KR100839337B1 - In2O3-ZnO-Sb2O5 target composition and its manufacturing method required for depositing n-type transparent conductive thin film by sputtering method - Google Patents

Abstract

The present invention relates to a conductive In ₂ O ₃ -ZnO-Sb ₂ O ₅ based ceramic material used as a material of an n-type in-less transparent conductive thin film and a thin film deposited by a sputtering method using the material. A method for producing a target, in which the content of indium is increased by fixing the ratio of Zn cations to Sb cations at 2: 1 (Zn: Sb = 2: 1) and increasing the simultaneous addition of Zn cations and Sb cations instead of In cations. The present invention relates to the production of dense In ₂ O ₃ -ZnO-Sb ₂ O ₅ based ceramic targets having a reduced sintering density and a sintered density of 97% or more of theoretical density.

In the present invention, when Zn cations and Sb cations are simultaneously added instead of In cations, volatilization of Sb cations occurs at a high temperature when In ₂ O ₃ -ZnO-Sb ₂ O ₅ -based ceramic targets are prepared. In order to suppress this, first, ZnSb ₂ O ₆ , which does not generate volatilization of Sb cations even at high temperatures, is synthesized and added together with ZnO such that the ratio of Zn cations and Sb cations is 2: 1. By doing so, when sintered by a general solid-state method, there is an advantage that the composition nonuniformity and densification problems due to volatilization of the Sb cation can be easily solved.

Description

Composition and fabrication of In2O3-ZnO-Sb2O5 targets for n-type transparent conducting oxide film deposition through sputteirng methods}

Figure 1 shows an embodiment composition of the present invention shows the composition of the content and state diagram of the indium oxide (In ₂ O ₃ ), zinc oxide (ZnO) and antimony oxide (Sb ₂ O ₅ ).

2 is a graph showing the results of phase analysis of the phase development of the sintered compact by XRD after sintering the composition of the embodiment of the present invention at 1500 ° C. in oxygen for 2 hours.

FIG. 3 is a graph showing the lattice constant change of the In ₂ O ₃ phase generated according to the change in the addition amount using the XRD result of FIG. 2.

Figure 4 shows a microstructure photograph of the embodiment of the present invention after sintering in oxygen for 2 hours at 1500 ℃ in the development of the sintered body using an electron microscope.

5 is a graph showing the results of analyzing the electrical properties of the sintered body after sintering at 1500 ° C. in oxygen for 2 hours in an embodiment of the present invention using a Hall effect meter.

The present invention relates to a conductive In ₂ O ₃ -ZnO-Sb ₂ O ₅ based ceramic material used as a material of an n-type in-less transparent conductive thin film and a thin film deposited by a sputtering method using the material. As a specific method for producing a target, more specifically, the ratio of Zn and Sb cations is fixed to 2: 1 (Zn: Sb = 2: 1), and the amount of simultaneous addition of Zn and Sb cations instead of In cations is increased. The present invention relates to the production of dense In ₂ O ₃ -ZnO-Sb ₂ O ₅ based ceramics targets having a reduced content of indium and a sintered density of not less than 97% of theoretical density.

The transparent conductive thin film is generally a material having an electrical conductivity of 10 ³ Ω ^-1 cm ^-1 , a light transmittance of 80% or more in the visible region, and a bandgap of 3.5 eV or more, and is relatively high in electrical conductivity and light transmittance in the visible region. The company has been interested in optical materials and has been the subject of research for many years.

Transparent conductive thin films are used in applications such as liquid crystal displays and solar cells, heat ray reflecting films for window panes, and antistatic films, and are classified into n-type and p-type according to the type of carriers contributing to electrical conductivity. Among n-type transparent conductive thin films, indium oxide (In ₂ O ₃ ) films containing 2-10 wt% tin oxide (SnO ₂ ) have many uses due to their high electrical conductivity and excellent transparency. Indium tin oxide (In ₂ O ₃ -SnO ₂ ) is hereinafter referred to as indium tin oxide (ITO). Such ITO is expensive because it contains 90 wt% or more of expensive indium oxide (In ₂ O ₃ ), and has a disadvantage of supply and demand imbalance with the development of the display industry.

As a transparent conductive ceramic material to replace ITO, zinc oxide (ZnO), tin oxide (SnO ₂ ) or indium zinc oxide-tin oxide (In ₂ O ₃ -ZnO-SnO ₂ ) compounds and the like are replaced according to such requirements. Although a lot of research has been conducted, the biggest reason why these materials are not applied for displays compared to ITO is that the electrical resistance properties are in absolute inferiority, and the main focus is on developing a dopant.

In the case of zinc oxide (ZnO), there is a problem in temperature rise due to lack of stability in the air over time. On the other hand, in order to obtain a low resistance film, indium, aluminum, boron, gallium, germanium and the like have been studied as impurities, but ZnO-Al ₂ O ₃ based aluminum oxide and ZnO-Ga ₂ O added several at% of gallium oxide _{The third} system is partially commercialized. However, in order for zinc oxide (ZnO) to be applied as an ITO substitute, there are still many problems to be solved, such as stability of film formation conditions, film adhesion strength, and etching characteristics.

Although the tin oxide (SnO ₂ ) based transparent conductive thin film is chemically stable and relatively inexpensive than indium oxide, the transparency and conductivity are inferior to that of the indium oxide (In ₂ O ₃ ) based transparent conductive film. It is also known that the etching property against acid is bad. Therefore, it can be said that it is difficult to implement characteristics that can replace ITO.

In the case of the indium oxide-tin oxide-zinc oxide compound composition, the solid solution range for indium oxide can be effectively expanded by co-substituting the Zn cation and the Sn cation instead of the In cation. It is expected that the expansion of the solid solution area will significantly reduce the amount of indium oxide, and thus, the possibility of replacing ITO may be sufficient. However, the transmittance and electrical properties corresponding to ITO have not been reached.

The first object of the present invention is to sputter by using a sintered body of a compound containing indium oxide (In ₂ O ₃ ), zinc oxide (ZnO) and antimony oxide (Sb ₂ O ₅ ) in an n-type transparent conductive material, It is an object of the present invention to provide a conductive In ₂ O ₃ -ZnO-Sb ₂ O ₅ based ceramic material capable of depositing thin films with better thermal stability, electrical conductivity and light transmittance than conventional ITO.

The second object of the present invention has been drawn to solve the problems of the prior art as described above, since supply and demand of indium oxide, the main material of ITO, which is currently used most widely for general use, is unstable and very expensive in terms of price (100 10,000 won / 1kg, as of 2006), to develop a more general purpose low cost material with reduced content of indium oxide.

The third object of the present invention is to more easily solve the problems of composition nonuniformity and densification due to volatilization of Sb cations when the In ₂ O ₃ -ZnO-SnO ₂ -based ceramic targets are synthesized by a general solid-state method. An object of the present invention is to provide a method for producing a dense In ₂ O ₃ -ZnO-SnO ₂ based ceramics target having a density of 97% or more.

According to the present invention, a fixed ratio (Zn: Sb = 2: 1) of Zn cations and Sb cations during the preparation of a target required for depositing an n-type indium oxide-based transparent conductive thin film by a sputtering method is fixed. An object of the present invention is to prepare an n-type transparent conductive sputtering target having a reduced content of indium oxide by increasing the amount of simultaneous addition of cations. In this case, Zn cations (Zn ²⁺ ) and Sb cations (Sb ⁵⁺ ), which have different charge numbers, are co-substituted in place of In cations (In ³⁺ ) at a 2: 1 ratio to expand the solid solution range due to the charge compensation effect. Could achieve.

On the other hand, In place of Zn cation to cation, and Sb by simultaneous addition of the cationic _{In 2 O 3 -ZnO-Sb 2} O 5 based ceramics to suppress the volatilization of Sb cations manufacturing the target, that is, first a volatile cation of Sb at high temperatures occur ZnSb ₂ O ₆ is synthesized and added together with ZnO such that the ratio of Zn cations and Sb cations is 2: 1. By doing so, when sintered by a general solid-state method, there is an advantage that the composition nonuniformity and densification problems due to volatilization of the Sb cation can be easily solved.

Hereinafter, the present invention will be described in detail through examples. However, the following examples are not intended to limit the scope of the present invention by one embodiment of the present invention.

Example 1

In ₂ O ₃ -ZnO-Sb ₂ O ₅ target manufacturing method required to form an indium oxide-based thin film, an n-type oxide transparent conductor, ZnSb ₂ O ₆ which does not volatilize Sb cation even at high temperature is synthesized together with ZnO. At this time, the ratio of Zn cation and Sb cation was 2: 1. In ₂ O ₃ powder, ZnSb ₂ O ₆ powder, and ZnO powder were mixed in the respective compositions shown in Fig. 1, treated with a ball mill for 24 hours, and then cooled to 200 MPa using cold isostatic pressing. After maintaining for 3 minutes, the molded specimen was injected with oxygen and sintered at 1500 ° C. for 2 hours, thereby preparing an In ₂ O ₃ -ZnO-Sb ₂ O ₅ target.

At this time, as shown in the X-ray phase diffraction analysis as shown in Figure 2, when sintered at 1500 ℃ in oxygen, as the addition amount of Zn ²⁺ and Sb ⁵⁺ in a 2: 1 ratio to pure In ₂ O ₃ , Until x = 5 (In ³⁺ : Zn ²⁺ : Sb ⁵⁺ = 85: 10: 5), which is assumed to be the co-substitution dissolution limit, only the In ₂ O ₃ peak of the cubic bixbyite structure of single phase is observed, but the amount of addition is increased In this case, a β-Zn ₇ Sb ₂ O ₁₂ phase having a spinel structure is formed at x = 7 (In ³⁺ : Zn ²⁺ : Sb ⁵⁺ = 79: 14: 7) to form a coexistence region of two phases. It can be seen that the fraction of the spinel phase of the phase increases with increasing.

Figure 3 shows the change in lattice constant with increasing simultaneous addition of Zn ²⁺ and Sb ⁵⁺ in a ratio of 2: 1. The lattice constant of In ₂ O ₃ phase of Cubic bixbyite structure decreases rapidly until x = 5 (In ³⁺ : Zn ²⁺ : Sb ⁵⁺ = 85: 10: 5) with increasing amount It was observed to remain constant at x = 7 (In ³⁺ : Zn ²⁺ : Sb ⁵⁺ = 79: 14: 7) which increased the amount added. This reduction in the lattice constant is determined by the results shown because of In ³⁺ (0.080nm) have an ionic radius smaller Zn ²⁺ (0.074nm) and Sb ⁵⁺ (0.060nm) is employed relative to the simultaneous substitution to the In ₂ O ₃ In other words, the lattice constant does not change at x = 7 beyond the employment limit.

4 is a microstructure photograph of a specimen sintered at 1500 ° C. in oxygen using a scanning electron microscope (SEM, Jeol, JSM-5400, Japan). It can be seen that almost no pores were present in all specimens and the sintered density was completely densified to more than 97% of theoretical density. Due to the complete employment of Zn ²⁺ and Sb ⁵⁺ , coarse particle size was maintained up to x = 5 composition regardless of the amount added. It was then observed that as the amount added increased, the particle size drastically decreased with the formation of the secondary phase. That is, in the case of x = 7, the β-Zn ₇ Sb ₂ O ₁₂ phase generated at the same time as the reduction of the In ₂ O ₃ phase is present in the grain boundary, and the grain growth is inhibited by preventing the movement of the grain boundary. In addition, in the case of x = 9, by increasing the fraction of β-Zn ₇ Sb ₂ O ₁₂ phase, such a particle growth inhibitory effect is more pronounced.

5 is a graph showing the change in electrical characteristics of the specimen sintered at 1500 ℃ in oxygen using a Hall Effect measuring instrument (Ecopia, HMS-3000, Korea). The In ₂ O ₃ phase has a nonstoichiometric formula of In ₂ O _3-δ when sintered in a reducing atmosphere, and it is known that the In ₂ O ₃ phase exhibits n-type electrical conductivity. In the case of the present invention, by sintering in an oxygen atmosphere for densification of the specimen, it is determined that the electrical conductivity of the pure In ₂ O ₃ phase of x = 0 will have a very low value. As the co-substitution of Zn ²⁺ and Sb ⁵⁺ increases in pure In ₂ O ₃ with x = 0, the electrical conductivity increases with increasing the amount of addition, and then reaches a maximum at the solid solution limit x = 5, Increasing the amount above the limit showed a decrease. This is due to the decrease in particle size due to precipitation of the secondary phase (β-Zn ₇ Sb ₂ O ₁₂ ).

When using a target made of a dense conductive In ₂ O ₃ -ZnO-Sb ₂ O ₅ based sintered compact having a sintered density of the present invention configured as described above 97% or more of theoretical density, it is inexpensive compared to the currently used general purpose ITO. There is an effect that it is possible to manufacture the n-type conductive sputtering target having excellent electrical properties.

Claims (3)

delete Each component of indium oxide, zinc oxide, and antimony oxide in terms of its metal atomic ratio InO _1.5 / (InO _1.5 + ZnO + SbO _2.5 ) = 0.73 to 0.97 ZnO / (InO _1.5 + ZnO + SbO _2.5 ) = 0.02 to 0.18 SbO _2.5 / (InO _1.5 + ZnO + SbO _2.5 ) = 0.01 to 0.09 In In ₂ O ₃ -ZnO-Sb ₂ O _5- based ceramic target characterized by the phosphorus composition, An In ₂ O ₃ —ZnO—Sb ₂ O ₅ based ceramics target, wherein the ratio of the Zn cation and the Sb cation is added to the indium cation in the same ratio of 2: 1. In the method for forming an In ₂ O ₃ -ZnO-Sb ₂ O ₅ -based ceramic target by simultaneously adding a Zn cation and an Sb cation instead of an In cation, after ZnSb ₂ O ₆ is synthesized without volatilization of the Sb cation, ZnO And adding together and simultaneously adding a Zn cation and a Sb cation in a ratio of 2: 1. A method of manufacturing an In ₂ O ₃ -ZnO-Sb ₂ O ₅ based ceramic target.

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