JPH1068072A - Ito cylindrical target and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ITO cylindrical (cylindrical or columnar) target having quality, i.e., density, grain size, bulk resistance or the like the same as that of the conventional planar ITO(indium tin oxide) target excellent in quality by using a sintering method. SOLUTION: In an ITO sputtering target, an ITO layer is formed on the surface of a cylindrical or columnar supporting body having >=40mm diameter, the thickness of the ITO layer is regulated to >=3mm, its length is regulated to >=500mm, furthermore, the ITO layer is free from joints in the longidudinal direction and peripheral direction and is integrated, the density of the ITO layer is regulated to >=5.0g/cm<3> and the content of oxygen in the ITO layer is regulated to 97 to 100% to the theoretical value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an indium tin oxide (Indi oxide) used for a transparent conductive film such as a liquid crystal.
um-Tin Oxide, hereinafter referred to as "ITO". )
For forming thin film of ITO by sputtering method
More particularly, the present invention relates to an ITO cylindrical (cylindrical or cylindrical) target and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, an ITO film has an n-type conductive semiconductor characteristic and has a visible light transmittance (transparency) in addition to a very high conductivity. It is used in a wide variety of applications, such as thin-film electroluminescence display devices, radiation detection elements, transparent tablets for terminal equipment, heat-generating films for preventing dew condensation on window glass, antistatic films, and selective transmission films for solar collectors.

As a means for forming the ITO film, a chemical film forming method such as a spray method or a CVD method utilizing thermal decomposition of a compound, or a physical film forming method such as a vacuum evaporation method or a sputtering method is known. Among them, the use of the “sputtering method” has been widely used, with the advantage that “a film can be formed in a large area and a low-resistance film can be formed with good reproducibility”.

In general, a flat ITO sintered target is used as ITO used in the sputtering method. This ITO sintered target is formed by pressing a powder mixture of indium oxide and tin oxide or a powder mixture obtained by adding a dopant thereto at room temperature, and further sintering the formed body at 1250 to 1650 ° C. in the atmosphere. An improved method of performing sintering in a pressurized oxygen atmosphere of 1 atm or more to obtain a manufacturing method and a higher density target has been adopted.

Since such a flat ITO sintered target has been used for a long time, various efforts have been made to increase the density and reduce the resistance of the target, and the film obtained by the sputtering method has good film characteristics. And has a feature that generation of nodules is small.

However, when sputtering is performed using a generally used magnetron sputtering apparatus with a flat ITO target, erosion proceeds to a specific portion of the target surface due to sputtering while controlling plasma by a magnet. Since the deepest erosion portion of the portion determines the life of the target, there is a problem that the utilization efficiency of the target is reduced to about 20 to 30%.

Therefore, a target having a cylindrical shape has been proposed in order to increase the use efficiency of the target. This new type of magnetron sputtering method using a cylindrical target is a method in which a magnetic field generating means is installed inside a cylindrical target, and the target is rotated while cooling from the inside of the target to perform sputtering.

[0008] This method is different from a flat target, and the use efficiency can be reduced to about 60 to 70%. Of the targets used for such sputtering, a metal target can be easily formed into a cylindrical shape, but there is a very difficult problem with ceramics, particularly an ITO sintered target.

A manufacturing method called CIP, HIP or cast molding, which is an extension of the conventional flat sintered target manufacturing method, has also been proposed (for example, Japanese Patent Application Laid-Open No. Hei 3-1553).
867, JP-A-3-153863, JP-A-5-1564
31) has a problem that cracking or deformation is apt to occur during sintering, and it is difficult to bond a sintered product to a cylindrical body (corresponding to a backing plate of a flat target) that supports the sintered product. At present, it is far from practical use.

In addition, as a method of manufacturing a cylindrical target, a target coating forming method by a thermal spraying method has been proposed in the field of ceramic targets.
(For example, JP-A-60-181270, JP-A-5-214)
525) However, ceramics have a problem that the thermal sprayed film cannot be thickened due to a large difference in thermal expansion with the metal as a support, and the adhesiveness is reduced due to a thermal shock during use, and the ceramic is peeled off. ing. Attempts have been made to solve this problem by forming an undercoat layer similar to a ceramic layer between the supporting metal body and the ceramic sprayed coating, but at present it has not been sufficient.

In particular, ITO sintered targets have unique problems different from ordinary ceramic targets, and there has been no example in which an effective ITO cylindrical target has been successfully produced by spray coating.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ITO cylindrical material (density, grain size, bulk resistance, etc.) having the same level of quality as a conventional high quality flat ITO target using a sintering method. (Cylindrical or cylindrical) target.

[0013]

The present invention provides: In an ITO sputtering target, a diameter of 4
ITO on the surface of a cylindrical or columnar support of 0 mm or more
A layer having a thickness of 3 mm or more and a length of 5 mm or more.
00 mm or more, and the ITO layer is integrated without any seam in the length direction and the circumferential direction.
An ITO cylindrical target, wherein the O layer has a density of 5.0 g / cm ³ or more and the oxygen content in the ITO layer is 97% to 100% of a theoretical value.

2. 2. The ITO cylindrical target as described in 1 above, wherein the average particle size of the ITO layer is less than 10 μm.

3. The bulk resistance of the ITO layer is 50mΩ
3. The ITO cylindrical target according to the above 1 or 2, which is less than 1 cm.

4. 4. The ITO cylindrical target according to any one of the above items 1 to 3, wherein the cylindrical or columnar support is made of Ti or Mo. By spraying ITO powder on a cylindrical or columnar support with a diameter of 40 mm or more, the thickness is 3 mm or more, the length is 500 mm or more, and there is no seam in the length direction and the circumferential direction. , Density is 5.0 g / c
m ³ or more, and 97% to 100% of the oxygen content theoretical
A method for producing an ITO cylindrical target, comprising forming an ITO layer as follows.

6. 6. The method for producing an ITO cylindrical target according to the above item 5, wherein the average particle size of the ITO layer is less than 10 μm.

[7] The bulk resistance of the ITO layer is 50mΩ
7. The method for producing an ITO cylindrical target according to the above 5 or 6, wherein the diameter is less than 1 cm.

8. 8. The method for producing an ITO cylindrical target according to any one of the above items 5 to 7, wherein the cylindrical or columnar support is made of Ti or Mo. The average particle size of the ITO powder used for thermal spraying is 20-60
9. The method for producing an ITO cylindrical target according to any one of the above items 5 to 8, wherein the thickness is μm.

[10] Raw material powder having an average primary particle size of 2.0 μm or less was granulated, and then roasted at 800 to 1,500 ° C.
The above-mentioned item 5, wherein the TO powder is sprayed on the support.
10. The method for producing an ITO cylindrical target according to any one of items 9 to 9.

11. The method for producing an ITO cylindrical target according to any one of the above items 5 to 10, wherein the ITO layer is formed by a plasma spraying method.

12. Before the ITO powder is sprayed, the cylindrical or cylindrical support is provided with an undercoat layer for relieving the stress caused by the difference in the coefficient of thermal expansion between the cylindrical or cylindrical support and the ITO layer in advance. 12. The method for producing an ITO cylindrical target according to any one of the above items 5 to 11, wherein

13. 13. The method for producing an ITO cylindrical target according to the above 12, wherein the undercoat layer is formed by a thermal spraying method.

Is provided.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, ITO powder is spray-coated on a cylindrical or columnar support, and the ITO powder is deposited on the support.
Basically, a layer is formed. The cylindrical or columnar support used here corresponds to the backing plate used in the flat target.

As the support, a metal plate having good thermal conductivity used in a conventional backing plate can be used. However, a Ti or Mo material having a thermal expansion coefficient closer to that of the ITO cylindrical target of the present invention can be used. The use of a support is more preferable because the separation of the target and the support can be effectively prevented. However, it does not limit the use of other metals as a support.

The undercoat layer for relaxing the stress caused by the difference in thermal expansion coefficient between the ITO target layer and the support of the present invention can be applied before the above-mentioned ITO powder spraying.

For example, an undercoat layer of Ti, Mo or the like can be provided on a metal support having relatively good thermal conductivity. In order to improve the adhesion between these materials, an undercoat layer can be provided via a film of a material such as Ni.

As can be seen from the above, the undercoat layer is not limited to a single layer, but may be a multilayer film. This undercoat layer can be formed by plating sputtering deposition or other coating methods, but using a thermal spray coating method is more convenient and preferable in view of the subsequent ITO powder spraying step.

As the ITO powder spraying method, several kinds of spraying methods such as a plasma spraying method, a high-speed gas spraying method and a gas spraying method can be used.

In the production of the ITO cylindrical target of the present invention, the amount of oxygen in the target is important. In order to adjust the oxygen content, thermal spraying may be performed in a shield gas in which the amount of oxygen is adjusted and the atmosphere is protected and adjusted with a non-oxidizing gas such as Ar, Ne, or He.

As a result, a homogeneous and stable sprayed layer of ITO without variation in chemical composition can be obtained. Before the thermal spray coating, the cylindrical or cylindrical support is preferably provided with irregularities of appropriate dimensions such as roughening the outer surface or forming grooves in order to improve the adhesion of the thermal spray coating. .

In the production of the ITO cylindrical target, setting the optimum conditions for the ITO powder is most important. Although the cylindrical target having the ITO sprayed layer has a feature that the use efficiency is remarkably excellent, the density of the ITO layer required as an important element of the ITO target is lower than that of the flat ITO target. It is because it turned out.

In the present invention, the density of the ITO layer formed by thermal spraying is set to 5.0 g / cm ³ or more, and the oxygen content in the ITO layer is set to 97% or more and less than 100% of the theoretical value. It is important that the density of the ITO layer formed by thermal spraying be 5.0 g / cm ³ or more.

When the ITO density is less than 5.0 g / cm ³ , the specific resistance of the thin film formed by sputtering deteriorates, and the thin film formed on the substrate by the heat effect of the sputtering is peeled off from the support or the ITO target. Defects such as cracks tend to occur.

In order to maintain the film characteristics depending on the oxygen content, the oxygen content in the ITO layer should be 97% or more of the theoretical value.
It is most suitable to use those having a range of less than 0%.

Therefore, the density of the ITO layer of the present invention formed by thermal spraying and the oxygen content in the ITO layer need to be set as described above.

It is desirable that the ITO layer of the ITO cylindrical target of the present invention has an average particle size of less than 10 μm and a bulk resistance value of less than 50 mΩ · cm, preferably less than 10 mΩ · cm. If the average particle size and the bulk resistance value of the ITO layer deviate from the above ranges, the discharge becomes unstable and the amount of generated particles increases, which is not preferable.

Further, the raw material powder having an average primary particle size of 2.0 μm or less was granulated and then roasted at 800 to 1,500 ° C.
O powder can be suitably used as a spray powder having a high fluidity.

The selection of the thermal spray powder is important in producing the ITO cylindrical target as described above.

The proper sprayed powder of the present invention improves the adhesion of the ITO layer of the target, provides a layer with a uniform distribution having an average particle size of less than 10 μm, and further reduces the oxygen content and the bulk resistance value in the ITO layer. It is possible to obtain the above values stably and easily.

The outline of the method for producing the ITO cylindrical target from the ITO raw material powder is as follows.

[0043]

[Table 1]

Next, a description will be given based on an embodiment. The conditions shown in the embodiment are merely examples showing one condition.
The scope of various conditions that can be accommodated are included in the present invention without departing from the scope of the appended claims.

[0045]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of manufacturing a target of the present invention is as follows.

Indium oxide was produced by first depositing metal indium as indium hydroxide by an electrolytic method, and then roasting the obtained indium hydroxide.

Further, tin oxide powder dissolves metal tin with nitric acid and precipitates it as metastannic acid. Then, the deposit (methstannic acid) was filtered, washed and dried, and the obtained metastannic acid was calcined to obtain tin oxide powder.

The obtained indium oxide powder and tin oxide powder were mixed, pulverized, granulated, and roasted at 1300 ° C. to obtain a sprayed powder.

On the other hand, the cylindrical support has an inner diameter of 50 mm.
A cylindrical support made of Ti having a diameter of mmφ, an outer diameter of 70 mmφ, and a length of 500 mm was prepared. The surface of the cylindrical support was subjected to a roughening treatment.

Using the above ITO powder for thermal spraying, plasma spraying was performed on the cylindrical support.

For plasma spraying, power was applied using a plasma gas of Ar gas to form a 4 mm-thick ITO film.

The ITO cylindrical target thus obtained has a density of 5.3 g / cm ³ , an oxygen content of 98% of the theoretical value, an average particle diameter of 1.2 μm, and a bulk resistance of 8.4 mΩ · cm. Was obtained.

Next, sputtering was performed on a substrate using this ITO cylindrical target, and the resulting transparent conductive film was examined for sheet resistance and transmittance.
An ITO film which can be used for a CD (liquid crystal) was formed. As a result, film forming characteristics equivalent to those of a good quality flat plate-like ITO sputtering target were obtained.

During the sputtering operation, peeling of the support from the target or generation of cracks in the target layer was not observed.

As another method, Ni and In were sprayed as an undercoat layer on a support made of Mo and Ti, and then ITO powder was sprayed in the same manner as described above. In this case, the same result as described above was obtained.

Further, the density of the ITO layer is 5.0 g / cm.
^When the oxygen content was less than ³ and the oxygen content was out of the range of 97% to less than 100% of the theoretical value, the sputtering thin film formed on the substrate had a poor specific resistance and could not be used.

When the average particle size of the ITO layer was 10 μm or more and the bulk resistance exceeded 50 mΩ · cm, a large amount of arc discharge occurred, and particles on the substrate tended to increase.

In the present invention, it is sufficient to obtain a result comparable to the sputtering film forming characteristics of a good quality flat plate-shaped ITO target, and a comparative example is not required.

The thus obtained ITO cylindrical target of the present invention shows much higher utilization efficiency than the flat target.

[0060]

According to the present invention, the ITO cylindrical target is a flat plate-shaped IT conventionally manufactured by a sintering method.
It has the same high density, low resistance and fine crystal grain size as the O target, and the characteristics of the film obtained by sputtering the target of the present invention have the same quality as that of the above high quality flat ITO target. Is provided.

Further, since the target is a cylindrical target, the use efficiency of the target is much higher than that of the flat target. Further, it is easy to regenerate the initial ITO state by spraying the ITO powder again on the target ITO erosion portion reduced by sputtering.

Claims (13)

[Claims] 1. In an ITO sputtering target, an ITO layer is formed on a cylindrical or columnar support having a diameter of 40 mm or more, and the ITO layer has a thickness of 3 mm or more, a length of 500 mm or more, and the ITO layer. The layers are integral with no seams in the length direction and the circumferential direction, and the density of the ITO layer is 5.0 g / cm ³ or more, and
An ITO cylindrical target, wherein the oxygen content in the TO layer is 97% to 100% of a theoretical value. 2. The ITO cylindrical target according to claim 1, wherein the average particle size of the ITO layer is less than 10 μm. 3. The bulk resistance value of the ITO layer is 50 mΩ · c.
3. The ITO cylindrical target according to claim 1, wherein the value is less than m. 4. The ITO cylindrical target according to claim 1, wherein the cylindrical or columnar support is made of Ti or Mo. 5. By spraying ITO powder on a cylindrical or columnar support having a diameter of 40 mm or more, a thickness of 3 mm or more, a length of 500 mm or more, and no joints exist in the length direction and the circumferential direction. It is integrated and has a density of 5.
0 g / cm ³ or more, and the oxygen content is 97% or more of the theoretical value.
Forming an ITO layer which is 100%.
A method for producing a TO cylindrical target. 6. The method for producing an ITO cylindrical target according to claim 5, wherein the average particle size of the ITO layer is less than 10 μm. 7. The bulk resistance value of the ITO layer is 50 mΩ · c.
7. The method for producing an ITO cylindrical target according to claim 5, wherein the value is less than m. 8. The method for producing an ITO cylindrical target according to claim 5, wherein the cylindrical or columnar support is made of Ti or Mo. 9. The method for producing an ITO cylindrical target according to claim 5, wherein the average particle size of the ITO powder used for thermal spraying is 20 to 60 μm. 10. An IT prepared by granulating raw material powder having an average primary particle size of 2.0 μm or less and then roasting at 800 to 1,500 ° C.
6. The thermal spraying of O powder on a support.
10. The method for producing an ITO cylindrical target according to any one of items 9 to 9. 11. The method for manufacturing an ITO cylindrical target according to claim 5, wherein the ITO layer is formed by a plasma spraying method. 12. A cylindrical or columnar support before spraying ITO powder is provided with an underlayer for relaxing stress caused by a difference between respective thermal expansion coefficients of the cylindrical or columnar support and the ITO layer. The ITO according to any one of claims 5 to 11, wherein a coat layer is provided.
A method for producing a cylindrical target. 13. The method for producing an ITO cylindrical target according to claim 12, wherein the undercoat layer is formed by a thermal spraying method.