JP2019073747A - AMORPHOUS TRANSPARENT OXIDE FILM, Sn-Zn-O OXIDE SINTERED BODY, METHOD FOR PRODUCING AMORPHOUS TRANSPARENT OXIDE FILM, AND METHOD FOR PRODUCING Sn-Zn-O OXIDE SINTERED BODY - Google Patents

Abstract

To provide an amorphous transparent oxide film having high gas barrier properties, excellent surface smoothness, and excellent insulation performance.SOLUTION: An amorphous transparent oxide film has Zn and Sn, and further has Ge and Ta, wherein, in a metal atom ratio, Sn/(Zn+Sn) is 0.29 or more and 0.39 or less, Ta/(Zn+Sn+Ge+Ta) is 0.0005 or more and 0.01 or less, Ge/(Zn+Sn+Ge+Ta) is 0.001 or more and 0.04 or less.SELECTED DRAWING: None

Description

  The present invention relates to sputtering when depositing an amorphous transparent oxide film or an amorphous transparent oxide film applied to an electroluminescent (EL) display element or a plasma electrode film formed by sputtering. The present invention relates to a Sn—Zn—O-based oxide sintered body configured as a target, a method for producing an amorphous transparent oxide film, and a method for producing a Sn—Zn—O-based oxide sintered body.

  A gas-barrier film (transparent resin substrate) in which a metal oxide film such as silicon oxide or aluminum oxide is covered on the surface of a plastic substrate or film substrate changes the quality of food or chemicals that require blocking of gas such as water vapor or oxygen It has been used in packaging applications for the purpose of preventing. Moreover, also in the field of electronic devices, for example, it is used for flexible display elements such as liquid crystal display elements, solar cells, and electroluminescent (EL) display elements.

  In recent years, gas barrier films used in liquid crystal display elements, EL display elements, etc., in addition to requirements for weight reduction and enlargement in accordance with the development of display elements, freedom of shape, adaptation to curved surface display, etc. Requirements are also sought. For this reason, adoption of a transparent resin film base material is examined instead of a glass substrate which is heavy and is easily broken and which is difficult to be enlarged.

  However, since the resin film substrate is inferior in gas barrier property to a glass substrate, there is a problem that water vapor and oxygen permeate through the substrate to deteriorate the liquid crystal display element and the EL display element. In order to overcome such a problem, development of a film (transparent resin substrate) in which a gas barrier property is enhanced by forming a metal oxide film on a resin film substrate has been performed.

  For example, Patent Document 1 discloses a transparent resin substrate that has better surface smoothness, higher transparency, and higher gas barrier performance than the prior art. In this transparent resin substrate, a transparent oxide film composed of a tin oxide-based amorphous film is formed on at least one surface of a resin film substrate as a gas barrier layer. By using a transparent oxide film as a tin oxide-based amorphous film, it has excellent gas barrier performance. In addition, by using a tin oxide-based amorphous film, surface smoothness is also improved. Thereby, in the case of forming a multilayer film in which films are laminated, it becomes possible to form a uniform film with less unevenness.

  Moreover, in patent document 2, in order to improve the relative density and durability of a target material, the Sn-Zn-O type oxide sinter in which this sputtering target has high density and has mechanical strength is proposed.

JP, 2005-103768, A JP, 2013-036073, A

  The transparent oxide film is formed by sputtering, but the target material used for this is naturally the same component as the film component. That is, in Patent Document 1, since the transparent oxide film is a tin oxide-based amorphous film, a tin oxide-based target material is used. However, since a tin oxide based target material generally has low relative density and poor durability, it is considered difficult to manufacture a high-density and durable sputtering target using this target material. Therefore, a sputtering target made of a tin oxide-based target material is not suitable for sputtering and film formation under high energy conditions.

  Further, in Patent Document 2, although a film formed by sputtering using a Sn—Zn—O-based oxide sintered body is an amorphous film, the surface roughness of the film is not sufficient and there is unevenness and is high. It does not have gas barrier properties. Therefore, a transparent oxide film capable of stably mass-producing a uniform film with less unevenness is required.

Furthermore, recently, this transparent oxide film is required to have insulating properties. For example, when it is used for an EL display element, when the transparent electrode film and the transparent oxide film which is a barrier layer are laminated, current may leak to the transparent oxide film side. Therefore, the transparent oxide film is required to have a surface resistance value of 1.00 × 10 ^{10 to} 1.00 × 10 ¹² levels.

  Therefore, the present invention was conceived in view of the problems of the prior art, and is a novel and improved amorphous which has high gas barrier properties, good surface smoothness, and excellent insulation. Quality transparent oxide film, Sn-Zn-O-based oxide sintered body used for sputtering the transparent oxide film, method for producing amorphous transparent oxide film, and Sn-Zn-O-based oxidation It aims at providing a manufacturing method of a thing sintered compact.

  That is, one embodiment of the present invention is an amorphous transparent oxide film containing Zn and Sn, which further contains Ge and Ta, and Sn / (Zn + Sn) is 0 at a metal atom ratio. .29 to 0.39, Ta / (Zn + Sn + Ge + Ta) is 0.0005 to 0.01, and Ge / (Zn + Sn + Ge + Ta) is 0.001 to 0.04.

  In one embodiment of the present invention, Sn / (Zn + Sn) is 0.31 or more and 0.36 or less, Ta / (Zn + Sn + Ge + Ta) is 0.002 or more and 0.003 or less, Ge / (Zn + Sn + Ge + Ta) in the metal atom number ratio. Is preferably 0.004 or more and 0.006 or less.

In one embodiment of the present invention, the surface resistance is preferably 1.0 × 10 ¹⁰ Ω / sq or more and 5.0 × 10 ¹² Ω / sq or less.

  Moreover, in one aspect of the present invention, the center line average surface roughness Ra of the surface is preferably 0.6 nm or less.

  Another aspect of the present invention is a Sn—Zn—O-based oxide sintered body used to form the above-described amorphous transparent oxide film by sputtering, and Zn and Sn. Contained as the main component and further contains Ge and Ta, and the number ratio of metal atoms, Sn / (Zn + Sn) is 0.29 or more and 0.39 or less, Ta / (Zn + Sn + Ge + Ta) is 0.0005 or more and 0.01 or less And Ge / (Zn + Sn + Ge + Ta) is 0.001 or more and 0.04 or less.

Moreover, in another aspect of the present invention, it is preferable that the Zn ₂ SnO ₄ phase be composed of 90% or more.

  Moreover, in the other aspect of this invention, it is preferable that a specific resistance is 1000 ohm * cm or more and 13000 ohm * cm or less.

  Moreover, the other aspect of this invention is a manufacturing method of the amorphous | non-crystalline transparent oxide film containing Zn and Sn, Comprising: The sputtering target comprised from a Sn-Zn-O type oxide sinter is considered. It is characterized in that film formation is performed by sputtering method.

  Furthermore, the other aspect of this invention is a manufacturing method of the Sn-Zn-O type oxide sinter mentioned above, Comprising: The oxide powder of zinc, the oxide powder of tin, and the oxide containing an additional element A granulation step of mixing powders to prepare granulated powder, a molding step of pressure forming the granulated powder to obtain a compact, and a firing step of firing the compact to obtain an oxide sintered body And, in the granulation step, Sn / (Zn + Sn) is 0.29 or more and 0.39 or less, Ta / (Zn + Sn + Ge + Ta) is 0.0005 or more and 0.01 or less, Ge / (at metal atom ratio) The granulated powder is prepared by mixing the oxide powder of zinc, the oxide powder of tin, and the oxide powder containing the additive element such that Zn + Sn + Ge + Ta) is 0.001 or more and 0.04 or less. It is characterized by

  The amorphous transparent oxide film according to the present invention has high gas barrier properties, good surface smoothness, and excellent insulation.

It is a flowchart which shows the outline of the manufacturing method of the sputtering target which concerns on one Embodiment of this invention. It is a SPM observation image of the transparent conductive film obtained in Example 2. FIG. It is an SPM observation image of a film substrate. It is a SPM observation image of an AZO transparent conductive film. It is a SPM observation image of the transparent conductive film obtained by the comparative example 4. FIG.

  Hereinafter, the Sn—Zn—O-based target according to the present invention, a method for producing the same, an amorphous transparent oxide film and a method for producing the same will be described with reference to the drawings. In addition, this invention is not limited to the following example, In the range which does not deviate from the summary of this invention, it can change arbitrarily.

  An amorphous transparent oxide film according to an embodiment of the present invention is mainly used as a barrier layer. A metal oxide film is covered on the surface of a flexible display element such as a plastic substrate or a film substrate, such as a liquid crystal display element, a solar cell, an electroluminescence (EL) display element, etc. to prevent deterioration by blocking gas such as water vapor or oxygen. It is used for the purpose of

  The transparent oxide film needs to shut off gases such as water vapor and oxygen. For that purpose, it is preferable that the barrier film be as dense as possible, and be thin and uniform. For this reason, the transparent oxide film is formed by sputtering. The transparent oxide film formed by the sputtering method is more preferably amorphous as described in Patent Document 1. This is because when the transparent oxide film is a crystalline film, crystal grain boundaries are present in this film, and gas and water vapor are transmitted through the crystal grain boundaries, so that the gas barrier performance is lowered. Further, although a tin oxide based film is proposed as the amorphous film in the above Patent Document 1, when forming a tin oxide based film by a sputtering method, a target material constituting a sputtering target used for sputtering is The tin oxide type which is the same component as the film is used. In general, the tin oxide-based target material is high in acid resistance but low in relative density of the target material, and there are many problems such as the inability to stably form a film because the target material is broken during sputtering.

  Therefore, in order to solve the above problems, the present inventors include Sn in a ratio of 0.29 or more and 0.39 or less as an atomic ratio Sn / (Zn + Sn), and Ta and Ge as additive elements. It is a barrier film having high gas barrier properties, good surface smoothness and excellent insulation properties by containing it at a predetermined ratio, which is excellent in mass productivity at the time of film formation by sputtering and can be stably produced. The inventors found a Sn—Zn—O-based transparent oxide film and completed the present invention.

[1-1. Sn-Zn-O-based oxide sintered body]
First, a Sn—Zn—O-based oxide sintered body (hereinafter, also referred to as “oxide sintered body”) according to an embodiment of the present invention will be described. The Sn—Zn—O-based oxide sintered body is configured as a sputtering target used for sputtering, and is used when forming an amorphous transparent oxide film described later by sputtering.

  The Sn—Zn—O-based oxide sintered body according to the present embodiment contains zinc (Zn) and tin (Sn) as main components, and further contains germanium (Ge) and tantalum (Ta). And Sn / (Zn + Sn) is 0.29-0.39, Ta / (Zn + Sn + Ge + Ta) is 0.0005-0.01, Ge / (Zn + Sn + Ge + Ta) is 0.001 or more by metal atom number ratio. It is characterized by being 04 or less.

By using Zn and Sn as main components for the target, improvement in reduction of relative density, which is a problem of tin oxide based targets, can be achieved. In particular, the strength of the sintered body is enhanced by the formation of a Zn ₂ SnO ₄ phase of a spinel crystal structure in the oxide sintered body.

When Sn is contained at a ratio of less than 0.33 as atomic number ratio Sn / (Zn + Sn), the compound in the sintered body is mainly composed of ZnO phase of wurtzite crystal structure and Zn ₂ SnO ₄ phase of spinel crystal structure When Sn is contained in an atomic ratio Sn / (Zn + Sn) at a ratio exceeding 0.33, the Zn ₂ SnO ₄ phase of the spinel crystal structure and the SnO ₂ phase of the rutile crystal structure are mainly used. When Sn is contained at a ratio of 0.33 as an atomic ratio Sn / (Zn + Sn), only the Zn ₂ SnO ₄ phase of the spinel type crystal structure is obtained. Therefore, the ratio of zinc (Zn) to tin (Sn) is 0.29 or more as the atomic ratio Sn / (Zn + Sn) of Sn so that the Zn ₂ SnO ₄ phase of spinel type crystal structure is about 90% or more. It is 0.39 or less. Furthermore, Sn is preferably 0.31 or more and 0.36 or less as an atomic ratio Sn / (Zn + Sn) so that the Zn ₂ SnO ₄ phase of the spinel type crystal structure is about 95% or more. Thereby, the strength of the oxide sintered body can be improved.

  Moreover, although the transparent oxide film formed into a film by sputtering using the target which has zinc (Zn) and tin (Sn) as a main component is an amorphous film, although mentioned later, surface roughness is not enough. . In particular, when Sn is less than 0.29 in atomic ratio Sn / (Zn + Sn), the above-mentioned ZnO phase increases, and this phase causes unevenness of the surface roughness during film formation. Therefore, Sn is 0.29 or more as atomic number ratio Sn / (Zn + Sn).

  Moreover, the ratio of zinc (Zn) and tin (Sn) which are main components also influences the specific resistance. When the ratio of Sn / (Zn + Sn) increases, the specific resistance value of the oxide sintered body tends to decrease. In addition, although mentioned later, the surface resistance value of a transparent oxide film can be adjusted also with the oxygen concentration at the time of film-forming.

In addition, since Zn ₂ SnO ₄ , ZnO, and SnO ₂ are substances having poor conductivity, the conductivity is greatly improved even if the compounding ratio and the amounts of the compound phase and ZnO and SnO ₂ are adjusted by adjusting the compounding ratio. It is not possible. Therefore, in the present embodiment, Ta is added as the first additive element. Since Ta substitutes for Zn in the ZnO phase, Zn in the Zn ₂ SnO ₄ phase, or Sn in the ₄ phase, and Sn in the SnO ₂ phase and forms a solid solution, the ZnO phase in the wurtzite crystal structure and Zn in the spinel crystal structure Compound phases other than the ₂ SnO ₄ phase and the SnO ₂ phase of rutile crystal structure are not formed. The conductivity is improved while maintaining the density of the oxide sintered body by the addition of Ta. The atomic ratio Ta / (Sn + Zn + Ge + Ta) to the total amount of all the metal elements of Ta is set to 0.0005 or more and 0.01 or less. Especially, in order to suppress abnormal discharge more certainly at the time of sputtering, 0.002 or more and 0.003 or less are preferable.

When the atomic ratio Ta / (Sn + Zn + Ge + Ta) is less than 0.0005, the conductivity does not increase. On the other hand, when the atomic number ratio Ta / (Sn + Zn + Ge + Ta) exceeds 0.01, another compound phase, for example, a compound phase such as Ta ₂ O ₅ or ZnTa ₂ O ₆ is generated to deteriorate conductivity. become.

  The amorphous transparent oxide film according to the present embodiment described later needs to be an amorphous film when deposited by sputtering. By being an amorphous film, it is possible to improve the gas barrier property by being dense. Further, the surface roughness of the transparent oxide film can be reduced, and when laminating the film, it becomes possible to laminate the film uniformly with less unevenness.

Although the transparent oxide film formed by sputtering using a target containing zinc (Zn) and tin (Sn) as main components is an amorphous film, the surface roughness is not sufficient although it will be described later. In addition, it can not be said that the sintered density of the oxide sintered body is sufficient. Therefore, Ge is added as a second additive element. Ge substitutes for Zn in the ZnO phase, Zn in the Zn ₂ SnO ₄ phase, or Sn in the ₄ phase, and Sn in the SnO ₂ phase to form a solid solution, and therefore, the ZnO phase in the wurtzite crystal structure and Zn in the spinel crystal structure Compound phases other than the ₂ SnO ₄ phase and the SnO ₂ phase of rutile crystal structure are not formed. The addition of Ge has the effect of densifying the oxide sintered body. Thereby, the sintered density of the oxide sintered body can be made higher. Further, by densifying the oxide sintered body, there is an effect of improving the surface roughness of the amorphous film when the film is formed by sputtering. The atomic ratio Ge / (Sn + Zn + Ge + Ta) to the total amount of all metal elements of Ge is 0.001 or more and 0.04 or less, preferably 0.004 or more and 0.006 or less.

If the atomic ratio Ge / (Sn + Zn + Ge + Ta) is less than 0.001, the film formed by sputtering may not be an amorphous film. On the other hand, when the atomic ratio Ge / (Sn + Zn + Ge + Ta) exceeds 0.04, another compound phase, for example, a compound phase of Zn ₂ Ge ₃ O ₈ or the like is generated to deteriorate the conductivity.

The specific resistance value of the oxide sintered body is an important item in order to perform sputtering efficiently and stably. At the time of sputtering, as the specific resistance value is smaller, it is possible to perform sputtering with smaller energy, and the deposition rate can be increased. However, the surface resistance value of the film formed by sputtering depends on the oxygen concentration at the time of sputtering and the specific resistance value of the oxide sintered body. If possible, by adjusting the specific resistance value of the oxide sintered body to the surface resistance value of the film, the oxygen concentration at the time of sputtering can be minimized and the stable surface resistance value of the film can be obtained. Thus, the amorphous transparent oxide film described later has insulation. Therefore, when the surface resistance value of the film is designed to be 1.0 × 10 ¹⁰ Ω / □ or more and 5.0 × 10 ¹² Ω / □ or less, the specific resistance value of the oxide sintered body is equal to this. Then, as described above, the productivity of sputtering is extremely reduced. Therefore, the specific resistance value of the oxide sintered body is set to 1000 Ω · cm or more and 13000 Ω · cm or less.

  If the specific resistance is less than 1000 Ω · cm, the surface resistance value of the obtained film will be low, and there is a possibility that a leak from a nearby electrode may occur. On the other hand, when the specific resistance value exceeds 13000 Ω · cm, discharge becomes difficult and there is a possibility that stable film formation can not be performed for direct current (DC) sputtering. The surface resistance of the film is adjusted by the oxygen concentration at the time of sputtering. Details will be described later.

  The relative density of the oxide sintered body is 94% or more. The relative density can be improved by blending in a ratio of 0.29 or more and 0.39 or less as the atomic number ratio Sn / (Sn + Zn) and blending predetermined amounts of Ge as an additive element.

  In addition, by setting the metal atom number ratio Sn / (Zn + Sn) to be 0.31 or more and 0.36 or less, the relative density of the oxide sintered body can be improved to 98% or more. When the relative density is 98% or more, the strength of the target material made of the oxide sintered body is improved, the film forming rate at the time of sputtering is improved, and at the same time, the generation of gas originating from the target material is reduced and stable film formation Is possible.

In the oxide sintered body according to one embodiment of the present invention, when the atomic ratio Sn / (Sn + Zn) is 0.29 or more and less than 0.33, the ZnO phase having a wurtzite crystal structure and the spinel crystal are used. The Zn ₂ SnO ₄ phase of the structure is the main component. When the atomic ratio Sn / (Sn + Zn) is more than 0.33 and 0.39 or less, the Zn ₂ SnO ₄ phase of the spinel crystal structure and the SnO ₂ phase of the rutile crystal structure are main components. . Furthermore, in the case where the atomic ratio Sn / (Sn + Zn) is 0.33, only the Zn ₂ SnO ₄ phase of the spinel crystal structure is obtained.

In the present embodiment, appropriate amounts of Ta as the first additive element and Ge as the second additive element, Zn in the ZnO phase, Zn or Zn in the Zn ₂ SnO ₄ phase, and Sn in the SnO ₂ phase are substituted. Therefore, other compound phases other than the ZnO phase of wurtzite crystal structure, the Zn ₂ SnO ₄ phase of spinel crystal structure, and the SnO ₂ phase of rutile crystal structure are not formed. Since an oxide sintered body is formed from such a phase, cracking or chipping or the like occurs in the target material even during sputtering for forming a film using a sputtering target on which the oxide sintered body is formed. It does not occur.

  Note that the metal element and the additive element may further contain an element other than the above-described elements, for example, Co, Mn, Al, Mg, Si, Bi, Ga, Ti, Cr, Fe, Cu, Ca, V, At least one element selected from Zr, Nb, Mo, and W can be used.

[1-2. Method of producing Sn-Zn-O-based oxide sintered body]
Next, the manufacturing method of the Sn-Zn-O type oxide sinter which concerns on one Embodiment of this invention is demonstrated. The method for producing a Sn—Zn—O-based oxide sintered body includes a granulation step S1, a forming step S2, and a firing step S3. For example, in the present embodiment, tantalum oxide as the first additive element and germanium oxide as the second additive element are added to the raw material powder containing only the tin-zinc oxide compound or the mixed powder of tin oxide and zinc oxide. The mixture is granulated, granulated, and the granulated powder is formed by a cold static pressure press or the like, and the formed body is fired in a firing furnace to obtain an oxide sintered body. Each step will be individually described below.

  The granulation step S1 is a step of mixing an oxide powder of zinc, an oxide powder of tin, and an oxide powder containing an additive element to produce a granulated powder.

First, in the granulation step S1, a main raw material is prepared. Tin oxide (SnO ₂ ) and zinc oxide (ZnO), which are main raw materials, are raw material powders containing only a tin oxide compound or a mixed powder of tin oxide and zinc oxide, and an atomic ratio of Sn to Sn / (Sn + Zn) As 0.29 or more and 0.39 or less. More preferably, it is contained in the ratio of 0.31 or more and 0.36 or less. It is preferable to use a mixed powder of tin oxide and zinc oxide as the main raw material because the compounding ratio can be easily adjusted. For example, the raw material powder is SnO ₂ powder and ZnO powder. The oxide powder containing the additive element is Ta ₂ O ₅ powder as Ta of the first additive element and GeO ₂ powder as Ge of the second additive element. Ta ₂ O ₅ powder and GeO ₂ powder are further added to the main raw materials SnO ₂ powder and ZnO powder to prepare.

  In the granulation step S1, Sn / (Zn + Sn) is 0.29 to 0.39, Ta / (Zn + Sn + Ge + Ta) is 0.0005 to 0.01, and Ge / (Zn + Sn + Ge + Ta + Ga) is 0. 0 by metal atom number ratio. A zinc oxide powder, a tin oxide powder, and an oxide powder containing an additive element are mixed so as to be 001 or more and 0.04 or less. As described above, a high density oxide sintered body is obtained by adding Ta and Ge as additive elements at a ratio such that Sn / (Zn + Sn) is 0.29 or more and 0.39 or less. Can be manufactured.

Subsequently, the prepared raw material powder is mixed with pure water or ultrapure water, an organic binder, a dispersant, and an antifoaming agent in a mixing tank so that the raw material powder concentration becomes a predetermined concentration. Then, the raw material powder is wet-grounded using a bead mill or the like into which hard ZrO ₂ balls are charged, and then mixed and stirred to obtain a slurry. A granulated powder can be obtained by spraying and drying the obtained slurry with a spray dryer or the like.

The forming step S2 is a step of press-forming the granulated powder obtained in the granulation step S1 to obtain a formed body. That is, in the forming step S2, pressure forming is performed, for example, at a pressure of about 294 MPa (3.0 ton / cm ² ) in order to remove pores between particles of the granulated powder. The method of pressing is not particularly limited. For example, a cold isostatic press (CIP: Cold Isostatic) capable of filling the granulated powder obtained in the granulation step S1 into a rubber mold and applying high pressure It is preferable to use Press).

  The firing step S3 is a step of firing the formed body obtained in the forming step S2 to obtain an oxide sintered body. That is, in the firing step S3, the oxide sintered body is fired by firing the compact obtained in the forming step S2 at a predetermined temperature and for a predetermined time at a predetermined temperature rising rate in the sintering furnace. obtain.

In the firing step S3, for example, firing is performed in an atmosphere in a firing furnace in the air. As for the temperature rising rate from 700 ° C. to a predetermined sintering temperature in this sintering furnace, it is preferable to fire the compact at a rate of 0.3 to 1.0 ° C./min. This is because the diffusion of ZnO, SnO ₂ or Zn ₂ SnO ₄ compound is promoted to improve the sinterability and the conductivity. Further, by such a heating rate in the high temperature region, there is also the effect of suppressing the volatilization of the ZnO and _Zn 2 SnO _4.

In the method for producing a Sn—Zn—O-based oxide sintered body according to the present embodiment, SnO ₂ may be present during sintering (at a relatively low temperature range), but Sn / (Zn + Sn) is the case is 0.3 or less (see example 4), the sintering is completed at a given temperature, SnO ₂ phase is no longer, the diffraction peak of SnO ₂ phase by X-ray diffraction analysis will not be measured.

  When the temperature rising rate in the sintering furnace is less than 0.3 ° C./min, the diffusion of the compound is reduced. On the other hand, when the temperature exceeds 1.0 ° C./min, the temperature rise rate is fast, so that the formation of the compound is incomplete, and a dense oxide sintered body can not be produced.

It is preferable to make sintering temperature after temperature rising into 1300 degreeC or more and 1400 degrees C or less. When the sintering temperature is less than 1300 ° C., the temperature is too low, and the grain boundary diffusion of sintering in the ZnO, SnO ₂ , Zn ₂ SnO ₄ compound does not proceed. On the other hand, when the temperature exceeds 1400 ° C., grain boundary diffusion is promoted and sintering proceeds, but the volatilization of the Zn component can not be suppressed, and a large number of pores are left inside the oxide sintered body. become.

The holding time after the temperature rise is preferably 15 hours or more and 25 hours or less. If the holding time is less than 15 hours, the sintering is incomplete, so a sintered body having a large strain and warpage is formed, and grain boundary diffusion does not proceed, and the sintering does not proceed. As a result, a dense sintered body can not be produced. On the other hand, if it exceeds 25 hours, volatilization of ZnO and Zn ₂ SnO ₄ increases, which leads to a decrease in density of the oxide sintered body, a deterioration in working efficiency, and an increase in cost.

[2. Method of manufacturing sputtering target]
The sputtering target is used for a sputtering apparatus when forming a film by sputtering. First, a machined body (target material) is obtained by subjecting the above-described oxide sintered body to a mechanical grinding process to a desired size. A sputtering target is obtained by bonding (bonding) the obtained processed body to a backing plate made of a copper material, a stainless steel material or the like using a bonding material such as indium (In) or the like. Note that the sputtering target may be a combination of a plurality of oxide sintered bodies.

  The oxide sinter according to the embodiment of the present invention mainly composed of Zn and Sn obtained under such conditions has also been improved in conductivity, so that film formation by DC sputtering is possible. Become.

[3-1. Amorphous Transparent Oxide Film]
Next, an amorphous transparent oxide film according to an embodiment of the present invention will be described. The amorphous transparent oxide film (hereinafter, also referred to as "transparent oxide film") according to the present embodiment has high gas barrier properties, good surface smoothness, and excellent insulation. In addition, since the characteristic of oxide sinter mentioned above is handed over to a transparent oxide film, the overlapping description is omitted.

  In the transparent oxide film according to the present embodiment, a film formed by sputtering using a sputtering target constituted of an oxide sintered body obtained by adding Ta and Ge to a Sn-Z-O system is an amorphous film and Become. The transparent oxide film is a transparent film made of an oxide containing an element of tin, zinc, tantalum and germanium, and its crystal structure has an amorphous structure. Since this transparent oxide film is an amorphous film, it has excellent unevenness in the surface of the film and therefore has excellent gas barrier properties. If the transparent conductive film is a crystalline film, crystal grain boundaries are present, and the gas passes through the crystal grain boundaries, so that the gas barrier performance is degraded.

  The transparent oxide film has a Sn / (Zn + Sn) ratio of 0.29 to 0.39, a Ta / (Zn + Sn + Ge + Ta) ratio of 0.0005 to 0.01, and a Ge / (Zn + Sn + Ge + Ta) ratio of 0. 0.2. It is 001 or more and 0.04 or less. Preferably, Sn / (Zn + Sn) is 0.31 or more and 0.36 or less, Ta / (Zn + Sn + Ge + Ta) is 0.002 or more and 0.003 or less, and Ge / (Zn + Sn + Ge + Ta) is 0.004 or more in metal atom number ratio. .006 or less.

  In particular, by setting the atomic ratio ratio Ge / (Sn + Zn + Ge + Ta) to the total amount of all metallic elements of Ge to 0.004 or more and 0.006 or less, the film structure becomes a dense amorphous film, and the unevenness on the film surface is improved. Because you can do it. Thereby, gas permeation can be prevented, and the gas barrier performance can be improved.

  In addition, the surface of the transparent oxide film has a center line average surface roughness (Ra) of 0.6 nm or less. The center line average surface roughness (Ra) of the surface of the transparent oxide film is measured by an atomic force microscope (for example, manufactured by Digital Instruments Corporation), and the concave and the convex from the center line in the 1 μm × 1 μm region of the film surface Indicates the average value of the height with.

  By the way, although a film sputtered using a sputtering target composed of a Sn-Z-O-based oxide sintered body to which Ge is not added is an amorphous film, the film surface has irregularities, and the center line average surface is rough. (Ra) is 1.5 to 2.0 nm. That is, such a film is inferior in the gas barrier property because the smoothness of the film surface is inferior. On the other hand, by setting the ratio of Sn and Zn appropriately to the Sn-Z-O-based oxide sintered body and adding Ge, sputtering was performed using a sputtering target composed of the oxide sintered body. The center line average surface roughness (Ra) of the film is improved to 0.6 nm or less. Therefore, in the present embodiment, it is possible to prevent the permeation of gases such as oxygen and water vapor by smoothing the film surface.

  In addition, a transparent oxide film is generally used by laminating a plurality of other transparent films. For this reason, if there are fine projections on the surface, for example, when a transparent conductive film is laminated, a part of the current may flow intensively at the projections and leak may occur. Therefore, leakage can be suppressed by reducing the surface roughness of the transparent film.

  Also, in this embodiment described later, a transparent oxide film is formed by sputtering on a film substrate, but the surface roughness on the film substrate is not affected, and the surface roughness is higher than the surface roughness on the film substrate. Can be made smaller. That is, the transparent oxide film is excellent in coverage. It is possible that the transparent oxide film is a dense amorphous film and is not affected by the surface roughness of the film under the laminated film. In particular, when used as the outermost layer of a plasma electrode film or the like, the central layer average surface roughness Ra of the surface layer can be made 0.6 nm or less without affecting the central line average surface roughness of the lower film. It is possible to generate stable plasma.

The transparent oxide film according to the present embodiment has an insulating property. Such a transparent oxide film is often used as a barrier layer. This is often laminated simultaneously with the transparent conductive film, and the barrier layer is required to have insulation. The insulating property of the barrier layer is often evaluated as the surface resistance of the film, and the surface resistance of the film is preferably 1.0 × 10 ¹⁰ Ω / □ or more and 5.0 × 10 ¹² Ω / □ or less. Within this range, when the transparent electrode film and the transparent oxide film which is a barrier layer are laminated when used for an EL display element, the current does not leak to the transparent oxide film side. That is, such a transparent oxide film can ensure insulation.

[3-2. Method for producing amorphous transparent oxide film]
Next, a method of manufacturing an amorphous transparent oxide film according to an embodiment of the present invention will be described. In this embodiment, sputtering is performed using the above-described sputtering target to form a film on a substrate. The sputtering apparatus is not particularly limited, but a DC magnetron sputtering apparatus or the like can be used.

  Although it does not specifically limit as a base material, For example, a glass plate, a quartz plate, a resin plate, or a resin film etc. are mentioned. Since a transparent film is used as a barrier layer, it is particularly effective for a resin plate or a resin film. Examples of the material constituting the resin plate or resin film include polyethylene terephthalate (PET), polyether sulfone (PES), polyarylate (PAR), polycarbonate (PC), cycloolefin polymer (COP) and the like. It may be a resin plate or a resin film having a structure in which an acrylic resin is coated on the surface of.

  The thickness of the substrate is not particularly limited, but in the case of a glass plate or quartz plate, it is 0.5 to 10 mm, preferably 1 to 5 mm, and in the case of a resin plate or resin film, 0.1 5 mm, preferably 1 to 3 mm. If the thickness of the substrate is smaller than the above range, the strength of the substrate is weak and the handling is also difficult.

Next, the conditions for sputtering will be described. Sputtering adjusts the degree of vacuum in the chamber to 1 × 10 ⁻⁴ Pa or less. The atmosphere in the chamber introduces an inert gas. The inert gas is argon gas or the like, and the purity is preferably 99.999% by mass or more. In addition, the inert gas contains 6 to 10% by volume of oxygen relative to the total gas flow rate. Since the oxygen concentration affects the surface resistance of the film as described above, the oxygen concentration is set to be a predetermined resistance. Thereafter, a predetermined direct current power source is used to supply between the sputtering target and the base material to generate plasma by direct current pulsing, thereby performing film formation by sputtering. In addition, as for the film thickness on a base material, 50-200 nm is preferable. The film thickness is controlled by the film formation time.

The surface resistance of the film depends on the specific resistance of the target and the oxygen concentration at the time of sputtering. The specific resistance value of the target is preferably 1000 Ω · cm or more and 13000 Ω · cm or less from the productivity of sputtering or the like as described above. The surface resistance value of the film is 1.0 × 10 ¹⁰ Ω / □ or more and 5.0 × 10 ¹² Ω or more by adjusting the oxygen concentration when sputtering using this target to 6% by volume or more and 10% by volume or less. It becomes possible to make / □ or less. The oxygen concentration during sputtering is preferably 6% by volume or more and 10% by volume or less. If the oxygen concentration exceeds 10% by volume, it becomes difficult to control the oxygen concentration, and the characteristics of the formed film may vary. In addition, under such circumstances, the deposition rate is reduced, and the productivity is reduced. Conversely, if the oxygen concentration is less than 6% by volume, the permeability of the membrane decreases. Therefore, the oxygen concentration is preferably 10% by volume or less, and the quality of the film is stable when the oxygen concentration is 6% by volume or more and 10% by volume or less.

[4. Summary]
The amorphous transparent oxide film according to the present embodiment contains Zn and Sn, and further contains Ge and Ta. And Sn / (Zn + Sn) is 0.29-0.39, Ta / (Zn + Sn + Ge + Ta) is 0.0005-0.01, Ge / (Zn + Sn + Ge + Ta) is 0.001 or more by metal atom number ratio. It is characterized by being 04 or less.

  Such an amorphous transparent oxide film has good surface smoothness and excellent insulation. Furthermore, since the transparent oxide film has good surface smoothness, it does not transmit oxygen and water, so it is excellent in gas barrier properties. Thus, the transparent oxide film can be used for EL display, liquid crystal display, and the like.

  The Sn-Zn-O-based oxide sintered body according to the present embodiment is a Sn-Zn-O-based oxide sintered body used for forming the above-mentioned amorphous transparent oxide film by sputtering. And contains Zn and Sn as main components, and further contains Ge and Ta. And Sn / (Zn + Sn) is 0.29-0.39, Ta / (Zn + Sn + Ge + Ta) is 0.0005-0.01, Ge / (Zn + Sn + Ge + Ta) is 0.001 or more by metal atom number ratio. It is characterized by being 04 or less.

  When such an oxide sintered body is used as a sputtering target for sputtering, it is possible to obtain a transparent oxide film which is excellent in surface smoothness and excellent in insulation. Furthermore, even when sputtering is performed using a sputtering target formed of a target material made of this oxide sintered body, the production efficiency can be improved and stable film formation can be achieved, which is of great industrial significance.

  EXAMPLES Hereinafter, the present invention will be more specifically described using examples, but the present invention is not limited to the following examples.

Example 1
In Example 1, SnO ₂ powder, ZnO powder, Ta ₂ O ₅ powder as the first additive element Ta, and GeO ₂ powder as the second additive element Ge were prepared.

Next, SnO ₂ powder and ZnO powder are mixed so that the atomic ratio Sn / (Sn + Zn) of Sn to Zn is 0.33, and the atomic ratio Ta / (Sn + Zn + Ge + Ta) of the first additive element Ta is 0. The Ta ₂ O ₅ powder and the GeO ₂ powder were mixed so that the atomic number ratio Ge / (Sn + Zn + Ge + Ta) of the second additive element Ge was 0.005.

Then, the prepared raw material powder, pure water, an organic binder, a dispersant, and an antifoaming agent were mixed in a mixing tank so that the raw material powder concentration would be 55 to 65% by mass. Next, using a bead mill apparatus (Ashizawa Finetech Co., Ltd., LMZ type) loaded with hard ZrO ₂ balls, wet grinding is performed until the average particle size of the raw material powder becomes 1 μm or less, and then 10 hours The above mixture was mixed and stirred to obtain a slurry. For measurement of the average particle diameter of the raw material powder, a laser diffraction type particle size distribution measuring apparatus (manufactured by Shimadzu Corporation, SALD-2200) was used.

  The obtained slurry was sprayed and dried by a spray dryer apparatus (manufactured by Ogawara Kako Co., Ltd., ODL-20 type) to obtain granulated powder.

Next, the obtained granulated powder is filled into a rubber mold and molded by a cold isostatic press under a pressure of 294 MPa (3 ton / cm ² ), and the obtained compact having a diameter of about 250 mm is pressure-baked The furnace was introduced and air was introduced into the sintering furnace up to 700 ° C. After confirming that the temperature in the firing furnace had reached 700 ° C., oxygen was introduced, the temperature was raised to 1350 ° C., and the temperature was maintained at 1350 ° C. for 20 hours. The temperature rising rate at this time was 0.7 ° C./min.

  After the holding time ended, the introduction of oxygen was stopped and cooling was performed to obtain a Sn—Zn—O-based oxide sintered body according to Example 1.

  Next, the Sn—Zn—O-based oxide sintered body according to Example 1 was processed to a diameter of 200 mm and a thickness of 5 mm using a surface grinder and a gliding center.

  The density of this processed body was measured by the Archimedes method, and the relative density was 96%. Moreover, it was 3000 ohm * cm when specific resistance was measured by the 4 probe method.

Moreover, a part of this processed body was cut and ground into a powder by mortar grinding. As a result of analyzing this powder with an X-ray diffraction apparatus (manufactured by PANalytical, X'Pert-PRO) using CuKα rays, it is found that 99.0% of Zn ₂ SnO ₄ phase of spinel type crystal structure and wurtzite type crystal structure The SnO ₂ phase of is diffracted to 1.0% of the whole, and the diffraction peaks of other compound phases are not measured. The results are shown in Table 1 below.

  Next, a sputtering target was produced using this sintered body. First, a sintered body processed into a predetermined size was bonded to a backing plate made of stainless steel using a bonding material of indium (In). Thus, a sputtering target was obtained.

Next, sputtering was performed by a sputtering apparatus using this sputtering target to form a film. As this sputtering apparatus, a DC magnetron sputtering apparatus (SPK 503 manufactured by Tokki Co., Ltd.) was used. The formation of the amorphous oxide film was performed under the following conditions. The target was attached to the cathode, and the resin film substrate was placed directly on the cathode. The distance between the target and the resin film substrate was 60 mm. As a resin film substrate, a COP film without an undercoat (manufactured by Zeon, thickness 0.2 mm) was used. When the degree of vacuum in the chamber reaches 1 × 10 ^-4 Pa or less, argon gas having a purity of 99.9999% by mass is introduced into the chamber to achieve a gas pressure of 0.6 Pa, and contains 6 to 10% by volume of oxygen DC power of 200 W employing 200 kHz DC pulsing is applied between the sputtering target and the resin film substrate using a DC power supply (RPG-50, manufactured by ENI) as a DC power supply in the argon gas supplied. Plasma was generated by direct current pulsing, and a transparent oxide film with a film thickness of 50 nm was formed on the resin film substrate by sputtering.

Further, the crystallinity of the transparent oxide film prepared above was measured by X-ray diffraction to observe a diffraction peak. Furthermore, the resistivity was measured by the four probe method. Further, the center line average roughness Ra of the 1 μm × 1 μm region of the film surface was measured at 20 locations in the sample by an atomic force microscope (NS-III, D5000 system, manufactured by Digital Instruments), and the average value was determined. The results are shown in Table 2 below. In addition, the surface roughness of the film-forming surface of the COP film was Ra 0.74 nm and R _max 6.8 nm.

  Moreover, when the film composition of the obtained transparent oxide film was measured by ICP emission analysis, it was the same metal component ratio as the composition of the oxide sintered body.

(Examples 2 to 9)
In Examples 2 to 9, the atomic number ratio Sn / (Sn + Zn) of Sn and Zn to the atomic number ratio Ta / (Sn + Zn + Ge + Ta + Ga) of the first additive element Ta and the second additive element Ge shown in Table 1 A sintered body was produced in the same manner as in Example 1 except that SnO ₂ powder, ZnO powder, GeO ₂ powder, and Ta ₂ O ₅ powder were prepared so as to have an atomic ratio of Ge / (Sn + Zn + Ge + Ta + Ga). did. Table 1 shows the results of the relative density of the sintered body, the specific resistance, and the amount of the compound analyzed by an X-ray diffractometer using a CuKα ray.

  Moreover, the target was produced using the sintered compact obtained in Example 2-Example 9. The film thickness at the time of sputtering using this target was adjusted to be the thickness shown in Table 2, and a transparent oxide film was formed on the COP film in the same manner as in Example 1 except the above. The results of the crystallinity, specific resistance, and surface roughness of the transparent oxide film are shown in Table 2.

  Moreover, when the film composition of the obtained transparent oxide film was measured by ICP emission analysis, it was the same metal component ratio as the composition of the oxide sintered body.

  Furthermore, in the 1 μm square area of the surface of the transparent oxide film obtained in Example 2, an SPM observation image shown in FIG. 2 was confirmed by a scanning probe microscope. The surface of the COP film which is not overcoated is shown in FIG. 3 as an SPM observation image, and the AZO film (a zinc oxide film to which 0.09 atm% aluminum is added, the film is a crystalline film) formed on the COP film. The surface is shown in FIG. 4 as an SPM observation image.

(Comparative Example 1 to Comparative Example 7)
In Comparative Examples 1 to 7, the atomic number ratio Sn / (Sn + Zn) of Sn and Zn to the atomic number ratio Ta / (Sn + Zn + Ge + Ta + Ga) of the first additive element Ta and the atomic number of the second additive element Ge shown in Table 1 A target was produced in the same manner as in Example 1 except that SnO ₂ powder, ZnO powder, GeO ₂ powder, and Ta ₂ O ₅ powder were blended so as to obtain the ratio Ge / (Sn + Zn + Ge + Ta + Ga). In addition, the relative density of a target, a specific resistance, and the result of the compound amount analyzed with the X-ray-diffraction apparatus using a CuK alpha ray are shown in Table 1.

  Moreover, the target was produced using the sintered compact obtained by Comparative Example 1-Comparative Example 5. The film thickness at the time of sputtering using this target was adjusted to be the thickness shown in Table 2, and a transparent oxide film was formed on the COP film in the same manner as in Example 1 except the above. The results of the crystallinity, specific resistance, and surface roughness of the transparent oxide film are shown in Table 2.

  Furthermore, in the 1 μm square range of the surface of the transparent oxide film obtained in Comparative Example 4, an SPM observation image shown in FIG. 5 was confirmed by a scanning probe microscope.

  On the other hand, although sputtering was performed using the targets obtained in Comparative Examples 6 to 7, the conductivity of the targets is poor, so discharge can not be performed during film formation, and film formation can not be performed on the COP film. The Therefore, the specific resistance and the surface roughness of the transparent oxide film could not be measured.

  The film composition of the obtained transparent oxide film was measured by ICP emission analysis, and the metal component ratio was the same as the composition of the oxide sintered body.

(Consideration by example)
From Table 2, the film of the present invention formed by sputtering using the target manufactured in Table 1 has a surface resistance when the oxygen concentration during sputtering is 6% by volume to 10% by volume with respect to the total gas flow rate. It was a high resistance film with 1.0 × 10 ¹⁰ Ω · cm or more and 5.0 × 10 ¹² Ω · cm or less, and the center line average surface roughness of the transparent oxide film surface was 0.6 nm or less. Thereby, it confirmed that the surface of the transparent oxide film obtained by Examples 1-9 is smooth. In particular, when using a sputtering target composed of an oxide sintered body having an atomic ratio of Sn / (Sn + Zn) of 0.33, the transparent oxide film formed by sputtering has a surface resistance and a center. It was confirmed that the line average surface height was excellent.

  Moreover, as a result of comparing FIG. 2 and FIG. 3, the surface roughness of the transparent oxide film formed into a film on this film substrate was smaller than the surface roughness of a film substrate. Therefore, it was confirmed that the target used in Example 2 had excellent coverage when it was sputtered. Furthermore, as a result of comparing FIG. 2 and FIG. 4, when sputtering is performed using the sputtering target obtained in Example 2, transparent oxide is formed when the film is formed more than a sputtering target formed of a target material made of AZO. It was confirmed that the surface of the object film was smooth.

  On the other hand, in Comparative Examples 1 to 5, it was confirmed that the surface resistance value or the surface roughness was inferior as compared with Examples 1 to 9. Further, in Comparative Example 4, FIG. 5 and FIG. 2 were compared, and it was confirmed that the film surface was not smoother than Example 2 because the metal atom number ratio was not within the predetermined range.

  In addition, although one embodiment and each example of the present invention were explained in detail as mentioned above, it is possible for a person skilled in the art that many modifications can be made without departing substantially from the novel item and the effect of the present invention. It will be easy to understand. Accordingly, all such modifications are intended to be included within the scope of the present invention.

  For example, in the specification or the drawings, the terms described together with the broader or synonymous different terms at least once can be replaced with the different terms anywhere in the specification or the drawings. In addition, a Sn-Zn-O-based oxide sintered body, an amorphous transparent oxide film, a method for producing a Sn-Zn-O-based oxide sintered body, and a method for producing an amorphous transparent oxide film The configuration of the present invention is not limited to those described in the embodiment and each example of the present invention, and various modifications can be made.

S1 granulation process, S2 forming process, S3 firing process

Claims (9)

It is an amorphous transparent oxide film containing Zn and Sn,
Further contains Ge and Ta,
The metal atom ratio,
Sn / (Zn + Sn) is 0.29 or more and 0.39 or less,
Ta / (Zn + Sn + Ge + Ta) is not less than 0.0005 and not more than 0.01,
Ge / (Zn + Sn + Ge + Ta) is 0.001 or more and 0.04 or less,
An amorphous transparent oxide film characterized by being. In the metal atom number ratio,
Sn / (Zn + Sn) is 0.31 or more and 0.36 or less,
Ta / (Zn + Sn + Ge + Ta) is 0.002 or more and 0.003 or less,
Ge / (Zn + Sn + Ge + Ta) is 0.004 or more and 0.006 or less,
The amorphous transparent oxide film according to claim 1, wherein 3. The amorphous transparent oxide film according to claim 1, wherein the surface resistance is 1.0 × 10 ¹⁰ Ω / sq or more and 5.0 × 10 ¹² Ω / sq or less.   4. The amorphous transparent oxide film according to any one of claims 1 to 3, wherein a center line average surface roughness Ra of the surface is 0.6 nm or less. It is a Sn—Zn—O-based oxide sintered body used for forming an amorphous transparent oxide film according to any one of claims 1 to 4 by sputtering.
Containing Zn and Sn as main components, and further containing Ge and Ta,
The metal atom ratio,
Sn / (Zn + Sn) is 0.29 or more and 0.39 or less,
Ta / (Zn + Sn + Ge + Ta) is not less than 0.0005 and not more than 0.01,
Ge / (Zn + Sn + Ge + Ta) is 0.001 or more and 0.04 or less,
Sn-Zn-O-based oxide sintered body characterized in that Zn ₂ Sn-Zn-O-based oxide sintered body according to claim 5, SnO ₄ phase is characterized in that it is composed of more than 90%.   The specific resistance is 1000 ohm * cm or more and 13000 ohm * cm or less, The Sn-Zn-O type oxide sinter of Claim 5 or 6 characterized by the above-mentioned. A method for producing an amorphous transparent oxide film containing Zn and Sn, comprising:
An amorphous transparent film formed by a sputtering method using a sputtering target comprising the Sn-Zn-O-based oxide sintered body according to any one of claims 5 to 7. Method of manufacturing oxide film. A method for producing a Sn-Zn-O-based oxide sintered body according to any one of claims 5 to 7,
A granulating step of mixing an oxide powder of zinc, an oxide powder of tin, and an oxide powder containing an additive element to produce a granulated powder,
A forming step of obtaining a formed body by pressure forming the granulated powder;
A firing step of firing the compact to obtain an oxide sintered body;
In the granulation step, the metal atom number ratio is
Sn / (Zn + Sn) is 0.29 or more and 0.39 or less,
Ta / (Zn + Sn + Ge + Ta) is not less than 0.0005 and not more than 0.01,
Ge / (Zn + Sn + Ge + Ta) is 0.001 or more and 0.04 or less,
An Sn—Zn—O system characterized in that the granulated powder is prepared by mixing the oxide powder of zinc, the oxide powder of tin, and the oxide powder containing the additive element so as to be Method of producing oxide sintered body

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