JP2013182091A - Antireflection film and method for forming the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antireflection film and a method for forming the film that is inexpensive and has good antireflection ability.SOLUTION: An antireflection film 10 is produced by a method including steps of: forming a silicon oxide-nitride film 1 on a substrate 20 by a sputtering process using oxygen and nitrogen as a raw material gas; forming a silicon nitride film 2 on the silicon oxide-nitride film 1 by a sputtering process using nitrogen as a raw material gas; and forming a silicon oxide film 3 on the silicon nitride film 2 by a sputtering process using oxygen as a raw material gas, with all the steps carried out in the same chamber using the same silicon target. The antireflection film 10 comprises layers of, from the substrate 20 side, the silicon oxide-nitride film 1, the silicon nitride film 2 and the silicon oxide film 3, in which a ratio of oxygen to nitrogen (oxygen:nitrogen) in the silicon oxide-nitride film 1 preferably ranges from 5:95 to 20:80.

Description

  The present invention relates to an antireflection film having good adhesion and antireflection performance at low cost and a method for forming the same.

The antireflection film (also referred to as “AR film”) is provided on the surface of various optical functional products and functions to prevent reflection of light. A general antireflection film has a structure in which a high refractive index film and a low refractive index film are laminated on a transparent substrate such as glass or PET, or a structure in which these films are alternately laminated. As the low refractive index film material, SiO ₂ , MgF ₂ or the like is used, and as the high refractive index film material, ZrO ₂ , TiO ₂ or the like is used.

  In general, vapor deposition or sputtering is used for the production of the antireflection film. However, both methods have a problem that the process is complicated because a plurality of target materials are used to obtain desired characteristics or a plurality of film forming apparatuses are required.

  With respect to such a problem, Patent Document 1 proposes a method of forming an antireflection film in which a single target (evaporation source material) is used and film formation can be performed with a single sputtering apparatus.

Japanese Patent Laid-Open No. 10-160902

  Although the method proposed in Patent Document 1 is effective in terms of cost reduction, there is a problem in that the antireflection ability is not sufficient and the adhesion to the substrate is insufficient.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an antireflection film having good adhesion and antireflection performance at low cost and a method for forming the same.

  An antireflection film according to the present invention for solving the above-described problems is characterized in that a silicon oxynitride film, a silicon nitride film, and a silicon oxide film are laminated in that order from the substrate side.

  According to the present invention, the silicon oxynitride film that is a low refractive index film, the silicon nitride film that is a high refractive index film, and the silicon oxide film that is a low refractive index film are provided in this order. It can be set as the anti-reflective film excellent in. In addition, since each film constituting the antireflection film is a silicon compound, the antireflection film can be easily formed by sputtering, for example. As a result, a low-cost antireflection film can be provided. Moreover, since each film | membrane is a silicon compound, it is excellent also in the adhesiveness between each film | membrane.

  In the antireflection film according to the present invention, the ratio of oxygen and nitrogen in the silicon oxynitride film is in the range of oxygen: nitrogen = 30: 70 to 80:20.

  According to the present invention, when the ratio of oxygen and nitrogen in the silicon oxynitride film is within the above range, the silicon oxynitride film is an intermediate refractive index intermediate between the high refractive index silicon nitride film and the low refractive index silicon oxide film. Thus, good antireflection performance is achieved.

  A method for forming an antireflection film according to the present invention for solving the above-described problems includes a step of forming a silicon oxynitride film on a substrate by sputtering using oxygen and nitrogen as source gases, A step of forming a silicon nitride film by a sputtering method using nitrogen as a source gas, and a step of forming a silicon oxide film by a sputtering method using oxygen as a source gas on the silicon nitride film, each step being performed in the same chamber And using the same silicon target.

  According to this invention, since each process is performed using the same silicon target in the same chamber and switching the source gas introduced into the chamber, each film constituting the antireflection film can be easily formed. . As a result, the antireflection film can be formed at low cost. In addition, since the silicon oxynitride film, the silicon nitride film, and the silicon oxide film are a medium refractive index film, a high refractive index film, and a low refractive index film, respectively, an antireflection film having excellent antireflection performance can be formed.

  In the method for forming an antireflection film according to the present invention, the sputtering method is preferably a DC pulse sputtering method.

  According to the present invention, since each film is formed by the DC pulse sputtering method, a dense and dense film can be formed. As a result, each film is difficult to permeate water, alcohol, etc., for example, and it is possible to prevent the adhesion from being lowered by the permeation, thereby improving the adhesion between each film. Adhesion with the film can be improved.

  In the method for forming an antireflection film according to the present invention, the introduction ratio of oxygen and nitrogen, which are raw material gases for the silicon oxynitride film, is in the range of oxygen: nitrogen = 5: 95 to 30:70.

  According to the present invention, since the introduction ratio of oxygen and nitrogen, which are the raw material gases of the silicon oxynitride film, is within the above range, the silicon oxynitride film formed has a high refractive index silicon nitride film and a low refractive index. The intermediate refractive index of the silicon oxide film is good, and the antireflection performance is good.

  According to the antireflection film and the method for forming the same according to the present invention, a silicon oxynitride film that is a low refractive index film, a silicon nitride film that is a high refractive index film, and a silicon oxide film that is a low refractive index film in that order. Since it is provided, an antireflection film having excellent antireflection performance can be obtained. In addition, since each film is formed by using the same silicon target in the same chamber and switching the source gas introduced into the chamber, each film constituting the antireflection film can be easily formed. . As a result, the antireflection film can be formed at low cost.

It is a section lineblock diagram showing an example of an antireflection film concerning the present invention. It is a section lineblock diagram showing other examples of an antireflection film concerning the present invention. 3 is a graph showing the reflectance of the antireflection film obtained in Example 1.

  Hereinafter, an antireflection film and a method for forming the same according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the following description and the contents described in the drawings.

  As shown in FIGS. 1 and 2, the antireflection film 10 according to the present invention includes a silicon oxynitride film 1, a silicon nitride film 2, and a silicon oxide film 3 stacked in that order from the substrate 20 side. Such an antireflection film 10 is formed by a step of forming a silicon oxynitride film 1 on a substrate 20 by a sputtering method using oxygen and nitrogen as source gases, and a sputtering method using nitrogen as a source gas on the silicon oxynitride film 1. A step of forming a silicon nitride film 2 and a step of forming a silicon oxide film 3 on the silicon nitride film 2 by a sputtering method using oxygen as a raw material gas. It is characterized by using it.

  Hereinafter, each component of the antireflection film will be described, and a method for forming the antireflection film will also be described.

[substrate]
The board | substrate 20 is arbitrarily selected according to the object which provides the antireflection film 10, and is not specifically limited. For example, various glass substrates and various plastic substrates are used. Examples of the glass substrate include various glass substrates such as soda glass and non-alkali glass. Examples of the plastic substrate include polyethylene terephthalate film, polyethylene naphthalate film, polycarbonate film, triacetyl cellulose film, (meth) acrylonitrile film, polyethersulfone film, polyphenylenesulfide film, and the like.

  Both the glass substrate and the plastic substrate are preferably excellent in transparency. For example, the total light transmittance is preferably 85% or more. Moreover, it is preferable that heat resistance is also favorable. When a film is formed by a DC pulse sputtering method, which will be described later, since it does not reach a high temperature, even a plastic substrate with relatively poor heat resistance can be widely used. The thickness of the substrate 20 is also arbitrary depending on the type and application.

[Antireflection film]
The antireflection film 10 is provided on the substrate 20, and the silicon oxynitride film 1, the silicon nitride film 2, and the silicon oxide film 3 are laminated in that order from the substrate 20 side. The silicon oxynitride film 1 is a film represented by SiO _x N _y (x: y = 30: 70 to 80:20) and has a refractive index of about 1.60 to 1.85. The silicon nitride film 2 is a film represented by Si ₃ N ₄ or a composition close thereto, and has a refractive index of about 1.94. The silicon oxide film 3 is a film represented by SiO ₂ or a composition close thereto, and has a refractive index of about 1.49.

  The antireflection film 10 includes a silicon oxynitride film 1 as a medium refractive index film, a silicon nitride film 2 as a high refractive index film, and a silicon oxide film 3 as a low refractive index film in this order on a substrate 20. As shown in the experimental results described later, the reflectivity is less than 1% within the range of 500 nm to 760 nm, and it has excellent antireflection performance.

  The antireflection film 10 is formed by a sputtering method. Specifically, a silicon oxynitride film 1 is formed on the substrate 20 by sputtering using oxygen and nitrogen as source gases, and silicon nitride is formed on the silicon oxynitride film 1 by sputtering using nitrogen as source gas. It is formed by a forming method including a step of forming the film 2 and a step of forming the silicon oxide film 3 on the silicon nitride film 2 by a sputtering method using oxygen as a source gas. Since each film constituting the antireflection film 10 is a silicon compound, the same chamber is used if the same silicon target is used and the gas species for forming each film are replaced in the order of oxygen and nitrogen → nitrogen → oxygen. Each film can be formed inside. Therefore, there is an advantage that there is no complexity such as transfer to a different film forming chamber for each film.

  Of each film, the silicon oxynitride film 1 formed by introducing oxygen and nitrogen can be formed with an arbitrary composition by changing the introduction ratio of oxygen and nitrogen. For example, the refractive index of the formed silicon oxynitride film 1 can be set to about 1.60 to 1.85 by introducing it into the chamber within the range of oxygen: nitrogen = 5: 95 to 20:80. it can. This refractive index region is intermediate between the silicon nitride film 2 as a high refractive index film and the silicon oxide film 3 as a low refractive index film, and can provide good antireflection performance.

  The thickness d of each layer is derived from the relationship of nd = λ / 4. Here, n is a refractive index and λ is a wavelength (633 nm). Each film is formed with the value obtained by the calculation formula as a target. Specifically, the silicon oxynitride film 1 having a refractive index of about 1.78 is formed with a thickness of about 89 nm, and the silicon nitride film 2 with a refractive index of about 1.94 is formed with a thickness of about 82 nm. The silicon oxide film 3 having a refractive index of about 1.49 is preferably formed with a thickness of about 106 nm.

  Thus, it can be said that the film configuration of the three-layer structure of the antireflection film 10 is a form in which the antireflection film 10 can be easily formed. As a result, a low-cost antireflection film 10 can be provided.

  As a sputtering method. Various sputtering methods such as a high-frequency sputtering method, a magnetron sputtering method, a DC sputtering method, and a DC pulse sputtering method can be applied. Among these, it is preferable to form a film by a DC pulse sputtering method. Film formation by the DC pulse sputtering method enables high-speed film formation with transition region control not found in other types of sputtering methods, and a dense and dense film can be formed. As a result, each film is difficult to permeate water, alcohol, etc., for example, and it is possible to prevent the adhesion from being lowered by the permeation and to improve the adhesion between the films 1, 2, and 3. There is an effect. In addition, the adhesion between the substrate 20 and the silicon oxynitride film 1 can be improved.

  Note that an antifouling film, a hard coat film, or the like may be provided on the antireflection film 10 as necessary within a range not inhibiting the antireflection ability.

  As described above, according to the antireflection film 10 according to the present invention, the silicon oxynitride film 1, the silicon nitride film 2, and the silicon oxide film 3 are a medium refractive index film, a high refractive index film, and a low refractive index film, respectively. Therefore, the antireflection film is excellent in antireflection performance. Each film is formed by using the same silicon target in the same chamber, and by switching the source gas introduced into the chamber, so that each film constituting the antireflection film 10 can be easily formed. can do. As a result, the antireflection film 10 can be formed at low cost. The antireflection film 10 thus obtained can be applied to various optical lenses, electronic display panels, building material glass, automobile glass and the like.

  EXAMPLES The present invention will be described more specifically with reference to examples. However, the present invention is not limited to the description of the following examples unless it exceeds the gist.

[Example 1]
As a sputtering apparatus, a DC pulse sputtering apparatus (manufactured by Fraunhofer, model: DRM400) provided with a DC pulse mechanism in a plasma power source was used. A Si target was used, argon gas was used as a sputtering gas, oxygen gas and nitrogen gas were introduced at a ratio of 10:90 as source gases, and a SiOxNy film was formed on a glass substrate with a thickness of 89 nm. Next, the introduction of the gas was stopped, the gas in the chamber was evacuated, and argon gas and nitrogen gas were introduced again to form a Si ₃ N ₄ film on the SiOxNy film with a thickness of 82 nm. Next, the introduction of the gas was stopped, the gas in the chamber was evacuated, and argon gas and oxygen gas were introduced again to form a SiO ₂ film on the Si ₃ N ₄ film with a thickness of 106 nm.

The refractive index of the obtained film was about 1.78 for the SiOxNy film, about 1.95 for the Si ₃ N ₄ film, and about 1.48 for the SiO ₂ film. The DC pulse sputtering method is advantageous in that high-speed film formation can be performed with transition region control, and here, the film formation speed is 4 nm / second. The mass ratio of oxygen and nitrogen constituting the SiOxNy film was oxygen: nitrogen = 38: 62. The refractive index is measured with a spectrophotometer (manufactured by JASCO Corporation, model: V-670), and the mass ratio is a wavelength dispersion type fluorescent X-ray element analyzer (manufactured by Rigaku Corporation, model: ZSX Primus II). The reflectance was measured with a spectrophotometer (manufactured by JASCO Corporation, model: V-670).

FIG. 3 is a graph of the reflectance of the obtained antireflection film. In the wavelength range of 500 nm to 760 nm, the reflectance was less than 1%, and excellent antireflection performance was exhibited. In particular, at 633 nm, the reflectance was 0.03%. In addition, the SiOxNy film, the Si ₃ N ₄ film, and the SiO ₂ film are all excellent in durability and can withstand long-term use. Moreover, even after being immersed in water and alcohol, the adhesiveness of each film was excellent. The reason is that each film is formed by a DC pulse sputtering method as a high-density film that does not easily allow moisture to penetrate.

[Example 2]
In Example 1, oxygen gas and nitrogen gas were introduced as source gases in a ratio of 20:80, respectively, and a SiOxNy film was formed on a glass substrate with a thickness of 89 nm as a target. Thus, an antireflection film of Example 2 was obtained. The refractive index of the obtained film was about 1.59 for the SiOxNy film, about 1.95 for the Si ₃ N ₄ film, and about 1.48 for the SiO ₂ film. The reflectance at 633 nm was 0.6%. The mass ratio of oxygen and nitrogen constituting the SiOxNy film was oxygen: nitrogen = 72: 28.

[Comparative Example 1]
In Example 1, an antireflection film of Comparative Example 1 was obtained in the same manner as in Example 1 except that a Si ₃ N ₄ film and a SiO ₂ film were directly provided without providing a SiOxNy film on the glass substrate. . The refractive indexes of the obtained Si ₃ N ₄ film and SiO ₂ film were the same as in Example 1. The reflectance at 633 nm was 1.1%.

[Comparative Example 2]
In Example 1, an antireflection film of Comparative Example 2 was obtained in the same manner as in Example 1 except that a Si ₃ N ₄ film, a SiOxNy film, and a SiO ₂ film were provided on the glass substrate in this order. The refractive index of each film obtained was the same as in Example 1. The reflectance at 633 nm was 11%.

[Comparative Example 3]
In Example 1, an antireflection film of Comparative Example 3 was obtained in the same manner as in Example 1 except that a SiO ₂ film, a SiOxNy film, and a Si ₃ N ₄ film were provided on the glass substrate in this order. The refractive index of each film obtained was the same as in Example 1. The reflectance at 633 nm was 12%.

DESCRIPTION OF SYMBOLS 1 Silicon oxynitride film 2 Silicon nitride film 3 Silicon oxide film 10 Antireflection film 20 Substrate

Claims (5)

  An antireflection film, wherein a silicon oxynitride film, a silicon nitride film, and a silicon oxide film are laminated in this order from the substrate side.   The antireflection film according to claim 1, wherein a ratio of oxygen and nitrogen in the silicon oxynitride film is in a range of oxygen: nitrogen = 30: 70 to 80:20.   Forming a silicon oxynitride film on the substrate by a sputtering method using oxygen and nitrogen as a source gas; forming a silicon nitride film on the silicon oxynitride film by a sputtering method using nitrogen as a source gas; and Forming a silicon oxide film on the silicon nitride film by sputtering using oxygen as a source gas, and performing each process using the same silicon target in the same chamber. Method.   The method for forming an antireflection film according to claim 3, wherein the sputtering method is a DC pulse sputtering method. 5. The method for forming an antireflection film according to claim 3, wherein an introduction ratio of oxygen and nitrogen, which are source gases of the silicon oxynitride film, is in a range of oxygen: nitrogen = 5: 95 to 30:70.

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