WO2007142043A1

WO2007142043A1 - Transparent conductive film, process for producing the same, and sputtering target for use in the production

Info

Publication number: WO2007142043A1
Application number: PCT/JP2007/060615
Authority: WO
Inventors: Hidefumi Odaka; Akira Mitsui
Original assignee: Asahi Glass Company, Limited
Priority date: 2006-06-06
Filing date: 2007-05-24
Publication date: 2007-12-13
Also published as: JP2009205799A; TW200807449A

Abstract

A transparent conductive film which has high resistance to erosion by a glass frit and suffers no increase in electrical resistance even when burned in the state of being in contact with a glass frit; and a process for producing the film. The transparent conductive film comprises tin oxide as the main component, and is characterized in that the transparent conductive film contains one or more elements selected from the group consisting of tungsten, tantalum, niobium, molybdenum, and bismuth as a dopant and substantially contains neither antimony nor indium. It is further characterized in that when the total amount of the element(s) contained as a dopant in the transparent conductive film is expressed by MA and the amount of tin element contained in the transparent conductive film is expressed by Sn, the film satisfies the following relationships (1) and (2). 0.8<(Sn)/(Sn+MA)<1.0 (1) 0.01<(MA)/(Sn+MA)<0.2 (2)

Description

Specification

Transparent conductive film, method for producing the same, and sputtering target used for the production thereof

Technical field

TECHNICAL FIELD [0001] The present invention relates to a transparent conductive film suitably used for a transparent electrode of a flat panel display (FPD), a manufacturing method thereof, and a sputtering target used in manufacturing the transparent conductive film. .

Background art

In FPD, ITO (tin-doped indium) has been widely used as a transparent conductive film forming a transparent electrode (see Patent Document 1). This is because ITO has high electrical conductivity and visible light transmittance. In the FPD manufacturing process, there may be a process of firing at a temperature of 350 ° C or higher. For example, in the firing process of the plasma display panel (PDP) manufacturing process, the transparent electrode is exposed to a high temperature of about 600 ° C. while being in contact with the glass frit. However, ITO is generally poor in heat resistance, and there is a problem that if it is in contact with a glass frit, firing at a temperature of 350 ° C. or more may significantly increase the electrical resistance. There was also a problem in terms of reserves of raw materials (eg indium).

[0003] On the other hand, tin oxide (SnO) is generally resistant to glass frit, which has high chemical durability.

2

High erosion can be expected. In particular, if a transparent conductive film in which antimony is added to tin oxide as a dopant is used as a transparent electrode, an erosion-resistant strong transparent electrode can be produced, and it is expected to be a transparent electrode for PDP. Patent Document 1 proposes a patterning method of tin oxide by a lift-off method, and a PDP transparent electrode can be formed by combining with such patterning technology.

Patent Document 1: Japanese Patent Laid-Open No. 6-280055

Disclosure of the invention

Problems to be solved by the invention

[0005] However, tin oxide provided with antimony as a dopant is not as good as ITO.

Since 1S glass frit causes erosion, the transparent electrode is in contact with the glass frit. In this state, there was a problem that the electrical resistance increased when firing at a temperature of 350 ° C or higher. Antimony is highly toxic and should not be used as much as possible.

[0006] The present invention provides a transparent conductive film that has strong resistance to erosion of a glass frit and does not increase in electrical resistance even when fired in contact with the glass frit, and a method for producing the same. Objective. Another object of the present invention is to provide a display member using such a transparent conductive film as a transparent electrode.

Another object of the present invention is to provide a sputtering target suitable for forming the transparent conductive film using a sputtering method, particularly a DC sputtering method. Means for solving the problem

[0007] In order to achieve the above object, the present invention provides a transparent conductive film containing tin oxide as a main component, and the transparent conductive film is selected from tungsten, tantalum, niobium, molybdenum, and a group force having a bismuth force. At least one element as a dopant, substantially free of antimony and indium,

M is the total amount of the elements contained as a dopant in the transparent conductive film,

A

Provided is a transparent conductive film characterized by satisfying the following formulas (1) and (2) when Sn is an amount of tin element contained in an electric film.

0.8 <(Sn) / (Sn + M) <1. 0 (1)

A

O. Ol <(M) / (Sn + M) <0.2 (2)

A A

[0008] The transparent conductive film of the present invention has a specific resistance value P of the transparent conductive film after heating to a temperature of 350 ° C or higher in contact with the glass frit, and a specific resistance of the transparent conductive film before heating. With value p

It is preferable to satisfy the following formula (3) when 10 is satisfied.

P ≤ '' (3)

Ten

The transparent conductive film of the present invention preferably has the specific resistance value ρ force 力 −2 Ωcm or less.

0

Yes.

The transparent conductive film of the present invention preferably has a specific resistance value p force of −2 Ωcm or less.

The transparent conductive film of the present invention preferably has a film thickness of 1 μm or less.

[0010] The present invention also provides a display member having the transparent conductive film of the present invention. [0011] Further, the present invention is a sputtering target mainly composed of tin oxide, wherein the sputtering target is at least one element selected from the group power of tungsten, tantalum, niobium, molybdenum and bismuth as dopants. The total amount of the elements contained as dopants in the sputtering target is M, and the sputtering phosphorus

A

A sputtering target characterized by satisfying the following formulas (4) and (5), where Sn is the amount of tin element contained in the target.

0. 8 <(Sn) / (Sn + M) <1. 0 (4)

A

0. 01 <(M) / (Sn + M) <0.2

A ... (5)

A

[0012] The sputtering target of the present invention preferably contains niobium as a dopant.

The sputtering target of the present invention containing niobium as a dopant has a relative density of 60

It is preferable that the sheet resistance value of the surface is 9% + 6Ω or less.

[0013] The present invention also provides a method for producing a transparent conductive film, which forms the transparent conductive film of the present invention described above by a sputtering method using the sputtering target of the present invention described above.

The invention's effect

[0014] The transparent conductive film of the present invention does not increase in electrical resistance even when fired at a temperature of 350 ° C or higher in contact with the glass frit having high erosion resistance to the glass frit. For this reason, it is suitable as a transparent electrode of FPD such as PDP, which includes a step of baking at a temperature of 350 ° C. or higher during the manufacturing process.

Since the transparent conductive film of the present invention does not contain expensive indium, the transparent conductive film can be provided at low cost. In addition, because it does not contain toxic antimony, it is also environmentally superior. In the PDP manufacturing process, the transparent electrode is baked and bonded to a dielectric called glass frit at a temperature of about 500 to 600 ° C. At this time, the transparent conductive film V used as the transparent electrode has low erosion resistance against the glass frit, and fine bubbles are generated in the glass frit or the transparent conductive film, or both. The generation of such fine bubbles is a serious problem that leads to defective PDP images. The transparent conductive film of the present invention uses tandasten, tantalum, niobium, molybdenum, and bismuth, which are dopants that have better erosion resistance to glass frit than antimony. G has the effect of reducing the generation of fine bubbles.

The sputtering target of the present invention is suitable for producing the transparent conductive film of the present invention. In particular, since the sputtering target of the present invention containing niobium as a dopant has a high sintered density, a DC sputtering method can be used, which contributes to improving the productivity of the transparent conductive film.

BEST MODE FOR CARRYING OUT THE INVENTION

[0015] The transparent conductive film of the present invention contains tin oxide as a main component, and contains at least one element selected from the group force of tungsten, tantalum, niobium, molybdenum and bismuth as a dopant, and substantially contains antimony and indium. Not included. “Containing tin oxide as a main component” means that 80 atomic% or more of tin oxide is contained in the film in terms of tin element.

The transparent conductive film of the present invention is characterized in that the following formulas (1) and (2) are satisfied when the total amount of elements such as tungsten contained as a dopant is M and the amount of tin element is Sn.

A

0. 8 <(Sn) / (Sn + M) <1. 0---(1)

A

0. 01 <(M) / (Sn + M) <0.2 (2)

A A

[0016] The present inventors have found that a film having the above composition is more resistant to erosion against glass frit than a tin oxide film containing antimony as a dopant, which has been used conventionally. Here, the erosion resistance with respect to the glass frit is to the extent that it does not become a problem as a product when it is in contact with the glass frit and kept under a high temperature, for example, when heated to a temperature of 350 ° C or higher. It means that it is not easily eroded by glass frit.

The difference in erosion resistance to glass frit is thought to be related to the stability of these dopants in the tin oxide film. Antimony is present in the tin oxide film with a valence of 5 or 3. Antimony with a valence of 5 is located at the position of tin in the crystal lattice and contributes to the conductivity of the tin oxide film. Heating above 350 ° C in contact with the glass frit changes the antimony valence from 5 to 3. Antimony having a valence of 3 escapes from the tin position of the crystal lattice and shifts to the interstitial position, causing formation of a compound with the elements constituting the glass frit. As a result of the formation of a compound between antimony having a valence of 3 and the elements constituting the glass frit at the interstitial positions, the electrical properties of the tin oxide film The resistance is thought to increase. Such a series of actions is the erosion action by the glass frit. Indium has a valence of 3 and exists at the position of the tin atom in the tin oxide crystal lattice. Therefore, it acts as an acceptor that absorbs carriers (electrons) in the film, and the presence thereof tends to increase the electric resistance value of the tin oxide film. Even when interstitial sites (locations) are present, impurity levels in the band gap are formed, which causes a decrease in mobility and a decrease in carrier density. Therefore, unlike antimony, indium inhibits the electrical properties of highly crystalline tin oxide films, regardless of their position in the crystal.

On the other hand, tantalum exists in tin oxide with a valence of 5 or 4! /. The tantalum with a valence of 5 is located at the position of tin in the crystal lattice and contributes to the conductivity of the tin oxide film. When the tantalum valence is changed from 5 to 4 by the same action as described above, the tantalum having the valence of 4 slips from the tin position of the crystal lattice and shifts to the interstitial position. It becomes a cause of forming a compound with the elements constituting the frit. It is considered that the electric resistance of the tin oxide film is increased as a result of the formation of a compound between the valence 4 tantalum and the elements constituting the glass frit.

However, with tantalum, the valence change (5 → 4) is less likely to occur than antimony (5 → 3). For this reason, the electrical resistance of the tin oxide film, which is difficult to be eroded by the glass frit, hardly increases.

In addition, the tantalum valence changes from 4 to 5 by heating to a temperature of 350 ° C or higher. As a result, tantalum having a valence of 5 enters the position of tin in the crystal lattice, and the electrical resistance of the tin oxide film is considered to decrease.

[0018] The force described above for the tin oxide film doped with tantalum has the same effect when doped with tungsten, niobium, molybdenum, or bismuth. Excellent erosion resistance.

In addition, the transparent conductive film of the present invention is characterized by substantially not containing antimony and indium. Since the pentavalent state is substantially free of unstable antimony at high temperatures, it is possible to prevent an increase in the resistance value after firing, and when considering use as a transparent electrode for PDP, glass frit It is preferable because it has the effect of excellent erosion resistance against Good. When heated to temperatures above 350 ° C in contact with the glass frit, the valence of antimony changes from 5 to 3. This is because antimony having a valence of 3 escapes from the position of tin in the crystal lattice and shifts to the interstitial position, causing formation of a compound with the elements constituting the glass frit. In addition, since it does not substantially contain antimony, an environmentally friendly transparent conductive film can be provided, and the electrical resistance does not increase even when heated to a temperature of 350 ° C. or higher. ,.

Here, the transparent conductive film substantially free of antimony and indium means that the transparent conductive film is formed without using a sputtering target that actively contains antimony or indium. It means that it contains no antimony or indium other than the resulting antimony and indium. Specifically, it means that the amount of antimony element contained in the transparent conductive film is 0.1 atomic% or less with respect to the amount of tin element, and the amount of indium element contained in the transparent conductive film is It means 0.1 atomic% or less with respect to the amount of.

[0019] In the transparent conductive film of the present invention, the specific resistance value P of the transparent conductive film after being heated to a temperature of 350 ° C or more in contact with the glass frit, the specific resistance of the transparent conductive film before being heated When the value is p, it is preferable to satisfy the following formula (3).

0

P ≤ P · '· (3)

Ten

That is, when the transparent conductive film of the present invention is heated to a temperature of 350 ° C. or higher in contact with the glass frit, the electrical resistance of the transparent conductive film does not increase but rather decreases. The reason for the decrease in electrical resistance is that immediately after deposition, the dopant (Tungsten, Tantalum, Niobium, Molybdenum or Bismuth) force that existed at the position of the tin oxide crystal lattice entered the tin position of the crystal lattice by heating, and the It is estimated that the density increased and the number of electron scatterers decreased.

Therefore, when the transparent conductive film of the present invention is used as a transparent electrode for an FPD such as a PDP, the transparent conductive film is subjected to a baking process at a temperature of 350 ° C. or higher performed in the FPD manufacturing process. The electrical characteristics of the are improved.

[0020] The transparent conductive film of the present invention preferably has a specific resistance value p force Ε-2 Ωcm or less.

1

“E−2” means 10 to the power of 2−. Such a notation is not The same applies to the resistance value. The specific resistance value _P is 350 ° C, which is implemented in the FPD manufacturing process.

1

It corresponds to the specific resistance value of the transparent conductive film after the baking process at the above temperature. Specific resistance value Force E—If the thickness is 2 cm or less, the electrical resistance of the transparent conductive film is sufficiently low.

1

It is suitable for the transparent electrode. The specific resistance value p is more preferably 1E—2 Ωcm or less.

1

More preferably, it is 0.5E−2 Ωcm or less.

The transparent conductive film of the present invention preferably has a specific resistance value p force E−2 Ωcm or less.

0

Specific resistance value / 0 force E—If it is 2 Ωcm or less, 350 ° C or more, which is performed in the FPD manufacturing process.

0

The specific resistance of the transparent conductive film after the baking process at the above temperature is 4E-2 Ωcm or less.

1

It ’s a lot. The specific resistance value / 0 is more preferably 4E—2 Ω cm or less 1Ε—2 Ω «η or less

0

More preferably, it is below.

[0022] The transparent conductive film of the present invention preferably has a thickness of 1 μm or less. If the film thickness is less than or equal to L m, the transparent conductive film does not have an optical defect such as haze. The thickness of the transparent conductive film is more preferably 0.3 μm or less, and further preferably 0.2 μm or less, and more preferably 0.02 ^ m or more. The film thickness hardly changes before and after firing.

[0023] The transparent conductive film of the present invention is preferably excellent in transparency. Specifically, the visible light transmittance (measured from JIS-R3106 (1998)) is preferably 80% or more, more preferably 85% or more. The visible light transmittance (measured from JIS-R3106 (1998)) after applying glass frit and baking is preferably 80% or more, more preferably 85% or more! /.

In order to further reduce the specific resistance value p, the transparent conductive film of the present invention has the following formulas (6), (

0 1

It is preferable to satisfy 7).

0. 85 <(Sn) / (Sn + M) <1. 0 (6)

A

0. 01 <(M) / (Sn + M) <0.15 (7)

A A

M and Sn in formulas (6) and (7) have the same meanings as in formulas (1) and (2).

A

[0025] For the formation of the transparent conductive film of the present invention, various film formation methods such as sputtering, CVD, sol-gel, and PLD can be used. From the viewpoint of large area uniformity and productivity, the sputtering method is used. It is desirable to use As a sputtering method, even when a target having a low sintered density is used, a high sheet resistance value that does not cause the target to be damaged is used. RF sputtering is preferred because it can be discharged even with one get.

When the transparent conductive film of the present invention is formed by sputtering, a metal-based target mainly composed of tin and an oxide-based target (oxide sintered body target) mainly composed of tin oxide are used. it can. However, in film formation using a metal target, it is difficult to form a thin film by power control, and the electrical resistance of tin is very sensitive to oxygen partial pressure. There is a problem that it becomes necessary. On the other hand, when an oxide-based target is used, the above-mentioned problem does not occur and film formation with high productivity can be realized.

As an oxide-based target, tin oxide is the main component, and the dopant of the transparent conductive film, that is, at least one element selected from the group power consisting of tungsten, tantalum, niobium, molybdenum and bismuth is used as the dopant. It is possible to use an oxide-containing sintered body target.

When the sputtering method is performed using such an oxide sintered body target, the composition of the obtained thin film and the composition of the acid oxide sintered body target substantially coincide. Therefore, in order to form the transparent conductive film of the present invention by a sputtering method, the total amount of elements such as tungsten contained as a dopant is set to M, and the amount of tin element is set as the above oxide sintered body target. When Sn is used, a material satisfying the following formulas (4) and (5) may be used.

A

0. 8 <(Sn) / (Sn + M) <1. 0 (4)

A

0. 01 <(M) / (Sn + M) <0.2 (5)

A A…

In addition, it is preferable that the oxide-ceramic sintered body target of the present invention substantially does not contain antimony and indium! /. Does not contain antimony! /, Which increases the safety of target production. By not containing indium, there is an effect that the conductivity of the target is not lowered. The meaning of “V substantially free of antimony and indium” is as described above for the transparent conductive film.

In addition, when forming the transparent conductive film of the present invention that satisfies the above formulas (6) and (7), a material that satisfies the following formulas (8) and (9) is used as the oxide sintered body target. Goodbye!

0. 85 <(Sn) / (Sn + M) <1. 0 · · · (8)

A

0. 01 <(M) / (Sn + M) <0.15 (9) Here, M and Sn in formulas (8) and (9) have the same meanings as in formulas (4) and (5).

A

[0026] The above-described thread-combined oxide-ceramic sintered body target can be produced by a normal procedure for producing a sputtering target. That is, the raw materials are blended so as to have a desired composition ratio, and after pressure molding, they are sintered in an air atmosphere at a high temperature (eg, 1100 ° C.) and atmospheric pressure.

[0027] In the oxide-ceramic sintered body target satisfying the above formulas (4) and (5), when the element contained as a dopant is niobium, the present inventors have increased the sintering density of the target. We have found that a target that can be used in the DC sputtering method can be obtained.

Here, the oxide-ceramic sintered compact target containing niobium as a dopant is represented by the following formulas (10) and (11) when the amount of niobium element contained as a dopant is Nb and the amount of tin element is Sn. Fulfill.

0. 8 <(Sn) / (Sn + Nb) <1. 0

0. 01 <(Nb) / (Sn + Nb) <0.2 (11)

An oxide sintered compact target satisfying the above formulas (10) and (11) has a relative density of 60% or more, and the sheet resistance value on the target surface is 9 mm + 6 Ω or less. It can be preferably used as a target for talling. Note that the use of the DC sputtering method instead of the RF sputtering method as the sputtering method is important because it makes it possible to drastically increase the deposition rate, and whether or not commercialization is possible. One of the elements. Here, the acid sinter sintered body target may contain a dopant other than niobium (tungsten, tantalum, molybdenum, or bismuth).

In this specification, the relative density can be obtained by the following formula (12).

Relative density (%) = (bulk density Z true density) X 100---(12)

Here, the bulk density (gZcm ³ ) is the actual density obtained by measuring the size and weight force of the fabricated target, and the true density is the theoretical density obtained by calculating the theoretical density force specific to the substance. is there.

More preferably, the element contained as the dopant is niobium, and the relative density of the oxide sintered compact target satisfying the above formulas (10) and (11) is 80% or more.

In addition, the above-mentioned formula (6), ( In order to form the transparent conductive film of the present invention that satisfies 7), a material satisfying the following formulas (13) and (14) may be used as the oxide sintered body target.

0. 85 <(Sn) / (Sn + Nb) <1. 0

0. 01 <(Nb) / (Sn + Nb) <0. 15 (14)

Here, Nb and Sn in formulas (13) and (14) have the same meanings as in formulas (10) and (11).

[0028] The display member of the present invention is used as an FPD substrate such as a PDP, in particular, as a front substrate of an FPD, and the transparent conductive film of the present invention described above is used as a transparent electrode on a glass substrate. It is formed.

A glass substrate is not specifically limited, For example, conventionally well-known various glass substrates (Soda lime glass, an alkali free glass, etc.) can be used. One preferred embodiment is a high strain point glass for PDP. Also, the size and thickness are not particularly limited. For example, lengths of about 400 to 3000 mm can be preferably used as the vertical and horizontal lengths. The thickness is preferably 0.7-3. Omm. 1.5-3. Omm is more preferred.

The display member of the present invention can be used as various FPD substrates in addition to the PDP. Specific examples of such an FPD include a liquid crystal display (LCD), an organic EL (FED), and the like.

Example

[0029] The following description is based on examples and comparative examples. This embodiment is merely an example and is not limited by these. In other words, the comprehensive scope of the present invention is defined by the scope of the claims, and includes various modifications other than the embodiments described below.

[0030] (Examples 1 to 4)

Of SnO, Ta O, WO, Mo O, Nb O with a purity equivalent to 99.99% and a particle size of 5 μm or less

2 2 5 3 2 3 2 5 Using the powder, the powder was prepared so that the composition ratio of the metal elements would be the composition ratio shown in Table 1, respectively. The powder was mixed using a mortar, press-molded, and then sintered in air at 1530 ° C under atmospheric pressure. This oxide-sintered body was machined into a target shape. Obtained Table 1 shows the relative density and surface resistance (surface sheet resistance value) of the sintered oxide target. The relative density of the target was calculated using the following formula (12). The sheet resistance value on the surface of the target was measured using a surface resistance measuring device (Mitsubishi Yuka: Loresta).

Relative density (%) = (bulk density Z true density) X 100---(12)

Next, a high strain point glass (made by Asahi Glass Co., Ltd .: PD200, the visible light transmittance of the substrate is 91%) having a thickness of 2.8 mm was prepared as a glass substrate. After the glass substrate was washed, it was set on the substrate holder. An oxide sintered compact target having the composition shown in Table 1 was attached to a force sword of an RF sputtering device. After the film formation chamber of the sputtering apparatus was evacuated to vacuum, a film mainly composed of tin oxide having a thickness of about 150 nm (0.15 m) was formed on the glass substrate by RF sputtering. A mixed gas of argon and oxygen was used as the sputtering gas. The substrate temperature was 250 ° C. The pressure at the time of film formation was 0.5 Pa. By changing the flow ratio of argon gas and oxygen gas, a transparent thin film with low electrical resistance could be formed. Table 2 shows the film composition, visible light transmittance, and specific resistance values obtained by adjusting the gas ratio so that the electric resistance is minimized. The composition of the film, the visible light transmittance, and the specific resistance value) were measured by the following methods.

0 1

(1) Composition: A 300 nm film was formed under the same process conditions used for film formation on a glass substrate. The amount of fluorescence emitted from a metal element was measured with a fluorescent X-ray apparatus (RIX3000 manufactured by Rigaku Corporation), and the amount and composition ratio of each metal element were calculated by theoretical calculation of Fundamental Parameter. The composition was the same even after firing.

(2) Visible light transmittance: According to JIS-R3106 (1998), using a spectrophotometer (manufactured by Shimadzu Corporation: U-4100), the transmission spectrum of the obtained film-coated glass substrate Visible light transmittance was calculated.

(3) Specific resistance value: It was determined by the van 'del' Paul method using a Hall effect measuring device (HL5500PC, Accent Optical Technology Ichi Co., Ltd.). About specific resistance of membrane Apply a glass frit (made by Asahi Glass Co., Ltd., glass paste, AP5655AE (YPT 065F)), which is mainly used for plasma TV front plates and mainly composed of silicon oxide, lead oxide and boron oxide, It was also measured at 600 ° C for 1 hour. In Table 2, p is the specific resistance value of the unfired film, and is the specific resistance value of the film after baking.

0 1

As is apparent from Table 2, the specific resistance values of the films of Examples 1 to 4 do not increase even when fired at a high temperature of 600 ° C. while being in contact with a frit material having strong acidity. High electrical conductivity was confirmed.

It should be noted that the visible light transmittance after applying the glass frit and firing is 80% or more in all examples.

(Example 5)

Use SnO, NbO powder with a purity of 99.99% and a particle size of 5 μm or less.

2 2 5

Powders were prepared so as to have the composition ratio to be mounted, and oxide sintered compact targets were prepared in the same procedure as in Examples 1 to 4. Table 1 shows the relative density and surface resistance (sheet resistance value of the target surface) of the obtained sintered oxide target. As shown in Table 1, the oxide sintered compact target (containing niobium as a dopant) satisfying the above formulas (10) and (11) has characteristics suitable as a target for DC sputtering. That is, the relative density force of the target is 0% or more, and the sheet resistance value of the target surface is 9Ε + 6 ΩΖ or less. Using the obtained oxide-ceramic sintered compact target, a thin film was formed in the same procedure as in Examples 1 to 4, and the film composition, visible light transmittance, specific resistance value, It was measured.

0 1

However, the DC sputtering method was used instead of the RF sputtering method to form the thin film. In other words, the obtained oxide-ceramic sintered compact target was attached to a force sword of a DC magnetron sputtering apparatus, the film formation chamber of the sputtering apparatus was evacuated to a vacuum, and then oxidized by a DC sputtering method with a thickness of about 150 nm. A film containing tin as a main component was formed on a glass substrate.

The deposition rate at this time is about twice as fast as when RF sputtering is used, which is excellent for industrial production. A mixed gas of argon and oxygen was used as the sputtering gas. The substrate temperature was 250 ° C. The pressure at the time of film formation was 0.5 Pa. By changing the flow ratio of argon gas and oxygen gas, it is transparent and has low electrical resistance. A thin film could be formed. Table 2 shows the composition of the film, the visible light transmittance, and the specific resistance value obtained by adjusting the gas ratio so that the electric resistance is minimized. As is clear from Table 2, the film of Example 5 is in contact with the frit material having strong acidity, and does not increase in specific resistance even when baked at a high temperature of 600 ° C. It is certain that it exhibits electrical conductivity.

The film composition is the same even after firing, and the visible light transmittance after applying glass frit and firing is 80% or more.

[0032] (Comparative Example 1)

SnO with a purity equivalent to 99.99% and a particle size of 5 m or less

2. Use Sb O powder and record in Table 1 2 5

Powders were prepared so as to have the composition ratio to be mounted, and oxide sintered compact targets were prepared in the same procedure as in Examples 1 to 4. Table 1 shows the relative density and surface resistance (sheet resistance value of the target surface) of the obtained sintered oxide target.

Using the obtained oxide-ceramic sintered compact target, a thin film was formed in the same procedure as in Examples 1 to 4, and the film composition, visible light transmittance, specific resistance value, It was measured.

0 1

Table 2 shows the composition of the film, the visible light transmittance, and the specific resistance value obtained by adjusting the gas ratio of argon and oxygen so that the electric resistance is minimized. As is apparent from Table 2, the film formed using the tin oxide sintered target doped with antimony has a specific resistance value of about 10% lower than that of the unfired film when fired in a state where glass frit is applied. 1. It was confirmed that the number would increase to 8.

[0033] (Comparative Example 2)

An ITO thin film was formed in the same procedure as in Examples 1 to 4, using an ITO target (Tosoichi Specialty Materials Co., Ltd., indium oxide target with 10% by mass tin oxide dopant). When the resistivity p of the obtained ITO thin film was measured, 1.5E-4 Q cm

0

Met. When the glass frit was applied in the same procedure as in Examples 1 to 4 and baked at 600 ° C for 1 hour in an atmospheric atmosphere, the specific resistance p increased to about 6 times that of 9.5E. -Four

Ten

It became Ω cm. The specific resistance value p after firing of the films obtained in Examples 1 to 5 is 2.7E-3 Q c

1

m to 7.7E—3 Q cm, and the electrical characteristics of both films are close to each other under the actual PDP manufacturing process environment, and the transparent conductive film of the present invention can serve as an ITO alternative material. It shows.

[0034] (Comparative Example 3)

An acid oxide sintered compact target was produced in the same procedure as in Examples 1 to 4. However, the powder was prepared so as to have the composition ratio shown in Table 1. The relative density and surface resistance (sheet resistance value of the target surface) of the obtained oxide sintered compact target are as shown in Table 1.

0 1

Table 2 shows the composition of the film, the visible light transmittance, and the specific resistance value obtained by adjusting the gas ratio of argon and oxygen so that the electric resistance is minimized. As is apparent from Table 2, even if the film is formed using a tin oxide sintered compact target doped with tantalum, if the composition does not satisfy the formulas (1) and (2), the glass frit It was confirmed that the specific resistance value was increased when fired in a state where the coating was applied as compared with the unfired film.

[0035] [Table 1]

[0036] [Table 2]

Table 2: Film composition, visible light transmittance, specific resistance

Industrial applicability

The transparent conductive film of the present invention is excellent in transparency and conductivity, and the specific resistance value of the film does not increase even when it is baked in contact with a frit material having strong acidity. High electrical conductivity. Therefore, it is suitable as a transparent electrode for FPD. In addition, if laser patterning technology, which has been developed in recent years, is applied to this film, high-definition electrode patterns can be easily formed on glass, plastic substrates, film substrates, and crystal substrates. In addition, a transparent conductive film containing tin oxide as a main component and containing at least one element selected from the group power of tungsten, tantalum, niobium, molybdenum, and bismuth as a dopant is an element that is included in the thermal, chemical, and chemical elements. Therefore, when firing with glass frit applied, optical defects such as microbubbles are generated compared to transparent conductive films containing tin oxide as the main component and antimony as a dopant. There is also an effect to suppress. It should be noted that the entire contents of the specification, patent claims, drawings and abstract of Japanese Patent Application 2006-157515 filed on June 6, 2006 are incorporated herein by reference. It is something that is incorporated.

Claims

The scope of the claims

[1] A transparent conductive film mainly composed of tin oxide,

The transparent conductive film contains at least one element selected from the group force consisting of tungsten, tantalum, niobium, molybdenum, and bismuth as a dopant, and is substantially free of antimony and indium.

A

A transparent conductive film characterized by satisfying the following formulas (1) and (2), where Sn is the amount of tin element contained in the electric film.

0.8 <(Sn) / (Sn + M) <1. 0 (1)

A

0. 01 <(M) / (Sn + M) <0.2 (2)

A A

[2] When the specific resistance value P of the transparent conductive film after heating to a temperature of 350 ° C. or more in contact with the glass frit and the specific resistance value p of the transparent conductive film before heating are given by the following formula: (3)

Ten

2. The transparent conductive film according to claim 1, wherein the transparent conductive film is satisfied.

P ≤ '' (3)

Ten

[3] The specific resistance value according to claim 1 or 2, wherein the specific resistance value ρ force Ε—2 Ωcm or less.

0

The transparent conductive film described.

[4] The specific resistance value is 4E—2 Ωcm or less.

1

The transparent conductive film according to any one of the above.

[5] The transparent conductive film according to any one of claims 1 to 4, wherein the film thickness of the transparent conductive film is: m or less.

[6] Claim 1! A member for display having the transparent conductive film according to any one of 5.

[7] A sputtering target mainly composed of tin oxide,

The sputtering target contains at least one element selected from the group force of tungsten, tantalum, niobium, molybdenum and bismuth as a dopant, and the total amount of the elements contained as a dopant in the sputtering target is M.

A

The sputtering target characterized by satisfying the following formulas (4) and (5) when the amount of tin element contained in the sputtering target is Sn.

0. 8 <(Sn) / (Sn + M) <1. 0 (4)

0. 01 <(M) / (Sn + M) <0. 2… (5)

A A

8. The sputtering target according to claim 7, wherein niobium is included as the dopant.

[9] The sputtering target according to [8], wherein the sputtering target has a relative density of 60% or more and a surface sheet resistance value of 9E + 6ΩZ or less.

[10] A method for producing a transparent conductive film, wherein the transparent conductive film according to any one of claims 1 to 5 is formed by a sputtering method using the sputtering target according to any one of claims 7 to 9.