JP2012142535A - Patterning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a patterning method sufficiently low in an etching rate in patterning a zinc oxide thin film, capable of easily and reliably controlling the etching rate, and capable of obtaining a zinc oxide thin film having a good pattern shape and also high in conductivity.SOLUTION: A patterning method of the present invention is a method for patterning a zinc oxide thin film by etching the zinc oxide thin film with an acid. The zinc oxide thin film contains zinc oxide as a main component, and has an atomic ratio Ti/(Zn+Ti) of titanium to the sum of zinc and titanium of greater than 0.02 and 0.1 or less. The zinc oxide thin film is preferably deposited using a target, which is obtained by processing an oxide sintered body or an oxide mixture which are substantially composed of zinc, titanium and oxygen, as a film forming martial.

Description

  The present invention relates to a method for patterning a zinc oxide-based thin film containing zinc oxide as a main component.

Transparent conductive films that combine electrical conductivity and light transmission have been used as electrodes in solar cells, liquid crystal display elements, and other various light receiving elements, as well as automotive window and heat ray reflective films for buildings, It is used for a wide range of applications such as anti-static films and transparent heating elements for anti-fogging in frozen showcases.
In particular, it is known that a transparent conductive film having a low resistance and excellent conductivity is suitable for a solar cell, a liquid crystal display element such as a liquid crystal, organic electroluminescence, and inorganic electroluminescence, a touch panel, and the like.

Conventionally, as the transparent conductive film, for example, a tin oxide (SnO ₂ ) -based thin film, a zinc oxide (ZnO) -based thin film, and an indium oxide (In ₂ O ₃ ) -based thin film are known.
Specifically, as the tin oxide-based transparent conductive film, an antimony-doped tin oxide (ATO) film using antimony as a dopant and a fluorine-doped tin oxide (FTO) film using fluorine as a dopant are known, and oxidation Known zinc-based transparent conductive films include aluminum-doped zinc oxide (AZO) films using aluminum as a dopant and gallium-doped zinc oxide (GZO) films using gallium as a dopant. Is known as a tin-doped indium oxide (ITO) film using tin as a dopant. Among them, the most industrially used is an indium oxide-based transparent conductive film, and in particular, an ITO film is widely used because of its low resistance and excellent conductivity.

  However, an indium oxide-based transparent conductive film such as an ITO film is expensive and may be depleted of resources because In (indium), which is an essential raw material, is a rare metal, and has toxicity and is harmful to the environment and the human body. In recent years, there is a demand for an industrially versatile transparent conductive film that can be substituted for an ITO film because it may adversely affect the film.

  As the non-indium oxide-based transparent conductive film, as described above, zinc oxide-based transparent conductive films such as AZO and GZO and tin oxide-based transparent conductive films such as ATO and FTO are known. In particular, zinc oxide-based transparent conductive films are industrially manufactured by a sputtering method or the like.

However, since the zinc oxide-based transparent conductive film has poor chemical resistance (acid resistance, alkali resistance), the zinc oxide-based transparent conductive film can be patterned in a desired shape, for example, when used as an element. When necessary, there is a problem that an appropriate wet etching solution does not exist and patterning cannot be performed satisfactorily. Specifically, because zinc oxide has a very high dissolution rate in acids and alkalis, etching with an acid or alkali on a zinc oxide-based transparent conductive film results in a very high etching rate. (Specifically, it is 100 times faster than the ITO film) It dissolved immediately and a good pattern shape could not be obtained.
On the other hand, tin oxide-based transparent conductive films are excellent in chemical resistance (acid resistance and alkali resistance) and are extremely stable against acids and alkalis. Therefore, there is a problem that patterning cannot be performed by wet etching.
Therefore, the zinc oxide-based transparent conductive film and the tin oxide-based transparent conductive film have hitherto been disadvantageous that they can only be used for applications that can be used as so-called solid films.

  Therefore, as a means for enabling patterning of a zinc oxide-based thin film, it has been proposed that a specific acid can be used as an etchant and a specific additive element can be doped to reduce the etching rate (Patent Document 1). ). Specifically, an example of etching a zinc oxide thin film doped with Zn at 6 at% (here, “at%” is the number of zinc and additive elements with respect to 100), and ZnO was doped with 3 at% Ti. An example of etching a zinc oxide-based thin film is disclosed.

JP 2008-159814 A

  However, the zinc oxide-based thin film disclosed in Patent Document 1 may have an insufficient etching rate suppression effect, making it difficult to reliably control the etching rate, and this thin film is replaced with an ITO film. When it is intended to be used as a conductive film, the conductivity is not always at a satisfactory level.

  Accordingly, an object of the present invention is that the etching rate when patterning a zinc oxide-based thin film is sufficiently low, the etching rate can be easily and reliably controlled, and has a good pattern shape and high conductivity. It is providing the patterning method which can obtain a zinc oxide type thin film.

  As a result of intensive studies to solve the above problems, the inventor of the present invention, when etching and patterning a zinc oxide-based thin film mainly composed of zinc oxide with an acid, titanium was added to this thin film at an atomic ratio of Ti / It has been found that by containing (Zn + Ti) = 0.02 to 0.1 or less, the etching rate can be significantly reduced, and the conductivity of the film is increased, and the present invention has been completed. .

That is, this invention consists of the following structures.
(1) A method in which a zinc oxide thin film is patterned by etching with an acid, wherein the zinc oxide thin film contains zinc oxide as a main component, and the atomic ratio of titanium to the total of zinc and titanium Ti / (Zn + Ti ) Is a thin film of more than 0.02 and 0.1 or less.
(2) The zinc oxide-based thin film is formed by using a target obtained by processing an oxide sintered body or an oxide mixture substantially composed of zinc, titanium, and oxygen as a film forming material. The patterning method according to (1) above.
(3) The patterning method according to (2), wherein the titanium is titanium derived from low-valent titanium oxide represented by a formula TiO _{2 -X} (X = 0.1-1).
(4) The patterning method according to (3), wherein the low-valence titanium oxide is titanium oxide (TiO) made of divalent titanium or titanium oxide (Ti ₂ O ₃ ) made of trivalent titanium.
(5) The patterning method according to any one of (1) to (4), wherein the zinc oxide-based thin film is a film formed by a vacuum film forming method.
(6) The patterning method according to (5), wherein the vacuum film forming method is a sputtering method, an ion plating method, a pulse laser deposition method (PLD method), or an electron beam (EB) vapor deposition method.

  According to the present invention, a zinc oxide thin film having a good pattern shape and high conductivity can be obtained. Specifically, according to the present invention, since the etching rate when patterning a zinc oxide thin film is sufficiently low, the etching rate can be easily controlled, and as a result, a pattern having a desired shape can be easily and reliably formed. it can. Further, the patterned zinc oxide thin film obtained in the present invention has high conductivity, and can be suitably used as an alternative conductive film for the ITO film, which is a rare metal and has toxic indium.

  The patterning method of the present invention is a method of patterning a zinc oxide thin film having a specific composition by etching with an acid. Hereinafter, the zinc oxide thin film having this specific composition will be described in detail.

The zinc oxide-based thin film in the present invention is a thin film containing zinc oxide as a main component and having an atomic ratio Ti / (Zn + Ti) of titanium with respect to the total of zinc and titanium of more than 0.02 and not more than 0.1. Specifically, this zinc oxide-based thin film is a solution in which titanium is substituted and dissolved in a zinc site of a zinc oxide wurtzite crystal structure. Here, it is preferable that zinc oxide as the main component occupies 99% or more of all atoms constituting the film.
Specifically, the zinc oxide thin film is preferably formed using a target obtained by processing an oxide sintered body or an oxide mixture substantially composed of zinc, titanium, and oxygen as a film forming material. . Here, “substantially” means that 99% or more of all atoms constituting the oxide sintered body are composed of zinc, titanium, and oxygen.

  As for the content of titanium contained in the zinc oxide-based thin film, the atomic ratio Ti / (Zn + Ti) of titanium to the total of zinc and titanium is more than 0.02 and 0.1 or less. If the value of Ti / (Zn + Ti) is 0.02 or less, the doping effect of titanium is insufficient, the etching rate cannot be kept sufficiently low, and the conductivity of the film is also insufficient. On the other hand, when the value of Ti / (Zn + Ti) exceeds 0.1, titanium cannot be dissolved in the zinc site and the crystallinity is lowered, and the mobility is lowered due to the impurity scattering factor. Will drop. Preferably Ti / (Zn + Ti) is 0.025 to 0.09, more preferably Ti / (Zn + Ti) is 0.03 to 0.08.

(Oxide sintered body)
The oxide sintered body in the present invention is preferably composed of a zinc oxide phase and a zinc titanate compound phase, or composed of a zinc titanate compound phase. If the zinc titanate compound phase is contained in the oxide sintered body in this way, the strength of the oxide sintered body itself increases, so that, for example, a film can be formed under severe conditions (high power, etc.) as a target. No cracks.
Here, the zinc titanate compound phase specifically includes ZnTiO ₃ , Zn ₂ TiO ₄ , those in which titanium element is dissolved in these zinc sites, and oxygen vacancies are introduced. And those having a non-stoichiometric composition in which the Zn / Ti ratio is slightly deviated from these compounds.
In addition, the zinc oxide phase specifically includes ZnO, a solution in which a titanium element is dissolved, an oxygen deficiency introduced, or a non-stoichiometric composition due to zinc deficiency. Including things. The zinc oxide phase usually has a wurtzite structure.

It is preferable that the oxide sintered body in the present invention does not substantially contain a titanium oxide crystal phase (hereinafter sometimes referred to as a titanium oxide phase).
If the oxide sintered body contains a crystal phase of titanium oxide, the resulting film may be uneven in physical properties such as specific resistance and lack uniformity. In the oxide sintered body according to the present invention, since the value of Ti / (Zn + Ti) described above is 0.1 or less, usually titanium completely reacts with zinc oxide, and titanium oxide crystals are contained in the oxide sintered body. The phase is difficult to generate.
Note that the crystal phase of titanium oxide specifically includes TiO ₂ , Ti ₂ O ₃ , and TiO, as well as substances in which other elements such as Zn are dissolved in these crystals.

The oxide sintered body in the present invention contains at least one element selected from the group consisting of gallium, aluminum, tin, silicon, germanium, zirconium, and hafnium (hereinafter, these may be referred to as “additive elements”). Is also preferably contained. By containing such an additive element, the specific resistance of the oxide sintered body itself can be reduced in addition to the specific resistance of the film formed using the oxide sintered body as a target. For example, the film formation rate during DC sputtering depends on the specific resistance of the oxide sintered body as a sputtering target, and the productivity during film formation is improved by lowering the specific resistance of the oxide sintered body itself. Can do. When an additive element is contained, the total content is preferably 0.05% or less with respect to the total amount of all metal elements constituting the oxide sintered body in terms of atomic ratio. When there is more content of an additional element than the said range, there exists a possibility that the specific resistance of the film | membrane formed using an oxide sintered compact as a target may increase.
The additive element may be present in the oxide sintered body in the form of an oxide, or may be present in a form substituted (solid solution) in the zinc site of the zinc oxide phase, The zinc titanate compound phase may exist in a form substituted (solid solution) with titanium sites and / or zinc sites.

  The oxide sintered body in the present invention may contain other elements such as indium, iridium, ruthenium, and rhenium as impurities in addition to the essential elements zinc and titanium and the additive elements. The total content of elements contained as impurities is preferably 0.5% or less in terms of atomic ratio with respect to the total amount of all metal elements constituting the oxide sintered body.

  The specific resistance of the oxide sintered body in the present invention is preferably 5 kΩ · cm or less. For example, the deposition rate during direct current sputtering depends on the specific resistance of the oxide sintered body as a sputtering target. Therefore, if the specific resistance of the oxide sintered body exceeds 5 kΩ · cm, stable formation by direct current sputtering is possible. There is a possibility that the film cannot be formed. Considering the productivity at the time of film formation, the specific resistance of the oxide sintered body in the present invention is preferably as low as possible, and specifically 100 Ω · cm or less.

  The oxide sintered body in the present invention as described above is preferably obtained by the method for producing an oxide sintered body in the present invention described later, but is not limited to those obtained by the production method. For example, a combination of titanium metal and zinc oxide powder or zinc hydroxide powder, or a combination of titanium oxide and zinc metal may be obtained as a raw material powder. Normally, when the oxide sintered body is sintered in a reducing atmosphere, the specific resistance of the oxide sintered body is reduced by introducing oxygen deficiency, and when the oxide sintered body is sintered in an oxidizing atmosphere, the specific resistance is high. Become.

(Method for manufacturing oxide sintered body)
The method for producing an oxide sintered body in the present invention was obtained after molding a raw material powder containing a mixed powder of titanium oxide powder and zinc oxide powder or zinc hydroxide powder and / or a zinc titanate compound powder. This is a method for obtaining the above-described oxide sintered body in the present invention by sintering the compact.
The raw material powder may be a mixture powder of titanium oxide powder, zinc oxide powder or zinc hydroxide powder, or a powder containing zinc titanate compound powder. Titanium oxide powder, zinc oxide powder or hydroxide A mixed powder of zinc powder and zinc titanate compound powder may be used. Preferably, a powder containing a mixed powder of titanium oxide powder and zinc oxide powder or zinc hydroxide powder is preferable.
As described above, the oxide sintered body in the present invention can be obtained by using, for example, a combination of titanium metal and zinc oxide powder or zinc hydroxide powder, or a combination of titanium oxide and zinc metal powder as a raw material powder. However, in this case, titanium and zinc metal particles are likely to be present in the oxide sintered body, and when this is used as a target, the metal particles on the target surface melt during the film formation. The composition of the film obtained and the composition of the target tend to be greatly different.

Examples of the titanium oxide powder include titanium oxide (TiO ₂ ) made of tetravalent titanium, titanium oxide (Ti ₂ O ₃ ) made of trivalent titanium, and titanium oxide (TiO) made of divalent titanium. Among them, a low-valent titanium oxide powder not containing TiO ₂ (IV) is preferable, and a Ti ₂ O ₃ powder is particularly preferable. Because the crystal structure of Ti ₂ O ₃ is trigonal and the zinc oxide mixed with it is hexagonal wurtzite, the symmetry of the crystal structure is the same, and the solid solution is substituted during solid phase sintering. Because it is easy to do.
Low valence titanium oxide includes not only those having an integer valence of TiO (II) and Ti ₂ O ₃ (III), but also Ti ₃ O ₅ , Ti ₄ O ₇ , Ti ₆ O ₁₁ , and Ti ₅ O. ₉ , Ti ₈ O _{15 and the} like are also represented by the formula TiO _2-X (X = 0.1-1). The structure of the low valence titanium oxide can be confirmed by the results of instrumental analysis such as an X-ray diffraction apparatus (X-ray diffraction, XRD), an X-ray photoelectron spectrometer (X-ray Photoelectron Spectroscopy, XPS).

The low-valent titanium oxide represented by the formula TiO _2-X (X = 0.1-1) may be a mixture of low-valent titanium oxide. Usually, it can be produced by heating titanium oxide (TiO ₂ ) in a reducing atmosphere such as a hydrogen atmosphere using carbon or the like as a reducing agent. By adjusting the hydrogen concentration, the amount of carbon as a reducing agent, and the heating temperature, the ratio of the low-valent titanium oxide mixture can be controlled.

As the zinc oxide powder, a powder of ZnO or the like having a wurtzite structure is usually used, and a powder obtained by firing this ZnO in advance in a reducing atmosphere and containing oxygen deficiency may be used.
The zinc hydroxide powder may be either amorphous or crystalline.
As the zinc titanate compound powder, for example, a powder of ZnTiO ₃ , Zn ₂ TiO ₄ or the like can be used, and it is particularly preferable to use a powder of Zn ₂ TiO ₄ .
The average particle size of each compound (powder) used as the raw material powder is preferably 5 μm or less.

  When a mixed powder of titanium oxide powder and zinc oxide powder or zinc hydroxide powder is used as the raw material powder, or a mixed powder of titanium oxide powder, zinc oxide powder or zinc hydroxide powder, and zinc titanate compound powder The mixing ratio of each powder in the case of using is the range in which the value of Ti / (Zn + Ti) in the atomic ratio in the finally obtained oxide sintered body depends on the type of the compound (powder) used. What is necessary is just to set suitably so that. At that time, considering that zinc has a higher vapor pressure than titanium and is likely to be volatilized when sintered, the desired composition of the desired oxide sintered body (atomic ratio of Zn and Ti), It is preferable to set the mixing ratio in advance so that the amount of zinc increases. Specifically, the easiness of volatilization of zinc varies depending on the atmosphere during sintering.For example, when zinc oxide powder is used, only the volatilization of zinc oxide powder itself occurs in an air atmosphere or an oxidizing atmosphere. When sintered in a reducing atmosphere, the zinc oxide is reduced and becomes metal zinc that is more easily volatilized than zinc oxide, so the amount of zinc lost increases (however, as described later, it is once sintered) After that, when annealing is performed in a reducing atmosphere, zinc is already difficult to evaporate because it is already a complex oxide at the time of annealing. Therefore, the amount of zinc to be increased with respect to the target composition may be set in consideration of the sintering atmosphere or the like. For example, it is desirable when sintering is performed in an air atmosphere or an oxidizing atmosphere. What is necessary is just to be about 1.1 to 1.3 times the amount of the desired atomic number ratio when sintering in a reducing atmosphere, about 1.0 to 1.05 times the amount of the atomic number ratio. In addition, each compound (powder) used as the raw material powder may be only one kind or two or more kinds.

The method for forming the raw material powder is not particularly limited. For example, the raw material powder and an aqueous solvent are mixed, and the resulting slurry is sufficiently mixed by wet mixing. What is necessary is just to dry and granulate and shape | mold the obtained granulated material.
The wet mixing may be performed by, for example, a wet ball mill using a hard ZrO ₂ ball or a vibration mill, and the mixing time when using the wet ball mill or the vibration mill is preferably about 12 to 78 hours. In addition, although raw material powder may be dry-mixed as it is, wet mixing is more preferable.
For solid-liquid separation / drying / granulation, known methods may be employed.
When the obtained granulated product is molded, for example, the granulated product is put into a mold, and a pressure of 1 ton / cm ² or more is applied using a cold molding machine such as a cold press or a cold isostatic press. Can be molded. At this time, when hot forming is performed using a hot press or the like, it is disadvantageous in terms of manufacturing cost and it is difficult to obtain a large-sized sintered body. In addition, when obtaining a granulated material as a molded object, what is necessary is just to granulate by a well-known method after drying, In that case, it is preferable to mix a binder with raw material powder.
As the binder, for example, polyvinyl alcohol, vinyl acetate and the like can be used.

Sintering of the obtained compact is performed in an inert atmosphere (nitrogen, argon, helium, neon, etc.), vacuum, reducing atmosphere (carbon dioxide, hydrogen, ammonia, etc.), air atmosphere and oxidizing atmosphere (oxygen concentration is higher than air). High atmosphere) at 600 to 1500 ° C. Then, when sintering is performed in an air atmosphere or an oxidizing atmosphere, annealing is further performed in an inert atmosphere, a vacuum, or a reducing atmosphere.
Annealing treatment in a reducing atmosphere that is performed after sintering in an air atmosphere or an oxidizing atmosphere is performed in order to cause oxygen deficiency in the oxide sintered body and lower the specific resistance. Accordingly, it is needless to say that the annealing treatment is preferably performed after the sintering when it is desired to further reduce the specific resistance even when the sintering is performed in an air atmosphere or a reducing atmosphere.

In sintering in any atmosphere, the sintering temperature is 600 to 1500 ° C., preferably 1000 to 1300 ° C. If the sintering temperature is lower than 600 ° C., the sintering does not proceed sufficiently, so that the target density is lowered. On the other hand, if it exceeds 1500 ° C., zinc oxide itself is decomposed and disappears. When the temperature of the molded body is raised to the sintering temperature, the rate of temperature rise is 5 to 10 ° C./min up to 600 ° C., and 1 to 4 ° C./min up to 1000 ° C. It is preferable to make the sintered density uniform.
When sintering in any atmosphere, the sintering time (that is, the holding time at the sintering temperature) is preferably 3 to 15 hours. If the sintering time is less than 3 hours, the sintered density tends to be insufficient, and the strength of the resulting oxide sintered body tends to decrease. On the other hand, if it exceeds 15 hours, the crystal grains of the sintered body As the growth becomes remarkable, there is a tendency that the pores are coarsened and consequently the maximum pore diameter is increased, and as a result, the sintered density may be lowered.
The method for performing the sintering is not particularly limited, and is a normal pressure firing method, a hot press method, a hot isostatic press method (HIP method), a cold isostatic press method (CIP method), Known methods such as a millimeter wave sintering method and a microwave sintering method can be employed.

Examples of the atmosphere for performing the annealing treatment include an atmosphere made of at least one selected from the group consisting of nitrogen, argon, helium, carbon dioxide, and hydrogen, and a vacuum.
As a method for the annealing treatment, for example, a method of heating at normal pressure while introducing a non-oxidizing gas such as nitrogen, argon, helium, carbon dioxide, or hydrogen, or heating under a vacuum (preferably 2 Pa or less). Although it can be performed by a method or the like, the former method at normal pressure is advantageous from the viewpoint of production cost.

  In performing the annealing treatment, the annealing temperature (heating temperature) is preferably 1000 to 1400 ° C., more preferably 1100 to 1300 ° C. The annealing time (heating time) is preferably 7 to 15 hours, and more preferably 8 to 12 hours. If the annealing temperature is less than 1000 ° C., introduction of oxygen deficiency due to the annealing treatment may be insufficient. On the other hand, if it exceeds 1400 ° C., zinc tends to be volatilized, and the composition of the obtained oxide sintered body There is a possibility that (the atomic ratio of Zn and Ti) is different from the desired ratio.

(Oxide mixture)
The oxide mixture in the present invention comprises zinc oxide powder and titanium oxide powder. That is, the oxide mixture in the present invention is a mixture of titanium-doped zinc oxide substantially consisting of zinc, titanium and oxygen. Here, “substantially” means that 99% or more of all atoms constituting the oxide mixture are composed of zinc, titanium and oxygen.

In the oxide mixture in the present invention, the atomic ratio Ti / (Zn + Ti) of titanium to the total of zinc and titanium is more than 0.02 and 0.1 or less. When the Ti content is such that the value of Ti / (Zn + Ti) is 0.02 or less, chemical durability such as chemical resistance of a film formed using this oxide mixture as a target becomes insufficient.
Preferably Ti / (Zn + Ti) is 0.03 to 0.09, more preferably Ti / (Zn + Ti) is 0.04 to 0.08.

As the titanium oxide powder, a low-valent titanium oxide powder containing no TiO ₂ (IV), particularly titanium oxide (III) is preferable. Zinc oxide powder usually has a wurtzite structure.
The oxide mixture in the present invention is a mixture of zinc oxide powder and titanium oxide powder, which is molded, for example, uniaxial press molding.
In order to increase the mechanical strength of the oxide mixture, the shaped oxide mixture may be heated at 600 ° C. or lower. If zinc oxide and titanium oxide are less than 600 ° C., the composite oxide is not formed by sintering.

  The low-valent titanium oxide is as described above, and a mixture of low-valent titanium oxide may be used.

However, titanium oxide (III) is oxidized in an atmosphere where oxygen exists (air atmosphere, oxidizing atmosphere) and is heated to 400 ° C. or higher, and changes to titanium oxide (IV), but oxygen does not exist. If the heating temperature is less than 600 ° C. in a reducing atmosphere or an inert atmosphere, it can exist as a mixture without sintering. Note that if it is an atmosphere in which oxygen exists (an oxidizing atmosphere or an air atmosphere), the temperature needs to be 400 ° C. or lower.
By heating in this way, the mechanical strength of the oxide mixture can be increased. Since the strength of the mixture itself increases, for example, even if a film is formed under harsh conditions (such as high power) as a target, no cracks are generated.

The oxide mixture in the present invention is preferably composed of a zinc oxide phase and a titanium oxide phase. It is important that the titanium oxide be in the state of the low-valence titanium oxide described above, including titanium (III) and titanium (II), which have a low valence. Although sintering may be performed, it is important that a composite oxide with the zinc titanate compound phase is not generated.
Here, examples of the zinc titanate compound phase, the zinc oxide phase, and the titanium oxide phase are the same as those exemplified for the oxide sintered body.

  The oxide mixture in the present invention contains at least one additive element selected from the group consisting of gallium, aluminum, tin, silicon, germanium, zirconium, and hafnium in the same manner as the oxide sintered body described above. You may contain 0.05% or less with respect to the total amount of all the metal elements which comprise a body. In addition, the oxide mixture according to the present invention, like the above-described oxide sintered body, contains other elements such as indium, iridium, ruthenium, and rhenium as impurities, and includes all the metal elements constituting the oxide mixture. You may contain 0.5% or less by atomic ratio with respect to the total amount.

(Method for producing oxide mixture)
The method for producing an oxide mixture in the present invention is a method for obtaining the above-described oxide mixture in the present invention by forming a mixed powder of titanium oxide powder and zinc oxide powder or zinc hydroxide powder.
The raw material powder may be a mixed powder of titanium oxide powder and zinc oxide powder or zinc hydroxide powder, and preferably includes the mixed powder.
As these titanium oxide powder, zinc oxide powder, and zinc hydroxide powder, the same oxide sintered body as described above can be used.

  When using a mixed powder of titanium oxide powder and zinc oxide powder or zinc hydroxide powder as the raw material powder, or when using a mixed powder of titanium oxide powder and zinc oxide powder, the mixing ratio of each powder is used. What is necessary is just to set suitably so that the value of Ti / (Zn + Ti) may become the range mentioned above by atomic number ratio in the oxide mixture finally obtained according to the kind of compound (powder).

The method for forming the raw material powder is not particularly limited. For example, the raw material powder and an aqueous solvent are mixed, and the resulting slurry is sufficiently mixed by wet mixing. What is necessary is just to dry and granulate and shape | mold the obtained granulated material.
The wet mixing may be performed by, for example, a wet ball mill using a hard ZrO ₂ ball or a vibration mill, and the mixing time when using the wet ball mill or the vibration mill is preferably about 12 to 78 hours. In addition, although raw material powder may be dry-mixed as it is, wet mixing is more preferable.
For solid-liquid separation / drying / granulation, known methods may be employed. When the obtained granulated product is molded, for example, the granulated product is put into a mold, and a pressure of 1 ton / cm ² or more is applied using a cold molding machine such as a cold press or a cold isostatic press. Can be molded. At this time, if hot forming is performed using a hot press or the like, it is disadvantageous in terms of manufacturing cost and it is difficult to obtain a large-sized formed body.

The obtained molded body is preferably heated and then annealed to increase the mechanical strength of the oxide mixture.
Annealing is any of inert atmosphere (nitrogen, argon, helium, neon, etc.), vacuum, reducing atmosphere (carbon dioxide, hydrogen, ammonia, etc.), air atmosphere and oxidizing atmosphere (air atmosphere with higher oxygen concentration than air) Perform in an atmosphere at 50 ° C. or higher and lower than 600 ° C. When annealing is performed in an oxidizing atmosphere or an air atmosphere, it is desirable that the annealing be performed at 400 ° C. or lower. This is because TiO and Ti ₂ O ₃ are oxidized to TiO ₂ .
When TiO ₂ is used as the titanium oxide, either the air atmosphere or the reducing atmosphere may be used as long as it is 600 ° C. or lower. By annealing, the mechanical strength of the mixed molded body can be increased.
When annealing is performed in any atmosphere, the annealing time (that is, the holding time at the annealing temperature) is preferably 1 hour to 15 hours. If the annealing time is less than 1 hour, the mechanical strength is not sufficiently improved.

A method for performing the annealing is not particularly limited, and a known method such as a normal pressure annealing method, a hot press method, a HIP method, or a CIP method can be employed.
Examples of the atmosphere for performing the annealing treatment include an atmosphere made of at least one selected from the group consisting of nitrogen, argon, helium, carbon dioxide, and hydrogen, and a vacuum.
As a method for the annealing treatment, for example, a method of heating at normal pressure while introducing a non-oxidizing gas such as nitrogen, argon, helium, carbon dioxide, or hydrogen, or heating under a vacuum (preferably 2 Pa or less). Although it can be performed by a method or the like, the former method at normal pressure is advantageous from the viewpoint of production cost.

(target)
The target in the present invention is used, for example, for forming a zinc oxide thin film by a vacuum film forming method.
Examples of the vacuum film forming method include physical vapor deposition methods such as sputtering, ion plating, PLD, and EB vapor deposition; gas source molecular beam epitaxy (MBE), plasma chemical vapor deposition, and mist chemical vapor deposition. And chemical vapor deposition methods such as MOCVD method, etc., among which sputtering method, ion plating method, PLD method or EB vapor deposition method are preferable.
In addition, although the solid material used in the film formation may be referred to as “tablet”, in the present invention, these are referred to as “target”. In addition, it is also possible to form a film by a general film forming method such as a sol-gel method in addition to the vacuum film forming method such as the vacuum evaporation method described above.

The target in the present invention is formed by processing the above-described oxide sintered body or oxide mixture in the present invention into a predetermined shape and a predetermined dimension.
A processing method in particular is not restrict | limited, What is necessary is just to employ | adopt a well-known method suitably. For example, the surface of the oxide sintered body or the oxide mixture is subjected to surface grinding and the like, then cut to a predetermined size, and then attached to a support base, whereby the target in the present invention can be obtained. Further, if necessary, a plurality of oxide sintered bodies or oxide mixtures may be divided into divided shapes to form a large area target (composite target).

The zinc oxide thin film formed using the oxide sintered body or oxide mixture according to the present invention or the target according to the present invention has excellent electrical conductivity and chemical durability (heat resistance, moisture resistance, chemical resistance ( For example, transparent electrodes such as liquid crystal displays, plasma displays, inorganic EL (electroluminescence) displays, organic EL displays, and electronic paper, and photoelectric conversion of solar cells. It is suitably used for applications such as element window electrodes, electrodes of input devices such as transparent touch panels, and electromagnetic shielding films of electromagnetic shields.
Furthermore, the zinc oxide-based thin film formed using the oxide sintered body or oxide mixture or the target of the present invention is used as a transparent radio wave absorber, an ultraviolet absorber, and further as a transparent semiconductor device. It can also be used in combination with a metal film or a metal oxide film.

(Zinc oxide thin film)
The film thickness of the zinc oxide-based thin film may be appropriately set depending on the application, and is not particularly limited. However, when the thin film patterned according to the present invention is used as the zinc oxide-based thin film, preferably 50 to 600 nm, More preferably, it is 100-500 nm. If the thickness is less than 50 nm, sufficient specific resistance may not be ensured. On the other hand, if the thickness exceeds 600 nm, the film may be colored.

When using the thin film patterned by this invention as a zinc oxide type thin film, the said zinc oxide type thin film is normally formed on a transparent base material.
A transparent base material will not be specifically limited if a shape can be maintained at the time of film-forming. For example, inorganic materials such as various glasses, thermoplastic resins and thermosetting resins (for example, epoxy resin, polymethyl methacrylate, polycarbonate, polystyrene, polyethylene sulfide, polyethersulfone, polyolefin, polyethylene terephthalate, polyethylene naphthalate, triacetyl cellulose) Plate-like material, sheet-like material, film-like material, etc. formed of a resin such as a plastic such as polyimide), and in particular, any of a glass plate, a resin film or a resin sheet Is preferred. The visible light transmittance of the transparent substrate is usually 90% or more, preferably 95% or more.

(Patterning method)
In the patterning method of the present invention, the above zinc oxide thin film is etched with an acid.
The etching solution that can be used in the present invention is not particularly limited as long as it contains an acid. For example, an etching solution used for patterning a conventional zinc oxide-based thin film such as an ITO film can be used. .
Specific examples of the acid include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrohalic acid (such as hydroiodic acid and hydrobromic acid), and mixtures thereof (such as aqua regia), and oxalic acid. Organic acids such as acetic acid, formic acid, propionic acid, succinic acid, malonic acid, butyric acid, citric acid, etc., and an etching solution containing these is usually used as a (water) solution dissolved in a suitable solvent. The acid itself may be used.
Also, various salts such as ammonium sulfate and ferric chloride can be dissolved in the etching solution. Only 1 type may be used for etching liquid and it may use 2 or more types together.

The concentration of the etching solution is not particularly limited, and may be set as appropriate according to the liquid temperature of the etching solution, the curing level of the film, and the like so as to obtain a desired etching rate.
The liquid temperature of the etching solution is preferably 10 to 150 ° C., more preferably 20 to 100 ° C. If the temperature of the etching solution is less than 10 ° C, the zinc oxide thin film may not be etched with acid. On the other hand, if the temperature exceeds 150 ° C, a solvent such as water tends to volatilize, and the concentration control of the etching solution May become difficult.

  There is no particular limitation on the processing method when performing etching using the etching solution. For example, a resist film having a desired pattern is formed on the zinc oxide thin film and is not covered with the resist film. A portion, that is, a portion exposed from the resist film is removed using an etching solution, and then the resist film is removed and removed using an appropriate solvent (for example, methyl cellosolve acetate) to form a desired pattern. be able to. There are no particular restrictions on the specific method and conditions for forming and removing the resist film and removing the exposed portion with an etching solution. For example, a wet etching process applied to a conventional zinc oxide-based thin film such as an ITO film It may be performed appropriately according to the method and conditions in.

The thin film patterned according to the present invention has high conductivity. For example, the transparent conductive substrate obtained by forming and patterning the zinc oxide thin film on the transparent substrate has a specific resistance. Usually, it is 2 × 10 ⁻³ Ω · cm or less, preferably 8 × 10 ⁻⁴ Ω · cm or less. The surface resistance (sheet resistance) varies depending on the application, but is usually 5 to 10,000 Ω / □, preferably 10 to 300 Ω / □.
The thin film patterned by the present invention is usually excellent in transparency. For example, a transparent conductive substrate obtained by forming and patterning the zinc oxide thin film on the transparent base material is transparent. The rate is usually 85% or more, preferably 90% or more in the visible light region.
The total light transmittance is preferably 80% or more, more preferably 85% or more, and the haze value is preferably 10% or less, more preferably 5% or less.

Since the thin film patterned by the present invention is obtained by sufficiently controlling the etching rate, the formed pattern shape is accurate.
Such thin films include, for example, transparent electrodes such as liquid crystal displays, plasma displays, inorganic EL (electroluminescence) displays, organic EL displays, and electronic paper that require pattern processing, window electrodes for photovoltaic cells in solar cells, and transparent touch panels. It can be utilized as an electrode of an input device such as an electromagnetic shield, an electromagnetic shielding film of an electromagnetic shield, a transparent radio wave absorber, an ultraviolet absorber, or as a transparent semiconductor device in combination with another metal film / metal oxide film.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by this Example.
In addition, evaluation of the obtained transparent conductive substrate was performed by the following method.

<Resistivity>
The specific resistance was measured by a four-terminal four-probe method using a resistivity meter (“LORESTA-GP, MCP-T610” manufactured by Mitsubishi Chemical Corporation). Specifically, four needle-shaped electrodes are placed on a straight line on the sample, a constant current is passed between the outer two probes, a constant current is passed between the inner two probes, and the inner two probes are The resulting potential difference was measured to determine the resistance.
<Surface resistance>
The surface resistance was calculated by dividing the specific resistance (Ω · cm) by the film thickness (cm).
<Transmissivity>
The transmittance was measured using an ultraviolet visible near infrared spectrophotometer (“V-670” manufactured by JASCO Corporation).

Example 1
Zinc oxide powder (ZnO; manufactured by Wako Pure Chemical Industries, Ltd., special grade) and titanium oxide powder (Ti ₂ O ₃ ; manufactured by High Purity Chemicals Laboratory Co., Ltd., purity 99.99%) are used as raw material powders. Were mixed in such a ratio that the atomic ratio of Zn: Ti was 92: 8 to obtain a mixture of raw material powders.
Next, the obtained mixture was put in a mold and molded by a uniaxial press at a molding pressure of 500 kg / cm ² to obtain a disk-shaped molded body having a diameter of 80 mm and a thickness of 5 mm. This compact was annealed at 400 ° C. for 3 hours in an argon atmosphere at normal pressure (0.1013 MPa) to obtain an oxide mixture (1).
When the obtained oxide mixture (1) was analyzed with an energy dispersive X-ray fluorescence apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Ti was Zn: Ti = 92. : 8 (Ti / (Zn + Ti) = 0.08). When the crystal structure of the oxide mixture (1) was examined with an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation), the crystal phase of zinc oxide (ZnO) and titanium oxide (Ti ₂ O ₃ ) It was a mixture.

  Next, the obtained oxide mixture (1) is processed into a disk shape of 50 mmφ to prepare a target, and a zinc oxide-based thin film is formed by sputtering using the target to obtain a transparent conductive substrate. It was. That is, the above-mentioned target and a transparent base material (quartz glass substrate) were installed in a sputtering apparatus (“E-200” manufactured by Canon Anelva Engineering Co., Ltd.), respectively, and Ar gas (purity 99.9995% or more, Ar pure) Gas = 5N) was introduced at 12 sccm, and sputtering was performed under the conditions of a pressure of 0.5 Pa, a power of 75 W, and a substrate temperature of 250 ° C. to form a zinc oxide thin film having a thickness of 500 nm on the substrate.

Quantitative analysis of the composition (Zn: Ti) in the formed zinc oxide thin film using a calibration curve by a fluorescent X-ray method using a wavelength dispersion type fluorescent X-ray apparatus (“XRF-1700WS” manufactured by Shimadzu Corporation) As a result, Zn: Ti (atomic ratio) = 92: 8 (Ti / (Zn + Ti) = 0.08). The zinc oxide thin film is subjected to X-ray diffraction using an attachment for thin film measurement using an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation) and an energy dispersive X-ray microanalyzer (TEM). -EDX) was used to investigate the doping state of titanium into zinc, and when the crystal structure was examined using a field emission electron microscope (FE-SEM), it was a wurtzite single phase with C-axis orientation, It was found that titanium was substituted and dissolved in zinc.
The specific resistance of the obtained zinc oxide thin film on the transparent conductive substrate was 8.3 × 10 ⁻⁴ Ω · cm, and the surface resistance was 16.6 Ω / □. The specific resistance distribution on the transparent substrate was uniform in the plane.
The transmittance of the obtained transparent conductive substrate was an average of 90% in the visible region (380 nm to 780 nm) and an average of 65% in the infrared region (780 nm to 2700 nm). The transmittance in the visible region (380 nm to 780 nm) of the quartz glass substrate before film formation was 94% on average, and the transmittance in the infrared region (780 nm to 2700 nm) was 94% on average.

  Next, the etching rate of the film was examined by measuring the rate of film thickness decrease (nm / second) when the formed thin film was immersed in a 1% by mass citric acid aqueous solution at 30 ° C. for 60 seconds. The film thickness was measured using a stylus type film thickness meter (“Alpha-Step IQ” manufactured by Tencor). As a result, the etching rate of the formed thin film was 0.27 nm / second.

  In general, if the etching rate is 0.5 nm / second or less, the level is sufficiently controllable. When this thin film is patterned using the citric acid aqueous solution as an etchant and a predetermined pattern mask, good etching is achieved. A pattern could be formed. The etching rate can be easily controlled, and a conductive zinc oxide thin film pattern was obtained.

(Example 2)
Zinc oxide powder (ZnO; manufactured by Wako Pure Chemical Industries, Ltd., special grade) and titanium oxide powder (Ti ₂ O ₃ ; manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.99%) are used as raw material powders. Mixing was performed at a Zn: Ti atomic ratio of 97: 3 to obtain a raw material powder mixture.
Next, the obtained mixture was put in a mold and molded by a uniaxial press at a molding pressure of 500 kg / cm ² to obtain a disk-shaped molded body having a diameter of 80 mm and a thickness of 5 mm. This compact was sintered at 800 ° C. for 4 hours in an argon atmosphere at normal pressure (1.01325 × 10 ² kPa) to obtain an oxide sintered body (1).
When the obtained oxide sintered body (1) was analyzed with an energy dispersive fluorescent X-ray apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Ti was Zn: Ti = 97: 3 (Ti / (Zn + Ti) = 0.03). When the crystal structure of this oxide sintered body (1) was examined with an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation), crystals of zinc oxide (ZnO) and zinc titanate (Zn ₂ TiO ₄ ) were obtained. It was a phase mixture and no titanium oxide was present.

  Next, by processing the obtained oxide sintered body (1) into a disk shape of 50 mmφ, a target is prepared, and a zinc oxide thin film is formed by sputtering using the target, and a transparent conductive substrate is formed. Obtained. That is, the above-mentioned target and a transparent base material (quartz glass substrate) were installed in a sputtering apparatus (“E-200” manufactured by Canon Anelva Engineering Co., Ltd.), respectively, and Ar gas (purity 99.9995% or more, Ar pure) Gas = 5N) was introduced at 12 sccm, and sputtering was performed under the conditions of a pressure of 0.5 Pa, a power of 75 W, and a substrate temperature of 250 ° C. to form a zinc oxide thin film having a thickness of 500 nm on the substrate.

Quantitative analysis of the composition (Zn: Ti) in the formed zinc oxide thin film using a calibration curve by a fluorescent X-ray method using a wavelength dispersion type fluorescent X-ray apparatus (“XRF-1700WS” manufactured by Shimadzu Corporation) As a result, Zn: Ti (atomic ratio) = 97: 3 (Ti / (Zn + Ti) = 0.04). The zinc oxide thin film is subjected to X-ray diffraction using an attachment for thin film measurement using an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation) and an energy dispersive X-ray microanalyzer (TEM). -EDX) was used to investigate the doping state of titanium into zinc, and when the crystal structure was examined using a field emission electron microscope (FE-SEM), it was a wurtzite single phase with C-axis orientation, It was found that titanium was substituted and dissolved in zinc.
The specific resistance of the zinc oxide thin film on the obtained transparent conductive substrate was 4.4 × 10 ⁻⁴ Ω · cm, and the surface resistance was 8.8Ω / □. The specific resistance distribution on the transparent substrate was uniform in the plane.
The transmittance of the obtained transparent conductive substrate was an average of 89% in the visible region (380 nm to 780 nm) and an average of 60% in the infrared region (780 nm to 2700 nm). The transmittance in the visible region (380 nm to 780 nm) of the quartz glass substrate before film formation was 94% on average, and the transmittance in the infrared region (780 nm to 2700 nm) was 94% on average.

  Next, the etching rate of the film was examined by measuring the rate of film thickness decrease (nm / second) when the formed thin film was immersed in a 1% by mass citric acid aqueous solution at 30 ° C. for 60 seconds. The film thickness was measured using a stylus type film thickness meter (“Alpha-Step IQ” manufactured by Tencor). As a result, the etching rate of the formed thin film was 0.40 nm / second.

  In general, if the etching rate is 0.5 nm / second or less, the level is sufficiently controllable. When this thin film is patterned using the citric acid aqueous solution as an etchant and a predetermined pattern mask, good etching is achieved. A pattern could be formed. The etching rate can be easily controlled, and a conductive zinc oxide thin film pattern was obtained.

(Comparative Example 1)
Zinc oxide powder (ZnO; manufactured by Wako Pure Chemical Industries, Ltd., special grade) and titanium oxide powder (Ti ₂ O ₃ ; manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.99%) are used as raw material powders. A mixture of raw material powders was obtained by mixing at a ratio where the atomic ratio of Zn: Ti was 99: 1.
Next, the obtained mixture was put in a mold and molded by a uniaxial press at a molding pressure of 500 kg / cm ² to obtain a disk-shaped molded body having a diameter of 80 mm and a thickness of 5 mm. This compact was annealed at 400 ° C. for 3 hours in an argon atmosphere at normal pressure (0.1013 MPa) to obtain an oxide mixture (C1).
When the obtained oxide mixture (C1) was analyzed with an energy dispersive X-ray fluorescence apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Ti was Zn: Ti = 99. : 1 (Ti / (Zn + Ti) = 0.01).

  Next, a target is prepared by processing the obtained oxide mixture (C1) into a disk shape of 50 mmφ, and a zinc oxide thin film is formed by sputtering using this to obtain a transparent conductive substrate. It was. That is, the above-mentioned target and a transparent base material (quartz glass substrate) were installed in a sputtering apparatus (“E-200” manufactured by Canon Anelva Engineering Co., Ltd.), respectively, and Ar gas (purity 99.9995% or more, Ar pure) Gas = 5N) was introduced at 12 sccm, and sputtering was performed under the conditions of a pressure of 0.5 Pa, a power of 100 W, and a substrate temperature of 130 ° C. to form a zinc oxide thin film having a thickness of 200 nm on the substrate.

Quantitative analysis of the composition (Zn: Ti) in the formed zinc oxide thin film using a calibration curve by a fluorescent X-ray method using a wavelength dispersion type fluorescent X-ray apparatus (“XRF-1700WS” manufactured by Shimadzu Corporation) As a result, Zn: Ti (atomic ratio) = 99: 1 (Ti / (Zn + Ti) = 0.01). The zinc oxide thin film is subjected to X-ray diffraction using an attachment for thin film measurement using an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation) and an energy dispersive X-ray microanalyzer (TEM). -EDX) was used to investigate the doping state of titanium into zinc, and when the crystal structure was examined using a field emission electron microscope (FE-SEM), it was a wurtzite single phase with C-axis orientation, It was found that titanium was substituted and dissolved in zinc.
The specific resistance of the obtained zinc oxide thin film on the transparent conductive substrate was 2.25 × 10 ⁻³ Ω · cm, and the surface resistance was 112.5 Ω / □. The specific resistance distribution on the transparent substrate was uniform in the plane.
The transmittance of the obtained transparent conductive substrate was 90% on average in the visible region (380 nm to 780 nm), and 70% on average in the infrared region (780 nm to 2700 nm). The transmittance in the visible region (380 nm to 780 nm) of the quartz glass substrate before film formation was 94% on average, and the transmittance in the infrared region (780 nm to 2700 nm) was 94% on average.

  Next, as in Example 1, the etching rate of the formed thin film was examined and found to be 1.2 nm / second.

  In the case of this film, it is difficult to control because the etching rate is 1.0 nm / second or more, and when this thin film is patterned using a citric acid aqueous solution similar to Example 1 as an etching solution using a mask of a predetermined pattern, It was difficult to form a good etching pattern.

(Comparative Example 2)
A zinc oxide thin film doped with aluminum atoms was formed on soda lime glass (thickness 0.7 mm) by a direct current magnetron sputtering method using a zinc oxide sputtering target containing 2% by mass of aluminum oxide. Sputtering was performed at a power of 75 W, a film formation pressure of 0.5 Pa, an oxygen partial pressure of 0 Pa, a substrate temperature of room temperature, and a film formation time of 30 minutes.

  Next, when the etching rate of the formed thin film was examined in the same manner as in Example 1, it was 1.5 nm / second.

  In the case of this film, it is difficult to control because the etching rate is 1.0 nm / second or more, and when this thin film is patterned using a citric acid aqueous solution similar to Example 1 as an etching solution using a mask of a predetermined pattern, It was difficult to form a good etching pattern.

(Example 3)
Zinc oxide powder (ZnO; manufactured by Wako Pure Chemical Industries, Ltd., special grade) and titanium oxide powder (TiO (II); manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.99%) are used as raw material powders. A mixture of raw material powders was obtained by mixing at a Zn: Ti atomic ratio of 92: 8.
Next, the obtained mixture was put in a mold and molded by a uniaxial press at a molding pressure of 500 kg / cm ² to obtain a disk-shaped molded body having a diameter of 80 mm and a thickness of 5 mm. This compact was annealed at 400 ° C. for 3 hours under an atmospheric pressure (0.1013 MPa) argon atmosphere to obtain an oxide mixture (2).
When the obtained oxide mixture (2) was analyzed with an energy dispersive X-ray fluorescence apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Ti was Zn: Ti = 92. : 8 (Ti / (Zn + Ti) = 0.08). When the crystal structure of the oxide mixture (2) was examined with an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation), the crystal phase of zinc oxide (ZnO) and titanium oxide (Ti ₂ O ₃ ) It was a mixture.

  Next, a target is prepared by processing the obtained oxide mixture (2) into a disk shape of 50 mmφ, and a zinc oxide-based thin film is formed by sputtering using this to obtain a transparent conductive substrate. It was. That is, the above-mentioned target and a transparent base material (quartz glass substrate) were installed in a sputtering apparatus (“E-200” manufactured by Canon Anelva Engineering Co., Ltd.), respectively, and Ar gas (purity 99.9995% or more, Ar pure) Gas = 5N) was introduced at 12 sccm, and sputtering was performed under the conditions of a pressure of 0.5 Pa, a power of 75 W, and a substrate temperature of 250 ° C. to form a zinc oxide thin film having a thickness of 500 nm on the substrate.

Quantitative analysis of the composition (Zn: Ti) in the formed zinc oxide thin film using a calibration curve by a fluorescent X-ray method using a wavelength dispersion type fluorescent X-ray apparatus (“XRF-1700WS” manufactured by Shimadzu Corporation) As a result, Zn: Ti (atomic ratio) = 92: 8 (Ti / (Zn + Ti) = 0.08). The zinc oxide thin film is subjected to X-ray diffraction using an attachment for thin film measurement using an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation) and an energy dispersive X-ray microanalyzer (TEM). -EDX) was used to investigate the doping state of titanium into zinc, and when the crystal structure was examined using a field emission electron microscope (FE-SEM), it was a wurtzite single phase with C-axis orientation, It was found that titanium was substituted and dissolved in zinc.
The specific resistance of the obtained zinc oxide thin film on the transparent conductive substrate was 7.6 × 10 ⁻⁴ Ω · cm, and the surface resistance was 15.2 Ω / □. The specific resistance distribution on the transparent substrate was uniform in the plane.
The transmittance of the obtained transparent conductive substrate was an average of 90% in the visible region (380 nm to 780 nm) and an average of 65% in the infrared region (780 nm to 2700 nm). The transmittance in the visible region (380 nm to 780 nm) of the quartz glass substrate before film formation was 94% on average, and the transmittance in the infrared region (780 nm to 2700 nm) was 94% on average.

  Next, the etching rate of the film was examined by measuring the rate of film thickness decrease (nm / second) when the formed thin film was immersed in a 1% by mass citric acid aqueous solution at 30 ° C. for 60 seconds. The film thickness was measured using a stylus type film thickness meter (“Alpha-Step IQ” manufactured by Tencor). As a result, the etching rate of the formed thin film was 0.27 nm / second.

  In general, if the etching rate is 0.5 nm / second or less, the level is sufficiently controllable. When this thin film is patterned using the citric acid aqueous solution as an etchant and a predetermined pattern mask, good etching is achieved. A pattern could be formed. The etching rate can be easily controlled, and a conductive zinc oxide thin film pattern was obtained.

Example 4
Zinc oxide powder (ZnO; manufactured by Wako Pure Chemical Industries, Ltd., special grade) and titanium oxide powder (TiO (II); manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.99%) are used as raw material powders. Mixing was performed at a Zn: Ti atomic ratio of 97: 3 to obtain a raw material powder mixture.
Next, the obtained mixture was put in a mold and molded by a uniaxial press at a molding pressure of 500 kg / cm ² to obtain a disk-shaped molded body having a diameter of 80 mm and a thickness of 5 mm. This molded body was sintered at 800 ° C. for 4 hours in an argon atmosphere at normal pressure (1.01325 × 10 ² kPa) to obtain an oxide sintered body (2).
When the obtained oxide sintered body (2) was analyzed with an energy dispersive fluorescent X-ray apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Ti was Zn: Ti = 97: 3 (Ti / (Zn + Ti) = 0.03)
)Met. When the crystal structure of this oxide sintered body (2) was examined with an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation), crystals of zinc oxide (ZnO) and zinc titanate (Zn ₂ TiO ₄ ) were obtained. It was a phase mixture and no titanium oxide was present.

  Next, by processing the obtained oxide sintered body (2) into a disk shape of 50 mmφ, a target is prepared, and a zinc oxide thin film is formed by sputtering using the target, and a transparent conductive substrate is formed. Obtained. That is, the above-mentioned target and a transparent base material (quartz glass substrate) were installed in a sputtering apparatus (“E-200” manufactured by Canon Anelva Engineering Co., Ltd.), respectively, and Ar gas (purity 99.9995% or more, Ar pure) Gas = 5N) was introduced at 12 sccm, and sputtering was performed under the conditions of a pressure of 0.5 Pa, a power of 75 W, and a substrate temperature of 250 ° C. to form a zinc oxide thin film having a thickness of 500 nm on the substrate.

Quantitative analysis of the composition (Zn: Ti) in the formed zinc oxide thin film using a calibration curve by a fluorescent X-ray method using a wavelength dispersion type fluorescent X-ray apparatus (“XRF-1700WS” manufactured by Shimadzu Corporation) As a result, Zn: Ti (atomic ratio) = 97: 3 (Ti / (Zn + Ti) = 0.03). The zinc oxide thin film is subjected to X-ray diffraction using an attachment for thin film measurement using an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation) and an energy dispersive X-ray microanalyzer (TEM). -EDX) was used to investigate the doping state of titanium into zinc, and when the crystal structure was examined using a field emission electron microscope (FE-SEM), it was a wurtzite single phase with C-axis orientation, It was found that titanium was substituted and dissolved in zinc.
The specific resistance of the obtained zinc oxide thin film on the transparent conductive substrate was 4.2 × 10 ⁻⁴ Ω · cm, and the surface resistance was 8.4 Ω / □. The specific resistance distribution on the transparent substrate was uniform in the plane.
The transmittance of the obtained transparent conductive substrate was an average of 89% in the visible region (380 nm to 780 nm) and an average of 60% in the infrared region (780 nm to 2700 nm). The transmittance in the visible region (380 nm to 780 nm) of the quartz glass substrate before film formation was 94% on average, and the transmittance in the infrared region (780 nm to 2700 nm) was 94% on average.

  Next, the etching rate of the film was examined by measuring the rate of film thickness decrease (nm / second) when the formed thin film was immersed in a 1% by mass citric acid aqueous solution at 30 ° C. for 60 seconds. The film thickness was measured using a stylus type film thickness meter (“Alpha-Step IQ” manufactured by Tencor). As a result, the etching rate of the formed thin film was 0.40 nm / second.

  In general, if the etching rate is 0.5 nm / second or less, the level is sufficiently controllable. When this thin film is patterned using the citric acid aqueous solution as an etchant and a predetermined pattern mask, good etching is achieved. A pattern could be formed. The etching rate can be easily controlled, and a conductive zinc oxide thin film pattern was obtained.

(Example 5)
Zinc oxide powder (ZnO; manufactured by Wako Pure Chemical Industries, Ltd., special grade) and titanium oxide powder (TiO (II); manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.99%) are used as raw material powders. Mixing was performed at a Zn: Ti atomic ratio of 97: 3 to obtain a raw material powder mixture.
After the mixing operation, the mixed powder obtained by removing the balls and ethanol is put into a mold (die) made of graphite, and vacuum-pressed at a pressure of 40 MPa with a punch made of graphite, followed by heat treatment at 1000 ° C. for 4 hours. To obtain a disk-shaped oxide sintered body (3). When the obtained oxide sintered body (3) was analyzed with an energy dispersive fluorescent X-ray apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Ti was Zn: Ti = 97: 3 (Ti / (Zn + Ti) = 0.03).
When the crystal structure of this oxide sintered body (3) was examined with an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation), crystals of zinc oxide (ZnO) and zinc titanate (Zn ₂ TiO ₄ ) were obtained. It was a phase mixture and no titanium oxide was present.

  Next, by processing the obtained oxide sintered body (3) into a disk shape of 50 mmφ, a target is prepared, and a zinc oxide thin film is formed by sputtering using this, and a transparent conductive substrate is formed. Obtained. That is, the above-mentioned target and a transparent base material (quartz glass substrate) were installed in a sputtering apparatus (“E-200” manufactured by Canon Anelva Engineering Co., Ltd.), respectively, and Ar gas (purity 99.9995% or more, Ar pure) Gas = 5N) was introduced at 12 sccm, and sputtering was performed under the conditions of a pressure of 0.5 Pa, a power of 75 W, and a substrate temperature of 250 ° C. to form a zinc oxide thin film having a thickness of 500 nm on the substrate.

Quantitative analysis of the composition (Zn: Ti) in the formed zinc oxide thin film using a calibration curve by a fluorescent X-ray method using a wavelength dispersion type fluorescent X-ray apparatus (“XRF-1700WS” manufactured by Shimadzu Corporation) As a result, Zn: Ti (atomic ratio) = 97: 3 (Ti / (Zn + Ti) = 0.03). The zinc oxide thin film is subjected to X-ray diffraction using an attachment for thin film measurement using an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation) and an energy dispersive X-ray microanalyzer (TEM). -EDX) was used to investigate the doping state of titanium into zinc, and when the crystal structure was examined using a field emission electron microscope (FE-SEM), it was a wurtzite single phase with C-axis orientation, It was found that titanium was substituted and dissolved in zinc.
The specific resistance of the obtained zinc oxide thin film on the transparent conductive substrate was 4.2 × 10 ⁻⁴ Ω · cm, and the surface resistance was 8.4 Ω / □. The specific resistance distribution on the transparent substrate was uniform in the plane.
The transmittance of the obtained transparent conductive substrate was an average of 89% in the visible region (380 nm to 780 nm) and an average of 60% in the infrared region (780 nm to 2700 nm). The transmittance in the visible region (380 nm to 780 nm) of the quartz glass substrate before film formation was 94% on average, and the transmittance in the infrared region (780 nm to 2700 nm) was 94% on average.

  Next, the etching rate of the film was examined by measuring the rate of film thickness decrease (nm / second) when the formed thin film was immersed in a 1% by mass citric acid aqueous solution at 30 ° C. for 60 seconds. The film thickness was measured using a stylus type film thickness meter (“Alpha-Step IQ” manufactured by Tencor). As a result, the etching rate of the formed thin film was 0.40 nm / second.

  In general, if the etching rate is 0.5 nm / second or less, the level is sufficiently controllable. When this thin film is patterned using the citric acid aqueous solution as an etchant and a predetermined pattern mask, good etching is achieved. A pattern could be formed. The etching rate can be easily controlled, and a conductive zinc oxide thin film pattern was obtained.

(Comparative Example 3)
Zinc oxide powder (ZnO; manufactured by Wako Pure Chemical Industries, Ltd., special grade) and titanium oxide powder (TiO (II); manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.99%) are used as raw material powders. A mixture of raw material powders was obtained by mixing at a ratio of the Zn: Ti atomic ratio of 88:12.
After the mixing operation, the mixed powder obtained by removing the balls and ethanol is put into a mold (die) made of graphite, and vacuum-pressed at a pressure of 40 MPa with a punch made of graphite, followed by heat treatment at 1000 ° C. for 4 hours. To obtain a disk-shaped oxide sintered body (C3). When the obtained oxide sintered body (C3) was analyzed with an energy dispersive X-ray fluorescence apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Ti was Zn: Ti = 88:12 (Ti / (Zn + Ti) = 0.12).
When the crystal structure of the oxide sintered body (C3) was examined with an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation), crystals of zinc oxide (ZnO) and zinc titanate (Zn ₂ TiO ₄ ) were obtained. It was a phase mixture and no titanium oxide was present.

  Next, by processing the obtained oxide sintered body (C3) into a disk shape of 50 mmφ, a target is prepared, and a zinc oxide-based thin film is formed by sputtering using this, and a transparent conductive substrate is formed. Obtained. That is, the above-mentioned target and a transparent base material (quartz glass substrate) were installed in a sputtering apparatus (“E-200” manufactured by Canon Anelva Engineering Co., Ltd.), respectively, and Ar gas (purity 99.9995% or more, Ar pure) Gas = 5N) was introduced at 12 sccm, and sputtering was performed under the conditions of a pressure of 0.5 Pa, a power of 75 W, and a substrate temperature of 250 ° C. to form a zinc oxide thin film having a thickness of 500 nm on the substrate.

Quantitative analysis of the composition (Zn: Ti) in the formed zinc oxide thin film using a calibration curve by a fluorescent X-ray method using a wavelength dispersion type fluorescent X-ray apparatus (“XRF-1700WS” manufactured by Shimadzu Corporation) As a result, Zn: Ti (atomic ratio) = 88: 12 (Ti / (Zn + Ti) = 0.12). The zinc oxide thin film is subjected to X-ray diffraction using an attachment for thin film measurement using an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation) and an energy dispersive X-ray microanalyzer (TEM). -EDX) was used to investigate the doping state of titanium into zinc, and when the crystal structure was examined using a field emission electron microscope (FE-SEM), it was a wurtzite single phase with C-axis orientation, It was found that titanium was substituted and dissolved in zinc.
The specific resistance of the obtained zinc oxide thin film on the transparent conductive substrate was 2.1 × 10 ⁻² Ω · cm, and the surface resistance was 420.0Ω / □. The specific resistance distribution on the transparent substrate was uniform in the plane.
The transmittance of the obtained transparent conductive substrate was an average of 89% in the visible region (380 nm to 780 nm) and an average of 60% in the infrared region (780 nm to 2700 nm). The transmittance in the visible region (380 nm to 780 nm) of the quartz glass substrate before film formation was 94% on average, and the transmittance in the infrared region (780 nm to 2700 nm) was 94% on average.

  Next, the etching rate of the film was examined by measuring the rate of film thickness decrease (nm / second) when the formed thin film was immersed in a 1% by mass citric acid aqueous solution at 30 ° C. for 60 seconds. The film thickness was measured using a stylus type film thickness meter (“Alpha-Step IQ” manufactured by Tencor). As a result, the etching rate of the formed thin film was 0.16 nm / second.

  In general, if the etching rate is 0.5 nm / second or less, the level is sufficiently controllable. When this thin film is patterned using the citric acid aqueous solution as an etchant and a predetermined pattern mask, good etching is achieved. A pattern could be formed. The etching rate can be easily controlled, and a conductive zinc oxide thin film pattern was obtained. Although the etching rate was sufficiently controllable, the resistance was high.

(Example 6)
Zinc oxide powder (ZnO; manufactured by Wako Pure Chemical Industries, Ltd., special grade) and titanium oxide powder (TiO (II); manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.99%) are used as raw material powders. Mixing was performed at a Zn: Ti atomic ratio of 97: 3 to obtain a raw material powder mixture.
After the mixing operation, the mixed powder obtained by removing the balls and ethanol is put into a mold (die) made of graphite, and vacuum-pressed at a pressure of 40 MPa with a punch made of graphite, followed by heat treatment at 1000 ° C. for 4 hours. To obtain a disk-shaped oxide sintered body (4). When the obtained oxide sintered body (4) was analyzed with an energy dispersive fluorescent X-ray apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Ti was Zn: Ti = 97: 3 (Ti / (Zn + Ti) = 0.03).
When the crystal structure of this oxide sintered body (4) was examined with an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation), crystals of zinc oxide (ZnO) and zinc titanate (Zn ₂ TiO ₄ ) were obtained. It was a phase mixture and no titanium oxide was present.

  Next, by processing the obtained oxide sintered body (4) into a disk shape of 50 mmφ, a target is prepared, and a zinc oxide-based thin film is formed by sputtering using this, and a transparent conductive substrate is formed. Obtained. That is, the above-mentioned target and a transparent base material (quartz glass substrate) were installed in a sputtering apparatus (“E-200” manufactured by Canon Anelva Engineering Co., Ltd.), respectively, and Ar gas (purity 99.9995% or more, Ar pure) Gas = 5N) was introduced at 12 sccm, and sputtering was performed under the conditions of a pressure of 0.5 Pa, a power of 75 W, and a substrate temperature of 250 ° C. to form a zinc oxide thin film having a thickness of 500 nm on the substrate.

Quantitative analysis of the composition (Zn: Ti) in the formed zinc oxide thin film using a calibration curve by a fluorescent X-ray method using a wavelength dispersion type fluorescent X-ray apparatus (“XRF-1700WS” manufactured by Shimadzu Corporation) As a result, Zn: Ti (atomic ratio) = 97: 3 (Ti / (Zn + Ti) = 0.03). The zinc oxide thin film is subjected to X-ray diffraction using an attachment for thin film measurement using an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation) and an energy dispersive X-ray microanalyzer (TEM). -EDX) was used to investigate the doping state of titanium into zinc, and when the crystal structure was examined using a field emission electron microscope (FE-SEM), it was a wurtzite single phase with C-axis orientation, It was found that titanium was substituted and dissolved in zinc.
The specific resistance of the obtained zinc oxide thin film on the transparent conductive substrate was 4.2 × 10 ⁻⁴ Ω · cm, and the surface resistance was 8.4 Ω / □. The specific resistance distribution on the transparent substrate was uniform in the plane.
The transmittance of the obtained transparent conductive substrate was an average of 89% in the visible region (380 nm to 780 nm) and an average of 60% in the infrared region (780 nm to 2700 nm). The transmittance in the visible region (380 nm to 780 nm) of the quartz glass substrate before film formation was 94% on average, and the transmittance in the infrared region (780 nm to 2700 nm) was 94% on average.

  Next, the etching rate of the film was examined by measuring the rate of film thickness decrease (nm / second) when the formed thin film was immersed in a 1 mol / l acetic acid aqueous solution at 20 ° C. for 120 seconds. The film thickness was measured using a stylus type film thickness meter (“Alpha-Step IQ” manufactured by Tencor). As a result, the etching rate of the formed thin film was 0.33 nm / second.

  In general, if the etching rate is 0.5 nm / second or less, the level is sufficiently controllable. When this thin film is patterned using the citric acid aqueous solution as an etchant and a predetermined pattern mask, good etching is achieved. A pattern could be formed. The etching rate can be easily controlled, and a conductive zinc oxide thin film pattern was obtained.

(Comparative Example 4)
A zinc oxide thin film doped with aluminum atoms was formed on soda lime glass (thickness 0.7 mm) by a direct current magnetron sputtering method using a zinc oxide sputtering target containing 2% by mass of aluminum oxide. Sputtering was performed at a power of 75 W, a film formation pressure of 0.5 Pa, an oxygen partial pressure of 0 Pa, a substrate temperature of room temperature, and a film formation time of 30 minutes.

Next, when the etching rate of the formed thin film was examined in the same manner as in Example 1, it was 1.5 nm / second.
Next, the etching rate of the film was examined by measuring the rate of film thickness decrease (nm / second) when the formed thin film was immersed in a 1 mol / l acetic acid aqueous solution at 20 ° C. for 120 seconds. The film thickness was measured using a stylus type film thickness meter (“Alpha-Step IQ” manufactured by Tencor). As a result, the etching rate of the formed thin film was 2.42 nm / second.

  In the case of this film, since the etching rate is 1.0 nm / second or more, it is difficult to control, and when this thin film is patterned using an acetic acid aqueous solution similar to that in Example 6 as an etchant using a predetermined pattern mask, the film is good. It was difficult to form an etching pattern.

Claims (6)

  A method of patterning by etching an zinc oxide thin film with an acid, wherein the zinc oxide thin film is mainly composed of zinc oxide, and the atomic ratio Ti / (Zn + Ti) of titanium to the total of zinc and titanium is 0. A patterning method characterized by being a thin film exceeding 0.02 and not more than 0.1.   The zinc oxide-based thin film is formed by using a target obtained by processing an oxide sintered body or an oxide mixture substantially composed of zinc, titanium, and oxygen as a film forming material. A patterning method according to claim 1. The patterning method according to claim 2, wherein the titanium is titanium derived from low-valent titanium oxide represented by a formula TiO _2−X (X = 0.1-1). The patterning method according to claim 3, wherein the low-valence titanium oxide is titanium oxide (TiO) made of divalent titanium or titanium oxide (Ti ₂ O ₃ ) made of trivalent titanium.   The patterning method according to claim 1, wherein the zinc oxide-based thin film is a film formed by a vacuum film forming method.   The patterning method according to claim 5, wherein the vacuum film forming method is a sputtering method, an ion plating method, a pulse laser deposition method (PLD method), or an electron beam (EB) vapor deposition method.