JP2014167445A - Humidity sensor and method for producing humidity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a humidity sensor capable of more efficiently detecting humidity as compared with conventional ones.SOLUTION: A humidity sensor which detects humidity based on a plurality of inter-electrode capacitance includes: a substrate (11), a protective coat (18) facing the substrate, a plurality of electrodes (conducting film 16) provided so that one end contacts the substrate, and a moisture-sensitive film (17) between the substrate and the protective coat, in which a dielectric constant changes with humidity of an environmental atmosphere. The other ends of the plurality of electrodes are in contact with the protective coat.

Description

  The present invention relates to a humidity sensor that detects the humidity of an environmental atmosphere and a method for manufacturing such a humidity sensor.

  As one of humidity sensors for detecting humidity, a capacitance type humidity sensor is used. A capacitance humidity sensor usually includes a plurality of electrodes and a film that absorbs and dehumidifies moisture in the air (hereinafter referred to as a moisture sensitive film) between the electrodes. When the moisture sensitive film absorbs and dehumidifies moisture in the air, the dielectric constant of the moisture sensitive film changes. Since the capacitance between the electrodes changes as the dielectric constant of the moisture sensitive film changes, the capacitive humidity sensor with the above configuration detects changes in humidity based on this capacitance change. To do.

  For example, Patent Literature 1 describes a humidity sensor including two flat electrodes provided so as to face each other substantially in parallel and a moisture sensitive film provided between the electrodes. Patent Document 2 describes a humidity sensor including two comb-shaped electrodes provided so as to face each other and a moisture-sensitive film provided so as to cover the two electrodes. .

Japanese Patent Laid-Open No. 7-120427 (released on May 12, 1995) Special Table 2003-516539 (May 13, 2003)

  FIG. 7 is a schematic diagram showing a cross-sectional configuration of the humidity sensor described in Patent Document 1. As shown in FIG. As shown in FIG. 7, the humidity sensor 4 described in Patent Document 1 has a structure in which a moisture sensitive film 42 is sandwiched between two flat electrodes 41. Therefore, moisture in the air enters and exits the moisture sensitive film 42 from the moisture sensitive film 42 and the side opening (in the horizontal direction of the moisture sensitive film 42 in FIG. 7) where the air comes into contact. The wet film 42 absorbs and dehumidifies. The capacitance between the two electrodes 41 changes with the change in the dielectric constant of the moisture sensitive film 42 that has absorbed and dehumidified moisture in the air. Here, in order to improve the detection sensitivity of the humidity sensor 4, it is necessary to increase the value of the measured capacitance.

  In the humidity sensor 4, in order to increase the measured capacitance value, it is conceivable to shorten the distance between the two flat electrodes. However, if the distance between the electrodes is shortened, the value of the measured capacitance can be increased, but the area where the moisture sensitive film 42 and the air come into contact is reduced. As a result, the humidity sensor 4 has a structure in which moisture in the air does not easily enter the moisture sensitive film 42, and as a result, there is a problem that it is difficult to efficiently detect a humidity change.

  FIG. 8 is a schematic diagram showing a cross-sectional configuration of the humidity sensor described in Patent Document 2. As shown in FIG. As shown in FIG. 8, the humidity sensor 5 described in Patent Document 2 is provided with a moisture sensitive film 53 so as to cover the plurality of electrodes 52, so that moisture in the air easily enters the moisture sensitive film 53. It has become. However, much of the moisture that enters the moisture sensitive film 53 through the protective film 54 is absorbed near the surface of the moisture sensitive film 53 (upper surface side in FIG. 8).

  In FIG. 8, a one-dot chain double-pointed arrow is an arrow indicating a path that contributes to the capacitance between the electrodes, and the thickness of the arrow corresponds to the magnitude of the contribution to the capacitance between the electrodes. Yes. As shown in FIG. 8, the contribution to the capacitance between the electrodes is greatest in the vicinity of the electrodes and decreases as the distance from the electrodes increases. Therefore, the vicinity of the surface of the moisture sensitive film 53 in which moisture in the air easily enters hardly contributes to the change in the capacitance between the electrodes. Therefore, there is a problem that the humidity sensor 5 cannot efficiently detect a humidity change.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a humidity sensor capable of detecting a change in humidity more efficiently than in the prior art.

  In order to solve the above-described problem, a humidity sensor according to one embodiment of the present invention is a humidity sensor that detects the humidity of an environmental atmosphere based on capacitance between a plurality of electrodes. A protective film opposite to the substrate, a plurality of electrodes provided so that one end thereof is in contact with the substrate, and a moisture-sensitive film whose dielectric constant changes between the substrate and the protective film due to a change in humidity of an environmental atmosphere The other ends of the plurality of electrodes are in contact with the protective film.

  In order to solve the above-described problem, a humidity sensor manufacturing method according to an aspect of the present invention is a humidity sensor manufacturing method that measures the humidity of an environmental atmosphere based on capacitance between a plurality of electrodes. A wiring forming step of forming conductive wiring on the substrate; an electrode forming step of forming a plurality of electrodes by depositing a conductive film on the wiring; and a space between the plurality of electrodes in the environment. It includes a moisture-sensitive film forming step for forming a moisture-sensitive film whose dielectric constant changes due to a change in atmospheric humidity, and a protective film forming step for forming a protective film so as to come into contact with the plurality of electrodes. Yes.

  According to one embodiment of the present invention, it is possible to provide a humidity sensor that can detect a change in humidity more efficiently than in the past.

It is the schematic which shows the cross-sectional structure of the humidity sensor which concerns on Embodiment 1 of this invention. It is the schematic which shows the manufacturing process of the humidity sensor which concerns on Embodiment 1 of this invention. (A) of FIG. 2 is a figure which shows the cross section of the humidity sensor in which the process to step S1-S3 shown in FIG. 3 was performed. FIG. 2B is a diagram showing a cross section of the humidity sensor in which a plurality of openings are formed in step S4 shown in FIG. FIG. 2C is a view showing a cross section of the humidity sensor on which the conductive film is deposited in step S5 shown in FIG. (D) of FIG. 2 is a figure which shows the cross section of the humidity sensor from which the upper surface of the electrically conductive film was removed by step S6 shown in FIG. FIG. 2E shows a cross section of the humidity sensor from which the silicon oxide film has been selectively removed in step S7 shown in FIG. FIG. 2F is a view showing a cross section of the humidity sensor in which the moisture sensitive film and the protective film are formed in step S8 shown in FIG. It is a flowchart which shows the manufacturing process of the humidity sensor which concerns on Embodiment 1 of this invention. It is a three-dimensional perspective view which shows an example of the arrangement | sequence of several electrodes in the humidity sensor which concerns on Embodiment 1 of this invention. It is a three-dimensional perspective view which shows an example of the arrangement | sequence of several electrodes in the humidity sensor which concerns on Embodiment 3 of this invention. It is a top view for demonstrating an example of the arrangement | sequence of several electrodes in the humidity sensor which concerns on this invention. FIG. 6A is a top view of the humidity sensor when cylindrical electrodes having a diameter of 1 μm are arranged in an orthorhombic lattice in the humidity sensor according to Embodiment 1 of the present invention. FIG. 6B is a top view of a humidity sensor according to Embodiment 3 of the present invention when plate-like electrodes having a thickness of 1 μm are arranged so that the distance between the electrodes is 1 μm. It is. It is the schematic which shows the cross-sectional structure of the conventional humidity sensor. It is the schematic which shows the cross-sectional structure of the conventional humidity sensor.

Embodiment 1
Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIGS.

(Humidity sensor configuration)
FIG. 1 is a cross-sectional view showing a configuration of a humidity sensor according to the present embodiment. As shown in FIG. 1, the humidity sensor 1 includes a substrate 11, a metal wiring 12, a silicon nitride film 13, a conductive film 16, a moisture sensitive film 17, and a protective film 18. FIG. 1 is a diagram schematically showing the configuration of the humidity sensor 1 according to this embodiment, and the number of members constituting the humidity sensor 1 and the dimensions of the members are not limited. Further, in the coordinate axes shown in FIG. 1, the z-axis positive direction side is defined as “upward”, and the z-axis positive direction surface of each member is referred to as “upper surface”.

  An insulating film (not shown) is formed on the upper surface of the substrate 11, and the metal wiring 12 is provided on the upper surface of the substrate 11 via the insulating film. That is, the substrate 11 and the metal wiring 12 are electrically insulated. The metal wiring 12 is made of a metal having a thickness of 0.05 μm or more and a width of 0.1 μm or more.

  As the silicon nitride film 13, for example, silicon nitride (chemical formula: SiN) is used. The silicon nitride film 13 has a thickness of 0.01 μm or more, and is formed so as to cover the substrate 11 and the metal wiring 12 in order to protect the substrate 11 and the metal wiring 12.

  The conductive film 16 is an electrode made of, for example, tungsten, which is a conductive material, and the shape thereof is an elliptic cylinder having a minor axis of 0.1 μm or more. Here, “an elliptic cylinder having a minor axis of 0.1 μm or more” includes “a true cylinder having a diameter of 0.1 μm or more”. The “elliptical cylinder” and the “true cylinder” are also simply referred to as “cylinder”. Hereinafter, the conductive film 16 may be referred to as an electrode 16. The plurality of electrodes 16 are provided so as to be in contact with the upper surface of the metal wiring 12 so that the mutual distance becomes 0.1 μm or more. In FIG. 1, the electrode 16 detects a capacitance between the plurality of electrodes 16 as indicated by a one-dot chain line bidirectional arrow.

  Each dimension of the metal wiring 12, the silicon nitride film 13, and the conductive film 16 is a dimension that can be processed by an existing semiconductor manufacturing apparatus. Therefore, the humidity sensor according to the present embodiment can be created by using an existing semiconductor manufacturing apparatus.

  As the moisture sensitive film 17, for example, a polymer film such as polyimide is used. The moisture sensitive film 17 absorbs and dehumidifies moisture in the air. When the moisture sensitive film 17 absorbs and dehumidifies moisture in the air, the dielectric constant of the moisture sensitive film 17 changes. The moisture sensitive film 17 is provided so as to fill the gaps between the plurality of conductive films 16. Therefore, when the dielectric constant of the moisture sensitive film 17 changes (the moisture sensitive film 17 absorbs and dehumidifies moisture), the capacitance value detected by the electrode 16 changes. Therefore, the humidity sensor 1 can detect the humidity of the environmental atmosphere based on the capacitance value detected by the electrode 16.

  The protective film 18 is a film for protecting the conductive film 16 and the moisture sensitive film 17. The protective film 18 is provided in contact with the conductive film 16 and the moisture sensitive film 17. Since the protective film 18 has a property of transmitting moisture, moisture in the air enters the moisture sensitive film 17 through the protective film 18 and is absorbed and dehumidified.

  As described above, in the humidity sensor 1 according to the present embodiment, the electrode 16 is provided so that one end is in contact with the metal wiring 12 and the other end is in contact with the protective film 18. With the above configuration, most of the moisture in the environmental atmosphere that enters the moisture sensitive film 17 through the protective film 18 is absorbed in the vicinity of the electrode 16. In general, the detected capacitance value depends sensitively on the change in dielectric constant in the vicinity of the electrode. Therefore, the humidity sensor 1 configured as described above can sharply detect a change in the dielectric constant of the moisture sensitive film 17 due to a change in the humidity of the environmental atmosphere.

  Therefore, the humidity sensor 1 according to the present embodiment can detect a change in the humidity of the environmental atmosphere more efficiently than in the past.

(Method for manufacturing humidity sensor)
Below, the manufacturing process of the humidity sensor 1 which concerns on this embodiment is demonstrated, referring FIG. 2 and FIG. The humidity sensor 1 is manufactured by, for example, a humidity sensor manufacturing apparatus (not shown). FIG. 2 is a schematic view showing a manufacturing process of the humidity sensor 1 according to the present embodiment. As in FIG. 1, FIG. 2 is a diagram schematically showing the configuration of the humidity sensor 1 according to the present embodiment, and limits the number of members constituting the humidity sensor 1 and the dimensions of the members. It is not a thing. In the coordinate axes shown in FIG. 2, the z-axis positive direction side is defined as “upward”, and the z-axis positive direction surface of each member is referred to as “upper surface”.
FIG. 3 is a flowchart showing the manufacturing process of the humidity sensor 1 according to this embodiment.

  In step S1 shown in FIG. 3, the humidity sensor manufacturing apparatus forms a metal wiring 12 having a thickness of 0.05 μm or more and a width of 0.1 μm or more on the upper surface of the substrate 11 (wiring forming step).

  Subsequently, in step S2, the humidity sensor manufacturing apparatus laminates a silicon nitride film 13 having a thickness of 0.01 μm or more so as to cover the metal wiring 12 formed in step S1 and the substrate 11.

Subsequently, in step S3, the humidity sensor manufacturing apparatus further stacks a silicon oxide film 14 having a thickness of 0.1 μm or more on the upper surface of the silicon nitride film 13 stacked in step S2. For example, silicon dioxide (chemical formula: SiO ₂ ) is used as the silicon oxide film 14. Since the silicon oxide film 14 stacked in step S3 is finally removed in a later process, it is also referred to as a sacrificial film. As a method of laminating the silicon oxide film 14, there is a CVD (Chemical Vapor Deposition) method, but the present invention is not limited to this.

  (A) of FIG. 2 is a figure which shows the cross section of the humidity sensor 1 in which the process to step S1-S3 was performed. As shown in FIG. 2A, the metal wiring 12, the silicon nitride film 13, and the silicon oxide film 14 are stacked on the substrate 11 by the processing from steps S <b> 1 to S <b> 3.

  Subsequently, in step S4, the humidity sensor manufacturing apparatus forms a plurality of openings 15 reaching from the upper surface of the silicon oxide film 14 laminated in step S3 to the upper surface of the metal wiring 12. The cross-sectional shape of the opening 15 formed here (the shape seen from the upper surface side of the silicon oxide film 14) is preferably an ellipse having a minor axis of 0.1 μm or more. As a method for forming the opening 15 in step S4, for example, a method of forming a contact hole in semiconductor manufacturing technology may be used.

  FIG. 2B is a diagram showing a cross section of the humidity sensor 1 in which a plurality of openings 15 are formed in step S4. As shown in FIG. 2B, the silicon oxide film 14 has a plurality of openings 15 formed so as to penetrate the silicon nitride film 13 from the upper surface of the silicon oxide film 14 and reach the upper surface of the metal wiring 12. The

  Subsequently, in step S5, the humidity sensor manufacturing apparatus deposits the conductive film 16 in the plurality of openings 15 formed in step S4, and further covers the silicon oxide film 14 and the openings 15 so as to cover the silicon oxide film 14 and the openings 15. 16 is deposited.

  (C) of FIG. 2 is a figure which shows the cross section of the humidity sensor 1 in which the electrically conductive film 16 was deposited in step S5. As shown in FIG. 2C, a conductive film 16 is deposited so as to cover the silicon oxide film 14 and the opening 15.

  Subsequently, in step S6, the humidity sensor manufacturing apparatus removes the upper surface of the conductive film 16 deposited in step S5 by dry etching. The humidity sensor manufacturing apparatus etches the conductive film 16 from the upper surface side of the deposited conductive film 16 until the upper surface of the silicon oxide film 14 is exposed. By etching the conductive film 16 until the upper surface of the silicon oxide film 14 is exposed, the length of the plurality of conductive films 16 in the z-axis direction becomes uniform.

  In this embodiment, the case where the dry etching method is used as the method of etching the conductive film 16 has been described, but the present invention is not limited to this. For example, the conductive film 16 may be etched by a CMP (Chemical Mechanical Polishing) method or the like. Also, in step S5, if the conductive film 16 deposited inside each of the plurality of openings 15 can be deposited so that the length in the z-axis direction is uniform, the process in step S6 is omitted. Also good.

  (D) of FIG. 2 is a figure which shows the cross section of the humidity sensor 1 from which the upper surface of the electrically conductive film 16 was removed in step S6. As shown in FIG. 2D, by etching the conductive film 16 until the upper surface of the silicon oxide film 14 is exposed, the lengths of the plurality of conductive films 16 in the z-axis direction are uniform. .

  Subsequently, in step S7, the humidity sensor manufacturing apparatus removes the silicon oxide film 14 using hydrofluoric acid (chemical formula: HF). Since hydrofluoric acid has a property of reacting with silicon dioxide to dissolve silicon dioxide, the silicon oxide film 14 can be removed. Further, since the substrate 11 and the metal wiring 12 are covered with the silicon nitride film 13, they are not removed by hydrofluoric acid, but only the silicon oxide film 14 is selectively removed. By selectively removing the silicon oxide film 14, only the conductive film 16 deposited inside each of the plurality of openings 15 remains. The remaining conductive film 16 serves as an electrode in the humidity sensor 1. That is, the process of steps S2 to S7 is a process of forming an electrode included in the humidity sensor 1 (electrode forming process). In the following steps, the conductive film 16 may be referred to as the electrode 16.

  FIG. 2E is a diagram showing a cross section of the humidity sensor 1 from which the silicon oxide film 14 has been selectively removed in step S7. As shown in FIG. 2E, only the silicon oxide film 14 is selectively removed from the humidity sensor 1. Therefore, the humidity sensor 1 that has undergone the processing up to step S7 includes the substrate 11, the metal wiring 12, the silicon nitride film 13, and the electrode 16.

  Finally, in step S8, the humidity sensor manufacturing apparatus forms the moisture sensitive film 17 so as to fill the gaps between the plurality of electrodes 16 (moisture sensitive film forming step). Furthermore, the humidity sensor manufacturing apparatus forms the protective film 18 so as to contact the moisture sensitive film 17 and the electrode 16 (protective film forming step).

  The humidity sensor manufacturing apparatus can manufacture the humidity sensor 1 according to the present embodiment by the above steps S1 to S8.

  (F) of FIG. 2 is a figure which shows the cross section of the humidity sensor 1 in which the moisture sensitive film | membrane 17 and the protective film 18 were formed in step S8. As shown in FIG. 2F, one end of the electrode 16 is in contact with the metal wiring 12, and the other end is in contact with the protective film 18. The humidity sensor 1 formed by the above procedure can detect a humidity change more efficiently than the conventional one.

  The manufacturing process of the humidity sensor 1 according to this embodiment has been described above. It will be easily understood by those skilled in the art that a part of the manufacturing process described above (steps S1 to S7) is almost the same as the manufacturing process of the semiconductor chip. Therefore, since a semiconductor chip manufacturing apparatus can be used to manufacture the humidity sensor 1, the humidity sensor 1 according to the present embodiment can be manufactured at a relatively low cost.

(About electrode arrangement)
Hereinafter, an example of the arrangement of a plurality of electrodes in the humidity sensor 1 according to the present embodiment will be described with reference to FIG. FIG. 4 is a three-dimensional perspective view showing an example of the arrangement of a plurality of electrodes in the humidity sensor 1 according to the present embodiment. In FIG. 4, the silicon nitride film 13, the moisture sensitive film 17, and the protective film 18 are omitted for simplification of description.

  FIG. 4 is a diagram schematically showing the humidity sensor 1 according to this embodiment, and the number of members constituting the humidity sensor 1 and the dimensions of the members are not limited. Further, in the coordinate axes shown in FIG. 4, the z-axis positive direction side is defined as “upward”, and the z-axis positive direction side surface of each member is referred to as “upper surface”.

  As shown in FIG. 4, the humidity sensor 1 according to the present embodiment includes a substrate 11, a metal wiring 12 formed on the upper surface of the substrate 11, and an electrode 16 provided on the upper surface of the metal wiring 12. .

  As shown in FIG. 4, the metal wiring 12 is provided on the upper surface of the substrate 11 so that the longitudinal direction coincides with the y-axis direction. The plurality of metal wirings 12 are provided so that the distances in the x-axis direction are kept substantially constant.

  The plurality of electrodes 16 are respectively provided on the upper surface of the metal wiring 12 so that the distances in the y-axis direction are kept substantially constant. Further, since the metal wirings 12 are provided so as to maintain a substantially constant distance from each other, the distances in the x-axis direction of the plurality of electrodes 16 are also maintained at a substantially constant distance.

  In the present embodiment, the distance between the plurality of electrodes 16 is preferably 0.1 μm or more. As described above, the humidity sensor 1 according to this embodiment can increase the density of the plurality of electrodes 16 while keeping the distance between the plurality of electrodes 16 substantially constant. Thereby, the contact area between the plurality of electrodes 16 and the moisture sensitive film 17 can be increased.

  Therefore, according to the above configuration, the ratio of moisture absorbed and dehumidified by the moisture sensitive film 17 in the vicinity of the electrode 16 can be improved. That is, according to said structure, it contributes to the improvement of the detection sensitivity of a humidity sensor.

  In the present embodiment, the case where the electrodes 16 are arranged in a lattice shape along the x-axis and the y-axis, that is, a square lattice shape has been described, but the present invention is not limited to this. That is, it is only necessary that the distances between the electrodes are arranged so as to maintain a substantially constant distance from each other.

  The configuration and manufacturing method of the humidity sensor 1 according to the first embodiment have been described above.

  As described above, the shape of the opening 15 formed in step S4 corresponds to the shape of the electrode 16 of the humidity sensor 1 according to the present embodiment. Therefore, the shape of the conductive film 16 provided in the humidity sensor 1 can be variously changed by changing the shape of the opening 15 formed in step S4.

  Below, the humidity sensor which concerns on other embodiment at the time of changing the shape of the electrode 16 is demonstrated.

[Embodiment 2]
Hereinafter, a second embodiment of the present invention will be described. The humidity sensor according to the present embodiment is different from the humidity sensor 1 according to the first embodiment in that the shape of the electrode 16 is a polygonal column. Therefore, since the components other than the electrode 16 are the same as those of the humidity sensor 1 according to the first embodiment, the humidity sensor according to this embodiment will be described with reference to FIGS.

  As shown in FIG. 4, the humidity sensor 1 according to the present embodiment includes a substrate 11, a metal wiring 12 formed on the upper surface of the substrate 11, and an electrode 16 provided on the upper surface of the metal wiring 12. .

  As shown in FIG. 4, the metal wiring 12 is provided on the upper surface of the substrate 11 so that the longitudinal direction coincides with the y-axis direction. The plurality of metal wirings 12 are provided so that the distances in the x-axis direction are kept substantially constant.

  The plurality of electrodes 16 are respectively provided on the upper surface of the metal wiring 12 so that the distances in the y-axis direction are kept substantially constant. Further, since the metal wirings 12 are provided so as to maintain a substantially constant distance from each other, the distances in the x-axis direction of the plurality of electrodes 16 are also maintained at a substantially constant distance.

  In the present embodiment, the shape of the plurality of electrodes 16 is a polygonal column (N prism, N is a natural number of 3 or more) having a side of 0.1 μm or more, and the distance between the plurality of electrodes 16 is 0.00. It is preferable that it is 1 micrometer or more. As described above, the humidity sensor 1 according to this embodiment can increase the density of the plurality of electrodes 16 while keeping the distance between the plurality of electrodes 16 substantially constant. Thereby, the contact area between the plurality of electrodes 16 and the moisture sensitive film 17 can be increased.

  Therefore, according to the above configuration, the ratio of moisture absorbed and dehumidified by the moisture sensitive film 17 in the vicinity of the electrode 16 can be improved. That is, according to said structure, it contributes to the improvement of the detection sensitivity of a humidity sensor.

  In the present embodiment, the case where the electrodes 16 are arranged in a lattice shape along the x-axis and the y-axis, that is, a square lattice shape has been described, but the present invention is not limited to this. That is, it is only necessary that the distances between the electrodes are arranged so as to maintain a substantially constant distance from each other. For example, they may be arranged in an orthorhombic lattice shape and a regular triangular lattice shape.

[Embodiment 3]
Hereinafter, a third embodiment of the present invention will be described with reference to FIG. The humidity sensor 2 according to this embodiment is different from the humidity sensors according to other embodiments in that the electrode 16 has a plate shape. FIG. 5 is a three-dimensional perspective view showing an example of the arrangement of a plurality of electrodes in the humidity sensor 2 according to the present embodiment. In FIG. 5, the silicon nitride film, the moisture sensitive film, and the protective film are not shown for the sake of simplicity.

  FIG. 5 is a diagram schematically showing the configuration of the humidity sensor 2 according to the present embodiment, and does not limit the number of members and the dimensions of the members. In the coordinate axes shown in FIG. 5, the z-axis positive direction side is defined as “upward”, and the z-axis positive direction surface of each member is referred to as “upper surface”.

  As shown in FIG. 5, the humidity sensor 2 according to this embodiment includes a substrate 21, a metal wiring 22 formed on the upper surface of the substrate 21, and a conductive film (also referred to as an electrode) provided on the upper surface of the metal wiring 22. 26).

  As shown in FIG. 5, the metal wiring 22 is provided on the upper surface of the substrate 21 so that the longitudinal direction coincides with the y-axis direction. Further, the plurality of metal wirings 22 are provided so that the distances in the x-axis direction are kept substantially constant.

  The plurality of electrodes 26 are respectively provided on the upper surface of the metal wiring 22 so that the longitudinal direction coincides with the y-axis direction. Further, since the metal wirings 22 are provided so as to maintain a substantially constant distance from each other, the distances in the x-axis direction of the plurality of electrodes 26 are maintained at a substantially constant distance. In the present embodiment, the distance between the plurality of electrodes 26 is preferably 0.1 μm or more.

  In addition, the manufacturing method of the humidity sensor 2 which concerns on this embodiment is substantially the same as the manufacturing method of the humidity sensor 1 which concerns on 1st Embodiment. That is, in the step S4 in FIG. 3, the shape of the opening formed in the silicon oxide film 14 may be formed in a plate shape having a thickness of 0.1 μm or more like the electrode 26 shown in FIG. .

[Comparison between columnar electrode and plate electrode]
Below, the advantage by using a cylindrical electrode is demonstrated, referring FIG. FIG. 6 is a top view for explaining an example of an arrangement of a plurality of electrodes in the humidity sensor 1 and the humidity sensor 2 according to the present invention. FIG. 6 is a diagram schematically showing the configuration of the humidity sensor 1 and the humidity sensor 2 according to the present invention, and does not limit the number of members and the dimensions of the members.

  FIG. 6A is a top view of the humidity sensor 1 when the cylindrical electrodes 16 having a diameter of 1 μm are arranged in an orthorhombic lattice shape. As shown in FIG. 6A, the electrodes 16 are arranged such that the distance between the electrodes is 1 μm in a range of 100 μm × 100 μm. When the plurality of electrodes 16 are arranged as described above, about 2900 electrodes 16 can be arranged.

  FIG. 6B is a top view of the humidity sensor 2 when the plate-like electrodes 26 having a thickness of 1 μm are arranged so that the distance between the electrodes is 1 μm within a range of 100 μm × 100 μm. When the plurality of electrodes 26 are arranged as described above, about 50 electrodes 26 can be arranged.

  Here, consider a case where foreign matter is accidentally generated (or mixed) for some reason inside the humidity sensitive film of the humidity sensor. A pair of electrodes arranged on both sides of the foreign object so that the generated foreign object is sandwiched when the generated foreign object has a size equal to or larger than the distance between the electrodes (ie, 0.1 μm). In some cases, the capacitance cannot be measured due to the influence of foreign matter. In the case where the columnar electrodes 16 as shown in FIG. 6A are arranged in an orthorhombic lattice, one pair (two) of the approximately 2900 electrodes 16 cannot be measured. That is, about 0.069% of all the electrodes 16 cannot be measured.

  On the other hand, when the plate-like electrodes 26 as shown in FIG. 6B are arranged side by side, one pair (two) of the about 26 electrodes 26 cannot be measured. That is, about 4% of all the electrodes 26 cannot be measured.

  As described above, by making the shape of the plurality of electrodes in the humidity sensor according to the present invention cylindrical, when foreign matter occurs accidentally inside the moisture sensitive film, the influence of foreign matter among all the electrodes As a result, the ratio of electrodes that cannot be measured can be reduced. Therefore, in the humidity sensor according to the present invention, it is preferable that the plurality of electrodes have a cylindrical shape.

[Summary]
The humidity sensor 1 according to the first aspect of the present invention is a humidity sensor that detects the humidity of the environmental atmosphere based on the capacitance between a plurality of electrodes, and includes a substrate 11 and a protective film 18 facing the substrate 11. The dielectric constant changes between the plurality of electrodes (conductive film 16) provided so that one end is in contact with the substrate 11 and the substrate 11 and the protective film 18 due to a change in humidity of the environmental atmosphere. A moisture-sensitive film 17, and the other ends of the plurality of electrodes are in contact with the protective film 18.

  According to the above configuration, since the plurality of electrodes are in contact with the protective film 18, most of the moisture in the environmental atmosphere entering the moisture sensitive film 17 through the protective film 18 is Moisture is absorbed in the vicinity. In general, since the contribution to the capacitance between the electrodes is the largest in the vicinity of the electrodes, the plurality of electrodes can detect the change in the dielectric constant of the moisture sensitive film 17 due to the change in the humidity of the environmental atmosphere. become.

  Therefore, according to said structure, the humidity sensor which can detect a humidity change more efficiently compared with the past can be provided.

  In the humidity sensor according to aspect 2 of the present invention, the shape of the plurality of electrodes in the aspect 1 is preferably columnar.

  In the humidity sensor according to aspect 3 of the present invention, in the aspect 2, the plurality of electrodes are elliptic cylinders having a minor axis of 0.1 μm or more, and a distance between the plurality of electrodes is 0.1 μm or more. It is preferable that it is provided.

  According to said structure, when a foreign material occurs accidentally inside a moisture sensitive film, the ratio of the electrode which becomes impossible to measure by the influence of a foreign material can be reduced.

  Therefore, according to the above configuration, it is possible to provide a humidity sensor that hardly affects the product performance even with respect to foreign matters that occur accidentally.

  In the humidity sensor according to aspect 4 of the present invention, in the aspect 2, the plurality of electrodes are polygonal columns having sides of 0.1 μm or more, and a distance between the electrodes is 0.1 μm or more. May be provided.

  According to said structure, it contributes to the improvement of the detection sensitivity of a humidity sensor similarly to the humidity sensor which concerns on the said aspect 3. FIG.

  In the humidity sensor 2 according to the fifth aspect of the present invention, the shape of the plurality of electrodes (conductive film 26) may be a plate shape in the first aspect.

  The humidity sensor 2 according to aspect 6 of the present invention is the humidity sensor 2 according to aspect 5 described above, wherein the thickness of the plurality of electrodes is 0.1 μm or more, and the distance between the plurality of electrodes is 0.1 μm or more. It is preferable that

  A humidity sensor manufacturing method according to aspect 7 of the present invention is a humidity sensor manufacturing method for measuring the humidity of an environmental atmosphere based on the capacitance between a plurality of electrodes, and includes a conductive wiring on a substrate 11. A wiring formation process for forming (metal wiring 12), an electrode formation process for forming a plurality of electrodes by depositing a conductive film 16 on the wiring, and a change in humidity of the environmental atmosphere in the gaps between the plurality of electrodes A moisture-sensitive film forming step for forming the moisture-sensitive film 17 whose dielectric constant changes due to the above, and a protective film forming step for forming the protective film 18 in contact with the plurality of electrodes.

  According to said manufacturing method, the humidity sensor which can detect a humidity change more efficiently compared with the past can be provided.

  Moreover, a part of the manufacturing method is realized by almost the same process as the manufacturing process of the semiconductor chip. Therefore, according to the manufacturing method described above, since the semiconductor chip manufacturing apparatus can be used to manufacture the humidity sensor, the humidity sensor according to the present embodiment can be manufactured at a relatively low cost.

[Additional Notes]
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment.

  The present invention can be suitably used for a humidity sensor.

1, 2 Humidity sensor 11, 21 Substrate 12, 22 Metal wiring (wiring)
13 Silicon nitride film 14 Silicon oxide film (sacrificial film)
15 opening 16, 26 conductive film (electrode, plural electrodes)
17 Moisture sensitive film 18 Protective film

Claims (5)

A humidity sensor that detects the humidity of the environmental atmosphere based on capacitance between a plurality of electrodes,
A substrate,
A protective film facing the substrate;
A plurality of electrodes provided so that one end abuts the substrate;
Between the substrate and the protective film, provided with a moisture sensitive film whose dielectric constant changes due to the humidity change of the environmental atmosphere,
A humidity sensor, wherein the other ends of the plurality of electrodes are in contact with the protective film. The shape of the plurality of electrodes is a columnar shape,
The humidity sensor according to claim 1. The plurality of electrodes are elliptic cylinders having a minor axis of 0.1 μm or more,
The humidity sensor according to claim 2, wherein the distance between the plurality of electrodes is set to be 0.1 μm or more. The plurality of electrodes are polygonal columns having a side of 0.1 μm or more,
The humidity sensor according to claim 2, wherein the distance between the plurality of electrodes is set to be 0.1 μm or more. A method of manufacturing a humidity sensor that measures the humidity of an environmental atmosphere based on capacitance between a plurality of electrodes,
A wiring forming step of forming conductive wiring on the substrate;
An electrode forming step of forming a plurality of electrodes by depositing a conductive film on the wiring;
A moisture-sensitive film forming step of forming a moisture-sensitive film having a dielectric constant that changes due to a change in humidity of the environmental atmosphere in the gap between the plurality of electrodes;
And a protective film forming step of forming a protective film so as to contact the plurality of electrodes.

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