WO2011019040A1

WO2011019040A1 - Substrate having transparent conductive film attached thereto, and substrate for plasma display panel

Info

Publication number: WO2011019040A1
Application number: PCT/JP2010/063576
Authority: WO
Inventors: 健岡東; 秀文小高
Original assignee: 旭硝子株式会社
Priority date: 2009-08-14
Filing date: 2010-08-10
Publication date: 2011-02-17
Also published as: JPWO2011019040A1; CN102471147A; KR20120055558A

Abstract

A substrate having a transparent conductive film attached thereto, comprising a transparent glass substrate, a transparent conductive film mainly composed of tin oxide (SnO₂), and a barrier layer comprising an oxide of at least one metal selected from the group consisting of indium (In), tin (Sn), gallium (Ga), zinc (Zn), titanium (Ti) and niobium (Nb), wherein the transparent conductive film and the barrier layer are laminated in this order on the glass transparent substrate.

Description

Substrate with transparent conductive film and substrate for plasma display panel

The present invention relates to a substrate with a transparent conductive film and a substrate for a plasma display panel (PDP) using the substrate with a transparent conductive film.

When producing a front panel of a PDP, a transparent conductive film and a bus electrode are formed in this order on a glass substrate. As the transparent conductive film, indium oxide, zinc oxide, and tin oxide are known. As the indium oxide system, ITO (tin-doped indium oxide) is particularly famous and widely used. The reason why ITO is widely used is its low resistance and good patterning property. However, it is known that indium has few reserve resources, and the development of alternative materials is desired.
A tin oxide (SnO ₂ ) film is a material that is expected as an alternative material, but in order to impart conductivity to tin oxide, it is necessary to use antimony as a dopant, which may cause environmental concerns in the future. was there. In Patent Document 1, in order to solve this problem, tin oxide is the main component, and at least one element selected from the A dopant group consisting of niobium, tungsten, tantalum, bismuth and molybdenum, and copper element are used as dopants. Including transparent conductive films have been proposed. In the case of the transparent conductive film described in Patent Document 1, copper element is a component contained as a sintering aid for the sputtering target, and it is the element of the A dopant group that imparts conductivity to tin oxide.
Further, in Patent Document 2, in order to solve the above problem, at least one element selected from an A dopant group composed mainly of tin oxide and made of zinc, niobium, titanium, magnesium, aluminum, and zirconium, tungsten, There has been proposed a transparent conductive film containing, as a dopant, at least one element selected from a B dopant group made of tantalum and molybdenum.

When a bus electrode is formed on a transparent conductive film, a silver paste containing glass frit is applied on the transparent conductive film and then fired at 500 to 600 ° C. (see Patent Document 3). As a glass frit to be contained in the silver paste, a lead glass frit has been mainly used in the past. However, in the future, a bismuth oxide containing bismuth oxide (Bi ₂ O ₃ ) as a main component is required in view of the requirement for lead-free. It is thought to move to glass frit.

International Publication No. 2008-111324 Pamphlet International Publication No. 2007-142330 Pamphlet Japanese Unexamined Patent Publication No. 2003-162962

However, when the present inventors form a bus electrode using a silver paste containing bismuth glass frit on a transparent conductive film containing tin oxide as a main component, the contact resistance between the formed bus electrode and the transparent conductive film Found to rise. When the contact resistance between the bus electrode and the transparent conductive film is increased, the display quality of a PDP manufactured using the bus electrode is deteriorated.
In order to solve the above-mentioned problems of the prior art, the present invention has a contact resistance when forming a bus electrode using a silver paste containing bismuth glass frit on a transparent conductive film mainly composed of tin oxide. It is an object of the present invention to provide a substrate with a transparent conductive film in which the rise is prevented, and a substrate for PDP using the substrate with a transparent conductive film.

As a result of intensive studies to achieve the above object, the present inventors have found that bismuth oxide (Bi ₂ O ₃ ), which is a main component of a bismuth glass frit, and tin oxide (SnO ₂ ), which is a main component of a transparent conductive film. It was found that the formation of Bi ₂ Sn ₂ O ₇ reacts during firing of the silver paste to cause an increase in contact resistance between the bus electrode and the transparent conductive film during the formation of the bus electrode.
The present invention has been made on the basis of the above-described knowledge. On a glass transparent substrate, a transparent conductive film mainly composed of tin oxide (SnO ₂ ), indium (In), tin (Sn), gallium ( With a transparent conductive film formed by laminating a barrier layer containing an oxide of at least one metal selected from the group consisting of Ga), zinc (Zn), titanium (Ti) and niobium (Nb) in this order Providing a substrate.

In the substrate with a transparent conductive film of the present invention, the barrier layer is selected from the group consisting of TiO ₂ , Nb ₂ O ₅ , ITO (tin-doped indium oxide), TZO (tin-zinc oxide), and GZO (gallium-doped zinc oxide). It is preferable to consist of any of the above metal oxides.

In the substrate with a transparent conductive film of the present invention, the barrier layer preferably has a thickness of 1 to 50 nm.

In the substrate with a transparent conductive film of the present invention, the transparent conductive film containing tin oxide (SnO ₂ ) as a main component preferably contains 0.1 to 10 atomic percent of tantalum (Ta) as a dopant in terms of element.

In the substrate with a transparent conductive film of the present invention, the thickness of the transparent conductive film is preferably 50 nm or more and 1 μm or less.

Further, in the present invention, a bus electrode is formed by applying a silver paste containing bismuth-based glass frit on the barrier layer of the substrate with a transparent conductive film of the present invention and baking at a temperature of 500 to 600 ° C. A substrate for a plasma display panel (PDP) is provided.

In the substrate with a transparent conductive film of the present invention, a barrier layer is formed on a transparent conductive film containing tin oxide as a main component. Therefore, when forming a bus electrode using a silver paste containing a bismuth-based glass frit, The contact resistance between the transparent conductive film and the bus electrode is prevented from increasing.
The board | substrate with a transparent conductive film of this invention does not impair the characteristics, such as the electroconductivity of a transparent conductive film, transparency, by forming a barrier layer on a transparent conductive film.
Since the substrate for PDP of the present invention has a low contact resistance between the transparent conductive film and the bus electrode, a PDP manufactured using the substrate as a front panel of the PDP is expected to have excellent display quality.

FIG. 1 is a schematic view showing a basic configuration of a substrate with a transparent conductive film of the present invention. FIG. 2 is a schematic view showing a state in which bus electrodes are formed on a barrier layer of a substrate with a transparent conductive film in Examples. FIG. 3 is a SEM photograph of the state of the surface after dissolving and removing the bus electrode in Example 1. FIG. 4 is a SEM photograph of the surface state after dissolving and removing the bus electrode in Example 4. FIG. 5 is an SEM photograph of the surface state after dissolving and removing the bus electrode in Comparative Example 1.

The present invention will be described below with reference to the drawings.
FIG. 1 is a schematic view showing a basic configuration of a substrate with a transparent conductive film of the present invention. As shown in FIG. 1, in the substrate with a transparent conductive film of the present invention, a transparent conductive film 2 and a barrier layer 3 are laminated on a glass transparent substrate 1 in this order.
Hereinafter, each structure of a board | substrate with a transparent conductive film is demonstrated.

[Glass transparent substrate]
The constituent material of the glass transparent substrate can be widely selected from those used as a glass substrate for PDP, and various glass materials such as soda lime glass, high strain point glass and non-alkali glass can be used. Among these, the glass substrate composition described in Japanese Patent No. 2738036 and Japanese Patent No. 3669022 is particularly preferable.
The glass transparent substrate preferably has a spectral transmittance of 80% or more in the range of 425 to 475 nm, 510 to 560 nm, and 600 to 650 nm.

Although the size and thickness of the glass transparent substrate are not particularly limited, for example, those having a length and width of about 400 to 3000 mm can be preferably used. The thickness is preferably 0.7 to 3.0 mm, more preferably 1.5 to 3.0 mm.

[Transparent conductive film]
In the present invention, a transparent conductive film containing tin oxide (SnO ₂ ) as a main component is used. Here, the transparent conductive film containing tin oxide as a main component means that the content of tin oxide is 80 atomic% or more in terms of tin element. Here, the transparent conductive film may be a film formed only of tin oxide, but it is usually preferable to add a dopant for the purpose of imparting conductivity to the tin oxide. Examples of the dopant added for this purpose include tantalum (Ta), tungsten (W), bismuth (Bi), and molybdenum (Mo).
Indium and antimony have been conventionally used as dopants added for the purpose of imparting conductivity to tin oxide, but the former is an expensive element, and the latter is environmentally concerned in the future. Therefore, it is preferably not used for the transparent conductive film in the present invention. For this reason, it is preferable that the transparent conductive film in this invention does not contain indium and antimony substantially, and these content is 0.1 atomic% or less in element conversion.

For the purpose of imparting conductivity to tin oxide, when the above dopant is contained in a transparent conductive film mainly composed of tin oxide, the dopant content in the transparent conductive film is 0.1 to 10 atomic% in terms of element. It is preferable that it is 0.5 to 5 atomic%.

In addition to tin oxide and the dopant added for the purpose of imparting conductivity to the above-mentioned tin oxide, the sputtering target used for forming a transparent conductive film mainly composed of tin oxide includes a sintering aid. Agents are usually added. Therefore, the transparent conductive film containing tin oxide as a main component usually contains a component of such a sintering aid. Examples of the sintering aid added to the sputtering target include copper (Cu), zinc (Zn), niobium (Nb), titanium (Ti), magnesium (Mg), aluminum (Al), and zirconium (Zr). It is done.
The content of the sintering aid component in the transparent conductive film containing tin oxide as a main component is preferably 10 atomic% or less in terms of element. In addition, the transparent conductive film mainly composed of tin oxide is composed of tin oxide, a dopant added for the purpose of imparting conductivity to the above-described tin oxide, and components other than the components of the sintering aid (hereinafter referred to as “others” In other words, the content of the other component is preferably 10 atomic% or less in terms of element.

The transparent conductive film containing tin oxide as a main component preferably has a specific resistance of 5 × 10 ⁻² Ωcm or less, more preferably 1 × 10 ⁻² Ωcm or less, and more preferably 0.5 × 10 ⁻² Ωcm. Or less, more preferably 9 × 10 ⁻³ Ωcm or less.

The transparent conductive film mainly composed of tin oxide preferably has a thickness of 1 μm or less. If a film thickness is 1 micrometer or less, there is no possibility that a transparent conductive film may have optical defects, such as a haze. The film thickness of the transparent conductive film is more preferably 0.4 μm or less, and further preferably 0.25 μm or less. Moreover, it is preferable that the film thickness of a transparent conductive film is 50 nm or more.

The transparent conductive film mainly composed of tin oxide is preferably excellent in transparency, and specifically, the visible light transmittance is preferably 80% or more.

In order to form a transparent conductive film mainly composed of tin oxide on a glass transparent substrate, sputtering is performed using a sputtering target having a desired composition, specifically, a sputtering target having the same composition as the transparent conductive film to be formed. Just do it. At this time, the sputtering method to be used is not particularly limited, but a DC sputtering method using a DC power source, a DC pulse sputtering method, an AC sputtering method using a DC power source by switching, or an MF sputtering method using a medium wave power source, It is preferable because it is easy to operate and advantageous in terms of film thickness control.
However, the transparent conductive film mainly composed of tin oxide may be formed by using another sputtering method such as an RF sputtering method using a high frequency power source, or a sputtering method such as a CVD method, a sol-gel method, or a PLD method. You may form using the film-forming method other than the method.

When forming the transparent conductive film which has tin oxide as a main component by sputtering method, it is preferable to perform sputtering in an oxidizing atmosphere. Here, the oxidizing atmosphere is an atmosphere containing an oxidizing gas, and is usually a mixed gas atmosphere of an oxidizing gas and an inert gas.
Further, the oxidizing _{_{gas, O 2, H 2 O,}} CO, CO 2 , etc., means an oxygen atom-containing gas.
Among them, a mixed gas atmosphere of O ₂ or CO ₂ and argon (Ar) is preferable because the gas composition is easy to control and it is convenient for obtaining a transparent and low resistance film, and CO ₂ and Ar A mixed gas atmosphere is particularly preferable.
The O ₂ concentration in the mixed gas atmosphere of O ₂ and Ar is preferably 1 to 10% by volume because a transparent and low resistance film can be obtained.
The CO ₂ concentration in the mixed gas atmosphere of CO ₂ and Ar is preferably 10 to 50% by volume because a transparent and low resistance film can be obtained.

Sputtering conditions vary depending on the sputtering method used, but in the case of magnetron DC sputtering, it is preferable to carry out under the following conditions.
Power density during sputtering: 1 to 15 W / cm ²
Sputtering pressure: 10 ⁻² to 10 Pa
Deposition temperature (substrate temperature): Room temperature to 300 ° C

[Barrier layer]
As the barrier layer, an oxide of at least one metal selected from the group consisting of indium (In), tin (Sn), gallium (Ga), zinc (Zn), titanium (Ti), and niobium (Nb) is used. Use what is included. By providing such a barrier layer on a transparent conductive film mainly composed of tin oxide, an increase in contact resistance between the bus electrode and the transparent conductive film during the formation of the bus electrode, specifically, a bismuth-based glass frit is formed. When the silver paste contained is applied on the barrier layer and then baked at 500 to 600 ° C., the contact resistance between the bus electrode and the transparent conductive film is prevented from increasing.

Specific examples of the barrier layer having the above composition include a TiO ₂ film, an Nb ₂ O ₅ film, an ITO (tin doped indium oxide) film, a TZO (tin zinc oxide) film, and a GZO (gallium doped zinc oxide) film. .

As described above, the increase in contact resistance between the bus electrode and the transparent conductive film during the formation of the bus electrode is caused by bismuth oxide (Bi ₂ O ₃ ), which is the main component of the bismuth-based glass frit, and the main component of the transparent conductive film. This is because certain tin oxide (SnO ₂ ) reacts during the baking of the silver paste to form Bi ₂ Sn ₂ O ₇ . The action of preventing an increase in contact resistance between the bus electrode and the transparent conductive film when forming the bus electrode varies depending on the material constituting the barrier layer as described below.

When the barrier layer is a TiO ₂ film or an Nb ₂ O ₅ film, Bi ₂ O _{3 in} which the crystalline TiO ₂ film or Nb ₂ O ₅ film is the main component of the bismuth-based glass frit and the main component of the transparent conductive film The reaction with tin oxide (SnO ₂ ) is suppressed. As a result, formation of Bi ₂ Sn ₂ O ₇ is suppressed, and an increase in contact resistance between the bus electrode and the transparent conductive film is prevented. Note that the TiO ₂ film or the Nb ₂ O ₅ film is an insulator, but since the thickness of the barrier layer is small as will be described later, the presence of the barrier layer between the bus electrode and the transparent conductive film The contact resistance between the bus electrode and the transparent conductive film does not increase.

On the other hand, when the barrier layer is an ITO film, a TZO film or a GZO film, the effect of suppressing the reaction between Bi ₂ O ₃ and SnO ₂ is less than that of the TiO ₂ film or the Nb ₂ O ₅ film. Since the film itself is excellent in conductivity, the resistance of the entire film configuration of the barrier layer and the transparent conductive film is lowered (hereinafter, this action is referred to as “bypass effect by the barrier layer”). As a result, an increase in contact resistance between the bus electrode and the transparent conductive film is prevented.

Among the barrier layers described above, an ITO film is preferable because of excellent conductivity of the film itself and good film patternability. In addition, the conductivity of the film itself is inferior to that of the ITO film, but the influence of the film thickness on the resistance value is relatively small, the film formation cost is lower than that of the ITO film, and it is chemically stable. A TZO film is also preferable because it does not dissolve even in alkaline cleaning where the GZO film dissolves.

The thickness of the barrier layer is preferably 1 to 50 nm. When the thickness of the barrier layer is in the above range, the effect of preventing an increase in contact resistance between the bus electrode and the transparent conductive film when forming the bus electrode is excellent. When the thickness of the barrier layer is less than 1 nm, it is impossible to prevent an increase in contact resistance between the bus electrode and the transparent conductive film when the bus electrode is formed. More specifically, when the barrier layer is a TiO ₂ film or an Nb ₂ O ₅ film, if the thickness of the barrier layer is less than 1 nm, the effect of suppressing the reaction between Bi ₂ O ₃ and SnO ₂ is ineffective. This is sufficient, and an increase in contact resistance between the bus electrode and the transparent conductive film during the formation of the bus electrode cannot be prevented. When the barrier layer is an ITO film, a TZO film, or a GZO film, if the thickness of the barrier layer is less than 1 nm, the increase in contact resistance due to the formation of Bi ₂ Sn ₂ O ₇ cannot be offset by the bypass effect. An increase in contact resistance between the bus electrode and the transparent conductive film during electrode formation cannot be prevented.
On the other hand, even if the thickness of the barrier layer exceeds 50 nm, the effect of preventing the increase in contact resistance between the bus electrode and the transparent conductive film during the formation of the bus electrode is not increased, increasing the tact time, increasing the material cost, This is not preferable because problems due to an increase in the thickness of the barrier layer such as an influence on patternability of a subsequent process occur. Further, when the barrier layer is a TiO ₂ film or an Nb ₂ O ₅ film, if the thickness of the barrier layer exceeds 50 nm, an increase in resistance due to the barrier layer itself becomes a problem.
The thickness of the barrier layer is more preferably 1 to 30 nm.

The total thickness of the laminate of the transparent conductive film and the barrier layer is preferably 50 to 1000 nm, considering the balance of conductivity, barrier properties, film transparency and productivity, and preferably 50 to 500 nm. It is more preferable that the thickness is 50 to 200 nm.

The barrier layer formed on the transparent conductive film is required to have the same optical characteristics as the transparent conductive film. That is, the barrier layer is required to have excellent transparency, and the visible light transmittance is preferably 80% or more.

In order to form the barrier layer on the transparent conductive film, sputtering may be performed using a sputtering target having a desired composition. At this time, the sputtering method to be used is not particularly limited, but a DC sputtering method using a DC power source, a DC pulse sputtering method, an AC sputtering method using a DC power source by switching, or an MF sputtering method using a medium wave power source, It is preferable because it is easy to operate and advantageous in terms of film thickness control.
However, the barrier layer may be formed by using another sputtering method such as an RF sputtering method using a high-frequency power source, or by using a film forming method other than the sputtering method such as a CVD method, a sol-gel method, or a PLD method. May be formed.

When the barrier layer is formed by a sputtering method, it is preferable to perform sputtering in an oxidizing atmosphere. Here, the oxidizing atmosphere is an atmosphere containing an oxidizing gas, and is usually a mixed gas atmosphere of an oxidizing gas and an inert gas. Further, the oxidizing _{_{gas, O 2, H 2 O,}} CO, CO 2 , etc., means an oxygen atom-containing gas.
Among them, a mixed gas atmosphere of O ₂ or CO ₂ and argon (Ar) is preferable because the gas composition is easy to control and it is convenient for obtaining a transparent and low resistance film, and CO ₂ and Ar A mixed gas atmosphere is particularly preferable.
The O ₂ concentration in the mixed gas atmosphere of O ₂ and Ar is preferably 1 to 10% by volume because a transparent film can be obtained.
The CO ₂ concentration in the mixed gas atmosphere of CO ₂ and Ar is preferably 10 to 50% by volume because a transparent film can be obtained.

The sputtering conditions vary depending on the sputtering method used, but in the case of the magnetron DC sputtering method, the sputtering can be performed under the same conditions as the sputtering conditions for forming the transparent conductive film.

The substrate for PDP of the present invention is such that a bus electrode is formed on the barrier layer of the substrate with a transparent conductive film of the present invention as described below.
First, a silver paste containing bismuth-based glass frit is applied to a portion where a bus electrode is formed on a transparent conductive film. The silver paste used for this purpose is usually prepared by mixing 60% by mass or more of silver powder, 1 to 20% by mass of a bismuth glass frit, and 10 to 30% by mass of an organic binder. A typical composition of the bismuth glass frit used for this purpose is shown below.
SiO ₂ 1-5% by mass
B ₂ O ₃ 5-15% by mass
Al ₂ O ₃ 3-8 mass%
Bi ₂ O ₃ 70-90 mass%
The coating method of the silver paste is not particularly limited, and for example, a coating method such as screen printing, a spray method, a blade coater method, or a die coating method can be used. The thickness to which the silver paste is applied is not particularly limited, and can be appropriately selected according to the thickness of the silver electrode to be formed. The thickness of the formed silver electrode is usually in the range of several μm to several tens of μm.
Next, a bus electrode is formed by baking at a temperature of 500 to 600 ° C. for a predetermined time (for example, 5 minutes to 1 hour), and the PDP substrate of the present invention is obtained.
As described above, in the substrate with a transparent conductive film of the present invention, since the barrier layer is formed on the transparent conductive film mainly composed of tin oxide, the contact between the bus electrode and the transparent conductive film when forming the bus electrode. Resistance rise is prevented. For this reason, the PDP substrate of the present invention has a low contact resistance between the transparent conductive film and the bus electrode, and a PDP produced using the substrate as a front panel of the PDP is expected to have excellent luminous efficiency.

The present invention will be further described below using examples.
(Examples 1 to 5)
In Examples 1 to 5, a Ta-doped SnO ₂ film was formed as a transparent conductive film on a glass transparent substrate by the following procedure, and a TiO ₂ film and Nb _{2 were formed} as a barrier layer on the Ta-doped SnO ₂ film. After forming an O ₅ film, an ITO film, a TZO film, or a GZO film, a bus electrode is formed on the barrier layer, and a contact resistance between the bus electrode and the barrier layer using a TLM (Transmission Line Model) method, And sheet resistance was calculated | required. The sheet resistance referred to here is the sheet resistance of the laminate including the transparent conductive film and the barrier layer.
[Glass transparent substrate]
As the glass transparent substrate, a high strain point glass substrate for PDP (PD200 manufactured by Asahi Glass Co., Ltd.) was used.
[Transparent conductive film]
On the top surface of the substrate, a film (Ta-doped SnO ₂ film) containing tin oxide as a main component and tantalum as a dopant as a transparent conductive film was formed under the following conditions. The composition of the Ta-doped SnO ₂ film is 2.1 atomic% in terms of tantalum atomic weight, and the film thickness is 100 nm.
Sputtering method: magnetron DC sputtering sputtering target: Ta-doped SnO ₂ target (Ta ₂ O ₃ doping amount 6 mass%)
Sputtering gas: Mixed gas of Ar and O ₂ (O ₂ 1% by volume)
Power density during sputtering: 5 W / cm ²
Sputtering pressure: 0.5 Pa
Deposition temperature (substrate temperature): 250 ° C

[Barrier layer]
As a barrier layer on the transparent conductive film, TiO ₂ film, Nb ₂ O ₅ film, ITO film (SnO ₂ doping amount 10 mass%), TZO film (Sn ₂ ZnO ₃ ) or GZO film (Ga ₂ O ₃ doping amount 5) .7 mass%) was formed under the following conditions.
<TiO ₂ film>
Sputtering method: magnetron DC sputtering sputtering target: Ti target sputtering gas: mixed gas of Ar and O ₂ (O ₂ 10 volume%)
Power density during sputtering: 12 W / cm ²
Sputtering pressure: 0.5 Pa
Deposition temperature (substrate temperature): Room temperature Film thickness: 30 nm
<Nb ₂ O ₅ film>
Sputtering method: magnetron DC sputtering sputtering target: Nb target sputtering gas: mixed gas of Ar and O ₂ (O ₂ 10 volume%)
Power density during sputtering: 12 W / cm ²
Sputtering pressure: 0.5 Pa
Deposition temperature (substrate temperature): Room temperature Film thickness: 30 nm
<ITO film>
Sputtering method: magnetron DC sputtering sputtering target: ITO target (SnO ₂ doping amount 10 mass%)
Sputtering gas: Ar
Power density during sputtering: 5 W / cm ²
Sputtering pressure: 0.5 Pa
Deposition temperature (substrate temperature): Room temperature Film thickness: 30 nm
<TZO film>
Sputtering method: magnetron DC sputtering sputtering target: TZO target (Sn ₂ ZnO ₃ )
Sputtering gas: Ar
Power density during sputtering: 2.5 W / cm ²
Sputtering pressure: 0.5 Pa
Deposition temperature (substrate temperature): Room temperature Film thickness: 30 nm
<GZO film>
Sputtering method: magnetron DC sputtering sputtering target: GZO target (Ga ₂ O ₃ doping amount 5.7 mass%)
Sputtering gas: Ar
Power density during sputtering: 5 W / cm ²
Sputtering pressure: 0.5 Pa
Deposition temperature (substrate temperature): Room temperature Film thickness: 30 nm

[Bus electrode]
A mixture of vehicle, terpineol, bismuth glass frit and silver powder mixed so as to be 10% by mass of bismuth glass frit and 90% by mass of silver powder was screen-printed on the barrier layer. The composition of the bismuth glass frit is as follows.
SiO ₂ 1-5% by mass
B ₂ O ₃ 5-15% by mass
Al ₂ O ₃ 3-8 mass%
Bi ₂ O ₃ 70-90 mass%
Then, it baked at 600 degreeC for 1 hour, and formed the bus electrode. As shown in FIG. 2, a plurality of bus electrodes 4 and 5 were formed on the barrier layer 3 at intervals.
[TLM method]
Contact resistance and sheet resistance were determined according to the following formula.
R _T = 2 × R _C + (R _SH × l) / W
In the equation, _RT is a resistance between bus electrodes, _RC is a contact resistance between the barrier layer and the bus electrode, R _SH is a sheet resistance, l is a distance between the bus electrodes, and W is a width of the bus electrode.
The measurement results of contact resistance and sheet resistance are shown in the following table.
(Comparative Example 1)
The same procedure as in the example was performed without forming the barrier layer, except that the bus electrode was directly formed on the transparent conductive film. The measurement results of contact resistance and sheet resistance are shown in the following table.

As is apparent from the above table, Examples 1 to 5 in which a TiO ₂ film, Nb ₂ O ₅ film, ITO film, TZO film or GZO film was formed as a barrier layer on a transparent conductive film containing tin oxide as a main component are as follows: It was confirmed that the contact resistance was lower than that of Comparative Example 1 in which no barrier layer was formed, and an increase in the contact resistance between the bus electrode and the transparent conductive film during the formation of the bus electrode was prevented.
For Example 1 (barrier layer: TiO ₂ film), Example 4 (barrier layer: TZO film), and Comparative Example 1 (no barrier layer), the surface state after dissolving and removing the bus electrode was scanned with electrons. Photographed with a microscope (SEM). The results are shown in FIGS.
As is clear from FIG. 5, in Comparative Example 1 in which the barrier layer was not formed on the transparent conductive film, it was confirmed that crystals (Bi ₂ Sn ₂ O ₇ ) were generated that caused the increase in contact resistance.
On the other hand, as is clear from FIG. 3, in Example 1 in which a TiO ₂ film was formed as a barrier layer on a transparent conductive film, the formation of crystals was not observed, and the crystalline TiO ₂ film was made of bismuth-based glass frit. It shows that the reaction between Bi ₂ O _{3 as the} main component and SnO ₂ constituting the tin oxide film was suppressed. As a result, an increase in contact resistance between the bus electrode and the transparent conductive film is prevented.
Further, as apparent from FIG. 4, in Example 4 in which the TZO film was formed as the barrier layer on the transparent conductive film, the formation of crystals was observed, but the TZO film itself has high conductivity, so the barrier layer By virtue of the bypass effect, the increase in contact resistance between the bus electrode and the transparent conductive film is prevented.

Although the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2009-187969 filed on Aug. 14, 2009, the contents of which are incorporated herein by reference.

In the substrate with a transparent conductive film of the present invention, a barrier layer is formed on a transparent conductive film containing tin oxide as a main component. Therefore, when forming a bus electrode using a silver paste containing a bismuth-based glass frit, The contact resistance between the transparent conductive film and the bus electrode is prevented from increasing. Moreover, the board | substrate with a transparent conductive film of this invention does not impair characteristics, such as electroconductivity of a transparent conductive film, transparency, by forming a barrier layer on a transparent conductive film. Furthermore, since the PDP substrate of the present invention has a low contact resistance between the transparent conductive film and the bus electrode, a PDP manufactured using the substrate as a front panel of the PDP is expected to have excellent display quality.

1: Transparent glass substrate 2: Transparent conductive film 3: Barrier layer 4, 5: Bus electrode

Claims

On a glass transparent substrate, a transparent conductive film mainly composed of tin oxide (SnO 2 ), indium (In), tin (Sn), gallium (Ga), zinc (Zn), titanium (Ti) and niobium (Nb) A substrate with a transparent conductive film in which a barrier layer containing an oxide of at least one metal selected from the group consisting of:
The barrier layer is made of any metal oxide selected from the group consisting of TiO 2 , Nb 2 O 5 , ITO (tin doped indium oxide), TZO (tin zinc oxide) and GZO (gallium doped zinc oxide). The substrate with a transparent conductive film according to claim 1.
The substrate with a transparent conductive film according to claim 1 or 2, wherein the barrier layer has a thickness of 1 to 50 nm.
The transparent conductive film mainly containing tin oxide (SnO 2) is transparent according to any one of claims 1 to 3 containing 0.1 to 10 atomic% tantalum (Ta) in terms of an element as a dopant Substrate with conductive film.
The substrate with a transparent conductive film according to any one of claims 1 to 4, wherein the transparent conductive film has a thickness of 50 nm to 1 µm.
A bus electrode is obtained by applying a silver paste containing a bismuth-based glass frit on the barrier layer of the substrate with a transparent conductive film according to any one of claims 1 to 5, and firing the paste at a temperature of 500 to 600 ° C. A substrate for a plasma display panel (PDP) on which is formed.