JP5695221B2 - Sintered body and amorphous film - Google Patents

Description

  The present invention relates to a sintered body capable of obtaining a transparent conductive film having good visible light transmittance and conductivity, and an amorphous film having a low refractive index and produced using the sintered body.

 Conventionally, as a transparent conductive film, a film obtained by adding tin to indium oxide, that is, an ITO (Indium-Tin-oxide) film is transparent and excellent in electrical conductivity, and is used in a wide range of applications such as various displays. However, this ITO has a problem that the manufacturing cost is inferior because indium which is a main component is expensive.

 For this reason, as an alternative to ITO, for example, proposals have been made to use a film using zinc oxide (ZnO). Since the film is mainly composed of zinc oxide, there is an advantage that the price is low. Such a film is known to increase in conductivity due to oxygen vacancies in ZnO, which is the main component, and if the film properties of conductivity and light transmission are similar to those of ITO, the use of such materials will increase. there's a possibility that.

 By the way, when using visible light in a display or the like, the material needs to be transparent, and in particular, it is preferable that the transmittance is high in the entire visible light region. In addition, if the refractive index is high, the optical loss increases and the viewing angle dependency of the display deteriorates. Therefore, the refractive index is low, and the film is an amorphous film to improve the film cracking and etching performance. It is also desirable.

 Since the amorphous film has low stress, cracks are unlikely to occur compared to the crystal film, and it is considered that the amorphous film is required to be used for display in the future toward flexible use. The above ITO needs to be crystallized in order to improve the resistance value and transmittance, and if it is amorphous, it absorbs in the short wavelength region and does not become a transparent film. Not suitable for.

 As materials using zinc oxide, IZO (indium oxide-zinc oxide), GZO (gallium oxide-zinc oxide), AZO (aluminum oxide-zinc oxide), and the like are known (Patent Documents 1 to 3). However, although IZO can be a low-resistance amorphous film, it has a problem that it has absorption in a short wavelength region and has a high refractive index. Further, GZO and AZO are likely to become crystallized films due to the ease of ZnO c-axis orientation, and such crystallized films have problems such as film peeling and film cracking because stress increases.

 Further, Patent Document 4 discloses a light-transmitting conductive material that realizes a wide refractive index mainly composed of ZnO and an alkaline earth metal fluoride compound. However, this is a crystallized film, and the effect of the amorphous film as in the present invention described later cannot be obtained. Patent Document 5 discloses a transparent conductive film that has a low refractive index and a low specific resistance and is amorphous. However, the composition system differs from the present invention, and the refractive index and the resistance value are disclosed. Cannot be adjusted together.

JP 2007-008780 A JP 2009-184876 A JP 2007-238375 A JP 2005-219982 A JP 2007-035342 A

  It is an object of the present invention to provide a transparent conductive film capable of maintaining good visible light transmittance and conductivity, in particular, a sintered body capable of obtaining an amorphous film having a low refractive index. Since this thin film has high transmittance and excellent mechanical properties, it is useful as a transparent conductive film for displays and a protective film for optical displays. Accordingly, it is an object to improve the characteristics of the optical device, reduce the equipment cost, and greatly improve the film forming characteristics.

 In order to solve the above-mentioned problems, the present inventors have conducted intensive research. As a result, by replacing the conventional transparent conductive film such as ITO with the material system shown below, the resistivity and refractive index can be arbitrarily set It is possible to adjust to the above, ensuring optical characteristics equal to or higher than conventional, stable film formation using a sputtering method or on-plating method, and further by using an amorphous film, We obtained the knowledge that it is possible to improve the characteristics and productivity of optical devices with thin films.

In order to solve the above-mentioned problems, the present inventors have conducted intensive studies and provide the following invention.
1) A sintered body containing zinc (Zn), tin (Sn) and / or indium (In), magnesium (Mg), oxygen (O), and the total content of Sn and / or In is SnO ₂ And / or 10 to 90 mol% in terms of In ₂ O ₃ , when the ratio of the number of Sn and / or In to the number of Zn atoms is 1 or less, the content of Mg is 15 to 50 mol% in terms of MgF ₂ , An oxide sintered body characterized in that when the ratio of the number of Sn and / or In to the number of Zn atoms is 1 or more, the Mg content is 1 to 40 mol% in terms of MgF ₂ ;
2) Further, gallium (Ga), aluminum (Al) and / or boron (B) is contained, and the total content of Ga and / or B is 0.1 in terms of Ga ₂ O ₃ and / or B ₂ O _3. The oxide sintered body according to 1) above, which is 10 mol%,
3) A sputtering target using the oxide sintered body according to 1) or 2) above,
4) An ion plating material characterized by using the oxide sintered body described in 1) or 2) above is provided.

The present invention also provides:
5) A thin film containing zinc (Zn), tin (Sn) and / or indium (In), magnesium (Mg), oxygen (O), wherein the total content of Sn and / or In is SnO ₂ and / or Alternatively, when the ratio of Sn and / or In atoms to Zn atoms is 1 or less in terms of In ₂ O ₃ , the content of Mg is 15 to 50 mol% in terms of MgF ₂ , A thin film characterized in that when the ratio of the number of Sn and / or In to the number of atoms is 1 or more, the Mg content is 1 to 40 mol% in terms of MgF ₂ and is amorphous;
6) Furthermore, it contains gallium (Ga), aluminum (Al) and / or boron (B), and the total content of Ga and / or B is 0.1 in terms of Ga ₂ O ₃ and / or B ₂ O _3. The thin film according to 5) above, which is 10 mol%,
7) The thin film according to 5) or 6) above, wherein the refractive index at a wavelength of 550 nm is 2.0 or less,
8) The thin film according to any one of 5) to 7) above, which has a specific resistance of 1 mΩ · cm to 1 MΩ · cm.

 According to the present invention, an amorphous film can be formed by a sputtering method or an ion plating method, and there is an effect that film cracking due to stress is small and occurrence of film peeling can be suppressed. Further, it is possible to provide a sintered material useful for a thin film having an excellent characteristic of low refractive index, particularly an optical thin film for forming a protective layer of an optical information recording medium, a thin film for an organic EL television, and a thin film for a transparent electrode.

The oxide sintered body of the present invention is a sintered body containing zinc (Zn), tin (Sn) and / or indium (In), magnesium (Mg), oxygen (O), and Sn and / or When the total content of In is 10 to 90 mol% in terms of SnO ₂ and / or In ₂ O ₃ and the ratio of the number of Sn and / or In to the number of Zn atoms is 1 or less, the content of Mg is MgF 15～50Mol% in ₂ terms, when the ratio of Sn and / or in the number of atoms to the number of atoms of Zn is 1 or more, the content of Mg is an 1～40Mol% by MgF ₂ terms, Ya sputtering An amorphous film can be formed by an ion plating method.

At the time of adjusting the raw materials, the balance is adjusted so that the total is 100 mol% with the balance being ZnO. Therefore, the Zn content can be determined from the remaining ZnO equivalent. By setting it as such a composition, the amorphous film of a low refractive index can be formed and the said effect of this invention is acquired.
In addition, in this invention, although content of each metal in a sintered compact is prescribed | regulated in conversion of an oxide, each metal in a sintered compact exists in part or all as complex oxide. Moreover, in the component analysis of the sintered body normally used, each content is measured not as an oxide but as a metal.

The present invention is characterized in that magnesium fluoride (MgF ₂ ) is added to form an amorphous film having a low refractive index. The Mg content is 15 to 50 mol% in terms of MgF ₂ when the ratio of Sn and / or In atoms to Zn atoms is 1 or less, and the ratio of Sn and / or In atoms to Zn atoms is when it is 1 or more, by a 1～40Mol% by MgF ₂ terms, it is possible to form a film of amorphous and low refractive index. Thereby, the generation | occurrence | production of the crack of a film | membrane and a crack can be reduced, and peeling of a film | membrane can be suppressed.

In the oxide sintered body of the present invention, an oxide of gallium (Ga) and / or boron (B) can be added in order to impart conductivity to the film. Since conductivity is reduced by the addition of magnesium fluoride, it is preferable to add an oxide of Ga or B depending on the amount of magnesium fluoride added. When the amount of magnesium fluoride added is small, desired conductivity can be obtained without adding Ga or B oxides. In the present invention, the total content of at least Ga and / or B, by a 0.1 to 10 mol% in _Ga 2 _{O 3} and / or terms _{of B} 2 _{O 3,} it is possible to obtain a desired conductivity.

 In the present invention, it is particularly important that an amorphous thin film can be formed by using a sputtering target method or an ion plating method. Since a thin film containing ZnO has a large film stress, if it is a crystallized film, cracks and cracks occur, and further problems such as film peeling occur. By making this thin film an amorphous film, there is an excellent effect that problems such as cracks and cracks due to film stress can be avoided. Whether the obtained film is an amorphous film is determined by, for example, observing the diffraction intensity in the vicinity of 2θ = 34.4 ° where the peak of the (002) plane of ZnO appears by using an X-ray diffraction method. Can be judged.

Further, a film formed by sputtering a target obtained by machining the sintered body of the present invention or a film formed by the ion plating may have a refractive index of 2.0 or less at a wavelength of 550 nm. preferable. Magnesium fluoride (MgF ₂ ), gallium oxide (Ga ₂ O ₃ ), and boron oxide (B ₂ O ₃ ) are materials having a lower refractive index than zinc oxide, tin oxide, or indium oxide. A film having a low refractive index can be obtained by adding a fluoride or oxide.

According to the present invention, zinc (Zn), tin (Sn) and / or indium (In), magnesium (Mg), oxygen (O) is contained, and the total content of Sn and / or In is SnO ₂ and / Or 10 to 90 mol% in terms of In ₂ O ₃ , and the Mg content is 15 to 50 mol in terms of MgF ₂ when the ratio of the number of Sn and / or In atoms to the number of Zn atoms is 1 or less. %, When the ratio of the number of Sn and / or In to the number of Zn atoms is 1 or more, it is 1 to 40 mol% in terms of MgF ₂ , and an amorphous thin film can be produced.
When the thin film of the present invention is used for organic EL televisions, transparent electrodes, and the like, it is desirable to have a refractive index and a conductivity suitable for these applications. The refractive index is more preferably 2.0 or less at a wavelength of 550 nm, and the conductivity is more preferably 1 mΩ · cm or more and 1,000,000 (1M) Ω · cm or less.

  Hereinafter, description will be made based on Examples and Comparative Examples. In addition, a present Example is an example to the last, and is not restrict | limited at all by this example. In other words, the present invention is limited only by the scope of the claims, and includes various modifications other than the examples included in the present invention.

Example 1
3N corresponds with 5 [mu] m or less of ZnO powder were prepared an average particle size 5 [mu] m or less of SnO ₂ powder, 3N average particle size 5 [mu] m or less of MgF ₂ powder with equivalent, 5 [mu] m following _Ga 2 _{O 3} powder with 3N corresponds with 3N equivalent. Next, ZnO powder, SnO ₂ powder, MgF ₂ powder, and Ga ₂ O ₃ powder were changed to ZnO: SnO ₂ : MgF ₂ : Ga ₂ O ₃ = 45.5: 30.4: 22.9: 1.25 mol%. Then, the powder material was hot-press sintered at a temperature of 850 ° C. and a pressure of 250 kgf / cm ² to obtain a sintered body for ion plating. As a result of ion plating using this sintered body, stable ion plating was achieved, and it was confirmed that the produced film was an amorphous film. The refractive index of the film reached 1.87 (wavelength 550 nm).

(Example 2)
3N corresponds with 5 [mu] m or less of ZnO powder were prepared an average particle size 5 [mu] m or less of SnO ₂ powder, 3N average particle size 5 [mu] m or less of MgF ₂ powder with equivalent, 5 [mu] m following _Ga 2 _{O 3} powder with 3N corresponds with 3N equivalent. Next, ZnO powder, SnO ₂ powder, MgF ₂ powder, and Ga ₂ O ₃ powder were changed to ZnO: SnO ₂ : MgF ₂ : Ga ₂ O ₃ = 68.21: 11.76: 18.24: 1.79 mol%. Then, the powder material was hot-press sintered at a temperature of 850 ° C. and a pressure of 250 kgf / cm ² to obtain a sintered body for ion plating. As a result of ion plating using this sintered body, stable ion plating was achieved, and it was confirmed that the produced film was an amorphous film. The refractive index of the film reached 1.87 (wavelength 550 nm).

(Example 3)
ZnO powder with 3N equivalent and 5 μm or less, 3N equivalent and In ₂ O ₃ powder with average particle size of 5 μm or less, 3F and MgF ₂ powder with average particle size of 5 μm or less, 3N equivalent with 5 μm or less Ga ₂ O ₃ powder did. Next, ZnO powder, In ₂ O ₃ powder, MgF ₂ powder, and Ga ₂ O ₃ powder were changed to ZnO: In ₂ O ₃ : MgF ₂ : Ga ₂ O ₃ = 66.7: 21.3: 14.9: After blending to a blending ratio of 8.3 mol% and mixing this, the powder material was hot-press sintered at a temperature of 850 ° C. and a pressure of 250 kgf / cm ² to obtain a sintered body for ion plating. As a result of ion plating using this sintered body, stable ion plating was achieved, and it was confirmed that the produced film was an amorphous film. The refractive index of the film reached 1.85 (wavelength 550 nm).

(Example 5)
ZnO powder of 3N equivalent to 5 μm or less, 3N equivalent of In ₂ O ₃ powder with an average particle size of 5 μm or less, 3N equivalent of MgF ₂ powder with an average particle size of 5 μm or less, 3N equivalent of B ₂ O ₃ powder of 5 μm or less did. Next, ZnO powder, In ₂ O ₃ powder, MgF ₂ powder, and B ₂ O ₃ powder were changed to ZnO: In ₂ O ₃ : MgF ₂ : B ₂ O ₃ = 41.1: 12.1: 45.8: After blending to a mixing ratio of 1.0 mol% and mixing this, the powder material was hot-press sintered at a temperature of 850 ° C. and a pressure of 250 kgf / cm ² to obtain a sintered body for ion plating. As a result of ion plating using this sintered body, stable ion plating was achieved, and it was confirmed that the produced film was an amorphous film. The refractive index of the film reached 1.70 (wavelength 550 nm).

(Example 6)
3N corresponds with 5 [mu] m or less of ZnO powder were prepared an average particle size 5 [mu] m or less of SnO ₂ powder, 3N average particle size 5 [mu] m or less of MgF ₂ powder with equivalent, 5 [mu] m following _Ga 2 _{O 3} powder with 3N corresponds with 3N equivalent. Next, ZnO powder, SnO ₂ powder, MgF ₂ powder, and Ga ₂ O ₃ powder were changed to ZnO: SnO ₂ : MgF ₂ : Ga ₂ O ₃ = 25.4: 38.1: 25.4: 3.0 mol%. Then, the powder material was hot-press sintered at a temperature of 850 ° C. and a pressure of 250 kgf / cm ² to obtain a sintered body for ion plating. As a result of ion plating using this sintered body, stable ion plating was achieved, and it was confirmed that the produced film was an amorphous film. The refractive index of the film reached 1.80 (wavelength 550 nm).

(Example 7)
3N corresponds with 5 [mu] m or less of ZnO powder were prepared an average particle size 5 [mu] m or less of SnO ₂ powder, 3N average particle size 5 [mu] m or less of MgF ₂ powder with equivalent, 5 [mu] m following _Ga 2 _{O 3} powder with 3N corresponds with 3N equivalent. Next, ZnO powder, SnO ₂ powder, MgF ₂ powder, and Ga ₂ O ₃ powder were changed to ZnO: SnO ₂ : MgF ₂ : Ga ₂ O ₃ = 31.1: 57.8: 8.0: 3.0 mol%. Then, the powder material was hot-press sintered at a temperature of 850 ° C. and a pressure of 250 kgf / cm ² to obtain a sintered body for ion plating. As a result of ion plating using this sintered body, stable ion plating was achieved, and it was confirmed that the produced film was an amorphous film. The refractive index of the film reached 1.98 (wavelength 550 nm).

(Example 8)
ZnO powder with 3N equivalent and 5 μm or less, SnO ₂ powder with 3N equivalent and average particle size of 5 μm or less, MgF ₂ powder with 3N equivalent and average particle size of 5 μm or less, AlN ₂ O ₃ powder with 3N equivalent and 5 μm or less, 3N equivalent A B ₂ O ₃ powder having an average particle size of 5 μm or less was prepared. Next, the ZnO powder and SnO ₂ and MgF ₂ powder and _Al 2 _{O 3} powder and _B 2 _{O 3 powder, ZnO: SnO 2: MgF 2} : Al 2 O 3: B 2 O 3 = 68.2: 14. After blending to a blending ratio of 2: 15.3: 1.8: 0.5 mol% and mixing this, the powder material was hot-press sintered in vacuum at a temperature of 1100 ° C. and a pressure of 250 kgf / cm ² . Thereafter, the sintered body was machined to finish a sputtering target shape. As a result of measuring the bulk resistance and relative density of the obtained target, the relative density reached 98.2%, the bulk resistance was 3.1 mΩ · cm, and stable DC sputtering was possible.
Next, sputtering was performed using the above-finished target. The sputtering conditions were DC sputtering, sputtering power 500 W, Ar gas pressure 0.5 Pa containing ₂ vol%, and a film thickness of 1500 to 7000 mm. It was confirmed that the produced thin film was an amorphous film. The refractive index of the film reached 1.94 (wavelength 550 nm).

Example 9
3N equivalent ZnO powder of 5 μm or less, 3N equivalent of In ₂ O ₃ powder with an average particle size of 5 μm or less, 3N equivalent of MgF ₂ powder with an average particle size of 5 μm or less, 3N equivalent of 5 μm or less Al ₂ O ₃ powder, 3N A B ₂ O ₃ powder having an average particle size of 5 μm or less was prepared. Next, ZnO powder, In ₂ O ₃ powder, MgF ₂ powder, Al ₂ O ₃ powder, and B ₂ O ₃ powder were changed to ZnO: In ₂ O ₃ : MgF ₂ : Al ₂ O ₃ : B ₂ O ₃ = 56. : 37.3: 5.0: 1.3: After mixing to 0.5 mol% and mixing this, the powder material is hot-press sintered at a temperature of 1100 ° C. and a pressure of 250 kgf / cm ² in a vacuum. did. Thereafter, the sintered body was machined to finish a sputtering target shape. As a result of measuring the bulk resistance and relative density of the obtained target, the relative density reached 99.1%, the bulk resistance became 3.2 mΩ · cm, and stable DC sputtering was possible.
Next, sputtering was performed using the above-finished target. The sputtering conditions were DC sputtering, sputtering power 500 W, Ar gas pressure 0.5 Pa containing ₂ vol%, and a film thickness of 1500 to 7000 mm. It was confirmed that the produced thin film was an amorphous film. The refractive index of the film reached 1.94 (wavelength 550 nm).

(Comparative Example 1)
3N corresponds with 5 [mu] m or less of ZnO powder were prepared an average particle size 5 [mu] m or less of SnO ₂ powder, 3N average particle size 5 [mu] m or less of MgF ₂ powder with equivalent, 5 [mu] m following _Ga 2 _{O 3} powder with 3N corresponds with 3N equivalent. Next, ZnO powder, SnO ₂ powder, MgF ₂ powder, and Ga ₂ O ₃ powder were changed to ZnO: SnO ₂ : MgF ₂ : Ga ₂ O ₃ = 21.2: 31.8: 45.0: 2.0 mol%. Then, the powder material was hot-press sintered at a temperature of 850 ° C. and a pressure of 250 kgf / cm ² to obtain a sintered body for ion plating. As a result of ion plating using this sintered body, it was confirmed that the produced film was an amorphous film, but the specific resistance of the film exceeded 1 MΩ · cm, and the conductivity was inferior. It became.

(Comparative Example 2)
3N corresponds with 5 [mu] m or less of ZnO powder were prepared an average particle size 5 [mu] m or less of SnO ₂ powder, 3N average particle size 5 [mu] m or less of MgF ₂ powder with equivalent, 5 [mu] m following _Ga 2 _{O 3} powder with 3N corresponds with 3N equivalent. Next, ZnO powder, SnO ₂ powder, MgF ₂ powder, and Ga ₂ O ₃ powder were changed to ZnO: SnO ₂ : MgF ₂ : Ga ₂ O ₃ = 79.2: 8.8: 10.0: 2.0 mol%. Then, the powder material was hot-press sintered at a temperature of 850 ° C. and a pressure of 250 kgf / cm ² to obtain a sintered body for ion plating. As a result of ion plating using this sintered body, the produced film was not an amorphous film.

(Comparative Example 3)
3N corresponds with 5 [mu] m or less of ZnO powder were prepared an average particle size 5 [mu] m or less of SnO ₂ powder, 3N average particle size 5 [mu] m or less of MgF ₂ powder with equivalent, 5 [mu] m following _Ga 2 _{O 3} powder with 3N corresponds with 3N equivalent. Next, ZnO powder, SnO ₂ powder, MgF ₂ powder, and Ga ₂ O ₃ powder were changed to ZnO: SnO ₂ : MgF ₂ : Ga ₂ O ₃ = 26.6: 11.4: 60.0: 2.0 mol%. Then, the powder material was hot-press sintered at a temperature of 850 ° C. and a pressure of 250 kgf / cm ² to obtain a sintered body for ion plating. As a result of ion plating using this sintered body, it was confirmed that the produced film was an amorphous film, but the specific resistance of the film exceeded 1 MΩ · cm, and the conductivity was inferior. It became.

(Comparative Example 4)
3N corresponds with 5 [mu] m or less of ZnO powder were prepared an average particle size 5 [mu] m or less of SnO ₂ powder, 3N average particle size 5 [mu] m or less of MgF ₂ powder with equivalent, 5 [mu] m following _Ga 2 _{O 3} powder with 3N corresponds with 3N equivalent. Next, ZnO powder, SnO ₂ powder, MgF ₂ powder, and Ga ₂ O ₃ powder were changed to ZnO: SnO ₂ : MgF ₂ : Ga ₂ O ₃ = 13.2: 26.4: 55.0: 1.0 mol%. Then, the powder material was hot-press sintered at a temperature of 850 ° C. and a pressure of 250 kgf / cm ² to obtain a sintered body for ion plating. As a result of ion plating using this sintered body, it was confirmed that the produced film was an amorphous film, but the specific resistance of the film exceeded 1 MΩ · cm, and the conductivity was inferior. It became.

 The sintered body of the present invention can be used as a sputtering target or an ion plating material, and a thin film formed using these sputtering target or ion plating material can protect a transparent conductive film and an optical disk in various displays. As a film, there is an effect that it has extremely excellent characteristics in terms of transmittance, refractive index, and conductivity. Further, the present invention has an excellent effect that the film can be remarkably improved in cracking and etching performance due to the amorphous film.

 The sputtering target using the sintered body of the present invention has a low bulk resistance value and a high relative density of 90% or more, and thus enables stable DC sputtering. And there is a remarkable effect that the controllability of sputtering, which is a feature of this DC sputtering, can be facilitated, the film forming speed can be increased, and the sputtering efficiency can be improved. RF sputtering is performed as necessary, but even in this case, the film formation rate is improved. In addition, particles (dust generation) and nodules generated during sputtering during film formation can be reduced, and quality variation can be reduced and mass productivity can be improved.

Moreover, since the ion plating material using the sintered body of the present invention can form an amorphous film having a low refractive index, it is possible to suppress the occurrence of cracks and cracks due to film stress, and film peeling. It has the effect. Such an amorphous film is particularly useful for an optical thin film for forming a protective layer of an optical information recording medium, a thin film for an organic EL television, and a thin film for a transparent electrode.

Claims (8)

A sintered body containing zinc (Zn), tin (Sn) and / or indium (In), magnesium (Mg), and oxygen (O), wherein the total content of Sn and / or In is SnO ₂ and / or Alternatively, when the ratio of Sn and / or In atoms to Zn atoms is 1 or less in terms of In ₂ O ₃ , the content of Mg is 15 to 50 mol% in terms of MgF ₂ , when the ratio of Sn and / or in the number of atoms is 1 or more with respect to the number of atoms, the oxide sintered body in which the content of Mg is characterized by a 1～40Mol% by MgF ₂ terms. Further gallium (Ga), aluminum containing (Al) and / or boron (B), Ga and / or 0.1 to 10 mol% total content of B is _Ga 2 _{O 3} and / or terms _{of B} 2 _{O 3} The oxide sintered body according to claim 1, wherein:  A sputtering target using the oxide sintered body according to claim 1.  An ion plating material using the oxide sintered body according to claim 1 or 2. A thin film containing zinc (Zn), tin (Sn) and / or indium (In), magnesium (Mg), oxygen (O), and the total content of Sn and / or In is SnO ₂ and / or In _When the ratio of the number of Sn and / or In to the number of Zn atoms is 1 or less in terms of ₂ O ₃ , the content of Mg is 15 to 50 mol% in terms of MgF ₂ , and the number of Zn atoms A thin film characterized in that when the ratio of the number of Sn and / or In atoms to 1 is 1 or more, the Mg content is 1 to 40 mol% in terms of MgF ₂ and is amorphous. Further gallium (Ga), aluminum containing (Al) and / or boron (B), Ga and / or 0.1 to 10 mol% total content of B is _Ga 2 _{O 3} and / or terms _{of B} 2 _{O 3} The thin film according to claim 5, wherein:  The thin film according to claim 5 or 6, wherein a refractive index at a wavelength of 550 nm is 2.0 or less. The specific resistance is 1 mΩ · cm to 1 MΩ · cm, and the thin film according to claim 5.