JP2003270402A - Method for manufacturing antireflection film having favorable adhesiveness - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an antireflection film by a new sputtering method. <P>SOLUTION: When an antireflection film is manufactured on the surface of a plastic base material by sputtering, a metal film is preliminarily introduced as an intermediate layer onto the surface of the base material. The metal film is preferably introduced by sputtering. The metal to form the metal film is preferably one or more kinds selected from a group consisting of titanium, silicon, aluminum, zinc, zirconium, tantalum and magnesium. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a technique for producing an antireflection film on a surface of a plastic substrate by using a sputtering method.

[0002]

2. Description of the Related Art Anti-reflection coatings are widely used in the fields of optics and electro-optics, especially for coating lenses for glasses, lenses for cameras, CRT panels, and recently display devices for mobile phones and PDAs. Used frequently.

Conventionally, as a method for producing an antireflection film, there are known a method of forming a film on a film and adhering it to a base material, and a method of forming a film directly on the base material. A vacuum deposition method is mainly used as a method for directly forming a film on a substrate. However, with the former method, the film forming process becomes complicated, and a decrease in yield is unavoidable. On the other hand, with the latter method, it is difficult to increase the scale of the vapor deposition apparatus, and there are problems that the processing area is limited and the frequency of maintenance is high in a relatively small-scale apparatus that is commonly used. In addition, since the defective product generation rate is high when the actual production is performed, and the manufacturing cost is increased, a film forming method for mass production with a low defective product generation rate is desired.

By the way, a sputtering method is drawing attention as a film forming method for solving these problems. It is considered to be most suitable for industrialization because it has the advantages that the device can be made relatively large in size and that the frequency of maintenance is reduced. However, in the case of the sputtering method, since the radiant heat generated during film formation is large,
The disadvantage arises that from a thermal point of view plastic substrates suitable for use are limited. Therefore, if the sputtering method is applied to a wide range of plastic base materials, the film formation temperature must be lowered, and then the temperature of the substrate during film formation is particularly high, as shown in Thornton's thin film microstructure model. When it is low, a film having a low density is formed, and the adhesion to the substrate becomes worse than usual. In addition, when a metal oxide film is formed on a plastic substrate, the adhesion becomes particularly poor, and as a result, the transmittance is remarkably reduced and the properties as an antireflection film are not exhibited.

[0005]

As means for solving the above problems, a method of roughening the surface of a substrate before film formation and a method of applying a hard coat treatment (Japanese Patent Laid-Open No. 7-
318703, JP-A-6-337302, JP-A-10-
123301), etc., but in the former case the incident light is considered to be reflected at the interface with the base material by roughening the surface of the base material, which is not desirable when used as an optical member, and in the latter case there are many treatment steps. Considering the above, it seems that a simpler method is desirable.

In view of the above situation, the present invention can be applied to a wide range of resin substrates without complicated processes such as hard coat treatment, and is particularly suitable for optical members and has good adhesion by a sputtering method. An object of the present invention is to provide a method for producing a simple antireflection film.

[0007]

Means for Solving the Problems As a result of repeated studies to solve the above-mentioned problems, the present inventors have found a method for producing an antireflection film on a plastic substrate by the following novel sputtering method and found the present invention. It came to completion.

That is, the present invention is characterized in that, when an antireflection film is formed on the surface of a plastic substrate by a sputtering method, a metal film is previously formed as an intermediate layer on the surface of the substrate to form an antireflection film. The present invention provides a method for producing.

When the antireflection film is formed on the plastic substrate, the metal film as an intermediate layer which is previously introduced between the plastic substrate and the antireflection film may be formed by any method, but the sputtering method is preferable. It is desirable to form a film by As a result, all the steps for producing the antireflection film can be performed by the sputtering method, and the steps can be simplified. Note that the sputtering method here is a means for depositing metal atoms scattered in the gas from the metal surface by vaporization or collision by heating or ion bombarding the metal in a low-pressure inert gas on the surface of the base material. Is generally defined as.

The constituent element of the metal film to be introduced and formed is not particularly limited, but one or more selected from the group consisting of titanium, silicon, aluminum, zinc, zirconium, tantalum and magnesium is preferably used.
More preferably titanium or silicon is particularly desirable.

The thickness (d) of the metal film formed by introduction is not particularly limited, but preferably 10 nm ≦ d ≦ 30.
It can be preferably used in the range of nm.

The plastic substrate used in the present invention is
A wide range of synthetic resins can be used regardless of whether they are thermoplastic or thermosetting. For example, (meth) acrylic resin, polycarbonate resin, polyvinyl chloride resin, diallyl phthalate resin, epoxy resin, polyarylate resin, norbornene resin. Etc. are preferably exemplified. A resin having heat resistance and transparency is more preferable, and a norbornene resin is particularly preferable.

In the present invention, the sputtering method for introducing the metal oxide onto the metal film formed by the above method is not particularly limited as long as it is an ordinary method according to the above definition, and for example, A so-called reactive sputtering method, in which oxygen gas is introduced at the same time as sputtering during film formation, can be preferably used.

The antireflection film is not limited to the above-mentioned one layer,
By forming two or more kinds of materials having different refractive indexes into multiple layers, the transmittance of the transparent base material can be increased without impairing the adhesiveness of the film.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to some examples of the present invention. However, these examples do not limit the present invention.

[0016]

EXAMPLES Example 1 (1) Titanium and silicon were attached as target materials in a vacuum chamber of a sputtering apparatus (HK-3S manufactured by Hirano Koson) installed in a clean room of class 10,000. As the base material, a processed transparent norbornene resin (Arton molded product) was prepared. After this was attached to the substrate holder installed in the vacuum chamber, the vacuum chamber was evacuated to 1.3 × 10 ⁻³ (Pa). After exhaustion, argon was introduced as a medium gas to reduce the total pressure in the vacuum chamber to 0.
It was set to 5 (Pa). (2) Titanium, which is the first layer, was formed as an intermediate layer on the surface of the substrate to a thickness of 15 nm. After forming the intermediate layer, an antireflection film made of titanium oxide and silicon oxide having the following constitution was formed by a reactive sputtering method in which oxygen gas was introduced into the vacuum chamber. These are shown in FIG. The substrate temperature during film formation was maintained at 100 ° C. or lower by a cooling device provided in the substrate holder portion. The second layer TiO ₂ (refractive index 2.35) has an optical thickness of 28 (nm), the third layer SiO ₂ (refractive index 1.46) has an optical thickness of 41 (nm) the fourth layer TiO ₂ (refractive index 2.35) with an optical film thickness of 277 (n
m) The fifth layer of SiO ₂ (refractive index 1.46) has an optical thickness of 131 (n).
m) (3) The results of performance evaluation of the antireflection film are shown in Table 1. A spectral characteristic graph of this sample is shown in FIG.

[Embodiment 2] In (2) of Embodiment 1, the first layer as a middle layer on the surface of the substrate is made of silicon to a thickness of 15
The same procedure as in Example 1 was performed except that the film was formed to a thickness of nm. The results of performance evaluation of the antireflection film are shown in Table 1. A spectral characteristic graph of this sample is shown in FIG.

Comparative Example 1 (1) Titanium and silicon were attached as target materials in a vacuum chamber of a sputtering apparatus (HK-3S manufactured by Hirano Koson) installed in a clean room of class 10,000. As the base material, a processed transparent norbornene resin (Arton molded product) was prepared. After this was attached to the substrate holder installed in the vacuum chamber, the vacuum chamber was evacuated to 1.3 × 10 ⁻³ (Pa). After exhaustion, argon was introduced as a medium gas to reduce the total pressure in the vacuum chamber to 0.
It was set to 5 (Pa). (2) An antireflection film made of titanium oxide and silicon oxide having the following constitution was formed by a reactive sputtering method performed by introducing oxygen gas into the vacuum chamber. These are shown in FIG. The substrate temperature during film formation was maintained at 100 ° C. or lower by a cooling device provided in the substrate holder portion. The first layer TiO ₂ (refractive index 2.35) has an optical film thickness of 28 (nm) the second layer SiO ₂ (refractive index 1.46) has an optical film thickness of 41 (nm) the third layer TiO ₂ (refractive index 2.35) with an optical film thickness of 277 (n
m) Fourth layer SiO ₂ (refractive index 1.46) with an optical film thickness of 131 (n
m) (3) The results of performance evaluation of the antireflection film are shown in Table 1. A spectral characteristic graph of this sample is shown in FIG.

[0019]

[Table 1]

Each test method in the performance evaluation table 1 is shown below. a) Adhesion Regarding the sample after film formation, JIS standard Z2307-20
A 90-degree direction tensile test was conducted in accordance with No. 00. For the tape peeling portion of the sample, use an optical microscope (magnification 30
The surface was observed with 0 times) to confirm the adhesion of the antireflection film. The judgment was performed as follows. A: No peeling of the antireflection film was confirmed in the range of the surface observation. B: Peeling of the antireflection film was confirmed in 1 to 10% of the area observed on the surface. C: Peeling of the antireflection film was confirmed in 11 to 30% of the area observed on the surface. D: Peeling of the antireflection film was confirmed in 31 to 50% of the area observed on the surface. E: Peeling of the antireflection film was confirmed in 51% or more of the surface observed area.

B) Heat resistance test The sample after film formation was placed in a hot air oven at 70 ° C. 3
After heating for a period of time, the surface was observed with an optical microscope (magnification: 300 times). The judgment was performed as follows. A: No change was observed in the antireflection film in the range where the surface was observed. B: Cracks were generated on the surface in 1 to 10% of the range of the surface observed. C: Cracks were generated on the surface in 11% to 30% of the surface observed range. D: Cracks were generated on the surface in 31 to 50% of the range of the surface observed. E: Cracks were generated on the surface in 51% or more of the area observed on the surface.

C) Surface observation The sample on which the antireflection film was formed was held by a fluorescent tube and visually observed to confirm whether or not interference fringes were observed on the film formation surface.

D) Measurement of reflectance The sample after the antireflection film was formed was measured with an optical film characteristic analyzer (USPM-RU manufactured by Olympus Optical Co., Ltd.) at wavelengths of 380 to 780 (n).
The reflectance was measured in the region m).

[0024]

According to the present invention, it is possible to obtain an antireflection film which is applicable to a wide range of plastic base materials and is particularly suitable for optical members and has good adhesion and heat resistance by the sputtering method. Further, there is an advantage that a series of film forming steps can be automated because the work efficiency can be greatly improved because a complicated process such as hard coating process is not performed and the whole film forming process can be performed by the sputtering method.

[0025]

[Brief description of drawings]

FIG. 1 is a diagram showing a film configuration of an antireflection film according to Example 1.

2 is a diagram showing a film configuration of an antireflection film according to Comparative Example 1. FIG.

3 is a graph showing the results of measuring the spectral reflectance of Example 1. FIG.

FIG. 4 is a graph showing the results of measuring the spectral reflectance of Example 2.

5 is a graph showing the results of measuring the spectral reflectance of Comparative Example 1. FIG.

[0026]

[Explanation of symbols]

a: plastic substrate b: Metal film c and e: Metal oxide 1 (high refractive index) d and f: Metal oxide 2 (low refractive index)

Claims (7)

[Claims] 1. A method for producing an antireflection film, comprising the steps of: when an antireflection film is produced on the surface of a plastic substrate by a sputtering method, a metal film is previously formed as an intermediate layer on the surface of the substrate. 2. The method for producing an antireflection film according to claim 1, wherein the metal film is introduced and formed by a sputtering method. 3. The metal forming the metal film is one or more selected from the group consisting of titanium, silicon, aluminum, zinc, zirconium, tantalum and magnesium. Method for producing antireflection film of the above. 4. The method for producing an antireflection film according to claim 1, wherein the metal forming the metal film is titanium or silicon. 5. The film thickness (d) of the metal film is 10 (nm) ≦ d ≦ 30.
(nm) is a manufacturing method of the antireflection film in any one of Claims 1-4 characterized by the above-mentioned. 6. The method for producing an antireflection film according to claim 1, wherein the plastic substrate is a transparent heat resistant resin. 7. The method for producing an antireflection film according to claim 1, wherein the antireflection film is a multilayered structure of metal oxides.