JPS6179647A - Manufacture of transparent conductive laminate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application] The present invention relates to a method for manufacturing a conductive laminate, and more specifically to a method for forming a transparent conductive layer containing mainly indium oxide on an organic polymer molded product by a sputter link method. Regarding.

[Prior Art] With the arrival of an advanced information society, there has been remarkable progress in parts and equipment that utilize the characteristics of both optics and electronics. Furthermore, with the rapid spread of microcomputers, innovations in computer peripherals have been remarkable. Transparent tablets are being developed as input devices for these computers. A transparent electrode using an organic polymer substrate is used as one form of this component, but this purpose requires higher durability and reliability than when used as a keyboard.

Further, the transparent electrodes are also used in liquid crystal displays, electroluminescent displays, etc. as output devices, and the durability and reliability of the transparent electrodes are similarly required for these purposes.

Transparent conductive housings include metal thin film (Atl, Pb, etc.) types, gold R oxide thin film types (ITO, CTo, etc.).

3n Oz, T! (Oz, etc.), multilayer thin film type (Ti
There are 1fi such as Ox /Ag/Ti Qx W), but they are transparent.

The metal oxide thin film type is superior in basic properties such as conductivity and mechanical properties. Among the gold-flexible oxide thin film types, I
To (Indium Tin Qxide) film has been attracting attention in recent years because it has particularly excellent transparency and 13-electroconductivity, and also has features such as easy electrode patterning (excellent etching properties). It's here.

The present inventors have already developed indium on organic polymer molded products.
We have proposed a method for forming a tin lower oxide film and then converting it into an ITO film.
2881. Showa 53-73397. (Sho 54-8670, etc.)

In addition, we would like to discover that when an indium-tin lower oxide film is formed by vacuum evaporation and then thermally oxidized, it is converted into a crystalline ITo film.

18 No. 8 pp. 440). By the way, although the above-mentioned crystalline ITO film is excellent in durability, there are some industrial problems because the indium tin lower oxide film is formed by vacuum evaporation. For example, (1) since the evaporation source is point-like, the range of uniform film thickness is narrow and it is difficult to form a film into a wide roll-shaped film;
(1) It is difficult to continuously supply the evaporation material, making it impossible to perform evaporation over a long period of time; (3) When using a two-component evaporation material, composition deviations may occur due to differences in vapor pressure. There are cases where this may occur.

On the other hand, recent advances in thin film formation technology have been remarkable, and it has become possible to form transparent conductive layers on organic polymer moldings that do not have much heat resistance. Among these, the sputtering method is one of the most used technologies, as it has the advantages of being able to form films over a long period of time, having no compositional deviation even after long periods of film formation, and being easy to widen the film width. . And the above-mentioned ITOF
It is also known to form J by a sputtering method.

Therefore, the present inventors applied ITOI to an organic polymer molded product using a sputtering method. was developed and its practicality was evaluated.

However, the conductive laminate formed by forming ITO151 by sputtering has a large change in resistance over time, and
It has been found that there is a serious practical drawback in that the durability is extremely poor when used as a transparent switch.

[Object of the Invention 1] The present invention was made in view of the current situation, and its object is to provide a method for manufacturing a conductive laminate using a sputtering method that is excellent in durability and reliability.

[Structure of the Invention] The above object is achieved by the present invention as described below. In other words,
The present invention relates to a method for manufacturing a conductive laminate in which a transparent conductive layer consisting mainly of indium oxide is formed on an organic polymer molded product by a sputtering method. Including wavelength 5
50rv light absorption rate is 2-30% and specific resistance is 1.5X1
Production of a transparent conductive laminate characterized by forming a layer having a resistance of 0-3 Ω·cra or more, and then converting the layer into a transparent conductive layer mainly consisting of crystalline indium oxide by heat treatment in an oxygen atmosphere. It's a method.

The details will be explained below along with the process leading up to the invention.

As mentioned above, IT formed by conventional sputtering method
It has been found that the O film has a major practical problem. The present inventors analyzed the structure of this ITO film using X-rays and found that it was amorphous. In order to obtain a crystalline ITO film using the normal sputtering method, a substrate temperature of about 300°C is required, and it is extremely difficult to form a crystalline ITO film on an organic polymer molded product that does not have much heat resistance. .

In response to this problem, the present inventors came up with the idea of combining a sputtering method and a heat treatment, and with the aim of converting the ITO film formed by the sputtering method into a crystalline state, the post-sputtering heat treatment ( Annealing) was carried out, but it could not be converted to crystalline material.

As a result of intensive research on this point, the present inventors found that due to differences in the characteristics of the [To film formed by the sputtering method, some films can be converted into crystalline materials and some cannot. That is, by performing sputtering using an indium-tin alloy target and varying the deposition rate under a constant oxygen partial pressure as shown in FIG. 1, ITO films with different resistivities and light absorption rates can be formed. Among these ITO films, those with a light absorption rate of 2 to 30% and a specific resistance of 1.5 x 10'Ω or more can be made into crystalline ITO films with good transparency by heat treatment in an oxygen atmosphere. It turns out that it can be converted into Films with a light absorption rate of less than 2% cannot be converted to crystalline form. Moreover, if it exceeds 30%, it is impossible to obtain an ITO film with good transparency.

Therefore, as mentioned above, the present invention first has a light absorption rate of 2 to 30% and a specific resistance of 1.5 x 10-3 on a polymer molded product.
The essential requirement is to form a layer containing mainly indium oxide with an Ωc of 11 or more, and then converting the layer into a layer containing mainly crystalline indium oxide by heat treatment in an oxygen atmosphere.

It is not clear why only films with a light absorption rate of 2% or more are converted into crystalline materials, but it is thought to be as follows. In other words, these films are chemically oxygen-deficient films, and there are many defects in the film, making it easy for indium and oxygen atoms to move during annealing, but films with low light absorption are chemically deficient films. Therefore, it is thought that this is because there are almost no defects and the indium and oxygen atoms are in a metastable state where they cannot easily move.

Here, the light absorption rate is the transmittance T (%) including the substrate at a wavelength of 550 nm, the reflectance R (%), and the sum B (%) of absorption and scattering by the organic polymer molded material that is the substrate, subtracted from 100. It is something that That is, light absorption rate = 100- (
T+R+B).

The light absorption rate of the indium-tin lower oxide film produced by the vacuum evaporation method previously proposed by the present inventors is 36%, and the specific resistance is 4×10-2 Ωα. It was confirmed that a layer was formed that was significantly different from the layer that was formed and mainly contained indium oxide. In the sputtering method for forming a layer mainly containing indium oxide, an alloy containing indium as a main component or a sintered body containing indium oxide as a main component can be used as a target. In the former method, reactive sputtering is performed by introducing an inert gas such as argon and oxygen gas into a vacuum chamber. In the latter case, sputtering is performed using an inert gas such as argon alone or a mixture of an inert gas such as argon and a trace amount of oxygen gas. The sputtering method is direct current or high frequency bipolar sputtering.

Known methods such as direct current or high frequency magnetron sputtering, ion beam sputtering, etc. can be applied. Among these, the magnetron method is preferable because it causes less plasma impact on the substrate and allows high-speed film formation.

In either case, the sputtering conditions must be controlled so that the light absorption rate and resistivity of the layer mainly containing indium oxide formed by the sputtering method reach desired values. Sputtering conditions vary depending on the device.

As mentioned above, the sputtering conditions can be determined by varying the deposition rate (i.e. input power) under a constant oxygen partial pressure and examining the characteristics of the deposited film, or by keeping the input power constant and increasing the oxygen There are methods to examine the characteristics of a deposited film by changing the partial pressure.

In short, in the sputtering equipment used, the sputtering conditions are experimentally determined so that the light absorption rate of the layer containing indium oxide is 2 to 30% and the resistivity is 1.5 x 10'Ωm or more. The sputtering conditions are controlled so that the light absorption rate and specific resistance of the layer contained have the above values.

The transparent conductive layer used in the present invention is a layer mainly containing indium oxide. The indium oxide layer is originally a transparent electrical insulator, but if it contains trace amounts of impurities,
It becomes a semiconductor when there is a slight oxygen deficiency.

Preferred semiconductor metal oxides include, for example, indium oxide containing tin or fluorine as an impurity.

Particularly preferred is an indium oxide layer containing 2 to 20 wt% of tin oxide.

In order to obtain sufficient conductivity, the thickness of the transparent conductive layer mainly made of indium oxide used in the present invention must be 3.
It is preferably 0 Å or more, and more preferably 50 Å or more. Further, in order to obtain a film with sufficiently high transparency, the thickness is preferably 500 Å or less, more preferably 400 Å or less.

In the present invention, a layer mainly made of indium oxide is formed by sputtering on an organic polymer molded article, with an intermediate layer interposed therebetween if necessary, and then heat treatment is performed in an oxygen atmosphere. The oxygen atmosphere may be one in which at least enough oxygen is present to convert the above into the indium oxide WIh crystalline substance formed by the sputtering method, and an inert gas may be introduced as necessary. Various atmospheres are applicable, such as a normal pressure atmosphere containing gas and/or ozone, a low pressure atmosphere containing oxygen gas and/or oxygen plasma, or a high pressure atmosphere containing oxygen gas and/or ozone. A normal pressure atmosphere containing ozone is preferably used. Also, the heating temperature is 100
-250 degreeC is preferable, and 130-200 degreeC is especially preferable. At temperatures below 100°C, it cannot be converted into crystalline indium oxide. Moreover, if the temperature exceeds 250°C, deformation or cracks will occur in the organic polymer molded product, which is not preferable.

Note that the heat treatment time is determined experimentally depending on the heating temperature, single layer composition, etc.

The organic polymer compound constituting the organic polymer molded product in the present invention is not particularly limited as long as it is a transparent organic polymer compound having heat resistance, but usually the heat resistance is 1.
00°C or higher, preferably 130°C or higher, such as polyimide, polyethersulfone, polysulfone, polyparabanic acid, polyhydantoin, polyethylene terephthalate, polyethylene-2,6-naphthalene dicarboxylate, polydiallyl. Examples include polyester resins such as phthalate and bocarbonate, aromatic polyamides, and cellulose triacetate.

Of course, these are homopolymers.

They can be used as copolymers, alone or in blends.

The shape of the molded product of the organic polymer compound is not particularly limited, but sheet-like or film-like products are usually preferred, and among them, film-like products can be rolled up and can be produced continuously. Therefore, it is particularly preferable. Furthermore, when a film-like material is used, the thickness of the film is preferably 6 to 500μ, more preferably 12 to 125μ.
is preferred.

Pigments may be added to these films or sheets to the extent that transparency is not impaired, or surface treatments such as sand matting may be applied.

Further, these films or sheets may be used alone or in a laminated manner.

Furthermore, in order to improve the adhesion with the transparent conductive layer, an intermediate layer may be formed on the organic polymer molded product before forming the transparent conductive layer. As the intermediate layer, a layer produced by hydrolysis of an organometallic compound such as an organosilicon compound, a titanium alkyl ester, or a zirconium alkyl ester is preferably used. The intermediate layer may have a multilayer structure.

The intermediate layer is coated onto the shaped polymer molding, dried, and cured by heating, ion bombardment, or radiation such as ultraviolet rays, β rays, and γ rays.

For coating the intermediate layer, a doctor knife may be used depending on the shape and properties of the transparent transparent polymer molding or coating liquid.

A coating method using a known coating machine such as a bar coater, gravure roll coater, curtain coater, knife coater, etc., a spray method, a dipping method, etc. are used.

The thickness of the intermediate layer is preferably 100 to 1000 people, particularly preferably 200 to 900 people. If there are fewer than 100 people, no continuous layer is formed and there is no effect of improving adhesion. Moreover, if the number of people exceeds 1000, cracks and peeling may occur, which is not preferable.

Furthermore, the conductive laminate of the present invention is coated on a transparent conductive layer made of indium oxide for the purpose of so-called surface protection to improve scratch resistance. The layers may be stacked.

It takes a long time! ! As the L layer, Ti 02 , 3n 0
2.

Transparent oxides such as Si02, Zr02, zno, etc.

S! 3 Nitride such as N4, TiN, acrylonitrile resin, styrene resin, acrylate resin.

Transparent organic compound combinations such as polyester resin 1, or organometallic compounds such as organosilicon compounds, titanium alkyl esters, and zirconium alkyl esters can be used.

The thickness of such a protective film can be set arbitrarily within a range that does not deteriorate the characteristics of the transparent conductive layer.

Furthermore, the conductive laminate of the present invention may have a structure in which transparent conductive layers are laminated on both sides of the organic polymer molded product via an intermediate layer if necessary, or a transparent conductive layer may be laminated on one side of the organic polymer molded product. In a structure in which a transparent conductive layer is laminated via an intermediate layer, improve adhesion, surface hardness, optical properties, etc. on the side opposite to the side on which the transparent conductive layer is laminated, within a range that does not impair transparency. For this purpose, for example, a layer of the same type as the above-mentioned intermediate layer, an oxide layer, a nitride layer, a sulfide layer, a carbide layer, or an organic layer may be provided.

[Effects] As described above, by using the sputtering method of the present invention, a conductive laminate can be produced which has extremely excellent durability and reliability equivalent to or higher than conventional vacuum evaporation methods, and which can be fully used for transparent tablet applications. became possible.

Since the conductive layer of the present invention is formed by a sputtering method, there are no problems with conventional vacuum evaporation methods, and a wide conductive laminate of uniform quality can be continuously and stably produced, resulting in extremely high productivity. A good process was obtained.

The conductive laminate obtained by the present invention is not only suitable as an electrode for transparent tablets, but also for use in, for example, electrophotography, antistatic material, nine-sided heating element, solid-state display, optical memory, photoelectric conversion element, and optical communication. It has a wide range of applications including optical information processing, solar energy utilization materials, etc.

EXAMPLES Hereinafter, the effects of the present invention will be explained in more detail with reference to Examples. Note that parts in the examples are parts by weight.

[Examples 1 to 4 and Comparative Examples 1 to 2] Butanol, an organosilicon compound, was applied to both sides of a 100 μm thick polyethylene tethyphthalate film.

An isopropanol mixed alcohol solution (concentration 0.6% by weight) was applied using a bar coater and dried at 120° C. for 1 minute. The thickness of the film after drying was 300.

The film was fixed on a substrate holder in a DC magnetron sputtering device, and the vacuum chamber was evacuated to a vacuum level of 2×10'i Torr. After that, Ar10z mixed gas (0
225%) into the tank, and the degree of vacuum was set to 5×1O-3To.
After maintaining the temperature at rr, the deposition rate was varied by reactive sputtering using a target made of In/Sn alloy (Sn 5% by weight) to obtain the light absorption rate and specific resistance of the samples of Examples 1 to 4 and Comparative Example 1. An indium tin oxide film was formed. After heat-treating these samples in a hot-air dryer kept at 150°C, the crystallinity of the transparent conductive film was measured using an
). Furthermore, the heat resistance (resistance change after 1000 hours of 90"C) and acid resistance (1N
The resistance change (when immersed in hydrochloric acid) was investigated.

The specific resistance and light absorption rate (at 550 nm) of the sample immediately after sputtering, and the specific resistance and light absorption rate (at 550 nm) after heat treatment.
550nIIl), crystallinity, heat resistance, and acid resistance are the first
Shown in the table.

In addition, as Comparative Example 2, conventional I without heat treatment was used.
The measurement results for the TO film are also shown.

In Examples 1 to 4 according to the method of the present invention, the indium tin oxide film was heated to a crystalline IT state by heat treatment in an oxygen atmosphere.
It was converted into an O film and exhibited extremely excellent heat resistance and acid resistance. On the other hand, Comparative Example 1 remains amorphous even after heat treatment, and has significantly poor heat resistance and acid resistance.

Further, the X-ray diffraction patterns of Example 1 and Comparative Example 1 after heat treatment are shown in FIGS. 2 and 3, respectively.

In addition, Examples 2 to 4 showed the same X-ray diffraction pattern as Example 1, and Comparative Example 2 showed the same X-ray diffraction pattern as Comparative Example 1.

(Left below) Furthermore, regarding the samples of Example 1 and Comparative Example 2, IT
A transparent switch was fabricated with the O membrane surfaces facing each other with a spacer at a distance of 100 μm.

Silicone rubber rod with 7R tip (weight 200SF)
> was continuously freely dropped onto a transparent switch using a solenoid (stroke 0.5 m+). The switch is pressed every time the rod falls, and 17FLA flows through the switch due to the constant current power supply. The life of the switch was investigated by observing the waveform on the pulse when the transparent switch was pressed using a synchroscope. The life of the switch was defined as the time when the waveform was no longer observed.

While the switch life of Example 1 is 5 million times,
The switch life of Comparative Example 2 was 300,000 cycles.

[Example 5, Comparative Example 3] A mixed alcoholic solution of methanol, ethanol, and isopropanol containing 0.3% by weight of an organosilicon compound was coated on both sides of a 100μ thick polyethylene terephthalate film using a gravure roll coater, and the film was coated at 150°C. Dry for 1 minute. The film thickness after drying was about 400.

The film was fixed to a substrate holder in a DC magnetron sputtering device, and the vacuum chamber was evacuated until the vacuum level reached 1 x 10" TOrr. Thereafter, Ar gas was introduced into the tank to increase the vacuum level to 4 x 10" Torr. After keeping at 3T orr I
An indium tin oxide film having the specific resistance and light absorption rate of the samples of Example 5 and Comparative Example 3 was formed by sputtering using a TO (SnOz 5% by weight) target. The sample was heat-treated in the same manner as in Example 1, and then the crystallinity of the transparent conductive film was examined in the same manner as in Example 1. Table 2 shows the specific resistance, light absorption rate, and crystallinity of the ITO film. A crystalline ITO film could be obtained by the method of the present invention, and the characteristics of the crystalline ITO film were similar to those in Example 1.

Table 2 (Margin below)

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) show the dependence of the light absorption rate and specific resistance of the ITO film on the deposition rate. FIG. 2 shows the X-ray diffraction pattern of the transparent conductive layer of Example 1. FIG. 3 shows the X-ray diffraction pattern of the transparent GW layer of Comparative Example 1.

Claims (1)

[Scope of Claims] 1. In a method for manufacturing a conductive laminate in which a transparent conductive layer mainly made of indium oxide is formed on an organic polymer molded product by a sputtering method, first, a transparent conductive layer mainly made of indium oxide is formed on the organic polymer molded product. The light absorption rate at a wavelength of 550 mm, including objects, is 2 to 30%, and the specific resistance is 1.5 x 10^-^3
1. A method for manufacturing a transparent conductive laminate, which comprises forming a layer having a thickness of Ω·cm or more, and then converting the layer into a transparent conductive layer mainly consisting of crystalline indium oxide by heat treatment in an oxygen atmosphere. 2. The method for producing a transparent conductive laminate according to claim 1, wherein the heat treatment temperature is 100 to 250°C.