TW201700996A - Anti-reflection structure and method of forming the same - Google Patents

Abstract

Provided is an anti-reflection structure including a substrate and a gradient film. The gradient film has a metal-doped fluorinated silicon oxide and is disposed on the substrate. The atomic ratio of silicon to metal in the gradient film is gradually reduced away from the surface of the substrate. The atomic ratio of silicon to metal in the gradient film is greater than about 1:1 and less than about 10:1. A method of forming an anti-reflection structure is also provided.

Description

Anti-reflection structure and manufacturing method thereof

The present invention relates to a semiconductor structure and a method of fabricating the same, and more particularly to an anti-reflective structure and a method of fabricating the same.

The antireflective or anti-reflection (AR) structure is a structure applied to the surface of various optical devices, and its purpose is to reduce reflection to improve light utilization efficiency. The aforementioned optical device covers a wide range, and an anti-reflection structure may be required from an optical lens such as an eyeglass lens or a telescope lens to a photoelectric conversion device such as a solar cell.

Reducing the reflectivity of glass has always been an important issue in research and development. On the solar cell module glass, if the reflectivity is reduced by 3%, the module output power can be directly increased by nearly 3%. On the display screen, if the reflectivity of the cover glass can be reduced, the quality of the visual viewing can be directly improved. However, the method of reducing the reflectance is nothing more than plating a low refractive index film layer on the glass surface or forming a low equivalent refractive index thin layer using a nanostructure. In addition, the anti-reflective structure is in the outermost layer in all product applications, so the hardness, strength and chemical stability of the structure are also very important, the conventional fluorine The ruthenium oxide film can greatly improve its performance through the metal doping and regulation of the present invention.

In view of this, the present invention provides an anti-reflection structure and a method for fabricating the same, which can produce a graded film having a low refractive index, a high hardness, and a high chemical stability.

The present invention provides an anti-reflection structure comprising a substrate and a graded film. The graded film has metal doped bismuth oxyfluoride and is disposed on the substrate. Gradient film: The atomic ratio of the metal gradually decreases from the surface of the grading film to the substrate. Gradient film: The atomic ratio of the metal is greater than about 1:1 to less than about 10:1.

In an embodiment of the invention, the gradation film has an atomic ratio of metal of from about 1.1:1 to about 8:1.

In an embodiment of the invention, the grading film is in an amorphous state.

In an embodiment of the invention, the graded film has a porosity of less than about 20%.

In an embodiment of the invention, the graded film has a pencil hardness of about 3H or higher.

In an embodiment of the invention, the grading film has a thickness in the range of about 20 nm to 300 nm.

In an embodiment of the invention, the anti-reflective structure has an equivalent refractive index of about 1.45 or less at a wavelength of 633 nm.

In an embodiment of the invention, the atomic ratio of the fluorine:metal of the grading film gradually decreases from the surface of the grading film to the substrate.

In an embodiment of the invention, the material of the substrate comprises glass.

In an embodiment of the invention, the metal comprises a Group IA metal, IIA Group metal, Group IIIA metal or a combination thereof.

The present invention further provides a method of fabricating an anti-reflective structure. A first solution of a metal salt, hydrofluoric acid, and fluoride ion stabilizer is formed. A second solution containing the casing is formed. The first solution is mixed with the second solution and applied to the substrate, and after drying, a layered film is formed. The layered film is annealed to form a graded film having metal doped bismuth oxyfluoride.

In an embodiment of the invention, the gradation of the grading film: the atomic ratio of the metal gradually decreases from the surface of the grading film to the substrate, and the atomic ratio of the 矽:metal of the grading film is greater than about 1:1 to less than about 10: 1.

In an embodiment of the invention, the metal concentration of the grading film gradually decreases from the surface of the grading film to the substrate, and the atomic ratio of 矽: metal of the grading film is in a range of about 1.1:1 to 8:1.

In an embodiment of the invention, the metal salt comprises a salt compound of a Group IA metal, a Group IIA metal, a Group IIIA metal, or a combination thereof.

In an embodiment of the invention, the fluoride ion stabilizer comprises tetrafluoride, hexafluoride or a salt which can form a tetrafluoride or a hexafluoride or an acid.

In an embodiment of the invention, the organic ruthenium has a structure of Si(OR) ₄ and R includes a linear or branched alkyl group having 1 to 4 carbon atoms.

In an embodiment of the invention, the annealing treatment temperature is in the range of 50 ° C to 400 ° C.

In an embodiment of the invention, the grading film is in an amorphous state.

In an embodiment of the invention, the graded film has a porosity of less than about 20%.

In an embodiment of the invention, the fluorine-containing metal atom of the grading film It gradually decreases toward the substrate from the surface of the grading film.

Based on the above, the present invention achieves a graded refractive index structure by a simple one-time coating, and forms an amorphous film having a hardness of 3H or more, a refractive index of 1.45 or less, and a porosity of 20% or less.

The above described features and advantages of the invention will be apparent from the following description.

10‧‧‧Substrate

20‧‧‧Under film

30‧‧‧Upper film

40‧‧‧layer film

50‧‧‧grading film

50-1, 50-2, 50-3, 50-4, 50-5, 50-6‧‧‧ sub-layer

100~108‧‧‧Steps

FIG. 1 is a flow chart of a method of fabricating an anti-reflective structure according to an embodiment of the invention.

2A through 2B are schematic cross-sectional views showing a method of fabricating an anti-reflective structure in accordance with an embodiment of the present invention.

Fig. 3 is a graph showing the hardness change of the antireflection film mixed solution after spraying for a film after the different standing time of Example 1 of the present invention and Comparative Example 1.

4A is a XPS depth profile of an anti-reflection structure of Example 1 of the present invention.

Fig. 4B is a graph showing changes in the atomic ratio of the depth vs. Si/Mg of the antireflection structure of Example 1 of the present invention.

Fig. 4C is a graph showing changes in the atomic ratio of the depth vs. F/Mg of the antireflection structure of Example 1 of the present invention.

Figure 5 is a surface AFM image of the anti-reflection structure of Example 1 of the present invention.

Figure 6 is an XRD diffraction pattern of the antireflection structure of Example 1 of the present invention.

Figure 7 is a FTIR spectrum of the antireflection structure of Example 1 of the present invention.

Figure 8 is a cross-sectional TEM image of the anti-reflection structure of Example 1 of the present invention.

Fig. 9 is a bar graph showing changes in transmittance of a bismuth boron glass substrate having different enthalpy: magnesium atom ratio films before and after weather resistance test.

FIG. 1 is a flow chart of a method of fabricating an anti-reflective structure according to an embodiment of the invention. 2A through 2B are schematic cross-sectional views showing a method of fabricating an anti-reflective structure in accordance with an embodiment of the present invention.

The invention controls the bonding characteristics of the organic germanium and the metal salt to form a low refractive index and high hardness material with a compositionally graded distribution.

Referring to FIG. 1, in step 100, a first solution containing a metal salt, hydrofluoric acid, and a fluoride ion stabilizer is formed. Specifically, a metal salt is dissolved in a solvent, and hydrofluoric acid is added to form a solution containing a bond group of FM-OH and M(OH) ₂ , wherein M represents a metal ion. The M includes a Group IA metal, a Group IIA metal, a Group IIIA metal, or a combination thereof. In an embodiment, the M comprises Li, Na, K, Be, Mg, Ca, Al, or a combination thereof. Metal salts include salt compounds of Group IA metals, Group IIA metals, Group IIIA metals, or combinations thereof. In one embodiment, the metal salt is, for example, lithium chloride, lithium acetate, lithium nitrate, magnesium chloride, magnesium acetate, magnesium nitrate, calcium chloride, calcium acetate, calcium nitrate, aluminum chloride, aluminum acetate or a combination thereof. The solvent includes water, methanol, ethanol, isopropanol or a combination thereof. Next, a fluoride ion stabilizer is added to the solution containing the FM-OH and M(OH) ₂ bonding groups to form a first solution. The fluoride ion stabilizer includes tetrafluoride, hexafluoride or a salt which can form a tetrafluoride or a hexafluoride or an acid.

In step 102, a second solution containing the casing is formed. The structure of the organic ruthenium is Si(OR) ₄ , and R includes a linear or branched alkyl group having a carbon number of 1 to 4. In one embodiment, the organic hydrazine is, for example, tetraethyl orthosilicate (TEOS; Si(OC ₂ H ₅ ) ₄ ). Specifically, Si(OR) _{4 is} dissolved in a solvent, and the pH is adjusted to partially hydrolyze to form Si(OR) _4-n (OH) _n (where n is a positive integer) to form a second solution. Contains Si(OR) ₄ and Si(OR) _4-n (OH) _n groups. The solvent includes water, methanol, ethanol, isopropanol or a combination thereof.

In step 104, the first solution is mixed with the second solution and applied to the substrate, and after drying, a layered film is formed. Specifically, the first solution is mixed with the second solution, thereby having a fluoride ion stabilizer, thereby effectively preventing free fluoride ions from accelerating Si(OR) ₄ hydrolysis and forming Si(OR) _4-x (F) _x (wherein x is a positive integer). In this way, the solution containing the FM-OH bond can react with a portion of Si(OR) _4-n (OH) _n to form Si(OR) _4-m (OMF) _m (where m is a positive integer), while A portion of Si(OR) _4-n (OH) _n and Si(OR) ₄ remain in solution. Therefore, after mixing the first solution with the second solution, M(OH) ₂ , Si(OR) _4-n (OH) _n , Si(OR) ₄ , Si(OR) _4-m (OMF) _{m will be formed.} Four groups of main components, and during the drying process, OH-rich M(OH) ₂ and Si(OR) _4-n (OH) _n can be more affinity with glass substrates, Si(OR) ₄ , Si ( OR) _4-m (OMF) _m is pushed away from the glass substrate due to the inability to bond with the substrate, resulting in a tendency to stratify the composition, so that the film is gradually dried to form a film having a gradually distributed composition.

As shown in FIG. 2A, the layered film 40 is disposed on the substrate 10. The layered film 40 has an underlayer film 20 and an upper layer film 30. In the film formation process, the underlayer film 20 is mostly composed of M(OH) ₂ and Si(OR) _4-n (OH) _n , and the upper film 30 is mostly composed of Si(OR) ₄ and Si(OR) _{4 .} The composition of _-m (OMF) _m also forms a tendency for the upper layer to have a higher concentration of germanium atoms and the lower layer to have a higher concentration of metal atoms. The material of the substrate 10 includes glass such as magnesium-free glass, magnesium-containing glass or borosilicate glass.

In step 106, the layered film is annealed to form a graded film having metal doped lanthanum oxyfluoride. The annealing treatment temperature is in the range of about 50 ° C to 400 ° C, 100 ° C to 300 ° C or 150 ° C to 250 ° C. Specifically, during the annealing process, the fluoride ion stabilizer continuously releases fluoride ions and is removed by cleavage, so that the remaining film layer has a metal-doped lanthanum oxyfluoride (represented by SiOF:M), wherein lanthanum: a metal atom The ratio is a gradient distribution.

As shown in FIG. 2B, the atomic ratio of germanium to metal of the graded film 50 is a gradual distribution. In one embodiment, the graded film 50 has, for example, but is not limited to, six sub-layers 50-1, 50-2, 50-3, 50-4, 50- from the surface of the graded film 50 from top to bottom. 5, 50-6. The enthalpy of the grading film 50: the atomic ratio of the metal gradually decreases from the surface of the grading film 50 toward the substrate, that is, the six sub-layers 50-1, 50-2, 50-3, 50-4, 50-5, 50- The enthalpy of 6: the atom of the metal gradually decreases from the substrate 10. Further, the thickness of the graded film 50 is in the range of about 20 nm to 300 nm.

The metal concentration is in the range of about 5 at% to 50 at%, based on the total atomic weight of the grading film 50, and the fluorine concentration thereof is in the range of 1 at% to 50 at%. It is particularly noted that the gradation film 50 may have a lower atomic ratio of metal to greater than about 1:1 to less than about 10:1 or fall within a range of from about 1.1:1 to about 8:1. The refractive index and at the same time have better chemical stability. In one embodiment, the gradation film 50 has a chemical stability of 矽: metal atomic ratio in the range of from about 1:1 to about 10:1. When the atomic ratio of the ruthenium:metal of the gradation film 50 exceeds or falls below this range, the chemical stability of the gradation film 50 is lowered.

In Fig. 2B, the portion with a high mesh density represents a higher enthalpy: the atomic ratio of the metal, which means that the region has more bismuth components, so that the surface has a higher hardness. And since the surface has a relatively high fluorine concentration at the same time, the reflectance can be effectively reduced by this structure. In one embodiment, the antireflective structure of the present invention has an equivalent refractive index of about 1.45 or less (e.g., about 1.40 or less) at a wavelength of 633 nm. If it is plated on a glass substrate, the glass can be worn. The penetration rate is increased by about 2% or higher.

Further, the gradation film 50 is in an amorphous state, and its main structure is still amorphous yttrium oxide. Therefore, the gradation film 50 of the present invention is not a gradation film of a crystalline metal fluoride free. The grading film 50 of the present invention is a film layer having no porosity or low porosity. In one embodiment, the graded film 50 has a porosity of about 20% or less.

The grading film 50 of the present invention has an amorphous form and has substantially no pores, and the surface is a component having a high atomic ratio of lanthanum metal, and thus is compared with a conventional porous or nanoparticle mixed film layer. The graded film 50 of the present invention has excellent film hardness. In one embodiment, the graded film has a pencil hardness of about 3H or higher. In another embodiment, the graded film has a pencil hardness of about 6H or higher.

Further, the gradation film 50 is a highly flat film and has a good adhesion to the substrate 10. In an embodiment, the graded film 50 has a roughness Ra of less than 1 nm.

Based on the above, the present invention is a metal salt solution formed by the addition of a special tetrafluoride or hexafluoride under the requirement of high hardness, and is mixed with an organic cerium solution due to the action of tetrafluoride or hexafluoride. The activity of the fluoride ion is lowered, and the Si-F bond generated by the condensation of the organic hydrazine by the fluorine ion in the mixed solution is suppressed and the generation of the Si-O-Si bond is accelerated, and the formation of the Si-OM bond is promoted. This will avoid metal agglomeration of metal fluoride particles, thus increasing the strength of the film.

Hereinafter, examples and comparative examples will be enumerated to verify the efficacy of the present invention.

Example 1

Referring to the flow of FIG. 1, a first solution containing magnesium acetate tetrahydrate (as a metal salt component), hydrofluoric acid, and boric acid (as a component of a fluoride ion stabilizer) is formed; and TEOS (as an organic bismuth component) is formed. a second solution; mixing the first solution with the second solution and coating on the bismuth boron glass, drying to form a layered film; and annealing the layered film to form a SiOF:Mg gradient film on the bismuth boron glass, wherein The overall gradient film: the atomic ratio of magnesium is 1.67:1.

Comparative example 1

Same as the procedure of Example 1, but Comparative Example 1 did not add a fluoride ion stabilizer.

Fig. 3 is a graph showing changes in pencil hardness with time in the antireflection structure of Example 1 of the present invention and Comparative Example 1. Figure 3 is a comparison of the hardness of the film with or without the addition of a fluoride ion stabilizer. It can be observed that the hardness of the film of Example 1 in which the fluoride ion stabilizer was added was maintained stable after the first solution was mixed with the second solution. On the contrary, the film hardness of Comparative Example 1 without the addition of the fluoride ion stabilizer rapidly decreased drastically. In other words, the fluoride ion stabilizer can greatly enhance the mass productivity of the present technology.

Fig. 4A is a longitudinal distribution diagram of XPS elements of the antireflection structure of Example 1 of the present invention. The tendency of the concentration of F, Si, and Mg from the surface of the film to the interface close to the film and the glass substrate can be observed. As shown in FIG. 4A, it can be seen that the concentrations of Si and F gradually decrease as they approach the interface, and the concentration of Mg gradually increases as it approaches the interface. Due to the high concentration of Si on the surface, the hardness and chemical resistance of the film can be greatly improved. In addition, the higher the F concentration on the surface, the lower the refractive index of the surface film component, so that the refractive index gradually decreases from the surface to the interface. The trend, such a gradient index trend will effectively improve the anti-reflective effect of the film.

4B is a depth vs. Si/Mg of the anti-reflection structure of Example 1 of the present invention. Trend graph of the atomic ratio. The tendency of the atomic ratio of Si/Mg from the surface of the film to the interface between the film and the glass substrate can be observed. As shown in FIG. 4B, it can be seen that the atomic ratio of Si/Mg gradually decreases as it approaches the interface, wherein the atomic ratio of Si/Mg is reduced from 1.78 to 1.49.

Fig. 4C is a graph showing changes in the atomic ratio of the depth vs. F/Mg of the antireflection structure of Example 1 of the present invention. The tendency of the atomic ratio of F/Mg from the surface of the film to the interface between the film and the glass substrate can be observed. As shown in Fig. 4C, it can be seen that the atomic ratio of F/Mg gradually decreases as it approaches the interface, wherein the atomic ratio of F/Mg decreases from 1.65 to 1.39.

Figure 5 is a surface AFM image of the anti-reflection structure of Example 1 of the present invention. It is calculated that the Rq of the film is 0.597 nm and the Ra is 0.461 nm, indicating that the SiOF:Mg gradient film is a highly flat film, which has durability advantages in PV module applications.

Figure 6 is an XRD diffraction pattern of the antireflection structure of Example 1 of the present invention. Referring to FIG. 6, no MgF ₂ peak is shown, indicating that the SiOF:Mg gradient film is an amorphous graded film having no MgF ₂ (MgF ₂ free) crystal structure.

Figure 7 is a FTIR spectrum of the antireflection structure of Example 1 of the present invention. The display film layer has Si-O-Mg and Si-F bond.

Figure 8 is a cross-sectional TEM image of the anti-reflection structure of Example 1 of the present invention. It can be seen that the graded film of Example 1 is amorphous and has a very low porosity with a porosity of less than about 20%, thus having a better strength than conventional techniques. In addition, it can be seen that the interface of the SiOF:Mg gradation film and the glass substrate is free from defects.

Table 1 compares the equivalent refractive index and transmittance of a boron neodymium glass substrate with/without a SiOF:Mg graded film. Compared with the bismuth boron glass of Comparative Example 2, the antireflection structure of Example 1 having a SiOF:Mg graded film was averaged at a wavelength of 400 nm to 700 nm. It can increase the transmittance by 3.25% and has an equivalent refractive index of 1.39 at 633 nm.

Table 2 shows the changes in the transmittance of the bismuth boron glass substrate with different films before and after the weather resistance test. The weatherability test is a comparison of the change in the transmittance before and after soaking for one hour in a 5 wt% NaCl aqueous solution at 50 °C. It can be seen that the MgF ₂ film and the SiOF film of Comparative Examples 3 to 4 are destroyed by the 5 wt% NaCl aqueous solution, resulting in a sharp drop in the transmittance. On the contrary, the SiOF:Mg gradation film of the present invention has good weather resistance, so that the transmittance does not change significantly.

Fig. 9 is a bar graph showing changes in transmittance of a bismuth boron glass substrate having films having different yttrium/magnesium atom ratios before and after weather resistance test.

Approach to change the film Si / Mg atomic ratio of SiOF: Mg thin film on a silicon-boron glass which is measured after the film transmittance is T _before. Next, the glass plated with the SiOF:Mg film was immersed in a 5 wt% NaCl aqueous solution at 50 ° C, soaked for one hour, then taken out of the glass for cleaning and blow dried, and the transmittance was measured as T _after . Further, the calculation of T _before -T _after is the amount of decrease in the penetration rate of the glass, and the change in the amount of decrease in the bar graph is as shown in FIG.

As a result of the transmission, it was observed that when the Si/Mg atomic ratio was lowered to 1 or less, the penetration rate of the 5 wt% NaCl aqueous solution was greatly reduced to more than 0.5% after immersing for 5 hours. In the anti-reflective glass application of the solar cell module, generally, if the anti-reflective film can be improved by 2%, it is a good performance, so the actual value of the 0.5% transmittance is greatly affected. However, if the anti-reflective glass of the solar cell module improves its NaCl-resistant aqueous solution, it can particularly increase its performance in coastal power generation equipment because the environment near the coast usually has a high NaCl concentration.

When the Si/Mg atomic ratio exceeds 1, the film's ability to resist NaCl solution is significantly improved, so the penetration rate before and after the immersion does not change. However, when the Si/Mg atomic ratio exceeds 12, the ability of the film to resist NaCl aqueous solution begins to decrease, which is equivalent to that of Mg-free SiOF. This result shows that the Si/Mg atomic ratio can effectively improve the chemical resistance of the film at a specific ratio (greater than 1:1 and less than 10:1), and has an unexpected effect.

Example 2

Referring to the flow of FIG. 1, a first solution containing magnesium acetate tetrahydrate, lithium chloride, hydrofluoric acid, and boric acid is formed; a second solution containing TEOS is formed; and the first solution is mixed with the second solution and coated on the boron-boron glass. Forming a layered film after drying; and annealing the layered film at 200 ° C for one hour to form a SiOF:MgLi graded film On the bismuth boron glass, the 渐变 of the graded film: the atomic ratio of magnesium:lithium is 4:2:1. The film has a hardness of more than 6H and has an anti-reflective structure of a SiOF:MgLi graded film, which can increase the transmittance by an average of 2% at a wavelength of 400 nm to 700 nm.

Example 3

Referring to the flow of FIG. 1, a first solution containing calcium nitrate tetrahydrate, hydrofluoric acid and boric acid is formed; a second solution containing TEOS is formed; the first solution is mixed with the second solution and coated on the boron borosilicate glass, and dried. A layered film was formed; and the layered film was annealed at 200 ° C for one hour to form a SiOF:Ca graded film on the bismuth boron glass, wherein the grading film had an atomic ratio of calcium of 4:1. The film has a hardness of more than 6H and has an anti-reflective structure of a SiOF:Ca grading film, which can increase the transmittance by an average of 2.5% at a wavelength of 400 nm to 700 nm.

In summary, the present invention achieves a graded refractive index structure by simple one-time coating to form a film having high hardness, high penetration, and high flatness. This structure will increase the average transmittance of the glass substrate at 400-700 nm light wavelength by more than 2%, and the film hardness exceeds the pencil hardness of 3H. Under certain conditions, the film hardness can exceed the pencil hardness of 6H. Such characteristics can be widely applied to PV. , panels, mobile phones and other related industries.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

10‧‧‧Substrate

50‧‧‧grading film

50-1, 50-2, 50-3, 50-4, 50-5, 50-6‧‧‧ sub-layer

Claims (20)

An anti-reflection structure comprising: a substrate; and a graded film having a metal-doped yttrium oxyfluoride and disposed on the substrate, wherein the grading film has a metal atomic ratio from a surface of the grading film The substrate is gradually lowered, and the atomic ratio of the metal of the graded film is from 1:1 to less than 10:1. The antireflection structure according to claim 1, wherein the gradation film has an atomic ratio of metal of from 1.1:1 to 8:1. The antireflection structure of claim 1, wherein the graded film is amorphous. The antireflection structure of claim 1, wherein the graded film has a porosity of less than 20%. The antireflection structure of claim 1, wherein the graded film has a pencil hardness of 3H or higher. The antireflection structure of claim 1, wherein the graded film has a thickness in the range of 20 nm to 300 nm. The antireflection structure of claim 1, wherein the antireflection structure has an equivalent refractive index of 1.45 or less at a wavelength of 633 nm. The anti-reflection structure of claim 1, wherein the atomic ratio of fluorine:metal of the graded film gradually decreases from the surface of the graded film toward the substrate. The anti-reflection structure of claim 1, wherein the material of the substrate comprises glass. The anti-reflection structure of claim 1, wherein the gold The genus includes a Group IA metal, a Group IIA metal, a Group IIIA metal, or a combination thereof. A method for producing an anti-reflective structure, comprising: forming a first solution containing a metal salt, a hydrofluoric acid, and a fluoride ion stabilizer; forming a second solution containing the organic mash; and the first solution and the second solution Mixing and coating on a substrate, drying to form a layered film; and annealing the layered film to form a graded film having metal doped bismuth oxyfluoride. The method for fabricating an anti-reflective structure according to claim 11, wherein the gradation of the grading film: the atomic ratio of the metal gradually decreases from the surface of the grading film toward the substrate, and wherein the grading film矽: The atomic ratio of the metal is greater than 1:1 to less than 10:1. The method for fabricating an anti-reflective structure according to claim 11, wherein the gradation of the grading film: the atomic ratio of the metal gradually decreases from the surface of the grading film toward the substrate, and wherein the grading film矽: The atomic ratio of the metal is in the range of 1.1:1 to 8:1. The method for producing an antireflection structure according to claim 11, wherein the metal salt comprises a salt compound of a Group IA metal, a Group IIA metal, a Group IIIA metal or a combination thereof. The method for producing an antireflection structure according to claim 11, wherein the fluoride ion stabilizer comprises tetrafluoride, hexafluoride or a salt which can form a tetrafluoride or a hexafluoride or an acid. The method for producing an antireflection structure according to claim 11, wherein the organic germanium structure is Si(OR) ₄ , and R includes a linear or branched alkyl group having a carbon number of 1 to 4. The method of producing an antireflection structure according to claim 11, wherein the annealing treatment temperature is in the range of 50 ° C to 400 ° C. The method for producing an anti-reflection structure according to claim 11, wherein the graded film is in an amorphous state. The method for producing an anti-reflection structure according to claim 11, wherein the graded film has a porosity of less than 20%. The method for producing an anti-reflection structure according to claim 11, wherein the atomic ratio of the fluorine:metal of the graded film gradually decreases from the surface of the graded film to the substrate.