JP2014168938A - Transparent laminate - Google Patents

Abstract

A transparent laminated body in which a pattern is difficult to be visually recognized is provided.
A transparent laminate includes a first transparent thin film and a patterned second transparent thin film in this order on one surface of a transparent film substrate. The transparent laminate 100 includes a second transparent thin film forming region 31 in which the second transparent thin film 22 is formed on the first transparent thin film 21, and a second transparent in which the second transparent thin film is not formed on the first transparent thin film 21. A thin film non-forming region 32 is provided. The surface of the second transparent thin film non-formation region 32 preferably has a microhardness measured by microhardness measurement in the range of 4 to 12 and a plastic deformation rate of 50% or less. The surface of the second transparent thin film forming region 31 preferably has a microhardness measured by microhardness measurement in the range of 4 to 12 and a plastic deformation rate of 50% or less.
[Selection] Figure 1

Description

  The present invention relates to a transparent laminate in which a plurality of thin films are formed on a transparent film substrate. The present invention also relates to a transparent conductive film in which a dielectric layer and a conductor layer are formed on a transparent film substrate.

  Transparent laminates in which an organic or inorganic thin film is formed on a transparent film are used in various fields. For example, a transparent conductive film in which a conductive oxide thin film such as indium-tin composite oxide (ITO) is formed on a transparent film is widely used as a transparent electrode for displays, light-emitting elements, photoelectric conversion elements and the like. Yes. Such a transparent conductive film is manufactured, for example, by forming a conductive oxide thin film as a transparent electrode layer on a transparent substrate by a dry process such as sputtering.

  Depending on the application, the transparent conductive film may be subjected to patterning of the transparent electrode layer. The patterning of the transparent electrode layer is performed, for example, by wet etching using a mask, a resist, or the like so that a part of the in-plane transparent electrode layer is removed. On the surface of the transparent conductive film after patterning, the conductive part (electrode layer forming part) where the transparent electrode layer remains without being etched, and the conductive electrode layer is etched and the underlying layer is exposed. There is a conductive portion (electrode layer non-formed portion).

  Thus, it is required for the transparent conductive film in which the transparent electrode layer is patterned that the pattern is difficult to be visually recognized (the invisibility of the pattern). It is known that the difference in optical characteristics (difference in transmittance, refractive index, etc.) between the “conductive part” and the “non-conductive part” affects the (non) visibility of the pattern. For example, in Patent Document 1, by providing a transparent dielectric layer having predetermined optical characteristics between the film base and the transparent electrode layer, the difference in optical characteristics between the conductive part and the non-conductive part is reduced. And suppressing the visual recognition of the pattern has been proposed.

JP 2010-15861 A JP 2001-96661 A

  Reducing the difference in optical properties between the conductive part and the non-conductive part is effective for suppressing pattern visual recognition. However, according to the study by the present inventors, it has been found that the invisibility of the pattern cannot be sufficiently enhanced only by the optical design. As a result of a more detailed examination of pattern visual recognition, in a transparent conductive film in which the transparent electrode layer was patterned, film waviness occurred at the same cycle as the pattern of the transparent electrode layer, and wrinkles were observed along the pattern boundaries. Had occurred. The visual recognition of the pattern of the transparent conductive film was considered to be caused by light reflection or refraction near the pattern boundary accompanying such deformation.

  Such deformations such as wrinkles due to patterning are presumed to involve stress strain at the interface between the transparent electrode layer and the underlying layer. As a method for evaluating the shape and distortion of a film, stress evaluation of a thin film by X-ray diffraction is cited as the most effective evaluation technique. However, stress evaluation by X-ray diffraction can only be used for crystalline thin films. A method for measuring stress by deriving a radial distribution function from X-ray fine structure absorption measurement of a thin film is also known. However, the evaluation by the radial distribution function has a problem in the reliability of the measurement result for a thin film having a film thickness of 100 nm or less.

  Thus, in the prior art, a method for evaluating a physical index such as a stress of a thin film has not been established, and the physical index such as strain and shape of a transparent laminated body including a patterned thin film and a pattern (non- ) It was difficult to find an association with visibility. In view of such a current situation, the present invention establishes a method for evaluating a physical index of a thin film and aims to improve the non-visibility of a pattern in a transparent laminate in which the thin film is patterned. Furthermore, this invention aims at provision of the design method for improving the invisibility of the pattern in a transparent laminated body by evaluating the characteristic of a thin film.

  In view of the above problems, the present inventors have focused on the hardness of the thin film in the laminate. In recent years, it has become possible to measure microhardness by nanoindentation as a method for evaluating thin films. However, there have been few examples focusing on the hardness of a thin film in a transparent conductive film or the like so far, and in Patent Document 2, it has been proposed that the microhardness and the plastic deformation rate are in a predetermined range.

  Patent Document 2 discloses that the microhardness of the surface of the transparent conductive film is 15 or more and the plastic deformation rate is 55% or less in order to improve the connection processing of the connector electrode for the touch panel. As a specific means, it is disclosed that a high-hardness coating film (hard coat layer) is formed on a film substrate and a conductive oxide thin film (ITO) is formed thereon. When the present inventors produced the transparent conductive film disclosed by the Example of the said patent document 2, and performed the patterning by an etching, the wrinkle along a pattern had generate | occur | produced and the pattern was visually recognized.

  Thus, in the prior art, since the hardness of the thin film was high and the buffering action was small, it was estimated that when the thin film was patterned, wrinkles were generated in the laminate, which led to the visual recognition of the pattern. That is, since the hardness of the thin film is high, when the stress acts on the interface due to thermal contraction of the film during thin film formation or crystallization, the buffering action of the interface is small, and the shape of the film is not maintained. It was thought that wrinkles along the line were likely to occur.

  Under the above estimation principle, the present inventors have found that the hardness and plastic deformation rate of the thin film on the film affect the pattern visibility of the transparent laminate, and have led to the present invention.

  The present invention relates to a transparent laminate including a first transparent thin film and a patterned second transparent thin film in this order on one surface of a transparent film substrate. The transparent laminate of the present invention includes a second transparent thin film forming region in which a second transparent thin film is formed on the first transparent thin film, and a second transparent thin film in which the second transparent thin film is not formed on the first transparent thin film. It has a formation area. The surface of the second transparent thin film non-formation region preferably has a microhardness measured by microhardness measurement in the range of 2 to 12 and a plastic deformation rate of 50% or less. The surface of the second transparent thin film forming region preferably has a microhardness measured by microhardness measurement in the range of 4 to 12 and a plastic deformation rate of 50% or less.

  The total thickness of the first transparent thin film and the second transparent thin film in the second transparent thin film forming region is preferably 60 nm to 100 nm. The film thickness of the second transparent thin film is preferably 10 nm to 32 nm.

  In one embodiment, the first transparent thin film is composed of two or more thin films. In one embodiment, the first transparent thin film includes one or more layers mainly composed of silicon oxide. In particular, the first transparent thin film preferably has a layer mainly composed of silicon oxide on the surface on the second transparent thin film side.

  One embodiment of the transparent laminate of the present invention is a transparent conductive film in which the first transparent thin film is a dielectric layer and the second transparent thin film is a conductor layer (transparent electrode layer).

  According to the present invention, the hardness and plastic deformation rate of the thin film constituting the transparent laminated body are within a predetermined range, so that even when the outermost thin film is patterned, warping and deformation of the laminated body are suppressed, and the pattern The non-visibility is improved.

It is a typical sectional view of a transparent layered product concerning one embodiment.

[Configuration of transparent laminate]
The transparent laminate of the present invention has a first transparent thin film 21 and a second transparent thin film 22 on a transparent film substrate 10. The second transparent thin film 22 is patterned. Since the second thin film 22 is patterned, the transparent laminate has a second transparent thin film forming region 31 in which the second transparent thin film 22 is formed on the first transparent thin film 21 and a first transparent thin film 21 on the first transparent thin film 21. And a second transparent thin film non-forming region 32 in which the two transparent thin films are not formed.

[Embodiment of transparent conductive film]
Hereinafter, the transparent conductive film embodiment will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of a transparent conductive film 100 having a transparent dielectric layer 21 and a transparent electrode layer 22 on a transparent film substrate 10.

<Transparent film substrate>
The transparent film substrate 10 is preferably transparent and colorless at least in the visible light region. Examples of the transparent film base 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. Is mentioned. Although the thickness of the transparent film base material 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 base material 10 is the said range, it may have durability and moderate softness | flexibility. Therefore, it is possible to form the transparent dielectric layer 21 and the transparent electrode 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 (not shown) such as a hard coat layer formed on one side or both sides.

<Dielectric layer (first transparent thin film)>
On the transparent film substrate 10, a transparent dielectric layer 21 is formed as a first transparent thin film. As a material for the transparent dielectric layer 21, an inorganic oxide is preferably used from the viewpoints of transparency, electrical characteristics, productivity, and the like. As the oxide, an oxide that is colorless and transparent in the visible light region and has a resistivity of 10 Ω · cm or more is preferable. For example, a metal or semi-metal oxide such as Si, Ge, Sn, Al, Ga, In, V, Nb, Ta, Ti, Zr, Zn, and Hf is preferably used. The transparent dielectric layer 21 may be composed of one layer, or may be composed of two or more layers as shown in FIG.

<Transparent electrode layer (second transparent thin film)>
On the transparent dielectric layer 21, a transparent electrode layer 22 is formed as a second transparent thin film. The transparent electrode layer 22 is a conductor layer, and is made of, for example, a conductive oxide thin film. As the conductive oxide, metal oxides such as zinc oxide, tin oxide, indium oxide, and titanium oxide, or composite metal oxides thereof are preferably used. From the viewpoint of enhancing conductivity, the conductive oxide is preferably a composite metal oxide, and in particular, an oxide containing indium oxide as a main component is preferably used. From the viewpoint of realizing high transmittance and low resistance, the transparent electrode layer 22 preferably contains 87.5% by mass to 99.0% by mass of indium oxide. The content of indium oxide is more preferably 90% by mass to 95% by mass. The metal oxide containing indium oxide as a main component preferably contains a doped impurity for imparting conductivity by imparting carrier density to the conductive thin film. As such doping impurities, tin oxide, zinc oxide, titanium oxide, tungsten oxide and the like are preferable. The transparent electrode layer when the doping impurity is tin oxide is indium tin oxide (ITO), and the transparent electrode layer when the doping impurity is zinc oxide is indium oxide zinc (IZO). In the transparent electrode layer mainly composed of indium oxide, the content of the doping impurity is preferably 4.5% by mass to 12.5% by mass, and more preferably 5% by mass to 10% by mass.

  The transparent electrode layer 22 is patterned by removing a part of the surface by etching or the like. Therefore, the transparent conductive film 100 includes a conductive portion (second transparent thin film forming region) 31 that remains without the transparent electrode layer 22 being removed, and the transparent dielectric layer that is a base layer from which the transparent electrode layer is removed. It has the nonelectroconductive part (2nd transparent thin film non-formation area | region) 32 where the body layer 21 is exposed. The pattern can be formed in an arbitrary shape according to the application. Each of the separated patterns 31a, 31b, 31c is preferably insulated from each other.

  When patterning is performed by etching, only the transparent electrode layer 22 may be etched, and the transparent dielectric layer 21 may be etched together with the transparent electrode layer 22. When the transparent dielectric layer 21 is etched, it is preferable that only a part of the transparent dielectric layer 21 in the thickness direction is etched so that the transparent film substrate 10 is not exposed. From the viewpoint of adjusting the microhardness and plastic deformation rate of the transparent conductive film within a predetermined range, it is preferable that only the transparent electrode layer 22 is patterned.

<Hardness and plastic deformation rate of thin film>
2-12 are preferable, as for the micro hardness of the surface of the nonelectroconductive part 32, 4-11 are more preferable, and 5-10 are more preferable. Further, the plastic deformation rate on the surface of the nonconductive portion 32 is preferably 50% or less, more preferably 10% to 45%, further preferably 15% to 40%, and particularly preferably 20% to 35%. By setting the microhardness and the plastic deformation rate of the surface of the non-conductive portion within the above ranges, it is possible to obtain a transparent conductive film in which wrinkles along the pattern are difficult to occur and the pattern is hardly visible.

  The characteristics of the surface of the non-conductive portion 32, that is, the surface of the transparent dielectric layer 21, are related to the characteristics of the interface between the transparent dielectric layer 21 and the transparent electrode layer 22 before the transparent electrode layer 22 is removed by etching. It is considered that the nature is high. In the conductive film 31 where the transparent electrode layer 22 is formed on the transparent dielectric layer 21 in the patterned transparent conductive film, stress strain remains at the interface between the transparent dielectric layer 21 and the transparent electrode layer 22. It is thought that there is. As the stress strain at the interface, a film-forming strain generated when the transparent electrode layer 22 is formed, or a strain accompanying a dimensional change of the base film or the transparent electrode layer when the conductive oxide in the transparent electrode layer is crystallized. Is assumed. On the other hand, in the non-conductive portion 32, it is considered that the stress strain at the interface is released by removing the transparent electrode layer. Therefore, the larger the residual stress strain at the interface between the transparent dielectric layer 21 and the transparent electrode layer 22, the greater the residual stress difference between the conductive portion and the non-conductive portion, which causes the film substrate to bend. , It is considered to appear in the shape as wrinkles along the pattern.

  In the present invention, a relatively soft transparent dielectric layer (first transparent thin film) 21 having a low hardness is formed on the transparent film substrate 10, and a transparent electrode layer (second transparent thin film) 22 is formed thereon. Thus, it is presumed that the transparent dielectric layer 21 has an interface stress buffering action. Therefore, even when the transparent electrode layer is patterned and the transparent electrode layer in the non-conductive portion (second transparent thin film non-formation region) is removed, the residual stress difference between the conductive portion and the non-conductive portion is small, warping and It is considered that bending or the like is suppressed.

The microhardness and the plastic deformation rate can be measured with a microhardness meter (nanoindentation measuring device). In the nano-indentation measurement, the indenter is pushed into a small region of several μm ² to quantitatively evaluate the plasticity / elasticity of the thin film, the accompanying deformation rate, Young's modulus, and the like. The plastic deformation rate is an index indicating how much the displacement (maximum displacement) when a predetermined load is applied to the sample is restored after unloading. The microhardness and the plastic deformation rate are calculated by the following formulas (1) and (2) from the result of nanoindentation measurement (load-displacement curve).

Micro hardness = α × maximum load / maximum displacement amount (1)
Plastic deformation ratio (%) = displacement after unloading / maximum displacement × 100 (2)
In the above formula (1), α is a constant and is determined according to the projected area and indentation depth of the indenter used for nanoindentation measurement.

  When the microhardness of the surface of the non-conductive portion 32 is larger than the above range, deformation along the pattern of the transparent electrode layer 22 is likely to occur, and the pattern tends to be visually recognized (non-visibility is reduced). This is because when the transparent electrode layer 22 of the nonconductive portion 32 is removed by etching or the like, or when a dimensional change occurs during crystallization of the transparent electrode layer after etching, the transparent dielectric layer 21 becomes conductive. It is considered that the strain of the stress at the boundary between the portion 31 and the non-conductive portion 32 cannot be followed and the strain appears as a shape strain of the film. On the other hand, when the microhardness of the surface of the nonconductive portion 32 is smaller than the above range, the mechanical strength of the thin film cannot be ensured, and damage due to a physical load or the like is likely to occur.

  Further, by reducing the plastic deformation rate on the surface of the non-conductive portion 32, flexibility can be imparted to the transparent laminate, and the strain can be easily recovered. If the plastic deformation rate on the surface of the non-conductive portion 32 is 10% or more, the shape of the laminate is easily stabilized due to elasticity, and deformation such as wrinkles tends to be suppressed.

  As described above, in the present invention, by setting the microhardness and plastic deformation rate of the surface of the non-conductive portion (second transparent thin film non-formation region) 32 within the above ranges, the strength of the thin film is ensured and the flexibility is secured. Can be granted. Therefore, a laminate that can flexibly follow the strain after patterning of the transparent electrode layer (second transparent thin film) 22 is obtained.

  4-12 are preferable, as for the microhardness of the electroconductive part 31 surface, 6-11 are more preferable, and 7-10 are more preferable. The plastic deformation rate on the surface of the conductive portion 31 is preferably 50% or less, more preferably 10% to 45%, further preferably 15% to 40%, and particularly preferably 20% to 35%. By setting the microhardness and the plastic deformation rate of the surface of the conductive portion within the above ranges, it is possible to obtain a transparent conductive film in which wrinkles along the pattern are difficult to occur and the pattern is hardly visible.

  If the surface hardness and plastic deformation rate of the conductive portion 31 are within the above ranges, the difference in hardness and plastic deformation rate at the interface between the transparent dielectric layer 21 and the transparent electrode layer 22 is small. The residual stress at is reduced. Therefore, it is considered that deformation such as wrinkles due to the residual stress difference between the conductive portion and the non-conductive portion is less likely to occur.

  From the viewpoint of reducing residual stress at the interface between the transparent dielectric layer 21 and the transparent electrode layer 22 and suppressing deformation such as wrinkles, the microhardness of the surface of the conductive portion 31 and the surface of the nonconductive portion 32 are reduced. The difference from the microhardness is preferably 5 or less, more preferably 3 or less, still more preferably 2 or less, and particularly preferably 1.5 or less. Either the microhardness of the surface of the conductive portion 31 or the microhardness of the surface of the nonconductive portion 32 may be large. Further, the difference between the plastic deformation rate of the surface of the conductive portion 31 and the plastic deformation rate of the surface of the nonconductive portion 32 is preferably 6% or less, more preferably 4% or less, further preferably 3% or less. .5% or less is particularly preferable. Either the plastic deformation rate of the surface of the conductive portion 31 or the plastic deformation rate of the surface of the nonconductive portion 32 may be large.

  The total thickness of the transparent dielectric layer 21 and the transparent electrode layer 22 in the conductive portion 31 is preferably 60 nm to 100 nm, and more preferably 70 nm to 90 nm. The film thickness of the transparent dielectric layer 21 is preferably 28 nm to 80 nm, and more preferably 35 nm to 70 nm. The film thickness of the transparent electrode layer 22 is preferably 10 nm to 32 nm, and more preferably 15 nm to 30 nm.

  If the thickness of each layer is excessively small, the hardness of the thin film becomes small and the strength may be insufficient. In addition, if the thickness of each layer is excessively large, the hardness of the thin film increases, so that there is a tendency that deformation occurs during patterning or transparency decreases. When the thickness of the transparent dielectric layer 21 is in the above range, it is possible to provide a follow-up property to the strain while ensuring the physical strength. When the thickness of the transparent electrode layer 22 is in the above range, both low resistance and high transparency can be achieved. If the thickness of the transparent electrode layer is excessively large, the hardness of the conductive portion 31 tends to increase. Accordingly, the difference in hardness and the difference in plastic deformation rate between the conductive portion 31 and the nonconductive portion 32 are caused. In some cases, the deformation becomes larger due to residual stress at the interface.

The resistivity of the transparent electrode layer 22 can be appropriately set according to the application and the like. For example, when the transparent conductive film is used as a transparent electrode for a capacitive touch panel, the resistivity of the transparent electrode layer is preferably 5.0 × 10 ⁻⁴ Ω · cm or less, and 4.5 × 10 ^{− It} is more preferably ⁴ Ω · cm or less, and further preferably 3.7 × 10 ⁻⁴ Ω · cm or less. When the resistivity of the transparent electrode layer is within the above range, the response speed of the touch panel can be increased. From the viewpoint of setting the resistivity within the above range, the conductive oxide such as ITO constituting the transparent electrode layer is preferably crystalline.

<Laminate design>
As described above, by controlling the hardness and plastic deformation rate of the thin film, the deformation of the film can be suppressed from the mechanical viewpoint, and the visual recognition of the pattern in the laminate can be suppressed. In addition, by adjusting the refractive index and thickness of the thin film, the difference in transmittance, reflectance, and color difference between the conductive part and non-conductive part can be reduced to reduce pattern visibility from the viewpoint of optical design. You can also

For example, as the transparent dielectric layer 21, a plurality of layers having different refractive indexes are stacked, whereby the visibility of the pattern can be suppressed. In this case, a transparent dielectric is taken into account by taking into account the refractive index of the film substrate 10 (generally about 1.4 to 1.7) and the refractive index of the transparent electrode layer 22 (generally about 1.8 to 2.2). The configuration of the body layer 21 is preferably determined. For example, as shown in FIG. 1, the transparent dielectric layer 21 includes a first dielectric layer 211 having a medium refractive index (refractive index: n ₁ ) and a second dielectric having a high refractive index from the transparent base film 10 side. In the case of a three-layered structure of a layer 212 (refractive index: n ₂ ) and a low-refractive third dielectric layer 213 (refractive index: n ₃ ), the refractive index of these three layers is n ₃ <n ₁ <it is preferable to satisfy a relation _{n 2.} The refractive index n ₄ of the transparent electrode layer 22 is preferably smaller than the refractive index n _{2 of} the second dielectric layer 212 and larger than the refractive index n _{1 of} the first dielectric layer 211. That is, when the transparent dielectric layer 21 is composed of three layers, the refractive index of the thin film constituting the transparent conductive film preferably satisfies the relationship of _{n 3 <n 1 <n 4} <n 2. In addition, a refractive index is a refractive index with respect to the light of wavelength 550nm measured by spectroscopic ellipsometry.

As an example of a configuration in which the dielectric layer 21 has three layers, the first dielectric layer 211 mainly composed of SiO _x (1 ≦ x <2) or aluminum oxide from the transparent film substrate 10 side; Nb, Ta, Ti , Zr, Zn, and Hf, the second dielectric layer 212 mainly composed of an oxide of a metal selected from the group consisting of; and the third dielectric composed mainly of SiO _y (1.5 <y ≦ 2) The thing provided with the body layer 213 in this order is mentioned. When the dielectric layer 21 is composed of three layers, the thickness of each dielectric layer is such that the difference in optical characteristics between the conductive portion 31 and the nonconductive portion 32 is reduced. It can be set appropriately in consideration of the product of the film thickness. For example, the first dielectric layer 211 having a film thickness d _{1 of 1} nm to 25 nm, the second dielectric layer 212 having a film thickness d ₂ of 5 nm to 15 nm, and the third dielectric layer 213 having a film thickness d ₃ of 30 nm to 80 nm. The structure which consists of these three layers is preferable.

  Thus, when the dielectric layer (first transparent thin film) 21 is composed of a plurality of layers, the characteristics of the dielectric layer 213 which is the surface layer of the dielectric layer 21 on the transparent electrode layer (second transparent thin film) 22 side are This is the main factor that determines the microhardness and plastic deformation rate of the surface of the non-conductive portion (second transparent thin film non-forming region) 32. If the dielectric layer 213 which is the outermost surface layer on the transparent electrode layer 22 side is a layer containing silicon oxide as a main component, it is easy to obtain optical merits due to lowering the refractive index. The microhardness and plastic deformation rate of the surface of 32 can be easily adjusted to the above-mentioned preferable ranges. When the film thickness of the dielectric layer 213 mainly composed of silicon oxide increases, the hardness of the nonconductive portion 32 tends to increase.

  When a high refractive index metal oxide layer such as niobium oxide, titanium oxide, tantalum oxide, zirconium oxide or the like is formed as the dielectric layer 212 immediately below the dielectric layer 213, these metal oxides are generally made of silicon oxide. Is also very hard. Therefore, the characteristics of the dielectric layer 212 made of a metal oxide can also be a factor that determines the microhardness and the plastic deformation rate of the surface of the nonconductive portion 32. In particular, when the thickness of the dielectric layer 212 containing metal oxide as a main component is large, the hardness of the dielectric layer 21 tends to increase. Therefore, the film thickness of the dielectric layer 212 containing metal oxide as a main component is preferably 15 nm or less from the viewpoints of both improvement of pattern non-visibility by optical design and improvement of pattern non-visibility by deformation prevention. Is more preferable.

[Method for producing transparent conductive film]
Hereinafter, the manufacturing process of a transparent conductive film is demonstrated.
In the production process of the transparent conductive film, the transparent electrode layer is preferably patterned after the transparent dielectric layer 21 and the transparent electrode layer 22 are sequentially formed on the transparent film substrate 10. The transparent dielectric layer 21 and the transparent electrode layer 22 are preferably formed by a roll-to-roll method using a winding type sputtering apparatus.

<Deposition of dielectric layer (first transparent thin film)>
On the transparent film substrate 10, a transparent dielectric layer 21 is formed as a first transparent thin film. When the transparent electrode layer 22 is formed thereon, the transparent dielectric layer reduces plasma damage to the gas barrier layer that suppresses volatilization of moisture and organic substances from the transparent film substrate 10 and the transparent film substrate. In addition to acting as a protective layer, it can also act as an underlayer for film growth during the formation of a transparent electrode layer. Furthermore, in the present invention, the transparent dielectric layer 21 provides a buffering action on the transparent electrode layer 22 forming interface, so that when the transparent electrode layer 22 is patterned, the occurrence of deformation such as wrinkles is suppressed, and the pattern Invisibility can be improved.

  The formation method of the transparent dielectric material layer 21 on the transparent film base material 10 will not be specifically limited if it is a method in which a uniform thin film is formed. Examples of the film forming method include dry coating methods such as sputtering, vapor deposition, and various CVD methods, and wet coating methods such as spin coating, roll coating, spray coating, and dipping coating. Among the above film forming methods, the dry coating method is preferable from the viewpoint of easily forming a nanometer-level thin film. In particular, the sputtering method is preferable from the viewpoint of controlling the film thickness in units of several nanometers and adjusting the hardness and optical characteristics. From the viewpoint of enhancing the adhesion between the transparent film substrate 10 and the transparent dielectric layer 21, surface treatment such as corona discharge treatment or plasma treatment is performed on the surface of the transparent film substrate 10 prior to the formation of the transparent dielectric layer. It may be done.

When the transparent dielectric layer is formed by sputtering, a metal, metal oxide, metal carbide, or the like can be used as the target. As the power source, a DC, RF, MF power source or the like can be used. From the viewpoint of productivity, an MF power source is preferable. 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 a flat type ^{cathode, 2W / cm 2 ~10W / cm} 2 is preferably about.

  Sputter deposition is performed while a carrier gas containing an inert gas such as argon or nitrogen and an oxygen gas is introduced into the deposition chamber. The introduced gas is preferably a mixed gas of argon and oxygen.

  The pressure (total pressure) in the film forming chamber at the time of forming the dielectric layer is preferably 0.2 Pa to 8.0 Pa, more preferably 0.3 Pa to 6.0 Pa, and further preferably 0.5 Pa to 5.5 Pa. When the film forming pressure increases, the hardness of the dielectric layer tends to decrease and the plastic deformation rate tends to increase. Therefore, by setting the film forming pressure of the dielectric layer within the above range, the hardness and plastic deformation rate of the conductive portion 31 and the nonconductive portion 32 can be controlled within the above range. According to the study by the present inventors, the morphology changes with the change of the film forming pressure of the dielectric layer, and the higher the film forming pressure, the larger the crystal grains tend to be. It is considered that film properties such as hardness and plastic deformation rate change due to such a change in morphology.

  When silicon oxide is formed as the dielectric layer, the smaller the amount of oxygen introduced during film formation, the higher the hardness of the film and the lower the plastic deformation rate. This is presumed to be due to the fact that the discharge mode of sputtering shifts from the transition region to the metal region as the amount of oxygen introduced decreases, and the characteristics of the resulting oxide film change. The optimum value of the oxygen introduction amount varies depending on the configuration of the film forming apparatus and the like. However, when silicon oxide is formed as the dielectric layer, the oxygen partial pressure in the film forming chamber is 0. 0 of the film forming pressure (total pressure). 01 times to 0.3 times are preferable, 0.02 times to 0.15 times are more preferable, and 0.03 times to 0.12 times are more preferable.

  As shown in FIG. 1, when the dielectric layer 21 consists of two or more layers, it is particularly preferable that the dielectric layer 213 on the surface of the transparent electrode layer 22 is formed under the above conditions.

  The substrate temperature at the time of forming the dielectric 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 high-quality thin film can be formed.

<Filming of transparent electrode layer (second transparent thin film)>
On the transparent dielectric layer 21, a transparent electrode layer 22 is formed as a second transparent thin film. The transparent electrode layer 22 is also preferably formed by a sputtering method. When film formation is performed by a winding type sputtering apparatus, the transparent dielectric layer 21 and the transparent electrode layer 22 may be continuously formed on the transparent film substrate 10.

As a target used for sputtering film formation, metal, metal oxide, or the like is used. In particular, an oxide target containing indium oxide and tin oxide or zinc oxide is preferably used. The oxide target preferably contains 87.5% by mass to 95.5% by mass of indium oxide.
The substrate temperature and power density at the time of forming the transparent electrode layer are not particularly limited, and may be, for example, the range of the substrate temperature and power density described above with respect to the formation of the transparent dielectric layer.

The gas introduced during the formation of the transparent electrode layer is preferably a mixed gas of argon and oxygen. The amount of oxygen introduced into the film forming chamber is preferably 0.1% by volume to 2.0% by volume, and more preferably 0.4% by volume to 1.5% by volume with respect to the total amount of introduced gas. The pressure (total pressure) in the film forming chamber at the time of forming the transparent electrode layer is preferably 0.1 Pa to 1.0 Pa, and more preferably 0.2 Pa to 0.8 Pa. The oxygen partial pressure in the deposition chamber is preferably from ^{1 × 10 -2 Pa~2 × 10 -1} Pa, 2 × 10 -2 Pa~1 × 10 -1 Pa is more preferable. By setting the film forming pressure and the amount of introduced gas in the above ranges, the transparency and conductivity of the transparent electrode layer can be improved. The mixed gas may contain other gases as long as the function of the present invention is not impaired.

<Patterning of transparent electrode layer>
By removing a part of the surface of the transparent electrode layer 22 by etching or the like, the transparent electrode layer 22 is patterned. The method for etching the transparent electrode layer may be either a wet process or a dry process, but a wet process is suitable from the viewpoint of selectively removing only the transparent electrode layer 22. A photolithography method is suitable as the wet process. As a photoresist, a developing solution, and a rinse agent used for photolithography, those that can form a predetermined pattern without damaging the transparent electrode layer 22 can be arbitrarily selected. As the etching solution, one that can dissolve and remove the transparent electrode layer 22 and does not attack the dielectric layer 21 is preferably used.

<Crystallization of transparent electrode layer>
A transparent electrode layer made of a metal oxide such as ITO is generally amorphous immediately after sputtering film formation. Depending on the use of the transparent conductive film, the transparent electrode layer is crystallized for the purpose of improving the transmittance of the transparent electrode layer and reducing the resistance. Crystallization is performed by heating the transparent electrode layer formed on the substrate. The heat treatment of the transparent electrode layer is performed, for example, in an oven at 120 ° C. to 150 ° C. for 30 to 60 minutes. Alternatively, it may be heated for a long time at a relatively low temperature such as 1 to 3 days at a lower temperature (for example, about 50 ° C. to 120 ° C.). Crystallization of the transparent electrode layer may be performed before or after patterning.

[Use of transparent conductive film]
The transparent conductive film of this invention can be used as transparent electrodes, such as a display, a light emitting element, and a photoelectric conversion element. In particular, since the non-visibility of the pattern is improved, it is preferably used as an electrode for position detection of a capacitive touch panel.

[Application to other transparent laminates]
In the above, this invention was demonstrated centering on embodiment of the transparent conductive film provided with a dielectric material layer as a 1st transparent thin film, and a conductor layer (transparent electrode layer) as a 2nd transparent thin film. In addition, this invention can suppress the pattern visual recognition with the 2nd transparent thin film formation part 31 and the 2nd transparent thin film non-formation part 32 by making the hardness and plastic deformation rate of a thin film into a predetermined range. Therefore, it can be applied to various transparent laminates regardless of the conductivity of the first transparent thin film and the second transparent thin film.

  Further, according to the present invention, it is presumed that the stress strain at the interface of the thin film is reduced by setting the hardness and plastic deformation rate of the thin film within a predetermined range. Such a principle of the present invention is not limited to the optical point of view of enhancing the invisibility of the thin film pattern, and can also be applied to shape control such as suppressing warping and deformation of the film.

  According to the above viewpoints, the present invention provides a method for designing a transparent laminate by measuring the microhardness of a thin film on the transparent laminate. That is, the present invention measures the microhardness of the thin film on the transparent laminate, and makes the microhardness and plastic deformation rate within a predetermined range, whereby the pattern visibility control method of the transparent laminate, or the deformation of the transparent laminate. It can be applied as a deterrent method.

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

  As the film thickness of each transparent dielectric layer and transparent electrode layer, values obtained by observation with a transmission electron microscope (TEM) of the cross section of the transparent laminate were used. The refractive index of each transparent dielectric layer and transparent electrode layer was determined for light having a wavelength of 550 nm by spectroscopic ellipsometry measurement.

The micro hardness and the plastic deformation rate were measured using an ultra micro hardness measuring apparatus (ENT-1000 manufactured by Elionix Co., Ltd.) equipped with a diamond indenter. The measurement conditions were an indentation load of 40 μN and a holding time when the maximum load was reached was 1 second. In the measurement, the transparent film substrate side of the sample was fixed on the sample table using an adhesive. In this measurement, the coefficient (refer to the above (Formula 1)) determined according to the projected area of the indenter and the indentation depth was α = 3.87 × 10 ⁻³ [μm / μN].

  The (non) visibility of the pattern of the transparent electrode layer was evaluated visually by observing the reflected light from the sample under a straight tube fluorescent lamp. Various changes are made to the tilt of the sample, and the reflected image of the fluorescent lamp appears to be linear (at a score = 3: no wrinkles) at the angle at which the pattern can be seen most. The evaluation was conducted in three stages.

[Example 1]
(Dielectric layer deposition)
As the transparent film substrate, a biaxially stretched PET film having a thickness of 188 μm in which hard coat layers made of urethane resin were formed on both surfaces was used. On one surface of this PET film, there are three layers of transparent dielectric layers, a middle refractive index layer made of silicon oxide, a high refractive index layer made of niobium oxide, and a low refractive index layer made of silicon oxide. Formed in order.

Medium refractive index layer: Boron-doped silicon was used as a target, and oxygen partial pressure was introduced into the apparatus while oxygen partial pressure: 3 × 10 ⁻² Pa, film forming chamber pressure: 0.3 Pa, Sputtering film formation was performed under the conditions of the substrate temperature: 0 ° C. and the power density: 3.0 W / cm ² . The obtained middle refractive index layer had a thickness of 10 nm and a refractive index of 1.5.

High refractive index layer: Using niobium as a target and introducing a mixed gas of oxygen and argon into the apparatus, oxygen partial pressure: 1 × 10 ⁻² Pa, film forming chamber pressure: 0.2 Pa, substrate temperature: 0 ° C. Then, sputtering film formation was performed under the condition of power density: 1.5 W / cm ² . The resulting high refractive index layer had a thickness of 10 nm and a refractive index of 2.2.

Low refractive index layer: Using silicon as a target and introducing a mixed gas of oxygen and argon (flow ratio oxygen: argon = 1: 9) into the apparatus, oxygen partial pressure: 1 × 10 ⁻² Pa, film forming chamber Sputtering film formation was performed under the conditions of pressure: 0.3 Pa, substrate temperature: 0 ° C., power density: 4 W / cm ² . The film thickness of the obtained refractive index layer was 40 nm, and the refractive index was 1.5.

(Transparent electrode layer deposition)
An indium tin oxide (ITO) thin film was formed as a transparent electrode layer on the dielectric layer. Using indium tin oxide (tin oxide content 5 mass%) as a target and introducing a mixed gas of oxygen and argon into the apparatus, oxygen partial pressure: 5 × 10 ⁻³ Pa, film forming chamber pressure: 0.5 Pa Sputtering was performed under the conditions of substrate temperature: 0 ° C. and power density: 4 W / cm ² . The film thickness of the obtained transparent electrode layer was 25 nm.

After the transparent electrode layer was formed, ITO was crystallized by heating at 150 ° C. for 1 hour. The resistivity of the transparent electrode layer after heating was 3.2 × 10 ⁻⁴ Ω · cm, the surface resistance was 128Ω / □, and the carrier density was 6.3 × 10 ²⁰ / cm ³ .

(Patterning)
On the crystallized transparent electrode layer, a positive photoresist (product name: TSMR-8900, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied in a thickness of 5 μm by spin coating. This was prebaked on a hot plate set at 90 ° C., and then exposed to ultraviolet rays having an integrated irradiation amount of 78 mJ. Thereafter, development was performed by immersing in a 0.5% by mass aqueous sodium hydroxide solution. After rinsing with pure water, the ITO was etched using an etching solution (product name: ITO-02 manufactured by Kanto Chemical Co., Inc.). After rinsing with pure water, the resist was peeled off with a 2% strength by weight aqueous sodium hydroxide solution, rinsed with pure water, and then dried.

  By the above process, a transparent dielectric layer consisting of three layers of a medium refractive index layer / a high refractive index layer / a low refractive index layer is provided on a transparent film substrate, and a transparent ITO transparent electrode layer patterned thereon is provided. A conductive film was produced.

[Examples 2-8, Comparative Examples 1-8]
The film forming conditions and film thickness of the low refractive index layer of the transparent dielectric layer and the film thickness of the transparent electrode layer were changed as shown in Table 1. Other than that was carried out similarly to Example 1, and produced the transparent conductive film provided with the patterned ITO transparent electrode layer.

  Table 1 shows the production conditions of the transparent conductive films of the above Examples and Comparative Examples, the thickness of each layer, the microhardness and plastic deformation rate in each of the conductive part and the non-conductive part, and the evaluation result of pattern visual recognition. .

  As shown in Table 1 above, in the transparent conductive film of each example in which the hardness and elastic modulus of the electrode layer forming part and the electrode layer non-forming part are within a predetermined range, the non-visibility evaluation is good as 3 or 2. there were. On the other hand, in the comparative example in which either the hardness or the plastic deformation rate of the electrode layer forming part and the electrode layer non-forming part is out of the predetermined range, the non-visibility evaluation is 1, and the pattern of the transparent electrode layer is followed. Deformation (wrinkle) was confirmed. If the hardness is excessively large, the flexibility of the thin film is insufficient, so that the thin film cannot follow the shape change of the film substrate, causing distortion, which appears as wrinkles. On the other hand, when the hardness is excessively small, the plastic deformation rate is large, and it is considered that the shape distortion generated in the film substrate appears as the shape of the laminate as it is.

  From the comparison between Examples 1 and 2 and Comparative Example 1, the higher the oxygen partial pressure during the formation of the silicon oxide low refractive index layer immediately below the transparent electrode layer, the lower the hardness of the electrode layer non-formed part, and the plastic deformation There is a tendency for the rate to increase. Further, the same tendency was observed in the comparison between Examples 5 to 7 and Comparative Examples 5 and 6 and in the comparison between Example 8 and Comparative Examples 7 and 8, and the ratio of the film forming pressure to the oxygen partial pressure was changed. It can be seen that the hardness of the conductive layer non-formation part can be adjusted to an intended range by setting it within the predetermined range.

  From the comparison between Examples 1 and 3 and Comparative Examples 2 and 3, there is a tendency that the hardness of the conductive layer non-formation portion increases as the film thickness of the low refractive index layer increases. Further, from the comparison between Example 1 and Comparative Example 4, when the thickness of the transparent electrode layer increases, the hardness of the conductive layer forming portion tends to increase, and the hardness of the conductive layer forming portion is excessively large. It can be seen that even when the hardness and the plastic deformation rate of the conductive layer non-forming portion are within a predetermined range, the pattern is easily visually recognized.

  On the other hand, from the comparison between Example 1 and Example 4, even when the power density at the time of forming the low refractive index layer was changed, no clear change was observed in the hardness and the plastic deformation rate. From the above results, the conductive layer is not formed by adjusting the oxygen partial pressure ratio and the thickness of the dielectric layer (the low refractive index layer of silicon oxide in the above embodiment) formed mainly on the outermost surface. It can be seen that the hardness and plastic deformation rate of the part can be set within a desired range.

  The hardness and plastic deformation rate of the electrode layer forming part are affected by the hardness and plastic deformation rate of the electrode layer non-forming part. This is presumably because the physical properties of the dielectric layer formed immediately below the transparent electrode layer affect the hardness and plastic deformation rate of the electrode layer forming portion (transparent electrode layer surface). It can also be seen that the hardness and plastic deformation rate of the electrode layer forming portion can be set within a desired range by adjusting the hardness of the transparent electrode layer by increasing the film thickness of the transparent electrode layer or the like.

100 transparent laminate (transparent conductive film)
10 Transparent film substrate 21 First transparent thin film (transparent dielectric layer)
22 Second transparent thin film (transparent electrode layer)
31 2nd transparent thin film formation area (conductive part)
32 Second transparent thin film non-formation area (non-conductive part)

Claims (7)

A transparent laminate comprising, in this order, a first transparent thin film and a patterned second transparent thin film on one surface of the transparent film substrate,
The transparent laminate includes a second transparent thin film forming region in which a second transparent thin film is formed on the first transparent thin film, and a second transparent thin film non-forming region in which the second transparent thin film is not formed on the first transparent thin film. Have
The surface of the second transparent thin film non-forming region has a microhardness measured by microhardness measurement in the range of 2 to 12, and a plastic deformation rate of 50% or less,
The surface of said 2nd transparent thin film formation area is a transparent laminated body whose micro hardness measured by micro hardness measurement is in the range of 4-12, and a plastic deformation rate is 50% or less.   The transparent laminated body of Claim 1 whose sum total of the film thickness of the 1st transparent thin film in a said 2nd transparent thin film formation area and a 2nd transparent thin film is 60-100 nm.   The transparent laminated body of Claim 1 or 2 whose film thickness of the 2nd transparent thin film in said 2nd transparent thin film formation area is 10 nm-32 nm.   The transparent laminated body according to claim 1, wherein the first transparent thin film is a dielectric layer, and the second transparent thin film is a conductor layer.   The transparent laminated body of any one of Claims 1-4 in which said 1st transparent thin film consists of a thin film of two or more layers.   The transparent laminate according to any one of claims 1 to 5, wherein the first transparent thin film includes one or more layers containing silicon oxide as a main component.   The transparent laminate according to claim 6, wherein the first transparent thin film has a layer mainly composed of silicon oxide on a surface on the second transparent thin film side.

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