KR20120039027A - Target for zno-based transparent conductive film and method for producing same - Google Patents

Abstract

Provided are a ZnO-based transparent conductive film target containing both boron (B) and vanadium (V) having a high sintered density, and a method of manufacturing the same. Target of the present invention, the boron _{amount, B 2 O 3 / (ZnO} + B 2 O 3 + V 2 O 3) × a as oxide equivalent to 100 0.5 to 10mass%, vanadium _{amount, V 2 O 3 / (ZnO} + B ₂ O ₃ + V ₂ O ₃ ) is a target for ZnO-based transparent conductive film, which is 0.05 to 5 mass% in terms of oxide, and the density is 90% or more of oxide sintered body in relative density, and the production method of the present invention is It is characterized by using H ₃ BO ₃ powder as the boron source and V ₂ O ₃ powder as the vanadium source. In the production method, it is preferable to sinter the calcined powder obtained by mixing the H ₃ BO ₃ powder with the ZnO powder or V ₂ O ₃ powder and calcining as a sintering raw material.

Description

TANKET-based transparent conductive film target and manufacturing method thereof {TARGET FOR ZnO-BASED TRANSPARENT CONDUCTIVE FILM AND METHOD FOR PRODUCING SAME}

This invention relates to the target for ZnO type transparent conductive films which added both boron (B) and vanadium (V) used for manufacture of a liquid crystal display, a thin film solar cell, etc., and its manufacturing method.

Electroconductive and transparent electrodes (transparent electrodes) are used for liquid crystal displays, thin film solar cells, and the like. As a material having such a property, for example, In ₂ O ₃ -SnO ₂ (hereinafter referred to as ITO), ZnO-B ₂ O ₃ (hereinafter referred to as BZO), ZnO-Al ₂ O ₃ (hereinafter referred to as AZO) and ZnO- an oxide material, such as Ga ₂ O ₃ (hereinafter, GZO) has been known. After such a material is formed as a thin film on a liquid crystal display or a thin film solar cell by sputtering, it is patterned as an electrode and becomes a transparent electrode.

In the sputtering method, in a sputtering apparatus, the board | substrate with which a thin film is formed, and a sputtering target (henceforth a target) are arrange | positioned facing. A gas discharge is generated between them, ions generated by the gas discharge hit the surface of the target, and the atoms (particles) released by the impact are attached to the opposing substrate to form a thin film. This target is formed of the material used as a transparent electrode, and the characteristic of a transparent electrode is reflected by the characteristic of the used target.

Moreover, in general, the target is very expensive, and the ratio of the price to the manufacturing cost of the liquid crystal display or the solar cell is large. For this reason, in order to reduce the cost of a liquid crystal display or a solar cell, a target with low cost is also required. Among BZO target is manufactured by using cheap raw materials ZnO powder and B ₂ O ₃ powder, it is low cost, the prospective. In addition, BZO is promising as a transparent electrode for solar cells in comparison with ITO and AZO, which are used as transparent electrodes, and having a high transmittance of a wavelength of 1000 nm or more and sunlight can be effectively utilized. However, by sintering the ZnO powder and B ₂ O ₃ powder to obtain a BZO target, B ₂ O ₃ is due to start liquid phase is produced at about 600 ℃ the fusion, coarsening due to the B ₂ O ₃ together done The problem that a dense sintered compact is difficult to obtain due to problems such as segregation in the sintered compact or a problem of hygroscopicity or evaporation of B ₂ O ₃ has been pointed out.

In order to solve this problem, a raw material composed of a composite powder obtained by calcining a ZnO powder and a B ₂ O ₃ powder is used, or a raw material composed of a composite powder obtained by calcining a powder by hydroxide by the hollow core method is used. Are disclosed (Patent Document 1, Patent Document 2, Patent Document 3).

Thus, it is not to use a composite powder is formed in advance, since the B ₂ O ₃ coarse phase does not exist, the effective in obtaining a dense sintered body by preventing segregation.

Moreover, it is disclosed that Co and V addition are effective in improving chemical resistance of ZnO (patent document 4).

According to Patent Document 4, the addition of Co or V is effective also for a ZnO-based conductive film to which the boron-containing group III element or the like used as a donor impurity is added. The sputtering method is applied to the formation of such a conductive film. There is also a start of a sintered body.

Japanese Patent Application Laid-open No. Hei 11-158607 Japanese Patent Application Laid-open No. Hei 11-171539 Japanese Patent Application Laid-open No. Hei 11-302835 Japanese Patent Application Laid-Open No. 2002-75062

V disclosed in Patent Document 4 is advantageous in terms of improving chemical resistance, but when V ₂ O ₅ having a specific description in Patent Document 4 is used as a vanadium source, careful handling of the toxicity of V ₂ O ₅ is avoided. need.

In addition, V ₂ O ₅ of all but the toxicity of this V ₂ O ₃ is known as a low-V oxide, with respect to the melting point of the V ₂ O ₅ has a low temperature as 690 ℃, the melting point of the V ₂ O ₃ is high as 1970 ℃, boron The behavior in obtaining the ZnO system sintered compact containing this was unclear.

In addition, as for the addition of boron, the method of forming a complex oxide like patent documents 1-3 is effective. However, also in the manufacturing technique using such a composite oxide, it was unknown at all whether the valence of V which is a raw material oxide at the time of adding V had any influence on sinterability or the like.

The objective of this invention is providing the target for ZnO type transparent conductive films which added both boron (B) and vanadium (V) which have high sintering density, and its manufacturing method.

The present inventor, according to the V ₂ O ₃ to obtain a sintered body containing boron, identify and to contribute to improving the sintered density, and reached the present invention.

That is, in the present invention, the amount of boron is 0.5 to 10 mass% and the amount of vanadium in terms of oxide in which B ₂ O ₃ / (ZnO + B ₂ O ₃ + V ₂ O ₃ ) × 100 is V ₂ O ₃ / (ZnO + B _{2 O 3 + V 2 O 3} ) × 100 from 0.05 to 5mass% in oxide equivalent, and a ZnO-based transparent conductive film that is the target density of the oxide-sintered body of 90% or more in relative density.

In addition, in this invention, aluminum and / or gallium can be converted into trivalent oxide, and can add 2 mass% or less, respectively.

In addition, the production method of the present invention, containing boron and vanadium, boron amount, and _{B 2 O 3 / (ZnO +} B 2 O 3 + V 2 O 3) × 0.5 to 10mass% in the terms of oxides to 100, V volume, V ₂ O ₃ / a _{(ZnO + B 2 O 3 +} V 2 O 3) × as oxides converted to 100 0.05 to 5mass% the method of producing a target for the ZnO-based transparent electrode composed of an oxide sintered body, a boron source H ₃ BO ₃ powder, a ZnO-based transparent conductive film production method of the target using the V ₂ O ₃ powder as a vanadium source.

Moreover, it is preferable that the sintering temperature in the manufacturing method of this invention makes 700-1050 degreeC, and a sintering atmosphere into a non-reducing atmosphere.

Further, in the production method of the present invention, it is preferable to mix the powder and H ₃ BO _3, ZnO powder or V ₂ O ₃ powder is further calcined by sintering a sintering material a calcined powder obtained.

In the case of using the calcined powder in the present invention, the composition of the calcined powder is 0.8 to 45 mass% in terms of oxide in which the composition of the calcined powder is B ₂ O ₃ / (ZnO + B ₂ O ₃ + V ₂ O ₃ ) × 100. It is preferable to mix and sinter one or both of ZnO powder or V ₂ O _{3 to} the calcined powder to obtain a sintered compact having a relative density of 90% or more.

In addition, it is preferable that calcining temperature shall be 100-500 degreeC.

This invention is a target for ZnO type transparent conductive films which added both boron (B) and vanadium (V) which have high sintering density, and has little abnormal discharge, and is suitable for manufacture of a liquid crystal display, a thin film solar cell, etc. Moreover, since the manufacturing method of this invention can manufacture safely and high precision, it becomes an important technique in obtaining the target mentioned above.

1 is a diagram showing an example of a microstructure of a target of the present invention and a corresponding specific atomic distribution.
2 is a diagram showing an example of the microstructure of the target of the comparative example and the corresponding specific atomic distribution.

As described above, an important feature of the present invention is that V ₂ O ₃ was found to contribute to the improvement of sintered density in obtaining a sintered body containing boron, and both boron and vanadium having high sintered density were added. The ZnO-based transparent conductive film target is realized.

In the present invention, the amount of boron is 0.5 to 10% by mass in terms of oxide in terms of B ₂ O ₃ / (ZnO + B ₂ O ₃ + V ₂ O ₃ ) × 100, which is formed by addition of boron. It is because it is effective in ensuring the low resistance and transparency of a film | membrane. Preferably, it is 0.5-5 mass%.

In the present invention, the amount of vanadium is 0.05 mass% or more in terms of an oxide of V ₂ O ₃ / (ZnO + B ₂ O ₃ + V ₂ O ₃ ) × 100, when less than 0.05 mass%, This is because it is difficult to obtain a definite effect of improving the sinterability and to make it possible to uniformly disperse the target at the time of manufacture. In addition, the reason why it is 5 mass% or less is for maintaining the effect | action of boron addition which is inexpensive and the transmittance | permeability of a specific wavelength is high. Preferably, it is 0.05-2 mass%.

In the present invention, in order to utilize the characteristics of the boron, an oxide that imparts conductivity other than boron and vanadium is not necessarily required, but can be added. Typically, addition of oxides of aluminum (Al) or gallium (Ga) is possible. It is preferable to make these addition into 2 mass% or less in conversion as a trivalent oxide.

In addition, the relative density of the target of this invention was 90% or more. Less than 90% is because, since conventional can be easily reached in sintering, there is less of a sintering property improving means by V ₂ O ₃ addition. Preferably, you may be 95% or more. More preferably, it is 98% or more.

Further, the relative density in the present invention is to assume that the target tissue, ZnO, B ₂ O _3, each independently of the presence of the V ₂ O ₃ different from each other, the relative density of the computed density.

Next, the manufacturing method of this invention is demonstrated in detail.

In the production method of the present invention, one important feature in using the V ₂ O ₃ powder as a, H ₃ BO ₃ powder, a boron source, vanadium source to obtain a target of the above composition.

Average B ₂ O ₃ powder used as a boron source, and make the problem of easy to cause a weighing error increases the hygroscopicity. On the other hand, the H ₃ BO ₃ powder used in the present invention is a hydrate and has no fear of moisture absorption, and thus is unlikely to cause a weighing error, and is effective in increasing the accuracy of component adjustment.

In addition, V ₂ O ₅ is used as the vanadium source is normal, there is a problem for handling toxic, as described above. On the other hand, V ₂ O ₃ used in the present invention does not have such a problem. It is important to note that V ₂ O ₃ contributes to increasing the sinterability even though V ₂ O ₃ has a high melting point of 1970 ° C.

According to the examination of the present inventors, it is confirmed that the Zn-BO phase structure present in the target structure is a columnar structure by the addition of V ₂ O ₃ , whereas the V ₂ O ₃ no addition structure is a granular structure. A V ₂ O ₃ powder is added from this having a significant effect on the target tissue, it is estimated that there is a factor for improving the sinterability.

And by this method, it becomes possible to improve a relative density to 90%, Preferably it is 95% or more, More preferably, it is 98% or more.

It is preferable that the sintering temperature in the manufacturing method of this invention is 700-1050 degreeC, and sintering atmosphere shall be a non-reducing atmosphere. This is because at a sintering temperature of less than 700 ° C., the sintering time is excessively long, and at 1050 ° C. or more, decomposition of the constituent oxide proceeds, a predetermined sintered density is not obtained, and composition variation may also increase.

In addition, there is an advantage in that decomposition of the oxide to constitute can be easily suppressed by selecting the non-reducing atmosphere as the sintering atmosphere. As this non-reducing atmosphere, it is possible to use air, nitrogen, an inert gas, or the like.

In the production method of the present invention, the use of the H ₃ BO ₃ powder is effective in the composition control as described above, but when it is used as the sintering raw material, it is decomposed into boron oxide and water by heating, so that the boron oxide is sintered as it is. As in the case of a large sintered body, large segregation may occur or a dense sintered body may not be obtained.

Therefore, when a calcination powder obtained by mixing ZnO powder and H ₃ BO ₃ powder is produced and calcined as a sintering raw material, a complex oxide is formed, so segregation can be prevented and a compact sintered body can be obtained. In addition, since the calcination process can remove previously unnecessary moisture as a sintered compact, it is effective also in preventing deformation | transformation of a sintered compact and formation of a defect by moisture presence. At this time, V ₂ O ₃ powder may also be mixed at the same time to obtain calcined powder.

In addition, in the manufacturing method of this invention, you may sinter only with a calcination powder as a raw material, but you may mix and sinter another oxide powder in addition to a calcination powder. Specifically, the composition of the calcined powder was adjusted to 0.5-45 mass% in terms of an oxide having a composition of B ₂ O ₃ / (ZnO + B ₂ O ₃ + V ₂ O ₃ ) × 100, and ZnO powder or V was added to the calcined powder. ₂ mixture of one or both of the O _3, it is preferable to sinter.

The B ₂ O ₃ ratio is set to 0.5% or more because it is difficult to obtain characteristics as an electrode at less than 0.5%, and in addition to the calcined powder, it is necessary to add another boron source or the like.

On the other hand, when the B ₂ O ₃ ratio is made to be 45% or less, when it becomes higher than 45%, the amount which exists as B ₂ O ₃ phase other than being present as a complex oxide will become large, and the dispersibility of B will worsen. Because there is. The actual composition of the calcined powder is to use H ₃ BO ₃ powder can be adjusted by the amount of ZnO, V ₂ O ₃ or V ₂ O ₃ powder in the amount of the amount of ZnO powder in the case where the B ₂ O _3.

In the above calcination step, the calcination temperature is preferably set to 100 ° C or higher and 500 ° C or lower. This is a temperature lower than 100 ℃, it is difficult to decompose the water removal from the H ₃ BO ₃ in progress.

On the other hand, when the temperature is higher than 500 ° C., the calcined powder grows significantly and a special grinding treatment or the like is required as the sintered raw material.

[Example]

Hereinafter, embodiments of the present invention will be described. However, this invention is not limited to the Example described below.

The manufacturing process applied in the present Example is as follows.

(Step A1)

The ZnO powder having a specific surface area of 4.5 m 2 / g and the H ₃ BO ₃ powder were weighed so as to have a predetermined target composition shown in Table 1, and then mixed with a ball mill to prepare a mixed powder.

The obtained mixed powder was calcined at a predetermined temperature to obtain calcined powder. V ₂ O ₃ powder was weighed into the obtained calcined powder so as to have a predetermined target composition, and then mixed with a ball mill to prepare a mixed powder. 0.5 mass% of polyvinyl alcohol was added to the obtained mixed powder as a binder, and it grind | pulverized, and after mixing, granulated granulated powder was produced.

Further, if the addition of another oxide powder, and the same is added with V ₂ O _3.

(Step A2)

The ZnO powder, H ₃ BO ₃ powder, and V ₂ O ₃ powder having a specific surface area of 4.5 m 2 / g were weighed to have a predetermined target composition, and then mixed with a ball mill to prepare a mixed powder. The obtained mixed powder was calcined at a predetermined temperature to obtain calcined powder. 0.5 mass% of polyvinyl alcohol was added to the obtained calcined powder as a binder, it grind | pulverized, it mixed, and the granulated powder granulated was produced.

(Step A3)

As a comparative example, the process, after the specific surface area 4.5㎡ / g of ZnO powder and H ₃ BO ₃ powder were weighed so that a predetermined target composition, to prepare a mixed decomposition mixture by a ball mill.

The obtained mixed powder was calcined at a predetermined temperature to obtain calcined powder. 0.5 mass% of polyvinyl alcohol was added to the obtained calcined powder as a binder, it grind | pulverized, it mixed, and the granulated powder granulated was produced.

(Step B)

Next, the granulated powder obtained in any of steps A1 to A3 was molded at a pressure of 3 ton / cm 2 by cold hydrostatic press to obtain a disk-shaped molded body having a diameter of 120 mm and a thickness of 8 mm. The obtained molded object was sintered at the predetermined temperature and atmosphere shown in Table 1, and the sintered compact was produced. The obtained sintered compact was processed into the disk shape of diameter 100mm and thickness 5mm, and the target for sputtering was produced.

(Target evaluation)

The density of the sintered compact obtained at the manufacturing process was measured by the underwater substitution method, and the value divided by the theoretical density calculated on the assumption that the component which comprises a sintered compact exists as a predetermined oxide was made into the relative density. The composition analysis of the sintered body is analyzed by ZnO, B amount, V amount, Al amount and Ga amount by high frequency inductively coupled plasma emission spectroscopy (ICP-AES), and ZnO, B ₂ O ₃ , V ₂ O ₃ Was converted back into oxides of Al ₂ O ₃ and Ga ₂ O ₃ , but was consistent with the desired composition. These results are shown in Table 1.

The obtained sintered compact was observed with the scanning electron microscope, and the element distribution in a structure was mapped to EPMA. As a typical example, the microstructure and the corresponding specific atomic distribution of the target of the second example in FIG. 1 and the second comparative example are shown in FIG.

The four observation images shown in FIG. 1 and FIG. 2 respectively correspond to the B atom distribution in the structure where the upper left corresponds to the structure by the scanning microscope, the upper right corresponding to the V atom distribution in the visual field to which the lower left corresponds, and the lower right correspond to. The Zn atomic distribution in the field of view is shown. In addition, the atomic distribution shows that concentration is high in order of black-white-brown.

In the examples and comparative examples, Zn ₃ B ₂ O ₆ compounds were detected in the boron enrichment unit by X-ray diffraction analysis, and Zn ₃ (VO ₄ ) ₂ compounds were detected in the vanadium enrichment unit.

(Film formation evaluation)

The film | membrane with a film thickness of 200 nm was formed by DC magnetron sputtering method using the manufactured target. The sputtering conditions were fixed at an input power of 200 W and an Ar gas pressure of 0.7 Pa. The number of abnormal discharges generated per 10 minutes after 10 hours had elapsed from the start of the experiment, the volume resistivity of the film at the substrate temperature of 200 ° C., and the transmittance in the 1200 nm wavelength region were measured. Furthermore, the film | membrane at the substrate temperature of 200 degreeC was exposed in the environment of the temperature of 60 degreeC, and 90% of humidity, the volume resistivity after 1000 exposure time was measured, and the change of the volume resistivity after exposure with respect to the volume resistivity before exposure was evaluated. The results are shown in Table 2.

In Table 1, for example, the third embodiment and the first comparative example when the contrast, the addition of V ₂ O ₃ with respect to the same amount of B ₂ O _3, which may be the same sintering conditions, notably the relative density is increased It can be seen that. In contrast with the third example and the second comparative example, it can be seen that when V ₂ O ₃ is not added, the sintering temperature is set to a high temperature of 1000 ° C., and only an approximate sintering density is obtained. These results show that, in obtaining a ZnO-based sintered body containing boron, the addition of V ₂ O ₃ works effectively to increase the sintered density.

Note that, in Table 2, the addition of V ₂ O _3, it can be seen that there can be suppressed a change in the volume resistivity, it can be seen that the addition of the V ₂ O ₃ to improve the environmental resistance. In addition, since the transmittance of 1200 nm does not significantly deteriorate even by the addition of the predetermined V ₂ O ₃ , it is also found to be effective in that the characteristics of the ZnO-based sintered body containing boron can be maintained.

Claims (8)

The amount of boron is 0.5 to 10 mass% and the amount of vanadium in terms of oxide converted to B ₂ O ₃ / (ZnO + B ₂ O ₃ + V ₂ O ₃ ) × 100, and V ₂ O ₃ / (ZnO + B ₂ O ₃ + V ₂ O ₃₎ × 100 with a 0.05 to 5mass% in the terms of oxides, the target density of the transparent conductive film ZnO-based, characterized in that the oxide-sintered body with a relative density of 90% or more. The target for ZnO-based transparent conductive films according to claim 1, wherein aluminum and / or gallium are converted into trivalent oxides, and each contains 2% by mass or less. Containing boron and vanadium, the amount of boron is 0.5 to 10 mass% and the amount of vanadium in terms of oxide converted to B ₂ O ₃ / (ZnO + B ₂ O ₃ + V ₂ O ₃ ) × 100, and V ₂ O ₃ / (ZnO _{+ B 2 O 3 + V 2} O 3) a × 100 a method of manufacturing a target for the ZnO-based transparent electrodes made of 0.05 to an oxide sintered body 5mass% in the terms of oxides, as the boron source H ₃ BO ₃ powder, a vanadium source the use of V ₂ O ₃ powder, characterized in, the method of the target ZnO-based transparent conductive film manufacture. The method for manufacturing a target for a ZnO-based transparent conductive film according to claim 3, wherein the target for the ZnO-based transparent electrode contains 2 mass% or less in terms of aluminum and / or gallium as a trivalent oxide. The method for producing a target for a ZnO-based transparent conductive film according to claim 3 or 4, wherein the sintering temperature is 700 to 1050 ° C and the sintering atmosphere is a non-reducing atmosphere. 6. The calcined powder obtained by further mixing H ₃ BO ₃ powder and ZnO powder or V ₂ O ₃ powder and calcining is sintered as a sintering raw material according to any one of claims 3 to 5, The manufacturing method of the target for ZnO type transparent conductive films. 7. The calcined powder according to claim 6, wherein the composition of the calcined powder is 0.5 to 45 mass% in terms of an oxide having a composition of B ₂ O ₃ / (ZnO + B ₂ O ₃ + V ₂ O ₃ ) × 100. one or both of V ₂ O ₃ mixture, and sintering, the relative density, the method of the target ZnO-based transparent conductive film prepared, characterized in that to obtain more than 90% of the sintered body. The method for producing a target for a ZnO-based transparent conductive film according to claim 6 or 7, wherein the calcining temperature is set to 100 to 500 ° C.

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