JPH0517201A - Ito sintered body and production thereof - Google Patents

Abstract

PURPOSE:To effectively suppress abnormal discharge phenomenon by sintering a pulverized and press molded raw material containing In oxide and Sn oxide to become a specific relative density under oxidizing atmosphere after impact compression processing. CONSTITUTION:>=20% of a raw material powder mixture obtained by mixing In2O3 and SnO2 powder is put into a cylindrical container and is pulverized to obtain a powdery material after impact compression processing of 500-10GPa with detonation shock wave by explosive or shock wave by collision of a high speed flying body. Next, after the powdery material is mixed again with the residual raw material powder to obtain a processed powder, which is press molded with >=1ton/cm<2> to obtain a molded body. Furthermore the molded body is sintered under O2 atmosphere at 1350-1450 deg.C to form the ITO sintered body containing In, Sn and O2 and >=80% in relative density, <=10mum in Sn aggregation diameter, <=10mum in average crystalline diameter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an indium oxide-tin oxide sintered body, that is, an ITO sintered body and a method for producing the same, which is suitable as a sputtering target material used for forming a transparent conductive film.

[0002]

2. Description of the Related Art IT consisting of indium oxide-tin oxide
A transparent conductive film obtained by sputtering an O-sintered body has attracted attention as a promising film because of its low specific resistance value. For example, targeting an ITO sintered body,
By sputtering this on a substrate heated to a high temperature of about 300 ° C. under appropriate conditions, a high-quality ITO film having good transparency and a specific resistance value of 2.0 × 10 ⁻⁴ Ω · cm or less can be obtained.

It is known that in order to obtain an ITO film having such characteristics, the relative density of the ITO sintered body must be 80% or more. Its high density IT
The O-sinter is usually substantially composed of indium, tin and oxygen, and after molding a powder having a desired composition, it is sintered in oxygen or the atmosphere at a temperature of 1500 ° C. or higher, or added. It is manufactured by raising the temperature under pressure and sintering at a temperature of 1000 ° C or less.

However, in the ITO sintered body sintered at a temperature of 1500 ° C. or higher, Sn atoms in the sintered body are agglomerated and the coarsening of the crystal grain size is promoted, so that It is known that the variation in crystal grain size is large,
It is also known that the SnO ₂ phase remains in the ITO sintered body sintered at a temperature of 1000 ° C. or lower. As a result, I
The variation of the surface resistance value of the TO sintered body becomes large.

[0005]

When the high-density ITO sintered body manufactured as described above is used as a target for sputtering, the ITO sintered body has a large variation in the surface resistance value, and therefore, during film formation. Abnormal discharge phenomenon easily occurs and the plasma state becomes unstable. As a result, it is known that stable film formation is not performed, the structure of the obtained film deteriorates, and the characteristic value of the film deteriorates. In addition, when the ITO sintered body target is used for a long time in a situation where the abnormal discharge phenomenon frequently occurs,
An altered layer is formed on the surface of the target (so-called blackening), which causes a problem that the film forming rate is reduced and the productivity is reduced.

Further, in recent years, coating of an ITO film on a color filter for a color liquid crystal display or coating of an ITO film on a plastic substrate has come to be performed from the viewpoint of weight saving of the display.
Since these color filters and plastic substrates are inferior in heat resistance, conventional high temperature sputtering cannot be performed and the substrate heating temperature is limited to 200 ° C or less.

In the above-mentioned conventional high density ITO sintered body, a film having a low specific resistance value can be obtained by sputtering by heating the substrate at a high temperature (for example, 300 ° C. or higher).
By sputtering by heating the substrate at a low temperature of 200 ° C. or lower, the specific resistance value of the ITO film obtained is 5 × 10 ⁻⁴ Ω · cm or more, and it is difficult to obtain a film having a low specific resistance value. That is, it is difficult for these ITO sintered bodies to form a good ITO film on a color filter or a plastic substrate. Therefore, the present invention provides an ITO sintered body capable of effectively suppressing an abnormal discharge phenomenon during formation of an ITO film, and capable of forming an ITO film having a low specific resistance value even under a condition of a low substrate temperature, and a manufacturing method thereof. The purpose is to provide.

[0008]

According to the present invention, it consists essentially of indium, tin and oxygen and has a relative density of 80.
% Or more of ITO sintered body, Sn aggregate diameter is 10μm
Provided is an ITO sintered body characterized by having an average crystal grain size of 10 μm or less.

ITO Sintered Body The ITO sintered body of the present invention is substantially composed of indium, tin and oxygen, and has a relative density of 80% or more. In the ITO sintered body of the present invention, it is important that the Sn aggregate diameter is 10 μm or less, preferably 5 μm or less, and the average crystal grain size is 10 μm or less. ITO
If the Sn agglomerate diameter in the sintered body exceeds 10 μm or the average crystal grain size exceeds 10 μm, the surface resistance value of the sintered body varies widely, and abnormal discharge phenomenon during sputtering easily occurs.

The ITO sintered body of the present invention can be manufactured, for example, as follows. That is, in the above ITO sintered body, 20% by weight or more of the raw material powder containing indium oxide and tin oxide is subjected to impact compression treatment and then pulverized, and the obtained powder has a residue of the raw material powder. In some cases, it can be produced by a production method comprising remixing with it, press-molding the obtained treated powder, and then sintering in an oxidizing atmosphere.

Raw Material Powder In the manufacturing method of the present invention, as the raw material powder, a mixed powder of indium oxide powder and tin oxide powder, a mixed powder of tin oxide solid solution indium oxide powder and tin oxide powder, tin oxide solid solution oxidation. A mixed powder of indium powder and indium oxide powder, or tin oxide solid solution indium oxide powder alone is used. This raw material powder is mixed and prepared to have a desired composition. The raw material powder is prepared by, for example, mixing and pulverizing using a ball mill or the like, and the mixing time is preferably 12 hours or longer, more preferably 24 hours or longer.

A molding binder such as paraffin wax or polyvinyl alcohol can be added to the raw material powder used in the present invention at the time of mixing and pulverizing. The addition amount of this binder is preferably in the range of 1 to 2% by weight.

Impact compression treatment In the present invention, the above-mentioned raw material powder is subjected to impact compression treatment. By this impact compression treatment, the constituent particles can be made finer and at the same time a microscopic strain can be formed inside the crystal. It is considered possible to improve the dispersion of

As the shock compression method, for example, a detonation shock wave caused by the explosion of explosive or a shock wave caused by the collision of a high-speed flying object is transmitted to the raw material powder and the powder is shock-compressed. As a simple method to process a large amount of powder at a time, for example, a metal cylindrical container with screw caps at the top and bottom is filled with the raw material powder, and a container filled with explosives is placed outside the container. , There is a method of detonating a detonator attached to the upper part of the container and shock-compressing the raw material powder with a shock wave accompanying the detonation of explosives.

The impact pressure should be arbitrarily selected according to the composition of the raw material powder, but is usually 500 MPa to 10 GPa, preferably 1 G in the composition range of the raw material powder according to the present invention.
Pa to 10 GPa. When the impact pressure is 100 GPa or more, it is considered that the raw material powder at the time of impact treatment becomes high temperature, sintering between powder particles occurs, and the strain in the crystal once introduced is relaxed under high temperature. Can not exert the effect of.

The object of the present invention can be achieved by subjecting 20% by weight or more, preferably 50% by weight or more of the raw material powder to impact compression treatment. If it is less than 20% by weight, an abnormal discharge phenomenon is likely to occur during sputtering, and the specific resistance value of the obtained film becomes high. The shock-compressed powder and the rest of the raw material powder are remixed to obtain a treated powder.

Molding / Sintering Step The above-mentioned treated powder is pressure-molded. Pressure molding is 1ton / cm
² or more is preferable. If the pressure is lower than 1 ton / cm ² ,
It is difficult to make the relative density of the sintered body 80% or more.
The sintering that follows the pressure molding is performed in an oxidizing atmosphere, such as oxygen or air.

According to the present invention, a sintered body having a relative density of 80% or more can be obtained even if sintering is performed at a temperature lower than 1500 ° C. Sintering temperature is 1350 ° C or higher, preferably 1400 ° C or higher,
Further, it is necessary to be less than 1500 ° C, preferably 1450 ° C or less. If the sintering temperature is less than 1350 ° C, the SnO ₂ phase remains, which is the reason why a high-quality film with low specific resistance cannot be obtained.If the sintering temperature is 1500 ° C or higher, the Sn aggregate diameter is There is an inconvenience that the number of grains increases and the coarsening of the crystal grain size is promoted. The ITO sintered body of the present invention is obtained by the above method.

[0019]

Example 1 Indium oxide powder having an average particle size of 0.2 μm was added with an average particle size of 1 μm.
m tin oxide powder was blended so that the tin composition was 7.8% by weight, 1% by weight of paraffin wax was added as a binder, mixed and pulverized for 18 hours in a wet ball mill, and dried to 30-40 μm. It granulated and obtained the raw material powder.

As shown in FIG. 1, 2.5 kg of raw material powder 1 was all enclosed in a cylindrical container (diameter 81 mm) 2 with a packing density of 56%, and an explosive container 4 filled with dynamite explosive 3 on the outside of the container. Arranged. The detonator 5 attached to the upper part of the explosive container 4 was detonated, and the raw material powder was subjected to impact compression treatment.

The treated powder thus obtained was roughly pulverized to several hundreds of μm by a disintegrator and then mixed in a wet ball mill for 24 hours to obtain 30 to 40 μm.
The powder was crushed to m ² and pressure-molded at 1 ton / cm ² to a diameter of 78 mm × 6 mm, and then sintered in an oxygen stream at 1400 ° C. for 5 hours. About the obtained sintered body, Sn by density measurement and EPMA analysis
The diameter of the aggregate of atoms was measured, and the crystal grain size was measured by SEM. The results are shown in Table 1.

Using the above sintered body as a sputtering target material, a film was formed on a substrate heated to 200 ° C. for 3 minutes by a DC magnetron sputtering method,
The film was formed to a thickness of 1000Å. The sputtering conditions were that the volume ratio of the sputtering gas was Ar: O ₂ = 99: 1, the sputtering gas pressure was 0.5 Pa, the sputtering output was 200 W, and the target-substrate distance was 60 mm.

The specific resistance value of the obtained film was measured by the four-point probe method, and the transmittance at a wavelength of 500 nm was measured. The results are shown in Table 1. Further, continuous sputtering was performed under the same sputtering conditions, and the number of abnormal discharges generated during that period was measured. The results are shown in Table 1.

Example 2 50% by weight of the same raw material powder as that used in Example 1 was subjected to impact compression treatment in the same manner as in Example 1. The obtained powder was crushed to 30 to 40 μm in the same manner as in Example 1 and then remixed with the remaining raw material powder in a ball mill. The obtained treated powder was granulated, shaped and sintered in the same manner as in Example 1. The physical properties of the obtained sintered body were measured by the same methods as in Example 1. The results are shown in Table 1.
Shown in.

Example 3 20% by weight of the same raw material powder as that used in Example 1 was subjected to impact compression treatment in the same manner as in Example 1. The obtained powder was crushed to 30 to 40 μm in the same manner as in Example 1 and then remixed with the remaining raw material powder in a ball mill. The obtained treated powder was granulated, shaped and sintered in the same manner as in Example 1. The physical properties of the obtained sintered body were measured by the same methods as in Example 1. The results are shown in Table 1.
Shown in.

Comparative Example 1 The same raw material powder as that used in Example 1 was molded and sintered in the same manner as in Example 1 except that the impact compression treatment was not performed. The physical properties of the obtained sintered body were measured by the same methods as in Example 1. The results are shown in Table 1.

Comparative Example 2 The same raw material powder as that used in Example 1 was molded in the same manner as in Example 1 except that impact compression treatment was not carried out, and sintering was performed at 1600 ° C. for 5 hours in an oxygen stream. went. The physical properties of the obtained sintered body were measured by the same methods as in Example 1. The results are shown in Table 1.

[0028]

[Table 1]

[0029]

When the ITO sintered body of the present invention is used as a sputtering target, an abnormal discharge phenomenon during sputtering can be effectively suppressed and a high quality transparent conductive film can be formed.

The ITO sintered body of the present invention can be sputtered to obtain a low resistance film having a specific resistance of 2 × 10 ⁻⁴ Ω · cm or less even at a substrate heating temperature of 200 ° C. or less. We can provide targets that can The ITO sintered body of the present invention is extremely useful for coating an ITO film on a color filter and an ITO film on a plastic substrate.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of a cylindrical impact device applicable to impact compression treatment of raw material powder in the present invention.

[Explanation of symbols]

Raw material powder 2 cylindrical container 3 dynamite gunpowder 4 explosive container 5 detonator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tamotsu Akashi             4-4-1 Omachi, Akabira-shi, Hokkaido

Claims (3)

[Claims] 1. An ITO sintered body which is substantially composed of indium, tin and oxygen and has a relative density of 80% or more has a Sn aggregate diameter of 10 μm or less and an average crystal grain diameter of 10 μm or less. Characteristic ITO sintered body. 2. 20% by weight or more of the raw material powder containing indium oxide and tin oxide is subjected to impact compression treatment and then pulverized, and the obtained powder is re-combined with residual powder of the raw material powder, if any. Mixing, pressure molding the resulting treated powder,
Then, sintering is performed in an oxidizing atmosphere.
A method for producing the ITO sintered body according to 1. 3. The method for manufacturing an ITO sintered body according to claim 2, wherein the impact compression treatment is performed by transmitting a detonation shock wave due to an explosion of explosive or a shock wave due to collision of a high-speed flying object to the treated powder. A method for producing an ITO sintered body, comprising: