KR100948557B1 - ???2 sputtering target and process for producing same - Google Patents

Abstract

The present invention provides a high-performance sputtering target capable of forming a sputtering film having both a high specific density and a low specific resistance and a high transmittance at a high film formation rate while preventing abnormal discharge and generation of particles.

This sputtering target contains SnO ₂ as a main component and contains 1.15 to 10 mass% of Nb ₂ O ₅ and Ta ₂ O ₅ in a total amount, and the content mass ratio of Nb ₂ O ₅ / Ta ₂ O ₅ is 0.15 to 0.90. And a sintered compact formed at 1550 to 1650 ° C.

SnO₂-based sputtering target, sputter film

Description

SnO₂-based sputtering target and manufacturing method thereof {SNOO2 SPUTTERING TARGET AND PROCESS FOR PRODUCING SAME}

[Background of invention]

[Field of Invention]

The present invention relates to a SnO ₂ -based sputtering target and a method for manufacturing the same, and specifically, to a SnO ₂ -based sputtering target used for forming a transparent conductive film such as a flat panel display, a resistive touch panel, a solar cell, and a method for manufacturing the same. It is about.

In recent years, SnO ₂ -based transparent conductive films have been used in a wide range of applications such as flat panel displays, resistive touch panels, and solar cells. The SnO ₂ transparent conductive film is mainly produced industrially by a spray method or a CVD method. However, these methods are not suitable for uniformizing the film thickness in large areas, difficult to control the film formation process, and furthermore, chlorine-based gas, which is a contaminant, can be generated during film formation, so a new manufacturing method without such a defect is required. have.

On the other hand, attempts are also prepared SnO ₂ based transparent conductive film by sputtering. However, since it is difficult to obtain a SnO ₂ -based sputtering target that can withstand the use for sputtering, it is not widely used. This is because SnO ₂ is a poorly sinterable material, which makes it difficult to manufacture a high density sintered compact suitable for use in sputtering. In addition, although in order to obtain a sputtering film having low resistance required as an electrode material, Sb ₂ O ₃ by the addition of SnO known sputtering target of the SnO ₂ type made a specific resistance of _2, sintering property improving effect was small.

A SnO ₂ -based sputtering target having a sintered density of 4.0 g / cm ³ or more containing Ta, Nb or the like is known (see, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2000-273622)). In addition, SnO ₂ -based sputtering targets having a specific resistance of 1 × 10 ⁷ Ω · cm or less containing Ta, Nb or the like are also known (see Patent Document 2 (Japanese Patent Laid-Open No. 2000-281431)). In the examples of these documents, the sintering of the sputtering target is performed at 1500 ° C. However, no reports have yet been made about SnO ₂ -based sputtering targets capable of producing sputtered films having both low resistivity and high transmittance characteristics, which are required as transparent electrode films for plasma display panels (PDPs), which are in high demand. .

<Patent Document 1> Japanese Patent Application Laid-Open No. 2000-273622

<Patent Document 2> Japanese Patent Application Laid-Open No. 2000-281431

[Overview of invention]

The present inventors have, as a main component and the SnO _2, Nb ₂ O ₅ and Ta ₂ O is made to contain the total amount of 1.15~10% by weight of a _5, Nb ₂ O ₅ / Ta ₂ O ₅ content mass ratio of 0.15 to 0.90 By sintering the molded product of phosphorus and microcrystalline at 1550-1650 ° C, a sputtered film having both a high specific density and a low specific resistance and high transmittance can be formed at a high film formation rate while preventing abnormal discharge and generation of particles. And knowledge that a high performance SnO ₂ -based sputtering target can be produced.

Accordingly, the present invention provides a high-performance SnO ₂ -based sputtering target having a high relative density and capable of forming a sputtered film having both a low specific resistance and a high transmittance at a high film formation rate while preventing abnormal discharge and generation of particles. It is for that purpose.

And, the manufacturing method of SnO ₂ based sputtering target according to the present invention,

SnO ₂ as a main component, Nb ₂ O ₅ and Ta ₂ O ₅ containing 1.15 to 10% by mass in a total amount, and the content mass ratio of Nb ₂ O ₅ / Ta ₂ O ₅ is 0.15 to 0.90 To prepare,

Sintering the molded body at 1550 to 1650 ° C

It comprises a method.

In addition, the SnO ₂ -based sputtering target according to the present invention comprises SnO ₂ as a main component and contains 1.15 to 10% by mass of Nb ₂ O ₅ and Ta ₂ O ₅ in a total amount, and Nb ₂ O ₅ / Ta ₂ O ₅ As a SnO ₂ -based sputtering target having a flow rate mass ratio of 0.15 to 0.90,

By X-ray diffraction using CuKα as the X-ray source, the peak attributable to Nb ₂ O ₅ at the diffraction angles 2θ at 22 to ₂₃ degrees and 28 to 29 degrees is substantially not observed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the relationship between the specific resistance and transmittance peak value after annealing, and oxygen flow rate (partial pressure) with respect to the sputter film obtained using the sputtering target produced in Example 2 and the comparative example 6.

2 is a diagram showing X-ray diffraction of the sputtering target produced in Example 4. FIG.

FIG. 3 is a diagram showing X-ray diffraction of the sputtering target produced in Example 8. FIG.

4 is a diagram showing X-ray diffraction of the sputtering target produced in Comparative Example 7. FIG.

[Detailed Description of the Invention]

SnO ₂ system Sputtering  Manufacturing method of target

In the method of the present invention, first, SnO ₂ is used as a main component, and Nb ₂ O ₅ and Ta ₂ O ₅ are contained in a total amount of 1.15 to 10% by mass, and the content mass ratio of Nb ₂ O ₅ / Ta ₂ O ₅ is The green body molded product which is 0.15-0.90 is prepared. When the total amount of Nb ₂ O ₅ and Ta ₂ O ₅ is 1.15 to 10% by mass, it is easy to realize a low film specific resistance while improving the sintered density while preventing the increase of the film specific resistance due to the increase of unsolvable Ta and Nb. Lose. Preferred total amounts of Nb ₂ O ₅ and Ta ₂ O ₅ are 1.15 to 8% by mass, more preferably 3.5 to 6% by mass, still more preferably 4 to 6% by mass. Furthermore, by setting the content mass ratio of Nb ₂ O ₅ / Ta ₂ O ₅ to 0.15 to 0.90, the film resistivity formed by sputtering film while ensuring the amount of Nb ₂ O ₅ contributing to densification by liquid phase sintering and preventing a decrease in sintering density. The rise of can be prevented. The content mass ratio of preferable Nb ₂ O ₅ / Ta ₂ O ₅ is 0.15 to 0.60, more preferably 0.17 to 0.33, still more preferably 0.20 to 0.33.

In the present invention, the molded product of the micro grains may be molded by any method as long as the raw material powder containing the composition is molded. For example, SnO ₂ Powder, Nb ₂ O ₅ The powder and Ta ₂ O ₅ powder may be mixed at a blending ratio that satisfies the above composition to produce a raw powder, and may be produced by molding the raw powder.

According to a preferred aspect of the present invention, it is preferable that the molded article of the green body using the raw material powder is made easy to give a predetermined shape by adding a binder to the raw material powder. Such a binder is not limited as long as it is a known binder that is lost or scattered by heating, and an aqueous polyvinyl alcohol solution or the like can be used. Therefore, in this aspect, it is preferable that the green body is dried and then heated (degreased) so that the binder scatters or disappears prior to sintering. Although the method of drying and a heating is not limited, It is preferable to dry at 50-130 degreeC for 5 to 30 hours first, and to carry out degreasing by heating at 500-800 degreeC for 6 to 24 hours next.

According to a preferred aspect of the present invention, the green body compact may further contain Fe ₂ O ₃ , NiO ₂ , CoO, In ₂ O ₃ , or a mixture thereof in order to further improve the sintered density. When adding these metal oxides, it is preferable to make the total addition amount into 100-7000 ppm, More preferably, it is 350-7000 ppm, More preferably, it is 700-7000 ppm.

According to another preferred aspect of the present invention, the green body compact may further contain Al ₂ O ₃ , SiO ₂ , Y ₂ O ₃ , or a mixture thereof in order to further lower the resistivity of the sputtering target. If the addition of these metal oxides, it is preferable that these metal oxides, Nb ₂ O _5, and the added amount is below this 20% by weight the total amount of Ta ₂ O _5.

According to another preferred aspect of the present invention, the green body is formed of Ga ₂ O ₃ , Bi ₂ O ₃ , Mn ₂ O ₃ , Fe ₂ O ₃ , NiO, CoO, or a mixture thereof in order to further improve the sintered density. It may contain more. If the addition of these metal oxides, it is preferable that these metal oxides, Nb ₂ O _5, and the added amount is below this 20% by weight the total amount of Ta ₂ O _5.

Next, in the method of the present invention, the green body molded product prepared as described above is sintered at 1550 to 1650 ° C. By performing sintering within this temperature range, liquid phase sintering is sufficiently proceeded to increase the sintered density, the transmittance when the resistivity value is minimum in the sputter film can be increased, and the melting of SnO ₂ is prevented to prevent the sintering of the desired shape. The sintered compact can be manufactured easily. Preferable sintering temperature is 1550-1600 degreeC. Within this temperature range, since the temperature difference inside the sintered compact can be made small, the warpage of the sintered compact can be effectively prevented and the productivity can be further improved.

According to a preferable aspect of the present invention, the sintering is preferably performed for 2 to 20 hours, more preferably 3 to 12 hours, still more preferably 4 to 8 hours. If it is in this range, sintering can fully be carried out, suppressing a power consumption and ensuring high productivity.

According to a preferred aspect of the present invention, the sintering is preferably performed in an oxygen-containing atmosphere in order to secure a high sintered density. For example, the sintering can be performed in an oxygen pressurized atmosphere, an oxygen atmosphere, or an atmospheric atmosphere.

SnO ₂ system Sputtering  target

The SnO ₂ -based sputtering target produced by the above-described production method of the present invention contains SnO ₂ as a main component and Nb ₂ O ₅ And 1.15 to 10% by mass of Ta ₂ O ₅ in a total amount, and the content mass ratio of Nb ₂ O ₅ / Ta ₂ O ₅ is 0.15 to 0.90, and CuKα rays (λ = 1.54050 Hz) are used as X-ray sources. By X-ray diffraction, the peak attributable to Nb ₂ O ₅ at the diffraction angles 2θ at 22 to ₂₃ ° and 28 to 29 ° may not be substantially observed, but is produced by the production method of the present invention. It is not necessarily limited to this. That is, in the production method of the present invention, the compacted molded product is sintered at 1550-1650 ° C, but according to the findings of the present inventors, in the sintered body obtained at the sintering temperature within this range, by X-ray diffraction using Cu as the X-ray source, Peaks attributable to Nb ₂ O ₅ at diffraction angles 2θ of 22 to ₂₃ degrees and 28 to 29 degrees are not observed. Such a SnO ₂ -based sputtering target of the present invention has a high relative density, and can form a sputtered film having both a low specific resistance and a high transmittance at a high film formation rate while preventing abnormal discharge and generation of particles.

According to a preferred aspect of the present invention, the X-ray diffraction is measured using an X-ray diffraction apparatus (MXP3, manufactured by MAC Science), and the tube voltage is 40 kV, the tube current is 30 mA, the sampling interval is 0.02 °, and the scan rate is 4 ° C. /. It is preferable to carry out on conditions of 1 degree of scattering slits: 1 degree, 1 degree of scattering slits, and a light receiving slit: 0.3 mm. And according to the preferable aspect of this invention, it is preferable that the highest value of an X-ray intensity is less than 100 at the diffraction angle 2 (theta) 22-23 degrees and 28-29 degrees by X-ray diffraction on the said suitable conditions. Do. In addition, if, for example, even if that peak is observed due to Nb ₂ O ₅ by X-ray diffraction of the more sensitive than X-ray diffraction of the above-described favorable conditions, due to Nb ₂ O ₅ by X-ray diffraction under the appropriate conditions, Unless a peak is substantially observed, it is included in the scope of the present invention.

According to a preferred aspect of the present invention, the SnO ₂ -based sputtering target preferably has a relative density of 90% or more and measured by the Archimedes method, more preferably 93% or more, and still more preferably 96% or more. By having such a high relative density, it is possible to effectively prevent abnormal discharge and generation of particles during sputtering. In addition, it is preferable that the measurement by this Archimedes method is performed at room temperature.

According to a preferred aspect of the present invention, the SnO ₂ -based sputtering target is preferably used for the production of a sputtered film having a film specific resistance of 1 × 10 ⁻² Ω · cm or less. According to the SnO ₂ -based sputtering target of the present invention, a sputtered film having a high transmittance can be produced while ensuring a low film specific resistance value.

According to a preferred aspect of the present invention, the SnO ₂ -based sputtering target is preferably used for producing a sputtered film having a peak value of transmittance of 96% or more at a wavelength of 500 to 600 nm measured by an ultraviolet visible spectrophotometer. According to the SnO ₂ -based sputtering target of the present invention, a sputtered film having a low film resistance value can be manufactured while securing a high light transmittance in this manner.

Example  One

First, the following three types of raw material powders are prepared.

SnO ₂ Powder: Purity 99.99% (4N), Average particle size 0.7-1.1 μm, Specific surface area 2.0-2.7 m ² / g

Ta ₂ O ₅ Powder: Purity 99.9% (3N), Average particle size 0.6 ~ 0.8μm, Specific surface area 2.0 ~ 3.1m ² / g

Nb ₂ O ₅ powder: Purity 99.9% (3N), average particle diameter 0.6-1.0μm, specific surface area 2.1-2.7m ² / g

Then, the SnO ₂ And powder 96.5% by weight and the Ta ₂ O ₅ powder, 3% by weight, the Nb ₂ O ₅ powder was mixed with 0.5% by weight 21 hours by a ball mill. A polyvinyl alcohol aqueous solution was added to this mixed powder, it filled into the metal mold | die of 400 * 800mm dimension, and it press-molded at the pressure of 800 kg / cm <^2> . After drying this molded object at 80 degreeC for 12 hours, it degreased at 600 degreeC for 4 hours. This degreasing body was baked for 4 hours at the baking temperature of 1600 degreeC in air | atmosphere atmosphere, and the sintered compact was obtained. At this time, both the temperature increase rate and the temperature decrease rate were controlled at 100 ° C / hour. By processing the obtained sintered body, the diameter was 6 inches (152mm), SnO ₂ based sputtering target having a thickness of 5mm in size.

Example  2 to 7 and Comparative example  1 to 5 and 9

A SnO ₂ -based sputtering target was produced in the same manner as in Example 1 except that the raw material powders were mixed at the composition ratios shown in Table 1.

Example  8

A SnO ₂ -based sputtering target was produced in the same manner as in Example 1 except that the raw material powders were mixed at the composition ratios shown in Table 1 and the firing temperature was set to 1550 ° C.

Comparative example  6 and 7

A SnO ₂ -based sputtering target was produced in the same manner as in Example 1 except that the raw material powders were mixed at the composition ratios shown in Table 1 and the firing temperature was set to 1500 ° C.

Comparative example  8

Production of SnO ₂ -based sputtering targets as sintered bodies was attempted in the same manner as in Example 1 except that the raw material powders were mixed at the composition ratios shown in Table 1 and the firing temperature was 1700 ° C. However, since SnO ₂ melted, the shape was broken, and a desired shape could not be obtained.

evaluation

(1)-(3) was evaluated about the sputtering target produced in Examples 1-8 and Comparative Examples 1-7 and 9.

(1) Measurement of relative density

The relative density of each sputtering target was measured by the Archimedes method. At this time, the density of each raw material is SnO ₂ : 6.95g / cm ³ , Ta ₂ O ₅ : 8.74g / cm ³ , Nb ₂ O ₅ : The weighted average density (theoretical density) was computed as 4.47 g / cm <^3> , and the relative density was computed using this weighted average density as 100%. The results were as shown in Table 1.

(2) measurement of film formation speed

Each sputtering target was metal-bonded to the backing plate made of oxygen-free copper. At this time, when the centerline average roughness Ra of the sputtering surface of a sputtering target was measured, it was 0.6 micrometers or less. In addition, when the composition of each sputtering target was analyzed by ICP, it was the same as the composition of the mixed powder used as a raw material. And magnetron sputtering using a DC power supply was performed about the metal-bonded sputtering target on the conditions shown below, and sputter film-forming was carried out on the alkali free glass substrate.

Reach Pressure: 1 × 10 ^-4 Pa

Substrate Temperature: Room Temperature

Argon partial pressure introduced: 0.5Pa

Introduced oxygen flow rate (partial pressure): 0 to 3 sccm (0 to ² × 10 ^-2 Pa)

DC applied power: 300W

Film thickness: about 140nm

Substrate: Alkali-Free Glass

The film formation speed was computed by measuring the thickness of the formed film | membrane by the stylus type surface shape measuring device (Dektak6M, ULVAC Corporation make), and dividing the obtained thickness by film-forming time. The results of the film formation rate at the introduced oxygen flow rate of 0 sccm were as shown in Table 1.

(3) Measurement of membrane resistivity

After sputter film deposition, annealing was performed at 500 ° C. for 1 hour in an air atmosphere. The minimum value of each film specific resistance was measured, and the result as shown in Table 1 was obtained. The specific resistance was measured by a four-probe method using a sheet resistance measuring instrument (MCP-TP06P, manufactured by Diamond Instruments), and the film thickness measured by a stylus type surface shape measuring instrument (Dektak6M, manufactured by ULVAC) on the sheet resistance obtained. Calculated by multiplying.

(4) Measurement of transmittance

For Examples 2 and 4 and Comparative Examples 6 and 7, the transmittance was measured as follows. The transmittance | permeability of the light of wavelength 300-800 nm was measured using the ultraviolet visible spectrophotometer (UV-2550, the Shimadzu Corporation) with respect to the sample of the oxygen partial pressure conditions which the specific resistance value after annealing was minimum. At this time, blank glass was used as a reference. The peak of transmittance | permeability was observed in the wavelength of 500-600 nm with respect to all the samples of Example 2 and 4 and the comparative examples 6 and 7, The peak value of the transmittance was as shown in Table 2.

(5) Evaluation of oxygen flow rate (partial pressure) dependence of specific resistance and transmittance peak value after annealing

The relationship between the specific resistance and transmittance peak value after annealing, and the oxygen flow rate (partial pressure) of the sputtered film obtained using the sputtering targets produced in Example 2 and Comparative Example 6 were as shown in FIG. 1. As can be seen from FIG. 1, the sputtering film obtained using the sputtering target produced in Example 2 in which the baking was performed at 1600 ° C. was obtained using the sputtering target produced in Comparative Example 6 in which the baking was performed at 1500 ° C. FIG. Compared with the sputter film, it is understood that the difference between the introduced oxygen flow rate at which the low specific resistance is obtained and the introduced oxygen flow rate at which the high transmittance is obtained is small, so that a high transmittance can be simultaneously realized under an oxygen partial pressure of which the specific resistance is minimum or close thereto. That is, by sputtering film formation using the sputtering target of this invention, two important performances, a low specific resistance and a high transmittance | permeability, have a wide introduction oxygen flow range, Preferably it is 0.8-3.0sccm or more, More preferably, it is 0.9-2.5 It can be seen that it can be realized simultaneously over the introduced oxygen flow rate range of sccm, more preferably 1.0 to 2.0 sccm, most preferably 1.0 to 1.5 sccm.

TABLE 1

TABLE 2

(6) Evaluation by X-ray Diffraction

X-ray diffraction of the sputtering target having a thickness of 5 mm produced in Examples 4, 8 and Comparative Example 7 was measured under the following conditions using an X-ray diffractometer (MXP3, manufactured by MAC Science). The result as shown in 4 was obtained.

Source: CuKα line (λ = 1.54050 Hz)

Tube voltage: 40kV

Tube Current: 30mA

Range of diffraction angle 2θ: 20 to 40 °

Sampling interval: 0.02 °

Scan Speed: 4 ° C / min

Diving Slit: 1 °

Scattering Slit: 1 °

Receiver Slit: 0.3mm

As shown in FIGS. 2-4, in the X-ray diffraction of the sputtering target of Example 4 and 8 in which baking was performed at 1550 degreeC or more, the diffraction angle in the X-ray diffraction of the sputtering target of the comparative example 7 in which baking was performed at 1500 degreeC The peak attributable to Nb ₂ O ₅ in which 2θ was observed at ₂₂ to ₂₃ degrees and 28 to 29 degrees was not observed. In addition, the X-ray diffraction intensity (Intensity) in the 2θ range is shown in Table 3, in the measurement conditions, the peak attributable to Nb ₂ O ₅ if the maximum value of the X-ray diffraction intensity (Intensity) is less than 100 It can be said that is not substantially observed. From this, within the composition range of the present invention, it is believed that the calcination temperature, for example by haenghaejim at a temperature of at least 1550 ℃, the X-ray diffraction peak due to Nb ₂ O ₅ lapse exceeding 1500 ℃.

TABLE 3

Claims (9)

SnO ₂ as a main component, Nb ₂ O ₅ and Ta ₂ O ₅ containing 1.15 to 10% by mass in a total amount, and the content mass ratio of Nb ₂ O ₅ / Ta ₂ O ₅ is 0.15 to 0.90 To prepare, Sintering the molded body at 1550 to 1650 ° C A method for producing a SnO ₂ -based sputtering target, comprising a. The method of claim 1, The sintered 2-20 hours is carried out, SnO ₂ based process for producing a sputtering target. The method of claim 1, Is, SnO ₂ based method of manufacturing a sputtering target is performed in an atmosphere wherein the oxygen-containing sintering. The method of claim 1, The molded article of the microcrystalline grains further comprises a binder, and the molded article of the microcrystalline grains is dried and then heated so that the binder scatters or disappears prior to the firing, and then the SnO ₂ based sputtering target is produced. Of SnO ₂ as a main component becomes the place and contain 1.15~10% by weight of Nb ₂ O ₅ and Ta ₂ O ₅ with the total amount, Nb ₂ O ₅ / Ta ₂ O ₅ mass ratio of the content is 0.15~0.90, SnO ₂ based As a sputtering target, SnO ₂ -based sputtering target in which the peak resulting from Nb ₂ O ₅ at the diffraction angles 2θ is 22 to ₂₃ ° and 28 to 29 ° is not substantially observed by X-ray diffraction using CuKα rays as the X-ray source. The method of claim 5, SnO _{2 type} sputtering target whose relative density measured by the Archimedes method is 90% or more. The method of claim 5, SnO _{2 type} sputtering target used for manufacture of a sputtering film whose film specific resistance value is 1 * 10 <^{-2> (} ohm) * cm or less. The method of claim 5, SnO _{2 type} sputtering target used for manufacture of the sputtering film whose peak value of the transmittance | permeability of wavelength 500-600 nm light measured by an ultraviolet-visible spectrophotometer is 96% or more. The method of claim 5, The SnO _{2 type} sputtering target manufactured by the manufacturing method in any one of Claims 1-4.

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