WO2011019039A1

WO2011019039A1 - Substrate having transparent conductive film attached thereto, and substrate for plasma display panel

Info

Publication number: WO2011019039A1
Application number: PCT/JP2010/063575
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: JPWO2011019039A1; CN102471145A; KR20120069661A

Abstract

A substrate having a transparent conductive film attached thereto, comprising a transparent glass substrate and a transparent conductive film mainly composed of tin oxide (SnO₂) and formed on the transparent glass substrate, wherein the peak intensity ratio (Y/X) is 1.5 to 1.8 inclusive (wherein Y represents the crystalline peak of SnO₂ face(100) contained in the XRD peaks of the transparent conductive film; and X represents the background peak caused by 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 transparent 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.
Tin oxide (SnO ₂₎ film has a material which is expected as an alternative material. However, in order to impart conductivity to tin oxide, it was necessary to use antimony as a dopant, which may have environmental concerns in the future. 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 bus electrode (silver electrode) is formed by applying a silver paste containing glass frit on the transparent conductive film and then baking at 500 to 600 ° C. ( (See Patent Document 3). Hereinafter, in this specification, the silver paste containing glass frit may be simply referred to as “silver paste”.
However, when a bus electrode (silver electrode) is formed using a silver paste, the glass transparent substrate develops yellow color (yellowing), and there is a problem that the quality of color display is deteriorated in a PDP manufactured using the glass transparent substrate. there were. That is, there is a problem that the screen displaying white has a yellowish color around the silver electrode, and the brightness of the screen displaying blue is reduced.
This yellowing occurs when the silver electrode is used to form a bus electrode (silver electrode), Ag ions in the silver paste diffuse from the surface of the glass transparent substrate to the inside (surface layer) and exist in the surface layer. It is considered that this is due to the color formation of the colloid produced by agglomeration by being reduced to Fe ⁰ by Fe ²⁺ , Sn ²⁺ , etc.

As a method of preventing such yellowing, Patent Document 4 discloses a reducing property formed on a surface of a glass substrate formed into a plate shape by a float method by polishing the surface on which the metal electrode is formed. It has been proposed to remove foreign layers. Patent Document 5 proposes that a protective layer is formed by continuously spraying SO ₂ on the surface of a glass plate formed into a plate shape by a float process at the inlet of the slow cooling furnace or upstream of the slow cooling furnace. . Patent Documents 6 and 7 propose forming a metal oxide layer on the surface of a glass substrate. Patent Document 8 proposes to use a silver paste or silver film containing Ag particles and a glass frit to which a transition metal oxide is added as a silver paste or silver film used for forming a silver electrode. .

However, since the methods described in Patent Documents 4 to 7 require specific treatment on the glass transparent substrate, the operation is complicated, leading to a decrease in yield and an increase in cost. Moreover, although the method of patent document 8 may use what contains the glass frit which added the oxide of the transition metal as a silver paste, a glass substrate and the silver particle contained in a silver paste are physically made. Since it is not completely isolated, there is a problem that it is difficult to completely suppress yellowing of the glass substrate.

International Publication No. 2008-111324 Pamphlet International Publication No. 2007-142330 Pamphlet Japanese Unexamined Patent Publication No. 2003-162962 Japanese Patent Laid-Open No. 10-255669 Japanese Unexamined Patent Publication No. 2007-204295 Japanese Laid-Open Patent Publication No. 10-302648 Japanese Unexamined Patent Publication No. 2003-16949 Japanese Unexamined Patent Publication No. 2003-162962

In order to solve the above-mentioned problems of the prior art, the present invention eliminates yellowing of a glass transparent substrate when forming a bus electrode using a silver paste without performing a specific treatment on the glass transparent substrate. An object of the present invention is to provide a substrate with a transparent conductive film that can be prevented, and a substrate for PDP using the substrate with a transparent conductive film.

In order to achieve the above object, the present invention is a substrate with a transparent conductive film in which a transparent conductive film mainly composed of tin oxide (SnO ₂ ) is formed on a glass transparent substrate,
When the crystal peak of the SnO ₂ (100) plane in the XRD peak of the transparent conductive film is Y and the background peak due to the glass transparent substrate is X, the peak intensity ratio Y / X is 1.5 or more and 1.8 or less. A substrate with a transparent conductive film is provided.

In the substrate with a transparent conductive film of the present invention, the transparent conductive film containing tin oxide as a main component preferably contains tantalum (Ta) as a dopant in an amount of 2.5 atomic% or less 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, the present invention is a method for producing a substrate with a transparent conductive film of the present invention, and when forming a transparent conductive film containing tin oxide (SnO ₂ ) as a main component on a glass transparent substrate by a sputtering method, Production of a substrate with a transparent conductive film, characterized by using a sputtering target containing tin oxide as a main component and containing 2.5 atomic% or less of tantalum (Ta) as a dopant, and performing sputtering at a substrate temperature of 250 ° C. or higher. Provide a method.

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

In the PDP substrate of the present invention, when the crystal peak of the Bi ₂ Sn ₂ O ₇ (222) plane in the XRD peak of the bus electrode is Z and the background peak due to the glass transparent substrate is X, the peak intensity ratio Z / X is preferably 2 or more.

According to the substrate with a transparent conductive film of the present invention, it is possible to prevent yellowing of the glass transparent substrate when a bus electrode is formed using a silver paste without performing a specific treatment on the glass transparent substrate. .
In the PDP substrate of the present invention, yellowing of the glass transparent substrate is prevented, so that the PDP produced using the substrate is excellent in the quality of color display.

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 an example of an XRD peak of the transparent conductive film in the substrate with the transparent conductive film on which the transparent conductive film containing tin oxide as a main component is formed. FIG. 3 is an example of an XRD peak of a bus electrode formed by applying a silver paste containing bismuth-based glass frit on a transparent conductive film of a substrate with a transparent conductive film and baking it. FIG. 4 is a SEM photograph of the surface of the substrate with a transparent conductive film of Example 1 after removing the bus electrode. FIG. 5 is an SEM photograph of the surface of the substrate with a transparent conductive film of Comparative Example 1 after removing the bus electrode. FIG. 6 is a cross-sectional SEM photograph of the substrate with a transparent conductive film of Example 1 after removing the bus electrode.

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 is formed on a glass transparent substrate 1.
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 substrate with a transparent conductive film of 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 more than 80 atomic% 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 dopants added for this purpose include tantalum (Ta), tungsten (W), niobium (Nb), bismuth (Bi), and molybdenum (Mo).
Among the above dopants, tantalum is particularly preferable because of its high effect of imparting conductivity to tin oxide.
As dopants added for the purpose of imparting conductivity to tin oxide, indium and antimony have also been used in the past, but the former is an expensive element, and the latter has environmental concerns in the future. The transparent conductive film in the present invention is preferably not used. 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.

However, when a dopant is added for the purpose of imparting conductivity to tin oxide, it is necessary to add it in an amount that does not adversely affect the function of the transparent conductive film as a barrier layer described later. About the tantalum which is a suitable dopant, suitable content in a transparent conductive film is mentioned later.

As described above, when forming a bus electrode using a silver paste, the cause of yellowing of the glass transparent substrate is that Ag ions in the silver paste diffuse from the glass transparent substrate surface to the inside (surface layer), and the surface It is considered that it is reduced to Ag ⁰ by Fe ²⁺ , Sn ²⁺ , etc. present in the layer, and this aggregates to form a colloid. Hereinafter, in this specification, “yellowing of a transparent glass substrate” refers to yellowing of a transparent glass substrate that occurs when a bus electrode is formed using a silver paste.
For this reason, the transparent conductive film formed on the glass transparent substrate is also required to have a function as a barrier layer for preventing Ag ions in the silver paste from reaching the glass transparent substrate surface. Hereinafter, in the present specification, the term “barrier layer” refers to a barrier layer for preventing Ag ions in the silver paste from reaching the glass transparent substrate surface.
In order for the transparent conductive film containing tin oxide as a main component to exhibit the function as the barrier layer, the transparent conductive film is a film having a high degree of crystallinity and the orientation of crystals constituting the film. The inventors of the present application have found that it is important from the viewpoint of chemical robustness of the film that the film is low, that is, that crystals having various orientations are mixed in the film.

When the transparent conductive film mainly composed of tin oxide is an amorphous film or a film with low crystallinity, the bus electrode is formed using silver paste because the film is not chemically robust. In this case, a hole is formed in a part of the film, and Ag ions in the silver paste reach the glass transparent substrate through the hole, so that the function as a barrier layer is low and yellowing of the glass transparent substrate can be prevented. Can not.

Even if the transparent conductive film containing tin oxide as a main component is a film having a high degree of crystallinity, if the orientation of the crystals constituting the film increases, the chemical fastness of the film decreases, so a silver paste is used. When the bus electrode is formed, holes are formed in a part of the film, and Ag ions in the silver paste reach the glass transparent substrate through the holes, so that the function as a barrier layer is low, and the yellowing of the glass transparent substrate is caused. Can not be prevented.

The degree of crystallinity of the transparent conductive film mainly composed of tin oxide and the degree of orientation of the crystals constituting the film can be confirmed by the XRD peak of the transparent conductive film, as will be described later. .
An example of the XRD peak of the transparent conductive film in the substrate with the transparent conductive film on which the transparent conductive film mainly composed of tin oxide is formed is shown in FIG. In FIG. 2, Y is a crystal peak of the SnO ₂ (100) plane, and X is a background peak due to the glass transparent substrate.
In the substrate with a transparent conductive film of the present invention, the peak intensity ratio (Y / X) between Y and X in the XRD peak of the transparent conductive film is 1.5 or more and 1.8 or less. Hereinafter, in this specification, when “Y / X” is described, it indicates a peak intensity ratio between Y and X in the XRD peak of the transparent conductive film.
If Y / X is in the above range, the transparent conductive film is a film having a high degree of crystallinity, and the orientation of the crystals constituting the film is low, and crystals that are oriented in various directions are formed in the film. Since they are mixed, the function as a barrier layer is sufficiently exhibited, and yellowing of the glass transparent substrate is prevented.

If Y / X is less than 1.5, the transparent conductive film is an amorphous film or a film having a low degree of crystallinity. The function as a layer cannot be exhibited, and yellowing of the glass transparent substrate cannot be prevented.
On the other hand, if Y / X is more than 1.8, although the film has a high degree of crystallinity, the orientation of the crystals constituting the film increases, so that the chemical robustness of the film decreases as described above. The function as a barrier layer cannot be exhibited, and yellowing of the glass transparent substrate cannot be prevented.

As described above, tantalum is preferable as a dopant added for the purpose of imparting conductivity to tin oxide. When adding tantalum as a dopant, the tantalum content in the transparent conductive film is 2.5 atomic% or less in terms of element.
From the viewpoint of imparting conductivity to tin oxide, it is preferable to increase the tantalum content of the transparent conductive film. However, if the Ta content in the transparent conductive film is more than 2.5 atomic% in terms of element, the film Since the orientation of the crystals constituting the film becomes high and the above Y / X exceeds 1.8, the function as a barrier layer is lowered and yellowing of the glass transparent substrate cannot be prevented.

The lower limit of the tantalum content in the transparent conductive film is not particularly limited as long as conductivity can be imparted to tin oxide, but it is preferably 0.1 atomic% or more in terms of Ta element, and 0.5 atomic% or more. It is more preferable that

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 less than 10 atomic% 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 components is preferably less than 10 atomic% in terms of elements.

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. However, Y / X of the formed transparent conductive film is required to be 1.5 or more and 1.8 or less.
The conditions for forming a transparent conductive film having a Y / X of 1.5 or more and 1.8 or less vary depending on the composition of the transparent conductive film containing tin oxide as a main component. In the case of a transparent conductive film to which tantalum is added as a dopant, sputtering may be performed under the following conditions.

As described above, in order to make Y / X of the transparent conductive film 1.8 or less, the tantalum content in the transparent conductive film is required to be 2.5 atomic% or less in terms of element. Accordingly, a sputtering target containing tin oxide as a main component and containing tantalum of 2.5 atomic% or less in terms of element is used.
On the other hand, in order to make Y / X of a transparent conductive film 1.5 or more, it is necessary to crystallize the formed transparent conductive film sufficiently. In order to sufficiently crystallize the transparent conductive film to be formed, sputtering may be performed while the substrate is heated. The transparent conductive film containing tin oxide as a main component and containing tantalum of 2.5 atomic% or less in terms of element. In the case of forming a film, sputtering may be performed with the substrate temperature heated to 250 ° C. or higher. When the substrate temperature at the time of sputtering is less than 250 ° C., crystallization of the formed transparent conductive film becomes insufficient, and there is a possibility that Y / X of the transparent conductive film cannot be made 1.5 or more.
However, when the substrate temperature is too high, it no longer contributes to crystallization of the formed transparent conductive film, which is not preferable because the manufacturing cost increases. From the viewpoint of manufacturing cost, the substrate temperature is preferably 280 ° C. or lower.
Therefore, it is preferable to perform sputtering at a substrate temperature of 250 to 280 ° C.

The sputtering method to be used is not particularly limited, but the DC sputtering method using a DC power source, the DC pulse sputtering method, the AC sputtering method using a DC power source by switching, or the MF sputtering method using a medium wave power source is easy to operate. From the viewpoint of film thickness control, it is preferable.
However, the transparent conductive film containing tin oxide as a main component may be formed by using another sputtering method such as an RF sputtering method using a high frequency power source.

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 5% 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 10 W / cm ²
Sputtering pressure: 10 ⁻² to 10 Pa
Substrate temperature: 250-280 ° C

In the substrate with a transparent conductive film of the present invention, the transparent conductive film having tin oxide as a main component and Y / X of 1.5 to 1.8 is formed because a function as a barrier layer is required. is there. Therefore, as long as the function as a barrier layer is sufficiently exhibited and yellowing of the glass transparent substrate can be prevented, the entire transparent conductive film is composed of a transparent conductive film mainly composed of tin oxide having a function as the barrier layer. It does not have to be. That is, a transparent conductive film having a conventional composition may be formed as a second transparent conductive film on a transparent conductive film having tin oxide as a main component and functioning as the barrier layer. As such a 2nd transparent conductive film, the metal oxide containing at least 1 sort (s) chosen from the group which consists of Ga, Zn, Ti, Al, Sn, In, and Nb is mentioned.
In addition, when forming a 2nd transparent conductive film on the transparent conductive film which has a function as said barrier layer, it is made for the total film thickness of both to satisfy | fill the film thickness of the transparent conductive film mentioned above.

The substrate with a transparent conductive film of the present invention may have a configuration other than a glass transparent substrate, a transparent conductive film containing tin oxide as a main component, and a second transparent conductive film. As a specific example of such a configuration, there is a base film formed between a glass transparent substrate and a transparent conductive film containing tin oxide as a main component for the purpose of improving the flatness. Examples of the constituent material of the base film formed for such a purpose include silica, zirconia, titania and the like.

The substrate for PDP of the present invention is a transparent conductive film mainly composed of tin oxide of the substrate with a transparent conductive film of the present invention described above (when the second transparent conductive film is formed on the transparent conductive film, A bus electrode is formed on the second transparent conductive film by the following procedure.
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, but is preferably such that a silver electrode having a thickness of several μm to several tens of μm is formed.
Next, a bus electrode is formed by baking at a temperature of 500 to 600 ° C. for a predetermined time (for example, 1 to 5 hours), 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, the transparent conductive film containing tin oxide as a main component functions as a barrier layer. Therefore, when the bus electrode is formed using silver paste, the yellow glass transparent substrate is formed. Changes are prevented. As a result, a PDP manufactured using the substrate is excellent in color display quality.

The function of the transparent conductive film mainly composed of tin oxide as a barrier layer and the superiority or inferiority of the yellowing prevention effect of the glass substrate thereby confirmed from the XRD peak of the bus electrode formed by the above procedure. can do.
An example of the XRD peak of the bus electrode formed by the above procedure is shown in FIG. In FIG. 3, Z is a crystal peak of the Bi ₂ Sn ₂ O ₇ (222) plane, and X is a background peak due to the glass transparent substrate. Here, Bi ₂ Sn ₂ O ₇ is composed of bismuth oxide (Bi ₂ O ₃ ) that is a main component of a bismuth glass frit and tin oxide (SnO ₂ ) that is a main component of a transparent conductive film. It is a crystalline compound formed by reaction at times, and when the compound exists in a high crystallinity state, the function as a barrier layer is sufficiently exhibited and yellowing of the glass transparent substrate is prevented. it is conceivable that. The degree of crystallinity of Bi ₂ Sn ₂ O ₇ can be confirmed by the peak intensity ratio (Z / X) between Z and X in the XRD peak of the bus electrode. Hereinafter, in the present specification, when “Z / X” is described, it indicates the peak intensity ratio of Z and X in the XRD peak of the bus electrode.
In the PDP substrate of the present invention, Z / X is preferably 2 or more. If Z / X is 2 or more, Bi ₂ Sn ₂ O ₇ is present in a state of high crystallinity, the function as a barrier layer is sufficiently exhibited, and the effect of preventing yellowing of the glass transparent substrate is achieved. Are better.

In the PDP substrate of the present invention, as a result of preventing yellowing of the glass transparent substrate, the color difference b * value (JIS-Z8729) of the L * a * b * system color coordinate is suppressed to ± 5 or less. preferable.

The present invention will be further described below using examples.
(Examples 1 to 4, Comparative Examples 1 and 2)
In Examples 1 to 4 and Comparative Examples 1 and 2, a film containing tin oxide as a main component as a transparent conductive film and tantalum as a dopant (Ta-doped SnO ₂ film) is formed on a glass transparent substrate by the following procedure. A bus electrode (silver electrode) was formed on the Ta-doped SnO ₂ film.
[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]
Using a DC sputtering method, a Ta-doped tin oxide film with a thickness of 100 nm was formed as a transparent conductive film on the top surface of the substrate. The Ta content in the Ta-doped tin oxide film is as shown in Tables 1 and 2 below.
In addition, the composition of the used sputtering target and the substrate temperature at the time of performing the sputtering are as shown in Tables 1 and 2 below, and the other sputtering conditions are as follows.
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
[Bus electrode]
A silver paste obtained by mixing vehicle, terpineol, bismuth glass frit (ASF 1094) and silver powder so as to be 10 wt% bismuth glass frit and 90 wt% silver powder was screen-printed on the barrier layer. Then, it fired at 615 degreeC for 10 minute (s), and formed the bus electrode.
[Evaluation of the physical properties]
(Y / X and Z / X at XRD peak)
XRD was performed when the transparent conductive film was formed and when the bus electrode was formed, and Y / X and Z / X were obtained from the respective XRD peaks. XRD measurement was performed by 2θ / θ scan (manufactured by Rigaku Corporation, Rad-RB).
(Specific resistance of transparent conductive film)
The specific resistance of the transparent conductive film was measured by a four-terminal method (Mitsubishi Yuka's LORESTA-FP).
(Yellowing of transparent glass substrate)
After removing the bus electrode by nitric acid etching, the degree of yellowing of the glass transparent substrate was evaluated as a color difference b * value (JIS-Z8729) of L * a * b * system color coordinates.
The results are shown in Tables 1 and 2 below.

(Comparative Example 3)
Instead of the Ta-doped SnO ₂ film, an ITO film (SnO ₂ doping amount 10 mass%, film thickness 100 nm) was formed as a transparent conductive film under the following conditions.
Sputtering method: magnetron DC sputtering sputtering target: ITO target (SnO ₂ doping amount 10 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
Substrate temperature: 250 ° C
The formation conditions of the bus electrode are the same as those in Examples 1 to 4 and Comparative Examples 1 and 2 described above, except that baking after screen printing of the silver paste was performed at 590 ° C. for 1 hour.

As is clear from Tables 1 and 2, the Ta-doped SnO ₂ film had a slightly lower specific resistance than the ITO film, but had sufficient conductive properties as a transparent conductive film. In Comparative Example 2, although the specific resistance of the transparent conductive film was not measured, it is considered that the specific resistance is comparable to the other examples (Examples 1 to 4 and Comparative Example 1).
In Examples 1 to 4 where a Ta-doped SnO ₂ film having a tantalum content of 2.5 atomic% or less was formed at a substrate temperature of 250 to 280 ° C., the Y / value obtained from the XRD peak of the transparent conductive film (Ta-doped SnO ₂ film) was obtained. X was in the range of 1.5 to 1.8, and it was confirmed to be a transparent conductive film having a function as a barrier layer. Z / X obtained from the XRD peak of the bus electrode was 2 or more, and it was confirmed that the function as a barrier layer was excellent. The b * value indicates that yellowing is not a problem.
On the other hand, in Comparative Example 1 in which a Ta-doped SnO ₂ film having a tantalum content of 3.5 atomic% was formed as a transparent conductive film, Y / X obtained from the XRD peak of the transparent conductive film exceeded 1.8 (1.85 ), The orientation of the crystals constituting the film is high, the function as a barrier layer cannot be exhibited, and yellowing of the glass transparent substrate cannot be prevented. Z / X obtained from the XRD peak of the bus electrode is also less than 2 (1.32), indicating that the function as a barrier layer is inferior. The b * value indicates that yellowing is a problem level.
In Comparative Example 2 in which the Ta-doped SnO ₂ film was formed at a substrate temperature of 190 ° C., the Y / X obtained from the XRD peak of the transparent conductive film was less than 1.5 (1.41). The degree of conversion is low, the function as a barrier layer cannot be exhibited, and yellowing of the glass transparent substrate cannot be prevented. Z / X obtained from the XRD peak of the bus electrode is also less than 2 (1.22), indicating that the function as a barrier layer is inferior. The b * value indicates that yellowing is a problem level.
In Comparative Example 3 in which the ITO film is formed as the transparent conductive film, the transparent conductive film does not have a function as a barrier layer, and thus yellowing of the glass transparent substrate cannot be prevented. This point is also clear from the b * value.

For Example 1 and Comparative Example 1, the surface state after removing the bus electrode by nitric acid etching was photographed with a scanning electron microscope (SEM). The results are shown in FIGS. In any surface, a crystalline product which is a reaction product of bismuth oxide (Bi ₂ O ₃ ) which is a main component of a bismuth-based glass frit and tin oxide (SnO ₂ ) which is a main component of a transparent conductive film. The compound (Bi ₂ Sn ₂ O ₇ ) was generated, and it was confirmed that the Ta-doped SnO ₂ film was eroded. However, Comparative Example 1, Ta-doped SnO ₂ film is lost more than half, whereas the portion transparent glass substrate is exposed has occurred, Example 1, Ta-doped SnO ₂ film is transparent glass substrate surface The entire coating was maintained. 6 is a cross-sectional SEM photograph of the substrate with the transparent conductive film after removing the bus electrode by nitric acid etching in Example 1. FIG. Also from FIG. 6, it can be confirmed that the Ta-doped SnO ₂ film maintains the state of covering the entire glass transparent substrate surface. From these results, in the case of Comparative Example 1, the Ta-doped SnO ₂ film is lost, and Ag ions in the silver paste are diffused into the glass transparent substrate from the portion where the glass transparent substrate is exposed, and yellowing occurs. It is thought that occurred.

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. 2009-187960 filed on Aug. 14, 2009, the contents of which are incorporated herein by reference.

According to the substrate with a transparent conductive film of the present invention, it is possible to prevent yellowing of the glass transparent substrate when a bus electrode is formed using a silver paste without performing a specific treatment on the glass transparent substrate. . In addition, since the PDP substrate of the present invention prevents yellowing of the glass transparent substrate, the PDP manufactured using the substrate is excellent in color display quality.

1: Glass transparent substrate 2: Transparent conductive film

Claims

A transparent conductive film-coated substrate in which a transparent conductive film mainly composed of tin oxide (SnO 2 ) is formed on a glass transparent substrate,
When the crystal peak of the SnO 2 (100) plane in the XRD peak of the transparent conductive film is Y and the background peak due to the glass transparent substrate is X, the peak intensity ratio Y / X is 1.5 or more and 1.8 or less. A substrate with a transparent conductive film.
2. The substrate with a transparent conductive film according to claim 1, wherein the transparent conductive film containing tin oxide as a main component contains 2.5 atomic% or less of tantalum (Ta) as a dopant in terms of element.
The substrate with a transparent conductive film according to claim 1 or 2, wherein the thickness of the transparent conductive film is 50 nm or more and 1 µm or less.
A transparent substrate with a conductive film manufacturing method according to claim 2, by a sputtering method, when forming the transparent conductive film mainly composed of tin oxide on a glass transparent substrate (SnO 2), tin oxide Production of a substrate with a transparent conductive film, characterized in that sputtering is carried out at a substrate temperature of 250 ° C. or more using a sputtering target containing 2.5 atomic% or less of tantalum (Ta) in terms of element as a main component. Method.
A silver paste containing bismuth-based glass frit is applied on the transparent conductive film of the substrate with a transparent conductive film according to any one of claims 1 to 3 and fired at a temperature of 500 to 600 ° C to thereby obtain a bath. A substrate for a plasma display panel (PDP) on which electrodes are formed.
When the crystal peak of the Bi 2 Sn 2 O 7 (222) plane in the XRD peak of the bus electrode is Z and the background peak due to the glass transparent substrate is X, the peak intensity ratio Z / X is 2 or more. The PDP substrate according to claim 5, wherein the substrate is a PDP substrate.