JP4729704B2 - Method for producing metal oxide film - Google Patents

Description

  The present invention relates to a method of manufacturing a metal oxide film on a substrate, and more particularly to a method of manufacturing a crystalline metal oxide film using vacuum ultraviolet light.

  A sol-gel method is known as one method for forming a metal oxide film on the surface of a substrate. In a typical embodiment of the sol-gel method, a sol containing a metal alkoxide or the like constituting a target metal oxide is prepared, and the sol is applied to a substrate surface, and the gel includes the metal oxide precursor. A film is formed. Next, the gel-like film is subjected to heat treatment to crystallize the metal oxide. In order to obtain a crystalline metal oxide film by a general sol-gel method, it is necessary to perform the heat treatment at a high temperature. For this reason, when a crystalline metal oxide film is formed on the surface of a substrate made of a material having low heat resistance such as a thermoplastic resin, a sol-gel is used as a method for forming the oxide film. It was difficult to adopt the law. In this regard, Patent Documents 1 and 2 disclose a technique for crystallizing a metal oxide without requiring heat treatment at a high temperature by irradiating the metal oxide gel thin film with ultraviolet light having a wavelength of 360 nm or less. Are listed.

Japanese Patent Laid-Open No. 09-157855 JP 2000-247608 A Japanese Patent Laid-Open No. 08-69809

By the way, ultraviolet light having a wavelength of 200 nm or less is referred to as vacuum ultraviolet (Vacuum Ultra-Violet, VUV) light. Ultraviolet rays in this wavelength range are called “vacuum ultraviolet rays” because absorption by oxygen molecules starts from around 195 nm and the propagation distance is short in the atmosphere, so O ₂ is substantially present as in vacuum or nitrogen gas. It is derived from being used in an atmosphere that does not. In Patent Document 3, a precursor of a metal organic compound is applied to a substrate, dried, heated in a vacuum chamber and simultaneously irradiated with vacuum ultraviolet light to crystallize the YSZ thin film at a low temperature. A synthesis method is described.
However, in the method described in Patent Document 3, although the temperature is lower than that of the conventional method, the heat treatment (implementation in a temperature range exceeding the heat resistance temperature of a normal thermoplastic resin or the like is still performed for crystallization. In the example, 330 ° C.) is necessary. In the manufacture of a metal oxide film using vacuum ultraviolet light, it would be beneficial if a manufacturing method capable of forming a crystalline metal oxide film at a lower temperature could be provided.

The metal oxide film manufacturing method provided by the present invention includes preparing a precursor film containing a metal oxide precursor capable of forming a metal oxide by thermal decomposition. This manufacturing method also provides a vacuum ultraviolet ray having a dominant wavelength of 130 to 180 nm toward the film in an atmosphere having an O ₂ concentration of about 7 mol / m ³ or more (typically, about 7 to 40 mol / m ³ ). Irradiating with light to form a crystalline metal oxide film from the film. According to such a method, the vacuum ultraviolet light is absorbed by the O ₂ easy wavelengths by irradiating toward the coating with daringly O ₂ concentration high atmosphere, the crystalline metal oxide precursor contained in said coating This metal oxide film can be formed efficiently.
Note that the metal oxide film obtained by the method disclosed herein is crystalline by analyzing the metal oxide film by an X-ray diffraction (XRD) method (for example, the X-ray diffraction). Can be grasped by the fact that a clear peak is observed in the chart showing the measurement results. According to the method disclosed herein, it is possible to produce a crystalline metal oxide film in which a clear peak is observed in X-ray diffraction measurement.

  The film is, for example, a metal alkoxide (for example, an alkoxide having 1 to 4 carbon atoms) and / or a salt (for example, a halide such as chloride, nitrate, acetate, etc.) constituting the metal oxide film. Can be appropriately prepared by a method including preparing a sol containing, and applying the sol to the surface of the substrate to form a gel-like film.

  In one preferred embodiment of the method disclosed herein, the distance from the light source that irradiates the vacuum ultraviolet light to the surface of the coating is about 3 mm or less (typically about 0.5 to 3 mm). By irradiating the vacuum ultraviolet light from such a short distance, the energy of the vacuum ultraviolet light can be used for the formation of the crystalline metal oxide film more efficiently.

As the light source for irradiating the vacuum ultraviolet light, for example, one or more light sources selected from a xenon excimer lamp, an F ₂ excimer lamp, and an argon excimer lamp can be used. By using such a light source, a crystalline metal oxide film can be more efficiently formed from the precursor film.

  In one preferred embodiment of the method disclosed herein, the crystalline metal oxide film is formed from the film in a temperature range of 80 ° C. or lower (typically, room temperature to 80 ° C.). According to such an embodiment, the metal oxide film can be appropriately formed on the surface of a wider range of substrates (including substrates with low heat resistance).

  In another preferred embodiment of the method disclosed herein, the crystalline metal oxide film is formed from the film at room temperature (typically without forced heating or cooling from the outside). According to such an embodiment, the metal oxide film can be appropriately formed on a wider range of substrates (including substrates having low heat resistance). In addition, since a mechanism for heating or cooling when irradiating vacuum ultraviolet light can be omitted or simplified, the present invention can be used even with a simpler configuration and / or a smaller apparatus. There is an advantage that the method can be implemented.

  In another preferred embodiment of the method disclosed herein, the crystalline metal oxide film is formed from the film in air at atmospheric pressure. According to this aspect, at the time of irradiation with vacuum ultraviolet light, at least one of a mechanism for adjusting the composition of the atmospheric gas and / or a mechanism for adjusting the atmospheric pressure can be omitted or simplified. Therefore, the method of the present invention can be carried out using a simpler device and / or a smaller device.

  Preferable examples of the metal oxide film manufactured by applying the method disclosed herein include a crystalline zinc oxide film and a crystalline indium oxide film. That is, the method disclosed herein can be preferably performed, for example, in an embodiment in which the metal oxide is zinc oxide or indium oxide.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

In the method disclosed herein, an oxide of any metal selected from a transition metal element and a typical metal element, and / or two or more kinds of metals selected from these metal elements are used as constituent metal elements. It can be applied to the production of a metal oxide film substantially composed of a composite oxide. For example, zinc oxide (typically ZnO), indium oxide (typically In ₂ O ₃ ), tin oxide (typically SnO ₂ ), indium tin oxide (usually ITO) Copper oxide (typically CuO), aluminum oxide (typically Al ₂ O ₃ ), zirconium oxide (eg ZrO ₂ ), tungsten oxide (eg WO ₃ ) titanium oxide (eg TiO ₂ ), Suitable as a method for producing a metal oxide film containing any oxide selected from tantalum oxide (eg TaO ₆ ), silicon oxide (eg SiO ₂ ), etc., or two or more oxides selected from these oxides Can be employed. Further, the object of application of the method disclosed herein is not limited to the production of a metal oxide film substantially composed of the above-described specific metal oxide, but by a conventional general sol-gel method ( The method can be applied to the production of various metal oxide films that can be produced (by thermally decomposing gels containing metal oxide precursors at high temperatures). The production method of the present invention is a metal oxide film substantially composed of one or more (typically one) of such metal oxides, which is crystalline (for example, X-ray diffraction). This method is suitable as a method for forming a metal oxide film that shows a clear peak by measurement. As a particularly preferable application target of the manufacturing method of the present invention, a crystalline zinc oxide (ZnO) film and a crystalline indium oxide (In ₂ O ₃ ) film are exemplified.

  The method disclosed herein is suitable as a method for forming a crystalline metal oxide film on the surface of various substrates. The material of the substrate is not particularly limited, and for example, it may be a substrate made of one or more materials selected from glass, ceramics, metal, polymer material, and the like. The polymer material constituting the substrate may be either a thermoplastic resin or a thermosetting resin. For example, polyolefin (polyethylene, polypropylene, etc.), polyvinyl chloride, polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS) resin, acrylic resin, polyester (for example, polyethylene terephthalate (PET)) resin, various synthetic rubbers, etc. are used. A substrate constructed in this manner can be preferably selected. According to the method of the present invention, a crystalline metal oxide film can be formed from a precursor film without requiring heat treatment at a high temperature (for example, 300 ° C. or higher) as in the conventional general sol-gel method. Is possible. Therefore, by applying the method of the present invention, crystals are formed on the surface of a substrate formed using a material having a heat resistant temperature of 300 ° C. or lower (preferably 200 ° C. or lower, more preferably 150 ° C. or lower, more preferably 100 ° C. or lower). When forming a conductive metal oxide film, the effects of the present invention can be exhibited particularly well. The shape of the substrate to be used is not particularly limited. From the standpoint that the formation of the precursor film and the irradiation with vacuum ultraviolet light are easily performed uniformly, a base (for example, a flat base) having at least a substantially flat surface on which the metal oxide film is formed is preferable.

  In the method for producing a metal oxide film of the present invention, irradiation with vacuum ultraviolet light having a predetermined dominant wavelength is performed under predetermined conditions toward a precursor film containing a metal oxide precursor capable of forming a metal oxide by thermal decomposition. To do. Here, “a metal oxide precursor capable of forming a metal oxide by pyrolysis” can form a metal oxide by thermally decomposing the precursor at a high temperature as in the conventional general sol-gel method. It refers to a metal oxide precursor. Such a precursor film can be typically formed using a sol containing a metal alkoxide and / or a metal salt corresponding to the composition of the metal oxide constituting the target metal oxide film. Such a sol can be prepared using, for example, a metal salt corresponding to the composition of the metal oxide constituting the target metal oxide film and water for hydrolyzing the metal salt. For the preparation of the sol, if necessary, an appropriate solvent (preferably one that can prepare a homogeneous solution is preferably selected), a catalyst that can promote the hydrolysis (typically an acid or One or two or more selected from alcohol) and other additives (for example, surfactant) can be used.

  In a preferred embodiment of the method disclosed herein, such a sol is applied to a substrate surface, and the sol is reacted on the substrate to form a gel-like film. In order to promote the formation (gelation) of the gel-like film, the sol applied to the surface of the substrate is appropriately used as necessary (for example, at a temperature of room temperature to 100 ° C., preferably 40 ° C. to 80 ° C.). You may heat. The gel-like film thus obtained is irradiated with vacuum ultraviolet light. Or you may irradiate a vacuum ultraviolet light toward the film | membrane which dried this gel-like film | membrane appropriately. The preparation of the sol, the application of the sol to the substrate, and the formation of the precursor film may be carried out by appropriately adopting a technique similar to the conventional general sol-gel method, and particularly characterizes the present invention. Since it is not a thing, detailed description is abbreviate | omitted.

In the present invention, a crystalline metal oxide film is formed by irradiating vacuum ultraviolet light having a dominant wavelength (the maximum peak in a spectroscopic spectrum) of 130 to 180 nm toward the precursor film. This range of the main wavelength is selected from the viewpoint of being easily absorbed by oxygen molecules (in particular, an oxygen absorption band near 153 nm is easily used). According to vacuum ultraviolet light having such a main wavelength, oxygen radicals (typically, doublet atomic radicals) can be efficiently generated from oxygen molecules in the atmosphere. In the production method disclosed herein, the irradiation of the vacuum ultraviolet light is further performed in an atmosphere having an O ₂ concentration of 7 mol / m ³ or more (typically about 7 to 40 mol / m ³ ). More preferably, the vacuum ultraviolet light is irradiated in an atmosphere having an O ₂ concentration of 8 mol / m ³ or more (typically about 8 to 40 mol / m ³ ). In the method of the present invention, a large amount of oxygen radicals can be generated by irradiating vacuum ultraviolet light having the above-mentioned dominant wavelength under an O ₂ concentration that is remarkably higher than that of normal use of vacuum ultraviolet light. Such oxygen radicals contribute to the formation of the crystalline metal oxide film, whereby the crystalline metal oxide film can be efficiently formed from the precursor film. That is, according to the manufacturing method of the present invention, by utilizing such an oxygen sensitizing type process, it is possible to crystallize the precursor film without requiring heat treatment at a high temperature as in the conventional general sol-gel method. Metal oxide film can be formed.

As the light source that can be used for irradiating vacuum ultraviolet light having the above-mentioned main wavelength, one or two selected from the group consisting of xenon excimer, F ₂ excimer, krypton excimer, argon excimer, ArBr excimer, and ArCl excimer are used. The thing using the excimer light obtained by the excimer of a seed | species or more can be illustrated. For example, one or more light sources selected from the group consisting of a xenon excimer lamp (main wavelength 172 nm), an F ₂ excimer lamp (main wavelength 157 nm), and an argon excimer lamp (main wavelength 126 nm) can be preferably used. .

In a preferred embodiment, the vacuum ultraviolet light irradiation is performed in an atmosphere having the above-described O ₂ concentration and an O ₂ partial pressure of approximately 20 to 100% of the total pressure (ie, the pressure of the atmospheric gas). . From the viewpoint of simplifying the device configuration, the total pressure is preferably set to a range of approximately 50 to 200% (for example, about 5 × 10 ⁴ Pa to 2 × 10 ⁵ Pa) with respect to the atmospheric pressure. It is more preferable that the pressure is within the range of about 80 to 150% (for example, about 8 × 10 ⁴ Pa to 1.5 × 10 ⁵ Pa) with respect to the atmospheric pressure, and the atmospheric pressure or the range of about ± 10% thereof is preferable. Is more preferable. Further, from the viewpoint of easy handling of atmospheric gas and control of irradiation conditions, it is preferable to irradiate the vacuum ultraviolet light in an atmosphere having an oxygen partial pressure (P _O2 ) of 20 to 50% of the total pressure. For example, may the O ₂ concentration Do the same extent as the air, or the O ₂ concentration in the air in the O ₂ concentration atmosphere in the range of approximately 100 to 150 percent 100 percent irradiating the vacuum ultraviolet light. One particularly preferable embodiment of the method disclosed herein includes an embodiment in which the vacuum ultraviolet light is irradiated in air at atmospheric pressure.

Under the O ₂ concentration as described above, the vacuum ultraviolet light attenuates rapidly with distance. For this reason, if the distance from the light source to the precursor film is too large, the position where oxygen radicals are generated becomes far from the film, and the utilization efficiency of the oxygen radicals tends to decrease. From this point of view, the distance from the light source to the precursor film is preferably about 3 mm or less (typically about 0.5 to 3 mm), and about 2.5 mm or less (typically about 0.5 mm). More preferably, it is set to 2.5 mm). Here, the distance from the light source to the precursor film refers to the distance from the outer surface of the lamp used as the light source to the outer surface of the precursor film. Therefore, the distance can be grasped as the thickness of the atmospheric gas (having the above-described O ₂ concentration) interposed between the light source and the precursor film.

The temperature at which the irradiation with the vacuum ultraviolet light is performed (that is, the temperature at which the metal oxide film is formed from the precursor film) is not particularly limited. In the method of the present invention, a crystalline metal oxide film is, for example, 120 ° C. or less (in a preferred embodiment, 100 ° C. or less, in a more preferred embodiment) by irradiating predetermined vacuum ultraviolet light under the above irradiation conditions. It can be formed in a temperature range of 80 ° C. or lower, and more preferably 60 ° C. or lower. Therefore, according to the method of the present invention, the surface of a substrate that is difficult to apply the conventional general sol-gel method (typically, a substrate formed using a material having a low heat-resistant temperature such as polyethylene) A crystalline metal oxide film can be appropriately formed. The lower limit of the irradiation temperature of the vacuum ultraviolet light is not particularly limited. However, in consideration of production efficiency, energy cost, simplification of the manufacturing apparatus, etc., the lower limit of the irradiation temperature is usually approximately the same as room temperature (environment temperature). Is appropriate. According to the manufacturing method of the present invention, for example, by performing irradiation with the vacuum ultraviolet light at room temperature (typically without forcibly heating or cooling from the outside), a crystalline metal oxide film is formed. It can be formed appropriately. However, for the purpose of stabilizing the quality of the obtained metal oxide film, the temperature may be adjusted so that the irradiation temperature of the vacuum ultraviolet light is maintained near room temperature.
In addition, when a metal oxide film is formed on the surface of a substrate made of a material having relatively high heat resistance (such as a silicon substrate) by applying the method of the present invention, the surface of the substrate made of a material having lower heat resistance Compared with the case where a metal oxide film is formed, the irradiation temperature of the vacuum ultraviolet light can be appropriately selected from a wider temperature range.

The time for performing the vacuum ultraviolet light irradiation is not particularly limited, and may be a time during which a target metal oxide film having crystallinity can be formed. From the viewpoint of production efficiency, usually, the irradiation conditions (for example, the O ₂ concentration of the atmospheric gas, the light source of the light source) are set so that the irradiation time is about 24 hours or less (more preferably 12 hours or less, more preferably 8 hours or less). It is appropriate to select one or more conditions selected from the type, the output of the light source, the distance from the light source to the precursor film, and the irradiation temperature.

  In one particularly preferred embodiment of the method disclosed herein, a primary wavelength of 130 at a room temperature in air at atmospheric pressure toward a precursor film of a metal oxide (eg, zinc oxide and / or indium oxide). Irradiate vacuum ultraviolet light of ˜180 nm. This forms a crystalline metal oxide film. According to this aspect, the mechanism for adjusting the irradiation conditions (the composition of the atmospheric gas and the atmospheric temperature) is omitted or simplified, the energy required for the adjustment is reduced, the material cost required for the adjustment is reduced, and the irradiation conditions are controlled. One or two or more effects can be realized. The irradiation distance (distance from the light source to the precursor film) at this time is preferably in the range of 0.5 to 3 mm.

FIG. 6 shows a schematic configuration example of an apparatus suitable for irradiating the vacuum ultraviolet light toward the precursor film to form a crystalline metal oxide film. This metal oxide film manufacturing apparatus 10 roughly includes a chamber 12, vacuum ultraviolet light irradiation means 20 for irradiating the chamber with vacuum ultraviolet light, and an O ₂ concentration for adjusting the O ₂ concentration in the chamber. And control means 30.

The vacuum ultraviolet light irradiation means 20 includes a quartz glass irradiation window 22 provided on the wall surface (here, the ceiling surface) of the chamber 12 and a predetermined vacuum ultraviolet light (typically, through the irradiation window 22 into the chamber 12. A vacuum ultraviolet light source 24 such as a xenon excimer lamp capable of irradiating a vacuum ultraviolet light having a main wavelength of 130 to 180 nm, and a lamp house 26 that houses the vacuum ultraviolet light source. A gas inlet 27 is formed at one end of the lamp house 26. By supplying an inert gas (for example, N ₂ gas) from the gas supply means 28 connected to the inlet 27, the inside of the lamp house 26 can be maintained in an inert gas atmosphere (N ₂ gas atmosphere).

  A stage 14 is disposed inside the chamber 12 and below the irradiation window 22. The stage 14 includes a mounting table 142 on which an object to be irradiated (a substrate on which a precursor film is formed) 3 is disposed, and leg portions 144 that support the mounting table 142 so as to be movable up and down. The stage 14 having such a configuration can appropriately adjust the distance from the surface of the irradiation object 3 (typically, the outer surface of the precursor film) disposed on the mounting table 142 to the outer surface of the irradiation window 22. it can. For example, this distance can be about 3 mm or less (typically about 0.5 to 3 mm), and further about 2.5 mm or less (typically about 0.5 to 2.5 mm). .

The O ₂ concentration control means 30 is provided in the chamber 12 and an O ₂ gas supply means 32 that is connected to a gas inlet 122 provided in the chamber 12 and supplies a gas containing O ₂ into the chamber from the inlet. And an exhaust pump (for example, a rotary pump) 34 connected to the gas exhaust port 124. A valve 36 is provided in the gas discharge passage extending from the chamber 12 to the exhaust pump 34, whereby the open / close state (degree) of the passage can be controlled.

  Using the apparatus 10 having such a configuration, for example, a crystalline metal oxide film can be manufactured as follows. Hereinafter, a preferred example of a method for producing a metal oxide film will be described with reference to a schematic process diagram shown in FIG.

First, a substrate on which a metal oxide film is to be formed is prepared. In order to form a high-quality metal oxide film, it is usually preferable to previously clean the surface of the substrate (step 110). This cleaning can be performed using, for example, acetone, ethanol, and water (for example, ultrapure water) in this order.
On the other hand, as a sol constituent, a metal alkoxide and / or a metal salt (for example, chloride) corresponding to the composition of the metal oxide constituting the target metal oxide film and water for hydrolyzing it are weighed. (Step 120). These sol components are stirred and mixed to prepare a sol (step 130).
This sol is applied to the surface of the substrate (step 140). As a coating method, for example, a spin coating method can be preferably employed. Next, the substrate on which the sol has been applied is heated by an electric furnace (preferably, heated to about 40 to 80 ° C.) to dry and react the sol. For example, in the subsequent step 160, the sol may be dried so that the water content is about 3 to 10% by mass (more preferably about 3 to 7% by mass, for example, around 5% by mass). In this way, a precursor film is formed on the surface of the substrate (step 150).

The substrate (object to be irradiated) 3 on which the precursor film is formed as described above is carried into the chamber 12 of the apparatus 10 shown in FIG. 6 and placed on the mounting table 142 of the stage 14. The height of the mounting table 142 is adjusted by the legs 144 so that the distance from the outer surface of the irradiation window 22 to the outer surface of the precursor film becomes a predetermined value. Then, the vacuum ultraviolet light source 24 is turned on, and the precursor film is irradiated with vacuum ultraviolet light through the irradiation window 22 for a predetermined time (step 160). At this time, the temperature in the chamber 12 can be room temperature, and the pressure and atmosphere in the chamber can be an atmospheric air atmosphere. Further, by adjusting the composition and / or pressure of the atmospheric gas using the O ₂ concentration control means 30, it is possible to make the atmosphere in the chamber 12 have a higher O ₂ concentration than in the air. In this way, a metal oxide film is manufactured.

  Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the examples.

<Example 1: Production of ZnO film (1)>
A sol was prepared by dissolving in zinc chloride (ZnCl ₂ ) ethanol. The sol was spin-coated on the surface of a previously cleaned silicon substrate (acetone used was acetone, ethanol, and ultrapure water in this order), and this was coated at 40-80 ° C. in an electric furnace. The precursor film of the target ZnO film was formed by heating (drying / reacting). This precursor film was irradiated with vacuum ultraviolet light having a main wavelength of 130 to 180 nm under different O ₂ concentrations to obtain ZnO films of Samples 1 to 3.

[Sample 1]
This precursor-coated silicon substrate is placed in air at atmospheric pressure (atmospheric gas pressure of about 1 × 10 ⁵ Pa, O ₂ concentration of about 8 mol / m ³ ), and a xenon excimer lamp (made by USHIO INC., Model number) Using “UER20-172V”), the film was irradiated with vacuum ultraviolet light having a dominant wavelength of 172 nm at room temperature for 5 hours. The distance from the outer surface of the lamp to the surface of the precursor film was 2 mm. Thus, a ZnO film (sample 1) was produced on the surface of the silicon substrate.

[Sample 2]
A silicon substrate was prepared in the same manner as Sample 1 except that the vacuum ultraviolet light was irradiated in air at an atmospheric gas pressure of 1 × 10 ³ Pa (O ₂ concentration: about 8 × 10 ⁻³ mol / m ³ ). A ZnO film (sample 2) was produced on the surface of the film.

[Sample 3]
The surface of the silicon substrate was coated with ZnO in the same manner as in the preparation of Sample 1 except that the irradiation with vacuum ultraviolet light was performed in air with an atmospheric gas pressure of 10 Pa (O ₂ concentration: about 8 × 10 ⁻⁵ mol / m ³ ). A membrane (Sample 3) was prepared.

Each of the ZnO films of Sample 1, Sample 2, and Sample 3 and the above-described ZnO films obtained by heating the spin-coated sol in an electric furnace at 40 to 80 ° C. (ie, before irradiation with vacuum ultraviolet light) X-ray diffraction measurement was performed on the precursor film (Comparative Sample 1). The results are shown in FIG. In FIG. 1, in order to facilitate the comparison of diffraction results between samples, the measurement results for each sample are shown with their positions shifted in the vertical direction (from the top, Comparative Sample 1, Sample 1, Sample 2, Sample 3)). As can be seen from FIG. 1, in the ZnO film of Sample 1 obtained by setting the O ₂ concentration of the atmospheric gas at the time of xenon excimer lamp irradiation to 8 mol / m ³ , a clear peak indicating ZnO crystallinity (in FIG. 1) (A peak with a black circle) was confirmed. That is, it was confirmed that the ZnO film of Sample 1 was crystalline. FIG. 2 shows an image obtained by observing the ZnO film of Sample 1 with a scanning electron microscope (SEM). The scale bar in the figure indicates 1 μm. As is clear from this figure, it was also confirmed from the observation result by SEM that the ZnO film of Sample 1 actually has high crystallinity.

On the other hand, the O ₂ concentration of the atmospheric gas at the time of xenon excimer lamp irradiation was 8 × 10 ⁻³ mol / m ³ (sample 2; the third data from the top in FIG. 1) and 8 × 10 ⁻⁵ mol / In the ZnO film obtained as m ³ (sample 3; bottom data in FIG. 1), the crystallinity is similar to the film before irradiation (comparative sample 1; top data in FIG. 1). The peak shown was not observed. This indicates that the ZnO films of Sample 2 and Sample 3 obtained by irradiation with vacuum ultraviolet light under a low O ₂ concentration condition are amorphous.

<Example 2: Production of ZnO film (2)>
[Sample 4]
A sol prepared in the same manner as in Example 1 was spin-coated on the surface of a glass substrate to form a precursor film of a ZnO film. This precursor-coated glass substrate is placed in air at atmospheric pressure (atmospheric gas pressure of about 1 × 10 ⁵ Pa, O ₂ concentration of about 8 mol / m ³ ), and at room temperature using the xenon excimer lamp. The film was irradiated with vacuum ultraviolet light having a dominant wavelength of 172 nm for 5 hours. The distance from the outer surface of the lamp to the surface of the precursor film was 2 mm. In this way, a ZnO film (sample 4) was produced on the surface of the glass substrate.

[Sample 5]
The mass of the sol used in Example 1 is defined as 100% by mass, and a nonionic surfactant having a mass corresponding to about 0.15% by mass (product of BASF, trade name “P123”, HO (CH ₂ CH ₂ O _{) 20 (CH 2 CH (CH} 3) O) 70 (CH 2 CH 2 O) 20) H) to prepare a sol composition which contains a. A ZnO film (sample 5) was produced on the surface of the glass substrate in the same manner as in the production of sample 4 except that a sol having such a composition was used.

For each of the ZnO films of Sample 4 and Sample 3, X-ray diffraction measurement was performed in the same manner as in Example 1. The results are shown in FIG. In FIG. 3, in order to facilitate the comparison of the diffraction results between samples, the measurement results for each sample are shown with their positions shifted in the vertical direction (from top to bottom, sample 5 and sample 4). As can be seen from FIG. 3, in all of Samples 4 and 5 (that is, whether or not a surfactant is used), a peak indicating ZnO crystallinity (a peak marked with a black circle in FIG. 3) is present. Observed. This result shows that the used surfactant was appropriately decomposed by irradiating the vacuum ultraviolet light at room temperature at the O ₂ concentration.

<Example 3: Production of In ₂ O ₃ film>
A sol was prepared by dissolving in indium chloride (InCl ₃ ) ethanol. This sol was spin-coated on the surface of a silicon substrate to form a desired precursor film of In ₂ O ₃ film. This precursor-coated silicon substrate was placed in air at atmospheric pressure (atmospheric gas pressure of about 1 × 10 ⁵ Pa, O ₂ concentration of about 8 mol / m ³ ), and at room temperature using the xenon excimer lamp. The film was irradiated with vacuum ultraviolet light having a dominant wavelength of 172 nm for 5 hours. The distance from the outer surface of the lamp to the surface of the precursor film was 2 mm. In this way, an In ₂ O ₃ film (sample 6) was produced on the surface of the silicon substrate.

The results of X-ray diffraction measurement performed in the same manner as in Example 1 on the precursor film (Comparative Sample 2) of the In ₂ O ₃ film dried at a temperature of 80 ° C. or less without irradiation with vacuum ultraviolet light. 4 and FIG. 5 show the results of X-ray diffraction measurement performed on the sample 6. As is clear from the comparison between FIG. 4 and FIG. 5, in FIG. 5, a clear peak indicating the crystallinity of In ₂ O ₃ (peak with a black circle in FIG. 5) was observed. From this result, it was confirmed that a crystalline In ₂ O ₃ film (sample 6) was formed by irradiating the vacuum ultraviolet light at room temperature at the O ₂ concentration.

6 is a chart showing the results of X-ray diffraction measurement for the ZnO film obtained in Example 1. FIG. 2 is a SEM image of a ZnO film obtained in Example 1. 6 is a chart showing the results of X-ray diffraction measurement for a ZnO film obtained in Example 2. FIG. 6 is a chart showing the results of X-ray diffraction measurement of a film obtained by drying the In ₂ O ₃ precursor film produced in Example 3. 6 is a chart showing the results of X-ray diffraction measurement for the In ₂ O ₃ film obtained in Example 3. FIG. It is a schematic diagram which shows the outline of one structural example of a vacuum ultraviolet light irradiation apparatus. It is a schematic process drawing which illustrates the manufacturing method of a metal oxide film.

Explanation of symbols

3 Object to be treated (base with precursor film)
10 metal oxide film manufacturing apparatus 12 chamber 14 stage 20 vacuum ultraviolet light irradiation means 22 irradiation window 24 a vacuum ultraviolet light source 30 O ₂ concentration control means

Claims (6)

A method for producing a crystalline metal oxide film comprising:
Providing a sol containing at least one of a metal alkoxide and a salt constituting the metal oxide film ;
It The sol was applied to the substrate surface to form the gel precursor film; and,
Using a light source for irradiating vacuum ultraviolet light having a main wavelength 130～180Nm, the film from the distance from the light source to the film surface as a 3mm or less O ₂ concentration of 7 mol / m ³ in more atmosphere source Irradiating the vacuum ultraviolet light toward the film to form a crystalline metal oxide film from the film;
A method for producing a crystalline metal oxide film, comprising: As a light source for irradiating the vacuum ultraviolet light, a xenon excimer lamp, F ₂ The method according to claim 1, wherein one or more light sources selected from an excimer lamp and an argon excimer lamp are used. The method according to claim 1, wherein the crystalline metal oxide film is formed from the film in a temperature range of 80 ° C. or less. The method according to claim 1, wherein the crystalline metal oxide film is formed from the film at room temperature. The method according to any one of claims 1 to 4, wherein the crystalline metal oxide film is formed from the film in air at atmospheric pressure. The method according to any one of claims 1 to 5, wherein the metal oxide is zinc oxide or indium oxide.

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