阅读说明：本技术 透明氧化物膜、透明氧化物膜的制造方法、氧化物烧结体和透明树脂基板 (Transparent oxide film, method for producing transparent oxide film, oxide sintered body, and transparent resin substrate ) 是由 下山田卓矢 桑原正和 仁藤茂生 于 2019-01-24 设计创作，主要内容包括：本发明提供一种通过量产性高的直流溅射而具有良好的透明性、水蒸气阻隔性能、以及优异的耐化学试剂性,并且柔性也优异的透明氧化物膜及其制造方法、用于形成膜的氧化物烧结体、以及使用透明氧化物膜的透明树脂基板。一种含有Zn和Sn的非晶质的透明氧化物膜,以金属原子数比计,Sn/(Zn+Sn)为0.44以上且0.90以下,膜厚为100nm以下。另外,一种透明氧化物膜的制造方法,使用由Sn-Zn-O系的氧化物烧结体构成的靶进行溅射而得到透明氧化物膜,溅射时所使用的所述氧化物烧结体中含有的Zn与Sn的金属原子数比的Sn/(Zn+Sn)为0.44以上且0.90以下,成膜的膜厚为100nm以下。(The invention provides a transparent oxide film which has good transparency, water vapor barrier performance, excellent chemical resistance and excellent flexibility by DC sputtering with high mass production performance, a manufacturing method thereof, an oxide sintered body for forming the film, and a transparent resin substrate using the transparent oxide film. An amorphous transparent oxide film containing Zn and Sn, wherein Sn/(Zn + Sn) is 0.44 to 0.90 in terms of a metal atom number ratio, and the film thickness is 100nm or less. Also disclosed is a method for producing a transparent oxide film, wherein a transparent oxide film is obtained by sputtering using a target composed of an Sn-Zn-O oxide sintered body, wherein the Sn/(Zn + Sn) which is the metal atom ratio of Zn to Sn contained in the oxide sintered body used in sputtering is 0.44-0.90, and the film thickness to be formed is 100nm or less.)

1. A transparent oxide film which is an amorphous transparent oxide film containing Zn and Sn,

Sn/(Zn + Sn) is 0.44 or more and 0.90 or less in terms of the metal atom number ratio,

the film thickness is 100nm or less.

2. The transparent oxide film according to claim 1, further containing Ta and Ge,

in the atomic ratio of Zn, Sn, Ta, and Ge,

Ta/(Zn + Sn + Ge + Ta) is 0.01 or less, and Ge/(Zn + Sn + Ge + Ta) is 0.04 or less.

3. The transparent oxide film according to claim 1, wherein the change in color difference Δ Eab before and after immersion of the transparent oxide film in a 5% hydrochloric acid solution or a 5% sodium hydroxide aqueous solution for 5 minutes is 1.0 or less.

4. The transparent oxide film according to claim 1, wherein the amount of change in film thickness of the transparent oxide film before and after immersion in a 5% hydrochloric acid solution or a 5% sodium hydroxide aqueous solution for 5 minutes is 2.0nm or less.

5. The transparent oxide film according to claim 1, wherein the water vapor transmission rate obtained by a prescribed pressure difference method according to JIS K7129 is 0.015g/m when the film thickness of the transparent oxide film is 50nm or more and 100nm or less²(ii) a value of/day or less,

0.08g/m when the film thickness of the transparent oxide film is 10nm or more and less than 50nm²And/day is less.

6. An oxide sintered body of Sn-Zn-O system for forming a transparent oxide film according to any one of claims 1 to 5 by a sputtering method,

Sn/(Zn + Sn) in the metal atomic number ratio of Zn to Sn contained in the oxide sintered body is 0.44 to 0.90.

7. The oxide sintered body as claimed in claim 6, further comprising Ta and Ge,

Ta/(Zn + Sn + Ge + Ta) in the metal atomic ratio of Ta to Zn, Sn, Ge is 0.01 or less,

the ratio of Ge to Zn, Sn, Ta metal atoms, Ge/(Zn + Sn + Ge + Ta) is 0.04 or less.

8. A method for producing a transparent oxide film, which comprises sputtering a target comprising a Sn-Zn-O-based oxide sintered body to obtain a transparent oxide film,

Sn/(Zn + Sn) in the metal atomic ratio of Zn to Sn contained in the oxide sintered body used in the sputtering is 0.44 or more and 0.90 or less,

the film thickness of the film is 100nm or less.

9. A transparent resin substrate obtained by forming the transparent oxide film according to any one of claims 1 to 5 on at least one surface of a transparent resin base material.

Technical Field

The present invention relates to a transparent oxide film, a method for producing a transparent oxide film, an oxide sintered body, and a transparent resin substrate, and relates to a transparent oxide film, a method for producing a transparent oxide film, an oxide sintered body for forming a film, and a transparent resin substrate using a transparent oxide film, which are generally used in displays of electronic elements such as liquid crystal elements (LCDs), touch panel elements (TPs), and electronic paper. This application claims priority based on japanese patent application No. 2018-050676, filed on 19/3/2018 in japan, and is incorporated herein by reference.

Background

In recent years, in electronic devices such as Liquid Crystal Devices (LCDs), touch panel devices (TPs), and electronic papers, there has been an increasing demand for devices using a film substrate in which a transparent conductive layer is formed on a transparent plastic film made of a polymer organic material, from devices using a glass substrate with a transparent conductive layer. The advantages include light weight, flexibility, impact resistance, and easiness in enlarging the area.

However, the film has a lower water vapor barrier property than a glass substrate, and this causes a problem in display performance. As a method for compensating for the deterioration of the water vapor barrier property, a method of providing a barrier layer on a transparent plastic film has been studied.

The barrier layer is mainly a metal oxide layer of silicon, aluminum, or the like. Formed by sputtering, ion plating, vacuum deposition, optical CVD, or the like. As the water vapor transmission rate required for each purpose, it is said to be 0.1g/m for electronic paper and the like²It is said to be 0.01g/m or less for a liquid crystal display or the like²About/day.

In addition, in order to protect the metal oxide layer from a chemical agent, a chemical agent resistant layer made of an organic compound is also provided on the metal oxide layer. The chemical agent is, for example, an alkaline aqueous solution or an acidic aqueous solution used in an etching step when patterning a transparent electrode of a barrier film with a transparent electrode. In general photolithography, these chemicals can be used in all cases. In addition, in the case of forming a liquid crystal display, the transparent barrier layer is partially etched by an acidic or basic solvent contained in an adhesive or a sealant of the adhesive layer, and the barrier property may be deteriorated. Therefore, chemical resistance is regarded as important.

For example, patent document 1 describes a water vapor barrier transparent resin substrate in which a transparent conductive film of tin oxide or the like is formed on a transparent film by a sputtering method, and describes the following: water vapour transmission rate of less than 0.01g/m obtained by Mocon method²And/day, the transmittance was not changed after immersion in hydrochloric acid solution or alkali solution.

Patent document 2 proposes a barrier film obtained by laminating an inorganic film and an organic film. It is described that the water vapor transmission rate at this time is 0.01g/m²The inorganic film has a thickness of 30nm to 1 μm and the organic layer has a thickness of 10nm to 2 μm, respectively, below day.

Disclosure of Invention

Problems to be solved by the invention

In recent years, as electronic devices have become thinner and smaller, the water vapor barrier transparent resin substrates used for these displays have been required to be flexible and have been required to be thinner while maintaining the water vapor transmission rate and chemical resistance. Specifically, the barrier film is required to have a film thickness of 100nm or less. Naturally, when the film thickness of the barrier film is 100nm or less, the film thickness decreases, and therefore, the water vapor transmission rate and the chemical resistance deteriorate. Therefore, it is necessary to improve the water vapor transmission rate and the chemical resistance as compared with the conventional ones.

On the other hand, in patent document 1, the water vapor transmission rate is measured by the Mocon method, but in the measurement by the Mocon method, it is difficult to accurately measure 0.01g/m²Below/day, there is still a question about the water vapor barrier properties of the actual film. In addition, the flexibility is poor because the film used is 200 μm and the thickness of the barrier film is as thick as 100 to 200 nm.

Patent document 2 proposes a barrier film obtained by laminating an inorganic film and an organic film, but since film formation processes are different between the inorganic film and the organic film, it is necessary to perform film lamination by different processes, and it is considered that productivity is deteriorated and characteristics are deteriorated due to foreign matter or the like. In addition, it describes: in order to achieve a water vapor transmission rate of 0.01g/m²The flexibility is poor because the structure must be 3 or more layers and the organic layer must be about 500nm or less per day.

The present invention has been made in view of these demands, and provides a transparent oxide film having good transparency, water vapor barrier performance, and excellent chemical resistance by dc sputtering with high mass productivity, and also having excellent flexibility, a method for producing the same, an oxide sintered body for forming a film, and a transparent resin substrate using the transparent oxide film.

Means for solving the problems

In view of the above problems, the present inventors have conducted extensive analyses on conditions suitable for chemical resistance and flexibility by adjusting the metal atomic ratio of Zn to Sn and the film thickness, and have completed the present invention.

That is, one embodiment of the present invention is an amorphous transparent oxide film containing Zn and Sn, wherein Sn/(Zn + Sn) is 0.44 or more and 0.90 or less in terms of the metal atom number ratio, and the film thickness is 100nm or less.

According to one embodiment of the present invention, Zn and Sn are contained in the above-described ratio, thereby providing excellent chemical resistance, and the film thickness is set to 100nm or less, thereby providing a transparent oxide film having excellent flexibility.

In this case, in one aspect of the present invention, Ta and Ge may be further contained, and Ta/(Zn + Sn + Ge + Ta) may be 0.01 or less and Ge/(Zn + Sn + Ge + Ta) may be 0.04 or less in the atomic ratio of Zn, Sn, Ta, and Ge.

Ta and Ge are components derived from the target, and therefore, the conductivity of the target itself can be improved, and the film formation rate can be increased, and the film formation can be stabilized by increasing the target density.

In one embodiment of the present invention, the change in color difference Δ Eab before and after immersing the transparent oxide film in 5% hydrochloric acid or 5% sodium hydroxide aqueous solution for 5 minutes may be 1.0 or less.

By satisfying the above requirements, the transparent oxide film can be said to have excellent chemical resistance.

In one embodiment of the present invention, the amount of change in film thickness of the transparent oxide film before and after immersion in 5% hydrochloric acid or 5% sodium hydroxide aqueous solution for 5 minutes may be 2.0nm or less.

By satisfying the above requirements, the transparent oxide film can be said to have excellent chemical resistance.

In one embodiment of the present invention, the water vapor transmission rate obtained by a prescribed pressure difference method in accordance with the JIS K7129 method may be 0.015g/m when the film thickness of the transparent oxide film is 50nm or more and 100nm or less²A film thickness of 0.08g/m or less when the transparent oxide film has a thickness of 10nm or more and less than 50nm²And/day is less.

By satisfying the above requirements, it can be said that the transparent oxide film has good water vapor barrier properties.

Another embodiment of the present invention is an Sn — Zn — O-based oxide sintered body for forming the transparent oxide film by a sputtering method, wherein Sn/(Zn + Sn), which is a metal atom ratio of Zn to Sn contained in the oxide sintered body, is 0.44 or more and 0.90 or less.

By sputtering using an oxide sintered body of such a composition, a transparent oxide film having excellent chemical resistance can be formed.

In this case, in another aspect of the present invention, Ta and Ge may be further contained, Ta/(Zn + Sn + Ge + Ta) in the metal atomic ratio of Ta to Zn, Sn, and Ge may be 0.01 or less, and Ge/(Zn + Sn + Ge + Ta) in the metal atomic ratio of Ge to Zn, Sn, and Ta may be 0.04 or less.

By doing so, the conductivity of the target itself can be improved, and the film formation rate can be increased, and the film formation can be stabilized by increasing the target density.

Another embodiment of the present invention is a method for producing a transparent oxide film, in which a target composed of an Sn — Zn — O-based oxide sintered body is used to perform sputtering to obtain a transparent oxide film, wherein Sn/(Zn + Sn), which is the ratio of metal atoms of Zn to Sn contained in the oxide sintered body used in sputtering, is 0.44 or more and 0.90 or less, and the film thickness to be formed is 100nm or less.

According to another aspect of the present invention, Zn and Sn are contained in the above-described ratio, thereby having excellent chemical resistance, and a transparent oxide film having excellent flexibility can be produced by setting the film thickness to 100nm or less.

Another embodiment of the present invention is a transparent resin substrate in which the transparent oxide film is formed on at least one surface of a transparent resin base.

According to another aspect of the present invention, by forming the transparent oxide film, a transparent resin substrate having both excellent water vapor barrier properties and chemical resistance and also excellent flexibility can be produced.

Effects of the invention

According to the present invention, it is possible to provide a transparent oxide film having good transparency, water vapor barrier performance, and excellent chemical resistance by dc sputtering with high mass productivity and versatility, and also having excellent flexibility, a method for producing the same, an oxide sintered body for forming a film, and a transparent resin substrate using the transparent oxide film.

Detailed Description

The transparent oxide film, the method for producing the transparent oxide film, the oxide sintered body, and the transparent resin substrate according to the present invention will be described in the following order. The present invention is not limited to the following examples, and can be modified as desired without departing from the scope of the present invention.

1. Transparent oxide film

2. Oxide sintered body

3. Method for producing transparent oxide film

4. Transparent resin substrate

< 1. transparent oxide film >

One embodiment of the present invention is an amorphous transparent oxide film containing Zn and Sn, wherein Sn/(Zn + Sn) is 0.44 or more and 0.90 or less in terms of a metal atom number ratio, and the film thickness is 100nm or less. By containing Zn and Sn in such a ratio, excellent chemical resistance is obtained, and by setting the film thickness to 100nm or less, a transparent oxide film having excellent flexibility can be obtained.

The amorphous transparent oxide film of the present invention is also used as a water vapor barrier film. The surface of a plastic substrate, a film substrate, or a flexible display element such as a liquid crystal display element or electronic paper is covered with a metal oxide film by a sputtering method for the purpose of preventing deterioration by blocking water vapor or the like.

The transparent oxide film needs to block water vapor. Therefore, the transparent oxide film is preferably as dense as possible, thin and uniform in thickness, and has few defects (gaps) through which moisture passes. Therefore, the transparent oxide film is formed by a sputtering method. The transparent oxide film formed by this sputtering method is desirably amorphous as described in patent document 1. This is because: in the case where the transparent oxide film is a crystalline film, since grain boundaries exist in the film and water vapor passes through the grain boundaries, the water vapor barrier performance is lowered.

In addition, the transparent oxide film needs to have acid resistance and alkali resistance in order to protect the metal oxide layer from the chemical agent. When the metal oxide layer is patterned in an arbitrary shape, it is performed by a general photolithography method. In this method, since an alkaline aqueous solution or an acidic aqueous solution is used in all cases, it is a prerequisite that the transparent oxide film is not dissolved and the film is not damaged by a chemical agent. In addition, in the formation of a liquid crystal display, the transparent oxide film is partially etched by permeation of an acidic or basic solvent contained in an adhesive material or a sealing material of an adhesive layer, and barrier properties are impaired, and thus chemical resistance is considered important.

In patent document 1, a tin oxide film is proposed as the transparent oxide film, but when a tin oxide film is formed by a sputtering method, a target material constituting a sputtering target used for sputtering may use a tin oxide film having the same composition as the film. The tin oxide-based target generally has high acid resistance but has a low relative density, and thus there are many problems such as the target breaking during sputtering and the like, which makes it impossible to stably form a film. The transparent oxide film according to the present invention eliminates the above-mentioned concerns by using a Sn-Zn-O sputtering target described later.

That is, the transparent oxide film according to one embodiment of the present invention is an amorphous transparent oxide film containing Zn and Sn, and is characterized in that Sn/(Zn + Sn) is 0.44 or more and 0.90 or less in terms of a metal atomic number ratio.

By setting Sn/(Zn + Sn) to 0.44 or more and 0.90 or less in terms of the metal atom number ratio, good water vapor transmission rate and chemical resistance can be obtained. Zinc oxide (ZnO) is easily dissolved in chemical reagents such as acids and alkalis, and has a disadvantage of lacking resistance to chemical reagents such as acids and alkalis. It is difficult to perform high-definition patterning processing by wet etching, for example. But tin oxide (SnO)₂) Has the characteristic of extremely high resistance to chemical agents. Therefore, the main component of the amorphous transparent oxide film containing Zn and Sn is SnO₂Thus, chemical resistance to acids and bases can be obtained.

When the metal atomic number ratio Sn/(Sn + Zn) is less than 0.44,with SnO₂More ZnO is easily dissolved in an acidic or alkaline aqueous solution, and thus, the ZnO alloy is less resistant to chemical reagents.

In addition, SnO may be added when the metal atom number ratio Sn/(Sn + Zn) exceeds 0.90₂The ratio is not increased, so that the relative density of the sputtering target is low, and the possibility of occurrence of a fracture failure of the sintered body in the dc sputtering is high.

The thickness of the transparent oxide film according to one embodiment of the present invention is preferably 100nm or less, and more preferably 90nm or less. By setting the film thickness as described above, an oxide film having excellent flexibility can be provided. In addition, the lower limit of the thickness of the oxide film according to one embodiment of the present invention is 10 nm.

If the thickness of the transparent oxide film according to one embodiment of the present invention is reduced to 10nm, the film is too thin, and therefore, the quality of the entire film is difficult to ensure, and defects occur due to permeation and dissolution of the chemical solution during film formation, which affects barrier performance. When the film thickness exceeds 100nm, the film stress causes warpage of the film substrate, and causes deterioration of flexibility and reduction of transmittance. Therefore, the film thickness is preferably 100nm or less, more preferably 90nm or less, in consideration of productivity and cost. Therefore, when used at 10 to 100nm, the film thickness is most suitable for use in assembling devices and mass production, in accordance with the requirements for flexibility, weight reduction, and film thickness reduction.

The transparent oxide film according to one embodiment of the present invention may further include Ta in a ratio of Ta/(Zn + Sn + Ge + Ta) of 0.01 or less, and Ge in a ratio of Ge/(Zn + Sn + Ge + Ta) of 0.04 or less, in terms of a metal atomic ratio. Even when Ta or Ge is contained, an amorphous film structure can be easily obtained because the crystallization temperature is 600 ℃ or higher. Further, since the crystallization temperature is high, the amorphous state can be easily maintained even when there is a thermal influence in the mass production process. In addition, when Ta and Ge are added in the above ratio, the characteristics of the sputtering target containing Zn and Sn are further improved.

Hereinafter, the additive elements (Ta, Ge) will be briefly described. The sputtering target is obtained by bonding (joining) an oxide sintered body composed of Sn — Zn alone to a backing plate composed of a copper material, a stainless steel material, or the like, using a joining material such as indium (In), or the like.

A target composed of only Sn — Zn may have insufficient conductivity and a high resistivity value. In sputtering, as the resistivity value increases, sputtering with a larger energy is required, and the film deposition rate cannot be increased. Therefore, it is necessary to increase the conductivity of the target. In the target Zn₂SnO₄、ZnO、SnO₂Is a substance having poor conductivity, and therefore, even if the mixing ratio is adjusted, the compound phase, ZnO or SnO is adjusted₂The amount of (3) also does not significantly improve the conductivity.

Therefore, Ta (tantalum) is preferably added. Ta will react with Zn and Zn in ZnO phase₂SnO₄Zn or Sn, SnO in phase₂Sn in the phase is substituted and dissolved in a solid solution, so that a ZnO phase having a wurtzite-type crystal structure and Zn having a spinel-type crystal structure are not formed₂SnO₄Phase, and SnO of rutile type crystal structure₂Compound phases other than the phase. By adding Ta, the conductivity can be improved while maintaining the density of the oxide sintered body.

In addition, the sintered density of the target composed of only Sn — Zn composition is about 90%, which may not be said to be sufficient. If the target density is low, there is a problem that stable film formation cannot be performed due to target breakage during sputtering or the like.

Therefore, a predetermined amount of Ge (germanium) is preferably added. In the target, Ge will react with Zn and Zn in ZnO phase₂SnO₄Zn or Sn, SnO in phase₂Sn in the phase is substituted and dissolved in a solid solution, so that a ZnO phase having a wurtzite-type crystal structure and Zn having a spinel-type crystal structure are not formed₂SnO₄Phase, and SnO of rutile type crystal structure₂Compound phases other than the phase. By adding Ge, the target is densified. This makes it possible to set the sintered density of the target to a higher density.

Therefore, it is preferable that the oxide sintered body further contains Ta and Ge, and Ta/(Zn + Sn + Ge + Ta) of the metal atomic ratio of Ta to Zn, Sn, and Ge is 0.01 or less, and Ge/(Zn + Sn + Ge + Ta) of the metal atomic ratio of Ge to Zn, Sn, and Ta is 0.04 or less. The approximate lower limit of the effect obtained by adding Ta and Ge is 0.0005 in the metal atom ratio together with Ta and Ge.

When Ta/(Zn + Sn + Ge + Ta) is more than 0.01 in the metal atom number ratio of Ta to Zn, Sn, Ge, another compound phase is formed, for example, Ta₂O₅、ZnTa₂O₆And a compound phase, and therefore, the conductivity cannot be greatly improved. When Ge/(Zn + Sn + Ge + Ta) is greater than 0.04 in the metal atom number ratio of Ge to Zn, Sn and Ta, another compound phase, for example, Zn, is formed₂Ge₃O₈And the density of the oxide sintered body is lowered due to the compound phase, and the target is easily broken during sputtering.

Even if sputtering is performed using a target to which Ta and Ge are added, the formed transparent oxide film is not affected. For example, no influence on the water vapor transmission rate and chemical resistance was observed. Therefore, even if Sn/(Zn + Sn) is 0.44 or more and 0.90 or less, Ta is 0.01 or less in terms of Ta/(Zn + Sn + Ge + Ta), and Ge is 0.04 or less in terms of Ge/(Zn + Sn + Ge + Ta), in terms of the metal atomic ratio, an amorphous transparent oxide film maintaining good chemical resistance can be obtained without deteriorating the water vapor barrier performance.

As described above, the transparent oxide film according to one embodiment of the present invention has chemical resistance. The chemical resistance was evaluated by the amount of change in film thickness and the color difference Δ Eab before and after immersion in the chemical solution. In these evaluations, when the transparent oxide film according to one embodiment of the present invention is formed on a transparent glass substrate by a sputtering method and immersed in an acidic aqueous solution or an alkaline aqueous solution, the amount of change in film thickness before and after immersion in a chemical solution is preferably 2.0nm or less, and the color difference of the transparent oxide film before and after immersion is preferably 1.0 or less in the value of Δ Eab in the color system of la b.

Specifically, chemical resistance was confirmed for acid and alkali. The acid resistance was evaluated by immersing the steel sheet in 5% hydrochloric acid for 5 minutes, and the alkali resistance was evaluated by immersing the steel sheet in 5% sodium hydroxide solution for 5 minutes, and measuring the change in the color difference Δ Eab between the two. Presume that: when the color difference Δ Eab is large, the color tone changes before and after the treatment, and the transparent oxide film is eluted by the chemical agent and discolored. If the change in the color difference Δ Eab is 1.0 or less, the transparent oxide film is less eluted by the chemical reagent, and can be judged to have chemical resistance. The change value of the color difference Δ Eab is more preferably 0.5 or less.

The color difference was evaluated using the L.a.b.0 color system (CIE 1976). L × a × b represents a color system, L × represents lightness, a × b represents hue and chroma, and L × is represented by a value of 0to 100, and the larger the value, the whiter the color becomes. a is an axis from red to green, + a is a red direction, -a is a green direction, b is an axis from yellow to blue, + b is a yellow direction, -b is a blue direction, and when a and b are all 0, the color is achromatic. The color difference Δ Eab is calculated by the color difference calculation formula of CIE 1976. In the transparent oxide sputtering film before and after the chemical agent immersion, Lx, aa and bx are measured, and the difference between the measured values is defined as DeltaLx, DeltaaA and Deltabx, and the color difference DeltaEab is defined by²+(Δa＊)²+(Δb＊)²)^1/2And (4) obtaining.

The thickness change before and after immersion in the chemical solution can be verified as follows: the acid resistance was measured by immersing the sample in 5% hydrochloric acid for 5 minutes, and the alkali resistance was measured by immersing the sample in 5% sodium hydroxide solution for 5 minutes, and the amounts of Zn and Sn dissolved in the chemical solution in which the sample was immersed were confirmed by ICP-AES (ICPS-8100, Shimadzu corporation), and the amount of decrease in film thickness (film change amount) was evaluated from the results, the film formation area, and the film density. Chemical resistance can be determined if the amount of decrease in film thickness (amount of change in film) after immersion in 5% hydrochloric acid for 5 minutes is 2.0nm or less with respect to acid resistance and the amount of decrease in film thickness (amount of change in film) after immersion in 5% sodium hydroxide solution for 5 minutes is 2.0nm or less with respect to alkali resistance.

As described above, tin oxide (SnO)₂) Has the characteristic of extremely high resistance to chemical agents. The main component of the amorphous transparent oxide film containing Zn and Sn is SnO₂And is andsince Sn/(Zn + Sn) is 0.44 or more and 0.90 or less in terms of the metal atomic number ratio, the color difference Δ Eab change value thereof may be 1.0 or less, and the film change amount thereof may be 2.0nm or less.

In the transparent oxide film according to one embodiment of the present invention, the water vapor transmission rate is affected by the film thickness. Regarding the water vapor transmission rate, the thicker the film thickness, the smaller the water vapor transmission rate. Therefore, the film thickness is appropriately set in consideration of the required water vapor transmission rate.

In the transparent oxide film according to one embodiment of the present invention, the water vapor transmission rate of the transparent oxide film obtained by the prescribed pressure difference method in accordance with the K7129 method of JIS standards is preferably 0.015g/m or more when the film thickness is 50nm to 100nm²A value of 0.08g/m or less per day, preferably 10nm or more and less than 50nm²And/day is less.

As described above, the transparent oxide film according to one embodiment of the present invention has both excellent water vapor barrier performance and chemical resistance by dc sputtering with high mass productivity, and has excellent flexibility.

< 2. oxide sintered body >

Next, a Sn — Zn — O-based oxide sintered body for forming a transparent oxide film according to an embodiment of the present invention by a sputtering method will be described. An oxide sintered body according to an embodiment of the present invention is an Sn — Zn — O-based oxide sintered body constituting a sputtering target used when an oxide sputtered film is sputtered.

Further, Sn/(Zn + Sn), which is the metal atom ratio of Zn to Sn contained in the oxide sintered body, is 0.44 or more and 0.90 or less. The characteristics of the above oxide sintered body can be inherited by the transparent oxide film.

Preferably, the oxide sintered body further contains Ta and Ge, and Ta/(Zn + Sn + Ge + Ta) of a metal atomic ratio of Ta to Zn, Sn, and Ge is 0.01 or less, and Ge/(Zn + Sn + Ge + Ta) of a metal atomic ratio of Ge to Zn, Sn, and Ta is 0.04 or less. The technical meaning of the composition range of the oxide sintered body according to one embodiment of the present invention is as described above.

The oxide sintered body according to one embodiment of the present invention is not limited to the following, and a specific method for producing the sintered body can be exemplified. First, Zn oxide powder, Sn oxide powder, and oxide powder containing Ta and Ge additive elements are mixed so as to have the preferred metal atom ratios described above. Then, pure water or ultrapure water, an organic binder, a dispersant, and an antifoaming agent are added to the granulated powder and mixed.

Then, hard ZrO was charged in₂The raw material powder is wet-pulverized by a ball mill device or the like, and then mixed and stirred to obtain a slurry. The slurry thus obtained is sprayed and dried by a spray dryer apparatus or the like to obtain a granulated powder.

Next, the granulated powder is press-molded to obtain a molded body. For removing the inter-particle pores of the granulated powder, the pressure is, for example, 294MPa (3.0 ton/cm)²) Press forming is performed under left and right pressures. The method of Press molding is not particularly limited, and for example, it is preferable to fill the granulated powder into a rubber mold and use a Cold Isostatic Press (CIP) capable of applying a high pressure.

Next, the compact is fired to obtain an oxide sintered body. The compact is fired at a predetermined temperature and for a predetermined time at a predetermined temperature rise rate in a firing furnace to obtain an oxide sintered body. The firing is performed, for example, in an atmosphere in a firing furnace in the air. The compact is preferably fired in the firing furnace at a temperature rise rate of from 700 ℃ to a predetermined firing temperature of from 0.3 to 1.0 ℃/min. This is because: promoting ZnO and SnO₂、Zn₂SnO₄The diffusion of the compound improves the sinterability and the conductivity. By setting such a temperature rise rate, ZnO and Zn are also suppressed in a high-temperature region₂SnO₄And (5) volatilization effect.

When the temperature rise rate in the sintering furnace is less than 0.3 ℃/min, the diffusion of the compound is reduced. On the other hand, if it exceeds 1.0 ℃/min, the rate of temperature rise is high, so that the formation of the compound is incomplete, and a dense oxide sintered body cannot be produced.

The sintering temperature after the temperature rise is preferably 1300 ℃ to 1400 ℃. When the sintering temperature is less than 1300 ℃, the temperature is too low, ZnO and SnO₂、Zn₂SnO₄Sintered grain boundary diffusion in the compound does not advance. On the other hand, if the temperature exceeds 1400 ℃, grain boundary diffusion is promoted to advance sintering, but the volatilization of the Zn component cannot be suppressed, and large pores remain in the oxide sintered body.

The holding time after the temperature rise is preferably 15 hours or more and 25 hours or less. When the holding time is less than 15 hours, sintering is incomplete, and therefore, a sintered body having large strain and warpage is obtained, and grain boundary diffusion does not proceed and sintering does not proceed. As a result, a dense sintered body cannot be produced. On the other hand, when it exceeds 25 hours, ZnO or Zn is present₂SnO₄The volatilization of (2) becomes large, resulting in a decrease in density of the oxide sintered body, deterioration in working efficiency, and high cost.

As described above, according to the oxide sintered body according to one embodiment of the present invention, a transparent oxide film having both excellent water vapor barrier performance and chemical resistance and also excellent flexibility can be obtained by dc sputtering with high mass productivity.

A sputtering target composed of the oxide sintered body was produced as follows. First, the oxide sintered body is mechanically polished to a desired size to obtain a processed body (target). The obtained processed body is bonded (joined) to a backing plate made of a copper material, a stainless steel material, or the like, using a joining material such as indium (In), to obtain a sputtering target. The sputtering target may be formed by bonding a plurality of oxide sintered bodies.

< 3. method for producing transparent oxide film

Next, a method for producing a transparent oxide film according to an embodiment of the present invention will be described. A method for producing a transparent oxide film according to an embodiment of the present invention is a method for obtaining an amorphous transparent oxide film by sputtering using a Sn — Zn — O-based oxide sintered body.

Then, a target composed of a sintered body of: the sintered body has a metal atomic ratio of Zn to Sn, i.e., Sn/(Zn + Sn), of 0.44 to 0.90, inclusive, in the sintered oxide body used for sputtering the transparent oxide film. The technical meaning of the above range is as described above.

The transparent oxide film is formed so that the film thickness is 100nm or less, preferably 90nm or less. When the film thickness is set to such a thickness, a transparent oxide film having good water vapor barrier properties and excellent chemical resistance and further excellent flexibility can be provided.

The sputtering may be performed using a sputtering target composed of the oxide sintered body. The sputtering apparatus is not particularly limited, and a direct current magnetron sputtering apparatus or the like can be used.

As a sputtering condition, the degree of vacuum in the chamber was adjusted to 1X 10^-4Pa or less. An inert gas is introduced into the atmosphere in the chamber. The inert gas is argon gas or the like, and the purity is preferably 99.999 mass% or more. The inert gas contains 4 to 10% by volume of oxygen with respect to the total gas flow rate. The oxygen concentration has an influence on the surface resistance value of the film, and therefore, the oxygen concentration is set so as to have a predetermined resistance value. Then, a predetermined dc power supply is applied between the sputtering target and the base material, and plasma is generated by a dc pulse to perform sputtering, thereby forming a film. The film thickness is controlled by the film formation time.

As described above, according to the method for producing a transparent oxide film according to one embodiment of the present invention, a transparent oxide film having excellent transparency, water vapor barrier performance, and chemical resistance and also excellent flexibility can be obtained by dc sputtering with high mass productivity.

< 4. transparent resin substrate

A transparent resin substrate according to an embodiment of the present invention is a substrate in which a transparent oxide film having a metal atom ratio of Zn to Sn, that is, Sn/(Zn + Sn) of 0.44 to 0.90, is formed on at least one surface of the base material. The transparent oxide film is characterized in that the thickness thereof is 100nm or less, preferably 90nm or less.

As the transparent substrate, polyethylene terephthalate, polyethylene, naphthalate, polycarbonate, polysulfone, polyethersulfone, polyarylate, cycloolefin polymer, fluororesin, polypropylene, polyimide resin, epoxy resin, or the like can be used. The thickness of the transparent resin substrate is not particularly limited, but is preferably 50 to 150 μm in consideration of flexibility, cost, and device requirements.

The sputtering method on the transparent resin substrate may be performed as described in the method for producing a transparent oxide film. The technical meanings of the above-mentioned appropriate metal atom ratio of Zn to Sn, film thickness, and the like are as described above.

The transparent resin substrate according to one embodiment of the present invention is a substrate in which a sputtered film of an amorphous transparent oxide containing Zn and Sn is formed on at least one surface of the base material, and may be laminated with another film interposed therebetween. For example, a silicon oxide film, a silicon oxynitride film, a resin film, a wet coating film, a metal film, an oxide film, or the like may be formed on the substrate, and then the transparent oxide film may be formed as the chemical-resistant layer on at least one of the substrates.

As described above, a Liquid Crystal Display (LCD), a touch panel device (TP), electronic paper, or the like, which is one of the flexible display devices, can be formed using the transparent resin substrate according to one embodiment of the present invention.

As described above, the transparent resin substrate according to one embodiment of the present invention has both excellent water vapor barrier performance and chemical resistance by dc sputtering with high mass productivity, and has excellent flexibility.