KR20190062155A - Izo target and manufacturing method of the same - Google Patents

Abstract

Provided is an IZO target in which film resistance of a sputter film is not affected by oxygen concentration during sputtering. In the IZO target, In, Sn, and Zn are contained with an atomic ratio to satisfy Zn / (In + Sn + Zn) = 0.030-0.250 and Sn / (In + Sn + Zn) = 0.002-0.080. The remainder of the IZO target consists of O and inevitable impurities. The IZO target has a target structure in which a Sn segregation grain is dispersed with more than 200 nm of a particle diameter containing In, Sn, and O specified by FE-EPMA.

Description

IZO TARGET AND MANUFACTURING METHOD OF THE SAME [0001]

The present invention relates to an indium zinc oxide (IZO) target and a method of manufacturing the same. The present invention also relates to an indium zinc oxide (IZO) target and a film forming method using the same.

A sputtering target made of a sintered body of indium zinc oxide (In ₂ O ₃ -ZnO: generally referred to as IZO) is widely used in many electronic parts such as a transparent conductive thin film and a gas sensor of a liquid crystal display. The IZO film has an advantage in that an etching rate is larger than that of a typical transparent conductive thin film, the generation of fine particles is less, and an amorphous film can be obtained. However, IZO has a problem that the bulk resistivity is higher than that of ITO and also shows a variation in the film resistance. Therefore, in the DC magnetron sputtering process, the discharge during sputtering sometimes becomes unstable.

Patent Document 1 (JP-A-6-234565) discloses that a transparent conductive film having excellent conductivity can be obtained by doping IZO with an element having a valence of 3 or more such as Sn.

Patent Document 2 (International Publication No. 2000/68456) discloses an IZO sputtering target for forming a transparent conductive film capable of stably discharging by sputtering while lowering the bulk resistance value by adding a very small amount of Sn One invention is described. Specifically, an IZO sputtering target for forming a transparent conductive film containing In and Zn oxides as main components, which contains Sn in an amount of 100 to 2000 ppm, is disclosed.

Patent Document 3 (JP-A-2017-014534) discloses that in the sputtering target described in Patent Document 2, it is necessary to polish the surface until the surface of the target tends to be uneven and unevenness is removed. In order to eliminate the stain, it has been proposed to set the Sn content to more than 2000 ppm and less than 20000 ppm (more than 2000 ppm to 20000 ppm).

Patent Document 1: JP-A-6-234565 Patent Document 2: International Publication No. 2000/68456 Patent Document 3: JP-A-2017-014534

However, when the IZO target described in Patent Documents 1 to 3 is used, it has been found that the film resistance of the sputter film tends to depend on the oxygen concentration in the atmosphere at the time of sputtering. More specifically, it was found that the sputtering using these IZO targets tends to significantly increase the film resistance of the sputter film as the oxygen concentration in the atmosphere at the time of sputtering becomes lower. It has also been found that the addition of Sn does not necessarily reduce the bulk resistance. It is desirable that sputtering at a low oxygen concentration and an oxygen-free condition is required depending on an application, so that it is possible to reduce the oxygen concentration dependency of the film resistance. Particularly, since the organic EL, which has recently received attention, is weak against oxygen, it is advantageous to obtain a sputter film having a low film resistance even under a low oxygen concentration, since deposition is required in a state in which oxygen is not introduced.

An object of the present invention is to provide an IZO target that is not affected by the film resistance of the sputter film to the oxygen concentration at the time of sputtering. Another object of the present invention is to provide a method of manufacturing such an IZO target. Another object of the present invention is to provide a film forming method using an IZO target related to the present invention.

The present inventors have conducted extensive studies to solve the above problems and found that an IZO target having a sintered body structure in which Sn flakes containing In and Sn are dispersed in the mother phase of IZO is effective. Such an IZO target can be produced by adding ITO powder to the raw material powder of the IZO target. As a result of film formation using an IZO target having the above-described structure as a sputtering target, it was found that the film resistivity did not fluctuate with a change in the oxygen concentration in the sputter atmosphere. The oxygen concentration in the sputter is often different depending on the intended use, but the fact that the film resistivity does not depend on the oxygen concentration in the sputter atmosphere is advantageous in obtaining a stable quality sputter film.

(In + Sn + Zn) = 0.030 to 0.250 and Sn / (In + Sn + Zn) = 0.002 to 0.25 in terms of atomic ratios of In, Sn and Zn in one aspect. 0.080, and the remainder is O and inevitable impurities. The target structure is an IZO target having a total composition composed of O and inevitable impurities. The target structure containing In, Sn, and O specified in FE-EPMA and having a grain size of 200 nm or more The branch is the IZO target.

In one embodiment, the IZO target related to the present invention contains In, Sn and Zn so as to satisfy Sn / (In + Sn + Zn) = 0.010 to 0.030 in atomic ratio.

In another embodiment, the IZO target related to the present invention contains In, Sn and Zn so as to satisfy Zn / (In + Sn + Zn) = 0.040 to 0.200 in atomic ratio.

In another embodiment of the IZO target related to the present invention, Sn flakes having a grain diameter of 200 nm or more exist in the target structure at a number density of 0.003 / mu m or more.

In another embodiment of the IZO target related to the present invention, Sn flakes having a grain diameter of 1000 nm or more exist in the target structure at a number density of 0.0003 / mu m or more.

The IZO target associated with the present invention is, in another embodiment, a relative density of at least 90%.

In another embodiment of the IZO target related to the present invention, the bulk resistance is not less than 0.3 m? · Cm and less than 7.0 m? · Cm.

In another embodiment of the IZO target related to the present invention, the average grain size of the Sn flakes is 450 nm or more and 9000 nm or less.

In another embodiment of the IZO target related to the present invention, Sn flakes having a particle diameter of 10000 nm or more exist in the target structure at a number density of 0.0002 pieces / 占 퐉 or less.

In another embodiment, the IZO target related to the present invention further contains B so as to satisfy B / (In + Sn + Zn + B) = 0.036 or less in atomic ratio.

In another aspect, the present invention is a method of manufacturing an IZO target according to the present invention, which comprises a step of sintering a mixture of ITO powder, In ₂ O ₃ powder and ZnO powder.

In one embodiment of the IZO target production method related to the present invention, each particle constituting the ITO powder contains In and Sn so as to satisfy 6? In / Sn? 36 in atomic ratio.

In another aspect, the present invention is a method for manufacturing an IZO target according to the present invention, which comprises a step of sintering a mixture of ITO powder, In ₂ O ₃ powder, ZnO powder and B ₂ O ₃ powder.

According to another aspect of the present invention, there is provided a film forming method including a step of sputtering using an IZO target related to the present invention.

In one embodiment of the film forming method related to the present invention, the sputtering process is performed in an atmosphere gas having an oxygen concentration of 0.1 vol% or less.

The IZO target related to the present invention has a characteristic that variation in film resistance obtained with respect to change in oxygen concentration in the sputter atmosphere is small. Therefore, a sputter film of stable quality can be obtained irrespective of the oxygen concentration. The present invention is particularly useful for applications in which film formation without oxygen introduction is required, such as organic EL.

Fig. 1 shows an element mapping image of Example 3. Fig.
Fig. 2 shows an element mapping image of Comparative Example 2. Fig.
Fig. 3 shows an element mapping image after smoothing of the Sn plane analysis result of Example 3. Fig.
Fig. 4 shows an element mapping image after binarization (binarization) of the Sn plane analysis result of Example 3. Fig.

(Total composition)

The IZO target related to the present invention is an IZO target according to an embodiment wherein In, Sn and Zn are atomic ratios of Zn / (In + Sn + Zn) = 0.030 to 0.250 and Sn / (In + Sn + Zn) = 0.002 to 0.080 Satisfactorily, and the remainder is composed of O and inevitable impurities. The total composition refers to the total composition of the sintered body including Sn flakes dispersed in the structure of the sintered body.

The reason why Zn / (In + Sn + Zn) is set to 0.030 or more is that the amount of Zn is in the proper range to obtain a sputter film with good conductivity. Zn / (In + Sn + Zn) is preferably 0.030 or more, and more preferably 0.040 or more. Also, even if Zn / (In + Sn + Zn) is set to 0.250 or less, too much Zn will deteriorate the conductivity of the sputter film. Zn / (In + Sn + Zn) is preferably 0.250 or less, and more preferably 0.200 or less.

The reason for setting Sn / (In + Sn + Zn) to 0.002 or more is that the effect of suppressing the variation of the film resistance against the change of the oxygen concentration in the sputter atmosphere and the decrease of the bulk resistance is exhibited. Sn / (In + Sn + Zn) is preferably 0.002 or more, more preferably 0.005 or more, and further preferably 0.010 or more. The reason why Sn / (In + Sn + Zn) is set to 0.080 or less is that when the amount is more than the above value, the density of the sintered body becomes too low and the bulk resistance tends to be high and adverse effects on the sputter . Sn / (In + Sn + Zn) is preferably 0.065 or less, more preferably 0.060 or less, and further preferably 0.030 or less.

Unavoidable impurities are those which are present in raw materials or are inevitably incorporated in the production process and are unnecessary in the beginning, but are trace amounts and allowable impurities because they have no significant effect on the properties of the sintered body.

In one embodiment, the IZO target related to the present invention further contains B such that B / (In + Sn + Zn + B) is 0.036 or less in atomic ratio. B is derived, for example, from B ₂ O ₃ . Since B ₂ O ₃ has a low melting point of 450 ° C, a liquid phase is generated in the sintered body during sintering, so that the sinterability can be improved and the density can be increased. B / (In + Sn + Zn + B) = (B + In + Sn + Zn + B) is preferably 0.004 or more in order to exhibit superior sinterability- 0.036 or less.

(2. Sn abrasive)

An IZO target related to the present invention is a composite oxide of indium oxide (In ₂ O ₃ ) and indium and zinc (Zn _k In ₂ O _{k +3} , k = 2 to 7 (k is an integer)), And a Sn sintered body containing In, Sn and O and having a grain diameter of 200 nm or more dispersed therein. One or both oxides of indium oxide and zinc oxide may be contained in the parent phase. When the sputtering target having the sintered body structure in which the Sn flakes having a particle size of 200 nm or more is dispersed in the mother phase is used, the dependence of the sputter film on the oxygen concentration in the sputter atmosphere is lowered. Therefore, a sputter film having a stable film resistivity can be obtained even if the oxygen concentration in the sputter atmosphere changes depending on the application.

In order to exhibit the effect of improving the conductivity and suppressing the fluctuation of the film resistance against the oxygen concentration change in the sputter atmosphere, it is preferable that the Sn flakes having a grain diameter of 200 nm or more exist in the sintered body structure at a number density of 0.003 / Preferably, it is present in the sintered body structure with a number density of 0.0045 / mu m < 2 > or more, more preferably in the sintered body structure with a number density of 0.01 / mu m or more. However, the number density of the particle size of Sn piece seokrip than 200nm is too high, as compared to when a Sn atom concentration of target are the same, because the Sn concentration of the individual Sn piece seokrip decreased, Sn is diffused by the addition as SnO ₂ , And there is a possibility that the original sputter characteristics may not be obtained well. Here, the Sn flakes having a grain diameter of 200 nm or more are preferably present in the sintered body structure at a number density of 0.1 / mu m < 2 > or less, more preferably 0.08 / It is more preferable that the sintered body exists in the sintered body structure at a number density of not more than 1 / mu m < 2 >.

In order to exhibit the effect of improving the conductivity and suppressing the fluctuation of the film resistance against the oxygen concentration change in the sputter atmosphere, the Sn flakes having a particle diameter of 1000 nm or more are present in the sintered body structure at a number density of 0.0003 / And is preferably present in the sintered body structure at a number density of not less than 0.001 per square micrometer, more preferably in the sintered body structure with a number density of not less than 0.003 per square micrometer. However, if the number density of the Sn flakes having a grain diameter of 1000 nm or more is too high, the sinterability is lowered and the density of the sintered body is lowered, which may increase the bulk resistance or cause fine particles. Here, the Sn flakes having a grain diameter of 1000 nm or more are preferably present in the sintered body structure with a number density of 0.03 / mu m < 2 > or less, more preferably present in the sintered body structure with a number density of 0.026 / It is more preferable that the sintered body exists in the sintered body structure at a number density of not more than 1 / mu m < 2 >.

It is preferable that the Sn flakes having a particle diameter of 10000 nm or more exist in the sintered body structure at a number density of 0.0002 / mu m < 2 > or less in view of the possibility of causing an arc discharge in an excessive Sn flakes, mu] m < 2 > or less, more preferably in the sintered body structure with a number density of 0.00005 / mu m < 2 > or less.

The average particle diameter of Sn flakes is preferably 450 nm or more, more preferably 800 nm or more, and more preferably 900 nm or more in order to exhibit the effect of suppressing the fluctuation of the film resistance against the oxygen concentration change in the sputter atmosphere . The average size of the Sn flakes is preferably 9000 nm or less, more preferably 6000 nm or less, and more preferably 3,000 nm or less because the bulk resistance may increase and may cause arc discharge.

In the present invention, the particle diameter and the number density of the Sn flakes are measured by the following methods. As the measuring instrument, FE-EPMA (Field Emission Electron Probe Micro Analyzer) is used. In the examples, JXA-8500 F (FE-EPMA manufactured by Japan Electronics) was used.

Measurement sample: The sputtering target is cut vertically to the sputter surface to polish the end face by mirror-polishing, and a half thickness portion is observed.

Observation method: Using the surface analysis function attached to the FE-EPMA, the surface analysis is performed under the following conditions.

Acceleration voltage: 15.0 kV

Radiation current: 1.0 to 2.5 × 10 ^-7 A

· Magnification: 2000 times

· Measurement method: Beam scan

· Beam diameter (㎛): 0

· Measurement time (ms): 5

· Total: 1

· Measurement elements and spectroscopic crystals: In (PETH), Zn (LIFH), Sn (PETH), O (LDE1)

Measurement field (per field of view): 50 탆 x 50 탆

· Pixels: 256 × 256

The surface analysis is performed in the above order, and the element mapping image is displayed in gray scale to obtain measurement data of FIG. 1 (Example 3) or FIG. 2 (Comparative Example 2). The Lv can be operated manually, but the Lv that is calculated automatically by the machine is used as it is. In Example 3, the portion where Sn is segregated in the form of coarse grains (the lightest portion on the element mapping of Sn) can be seen, whereas in Comparative Example 4, segregation of the assembled shape can not be seen. In Comparative Example 4, it is considered that the reason why Sn flakes are not observed is that when SnO ₂ powder is added as a raw material, Sn is diffused into the In ₂ O ₃ particles to have a concentration lower than the detection limit of FE-EPMA . On the other hand, although not intended that the invention be limited, and considering that the tank for the addition of ITO powder, Sn win estimated for the cause it does not spread, but depends on the driving force of the diffusion gradient, SnO ₂ powder and In the ITO powder, it can be considered that since the Sn concentration of ITO powder is low, Sn does not diffuse well around the ITO powder.

From the grayscale phase of the obtained Sn, the grain size of the Sn flakes and the number density of the Sn flakes are measured using the particle measuring function. The following is the procedure of the analysis software attached to JXA-8500F, but the same image processing software may be used. First, a smoothing filter is executed from the filter item. An example of Embodiment 3 is shown in Fig. Then, binarization is performed. The threshold value in the binarization is manually set as a threshold value so that the shape of the Sn flakes in the surface analysis can be included in an adequate manner. However, in order to accommodate relatively large Sn flakes in the grayscale phase, . An example of Embodiment 3 is shown in Fig.

Thereafter, labeling of the binary image is performed. In the software, the selection items of the labeling process are "3 connection" and "do not label outer particles". Subsequently, the labeling phase is measured, and the circle equivalent diameter of each Sn flakes is mechanically calculated. The number of particles present in the measurement field of 2500 mu m was determined by counting the number of particles having a particle diameter of 200 nm or more, 1000 nm or more, and 10000 nm or more as the particle diameter of the Sn flakes as the circle equivalent diameter of each Sn flakes, Obtain the number density (탆 / ㎡) by dividing by visual field area. The average particle diameter of the Sn flakes is obtained from the mechanically calculated diameter of the circle equivalent of each Sn flakes. The above procedure is carried out in a measurement visual field of 5 or more, and the average value is used as a measurement result.

(3. Bulk resistivity)

The IZO target associated with one embodiment of the present invention can significantly reduce the bulk resistivity as compared to the conventional IZO target due to the fact that the Sn flakes are dispersed throughout the structure. Specifically, the IZO target associated with the present invention, in one embodiment, may have a bulk resistivity of less than 7.0 m? · Cm. The bulk resistivity of the IZO target related to the present invention is preferably 3.0 m? · Cm or less, and more preferably 2.0 m? · Cm or less. There is no limitation on the lower limit of the bulk resistivity, but from the material limit of IZO, the bulk resistivity of the IZO target related to the present invention is generally 0.3 m? · Cm or more, and typically 0.5 m? · Cm or more.

In the present invention, the bulk resistivity of the target is measured by a four-probe method using a resistivity meter. On the surface of the sintered body, there is a denatured layer having a small amount of Zn. Therefore, the sintered body is ground to 0.5 mm and finishing up to # 400 with a polishing paper. In the examples, the following devices were used.

Resistivity meter: Model FELL-TC-100-SB-Σ5 + (manufactured by NIPPO SES Co., Ltd.)

Measuring jig RG-5

(4. Relative density)

The higher relative density of the target is preferable for carrying out stable sputtering with less arc discharge. The IZO target associated with the present invention, in one embodiment, has a relative density of at least 90%. The relative density is preferably 92% or more, more preferably 95% or more, and further preferably 96% or more, for example, 90 to 99%. The relative density can be determined by the ratio of the Archimedes density to the reference density determined by the composition.

Here, the reference density is obtained by analyzing the components of the sputtering target, converting the atomic ratios (At%) of In and Zn and Sn and B to the total of 100 at% of In and Zn, Sn and B thus obtained (Weight%), and the single density of In ₂ O ₃ , ZnO, SnO _2, and B ₂ O ₃ . Specifically, the group density of the collective density of _{In 2 O 3 7.18 (g /} ㎤), ZnO 5.61 (g / ㎤), the collective density of _{SnO 2 6.95 (g / ㎤)} , B 2 O 3 groups density of 1.85, a weight ratio of in ₂ O ₃ W _In2O3 (% by weight), the weight ratio of ZnO W _ZnO (% by weight), the weight ratio of SnO ₂ W _SnO2 (% by weight), B ₂ O ₃ weight ratio of the W _B2O3 of And the reference density (g / cm 3) is calculated as (7.18 x W In _{2 O 3} + 5.61 x W _ZnO + 6.95 x W _{SnO 2} + 1.85 x W _{B 2 O 3} ) / 100. However, when B is not added, W _{B2O3 is set} to 0 and it is calculated.

This relative density is based on a reference density calculated on the assumption that the sputtering target is a mixture of In ₂ O ₃ and ZnO and SnO _2. The actual value of the density of the target sputtering target may be higher than the reference density In this regard, the relative density referred to herein may exceed 100%.

(Recipe 5)

Next, preferred examples of a method of manufacturing an IZO target related to the present invention will be described in order.

(5-1 Preparation of ITO powder)

First, a powder of an oxide sintered body (ITO powder) composed of Sn, In, O and unavoidable impurities is prepared. The ITO powder can be obtained by preparing an ITO sintered body by a known method and pulverizing the ITO sintered body. Alternatively, a powder mixture of In ₂ O ₃ and SnO ₂ may be sintered (referred to as calcination) and pulverized to facilitate pulverization.

The ITO powder is finally the raw material of the Sn flakes described above in the sintered body. As to the composition of each particle constituting the ITO powder, the atomic ratio of In and Sn is preferably 6? In / Sn, more preferably 7? In / Sn, and more preferably 9? In / Sn is more preferred. The ITO powder preferably has an In / Sn? Atomic ratio of In / Sn? 25, more preferably an In / Sn? 25 atomic ratio of In and Sn? Is more preferable.

The ITO sintered body can be manufactured by pulverizing and mixing SnO ₂ powder and In ₂ O ₃ powder at a predetermined blending ratio and then sintering. It is preferable that the SnO ₂ powder and the In ₂ O ₃ powder to be used as raw materials have a high purity, for example, a purity of 99 mass% or more, and more preferably 99.9 mass% or more, from the viewpoint of preventing unexpected failure. The average particle diameter of the raw material powder may be, for example, 0.5 to 2.5 占 퐉. Here, when referring to the average particle diameter of the powder in the present specification, it refers to the median diameter (D50) when the cumulative distribution of particle sizes is obtained on the basis of volume by the laser diffraction / scattering method. There are various methods of grinding and mixing, but wet grinding mixing using a wet medium stirring mill such as a bead mill can be preferably used. In the case of wet grinding mixing, the uniformity of the slurry may be increased by adding a dispersant as appropriate. It may be a method capable of realizing the effect of uniform mixing of the raw materials by any other method.

The mixed powder obtained after the pulverization and mixing is subjected to press forming. The press molding is carried out by filling the mixed powder into a mold and holding the pressure of 30 to 60 MPa for 1 to 3 minutes, for example. Prior to press forming, granulation may be carried out as necessary. By improving the fluidity of the powder by assembly, the powder can be homogeneously filled into the mold at the time of press molding in the next step to obtain a homogeneous molded body. There are various methods of assembling, but there is a method using a spray dryer (spray dryer) as one of methods for obtaining granulated powder suitable for press forming. Further, a binder such as polyvinyl alcohol (PVA) may be added to the slurry to be contained in the granulated powder to improve the strength of the molded product. Alternatively, cold isostatic pressing (CIP) may be performed after press forming.

The sintering of the molded body can be carried out in an oxygen atmosphere using an electric furnace. The sintering temperature is preferably 1300 to 1600 占 폚. In order to obtain a high-density sintered body, it is preferable that the sintering temperature is 1300 DEG C or higher. From the viewpoint of preventing the sintering density from being lowered due to the volatilization of tin oxide or the difference in the composition thereof, the sintering temperature is preferably 1600 캜 or lower. When the molded article contains a binder, the binder removal step may be introduced as necessary during the temperature increase to the sintering temperature.

The holding time at the sintering temperature is appropriately selected according to the size of the compact, but if the time is shorter than 5 hours, the sintering does not proceed sufficiently and the density of the sintered body is not sufficiently high or the sintered body is warped. Even if the retention time exceeds 30 hours, waste that requires unnecessary energy and time is generated, which is not preferable for production.

The obtained ITO sintered body is pulverized to obtain an ITO powder. Examples of the pulverizing method include kneading a mortar and a mortar, a hammer mill and a pot mill, and among them, a pot mill is preferable from the viewpoint of productivity. In addition, it is more preferable to use a wet bead mill or the like more carefully. Sieve to remove coarse particles of ITO powder. For example, a sieve having a sieve size of 150 mu m or less can be used. The average particle diameter (D50) of the ITO powder after being sieved is preferably 10 mu m or less, more preferably 5 mu m or less. The average particle diameter of the ITO powder before mixing with the In ₂ O ₃ powder and the ZnO powder is preferably 0.4 μm or more, and more preferably 0.9 μm or more.

(5-2 Production of IZO target)

The IZO targets related to the present invention are obtained by grinding the In ₂ O ₃ powder, the ZnO powder and the ITO powder obtained above in such a manner that the Zn / (In + Sn + Zn) and Sn / (In + Sn + Zn) Mixing, and sintering. If necessary, a B ₂ O ₃ powder may be added. Lt; / RTI > The specific sequence will be described as an example. First, In ₂ O ₃ powder, ZnO powder, and B ₂ O ₃ powder as required are weighed at a predetermined blending ratio, followed by pulverizing and mixing. In order to uniformly mix the ITO powder as fine as possible without mixing, it is preferred to mix the In ₂ O ₃ powder, ZnO powder and B ₂ O ₃ powder as required, Do. The In ₂ O ₃ powder, the ZnO powder and the B ₂ O ₃ powder to be added as the raw material, which have high purity, for example, a purity of 99 mass% or more, and more than 99.9 mass% . As a mixing method, a wet grinding mixing method using a wet medium stirring mill such as a bead mill can be mentioned. In the case of wet pulverization and mixing, a dispersant may be appropriately added to increase the uniformity of the slurry. It may be a method capable of realizing the effect of uniform mixing of the raw materials by other methods.

In order to improve the sinterability, the mixed powder after the fine pulverization and mixing preferably has an average particle diameter of 2 탆 or less, more preferably 1.5 탆 or less. The average particle diameter of the mixed powder after the pulverization and mixing is preferably 0.3 mu m or more, more preferably 0.5 mu m or more because the amount of contamination from beads and the like increases when crushed too much. The above is the average particle diameter including the ITO powder.

Press molding is performed on the mixed powder after the fine pulverization and mixing. The press molding is performed by filling the mixed powder into a metal mold and holding the pressure of 30 to 60 MPa for 1 to 3 minutes, for example. The compact obtained by press molding may be further pressurized to 140 to 200 MPa by a hydrostatic pressure device (CIP). As a result, a more uniform and dense molded body can be obtained.

Prior to press forming, the assembly may be carried out if necessary. By improving the fluidity of the powder by assembly, the powder can be uniformly filled into the mold at the time of press molding in the next step, and a homogeneous molded body can be obtained. There are various methods of assembling, but there is a method using a spray dryer (spray dryer) as one of methods for obtaining granulated powder suitable for press forming. Further, a binder such as polyvinyl alcohol (PVA) may be added to the slurry to be contained in the granulated powder to improve the strength of the molded product.

The sintering of the molded body can be carried out in an oxygen atmosphere using an electric furnace. The sintering temperature is preferably 1300 to 1500 占 폚. In order to obtain a high-density sintered body, it is preferable that the sintering temperature is 1300 DEG C or higher. From the viewpoint of preventing reduction in sintering density or difference in composition due to volatilization of zinc oxide, the sintering temperature is preferably 1500 캜 or lower. When the molded article contains a binder, the binder removal step may be introduced as necessary during the temperature increase to the sintering temperature.

The holding time at the sintering temperature is appropriately selected according to the size of the compact, but if it is shorter than 5 hours, the sintering does not proceed sufficiently and the density of the sintered body does not become sufficiently high, or the sintered body is bent. Even if the holding time exceeds 30 hours, waste which requires unnecessary energy and time is generated, which is not preferable in production.

The thus-obtained IZO sintered body can be processed into a desired shape by a processing machine such as a plane grinder, a cylindrical grinder, or a machining process to produce a sputtering target. The shape of the sputtering target is not particularly limited. For example, it may be a disk shape, a rectangular shape, a cylindrical shape, or the like. The sputtering target may be bonded to the backing plate and the bonding material as needed.

(6th Tabernacle)

In one aspect, the present invention provides a deposition method comprising sputtering using an IZO target associated with the present invention. The IZO target related to the present invention has a characteristic that variation in film resistance obtained with respect to change in oxygen concentration in the sputter atmosphere is small. Therefore, by using the IZO target related to the present invention, it is possible to obtain a stable quality sputter film regardless of the oxygen concentration. In one embodiment, the oxygen concentration in the atmosphere gas at the time of sputtering is 2 vol% or less. In another embodiment, the oxygen concentration in the atmosphere gas at the time of sputtering is 1 vol% or less. In another embodiment, the oxygen concentration in the atmosphere gas at the time of sputtering is 0.5 vol% or less. In another embodiment, the oxygen concentration in the atmosphere gas at the time of sputtering is 0.1 vol% or less. In another embodiment, the oxygen concentration in the atmospheric gas at the time of sputtering is 0 vol%. As the atmospheric gas at the time of sputtering, a mixed gas of Ar and oxygen can be mentioned.

Example

Embodiments of the present invention will now be described in conjunction with comparative examples, which are provided for a better understanding of the invention and its advantages and are not intended to be limiting.

<1. Preparation of ITO powder>

SnO ₂ powder and In ₂ O ₃ powder were mixed with SnO ₂ : In ₂ O ₃ = 10: 90 (Example 16: SnO ₂ : In ₂ O ₃ = 15: 80, Example 17: SnO ₂ : In ₂ O ₃ = 5: 95), followed by wet milling (using ZrO ₂ beads). Polyvinyl alcohol (PVA) was added as a binder to the slurry obtained by wet pulverization and mixing to obtain granulated powder. The granulated powder was press-molded at 280 MPa x 20 mmt at 30 MPa and sintered at 1500 DEG C for 20 hours in an electric furnace in an oxygen atmosphere to produce an ITO sintered body. The obtained ITO sintered body was pulverized with a mortar and pestle, pulverized using a pot mill, wet milled with a ball mill, and sieved to a size of 150 mu m to obtain an ITO powder. The average particle diameter of the ITO powder was adjusted by sieving according to the test number.

<2. Preparation of sintered body &gt;

In ₂ O ₃ powder, ZnO powder, SnO ₂ powder and B ₂ O ₃ powder were prepared in accordance with the test numbers listed in Table 1-1. Then, these were pulverized and mixed by wet pulverization (using ZrO ₂ beads). Five minutes before the stop of the pulverization and mixing, the ITO powder prepared in advance was added to the metal atomic ratio finally shown in Table 1-1. The average particle diameter of the slurry (mixed powder) after the pulverization and mixing was in the range of 0.3 to 0.8 mu m in any test example. PVA was added to the slurry after the pulverization and mixing, and the granulation was carried out to obtain granulated powder. In the test examples in which "Prestressing" is indicated in the table, the In ₂ O ₃ powder, the ZnO powder and the ITO powder were mixed before being pulverized so as to have the metal atom ratios shown in Table 1-1, At room temperature for 5 hours in air, and the mixture was wet milled in a ball mill to a range of 0.3 to 0.8 mu m in average particle size. PVA was added to the obtained slurry, and the mixture was assembled to obtain a granulated powder.

Thereafter, in each of the test examples, the granulated powder was press-molded at 30 MPa to 280 mm x 20 mmt, pressed with cold isostatic press at 140 MPa, and sintered at 1400 캜 for 10 hours in an atmospheric furnace. The analysis of the composition of the sintered body confirmed that the blending ratio of the raw powder was the same.

The average particle diameter of the powder refers to the median diameter (D50) when the cumulative distribution of particle sizes is obtained on the basis of volume by laser diffraction / scattering method using LA-960 manufactured by Horiba Seisakusho Co., Ltd.

<3. Average grain diameter of Sn flakes>

With respect to the sintered bodies relating to the respective test examples obtained by the above-mentioned production method, the average grain diameter of Sn flakes dispersed in the structure was measured by the above-mentioned method. The results are shown in Table 1-2.

<4. Numerical density of Sn flakes>

With respect to the sintered bodies related to the respective test examples obtained by the above-mentioned production method, the number density of Sn flakes dispersed in the structure was measured by the above-mentioned method. The results are shown in Table 1-2.

<5. Bulk resistivity>

With respect to the sintered bodies related to the respective test examples obtained by the above-mentioned production method, the bulk resistivity was measured at room temperature by the 4-probe method using the following apparatus.

Resistivity meter: Model FELL-TC-100-SB-Σ5 + (manufactured by NIPPO SES Co., Ltd.)

Measuring jig: RG-5

The results are shown in Table 1-2.

<6. Relative density>

The densities of the sintered bodies related to the respective test examples obtained by the above-mentioned production method were measured by the Archimedes method, and the ratio (%) to the reference density determined by the composition was determined to be the relative density.

<7. Sputtering test>

The sintered body related to each test example obtained by the above-mentioned manufacturing method was machined and finished with a disk-shaped sputtering target having a diameter of 8 inches and a thickness of 5 mm. The cylindrical shape was finished by cylindrical grinding and lathe machining. Then, using this sputtering target, sputtering was performed. The sputter conditions were set as follows. The sputtering test was carried out twice with varying oxygen concentration in the atmosphere. Further, substrate heating at the time of sputtering and annealing after sputtering were not performed.

Sputter power: 1 W / c㎡

Gas pressure: 0.5 Pa (abs)

Atmosphere: (1) Ar: gas pressure of 0.5 Pa (abs) containing 0 vol% of oxygen

(2) Ar: gas pressure of 0.5 Pa (abs) containing 2 vol%

Thickness: 1000 Å

The film resistivity of the resultant sputter film was measured by the 4-probe method using a FELL-TC-100-SB-Σ5 + thin film resistivity measuring instrument manufactured by NIPPON K.K. The results are shown in Table 1-2.

[Table 1-1]

[Table 1-2]

Comparative Example 4 and Comparative Example 5 were examples in which neither SnO ₂ nor ITO was added to the raw material, and the film resistance largely fluctuated with respect to oxygen concentration change in the sputter atmosphere.

In Comparative Examples 1 to 3, SnO ₂ was added to the raw material. The variation of the film resistance against the oxygen concentration change in the sputter atmosphere was large and the bulk resistivity was large. The addition of SnO ₂ did not appear to directly affect the decrease in bulk resistance.

Examples 1 to 21 are examples in which ITO is added to a raw material. The bulk resistivity was lowered in view of the fact that the size of the Sn flakes that were dispersed in the composition and the target structure was appropriate. Also, the variation of the membrane resistivity with respect to the oxygen concentration change in the sputter atmosphere was small.

In Example 18, the relative density was low and the bulk resistivity was large as compared with the other examples because the ratio of Sn occupying the entire composition of the target was large. In addition, the bulk resistivity of Example 19 was larger than that of the other Examples in view of the fact that the average grain size of Sn flakes dispersed in the target structure was large.

Claims (15)

(In + Sn + Zn) = 0.030 to 0.250 and Sn / (In + Sn + Zn) = 0.002 to 0.080 in terms of atomic ratio and the remaining part is composed of O and unavoidable impurities And an IZO target having an aggregate of Sn particles having a particle diameter of 200 nm or more containing In, Sn, and O as specified in FE-EPMA is dispersed. The method according to claim 1,
An IZO target containing In, Sn and Zn in an atomic ratio satisfying Sn / (In + Sn + Zn) = 0.010 to 0.030. 3. The method according to claim 1 or 2,
An IZO target containing In, Sn and Zn in an atomic ratio satisfying Zn / (In + Sn + Zn) = 0.040 to 0.200. 4. The method according to any one of claims 1 to 3,
An IZO target in which a Sn grain with a grain diameter of 200 nm or more is present in the target structure at a number density of 0.003 / μ m 2 or more. 5. The method according to any one of claims 1 to 4,
An IZO target in which the Sn flakes having a particle diameter of 1000 nm or more are present in the target structure at a number density of 0.0003 / μ m 2 or more. 6. The method according to any one of claims 1 to 5,
IZO targets with relative densities of more than 90%. 7. The method according to any one of claims 1 to 6,
An IZO target with a bulk resistance of 0.3 mΩ · cm to 7.0 mΩ · cm. 8. The method according to any one of claims 1 to 7,
Wherein said Sn flakes have an average particle diameter of 450 nm or more and 9000 nm or less. 9. The method according to any one of claims 1 to 8,
An IZO target in which Sn flakes having a particle diameter of 10000 nm or more are present in the target structure at a number density of 0.0002 / μ m 2 or less. 10. The method according to any one of claims 1 to 9,
B in an atomic ratio satisfying B / (In + Sn + Zn + B) = 0.036 or less. 11. The method according to any one of claims 1 to 10,
And sintering a mixture of ITO powder, In ₂ O ₃ powder and ZnO powder. 12. The method of claim 11,
Wherein each particle constituting the ITO powder contains In and Sn so as to satisfy an atomic ratio of 6? In / Sn? 36. 11. The method of claim 10,
And sintering a mixture of ITO powder, In ₂ O ₃ powder, ZnO powder and B ₂ O ₃ powder. A method for forming a film comprising sputtering using the IZO target according to any one of claims 1 to 10. 15. The method of claim 14,
Wherein the step of sputtering is performed in an atmospheric gas having an oxygen concentration of 0.1 vol% or less.

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