WO2002072912A1

WO2002072912A1 - Tin oxide powder for ito sputtering target, production method of the powder, sintered body sputtering target for ito film fomation and production method of the target

Info

Publication number: WO2002072912A1
Application number: PCT/JP2002/001305
Authority: WO
Inventors: Mitsuyuki Konaka; Toshiya Kurihara
Original assignee: Nikko Materials Company, Limited
Priority date: 2001-03-12
Filing date: 2002-02-15
Publication date: 2002-09-19
Also published as: JP2009029706A; TW555875B; CN1633516A; KR20030087185A; JP4190888B2; KR20060033935A; KR100663617B1; KR100581138B1; JPWO2002072912A1; CN100537828C; JP5456291B2

Abstract

Tin oxide powder for ITO sputtering target, characterized in that a median diameter obtained from a particle size distribution ranges from 0.40 to 1.0 νm, and a 90% particle size obtained from a particle size distribution is up to 3.0 νm. Tin oxide powder that can provide a sintered body having excellent density enhancing feature and component uniformity which are suitable for ITO thin film formation, and an ITO film forming sputtering target sintered by using the powder, whereby it is possible to produce at low costs an ITO film forming tin oxide-indium oxide target that can restrict nodules from being generated at ITO thin film forming and their attendant deterioration in thin film quality.

Description

Specification

Tin oxide powder for I T O sputtering target, method of manufacturing the same powder, sintered body sputtering target for forming I T O film, and method of manufacturing the same

The present invention relates to a tin oxide powder for IT T sputtering target, a sintered body sputtering target suitable for forming an IT0 film for forming an IT0 film, and a method for producing the same. Background ·

An I T O (complex oxide of indium monotin) film is widely used as a transparent electrode (film) for display devices centered on liquid crystal displays.

As a method of forming this I T O film, it is common to carry out by means generally called physical vapor deposition such as vacuum vapor deposition and sputtering. In particular, magnetron sputtering is often used for operability and film stability.

In the formation of a film by sputtering, positive ions such as Ar ions are physically collided with the evening getter installed at the cathode, and the collision energy is used to release the material that constitutes the umbrella, and they face each other. It is carried out by laminating a film having substantially the same composition as the target material on the anode side substrate.

The coating method by the sputtering method is characterized in that thin films of angstrom unit to thick films of several tens / X m can be formed at stable film forming speed by adjusting processing time, power supply and the like.

What is particularly problematic when forming an ITO film is the occurrence of projections called nodules in the erosion area of the ITO target and its periphery. The generation of nodules causes a decrease in sputtering rate and an abnormal discharge (micro-ring), which significantly lowers productivity. Also, due to nodules and abnormal discharge, coarse particles (particles) float in the sputtering chamber, and these particles reattach to the generated thin film, causing defects (pinholes) and protrusions on the thin film. The problem is that the quality of the membrane decreases.

As a measure to reduce the generation of nodules, it is generally known to increase the density of the target and to reduce the pores in the get.

In addition, it is effective to reduce dispersion of the composition in the target by finely dispersing zinc oxide and tin oxide which are raw material powders of the target sintered body and increasing their dispersibility. In particular, when the particles of tin oxide are coarse, they can not be sufficiently dissolved in mixed indium oxide, and since they are present as a lump of tin oxide in a sintered body, they become the origin of nodules during sparging. . In addition, they cause pores in the sintered body and become a factor that hinders the densification of the sintered body.

In order to refine the tin oxide powder, the method of mechanically pulverizing the raw material powder is the simplest and most inexpensive. Commonly known grinding devices include jet mills in which the raw materials collide with each other or impact on a liner for grinding, and bead mills in which powder media is used for grinding by grinding between media or between liners. . However, in the jet mill method, in order to grind a hard and cohesive raw material such as tin oxide powder to the particle size in the submicron range, the number of passes increases and the throughput is extremely reduced, which is costly. It will be a disadvantage.

From such a thing, it is preferable to use a media stirring type crusher for sintering powder of IT target, and a wet type bead mill that is easy to control the aggregation of the raw material is most suitable.

If the grinding power or the number of passes is increased in this bead mill grinding machine, it will be further pulverized, but if it is too strong, control of the grinding amount will be difficult, and if it is too weak, the movement of beads and slurry in the mill will deteriorate and grinding will occur. Since the efficiency is significantly reduced, it is required to control with appropriate strength to grind. The indium oxide powder, which is the raw material powder of the ITO target, is easy to grind and does not pose any problem, but it is hard like tin oxide and powder with strong cohesiveness is harder to grind than indium oxide powder. . Therefore, grinding of tin oxide is particularly problematic as raw material powder, and it is necessary to control this.

When grinding tin oxide, it is considered that grinding can be made more finely by increasing powder power or pass number, but in addition to the problems caused by increasing grinding power or pass number, liners in mill grinders or There is a problem that hard bead material etc. is mixed in the tin oxide powder as contamination (contaminant).

Therefore, the problem of contamination of the sintered material due to densification and sintering due to sintering by using finely divided powder is a mutually contradictory problem, and it is an optimum powder for carrying out densification. The current situation is that it can not be said that

From the above, it was necessary to obtain a sintered body target with uniform and high density components for forming an ITO thin film, but the optimum tin oxide powder and high density baking that can satisfy these requirements There was a problem that no target was obtained. Disclosure of the invention

The present invention solves the above-mentioned problems, and in particular, tin oxide powder capable of obtaining a sintered body excellent in densification and uniformity of components suitable for forming an IT thin film and baking using the powder. A sputtering target for forming an ITO film and a manufacturing method thereof are provided, whereby tin oxide for forming an ITO film can be suppressed which can suppress deterioration of nodules and the like generated at the time of forming an ITO thin film and the film It aims to provide indium oxide targets at low cost.

The technical means for solving the above problems is to strictly control the particle size of the tin oxide powder, whereby it is possible to obtain a sputtering alloy suitable for an ITO transparent conductive film or the like. We found that we could do it. The present invention is based on this finding.

1) It is characterized in that the median diameter obtained from the particle size distribution is in the range of 0.40 to 1. O m and the 90% particle size obtained from the particle size distribution is in the range of 3.06 m or less. Tin oxide powder for sputtering targets.

2) It is characterized in that the median diameter obtained from the particle size distribution is in the range of 0.40 to 0. 0, and the 90% particle size obtained from the particle size distribution is in the range of 1.0 m or less. Tin oxide powder for sputtering evening get.

3) A method of producing a tin oxide powder for ITO sputtering according to the above 1) or 2), characterized in that a slurry of tin oxide powder having a solid content of 65% or more is ground by a wet bead mill.

4) Sintered tin oxide and zinc oxide powder having a median diameter determined from the particle size distribution in the range of 0.40 to 1.1, and a 90% particle size determined from the particle size distribution in the range of 3.0 or less It is characterized in that it is a sintered body for I TO film formation.

5) Oxidation with a median diameter determined from the particle size distribution in the range of 0.40 to 0.60 ^ m and a 90% particle size determined from the particle size distribution in the range of 1.0 / x m or less A sintered body sputtering target for forming an ITO film, characterized in that tin and indium oxide powder are sintered.

6) 7. The sputtering target for forming an ITO film as described in the above 4) or 5) characterized by having a density of 12 g / cm ³ or more.

7) A slurry of tin oxide powder having a solid content of 65% or more is sintered using a tin oxide powder obtained by grinding using a wet bead mill, and the I TO according to each of the above 4) to 6). Method for producing a sputtering target for film formation.

I will provide a. Brief description of the drawings

FIG. 1 is a diagram showing the integrated sputtering power and the nodule coverage at sputtering of sputtering singlets prepared in Examples 1 and 2 and Comparative Example, and FIG. 2 is a diagram showing Examples 1 and 2 and Comparative Example FIG. 3 is a diagram showing the integrated sputter power and the micro-arcing frequency at the time of sputtering of the sputtering target produced in FIG. 3. FIG. 3 is the median diameter and Z at each solid concentration of the tin oxide powder slurry produced in Example 3. It is a figure which shows r amount of contamination. Embodiment of the Invention

In the present invention, the tin oxide powder for ITO sputtering target has a median diameter in the range of 0.40 to 1.0 m determined from the particle size distribution, and a 90% particle size determined from the particle size distribution. Preferably, the median diameter obtained from the particle size distribution is in the range of 0.40 to 0.60 m and the 90% particle size obtained from the particle size distribution is 1.0 or less. Range

The normal (conventional) tin oxide powder has an integrated volume frequency of 50% obtained from the particle size distribution = median diameter of 1.5 to 2.5 / zm, and an integrated volume frequency of 90% obtained from the particle size distribution. % Value = 90% The particle size was in the range of 5. 0 to 10 0 m.

The above-mentioned tin oxide powder was mixed with indium oxide powder at a predetermined ratio, and was pulverized to a median diameter of about 0.5 to 1. 0 m by a wet bead mill. However, tin oxide powder in the mixed powder is not well dispersed, and some are 5 to 1

It was present as coarse particles of about 0 / m. Such coarse particles of tin oxide can not be sufficiently dissolved in zinc oxide and cause tin oxide lumps or pores in the sintered body, so the density of the sintered body can not be sufficiently increased, and uniform and high density can be obtained. It was not possible to obtain a sintered body of

And since the component of a sintered compact target is not uniform like this and sufficient density is not obtained like this, dispersion occurs during sputtering film formation.

There is a problem that the quality of the TO film is reduced. As a result of investigating this cause, the particle diameter of the above-mentioned tin oxide powder is important, noticing that coarse particles contained in the raw material reduce the density of the sintered body, the particle size distribution of tin oxide powder The median diameter determined is in the range of 0.40 to 1.O m and the 90% particle diameter determined from the particle size distribution is in the range of 3.0 m or less, and preferably the median diameter determined from the particle size distribution is 0. By obtaining a sintered body of high density and high quality by setting the particle diameter in the range of 40 to 0.60 m and the 90% particle diameter obtained from the particle size distribution to be within the range of 1. O im or less Successful. By using the above-mentioned powder of the present invention, sintering having a high density of 7.1 2 g / cm ³ or more, further 7.1 3 g / cm ³ or more, which is suitable for I-TO sputtering. You can get the body.

In the case of powder, adjustment of the particle size of tin oxide is performed by selection of raw material powder, adjustment of grinding power, number of passes, adjustment of material of crushed beads, adjustment of solid content of tin oxide powder slurry, It can be carried out by appropriately controlling such that the above conditions can be achieved.

Although zircon dioxide is used as powder media, the problem of contamination can be minimized by using a tin oxide powder slurry with a solid content of 65% or more because of the problem of zirconium contamination.

As a result, it is possible to obtain a fired powder with excellent sinterability, which can be crushed without difficulty. [Examples and Comparative Examples]

An embodiment of the present invention will be described. The present embodiment is merely an example, and the present invention is not limited to this example. That is, within the technical idea of the present invention, all aspects or modifications other than the embodiment are included. (Example 1)

A tin oxide powder with a median diameter of 2.0 x m, a 90% particle diameter of 3.50 / im, and a BET specific surface area of 4.0 m ² Zg determined from the particle size distribution is mixed with pure water to have a solid content of 6 5% A slurry was made. The particle size distribution was measured using a laser diffraction / scattering particle size distribution analyzer (LA-920, manufactured by Horiba, Ltd.), and the BET specific surface area was a continuous flow surface area meter (SA-6200, manufactured by Horiba, Ltd.). At this time, in order to disperse tin oxide powder in pure water, ammonia water was added to adjust the pH of the slurry to 9.0. Next, the prepared slurry is crushed by a bead mill, and the median diameter determined from the particle size distribution is 1.0 m, 90% particle diameter is 2.0 zm, and 8 lbs. Specific surface area is 6.0 m ² Zg. did. At this time, we used zircon beads (YTZ) in consideration of abrasion resistance.

The tin oxide slurry pulverized according to the above and a zinc oxide powder having a median diameter of 2.0 xm, a 90% particle diameter of 3.0 im, and a BET specific surface area of 8.0 m ² / g as determined from the particle size distribution It mixed with the pure water so that it might become tin oxide 1: oxygen oxide 9 by a weight ratio, and the slurry of solid content 50% was produced.

Next, the prepared tin oxide / indium oxide mixed slurry is mixed with a bead mill using a bead mill, and the median diameter obtained from the particle size distribution is 0.80 / m, the 90% particle diameter is 1.50 m, the BET specific surface area Powdered to 10 m ² Zg.

Next, a binder was added to the pulverized slurry, and the mixture was granulated and dried by a spray dryer. The dry powder is filled into a mold and molded with a hydraulic press at a pressure of 1000 kgf Zcm ² and further with a cold isostatic press (CIP) a pressure of 1 500 kgf / cm ² The resultant was molded at a density of 4.0 g Z cc.

Next, as a result of sintering the compact at a sintering temperature of 1550 ° C. for 4 hours in an oxygen atmosphere, the density of the obtained sintered body is a high density of 7.12 g / cm ^{3 according} to the Archimedes method. A sintered body was obtained.

However, when the compact was sintered at a sintering temperature of 1 500 ° C., the density reached only 7.00 7 g / cm ³ . (Example 2)

Under the same powder conditions as Example 1 described above, the median diameter is 0.5 m, the 90% particle diameter is 0.80 m, and the B ET specific surface area is 7.0 m ² Zg, which are obtained from the particle size distribution. Crushed.

Next, powdered tin oxide slurry, and median oxide diameter determined from particle size distribution: 2.0 m, 90% particle diameter: 3.0 ^ m, B ET specific surface area: 8.0 m ² / g The powder is mixed with pure water, and the median diameter is 0.80 m, the 90% particle size is 1.50 2 m, and the BET specific surface area is 10 m ² / g in the same manner as in Example 1. I framed.

The ground slurry was granulated and dried in the same manner as in Example 1. Next, the powder obtained is filled into a mold and, after being formed at a pressure of 1000 kgf / cm ^{2 with} a hydraulic press, it is further subjected with a cold isostatic press (CIP). It was molded at a pressure of kgf Zcm ² to obtain a molded body having a density of 4.0 g / cc.

Next, as a result of sintering the compact at a sintering temperature of 1550 ° C. for 4 hours in an oxygen atmosphere, the density of the obtained sintered body is a high density of 7.12 g zcm ^{3 by} Archimedes method. A sintered body was obtained.

Furthermore, even when the compact was sintered at a sintering temperature of 150 ° C., a high density sintered body with a density of 7.30 g / cm ³ was obtained. (Comparative example 1)

A tin oxide powder having a median diameter of 2.0 / m, a 90% particle diameter of 3.50 m, and a BET specific surface area of 4.0 m ² / g determined from the particle size distribution, and a median diameter determined from the particle size distribution There 2. 0 im, 9 0% particle size 3. 0 m, tin oxide B ET specific surface area of 8, 0 m ² Zg solids weight ratios in the same manner as in example oxidation Injiumu powder 1: oxidation It mixed with pure water so that it might become indium 9, and the slurry of solid content 50% was produced.

Next, according to the same method as in Example 1, the particles were milled to a median diameter of 0.80 m, a 90% particle diameter of 1.50 / m, and a BET specific surface area of 10 mg as determined from the particle size distribution. A binder was added to the powdery slurry and granulated and dried in the same manner as in Example 1. After the obtained powder is filled in a mold, it is molded with a hydraulic press at a pressure of 1000 kgf Zcm ² and further subjected to a cold isostatic press (CIP) 150 500 kgf / cm ² It shape | molded by the pressure of, and obtained the molded object whose density is 4.0 g / cc.

Next, as a result of sintering the compact at a sintering temperature of 1550 ° C. for 4 hours in an oxygen atmosphere, the density of the obtained sintered body is only 7.10 g / cm ³ by the Archimedes method. It did not reach. In addition, even when the sintering temperature was raised to 160 ° C. Density of the sintered body was 7. l OS gZc m ³ .

The sintered bodies produced in the above-described Examples 1 and 2 and Comparative Example 1 were machined, a sputtering set was produced, and the amount of generation of nodules (coverage) at the time of sputtering and the abnormal discharge at the time of sputtering The number of (micro arching) was measured.

The conditions of sputtering are as follows.

Target size: 1 2 7 x 5 0 8 x 6. 3 5 mm

Spatter gas: Ar + 0 ₂

Sputtering gas pressure: 0.5 P a

Spatter gas flow rate: 3 0 0 S C CM

Oxygen concentration in the sputtering gas: 1 V o 1%

Leakage flux density: 0. I T

Sputtering power density: Sputtering was started at 0.5 W / cm ² and the film deposition rate was increased to maintain a constant rate.

Spatula integrated power: ~ 1 6 0 WH r / cm ²

Fig. 1 shows the amount of nodule generation and Fig. 2 shows the number of micro arcing. The amount of generated nodules (coverage) was calculated by binarizing the image of the erosion area of the target with a computer and dividing the area of the generated nodules by the area of the erosion. The threshold value of micro-arcing is set to: detection voltage: 100 V or more; emission energy (sputter voltage when arc discharge occurs X sputtering current X generation time): 10 mJ or less. As apparent from FIG. 1, the target of the comparative example has a rapid increase of nodules from the integrated power of 4 OWH r Z cm ² , and the life end of integrated power of 1 6 0 WH rZ cm ² with a nodule coverage of 40% or more In contrast to the above, the evening get of Examples 1 and 2 is significantly superior, with no accumulation being 0% even when spattering is performed up to an integrated power of 1 6 OWH r "cm ^2. I understand.

Also in the micro arcing number in FIG. 2, the target of the comparative example rapidly increases the arcing number from the integrated power of 8 OWH r / cm ² , while the target of the examples 1 and 2 always has the arcing number from time to time. It can be seen that stable film formation conditions can be obtained with less.

From the comparison of Examples 1 and 2, no difference was found between the two in terms of the amount of nodule generation, but it can be seen that Example 2 is superior in terms of the number of arcings. (Example 3)

The amount of contamination (impurities) of zirconavis at the time of producing the tin oxide powder used in the above Examples 1 and 2 was examined. For grinding, the bead mill used in the above example was used, and powder frame beads used were Zr beads (YTZ) with a diameter of 0.5 mm.

Tin oxide powder was mixed with pure water so that the solid content weight ratio was 25%, 45% and 65%, respectively. At this time, in order to disperse tin oxide powder in pure water, ammonia water was added to adjust the pH to 8. 0 to 10. 0, and the viscosity of the slurry was adjusted to 0 l Pa · s or less.

The slurry of each solid content was subjected to pass operation under the same powdering conditions, and the respective crushed particle sizes and the amount of Zr mixed were investigated. As a result, as shown in FIG. 3, when compared with the same particle size, it was found that the higher the solid content, the smaller the mixing amount of Zr. Effect of the invention

It has the remarkable property of being able to obtain a sintered body excellent in densification suitable for forming an ITO thin film and uniformity of the component, and thereby the quality that occurs when the ITO sputtering film formation is not uniform. It has an excellent effect of being able to obtain a tin oxide-indium oxide target for forming an ITO film which can suppress abnormal projections such as nodules and the like at low cost.

Claims

The scope of the claims

1. It is characterized in that the median diameter obtained from the particle size distribution is in the range of 0.40 to 1.0 / xm, and the 90% particle size obtained from the particle size distribution is in the range of 3.0 or less. It is a tin oxide powder for ITO sputtering target.

2. It is characterized in that the median diameter obtained from the particle size distribution is in the range of 0.40 to 0.60 m, and the 90% particle size obtained from the particle size distribution is in the range of 1.0 or less. Tin oxide powder for sputtering targets.

3. A method for producing a tin oxide powder for an I-TO sputtering target according to 1) or 2) above, characterized in that a slurry of tin oxide powder having a solid content of 65% or more is milled by a wet bead mill.

4. Tin oxide and indium oxide powder having a median diameter determined from the particle size distribution in the range of 0.40 to 1.0 m and a 90% particle size determined from the particle size distribution in the range of 3.0 or less And a sintered body sputtering target for forming an I-TO film.

5. Tin oxide and indium oxide powder having a median diameter determined from the particle size distribution in the range of 0.40 to 0.60 m and a 90% particle size determined from the particle size distribution in the range of 1. O ^ m or less A sintered sputtering target for forming an IT film, characterized in that it is sintered.

6.7.1 A sputtering target for forming an ITO film as described in 4 or 5 above, which has a density of 2 gZ cm ³ or more.

7. A slurry of tin oxide powder having a solid content of 65% or more is sintered using a tin oxide powder obtained by grinding in a wet bead mill, as described in each of 4) to 6) above. Method of producing a sputtering set for ITO film formation.