WO2007013387A1

WO2007013387A1 - Sputtering target, method for manufacturing such sputtering target, and transparent conducting film

Info

Publication number: WO2007013387A1
Application number: PCT/JP2006/314550
Authority: WO
Inventors: Koki Yano; Kazuyoshi Inoue; Nobuo Tanaka
Original assignee: Idemitsu Kosan Co., Ltd.
Priority date: 2005-07-27
Filing date: 2006-07-24
Publication date: 2007-02-01
Also published as: KR20080032121A; JP4761868B2; TWI394852B; CN101233258B; TW200714724A; KR101302332B1; CN101233258A; JP2007031786A

Abstract

Provided is a sputtering target containing zinc oxide and tin oxide or a sputtering target containing zinc oxide, tin oxide and indium oxide. A metal or an alloy is dispersed over the entire sputtering target.

Description

Specification

Sputtering target, manufacturing method thereof and transparent conductive film

Technical field

[0001] The present invention relates to a sputtering target, a method for producing the same, and a transparent conductive film. More specifically, the present invention relates to a sputtering target that does not reduce or use indium, which is a scarce resource. Background art

[0002] Liquid crystal displays (LCD) and organic-electrical luminescence (EL) displays are used in display devices such as mobile phones, personal digital assistants (PDAs), personal computers, laptop computers, and televisions in terms of display performance and energy saving. As the mainstream. As the transparent conductive film used in these devices, an indium stannate (hereinafter referred to as ITO) film dominates. However, ITO films use a large amount of indium (usually about 90% by mass). Since indium is a scarce resource and there are concerns about supply, and there is some toxicity, the development of transparent conductive films with a small amount of indium is important for the further spread of display devices using transparent electrodes.

[0003] A transparent conductive film containing zinc oxide tin monoxide as a main component has been studied as a transparent conductive film by reducing or using indium (for example, see Patent Document 1).

Although this transparent conductive film has problems such as high resistance and large in-plane distribution of resistance, no studies have been made to solve these problems.

[0004] As the sputtering target ITO, that by the amount of oxygen is constant over kills with low resistance I spoon has been published (e.g., see Patent Document 2.) ₀

However, the oxygen content of the sputtering target with reduced indium has not been studied.

[0005] Moreover, the sputtering target made of site power site and the metal of the metal Sani匕物have been published (e.g., see Patent Document 3.) ₀

However, the impact on the target with reduced indium has not been studied. In addition, the sputtering target consisting of the metal oxide part and metal part force is a metal oxide target. This is a composite of a get, a metal target, and a metal wire. To apply it to a target with reduced indium, the target itself has high resistance, the discharge during sputtering is not stable, the sputtering speed is slow, etc. There was a problem.

Patent Document 1: JP-A-8-171824

Patent Document 2: JP 2000-256842 A

Patent Document 3: Japanese Patent Application Laid-Open No. 2004-030934

[0006] The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a sputtering target capable of obtaining a low-resistance transparent conductive film even when indium is reduced, and a method of manufacturing the sputtering target.

Disclosure of the invention

[0007] As a result of intensive studies to overcome the above problems, the present inventors have determined that the number of oxygen atoms in the metal atoms and oxygen atoms that constitute the sputtering target constitutes an oxide. It was found that a transparent conductive film having a low resistance can be obtained even if indium is reduced by making the amount less than the stoichiometric amount. Further, it has been found that by dispersing a metal or an alloy that is oxidized in a sputtering target, a target with a small amount of oxygen can be stably produced, and the resistance of the target can be reduced. Completed.

[0008] According to the present invention, there are provided the following sputtering target, a production method thereof, a transparent conductive film and a transparent electrode.

1. A sputtering target containing dumbbell and tin oxide, or a dumbbell, tin oxide and indium oxide, wherein a metal or alloy is dispersed throughout the sputtering target.

2. The sputtering target according to 1, which satisfies the following (1) and (2).

0. 65≤M / (M + M) ≤0.9 (1)

Zn Zn Sn

0≤M / (M + M + M) ≤0.7 (2)

In Zn Sn In

[Where M, M and M are Zn in the sputtering target, respectively.

Sn In, Sn and

Zn

And the number of In atoms. ]

3. Furthermore, the sputtering target according to 1 or 2, which satisfies the following (3). M / (M + MX 2 + MX I. 5) ≤0. 99 (3)

o Zn Sn In

[Where M, M, M and M are Zn, S in the sputtering target, respectively.

Zn Sn o In

Indicates the number of atoms of n, O and In. ]

4. sputter-ring target according to any one of the metal or alloy from 0.1 to 6 mass ^_0/0 containing 1 to 3.

5. Hexagonal phase layered compound (In O (ZnO) m: m is 3

twenty three

The sputtering target according to any one of 1 to 4, which includes an integer of force up to 20.

6. The sputtering ticket according to any one of 1 to 5, wherein the Balta resistance is less than 100 mΩcm.

7. The sputtering target according to any one of 1 to 6, wherein the density is 5.3 to 7.2 gZcm ³ .

8. The method for producing a sputtering target according to any one of 1 to 7, comprising a step of mixing a metal oxide powder and a metal powder.

9. A transparent conductive film produced using the sputtering target according to any one of 1 to 7 above.

10. A transparent electrode prepared by etching the transparent conductive film according to 9 above.

[0009] With the sputtering target of the present invention, a transparent conductive film having a low resistance can be obtained even if indium is reduced.

Brief Description of Drawings

[0010] FIG. 1 is a graph showing the relationship between the amount of Zn metal powder and the Balta resistance of a target.

FIG. 2 is a graph showing the relationship between the amount of Zn metal powder and the specific resistance value of a transparent conductive film.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the sputtering target of the present invention will be specifically described.

The sputtering target of the present invention has a form in which a metal or an alloy is dispersed as a whole in an oxide containing at least zinc oxide and tin oxide. As a result, a target with which a low-resistance transparent conductive film can be obtained even if the indium is reduced. Moreover, the resistance of the target can be reduced by dispersing a small metal or alloy that has been oxidized in the sputtering target. [0012] The metal or alloy can be used without particular limitation as long as the performance of the present invention is not impaired. A metal or alloy having a melting point of 1300 ° C or lower, preferably 1000 ° C or lower, more preferably 800 ° C or lower, more preferably 600 ° C or lower is preferable. Is used. If the melting point is 1300 ° C or lower, the resistance of the target tends to decrease because it melts during sintering and the density of the target increases.

Moreover, what a metal oxide shows electroconductivity is also preferable. As such, Zn, Sn, In, Ga, Ge, Cd, Nd, Sm, Ce, Eu, Ag, Au, Al, and alloys containing them as main components can be preferably used. In particular, Zn, Sn, or In is preferable. A plurality of these metals or alloys may be used in combination.

[0013] The metal or alloy is preferably dispersed in the target as aggregates of 500 m or less. More preferably, it is 100 / z m or less, more preferably 10 / z m or less, and particularly preferably 5 m or less.

The presence of a metal or alloy can be judged from the peak of X-ray diffraction. In addition, the dispersion state can be confirmed by the presence of an agglomerated part of metal atoms or a low oxygen part by surface analysis with an X-ray microanalyzer (EPMA). “Dispersed throughout” means that one or more metals or alloys of 500 μm or less can be confirmed in an arbitrary 5000 / z m square region. In addition, the form in which the metal or alloy is dispersed can be realized by a manufacturing method described later.

[0014] The content of the metal or alloy in the sputtering target is preferably 0.1 to 6% by mass, more preferably 0.2 to 4% by mass, and particularly preferably 0.3 to 3% by mass. 0.1 If less than 1% by mass, the effect of the present invention may not be exhibited, or white spots may be formed. If more than 6% by mass, oxygen is insufficient and resistance increases or transparency decreases. There is a risk.

It can be confirmed by X-ray diffraction (XRD) whether or not the sputtering target contains any metal or alloy that is oxidized.

[0015] The sputtering target of the present invention preferably satisfies the following (1) and (2).

0. 65≤M / (M + M) ≤0.9 (1)

Zn Zn Sn

0≤M / (M + M + M) ≤0.7 (2)

In Zn Sn In

[Wherein M, M and M represent Zn, Sn and And the number of In atoms. ]

The value [M / (M + M;)] in the above formula (1) is the value of Zn and Sn in the sputtering target.

Zn Zn Sn

The existence ratio is defined. If this value is less than 0.65, the amount of Sn occupying the target increases and SnO aggregates, which may cause abnormal discharge by charging during film formation.

2

The On the other hand, if it is greater than 0.9, the acid resistance may decrease. M

Zn Z (M + M Zn Sn

), preferably 0.75 to 0.85, more preferably 0.75 to 0.8.

[0016] Equation (2) defines the amount of In in the sputtering target. In consideration of the object of the present invention, it is preferable that the amount of In used is small. However, by adding In, the resistance of the target and the thin film after film formation can be reduced. M Z (M + M + M) is preferably 0.05

In Zn Sn In

˜0.6, more preferably 0.1 to 0.45, even more preferably 0.15 to 0.35, and particularly preferably 0.25 to 0.35.

[0017] The sputtering target of the present invention preferably further satisfies the following (3).

Μ / (Μ + Μ Χ 2 + Μ X I. 5) ≤0. 99 (3)

o Zn Sn In

[Where M, M, M and M are Zn in the sputtering target, respectively.

The numbers of atoms of Zn Sn o In, Sn, O and In are shown. ]

Equation (3) defines the amount of oxygen atoms (O) in the sputtering target. The denominator of equation (3) is the number of oxygen atoms when each metal atom forms an oxide (ZnO, SnO, InO).

2 2 3

means. If the value of equation (3), that is, the ratio of the number of oxygen atoms contained in the sputtering target to the number of oxygen atoms when all of the metal atoms form an oxide, is not greater than 0.99. Even if In is not reduced or used, a sputtering target can be obtained in which a transparent conductive film having low resistance can be obtained. The value of the formula (3) is preferably 0.8 to 0.98, more preferably 0.9 to 0.97. If it is smaller than 0.8, the conductive film after film formation may be colored.

[0018] By controlling the oxygen content in the target as described above, it becomes possible to reduce the resistance of the sputtering thin film, but the exact reason has not been elucidated. However, in the conventional method, it is presumed that the oxygen in the film was excessive because the Zn atoms, which are relatively lighter than Sn and In, were exhausted without reverse sputtering. .

[0019] The values of the above-mentioned formulas (1) to (3) are values of the abundance ratio of each atom obtained by analyzing the composition of the sputtering target using an X-ray microanalyzer (EPMA). We can calculate [0020] As a method for producing the sputtering target of the present invention, for example, there is a method in which a metal or alloy powder is further mixed with a mixed powder of each metal oxide and sintered. By using metal powder, the oxygen content in the target can be easily controlled. In addition, since the resistance of the target itself decreases, the sputtering rate increases and stable sputtering can be performed. In addition, metal powder is known to have a mechanism to stabilize oxygen vacancies in the film and reduce the resistance by generating carriers.

In order to adjust the difference depending on the sputtering equipment and the sputtering conditions, it may be adjusted by introducing a small amount of acidic gas at the time of sputtering in a slightly oxygen-deficient state at the time of sintering.

[0021] When a metal or alloy powder is mixed with each metal oxide powder and sintered, the particle size of the powder is 500 μm or less, preferably 100 μm or less, more preferably 10 μm. Hereinafter, it is particularly preferably 5 m or less. If it is larger than 500 / zm, it will not be uniformly mixed with other raw material powders, so there is a risk that the metal or alloy will be dispersed in the target and the target resistance will increase.

The particle diameter is a value measured with a light scattering equivalent diameter (JIS R 1629).

[0022] In the present invention, in addition to the above metal oxide powders and metal powders, sintering aids (yttria, magnesia, etc.), dispersants (polyesters) are included within the range not impairing the object of the present invention. Ammonia acrylate, etc.), a binder, a lubricant (eg, emulsion of stearic acid), etc. may be added.

The sputtering target of the present invention preferably contains a hexagonal phase layered compound (In 2 O 3 (ZnO) m: m is an integer from 3 to 20) that also has indium oxide / acid / zinc strength. this

twenty three

By including these structures, the sintered density is increased and the resistance of the target is easily decreased. Such a structure can be obtained by the manufacturing method described above. The structure is analyzed by X-ray diffraction (XRD).

The sputtering target of the present invention preferably has a Balta resistance of 0.2 to less than 100 m Q cm. Satisfying this value stabilizes the discharge during sputtering and increases the sputtering rate. More preferably, 0.4 to 20 m Q cm or less, particularly preferably 0.6 to: ίΟπι Ω cm or less. The density of the sputtering target, 5. 3~7. 2gZcm ³ a it is preferred instrument further 6.1 to 7. It especially preferred instrument OgZcm is ^3, at 6. 4~6. 8gZcm ³ It is preferable that there is. By satisfying this value, the discharge during sputtering can be stabilized and the film formation rate can be improved.

[0025] The transparent conductive film of the present invention can be obtained by depositing the above-described sputtering target of the present invention by a conventional method. Further, a transparent electrode can be obtained by etching this transparent conductive film with an etching solution such as mixed acid containing oxalic acid or phosphoric acid.

[Example]

[0026] Hereinafter, the present invention will be described more specifically with reference to Examples. The particle diameter is a value measured by a laser diffraction scattering method.

Example 1

Zinc oxide powder (particle size of 1 m or less), tin oxide powder (particle size of 0.4 m or less) and metallic zinc powder (particle size of 5 μm or less) in a polyethylene pot at the mixing ratio shown in Table 1. The mixed powder was produced by mixing for 72 hours using a dry ball mill.

This mixed powder was put into a mold and pressed at a pressure of 300 kgZcm ² to obtain a molded body. The pressure CIP (cold isostatic pressing) of the molded body 3TonZcm ² rows densification process by molding ivy. Next, this compact was placed in a pure oxygen atmosphere sintering furnace and sintered under the following conditions.

[0027] (Sintering conditions)

Sintering temperature: 1450 ° C, heating rate: 25 ° C ZHr, sintering time: 6 hours, gas introduced into the sintering furnace: oxygen, introduced gas pressure: 30mmH 0 (gauge pressure), introduced gas linear velocity: 2. Preparation for 6cmZ

2

Weight Z gas flow rate: 0.4 kg-min / L, gas introduction start temperature (when the temperature is raised): 400 ° C, gas introduction stop temperature (when the temperature is lowered): 400 ° C.

[0028] The density of the obtained sintered body was measured by the Archimedes method and found to be 5.5 gZcm ³ .

The composition of the sintered body was analyzed using an X-ray microanalyzer (EPMA). As a result, the ratio of the number of oxygen atoms to the total number of metal atoms (OZ (Zn + Sn + In)) was 1.18. The Balta resistance of the target measured by the four probe method was 80 mΩcm. Furthermore, when the target was analyzed by X-ray diffraction (XRD), a peak derived from Zn metal could be confirmed.

In addition, EPMA surface analysis confirms that there are more than 100 dispersed portions of 5-50 μm metal atoms and low oxygen in a 5000 μm square region. It was.

[0029] EPMA and XRD were measured under the following conditions.

• EPMA

Equipment used: Shimadzu Corporation, Electron Beam Microanalyzer EPMA-2300 Caro Fast Voltage: 15kV, Sample Current: 0.05m, Beam Size: 1m, Area Size: 68.

4 X 68. 4 πι, Step Size: 0.2 / z m X O. 2 πι, Measurement elements: Zn, Sn, 0, SBSE (Backscattered electron image)

XRD

Equipment used: Ultima-III, manufactured by Rigaku Corporation

X-ray: Cu-Κ α-ray (wavelength 1.5406Α, monochromatic with graph eye monometer), measured by 2 0-Θ reflection method, continuous scan (1.0 ° Ζ), sampling interval: 0. 02 °, Slit: DS, SS, 2/3 °, RS: 0.6mm

[0030] This sintered body was processed into a sintered body having a thickness of 6 mm by a wet processing method, and joined to an oxygen-free copper backing plate using indium solder to obtain a target.

Using this target, a transparent conductive film was formed by sputtering on a 0.7 mm thick glass substrate (Corning, # 7059). The sputtering conditions were as follows.

(Sputtering conditions)

RF power: 110 W, gas pressure: 0.3 Pa, sputtering gas: Ar, 100%, film thickness: 100 nm, substrate temperature: 200 ° C.

[0031] The specific resistance of the obtained conductive film measured by the four probe method was 50 mΩ · cm. The light transmittance at a wavelength of 550 nm was 90%. The transmittance was measured as the transmittance including the glass substrate using air as a reference.

Raw material composition of sputtering target, composition analysis, sputtering conditions, transparent conductive film

The structure was measured by X-ray diffraction (XRD).

The film composition is the value of each metal atom in the total metal atoms contained in the film.

0032 [0033] Examples 2 and 3: Comparative Examples 1 to 3

A target was prepared and a snotter film was formed in the same manner as in Example 1 except that the composition ratio of the raw materials was changed as shown in Table 1.

The results are shown in Table 1.

[0034] Evaluation example

According to the raw material composition of the sputtering target, the amount of Zn metal powder was changed to 0 to 4 wt%, and the amount of ZnO powder was adjusted by that amount. A snow film was formed.

The obtained transparent conductive film was evaluated for the relationship between the amount of Zn metal powder and the target resistance value, and the amount of Zn metal powder and the specific resistance value of the transparent conductive film. The results are shown in Figs.

Industrial applicability

The transparent conductive film formed using the sputtering target of the present invention can be suitably used as a transparent electrode for various display devices such as liquid crystal display devices and EL display devices.

Claims

The scope of the claims

[1] A sputtering target including dumbbell and tin oxide, or a dumbbell, tin oxide and indium oxide, wherein a metal or an alloy is dispersed throughout the sputtering target.

[2] The sputtering target according to claim 1, wherein the following (1) and (2) are satisfied.

0. 65≤M / (M + M) ≤0.9 (1)

Zn Zn Sn

0≤M / (M + M + M) ≤0.7 (2)

In Zn Sn In

[Wherein M, M and M represent Zn, Sn and

Zn Sn In

And the number of In atoms. ]

[3] The sputtering target according to claim 1 or 2, further satisfying the following (3).

M / (M + M X 2 + M X I. 5) ≤0. 99 (3)

o Zn Sn In

[Where M, M, M and M are Zn, S in the sputtering target, respectively.

Zn Sn o In

Indicates the number of atoms of n, O and In. ]

[4] The sputtering target according to any one of [1] to [3], comprising 0.1 to 6% by mass of the metal or alloy.

[5] Hexagonal phase layered compound with indium oxide / acid / zinc strength (In O (ZnO) m: m is 3?

twenty three

The sputtering target according to any one of claims 1 to 4, further comprising an integer up to 20.

6. The sputtering target according to any one of claims 1 to 5, wherein the Balta resistance is less than 100 mΩcm.

[7] The sputtering ticket according to any one of [1] to [6], wherein the density is 5.3 to 7.2 gZcm ³ .

[8] The method for producing a sputtering target according to any one of [1] to [7], comprising a step of mixing a metal oxide powder and a metal powder.

[9] A transparent conductive film produced using the sputtering target according to any one of claims 1 to 7.

10. A transparent electrode produced by etching the transparent conductive film according to claim 9.