JP6404663B2 - Method for producing transparent conductive laminate - Google Patents

Description

The present invention relates to the production how a copper-based film is laminated on a transparent film substrate the transparent electroconductive laminate.

  Conventionally, an analog resistance film method for detecting conduction at a touch position between two conductive films (electrode layers) arranged to face each other with a dot spacer interposed therebetween has been used for touch panels. The development of capacitive touch panels that detect the touch position of a fingertip by using a change in capacitance has become widespread and has been installed in various devices such as smartphones, tablets, and personal computers.

  In such a display device such as a capacitive touch panel, an indium-tin composite oxide (ITO) thin film having excellent transparency is used as the transparent electrode, but the specific resistance is 10 times that of a single metal. Due to the above, it is said that it is difficult to apply to a large screen. Therefore, instead of this ITO, the mesh pattern copper line, which can increase the sensitivity of capacitance control, is a low resistance conductor, and has excellent mechanical strength, has recently attracted attention. Attempts have been made to commercialize display devices that use surface electrodes. The reason why the electrode is made into a mesh pattern is to arrange the conductors in a planar shape in order to improve the capacitance and to increase the aperture ratio geometrically because the copper line does not transmit light.

  The transparent conductive laminate having the copper pattern is known to have poor adhesion between the film and the copper pattern, while it is desired to use a film substrate as the display device becomes thinner and lighter. Therefore, it is considered to use a thin film made of manganese (Mn), chromium (Cr), nickel (Ni), indium (In), tin (Sn) or an alloy thereof as an adhesion layer between the film and the copper layer, Measures have been taken to improve the adhesion (see, for example, Patent Document 1).

  On the other hand, diffusion (bleeding) of moisture or impure gas that has passed through the film into the copper thin film is also an important issue. Since moisture and impure gas affect the deterioration of the conductive thin film, a barrier layer using a metal oxide film is provided on the film to improve heat resistance and moist heat resistance. Measures have been taken (see, for example, Patent Document 2).

  Further, in Patent Document 3, when the metal oxide thin film is formed with the oxygen concentration in the atmospheric gas at the time of forming the metal oxide thin film being 5 volume% to 15 volume%, it is adjacent to the metal oxide thin film. It has been shown that a metal thin film can ensure high conductivity. Furthermore, it is shown that the resistance value of the metal oxide thin film tends to increase when the oxygen concentration is 15% by volume or more. However, no mention is made regarding the adhesion between the metal oxide thin film and the metal thin film adjacent thereto and the reliability of the metal thin film.

JP-A-61-128593 JP 2002-197925 A JP 2001-329363 A

  In producing a transparent conductive film comprising a mesh pattern copper line, in order to improve the adhesion between the film and the copper layer, manganese (Mn), chromium (Cr), nickel (Ni), indium (In), tin (Sn) When the metal thin film such as) is formed between the film and the copper layer, the difference in etching rate between the copper layer and the metal thin film is greatly different, so that there is a problem that fine line patterning with a line width of 10 μm or less is difficult. If the metal wiring pattern is not thinned, when the metal wiring pattern is formed on the transparent film substrate, the wiring pattern traces are visible, so that the so-called invisibility of the wiring pattern becomes poor, and the transparent conductive film The transparency of the film cannot be ensured, and inconvenience arises when used as a transparent conductive film.

  As the above countermeasure, in Patent Document 2, a silicon compound is formed as an adhesion layer between a film and a metal thin film. The silicon compound is effective as a barrier layer against moisture and impure gas passing through the film. In patent document 2, it aims at the use for the front plate of PDP (plasma display panel), and the characteristic required for a touch panel is not assumed. Therefore, in view of such problems, the present invention makes it possible to achieve high adhesion between the film and the copper layer by forming silicon oxide under specific conditions by sputtering film formation, and has excellent barrier properties. It aims at providing the transparent conductive laminated body for electrostatic capacitance type touch panels with high electroconductivity.

To solve the above problem, a result of inventors studied intensively, by forming the oxidation of silicon at a predetermined film forming conditions, excellent adhesion between the film and the copper layer, and excellent in barrier property, 1 It came to obtain the transparent conductive laminated body in which the copper pattern of the line | wire width of 10 micrometers was formed.

That is, in the present invention, at least a silicon oxide layer is formed between the transparent film and the copper layer, and the silicon oxide layer has an oxygen concentration in the film forming atmosphere gas of 35% by volume to the total amount of introduced gas. a silicon oxide layer under a 60% by volume of the environment is a method for producing to that translucent transparent conductive laminate formed of an oxide mode. It has been found that when the O ₂ concentration during the formation of the silicon oxide layer is less than 35% by volume, the transmittance of the silicon compound is greatly reduced or the adhesion is poor.

In the present invention, the silicon oxide side of the film is preferably a polyester resin. The oxygen partial pressure during film formation is preferably 4.0 × 10 ⁻⁵ Pa to 9.0 × 10 ⁻⁵ Pa, and the silicon oxide is preferably SiOx (1.6 ≦ x ≦ 2.0), and the thickness thereof is The average surface roughness Sa is preferably 0.5 nm to 5 nm or less.

  The copper layer preferably has an aperture ratio of 80% or more after the patterning process, and the silicon oxide is preferably formed by magnetron sputtering.

  In another embodiment of the present invention, oxidation is performed in an environment where the oxygen concentration in the film forming atmosphere gas is 35% by volume to 60% by volume with respect to the total amount of introduced gas on a transparent substrate having at least the outermost surface made of a polyester resin. This is a method for producing a transparent conductive laminate in which a silicon layer is formed, a copper layer is further laminated thereon, and only the copper layer is patterned to form a conductive pattern having a line width of 1 to 10 μm.

  According to the present invention, a silicon oxide layer is used as the base layer of the copper layer, and the oxygen gas ratio with respect to the mixed gas of oxygen gas and argon gas is 35 volume% to 60 volume as the conditions for forming the silicon oxide layer. %, A transparent conductive laminate excellent in high adhesion, durability, and light transparency can be provided.

It is a cross-sectional schematic diagram which shows a conductive laminated body.

Attached to this onset Akira will be described below with reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view of a conductive film 100 in which a silicon oxide layer 21 and a copper layer 22 are sequentially laminated on a transparent film substrate 10. The silicon oxide layer 21 and the copper layer 22 are combined to form a laminated film 23.

  The manufacturing process of a transparent conductive film is demonstrated below. As a production process of the transparent conductive film, the step of forming the silicon oxide layer 21 on the transparent film substrate 10 is preferably formed by a roll-to-roll method using a winding type sputtering apparatus. In addition, the copper layer is preferably formed by sputtering or plating.

<Transparent film substrate>
The transparent film substrate 10 is preferably transparent and colorless at least in the visible light region. Examples of the material for the transparent film substrate 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. The transparent film substrate 10 preferably has a polyester resin formed on the outermost surface. An index matching layer functioning as a functional layer such as a hard coat layer or an optical adjustment layer may be formed on the transparent film substrate 10 with or without a polyester resin.

When the polyester-based resin and the silicon oxide layer are in contact with each other, it is presumed that the bond is strengthened through the carbon and oxygen of the polyester-based resin, and the adhesion with the transparent film substrate is estimated to be strong. Although the thickness of the transparent film board | substrate 10 is not specifically limited, 10 micrometers-400 micrometers are preferable, and 25 micrometers-200 micrometers are more preferable. If the thickness of the transparent film substrate 10 is in the above range, it may have durability and appropriate flexibility. Therefore, it is possible to form the transparent dielectric layer 21 and the copper layer 22 on the transparent film substrate with high productivity by a roll-to-roll method using a winding type sputtering film forming apparatus. The transparent film substrate 10 may have a functional layer such as a hard coat layer formed on one side or both sides.

  In order to improve the adhesion on the transparent polymer film substrate, surface treatment such as roughening treatment is performed on the surface in advance by plasma treatment, corona discharge, flame, ultraviolet ray irradiation, electron beam irradiation, chemical conversion, oxidation, etc. You may do.

<Formation of silicon oxide layer>
A silicon oxide layer 21 is formed on the transparent film substrate 10. As a silicon oxide layer, a copper layer 22 is formed thereon, thereby providing a gas barrier layer that suppresses volatilization of moisture and organic substances from the transparent film substrate 10 and a protective layer that reduces plasma damage to the transparent film substrate. Can work. Furthermore, in this invention, the effect | action which suppresses deterioration of the copper layer by the bleed from a film board | substrate is brought about, Furthermore, the reliability with respect to an environment can be satisfied.

Shape formation of the silicon oxide layer 21 on the transparent film substrate 10, from the viewpoint of rather easy to form a uniform thin film of a nanometer level, and controls the film thickness of several nanometers units, adjusting the hardness and optical properties, sputtering Done by law. From the viewpoint of improving the adhesion between the transparent film substrate 10 and the silicon oxide layer 21, the surface of the transparent film substrate 10 may be subjected to surface treatment such as corona discharge treatment or plasma treatment.

Oxidation of silicon is formed by reactive sputtering. Reactive sputtering includes film formation in three states with different film formation rates and film qualities. Generally, there are three states called a metal mode, a transition mode, and an oxide mode. When sputtering a silicon-based target using a mixed gas of Ar (argon gas) and oxygen as a sputtering gas, there are an oxide mode, a metal mode, and a transition mode.

In the oxide mode, a sufficient amount of reactive gas is present in the chamber to compound the silicon target, and the surface of the silicon target is oxidized, so the deposition rate is very slow. is very stable der is, silicon is a mode capable of forming a sufficiently oxidized highly transparent silicon oxide film.

  The metal mode is a state where there is a low oxygen flow rate and an insufficient amount of reactive gas in the chamber to compound the target surface. This is because oxygen molecules incident on the target surface and adsorbed on the surface This is because the number of oxygen molecules (atoms) knocked out together with silicon by incident ions is larger than the ratio of. Therefore, the film formation rate is very high and the state is very stable, but the film formation is almost uncombined and a metallic film is obtained, so the transparency of the silicon oxide film is also low. Become.

  The transition mode is a state in which the reactive gas is present in the chamber in such an amount that the target is partially compounded. Since the target surface is partially compounded, it is an extremely unstable state between the compound state and the metal state.

Usually, it is often formed in a transition mode from the viewpoint of productivity and transmittance of a silicon oxide film. When silicon oxide is formed in the metal mode, the transmittance is rapidly deteriorated. On the other hand, when it is formed in the oxide mode, there is a concern that the film forming speed may be lowered. However, in the present application, the introduced gas is preferably formed with an oxygen concentration of 35 volume% to 60 volume%, and more preferably 35 volume% to 45 volume%, with respect to the mixed gas of argon gas and oxygen gas. It has been found that forming in mode is desirable for adhesion. If the amount of oxygen is large in the formation of the silicon oxide film, the refractive index of the film is lowered, and an improvement in transmittance can be expected. However, if it is formed at an oxygen concentration greater than 60% by volume, the silicon oxide layer has a porous shape and there is a concern that the resistance to moist heat resistance will deteriorate. The productivity is also sufficiently thin with respect to the metal film, and does not cause a problem within the scope of the present application.

The power density during film formation can be adjusted within a range that does not give excessive heat to the transparent film and does not impair productivity. Proper value of the power density is dependent on the cathode of the shape and size of such flat plate type or a cylindrical type, in the case of the flat type ^{cathode, 0.5W / cm 2 ~10.0W / cm} 2 is preferably about. The pressure (total pressure) in the film ^- forming chamber at the time of forming the silicon oxide layer is preferably 5.0 × 10 ⁻³ Pa to 4.0 × 10 ⁻¹ Pa, and 1.0 × 10 ⁻² Pa to 2.0. × 10 ⁻¹ Pa is more preferable. The oxygen partial pressure to the total pressure during the silicon oxide film formation is ^{4.0 × 10 -5 Pa~9.0 × 10 -5} Pa is preferred.

  According to the study by the present inventors, the morphology changes as the film forming pressure changes, and the higher the film forming pressure, the larger the crystal grains tend to become. The surface roughness Sa of the silicon oxide layer is preferably 0.5 nm to 5 nm, and more preferably 0.5 nm to 2 nm. Such a change in morphology is thought to affect the specific resistance of the transparent conductive film. The film thickness of the silicon oxide layer is preferably 10 to 30 nm. Adhesion can be sufficiently improved when such a thickness relationship is established.

  On the other hand, if the thickness of the silicon oxide layer is too thin, the silicon oxide layer is not formed as a continuous film, so that the function as the adhesion layer cannot be sufficiently exhibited. The substrate temperature at the time of forming the silicon oxide layer may be in a range in which the transparent film substrate has heat resistance, and is preferably 60 ° C. or less, for example. The substrate temperature is more preferably −20 ° C. to 40 ° C., and further preferably −10 ° C. to 20 ° C. By setting the substrate temperature within the above range, embrittlement and dimensional change of the transparent film substrate are suppressed, so that a good quality thin film can be formed.

<Copper layer film formation>
The copper layer is laminated and formed on the silicon oxide layer in order from the transparent film substrate side. With regard to the copper layer, it is possible to form a film only by the sputtering method or only by the plating method, but it is possible to form a base thin film layer for the plating method by the sputtering method and then form the copper film by the plating method. From the viewpoint of production cost. When film formation is performed by a winding type sputtering apparatus, the silicon oxide layer 21 and the copper layer 22 may be continuously formed on the transparent film substrate 10.

  For example, when formed using a sputtering method, the substrate temperature and power density at the time of forming a copper layer are not particularly limited. For example, even within the range of the substrate temperature and power density described above for the formation of a copper layer. Good.

  Argon gas is preferable as the introduced gas during film formation. The pressure (total pressure) in the film forming chamber at the time of forming the copper layer is preferably 0.1 Pa to 1.0 Pa, and more preferably 0.2 Pa to 0.8 Pa. The electroconductivity of an electrode layer can be improved by making film forming pressure into the said range.

<Manufacturing process of transparent conductive laminate for capacitive touch panel>
As the manufacturing process of the capacitive transparent conductive laminate for a touch panel of the present invention, preferably, the transparent film base plate as the first step, a silicon oxide layer is formed by sputtering, the silicon oxide layer as a second step more laminating copper layer sputtering on, performs an antirust treatment on the copper layer as the third step, a resist is formed on the copper layer as the fourth step, the resist is developed as a fifth step, to expose the copper layer, as a mask the resist pattern as a sixth step, the copper layer was d etching, patterning is performed, separating the last remaining resist pattern as a seventh step. The line width of the copper pattern in terms of non-visibility, 1 10 .mu.m are preferred, 1 5 .mu.m is preferred.

[Use of transparent conductive film]
The transparent conductive laminate for a capacitive touch panel of the present invention is preferably used as an electrode for position detection of a capacitive touch panel, since the pattern non-visibility and adhesion are particularly improved. Therefore, each of the silicon oxide layer and the copper layer is preferably a single film rather than an alternately laminated film.

For transparent conductive laminates obtained in the following Examples and Comparative Examples, oxygen partial pressure at the time of forming the transparent conductive laminate, film thickness of the transparent conductive laminate, adhesion, and evaluation of the reflective color layer after 85 ° C. 120 hours test Went. The results are shown in Table 1.

<Film thickness measurement>
The film thickness of the copper layer before etching was measured with a transmission electron microscope.

<Adhesion>
The adhesion force between the silicon oxide layer on the transparent film substrate and the copper layer before patterning was measured using a CYCUS apparatus (surface interface physical property analyzer) NN-05 type (Mitsuwa Frontech Co., Ltd.). The measurement was carried out in a mode in which the blade was moved horizontally and vertically at a constant speed to perform cutting and peeling. The cutting blade was a single crystal diamond cutting blade.

<Color phase (reflection)>
After sequentially laminating a silicon oxide layer and a copper layer on a transparent film substrate, a heat treatment was performed at 80 ° C. for 120 hours as an aging acceleration test in the atmosphere. Measurement was performed using a spectrocolorimeter CM-3600d (Minolta Co., Ltd.) to obtain the reflection a ^* . The a ^* of the copper layer before heating was 12.2.

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

[Example 1]
(Formation of silicon oxide layer)
As the transparent film substrate, a 125 μm thick biaxially stretched PET film on which an easy adhesion layer made of a polyester resin was formed was used. Before forming the silicon oxide layer on the transparent film substrate, heat treatment was performed at 70 ° C. for 1 minute in order to remove moisture and impure gas in the transparent film substrate. Thereafter, a silicon oxide layer was formed in contact with the easy adhesion layer. Using a Si target doped with B (boron), while introducing a mixed gas (oxygen concentration: 36%) of oxygen gas (flow rate: 27.5 sccm) and argon gas (flow rate: 50 sccm) into the apparatus, Sputtering film formation was performed under the conditions of the pressure inside the film: 9.7 × 10 ⁻² Pa, the partial pressure of oxygen: 4.6 × 10 ⁻⁵ Pa, and the power density: 1.5 W / cm ² . The film thickness of the obtained silicon oxide layer was 20 nm.

(Copper layer deposition)
A copper layer was formed on the silicon oxide layer by a sputtering method. Using a copper target, sputtering film formation was performed under the conditions of a film forming chamber pressure: 0.4 Pa and a power density: 4.2 W / cm ² while introducing argon gas (flow rate: 270 sccm) into the apparatus. The film thickness of the obtained copper layer was 300 nm.

(Metal electrode patterning)
After forming the copper layer, performs anti-rust treatment on the copper layer, the resist is patterned by off O preparative lithography method, to expose the wiring pattern portion, the resist pattern as a mask, a copper layer only iron chloride ( and patterned by e etching with 5 vol% III) aqueous solution, and peeled off the last remaining resist pattern was thinned.

(Example 2)
Compared to Example 1, the amount of oxygen gas at the time of forming the silicon oxide layer was changed to a flow rate: 40.0 sccm (oxygen partial pressure: 5.8 × 10 ⁻⁵ Pa) . A transparent conductive laminate was produced without changing other conditions.

(Example 3)
Compared to Example 1, the amount of oxygen gas at the time of forming the silicon oxide layer was changed to a flow rate of 52.0 sccm (oxygen partial pressure: 7.8 × 10 ⁻⁵ Pa) . A transparent conductive laminate was produced without changing other conditions.

(Comparative Example 1)
In contrast to Example 1, no silicon oxide layer was formed . A transparent conductive laminate was produced without changing other conditions.

(Comparative Example 2)
In contrast to Example 1, in addition to not forming the silicon oxide layer, the transparent film substrate was not heat-treated . A transparent conductive laminate was produced without changing other conditions.

(Comparative Example 3)
In contrast to Example 1, the amount of oxygen gas at the time of forming the silicon oxide layer was changed to a flow rate: 20.0 sccm (oxygen partial pressure: 3.3 × 10 ⁻⁵ Pa) to produce a transparent conductive laminate.

As is apparent from Table 1 above, the transparent conductive laminates of the examples maintain high adhesion by forming silicon oxide, while maintaining a high degree of adhesion and a small change in reflection a ^* after the heating test. You can see that it is made. On the other hand, in Comparative Examples 1 and 2 in which no silicon oxide was formed, a ^* after the heating test was large, and it was confirmed that the heating test turned red. Comparing Comparative Examples 1 and 2, it can be inferred that the comparative example 2 in which the substrate was not subjected to the heat treatment before the silicon oxide was formed was caused by moisture or impure gas in the substrate because a ^* was larger. Is done. As for Comparative Example 3, silicon oxide was formed, but the oxygen concentration at the time of silicon oxide formation was lower than the concentration of the example, resulting in low adhesion.

  In an environment where the oxygen concentration is high, it is assumed that the copper layer is modified to copper oxide or the like at the interface between the silicon oxide and the copper layer, and the adhesion is improved, and the degree of oxidation of the silicon oxide film increases, and the silicon oxide film It is thought that the surface was activated more and the wettability with respect to the copper film was improved. However, if the amount of oxygen in the film formation is excessively introduced to increase the degree of oxidation, the silicon oxide layer becomes a porous film and loses its function as a barrier layer, and the high temperature and high humidity reliability deteriorates. There is a concern that Further, when a metal film such as a nickel layer is formed instead of the silicon oxide layer as the underlayer, it is assumed that a patterning failure occurs due to a difference in etching rate with the copper layer, and the total light transmittance is deteriorated.

100 conductive laminate 10 transparent film substrate 21 a silicon oxide layer 22 of copper layer 23 product layer film

Claims (3)

A method for producing a transparent conductive laminate in which a silicon oxide layer and a copper layer are sequentially laminated on at least one surface of a transparent film substrate, and the copper layer is conductively patterned to a line width of 1 to 10 μm,
The silicon oxide layer is SiOx (1.6 ≦ x ≦ 2.0), and the oxide mode has an oxide mode in which the introduction amount of the oxygen gas is 35% by volume to 60% by volume with respect to the mixed gas containing argon gas and oxygen gas . A film is formed with a thickness of 10 to 30 nm by sputtering ,
The copper layer is formed on the silicon oxide layer by sputtering,
The method for producing a transparent conductive laminate, wherein the adhesion between the silicon oxide layer and the copper layer is 35 N / m to 80 N / m. The method for producing a transparent conductive laminate according to claim 1, wherein a surface of the transparent film substrate in contact with the silicon oxide layer is a polyester resin. The method for producing a transparent conductive laminate according to claim 1 or 2 total light transmittance of 90% or more in the copper layer is removed portions of the transparent conductive laminate.