JP5685428B2 - IGZO sintered body and manufacturing method thereof - Google Patents

Description

  The present invention relates to an IGZO sintered body and a method for producing the same.

IGZO (InGaZnO ₄ ) is an oxide semiconductor made of indium oxide, gallium oxide, and zinc oxide, and is a transparent oxide semiconductor that has been attracting attention as a material for TFT channel layers for driving electronic paper, liquid crystal panels, and organic EL. It is a kind. The IGZO sintered body is used as a target material for forming a transparent electrode, a transparent oxide semiconductor, or the like by sputtering.

As such a target material, for example, in Patent Document 1, a mixed powder containing indium oxide powder, gallium oxide powder, and zinc oxide powder is used as a raw material, and this raw material is mixed and pulverized by a wet medium stirring mill to obtain a specific surface area. An IGZO sputtering target obtained by increasing the specific surface area of the entire mixed powder by 1.0 to 3.0 m ² / g, then forming the raw material, and firing it in an oxygen atmosphere at a temperature of 1250 to 1450 ° C. Have been described.

JP 2008-144246 A

However, as described above, when an IGZO (InGaZnO ₄ ) sintered body is obtained by firing, a surface-modified layer containing In ₂ Ga ₂ Zn ₁ O ₇ is generated. That is, at the time of firing, zinc oxide is first vaporized and scattered from the surface of IGZO exposed to high temperature, and the crystal structure is disturbed. Then, the indium oxide that has been easily scattered is vaporized and scattered. In this way, a surface altered layer is generated.

  Such a surface-affected layer is not a desired IGZO and cannot be used as a target material. For this reason, the sintered IGZO sintered body becomes a target material as a product only after the surface altered layer is scraped off. Since the raw material of IGZO is expensive, it is desirable in terms of manufacturing cost to prevent the generation of a surface-modified layer as much as possible.

  An object of the present invention is to provide an IGZO sintered body that has as few surface deteriorated layers as possible as a result of firing in view of the problems of the prior art.

In order to achieve this object, the IGZO sintered body according to the first invention is referred to as a surface-modified layer containing In ₂ Ga ₂ Zn ₁ O ₇ produced by firing (hereinafter referred to simply as “surface-modified layer” in this section). ) An IGZO sintered body made of InGaZnO ₄ having a thickness of the surface-modified layer of 1 mm or less. According to this, since the thickness of the surface-modified layer that is excluded when the IGZO sintered body is commercialized as a target material is less than the conventional case of exceeding 1 mm, the manufacturing cost of the IGZO sintered body is reduced. It can be reduced as compared with the prior art.

The manufacturing method of the IGZO sintered compact which concerns on 2nd invention shape | molds the mixed powder containing an indium oxide powder, a gallium oxide powder, and a zinc oxide powder, or the oxide powder of indium-gallium-zinc, and obtained molding When the IGZO sintered body made of InGaZnO ₄ is manufactured by firing the body, the compact is fired in an atmosphere containing vaporized zinc oxide.

  According to this, since the partial pressure of zinc oxide is high at the time of firing, the amount of zinc oxide vaporized and scattered from the surface of the molded body is reduced. Thereby, generation | occurrence | production of a surface modified layer is suppressed and the thickness of the surface modified layer at the time of completion of sintering reduces compared with the past. Therefore, since the amount of the surface-modified layer that should be excluded when the IGZO sintered body is commercialized as a target material is reduced, the manufacturing cost of the IGZO sintered body can be reduced.

  The manufacturing method of the IGZO sintered body according to the third invention is the second invention, wherein the container in which the molded body is disposed at the time of firing the molded body is hermetically sealed except for a predetermined opening. The opening area of the opening is 0.1 to 15% of the area of the inner surface of the container.

  According to this, since the container other than the opening is sealed in the container in which the molded body is arranged at the time of firing, the inside of the container is zinc oxide by being vaporized and scattered from the surface of the molded body at the time of firing. It becomes the atmosphere containing. That is, when the partial pressure of zinc oxide increases in the container or reaches a saturation pressure, the amount of zinc oxide scattered decreases.

  And if the opening area of an opening part is in the said range, the scattering amount of the zinc oxide at the time of baking can be reduced reliably, and the thickness of the surface alteration layer at the time of completion of baking can be 1 mm or less. In addition, when the opening area is less than 0.1%, the binder is hardly scattered from the sintered body, and the sintered body may be broken, which is not preferable.

  In the method for producing an IGZO sintered body according to the fourth invention, in the second or third invention, the firing of the molded body is a zinc oxide powder in a container in which the molded body is disposed during firing of the molded body, Alternatively, it is characterized in that it is performed by arranging a powder containing zinc oxide such as powdered IGZO sintered body of the present invention. According to this, since the partial pressure of zinc oxide in the container is increased by the zinc oxide vaporized from the zinc oxide powder, it is possible to more effectively reduce the thickness of the surface-affected layer at the completion of firing.

  The manufacturing method of the IGZO sintered body according to the fifth invention is the fourth invention, wherein the zinc oxide powder or the powder containing zinc oxide has an average particle size of 2.0 μm or less, and the volume of zinc oxide contained is The volume of the container is 1% or more. According to this, the amount of zinc oxide scattered during firing can be reliably reduced, and the thickness of the surface-affected layer upon completion of sintering can be reduced to 1 mm or less.

It is a perspective view of the container which can be used for baking in this invention.

The IGZO (InGaZnO ₄ ) sintered body of the present invention is a metal oxide sintered body made of indium oxide (In ₂ O ₃ ), gallium oxide (Ga ₂ O ₃ ), and zinc oxide (ZnO), and is fired. A surface-modified layer containing In ₂ Ga ₂ Zn ₁ O ₇ produced by the above (hereinafter, simply referred to as “surface-modified layer” in this column). The thickness of the surface damaged layer is 1 mm or less, preferably 0.3 mm or less.

  Since the surface-affected layer is different from IGZO, it is excluded when the IGZO sintered body is commercialized as a target material. In this regard, the IGZO sintered body of the present invention has a surface-altered layer with a thickness that is less than the conventional case of exceeding 1 mm, so that the manufacturing cost of the IGZO sintered body is reduced as compared with the conventional case.

  The IGZO sintered body of the present invention is made by using indium oxide powder, gallium oxide powder, and zinc oxide powder as raw materials, and adding a mixed powder such as PVA (polyvinyl alcohol) or acrylic. It is obtained by molding and firing the mixed powder. Instead of the mixed powder, an oxide powder of indium-gallium-zinc may be formed and fired.

The indium oxide powder and gallium oxide powder used as raw materials preferably have a specific surface area of 5 to 10 m ² / g. The zinc oxide powder preferably has a specific surface area of ² to 5 m ² / g.

  Preparation of mixed powder can be performed using well-known methods, such as ball mill mixing. The mixed powder is molded by press molding, casting molding, or the like to form a molded body.

  The molded body is fired in the air at a firing temperature of 1300 to 1600 ° C, preferably 1400 to 1500 ° C. The firing time is preferably 10 to 20 hours.

  During firing, zinc oxide is first vaporized and scattered from the surface of the molded body exposed to high temperature, and the crystal structure of the surface is disturbed. Then, the indium oxide that has been easily scattered is vaporized and scattered, whereby a surface-modified layer is generated. This surface-affected layer is not a desired IGZO but needs to be removed in order to obtain an IGZO sintered product. That is, since the raw material powder is consumed wastefully by the amount of the surface-modified layer, it is preferable to suppress the generation of the surface-modified layer as much as possible.

  In the present invention, in order to suppress the generation of the surface-modified layer as much as possible, the molded body is fired in an atmosphere containing vaporized zinc oxide (hereinafter simply referred to as “zinc oxide atmosphere”). Thereby, vaporization of zinc oxide from the surface of the molded body is suppressed, and the generation of the surface altered layer is suppressed. That is, the thickness of the surface-modified layer generated by firing is thinner than that in the case of exceeding the conventional 1 mm.

  In order to perform firing in a zinc oxide atmosphere, the molded body is fired using a container 10 as shown in FIG. The container 10 includes a container main body 11 and a lid body 12 for closing the upper surface of the container 10. Concave portions 13 are provided at the upper end portions of the side walls at both ends of the container body 11.

  When the container 10 is closed by the lid 12 as indicated by an arrow 14, an opening is formed by the recess 13 and the end of the lid 12. At this time, the container 10 is in a state in which portions other than the opening are sealed. The recess 13 may be provided only at one end of the container body 11.

  The molded body is placed in the container 10 and fired in a state of being substantially isolated from the outside of the container 10 by closing the lid body 12. At the start of firing, zinc oxide is vaporized and scattered from the molded body, and when the surface crystal structure is disturbed, the indium oxide, which is easily scattered, is then vaporized and scattered to form a surface-modified layer. The

  However, after that, the partial pressure of zinc oxide in the container 10 increases or reaches a saturation pressure, so that vaporization of zinc oxide is suppressed. Thereby, the production | generation of the surface modified layer at the time of baking is suppressed, and the thickness of the surface damaged layer at the time of completion of baking reduces compared with the past.

  Thereby, the amount of the surface-modified layer that should be excluded when the IGZO sintered body is commercialized as a target material is reduced, and the manufacturing cost of the IGZO sintered body is reduced. In addition, at the time of baking, it is necessary to vaporize and exclude the binder etc. which are contained in a molded object, but the vaporized binder etc. are discharged | emitted through the opening part by the recessed part 13 without trouble.

  The ratio of the area of the opening to the area of the inner surface of the container 10 is preferably 0.1 to 15%. If it is 0.1% or less, it becomes difficult to volatilize and remove the binders contained in the molded body, which may cause the sintered body to break, and it is difficult to form a stable sintered body. Become. If it is 15% or more, the effect of suppressing the vaporization of zinc oxide becomes thin. A more preferable range is 1 to 3%.

  Moreover, in order to suppress the vaporization of zinc oxide more effectively during firing, a zinc oxide powder or a powder containing zinc oxide obtained by pulverizing the IGZO sintered body of the present invention is laid in the container 10. It is preferable to perform calcination. In this case, since the partial pressure of zinc oxide in the container 10 is further increased by the vaporization of zinc oxide in the installed powder, the vaporization of zinc oxide is more effectively suppressed and the formation of the surface altered layer is limited. .

  The amount of the zinc oxide powder or the powder containing zinc oxide to be used is preferably 1% or more in terms of the ratio of the volume of zinc oxide contained in the zinc oxide powder or the powder containing zinc oxide to the volume of the container 10. A more preferable range is 2% or more. However, the zinc oxide powder or the powder containing zinc oxide has a problem in firing due to the heat insulating effect of the powder if the molded body is buried in the powder.

The volume of zinc oxide contained in the zinc oxide powder or the powder containing zinc oxide is based on the weight of the zinc oxide powder or the weight of zinc oxide in the powder containing zinc oxide, and the density of zinc oxide is 5.6 g / cm ^3. Calculated.

  The average particle diameter of the zinc oxide powder or the powder containing zinc oxide to be used is preferably as small as possible, and is preferably 2.0 μm or less. This is because the smaller the average particle size, the larger the surface area of the powder and the more volatilized zinc oxide, which is preferable in forming a zinc oxide atmosphere.

Further, instead of the container 10, a conventional container without a lid is used, and the container contains a zinc oxide having a volume ratio of 1% or more, preferably 2% or more, in the same manner as described above. The zinc oxide powder or the powder containing zinc oxide may be spread and fired. Also in this case, since the firing is performed in a zinc oxide atmosphere, the formation of the surface deteriorated layer is suppressed.
[Example]
As Example 1, an IGZO sintered body was obtained as follows, and the thickness of the surface-modified layer was measured.

That is, first, indium oxide powder, gallium oxide powder, and zinc oxide powder are mixed and pulverized by a wet ball mill at a mass ratio of 45:30:25 (molar ratio of indium, gallium and zinc is 1: 1: 1) A mixed powder was obtained.

  Next, the obtained mixed powder was granulated with a spray dryer using PVA (polyvinyl alcohol) as a binder, and then molded by a uniaxial pressure press to obtain a molded body. Next, the obtained molded body was fired for 15 hours at a firing temperature of 1450 ° C. using the container 10 of FIG. 1 in an air atmosphere to obtain an IGZO sintered body. However, the ratio of the area of the opening (recess 13) to the area of the inner surface of the container 10 used for firing was 0.1% shown in the column of “opening area” in Example 1 in Table 1. Is. Moreover, the magnitude | size of the container 10 is 200x300x100 mm, and the magnitude | size of a molded object is 100x100x10 mm.

  And about the obtained IGZO sintered compact, the thickness of the surface alteration layer was measured. The results are shown in the column “Surface Altered Layer Thickness” in Example 1 in Table 1.

  Next, as Example 2-4, as the container 10, the ratio of the area of the opening with respect to the area of the inner wall is each value shown by the column of "opening area" in Examples 2-4 in Table 1. Except having used a certain container 10, it carried out similarly to the case of Example 1, and acquired the IGZO sintered compact and measured the thickness of the surface alteration layer. The results are shown in the column of “Thickness of surface-affected layer” in Examples 2 to 4 in Table 1.

  Next, as Examples 5 to 14, an IGZO sintered body was obtained in the same manner as in Example 1 except that a zinc oxide powder having an average particle size of 2.0 μm or less was laid in the container 10. The thickness of the surface altered layer was measured.

  However, as the container 10, each container 10 in which the ratio of the area of the opening to the area of the inner surface is each value shown in the column of “opening area” in Examples 5 to 14 in Table 1 is used. Acquire an IGZO sintered body in each case where the ratio of the volume of zinc oxide contained in the zinc oxide powder to be laid with respect to the volume of 10 was set to each value shown in the column of “volume of zinc oxide laid” in Examples 5-14. Then, the thickness of the surface altered layer was measured.

  This result is shown in the column of “surface deteriorated layer thickness” in Examples 5 to 14 in Table 1.

  Further, as Examples 15 to 18, Example 1 was used except that a normal container without a lid was used instead of the container 10, and zinc oxide powder having an average particle size of 2.0 μm or less was laid in the container. The IGZO sintered compact was acquired similarly to the case of, and the thickness of the surface altered layer was measured. However, in each case, the ratio of the volume of zinc oxide contained in the zinc oxide powder to be laid to the volume of the container was set to each value shown in the column of “laying zinc oxide volume” in Examples 15 to 18 for IGZO sintering. The body was obtained, and the thickness of the surface altered layer was measured.

The results are shown in the column of “Surface Altered Layer Thickness” in Examples 15 to 18 in Table 1 .
As a ratio Comparative Examples 1, except that firing was carried out by using a conventional container with no lid instead of the container 10 in the same manner as in Example 1 to obtain the IGZO sintered body, the thickness of the surface affected layer Measured. The results are shown in the column “Thickness of surface-affected layer” in Comparative Example 1 in Table 1.

Next, as Examples 19 and 20 , the ratio of the area of the opening to the area of the inner surface of each container 10 to be used, each value shown in the “opening area” column in Examples 19 and 20 in Table 1 Except for the above, an IGZO sintered body was obtained in the same manner as in Example 1, and the thickness of the surface-modified layer was measured. The results are shown in the column “Surface Altered Layer Thickness” in Examples 19 and 20 in Table 1.

Furthermore, as Example 21 , firing was performed using a normal container without a lid instead of the container 10, and the ratio of the volume of the zinc oxide contained in the zinc oxide powder laid in the container to the volume of the container the, except that the value of Ru indicated in column "laying zinc oxide volume" in example 21 in Table 1, in the same manner as in example 1 to obtain the IGZO sintered body, the surface alteration layer The thickness of was measured. The result is shown in the column “Surface Altered Layer Thickness” in Example 21 in Table 1.

  Referring to Table 1, according to Comparative Example 1 in which a normal container was used and no zinc oxide powder was laid, the thickness of the surface-modified layer produced by firing was 2.0 mm. On the other hand, Examples 1-4 using the container 10 whose area of an opening part is 0.1 to 15%, or the volume of zinc oxide with respect to the volume of a container is further used using this container 10 or a normal container. According to Examples 5-18 in which -30% zinc oxide powder was laid, the thickness of the surface-modified layer is 0.2-1.0 mm.

  Therefore, by firing in a predetermined zinc oxide atmosphere using the container 10 or zinc oxide powder, the thickness of the surface altered layer is set to 1 mm or less, which is thinner than the conventional case exemplified by Comparative Example 1. You can see that

  Further, by optimizing the opening area of the container 10, the amount of zinc oxide powder to be laid, and other conditions, it is considered that the thickness of the surface-affected layer can be reduced to 0.2 mm or less and can be closer to 0 mm. . If it is 0.3 mm or less, the cost reduction at the time of commercializing IGZO sintered compact as a target material can be fully achieved, and it is preferable.

  Moreover, when using the container 10 whose area of an opening part is 0.1 to 15% (Examples 1-14), the volume of zinc oxide with respect to the volume of the container 10 is further like Example 5-14. It can be seen that the thickness of the surface-affected layer can be further reduced by laying the zinc oxide powder of 1 to 30%. In particular, the thickness of the surface-affected layer can be reduced to at least 0.5 mm by setting the area of the opening to 0.1 to 3% and the volume of zinc oxide to 2 to 10%.

In addition, based on the results of Examples 5-8, Examples 15-18, and Example 21, no matter whether the container 10 or a normal container is used, in order to reduce the thickness of the surface-modified layer, it is laid. When the volume of zinc oxide contained in the zinc oxide powder is 1% or more, particularly 2% or more is preferable and less than 1%, the effect of reducing the thickness of the surface-affected layer is lost when the container 10 is not used. I understand that.

Moreover, when using the container 10 without laying zinc oxide powder, as Example 1-4 , 19 and 20 show, if the area of an opening part is 0.1 to 15%, the thickness of a surface alteration layer The thickness of the surface-affected layer can be reduced to at least 0.3 mm if the opening area is 0.1 to 3%. I understand.

  If the area of the opening exceeds 15%, the thickness of the surface-modified layer exceeds 1 mm, which is not preferable. On the other hand, if it is less than 0.1%, the binders contained in the molded body cannot be removed by volatilization during firing, and the sintered body may be broken. % Is preferable.

  DESCRIPTION OF SYMBOLS 10 ... Container, 11 ... Container main body, 12 ... Cover body, 13 ... Recessed part.

Claims (5)

A IGZO sintered body made of InGaZnO ₄ having a surface deteriorated layer containing _In 2 _Ga 2 _Zn 1 _{O 7} generated by firing, IGZO sintered, wherein the thickness of the surface alteration layer is 1mm or less Union. A mixed powder containing indium oxide powder, gallium oxide powder, and zinc oxide powder, or an indium-gallium-zinc oxide powder is molded, and the obtained molded body is fired to obtain an IGZO sintered body made of InGaZnO _4. In manufacturing,
Firing of the molded body is performed in an atmosphere containing vaporized zinc oxide. The container in which the molded body is disposed at the time of firing the molded body is hermetically sealed except for a predetermined opening,
The method for producing an IGZO sintered body according to claim 2, wherein the opening area of the opening is 0.1 to 15% of the area of the inner surface of the container.   The firing of the molded body is performed by laying a zinc oxide powder or a powder containing zinc oxide in a container in which the molded body is placed when the molded body is fired. The manufacturing method of the IGZO sintered compact as described in a term.   5. The zinc oxide powder or the powder containing zinc oxide has an average particle size of 2.0 μm or less, and the volume of zinc oxide contained is 1% or more of the volume of the container. The manufacturing method of IGZO sintered compact of description.