JP3453805B2 - Transparent conductive film - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to a transparent conductor having high performance.
Conductive film, particularly a liquid crystal display device, a plasma display transparent electrodes such as a light emitting element, a transparent electrode for a solar cell, the heat-ray reflection film or translucent <br/> useful magnetic Akirashirube film and said as a light heating element electrodes, about the transparent heating element which is transmissive Akirashirube <br/> conductive film.

[0002]

2. Description of the Related Art A transparent conductive film has both high transmittance and high conductivity in the visible light range, and is used for liquid crystal display devices, plasma light emitting devices,
EL (electroluminescence) transparent electrodes for display elements, such as elements, a solar cell, TFT, are utilized in a transparent electrode of various other light receiving elements. In addition, heat-reflecting films for automobiles and buildings, antistatic films for photomasks and other applications, various anti-fog windows such as freezer showcases, glass with melting ice and anti-fog function for automobile windshields (Electrically Heated) It is widely used as an electrode of a transparent heating element such as a window (hereinafter referred to as EHW). Further, it is also used as an electrode for an electrochromic device as a light control glass.

Conventionally, as the transparent conductive film was deposited on a glass substrate, tin oxide containing antimony or fluorine as a dopant (SnO ₂₎ film, an indium oxide containing tin as a dopant (In ₂ O ₃₎ film [following ITO film Call]
Are known zinc oxide film or the like, I TO film especially is widely used as a display element electrode mainly liquid crystal or the like from easily Der Rukoto low resistance <br/> is.

The conductive glass for reach indoors is formed by spraying a raw material liquid onto a substrate heated to several hundreds of degrees by a spraying method and causing a thermal decomposition reaction on the substrate surface to form a tin oxide film. Fluorine and antimony are often used as the dopant for imparting conductivity to the film. However , in the spray method, for a large substrate of about 1 m × 2 m used in reach indoors or EHW, a film having a uniform film quality and a uniform film is formed on the entire processing area. It is very difficult to produce thick and stable.

[0005] When the film thickness is not uniform, it occurs uneven reflectance and the reflection color, appearance, ing unsightly things. Further, if there is unevenness in the sheet resistance within the film plane, localized abnormal heating and when energized, to produce not heated portions, functionally or safety undesirable. In the spray method, during deposition, wraparound of film-to-back is likely to occur in the substrate, effectively difficult to mask the film with partially not want such peripheral portion and the electrode lead-out City area around Further, formed It is necessary to remove this by means such as etching or polishing after the film, which causes a problem that the process becomes complicated and the cost increases.

[0006] In addition to EHW is, Ru good to sputter ring method
Membrane system using a metal thin film having a film thickness several hundred Å is used.
The metal film has a high transmittance in the visible light region (12 to 24V), which has a high transmittance in the visible light region (400 to 700 nm) in order to secure the transparency required as a window material for vehicles.
The silver film is used because it is necessary to simultaneously satisfy the two points that the resistance is low because it can be driven by.

[0007] Usually, by increasing the transparency in the visible light region, <br/> one or, in order to prevent the a glaring appearance, viewed clamping both sides of the silver layer of a transparent dielectric film, a visible light region three-layer optical conditions are adjusted so that the reflectance is reduced in, or, I sandwiched by transparent dielectric film between both sides of the silver 2 layer 5 layer film structure, in use. However , a so-called electromigration phenomenon is known in the silver layer , and when current is continuously applied, silver atoms in the film are likely to cause grain boundaries / intragrain diffusion to generate hillocks and voids, which easily causes film breakage.

Also, the silver layer is originally durable against the environment.
Susceptible to chemical attack by moisture etc. so poor, a suitable membrane system has been desired in the silver layered membrane system from the viewpoint of reliability cash Waru transparent heating element.

[0009] to impart conductivity to the transparent substrate, as is given in wear transparent conductive film with a function as a transparent heating element, vapor fusing method or an ion plating method doped tin oxide film by a vapor deposition method Ya ITO film by an ion plating method or a sputtering ring <br/> method, doped zinc oxide film, there is.
However, in the tin oxide film, a so-called physical vapor deposition mentioned above, it is difficult to form a transparent conductive film of low resistance suitable for transparent heating element.

Further, it is easy to reduce the resistance of the ITO film.
, And the especially Ru can form a transparent conductive film by lever EHW and reach indoor uniform characteristics and thickness to the substrate having a large area suitable for the sputtering ring method, whereas, indium scarce
Such for a high price, the cost reduction of the product Ri naturally limits <br/> Oh, Applications: in a wide range of fields transparent heating element is hindered. In addition, the resource reserve of indium is particularly small compared to other elements, and since it is extracted as a by-product during refining of zinc ore, its production amount also depends on the zinc production amount. Have difficulty.

In the future, when the demand for a transparent conductive film including other uses such as display devices is increased, in the case of ITO, there is a problem in stable supply of indium as a raw material. On the other hand, in the transparent conductive film mainly composed of zinc oxide (ZnO), although low resistivity comparable aluminum used when 10 ^-4 Ω · cm stand and the ITO film is Ru obtained as a dopant, during deposition, high In order to avoid film damage due to energetic particle bombardment, it is necessary to arrange the substrate vertically with respect to the target, to apply an external magnetic field, or to perform heat treatment in a non-oxidizing atmosphere after film formation. there were.

[0012] or a difficult to produce with good reproducibility a low resistance film on the influence susceptibility to damage of the temporal change of the target properties, since the deposition rate of the low resistance film is extremely small and not more than about 5 Å / sec However , in industrial production, there is a fatal problem that the production speed is slow, and it has not been widely used.

Meanwhile, when applying the transparent conductive film electrode of such a display device, a transparent conductive film Keru Contact the device manufacturing process 3
It is exposed to heat treatment at a high temperature of about 00 to 500 ° C. In this case, it is also possible heat treatment in an inert gas, Ri Do requires facilities for maintaining the atmosphere, leading to increased cost. Where the industrial basis is a need for a heat treatment in the atmosphere. Also, when using a transparent conductive film to the heating element, a transparent conductive <br/> film is used in a state of being energized and heated at atmospheric Kikiri囲気.
Therefore, it is required that the change in resistance value due to heat generation is small, that is, heat resistance in an oxidizing atmosphere.

Further, even if the application of the transparent conductive film is heat-reflecting glass, the atmosphere in performing bending or tempering, 6
00 ℃ or more of Kotogaa because that is exposed to high-temperature heat treatment,
Similar heat resistance is required. As described above, when the transparent conductive film is applied to the industrial field, not only heat resistance in a non-oxidizing atmosphere but high heat resistance in the air is required.

[0015] Since it ITO film is not sufficient in this respect to have a heat resistance in the atmosphere, the ITO film is mainly used in a liquid crystal display device or the like. This is because only heat resistance at relatively low temperatures around 300 ° C. is required. On the other hand, the conventional ZnO film (without additives) is significantly inferior to the ITO film in heat resistance in an oxidizing atmosphere, and improvement in heat resistance in an oxidizing atmosphere has been a problem in practical use.

[0016] To improve the heat resistance of the Z nO film, conventionally, as shown in Japanese Patent Kokoku 3-72011, by the addition of periodic table group III impurity into ZnO, a stream of argon Rukoto to improve the heat resistance in a non-oxidizing atmosphere of a medium or vacuum secondary have been proposed.

[0017] However, if the addition of Group 3 impurities, the heat resistance of an inert gas atmosphere or reducing gas atmosphere is improved, at a high temperature heat treatment at 400 ° C. in an air atmosphere, the electrical resistance is more than 4 orders of magnitude It is also known that it cannot be used as a conductive film because it also increases (Technical Report of IEICE, CPM84-8,55 (1984)) . For lack of heat resistance in the atmosphere, ZnO film is delayed practical use as the transparent conductive film.

When the transparent conductive film is applied to the display element substrate, the transparent heating element, and the heat ray reflective glass as described above , the transparent conductive film loses its electrical and optical characteristics even after being heated to a high temperature in the atmosphere. We of Ikoto is important. And only, ZnO
The while the transparent conductive film composed mainly been expected as a low-cost materials that alternative to ITO film, extensive practical because the heat resistance is insufficient in an oxidizing atmosphere, and industrialization is delayed, heat in the air The improvement of the property has been regarded as the biggest problem of the ZnO film.

[0019]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art, obtains characteristics of low resistance and high transmittance even when manufactured at a high speed, and can be used in an atmospheric environment. not impaired electrical properties even at high-temperature heat treatment in an oxidizing atmosphere, high quality and low cost of the transparent conductive film, particularly a display element electrodes, architectural and transparent heating body for a motor vehicle, the heat ray reflective moth <br/> and to provide a useful transparent conductive film la scan.

[0020]

Means for Solving the Problems The present invention is a transparent conductive film mainly containing zinc oxide, gallium containing 0.5 to 12 atomic% with respect to zinc, X-rays of the transparent Akirashirubedenmaku in the diffraction pattern includes a diffraction peak due to (002) plane half width of the diffraction peak that provides der Ru permeable Akirashirubeden film than 0.6 degrees.

Further , the above-mentioned transparent conductive film is provided on the substrate.
To provide a transparent heating element.

The transparent conductive film of the present invention has a specific resistance of 10 ^-2 Ω.
· Cm or less, the film thickness is preferably in the 5 [mu] m or less in the range of 100 Å. If the film thickness is less than 100Å, a discontinuous film is likely to be formed, and there is a problem that the film is likely to be broken in coating the step portion. The thickness becomes longer deposition time becomes a 5 [mu] m greater, the cost is increased. On the other hand, the specific resistance is cut with satisfaction sheet resistance required as transparent heating element in the aforementioned thickness range to be equal to or less than 10 ^-2 Ω · cm.

The transparent conductive film (hereinafter, simply referred to as conductive layer) of the present invention is, Zn, but there is no problem even be included in not jeopardized the objectives of the present invention metal element other than Ga, as much as possible It is desirable to keep the amount small.

Further, the substrate to form a transparent conductive film of the present invention is glass, you can use a plastic or the like. Substrate as soda lime glass, if it contains alkali metal as its component, during film, the heat treatment or to prevent diffusion of alkali metals from the substrate definitive <br/> during long-term use to the conductive film For this purpose, an underlayer (alkaline barrier coat) containing a metal oxide such as Si, Al or Zr as a main component is provided between the substrate and the conductive film.
It is more preferable to form the chromatography vii).

The method for forming the conductive film of the present invention is not particularly limited, and a physical vapor deposition method such as a sputtering method or a vacuum vapor deposition method, or a chemical vapor deposition method such as a CVD method can be used, but it is lower.
A physical vapor deposition method is preferable because it provides good conductivity at a low substrate temperature. Above all, a sputtering method using a high-density plasma effective as a means for activating crystallinity,
Low-voltage sputtering method using a high magnetic field, or, more preferred for plasma activated vacuum deposition method to obtain a film having excellent heat resistance at low resistance. The target used in forming the transparent conductive film of the present invention by a sputtering method,
Not only sintering by adding a predetermined amount of gallium oxide in the zinc oxide, for example, by performing a process of holding more than 2 hours at 1400 ° C. or higher temperatures, <br/> charge fraction gallium oxide in the zinc oxide Ru used after subjected to processing to solid solution. Although in the embodiment shows a DC sputtering method as the sputtering method, even if a high-frequency sputtering method
Yes.

[0026] In the conductive film of the present invention, if that will be deposited by Ma Gunetoron DC Sputtering method, 40 Å
/ Because sometimes fast until seconds is film of high heat resistance at low resistance and the atmosphere is ensured, Ru can be deposited <br/> at a practical deposition rate.

[0027] In the transparent heating element of the present invention for the purpose of adjusting the appearance, one or more layers of the undercoat film between the transparent conductive film layer and the substrate, and / or, on the transparent conductive film layer
Provided one or more layers of the overcoat film, Ru can temper <br/> integer interference phenomenon and film transmission and reflection color tone or a visible light the reflectivity by utilizing absorption of light.

Examples of the one or more layers of film material of one or more layers or overcoat film of the undercoat layer, if example embodiment,
Silicon oxide, titanium oxide, zirconium oxide, tin oxide,
Tantalum oxide, chromium oxide, niobium oxide, boron oxide,
Indium oxide, such as one or more selected from the group consisting of oxidized zinc Contact and cerium oxide, or titanium, zirconium, hafnium, chromium, niobium metal, a nitride contact and the metal oxynitride of the metal One or more selected from the group consisting of

[0029] The above Symbol undercoat film and the overcoat film of, can have use also for purposes other than to adjust the optical properties. For example, Ru is used for the purpose of imparting durability to improve the handling properties of the previous coating products combined.
Further also the structure combined with other substrates or the multilayer structure, at the time of or attach the extraction portion of the electrode lead, if
Spacer ligament, in the multi-layer structure in that put in I was structure,
Or assemble other components, and is used for the purpose of adjusting the adhesion between. Also after forming the transparent heating element 1)
Laminated glass , 2) Bus bar and electrode formation , or 3)
Strengthening or bending of the glass substrate, or to impart heat resistance to withstand the step of requiring a high temperature such as, Ru used for purposes such and increasing the reliability for use at high temperatures.

The transparent heating element of the present invention can be used in the substrate alone transparency conductive film is formed, for example, in order to satisfy the safety standards for motor vehicles, strengthening treatment or a transparent substrate to be paired and also through the resin film can be or only with adhesion treatment resin film.

[0031] In the transparent heating element of the present invention, more than two portions, Rukoto have electrode extraction portion is provided for the energization
Is preferred. DC to the electrode extraction portion, alternating, or voltage DC and AC is superimposed is, or is applied by turning on and off in pulses in succession, the transparent heating element is heated by the Joule heat.

[0032] In the transparent heating element of the present invention, if necessary, the temperature control during electric heating, abnormal heating, or for the purpose of fault detection, such as cracks in the transparent heating element, may be provided detecting means.

FIG. 3 is a sectional view of the transparent heating element of the present invention, and FIG. 4 is a plan view of an EHW using the transparent conductive film of the present invention. In the figure, 1 is an overcoat layer, 2
Is a gallium-doped zinc oxide layer (the transparent conductive film of the present invention) ,
3 is an undercoat layer, 4 is a substrate, 5 is an upper bus bar,
6 is a transparent heating film coating portion, 7 is a lower side bus bar, and 8 is a substrate.

[0034]

The present inventors controlled the Ga concentration in the ZnO transparent conductive film to 0.5% or more and 12% or less in atomic ratio, and the half-width of the X-ray diffraction peak due to the (002) plane of the film was 0. by controlling the crystallinity of the film to be less than .6 degrees, 2
× 10 ^-4 Ω · cm and ITO film equivalent low resistivity say it was found to be obtained easily even when produced at high speed in a conventional substrate arrangement. Obtained conductive film is not conductive degradation after atmospheric heat treatment at 500 ° C. or higher, it had very excellent heat resistance in an oxidizing atmosphere.

The simple addition of Ga to ZnO has already been reported (J. Electrochem. Soc, 127, 1636 (198).
0), Jpn.J.Appl.Phys, 24, L781 (1985)). The former is Zn
Is an example of a film in which 1 atomic% of Ga is added, and the latter is an example of a film in which 1 to 4 atomic% of Ga is added to Zn ( by a sputtering method ) . However, in all cases, it is a report example in which the addition film and the non-addition film were compared and examined for electrical characteristics and optical characteristics , and no examination or description regarding heat resistance was found. Further, the conductivity of these films is inferior to that of the conventional Al-doped ZnO film.

The present invention is by controlling the crystallinity of the Ga concentration and the film contrast, it is significantly improved electrical characteristics
Allowed, and significantly improve the heat resistance in the atmosphere. That heat resistance do not express only comprises Ga, wherein the amount of a particular range of the Ga, and the value of the half-value width of the X-ray diffraction peaks are expressed only when it is below a certain value.

[0037] In general, the conductivity is increased because the electron density The addition of Group 3 element in ZnO is increased. It is considered that this is because a group 3 element, that is, a trivalent element substitutes at the divalent Zn position to form a shallow electric donor and generate a free electron. The increase in electron density by donors formed by generation of it and oxygen defects excess Zn is generated on interstitial sites simultaneously Ru can be explained. It is presumed that these are mixed in the actual film.
Since the ionic radii of the Group 3 element and Zn are not the same, it is conceivable that crystal lattice distortion will occur even when they are replaced.

It is considered that not all the Group 3 elements can be replaced, but some of them are precipitated between crystal lattices or at grain boundaries. This is because the amount of the Group 3 element detected in the film is larger by about one digit than the amount theoretically calculated from the electron density. Since these excess elements cause lattice distortion, it is expected that oxygen vacancies will be generated. Since defects such as oxygen vacancies are reduced by heat treatment in a high-temperature oxygen atmosphere, it is considered that the electron density generated by the vacancies is also reduced and the resistance is increased.

Actually, the ZnO film to which a group 3 element of Al, In, and B other than Ga is added has excellent heat resistance in a non-oxidizing atmosphere, but has extremely poor heat resistance in an oxidizing atmosphere such as the air. As a result of detailed examination of the relationship between the composition and crystallinity of the film and the thermal stability in the atmosphere by X-ray diffraction, the present inventors have found that the additive element is Ga, not simply the Group 3 element,
Moreover, it has been found that a film having high heat resistance in the atmosphere can be obtained only when the added amount is within a specific range and in addition, the half width of the X-ray diffraction peak of the film is less than a certain value.

The additive element Al, B, as the cause of heat resistance is different in the atmosphere in cases of In and Ga it is thought that the difference in ionic radius. That is, the ionic radii of Al and B are too small compared with Zn, respectively, and conversely In is too large. Since the ionic radius of Ga is the closest to that of Zn, it is considered that the lattice strain in the case of substitution is the smallest. In order to obtain a low resistance film, it is necessary to add a large amount of Al, B and In. In this case, it is considered that the strain increases and oxygen vacancies are generated. It is considered that this defect is easily reduced by high-temperature heat treatment in an oxidizing atmosphere, and at the same time, the number of free electrons generated by the defect is also reduced, so that the resistance is increased.

On the other hand, in the case of a Ga-added film, it is considered that even if a large amount of Ga is added, lattice strain and oxygen defects are less likely to occur, so that the heat resistance in an oxidizing atmosphere is also improved. It was found that the heat resistance strongly depends on the crystallinity of the film even when Ga is added, and when the half-width of the X-ray diffraction peak is a certain value or less, the heat resistance in an oxidizing atmosphere is remarkably high. It turned out to improve.

[0042]

EXAMPLES [Examples 1 to 6 and Comparative Examples 1 to 9] Examples of the present invention will be described in detail below with reference to the drawings. A glass substrate (5 cm x 5 c) on which a silica film with a thickness of about 500 Å is formed as an alkali barrier coat.
m × 1 mm), and various targets (Ga / Zn ratio of 0.3 to 0.3) were prepared by adding gallium oxide (Ga ₂ O ₃ ) into ZnO by direct current sputtering on a sufficiently washed silica-coated glass substrate. 15 atomic%) using Ar
ZnO having a film thickness of 3000Å to 10000Å in the atmosphere
A transparent conductive film was formed. The target used at this time is
This is a target in which gallium oxide is added to ZnO and then kept at a temperature of 1400 ° C. or higher for 2 hours or more to sufficiently dissolve gallium oxide in ZnO.

The vacuum apparatus was evacuated to 10 ^-6 Torr or less in advance, and then Ar gas was introduced at 0.01 Torr for sputtering. The substrate temperature was set in the range of room temperature to 300 ° C. The sputtering power was set to standard conditions to 50W but was changed from 400W Examples of high-speed film formation.

[0044] Further, ZnO target not doped with impurities, and in ZnO, aluminum oxide (Al ₂ O
₃ ), indium oxide (In ₂ O ₃ ) or boron oxide (B ₂ O ₃ ) added to various targets (Al / Zn)
A ratio of 4 atomic%, an In / Zn ratio of 5 atomic%, and a B / Zn ratio of 4.5 atomic%) were prepared by a sintering method, and a sample of a comparative example was prepared by using this.

The Ga content in the prepared film was 2 times that of the ZnO film.
After dissolving in specified hydrochloric acid solution, by ICP emission spectrometry
Measured . The Ga content is expressed in atomic% based on zinc.
The specific resistance was calculated from the sheet resistance obtained by the 4-probe method and the film thickness measured by a stylus type film thickness meter.

The X-ray diffraction analysis of the conductive film was performed by using a Kα ray of Cu and a rate meter using a proportional coefficient tube.
An example of measurement of the X-ray diffraction spectrum is shown in FIGS. This is an enlarged X-ray diffraction peak by the (002) plane in Example 3 and Comparative Example 4 of the ZnO film added with Ga as described later. As shown in the figure, on the (002) plane
At the position where the intensity is half the maximum intensity of the diffraction peak
The peak width (expressed in degrees) is called the half-value width (half-value width) (in the table )
"(002) plane peak half width"), but the half width in the case of Example 3 in FIG. 1 is 0.28 degrees, and Comparative Example 4 in FIG.
In this case, the full width at half maximum is 0.82 degrees.

The visible light transmittance measured by a spectrometer using an integrating sphere, was evaluated by the average value of the wavelength of 400 ~ 700 nm. These conductive films were subjected to a heat treatment test in air under the conditions shown in Table 1. Tables 2 and 3 show the results of measurement of changes in properties before and after heat treatment.

[0048]

[Table 1]

In Examples 1 to 6 shown in Table 2, the added amount of Ga is 0.5 to 12 atom %, and the X due to the (002) plane is
It is a heat resistance test result about the film | membrane in case the half value width of a line diffraction peak is 0.6 degrees or less. The X-ray diffraction pattern of the film of Example 3
The full width at half maximum of the peak was 0.28 degrees as shown in FIG.
These films are formed from 10 ⁻³ Ω · cm to 10 ⁻⁴ during film formation.
Shows high conductivity in the Ω · cm range, 500 ° C, 1
Even after the heat treatment in the atmosphere for 0 minutes, the conductivity does not decrease, and the conductivity is equal or, conversely, improved.

It was found that the visible light transmittance did not change and the film was stable against heat treatment in the atmosphere. Of particular note Ri example der fast film shown in Example 4, 40 Å
/ Even if it is deposited at a high speed of seconds, the half value width of 0.4
5 degrees and less film is also 2 × 10 ^-4 Ω · cm stand low resistance immediately after film formation, and was stable after the atmosphere heat treatment.

[0051]

[Table 2]

[0052] In contrast to the specific Comparative Examples 1 is not added ZnO, it was not observed at all heat resistance as known in the art. When Ga was added in an amount of 0.3 atomic%, the half-value width was good as shown in Comparative Example 2, but practically only insufficient heat resistance was obtained.

In Comparative Examples 3 and 4, the amount of Ga added is 0.5 atom%.
The above is an example in which the half width exceeds 0.6. In this case, substantially the atmospheric heat treatment resistance low after deposition
A significant increase in resistance occurred. Comparative Example 5 is an example in which the Ga addition amount is 15 atomic% , but an increase in resistance was observed due to the heat treatment in the atmosphere even though the half width was 0.6 or less. Comparative Example 1
In Nos. 5 to 5, the visible light transmittance also changes (increases) as the resistance changes. This is considered to reflect the effect of oxidation due to heat treatment in the atmosphere.

Al, In, B which are Group 3 elements other than Ga
When addedToComparisonExample 6~ 9. In either case
Even though the half-width is less than 0.6 degrees,
The heat resistance ofvisible lightTransmittanceofChangeAh
It was In the case of adding Al in Comparative Example 7, sputteringRing power
Increase the speedSuccessA membrane was tried, but the low speed shown in Comparative Example 6
SuccessIn case of membraneratioAllSuccessResistance after film increases and heat resistance
Also deteriorated. Thus, in the case of adding a Group 3 element other than Ga
Is X-ray diffractionpeakHeat resistance even when the half-width of is smallofImprovementIs
Nawon.

[0055]

[Table 3]

Example 7 Soda-lime silica glass (10 cm ×
A bus bar was formed on two opposite sides by screen printing and firing on a 10 cm × 2 mm thick substrate. The length of the bus bar was 8 cm, and the distance between the bus bars was 8 cm. This DC Sputtering method on a substrate, a zinc oxide transparent conductive film having a film thickness of 2000Å in an argon atmosphere at a pressure of 0.01Torr using a target in which the gallium oxide was added 7.5% in the zinc oxide (the onset
Bright transparent conductive film) . The target used at this time was 1400 after adding gallium oxide into ZnO.
Keep gallium oxide in Z
The target is a solid solution in nO. It should be noted in particular the substrate heating during the film formation was not I row.

The substrate on which the film was formed and another soda lime glass (10 cm ×
8.5 cm x 2 mm thick) and polyvinyl butyral (P
VB) After film Tsu line was I if treatment were used to measure the resistance between the bus bar electrode was 50.4Omu. A voltage of 22 V is applied between the electrodes to generate heat 15 per unit area.
00W / m ² at a current test was Tsu rows, even after 6 weeks, the resistance was constant showed no change with appearance.

[Comparative Example 10] A substrate having a bus bar similar to that of Example 7 was coated with metallic zinc and Ag.
Using an in-line type sputtering ring apparatus having a target, and a conductive film of high transmittance comprising three layers of ZnO / Ag / ZnO. ZnO layer as a target of metallic zinc, in a mixed gas atmosphere of argon and oxygen was deposited by reactive sputtering ring. The Ag layer was formed in a pure argon atmosphere with silver as a target. The film thickness of each layer was 450Å, 100Å, and 450Å in order from the substrate side. This laminated film had a terminal resistance of 7.1Ω measured between the bus bars.

In the same manner as in Example 7, the above-mentioned substrate and another soda lime glass (1
After the 0 cm × 8.5 cm × 2 mm thick) were Tsu row processing combined with PVB film, the applied voltage 8.2V operation test in calorific 1 500 W / m ² per unit area between the bus bar where was Tsu line, but the appearance did not change, the inter-terminal resistance has increased to 12.9Ω after a lapse of three weeks. Continue at the current test was Tsu row, exceeded the 100Ω to 6 weeks
It was

[0060] The same bus bar with the substrate and Comparative Example 11 Example 7, using an ITO target _{(In 2 O 3 -7.5wt% SnO} 2), thickness 2400 in-line type DC Sputtering device
An ITO layer of Å was formed. And argon as the sputtering gas, with 2% oxygen mixture gas added to argon amount, deposition chamber pressure of Sputtering <br/> in a mass flow meter was introduced so as to 0.01Torr . It should be noted in particular the substrate heating during the film formation was not I row. 30c
When the sheet resistance distribution in the m-square substrate surface was measured,
There was a variation of ± 30%. 22V between bus bar electrodes
It was found that when high voltage was applied, almost no heat was generated in the high resistance part, and there was a problem in the function as electrothermal glass.

Example 8 When a glass substrate with a transparent conductive film on which a gallium-doped zinc oxide film was formed was prepared in the same manner as in Example 7, a zirconium-silicon alloy (composition) provided in the same vacuum chamber was prepared. Is an atomic ratio of Zr / Si = 1/2), and a zirconia-silica film overcoat and undercoat are continuously formed on a glass substrate without breaking vacuum by reactive sputtering in argon-oxygen plasma. Formed. That is, from the glass substrate side, the zirconia-silica film having a film thickness of 300Å, the gallium-doped zinc oxide film having a film thickness of 1200Å, and the film film having a film thickness of 300Å
Zirconia-silica film.

A bus bar and an electrode lead-out portion were printed on this by a screen printing method, and after baking at 300 ° C.,
A lead wire was soldered to the electrode extraction portion. Then sealed with a sealant across the glass and space Sa of the same size
It was made into a multi-layer glass to obtain an electric heating glass. When the resistance between the bus bar electrodes was measured with a lead wire penetrating the sealant and taken out to the outside, it was 108Ω. Where a current test was Tsu line by applying a voltage 32.2V between the bus bars, also after 6 weeks, the resistance value, showed no change with appearance, was constant.

[0063]

As is clear from Table 2 , a film having a Ga concentration of 0.5 to 12 atomic% in atomic ratio has a Ga concentration of 10 ⁻³ Ω · cm to 10 ⁻⁴ Ω · cm. In addition to exhibiting high conductivity, the conductivity does not decrease even after heat treatment in the air, and the conductivity is equivalent or improved. The visible light transmittance is not changed and the film is stable in high temperature atmosphere.

On the other hand, as shown in Comparative Examples 1 and 2 in Table 3, the X-ray diffraction pattern was found in the films having a Ga content of 0.5 atomic% or less.
Even if the full width at half maximum of the peak is 0.6 degrees or less, the resistance is significantly increased after the heat treatment in the atmosphere. At the same time by heat treatment
The visible light transmittance is also changing. Also if Ga amount shown to <br/> so in Comparative Examples 3 and 4 are half width even 0.5 atomic% or more is 0.6 degrees greater than the resistance increases by the atmosphere heat treatment is observed.

[0065] more Ga concentration as are shown in Comparative Example 5 1
Similarly, for a film containing more than 2 atomic%, a large increase in resistance is observed after heat treatment. Shows the case the additive is a Group 3 element other than Ga in <br/> Comparative Example 6-9, in either case half width 0.6
Despite heat resistance in the atmosphere is less than degrees have such at all.

The transparent heating element using the gallium-doped zinc oxide layer according to the present invention as a heating element layer has a long-term reliability against electric current as compared with a film system for a transparent heating element using a thin metal layer such as a thin silver layer. It excels in stability and stability against attacks from the environment.

[0067] In addition, a large since the area substrate uniform film thickness and film quality distribution in film formation cut with film by a DC sputtering ring method capable, for example, a large area of more than 1m width is required, for example, the windshield of a motor vehicle It can be applied, such as the anti-fogging applications, and because kills with plural simultaneously film side by side substrate of a small size, is also excellent in production efficiency.

As shown above, the Ga concentration and the X-ray diffraction peak
By controlling the specific range of the half width of click, conductive, in addition to high transparency conductive film having a visible light transmittance can be realized, conductivity not crack at all damaged by the atmosphere heat treatment, oxidation resistance Ru can be obtained a transparent conductive film. Thus, the transparent conductive film of the present invention is high transparency, low resistance, the atmosphere heat resistance, since the e Bei each element of low cost, 1) various display devices, solar cells, membranes for the transparent electrode of the light reception element ,
2) construction and heat ray reflection film for an automobile, selectively permeable membrane or <br/> electromagnetic wave shielding film, 3) Auto antifogging glass, the freezing showcase or transparent heating body used for other architectural glass,
Film use, 4) photomasks and antistatic film construction such as, preferably der as such is, Ru can be applied to an extremely wide range of fields.

[Brief description of drawings]

FIG. 1 is an X of a (002) plane of a transparent conductive film of Example 3.
Graph showing half-width of line diffraction peak

FIG. 2 is an X of the (002) plane of the transparent conductive film of Comparative Example 4.
Graph showing half-width of line diffraction peak

FIG. 3 is a sectional configuration diagram of the transparent heating element of the present invention.

FIG. 4 is a plan view of an EHW using the transparent conductive film of the present invention.

[Explanation of symbols] 1: Overcoat layer 2: gallium-doped zinc oxide layer 3: Undercoat layer 4: substrate 5: Upper bus bar 6: Transparent heating film coating part 7: Lower bus bar 8: Substrate

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-141909 (JP, A) JP-A-1-133961 (JP, A) JP-A-62-12011 (JP, A) JP-A-62-1 154411 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01B 5/14 H05B 3/20 307

Claims (6)

(57) [Claims] 1. A transparent conductive film containing zinc oxide as a main component, which contains gallium in an amount of 0.5 to 12 atomic% with respect to zinc, and has an X-ray diffraction pattern of (00
2) A transparent conductive film having a diffraction peak due to a plane and having a half width of the diffraction peak of 0.6 degrees or less. 2. The specific resistance of the transparent conductive film is 10 ⁻² Ω · cm.
The transparent conductive film according to claim 1, having a film thickness of 100 Å or more and 5 μm or less. 3. A transparent heating element having the transparent conductive film according to claim 1 on a substrate. 4. The one or more undercoat film is provided between the substrate and the transparent conductive film, and / or the one or more overcoat film is provided on the transparent conductive film. The transparent heating element described in. 5. One or more layers before or under the undercoat film
The film material for one or more layers of the overcoat film is made of silicon oxide.
Element, titanium oxide, zirconium oxide, tin oxide, tan oxide
Tal, chromium oxide, niobium oxide, boron oxide, in oxide
Selected from the group consisting of dium, zinc oxide and cerium oxide
More than one type, or titanium, zirconium
Metals such as aluminum, hafnium, chromium, and niobium;
Selected from the group consisting of oxides and oxynitrides of said metals
The transparent heating element according to claim 4, which is one or more kinds. 6. A laminated structure or a multilayer structure having the transparent heating element according to claim 3, 4, or 5 .