JP2000169220A - Metal oxide sintered compact and its use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flat thin film having not domain structure and excellent in etching characteristics even when ITO thin film used for transparent electrodes, etc., of flat panel displays is formed at a substrate temperature not lower than crystallization temperature. SOLUTION: This metal oxide sintered compact comprises In, Sn, Al and O and has Al content (atom ratio) satisfying the formula Al/ (In+Sn+Al)>=0.1 and <2.0. A deposition material is obtained by using the metal oxide sintered compact. A sputtering target is obtained by using the metal oxide sintered compact. A transparent electroconductive film for equipment of flat panel display, touch panel, etc., comprising In, Sn and Al and having an Al content (atomic ratio) satisfying the formula Al/ (In+Sn+Al)>=1.0 and <2.0 is formed by using the sputtering target.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a conductive metal oxide sintered body, a target, a thin film, and uses thereof.

[0002]

2. Description of the Related Art ITO (Indium Tin Oxi)
de) The thin film has characteristics such as high conductivity and high transmittance,
Furthermore, since fine processing can be easily performed, display electrodes for flat panel displays, resistive touch panels,
Window materials for solar cells, antistatic films, electromagnetic wave prevention films, antifogging films,
It is used in a wide range of fields such as sensors. The method for producing such an ITO thin film is spray pyrolysis, CV
The method can be broadly classified into a chemical film formation method such as a D method and a physical film formation method such as an electron beam evaporation method, an ion plating method, and a sputtering method. Among these, the physical film formation method
Since it is a film forming method that can easily form a film on a large area and obtain a high-performance film, it is used in various fields.

[0003] When an ITO thin film is manufactured by a physical film-forming method, the raw materials to be used (a sputtering target in the case of a sputtering method, and a deposition material in the case of a vacuum evaporation method and an ion plating method) are made of metal indium and metal tin. Alloy (IT alloy) or a composite oxide composed of indium oxide and tin oxide is used. Among these, the method using the ITO composite oxide is IT
Compared to the method using an alloy, the resistance value and the transmittance of the obtained film have little change with time and the control of the film forming condition is easy, so that it is the mainstream of the ITO thin film manufacturing method.

When an ITO thin film is formed at room temperature, an amorphous film can be obtained except for special conditions. However, in consideration of heat resistance resistance stability and weather resistance, it is preferable to crystallize a thin film. The crystallization temperature of ITO is 150 ° C., and it is necessary to form a film at a film formation temperature higher than this temperature in order to obtain a crystallized film. However, after a film forming process using plasma such as sputtering or ion plating, crystalline ITO
When a thin film is formed, a domain structure characteristic of the ITO thin film is formed. The domain structure is a structure in which crystal grains of 10 to 30 nm with well-aligned crystal orientations as shown in FIG. 1 are gathered to form a crystal grain region of 200 to 300 nm. This domain structure is a collection of small grains having different crystal orientations, and is mainly composed of (1
11), (110) or (100).
Further, it has a feature that the resistance to plasma damage varies depending on the orientation plane. For this reason, the sputtering speed when the formed film is re-sputtered by plasma during the film formation differs. As a result, as shown in FIG. 2, a thin film having a thick surface on the (100) plane and a thin surface on the (110) plane is formed.

On the other hand, in the field of thin-film displays, in which ITO thin films are often used, especially in the field of liquid crystal displays, screens are becoming larger and finer at a rapid pace. Therefore, as a demand for a transparent conductive film, a film having a large area, low resistance, and easy microfabrication is required.

However, when a film is formed at a high substrate temperature by using a sputtering method capable of forming a uniform film over a large area, a film having a severe surface irregularity as described above is formed, and etching residues are easily generated. That is, there has been a problem that a thin film unsuitable for fine processing is formed.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an IT device used for a transparent electrode or the like of a flat panel display.
Even when an O thin film is formed at a substrate temperature higher than the crystallization temperature, it is an object to provide a flat thin film having no domain structure and excellent in etching characteristics.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on a conductive metal oxide obtained by doping ITO with a different element, and as a result, have found that the above problems can be solved in an ITO thin film containing aluminum as a dopant. We have found and completed the present invention.

That is, the present invention provides a method for producing substantially indium,
A metal oxide sintered body comprising tin, aluminum and oxygen, wherein aluminum is contained at a ratio of 0.1% or more and less than 2.0% in an atomic ratio of Al / (In + Sn + Al); Evaporation material using sintered body,
A sputtering target using the sintered body, substantially consisting of indium, tin, aluminum and oxygen, wherein aluminum is contained in an atomic ratio of Al / (In + Sn + Al) of 0.1% or more and less than 2.0%. The present invention relates to a transparent conductive film and a device comprising the transparent conductive film.

Hereinafter, the present invention will be described in detail.

The sintered body according to the present invention, a sputtering target made of the sintered body, a vapor deposition material, a thin film, and a device containing the thin film are manufactured by the following method.

First, powders are mixed. Indium oxide powder, tin oxide powder, and aluminum oxide powder may be mixed, or tin oxide solid solution indium oxide powder and aluminum oxide powder may be mixed. Here, the mixing amount of tin oxide is 1.9 in the atomic ratio of Sn / (Sn + In).
It is preferably set to １４14%. More preferably, 4 to
11%. This is achieved by using the target of the present invention.
This is because when the TO thin film is manufactured, the composition has the lowest resistivity of the film.

The mixing amount of aluminum oxide is Al
1. At least 0.1% by atomic ratio of / (In + Sn + Al);
Less than 0%. If the addition amount of aluminum oxide is less than the above range, the effect of the present invention is weakened, the obtained thin film shows a domain structure, and if it exceeds the above range, not only is it not appropriate because the resistivity becomes too high, When performing lithography, there is a problem that a thin film is peeled off when an alkaline developer is used. The mixing of the powder may be performed by dry mixing or wet mixing using a ball mill or the like.

Next, an ITO sintered body containing aluminum oxide is prepared using the obtained mixed powder. The method for producing the sintered body is not particularly limited, but it can be produced, for example, by the following method.

A binder or the like is added to the mixed powder of indium oxide, tin oxide and aluminum oxide obtained as described above, and the mixture is molded by a molding method such as a press method or a casting method to produce a molded body. When manufacturing a molded body by the press method, after filling the solid solution powder in a predetermined mold,
Pressing is performed using a powder press at a pressure of 100 to 300 kg / cm ² . If the powder has poor moldability, a binder such as paraffin or polyvinyl alcohol may be added as necessary.

When a molded body is manufactured by the casting method,
A binder, a dispersant, and ion-exchanged water are added to the TO mixed powder and mixed by a ball mill or the like to prepare a slurry for producing a cast molded body. Subsequently, casting is performed using the obtained slurry. It is preferable to defoam the slurry before pouring the slurry into the mold. For defoaming, for example, a polyalkylene glycol-based defoaming agent may be added to the slurry to perform defoaming treatment in a vacuum. Subsequently, a drying process of the cast molded body is performed.

Next, if necessary, a consolidation treatment such as a cold isostatic press (CIP) is performed on the obtained molded body. At this time, the CIP pressure is 2 ton / c to obtain a sufficient consolidation effect.
m ² or more, preferably ^{2 to 5} ton / cm ² . When the initial molding is performed by a casting method, a binder removal treatment may be performed for the purpose of removing water and organic substances such as a binder remaining in the molded body after the CIP. Also, even when the initial molding is performed by the press method, when a binder is used during molding,
It is desirable to perform the same binder removal treatment.

The compact thus obtained is put into a sintering furnace and sintered. As the sintering method, any method can be applied, but sintering in the air is desirable in consideration of the cost of production equipment and the like. However, it goes without saying that other conventionally known sintering methods such as a hot press (HP) method, a hot isostatic pressing (HIP) method and an oxygen pressure sintering method can be used. The sintering conditions can be appropriately selected, but the sintering temperature is desirably 1450 to 1650 ° C. in order to obtain a sufficient density increasing effect and to suppress the evaporation of tin oxide. The atmosphere during sintering is preferably air or a pure oxygen atmosphere. Also, the sintering time is 5 hours or more, preferably 5 to 30 in order to obtain a sufficient density increasing effect.
Desirably time. Thus, the aluminum-containing ITO sintered body according to the first invention of the present application can be manufactured.

Next, the obtained sintered body is processed into a desired shape to produce the aluminum-containing ITO vapor deposition material according to the second aspect of the present invention. In addition, the aluminum-containing ITO sintered body processed into a desired shape is bonded to a backing plate made of oxygen-free copper using an indium half as needed, so that the aluminum-containing ITO sintered body according to the third aspect of the present invention is obtained. An ITO sputtering target is produced.

The aluminum-containing I according to claim 4 of the present invention is applied on a substrate such as a glass substrate or a film substrate by using the obtained vapor deposition material or sputtering target.
A TO thin film can be obtained. The film forming means is not particularly limited, and the dc sputtering method, the rf sputtering method, d
A sputtering method in which rf is superimposed on c, a vacuum evaporation method (ion plating), and the like can be given.

Further, a vapor deposition material or a sputtering target prepared as three kinds of indium oxide, tin oxide and aluminum oxide, or two kinds of mixed oxides of the above three kinds and the remaining oxides is used. The film may be formed by co-evaporation or multi-source simultaneous sputtering. Further, a part or all of the individual evaporation sources or sputtering targets may be replaced with metals or alloys.

The thin film formed on the substrate is etched into a desired pattern if necessary, and then the flat panel display, the touch panel, the window material for a solar cell, the antistatic film, It can be used for devices such as an anti-fogging film, anti-fogging film, and sensor.

[0023]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 450 g of indium oxide powder, 50 g of tin oxide powder and 0.25 g of aluminum oxide powder were placed in a polyethylene pot and mixed for 72 hours by a dry ball mill.
A mixed powder was prepared.

This powder is placed in a mold and is weighed at 300 kg / cm.
Pressing was performed at a pressure of ² to obtain a molded body. 3t of this compact
Densification treatment by CIP was performed at a pressure of on / cm ² . Next, this compact was placed in a pure oxygen atmosphere sintering furnace and sintered under the following conditions. (Sintering conditions) Sintering temperature: 1500 ° C., heating rate: 25 ° C./Hr, sintering time: 6 hours, oxygen pressure: 50 mmH ₂ O (gauge pressure),
Oxygen linear velocity: 2.7 cm / min When the density of the obtained sintered body was measured by the Archimedes method, it was 7.12 g / cm ³ . The composition analysis of this sintered body was performed by EPMA (Electron Probe Mi).
cro Analysis). Table 1 shows the results.

This sintered body was processed into a sintered body having a diameter of 4 inches and a thickness of 6 mm by a wet processing method, and was bonded to a backing plate made of oxygen-free copper using indium solder to obtain a target.

This target was sputtered under the following sputtering conditions to evaluate the thin film. (Sputtering conditions) DC power: 200 W, gas pressure: 5.0 mTorr, Ar
Gas flow rate: 50 SCCM, O ₂ gas flow rate: 0.1 SCC
M, substrate temperature: 200 ° C., film thickness: 3000 A.

The resistivity of the obtained film is 200 μΩ · cm
The transmittance at 550 nm was 86.7%.
The transmittance was measured as a transmittance including a glass substrate using air as a reference. Cor on the glass substrate
# 7059 manufactured by Ning Co. was used.

Next, the surface of the obtained thin film was subjected to SEM (Sc
Anning ElectronMicroscope
Observed using e). The results are shown in the photograph of FIG. No domain structure was observed.

Next, the composition of the film was examined using EPMA. Table 2 shows the results.

Next, the etching characteristics were examined. Using hydrochloric acid as an etchant, patterning was performed on a line and space of 5 μm × 5 μm. As shown in the SEM photograph of FIG. 4, no etching residue was generated. Example 2 450 g of indium oxide powder, 50 g of tin oxide powder and 3.5 g of aluminum oxide powder were put into a polyethylene pot and mixed by a dry ball mill for 72 hours to prepare a mixed powder.

This powder is placed in a mold and is weighed at 300 kg / cm.
Pressing was performed at a pressure of ² to obtain a molded body. 3t of this compact
Densification treatment by CIP was performed at a pressure of on / cm ² . Next, this compact was placed in a pure oxygen atmosphere sintering furnace and sintered under the same conditions as in Example 1.

When the density of the obtained sintered body was measured by the Archimedes method, it was 7.11 g / cm ³ . The composition of this sintered body was analyzed using EPMA. Table 1 shows the results.

The sintered body was processed into a sintered body having a diameter of 4 inches and a thickness of 6 mm by a wet processing method, and was bonded to a backing plate made of oxygen-free copper using indium solder to obtain a target.

This target was sputtered under the following sputtering conditions to evaluate the thin film. (Sputtering conditions) DC power: 200 W, gas pressure: 5.0 mTorr, Ar
Gas flow rate: 50 SCCM, O ₂ gas flow rate: 0.1 SCC
M, substrate temperature: 200 ° C., film thickness: 3000 A.

The resistivity of the obtained film is 480 μΩ · cm
The transmittance at 550 nm was 86.2%.
The measurement conditions of the transmittance were the same as those in Example 1.

Next, the surface of the obtained thin film was observed using an SEM. The results are shown in the photograph of FIG. No domain structure was observed.

Next, the composition of the film was examined using EPMA. Table 2 shows the results.

Next, an etching test was performed under the same conditions as in Example 1. As shown in the SEM photograph of FIG. 6, no etching residue was generated.

Comparative Example 1 450 g of indium oxide powder and 50 g of tin oxide powder
Was placed in a polyethylene pot and mixed for 72 hours by a dry ball mill to prepare a mixed powder.

This powder was put in a mold and was weighed at 300 kg / cm.
Pressing was performed at a pressure of ² to obtain a molded body. 3t of this compact
Densification treatment by CIP was performed at a pressure of on / cm ² . Next, this compact was placed in a pure oxygen atmosphere sintering furnace and sintered under the same conditions as in Example 1.

When the density of the obtained sintered body was measured by the Archimedes method, it was 7.12 g / cm ³ . The composition of this sintered body was analyzed using EPMA. Table 1 shows the results.

This sintered body was processed into a sintered body having a diameter of 4 inches and a thickness of 6 mm by a wet processing method, and was bonded to a backing plate made of oxygen-free copper using indium solder to obtain a target.

The thin film was evaluated by sputtering this target under the following sputtering conditions. (Sputtering conditions) DC power: 200 W, gas pressure: 5.0 mTorr, Ar
Gas flow rate: 50 SCCM, O ₂ gas flow rate: 0.1 SCC
M, substrate temperature: 200 ° C., film thickness: 3000 A.

The resistivity of the obtained film is 200 μΩ · cm
The transmittance at 550 nm was 86.7%.
The measurement conditions of the transmittance were the same as those in Example 1.

Next, the surface of the obtained thin film was observed using an SEM. The results are shown in the photograph of FIG. A domain structure was observed.

Next, the composition of the film was examined using EPMA. Table 2 shows the results.

Next, an etching test was performed under the same conditions as in Example 1. As shown in the SEM photograph of FIG. 8, an etching residue occurred. Comparative Example 2 450 g of indium oxide powder, 50 g of tin oxide powder and 6.0 g of aluminum oxide powder were placed in a polyethylene pot and mixed by a dry ball mill for 72 hours to prepare a mixed powder.

This powder is placed in a mold and is weighed at 300 kg / cm.
Pressing was performed at a pressure of ² to obtain a molded body. 3t of this compact
Densification treatment by CIP was performed at a pressure of on / cm ² . Next, this compact was placed in a pure oxygen atmosphere sintering furnace and sintered under the same conditions as in Example 1.

The density of the obtained sintered body was measured by the Archimedes method and found to be 7.10 g / cm ³ . The composition of this sintered body was analyzed using EPMA. Table 1 shows the results.

The sintered body was processed into a sintered body having a diameter of 4 inches and a thickness of 6 mm by a wet processing method, and was bonded to a backing plate made of oxygen-free copper using indium solder to obtain a target.

The thin film was evaluated by sputtering this target under the following sputtering conditions. (Sputtering conditions) DC power: 200 W, gas pressure: 5.0 mTorr, Ar
Gas flow rate: 50 SCCM, O ₂ gas flow rate: 0.1 SCC
M, substrate temperature: 200 ° C., film thickness: 3000 A.

The etching test of the obtained thin film was conducted in Example 1.
The same conditions were used. However, when the film was developed using alkali-based development, the film was completely dissolved and etching could not be performed.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

The aluminum oxide-containing ITO thin film of the present invention can be obtained as a flat film without having a domain structure peculiar to the ITO thin film, so that a thin film which is hard to generate etching residue and which is excellent in fine processing can be obtained. .

[Brief description of the drawings]

FIG. 1 is a diagram showing a domain structure of a conventional ITO thin film.

FIG. 2 is a view showing the surface of a conventional ITO thin film.

FIG. 3 is a view showing the surface of a thin film obtained in Example 1.

FIG. 4 is a diagram showing an etching result obtained in Example 1.

FIG. 5 is a view showing the surface of a thin film obtained in Example 2.

FIG. 6 is a diagram showing an etching result obtained in Example 2.

FIG. 7 is a view showing a surface of a thin film obtained in Comparative Example 1.

FIG. 8 is a diagram showing an etching result obtained in Comparative Example 1.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazumasa Nakamura 2-2-1 Minatomirai, Nishi-ku, Yokohama-shi, Kanagawa Prefecture Inside (72) Inventor Hideyuki Shinoda 2-2-1 Geomatek Minatomirai, Nishi-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Kentaro Utsumi 5-7-8 Chuo-Rinkan, Yamato City, Kanagawa Prefecture (72) Inventor Yuichi Nagasaki 5-21-33, Rokukakubashi, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Tsutomu Takahata, Kanagawa Prefecture 1-4-5 Akanedai, Aoba-ku, Yokohama-shi F term (reference) 4G030 AA34 AA36 AA39 BA02 BA15 GA22 4K029 AA08 BA50 BC09 CA05 DA08 DC05 DC09 DC24 5G307 FA01 FB01 FC10

Claims (5)

[Claims] 2. The method according to claim 1, wherein the aluminum substantially consists of indium, tin, aluminum and oxygen.
A metal oxide sintered body characterized by being contained in an atomic ratio of (Sn + Al) of 0.1% or more and less than 2.0%. 2. The method according to claim 2, wherein the aluminum is substantially composed of indium, tin, aluminum and oxygen, and the aluminum is Al / (In + S
A vapor deposition material using a metal oxide sintered body, which is contained in a ratio of 0.1% or more and less than 2.0% in an atomic ratio of (n + Al). 3. The method according to claim 1, wherein the aluminum is substantially composed of indium, tin, aluminum and oxygen, wherein the aluminum is Al / (In + S
A sputtering target using a metal oxide sintered body, which is contained at a ratio of 0.1% or more and less than 2.0% in an atomic ratio of (n + Al). 4. Substantially consisting of indium, tin, aluminum and oxygen, wherein the aluminum is Al / (In +
A transparent conductive film, which is contained in an atomic ratio of (Sn + Al) of 0.1% or more and less than 2.0%. 5. An apparatus comprising the transparent conductive film according to claim 4.