湿膜上に電極材料をスパッタリング法により成膜した後に、その上にレジスト層を形成し、感湿領域以外の領域にレジスト層が残存するようにレジスト層をパターニングし、残存したレジスト層をマスクとして電極材料をミリング加工して除去する。例えば、上部電極の膜厚を２００ｎｍとする場合、ミリング量はプロセスマージンを考慮して３００ｎｍと設定する。このため、この設定から高分子感湿膜は１００ｎｍ削られることになる。ただし、ミリング量には分布（約１０％）が生じるため、実際には高分子感湿膜はウェハ内で８５ｎｍ～１１５ｎｍの範囲で削られることになる（ミリング分布は総ミリング量の１０％となる）。 Here, variations in sensitivity in the case of partially removing the upper electrode by milling will be described. That is, after forming an electrode material on a polymer moisture sensitive film by sputtering, a resist layer is formed thereon, and the resist layer is patterned so that the resist layer remains in a region other than the moisture sensitive region, and remaining The electrode material is removed by milling using the formed resist layer as a mask. For example, when the film thickness of the upper electrode is 200 nm, the milling amount is set to 300 nm in consideration of the process margin. For this reason, the polymer moisture sensitive film is scraped 100 nm from this setting. However, since a distribution (about 10%) occurs in the amount of milling, the polymer moisture sensitive film is actually scraped in the range of 85 nm to 115 nm in the wafer (the milling distribution is 10% of the total amount of milling) Become).
　本発明者らの実験データから、図２に示す素子デザインで高分子感湿膜が２００ｎｍ削れると容量が４１．２ｆＦ減少することから、８５ｎｍ～１１５ｎｍの膜厚変化で容量が６．１８ｆＦ変化することになる。素子の感度（容量の変化率）は素子容量に対して決まっているので、上記６．１８ｆＦのばらつきはそのまま感度ばらつきにつながる。例えば、素子容量が２００ｆＦで容量変化率が２０％である場合、感度は０．４ｆＦ／％となる。また、高分子感湿膜の削れ量にばらつきが無い場合は、感度もばらつきが無いことになる。 From the experimental data of the present inventors, the capacity decreases by 41.2 fF when the polymer moisture sensitive film is scraped by 200 nm in the device design shown in FIG. 2, so the capacity changes by 6.18 fF with a film thickness change of 85 nm to 115 nm. It will be. Since the sensitivity (rate of change of capacitance) of the element is determined with respect to the element capacitance, the variation of 6.18 fF leads directly to the sensitivity variation. For example, when the element capacitance is 200 fF and the capacitance change rate is 20%, the sensitivity is 0.4 fF /%. In addition, when there is no variation in the amount of scraping of the polymer moisture sensitive film, the sensitivity will also be uniform.
　上記のばらつきを考慮して素子容量を計算すると、
　（１）２００－６．１８／２＝１９６．９１ｆＦ
　（２）２００＋６．１８／２＝２０３．０９ｆＦ
となり、感度は、
　（１）１９６．９１×０．２／１００＝０．３９３ｆＦ／％
　（２）２０３．０９×０．２／１００＝０．４０６ｆＦ／％
のばらつきとなる。すなわち、この上部電極形成工程のみで３％前後の感度ばらつきが生じることとなる。当然、ウェハ間の中心値もばらつきを持つことになるので、さらに感度ばらつきが大きくなる。 If the element capacitance is calculated in consideration of the above variation,
(1) 200-6.18 / 2 = 196.91 fF
(2) 200 + 6.18 / 2 = 203.09 fF
And the sensitivity is
(1) 196.91 × 0.2 / 100 = 0.393 fF /%
(2) 203.09 x 0.2 / 100 = 0.406 fF /%
Variation in That is, sensitivity variations of about 3% occur in this upper electrode formation step alone. Of course, since the center value between the wafers also has variations, the sensitivity variation is further increased.
　そこで、本発明者らは、感湿領域以外の領域において、一対の電極で挟持された高分子感湿膜の厚さと略同じ厚さの高分子感湿膜を有する領域を上部電極の近傍に有することにより、すなわち、上部電極の近傍において、高分子感湿膜の体積を確保した領域を設けることにより、湿度検出センサの感度にばらつきが抑えられることを見出して本発明をするに至った。 Therefore, in the region other than the moisture sensitive region, the present inventors set a region having a polymer moisture sensitive film having substantially the same thickness as the thickness of the polymeric moisture sensitive film sandwiched between the pair of electrodes in the vicinity of the upper electrode. By having the region, that is, by providing a region in which the volume of the polymer moisture sensitive film is secured in the vicinity of the upper electrode, it has been found that the variation in the sensitivity of the humidity detection sensor can be suppressed.
　すなわち、本発明の骨子は、感湿領域以外の領域において、一対の電極で挟持された高分子感湿膜の厚さと略同じ厚さの高分子感湿膜を有する領域を上部電極の近傍に有することにより、感度にばらつきの小さい、感度が安定した湿度検出センサを実現することである。 That is, in the region of the present invention, in the region other than the moisture sensitive region, the region having the polymeric moisture sensitive film having substantially the same thickness as the thickness of the polymeric moisture sensitive film sandwiched between the pair of electrodes By having it, it is implementing a humidity detection sensor with a small variation in sensitivity and stable sensitivity.
　図３（ｂ）に示すセンサ部２０においては、感湿領域Ａ以外の領域Ｂ＋領域Ｃ（参照符号５４ｂ）で、一対の電極５３，５５で挟持された高分子感湿膜５４の厚さＤ１と略同じ厚さＤ２の高分子感湿膜５４を有する領域Ｂを有する。この領域Ｂは、領域Ｃの上部電極５５の近傍に位置する。また、感湿領域Ａでは、高分子感湿膜５４の厚さＤ３が薄くなっている。このように、感湿領域Ａで高分子感湿膜５４の厚さＤ３が薄くなっていても、領域Ｂを設けることにより、高分子感湿膜５４における、上部電極５５と下部電極５３との間に電界が印加されたときの漏れ電界のパスを確保することができるので、湿度検出センサの感度のばらつきを小さくすることが可能となる。したがって、領域Ｂの幅Ｗは、少なくとも一対の電極５３，５５間の電界の漏れ領域（漏れ電界のパスを確保できる領域）を含む幅であることが好ましい。 In the sensor unit 20 shown in FIG. 3B, the thickness D of the polymeric moisture-sensitive film 54 sandwiched between the pair of electrodes 53 and 55 in the region B + region C (reference numeral 54b) other than the moisture-sensitive region A 1 as having a substantially region B having a polymer humidity-sensitive film 54 of the same thickness D 2. This area B is located near the upper electrode 55 of the area C. Further, in the humidity-sensing area A, the thickness D 3 of polymer humidity-sensitive film 54 is thinner. Thus, even thinner thickness D 3 of polymer humidity-sensitive film 54 in the humidity-sensing area A, by providing the region B, the polymer humidity-sensitive film 54, and the upper electrode 55 and lower electrode 53 Since it is possible to secure the path of the leaked electric field when the electric field is applied between the two, it is possible to reduce the variation of the sensitivity of the humidity detection sensor. Therefore, the width W of the region B is preferably a width including a leakage region of the electric field between at least the pair of electrodes 53 and 55 (a region capable of securing a path of the leakage electric field).
　図３（ｂ）に示すような構造、すなわち、一対の電極５３，５５で挟持された高分子感湿膜５４の厚さＤ１と略同じ厚さＤ２の高分子感湿膜５４を有する領域Ｂ及び高分子感湿膜５４の厚さＤ３が薄い感湿領域Ａを有する構造は、上部電極５５のパターニングの際に、フォトリソグラフィー及びエッチングによるウェット工程で処理を行い、次いで保護層５６を形成した後に、異方性エッチングやミリング加工などのドライ工程で保護層５６に開口部を形成することにより実現することができる。 FIG structure as shown in 3 (b), i.e., has a thickness D 1 substantially equal thickness D 2 polymer humidity-sensitive film 54 of polymer humidity-sensitive film 54 which is sandwiched by a pair of electrodes 53 and 55 structure having a thickness D 3 is thin humidity-sensing region a region B and the polymer humidity-sensitive membrane 54, in patterning of the upper electrode 55, performs the processing in wet process by photolithography and etching, and then the protective layer 56 Can be realized by forming an opening in the protective layer 56 by a dry process such as anisotropic etching or milling.
　したがって、上部電極５５をスパッタリング法などで電極材料を被着して形成する場合には、電極材料をフォトリソグラフィー及びエッチングしてパターニングして上部電極５５を形成する。一方、上部電極５５をめっき法で電極材料を被着して形成する場合には、電極材料を被着してめっきシード層を形成し、このめっきシード層をフォトリソグラフィーによりパターニングする。その後、レジストをフレームとして電気めっき処理を施して、めっきシード層上にめっき層を形成して上部電極を形成する。めっきシード層は、めっき層を保護しており、ウェット工程にてエッチングして除去する。 Therefore, when the upper electrode 55 is formed by depositing an electrode material by sputtering or the like, the electrode material is patterned by photolithography and etching to form the upper electrode 55. On the other hand, when the upper electrode 55 is formed by depositing an electrode material by plating, the electrode material is deposited to form a plating seed layer, and the plating seed layer is patterned by photolithography. Thereafter, electroplating is performed using the resist as a frame, and a plating layer is formed on the plating seed layer to form an upper electrode. The plating seed layer protects the plating layer and is removed by etching in a wet process.
　湿度にかかわらず静電容量が変化しない基準部３０においては、基板上に熱酸化膜を介して下部電極が形成されている。下部電極上には、下部電極全体を覆うようにして高分子感湿膜が形成されている。高分子感湿膜上には、高分子感湿膜全体を覆うようにして上部電極が形成されている。基準部３０全体には、露出した上部電極を保護するための保護層が形成されている。 In the reference portion 30 in which the capacitance does not change regardless of the humidity, the lower electrode is formed on the substrate via the thermal oxide film. A polymeric moisture-sensitive film is formed on the lower electrode so as to cover the entire lower electrode. An upper electrode is formed on the polymer moisture sensitive film so as to cover the entire polymer moisture sensitive film. A protective layer is formed on the entire reference portion 30 to protect the exposed upper electrode.
　基板５１としては、表面が絶縁体で保護された基板（例えば、シリコン基板）などを用いることができる。下部電極５２及び上部電極５５を構成する材料としては、例えばＡｌ、ＡｌＣｕ、Ｔａ、Ｔｉ、ＮｉＦｅ、Ｎｉなどを用いることができる。高分子感湿膜５４を構成する材料としては、パターニングが容易なポリイミドなどを用いることができる。また、保護層５６としては、例えば窒化シリコン（ＳｉＮｘ）膜、ＳｉＯ２膜、Ａｌ２Ｏ３／ＳｉＯ２積層膜、ＳｉＯ２／ＳｉＮ積層膜などを用いることができる。 As the substrate 51, a substrate (eg, a silicon substrate) or the like whose surface is protected by an insulator can be used. As a material which comprises the lower electrode 52 and the upper electrode 55, Al, AlCu, Ta, Ti, NiFe, Ni etc. can be used, for example. As a material for forming the polymeric moisture sensitive film 54, polyimide or the like which can be easily patterned can be used. Further, as the protective layer 56, for example, a silicon nitride (SiNx) film, an SiO 2 film, an Al 2 O 3 / SiO 2 laminated film, an SiO 2 / SiN laminated film, or the like can be used.
　本実施の形態に係る湿度検出センサにおいては、図２に示すように、下部電極２１はセンサ部２０と基準部３０とで共通に設けられている。下部電極２１には、センサ部２０と基準部３０との間のほぼ中間の位置から下部電極配線が引き出され、この下部電極配線が回路部４０の電極パッド４０ａに接続されている。このように下部電極配線をセンサ部２０と基準部３０との間のほぼ中間の位置から引き出すことにより、センサ部２０と基準部３０の電気的な対称性が良くなり、センサ容量Ｃ２０と基準容量Ｃ３０のばらつきを低減させることができる。 In the humidity detection sensor according to the present embodiment, as shown in FIG. 2, the lower electrode 21 is provided commonly to the sensor unit 20 and the reference unit 30. In the lower electrode 21, a lower electrode wire is drawn out from a substantially middle position between the sensor unit 20 and the reference unit 30, and the lower electrode wire is connected to the electrode pad 40 a of the circuit unit 40. By thus pulling out the lower electrode wiring from a position approximately halfway between the sensor unit 20 and the reference unit 30, the electrical symmetry of the sensor unit 20 and the reference unit 30 is improved, and the sensor capacitance C 20 and the reference Variations in capacitance C 30 can be reduced.
　また、高分子感湿膜５４及び上部電極５５は、図２に示すように、センサ部２０と基準部３０とで個別に設けられている。上部電極５５には、上部電極５５と回路部４０の電極パッド４０ａとを接続する上部電極配線がそれぞれ設けられている。上部電極配線は、一対の上部電極５５からそれぞれ一定の幅寸法で延在する配線パターンであって、その幅寸法は、センサ部２０と基準部３０で生じる寄生容量が同一になるように調整されている。これにより、寄生容量によるセンサ容量Ｃ２０と基準容量Ｃ３０のばらつきを低減させることができる。 Further, as shown in FIG. 2, the polymer moisture sensitive film 54 and the upper electrode 55 are separately provided in the sensor unit 20 and the reference unit 30. The upper electrode wiring is provided on the upper electrode 55 to connect the upper electrode 55 and the electrode pad 40 a of the circuit unit 40. The upper electrode wiring is a wiring pattern extending from the pair of upper electrodes 55 with a fixed width, and the width is adjusted so that parasitic capacitances generated in the sensor unit 20 and the reference unit 30 become the same. ing. Thus, it is possible to reduce variations in sensor capacitance C 20 and the reference capacitance C 30 due to parasitic capacitance.
　上記構成を有する湿度検出センサにおいては、次のようにして湿度を検出する。まず、センサ部２０では、感湿領域Ａにおいて開口部５４ａを介して高分子感湿膜５４が外界に露出している。このため、高分子感湿膜５４は、雰囲気中の湿度（水分量）に応じて吸収又は放出する水分量が変化し、誘電率εが変化する。このため、下部電極５３と上部電極５５との間の静電容量Ｃ２０が変化する。一方、基準部３０では、高分子感湿膜５４が外界に露出しないので、雰囲気中の湿度（水分量）が変化しても高分子感湿膜５４中の水分量は変化せず、誘電率εも変化しない。このため、下部電極５３と上部電極５５との間には一定の静電容量Ｃ３０が保持される。そして、センサ部２０の静電容量Ｃ２０と基準部３０の静電容量Ｃ３０との間の容量差分を求めることにより、湿度により変化した静電容量（差分値）を測定することができる。本湿度検出センサにおいては、この差分値を電圧に変換して出力するように構成されている。 The humidity detection sensor having the above configuration detects humidity as follows. First, in the sensor unit 20, the polymer moisture sensitive film 54 is exposed to the outside through the opening 54a in the moisture sensitive region A. For this reason, the amount of moisture absorbed or released in the polymer moisture sensitive film 54 changes in accordance with the humidity (the amount of water) in the atmosphere, and the dielectric constant ε changes. Therefore, the capacitance C 20 between the lower electrode 53 and the upper electrode 55 changes. On the other hand, in the reference portion 30, the polymer moisture sensitive film 54 is not exposed to the outside, so the moisture content in the polymer moisture sensitive film 54 does not change even if the humidity (water content) in the atmosphere changes. Also ε does not change. Therefore, a constant capacitance C 30 is held between the lower electrode 53 and the upper electrode 55. Then, by obtaining a capacitance difference between the electrostatic capacitance C 30 of the capacitance C 20 and the reference portion 30 of the sensor unit 20 may measure the changed capacitance (difference value) by humidity. The present humidity detection sensor is configured to convert this difference value into a voltage and output it.
　次に、湿度検出センサの製造方法について説明する。図４（ａ）～（ｅ）は、本発明の実施の形態に係る湿度検出センサの製造方法を説明するための断面図である。 Next, a method of manufacturing the humidity detection sensor will be described. 4 (a) to 4 (e) are cross-sectional views for explaining the method of manufacturing the humidity detection sensor according to the embodiment of the present invention.
　まず、図４（ａ）に示すように、シリコン基板５１を熱酸化して熱酸化膜（ＳｉＯ２膜）５２を形成する。次いで、図４（ｂ）に示すように、熱酸化膜５２上に下部電極５３を形成する。すなわち、下部電極５３は、熱酸化膜５２を有するシリコン基板５１の全面に電極材料を被着し、その上にレジスト層を形成し、パターニングしてマスクとし、そのマスクを介して電極材料をエッチングすることにより形成する。下部電極５３は、センサ部２０及び基準部３０で共通である。なお、この下部電極５３を形成する際に、回路部４０の配線導体とパッド４０ａを同時に形成する。 First, as shown in FIG. 4A, the silicon substrate 51 is thermally oxidized to form a thermal oxide film (SiO 2 film) 52. Next, as shown in FIG. 4B, the lower electrode 53 is formed on the thermal oxide film 52. That is, the lower electrode 53 is formed by depositing an electrode material on the entire surface of the silicon substrate 51 having the thermal oxide film 52, forming a resist layer thereon, patterning it as a mask, and etching the electrode material through the mask It forms by doing. The lower electrode 53 is common to the sensor unit 20 and the reference unit 30. When the lower electrode 53 is formed, the wiring conductor of the circuit section 40 and the pad 40a are simultaneously formed.
　次いで、図４（ｃ）に示すように、下部電極５３上に、下部電極５３を覆うように、センサ部２０、基準部３０それぞれで高分子感湿膜５４を形成する。すなわち、高分子感湿膜５４は、シリコン基板５１の全面に高分子材料（例えばポリイミド）を塗布し、硬化させ、その上にレジスト層を形成し、パターニングしてマスクとし、そのマスクを介して高分子材料をエッチングすることにより形成する。または、高分子感湿膜５４は、感光性の高分子材料を用いてフォトリソグラフィーによりパターンを形成し、高分子材料を硬化させることによって形成する。高分子感湿膜５４は、センサ部２０及び基準部３０でそれぞれ個別である。 Next, as shown in FIG. 4C, the polymer moisture sensitive film 54 is formed on the lower electrode 53 in the sensor unit 20 and the reference unit 30 so as to cover the lower electrode 53. That is, the polymer moisture sensitive film 54 is formed by applying and curing a polymer material (for example, polyimide) on the entire surface of the silicon substrate 51, forming a resist layer thereon, patterning it as a mask, and using the mask It is formed by etching a polymer material. Alternatively, the polymeric moisture-sensitive film 54 is formed by forming a pattern by photolithography using a photosensitive polymeric material and curing the polymeric material. The polymeric moisture sensitive film 54 is individual in each of the sensor unit 20 and the reference unit 30.
　次いで、図４（ｄ）に示すように、高分子感湿膜５４上に、高分子感湿膜５４を覆うように、センサ部２０、基準部３０それぞれで上部電極５５を形成する。すなわち、上部電極５５は、シリコン基板５１の全面に電極材料を被着し、その上にレジスト層を形成し、パターニングしてマスクとし、そのマスクを介して電極材料をエッチングすることにより形成する。これにより、上部電極５５に開口部５５ａ（感湿領域Ａ＋領域Ｂに相当する幅）を形成する。なお、上部電極５５は、センサ部２０及び基準部３０でそれぞれ個別である。 Next, as shown in FIG. 4D, the upper electrode 55 is formed on the polymer moisture sensitive film 54 in the sensor unit 20 and the reference unit 30 so as to cover the polymer moisture sensitive film 54. That is, the upper electrode 55 is formed by depositing an electrode material on the entire surface of the silicon substrate 51, forming a resist layer thereon, patterning it as a mask, and etching the electrode material through the mask. Thus, the opening 55 a (width corresponding to the humidity sensitive region A + region B) is formed in the upper electrode 55. The upper electrode 55 is individual in each of the sensor unit 20 and the reference unit 30.
　次いで、図４（ｅ）に示すように、湿度検出センサ全体に保護層構成材料を被着することにより、センサ部２０及び基準部３０上に保護層５６を形成する。次いで、感湿領域Ａ以外の領域（領域Ｂ＋領域Ｃ）をマスクした状態でドライエッチングなどの異方性エッチングで開口部５６ａ，５４ａを形成する。このようにして、一対の電極５３，５５で挟持された高分子感湿膜５４の厚さＤ１と略同じ厚さＤ２の高分子感湿膜５４を有する領域Ｂを有する本発明の湿度検出センサを作製することができる。 Next, as shown in FIG. 4E, the protective layer forming material is deposited on the entire humidity detection sensor to form the protective layer 56 on the sensor unit 20 and the reference unit 30. Next, the openings 56a and 54a are formed by anisotropic etching such as dry etching with the region (region B + region C) other than the moisture sensitive region A masked. In this way, the humidity of the present invention having a region B having a thickness D 1 substantially equal thickness D 2 of the polymer humidity-sensitive film 54 of polymer humidity-sensitive film 54 which is sandwiched by a pair of electrodes 53 and 55 A detection sensor can be made.
　次に、本発明の効果を明確にするために行った実施例について説明する。
　実施例として、図３（ｂ）に示す構造、すなわち、一対の電極５３，５５で挟持された高分子感湿膜５４の厚さＤ１と略同じ厚さＤ２の高分子感湿膜５４を有する領域Ｂを有する構造を持つ湿度検出センサを作製した。このとき、上部電極及び下部電極は、それぞれ厚さ０．２μｍのＡｌ膜とし、高分子感湿膜は、厚さ１．０μｍのポリイミド膜とし、保護層は、厚さ１．０μｍのＳｉＮｘ膜とした。また、領域Ｂの幅は、１．５μｍとした。この湿度検出センサについて、感度のばらつきを調べた。感度のばらつきは、ＬＣＲメータにより測定した。その結果、感度ばらつきが６％であり、非常に小さかった。 Next, an example carried out to clarify the effect of the present invention will be described.
As an example, the structure shown in FIG. 3 (b), i.e., wet substantially sensitive polymer of the same thickness D 2 and the thickness D 1 of the polymer humidity-sensitive film 54 which is sandwiched by a pair of electrodes 53 and 55 film 54 A humidity detection sensor having a structure having a region B having the At this time, the upper electrode and the lower electrode are respectively an Al film with a thickness of 0.2 μm, the polymer moisture sensitive film is a polyimide film with a thickness of 1.0 μm, and the protective layer is a SiNx film with a thickness of 1.0 μm. And In addition, the width of the region B was 1.5 μm. About this humidity detection sensor, the dispersion | variation in a sensitivity was investigated. The variation in sensitivity was measured by an LCR meter. As a result, the sensitivity variation was 6%, which was very small.
　比較として、上部電極近傍に上記領域Ｂを有しない構造、すなわち、ミリング加工により上部電極を部分的に除去した構造を有すること以外は実施例と同様にして湿度検出センサを作製した。この湿度検出センサについて、感度のばらつきを実施例と同様にして調べた。その結果、感度ばらつきが１１％であり、非常に大きかった。 As a comparison, a humidity detection sensor was manufactured in the same manner as in the example except that the region B was not present in the vicinity of the upper electrode, that is, the upper electrode was partially removed by milling. About this humidity detection sensor, the dispersion | variation in a sensitivity was investigated like the Example. As a result, the sensitivity variation was 11%, which was very large.
　このように、本発明に係る湿度検出センサにおいては、感湿領域以外の領域において、一対の電極で挟持された高分子感湿膜の厚さと略同じ厚さの高分子感湿膜を有する領域を上部電極の近傍に有するので、高分子感湿膜における、上部電極と下部電極との間に電界が印加されたときの漏れ電界のパスを確保することができる。その結果、湿度検出センサの感度のばらつきを小さくすることが可能となる。このように、本発明によれば、感度ばらつきのない平行平板型の湿度検出センサを実現することができる。 As described above, in the humidity detection sensor according to the present invention, in the area other than the moisture sensitive area, the area having the polymer moisture sensitive film having substantially the same thickness as the thickness of the polymer moisture sensitive film sandwiched between the pair of electrodes. Since it is in the vicinity of the upper electrode, it is possible to secure a path of a leaked electric field when an electric field is applied between the upper electrode and the lower electrode in the polymer moisture sensitive film. As a result, the variation in sensitivity of the humidity detection sensor can be reduced. As described above, according to the present invention, it is possible to realize a parallel plate type humidity detection sensor with no sensitivity variation.
　本発明は上記実施の形態に限定されず、適宜変更して実施することができる。上記実施の形態においては、センサ部と基準部とを備えた湿度検出センサについて説明しているが、本発明はこれに限定されず、センサ部のみで構成された湿度検出センサにも同様に適用することができる。また、上記実施の形態における材料、各層の配置位置、厚さ、大きさ、製法などは適宜変更して実施することが可能である。その他、本発明は、本発明の範囲を逸脱しないで適宜変更して実施することができる。 The present invention is not limited to the above embodiment, and can be implemented with appropriate modifications. In the above embodiment, although the humidity detection sensor provided with the sensor unit and the reference unit is described, the present invention is not limited to this, and the present invention is similarly applied to a humidity detection sensor composed of only the sensor unit. can do. In addition, the materials, the arrangement position of each layer, the thickness, the size, the manufacturing method, and the like in the above-described embodiment can be appropriately changed and implemented. In addition, the present invention can be implemented with appropriate modifications without departing from the scope of the present invention.
　本件は、２００９年１１月３０日出願の特願２００９－２７２４２７に基づく。この内容は、全てここに含めておく。
  This case is based on Japanese Patent Application No. 2009-272427 filed on November 30, 2009. All this content is included here.

Claims (4)

  1. 　基板と、前記基板上に設けられ、湿度に応じて誘電率が変化する高分子感湿膜を一対の電極で挟持し、前記高分子感湿膜が部分的に外界に露出する感湿領域を持つセンサ部と、少なくとも前記一対の電極のうちの上側の電極上に形成された保護層と、を具備し、前記感湿領域以外の領域において、前記一対の電極で挟持された高分子感湿膜の厚さと略同じ厚さの高分子感湿膜を有する領域を前記上側の電極の近傍に有することを特徴とする湿度検出センサ。 A substrate and a polymer moisture sensitive film which is provided on the substrate and whose dielectric constant changes according to humidity are sandwiched between a pair of electrodes, and the moisture sensitive region where the polymer moisture sensitive film is partially exposed to the outside is A polymer sensor having a sensor portion and a protective layer formed on at least the upper electrode of the pair of electrodes, and in a region other than the humidity sensitive region, a polymer moisture sensitive device sandwiched by the pair of electrodes A humidity detection sensor comprising a region having a polymer moisture sensitive film having a thickness substantially the same as the thickness of the film in the vicinity of the upper electrode.
  2. 　前記領域の幅は、少なくとも前記一対の電極間の電界の漏れ領域を含む幅であることを特徴とする請求項１記載の湿度検出センサ。 The humidity detection sensor according to claim 1, wherein the width of the region is a width including a leak region of an electric field between at least the pair of electrodes.
  3. 　前記高分子感湿膜上の電極は、フォトリソグラフィー及びエッチングによりパターニングされてなることを特徴とする請求項１又は請求項２記載の湿度検出センサ。 The humidity detection sensor according to claim 1 or 2, wherein the electrode on the polymer moisture sensitive film is patterned by photolithography and etching.
  4. 　前記高分子感湿膜上の電極は、フォトリソグラフィー及びエッチングによりパターニングされてなるシード層と、前記シード層上に形成されためっき層とで構成されていることを特徴とする請求項１又は請求項２記載の湿度検出センサ。 The electrode on the polymer moisture sensitive film is constituted of a seed layer patterned by photolithography and etching, and a plating layer formed on the seed layer. The humidity detection sensor according to Item 2.
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