JPH08264022A - Transparent conductive film - Google Patents

Abstract

PURPOSE: To provide a transparent conductive film made of oxides containing group II, III, and IV elements, having the pseudoternary or pseudoquaternary composition, having high conductivity, capable of widely selecting the light refraction factor from a small one to a large one, and having stability and proper chemical resistance in the high-temperature oxidizing atmosphere. CONSTITUTION: A quaternary transparent conductive film made of the pseudoternary composition containing the mixed crystal indicated by (Zn,Cd,Mg) O-(B,Al,Ga,In,Y)2 O3 -(Si,Ge,Sn,Pb,Ti,Zr)O2 or (Zn,Cd,Mg)O-(B,Al,Ga,In,Y)2 O3 -(Si,Sn, Pb)O is manufactured with the pseudoternary powder or a sintered target of the same composition by the high-frequency or DC magnetron spattering method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent conductive oxide film and a sintered body used for producing the film.

[0002]

2. Description of the Related Art Various display devices, thin-film solar cells, and energy-saving architectural window glass coating materials with excellent ultraviolet blocking and infrared reflecting properties, which are expected to have huge demand in the future, have high visible light transmittance and low resistance. The transparent conductive film that it has is indispensable. The most widely used transparent conductive film at present is mainly a metal oxide thin film,
The tin oxide SnO ₂ type having high chemical stability (the one to which F or antimony (Sb) is added is mainly used), the indium oxide (In ₂ O ₃ ) type, and more recently, the applicants There is known a zinc oxide (ZnO) system which has a low cost, has no resource problems, and has excellent electrical and optical characteristics comparable to Sn-doped In ₂ O ₃ (ITO).

[0003]

However, the conventional transparent conductive film cannot cope with the recent diversification of applications for the transparent conductive film. That is, there is a demand for a transparent conductive film which is uniform over a large area and has a lower resistivity, a higher light transmittance, and an arbitrary light refractive index. Moreover, although high chemical resistance to acids and alkalis and high stability in use in a high temperature oxidizing atmosphere are required, there is a problem that the conventional transparent conductive film cannot be used.

[0004]

The present invention includes a group II and a group III
It is intended to provide a new transparent conductive film having a pseudo ternary or quaternary composition composed of an oxide containing a group IV element and a group IV element. As a result, the above-mentioned problems of the transparent conductive film due to the use of the conventionally used pseudo binary or ternary compound are solved, and the film having various electric and optical characteristics is used alone or in appropriate combination. It is an object of the present invention to provide a new transparent conductive film that can achieve stability in a high temperature oxidizing atmosphere and appropriate chemical resistance when used, and a sintered body used for producing the same. .

Specifically, zinc (Zn) is a group II element.
Alternatively, an oxide composed of magnesium (Mg), gallium (Ga) or indium (In) as a group III element, and silicon (Si), germanium (Ge), tin (Sn) or titanium (Ti) as a group IV element,
That (Zn, Mg) O- (Ga , In) 2 O 3 - (Si,
[0.1 + x] (Zn, Cd, Mg) O- in a quasi-ternary system containing a mixed crystal represented by Ge, Sn, Ti) O _2.
[0.1] (B, Al, Ga, In, Y) ₂ O _3- [9
9.8-x] (Si, Ge, Sn, Pb, Ti, Zr)
O ₂ , [99.8-x] (Zn, Cd, Mg) O-
[0.1 + x] (B, Al, Ga, In, Y) ₂ O ₃ −
[0.1] (Si, Ge, Sn, Pb, Ti, Zr) O
₂ , [0.1] (Zn, Cd, Mg) O- [99.8-
x] (B, Al, Ga, In, Y)-[0.1 + x]
A composition surrounded by each region of (Si, Ge, Sn, Pb, Ti, Zr) O ₂ or an oxide of a group IV element of the same group (S
i, Sn, Pb) O, and the composition range surrounded by each of the above regions, where 0 ≦ x ≦ 99.7 [mol%], and the film is made of glass. The object of the present invention can be achieved by forming it on such a ceramic substrate or an organic substrate such as plastic. Thus, for example ZnO-In ₂ O ₃ -SnO
_In a transparent conductive film having a quasi-ternary or quaternary composition of 2, the average visible light transmittance is improved and the light refractive index in the visible light region is improved to about 2.0 by replacing ZnO with MgO. Can be changed drastically. Further, by sequentially replacing In ₂ O ₃ with Ga ₂ O ₃ , the same light refractive index can be adjusted within the range of 2.0 to 1.6, and the average visible light transmittance is also improved, Can significantly improve chemical properties. However, In _{2 of} Ga ₂ O ₃
The substitution amount for O ₃ was limited to about 30%. 30%
With the above, the resistance value of the film rises sharply, and the film does not function as a transparent conductive film. On the other hand, by substituting SnO ₂ with SiO ₂ , GeO ₂ or TiO ₂ , the optical refractive index is increased to 2.5.
It was found that it could be changed significantly to ~ 1.6. In addition, the environment resistance of the film could be greatly improved. Such characteristics are quite different from those of the conventional transparent conductive film made of quasi-binary system or ternary system, and it is impossible to predict such composition and properties. Further, the composition control of the target used in producing the transparent conductive film according to the present invention is particularly important, and there is not always a correspondence between the stoichiometric composition ratio and the electrical characteristics of the film. Therefore, it is necessary to adjust the target composition in advance according to the type of the transparent conductive film to be manufactured. For example, although the major component of the film can be a ZnO-In ₂ O ₃ -SnO ₂ based is Zn ₂ In ₂ O _5, the compound Z
If the molar ratio of nO and In ₂ O ₃ is 2: 1, the above compound is not produced. Therefore, it was necessary to set the molar ratio to 1: 1.

The method for producing the transparent conductive film according to the present invention includes a vacuum vapor deposition method, a sputtering method and a chemical vapor phase crystal growth (CV) method.
Known thin film forming methods such as the D) method, the sol-gel method, and the molecular beam epitaxial growth method can be used.

[0007]

[Operation] When a thin film having the above composition range suitable for the purpose of the present invention is formed on the substrate by the known thin film forming method as described above, intrinsic properties due to intrinsic lattice defects such as oxygen vacancies and interstitial atoms are generated. Donor or part of group II element is group III element, part of group III element is group IV element, part of group II element is group I
It is possible to generate carriers by the introduction of exogenous donors that substitute with group V elements, or part of group VI elements with group VII elements, or alternatively, with one or more combinations thereof. The thin film according to the present invention is expected to be amorphous or crystalline, but in any case, carrier generation by the above-mentioned mechanism is considered. Further, in any of the above oxides, a transparent conductive film having a large band gap of about 3 eV or more and very little absorption in the visible light region can be realized. Further, the optical refractive index of the transparent conductive film according to the present invention is higher than that of the conventional transparent conductive film such as In ₂ O ₃ system, SnO ₂ system and ZnO system from about 2.4 to about 1.6. It has the feature that it can be changed by adjusting the composition of the original system. Therefore, by changing the composition of the film, a transparent conductive film having various optical refractive indexes can be produced. Therefore, a film having a small optical refractive index and a film having a large optical refractive index such as glass often used as a substrate or a conventional transparent conductive film can be formed. It has an unprecedented wide range of options that can be used in appropriate combinations. As a result, conductive coating film, interference filter,
It produces the effect that it can be used as a reflector (black reflector), a decorative coating for window glass or a transparent electrode film. Further, the film according to the present invention is, for example, ZnO-based which is easily dissolved in acid / alkali, SnO ₂ -based which has extremely high chemical resistance, and In ₂ which has appropriate chemical resistance.
Since it is composed of O ₃ system, it produces the action effect that it can be given chemical resistance that can deal with a wide range of needs.
Therefore, it has a feature that it can be sufficiently applied to various uses of transparent conductive films.

The present invention will be described below with reference to examples.

Example 1 MgIn ₂ O ₄ added with 0.1 mol% of Sn per chemical formula and Sn of the same amount per chemical formula of 0.
In a system consisting of 1 mol% added Zn ₂ In ₂ O ₅ ,
A typical example of composition dependence of band gap energy, resistivity, photorefractive index and average visible light transmittance of a thin film prepared by changing the atomic ratio of Zn / (Zn + Mg) from 0 to 100% is shown in FIG. Shown in. The film forming conditions at this time are as follows. Zn and Mg were uniformly mixed at the above mixing ratio, and each fired powder fired in argon at 1000 ° C. for 5 hours was filled in a stainless steel dish having a diameter of 80 mm to be a sputtering target. Pure argon gas was used as the sputtering gas. The sputtering gas pressure was set to 1.2 Pa, and sputtering film formation was performed on a glass substrate at room temperature held parallel to the target surface with a high-frequency input power of 40 W. The average thickness of the produced film was 380 nm, and the minimum resistivity of the film obtained at room temperature was 3.9 × 10 ⁻⁴ Ωcm obtained in the film having a composition corresponding to Zn ₂ In ₂ O ₅ . Further, the optical refractive index of the film of each composition was about 2.0 in the Mg-rich film, while the maximum value of about 2.4 was obtained in the Zn-rich film. However, the band gap value is 2.
The value was 9 eV, which was lower than that of the conventional transparent conductive film. An average visible light transmittance of 80% or more could be secured except for the Zn side. By changing the composition in this way, a high photorefractive index and a low resistivity could be obtained. When the obtained film was analyzed by x-ray diffraction, the main component in the Zn-rich film was Z.
n ₂ In ₂ O ₅ and the main component of the Mg-rich film is MgIn ₂
It was O ₄ . Even when the substrate was held vertically to form a film, almost the same result as above was obtained. Further, instead of Sn as an additive, Ge, Si, Pb, Ti or Z
Even if it was replaced by r, almost the same electro-optical characteristics were obtained. It should be noted that either of the above oxides or oxides was effective in introducing the additive. Further, when the substrate was manufactured at a temperature of 350 ° C., it was possible to secure the transmittance of 80% or more in the entire composition range without impairing the electrical characteristics.

[0009]

Example 2 Under the same sputtering conditions as in Example 1, InGaO ₃ and MgI added with 0.1 mol% Sn per chemical formula.
In a film made by changing the In / (In + Mg) ratio from 0 to 100% in the system composed of n ₂ O ₄ as in Example 1, the In-rich film had a photorefractive index of about 1.6 and a resistivity. It was 4.5 × 10 ⁻⁴ Ωcm. In addition, the additive S
Even if Si, Ge, Pb, Ti or Zr was used instead of n, almost the same electro-optical characteristics were obtained. Also,
It was also effective to use B, Al or Y instead of Ga. If the substrate temperature is 350 ° C.,
The transmittance could be improved to 85% without impairing the electrical characteristics.

[0010]

Example 3 Under the same sputtering conditions as in Example 1, InGaO ₃ and Zn ₂ I added with 0.1 mol% Sn per chemical formula.
In a film made by changing the Zn / (In + Zn) ratio from 0 to 100% in the system consisting of n ₂ O ₅ as in Example 1, the In-rich film had a photorefractive index of about 1.6 and a resistivity. It was 5.5 × 10 ⁻⁴ Ωcm. Further, instead of Sn which is an additive, Si, Ge, Pb, Ti or Zr
Even when replaced with, the almost same electro-optical characteristics were obtained. When the substrate was manufactured at a temperature of 350 ° C., the transmittance could be improved to 85% without impairing the electrical characteristics.

[0011]

Example 4 Example 1 comprising MgIn ₂ O ₄ , Zn ₂ In ₂ O ₅ or InGaO _{3 with} 0.1 mol% Sn added per chemical formula, or a combination of two or more thereof.
ZnO, which was used to prepare two or three of the transparent conductive _{film, MgO, In 2 O 3,} Ga 2 O 3, IV group were uniformly mixed oxide raw material powder, after molding to the diameter 80 mm, baked A bonded sintered body target was used. In each case, almost the same results were obtained as the electric and optical characteristics of the transparent conductive film produced by using the fired powder target. It was also confirmed that the same result can be realized by the DC magnetron sputtering method using a sintered target.

The transparent conductive film according to the present invention is not limited to the above embodiment, but various raw materials such as, for example,
In the above examples, oxides were used for all raw materials, but oxides containing Group II, Group III or Group IV or lower vaporizable compounds such as acetate, acetylacetonate, or alcoholate were used. Various compounds such as various organic metal complexes can be appropriately combined and used.
That is, as a Zn raw material, [Zn (acac) ₂ ], Zn acetate [Zn (CH ₃ COO) ₂ ], zinc chloride (ZnC
l ₄ ), a salt or a halogenide, an alkoxide such as Zn (OCH ₃ ) ₂ or Zn (OC ₂ H ₅ ) ₂ , dimethyl Zn [Zn (C
Many complex salts and complexes such as alkyl compounds such as H ₃ ) ₂ ] and diethyl Zn [Zn (C ₂ H ₅ ) ₂ ] can be used. Mg
The same compound as in the case of Zn can be used as the raw material. Further, as the Sn starting _{material, [Sn (CH 3 COO)} 2], tetra propoxy Sn [Sn (O-i- C 3 H 7) 4], tetra -n- butoxy Sn [Sn (O-n- C 4 H ₉ ) Alkoxides such as ₄ , stannous oxalate (SnC ₂ O ₄ ), stannic chloride (SnCl ₄ ), tin acetylacetonate [S
n (C ₄ H ₉ ) ₂ (C ₅ H ₇ O ₂ ) ₂ ], tin salt or tin halogenide type, and further tetramethyltin [Sn (C
It can also be produced using many complex salts and complexes such as alkyl compounds such as H ₃ ) ₄ ] and [Sn (C ₂ H ₅ ) ₄ ]. Ti and G
Similar compounds can be used for the raw material of e. Further, it goes without saying that the same compounds as described above can be used for the group III elements In and Ga.

EFFECTS OF THE INVENTION In the quasi-ternary oxide according to the present invention, the band gap changed greatly from 2.9 to 3.4 eV. Furthermore, a transparent conductive film with very little absorption in the visible light region was realized. Furthermore, In ₂ O ₃ system, SnO ₂
In the present invention, the light refractive index of conventional transparent conductive films such as ZnO and ZnO is about 2.0, while in the present invention, the light refractive index is changed from 2.4 to 1 by changing the quasi-ternary composition. A remarkable effect that a highly light-transmissive transparent conductive film that can be controlled over a wide range of .6 and can sufficiently meet various uses of the transparent conductive film was recognized. For example, by appropriately combining MgIn ₂ O ₄ having a light refractive index of about 2.0, Zn ₂ In ₂ O _{5 of} 2.4 and InGaO ₃ of 1.6, an antireflection coating film, an interference filter or a reflector. The remarkable effect that the new application that the (black reflector) can be composed of the conductive thin film as in the present invention becomes possible is recognized.

[Brief description of drawings]

FIG. 1 shows composition dependence of bandgap energy, resistivity, light refractive index and average visible light transmittance of the transparent conductive film obtained in Example 1 of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C23C 16/40 C23C 16/40

Claims (4)

[Reference number] MT41227DD [Claims] 1. A transparent conductive film comprising a base and a thin film of an oxide containing a group II, a group III and a group IV element formed thereon. 2. The group II element according to claim 1, which is zinc (Zn), cadmium (Cd) or magnesium (M
g), boron (B), aluminum (Al), gallium (Ga), indium (In) or yttrium (Y) as a group III element, and silicon (S) as a group IV element.
i), germanium (Ge), tin (Sn), lead (P)
b), titanium (Ti) or zirconium (Zr)
The transparent conductive film according to claim 1, wherein 3. The component of the film according to claim 1 is (Zn, C
d, Mg) O- (B, Al, Ga, In, Y) 2 O 3 -
In the quasi-ternary system containing a mixed crystal represented by (Si, Ge, Sn, Pb, Ti, Zr) O ₂ , [0.1 + x] (Z
n, Cd, Mg) O- [0.1] (B, Al, Ga, I
_{n, Y) 2 O 3 -} [99.8-x] (Si, Ge, Sn,
Pb, Ti, Zr) O ₂ , [99.8-x] (Zn, C
d, Mg) O- [0.1 + x] (B, Al, Ga, I
n, Y) ₂ O _3- [0.1] (Si, Ge, Sn, Pb,
Ti, Zr) O ₂ , [0.1] (Zn, Cd, Mg) O
-[99.8-x] (B, Al, Ga, In, Y)-
[0.1 + x] (Si, Ge, Sn, Pb, Ti, Z
r) O ₂ or an oxide of a group IV element is a group of (Si, S
n, Pb) O replaced with pseudo-ternary or quaternary composition range surrounded by the above respective regions, where 0 ≦ x ≦ 99.7
[Mole%], 3.
The transparent conductive film described. 4. A sintered body used for producing the transparent conductive film according to claim 1, 2.