JPH06239659A - Metal oxide sintered product and its production and sputtering target using the same - Google Patents

Abstract

PURPOSE:To form a transparent conductive film by subjecting the mixture of In2O3 powder with SnO2 powder to a hot-pressing treatment, a sintering treatment, and subsequently an oxidation treatment, and using the product as a target material having a specific sintered density, a specific sintered particle diameter and a prescribed refractive index to a light having a prescribed wave length. CONSTITUTION:The powder of In2O3 and the powder of SnO2 are mixed with each other in a weight ratio of 97/3 to 85/15, hot-pressed at 700-1500 deg.C under a pressure of 50-200kg/cm<2> at 700-1500 deg.C, and subsequently subjected to an oxidation treatment in a graphite mold at >=300 deg.C, preferably 600-1300 deg.C, in the atmosphere to produce the In2O3.SnO2 sintering product having a sintered density of 5.5-6.5g/cm<3>, a sintered particle diameter of >=0.1mum and a reflectance of 15-70% to a light having a wavelength of 550-700nm. The sintering product is used as a sputtering target to form a high performance transparent conductive film.

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 (hereinafter referred to as ITO) sintered body, a method for producing the same, and a use thereof. The ITO sintered body according to the present invention is
Since it has a high density and contains sufficient oxygen, it has extremely excellent performance as a sputtering target when a transparent conductive film is formed by a sputtering method.

[0002]

2. Description of the Related Art In recent years, there has been a rapid increase in demand for ITO thin films as transparent conductive thin films used for transparent electrodes of solar cells and liquid crystal displays, and touch panels. Such ITO
The thin film can be formed by applying ITO fine particles to a substrate, applying an ITO precursor to the substrate and then thermally decomposing it, or an IT alloy target or an ITO sintered body target.
A method of forming an ITO film on the surface of a base material by sputtering of a get is known, but at present, a method of sputtering an ITO sintered body is the most general method. However, since the conventional ITO sintered body target has low density, reduction and composition change occur during sputtering, and it is difficult to stably manufacture a high-performance transparent conductive film. Therefore, in order to solve such a problem, we have already proposed a high density ITO sintered body sputtering target. However, in the conventional high density ITO sintered body, a phenomenon was observed in which a small amount of oxygen defects were generated in the process of high density. On the other hand, as another high-density ITO target, a target in which oxygen defects are intentionally introduced by hot pressing has already been proposed (see US Pat. No. 4,647,548). However, the ITO sintered body target in which oxygen defects were intentionally introduced in this way was inferior in performance because there were too many oxygen defects.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a sputtering target capable of forming a high performance transparent conductive film.

[0004]

Means for Solving the Problems The inventors of the present invention have earnestly studied the sintered density and oxygen content of the ITO sintered body and the characteristics of the transparent conductive film obtained by sputtering. By oxidizing the sintered body obtained by oxidation, a high density and high oxygen content I
It was found that a TO sintered body can be obtained, and in particular oxidation treatment
It was found that an ITO sintered body having a high density, a large oxygen content, and sintered particles grown by performing the growth at a temperature of 300 ° C. or higher can be obtained. Moreover, when this ITO sintered body is used as a sputtering target, it is a target.
The present invention has been completed by finding that the get performance does not change with time, the amount of oxygen gas supplied into the sputtering apparatus may be small, and in addition, a transparent conductive film having extremely uniform and low resistance can be formed.

The present invention will be described in detail below.

[0006]

The sintered density of the ITO sintered body of the present invention is an apparent density obtained by dividing the weight by the apparent volume from 5.5 g / cm ³ to
It is 6.5 g / cm ³ . Sintered density is 5.5g / c
When it is smaller than m ³ , when this material is used for sputtering, the target surface is reduced and the composition is changed, which is not preferable. On the other hand, even if the sintered density is too high, the effect is saturated, so that up to about 6.5 g / cm ³ is sufficient.

In order to obtain an ITO sintered body having such a high sintering density and containing sufficient oxygen, the sintered particles of the sintered body before the oxidation treatment are small and the surface area of the sintered body is small. It needs to be large. To obtain such a sintered body, the raw material powder is obtained by hot pressing.
Conventionally, it is well known that in a method for obtaining a sintered body by hot pressing, sintered particles do not grow even if the sintered density of the sintered body is improved (Kingery et al., "Introduction to Ceramics Material Science", Basic Edition). p484).

One of the preferred embodiments of the present invention is to sinter the raw material powder by hot pressing. The hot pressing pressure at this time is 50 kg / cm ^{2 to} 200 k.
g / cm ² , especially 80 kg / cm ^{2 to} 150 kg / cm ²
Is preferred. The heating temperature is 700 ° C
It is preferable to heat at 1500 ° C., particularly about 900 ° C. to 1100 ° C. If the heating temperature is too low, it will take a long time for sintering, and if it is too high, grain growth will occur, and it will be difficult to mix oxygen into the sintered body even after the oxidation treatment. The pressing die used is generally a graphite mold, but is not limited to this. Also, the processing time of hot pressing is 10 minutes or more, especially 25 minutes to 60 minutes.
The range of minutes is preferred.

The composition of the raw material powder used in the present invention is preferably 97/3 to 85/15, and more preferably about 95/5 to 90/10 by weight ratio of indium oxide / tin oxide. The ITO powder having such a composition may be a mixed powder of indium oxide and tin oxide, or a powder obtained by thermally decomposing an organic acid salt of an organic acid aqueous solution of indium and / or tin (JP-A-63-63). -195101 specification) and the like.

By hot pressing under the above conditions, the sintered density is 5.5 g / cm ^{3 to} 6.5 g / cm ^3.
It is possible to obtain a high-density ITO sintered body having a sintered particle size of 1 μm or less, a large amount of oxygen defects, and a blue to black color with a high density in the range. The present invention is obtained by further oxidizing such an ITO sintered body.

The oxidation treatment of the present invention can be carried out by heating in an oxygen-containing atmosphere such as air. In the atmosphere containing no oxygen, no change in the color tone of the sintered body is recognized.
The heating temperature here can be 300 ° C. or higher, particularly 600 ° C. or higher, but at a temperature lower than 1300 ° C., a sintered body having sintered particles of 0.1 μm to 2 μm can be obtained. If the sintered particle diameter is smaller than this range, the surface area of the particle is large, and when a sputtering target composed of such a sintered particle diameter is used for sputtering, the surface becomes black due to reduction, which is not preferable. On the other hand, 1300 ° C or higher, especially 1
When the oxidation treatment is performed at 400 ° C. or higher, the sintered particles become a high-density sintered body with grain growth. When grains are grown in this way,
Sputtering characteristics become more preferable. However, 14
When heated at 50 ° C. or higher, tin in the sintered body is sublimated and a large particle size is obtained, but compositional deviation occurs, which is not preferable. In the present invention, the particle size is at most about 10 μm. In addition, although there is no particular limitation on the temperature rising rate and the temperature lowering rate in such a heat treatment, it is not preferable that the sintered body is cracked under the condition that the temperature changes abruptly.

High density IT produced by sintering in air without using a hot press as used in the present invention.
In the O sintered body, densification and grain growth proceed simultaneously, it is difficult to control the oxygen content, the color tone of the sintered body becomes blue or black, and some oxygen defects tend to occur in the sintered body. was there. On the other hand, according to the method of the present invention, even if a sintered body densified by hot pressing is manufactured, and then an oxygen treatment is performed to grow grains, oxygen defects do not increase, and a high density sintered body that remains yellow green is obtained. Is obtained.

As a method of evaluating the oxygen / indium composition ratio of such an ITO sintered body, ESCA (XPS), A
ES (Auger electron spectroscopy) or the like is applicable. It is clearly judged that the oxygen content increases after the oxidation treatment of the present invention by these measuring methods, but these values are relative values, and it is difficult to quantitatively show the oxygen content. Is.

However, as described above, since the ITO sintered body undergoes a color tone change due to the oxidation treatment, the oxygen content can be indirectly quantitatively measured by the light reflectance.

The sintered body after hot pressing is black or blue, but becomes yellowish green as the oxygen content in the sintered body is increased by oxidation treatment. The sintered body according to the present invention is oxidized to have a reflectance of light of 500 to 700 nm of 15
It is in the range of up to 70%. On the other hand, depending on the manufacturing method, the surface is yellowish green, and the inside of the sintered body is black or blue, and the reflectance is in the range of 15 to 70%. Not included in the present invention.
The light reflectance in the range of 15 to 70% referred to in the present invention means that all the portions including both the surface and the inside of the sintered body satisfy this condition.

This method of measuring oxygen content depends on the amount of adsorbed oxygen on the surface and other measurement conditions.
(XPS), AES (Auger electron spectroscopy), etc.
The measurement error is small, and the oxygen content can be measured easily and quantitatively.

The sample used at the time of measurement was I whose surface was polished.
The surface or fracture surface of the TO sintered body can be measured with a generally commercially available reflection spectrum measuring device.

By performing the above-mentioned oxidation treatment, an ITO sintered body having a high density and a high oxygen content can be obtained.

[0019]

EXAMPLES The present invention will be described below based on examples, but the present invention is not limited to the examples.

Example 1 Mixed powder of indium oxide and tin oxide (weight ratio 90/1
0) was hot-pressed at 1000 ° C. and 100 kg / cm ² for 30 minutes to obtain a blue ITO sintered body having a sintering density of 5.7 g / cm ³ and containing many oxygen defects. The average of the sintered particles by SEM observation is 0.7 μm or less, and
The reflectance of nm light was 12% or less.

This ITO sintered body was heated to 1000 ° C. in the atmosphere to be oxidized. The temperature rising / falling rate at this time is 100
C./hour and held at 1000.degree. C. for 2 hours. By such an oxidation treatment, the average particle size of the sintered particles is 0.5 μm
Thus, an ITO sintered body having a sintered density of 5.7 g / cm ³ and a reflectance of light of 500 to 700 nm of 20% or more was obtained.

Example 2 Mixed powder of indium oxide and tin oxide (weight ratio 90/1
0) was hot-pressed at 1000 ° C. and 100 kg / cm ² for 30 minutes to obtain a blue ITO sintered body having a sintering density of 5.7 g / cm ³ and containing many oxygen defects. The average of the sintered particles by SEM observation is 0.8 μm or less, and the average particle size is 500 to 700.
The reflectance of nm light was 13% or less. This ITO sintered body was heated at 1400 ° C. in the atmosphere to be oxidized. The temperature rising / falling rate was 100 ° C./hour, and the temperature was maintained at 1400 ° C. for 2 hours. By such an oxidation treatment, the average particle size of the sintered particles is about 5 μm, and the sintered density is 6.0 g / cm ³ ,
The reflectance of light of 500 to 700 nm is 20% or more I
A TO sintered body was obtained.

Example 3 Mixed powder of indium oxide and tin oxide (weight ratio 90/1
0) was hot-pressed at 1000 ° C. and 100 kg / cm ² for 30 minutes to obtain a blue ITO sintered body having a sintering density of 5.7 g / cm ³ and containing many oxygen defects. The average of the sintered particles by SEM observation is 0.8 μm or less, and the average particle size is 500 to 700.
The reflectance of nm light was 13% or less.

Such an ITO sintered body was heated to 700 ° C. in the atmosphere.
It was heated to and oxidized. Temperature rising / falling rate is 100 ° C /
The temperature was kept at 700 ° C. for 2 hours. By such an oxidation treatment, an ITO sintered body having an average sintered particle size of 0.5 μm, a sintered density of 5.7 g / cm ³ , and a reflectance of light of 500 to 700 nm of 20% or more is obtained. It was

Example 4 Mixed powder of indium oxide and tin oxide (weight ratio 90/1
0) was hot-pressed at 1000 ° C. and 100 kg / cm ² for 30 minutes to obtain a blue ITO sintered body having a sintering density of 5.7 g / cm ³ and containing many oxygen defects. The average of the sintered particles by SEM observation is 0.8 μm or less, and the average particle size is 500 to 700.
The reflectance of nm light was 13% or less.

Such an ITO sintered body was placed in the atmosphere at 800 ° C.
It was heated to and oxidized. Temperature rising / falling rate is 100 ° C /
The temperature was kept at 800 ° C. for 2 hours. By such an oxidation treatment, an ITO sintered body having an average sintered particle size of 0.5 μm, a sintered density of 5.7 g / cm ³ , and a reflectance of light of 500 to 700 nm of 20% or more is obtained. It was

Example 5 Mixed powder of indium oxide and tin oxide (weight ratio 90/1
0) was hot-pressed at 1000 ° C. and 100 kg / cm ² for 30 minutes to obtain a blue ITO sintered body having a sintering density of 5.7 g / cm ³ and containing many oxygen defects. The average of the sintered particles by SEM observation is 0.8 μm or less, and the average particle size is 500 to 700.
The reflectance of nm light was 13% or less.

Such an ITO sintered body was placed in the atmosphere for 1100
Oxidation treatment was performed by heating to ℃. Temperature rising / falling rate is 100 ℃
/ Hour and held at 1100 ° C. for 2 hours. By performing such an oxidation treatment, the average particle size of the sintered particles is about 0.7 μm, the sintered density is 5.7 g / cm ³ , and 500 to 700 nm.
An ITO sintered body having a light reflectance of 20% or more was obtained.

Example 6 Mixed powder of indium oxide and tin oxide (weight ratio 90/1
0) was hot-pressed at 1000 ° C. and 100 kg / cm ² for 30 minutes to obtain a blue ITO sintered body having a sintering density of 5.7 g / cm ³ and containing many oxygen defects. The average of the sintered particles by SEM observation is 0.8 μm or less, and the average particle size is 500 to 700.
The reflectance of nm light was 12% or less.

Such an ITO sintered body was placed in air at 1200
Oxidation treatment was performed by heating to ℃. Temperature rising / falling rate is 100 ℃
/ Hour and held at 1200 ° C. for 2 hours. By performing such an oxidation treatment, an ITO sintered body having an average sintered particle size of about 2 μm, a sintered density of 5.8 g / cm ³ , and a reflectance of light of 500 to 700 nm of 20% or more was obtained. .

Example 7 Mixed powder of indium oxide and tin oxide (weight ratio 90/1
0) was hot-pressed at 1000 ° C. and 100 kg / cm ² for 30 minutes to obtain a blue ITO sintered body having a sintering density of 5.7 g / cm ³ and containing many oxygen defects. The average of the sintered particles by SEM observation is 0.8 μm or less, and the average particle size is 500 to 700.
The reflectance of nm light was 12% or less.

Such an ITO sintered body was placed in the atmosphere for 1300
Oxidation treatment was performed by heating to ℃. Temperature rising / falling rate is 100 ℃
/ Hour and held at 1300 ° C. for 2 hours. By performing such an oxidation treatment, an ITO sintered body having an average sintered particle size of about 3 μm, a sintered density of 5.9 g / cm ³ , and a reflectance of light of 500 to 700 nm of 20% or more was obtained. .

Example 8 Using the ITO sintered body obtained in Example 1 as a target, a transparent conductive film was prepared by DC magnetron sputtering. The sputtering condition is a pressure of 0.6
Pa, Ar / O ₂ = 99/1, input power 4 w / cm ² , target-substrate distance = 3 cm. Substrate temperature 300
The specific resistance of the transparent conductive film obtained at ℃ is 1.8 × 10 ^-4 Ω
cm, average visible light transmittance of 80% or more, substrate temperature 2
At 00 ° C., an excellent transparent conductive film having a viscosity of 2.7 × 10 ⁻⁴ Ω · cm and an average visible light transmittance of 80% or more was obtained.

Example 9 Using the ITO sintered body obtained in Example 2 as a target, a transparent conductive film was prepared by DC magnetron sputtering. The sputtering condition is a pressure of 0.6
Pa, Ar / O ₂ = 99/1, input power 4 w / cm ² , target-substrate distance = 3 cm. Substrate temperature 300
The specific resistance of the transparent conductive film obtained at ℃ is 1.5 × 10 ^-4 Ω
cm, average visible light transmittance of 80% or more, substrate temperature 2
At 00 ° C., an excellent transparent conductive film having a density of 2.5 × 10 ⁻⁴ Ω · cm and an average visible light transmittance of 80% or more was obtained.

Example 10 Using the ITO sintered body obtained in Example 3 as a target, a transparent conductive film was prepared by DC magnetron sputtering. The sputtering condition is a pressure of 0.6
Pa, Ar / O ₂ = 99/1, input power 4 w / cm ² , target-substrate distance = 3 cm. Substrate temperature 300
The specific resistance of the transparent conductive film obtained at ℃ is 2.3 × 10 ^-4 Ω ・
cm, average visible light transmittance of 80% or more, substrate temperature 2
At 00 ° C., an excellent transparent conductive film having 3.4 × 10 ⁻⁴ Ω · cm and an average visible light transmittance of 80% or more was obtained.

Example 11 Using the ITO sintered body obtained in Example 4 as a target, a transparent conductive film was prepared by DC magnetron sputtering. The sputtering condition is a pressure of 0.6
Pa, Ar / O ₂ = 99/1, input power 4 w / cm ² , target-substrate distance = 3 cm. Substrate temperature 300
The specific resistance of the transparent conductive film obtained at ℃ is 2.2 × 10 ^-4 Ω ・
cm, average visible light transmittance of 80% or more, substrate temperature 2
At 00 ° C., an excellent transparent conductive film with 3.3 × 10 ⁻⁴ Ω · cm and an average visible light transmittance of 80% or more was obtained.

Example 12 Using the ITO sintered body obtained in Example 5 as a target, a transparent conductive film was prepared by DC magnetron sputtering. The sputtering condition is a pressure of 0.6
Pa, Ar / O ₂ = 99/1, input power 4 w / cm ² , target-substrate distance = 3 cm. Substrate temperature 300
The specific resistance of the transparent conductive film obtained at ℃ is 1.5 × 10 ^-4 Ω
cm, average visible light transmittance of 80% or more, substrate temperature 2
At 00 ° C., an excellent transparent conductive film having a viscosity of 2.4 × 10 ⁻⁴ Ω · cm and an average visible light transmittance of 80% or more was obtained.

Example 13 Using the ITO sintered body obtained in Example 6 as a target, a transparent conductive film was prepared by DC magnetron sputtering. The sputtering condition is a pressure of 0.6
Pa, Ar / O ₂ = 99/1, input power 4 w / cm ² , target-substrate distance = 3 cm. Substrate temperature 300
The specific resistance of the transparent conductive film obtained at ℃ is 1.3 × 10 ^-4 Ω ・
cm, average visible light transmittance of 80% or more, substrate temperature 2
At 00 ° C., an excellent transparent conductive film having 2.2 × 10 ⁻⁴ Ω · cm and an average visible light transmittance of 80% or more was obtained.

Example 14 Using the ITO sintered body obtained in Example 7 as a target, a transparent conductive film was prepared by DC magnetron sputtering. The sputtering condition is a pressure of 0.6
Pa, Ar / O ₂ = 99/1, input power 4 w / cm ² , target-substrate distance = 3 cm. Substrate temperature 300
The specific resistance of the transparent conductive film obtained at ℃ is 1.4 × 10 ^-4 Ω ・
cm, average visible light transmittance of 80% or more, substrate temperature 2
At 00 ° C., an excellent transparent conductive film having 2.3 × 10 ⁻⁴ Ω · cm and an average visible light transmittance of 80% or more was obtained.

Comparative Example A transparent conductive film was prepared by DC magnetron sputtering using an ITO sintered body obtained by hot pressing under the conditions of Example 1 which was not subjected to oxidation treatment as it was as a target. The sputtering condition is a pressure of 0.6
Pa, Ar / O ₂ = 98/2, input power 4 w / cm ² , target-substrate distance = 3 cm. Since the sintered body used had a large number of oxygen defects, the oxygen content at which the resistance was the lowest was a little larger than that of the example. Substrate temperature 30
The specific resistance of the transparent conductive film obtained at 0 ° C. is 2.4 × 10 ⁻⁴ Ω
-Cm, average visible light transmittance of about 70%, 200 ℃
The substrate was a transparent conductive film having a specific resistance of 3.5 × 10 ⁻⁴ Ω · cm.

[0041]

EFFECT OF THE INVENTION The sintered body of the present invention is extremely excellent as a sputtering target.
It is possible to obtain a uniform and low-resistance transparent conductive film without any change in the get performance with time. Furthermore, by performing the oxidation treatment at 1300 ° C. or higher, it is possible to obtain an ITO sintered body having a high density, a high oxygen content, and sintered particles that have grown. The surface of such a sintered body is
Since it has a small specific surface area, it is chemically and physically stable,
The composition of the target surface is unlikely to change, abnormal discharge is small, and a more uniform and low-resistance transparent conductive film can be obtained. Further, the amount of oxygen gas supplied into the sputtering apparatus may be small, and in addition, a transparent conductive film having low resistance can be formed.

Further, by growing the sintered particles of such an ITO sintered body, a higher performance sputtering target can be obtained.

Claims (3)

[Claims] 1. A sintered density of 5.5 g / cm ^{3 to} 6.5 g /
cm ³ , the sintered particle diameter is 0.1 μm or more, and 550 n
An indium oxide / tin oxide sintered body, which has a reflectance of 15% to 70% for light having a wavelength of m to 700 nm. 2. A mixed powder of indium oxide and tin oxide is hot-press-sintered and then oxidized to give a sintered density of 5.5 g / cm.
^{3 to} 6.5 g / cm ³ , the sintered particle diameter is 0.1 μm or more,
And the reflectance of light with a wavelength of 550 nm to 700 nm is 15
% -70% Indium oxide / tin oxide sintered body manufacturing method. 3. A sintered density of 5.5 g / cm ^{3 to} 6.5 g /
cm ³ , the sintered particle diameter is 0.1 μm or more, and 550 n
A sputtering target using an indium oxide / tin oxide sintered body having a reflectance of 15% to 70% for light having a wavelength of m to 700 nm.