JPH01188660A - Manufacture of crystalline transparent electrical conductive laminated body - Google Patents

Abstract

PURPOSE:To obtain a crystalline transparent electrical conductive laminated body having extremely superior transparency and durability by laminating a crystalline transparent electrical conductive layer composed of a mixture of indium oxide and tin oxide on a substrate by a D.C. sputtering method under the conditions of the prescribed degree of vacuum and impressed voltage. CONSTITUTION:The conditions of <=5X10<-3>torr, preferably 1X10<-3>-5X10<-3> torr, degree of vacuum and >=380V, preferably 380-500V, target impressed voltage are set up, Then, under the above conditions, a crystalline transparent electrical conductive laminated body consisting of a mixture of indium oxide and tin oxide is formed on a substrate by a D.C. sputtering method. At this time, it is preferable to regulate the weight ratio of indium oxide to tin oxide to 80/20-99/1. Further, the preferred thickness of the above transparent conductive layer is 30-1500Angstrom . Since the crystalline electrical conductive layer is directly formed by a sputtering method according to this method, a broad crystalline transparent electrical conductive film with uniform quality can be continuously obtained with high productivity when an organic high polymer film substrate is used.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a crystalline transparent conductive laminate with excellent optical performance and durability, which is widely used as a transparent input keyboard and transparent electrode. be.

Transparent conductive laminates are widely used in applications that take advantage of their transparency and conductivity, particularly as movable switches such as transparent input keyboards for inputting data to electronic and electrical display elements. Moreover, among these, transparent conductive films having an organic polymer as a substrate allow devices to be made lighter and thinner than those having a glass substrate, and are more flexible and have excellent processability.

In addition, the manufacturing process has various advantages such as continuous production, so transparent electrodes for various display devices such as electrodes for liquid crystal displays, electrodes for plasma displays, and electrodes for electroluminescent devices are used. It is also widely used as

(Prior Art and Problems) A transparent conductive laminate is generally constructed by providing a conductive layer made of metal or metal oxide on a transparent substrate.

Conventionally known transparent conductive films include: - Metal thin films such as gold, silver, and palladium; - Indium oxide, tin oxide, indium-tin oxide (ITO), and cadmium-tin oxide (CTO). )
, metal oxide thin films such as zinc oxide (ZrlO), and multilayer thin films such as (2) and (2), but the metal oxide thin film (3) has better basic characteristics than other thin films. In particular, ITO films have particularly excellent transparency and conductivity, and are widely used as transparent conductive films.

Methods for forming the above-mentioned transparent conductive film include a vacuum deposition method, a sputtering method, an ion blasting method, a chemical spray method, a screen printing method, and the like.

Among these, the sputtering method is the most widely used film forming method because it allows continuous film formation on organic polymer films and has the advantage of having little compositional deviation even during long-term operation. There is one.

The ITO films formed by the above methods are roughly classified into acid-soluble amorphous ITO films and acid-refractory crystalline ITO films, depending on the formation conditions. At this time, since the crystalline ITO film is in a lower energy state than the amorphous ITO film, the rate at which the conductivity changes due to external factors tends to be small.

Also, for boat fishing, crystalline ITO films have better electrical conductivity than crystalline ITO films, and also have better optical properties such as light transmittance and hue.

However, ITO films formed on organic polymer substrates by sputtering are generally amorphous. This is because the heat resistance temperature of the organic polymer substrate is not very high (approximately 200'C or less), so in order to form an ITO layer without causing deformation of the substrate, the substrate temperature must be lowered. .

Therefore, conventional sputtering is used to deposit IT onto organic polymers.
Transparent switches using a transparent conductive film laminated with an O film have had major problems in durability such as key press durability and flexibility, and optical properties such as visible light transmittance and hue.

On the other hand, a method for forming a crystalline TO film that is superior to an amorphous ITO film in these properties is to form an ITO film at a substrate temperature of about 300'C or higher when using a normal glass substrate. is taken. Furthermore, for organic polymer substrates whose heat resistance is not so high, a two-step manufacturing process has conventionally been used in which a lower oxide film is formed by sputtering, and then a thermal oxidation treatment is performed in an oxygen atmosphere.

Therefore, forming a crystalline ITO film on an organic polymer substrate requires one more manufacturing process than forming a normal amorphous film. Moreover, in the thermal oxidation treatment process, a long treatment time is required because an amorphous film must be converted into a crystalline film without deforming the organic polymer substrate.

Therefore, this method has a problem in that the productivity of the crystalline film is considerably low.

(Objective of the Invention) The object of the present invention is to create a high-quality crystalline ITO layer with excellent transparency and durability, not only on glass substrates but also on organic polymer substrates, without requiring the conventional thermal oxidation process. It is an object of the present invention to provide a highly productive manufacturing method in which a crystalline ITO film is obtained in one step during sputtering.

(Structure of the Invention) The present invention provides a crystalline transparent conductive layer made of a mixture of at least indium oxide and tin oxide on a substrate with direct current (hereinafter referred to as D
In the manufacturing method of laminating layers by sputtering (denoted as C), the sputtering conditions are vacuum degree 5X10-3T.
The present invention relates to a method for manufacturing a crystalline transparent conductive laminate, characterized in that the applied voltage is 380 V or higher and 380 V or lower.

Although the sputtering apparatus used in the present invention is not particularly limited, the conditions for forming the crystalline conductive film differ depending on the target used as shown below.

The shape of the target used in the present invention is flat type,
Any shape, such as a cylindrical shape, may be used. However, when the substrate is an organic polymer film or the like, a flat target is most preferable because film formation is performed continuously while being wound up.

First, in the case of DC direct sputtering using an indium oxide-tin oxide target, the degree of vacuum during sputtering is 5×10 −3 Torr or less, and the target applied voltage is 480 V or more. More preferably, the degree of vacuum is 1X10-3Torr~1
xl 0'Tor r, and the target applied voltage is in the range of 480V to 600V.

At this time, if the degree of vacuum is less than 1.times.10@-3 Torr, the plasma stability of sputtering deteriorates.

Further, if the degree of vacuum is more than 5×10' orr, it becomes difficult to increase the voltage applied to the target, which is not preferable.

Furthermore, if the voltage applied to the target is 480 V or less, the effect of obtaining the crystalline oxide film of the present invention will not appear.

Further, if the voltage is 600 V or more, the plasma stability of sputtering becomes extremely poor, which is not preferable.

The voltage applied to the target in the present invention is usually much higher than the conditions for forming an amorphous ITO layer on an organic polymer substrate. FIG. 1 shows the characteristics of ITO films formed by varying the voltage applied to the target during DC direct sputtering. Unlike amorphous ITO films, crystalline IT0 films exhibit physical properties of being insoluble in acids;
= 1:4.25°C), the disappearance time (hereinafter referred to as acid resistance) of the ITO film is much longer than that of the amorphous film.

Therefore, IT formed with each target applied voltage shown in the figure
The acid resistance inflection point in the O film indicates that crystallization of the ITO film has occurred.

As shown in FIG. 1, as the voltage applied to the target during sputtering increases, the substrate temperature at which the crystalline ITO film is formed decreases. In other words, in the case of the DC direct sputtering method, when the target applied voltage is 480V or more,
A crystalline ITO layer can also be formed on a substrate that does not have a very high heat resistance temperature, such as an organic polymer.

Next, in the case of the DC reactive sputtering method using an indium-tin alloy target, the degree of vacuum during sputtering is 5x10'Torr or less, and the target applied voltage is 380V or more. More preferably, the degree of vacuum is 1 x 10-3Torr to 5 x 1O-3Torr.
and the target mark 710 voltage is 380V to 500V
is within the range of

At this time, if the degree of vacuum is less than 1.times.10@-3 Torr, the plasma stability of sputtering deteriorates. Further, if the degree of vacuum is 5×10' Torr or more, it is not preferable because it becomes difficult to increase the voltage applied to the target.

Furthermore, if the voltage applied to the target is 380 V or less, the effect of obtaining the crystalline ITO film of the present invention is not exhibited.

Moreover, if it is 500 V or more, the plasma stability of sputtering will be significantly deteriorated, which is not preferable.

Further, when the above method is combined with a magnetron sputtering method which has a high film forming speed, productivity is greatly improved.

The sputtering atmosphere gas in the present invention is preferably a mixed gas of an inert gas such as argon gas and oxygen gas. This is to more accurately control the oxidation state of the ITO film, which is a parameter, in order to obtain the best transparency and conductivity of the ITO film to be formed. At this time, the partial pressure of the oxygen scum is preferably -9= 50% or less. Furthermore, impurity gases such as hydrogen gas, nitrogen gas, and carbon gas may be mixed in to an extent that does not impair the transparency and conductivity of the ITO film to be formed.

In the case of an organic polymer substrate, the substrate temperature during sputtering in the present invention is a temperature at which the substrate does not deform (200°C).
It is necessary to set it to 130'C~1
A range of 80'C is preferred. However, if the substrate temperature rises significantly due to target applied voltage and film forming time, it is necessary to adjust the substrate temperature setting or cool the substrate so that the organic polymer substrate temperature does not exceed the above temperature.

Further, in the case of a glass substrate, the substrate temperature may be higher than the above-mentioned organic polymer substrate.

The conductive layer used in the present invention is a layer consisting of at least indium oxide and tin oxide, and particularly preferably the weight ratio of indium oxide/tin oxide is 80/20 to 99/1. Further, the layer may contain impurities such as hydrogen and fluorine to an extent that does not impair the transparency and conductivity of the conductive layer.

The thickness of the transparent conductive layer used in the present invention is 30 to 150 mm.
It is preferably 0 people, and more preferably 50 to 1000 people. Furthermore, the most preferable thickness is 100 to 400 people. At this time, if it is less than 30 Å, sufficient conductivity cannot be obtained and the durability of the conductive layer will be poor, which is not preferable.

Further, if the thickness is 1500 Å or more, the transparency of the conductive layer deteriorates, which is not preferable.

For the substrate used in the present invention, transparent materials such as glass and organic polymers are used. Examples of glass substrates include soda lime glass, lead glass, borosilicate glass,
High silicate glass, alkali-free glass, etc. are rejected. Among them, borosilicate glass and alkali-free glass are most suitable.

Examples of organic polymer substrates include polyester resin films such as polyethylene terephthalate and polyethylene naphthalate, styrene resin films such as AB and ABS, polyolefin resin films such as polyethylene and polypropylene, fluorine resin films, In addition, plastic resin films such as polyether sulfone, polyphenylene oxide, polyether ether ketone, etc., as well as epoxy resins, diaryl phthalate resins,
Thermosetting resin films such as diethylene glycol, bis-allyl carbonate resin, urethane resin, silicon resin, unsaturated polyester resin, phenol resin, urea resin, etc., and polyvinyl alcohol, polyacrylonitrile, polyurethane, aromatic polyamide, polyimide resin Examples include casting films of solvent-soluble resins such as. Among them, polyethylene terephthalate film has excellent optical durability and is the most suitable.

Further, the organic polymer film used may have a thickness that allows continuous production, and the thickness is 12 μm to 500 μm.
The thickness is preferably 50 μm to 200 μm, and more preferably 50 μm to 200 μm.

Furthermore, an intermediate layer may be provided on one or both surfaces of the above-mentioned substrate to improve adhesion to the conductive layer, and a treated layer may be further provided to improve slipperiness.

(Effects of the Invention) The present invention has made it possible to produce a crystalline transparent conductive laminate using a sputtering method that has transparency and durability that are extremely superior to conventional amorphous ITO films. Moreover, since the present invention directly forms a crystalline conductive layer using a sputtering method, when an organic polymer film substrate is used, a wide crystalline transparent conductive film of uniform quality can be continuously produced. A very productive process was obtained.

(Example) Example 1 After mounting a biaxially stretched polyester film (thickness 125 μm) on a magnetron high speed sputtering device,
The pressure was reduced to 100 ml. After that, argon gas (purity 99.9999% or more) and oxygen gas (purity 99.99%)
% or more) and introduced to a vacuum pressure of 410-3 Torr, In2O3/S n 02 = 90/
DC magnetron direct sputtering was performed using a 10 indium-tin oxide target. The sputtering conditions are: target applied voltage of 530V, substrate temperature of 170°C.
Furthermore, the partial pressure of argon gas/oxygen gas was determined so that the conductive film properties would be the lowest in resistance, highest in transparency, and samples having the characteristics shown in Table 1 were obtained.

When the crystallinity of the obtained sample was examined by X-ray diffraction, it was found to be crystalline, excellent in transparency, and good in appearance with no deformation of the polyester film substrate. In addition, the flexibility of the ITO film (bending out of the conductive plane with a 2 mmφ iron rod 1
The resistance increase (resistance increase around 0 seconds) was about 5 times that of the amorphous film, which was extremely superior to that of the amorphous film.

Comparative Example 1 DC magnetron direct sputtering was performed in the same procedure as in Example 1.

As a sputtering condition, the target applied voltage was set to 35
The 0V substrate temperature was set at 170'C, and the argon gas/oxygen gas partial pressure was determined so that the conductive film properties were the lowest in resistance, highest in transparency, and samples having the characteristics shown in Table 1 were obtained.

When the crystallinity of the obtained sample was examined by X-ray diffraction, it was found to be amorphous, and the flexibility of the ITO film was about 200 times higher, which caused problems in terms of durability.

(continued on next page) 15 Example 2 After a biaxially stretched polyester film (thickness: 125 μm) was installed in a continuous winding type reactive DC high-speed sputtering device, it was placed in a vacuum chamber to remove outgassing from the film. Rewind the film with 2. within the entire film roll range.
The pressure was reduced to 0x10-5 Torr. After that, a mixture of argon gas (purity of 99°9999% or more) and oxygen gas (purity of 99.99% or more) is pumped under a vacuum pressure of 3 x 10"
DC magnetron reactive sputtering was performed using an indium-tin alloy target plate with In/5n=90/10.

As sputtering conditions, the target applied voltage was set to 44
By setting the substrate temperature to 0V and 140'C, and determining the partial pressure of argon gas/oxygen gas so that the conductive film had the lowest resistance and highest transparency, samples having the characteristics shown in Table 2 were obtained. . When the crystallinity of the obtained sample was examined by X-ray diffraction, it was found to be crystalline, excellent in transparency, and good in appearance with no deformation of the polyester film substrate. Moreover, the flexibility of the ITO film was about four times that of the amorphous film, and was extremely superior to that of the amorphous film.

Comparative Example 2 DC magnetron reactive sputtering was performed in the same procedure as in Example 2.

As sputtering conditions, the target applied voltage was set to 34
The temperature of the substrate was set to 0V and 140'C, and the partial pressure of argon gas/M elementary gas was determined so that the conductive film had the lowest resistance, highest transparency, and a sample having the characteristics shown in Table 2 was obtained. Ta.

When the crystallinity of the obtained sample was examined by X-ray diffraction, it was found to be amorphous, and the flexibility of the ITO film was about 200 times higher, which caused problems in terms of durability.

(continued on next page)

[Brief explanation of the drawing]

FIG. 1 shows the relationship between target applied voltage and substrate temperature at which crystallization occurs in the DC magnetron direct sputtering method carried out in Example 1 and Comparative Example 1. FIG. 2 shows the X-ray diffraction pattern of Example 2. FIG. 3 shows the X-ray diffraction pattern of Comparative Example 2.

Claims (1)

[Claims] In a manufacturing method in which a crystalline transparent conductive layer made of a mixture of at least indium oxide and tin oxide is laminated on a substrate by direct current sputtering, the sputtering conditions are such that the degree of vacuum is 5×10^-^3 Torr or less. The applied voltage is 38
A method for producing a crystalline transparent conductive laminate, characterized in that the voltage is 0V or more.