KR101005973B1 - Conductive laminate and manufacturing method thereof - Google Patents

Abstract

The present invention (a) a substrate; (b) a zinc oxide thin film doped with element M; And (c) an interlayer formed between the substrate and the zinc oxide based thin film and comprising an oxide M ′ ₂ O ₃ , wherein the dopant element M and M ′ of the oxide M ′ ₂ O ₃ are each independently A method of manufacturing a conductive laminate, the element selected from the group consisting of a Group 13 element and a transition metal having an oxidation number of +3, comprising: forming an intermediate layer including an oxide M ' ₂ O ₃ on a substrate; And forming a zinc oxide based thin film doped with element M 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 specific resistance, and having uniform physical properties over the entire surface, and a method of manufacturing the same.

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 transparent because it has a relationship inversely proportional to the concentration of electrons and mobility (ρ = 1 / (eμN), e: electric charge, μ: mobility, N: electron concentration). In order to reduce the specific resistance (ρ) of the electrode, 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 inventors have found that in manufacturing a zinc oxide based thin film on a substrate, the specific resistance of the thin film can be reduced by using hydrogen gas during deposition, but the heat / moisture resistance is lowered and it is difficult to secure uniformity of the specific resistance. In addition, the inventors have found that the problem of using the hydrogen gas can be solved by inserting an intermediate layer containing an oxide between the substrate and the zinc oxide thin film.

Accordingly, 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) a zinc oxide thin film doped with element M; And (c) an interlayer formed between the substrate and the zinc oxide thin film and comprising an oxide M ′ ₂ O ₃ ,

The dopant element M and the M 'of the oxide M' ₂ O ₃ are each independently a group 13 element and a method for producing a conductive laminate which is an element selected from the group consisting of a transition metal having an oxidation number of +3,

Forming an intermediate layer comprising oxide M ′ ₂ O ₃ on the substrate; And

Forming a zinc oxide-based thin film doped with element M 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) a zinc oxide thin film doped with element M; And (c) an interlayer formed between the substrate and the zinc oxide thin film and comprising an oxide M ′ ₂ O ₃ ,

The dopant element M and the M 'of the oxide M' ₂ O ₃ each independently provide a conductive laminate which is an element selected from the group consisting of a Group 13 element and a transition metal having an oxidation number of +3.

According to the present invention, in preparing a zinc oxide transparent conductive film on a substrate, an effect of increasing the electron concentration can be obtained by incorporating not only an inert gas such as argon gas but also hydrogen gas, wherein the substrate and the zinc oxide transparent conductive film By providing an intermediate layer of metal oxide in between, 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 based thin film can be improved by depositing it under a gas containing hydrogen when the zinc oxide thin film doped with element M is formed on the substrate. In addition, the present invention by interposing the intermediate layer containing the oxide M ' ₂ O ₃ between the substrate and the zinc oxide-based thin film doped with element M, it is possible to improve the heat / moisture resistance stability and the uniformity of the specific resistance Is characteristic.

When forming a zinc oxide based thin film doped with element M on a substrate as in the present invention, deposition on a gas containing hydrogen, preferably at elevated temperature, results in the formation of oxygen vacancy by hydrogen gas. Deficiency may act as an electron donor (donor) to increase the electron concentration, thereby reducing the specific resistance of the zinc oxide thin film may improve the electrical properties.

In addition, when the intermediate layer including the oxide M ' ₂ O ₃ is interposed between the substrate and the zinc oxide thin film doped with the element M as in the present invention, the high energy particles in the thin film are caused to collide with each other. Since the occurrence of defects can be reduced by the intermediate layer, it is possible to secure uniform electrical properties over the entire surface of the zinc oxide thin film to improve uniform resistivity and heat / moisture stability.

At this time, the effect of improving the heat / moisture stability by the interlayer insertion is greater when the thickness of the zinc oxide thin film is thin, which can be confirmed through FIGS. 1 and 2.

In the present invention, in the deposition for forming the zinc oxide thin film, its temperature range is not particularly limited. However, if the temperature at the time of deposition is too low or too high, it is difficult to form a good crystalline zinc oxide-based thin film, and the degree of crystalline directly affects the electron concentration or mobility, so that it can be deposited preferably in an elevated temperature region. It is possible to deposit more preferably at 100 to 400 ° C.

Further, in the present invention, the gas containing hydrogen may be composed of hydrogen and an inert gas, and the zinc oxide-based thin film may be formed by depositing a zinc oxide target doped with element M under such a mixed gas atmosphere. Non-limiting examples of the inert gas include argon gas. Optionally, even when the intermediate layer including the oxide M ' ₂ O ₃ is formed on the substrate, a target including the oxide M' ₂ O ₃ may be formed by depositing 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 effect of etching (etching) may appear to reduce the thickness of the zinc oxide thin film.

In the present invention, the intermediate layer may be deposited by chemical vapor deposition (CVD) and physical vapor deposition (PVD), such as evaporation, ion plating, sputtering, or the like. In addition, the zinc oxide-based thin film may be deposited by PVD (Physical Vapor Deposition) method, for example, ion-plating or sputtering.

Preferably, the intermediate layer and the zinc oxide-based thin film may be deposited by a sputtering method, and more preferably may be deposited by RF magnetron sputtering. However, the present invention is not limited to the above method, and is not particularly limited as long as it is a thin film deposition method.

For example, referring to one embodiment of the method for manufacturing a conductive laminate of the present invention, after placing the substrate and the oxide target in the sputtering chamber to face each other at a predetermined interval, and plasma-mixing 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 oxide thin film. Meanwhile, when the target is replaced with zinc oxide in the same system and the same process is performed, a zinc oxide thin film may be deposited on the substrate on which the oxide 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 be easily produced without a cumbersome process in that it is possible to continuously deposit the oxide M ' ₂ O ₃ thin film and the zinc oxide transparent conductive film in one system. However, the present invention is not limited to the method in which the oxide M ′ ₂ O ₃ 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 oxide M ′ ₂ O ₃ 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 doped with the element M may be represented by a chemical formula such as ZnO: M, wherein M is a dopant element and may be a transition metal having a Group 13 element or an oxidation number of +3. . Non-limiting examples of the dopant element M include B, Al, Ga, In, Tl, Sc, V, Cr, Mn, Fe, Co, Ni and the like. Preferably, the dopant element M is aluminum (Al) or gallium (Ga).

The dopant element may be doped with zinc oxide (ZnO) in the form of a + trivalent cation, and acts as an n-type dopant in which excess electrons are generated by substituting the Zn site for electrons of the zinc oxide-based transparent conductive film. The concentration can be increased. However, the content of the dopant element M 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.

On the other hand, the interlayer thin film of the present invention may include an oxide in the form of M ' ₂ O ₃ , wherein M' may be a group 13 element or a transition metal having an oxidation number of +3. Non-limiting examples of oxides M ' ₂ O ₃ include oxides of Group 13 elements on the periodic table (B ₂ O ₃ , Al ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , Tl ₂ O ₃ ) or transition metal oxides ( 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 ), and the like. Preferably, the oxide M ′ ₂ O ₃ is aluminum oxide (Al ₂ O ₃ ) or gallium oxide (Ga ₂ O ₃ ).

The substrate used in the present invention is not particularly limited as long as it is a transparent substrate, and non-limiting examples thereof include a glass substrate or a polymer substrate, and non-limiting examples of the polymer substrate include polyethylene terephthalate (PET) and polyethylene 2, PEN. 6-naphthalate (PE), polyether sulfone (PES), polyether imide (PEI), polymethylmethacrylate (PMMA), and polycarbonate (PC).

In this case, in the present invention, since the deposition may be performed in an elevated temperature range, preferably 100 to 400 ° C., the substrate is preferably heat resistant in the temperature range, and such a substrate is heat resistant at a glass substrate or 100 to 400 ° C. Polymer substrates can be used.

In this invention, although the thickness of the said intermediate | middle layer and the thickness of a zinc oxide type thin film are not specifically limited, It is preferable that they are each independently 10-300 nm. If the thickness of the intermediate layer is less than 10 nm, overall coverage problems are caused, and if it is more than 300 nm, the surface roughness increases, which is a problem. In addition, when the thickness of the zinc oxide thin film is less than 10 nm, the crystallinity decreases, which is not preferable.

In the conductive laminate of the present invention, the zinc oxide thin film may have an XRD peak shifted by + 0.05 ° to + 0.5 ° from the XRD peak when there is no intermediate layer including the oxide M ′ ₂ O ₃ . . At this time, the XRD peak is (002) peak of zinc oxide (ZnO) located between 2θ = 34 ° ± 0.5 ° by CuKα (λ = 0.154nm) radiation.

Although the shift value of the XRD peak may vary slightly depending on the measurement conditions, it is preferable that the XRD peak is in the range of + 0.05 ° to + 0.5 ° compared to the case where there is no intermediate layer based on CuKα (λ = 0.15405 nm) radiation. Do. If the XRD peak shift is smaller than the above range, the effect of improving the resistivity characteristics by the interlayer is negligible. If the XRD peak shift is smaller than the above range, deformation and / or stress of the crystal lattice are generated, which is not good for the resistivity. May affect

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 the following Examples. However, the following examples are merely to illustrate the present invention and the present invention is not limited by the following examples.

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

Interlayer Deposition

An Al ₂ O ₃ thin film was deposited on the glass substrate 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 55 nm.

The other sputtering conditions were about -260V of bias voltage, the pressure in a chamber 3x10 <^-3> rr, and the flow volume of argon (Ar) gas 50sccm.

Zinc Oxide Transparent Conductive Film Deposition

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

Sputtering conditions were outside of the bias voltage (bias voltage) 50sccm flow rate of the gas mixture of about -350V, pressure 3 × 10 ^-3 torr, a 2.8vol% ratio of H ₂ / Ar of H ₂ / Ar in the chamber, 200 ℃ Deposited at.

Example 2 Preparation of Ga doped ZnO / Al ₂ O ₃ Interlayer / Glass 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 30 nm.

Comparative Example 1 Preparation of Ga doped ZnO / Glass 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 glass substrate without depositing an intermediate layer, and no hydrogen gas was used during deposition.

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

A conductive laminate was prepared in the same manner as in Example 1 except that ZnO (Ga 5.5 wt% doping) was deposited directly on the glass substrate without depositing an intermediate layer.

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

A conductive laminate was prepared in the same manner as in Example 2, except that ZnO (doped 5.5 wt% Ga) was deposited directly on the glass substrate without depositing an intermediate layer, and no hydrogen gas was used during deposition.

Comparative Example 4 Ga doped ZnO / Glass 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 glass substrate without depositing the intermediate layer.

Experimental Example 1

Specific resistance of the transparent conductive films prepared in Example 1 and Comparative Examples 1 and 2 were measured for each position on the surface of the conductive film, and the results are shown in FIG. 1. In addition, the specific resistance of the transparent conductive films prepared in Example 2 and Comparative Examples 3 to 4 was measured for each position on the surface of the conductive film, and the results are shown in FIG. 2.

1 and 2 measure the conductive film center at 0, draw an arbitrary straight line passing through the zero point and intersecting the conductive film, and divide it equally into equal parts from the zero point to both sides, and in the order of being close to the zero point. -1), 2 (-2), 3 (-3) and 4 (-4) points were set and the specific resistance was measured at that point.

According to FIG. 1, in the case of Comparative Example 1 prepared without depositing an aluminum oxide interlayer and without using hydrogen, the uniformity of the specific resistance according to the measurement position was very bad. The resistivity increases sharply in the center (position 0), which is thought to be due to defect formation due to the collision of energetic particles. However, in the case of Comparative Example 2 prepared using hydrogen gas when growing a zinc oxide-based transparent conductive film, the distribution of the specific resistance was similar to that of Example 1 (not uniformity), but the figures were reduced as a whole. This is thought to be a result of the increase of the electron concentration by hydrogen gas. Finally, in Example 1 prepared by depositing an aluminum oxide interlayer and using hydrogen gas, the resistivity was greatly reduced and the uniformity according to the position was also excellent. This is thought to be the result of the combined effect of the aluminum oxide interlayer and the effect of hydrogen gas.

According to FIG. 2, only the thickness of the zinc oxide-based transparent conductive film differs from 30 nm, and similar results to those described in FIG. 1 are shown. However, when comparing the thickness of the zinc oxide-based transparent conductive film when compared with Figure 1 and 2, the effect by the aluminum oxide intermediate layer or hydrogen gas appeared more prominent.

Experimental Example 2

The specific resistance change before and after the constant temperature and humidity experiment with respect to the transparent conductive film prepared in Examples 1 to 2 and Comparative Examples 1 to 4 was measured, and the results are shown in Table 1 below. The constant temperature and humidity experiment was performed for 42 hours at 64 ° C. and 93% relative humidity.

Specimen Type Thickness of GZO Resistivity growth rate Comparative Example 1 (GZO / Glass)
GZO = 150 nm 10% Comparative Example 2 (GZO / Glass + H ₂ ) 16% Example 1 (GZO / Al ₂ O ₃ / Glass + H ₂ ) 4% Comparative Example 3 (GZO / Glass)
GZO = 30 nm 9x Comparative Example 4 (GZO / Glass + H ₂ ) 690 times Example 2 (GZO / Al ₂ O ₃ / Glass + H ₂ ) 19 times

According to Table 1, almost the same tendency change was observed regardless of the thickness of the zinc oxide transparent conductive film, but the increase in the specific resistance was large when the thickness of the transparent conductive film was thin. In particular, the specific resistance of the transparent conductive film decreases before the constant temperature and humidity experiment with hydrogen, but the increase in the specific resistance was greatest after the constant temperature and humidity experiment. However, this increase in resistivity could be greatly reduced by the use of aluminum oxide interlayers. Therefore, it was found that the heat / moisture resistance is improved by the intermediate layer.

[Experimental Example 3]

XRD of the transparent conductive films prepared in Example 1 and Comparative Examples 1 and 2 were analyzed, and the results are shown in FIG. 3. In the case of Comparative Example 1 (GZO / glass) in which only GZO was grown on a glass substrate without mixing hydrogen gas, the peak appeared to be quite broad and two peaks. This is because the peak is asymmetrically changed by damage, and in severe cases, the actual peak is divided into two. In Comparative Example 2 (GZO / glass, H ₂ flow) using hydrogen, a peak almost similar to that of Comparative Example 1 was observed. However, for Example 1 (GZO / Al ₂ O ₃ / glass, H ₂ flow) with Al ₂ O ₃ interlayers and with hydrogen, the peak shifted slightly to a high angle (ie, ~ 34.3 °). → 34.38 °), the width is sharpened and symmetrically changed.

1 is a result of measuring the specific resistance of the transparent conductive films prepared in Example 1 and Comparative Examples 1 and 2 for each position on the surface of the conductive film.

2 is a result of measuring the specific resistance of the transparent conductive films prepared in Example 2 and Comparative Examples 3 to 4 by position on the surface of the conductive film.

3 is XRD analysis results of the transparent conductive films prepared in Example 1 and Comparative Examples 1 and 2;

Claims (10)

(a) a substrate; (b) a zinc oxide thin film doped with element M; And (c) an interlayer formed between the substrate and the zinc oxide thin film and comprising an oxide M ′ ₂ O ₃ , The dopant element M and the M 'of the oxide M' ₂ O ₃ are each independently a group 13 element and a method for producing a conductive laminate which is an element selected from the group consisting of a transition metal having an oxidation number of +3, Forming an intermediate layer comprising oxide M ′ ₂ O ₃ on the substrate; And Forming a zinc oxide-based thin film doped with element M on the intermediate layer, The zinc oxide thin film is deposited under a gas containing hydrogen, The zinc oxide based thin film has a XRD peak shifted by + 0.05 ° to + 0.5 ° from the XRD peak when there is no intermediate layer including the oxide M ' ₂ O ₃ . (The XRD peak is the (002) peak of zinc oxide (ZnO) located between 2θ = 34 ° ± 0.5 ° by CuKα (λ = 0.154 nm) radiation. The method of claim 1, wherein the zinc oxide thin film is deposited at 100 to 400 ° C. 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 method of claim 1, wherein the intermediate layer is deposited by a method selected from sputtering, ion plating, and evaporation; The zinc oxide thin film is a method of manufacturing a conductive laminate, characterized in that the deposition by sputtering. The method of manufacturing a conductive laminate according to claim 1, wherein the substrate is a glass substrate or a polymer substrate having heat resistance at 100 to 400 ° C. The method of claim 1, wherein the dopant element M is aluminum (Al) or gallium (Ga), and the oxide M ′ ₂ O ₃ is aluminum oxide (Al ₂ O ₃ ) or gallium oxide (Ga ₂ O ₃ ). The manufacturing method of a phosphorus conductive laminated body. The method of manufacturing a conductive laminate according to claim 1, wherein the thickness of the intermediate layer and the thickness of the zinc oxide thin film are each independently 10 to 300 nm. The method according to claim 1, wherein the content of the dopant element M in the zinc oxide thin film is 0.1 to 10% by weight. delete A conductive laminate produced according to the method of any one of claims 1 to 8.

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