Liquid droplet sensor, dew detection device and manufacturing method thereof

Abstract

The present invention provides: a droplet sensor which has stable detection characteristics, little production variation among elements even when mass-produced, and high detection accuracy, and can obtain a high electric output; a dew condensation detection device; and a method for producing the droplet sensor and the dew condensation detection device. This droplet sensor is provided with an insulating substrate, a first electrode having a first thin wire and a first current collector, and a second electrode having a second thin wire and a second current collector, wherein: the first electrode and the second electrode are arranged on the insulating substrate; the first thin wire and the second thin wire are alternately juxtaposed on the insulating substrate; and a galvanic current, which flows between the first thin wire and the second thin wire via a conductive droplet, is detected. The first thin wire is composed of a first metal-containing material layer having a lower electric resistivity than platinum, the second thin wire is composed of a composite film of the first metal-containing material layer and a platinum-containing material including platinum or a platinum alloy, and at least a part of the surface of the platinum-containing material layer is exposed to the outside.

Description

[Technical field]

[0001] The present invention relates to a liquid drop sensor and a dew condensation detection device, and more particularly to a liquid drop sensor and a dew condensation detection device with high accuracy and sensitivity in liquid drop detection, and a method for manufacturing the same. [Background technology]

[0002] Known liquid droplet sensors and condensation detection devices that utilize them include elements that measure changes in the electrical resistance (impedance) or capacitance of the sensor element, as well as elements that detect the galvanic current that flows between two types of metal via liquid droplets (galvanic droplet sensors). Among these, the galvanic type droplet sensor has a number of features, including a simple structure, compact size, high droplet detection sensitivity, and the ability to operate without necessarily requiring an external power source.

[0003] This galvanic droplet sensor is a sensor having a structure in which a large number of wires made of two different metals are arranged at minute intervals, and detects droplets by detecting the current that flows between the metal wires when a conductive droplet touches the minute interval. This galvanic droplet sensor is disclosed, for example, in Patent Document 1. Also, Non-Patent Document 1 proposes that in a galvanic droplet sensor using aluminum / gold as a combination of different metals, the gold cathode is coated with platinum to increase the electrical output.

[0004] Condensation on the surface of an object can cause mold and rust, and can scatter light. For example, in the case of walls, mold often grows on the wall material and contaminants on its surface when moisture from condensation is present, and in the case of metal, rust occurs due to corrosion. Condensation in a food store can cause food to lose its taste and quality. It can also lead to hygiene problems, such as food being more susceptible to mold. Condensation on transparent materials such as window glass can cause fogging. Condensation on a lens due to high humidity can scatter the light entering the lens, causing the image to become distorted and reducing the imaging performance of the lens. If the size of each droplet of condensation is small, the image will appear flared, reducing the contrast of the image. For this reason, it is essential to detect condensation accurately and with high sensitivity, and there is high demand for condensation detection devices with high accuracy and sensitivity. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2016 / 13544 [Non-patent literature]

[0006] [Non-Patent Document 1] RG Shrestha,et al.,ECS Transactions,98(11)35-47(2020) Summary of the Invention [Problem to be solved by the invention]

[0007] When manufacturing multiple conventional galvanic droplet sensors and condensation detection devices using them, it was found that the detection accuracy of each sensor (element) was not stable, and the detection sensitivity (detected galvanic current (electrical output)) was not necessarily sufficient. The object of the present invention is to solve these conventional problems and provide a droplet sensor and condensation detection device with stable detection characteristics, which have little manufacturing variation (variation due to the manufacturing process) between droplet sensors and condensation detection devices even when manufactured in large quantities, have high detection accuracy, and can provide a high electrical output, as well as a method for manufacturing the same. [Means for solving the problem]

[0008] The configuration of the present invention is shown below. (Configuration 1) An insulating substrate; a first electrode having a first wire and a first current collector; a second electrode having a second wire and a second current collector; the first electrode and the second electrode are disposed on the insulating substrate, and the first thin wires and the second thin wires are alternately arranged in parallel on the insulating substrate; A droplet sensor that detects a galvanic current flowing between the first thin wire and the second thin wire through a conductive droplet, the first thin wire and the first current collector are made of a first metal-containing layer having an electrical resistivity lower than that of platinum; the second thin wire is made of a composite film of the first metal-inclusive layer and a platinum-inclusive layer made of platinum or a platinum alloy, the second current collector includes the first metal-inclusive layer, At least a portion of the surface of the platinum-containing layer is exposed to the outside. (Configuration 2) 2. The droplet sensor according to claim 1, wherein the second thin wire is a laminated film of the first metal-containing layer and the platinum-containing layer. (Configuration 3) 2. The droplet sensor according to claim 1, wherein the second thin wire has a core portion made of the first metal-containing layer, and the platinum-containing layer is formed on at least a portion of a side wall portion of the core portion. (Configuration 4) 2. The droplet sensor according to claim 1, wherein the second thin wire has a core portion made of the first metal-containing layer, and the platinum-containing layer is formed so as to cover the core portion. (Configuration 5) 5. The droplet sensor of any one of configurations 1 to 4, wherein the spacing between the first thin wire and the second thin wire is constant. (Configuration 6) 6. The droplet sensor of any one of claims 1 to 5, wherein the first metal-containing layer is comprised of one or more metals selected from the group consisting of aluminum (Al), magnesium (Mg), zinc (Zn), iron (Fe), cobalt (Co), nickel (Ni), molybdenum (Mo), copper (Cu), silver (Ag), gold (Au), and tungsten (W), or an alloy containing one or more metals selected from the group. (Configuration 7) 7. The droplet sensor of any one of claims 1 to 6, wherein the platinum-containing layer has a thickness of 5 nm or more and 150 nm or less. (Configuration 8) 8. A droplet sensor according to any one of configurations 1 to 7, wherein the distance between the first thin wire and the second thin wire is 100 nm or more and 100 μm or less. (Configuration 9) 9. The droplet sensor of configuration 8, wherein the distance between the first thin wire and the second thin wire is 100 nm or more and 10 μm or less. (Configuration 10) A dew detection device equipped with the droplet sensor described in any one of configurations 1 to 9. (Configuration 11) Producing an intermediate structure having a pattern made of a platinum-containing layer made of platinum or a platinum alloy formed on an insulating substrate; forming a first metal-containing layer on the intermediate structure, the first metal-containing layer including a metal having an electrical resistivity lower than that of platinum; A method for manufacturing a droplet sensor or a condensation detection device, comprising: forming, on the insulating substrate, a first electrode having a first thin wire made of the first metal inclusion layer and a first current collector made of the first metal inclusion layer, and a second electrode having a second thin wire made of a composite film of the platinum inclusion layer and the first metal inclusion layer and a second current collector including the first metal inclusion layer, by a single lithography process; and arranging the first thin wire and the second thin wire alternately on the insulating substrate. (Configuration 12) forming a first metal-containing layer containing a metal having an electrical resistivity lower than that of platinum on an insulating substrate; Producing an intermediate structure having a pattern formed of a laminate in which a platinum-containing layer made of platinum or a platinum alloy is laminated on the first metal-containing layer; A method for manufacturing a droplet sensor or a condensation detection device, comprising: forming, on the insulating substrate, a first electrode having a first thin wire made of the first metal inclusion layer and a first current collector made of the first metal inclusion layer, and a second electrode having a second thin wire made of a composite film of the platinum inclusion layer and the first metal inclusion layer and a second current collector including the first metal inclusion layer, by a single lithography process; and arranging the first thin wire and the second thin wire alternately on the insulating substrate. (Configuration 13) A method for manufacturing a liquid droplet sensor or dew condensation detection device, comprising: a first electrode having a first thin wire made of a first metal inclusion layer containing a metal having a lower electrical resistivity than platinum and a first current collector made of the first metal inclusion layer, and a second electrode having a second thin wire made of a composite film of the first metal inclusion layer and a platinum inclusion layer made of platinum or a platinum alloy and a second current collector including the first metal inclusion layer, the first thin wire and the second thin wire being alternately arranged on the insulating substrate, the method comprising: forming a temporary electrode on the insulating substrate, the temporary electrode being made of the first electrode and the first metal-containing layer and having the same pattern as the second electrode or a pattern obtained by subjecting the second electrode to a ressence treatment, to prepare an intermediate structure; forming the second electrode by electroplating the platinum-containing layer on at least a surface of the fine wire of the temporary electrode of the intermediate structure. (Configuration 14) 14. The method of claim 13, wherein the first electrode and the temporary electrode are formed by a single lift-off process. (Configuration 15) 14. The method of claim 13, wherein the first electrode and the temporary electrode are formed by a single deposition of the first metal inclusion on the insulating substrate, a single lithography step, and an etching step. (Configuration 16) A first metal having an electrical resistivity smaller than that of platinum is formed on an insulating substrate. metal A method for manufacturing a liquid droplet sensor or dew condensation detection device, comprising: a first electrode having a first thin wire made of an inclusion layer and a first current collector made of the first metal inclusion layer; and a second electrode having a second thin wire made of a composite film of the first metal inclusion layer and a platinum inclusion layer made of platinum or a platinum alloy and a second current collector including the first metal inclusion layer, the first thin wires and the second thin wires being alternately arranged on the insulating substrate, the method comprising: forming the first metal-containing layer and an oxide insulating film in sequence on the insulating substrate; forming a temporary electrode having the same pattern as the first electrode and the second electrode or a pattern obtained by subjecting the pattern of the second electrode to a lithography process on the insulating substrate to prepare an intermediate structure; depositing a platinum-containing material on the intermediate structure to form a platinum-containing material layer; Anisotropic etching is performed to remove the first thin wire and the first electrode. A platinum-containing layer is formed only on a side wall portion of the first current collector, and The temporary electrode Wire and current collector forming a second electrode having a platinum-containing layer formed only on a side wall portion of the second electrode; forming a resist pattern formed by subjecting the pattern of the second electrode to a broadon process, and removing the platinum-containing layer in a portion not protected by the resist pattern by etching; removing the resist pattern. (Configuration 17) The method for manufacturing a droplet sensor or a dew detection device according to claim 16, wherein the oxide insulating film is made of an oxide containing one or more substances selected from the group consisting of yttrium (Y), aluminum, silicon (Si), and cerium (Ce). (Configuration 18) 18. The method for manufacturing a droplet sensor or condensation detection device according to any one of claims 11 to 17, wherein the first metal-containing layer is made of one or more metals selected from the group consisting of aluminum, magnesium, zinc, iron, cobalt, nickel, molybdenum, copper, silver, gold, and tungsten, or an alloy containing one or more metals selected from the group. (Configuration 19) 19. The method for manufacturing a droplet sensor or condensation detection device according to any one of claims 11 to 18, wherein the platinum-containing layer has a thickness of 5 nm or more and 150 nm or less. (Configuration 20) 20. The method for manufacturing a droplet sensor or a dew detection device according to any one of configurations 11 to 19, wherein the distance between the first thin wire and the second thin wire is 100 nm or more and 100 μm or less. Effect of the Invention

[0009] According to the present invention, there are provided a droplet sensor and a condensation detection device having stable detection characteristics, with little manufacturing variation between elements even when mass-produced, high detection accuracy, and a high electrical output, as well as methods for manufacturing the same. [Brief description of the drawings]

[0010] [Figure 1] 2 is a bird's-eye view explaining the configuration and operation of a galvanic type liquid drop sensor 201. FIG. [Diagram 2] 2A and 2B are diagrams showing the configuration of the main parts of a galvanic liquid drop sensor 201, in which (a) is a top view and (b) is a cross-sectional view. [Diagram 3] FIG. 2 is a top view illustrating one of the problems with conventional galvanic drop sensors. [Figure 4] FIG. 2 is a cross-sectional view illustrating the configuration of a main part of the galvanic droplet sensor of the present invention. [Diagram 5] 1A to 1C are cross-sectional views showing the manufacturing process of the first galvanic drop sensor 101 of the present invention. [Figure 6] 1A to 1C are manufacturing process diagrams showing, in plan view, the manufacturing process of the first galvanic type liquid drop sensor 101 of the present invention. [Figure 7] 3A to 3C are cross-sectional views showing the manufacturing process of the second galvanic drop sensor 102 of the present invention. [Figure 8] 1A to 1C are manufacturing process diagrams showing, in plan view, the manufacturing process of the second galvanic type droplet sensor 102 of the present invention. [Figure 9] 10A to 10C are cross-sectional views showing the manufacturing process of the third galvanic drop sensor 103 of the present invention. [Figure 10] 10A to 10C are manufacturing process diagrams showing, in plan view, the manufacturing process of the third galvanic type droplet sensor 103 of the present invention. [Figure 11] 10A to 10C are cross-sectional views showing the manufacturing process of the fourth galvanic drop sensor 104 of the present invention. [Figure 12] 10A to 10C are manufacturing process diagrams showing, in plan view, the manufacturing process of the fourth galvanic drop sensor 104 of the present invention. [Figure 13] FIG. 11 is a plan view illustrating the configuration of a sample before Pt plating treatment in Example 2. [Figure 14] In Example 2, a photograph (left) shows the upper surface of a sample (part including the first fine wire and the first current collector) observed with an optical microscope before Pt plating, and a photograph (right) shows the upper surface of the sample observed with an optical microscope after Pt plating was performed on the Al layer constituting the first fine wire and the first current collector. [Figure 15] In Example 2, a photograph (left) shows the top surface of a sample (including the second fine wire and the second current collector) observed with an optical microscope before Pt plating, and a photograph (right) shows the top surface of the sample observed with an optical microscope after Pt plating was performed on the Au layer that constitutes the second fine wire and the second current collector. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <Concept and structure> As shown in Figure 1, the galvanic droplet sensor 201 is a current detection sensor in which thin wires made of different metals (metals A and B) are arranged side by side on an insulating substrate, and when a conductive droplet such as a water droplet touches the space between the first thin wire 1 and the second thin wire 2, a galvanic current flows between the thin wires. As shown in FIG. 2, the electrode 202 of the galvanic liquid drop sensor 201 is composed of a first thin wire 1, a first current collector 3 electrically connected to the first thin wire 1 (these are also collectively referred to as a first electrode 5), and a second thin wire 2, a second current collector 4 electrically connected to the second thin wire 2 (these are also collectively referred to as a second electrode 6). Here, as described above, the metal constituting the first thin wire 1 is different from the metal constituting the second thin wire 2. In terms of wiring fabrication, it is preferable that the first thin wire 1 and the first current collector 3, and the second thin wire 2 and the second current collector 4 are each composed of the same material, but from the viewpoint of electrical resistance, it is also preferable that the first current collector 3 and the second current collector 4 are composed of the same material and that the wiring drawn out from the galvanic liquid drop sensor 201 is also composed of the same material. In addition, (a) in Figure 2 is a top view, (b) is a cross-sectional view cut along AA' in Figure 2(a), 7 is an insulating substrate, and d is the distance between the first fine wire 1 and the second fine wire 2.

[0012] In this conventional galvanic drop sensor 201, different materials (metals) are used for the first thin wire 1 and the second thin wire 2, so during manufacture it was necessary to carry out a first lithography for forming the first thin wire 1 and a second lithography for forming the second thin wire 2 separately. For this reason, misalignment inevitably occurs between the first and second lithography. This is shown in FIG. 3, which shows the electrode (thin wire and current collector) pattern 202a of the galvanic drop sensor 201 from above.

[0013] In the galvanic type liquid drop sensor 201, not only is the line width L of the first thin wire 1 and the second thin wire 2 minute, but the distance d between the first thin wire 1 and the second thin wire 2 is also narrow. When misalignment X during manufacturing is added to this, the wide distance d1 becomes (d+X) and the narrow distance d2 becomes (dX), and the difference between the wide distance d1 and the narrow distance d2, Δd=d1-d2, becomes (d+X)-(dX)=2X. Generally, the alignment accuracy of lithography is 1 / 5 to 1 / 4 of the width of the pattern to be formed. Therefore, for example, if the designed interval d is 1 μm, an alignment error of 0.2 to 0.25 μm must be tolerated. In this case, the fluctuation width of the pattern interval d to be formed will be 0.75 μm to 1.25 μm, and the value will fluctuate by as much as 0.5 μm (Δd = 2 × 0.25) when it is larger than the design value of 1 μm.

[0014] Since the galvanic liquid drop sensor 201 detects when a liquid drop comes into contact with the first thin wire 1 and the second thin wire 2, the distance d between the first thin wire 1 and the second thin wire 2 directly affects the size of the liquid drop to be detected. For this reason, the accuracy of the distance d is extremely important for the galvanic liquid drop sensor 201. Since a large misalignment such as that described above is unacceptable, it is necessary to select a sensor whose distance d falls within the allowable range, which results in a low product yield.

[0015] The structure of the thin wire constituting the droplet detection unit, which is the main part of the galvanic droplet sensor according to the embodiment of the present invention, is shown in Fig. 4. The structures are roughly divided into four types, first to fourth galvanic droplet sensors 101 to 104 shown in Fig. 4(a) to (d), and in each of them, the first thin wire is made of a first metal-containing layer having a lower electrical resistivity than platinum, and the second thin wire is made of a composite film of the first metal-containing layer and a platinum-containing layer such as platinum or a platinum alloy. Although not shown in Fig. 4, in the first to fourth galvanic droplet sensors 101 to 104, the first current collector is made of the first metal-containing layer, and the second current collector includes the first metal-containing layer. Here, at least a part of the surface of the platinum-containing layer of the second thin wire is exposed to the outside. In other words, the second thin wire is formed so that at least a part of the surface of the platinum-containing layer constituting the composite film is exposed to the outside, and the exposed part is made contactable with a conductive droplet. Note that in this context, "exposed to the outside" means that the detection target droplet is in an environment that can contact it, and does not limit whether the space in which the droplet sensor itself is placed is an open system or a closed system.

[0016] As will be explained in the manufacturing method section below, in the first to fourth galvanic type droplet sensors 101 to 104, the arrangement of the first thin wire 12 and the second thin wire 13 is determined by a single lithography process, so that the intervals d1 and d2 between the first thin wire 12 and the second thin wire 13 can be made the same value. This makes it possible to prevent a decrease in droplet detection accuracy caused by variations in the thin wire intervals. In addition, since the second thin wire 13 has a layer made of a platinum-containing material such as platinum or a platinum alloy that produces a high galvanic effect (high electromotive current) and is composed of a composite film with a layer made of a first metal-containing material that is an electrical conductor with a lower resistivity than platinum, a large galvanic current flows when a conductive droplet straddles between the first thin wire 12 and the second thin wire 13. This increases the droplet detection sensitivity of the droplet sensor. Furthermore, the first and second current collectors, which correspond to the first current collector 3 and the second current collector 4 in the electrodes of a conventional galvanic liquid drop sensor, can also be made of the first metal-containing material without going through any special process, and the output terminal material of the liquid drop sensor can be made of one type of material. This makes it possible to avoid problems such as contact potential when connecting the liquid drop sensor to other devices such as an amplifier, analyzer, or alarm device.

[0017] Here, the first metal-containing substance can be one or more metals selected from the group consisting of aluminum (Al), magnesium (Mg), zinc (Zn), iron (Fe), cobalt (Co), nickel (Ni), molybdenum (Mo), copper (Cu), silver (Ag), gold (Au), and tungsten (W), or an alloy containing one or more metals selected from the group. Among these, Al is particularly preferred because it has low electrical resistance, is easy to process, is widely used, and has low material and process costs. Examples of Al alloys include Al-Cu, Al-Si, Al-Cu-Si, Al-Mn, Al-Mg, Al-Mg-Si, Al-Mg-Zn, and Al-Mg-Zn-Cu. By alloying, it is possible to improve various properties such as electromigration, electrical resistivity, processability, bending resistance, hardness, flexibility, reflectivity control that contributes to suppressing halation during photolithography, corrosion resistance, wear resistance, adhesion with different materials, hydrophilicity, and hydrophobicity. Examples of platinum alloys include Pt-Au, Pt-Pd, Pt-Ir, Pt-Rh, Pt-Co, Pt-Fe, Pt-Cr, etc. By using platinum alloys, it is possible to obtain the effects of improving electrical conductivity, catalytic activity, temperature coefficient, and poisoning resistance, and reducing the amount of platinum used.

[0018] As shown in Figure 4(a), the structure of the first galvanic type droplet sensor 101 is composed of a first thin wire 12 formed on an insulating substrate 11 and made of a first metal-containing layer having an electrical resistivity lower than that of platinum, and a second thin wire 13 which is a two-layer film having an upper layer 13a made of the same material as the first thin wire 12 and a lower layer 13b made of a platinum-containing material. This structure has the advantage that because the lower layer of the second thin wire is composed of a platinum-containing material, it can detect droplets even if they are in such small amounts that they accumulate at the bottom of the space between the thin wires (the droplets are on the insulating substrate and span the space between the thin wires).

[0019] The first fine wire 12 is electrically connected to a first current collector, the second fine wire 13 is electrically connected to a second current collector, and the first and second current collectors are connected to a signal output terminal via electrical wiring (not shown) connected thereto. Here, an amplifier may be connected to the first current collector and the second current collector to amplify the galvanic current that flows due to the presence of droplets.

[0020] When a first metal and a second metal with a different electrochemical potential are connected by a conductive liquid such as a water droplet, a galvanic current flows. Water has low conductivity and is insulating in its ultrapure state, but it can be broken down by at least 10 -7 When trace amounts of electrolytic components, such as hydrogen ions and hydroxide ions present in mol / L quantities or contaminants, are present, a measurable (detectable) galvanic current flows.

[0021] This structure uses two types of thin wires, which makes it possible to lengthen the area where the two thin wires face each other closely relative to the area of ​​the droplet detection section on the substrate (the area where the first and second electrodes are arranged), thereby increasing the galvanic current that can be extracted. Examples of configurations that increase the length of the adjacent portion between the thin wires (hereinafter referred to as the parallel running distance) by arranging such thin wires in parallel (alternately) include a comb structure and a double spiral structure. The structure itself for making the parallel running distance of two thin wires as long as possible within a certain planar area is well known in the field of semiconductor devices, etc., and such a structure may be adopted as necessary. In the present invention, "arranging thin wires juxtaposed on a substrate" does not specify the mutual orientation of multiple thin wires placed on the substrate, but refers to arranging the thin wires spaced apart on the same plane of the substrate.

[0022] The structure of the second galvanic type droplet sensor 102, as shown in Figure 4(b), is such that the order of the layers of the laminated film of the second thin wire 13 of the first galvanic type droplet sensor 101 is reversed, and the sensor comprises a first thin wire 12 formed on an insulating substrate 11 and made of a first metal-containing layer having an electrical resistivity lower than that of platinum, and a second thin wire 13 which is a two-layer film made of an upper layer 13b made of a platinum-containing material and a lower layer 13a made of the same material as the first thin wire 12. This structure has the characteristic that, because the upper layer of the second thin wire is composed of platinum inclusions, when a relatively large droplet that straddles the upper parts of the first and second thin wires is detected by the galvanic effect, the galvanic effect is enhanced by the platinum inclusions in the upper layer of the second thin wire, and an increase in current is simultaneously obtained due to the low electrical resistance of the first metal inclusions in the lower layer (i.e., sufficient current is supplied from the first metal inclusions in the lower layer to the platinum inclusions in the upper layer).

[0023] The structure of the third galvanic type droplet sensor 103, as shown in Figure 4(c), consists of a first thin wire 12 formed on an insulating substrate 11 and made of a first metal-containing layer having an electrical resistivity lower than that of platinum, and a second thin wire 13 having a core portion (base layer) 13a made of the same material as the first thin wire 12 and a composite film 13b made of a platinum-containing layer formed to cover the core portion. This structure has the advantage that the portion of the second thin wire 13 exposed to the outside is entirely made of platinum-containing material, and the electrical resistance can be significantly reduced by the first metal-containing material in the core portion, thereby achieving high and stable droplet detection sensitivity.

[0024] The structure of the fourth galvanic type droplet sensor 104, as shown in Figure 4(d), consists of a first thin wire 12 formed on an insulating substrate 11 and consisting of a first metal-containing layer having an electrical resistivity lower than that of platinum, with an oxide insulating film 14 formed on the upper surface as a cap, and a second thin wire 13 having a core portion (base layer) 13a made of the same material as the first thin wire 12, a platinum-containing layer 13b formed on the side wall of the core portion, and a composite film of the oxide insulating film 14 formed on the upper surface as a cap.

[0025] Here, the oxide insulating film 14 has the following functions: an etching mask function when etching the first metal-containing layer during sensor fabrication, a protective cap function to protect the first and second thin wires, and a steepness function to make the detection response according to the droplet size steep by insulating the upper surfaces of the first and second thin wires and limiting the path through which the galvanic current flows to the sidewalls of the first and second thin wires. Furthermore, by forming the oxide insulating film 14 from a hydrophobic or hydrophilic material and controlling the droplet wettability, it can also have a detection characteristic control function to improve the detection response according to the droplet size. The material for the oxide insulating film 14 is not particularly limited as long as it performs the above-mentioned functions, but oxides containing one or more substances selected from the group consisting of yttrium (Y), aluminum, silicon (Si), and cerium (Ce), specifically Y2O3, Al2O3, SiO2, and CeO2, are particularly preferably used.

[0026] In this structure, only the side wall of the second thin wire consisting of the first thin wire 12 and the platinum-containing layer 13b, which have constant distances d1 and d2, senses the contact of the droplet, so that the detection response (current-time curve) depending on the droplet size becomes steep, making it easy to identify the size of the droplet to be detected. In the first to fourth galvanic droplet sensors 101 to 104, the intervals d1 and d2 being constant does not necessarily mean that the measured values ​​of the intervals d1 and d2 are exactly the same. In other words, the interval between the first thin wire 12 and the second thin wire 13 being constant does not necessarily mean that the intervals between the first thin wire 12 and the second thin wire 13 are exactly the same, but includes errors resulting from the measurement accuracy (reproducibility) of an apparatus such as a CD-SEM (critical dimension SEM) used for measurement.

[0027] Here, in the first to fourth galvanic type droplet sensors 101 to 104, the distance between the first thin wire 12 and the second thin wire 13 in the droplet detection portion on the insulating substrate 11 (the region where the first electrode having the first thin wire 12 and the first current collector, and the second electrode having the second thin wire 13 and the second current collector are arranged) is preferably 100 nm or more and 100 μm or less, more preferably 100 nm or more and 10 μm or less. Within this range, droplets can be detected with good sensitivity. In addition, the thickness of the platinum-containing layer 13b is preferably 5 nm or more and 150 nm or less. If the thickness of the platinum-containing layer 13b is 5 nm or more, it is easy to ensure the uniformity of the thickness of the platinum-containing layer during sensor manufacturing, and the number of places where the platinum-containing layer is not formed, that is, so-called defective parts, is reduced, making it possible to obtain high droplet detection accuracy. In addition, by making the thickness of the platinum-containing layer 13b 150 nm or less, the ratio of the first metal inclusion, which has a relatively lower electrical resistivity than the platinum inclusion, in the second thin wire can be increased, and the electrical resistance of the second thin wire can be easily reduced. In addition, it is also possible to reduce the amount of platinum, which is expensive. Since the galvanic type droplet sensor is a current detection type sensor, it is extremely important to reduce the electrical resistance of the part that senses the contact of the droplet in order to obtain high droplet detection sensitivity.

[0028] <Method for manufacturing the first structure> A method for manufacturing the first galvanic type droplet sensor 101 will be described with reference to FIG. 5, which is a cross-sectional view, and FIG. 6, which is a plan view.

[0029] First, an insulating substrate 11 is prepared, and a platinum-containing layer pattern 21a made of a platinum-containing material is formed on the insulating substrate 11 to produce an intermediate structure 111 (see FIG. 5(a)). Examples of insulating substrate 11 include substrates in which a SiO2 oxide film is formed on a Si wafer, glass substrates such as synthetic quartz glass and soda lime glass, resin substrates such as acrylic, polystyrene (PS), polypropylene (PP), polyethylene terephthalate (PET) and polycarbonate (PC), and substrates in which a resin layer such as acrylic resin, methacrylate resin, novolac resin, polyester resin, polyamide resin, polyimide resin, polyamideimide resin and silicone resin is formed on the above substrates.

[0030] The pattern 21a of the platinum-containing layer is a pattern obtained by subjecting the pattern of the second electrode 18, which is a final product of the second fine wire 13 and the second current collector 16 integrated together, to a broadening process (see FIG. 6(a)). The amount of broadening can be determined by taking into consideration the amount of misalignment between lithographies. The pattern 21a of the platinum-containing layer can be formed by a method including deposition of a platinum-containing thin film such as Pt, lithography, and etching, or a lift-off method. The deposition method of a platinum-containing thin film can be a sputtering method, a deposition method, a CVD (Chemical Vapor Deposition) method, a coating method, or the like.

[0031] Next, a first metal inclusion constituting a first electrode in which the first thin wire and the first current collector are integrated is deposited on the intermediate structure 111 to form a first metal inclusion layer 22a (see FIG. 5(b)). Here, an example of the first metal inclusion is Al. Examples of a method for depositing the first metal inclusion (a method for forming the first metal inclusion layer 22a) include a sputtering method, a vapor deposition method, and a CVD method.

[0032] Thereafter, a resist pattern 23 including a resist pattern 23a of a first electrode 17 having a first thin wire 12 and a first current collector 15 to be finally formed, and a resist pattern 23b of a second electrode 18 having a second thin wire 13 and a second current collector 16 is formed by a single exposure (see Figures 5(c) and 6(b)).

[0033] Thereafter, using the resist pattern 23 as an etching mask, the first metal-containing material layer 22a is etched to form a pattern 22 of the first metal-containing material layer (see FIG. 5(d)), and then using the resist pattern 23 as an etching mask, the platinum-containing material layer pattern 21a is also etched to form a platinum-containing material layer pattern 21 (see FIG. 5(e)). When Al is used as the first metal-containing material, the etching gas that can be used here may be a chlorine-, bromine-, or iodine-based gas.

[0034] Thereafter, the resist pattern 23 is removed by ashing or a stripping solution, and a first galvanic type liquid drop sensor 101 is fabricated, in which a first electrode 17 having a first thin wire 12 and a first current collector 15, and a second electrode 18 having a second thin wire 13 and a second current collector 16 are formed (see FIG. 5(f) and FIG. 6(c)). Here, the first thin wire 12 is configured as a part of a pattern 22 of a first metal-containing material layer, and the second thin wire 13 is configured as a part of a pattern 21 of a platinum-containing material layer consisting of a part (13a) of the pattern 22 of the first metal-containing material layer and a platinum-containing material layer (13b). In this method, a first current collector 15 having the same configuration as the first thin wire 12 and a second current collector 16 having the same configuration as the second thin wire 13 can also be formed at the same time. That is, in this method, a first electrode 17 is formed by integrating a first thin wire 12 and a first current collector 15, and a second electrode 18 is formed by integrating a second thin wire 13 and a second current collector 16, and the area in which the first electrode 17 and the second electrode 18 are formed constitute the droplet detection portion of the first galvanic type droplet sensor 101.

[0035] In the first galvanic type liquid drop sensor 101 thus manufactured, the arrangement of the first thin wire 12 and the second thin wire 13 (i.e., the arrangement of the first electrode 17 and the second electrode 18) is determined by the resist pattern 23 formed by a single exposure, so the difference Δd between the distances d1 and d2 between the first thin wire 12 and the second thin wire 13 can be made 0. This makes it possible to prevent a decrease in the accuracy of liquid drop detection caused by variations in the thin wire distances. In addition, since second current collector 16 has the same configuration as second thin wire 13, and the upper layer is made of the first metal-containing layer and is made of the same material as first current collector 15, the wiring drawn out from first galvanic type droplet sensor 101 can be made of the same material. Therefore, first galvanic type droplet sensor 101 manufactured by this method has a preferable structure from the viewpoint of the electrical resistance described above.

[0036] <Method for manufacturing the second structure> A method for manufacturing the second galvanic type droplet sensor 102 will be described with reference to the cross-sectional view of FIG. 7 and the plan view of FIG.

[0037] First, an insulating substrate 11 is prepared, and a first metal inclusion such as Al having a lower electrical resistivity than platinum is deposited on the insulating substrate 11 to form a first metal inclusion layer 31a (see Fig. 7(a) and Fig. 8(a)). Here, the insulating substrate 11 may be the same as that described in the manufacturing method of the first structure. Examples of a method for depositing the first metal inclusion (a method for forming the first metal inclusion layer 31a) include a sputtering method, a vapor deposition method, and a CVD method.

[0038] Next, a platinum-containing material layer pattern 32a made of a platinum-containing material is formed (laminated) on the first metal-containing material layer 31a to produce an intermediate structure 112 (see FIG. 7(b) and FIG. 8(b)). The pattern 32a of the platinum-containing layer is a pattern obtained by subjecting the pattern of the second electrode 18, which is to be finally formed by integrating the second fine wire 13 and the second current collector 16, to a broadening process (see FIG. 8(b)). The amount of broadening can be determined by taking into consideration the amount of misalignment between lithographies. The pattern 32a of the platinum-containing layer can be formed by a method including deposition of a platinum-containing thin film such as Pt, lithography, and etching, or a lift-off method. The deposition method of a platinum-containing thin film can be sputtering, vapor deposition, CVD, coating, plating, or the like.

[0039] Thereafter, a resist pattern 33 including a resist pattern 33a of a first electrode 17 having a first thin wire 12 and a first current collector 15 to be finally formed, and a resist pattern 33b of a second electrode 18 having a second thin wire 13 and a second current collector 16 is formed by a single exposure (see Figures 7(c) and 8(c)).

[0040] Thereafter, using resist pattern 33 as an etching mask, platinum-containing material layer pattern 32a and first metal-containing material layer 31a are etched to form platinum-containing material layer pattern 32 and first metal-containing material layer pattern 31 (see FIG. 7(d)). When Al is used as the first metal-containing material, the etching gas that can be used here may be a chlorine-, bromine-, or iodine-based gas.

[0041] Thereafter, the resist pattern 33 is removed by ashing or a stripping solution, and a second galvanic type liquid drop sensor 102 is fabricated in which a first electrode 17 having a first thin wire 12 and a first current collector 15, and a second electrode 18 having a second thin wire 13 and a second current collector 16 are formed (see FIG. 7(e) and FIG. 8(d)). Here, the first thin wire 12 is configured as a part of a first metal-containing layer pattern 31, and the second thin wire 13 is configured as a part of a platinum-containing layer pattern 32 consisting of a part (13a) of the first metal-containing layer pattern 31 and a platinum-containing layer (13b). In this method, a first current collector 15 having the same configuration as the first thin wire 12 and a second current collector 16 having the same configuration as the second thin wire 13 can also be formed at the same time. That is, in this method, a first electrode 17 is formed by integrating a first thin wire 12 and a first current collector 15, and a second electrode 18 is formed by integrating a second thin wire 13 and a second current collector 16, and the area in which the first electrode 17 and the second electrode 18 are formed constitute the droplet detection portion of the second galvanic type droplet sensor 102.

[0042] In the second galvanic type liquid drop sensor 102 thus manufactured, the arrangement of the first thin wire 12 and the second thin wire 13 (i.e., the arrangement of the first electrode 17 and the second electrode 18) is determined by the resist pattern 33 formed by a single exposure, so the difference Δd between the distances d1 and d2 between the first thin wire 12 and the second thin wire 13 can be made 0. This makes it possible to prevent a decrease in the liquid drop detection accuracy caused by variations in the thin wire distances. In addition, since second current collector 16 has the same configuration as second thin wire 13, and the lower layer is made of the first metal-containing layer and is made of the same material as first current collector 15, the wiring drawn out from second galvanic type droplet sensor 102 can be made of the same material. Therefore, second galvanic type droplet sensor 102 manufactured by this method has a preferable structure from the viewpoint of the electrical resistance described above.

[0043] <Method for manufacturing the third structure> A method for manufacturing the third galvanic type droplet sensor 103 will be described with reference to FIG. 9, which is a cross-sectional view, and FIG. 10, which is a plan view.

[0044] First, an insulating substrate 11 is prepared, and a first metal inclusion such as Al having a lower electrical resistivity than platinum is deposited on the insulating substrate 11 to form a first metal inclusion layer 41a (see FIG. 9(a)). Here, the insulating substrate 11 may be the same as that described in the manufacturing method of the first structure. Examples of a method for depositing the first metal inclusion (a method for forming the first metal inclusion layer 41a) include a sputtering method, a vapor deposition method, and a CVD method.

[0045] Next, a resist pattern 43 is formed (see FIG. 9(b)). Resist pattern 43 is made up of resist pattern 43b having a pattern obtained by subjecting the pattern of second electrode 18, which is an integrated second thin wire 13 and second current collector 16 to be finally formed, to a ressence treatment, and resist pattern 43a having a pattern obtained by subjecting the pattern of first electrode 17, which is an integrated first thin wire 12 and first current collector 15, to a merge treatment. Here, the amount of ressence is determined with reference to the thickness of the platinum-containing layer to be formed on the sidewall of the second thin wire.

[0046] Thereafter, the first metal-containing layer 41a is etched using the resist pattern 43 as an etching mask. When Al is used as the first metal-containing material, the etching gas may be a chlorine-, bromine-, or iodine-based gas. Thereafter, resist pattern 43 is removed by ashing, a stripping solution, or the like to form first metal-containing layer pattern 41, and intermediate structure 113 is fabricated (see Fig. 9(d) and Fig. 10(a)). At this time, the portion of first metal-containing layer pattern 41 formed via resist pattern 43b that corresponds to the second electrode to be finally formed becomes a temporary electrode (i.e., a portion including a temporary thin wire corresponding to the second thin wire and a temporary current collector corresponding to the second current collector).

[0047] Next, the intermediate structure 113 (insulating substrate 11 on which the first metal inclusion layer pattern 41 is formed) is immersed in an electroplating electrolyte solution, and a voltage is applied to the above-mentioned temporary electrode (i.e., the portion of the pattern to be the second thin wire and the second current collector) of the first metal inclusion layer pattern 41 to coat the surface of the temporary electrode (the portion of the pattern to be the second thin wire and the second current collector) with a platinum inclusion, forming a second electrode 18 having the second thin wire 13 and the second current collector 16, with the first metal inclusion layer pattern 41 serving as a core portion (base layer) and the platinum inclusion layer 42 formed so as to cover it (see Figures 9(e) and 10(b)). At this time, the pattern of the first metal inclusion layer 41 to which no voltage is applied becomes the first electrode 17 having the first thin wire 12 made of the first metal inclusion layer and the first current collector 15. In this manner, the third galvanic type liquid drop sensor 103 is fabricated. When performing electroplating, it is preferable to form a resist pattern so as to cover the areas to which no voltage is applied (the areas of the pattern that will become the first fine wires and the first current collector) in order to suppress the occurrence of defects due to plating.

[0048] In the third galvanic type droplet sensor 103 manufactured in this manner, the arrangement of the first thin wire 12 and the second thin wire 13 (i.e., the arrangement of the first electrode 17 and the second electrode 18) is determined by the resist pattern 43 formed by a single exposure, so that variation in the spacing between the first thin wire 12 and the second thin wire 13 can be suppressed, and a decrease in droplet detection accuracy caused by variation in the spacing between the thin wires can be prevented. In addition, since second current collector 16 has the same configuration as second thin wire 13, and its core portion (base layer) is made of the first metal-containing layer and is made of the same material as first current collector 15, the wiring drawn out from third galvanic type droplet sensor 103 can be made of the same material. Therefore, third galvanic type droplet sensor 103 manufactured by this method has a preferable structure from the viewpoint of the above-mentioned electrical resistance.

[0049] <Manufacturing method of the fourth structure> A method for manufacturing the fourth galvanic type droplet sensor 104 will be described with reference to FIG. 11, which is a cross-sectional view, and FIG. 12, which is a plan view.

[0050] First, an insulating substrate 11 is prepared, and a first metal-containing material such as Al having a lower electrical resistivity than platinum is deposited on the insulating substrate 11 to form a first metal-containing layer 51a, followed by the formation of an oxide insulating film 54a (see FIG. 11(a)). Here, the insulating substrate 11 may be the same as that described in the manufacturing method of the first structure. Examples of a method for depositing the first metal-containing material (a method for forming the first metal-containing layer 51a) include a sputtering method, a vapor deposition method, and a CVD method. As the material of the oxide insulating film 54a, an oxide containing one or more substances selected from the group consisting of yttrium (Y), aluminum, silicon (Si), and cerium (Ce), specifically Y2O3, Al2O3, SiO2, and CeO2, can be preferably used, and these films can be formed by a sputtering method, a CVD method, a spin coating method, etc. The thickness of the oxide insulating film 54a may be set to a thickness that is equal to or greater than the thickness remaining after etching the first metal-containing layer 51a.

[0051] Next, a resist pattern 53 is formed. The resist pattern 53 is a resist pattern 53b having a pattern of the second electrode 18 in which the second thin wire 13 and the second current collector 16 to be finally formed are integrated, which is subjected to a Ressene process, and a resist pattern 53a having a pattern of the first electrode 17 in which the first thin wire 12 and the first current collector 15 are integrated, which is subjected to a merge process. Here, the amount of Ressene is determined with reference to the thickness of the platinum-containing layer formed on the sidewall of the second thin wire, but it is also possible to omit the Ressene process. This is because what is important for the galvanic type droplet sensor in detecting droplets is the interval between the first and second thin wires, and the line width of the first and second thin wires has little effect. In particular, in the fourth galvanic type droplet sensor 104, the place where the two types of metals are formed (the place where the droplet straddles between the two types of metals) is only the sidewall of the thin wire, so the line width of the first and second thin wires has almost no effect on the detection characteristics of the droplets.

[0052] Thereafter, the oxide insulating film 54a is etched using the resist pattern 53 as an etching mask, and then the first metal-containing layer 51a is etched (FIG. 11(b)). Here, when etching the first metal-containing layer 51a, the resist pattern 53 may be left and both the resist pattern 53 and the oxide insulating film pattern 54 may be used as an etching mask, or the resist pattern 53 may be removed and the oxide insulating film pattern 54 may be used as an etching mask (FIG. 11(b) shows the former case in which the resist pattern 53 is left). A fluorine-based gas can be preferably used as an etching gas for the oxide insulating film 54a, and a chlorine-based gas, a bromine-based gas, or an iodine-based gas with added oxygen can be preferably used as an etching gas for the first metal-containing layer 51a. Thereafter, the resist pattern 53 is removed by ashing or a stripping solution to form a pattern consisting of an oxide insulating film pattern 54 and a first metal-containing layer pattern 51, thereby producing an intermediate structure 114 (see Figures 11(c) and 12(a)).

[0053] Next, a platinum-containing material is deposited on the intermediate structure 114 (the insulating substrate 11 on which the above-mentioned pattern is formed) to form a platinum-containing material layer 55a (FIG. 11(d)). The deposition of the platinum-containing material is preferably conformal deposition. Examples of deposition methods include sputtering, vapor deposition, and CVD, but electroplating may also be used. In the electroplating method, the intermediate structure 114 (insulating substrate 11 on which the above pattern is formed) is immersed in a plating solution, and a voltage is applied to the pattern 51 of the first metal-containing layer.

[0054] Thereafter, anisotropic etching is performed to remove the platinum-containing layer formed on the flat surface (the surface parallel to the surface of insulating substrate 11), leaving platinum-containing layer 55 on the side wall portion (the surface approximately perpendicular to the surface of insulating substrate 11) of pattern 51 of the first metal-containing layer (see Figures 11(e) and 12(b)). In addition, when the platinum-containing material is deposited by applying an electroplating method, the insulator is not plated, and the platinum-containing material is deposited only on the sidewall of the first metal-containing layer pattern 51, which is the location where the conductive material is exposed, without going through a full-cover deposition state (a state in which a platinum-containing layer is formed on the entire surface of the insulating substrate 11 and the surface of the pattern formed on the surface) as shown in FIG. 11(d), and a structure as shown in FIG. 11(e) is obtained. Therefore, the electroplating method has the effect of reducing the number of steps. On the other hand, the method of forming a platinum-containing layer on the sidewall of the first metal-containing layer pattern 51 by combining deposition and anisotropic etching is characterized by excellent shape controllability.

[0055] after that, Second thin line 13 and Second current collector 16 The part that becomes ( Second electrode 18 A resist pattern 56 is formed so as to cover the platinum-containing layer (portions that will become the platinum-containing layer) (see FIG. 11(f) and FIG. 12(c)), and the platinum-containing layer in the areas not covered with the resist is removed by a wet etching solution or the like (see FIG. 11(g) and FIG. 12(d)). Finally, the resist pattern 56 is removed by ashing or a stripping solution, and a fourth galvanic type liquid drop sensor 104 is formed, which includes a first electrode 17 having a first thin wire 12 and a first current collector 15, the first thin wire 12 being made of a first metal-containing layer whose upper surface is capped with an oxide insulating film pattern 54, and a second electrode 18 having a second thin wire 13 and a second current collector 16, the second thin wire 13 being made of a first metal-containing layer whose core (base layer) is made of a first metal-containing layer and a platinum-containing layer formed on a sidewall, the second electrode 18 being capped with an oxide insulating film pattern 54, and the second current collector 16 (see Fig. 11(h), Fig. 12(e), Fig. 12(e')). Note that Fig. 12(e) is a view from the top, and Fig. 12(e') is a view seen through from the top of the first and second electrode patterns (a position below the lower surface of the oxide insulating film) as a height position (position in the thickness direction).

[0056] In the fourth galvanic type droplet sensor 104 manufactured in this manner, the arrangement of the first thin wire 12 and the second thin wire 13 (i.e., the arrangement of the first electrode 17 and the second electrode 18) is determined by the resist pattern 53 formed by a single exposure, so that variation in the spacing between the first thin wire 12 and the second thin wire 13 can be suppressed, and a decrease in droplet detection accuracy caused by variation in the spacing between the thin wires can be prevented. In addition, the second current collector 16 has the same configuration as the second thin wire 13, and its core (base layer) is made of the first metal-containing layer and is made of the same material as the first current collector 15 (excluding the oxide insulating film), so that the wiring drawn out from the fourth galvanic type droplet sensor 104 can be made of the same material. Therefore, the fourth galvanic type droplet sensor 104 manufactured by this method has a preferable structure from the viewpoint of the above-mentioned electrical resistance. EXAMPLES

[0057] Example 1 In Example 1, a galvanic type liquid drop sensor 102 having a second structure was fabricated in which a first electrode 17 having a first thin wire 12 and a first current collector 15 was a first metal inclusion layer made of Al, a second electrode 18 having a second thin wire 13 and a second current collector 16 was a first metal inclusion layer 13a made of Al as a lower layer and a platinum inclusion layer 13b as an upper layer, and the first thin wires 12 and second thin wires 13 were arranged in a comb structure, and the characteristics of the sensor were investigated. However, it should be noted that the present invention is not limited to such a specific form, and the technical scope of the present invention is defined by the claims.

[0058] The detailed structure of the sample of Example 1 is shown below with reference to FIG. As the insulating substrate 11, a 6-inch Si wafer on which a silica film having a thickness of 100 nm was formed by sputtering was used. The first thin wires 12 were made of an aluminum (Al) layer formed by electron beam deposition. The thin wires had a width of 1 μm, a thickness of 150 nm, and a length of 1 mm, and there were 50 of them. The electrical resistivity of Al was 2.65×10 -8The electrical resistivity of platinum in Ωm is 1.06 x 10 -7 The film was deposited at room temperature and at a deposition rate of 0.1 to 0.2 nm per second. The second fine wires 13 were made of a laminated film in which the lower first metal-containing layer 13a was made of Al and the upper layer was made of platinum (Pt). The Al layer was formed by electron beam deposition under the same film-forming conditions as those for the first fine wires 12. The platinum layer was also formed by electron beam deposition at a substrate temperature of room temperature and a film-forming rate of 0.1 to 0.2 nm per second. The fine wires had a line width of 1 μm, a thickness of 150 nm, a length of 1 mm, and a total number of 50. The thickness of the first metal-containing layer 13a made of Al was 100 nm, and the thickness of the layer 13b made of platinum was 50 nm. Two types of spacings d1 and d2 between the first fine wire 12 and the second fine wire 13 were fabricated: one with a design value of 0.5 μm (d1=d2=0.5 μm) and one with a design value of 10 μm (d1=d2=10 μm).

[0059] The prototype galvanic droplet sensor 102 was placed in a box with a relative humidity of 100% at room temperature to measure the sensor response. Four measurements were performed on the sensor with a 0.5 μm gap between the first thin wire 12 and the second thin wire 13, and the minimum current value was 180 pA, the maximum was 330 pA, and the average value was 255 pA. The S / N ratios were all above 100. In addition, the sensitivity variation between the samples was small.

[0060] In order to verify the effect of the sample of Example 1, a comparative sample was prepared in accordance with the sample of Example 1 in all respects, except that the second thin wire was made of only a platinum layer. The sensor response of this comparative sample was measured, and the current value obtained for the thin wire spacing of 0.5 μm was 100 pA or less, and the maximum S / N ratio was approximately 10.

[0061] Example 2 In Example 2, as an example of forming a platinum-containing layer by electroplating, an example of forming a platinum layer on a first metal-containing layer by platinum (Pt) plating treatment is shown. Using a Si substrate on which a thermally oxidized film of 500 nm thickness was formed as an insulating substrate, a sample 301 was prepared in which a first thin wire 61 and a first current collector 62 made of aluminum (Al), and a second thin wire 63 and a second current collector 64 made of gold (Au) were formed thereon, as shown in Fig. 13. Here, the design values ​​of the line widths of both the first thin wire 61 and the second thin wire 63 were 2 µm, and the distance between the first thin wire 61 and the second thin wire 63 was 5 µm.

[0062] The results of Pt plating of the first fine wire 61 and the first current collector 62 of the sample 301, and the results of Pt plating of the second fine wire 63 and the second current collector 64 are shown in Figs. 14 and 15, respectively, along with the results of the sample without Pt plating. Figs. 14 and 15 are photographs of the upper surface of each sample observed by an optical microscope, with the left side of each figure showing a state before Pt plating and the right side showing a state after Pt plating. Since both photographs are observation images of the upper surface of the sample, the materials that constitute each fine wire and current collector that are exposed on the upper surface and sidewall are observed. In other words, the exposed materials are aluminum (71a, 72a, 81), gold (73, 83a, 84a), and platinum (71b, 72b, 83b, 84b). Therefore, in Figs. 14 and 15, the structures (71b, 72b, 83b, 84b) indicated with the symbol "b" are the thin wires and current collectors on which a platinum layer is formed by Pt plating.

[0063] Here, the Pt plating solution was K2PtCl4 (10 g / dm 3 ), boric acid (40g / dm 3 ) and sodium malonate (0.02 mol / dm 3 ) was used, and a current of 2.5 μA was applied for 120 seconds only to the wire and current collector to which Pt was to be deposited (to form a platinum layer), to perform Pt plating. The temperature was room temperature (25°C).

[0064] As a result, it was confirmed that Pt was selectively and symmetrically formed only on the fine wires and current collectors to which current was applied. This means that by forming a pattern of a first electrode having a first fine wire and a first current collector, and a pattern of a second electrode having a second fine wire and a second current collector (an electrode pattern consisting of a first electrode and a second electrode) all at once, i.e., with a single lithography step, and then applying a current to either the first electrode or the second electrode to perform electroplating, it is possible to form an electrode having fine wires with uniform spacing between the first and second fine wires. [Industrial Applicability]

[0065] According to the present invention, even when mass-produced, there is little manufacturing variation between elements, detection accuracy is high, and a high electrical output can be obtained. Furthermore, by incorporating this liquid drop sensor into a dew condensation detection device, it is possible to provide a dew condensation detection device with stable detection characteristics, which has little manufacturing variation between elements even when mass-produced, has high detection accuracy, and can obtain a high electrical output. Liquid droplet sensors and condensation detection devices have a wide range of applications, including environmental control, grasping and controlling indoor condensation and window fogging, monitoring corrosive environments such as bridges, and rain and fog detection sensors. The sensor of the present invention is small, highly accurate, highly sensitive, and has stable liquid droplet detection characteristics with little variation between lots, and is expected to be used in a variety of situations. [Explanation of symbols]

[0066] 1: First thin wire (metal A) 2: Second thin wire (metal B) 3: First current collector 4: Second current collector 5: First electrode 6: Second electrode 7: Insulating substrate 11: Insulating substrate 12: First thin line 13: Second thin line 13a: First metal-containing layer 13b: Platinum-containing layer 14: Oxide insulating film 15: First current collector 16: Second current collector 17: First electrode 18: Second electrode 21: Platinum inclusion layer pattern 21a: Platinum inclusion (Pt) layer pattern 22: Pattern of the first metal inclusion layer 22a: First metal inclusion (Al) layer 23: Resist pattern 23a: Resist pattern for the first electrode 23b: Resist pattern for second electrode 31: Pattern of first metal inclusion layer 31a: first metal inclusion (Al) layer 32: Platinum inclusion layer pattern 32a: Platinum inclusion layer pattern 33: Resist pattern 33a: Resist pattern for the first electrode 33b: Resist pattern for second electrode 41: Pattern of first metal inclusion layer 41a: first metal inclusion (Al) layer 42: Platinum-containing layer 43: Resist pattern 43a: Resist pattern 43b: Resist pattern 51: Pattern of first metal inclusion layer 51a: first metal inclusion (Al) layer 53: Resist pattern 53a: Resist pattern 53b: Resist pattern 54: Oxide insulating film pattern 54a: oxide insulating film 55: Platinum-containing layer 55a: Platinum-containing layer 56: Resist pattern 61: First wire (Al) 62: First current collector (Al) 63: Second wire (Au) 64: Second current collector (Au) 71a: Aluminum wire 71b: Aluminum wire with a Pt layer 72a: Current collector made of Al 72b: Al current collector with Pt layer formed 73: Au wire 81: Aluminum wire 83a: Au wire 83b: Au wire with a Pt layer 84a: Au current collector 84b: Au current collector with a Pt layer formed 101: Galvanic droplet sensor 111: Intermediate structure 102: Galvanic droplet sensor 112: Intermediate structure 103: Galvanic droplet sensor 113: Intermediate structure 104: Galvanic droplet sensor 114: Intermediate structure 201: Conventional galvanic droplet sensor 202: Electrode 202a: Electrode (thin wire and current collector) pattern 301: Sample

Claims

1. An insulating substrate; a first electrode having a first wire and a first current collector; a second electrode having a second wire and a second current collector; the first electrode and the second electrode are disposed on the insulating substrate, and the first thin wires and the second thin wires are alternately arranged in parallel on the insulating substrate; A droplet sensor for detecting a galvanic current flowing between the first thin wire and the second thin wire through a conductive droplet, the first thin wire and the first current collector are made of a first metal-containing layer having an electrical resistivity lower than that of platinum; the second thin wire is made of a composite film of the first metal-containing layer and a platinum-containing layer made of platinum or a platinum alloy, the second current collector includes the first metal-containing layer, At least a portion of the surface of the platinum-containing layer is exposed to the outside.

2. The liquid drop sensor according to claim 1 , wherein the second thin wire is made of a laminated film of the first metal-containing layer and the platinum-containing layer.

3. The liquid drop sensor according to claim 1 , wherein the second thin wire has a core portion made of the first metal-containing layer, and the platinum-containing layer is formed on at least a portion of a side wall portion of the core portion.

4. The liquid drop sensor according to claim 1 , wherein the second thin wire has a core portion made of the first metal-containing layer, and the platinum-containing layer is formed so as to cover the core portion.

5. The droplet sensor of claim 1 , wherein the spacing between the first thin line and the second thin line is constant.

6. 2. The droplet sensor of claim 1, wherein the first metal-containing layer is comprised of one or more metals selected from the group consisting of aluminum (Al), magnesium (Mg), zinc (Zn), iron (Fe), cobalt (Co), nickel (Ni), molybdenum (Mo), copper (Cu), silver (Ag), gold (Au), and tungsten (W), or an alloy containing one or more metals selected from the group.

7. The droplet sensor of claim 1 , wherein the platinum-containing layer has a thickness of 5 nm to 150 nm.

8. The droplet sensor according to claim 1 , wherein the distance between the first thin wire and the second thin wire is not less than 100 nm and not more than 100 μm.

9. The droplet sensor according to claim 8 , wherein the distance between the first thin wire and the second thin wire is not less than 100 nm and not more than 10 μm.

10. A dew condensation detection device equipped with the droplet sensor according to any one of claims 1 to 9.

11. Producing an intermediate structure having a pattern made of a platinum-containing layer made of platinum or a platinum alloy formed on an insulating substrate; forming a first metal-containing layer on the intermediate structure, the first metal-containing layer including a metal having an electrical resistivity lower than that of platinum; A method for manufacturing a droplet sensor or a dew detection device, comprising: forming, on the insulating substrate, a first electrode having a first thin wire made of the first metal inclusion layer and a first current collector made of the first metal inclusion layer, and a second electrode having a second thin wire made of a composite film of the platinum inclusion layer and the first metal inclusion layer and a second current collector including the first metal inclusion layer, by a single lithography process; and arranging the first thin wire and the second thin wire alternately on the insulating substrate.

12. forming a first metal-containing layer containing a metal having an electrical resistivity lower than that of platinum on an insulating substrate; Producing an intermediate structure having a pattern formed of a laminate in which a platinum-containing layer made of platinum or a platinum alloy is laminated on the first metal-containing layer; A method for manufacturing a droplet sensor or a dew detection device, comprising: forming, on the insulating substrate, a first electrode having a first thin wire made of the first metal inclusion layer and a first current collector made of the first metal inclusion layer, and a second electrode having a second thin wire made of a composite film of the platinum inclusion layer and the first metal inclusion layer and a second current collector including the first metal inclusion layer, by a single lithography process; and arranging the first thin wire and the second thin wire alternately on the insulating substrate.

13. A method for manufacturing a liquid droplet sensor or dew condensation detection device, comprising: a first electrode having a first thin wire made of a first metal-inclusive layer containing a metal having a smaller electrical resistivity than platinum and a first current collector made of the first metal-inclusive layer on an insulating substrate; and a second electrode having a second thin wire made of a composite film of the first metal-inclusive layer and a platinum-inclusive layer made of platinum or a platinum alloy and a second current collector including the first metal-inclusive layer, the first thin wire and the second thin wire being alternately arranged on the insulating substrate, the method comprising: forming a temporary electrode on the insulating substrate, the temporary electrode being made of the first electrode and the first metal-containing layer and having the same pattern as the second electrode or a pattern obtained by subjecting the second electrode to a ressence treatment, to prepare an intermediate structure; forming said second electrode by electroplating said platinum-containing layer on at least a surface of said fine wires of said temporary electrode of said intermediate structure.

14. The method of claim 13 , wherein the first electrode and the temporary electrode are formed in a single lift-off process.

15. 14. The method of claim 13, wherein the first electrode and the temporary electrode are formed by a single deposition, single lithography, and etching of the first metal inclusion on the insulating substrate.

16. A method for manufacturing a liquid droplet sensor or dew condensation detection device, comprising: a first electrode having a first thin wire made of a first metal-inclusive layer containing a metal having a smaller electrical resistivity than platinum and a first current collector made of the first metal-inclusive layer on an insulating substrate; and a second electrode having a second thin wire made of a composite film of the first metal-inclusive layer and a platinum-inclusive layer made of platinum or a platinum alloy and a second current collector including the first metal-inclusive layer, the first thin wire and the second thin wire being alternately arranged on the insulating substrate, the method comprising: forming the first metal-containing layer and an oxide insulating film in sequence on the insulating substrate; forming the first electrode and a temporary electrode having the same pattern as the second electrode or a pattern obtained by subjecting the second electrode to a lithography process on the insulating substrate to prepare an intermediate structure; depositing a platinum-containing material on the intermediate structure to form a platinum-containing material layer; performing anisotropic etching to form a platinum-containing layer only on the first thin wires and the sidewalls of the first current collector of the first electrode, and to form a second electrode having a platinum-containing layer only on the thin wires and the sidewalls of the current collector of the temporary electrode; forming a resist pattern formed by subjecting the pattern of the second electrode to a broadening process, and removing the platinum-containing layer in the portion not protected by the resist pattern by etching; removing the resist pattern.

17. The method for manufacturing a droplet sensor or a dew detection device according to claim 16, wherein the oxide insulating film is made of an oxide containing one or more substances selected from the group consisting of yttrium (Y), aluminum, silicon (Si), and cerium (Ce).

18. 14. The method of claim 13, wherein the first metal-containing layer is comprised of one or more metals selected from the group consisting of aluminum, magnesium, zinc, iron, cobalt, nickel, molybdenum, copper, silver, gold, and tungsten, or an alloy containing one or more metals selected from the group.

19. The method of claim 13, wherein the platinum-containing layer has a thickness of 5 nm to 150 nm.

20. The method for manufacturing a liquid drop sensor or a dew detection device according to claim 13, wherein the distance between the first thin wire and the second thin wire is 100 nm or more and 100 μm or less.

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