JP6356520B2 - Substrate with transparent electrode and method for manufacturing the same - Google Patents

Description

The present invention relates to a substrate with a transparent electrode in which a transparent electrode thin film is formed on a transparent film substrate, and a method for producing the same.

  In a substrate with a transparent electrode used for a display device such as a touch panel or a display, a light-emitting device such as an LED, or a light-receiving device such as a solar cell, it is important to control electrical characteristics expressed as sheet resistance. In particular, the technology to heat-treat the transparent electrode thin film and reduce the resistance of the transparent electrode thin film by promoting crystallization is important. Therefore, many researches and developments so far have pursued crystallization promotion and achieved low resistivity. Met.

  As a general structure of a substrate with a transparent electrode, a structure in which a transparent electrode thin film is formed on a soft substrate such as a film is known, but an underlayer may be formed between the film and the transparent electrode thin film. is there. For example, Patent Document 1 describes a technique in which crystalline cerium oxide is formed as an underlayer, thereby reducing the resistance of the transparent electrode thin film. Patent Document 2 describes a technique for laminating a transparent electrode thin film to promote crystallization. Patent Document 3 and Patent Document 4 include a technique for controlling irregularities on the surface of a transparent conductive film by using zinc oxide to which various elements such as aluminum, gallium, and silicon are added as a base layer of a transparent electrode film. In addition, there is described a technique for suppressing outgas from a base material at the time of forming a transparent electrode and reducing resistance. However, in both Patent Documents 3 and 4, zinc oxide containing several percent of aluminum has been studied, but those to which silicon oxide has been added have not been substantially studied.

JP-A-7-178863 JP 2012-1114070 A JP 2000-108244 A JP 2007-327079 A

  By the way, recently, it has been found that electrical characteristics may change when a substrate with a transparent electrode is stored for a long period of time in a normal temperature and normal pressure environment. This is a phenomenon in which an amorphous transparent electrode thin film unintentionally transitions to a thermodynamically stable crystalline material in a normal temperature and normal pressure environment. Originally, it is known that amorphous changes to crystalline, but crystallization in such a room temperature and normal pressure environment causes stress of the substrate and the crystalline transparent electrode thin film in the subsequent device fabrication process. When the difference is large, particularly when the substrate is a soft material such as a film or plastic, problems such as causing peeling or deformation from the substrate are likely to occur. The above-mentioned “acceleration of crystallization during heat treatment” and “inhibition of crystallization at normal temperature and pressure” are considered to be mutually contradictory physical properties, but are simultaneously required for higher performance products.

  In addition to the above-described physical properties relating to crystallization, the transparent electrode-equipped substrate is required to have a high transmittance in the visible light region because it is placed on a display.

In response to such a problem, the techniques of Patent Documents 1 and 2 respond to the requirement of “acceleration of crystallization during heat treatment” among the above-mentioned physical properties, but “suppression of crystallization at normal temperature and pressure” And “high transparency and non-visibility” are not solved. Patent Document 3 is not a technique that assumes “crystallization suppression at room temperature and normal pressure” because the underlayer and the transparent electrode thin film are formed and crystallized in an environment of 180 ° C. Furthermore, with respect to Patent Document 4, since the refractive index of the dielectric layer is the same as that of the transparent electrode and the film thickness is as thick as 20 nm or more, the transmittance deteriorates due to an increase in the reflectance of the substrate with the transparent electrode. Therefore, the above three problems are not solved.

  Therefore, in view of the above problems, the present invention provides a substrate with a transparent electrode that simultaneously achieves crystallization promotion and room temperature crystallization suppression by heat treatment, as well as high light transmission.

  As a result of intensive studies, the inventors of the present invention have formed the above three physical properties by forming zinc oxide (SZO) to which silicon oxide is added as a base layer within a thickness of 8 nm or less when forming a transparent electrode thin film. I found that it can be solved at the same time. Furthermore, the present inventors have found that the above-described effect varies depending on the silicon oxide content of SZO, and have reached the present invention.

  That is, the substrate with a transparent electrode of the present invention is a substrate with a transparent electrode in which a transparent electrode thin film is formed on a film substrate, and an underlayer composed of SZO is formed between the film substrate and the transparent electrode thin film. ing.

  The transparent electrode thin film is preferably an oxide containing indium oxide as a main component, and the film thickness is preferably in the range of 15 to 30 nm from the viewpoint of low resistance and high light transmittance. Further, the film thickness of the SZO layer is 0 in terms of suppressing the diffusion of components that inhibit the crystallization of the transparent electrode thin film from the substrate and controlling the surface free energy when forming the transparent electrode thin film. It is preferably 5 to 8 nm.

The amount of silicon oxide added in the SZO is preferably 1 to 4% by weight, more preferably 2 to 4% by weight. When the added amount of silicon oxide is 1% by weight or less, since the refractive index values of the underlayer SZO and the transparent electrode thin film are close to each other, the reflectance at the interface between the transparent electrode thin film and the transparent adhesive increases, and transmission The rate decreases. On the other hand, if it is 5% by weight or more, crystallization of the transparent electrode thin film during heat treatment is promoted, but crystallization at normal temperature occurs.

  The covalent bond state between silicon and oxygen in SZO preferably has a smaller oxidation number. The bonding state of silicon oxide at that time can be analyzed by X-ray photoelectron spectroscopy. Usually, in the state where oxygen in silicon oxide is in a two-coordinate state, the binding energy of silicon is about 104 to 105 eV. On the other hand, the binding energy of silicon in the base SZO is 102 to 103 eV, which means that the silicon is in a monovalent or divalent positive charge state, and there is much silicon in which oxygen is not coordinated. Suggests it exists. Since silicon has a strong bond with oxygen, a sputtering thin film can easily become a supersaturated film of oxygen. However, the number of silicon oxidations is small by setting the film-forming conditions for producing SZO to the predetermined conditions described later. SZO can be manufactured. As a typical underlayer that promotes crystallization of a transparent electrode thin film during heat treatment, silicon oxide in which oxygen is coordinated to two by silicon is exemplified. Although silicon oxide has an effect of promoting crystallization, it cannot suppress room temperature crystallization. Although the principle that SZO promotes crystallization of the transparent electrode thin film during heat treatment and has the effect of suppressing room temperature crystallization is not clear, the oxidation state of silicon in SZO is controlled to have oxygen deficiency. It is speculated that this has an effect.

  The resistivity of the SZO is preferably 1 Ω · cm or more. If the resistivity of the SZO is within the above range, the function as a conductive electrode is not exhibited when the film thickness is 8 nm or less, and thus an electrical signal leaks through the SZO after the transparent electrode pattern is formed. Absent. Therefore, the film thickness range of the SZO is preferably between 0.5 and 8 nm, and more preferably between 1 and 5 nm.

  Moreover, the manufacturing method of the board | substrate with a transparent electrode of this invention forms both the said base layer and the said transparent electrode thin film by magnetron sputtering method, using oxygen gas as reactive gas. At that time, the underlayer is formed by sputtering with a direct current power source or a high frequency power source, and the discharge voltage at that time is preferably -100 to -350V. The underlayer and the transparent electrode thin film can be formed by a roll-to-roll method.

  According to the present invention, a transparent electrode is obtained by using SZO, which is zinc oxide to which a small amount of silicon oxide is added as an underlayer, and controlling the content of silicon oxide in the SZO and the oxidation state of silicon in the SZO film. Controls the crystallinity and electrical properties of the thin film, promotes crystallization after heat treatment, and suppresses crystallization in a room temperature environment. In addition, it can achieve high light transmission, and has high quality and reliability. An electrode-attached substrate can be provided.

1 is a schematic cross-sectional view of a substrate with a transparent electrode in Example 1. FIG. FIG. 3 is a schematic cross-sectional view of a substrate with a transparent electrode when a transparent electrode thin film is formed in a plurality of times with the structure of Example 1. In the structure of Example 1, it is a typical sectional view of a substrate with a transparent electrode when a coating layer is formed under an underlayer.

[Configuration of substrate with transparent electrode]
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a substrate with a transparent electrode in which an SZO 200 as an underlayer is formed on a transparent film substrate 100 and a transparent electrode thin film 300 is further formed thereon. As shown in FIG. 2, the transparent electrode thin film 300 may be formed of a plurality of layers such as a layer 301 and a layer 302. In FIG. 3, a coating layer 400 is provided between the transparent film substrate 100 and the foundation layer 200. The coating layer 400 is provided for the purpose of protecting the transparent film substrate 100, suppressing the diffusion of low molecular weight components contained in the transparent film substrate 100, and adjusting the optical film thickness. In FIG. 3, the coating layer 400 is formed only on one side of the transparent film substrate 100, but may be formed on both sides.

  The transparent film constituting the transparent film substrate 100 is preferably transparent and colorless at least in the visible light region.

  The SZO 200 as an underlayer is an inorganic thin film containing zinc oxide as a main component and containing 1 to 4% by weight of silicon oxide, more preferably 2 to 4%. The film thickness of SZO200 is preferably 0.5 to 8 nm, and more preferably 1 to 5 nm. The SZO 200 includes a transparent film from plasma when the transparent electrode thin film 300 is formed by sputtering, and the diffusion suppression of carbon atoms and nitrogen atoms from the transparent film substrate 100 that functions as a crystallization inhibiting component of the transparent electrode thin film 300. There are roles such as protection of the substrate 100 and control of surface free energy when the transparent electrode thin film 300 is formed, and the above film thickness range is preferable in order to satisfy these roles.

The zinc oxide constituting the SZO 200 controls not only the surface free energy of the underlayer 200 to an optimal value for forming the transparent electrode thin film 300, but also physical factors such as plasma as well as chemical factors such as water vapor. On the other hand, it is preferable from the viewpoint of barrier properties for protecting the film and from not containing carbon or nitrogen atoms that may inhibit crystallization of the transparent electrode thin film 300. Furthermore, it is possible to suppress crystallization at room temperature as compared with known underlayer materials such as a material composed only of silicon oxide. This is presumably because the oxidation state of silicon in SZO 200 affects the crystallization of the transparent electrode thin film.

  The formation method of SZO200 is preferably a sputtering method from the viewpoint of productivity. As the sputtering method, a magnetron sputtering method is particularly preferable. The strength of the magnet at the time of magnetron sputtering is preferably 700 to 1300 gauss, thereby suppressing a reduction in the utilization efficiency of the sputtering target due to extreme erosion and enabling formation of a good quality underlayer 200. This is because the discharge voltage can be lowered by increasing the magnetic field strength, and there is an advantage that the formation of the underlayer SZO 200 can be performed on the transparent film substrate 100 with low damage. The power source used for sputtering is not limited, and a DC power source or an AC power source can be selected according to the target material. Although the discharge voltage depends on the type of the device and the power source, it is preferably about −100 to −350 V, more preferably about −180 to −300 V in order to form a good underlayer 200.

  Since the SZO 200 is formed on a layer containing an organic compound such as the transparent film substrate 100 or the coating layer 400, it is preferable that the SZO 200 be formed as low damage as possible on the substrate. In addition to the low-voltage film formation using the high magnetic field cathode as described above, such low damage film formation includes techniques such as not increasing the input power density and increasing the film formation pressure in the film formation chamber. .

  The SZO 200 is formed by introducing an inert gas and a reactive gas into the film forming chamber at a predetermined pressure. The amount of oxygen introduced is preferably 3% by volume (vol.%) Or less with respect to the inert gas. The amount of oxygen introduced is 3 vol. If it exceeds 50%, there is damage to the thin film due to oxygen plasma generated by oxygen, which is not preferable because the moisture and heat resistance of the substrate with a transparent electrode is lowered.

The transparent electrode thin film 300 preferably contains 87.5 wt% to 99.0 wt% indium oxide, and more preferably 90 wt% to 95 wt%. The crystalline transparent electrode thin film contains a doped impurity for imparting conductivity by giving a carrier density in the film. As such a doping impurity, tin oxide, zinc oxide, titanium oxide or tungsten oxide is preferable. The transparent electrode thin film when the doped impurity is tin oxide is indium tin oxide (ITO), and the transparent electrode thin film when the doped impurity is zinc oxide is indium oxide zinc (IZO). The content of the doped impurity in the transparent electrode thin film is preferably 4.5% by weight to 12.5% by weight, and more preferably 5% by weight to 10% by weight. From the viewpoint of making the transparent electrode thin film 300 have low resistance and high light transmittance, the film thickness of the transparent electrode thin film 300 is preferably 15 nm to 30 nm, more preferably 17 nm to 27 nm, and even more preferably 20 nm to 25 nm.

  The total thickness of the transparent electrode thin film and the underlayer is preferably less than 50 nm, more preferably 23 to 38 nm, and most preferably 20 to 35 nm.

  The transparent electrode thin film 300 has a crystallinity of 80% or more after annealing and crystallization, and more preferably 90% or more. When the crystallinity is in the above range, light absorption by the transparent electrode thin film can be reduced, and a change in resistance value due to an environmental change or the like is suppressed. The crystallinity is obtained from the ratio of the area occupied by the crystal grains in the observation field during microscopic observation.

The transparent electrode thin film 300 preferably has a resistivity of 8.0 × 10 ⁻⁴ Ωcm or less. Moreover, the surface resistance of the crystalline transparent electrode thin film 300 is preferably 170Ω / □ or less, and more preferably 150Ω / □ or less. If the transparent electrode thin film has a low resistance, it can contribute to improving the response speed of the capacitive touch panel, improving the uniformity of in-plane luminance of organic EL lighting, and reducing the power consumption of various optical devices.

The carrier density of the transparent electrode thin film 300 is preferably 2 × 10 ²⁰ cm ^{−3 to} 9 × 10 ²⁰ cm ⁻³ , and more preferably 3 × 10 ²⁰ cm ^{−3 to} 6 × 10 ²⁰ cm ^−3. preferable. If the carrier density is within the above range, the resistance of the transparent electrode thin film 300 can be reduced.

  The method for forming the transparent electrode thin film 300 is preferably a sputtering method from the viewpoint of productivity, and among these, a magnetron sputtering method is preferable. The formation of the transparent electrode thin film 300 by sputtering may form the entire thickness of a desired film thickness by a single film formation, but the production process speed and the transparent film base material 100 are better formed by a plurality of times of lamination. From the viewpoint of the heat history. When film forming is performed a plurality of times, crystallinity can be controlled by the following two methods. One is a method of changing the film forming conditions for each layer using a target having the same composition, and the other is a method of stacking using a target having a different composition. As the former method, the amount of oxygen in the first layer is made smaller than the amount of oxygen introduced when forming a normal transparent conductive indium oxide (the optimum amount of oxygen with the lowest resistivity), so that the SZO 200 and the transparent layer are transparent. The number of crystal nuclei formed in the vicinity of the interface of the electrode thin film 300 can be reduced, and the crystallinity of the transparent electrode thin film can be controlled in a direction in which crystallization is difficult. Moreover, since the transparent electrode thin film with little damage by oxygen plasma is formed by the amount of oxygen in the first layer being small, reliability such as resistance to moist heat is also improved. The latter method is a method in which the material constituting the transparent electrode thin film and the composition / concentration of the dopant are sequentially changed. In the case of this method, from the viewpoint of smooth electron transport in the transparent electrode thin film, it is preferable that the dopant materials are the same, and the change in concentration preferably occurs only in the film thickness direction.

[Method for producing substrate with transparent electrode]
Hereinafter, a preferred embodiment of the present invention will be further described along with a method for producing a substrate with a transparent electrode. In the production method of the present invention, a transparent film substrate 100 having a transparent dielectric layer such as a hard coat on a transparent film is used (substrate preparation step). The transparent electrode thin film is formed by a sputtering method (film forming process), and then the transparent electrode thin film is crystallized (crystallization process). Generally, in order to crystallize an amorphous transparent electrode thin film containing indium oxide as a main component, a heat treatment at about 150 ° C. is performed.

(Base material preparation process)
The material of the transparent film constituting the transparent film substrate 100 is not particularly limited as long as it is colorless and transparent at least in the visible light region and has heat resistance at the transparent electrode thin film forming temperature. Examples of the transparent film material include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), cycloolefin resins, polycarbonate resins, polyimide resins, and cellulose resins. Can be mentioned. Of these, polyester resins are preferable, and polyethylene terephthalate is particularly preferably used.

Although the thickness of the transparent film base material 100 is not specifically limited, 10 micrometers-400 micrometers are preferable and 20 micrometers-200 micrometers are more preferable. If the thickness is within the above range, the transparent film substrate 100 can have durability and appropriate flexibility, so that each transparent dielectric layer and transparent electrode thin film are produced on the roll film by a roll-to-roll method. It is possible to form a film with high performance. As the transparent film base material 100, a film in which mechanical properties such as Young's modulus and heat resistance are improved by orienting molecules by biaxial stretching is preferably used.

  In general, a stretched film has a property of being thermally contracted when heated because strain caused by stretching remains in a molecular chain. In order to reduce such heat shrinkage, stress is relaxed by adjusting the stretching conditions and heating after stretching, the thermal shrinkage rate is reduced to about 0.2% or less, and the heat shrink start temperature is increased. Biaxially stretched films (low heat shrink films) are known. From the viewpoint of suppressing problems due to thermal shrinkage of the base material in the manufacturing process of the substrate with transparent electrodes, it has also been proposed to use such a low heat shrink film as the base material.

  A functional layer 400 such as a hard coat layer may be formed on one side or both sides of the transparent film substrate 100. In order to give the transparent film base material appropriate durability and flexibility, the thickness of the hard coat layer is preferably 1 to 10 μm, and more preferably 1.5 to 8 μm. The material of the hard coat layer is not particularly limited, and a material obtained by applying and curing a urethane resin, an acrylic resin, a silicone resin, or the like can be appropriately used.

(Film forming process)
On the transparent film base material 100, SZO200 as a base layer and the transparent electrode thin film 300 are sequentially formed by a sputtering method.

  Sputtering is performed while a carrier gas containing an inert gas such as argon or nitrogen and an oxygen gas is introduced into the film forming chamber. The introduced gas is preferably a mixed gas of argon and oxygen. Argon and oxygen may be prepared in advance with a gas having a predetermined mixing ratio, or each gas may be mixed after the flow rate is controlled by a flow rate control device (mass flow controller). The mixed gas may contain other gases as long as the function of the present invention is not impaired.

  In the present invention, the pressure in the deposition chamber during SZO200 deposition is preferably 0.1 Pa to 1.0 Pa, and more preferably 0.3 Pa to 0.8 Pa. By increasing the pressure, the oxidation state of silicon near the interface between the SZO 200 and the transparent electrode thin film 300 increases, and the crystallization of the transparent electrode thin film formed thereon is suppressed while suppressing the crystallization of the transparent electrode thin film at room temperature. There is a tendency to be promoted. On the other hand, when the pressure is too high, the film forming speed is reduced.

In the present invention, the oxygen partial pressure during formation of the underlayer SZO200 is preferably 0 Pa to 9 × 10 ⁻³ Pa. Here, the oxygen partial pressure was calculated by the following equation.
Oxygen partial pressure = total pressure × oxygen gas introduction amount / (oxygen gas introduction amount + argon gas introduction amount)
If the oxygen partial pressure is increased too much, oxygen deficiency of silicon in SZO200 increases, and room temperature crystallization is promoted, or SZO200 is damaged by oxygen plasma generated by excess oxygen, and reliability such as heat and moisture resistance is improved. It will decline.

  The substrate temperature at the time of forming the underlayer SZO200 may be in a range in which the transparent film substrate has heat resistance, and is preferably −20 ° C. to 90 ° C. There is a tendency that the oxidation state of silicon near the interface between the SZO 200 and the transparent electrode thin film 300 is increased, and the crystallization of the transparent electrode thin film formed thereon is promoted while the room temperature crystallization of the transparent electrode thin film 300 is suppressed. . Moreover, by making a substrate temperature into the said range, while embrittlement of a transparent film base material is suppressed, a film base material does not produce a big dimensional change in a film forming process.

  In the present invention, as the transparent electrode thin film 300, the pressure in the film forming chamber when forming 10% tin ITO (indium-tin composite oxide) is preferably 0.1 Pa to 1.0 Pa, preferably 0.15 Pa to 0.15 Pa. 0.8 Pa is more preferable. By increasing the pressure in the film forming chamber, the discharge voltage is lowered by lowering the impedance of the discharge, and it becomes possible to form a transparent electrode thin film with lower damage. When the gas component at is high, the mean free path of the sputtered particles becomes small, leading to a decrease in the film forming speed.

In this invention, it is preferable that the oxygen partial pressure at the time of transparent electrode thin film 300 formation is 1 * 10 < ^-3 > Pa-1 * 10 < ^-2 > Pa, 3.0 * 10 < ^-3 > Pa ^- 8.0 * 10 ^<-2 >. More preferably, it is Pa. The oxygen partial pressure range is a value lower than the oxygen partial pressure in general sputtering film formation. That is, in the present invention, the transparent electrode thin film is formed with a small amount of oxygen supply. Therefore, it is considered that many oxygen vacancies exist in the amorphous film after film formation.

The substrate temperature at the time of forming the transparent electrode thin film 300 may be a range in which the transparent film substrate has heat resistance, and is preferably 60 ° C. or less. The substrate temperature is more preferably −20 ° C. to 40 ° C. By setting the substrate temperature to 60 ° C. or lower, moisture from the transparent film substrate and volatilization of organic substances (for example, oligomer components) are less likely to occur, crystallization of indium oxide is likely to occur, and an amorphous film is formed. An increase in resistivity of the crystalline transparent electrode thin film after being crystallized can be suppressed. In addition, by setting the substrate temperature within the above range, a decrease in the transmittance of the transparent electrode thin film and embrittlement of the transparent film base material are suppressed, and the film base material undergoes a significant dimensional change in the film forming process. There is no.

In the present invention, it is preferable that film formation is performed by a roll-to-roll method using a winding type sputtering apparatus. By forming the film by a roll-to-roll method, a roll-shaped wound body of a long sheet of a transparent film substrate on which an amorphous transparent electrode thin film is formed is obtained. Formation of the dielectric underlayer 200 and the transparent electrode thin film 300 on the transparent film substrate 100 may be continuously formed using a winding type sputtering apparatus.

The atmosphere in the vacuum apparatus at the time of sputtering film formation is such that the partial pressure of the component of m (mass) / z (charge) = 18 when measured with a quadrupole mass spectrometer is 2.8 × 10 −4 Pa or less. And the partial pressure of the component of m / z = 28 is preferably 7.0 × 10 −4 Pa or less. The component of m / z = 18 is mainly water, and the component of m / z = 28 is mainly a component derived from organic matter or nitrogen. When these partial pressures are within the above range, mixing of the crystallization inhibitor can be suppressed in the transparent electrode thin film . In order to make such an atmosphere, a method of degassing the film roll in the sputtering apparatus or before the apparatus is generally used. For example, moisture can be removed by heating. In addition to these, by forming the dielectric underlayer of the present invention, it is possible to suppress the diffusion of the components from the film during the formation of the transparent electrode, and to suppress the diffusion after the film formation.

(Crystallization process)
The substrate on which the underlayer and the amorphous transparent electrode thin film are formed is subjected to a crystallization process. In the crystallization step, the substrate is heated to 120 to 170 ° C.

  In order to sufficiently incorporate oxygen into the film and shorten the crystallization time, the crystallization is preferably performed in an oxygen-containing atmosphere such as the air. Crystallization proceeds even in a vacuum or in an inert gas atmosphere, but in a low oxygen concentration atmosphere, crystallization tends to take a longer time than in an oxygen atmosphere.

  When a roll-shaped wound body of a long sheet is subjected to a crystallization process, crystallization may be performed with the wound body as it is, and crystallization is performed while the film is conveyed by a roll-to-roll. Alternatively, the film may be cut into a predetermined size and crystallized.

When crystallization is performed in the form of a wound body, the substrate after forming the transparent electrode thin film may be placed in a room temperature / normal pressure environment as it is, or may be cured (standing) in a heating chamber or the like. When crystallization is performed by roll-to-roll, the substrate is introduced into a heating furnace while being conveyed and heated, and then wound again in a roll shape. Even when crystallization is performed at room temperature, a roll-to-roll method may be employed for the purpose of promoting crystallization by bringing the transparent electrode thin film into contact with oxygen.

[Use of substrates with transparent electrodes]
The board | substrate with a transparent electrode of this invention can be used as transparent electrodes, such as a display, a light emitting element, a photoelectric conversion element, and is used suitably as a transparent electrode for touchscreens. Especially, since a transparent electrode thin film is low resistance, it is preferably used for a capacitive touch panel.

  In the formation of the touch panel, a conductive ink or paste is applied on a substrate with a transparent electrode and is heat-treated to form a collector electrode as a wiring for a routing circuit. The method for the heat treatment is not particularly limited, and examples thereof include a heating method using an oven or an IR heater. The temperature and time of the heat treatment are appropriately set in consideration of the temperature and time at which the conductive paste adheres to the transparent electrode. For example, in the case of heating with an oven, examples include 30 to 60 minutes at 120 to 150 ° C., and in the case of heating by an IR heater, examples include 150 minutes at 150 ° C. In addition, the formation method of the circuit wiring is not limited to the above, and may be formed by a dry coating method. In addition, since the wiring for the routing circuit is formed by photolithography, the wiring can be thinned.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

(Electrical properties, optical properties)
As the film thicknesses of SZO 200 and the transparent electrode thin film 300 as the underlayer, values obtained by observation with a transmission electron microscope (TEM) of the cross section of the substrate with the transparent electrode were used. The surface resistance of the transparent electrode layer was measured by four-probe pressure measurement using a low resistivity meter Loresta GP (MCP-T710, manufactured by Mitsubishi Chemical Corporation). The total light transmittance of the substrate with a transparent electrode was a Nippon Denshoku Industries Co., Ltd. haze meter NDH-5000.

(Measurement of crystallization time)
Parallel electrodes were attached to two opposite sides of the transparent electrode thin film 300 side surface of the substrate with a transparent electrode before heating. At this time, the sheet resistance can be read from the resistance value by equalizing the distance between the electrodes and the length of the side to which the electrodes are attached. With the parallel electrodes attached, the transparent conductive film was put into an oven at 140 ° C., and the change in sheet resistance with time was measured. The time when the difference between the sheet resistance and the resistance value (resistance value at the time of complete crystallization) when resistance does not change with time was within 2Ω / □ was defined as the crystallization completion time.

[Example 1]
(SZO200 film formation)
Using an SZO target in which 2% by weight of silicon oxide is added to zinc oxide, while introducing argon gas into the apparatus, the pressure inside the film forming chamber is 0.3 Pa, the substrate temperature is 20 ° C., and the power density is 0 on the transparent film substrate 100. The film was formed under the condition of 6 W / cm ² . The film thickness of the formed SZO was 3 nm, and the resistivity was 7 Ω · cm. Details of other film forming conditions are shown in Table 1.

(Formation of transparent electrode thin film layer 300)
While introducing a mixed gas of oxygen and argon into the apparatus continuously, oxygen partial pressure 4.0 × 10 ⁻³ Pa, film forming chamber pressure 0.3 Pa, substrate temperature 20 ° C., power density 3.0 W / cm It carried out on condition of ² . The film thickness was 20 nm.

(Crystallization (heat treatment))
This substrate with a transparent electrode was heat-treated at 140 ° C. for 1 hour. Microscopic observation confirmed almost complete crystallization (100% crystallinity).

(Evaluation of underlayer)
About SZO200, using the board | substrate with a transparent electrode which formed the transparent electrode thin film 300 on it, from the transparent electrode thin film 300 side, the interface (SZO surface) of the transparent electrode thin film 300 and SZO200 by X-ray photoelectron spectroscopy, and SZO200 When the binding energy of silicon in the film was measured, the surface showed 102.9 eV and the film showed 102.7 eV.

(Evaluation of room temperature crystallization)
The film formed was left in an environment of 25 ° C. and 50% RH for 90 days and evaluated by measuring the sheet resistance at that time. It is assumed that the sheet resistance is lowered and the crystallization is progressing.

[Example 2]
In the film formation of SZO200, the same conditions as in Example 1 except that film formation was performed at an oxygen partial pressure of 5.0 × 10 ⁻³ Pa while introducing a mixed gas in which oxygen was added in addition to argon. Example 2 was produced. As the oxygen partial pressure, a value calculated from the following equation was used.

Oxygen partial pressure = total pressure x (oxygen gas introduction amount / argon gas introduction amount + oxygen gas introduction amount)
The formed SZO had a thickness of 3 nm and a resistivity of 40 Ω · cm.

[Example 3]
Example 3 was produced under the same conditions as Example 1 except that the SZO 200 film was formed by doubling the argon flow rate and setting the film forming chamber pressure to 0.60 Pa. The formed SZO had a thickness of 3 nm and a resistivity of 4 Ω · cm.

[Example 4]
Example 4 was produced under the same conditions as in Example 1 except that the film formation of SZO200 was performed with the substrate temperature set at 90 ° C. The formed SZO had a thickness of 3 nm and a resistivity of 4 Ω · cm.

[Example 5]
Example 4 was produced under the same conditions as Example 1 except that the film thickness of SZO200 was set to 0.5 nm. The film thickness of the formed SZO was 1 nm or less, and the resistivity was 40 Ω · cm or more.

[Comparative Example 1]
Comparative Example 1 was produced under the same conditions as Example 1 except that the transparent electrode thin film 300 was formed directly on the transparent film substrate 100 without forming the SZO 200.

[Comparative Example 2]
Instead of SZO200, the comparative example 2 was produced on the same conditions as Example 1 except having formed the transparent electrode thin film 300 3nm on the transparent film base material 100, and having formed the transparent electrode thin film 300 on it. The formed transparent electrode thin film 300 had a total film thickness of 23 nm and a resistivity of 2 × 10 ⁻⁴ Ω · cm.

[Comparative Example 3]
Instead of SZO200, a single crystal of silicon was used as a target, and while introducing a mixed gas of argon and oxygen into the apparatus, oxygen partial pressure 2.0 × 10 ⁻² Pa, power density 3.0 W / cm ² , film Comparative Example 3 was produced under the same conditions as in Example 1 except that the silicon oxide film was formed with a thickness of 3 nm. The film thickness of the formed silicon oxide was 3 nm, and the resistivity was 4 × 10 ⁴ Ω · cm.

[Comparative Example 4]
Comparative Example 4 was produced under the same conditions as in Example 1 except that an SZO target in which 5% by weight of silicon oxide was added to zinc oxide was used in the formation of SZO200. The formed SZO had a thickness of 3 nm and a resistivity of 20 Ω · cm.

  Table 1 shows the structure of each layer, results, and characteristics at each level.

  From the results shown in Table 1, the substrate with transparent electrodes exhibiting low resistance after heat treatment, suppression of crystallization at room temperature, and high transmittance can be obtained by using SZO in which 2% by weight of silicon oxide is added to zinc oxide for the underlayer. It was found that it can be produced. On the other hand, as in Comparative Example 4, when SZO to which the addition amount of silicon oxide was added up to 5% by weight was used as the underlayer, room temperature crystallization could not be suppressed. Although this cause is not certain, it is presumed that the content of silicon oxide has an influence on the crystallization of the transparent electrode thin film, and the crystallization is promoted by the high content of silicon. Therefore, the amount of silicon oxide added should be 1 to 4% by weight, more preferably 2 to 4% by weight.

  The larger the binding energy of silicon on the surface of the SZO 200 in Example 1, Example 3, and Example 4, the less time is required for crystallization during heat treatment. This is considered to be due to the fact that the oxidation state of silicon on the surface of the underlayer SZO 200 is large. In Examples 1 to 4, the time required for crystallization during the heat treatment at 140 ° C. is shorter than that in Example 5. This is considered to be due to the fact that the film thickness of SZO 200 is large and the effect of promoting crystallization during heat treatment is large. The reason why the transmittance is improved by inserting the SZO 200 is that the refractive index of the SZO 200 is lower than that of the transparent electrode thin film 300, thereby reducing the reflectance of the entire substrate with the transparent electrode.

  In the example, although the sheet resistance after the heat treatment was lowered, no crystallization occurred at room temperature, and a substrate with a transparent electrode having a high transmittance could be produced. On the other hand, in the comparative example, the sheet resistance after the heat treatment decreases, but room temperature crystallization cannot be suppressed, or the room temperature does not crystallize but the sheet resistance does not decrease even by heat treatment, and the transmittance is low depending on the type of the underlayer. As a result.

100: Transparent film substrate 200: Underlayer SZO
300: Transparent electrode thin films 301, 302,...: Layer 400 constituting transparent electrode thin film: Coating layer

Claims (4)

In a substrate with a transparent electrode in which a base layer and a transparent electrode thin film are sequentially formed on a transparent film substrate,
The transparent electrode thin film is indium tin oxide having a tin content of 4.5 wt% to 12.5 wt%,
A substrate with a transparent electrode, characterized in that the underlayer contains zinc oxide as a main component, has a film thickness of 0.5 to 8 nm, and contains 1 to 4% by weight of silicon oxide.   2. The substrate with a transparent electrode according to claim 1, wherein the underlayer has a peak position of silicon binding energy measured by X-ray photoelectron spectroscopy of 100 eV to 104.0 eV. The underlayer-out transparent with electrodes according to claim 1 or 2 resistivity is 1 [Omega · cm or more substrates. It is a manufacturing method of a substrate with a transparent electrode given in any 1 paragraph of Claims 1-3 ,
A method for producing a substrate with a transparent electrode, wherein the underlayer is formed using a target containing 1 to 4% by weight of silicon oxide.

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