JPH0315106A - Oxide sintered body and its application - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a metal oxide sintered body and its uses. More specifically, the present invention relates to transparent conductive metal oxide sintered bodies formed by sputtering, CVD, etc., thin films thereof, and uses thereof.

[Prior Art] In recent years, there has been an increasing demand for transparent conductive thin films as transparent electrodes for solar cells and display devices, and as conductive coatings for antistatic purposes. Such a transparent conductive thin film is formed by a sputtering method, a CVD method, or the like using a conductive metal oxide composition.

Conventionally, as such transparent conductive metal oxide, indium oxide (hereinafter referred to as IT) doped with tin as a different additive element has been used.
(described as O), and tin oxide doped with antimony as a foreign additive element is mainly used. However, tin oxide doped with antimony as a source of foreign doping generally has a high resistance (specific resistance: about Low Ω・am), and I
Even with TO, a specific resistance of only about 0.2 mΩ◆cm can be achieved. Under these circumstances, transparent conductive film materials with lower resistance are eagerly desired.

Up until now, tin has been most commonly used as a dopant for indium oxide, but in addition to tin, there are also molybdenum, tungsten, titanium (Japanese Unexamined Patent Publication No. 59-204625), zinc,
Cerium, cobalt, nickel (JP-A-60-2205
05), thorium (Japanese Patent Publication No. 59-198602), ruthenium, lead, copper (Japanese Patent Application Publication No. 59-183707). boron,
Arsenic, antimony, bismuth (JP-A-59-90307
0), silicon, germanium (JP-A-82-2024
15), 7luminium, gallium (JP-A-62-845
67), halogen element (JP-A-62-142774)
, tellurium (Japanese Unexamined Patent Publication No. 63-178414), etc. are being considered. However, the electrical conductivity obtained using either dopant was not necessarily sufficient.

[Means for Solving the Problems] As a result of intensive studies on conductive metal oxides in which indium oxide is doped with different additive elements, the present inventors have found that tantalum and/or tantalum oxide is contained as part or all of the dopant. The present invention was completed by discovering that indium oxide can be used to form a transparent conductive film with extremely low resistance.

When the conductivity is improved by doping indium oxide with a different additive element, the conductivity is defined by the electron density and electron mobility in the indium oxide. When indium oxide is doped with a different additive element, the electron density increases and the conductivity improves, but if the dopant content increases more than necessary, the conductivity decreases again by suppressing electron mobility. .

Like tin or tin oxide, tantalum or tantalum oxide not only has a great effect of improving electron density when doped with indium oxide, but also has a low decrease in electron mobility in indium oxide due to doping. Extremely excellent as a dovant.

The content of tantalum in the present invention is 1wt% to 20wt%, especially 0.5wt% in terms of tantalum oxide based on indium oxide.
A range of 1 vt% to 5 vt% is preferred. Also, when doping tantalum or tantalum oxide into indium oxide,
In addition to using these alone, using them in combination with tin or tin oxide also gives favorable results in lowering the resistance of the resulting product. On this occasion,
The content of tin and tantalum in indium oxide is lvt% to 2% in total amount as tin oxide and tantalum oxide.
A range of 0vt%, particularly 3vt% to 12vt% is preferred. If the amount is too small, there will be no effect, and if the amount is too large, the resulting product will have increased resistance, which is not preferable. Further, the ratio of tantalum oxide to tin oxide used is not particularly limited, but is preferably 3 vt % to 30 wt %. In this case as well, as described above, if the amount of tantalum oxide is too large, it will have an unfavorable effect on lowering the resistance.

Films can be formed using conventional methods such as sputtering and CVD using an indium oxide composition having such a composition, but the resulting transparent conductive film has extremely low resistance and excellent transparency. There is. As mentioned above, the conventional ITO transparent conductive film had a specific resistance limit of about 0.2 lΩ・cg+, but the transparent conductive film of the composition of the present invention can have a resistivity lower than that, especially 0.16 mΩ・cg+ or less. It is.

In addition, as mentioned above, sputtering is one of the methods for forming such a low-resistance transparent conductive film, but the sintered body of the oxide having the composition of the present invention has the above-mentioned excellent transparent conductivity. Used as a target to form a film.

A sintered body of an oxide having the composition of the present invention can be sputtered to form a transparent conductive film with extremely low resistance, but it is preferable that this sintered body has as high a density as possible. .

A high-density sintered target not only has high mechanical strength, but also is resistant to change in target composition due to sputtering, making it easy to form a low-resistance transparent conductive film with strong conductive crystal orientation. The apparent density of the sintered body of indium oxide using a different element as a dopant is approximately 7 g/cs
3, the density of a certain sintered body of the present invention is 5 g/cs' or more.

Each component constituting the present invention exists in the form of an oxide.

The indium oxide powder for preparing such a sintered body is not particularly limited as long as it satisfies the composition of the present invention;
As mentioned above, in order to obtain a high-density sintered body, it is preferable that the material be fine and highly dispersible. In addition, this powder preparation method can be applied to either a mixture of oxides of each component or a composite oxide obtained from a co-precipitated product of these components.

The sintering conditions for obtaining the sintered body of the present invention include temperatures ranging from taoo to
Sintering is carried out at 500° C. for 5 to 20 hours in air or an inert atmosphere.

[Effects of the Present Invention] A metal oxide having such a composition has extremely excellent performance, especially in terms of conductivity and conductivity, when used as a transparent conductive film.

[Examples] The present invention will be described below based on Examples, but the present invention is not limited to the Examples in any way.

Example 1 Dopant was added to indium oxide at 5vt% and 10%.
Two types of composite oxides added vt% (average particle size 0.5μ
1) was preformed (100 mm thick) and sintered at 1400°C to prepare sintered pellets.

Table 1 shows the specific resistance at the same density for each dopant composition. It can be seen from Table 1 that indium oxide containing tantalum oxide as a dopant has a lower resistance than that containing tin oxide as a dopant.

Example 2 A transparent conductive film was prepared by DC magnetron sputtering using a mixed oxide target of indium oxide, tantalum oxide, and tin oxide. When forming a transparent conductive film, the amount of different added elements in the raw material is preferably about 5 to 8 vt%, but the amount in the film obtained by sputtering tends to be lower than the amount in the raw material. In this example, a material containing 10 wt % of a foreign additive element was used. Density 5g/cs+
3. Sintered target with diameter foci (sintering temperature 140
The sputtering conditions were as follows: gas: pure argon, pressure: 0.8 Pa, input power: 4 w/c1. In addition, quartz glass is used for the substrate, and the substrate inside the film is 350mm.
heated to ℃. Approximately 3,000 transparent conductive films were prepared under these conditions. Table 2 shows the properties of the obtained transparent conductive film. When tantalum oxide was used as part or all of the dopant, a transparent conductive film with lower resistance was obtained than when indium oxide was doped with only tin oxide. Furthermore, the light transmittance of the films was all 85% or more at 550 nm, and the transparency was also superior to that of conventional films.

Table 1 Sintered body components (wt%) In203 Sn02 Ta2 0,90
l0 9055 955 95 4.5 954 95 3.5 Note) Sintered body density Sintered body specific resistance (IIΩ●C■) 2.1 1.8 0.65 0.5 0.5 1 0.45 1. 5 0.5 5±0.2g/cs 3? 2 Target component (vt%) lnz Os SnO■Ta20s 90l0 909l 9082 9073 Conductive film specific resistance (mΩ●cm) 0.2l O. t6 0.14 0.14 Note) Target density 5 ±0.2g/cm

Claims (1)

[Scope of Claims] 1) A metal oxide sintered body whose main component is indium oxide containing a tantalum component. 2) Metal oxide sintered body whose main component is indium oxide containing tantalum and tin components. 3) A sputtering target using a metal oxide sintered body whose main component is indium oxide containing a tantalum component. 4) A sputtering target using a metal oxide sintered body whose main component is indium oxide containing tantalum and tin components. 5) A transparent conductive film made of a metal oxide whose main component is indium oxide containing a tantalum component. 6) A transparent conductive film made of a metal oxide whose main component is indium oxide containing tantalum and tin components.