KR101236039B1 - Conductive laminate and manufacturing method thereof - Google Patents

Abstract

The present invention (a) a substrate; (b) zinc oxide thin film; And (c) a method of manufacturing a conductive laminate formed between the substrate and the zinc oxide thin film and including an inorganic layer, the method comprising: forming an intermediate layer including an inorganic material on the substrate; And forming a zinc oxide based thin film on the intermediate layer, wherein the zinc oxide based thin film is deposited under a gas containing hydrogen. The present invention also relates to a conductive laminate produced according to the above method.

Description

Conductive Laminates and Manufacturing Method Thereof {CONDUCTIVE LAMINATE AND MANUFACTURING METHOD THEREOF}

The present invention relates to a conductive laminate having improved heat resistance, moisture resistance, and resistivity, and more particularly to a conductive laminate including a substrate, an interlayer containing an inorganic material, and a zinc oxide thin film. It relates to a manufacturing method of.

Transparent electrodes are used in various types of electrodes of various displays, photoelectric conversion elements such as solar cells, touch panels, and the like, and are manufactured by forming transparent conductive thin films on transparent substrates such as glass and transparent films. Currently, the transparent conductive material mainly used is indium tin oxide (ITO) doped with tin, and has excellent transparency and low specific resistance (1 × 10 ⁻⁴ to 2 × 10 ⁻⁴ Ωcm). Known.

The method of manufacturing a transparent conductive thin film includes vacuum deposition methods such as sputtering, chemical vapor deposition (CVD), ion beam deposition, and pulsed laser deposition, and spray coating. There are various methods, such as coating, spin coating, and wet methods such as dip coating. Among these methods, a vacuum deposition method such as sputtering is more preferred, and since the vacuum deposition method uses plasma, it is possible to grow a film having high particle energy, thereby obtaining a high quality film having a higher density than other methods. . In addition, there is an advantage that the thin film of good quality can be grown at low temperature without additional heat treatment.

Recently, the demand for ITO is increasing rapidly as the flat display market grows. However, due to supply and demand instability due to high price of indium and harmfulness to human body, development of low-cost transparent conductive material that can replace ITO is required. to be.

Such substitutes include tin oxide (SnO ₂ ), zinc oxide (ZnO), and the like. In this regard, attempts have been made to produce a conductive thin film having a low specific resistance (2 × 10 ⁻⁴ to 3 × 10 ⁻⁴ Ωcm) by doping aluminum (Al) to zinc oxide. It is known that zinc oxide (ZnO) is a semiconductor material having a wide bandgap (~ 3.3ev), and can have excellent transmittance (more than 85%) and low resistivity through doping, and is relatively inexpensive for doped zinc oxide. And, since it is a material harmless to the human body, it is receiving great attention as a material that can replace ITO. Currently, research is mainly focused on materials for transparent electrodes made of zinc oxide (ZnO) containing aluminum (Al), gallium (Ga), silicon (Si) and / or indium (In). There is a problem that needs to be solved because it does not reach ITO yet.

In general, the specific resistance of a transparent conductive film having a constant thickness is inversely proportional to electron concentration and mobility (ρ = 1 / (eμN), e: electric charge, μ: mobility, N: electron concentration), so that the transparent electrode In order to reduce the specific resistivity of ρ, the electron concentration must be increased or the mobility must be increased. In general, as a method of easily increasing the electron concentration, it is conceivable to increase the amount of dopant added to the sputtering target. However, if the electron concentration is above a certain concentration (N> 1 × 10 ²⁰ cm ^-3 ), the mobility decreases due to the collision between the electron and the dopant, the scattering center (N <1 × 10 ^20). The case of cm ⁻³ is known to depend on scattering at the grain boundary.). That is, an increase in the electron concentration obtained by increasing the amount of dopant added to the sputtering target entails a decrease in mobility, and as a result, the specific resistance is maintained as it is or rather increased. The relationship between electron concentration and mobility has been experimentally demonstrated by several researchers. Therefore, there is a limit in improving the electrical characteristics of a transparent conductive film by the existing method.

The present invention uses hydrogen gas as a method for improving the electrical properties when the zinc oxide thin film is deposited on the substrate, and also between the zinc oxide thin film and the substrate to improve heat resistance, moisture resistance, and uniformity of electrical properties. An object of the present invention is to provide a method for producing a conductive laminate, and a conductive laminate produced thereby.

The present invention (a) a substrate; (b) zinc oxide thin film; And (c) an interlayer formed between the substrate and the zinc oxide thin film and including an inorganic material, the method comprising:

Forming an intermediate layer including an inorganic material on the substrate; And

Forming a zinc oxide based thin film on the intermediate layer;

The zinc oxide-based thin film provides a method for producing a conductive laminate, characterized in that deposited under a gas containing hydrogen.

The present invention also relates to a conductive laminate prepared according to the above method, specifically

(a) a substrate; (b) zinc oxide thin film; And (c) an interlayer formed between the substrate and the zinc oxide thin film and including an inorganic material.

According to the present invention, in preparing a zinc oxide-based transparent conductive film on a substrate, an inert gas such as argon gas, as well as hydrogen gas may be mixed to obtain an effect of increasing electron concentration to improve electrical characteristics, wherein the substrate and oxidation By providing an intermediate layer made of an inorganic material between the zinc-based transparent conductive films, it is possible to ensure heat / moisture stability and uniformity of electrical properties.

The present invention is characterized in that the electrical properties of the zinc oxide thin film can be improved by depositing it under a gas containing hydrogen when the zinc oxide thin film is formed on a substrate. In addition, the present invention is characterized by improving the uniformity of heat / moisture resistance and specific resistance by interposing an intermediate layer containing an inorganic material between the substrate and the zinc oxide thin film.

When forming a zinc oxide thin film on a substrate as in the present invention, when deposited on a gas containing hydrogen, preferably deposited at 100 ° C. or less, it remains in the apparatus for deposition to deteriorate the electrical properties of the zinc oxide thin film. Hydrogen can hold moisture to increase the electron concentration, thereby improving the electrical properties of the zinc oxide thin film.

On the other hand, when hydrogen is mixed in the deposition, the heat / moisture stability of the zinc oxide thin film may be lowered, and it may be difficult to secure uniformity of specific resistance. However, when an intermediate layer containing an inorganic material is interposed between the substrate and the zinc oxide thin film as in the present invention, the crystallinity of the zinc oxide thin film is improved and defects are generated due to collision between high energy particles. Since it is possible to reduce the uniformity of the electrical properties throughout the surface of the zinc oxide thin film to improve the specific resistance uniformity and heat / moisture stability.

In the present invention, in the deposition for forming the zinc oxide thin film, its temperature range is not particularly limited. Preferably, it can be deposited in an elevated temperature range, and more preferably, it can be deposited at 10 to 100 ° C., but below 10 ° C., the quality of the thin film formed is significantly reduced, and if it is above 100 ° C., the substrate is a plastic material. Damage occurs.

In addition, in the present invention, the hydrogen-containing gas may be composed of hydrogen and an inert gas, and the zinc oxide-based thin film may be formed by depositing a zinc oxide-based target under such a mixed gas atmosphere. Non-limiting examples of the inert gas include argon gas. Optionally, even when the intermediate layer including the inorganic material is formed on the substrate, it may be formed by depositing a target including the inorganic material under the gas containing hydrogen.

In the present invention, the hydrogen may be 0.1 to 20% by volume in the total gas. If the content of hydrogen gas is less than 0.1% by volume, the effect of improving the electrical properties is insignificant, and if it is more than 20% by volume, the transmittance of the formed zinc oxide thin film may be reduced.

The intermediate layer and the zinc oxide thin film may be independently deposited by a method selected from the group consisting of sputtering, ion plating, pulsed laser deposition, zolgal method, CVD, and spray deposition, but is not limited thereto. The method is not particularly limited. In particular, when the zinc oxide thin film is deposited at room temperature, various methods as exemplified above may be used, but pulsed laser deposition, ion plating, or sputtering is preferable.

For example, referring to one embodiment of the method for manufacturing a conductive laminate of the present invention, after placing the substrate and the inorganic target in the sputtering chamber to face each other at a predetermined interval, and plasma the mixed gas of hydrogen and argon (Ar), The hydrogen plasma and the argon plasma are accelerated by the bias voltage applied to the target to collide with the target. The target material separated by the collision of the hydrogen plasma and the argon plasma is deposited on the substrate to form an inorganic thin film. Meanwhile, when the target is replaced with zinc oxide only in the same system and the same process is performed, a zinc oxide thin film may be deposited on the substrate on which the inorganic intermediate layer is formed. At this time, the thickness of the thin film can be easily adjusted by adjusting the sputtering time or the like.

In particular, the method of the present invention can easily prepare a thin film without the cumbersome process in that it is possible to continuously deposit a thin film of an inorganic material and a zinc oxide transparent conductive film in one system. However, the present invention is not limited to the method in which the inorganic thin film and the zinc oxide thin film are continuously deposited in one system, and may be deposited independently. For example, after depositing only the inorganic thin film on the substrate, the chamber may be moved to deposit a zinc oxide thin film in another chamber.

In the present invention, the zinc oxide based thin film may be formed of a zinc oxide based material and doped with a dopant for imparting electrical conductivity. As a non-limiting example, the zinc oxide thin film may be doped with an element selected from the group consisting of Ga, Al, In, B, Si, and Ge or an oxide of the element. Preferably, the dopant may be Al, Ga, or B.

However, the content of the dopant in the zinc oxide thin film is preferably in the range of 0.1 to 10% by weight in order not to reduce the mobility of electrons. In particular, the content of Al in the zinc oxide thin film is 5% by weight or less, and the content of Ga is preferably 10% by weight or less. If more dopant is added than the amount described above, there is a fear that the specific resistance increases.

Meanwhile, the interlayer thin film of the present invention includes an inorganic material, which is composed of an oxide of a (semi) metal, a compound of a (semi) metal and a nonmetal of Group 5, and a compound of a (semi) metal and a nonmetal of Group 6 Can be selected from the group. Preferably, the inorganic material is Al ₂ O ₃ , Ga ₂ O ₃ , B ₂ O ₃ , In ₂ O ₃ , Tl ₂ O ₃ , Sc ₂ O ₃ , V ₂ O ₃ , Cr ₂ O ₃ , Mn ₂ O ₃ , Fe ₂ O ₃ , Co ₂ O ₃ , Ni ₂ O ₃ , Nb ₂ O ₅ , SiO ₂ , Si ₃ N ₄ , CeO ₂ , TiO ₂ , Y ₂ O ₃ , CaO and MgO It may be, but is not limited thereto.

The substrate used in the present invention is not particularly limited as long as it is a substrate having transparency, and non-limiting examples thereof include a glass substrate or a polymer substrate.

In addition, as a non-limiting example, the polymer substrate may be polyethylene terephthalate (PET), polyethylene 2,6 naphthalate (PEN), polyethylene (PE), polypropylene (PP), polyvinyl alcohol (PVA), polyether sulfone ( PES), polyether imide (PEI), polymethyl methacrylate (PMMA), polyvinyl chlorite (PVC) and polycarbonate (PC).

When the deposition on the polymer substrate, the glass transition temperature (Tg) of the polymer substrate is low, it is preferable to deposit at a low temperature, preferably 100 ℃ or less. However, the zinc oxide-based transparent conductive material shows the highest electrical conductivity at a high temperature of 200 to 300 ° C. on the basis of the sputter, and may be inferior when deposited at a temperature lower than the above temperature.

However, even if the polymer substrate is used in accordance with the present invention and deposited at a low temperature of 100 ° C. or lower, the electrical conductivity of the formed zinc oxide thin film can be improved by depositing under an inert gas atmosphere containing hydrogen.

Also, in general, the polymer substrate has poor surface smoothness due to the characteristics of the material, and is weak in plasma or heat, so that the crystallinity of the zinc oxide-based conductive film deposited thereon may be reduced. In addition, the polymer substrate may be inferior in moisture resistance because moisture is relatively permeable.

However, even when the polymer substrate is used according to the present invention, by inserting an intermediate layer containing an inorganic material, it is possible to improve the moisture resistance stability of the zinc oxide thin film formed on the intermediate layer, and also improve the crystallinity of the zinc oxide thin film. It can reduce the resistivity.

In the present invention, the thickness of the zinc oxide-based thin film may be 10 ~ 500nm, preferably 10 ~ 100nm. If the thickness of the zinc oxide thin film is less than 10 nm, the electrical conductivity is inferior, and if it is more than 500 nm, the transparency is inferior.

In addition, the thickness of the intermediate layer may be 10 ~ 200nm. If the thickness of the intermediate layer is less than 10 nm, overall coverage problems are caused, and if it is more than 200 nm, the surface roughness increases, which is a problem.

In addition, the conductive laminate according to the present invention may have an average transmittance of 80% or more at 400 ~ 750nm.

On the other hand, the conductive laminate of the present invention is not limited to a particular use, but may be preferably used as an electrode substrate used in solar cells, liquid crystal displays, electroluminescent displays, and the like, and may also be applied to TFT (Thin Film Transistor) and the like.

Hereinafter, the present invention will be described in detail with reference to examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Example 1 Preparation of Ga doped ZnO / Al ₂ O ₃ Interlayer / PET with H ₂ Conductive Laminate

Interlayer Deposition

An Al ₂ O ₃ thin film was deposited on a PET film (Dupont-Teijin melinex 504st) using an RF magnetron sputter. As the sputtering target, an Al ₂ O ₃ sintered compact target was used, and the thickness of the deposited Al ₂ O ₃ thin film was 50 nm.

Other sputtering conditions were about -350V of bias voltage, the pressure in a chamber 3x10 <^-3> torr, and the flow volume of argon (Ar) gas 50sccm.

Zinc Oxide Transparent Conductive Film Deposition

A Ga 5.5 wt% doped ZnO (GZO) thin film was deposited on the prepared Al ₂ O ₃ intermediate layer using an RF magnetron sputter. The sputtering target was a ZnO (Ga 5.5 wt% doped) sintered compact target, and the thickness of the deposited ZnO thin film was 150 nm.

Sputtering conditions other than the bias voltage (bias voltage) was a flow rate of 50sccm of gas mixture of about -70V, pressure 3 × 10 ^-3 torr, a 2.8vol% ratio of H ₂ / Ar of H ₂ / Ar in the chamber.

Example 2 Ga doped ZnO / Al ₂ O ₃ interlayer / PET with H ₂ conductive laminate

A conductive laminate was prepared in the same manner as in Example 1, except that the zinc oxide transparent conductive film was deposited to a thickness of 50 nm.

Comparative Example 1 Ga doped ZnO / PET without H ₂ conductive laminate

A conductive laminate was prepared in the same manner as in Example 1, except that ZnO (Ga 5.5 wt% doped) was deposited directly on the PET film without depositing an intermediate layer, and no hydrogen gas was used during deposition.

Comparative Example 2 Preparation of Ga doped ZnO / PET with H ₂ Conductive Laminate

A conductive laminate was produced in the same manner as in Example 1, except that ZnO (Ga 5.5 wt% doping) was deposited directly on the PET film without depositing the intermediate layer.

Comparative Example 3 Preparation of Ga doped ZnO / PET without H ₂ Conductive Laminate

A conductive laminate was manufactured in the same manner as in Example 2, except that ZnO (Ga 5.5 wt% doped) was deposited directly on the PET film without depositing an intermediate layer, and hydrogen gas was not used during deposition.

Comparative Example 4 Preparation of Ga doped ZnO / PET with H ₂ Conductive Laminate

A conductive laminate was produced in the same manner as in Example 2, except that ZnO (Ga 5.5 wt% doping) was deposited directly on the PET film without depositing the intermediate layer.

[Experimental Example]

The specific resistance of the transparent conductive films prepared in Examples 1 to 2 and Comparative Examples 1 to 4 was measured, and the heat resistance and moisture resistance were measured by measuring the sheet resistance change before and after the constant temperature and humidity experiment, and the results are shown in Table 1 below. It was. The constant temperature and humidity experiment was performed for 42 hours at 64 ° C. and 95% relative humidity. In addition, specific resistance and sheet resistance were measured using Mitsubishi's Loresta-Gp 4 point probe.

Example 1 Comparative Example 1 Comparative Example 2 Example 2 Comparative Example 3 Comparative Example 4 Middle layer Al ₂ O ₃ - - Al ₂ O ₃ - - Transparent conductive material ZnO: Ga (GZO) ZnO: Ga (GZO) ZnO: Ga (GZO) ZnO: Ga (GZO) ZnO: Ga (GZO) ZnO: Ga (GZO) Deposition atmosphere H ₂ / Ar Ar H ₂ / Ar H ₂ / Ar Ar H ₂ / Ar Transparent conductive film thickness (nm) 150 ± 10 150 ± 10 150 ± 10 50 ± 10 50 ± 10 50 ± 10 Sheet resistance (Ω) 55 124 69 137 912 284 Resistivity (Ω㎝) 7.6 × 10 ^-4 1.9 × 10 ^-3 9.1 × 10 ^-4 1.7 × 10 ^-3 5.2 × 10 ^-3 1.6 × 10 ^-3 Charge concentration (cm ^-3 ) 1.5 × 10 ²¹ 6.8 × 10 ²⁰ 1.0 × 10 ²¹ 9.3 × 10 ²⁰ 4.6 × 10 ²⁰ 9.5 × 10 ²⁰ Surface resistance after constant temperature and humidity experiment (Ω) 106 169 189 930 2736 2587 Sheet resistance increase rate 1.93 times 1.36 times 2.74 times 6.79 times 3.00 times 9.11 times

According to Table 1, when hydrogen is used, the resistivity decreases and the charge concentration increases. Accordingly, when the zinc oxide-based transparent conductive film was formed, hydrogen gas was mixed to increase the electron concentration, thereby improving electrical characteristics.

In addition, the surface resistance of the transparent conductive film was decreased before the constant temperature and humidity experiment with hydrogen, but the increase of the surface resistance was significant after the constant temperature and humidity experiment. At this time, when the thickness of the zinc oxide transparent conductive film was thin, the increase in sheet resistance was large. However, this increase in sheet resistance could be greatly reduced by the use of an aluminum oxide intermediate layer. Therefore, it was found that the heat / moisture resistance is improved by the intermediate layer.

Claims (11)

(a) a substrate; (b) zinc oxide thin film; And (c) an interlayer formed between the substrate and the zinc oxide thin film and including an inorganic material, the method comprising: Forming an intermediate layer including an inorganic material on the substrate; And Forming a zinc oxide based thin film on the intermediate layer; The zinc oxide thin film is to be deposited under a gas containing hydrogen, The inorganic material is Al ₂ O ₃ , Ga ₂ O ₃ , B ₂ O ₃ , Tl ₂ O ₃ , Sc ₂ O ₃ , V ₂ O ₃ , Cr ₂ O ₃ , Mn ₂ O ₃ , Fe ₂ O ₃ , Co _{2 O 3, Ni 2 O 3,} Nb 2 O 5, SiO 2, Si 3 N 4, TiO 2, Y 2 O 3, a method for producing a conductive laminate is selected from the group consisting of CaO and MgO. The method of claim 1, wherein the zinc oxide thin film is doped with an element selected from the group consisting of Ga, Al, In, B, Si, and Ge or an oxide of the element. delete The method of claim 1, wherein the zinc oxide thin film is deposited at 10 to 100 ℃. The method of claim 1, wherein the hydrogen is 0.1 to 20% by volume in the total gas manufacturing method of the conductive laminate. The conductive laminate of claim 1, wherein the intermediate layer and the zinc oxide thin film are each independently deposited by a method selected from the group consisting of sputtering, ion plating, pulsed laser deposition, zolgal method, CVD, and spray deposition. Manufacturing method. The method of claim 1, wherein the substrate is polyethylene terephthalate (PET), polyethylene 2,6 naphthalate (PEN), polyethylene (PE), polypropylene (PP), polyvinyl alcohol (PVA), polyether sulfone (PES) , Polyether imide (PEI), polymethyl methacrylate (PMMA), polyvinyl chlorite (PVC) and polycarbonate (PC) selected from the group consisting of a polymer substrate or a glass substrate characterized in that the production of a conductive laminate Way. The method of claim 1, wherein the zinc oxide thin film has a thickness of 10 to 500 nm. The method for manufacturing a conductive laminate according to claim 1, wherein the intermediate layer has a thickness of 10 nm to 200 nm. The method for manufacturing a conductive laminate according to claim 1, wherein the average transmittance is 400% or more at 400 to 750 nm. delete