KR20070093817A - Ito sintered body, sputtering target, and method for manufacturing sputtering target material - Google Patents

Abstract

An ITO sputtering target material which is used highly efficiently, has a long service life, and has a low aging effect in the sputtering conditions, an ITO sputtering target comprising the ITO sputtering target material, an ITO sintered body suitable for use in the ITO sputtering target material and the ITO sputtering target, and a method for manufacturing a sputtering target material that is suitable for manufacturing the ITO sputtering target material are provided. An ITO(Indium-Tin-Oxide) sintered body(10) satisfies the following relational expression: -30<=100x(Av1-Av2)/Av1<=30, where Av1 denotes a mean value(nm) of maximum diameters of fine particles(12) in In2O3 parent phase grains(11) that present in a central part of the sintered body, and Av2 denotes a mean value(nm) of maximum diameters of fine particles in In2O3 parent phase grains that present in an end portion of the sintered body. An ITO sputtering target comprises the ITO sintered body and a backing plate. As a method for manufacturing a sputtering target material by powder metallurgy, the method includes performing a sintering operation comprising a heating process of heating a molded object to be sintered and a cooling process of cooling the object to be sintered at a temperature decreasing rate of 50 deg.C/hour or more such that both ends of the object to be sintered have a temperature gradient with respect to one object to be sintered that has passed through the heating process.

Description

ITO sintered body, sputtering target, and sputtering target material manufacturing method {ITO SINTERED BODY, SPUTTERING TARGET, AND METHOD FOR MANUFACTURING SPUTTERING TARGET MATERIAL}

1 is a schematic diagram of a microstructure structure of an ITO sintered compact (1).

2 is a schematic view of the microstructure of the ITO sintered body 2.

3 is a schematic cross-sectional view showing the structure of a molding die of Example 1;

4 is a temperature profile diagram of a calcination process of Example 1;

5 is a temperature profile diagram of a calcination process of Example 2. FIG.

Description of the main symbols in the drawings

DESCRIPTION OF SYMBOLS 1 Slurry, 2 molding die, 3 molding lower die, 4 filter, 5 sealing material, 6 water drain hole, 10 ITO sintered compact, 11 In ₂ O ₃ parent grain, 12 : Fine particle, 13: grain boundary, 14: compound phase, 15: fine particle free zone

The present invention relates to an ITO sintered body, a sputtering target material and a sputtering target using the same. More particularly, the present invention relates to ITO sintered body the parts of the In ₂ O ₃ matrix fine ITO sputtering target material and the ITO sputtering target used in which ITO sintered body and it reduces the variation in the form of particles present in the granules.

Moreover, this invention relates to the manufacturing method of a sputtering target material. In more detail, it is related with the manufacturing method suitable for manufacture of the said ITO sputtering target material.

In general, in sputtering using an ITO sputtering target, a portion called an erosion portion of the sputtering surface (surface provided on the sputtering) of the ITO target material is consumed while sputtering is continuously or intermittently performed. Goes. When the consumption of the erosion portion proceeds and a suitable ITO thin film cannot be formed due to the generation of arcing, generation of particles, yellow powder, or the like, the lifetime of the ITO sputtering target is terminated.

Conventionally, various attempts have been made to prevent the occurrence of arcing and particles during sputtering. However, when a simple flat plate-shaped ITO target material is used, the consumption of the ITO target material by sputtering is still less than 30% of the total weight of the target material. It remained, the problem of low use efficiency and short life.

In addition, the oxygen partial pressure dependence and the voltage dependence at the time of sputtering of the ITO target material change over time while the sputtering is continuously or intermittently performed. In order to form a suitable ITO thin film, the sputtering conditions are adjusted each time. There is also a problem that the operation to obtain the condition is complicated and hinders the yield improvement of the film formation.

By the way, when the ITO sintered compact used as an ITO sputtering target material is cut horizontally in the thickness direction, the obtained cut surface is etched, and the microstructure is observed, the state along grain boundaries other than the main crystal grain In ₂ O ₃ and its grain boundary is observed. Compound phase present with or In ₂ O ₃ The fine particle which exists in a mother image may be seen. However, as far as the present inventors know, there is a relationship between such a microstructure of the ITO sintered body and the use efficiency of the ITO target material, the lifespan, the time-dependent change in oxygen partial pressure dependence during sputtering, and the time-dependent change in voltage dependence. It was not examined at all.

For example, about the Al target material and Al alloy target material, the technique of reducing the variation of a crystal grain size is reported by performing a rolling process and a recrystallization process conventionally (refer patent document 1). However, in this report, the inside of the crystal grain of a target material, ie, the fine particle in a parent grain, is not disclosed at all, including the presence. In addition, although this technique targets a metal target material or an alloy target material, since ceramics target materials, such as ITO, are brittle material, plastic processing, such as a rolling process, is impossible and cannot apply this technique.

<Patent Document 1> Japanese Unexamined Patent Publication No. 6-299342

An object of the present invention is to provide an ITO sputtering target material, an ITO sputtering target, and an ITO sintered body suitable for use in these, having high use efficiency, long life, and small change over time of sputtering conditions.

Moreover, this invention also makes it the subject to provide the manufacturing method of a sputtering target material, especially the manufacturing method of the sputtering target material suitable for manufacture of the said ITO sputtering target material.

The present inventors have found that the primary grains of the review with respect to the relation between the time variation of the fine structure of the ITO sintered body target material utilization efficiency, the life, the oxygen partial pressure dependence, the voltage-dependent change with time bar, ITO sintered In ₂ O ₃ matrix lip According to the ITO sintered body which controlled the fluctuation | variation according to the difference of the ITO sintered compact site | part with respect to the fine particle shape which exists in it, ITO sputtering target material and ITO sputtering target which are high in use efficiency, long life, and small with time-dependent change of sputtering conditions are provided. In addition, it was found out that the variation in the form of the fine particles can be controlled by cooling the ends of the fine particles to have a temperature gradient with respect to each object to be baked in the firing process when producing the target material (sintered body). The present invention has been completed.

That is, this invention relates to the following matters.

The ITO sintered compact which concerns on this invention is characterized by satisfy | filling the relationship of the following formula.

-30 ≤ 100 × (Av1-Av2) / Av1 ≤ 30

Wherein, Av1 is In ₂ O ₃ present in the sintered body the central portion A mean value (nm) of the maximum diameter of the matrix granules within the microparticles, Av2 represents the maximum average diameter (nm) of the fine particles within the In ₂ O ₃ matrix granules present in the sintered body end. In addition, the specification of the ITO means a material obtained by adding a tin oxide (SnO ₂₎ 1-35% by weight of a conventional indium oxide (In ₂ O _3).

In one of the preferable aspects of the ITO sintered compact of this invention, it is more preferable that both said Av1 and Av2 are 120 nm or less.

In one of the preferable aspects of the IT0 sintered compact of this invention, it is more preferable that both said Av1 and Av2 are larger than 120 nm.

The ITO sintered compact of this invention can be used suitably as a sputtering target material.

Moreover, the ITO sputtering target which concerns on this invention is provided with the said ITO sintered compact and a backing plate, It is characterized by the above-mentioned.

In addition, the manufacturing method of the sputtering target material which concerns on this invention is a method of manufacturing a sputtering target material by the powder metallurgy method, The both ends of each to-be-baked body after a heating process and a heating process which heat the to-be-baked body after shaping | molding are performed. It is characterized by performing a calcination process including a cooling step of cooling at a temperature lowering rate of 50 ° C./hour or more or less than 50 ° C./hour so as to have a temperature gradient.

Moreover, in the manufacturing method of this sputtering target material, it is preferable that the said sputtering target material consists of ceramics, It is more preferable that it contains indium oxide, It is more preferable that it consists of ITO.

Best Mode for Carrying Out the Invention

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated concretely.

<ITO sintered body, sputtering target material, sputtering target>

The ITO sintered compact of this invention has satisfy | filled the relationship of the following formula.

-30 ≤ 100 × (Av1-Av2) / Av1 ≤ 30

In the above formula, Av1 is the average value (nm) of the maximum diameter of the fine particles in the In ₂ O ₃ parent grain existing in the center of the sintered body, and Av2 is the maximum of the fine particles in the In ₂ O ₃ parent grain existing in the sintered body end. The average value (nm) of a diameter is shown.

Here, the average value of the maximum diameters of the fine particles existing in the In ₂ O ₃ mother grains means that the cut surface obtained by cutting the ITO sintered body horizontally in the thickness direction using a diamond cutter is emerald # 170, # 320, # 800. , # 1500, # 2000, stepwise polishing, and finally buff polishing to finish the mirror surface, and then etching solution at 40 ℃ (nitric acid (60-61% aqueous solution, 1.38 rust nitric acid manufactured by Kanto Kagaku Co., Ltd.) Class 1 product number 28161-03), hydrochloric acid (35.0 to 37.0% aqueous solution, manufactured by Kanto Chemical Co., Ltd., hydrochloric acid rust class 1 product number 18078-01), and water in a volume ratio of HCl: H ₂ 0: HNO ₃ = It is immersed and etched in the ratio of 1: 1: 0.08 for 9 minutes, and it is an arbitrary 2 micrometer x 2 micrometer area | region of a surface which shows, (a compound existing in the state along a grain boundary and a grain boundary, and a free zone defined later) It refers to the average value of the largest diameter of a microparticle observed in the area which does not contain anything).

In addition, the largest diameter of a fine particle shall mean the largest thing in the straight line (diameter) which connects arbitrary two points of the observed fine particle cross section. Observation of fine particles is performed by SEM (scanning electron microscope) (magnification 30,000 times). In ₂ O ₃ The fine particles present in the mother phase are considered to be heterogeneous compounds with In ₂ O ₃ from the SEM image, and are probably assumed to be In ₄ Sn ₃ O ₁₂ . In addition, in the above observation method, the fine particle free zone means In ₂ O ₃ in which fine particles are not observed when SEM observation is performed at a magnification of 3,000 times. It means the region in a mother phase (however, the region of a compound phase which exists in the state along a grain boundary is not included).

In general, by the above-described observation method, the parts of the ITO sintered body cut surface even if the maximum diameter of a plurality of In ₂ O ₃ matrix lip same is observed in (for example, ITO sintered body center, and end), In ₂ O ₃ matrix thereof The shape (size, shape) and dispersion state of the fine particles present in the lip vary depending on each part of the IT0 sintered body.

However, according to the studies by the present inventors, even if the shape and dispersion state of the fine particles present in the In ₂ O ₃ parent grain at each site of the ITO sintered body are different, it is difficult to sputter if the deviation falls within a specific range. On the contrary, it is said that uniformity of the microstructure structure is planned throughout the entire ITO sintered body. When sputtering using this as a target material, the entire sputter surface is sputtered uniformly, so that the use efficiency is improved and the target life is long. At the same time, it has been found that the change over time of the oxygen partial pressure dependence and the change over time of the voltage dependence during sputtering can be suppressed.

That is, if the IT0 sintered body satisfies the above relation and the deviation of the average value (nm) of the maximum diameter of the fine particles in the In ₂ O ₃ parent grains at the center and the end of the sintered body is within the range of ± 30%, Preferably, the following formula −10 ≦ 100 × (Av1−Av2) / Av1 ≦ 10 (where Av1 and Av2 are the same as described above) is satisfied, and In ₂ O at the center and the end of the sintered body _{3 If} the variation of the average value (nm) of the maximum diameter of the fine particles in the parent grains is within a range of ± 10%, uniformity of the microstructure structure is achieved throughout the sintered body, regardless of the difference of the sintered body part. Not only the fine particle size variation but also its dispersion state is uniformized so that sputtering does not interfere. In the ITO sintered compact which has a uniform microstructure structure in this way, generation | occurrence | production of arcing and a particle is expected to be reduced.

On the other hand, if the variation of the individual fine particle forms present in each In ₂ O ₃ mother grain is large and does not satisfy the relationship of the above formula, the microstructure structure is greatly changed by the difference of the target material site. When sputtering this using this ITO sintered compact as a sputtering target material, since a sputtering speed changes according to the structure | tissue of a target material site | part, an erosion part is not sputtered uniformly, the use efficiency of a target material becomes bad, and life span also shortens. In addition, many arcing and particle generation is expected. In this case, not only the variation of the fine particle size but also the dispersion of the dispersed state increases, and as the consumption of the target material by sputtering proceeds, the microstructure of the exposed tissue changes significantly, so that the oxygen partial pressure dependence of the sputtering In addition, it is thought that time-dependent change of voltage dependency is also large.

The ITO sintered compact of this invention which satisfy | fills the relationship of the said Formula contains two preferable aspects. Specifically, (1) In addition to satisfying the relationship of the above formula, and furthermore, the Av1 and Av2 are both 120 nm or less, and (2) In addition to satisfying the relationship of the above formula, the Av1 and Av2 are both 120 nm. It is a bigger sun.

Below, the ITO sintered compact of said (1) and (2) is demonstrated in detail.

ITO sintered compact (1) which is one of the preferable aspects of this invention is an ITO sintered compact in which the said Av1 and Av2 are both 120 nm or less, More preferably, it is the range of 10-100 nm in addition to satisfy | filling the relationship of said formula. In the case where Av1 and Av2 satisfy the relationship of the above formula, and both are 120 nm or less, more preferably within the specific range, regardless of the difference of the ITO sintered body part, the In ₂ O ₃ parent grain Since the present fine particles are small and the dispersion state is also uniform, the entire sputter surface is sputtered uniformly, and the improvement of the use efficiency as a target material can be expected.

The structure of a part of the structure of this ITO sintered compact 1 is shown in FIG. 1 (However, FIG. 1 shows the structure of the ITO sintered compact exaggerated typically for description, and the dimension, ratio, etc. of each component are shown. Unlike real life). Figure and the 1, 10 represents the ITO sintered body (1) in total, the ITO main crystal of In ₂ O ₃ matrix is fine particles 12 into the lip 11 of the sintered body (1) is present, also the grain boundary ( The compound phase 14 exists in the state along 13). In addition, In ₂ O ₃ where the fine particles 12 were not observed The fine particle free zone 15 which is an area | region in the mother phase 11 also exists.

In addition, the ITO sintered compact 2 which is one of the preferable aspects of this invention satisfy | fills the relationship of said Formula, and both said Av1 and Av2 are larger than 120 nm, Preferably they are ITO sintered compact in the range of 150-1000 nm. When Av1 and Av2 satisfy the relationship of the above formula, and both are larger than 120 nm, more preferably, within the specific range, In ₂ O ₃ compared with not satisfying the above condition. The larger the number of fine particles present in the mother grains, the smaller the number thereof becomes, and the less likely to be a starting point of yellow powder and particle generation.

A schematic representation of a part of the structure of the ITO sintered compact 2 is shown in FIG. 2 (However, for the sake of explanation, FIG. 2 is an exaggerated schematic representation of the structure of the ITO sintered compact. Unlike real life). In FIG. 2, 10 represents the ITO sintered compact 2 as a whole, and In ₂ O ₃ which is a main crystal of the ITO sintered compact 2 The fine particle 12 exists in the parent grain 11, and the compound phase 14 exists in the state along the grain boundary 13. In addition, it is fine-particle-free zone (15) region in the fine particles 12 is not observed In ₂ O ₃ matrix lip 11 is also present.

These ITO sintered compacts are subjected to compression molding by adding a binder to the raw material powder as necessary, degreasing the obtained molded article as necessary, and then firing the molded body to obtain a sintered compact, according to a so-called powder metallurgy method, which specifies the firing treatment. It can manufacture by performing under conditions. More specifically, the manufacturing method of the sputtering target material mentioned later can be applied suitably, The detail is described in the following description of the manufacturing method of the sputtering target material.

The said ITO sintered compact can be used suitably as an ITO sputtering target material, after cut | disconnecting to a desired shape by well-known means as needed and grinding etc. In addition, an ITO sputtering target can be obtained by cutting out the said ITO sintered compact as needed, grinding, etc., and joining with the backing plate which is a cooling plate.

The backing plate should just be used as a backing plate of a sputtering target normally, Although it does not specifically limit, The backing plate made from copper or a copper alloy is preferable at the favorable thermal conductivity. Moreover, the shape may also be a well-known thing, and is not specifically limited.

Moreover, joining of an ITO sintered compact and a backing plate can also be performed suitably by a well-known method, Although it does not specifically limit, The method of joining via bonding agents, such as In solder, from a cost and productivity point is mentioned preferably. Specifically, the ITO sintered compact is cut out into a desired shape as necessary, ground as necessary, and then heated to a temperature equal to or higher than the melting point of In, and bonded with the backing plate of the ITO sintered compact while maintaining the temperature. It can be bonded by a method such as applying molten In solder to the surface to be applied, attaching the backing plate to the backing plate, cooling it under pressure, and cooling to room temperature.

<Method for Producing Sputtering Target Material>

The manufacturing method of the sputtering target material of this invention is a method of manufacturing a sputtering target material by the powder metallurgy method, The temperature gradient of the both ends is carried out with respect to the heating process which heats the to-be-baked body after shaping | molding, and per to-be-baked body after a heating process. It is characterized by performing a calcination process including a cooling step of cooling at a temperature lowering rate of 50 ° C./hour or more or less than 50 ° C./hour so that

The material of the sputtering target material which can be manufactured by the manufacturing method of this invention should just be able to apply the powder metallurgy method, It does not specifically limit, Sintered alloy, ceramics, etc. are mentioned. In the point which can demonstrate the effect of this invention more effectively, the thing which plastic processing, such as a rolling process, is impossible, for example, ceramics etc. are mentioned preferably. Especially, what consists of indium oxide is preferable and it is more preferable that it is ITO. This is because the size and dispersed state of the fine particles present in the In ₂ O ₃ mother grains of the ITO sintered compact will affect the production method of the ITO sintered compact, particularly the firing conditions. For example, when firing a fired body after molding in a conventionally known batch type furnace (hereinafter also referred to as a batch furnace), heat distribution in the furnace occurs, so that, for example, the inside of the furnace at a certain temperature Even if it is set, the whole to-be-baked body cannot be heated and cooled uniformly at the temperature, and final heat history differs in the center part and end part of the obtained ITO sintered compact. This difference in thermal history affects the growth of the fine particles present in the In ₂ O ₃ parent grains of the obtained ITO sintered compact, thereby increasing the variation of the shape and dispersion state of the fine particles between the respective portions of the ITO sintered compact. It is thought to be.

Operation other than the said baking process of the manufacturing method of this invention can be performed in accordance with well-known means and conditions normally performed by the powder metallurgy method. For example, a raw material powder (for example, in the case of ITO, indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ )) is mixed in a desired ratio, a binder is added if necessary, compression molding The operation | movement until a molded object (henceforth a to-be-baked body) is obtained and the obtained molded object is degreased as needed can be performed by the well-known means and conditions currently performed.

Specifically, the raw material powder may be calcined and classified as necessary, and the subsequent mixing of the raw material powder can be performed by, for example, a ball mill. Thereafter, the mixed raw material powder is filled into a molding die and compression molded to produce a molded body, and may be degreased under an air atmosphere or an oxygen atmosphere, or the ceramics may be cast as in the slurry casting method described in JP-A-11-228220. A slurry made of mixed raw material powder, ion-exchanged water, and an organic additive is poured into a filter forming mold made of a non-aqueous material for obtaining a molded product by depressurizing and draining moisture from the raw material slurry, and draining the water in the slurry at reduced pressure to form a molded article. You may prepare and dry-degrease this molded object. In addition, you may perform degreasing | molding of a molded object in the continuous furnace mentioned later.

Then, the baking process containing the said specific cooling process is performed to the molded object (fired body) obtained in this way. The firing treatment includes a heating step, a cooling step, and a heat retention step as necessary. Hereinafter, each process is demonstrated in this order.

First, the to-be-baked body (molded body) after shaping | molding is heated by the process heated in a furnace so that the both ends may have a temperature gradient with respect to each to-be-baked body. More specifically, the step of heating while conveying the to-be-baked body is preferably mentioned so that the to-be-baked body passes through two or more adjacent areas set to different temperatures provided in the furnace. By heating in this way, the object to be fired can be sequentially heated and sintered from the end of the conveying direction side, and shrinkage due to sintering is performed sequentially from the end to the object to be fired. Problems are unlikely. In addition, since the bias of the heat distribution is very small compared to the batch furnace, the thermal history of each part in the heating process can be equalized to the same degree regardless of the difference of the part to be baked. The conveying means may be any known means, and is not particularly limited. The conveying means may be a means for mounting the object on the plurality of rollers, rotating the rollers in one direction, and conveying the object, depending on the kind of furnace used. The means which mounts on a belt and moves this belt and conveys is mentioned.

Moreover, when the surface shape seen from the upper side of a to-be-baked body differs in aspect ratios, such as a rectangle, what is necessary is just to mount and convey so that the longer side of a to-be-baked body surface shape may be parallel to a conveyance direction. In addition, in order to make a thermal history more uniform, you may supply to a heating process, the cooling process mentioned later, a thermal insulation process, or any, in the state which mounted the to-be-baked body on the well-known baking board.

The length (length in the length direction) of the conveyance direction side of each area | region in a furnace may be the same as another area | region, and may differ from each area | region, and it can determine suitably according to the magnitude | size of a to-be-baked body, the size of the furnace to be used, the number of the area | regions arrange | positioned, etc. The number of regions to be arranged can be appropriately determined according to the size of the body to be baked and the baking program.

Moreover, compared with the temperature of the area | region adjacent to each other among these, in the said heating process, the temperature of each area | region is normally raised so that it may become high sequentially as it goes to a conveyance direction within the range of 10-500 degreeC normally. The conveyance speed of the to-be-baked body which has been set and passes inside these two or more areas is usually in the range of 1 to 50 mm / min. Moreover, in the said process, the temperature of the region with the lowest temperature is normally room temperature-800 degreeC, and the temperature of the region with the highest temperature is 1400-1600 degreeC normally.

In the heating step, the set temperature of each region is determined by a temperature detection device such as a thermocouple provided at approximately an intermediate point with respect to the length in the longitudinal direction for each region. At this time, it is preferable that the temperature between each temperature detection apparatus provided in the area | region adjacent to each other is adjusted so that it may increase at the ratio of 0.02-11.1 degreeC / mm normally.

In addition, when the sputtering target material to be obtained consists of an ITO sintered compact, it is preferable to introduce oxygen into a furnace and perform the said heating process in oxygen atmosphere from a viewpoint of the density improvement of the obtained ITO sintered compact. The flow rate of oxygen introduced into the furnace is usually in the range of 0.1 to 500 m ³ / hour per 1 m ³ of the furnace. In addition, when oxygen is introduced in the heating step, oxygen may continue to be introduced in an amount within the above range in the cooling step or the warming step described later, or the introduction of oxygen may be stopped to replace the atmosphere in the furnace with air or nitrogen.

Next, the to-be-baked body after passing through the said heating process is cooled by the cooling process which cools so that the both ends may have a temperature gradient with respect to each one. More specifically, the step of cooling while conveying the to-be-baked material is preferably mentioned so that the to-be-baked material passes through two or more adjacent areas set at different temperatures provided in the furnace. The conveying means is the same as that of the heating process mentioned above.

By cooling in this way, the object to be baked can be cooled sequentially from the end of the conveying direction side at the same time, and the bias of the heat distribution is very small compared with the batch path, so that the part to be baked is Regardless of the difference, the final thermal history of each part can be equalized. Therefore, it is thought that the growth of the fine particles existing in the crystal grains (parent granules) of the obtained sintered compact is also about the same, and the variation in the form and dispersion state at each site can be brought within the specific range.

In the said cooling process, the length (length in the length direction) of the conveyance direction side of each area | region may be the same as another area | region, and may differ suitably according to the magnitude | size of a to-be-baked body, the size of the furnace used, the number of the area | regions installed, etc. have. The number of regions to be arranged can be appropriately determined according to the size of the body to be baked and the baking program.

In the said cooling process, the temperature of each area | region of two or more adjoining areas | regions becomes so that it may become low sequentially as it goes to a conveyance direction normally in the range of 10-500 degreeC compared with the temperature of the area | region adjacent to each other among these, respectively. The conveyance speed of the molded article which is set and passes through these two or more regions is usually in the range of 1 to 50 mm / min. Moreover, in the said cooling process, the temperature of the region with the highest temperature is 1400-1600 degreeC, and the temperature of the region with the lowest temperature is room temperature-400 degreeC normally.

In the cooling step, the set temperature of each region is determined by a temperature detection device such as a thermocouple provided at approximately an intermediate point with respect to the length in the longitudinal direction of each region for each region. At this time, it is preferable that the temperature between each temperature detection apparatus provided in the area | region adjacent to each other is set so that it may fall normally at the ratio of 0.02-1.11 degreeC / mm.

In addition, when made of a sputtering target material is ITO sintered body to obtain, with a view to controlling the maximum diameter of the average value of the fine particles present in the primary crystal grains of In ₂ O ₃ matrix granules, of the cooling step, 400 from the maximum temperature It is preferable to adjust the temperature-fall rate of a cooling process by adjusting the conveyance speed of the to-be-baked body at the time of letting the area | region set to the temperature to ° C pass.

Specifically, during the cooling process, when the temperature reduction rate is adjusted to 50 ° C / hour or more, preferably 100 to 300 ° C / hour, more preferably 150 to 300 ° C / hour in the temperature range from the highest temperature to 400 ° C. Since the to-be-baked body after a heating process is rapidly cooled and the growth of the fine particles in the In ₂ O ₃ parent grain is hindered, the average value Av1 of the maximum diameter of the fine particles in the In ₂ O ₃ parent grain present in the center of the sintered compact (nm) and the average value Av2 (nm) of the maximum diameter of the fine particles in the In ₂ O ₃ parent grain present at the end of the sintered body can all be controlled to 120 nm or less, and these values are represented by the following formula -30? An ITO sintered body that satisfies the relationship of (Av1-Av2) / Av1 ≤ 30 can be obtained. Moreover, when the said temperature-fall rate exceeds 300 degreeC / hour, the probability of a crack of a sintered compact will become high and it is unpreferable in production efficiency.

On the other hand, in the cooling process, in the temperature range from the highest temperature to 400 ° C, the temperature-fall rate is adjusted to less than 50 ° C / hour, preferably 20 to 40 ° C / hour, more preferably 25 to 35 ° C / hour. As the material to be cooled after the heating process is slowly cooled, the growth of fine particles in the In ₂ O ₃ parent grains is promoted and coarsened, so that both Av1 (nm) and Av2 (nm) are 120 nm. A larger control can be achieved, and an ITO sintered body whose values satisfy the following expression -30 &lt; = 100 x (Av1-Av2) / Av1 &lt; = 30 can be obtained.

In addition, the temperature-fall rate of the area | region set to the temperature from less than 400 degreeC to room temperature in the said cooling process is not specifically limited. This is because the fine particles in the In ₂ O ₃ mother grain do not substantially grow in such a temperature range. Specifically, the temperature-fall rates of these regions may be appropriately set, and in particular, it is allowed to cool without adjusting the temperature-fall rate and naturally cooled to room temperature.

In the present invention, if necessary, between the heating step and the cooling step, between each heating step when the heating step is performed in multiple stages, and between each cooling step when the cooling step is performed in multiple stages. You can also provide a thermal insulation process. In a heat retention process, the temperature of the area | region of the heating process immediately before or the area | region of a cooling process is maintained. The length, the number, and the like of the region in the thermal insulation step can be appropriately determined according to the size of the to-be-baked body, the size of the furnace to be used, the total number of regions to be arranged, and the like.

In addition, in the ease of temperature-control and temperature-lowering condition control, it is preferable that the said heating process and a cooling process (in the case of a heat retention process, also a heat retention process) are performed in a continuous furnace. Here, a continuous furnace means the furnace which can continuously heat and cool a to-be-baked body, or the furnace which can continuously heat, cool and heat | maintain a to-be-baked body, Specifically, for example, a roller hearth kiln (roller) hearth kiln), pusher kiln, mesh belt kiln, and the like.

In addition, from the viewpoint of minimizing the bias of the temperature distribution in the width direction of the furnace and achieving uniform heating in the width direction portion of the to-be-baked body, the continuous path is provided with heating means in the up and down direction at the boundary of the conveying path of the to-be-baked material. It is preferable, and it is more preferable that it is a roller hearth kiln. A roller hearth kiln is a kind of continuous furnace which can set a preheating zone, a heating zone, a heat insulation zone, a cooling zone, etc. according to the set temperature, and can implement a specific temperature profile. In addition, when a heating means is provided in the up-down direction on the basis of the conveyance path of the to-be-baked body, the thermocouple may be provided up and down similarly, and temperature detection and temperature control may be performed from above and below.

The sintered compact obtained through the above-mentioned baking process is cut out to a desired shape by a well-known means as needed, can be used suitably as a sputtering target material, after grinding and the like.

Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.

EXAMPLE

(Example 1)

<Production of ITO Sputtering Targets>

900 g of indium oxide powder having a specific surface area of 8.07 m ² / g, 100 g of tin oxide powder having a specific surface area of 2.2 m ² / g, 30 g of ion-exchanged water, and a zirconia ball having a diameter of 5 mm were placed in a resin pot for ball mill mixing for 20 hours. Next, 178.3 g of ion-exchanged water and 7.9 g of a polycarboxylic acid dispersant were added and ball milled for 1 hour. After 1 hour, 9.9 g of a wax binder was added, and ball milling was carried out for 19 hours to obtain a slurry.

Next, 0.2 g of an amide defoaming agent was added to the obtained slurry, and degassing was performed under reduced pressure. Solid content concentration of this slurry was 83 weight%. This slurry is formed on the molding die having the structure shown in FIG. 3, specifically, on the lower mold 3 having the drain hole 6, through the filter 4 and the sealing material 5, the molding die 2. The slurry 1 was poured into the recessed part of the shaping | molding die which has this stacked structure, it drained to the drain hole 6 at reduced pressure-760 mmHg, and the molded object of 350 mm x 400 mm x 12 mm was obtained.

After drying the obtained molded article at 25 ℃, Roller Hearth Kiln sent introduced into (an area number 24, the total length of 10,800mm), and the flow of oxygen gas of 100% oxygen concentration in the furnace per 1m ³ flow rate 0.2m ³ / hour in the furnace In addition, the baking process was performed on the conditions shown in Table 1. After the baking treatment, the molded body after baking was taken out of the outlet of the roller hearth kiln, cooled to room temperature, and the ITO sintered compact was obtained. The size of the obtained ITO sintered compact was about 300 mm x 348 mm x 10 mm.

When the molded body is introduced into the roller hearth kiln, the molded body is gradually approached to the inlet of the roller hearth kiln so that the temperature of the molded body, which is a to-be-fired body, does not increase rapidly, and when the mold body is taken out of the roller hearth kiln, the temperature of the molded body after firing The molded body was gradually moved away from the ejection opening of the roller haskiln, so as not to fall sharply.

In addition, in the cooling process of the said baking process, the average temperature-fall rate of the temperature range from the highest temperature to 400 degreeC was 200 degreeC / hour. The temperature profile at this time is shown in FIG.

Based on the four probe method, the specific resistance of the obtained ITO sintered compact was measured by a constant current voltage measuring device (Chisley; SMU236), a measuring stand (Kyowa Riken; K-504RS), and a four probe probe (Kyowa Riken). K89PS150 µ) was used, and it was 1.7 × 10 ^-4 (Ωcm).

Then, the cut surface obtained by cutting | disconnecting the obtained ITO sintered compact by the diamond cutter horizontally in the thickness direction at the position of 5 mm from the upper surface at the time of the sintering is emery paper # 170, # 320, # 800, # 1500, # 2000. Polishing step by step, rotating 90 degrees each using buffing, and finally buff polishing to finish the mirror surface, and then etching solution at 40 ° C (nitric acid (60-61% aqueous solution, manufactured by Kanto Chemical Co., Ltd., 1.38 green nitrate) Article No. 28161-03), hydrochloric acid (35.0 to 37.0% aqueous solution, Kanto Chemical Co., Ltd., chlorine hydrochloric acid No. 1 class No. 18078-01) and water in volume ratio of HCl: H ₂ O: HNO ₃ = 1: 1 : Immersed for 9 minutes in a ratio of 0.08) and etched, and (i) SEM observation was performed at 3,000 times and 30,000 times magnification of the center position of the surface shown and (ii) the length of 30 mm in the width direction and 30 mm in the width direction, respectively, from the corners. JSM-6380A; JE0L agent), and the maximum diameter of the fine particles present in the in ₂ O ₃ portion each matrix The mean value was determined.

As a result, (i) the average value (Av1) of the maximum diameter of the fine particles in the In ₂ O ₃ parent grain present in the center of the ITO sintered compact was 70 nm, and (ii) the fine particles in the In ₂ O ₃ parent grain existing at the edge of the sintered compact. The average value (Av2) of the largest diameter of was 65 nm, and (iii) the variation of the fine particles was 7.1% (= 100 × (Av1-Av2) / Av1). In addition, the In ₂ O ₃ matrix grain size of the ITO sintered body center, and the ends whichever is made uniform within the range of ± 1μm.

Subsequently, the said ITO sintered compact was cut | disconnected to the moderate magnitude | size, and both surfaces were ground by the planar grinder, and the ITO sputtering target material of diameter 152.4mm x thickness 6mm was obtained. The obtained ITO sputtering target material was bonded to the copper backing plate through In solder, and the IT0 sputtering target was produced.

<Evaluation of ITO Sputtering Target>

Using the obtained ITO sputtering target, the following methods evaluated the change of the use efficiency and life of a target material, the time-dependent change of the oxygen partial pressure dependency at the time of sputtering, and the time-dependent change of voltage dependence.

These results are collectively shown in Table 3.

Evaluation of the use efficiency and lifespan of the target material

After the weight of the obtained ITO sputtering target was measured, the ITO sputtering target was sputtered under the following conditions, using a μ arcing monitor (manufactured by Landmark Technology Inc.), an arc detection voltage of 100 V and a large arc energy boundary of 50 mJ. The cumulative arc number is measured from the start of sputtering under conditions of 10 mJ of small and medium arc energy boundary, and when the cumulative arc number reaches 50 times (however, the number of arcings occurring during 5 minutes from the sputtering start (hereinafter, initial stage) The amount of input power (Wh / cm ² ) of the ITO sputtering target material was evaluated.

In addition, the weight (M2) of the ITO sputtering target after sputtering end is measured, and the use efficiency (%) of the ITO sputtering target material is calculated | required by the following formula with the weight (M1) of the ITO sputtering target before the sputtering start measured beforehand. Evaluated.

Target Efficiency (%) = 100 × (M1-M2) / M1

Sputtering  City oxygen Partial pressure  Assessment of Dependency Changes Over Time

Using the obtained ITO sputtering target, presputtering and sputtering were carried out under the following conditions, and the specific resistance (a) (Ωcm) of the ITO film formed immediately after the sputtering was started, and the ITO film formed at 40 Wh / cm ² of the integrated input power 40 Wh / cm ² , respectively. Specific resistance (b) (Ωcm) was respectively measured by ResiTest8308 (Toyo Technica) based on van der Pauw method (However, in order to remove the influence of an initial arc, sputtering was started after 15 minutes of presputtering. ).

The obtained specific resistance measured value was calculated | required as the film specific resistance change rate (%), and the following reference | standard evaluated the change of oxygen partial pressure dependency at the time of sputtering by the following formula | equation.

Membrane resistivity change (%) = 100 × | (a-b) / a |

Evaluation standard

Large: Film resistivity change rate exceeds 20%

Medium: Film resistivity change rate is over 15% to 20%

Small: film resistivity change rate is less than 15%

Sputtering  Evaluation of Voltage-dependent Time-dependent Changes in Time

In the same manner, the time required for sputtering after 15 minutes of presputtering to form an ITO film having a film thickness of 1200 kPa on the substrate is measured immediately after the sputtering start (c) and at the integrated input power 40 Wh / cm ² (d). The measured value obtained by measuring on the conditions of each was obtained, and the voltage dependence change at the time of sputtering was calculated | required as a sputtering rate fall rate (%) by the following formula, and the following reference | standard evaluated.

Sputtering Rate Reduction (%) = 100 × | (c-d) / c |

Evaluation standard

Large: Sputtering rate drop exceeded 20%

Medium: Sputtering rate reduction rate is more than 10%-20% or less

Small: Sputtering rate reduction rate is 10% or less

<Sputtering condition>

Deposition conditions:

Device; DC magnetron sputtering device, exhaust system; Cryopump, rotary pump

Reach vacuum degree; 3.0 × 10 ^-6 Pa

Sputtering pressure; 0.4 Pa (nitrogen equivalent value, Ar pressure),

Oxygen partial pressure; 5 × 10 ^-3 Pa

Input power; 600 W (1.85 W / cm ² )

Substrate temperature; 250 ℃

Board; Glass Substrate (Corning # 1737) Plate Thickness 0.8mm

Film thickness; 1200Å

TABLE 1

(Example 2)

According to the conditions shown in Table 2 and the temperature profile shown in FIG. 5, it is the same as Example 1 except having set the average temperature-fall rate of the temperature range from the highest temperature to 400 degreeC in 30 degreeC / hour during the cooling process of baking treatment. The ITO sintered compact was obtained by the method.

It was 2.0 * 10 <^-4> (ohm * cm) when the specific resistance of the obtained ITO sintered compact was measured by the method similar to Example 1. In addition, when the microstructure of the obtained ITO sintered compact was observed in the same manner as in Example 1, (i) Av1 was 300 nm, (ii) Av2 was 280 nm, and (iii) the variation in the fine particles was 6.7%. Moreover, In ₂ O ₃ of the center part and the edge part of the ITO sintered compact In any case, the mother particle size was uniform in the range of ± 1 μm.

Next, the ITO sputtering target was produced by the method similar to Example 1, and the time-dependent change of the use efficiency and lifetime of a target material, the oxygen partial pressure dependency at the time of sputtering, and the time-dependent change of voltage dependence were evaluated.

The results are shown in Table 3.

TABLE 2

(Comparative Example 1)

An ITO sintered compact was obtained in the same manner as in Example 1 except that the baking treatment was performed in a batch furnace set at the following temperature conditions without using a roller hearth kiln.

200 ℃ → (100 ℃ / hr) → 800 ℃ × 2hr → (200 ℃ / hr) → 1600 ℃ × 8hr → (-200 ℃ / hr) → 400 ℃

It was 1.8 * 10 <^-4> (ohm * cm) when the specific resistance of the obtained ITO sintered compact was measured by the method similar to Example 1. Furthermore, when the microstructure structure of the obtained ITO sintered compact was observed by the method similar to Example 1, (i) Av1 was 70 nm, (ii) Av2 was 30 nm, and (iii) the variation of the microparticles was 57.1%. In addition, In ₂ O ₃ matrix grain size of the ITO sintered body has a central portion and end portions whichever was uniform within a range of ± 1μm.

Next, the ITO sputtering target was produced by the method similar to Example 1, and the time-dependent change of the use efficiency and lifetime of a target material, the oxygen partial pressure dependency at the time of sputtering, and the time-dependent change of voltage dependence were evaluated.

The results are shown in Table 3.

(Comparative Example 2)

The ITO sintered compact was obtained by the method similar to Example 1 except having performed baking process in the batch furnace set to the following temperature conditions without using a roller hearth kiln.

200 ℃ → (100 ℃ / hr) → 800 ℃ × 2hr → (200 ℃ / hr) → 1600 ℃ × 8hr → (-30 ℃ / hr) → 400 ℃

It was 2.2 * 10 <^-4> (ohm * cm) when the specific resistance of the obtained ITO sintered compact was measured by the method similar to Example 1. In addition, when the microstructure structure of the obtained ITO sintered compact was observed by the method similar to Example 1, (i) Av1 was 300 nm, (ii) Av2 was 200 nm, and (iii) the deviation of the fine particle was 33.3%. In addition, In ₂ O ₃ matrix grain size of the sintered body ITO central portion and the ends are whichever was uniform within a range of ± 1μm.

Next, the ITO sputtering target was produced by the method similar to Example 1, and the time-dependent change of the use efficiency and lifetime of a target material, the oxygen partial pressure dependency at the time of sputtering, and the time-dependent change of voltage dependence were evaluated.

The results are shown in Table 3.

TABLE 3

In Table 3, the ITO sputtering target material and the ITO sputtering target obtained from the ITO sintered bodies of Examples 1 and 2 which satisfy the relation of the formula -30 ≤ 100 × (Av1-Av2) / Av1 ≤ 30 have high use efficiency, long life The change in the sputtering conditions over time was small. On the other hand, the ITO sputtering target material and ITO sputtering target obtained from the ITO sintered compacts of the comparative examples 1 and 2 which do not satisfy the relationship of the said formula showed that the use efficiency was low, the lifetime was short, and the time-dependent change of sputtering conditions is large. . This is considered to be because in Comparative Examples 1 and 2, unlike Examples 1 and 2, the variation of the fine particle form in the In ₂ O ₃ mother grains at both ends of the ITO sputtering target material is large.

In the ITO sintered compact of the present invention, the ITO sintered compact is controlled by uniformity of the entire structure including the microstructure by controlling the variation in the form of the fine particles existing in the In ₂ O ₃ parent grains regardless of the difference in the sintered compact site. By using as a sputtering target material, the ITO sputtering target material and ITO sputtering target which are high in use efficiency, long life, and small with time-dependent change of sputtering conditions can be obtained.

Since the ITO sputtering target material and ITO sputtering target of this invention have high use efficiency, long life, and small change with the sputtering conditions with time, the ITO thin film excellent in physical properties can be easily and stably formed into a film with high yield.

Moreover, according to the manufacturing method of the sputtering target material of this invention, the sputtering target material in which the whole structure | tissue which contained the microstructure was made uniform can be obtained. The manufacturing method of this sputtering target material is suitable for manufacture of the said ITO sputtering target material.

Claims (10)

Indium-Tin-0xide (IT0) sintered body characterized by satisfying the relationship of the following formula; -30 ≤ 100 × (Av1-Av2) / Av1 ≤ 30 Wherein, Av1 is In ₂ O ₃ present in the sintered body the central portion The matrix granules (母相粒) mean value (nm) of the maximum diameter of the fine particles within, Av2 represents the maximum average diameter (nm) of the fine particles within the In ₂ O ₃ matrix granules present in the sintered body end. The method of claim 1, ITO sintered compact, characterized in that both Av1 and Av2 are 120 nm or less. The method of claim 1, ITO sintered body, characterized in that both Av1 and Av2 are larger than 120 nm. The method according to any one of claims 1 to 3, ITO sintered compact characterized by being a sputtering target material. An ITO sputtering target provided with the ITO sintered compact as described in any one of Claims 1-3, and a backing plate. A method for producing a sputtering target material by powder metallurgy, comprising: a heating step of heating a to-be-baked body and a temperature drop of 50 ° C / hour or more so that both ends have a temperature gradient with respect to one to-be-baked body after the heating step A firing process including a cooling step of cooling at a rate is performed. A method for producing a sputtering target material, characterized by the above-mentioned. A method for producing a sputtering target material by powder metallurgy, comprising a heating step of heating a to-be-baked body and a temperature gradient of less than 50 ° C / hour so that both ends have a temperature gradient for each of the to-be-baked bodies. A firing process including a cooling step of cooling at a temperature lowering rate is performed. The method of producing a sputtering target material. The method according to claim 6 or 7, The said sputtering target material consists of ceramics, The manufacturing method of the sputtering target material characterized by the above-mentioned. The method according to claim 6 or 7, The said sputtering target material contains indium oxide, The manufacturing method of the sputtering target material characterized by the above-mentioned. The method according to claim 6 or 7, The said sputtering target material consists of ITO, The manufacturing method of the sputtering target material characterized by the above-mentioned.

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