JP2001040469A - Multi-split ITO sputtering target and method for producing the same - Google Patents

Abstract

(57) [Problem] A split type ITO target in which a plurality of ITO sintered bodies are joined on a single backing plate,
Provided is a target in which the amount of nodules generated around a divided portion is reduced even when sputtering is performed with low applied power. SOLUTION: In a multi-split ITO sputtering target in which a plurality of ITO sintered bodies substantially consisting of indium, tin and oxygen are joined on a single backing plate, a split formed by adjacent sintered bodies. An ITO sputtering target characterized in that the width of the portion is 0.05 to 0.20 mm and no solder material is present at the bottom of the divided portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ITO sputtering target used for producing a transparent conductive thin film,
In particular, the present invention relates to an ITO sputtering target having a divided portion in which a plurality of target materials are arranged on a single backing plate.

[0002]

2. Description of the Related Art ITO (Indium Tin Oxi)
de) The thin film has characteristics such as high conductivity and high transmittance,
Further, since fine processing can be easily performed, they are used in a wide range of fields such as display electrodes for flat panel displays, window materials for solar cells, and antistatic films. There are various methods for manufacturing an ITO thin film, and a high-performance film such as an easy enlargement of an area, easy control of film forming conditions, and a small change with time in the resistance value and transmittance of the obtained film is desired. For this reason, a sputtering method using an ITO sintered body has become mainstream.

In recent years, the size of mother glass for producing liquid crystal panels has increased in order to increase the size of liquid crystal panels and improve productivity. However, the I target used for the ITO target
Since the TO sintered body is a ceramic, it is difficult to produce such a large sintered body with a high yield, and it is expensive because of a low yield. Therefore, instead of manufacturing a large sintered body, a method of manufacturing a target by arranging a plurality of small sintered bodies on one backing plate has been adopted.

[0004] An ITO sputtering target formed by arranging a plurality of ITO sintered bodies side by side on a single backing plate can produce a large-sized target with good yield, but increases the use time of the target. Accordingly, a new problem is caused in that a large amount of nodules is generated in an adjacent portion (divided portion) between the sintered bodies and around the divided portion.

[0005] The nodule means a black substance generated on the surface of the target as the cumulative sputtering time increases when the ITO target is continuously sputtered in a mixed gas atmosphere of argon gas and oxygen gas. It is known that this black deposit, which is considered to be a lower oxide of indium, is likely to cause abnormal discharge during sputtering, and itself is a source of foreign matter (particles). Therefore, when sputtering is performed continuously, foreign matter defects occur in the formed thin film, which causes a reduction in the manufacturing yield of flat panel displays such as liquid crystal display devices.

[0006] In order to reduce the nodules generated in the divided portion, for example, as disclosed in JP-A-11-61395, the density of the divided sintered body is set to 6.4 g / cm ³ or more, and the width of the divided portion is reduced. A method has been proposed in which 0.05 mm to 0.4 mm is set, and among the respective ends of the divided ITO sintered body, the end existing on the sputtering surface is processed into R1 to R2.

However, in recent years, in order to improve the performance of a thin film formed with higher definition and higher performance of a liquid crystal display element, a film forming method of discharging with a low applied power has been adopted. It has become. Due to the film formation with the low applied power, nodules are generated even when a target adopting each of the above-described methods is used, which is becoming a problem. In particular, nodules generated around the divided portion cannot be reduced by the technique described in JP-A-11-61395, and further improvement has been desired.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to carry out recent sputtering with a low applied power by using an ITO sputtering target having a split portion which is a single target by combining a plurality of ITO sintered bodies. Even in such a case, an object of the present invention is to provide an ITO sputtering target in which the amount of nodules generated around the divided portion is reduced.

[0009]

Means for Solving the Problems The present inventors have conducted a detailed study on the causes of the formation of nodules around the split part in order to reduce the amount of nodules around the split part of the ITO sputtering target. As a result, nodules generated in the vicinity of the divided portion are such that the solder material remaining at the bottom of the divided portion adheres to the erosion portion of the target surface during sputtering, and the target remains excavated with the adhered portion as a nucleus and becomes a nodule I found that.

Although the cause of the adhered solder material as a nucleus for generating digging remains unclear, the solder material adhered to the target surface reacts with oxygen contained in the sputtering gas to form an oxide. It is considered that this oxide is digged because it has a much higher resistivity than ITO.

The inventors of the present invention have conducted detailed studies on measures to prevent the solder material present at the bottom of the divided portion from adhering to the target surface during sputtering.
In the O sputtering target, it has been found that the nodule generation amount in the vicinity of the divided portion can be reduced by adopting a structure in which the solder material does not exist at the bottom of the divided portion formed between the plurality of sintered bodies, and completed the present invention. .

That is, the present invention provides a multi-split ITO sputtering target in which a plurality of ITO sintered bodies substantially consisting of indium, tin, and oxygen are bonded on a single backing plate, by using adjacent sintered bodies. Characterized in that no solder material is present at the bottom of the divided portion to be formed.
The present invention relates to a TO sputtering target and a method for manufacturing the same.

Hereinafter, the present invention will be described in detail.

FIG. 1 shows an example of the ITO sputtering target of the present invention. In this example, three ITO sintered bodies 2
Is a three-divided ITO target arranged side by side on one backing plate 1, and each ITO sintered body 2 constituting the target has a gap 4 (width of a divided portion) of 0.05 mm to 0.2 mm. Keep the backing plate 1
Are joined on top.

In the present invention, the target having a divided portion is not particularly limited as long as a plurality of sintered bodies are arranged on one backing plate, and the number and shape of the divided portions are not particularly limited. As shown in FIG. 1, the sintered body may be equally divided into three equal parts, or the three divided sintered bodies may have different sizes. Further, in the case of four divisions, it may be divided into a cross-shaped.

The method for producing the ITO sintered body is not particularly limited, but the density of the obtained ITO sintered body is 9%.
It is preferably at least 9.0%.
The sintered body can be manufactured, for example, by the following method.

First, a binder or the like is added to a mixed powder of indium oxide powder and tin oxide powder or an ITO powder or the like, and the mixture is molded by a molding method such as a press method or a casting method to produce an ITO molded body. At this time, if the average particle size of the powder used is large, the density after sintering does not sufficiently increase, and it may be difficult to obtain a sintered body having a relative density of 99.0% or more.
The average particle size of the powder used is desirably 1.5 μm or less, and more preferably 0.1 to 1.5 μm.

The tin oxide content in the mixed powder or the ITO powder is 5 to 15 wt.% At which the specific resistance decreases when a thin film is manufactured by a sputtering method. % Is desirable.

Next, if necessary, CI
A consolidation process such as P is performed. At this time, in order to obtain a sufficient consolidation effect, the CIP pressure is preferably ² ton / cm ² or more, and more preferably ² to 3 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. Even when the initial molding is performed by the press method, it is desirable to perform the same binder removal treatment when a binder is used at the time of molding.

The compact thus obtained is put into a sintering furnace and sintered. As the sintering method, any method may be used as long as the relative density of the sintered body is 99.0% or more, but sintering in air is preferable in consideration of the cost of production equipment and the like. However, in addition to this, hot pressing (H
Other conventionally known sintering methods such as P) method, HIP method and oxygen pressure sintering method can also be used. As for the sintering conditions, the sintering conditions that make the relative density of the sintered body 99.0% or more can be appropriately selected. However, in order to obtain a sufficient density increasing effect and to suppress the evaporation of tin oxide. ,
It is desirable that the sintering temperature be 1450 to 1650 ° C. The atmosphere during sintering is preferably air or a pure oxygen atmosphere. The sintering time is also 5 hours or more, preferably 5 hours, in order to obtain a sufficient density increasing effect.
Desirably, it is 30 hours.

Subsequently, the ITO sintered body is ground to a desired size. At this time, the end of the ITO sintered body on the side where the ITO sintered bodies 2 face each other, and the end (3 in the figure) existing on the sputtering surface has a radius of 0.5 to 2 mm. In other words, it is preferable to process to R0.5 to R2. If this R processing is larger than R2, the generation of nodules in the divided portion may be remarkable, and if smaller than R0.5, abnormal discharge may occur frequently due to electric field concentration at the end. . In addition, about the other end which exists on the sputtering surface of the ITO sintered body,
Although not necessary, appropriate rounding may be performed.

Next, the sputtering surface of the ITO sintered body is mechanically polished, and the surface roughness of the surface to be sputtered is Ra.
Is preferably 0.8 μm or less, and Rmax is preferably 7.0 μm or less. More preferably, Ra is 0.1.
1 μm or less, and Rmax is 2 μm or less. By doing so, it is possible to effectively suppress abnormal discharge generated in the uneven portion on the target surface and formation of nodules due to abnormal discharge.

Further, since the ITO sintered body has a high hardness and cracks easily occur inside the sintered body during the grinding, it is desirable to perform the processing by wet processing.

The plurality of ITOs thus obtained are
The sintered body is joined on one backing plate. The backing plate and the solder material used in the present invention are not particularly limited, but examples of the backing plate include oxygen-free copper and phosphor bronze, and examples of the solder material include indium solder.

The joining can be performed, for example, in the following steps. First, the processed plurality of ITO sintered bodies and the backing plate are heated to a temperature equal to or higher than the melting point of the solder material to be used.

Next, a solder material is applied to the joint surface of the heated ITO sintered body and the joint surface of the backing plate. The bonding surface of the ITO sintered body coated with the solder material and the bonding surface of the backing plate obtained in this manner are bonded, but the R-processed end is arranged on the sputtering surface of the split portion, The width of the divided part after cooling is from 0.05 mm to 0.1 mm.
It is preferable to arrange them so as to be 20 mm.

If the width of the divided portion exceeds 0.20 mm, the backing plate material made of oxygen-free copper or the like at the bottom of the divided portion may fly out and cause particles. If the thickness is less than 0.05 mm, the ITO sintered body increases due to thermal expansion when installed in a vacuum apparatus and actually sputtered, and adjacent sintered bodies may collide with each other and be damaged.

The width of the divided portion in the state of being heated for bonding depends on the material of the backing plate to be used, the melting point of the solder material to be used, the size of the ITO sintered body to be used, and the final target size. May be selected as appropriate.
For example, when bonding three sintered bodies of 800 mm × 280 mm on one backing plate to form one target, when oxygen-free copper is used for the backing plate and indium solder is used for the solder material, By setting the width of the divided portion to 0.53 mm while the sintered body and the backing plate are heated to 156 ° C., the width of the joined portion after cooling is 0.2 mm.

The control of the width of the divided portion can be performed, for example, as follows. That is, a jig having a thickness of 0.53 mm is inserted into the divided portion, and the backing plate and the sintered body are joined. After the positioning of the sintered body and the backing plate is performed and the solder material is solidified, the jig inserted into the joint is extracted and cooled to room temperature.

The jig to be inserted into the division is not particularly limited as long as it can withstand the temperature at the time of joining.
Examples include stainless steel, iron, brass, carbon, Teflon, and polyimide resin.

Next, the sintered body-backing plate assembly thus obtained is cooled. In this cooling process, the temperature of the assembly is (the melting point of the solder material−30 ° C.)
The jig is once removed while the temperature is between (melting point of solder material) and the temperature (melting point of solder material −10 ° C.) to (melting point of solder material + 50 ° C.) at a pressure of 0.1 to 0.5 kgf / cm ² or less. )
Is blown to the divided portion to remove the solder material existing in the divided portion.

As a gas blown to the dividing portion, an inert gas such as argon or nitrogen is preferable. Immediately after the removal of the solder material at the divided portion, the jig is inserted into the divided portion again, and
Cool to 0 ° C. When the temperature of the assembly reaches 120 ° C., the jig is removed again, and the assembly is cooled to room temperature, thereby manufacturing the ITO sputtering target of the present invention, characterized in that no solder material is present at the bottom of the divided portion. Becomes possible. If the jig is kept inserted to a temperature lower than 120 ° C., the jig may not be able to be pulled out, which is not preferable.

Here, the variation in the density between the respective sintered bodies bonded on one backing plate is ±
Desirably, it is within 0.3%. By doing so, the film thickness distribution of the thin film formed on the substrate is improved. Further, it is desirable that the structure of each sintered body, for example, the particle size, the dispersibility of tin, and the like have little variation among the sintered bodies. By doing so, the film quality (resistivity, transmittance) distribution of the thin film formed on the substrate is improved.

At the time of sputtering, an inert gas such as an argon gas is used as a sputtering gas, if necessary, and an oxygen gas is used as necessary.
Discharge is performed while controlling to rr. As a power application method for discharging, DC, RF or a combination thereof can be used. However, in consideration of the stability of discharge, DC or RF superimposed on DC is preferable. There is no particular limitation on the power density applied to the target, but the target of the present invention is particularly effective under recent low-power discharge (2.0 W / cm ² or less) conditions.

The thus-obtained ITO sputtering target having the divided portion of the present invention reduces the amount of nodules generated around the divided portion even when a recent film forming method with low applied power is used. be able to.

The sputtering target according to the present invention is also effective for a target to which a third element is added for the purpose of imparting an additional function to ITO. As the third element, for example, Mg, Al, Si, T
i, Zn, Ga, Ge, Y, Zr, Nb, Hf, Ta and the like can be exemplified. The addition amount of these elements is not particularly limited. However, in order not to deteriorate the excellent electro-optical characteristics of ITO, (the total amount of oxides of the third element)
0% at // (ITO + sum of oxides of third elements) / 100
Over 20% (weight ratio).

[0037]

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 Indium oxide powder having an average particle diameter of 1.3 μm and tin oxide powder having an average particle diameter of 0.7 μm were put into a ball mill pot, and nylon balls having a diameter of 10 mm were added thereto, followed by dry ball mill mixing for 5 hours. To produce a mixed powder. The obtained mixed powder was mixed with water, a dispersant, and a binder to form a slurry, which was then poured into a resin mold for casting to produce three molded articles of 130 mm × 80 mm × 10 mm.

Next, after performing installed drying them molded body into a drying oven, 3 ton / cm ² These moldings
CIP treatment at a pressure of Subsequently, these compacts were placed in a degreasing furnace and heated at 450 ° C. for 10 hours in an air atmosphere to remove organic substances remaining on the compacts. Sintering was performed under the conditions.

Sintering temperature: 1500 ° C. Heating rate: 25 ° C./Hr Sintering time: 10 hours When the density of the obtained sintered body was measured by the Archimedes method, all were 7.11 g / cm ³ (relative density: 99) .4
%)Met. Next, this sintered body is 100 mm × 58 mm
It processed to × 6 mm. Next, among the surfaces of the obtained sintered body, Ra and Rmax of the sputtering surface were machined to 0.08 μm and 1.1 μm, respectively, using a polishing machine. Further, for the end portion to be the sputtering surface, R
1 processing was performed. After heating the thus obtained sintered body and the backing plate to 156 ° C., indium solder (melting point: 156 ° C.) is applied to each joint surface, and these sintered bodies are separated by the width of the divided part. Was set to 0.11 mm, and a Teflon plate having a width of 0.11 mm was inserted into the divided portion.

When the temperature of the ITO sintered body-backing plate assembly reached 128 ° C., once the Teflon plate was removed, a heat gun (manufactured by Kawabe Sawtooth Sales Co., Ltd.)
By irradiating with argon gas at a temperature of 200 ° C. and a pressure of 0.5 kgf / cm ² using a trade name “HOT JET”), the indium solder present in the divided portion was removed. Thereafter, a Teflon plate was inserted again into the division. After pulling out the Teflon plate inserted in the division when the target-backing plate assembly reaches 120 ° C.,
The target was cooled to room temperature. The width of the divided portion after cooling was 0.1 mm.

The obtained target was set in a vacuum apparatus, and sputtering was performed under the following conditions.

DC power: 1.7 W / cm ² Sputter gas: Ar + O ₂ gas pressure: 5 mTorr O ₂ / Ar: 0.1% A sputtering test was continuously performed under the above conditions for 60 hours. The external appearance photograph of the target after the discharge was subjected to image processing using a computer, and the generation amount of nodules was examined. Nodules only occurred on 4% of the target surface.

Example 2 In the same manner as in Example 1, three ITO sintered bodies of 7.11 g / cm ³ (relative density: 99.4%) were obtained. Next, this sintered body was processed into 100 mm × 58 mm × 6 mm. Next, among the surfaces of the obtained sintered body, Ra and Rmax of the sputtering surface were set to 0.08 μm and 1.1 μm, respectively.
m was machined using a grinder. Further, R1 processing was performed on an end portion to be a sputtering surface. The sintered body and the backing plate thus obtained were
After heating to 56 ° C., indium solder was applied to each joint surface, and these sintered bodies were separated by a width of 0.2 parts.
It joined to the backing plate so that it might be 3 mm, and the Teflon board of width 0.23 mm was inserted in the division part.

When the temperature of the ITO sintered body-backing plate assembly reached 154 ° C., the Teflon plate was once removed, and then an argon gas having a temperature of 160 ° C. and a pressure of 0.1 kgf / cm ² was used using a heat gun. To remove the indium solder present in the divided portion. Thereafter, a Teflon plate was inserted again into the division. After pulling out the Teflon plate inserted in the division when the target-backing plate assembly reaches 120 ° C.,
The target was cooled to room temperature. The width of the divided part after cooling was 0.20 mm.

The obtained target was set in a vacuum apparatus, and a sputtering test was continuously performed under the same conditions as in Example 1 for 60 hours. The external appearance photograph of the target after the discharge was subjected to image processing using a computer, and the generation amount of nodules was examined. Nodules only occurred on 4% of the target surface.

Example 3 In the same manner as in Example 1, three ITO sintered bodies of 7.11 g / cm ³ (relative density: 99.4%) were obtained. Next, this sintered body was processed into 100 mm × 58 mm × 6 mm. Next, among the surfaces of the obtained sintered body, Ra and Rmax of the sputtering surface were set to 0.08 μm and 1.1 μm, respectively.
m was machined using a grinder. Further, R1 processing was performed on an end portion to be a sputtering surface. The sintered body and the backing plate thus obtained were
After heating to 56 ° C., indium solder was applied to each joint surface.

Next, these sintered bodies were joined to a backing plate so that the width of the divided portion became 0.23 mm, and a Teflon plate having a thickness of 0.23 mm was inserted into the divided portion. The temperature of the sintered body-backing plate assembly is set to 1
While maintaining the temperature at 56 ° C., the Teflon plate was once extracted, and the temperature was set to 147 ° C. and the pressure was set to 0.5 kgf / c using a heat gun.
By irradiating with argon gas of m ² , indium solder existing in the divided portion was removed. Thereafter, a Teflon plate having a thickness of 0.23 mm was inserted into the divided portion again, and the assembly was cooled.

When the temperature of the assembly reached 120 ° C., the Teflon plate inserted into the division was pulled out and cooled to room temperature to obtain a target. The width of the divided part after cooling was 0.20 mm.

The obtained target was set in a vacuum apparatus, and a sputtering test was continuously performed for 60 hours under the same conditions as in Example 1. The external appearance photograph of the target after the discharge was subjected to image processing using a computer, and the generation amount of nodules was examined. Nodules only occurred on 6% of the target surface.

Comparative Example 1 An ITO sintered body was manufactured under the same conditions as in Example 1. When the density of the obtained sintered bodies was measured by the Archimedes method, all were 7.11 g / cm ³ . Next, this sintered body is
It processed to 00 mm x 58 mm x 6 mm. Next, among the surfaces of the obtained sintered body, Ra and R of the sputtering surface were used.
Max was machined to 0.08 μm and 1.1 μm, respectively, using a polishing machine. Further, R1 processing was performed on an end portion to be a sputtering surface. After heating the thus obtained sintered body and the backing plate to 156 ° C., indium solder was applied to each joint surface. Next, these sintered bodies were separated by a width of 0.27 m.
m, and then cooled to room temperature to obtain a target. The width of the divided part after cooling was 0.24 mm. The resulting target had a structure in which indium solder remained at the bottom of the split part.

The obtained target was set in a vacuum apparatus, and sputtering was performed under the following conditions.

DC power: 1.3 W / cm ² Sputter gas: Ar + O ₂ gas pressure: 5 mTorr O ₂ / Ar: 0.1% A sputtering test was continuously performed for 60 hours under the above conditions. The external appearance photograph of the target after the discharge was subjected to image processing using a computer, and the generation amount of nodules was examined. Nodules also occurred on 46% of the target surface.

[0054]

According to the ITO sputtering target having the dividing portion of the present invention, the amount of nodules generated around the dividing portion can be reduced even when a recent method of forming a film with low applied power is used.

[Brief description of the drawings]

FIG. 1 is a view showing the appearance of a multi-split ITO sputtering target of the present invention.

[Explanation of symbols]

 1: backing plate 2: ITO sintered body 3: end of ITO sintered body 4: divided part

Continued on the front page F term (reference) 4G030 AA34 AA39 BA02 BA15 GA14 GA16 GA20 GA27 4K029 BA50 BC09 DC05 DC12 DC16 DC21 DC25 DC34

Claims (6)

[Claims] 1. A multi-split ITO sputtering target in which a plurality of ITO sintered bodies substantially consisting of indium, tin, and oxygen are bonded on a single backing plate, and divided by adjacent sintered bodies. A multi-split ITO sputtering target characterized in that no solder material is present at the bottom of the portion. 2. The width of the divided portion is 0.05 mm to 0.20 m.
2. The multi-segment IT according to claim 1, wherein
O sputtering target. 3. The multi-split ITO sputtering target according to claim 1, wherein the relative density of the ITO sintered body is 99.0% or more. 4. An end of the ITO sintered body where the sputtering surface of the ITO sintered body intersects with the side surface constituting the divided portion is R.
4. Processed to 0.5 to R2.
The multi-split ITO sputtering target according to any one of the above. 5. The ITO sintered body according to claim 1, wherein the surface to be sputtered has a center line average roughness (Ra) of 0.8 μm or less and a maximum height (Rmax) of 7.0 μm or less. Item 5. Multi-division ITO according to any one of items 1 to 4
Sputtering target. 6. A method of bonding a plurality of ITO sintered bodies substantially consisting of indium, tin and oxygen to desired positions on a single backing plate by using a solder material, and then sintering the backing plate. In the cooling process of the assembly, while the temperature of the assembly is (melting point of solder material−30 ° C.) to (melting point of solder material), the pressure is 0.1 to 0.5 kgf / c.
m ² , a gas having a temperature of (the melting point of the solder material −10 ° C.) to (the melting point of the solder material + 50 ° C.) is blown to the divided portion to remove the solder material existing at the bottom of the divided portion. A method for producing a split ITO sputtering target.