JPH1170610A - Transparent conductive film and formation of transparent electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance not only low specific resistance and durability but also minuscule electrode processability by adding ZnO to a transparent oxide layer to obtain an oxide layer containing In within a specific value range with respect to the sum total of Zn and In and forming a metal layer as an Ag-containing metal layer. SOLUTION: As a substrate 1, a glass plate, a resin film or the like is used. Transparent oxide layers 2, 4, 6 are oxide layers containing ZnO and containing In within a 9-98 atomic % range with respect to the sum total of Zn and In and enhanced in the durability against an alkali soln. or an acidic soln. Subsequently, since metal layers 3, 5 contain Ag and the transparent oxide layers contain ZnO, the crystallization of Ag is accelerated even under a low temp. film forming condition of 150 deg.C or lower and the lowering of the specific resistance of the Ag-containing metal layers and the reduction of the flocculation of Ag are prevented. By this constitution, low specific resistance can be easily realized and durability such as alkali resistance, humidity resistance or the like can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a transparent conductive film used for a liquid crystal display (LCD) and the like, and a method for forming a transparent electrode.

[0002]

At present, a mixed oxide of In and Sn as an electrode for LCD (hereinafter referred to as InSn _x O _y) has films are widely used. In particular, with STN-type color LCDs, as the definition and size of the screen increase, the line width of the liquid crystal drive transparent electrode is required to be narrower and longer. Therefore, an extremely low-resistance transparent conductive film having a sheet resistance of 3Ω / □ or less is required. To achieve this sheet resistance, the thickness of the transparent conductive film must be increased (300
nm or less) or low specific resistance (100 μΩ · cm or less)
Need to be measured.

[0003] However, increasing the film thickness involves 1) increasing the cost of forming a transparent conductive film, 2) increasing the difficulty of electrode patterning, and 3) increasing the level difference due to the presence or absence of a transparent electrode. There is a limit due to problems such as difficulty in controlling the orientation. On the other hand, a method of low specific resistance of the InSn _x O _y film itself has been studied, 100μΩ · c
How to stably produce the following resistance InSn _x O _y film m is not yet established.

On the other hand, as a method for easily obtaining a low-resistance transparent conductive film having a resistance of 100 μΩ · cm or less, an Ag layer is formed of InSn _x
Sandwiched between O _y layer _{InSn x O y / Ag / InSn} x O y
Is known. However, although this configuration also has a low specific resistance, its durability is insufficient enough to cause white defects which are considered to be film peeling when left indoors. Also, during electrode processing by etching using an acidic aqueous solution,
The processability is insufficient, such as side etching progressing and peeling off at the pattern edge.

[0005] _{Therefore, InSn x O y / Ag /} InS
substrate n _x O _y configuration while having the advantage of low resistance can be easily obtained, it has been put to practical use so far as the transparent conductive substrate for LCD.

[0006]

SUMMARY OF THE INVENTION The present invention provides a transparent conductive film having low specific resistance, excellent durability and excellent fine electrode processing performance, and a method for forming a transparent electrode, which are used for LCDs and the like. Aim.

[0007]

According to the present invention, a transparent oxide layer and a metal layer are formed on a substrate in this order from the substrate side (2n +
1) In a transparent conductive film formed by stacking layers (n is an integer of 1 or more), the transparent oxide layer contains ZnO and
Is an oxide layer containing 9 to 98 atomic% of the total of Zn and In, and the metal layer is a metal layer containing Ag. .

FIG. 1A is a cross-sectional view of the transparent conductive film of the present invention when n = 1, and FIG. 1B is a cross-sectional view of the transparent conductive film when n = 2. 1
Is a substrate, 2, 4, and 6 are transparent oxide layers, and 3, 5 are metal layers containing Ag. The transparent oxide layers 2, 4, and 6 are made of Zn.
The oxide layer contains O and contains 9 to 98 atomic% of In with respect to the total of Zn and In. In
Is particularly preferably 45 to 95 atomic%.

The present invention, since the transparent oxide layer comprises ZnO, in comparison with the case of using the conventional InSn _x O _y film, even in low-temperature film-forming conditions of 0.99 ° C. or less, the crystallization of Ag Not only to lower the resistance of the Ag-containing metal layer (hereinafter referred to as Ag layer) and prevent the Ag aggregation phenomenon, but also to improve the adhesion at the interface between the ZnO-containing oxide layer and the Ag layer. As a result, the moisture resistance and the processability of the fine electrode pattern with an acidic aqueous solution (hereinafter referred to as patterning property) are significantly improved.

In this case, it is preferable that the Ag layer and the layer rich in the ZnO component are in contact with each other. In particular, in an oxide layer which is in contact with the Ag layer, a portion which is in contact with the Ag layer preferably contains Zn in an amount of 50 atomic% or more based on the total amount of Zn and In. In this case, Zn is 100 atomic%, that is, the portion in contact with the Ag layer is Zn not containing In.
It may be O. The thickness of the part in contact with the Ag layer is
It is preferably at least 1 nm, particularly preferably at least 5 nm.

Further, since the oxide layer contains In in the range of 9 to 98 atomic% with respect to the total amount of Zn and In,
In addition to the above-mentioned excellent characteristics of ZnO, durability against an alkali solution or an acidic solution is improved.

As the substrate 1 in the present invention, a glass plate, a resin film or the like is used. Further, a substrate as shown in FIG. 2 is also used. FIG. 2 shows a substrate for a color LCD corresponding to the base 1 of FIG. Reference numeral 39 denotes a glass substrate, 7 denotes a color filter layer serving as a color pixel, 8 denotes a transparent resin protective layer, and 9 denotes an inorganic intermediate layer. Transparent resin protective layer 8
Protects and smoothes the color filter layer. The inorganic intermediate layer 9 is for improving the adhesion between the transparent resin protective layer 8 and the transparent conductive film, and is made of silica, SiN _x or the like.

At least one of the transparent oxide layers comprises 1) I
a layer made of a mixed oxide of n ₂ O ₃ and ZnO, or
2) As shown in FIG. 3, a film 1 containing In ₂ O ₃ as a main component.
This is a layer composed of a multilayer film of 0 and a film 11 containing ZnO as a main component. Practically, it is desirable that all the transparent oxide layers are unified with either type 1) or 2).

When the transparent oxide layer is a multilayer film, the transparent oxide layer 2 has a total thickness of 10 to 200 nm, and the total thickness of the film 10 containing In ₂ O ₃ as a main component. It is preferable that the total thickness ratio be 5 to 95%. The same applies to the transparent oxide layers 4 and 6. By adopting such a configuration, moisture resistance and patterning properties are not impaired,
The alkali resistance is improved. In particular, it is preferably from 45 to 95%. In this specification, “film thickness” means a geometric film thickness.

As the transparent oxide layer 6 farthest from the substrate, a) a multilayer film composed of a film mainly composed of In ₂ O ₃ and a film mainly composed of ZnO as shown in FIG. A layer comprising a multilayer film in which films are stacked such that the content of In (the ratio of In to the sum of Zn and In) increases as the film moves away from the substrate, or b. 4) In ₂ O ₃ and ZnO as shown in FIG.
And a layer having a gradient composition in which the In content increases in the thickness direction as the distance from the substrate increases. FIG.
(B) shows how the In content of the transparent oxide layer 6 increases in a direction away from the substrate.

In FIG. 4, reference numeral 12 denotes a film having a lower In content than the oxide film 13, and 13 denotes a film having a lower I content than the oxide film 12.
A film having a high n content, and 14 has an In content of 50 atomic%.
The portion less than 40 is a portion where the In content is 50 atomic% or more. By adopting the configuration of a) or b), corrosion and durability against an alkaline solution or an acidic solution are excellent.

In the case of a), as an example, a film mainly composed of ZnO and a film mainly composed of In ₂ O ₃ are laminated in this order from the substrate side, and the further away from the substrate, the farther from the substrate.
The thickness ratio of the film mainly composed of In ₂ O ₃ to the film thickness mainly composed of ZnO is increased, and the uppermost layer is made of In ₂ O _3.
What is necessary is just to make it into the film | membrane which contains as a main component.

In the case of b), as an example, a target mainly composed of ZnO and a target mainly composed of In ₂ O ₃ are simultaneously sputtered, and the composition ratio of In ₂ O _{3 in} a direction away from the substrate is increased. It can be realized by changing the sputtering power of each target so as to increase. Further, several mixed oxide targets having different composition ratios of ZnO and In ₂ O ₃ are mixed in the order such that the composition ratio of In ₂ O ₃ increases in a direction away from the substrate,
It can also be realized by sequential sputtering.

As the transparent oxide layer 2 closest to the substrate, c) a multilayer film composed of a film mainly composed of In ₂ O ₃ and a film mainly composed of ZnO as shown in FIG. A layer that is a multilayer film in which films are stacked so that the content of In increases as the film moves closer to the base, or d) In as shown in FIG. The mixed oxide layer of ₂ O ₃ and ZnO is preferably a layer having a gradient composition in which the In content increases in the thickness direction as it approaches the substrate. FIG.
(D) shows how the In content of the transparent oxide layer 2 increases in the direction approaching the substrate. By adopting the configuration of c) or d), the adhesive force upon contact with an alkali solution or an acidic solution is remarkably improved.

In the cases of a) to d), the thickness of the transparent oxide layer is 1 from the viewpoint of color tone and visible light transmittance.
0-200 nm is preferred. Further, in the configurations a) to d), the total film thickness of the portion where the thickness ratio of the film mainly composed of In ₂ O ₃ on the film to the film thickness mainly composed of ZnO is 1 or more. Thickness (for example, a) ZnO (7 nm) / b) In ₂ O ₃ (3 nm)
/ C) ZnO (5 nm) / d) In ₂ O ₃ (5 nm) /
e) When ZnO (3 nm) / f) In ₂ O ₃ (20 nm), the total film thickness of c) to f)) or the film thickness of the portion where the In content exceeds 50 atomic% is determined by the patterning property. From the viewpoint of alkali resistance, the thickness is preferably 5 to 50 nm. If the thickness is less than 5 nm, the alkali resistance is not excellent, and if it exceeds 50 nm, the patterning property is reduced.

In particular, in the configuration of a) or b), the lower layer portion 12 or 14 of the transparent oxide layer 6 farthest from the substrate has an In content of 50 to 90 atomic%, and the upper layer portion 13 or 40 has an In content of In. Is preferably 90 atomic% or more and the thickness of the upper layer portion 13 or 40 is 5 to 50 nm from the viewpoint of alkali resistance and patterning properties.

In the present invention, when a film containing ZnO as a main component is formed, the film preferably contains Ga. Specifically, ZnO containing Ga is preferable. When a trivalent dopant such as Al is added to ZnO, which is an insulator, conductivity is exhibited, but the addition of Ga exhibits the best conductivity and visible light transmittance.

Further, when DC sputtering with high productivity is assumed as a ZnO film forming method, Zn metal can be used as a target, but there is a disadvantage that a margin of film forming conditions is narrow. By adding Ga to Zn, direct-current sputtering from a ZnO target becomes possible, and the margin of the film forming conditions becomes extremely wide.

The content ratio of Ga is preferably 1 to 15 atomic% with respect to the sum of Zn and Ga. If the amount is less than 1% by atom, the film forming rate is low, and if the doping amount is more than 15% by atom, the visible light transmittance is low.

In the present invention, at least one of the metal layers includes 1)
A layer composed of an alloy film of Ag and another metal, 2) a multi-layered layer composed of an Ag layer and another metal layer, or 3) a layer composed of Ag and another metal, and Ag in the thickness direction of the layer. It is preferable that the layer has a gradient composition in which the concentration changes.

In the case of the above 2), for example, another metal layer is
It is also preferable to configure so as to be interposed at the interface with the transparent oxide layer. In this case, there are multiple interfaces, but at least one
It is configured to intervene at two interfaces.

As described above, the metal layer is composed of 1) an alloy layer,
2) a multilayer composition layer or 3) a gradient composition film,
It is possible to improve the decrease in moisture resistance due to the aggregation phenomenon of Ag without impairing low resistance and high transparency and high transparency.

In any of the above cases 1) to 3), the thickness of each metal layer (corresponding to 3 and 5 in FIGS. 5 and 6) is
It is preferably from 3 to 20 nm. If it is less than 3 nm, the sheet resistance increases, and if it exceeds 20 nm, the visible light transmittance decreases.

As other metals, P is preferred because it can satisfy the reduction in resistance, the improvement in transmittance, and the improvement in durability.
d, Au, Cu, Zn, Sn, Ti, Zr, V, Ni,
One or more metals selected from the group consisting of Cr, Pt, Rh, Ir, W, Mo, and Al are preferred. In particular, the other metal is preferably Au and / or Pd. By adding Au or Pd, the aggregation phenomenon of Ag is prevented, and a highly durable Ag film is obtained.

The structure of the above metal layers 1) to 3) will be specifically described using Pd as another metal. As the configuration 1), a layer made of an alloy film of Ag and Pd (referred to as a PdAg alloy layer) is used. In the PdAg alloy layer, Pd is uniformly present in Ag. in this case,
The content ratio of Pd in the PdAg alloy layer is preferably 0.1 to 5.0 atomic% with respect to the total of Ag and Pd. If the content is less than 0.1 atomic%, the durability becomes insufficient, and
If it exceeds 0 atomic%, the visible light transmittance decreases and the resistance increases.

In the structure 2), Pd layers (intervening layers) 15 and 17 are interposed between the transparent oxide layers 2 and 4 and the Ag layer 16 as shown in FIG. In this case, the thickness range of the intervening layers 15 and 17 is 0.1 to 3 nm.
Is preferred. By interposing with this thickness, the same effect as the effect of adding Pd in 1) can be obtained. If the thickness of the intervening layer is less than 0.1 nm, the durability will be insufficient, and if it exceeds 3 nm, the visible light transmittance will decrease. In particular, 0.1 to 1 nm is preferable. Further, as the configuration of the above 2), as shown in FIG. 6A, a multilayer configuration of an Ag layer 22 and a Pd layer 21 may be adopted. In this case, the thickness of each Pd layer 21 is set to 0.1 to 3 n.
m, the thickness of each Ag layer 22 is preferably 1 to 20 nm.

As the structure of the above 3), as shown in FIG. 5B or FIG. 6B, a layer having a gradient composition in which the Ag concentration changes in the thickness direction of the layer is used. In this case, P
As shown in FIG. 6B, the Pd-rich layers 18 and 20 having a high d-concentration and the Ag-rich layers 19 and
A multi-layer configuration of the d-rich layers 18, 20, 23, 24 and the like are used.

As shown in FIG. 5B, the Pd-rich layers 18, 20, 23 and 24 are layers in which Pd is at least 50 atomic% with respect to the sum of Ag and Pd. Pd
When the thickness of the rich layer is 0.1 nm, the durability is insufficient, and when it exceeds 3 nm, the visible light transmittance tends to decrease. Therefore, the thickness of 0.1 to 3 nm is appropriate.

By selecting the thickness of each layer constituting the transparent conductive film within the above-described range, it is possible to adjust the transmittance, the color tone, and the sheet resistance by the optical interference effect. Specific examples of the structure of the transparent conductive film formed by stacking (2n + 1) layers (n is an integer of 1 or more) of the present invention include a)
Substrate / transparent oxide layer (5 to 30 nm) / metal layer (5 to 2
0 nm) / transparent oxide layer (30-50 nm), b) transparent oxide layer (30-50 nm) / metal layer (5-20 nm)
/ Transparent oxide layer (80-120 nm) / metal layer (5-2)
0 nm) / transparent oxide layer (30-50 nm).

The transparent conductive film of the present invention exhibits low sheet resistance, high visible light transmittance, and high durability. However, in order to further improve the characteristics, the film may be subjected to a heat treatment at 100 to 300 ° C. after film formation. Good. This heat treatment promotes crystallization and stabilization of the oxide layer and the Ag layer, so that lower resistance and higher visible light transmittance are obtained, and heat resistance is also improved.

Since the transparent conductive film of the present invention can easily obtain a low resistance of 3 Ω / □ or less, it requires a low resistance such as an LCD, an electroluminescence display, a plasma display, or an electrochromic element. As a transparent electrode film for electronic displays. In particular, in a simple matrix type LCD, by using the transparent conductive film of the present invention, an excellent effect of improving display quality such as enlargement of a display area and reduction of crosstalk is exhibited.

The present invention also provides a method for forming a transparent electrode, in which the transparent conductive film is formed on a substrate and then patterned by etching using an acidic aqueous solution having a hydrogen ion concentration of 0.01 to 9 M. . By using the method for forming a transparent electrode of the present invention, a side etching amount of 5
Patterning of μm or less is possible, and it is suitable as a transparent electrode of a transparent conductive substrate for various displays such as LCDs requiring fine dimensional accuracy.

As a first patterning method, after a desired resist pattern is formed on a transparent conductive film as shown in FIG. 1 by a photolithography method, an acidic aqueous solution having a hydrogen ion concentration of 0.01 to 9 M (mol / liter) is formed. The patterning is performed by performing etching using a mask. Also in the hydrogen ion concentration range, a concentration range in which the side etching amount is 5 μm or less is preferable. In an acidic aqueous solution having a hydrogen ion concentration of less than 0.01 M, etching hardly progresses, and in an acidic aqueous solution having a hydrogen ion concentration of more than 9 M, the etching rate is increased and it becomes difficult to control, and the side etching amount greatly increases beyond 5 μm. Would.

Examples of the acidic aqueous solution include hydrochloric acid, hydrobromic acid,
An aqueous solution mainly containing hydroiodic acid, nitric acid, sulfuric acid, and ferric chloride is exemplified. In particular, an acidic aqueous solution containing hydrochloric acid or hydrobromic acid as a main component is preferable because the etching rate is high and the side etching is low.

Further, from the viewpoint that the Ag layer can be efficiently etched, it is preferable to add an oxidizing agent having a higher oxidation-reduction potential (having an oxidizing effect on Ag) than Ag to the above-mentioned acidic aqueous solution. By adding the oxidizing agent, the dissolution rate of Ag can be increased, and better patterning properties can be obtained. The addition of the oxidizing agent is also effective in dissolving indium oxide efficiently. Examples of the oxidizing agent include nitrous acid, hydrogen peroxide, potassium permanganate, potassium iodate, ceric ammonium nitrate, and ferric chloride. In particular, ferric chloride is preferred.

In this case, an oxidizing agent is added to the acidic aqueous solution,
It is preferable that the hydrogen ion concentration be 0.01 to 9M and the oxidizing agent concentration be 0.0001 to 1.5M. When the concentration is out of this range, the etching of the Ag layer becomes difficult to proceed, resulting in an etching residue or an increase in the side etching amount exceeding 5 μm. Alternatively, the etching rate becomes high and control becomes difficult.

In particular, because an easily controllable etching rate is obtained and side etching is small,
An acidic aqueous solution containing ferric chloride and hydrochloric acid or ferric chloride and hydrobromic acid as main components is preferable. Specifically, ferric chloride is used in an amount of 0.01 to 4 μm because a very good patterning property of 2 to 4 μm is obtained.
Hydrochloric acid has a hydrogen ion concentration of 0.1 to 5
M or the combination of ferric chloride is 0.0005 to
Hydrobromic acid has a hydrogen ion concentration of 3 to 9 with respect to 0.5M.
Preferred examples include a combination of M and the like.

It is preferable to appropriately optimize the concentrations of the acid and the oxidizing agent according to the respective film constitutions. However, as the oxide layer, a zinc oxide-rich oxide as shown in Examples 4, 6, and 19 is used. When an object is used, good patterning can be achieved only with an acid. On the other hand, when patterning a film using an indium oxide-rich oxide that is difficult to dissolve only with an acid, it is preferable to add an oxidizing agent within the above range because the indium oxide is easily dissolved.

In the present invention, it is preferable to use an acidic aqueous solution containing a halogen ion as the acidic aqueous solution, to perform etching, and then to immerse the substrate in an aqueous solution of an alkali metal halide or an aqueous solution of sodium thiosulfate. By such processing, the etching residue 25 as shown in FIG.
Can be effectively removed.

This is because when an etching residue such as a reaction product at the time of etching is immersed in a solution containing an excess of halogen ions, the dissolution equilibrium is broken, and the etching residue is rapidly dissolved in an aqueous solution of an alkali metal halide salt. It seems to be because. Also, it seems that when immersed in an aqueous solution of sodium thiosulfate, etching residues such as silver halide are rapidly dissolved.

Examples of the acidic aqueous solution containing a halogen ion include HCl, HBr, HI, and an aqueous solution of ferric chloride. Examples of the alkali metal halide include NaC
1, KCl, NaBr and the like. The concentration of the alkali metal halide is preferably 0.5 M or more from the viewpoint of reliably removing the etching residue. Further, the concentration of sodium thiosulfate is preferably 0.1 to 3M.

As a second patterning method in the present invention, as shown in FIG. 8, a desired pattern is formed on a substrate using a resist soluble in an alkali solution or an organic solvent, and then the transparent conductive film is formed. Form a film, then
A method in which unnecessary portions of the transparent conductive film are removed together with the resist using an alkali solution or an organic solvent.

Examples of the resist 26 soluble in an alkali solution or an organic solvent include a resist obtained by dissolving a novolak resin containing a photosensitive material in an organic solvent such as ethylene glycol monoethyl ether monoacetate. As the alkaline solution of the stripping solution, an alkaline aqueous solution containing 0.5 to 3% by weight of NaOH with respect to the solution, an alkaline aqueous solution containing 2 to 3% by weight of tetramethylammonium hydroxide with respect to the solution, or o- An organic alkali solution composed of dichlorobenzene, phenol, and alkylbenzene sulfonic acid is exemplified.

Examples of the organic solvent for the stripping solution include organic solvents such as isopropanol, dimethyl sulfoxide, ethylene glycol, and trichloroethylene. Both the resist and the stripper are not particularly limited as long as they do not damage the transparent conductive film or the substrate. As a method for forming the transparent conductive film after the formation of the resist pattern, it is preferable to form the film at a substrate temperature of 150 ° C. or lower in order to avoid thermal damage to the resist.

The first patterning method described above is characterized in that an arbitrary electrode pattern after film formation can be formed;
There is no deterioration in film characteristics due to outgassing from the resist during film formation. On the other hand, the second patterning method does not require complicated etching solution composition and optimization of etching conditions, and has little etching residue such as a reaction product with an acid, so that high patterning accuracy and a good pattern shape can be obtained. Has features.

The method for forming a transparent conductive film and a transparent electrode of the present invention can be applied to a thin film transistor (TFT) type LCD as shown in FIG. In FIG. 9, 27 is a gate electrode, 28 is a gate insulating film, 29 is a semiconductor layer, 30 is a pixel electrode, 31 is a drain electrode, 32 is a source electrode, 33 is a pixel electrode integrated drain electrode, and 34 is a source electrode. .

The present invention relates to a source electrode of a TFT type LCD,
Provided is a substrate with an electrode wiring for an LCD, wherein a drain electrode and a pixel electrode are formed of the transparent conductive film. The present invention also provides, after forming a gate electrode, a gate insulating film and a semiconductor layer on a substrate, forming the transparent conductive film,
Next, there is provided a method for forming a substrate with electrode wiring for an LCD, wherein a drain electrode integrated with a source electrode and a pixel electrode is formed by etching the transparent conductive film.

By using the transparent conductive film as the source electrode 32, the drain electrode 31, and the pixel electrode 30, it is possible to form a source, a drain, and a pixel electrode at one time and to collectively pattern them. Exhibits an excellent effect on reduction of

[0054]

EXAMPLE As shown in FIG. 2, a glass substrate 39, a color filter layer 7, an acrylic transparent resin protective layer 8 for protecting and smoothing a color filter, and an inorganic intermediate layer 9 made of a silica film were previously prepared. On the formed base 1,
Examples 1 to 18 (all examples) and Example 19 in Tables 1 and 2
To 20 (all comparative examples) were formed by DC sputtering.

When a film containing In ₂ O ₃ as a main component is formed, In ₂ O ₃ containing 10 atomic% of Sn (“Sn
(In ₂ O ₃ containing atomic%) is hereinafter referred to as “ITO”).
The film was formed in an atmosphere of mTorr. When forming a film containing ZnO as a main component, ZnO containing 5 atomic% of Ga (“G
A film target was formed in an atmosphere of Ar gas at 3 mTorr using a sintered body target of “ZnO containing 5 at% a” (hereinafter referred to as “GZO”).

When the oxide layer has a multilayer structure, the IT
An O layer and a GZO layer were alternately stacked, and a GZO layer was arranged at a portion in contact with the Ag layer, and an ITO layer was arranged at the uppermost portion of the uppermost oxide layer.

When a mixed oxide is formed, the atomic ratio of In to Zn is 4: 6 (in the table, described as mixture 1), 8: 2 (in the table, described as mixture 2), and 9: 1 (table). In the following, a mixture target of various mixed oxides described as mixture 3) is used.
The film was formed in an atmosphere of 3 mTorr of Ar gas containing 3% by volume of oxygen. The multilayer 1 in the table has an ITO film thickness of about 3
and the thickness of GZO is about 7 nm.
Was about 7 nm, and the thickness of GZO was about 3 nm. For both the multilayer 1 and the multilayer 2, a) between the base and the metal layer, the base / ITO / GZO /... / ITO / GZO /
A) a metal layer / GZ between the metal layer and the metal layer;
O / ITO /.../ ITO / GZO / metal layer, c) On the outermost metal layer, a metal layer / GZO / ITO ... GZ
The layers were alternately laminated so as to be O / ITO.

The metal layer is made of Pd, Au, Ag, an Ag alloy containing 1 atomic% of Pd (1% PdAg), or 1 atomic%.
The film was formed in an atmosphere of Ar gas at 3 mTorr using various targets of an Ag alloy containing Au (1% AuAg).
The thickness of each film was adjusted by the sputtering power and the film formation time. Pd rich layer and Ag in the table
The rich layer is formed by simultaneously sputtering a Pd target and an Ag target so that the Pd composition ratio increases at the interface with the oxide layer (50% or more) and the Ag composition ratio increases at the center of the metal film (50%). %), And the sputtering power of each target was changed so that the thickness of the Pd-rich layer was about 1 nm.

After the film formation, the film is formed at 250 ° C. × 30 in the air.
The case where the heat treatment was performed for 1 minute was indicated as “present”, and the case where the heat treatment was not performed was indicated as “absent”. The number in parentheses in the table is the film thickness (nm).

The samples shown in Examples 1 to 20 of Tables 1 and 2 were evaluated for 1) resistance, 2) visible light transmittance, 3) patterning property, 4) moisture resistance, and 5) alkali resistance. Table 3 shows evaluation methods for 3) patterning properties, 4) moisture resistance, and 5) alkali resistance.

For patterning, a resist was applied on each of the transparent conductive films shown in Tables 1 and 2, and the line width was 130 μm and the space width was 20 μm by photolithography.
After forming a stripe-shaped resist pattern of m, the etching was performed using the following etchant. That is, Example 4,
For 6 and 19, using an etching solution of ferric chloride serving also as an acidic aqueous solution and an oxidizing agent, for each, after determining the optimal concentration from the range of 0.01 to 6M hydrogen ion concentration, and For the other examples, an etching solution comprising hydrochloric acid (acidic aqueous solution) and ferric chloride (oxidizing agent) was used, and the hydrogen ion concentration was 0.1 to 5 M and the oxidizing agent concentration was 0.1 M for each. 01-1.5M
The determination was made after determining the optimum composition concentration from the range. The results are as shown in Tables 1 and 2.

Next, in order to examine the effective composition range of the etching solution in detail, the transparent conductive film was patterned using etching solutions of various compositions. That is, after forming a resist pattern on the transparent conductive film of Example 1 in the same manner as described above,
Patterning properties were evaluated using etching solutions having various compositions shown in Table 4. The results are as shown in Table 4. When the same patterning property evaluation was performed with respect to Examples 2 to 18 using etching solutions of various compositions, the same results as in Example 1 were obtained. Further, Example 4 was carried out using etching solutions having various concentrations shown in Table 5. The results are as shown in Table 5. When the same patterning property evaluation using etching solutions of various compositions was performed on Examples 6 and 19, the same results as in Example 4 were obtained. On the other hand, Example 2
Regarding 0, patterning was attempted with etching solutions of various compositions shown in Tables 4 and 5, but in any case, good patterning properties were not obtained.

The concentrations in Table 5 indicate the hydrogen ion concentration. In Tables 4 and 5, ◎ indicates that the side etching amount was 4 μm or less, and ○ indicates that the side etching amount was more than 4 μm and 5 μm.
Hereinafter, x means that the side etching amount exceeds 5 μm.

As shown in Tables 4 and 5, in the composition of the etchant, in a region having a concentration lower than the optimum acid concentration, the etching rate decreases and the side etching amount also increases.
In a region having a concentration higher than the optimum acid concentration, the etching rate becomes unnecessarily high and the side etching amount also increases. Regarding the oxidizing agent, in a region having a concentration lower than the optimum oxidizing agent concentration, the dissolution of the Ag layer is difficult to proceed, and the amount of side etching also increases. There was a tendency to increase.

In particular, after etching using an acidic aqueous solution containing ferric chloride, the effects of removing etching residues were compared between those immersed in an aqueous solution of 5M alkali metal halide and those not immersed. Good results were obtained when immersed in an aqueous solution of an alkali metal halide salt. Similarly, after etching, good results were obtained when immersed in a 1 M aqueous solution of sodium thiosulfate instead of the aqueous solution of the alkali metal halide.

Tables 1 and 2 show various properties of the transparent conductive film of the present invention. Transparent oxide and A shown in Examples 1 to 14 and 19 to 20
In a three-layer film configuration with the g layer, a transparent conductive film having a resistance of 3 to 4 Ω / □ and a visible light transmittance of 74 to 76% was obtained.
In the five-layer film configuration shown in FIG.
A transparent conductive film having a visible light transmittance of about 73% was obtained. In addition, the direction of visible light transmittance can be improved by heat treatment after film formation,
Low resistance was achieved.

When the transparent conductive films shown in Examples 1 to 19 were used, they had sharp pattern edge shapes, hardly any etching residue, and had a side etching amount of 2 to 2.
A good patterning property of about 4 μm was obtained. With respect to moisture resistance, no bright spots (defects) having a diameter of 0.5 mm or more were observed, and good performance was obtained.

The alkali resistance of the structure using the oxide film containing no In ₂ O ₃ shown in Example 19 is not always sufficient. The alkali resistance improves as the mixing ratio of In ₂ O _{3 to} ZnO increases, or as the ratio of the thickness of the ITO layer to the GZO layer increases. However, when the composition ratio of In ₂ O ₃ exceeds 98 atomic%, or when the ratio of the thickness of the ITO layer exceeds 95%, the patterning property and the moisture resistance deteriorate.

As shown in Examples 7, 8, 14, 16, 17, and 18, by making the uppermost layer of the uppermost oxide layer a layer containing a large amount of In ₂ O ₃ , the effect of alkali attack from the film surface can be reduced. Can be prevented. However, when the film thickness exceeds 50 nm, the patterning property decreases.

As shown in Examples 11 to 15, the visible light transmittance was improved by forming the metal layer into a multilayer structure or a gradient composition structure.
Low resistance can be achieved. On the other hand, a film having a configuration in which a film containing Ag as a main component and sandwiched between ITO films as shown in Example 20 is excellent in alkali resistance, but has a severe peeling at the interface between the metal film and the ITO film, and thus has a desired electrode pattern. Was not obtained, and in the moisture resistance test, many bright spots (defects) having a diameter of 1 mm or more were generated, and good results were not obtained.

Next, as a second patterning method, a color filter layer 7, an acrylic transparent resin protective layer 8 for protecting and smoothing the color filter, and an inorganic intermediate layer made of silica are formed on a glass substrate 39. After a photoresist made of a novolak resin is applied to the substrate 1 on which the substrate 9 has been formed in advance, a stripe pattern 26 having a line width of 130 μm and a space width of 20 μm is formed by ordinary photolithography (see FIG. )),
Transparent conductive films having the structures shown in Examples 1 to 18 were formed by DC sputtering. No substrate heating was performed (FIG. 8).
(B)). Then, while applying ultrasonic vibration, NaOH
Unnecessary portions of the transparent conductive film were stripped together with the resist using the aqueous solution of (2) to form a desired electrode pattern (FIG. 8).
(C)).

As a result, in any case, no residue of the transparent conductive film was observed in the space portion, the edge shape was very sharp, and the dimensional accuracy of the pattern width was 1 to 10.
Good ones of about 2 μm were obtained.

Further, a transparent conductive film having the structure shown in Examples 1 to 18 was formed on a glass substrate by DC sputtering without heating the substrate. Some of the films were subjected to a heat treatment at 250 ° C. for 30 minutes in the air after the film formation. After that, a resist is applied, and a TFT as shown in FIG.
Source 34 for type LCD, a drain 33, and a pixel electrode (InSn _x O _y) 33 to form a resist pattern that imitates.

Further, using a dry etching apparatus as shown in FIG. 10, an attempt was made to form an electrode pattern using HI (hydrogen iodide) and Ar gas. As a result, the pattern edge shape was sharp, no etching residue, etc. were seen,
TFT type LCD with side etching amount of 1-2μm
Satisfactory results were obtained for the source, drain, and pixel electrode. In FIG. 10, 35 is an RF power source,
36 is a cathode electrode, 37 is a sample, and 38 is an anode electrode.

[0075]

[Table 1]

[0076]

[Table 2]

[0077]

[Table 3]

[0078]

[Table 4]

[0079]

[Table 5]

[0080]

According to the present invention, when the total thickness of the transparent conductive film is 300 nm or less, a low specific resistance of a sheet resistance value of 3 Ω / □ or less can be easily realized, and durability such as alkali resistance and moisture resistance can be easily achieved. It is possible to provide a transparent conductive film having excellent properties.

Further, according to the electrode forming method of the present invention, it is possible to perform inexpensive and accurate electrode processing.

The transparent conductive film of the present invention can be used in addition to glass.
Because it can be formed on plastics with low film formation temperature (100 ° C or less) and on substrates with color filters for color LCDs (250 ° C or less),
It is most suitable as a transparent electrode film for an electronic display requiring a low resistance, such as an electroluminescence display, a plasma display, or an electrochromic element, and can be provided at a lower cost than in the past. In particular, in a simple matrix type LCD, an excellent effect of improving display quality such as enlargement of a display area and reduction of crosstalk is exhibited.

Also, in a TFT type LCD, by using it as a source electrode, a drain electrode and a pixel electrode, the source, drain and pixel electrodes can be formed simultaneously.
In addition, batch patterning becomes possible, and an excellent effect of improving productivity and reducing defects is exhibited.

[Brief description of the drawings]

1A is a schematic cross-sectional view of an example of a three-layered transparent conductive film of the present invention, and FIG. 1B is a schematic cross-sectional view of an example of a five-layered transparent conductive film of the present invention.

FIG. 2 is a schematic sectional view of a color LCD substrate used in the present invention.

FIG. 3 is a schematic cross-sectional view of an example of a transparent conductive film having a multilayer structure of an oxide layer of the present invention.

FIG. 4 (a) The top transparent oxide layer of the present invention is In ₂
The O ₃ a layer made of a multilayer film of a film composed mainly of film and ZnO as a main component, overlapping the membrane in such a manner that the content of In ₂ O ₃ as the film in the direction away from the substrate increases Cross-sectional schematic view of an example of a transparent conductive film composed of a multi-layered film, (b)
The uppermost transparent oxide layer of the present invention is a mixed oxide layer of In ₂ O ₃ and ZnO, and the gradient in which the In ₂ O ₃ content increases in the film thickness direction as going away from the substrate. FIG. 3C is a schematic cross-sectional view of an example of a transparent conductive film composed of a layer having a composition. FIG.
A layer composed of a multilayer film of a film containing n ₂ O ₃ as a main component and a film containing ZnO as a main component, such that the film closer to the substrate has a higher content of In ₂ O _3. Schematic cross-sectional view of an example of a transparent conductive film composed of a multilayer film in which a plurality of layers are stacked, (d)
The transparent oxide layer closest to the substrate of the present invention is a mixed oxide layer of In ₂ O ₃ and ZnO, and the content of In ₂ O ₃ increases in the film thickness direction as approaching the substrate. FIG. 1 is a schematic cross-sectional view of an example of a transparent conductive film made of a layer having a gradient composition.

FIG. 5A is a schematic cross-sectional view of an example of a transparent conductive film in which a metal other than Ag is interposed at the interface between the Ag-containing metal layer and the oxide layer of the present invention, and FIG. FIG. 4 is a schematic cross-sectional view of an example of a transparent conductive film using a gradient composition metal film having a high metal composition ratio other than Ag at an interface between a contained metal layer and an oxide layer.

FIG. 6A is a schematic cross-sectional view of an example of a transparent conductive film in which the metal layer of the present invention has a multilayer structure, and FIG.
FIG. 2 is a schematic cross-sectional view of an example of a transparent conductive film which is a graded metal film of a metal other than Ag and Ag.

FIG. 7 is a schematic view showing a state in which an etching residue is generated.

FIG. 8 is a schematic view showing a patterning method of the present invention.

9A is a schematic view of a TFT-type LCD electrode wiring according to a conventional example, and FIG. 9B is a schematic view of a TFT-type LCD electrode wiring according to an embodiment of the present invention.

FIG. 10 is a schematic view of a dry etching apparatus used in the embodiment.

[Explanation of symbols]

1: substrate, 2, 4, 6: transparent oxide layer, 3, 5: metal layer containing Ag, 7: color filter layer, 8: transparent resin protective layer, 9: inorganic intermediate layer, 10: In ₂ O ₃ , a film mainly containing ZnO, 12: a film containing less than 13 In, 13: a film containing more than 12 In, and 14: a film containing 50 In Atomic%, 15, 17, 21: Other metal layers other than Ag, 16, 22: Metal layer containing Ag, 18, 20, 23, 24: Other metal composition ratios other than Ag are 50% 19: Metal layer having a composition ratio of Ag of 50% or more, 25: etching residue, 26: resist, 27: gate electrode, 28: gate insulating film, 29: semiconductor layer, 30: pixel electrode, 31 : Drain electrode, 32: Source electrode, 33: Pixel electrode integrated Drain electrode, 34: source electrode, 35: RF power supply, 36: cathode electrode, 37: sample, 38: anode electrode, 39: glass substrate, 40: portion where the content of In is 50 atomic% or more.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01B 5/14 H01B 5/14 A H01J 9/02 H01J 9/02 F // H05B 33/28 H05B 33/28 (72) Invention Person Yuki Kawamura 1150 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside the Central Research Laboratory, Asahi Glass Co., Ltd.

Claims (17)

[Claims] 1. A transparent conductive film in which a transparent oxide layer and a metal layer are laminated in this order from the substrate side (n is an integer of 1 or more), wherein the transparent oxide layer contains ZnO, And In with Zn and I
A transparent conductive film, which is an oxide layer containing 9 to 98 atomic% with respect to the total of n and the metal layer is a metal layer containing Ag. 2. The method according to claim 1, wherein at least one of the transparent oxide layers comprises In ₂
2. The transparent conductive film according to claim 1, wherein the transparent conductive film is a layer composed of a multilayer film of a film mainly containing O ₃ and a film mainly containing ZnO. 3. The transparent oxide layer furthest from the substrate comprises In
A layer composed of a multilayer film composed of a film mainly composed of ₂ O ₃ and a film mainly composed of ZnO, wherein the film is stacked in such a manner that the further away from the substrate, the higher the content of In is. 3. The transparent conductive film according to claim 1, which is a layer made of a film. 4. The method according to claim 1, wherein the transparent oxide layer closest to the substrate is In ₂ O.
₃ is a layer composed of a multi-layered film of a film composed mainly of ZnO and a film composed mainly of ZnO, wherein the film closer to the substrate has a multi-layered film in which the content of In increases as the film becomes closer to the substrate. The transparent conductive film according to claim 1, wherein the transparent conductive film is a layer formed of: 5. The method according to claim 1, wherein at least one of the transparent oxide layers comprises In ₂
The transparent conductive film according to claim 1, wherein the transparent conductive film is a layer containing a mixed oxide of O ₃ and ZnO. 6. The transparent oxide layer farthest from the substrate is In
_This is a layer containing a mixed oxide of ₂ O ₃ and ZnO.
The transparent conductive film according to claim 1 or 5, which is a layer having a gradient composition whose content increases. 7. The transparent oxide layer closest to the substrate comprises In ₂ O
The transparent conductive layer according to claim 1 or 5, wherein the layer is a layer containing a mixed oxide of ₃ and ZnO, and has a gradient composition in which the In content increases in the thickness direction as approaching the substrate. film. 8. The method according to claim 1, wherein at least one of the transparent oxide layers comprises In ₂
A layer containing a mixed oxide of O ₃ and ZnO, or In ₂
In a layer composed of a multilayer film of a film containing O ₃ as a main component and a film containing ZnO as a main component, Zn is converted to Zn and In at a portion where the transparent oxide layer is in contact with a metal layer containing Ag.
The transparent conductive film according to any one of claims 1 to 7, wherein the oxide layer contains 50 atomic% or more of the total of 9. At least one of the transparent oxide layers is made of In ₂ O.
₃ is a layer composed of a multilayer film of a film containing ZnO as a main component and a film containing ZnO as a main component, wherein the film containing ZnO as a main component is Ga
The transparent conductive film according to claim 1, further comprising: 10. The transparent conductive film according to claim 1, wherein at least one of the metal layers is a layer made of an alloy film of Ag and another metal. 11. The transparent conductive material according to claim 1, wherein at least one of the metal layers is a layer composed of a multilayer film of a metal layer containing Ag and a metal layer made of another metal. film. 12. The method according to claim 1, wherein at least one of the metal layers is made of Ag and another metal, and has a gradient composition in which the Ag concentration changes in the thickness direction of the layer. The transparent conductive film according to the above. 13. The transparent conductive film according to claim 10, wherein the other metal is Au and / or Pd. 14. After forming the transparent conductive film according to any one of claims 1 to 13 on a substrate, the hydrogen ion concentration is adjusted to 0.1.
A method for forming a transparent electrode which is patterned by etching using an acidic aqueous solution of 01 to 9M. 15. The method for forming a transparent electrode according to claim 14, wherein an acidic aqueous solution to which an oxidizing agent having an oxidizing effect on Ag is added is used as the acidic aqueous solution. 16. A thin film transistor type liquid crystal display comprising a source electrode, a drain electrode and a pixel electrode.
A substrate with electrode wiring for a liquid crystal display, formed of the transparent conductive film according to any one of claims 13 to 13. 17. A transparent conductive film according to claim 1, wherein a gate electrode, a gate insulating film and a semiconductor layer are formed on a substrate, and then the transparent conductive film is etched. A method for forming a substrate with electrode wiring for a liquid crystal display, wherein a drain electrode integrated with a source electrode and a pixel electrode is formed by processing.