JPH11262968A - Transparent conductive film - Google Patents

Abstract

(57) [Problem] To provide a transparent conductive film having low resistance and excellent in moisture resistance and chemical resistance. In a transparent conductive film in which an oxide film, a metal film, and an oxide film are laminated in this order on a base, a (2n + 1) layer (n ≧ 1) is formed. At least one of the two interfaces far from the substrate is Ni and Zn.
A transparent conductive film in which the oxide films 3 and 5 containing the same are provided as part or all of the oxide films 2 and 6 forming the transparent conductive film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a transparent conductive film.

[0002]

2. Description of the Related Art A multi-layered Ag-based transparent conductive film in which an Ag layer is sandwiched between transparent oxide layers can easily obtain a lower resistance than an ITO film which is widely used at present, and therefore, such as a liquid crystal display (LCD). Is expected as a transparent electrode for display.
As the Ag-based transparent conductive film, 1) In ₂ O ₃ / Ag / In ₂ O ₃ sandwiching an Ag layer between In ₂ O ₃ layers, 2) ITO / Ag / ITO sandwiched between an ITO layer, and 3) Ga addition ZnO
GZO / Ag / GZO sandwiched between (GZO) layers are known. In ₂ O ₃ / Ag / In ₂ O ₃ or ITO / A
Although g / ITO is excellent in chemical resistance, it has insufficient moisture resistance to cause white defects when left indoors.
On the other hand, GZO / Ag / GZO has a defect that the moisture resistance is good but the chemical resistance is insufficient. For this reason,
Neither of the films has been put to practical use for LCD.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a transparent conductive film having a low resistance and being excellent in moisture resistance and chemical resistance which can be used for LCDs and the like.

[0004]

According to the present invention, there is provided a transparent conductive film in which an oxide film, a metal film, and an oxide film are laminated in this order on a substrate in (2n + 1) layers (n ≧ 1). An oxide film containing Ni and Zn (hereinafter, referred to as an NZ oxide film) is formed on at least one of the two interfaces formed by the film and the oxide film at an interface far from the substrate. A transparent conductive film provided as part or all is provided.
The NZ oxide film is a film mainly composed of a composite oxide film of Ni and Zn or a composite oxide film of Ni and Zn. Because better moisture resistance and chemical resistance can be obtained,
The NZ oxide film is preferably provided on both sides of two interfaces formed by the metal film and the oxide film.

FIG. 1 is a cross-sectional view of a typical example of a transparent conductive film using one metal film according to the present invention, and FIG. 2 is a cross-sectional view of a typical example of a transparent conductive film using two metal films according to the present invention. The figure is shown. 1
Is a substrate, 3, 5, 7, and 9 are NZ oxide films, 2, 6, 10
Is an oxide film, and 4 and 8 are metal films.

As the substrate 1 in the present invention, a glass plate, a resin film, a resin plate or the like can be used. In addition, a color filter layer serving as a color pixel is formed on a glass plate or the like, a color resin layer is protected on the color filter layer, a transparent resin layer for forming and smoothing the color filter is formed, and further on the transparent resin layer. A substrate obtained by sequentially laminating an inorganic intermediate film layer such as silica or SiN _x (a layer for improving adhesion to a transparent conductive film) may be used as the substrate.

The NZ oxide films 3, 5, 7, 9 are made of Ni and Z
Preferably, Ni is contained in an amount of 5 to 80 atomic% based on the total of n. If it is less than 5 atomic%, the chemical resistance is insufficient,
If it exceeds 80 atomic%, adhesion to a metal film (particularly, a film containing Ag as a main component, which will be described later) becomes insufficient, so that peeling easily occurs due to the influence of moisture.

It is preferable that the NZ oxide films 3, 5, 7, and 9 contain Ga in order to increase conductivity.
In particular, Ga is 2 to 15 with respect to the sum of Ni, Zn, and Ga.
It is preferable to contain atomic%.

The oxide films 2, 6, and 10 are preferably films having excellent chemical resistance. For example, In ₂ O ₃ , IT
Materials such as O, SnO ₂ , TiO ₂ and NZ oxide can be used. Each oxide film may have a multilayer structure in which two or more oxide films are stacked. When high conductivity is required, it is preferable to use a conductive film such as In ₂ O ₃ or ITO. More specifically, as an oxide film,
1) ITO film, 2) NZ oxide film / ITO film, 3) NZ
An oxide film or the like is used.

The thickness of each of the oxide films 2, 6, and 10 is preferably from 10 to 150 nm in total with the thickness of the NZ oxide film from the viewpoint of optical characteristics. 10
If it is less than 150 nm or more than 150 nm, the visible light transmittance decreases.

The thickness of the NZ oxide films 3, 5, 7, 9 is 1n
m or more is preferable. If the thickness is less than 1 nm, the adhesion to a metal film (particularly, a film containing Ag as a main component, which will be described later) becomes insufficient, so that the moisture resistance becomes poor.

In order to improve mechanical and chemical durability, the transparent conductive film of the present invention has a distance of (2n +
1) A protective layer or the like may be provided further outside the oxide film of the layer.

The oxide film in the present invention is preferably formed by a sputtering method in consideration of productivity. The oxide film is formed by sputtering in an Ar atmosphere using an oxide sintered body target or in an Ar atmosphere containing a small amount of an oxidizing gas, or by mixing an oxidizing gas and an Ar gas using a metal target. Although there is a method of sputtering in an atmosphere, the NZ oxide film is preferably formed by the former method. In the latter method, the specific resistance increases because the metal film is damaged. An oxide film other than the NZ oxide film may be formed by either method.
It is determined in consideration of target material cost, productivity, production stability, and the like. Note that in the case where any of the oxide films has a conductive target and can be formed by DC sputtering, it is preferable to form the film by DC sputtering from the viewpoint of productivity.

The metal films 4 and 8 are preferably films containing Ag as a main component, since low specific resistance and high visible light transmittance can be obtained. The film containing Ag as a main component may be a film consisting of Ag alone. However, since the stability of Ag is improved, P
An alloy film containing at least one metal selected from the group consisting of d, Au, Pt, Co and Cu is preferred.

One or more metals selected from the group consisting of Pd, Au, Pt, Co and Cu are preferably contained at a ratio of 0.1 to 10 atomic% with respect to the total amount of Ag. If it is less than 0.1 atomic%, the durability becomes insufficient, and
If it exceeds atomic%, the visible light transmittance is reduced and the specific resistance is increased.

The thickness of the metal films 4 and 8 is preferably 3 to 25 nm. If it is less than 3 nm, the sheet resistance becomes high,
If it exceeds m, the visible light transmittance decreases. The metal film is formed by sputtering in an Ar gas atmosphere using a metal target. Since the metal target has sufficient conductivity, film formation by DC sputtering is possible. A gas such as N ₂ may be added to the atmosphere for the purpose of adjusting the specific resistance and improving the mechanical durability.

After forming the transparent conductive film of the present invention, 100 to 3
The heat treatment may be performed at a temperature of 00 ° C. The heat treatment can be expected to reduce the resistance, increase the visible light transmittance, and improve the durability.

[0018]

[Action] Moisture resistance deterioration of Ag-based transparent conductive film (white spots generated)
The reason is that peeling occurs at the interface between the Ag film and the oxide film due to the influence of moisture, and the oxide film is damaged. By introducing an NZ oxide film having high adhesion to the Ag film at the interface between the Ag film and the oxide film, peeling can be prevented and moisture resistance can be improved.
In addition, since the NZ oxide film itself has high chemical resistance,
By using the NZ oxide film for part or all of the oxide film included in the transparent conductive film, the moisture resistance and chemical resistance of the obtained transparent conductive film can be improved.

[0019]

EXAMPLE A transparent conductive film having the structure shown in Examples 1 to 8 of Table 1 was formed on a glass substrate by a direct current sputtering method.
The numbers in parentheses in Table 1 are film thicknesses (nm). The left side is the substrate side. The In ₂ O ₃ film was formed by using an In ₂ O ₃ sintered target and using Ar gas containing 2% by volume of oxygen at 6 mTorr.
The film was formed by DC sputtering at a power density of 2.2 W / cm ² in the atmosphere described above.

The ITO film has a value of S with respect to the sum of Sn and In.
Using an In ₂ O ₃ sintered target containing 10 atomic% of n, a film was formed by direct current sputtering at a power density of 2.2 W / cm ^{2 in} an atmosphere of Ar gas containing 2 vol% oxygen and 6 mTorr. The composition of the ITO film after film formation was the same as the composition of the target used.

The NZ oxide film to which Ga ₂ O ₃ is added (hereinafter abbreviated as GNZ film) contains 15.7 atomic% of Ni with respect to the sum of Ni and Zn, and 2.2 W / c in an atmosphere of 6 mTorr of Ar gas using a ZnO sintered body target containing 4.3 atomic% of Ga
The film was formed by DC sputtering at a power density of m ² . The composition of the GNZ film after film formation was the same as the composition of the target used.

For the GZO film, a ZnO sintered target containing 5.0 atomic% of Ga with respect to the sum of Ga and Zn is used.
The film was formed by DC sputtering at a power density of 2.2 W / cm ^{2 in} an atmosphere of Ar gas at 6 mTorr. The composition of the GZO film after film formation was the same as the composition of the target used.

The AgPd film is made of Ag-P containing 1 atomic% of Pd.
The film was formed by DC sputtering at a power density of 0.55 W / cm ^{2 in} an atmosphere of Ar gas at 2 mTorr using a d alloy target. The composition of the AgPd film after film formation was the same as the composition of the target used. After the film formation, all the transparent conductive films were subjected to a heat treatment in an atmosphere at 250 ° C. for 30 minutes. Table 1 shows the measurement results of the sheet resistance and the evaluation results of the moisture resistance and the alkali resistance of the transparent conductive film of each configuration. The sheet resistance was measured by a four probe method.

Regarding the moisture resistance, after performing a moisture resistance test of leaving it in an atmosphere of 70 ° C. and 90% humidity for one week,
A sample in which white spots having a diameter of 0.5 mm or more did not occur was evaluated as ○, and a sample in which white spots having a diameter of 1 mm or more occurred was evaluated as x.

With respect to alkali resistance, 1% by weight at room temperature
After performing an alkali resistance test in which the film was immersed in an NaOH aqueous solution for 20 minutes, a sample in which no change was observed in the film was evaluated as ○, and a sample in which deterioration such as discoloration was observed was evaluated as ×.

From Table 1, it can be seen that the structure in which the In ₂ O ₃ film and the AgPd film are laminated (Examples 5 and 6) and the structure in which the ITO film and the AgPd film are laminated (Example 7) exhibit good alkali resistance. It can be seen that the moisture resistance was poor. GZ
In the configuration in which the O film and the AgPd film are laminated (Example 8), the moisture resistance is good, but the alkali resistance is poor. On the other hand, a film having a configuration in which a thin GNZ film is introduced between the In ₂ O ₃ film and the AgPd film according to the present invention (Examples 1 and 2), IT
A film having a configuration in which a thin GNZ film is introduced between an O film and an AgPd film (Example 3) and a film in which a GNZ film and an AgPd film are laminated (Example 4) have good moisture resistance and alkali resistance.

[0027]

[Table 1]

[0028]

According to the present invention, a low-resistance transparent conductive film having both moisture resistance and chemical resistance can be provided. In particular, 3
A transparent conductive film having a low resistance of Ω / □ or less can be easily produced.

The transparent conductive film of the present invention is suitable not only for transparent electrodes for liquid crystal displays, electrochromic displays, electroluminescent displays, and plasma displays, but also for heat ray blocking films, electromagnetic wave shielding films, and transparent heating elements for anti-fog glass. It is.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a typical example of a transparent conductive film using one metal film according to the present invention.

FIG. 2 is a cross-sectional view of a representative example of a transparent conductive film using two metal films according to the present invention.

[Explanation of symbols]

 1: Base 2, 6, 10: oxide film 3, 5, 7, 9: oxide film containing Ni and Zn 4, 8: metal film

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuki Aoshima 1150 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa-ken Asahi Glass Co., Ltd.

Claims (5)

[Claims] In a transparent conductive film in which an oxide film, a metal film, and an oxide film are laminated in this order on a substrate in a (2n + 1) layer (n ≧ 1), the upper and lower interfaces of the metal film are formed. A transparent conductive film in which an oxide film containing Ni and Zn is provided as a part or all of an oxide film forming a transparent conductive film at least at an interface far from the base. 2. An oxide film containing Ni and Zn is made of Ni
2. The transparent conductive film according to claim 1, wherein the transparent conductive film contains 5 to 80 atomic% of Ni with respect to the total of Zn and Zn. 3. An oxide film containing Ni and Zn is Ga
The transparent conductive film according to claim 1, comprising: 4. The transparent conductive film according to claim 1, wherein the metal film is a film containing Ag as a main component. 5. A film comprising Ag as a main component is composed of Pd, Au, P
The transparent conductive film according to claim 4, wherein the transparent conductive film is an alloy film containing at least one metal selected from the group consisting of t, Co, and Cu.