JP2003277922A - Diamondlike hard carbon film and antireflection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diamondlike hard carbon film which has excellent water repellency and extremely satisfactory adhesion with an oxide film, a target with which the diamondlike hard carbon film can be produced, a diamondlike hard carbon film which has excellent water repellency and extremely satisfactory adhesion with a metal oxide film, and an antireflection film having the diamondlike hard carbon film as a protective film. <P>SOLUTION: The antireflection film consists of a transparent substrate, an antireflection film formed on the substrate and a protective film formed on the antireflection film. The protective film consists of a diamondlike hard carbon film containing at least one or more kinds of metals selected from the group consisting of aluminum, magnesium, yttrium, gadolinium, cerium and calcium, and fluorine. The protective film is produced by a sputtering method. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diamond-like hard carbon film and an antireflection film using the same as a protective film, and more particularly to a liquid crystal display (LCD), a cathode ray tube (CRT) for a display screen of a television or a computer, The present invention relates to an antireflection film that is attached to a plasma display panel (PDP) or other display screen and has excellent scratch resistance, durability and antireflection performance.

[0002]

2. Description of the Related Art When viewing a display screen such as a liquid crystal display or a cathode ray tube, light from a window or light from interior lighting (back light source) is reflected on the display screen, which makes it difficult to see the display, resulting in fatigue during display work. Is also the cause of. As one of the countermeasures, the display image quality is improved by providing an antireflection film on the surface of the display screen.

Generally, a display screen such as a liquid crystal display (LCD), a cathode ray tube (CRT) for a display screen of a television or a computer is often made of glass, and conventionally, a glass surface has an antireflection function. By directly applying anti-reflection processing, we have avoided the visual obstacle due to the reflection of the back light source.

As such an antireflection treatment, usually,
Multilayer film consisting of metal oxides and dielectrics is vapor-deposited in high vacuum, but if the material to be processed has a size of several tens of centimeters square such as CRT or has a curved surface, large-scale production is performed. There was a problem in terms of economy because it required equipment.

Therefore, it has become possible to prepare a resin film such as PET or PC which is provided with an antireflection function in advance and adhere it to the glass surface. That is, a plastic film or sheet-like base material having antireflection ability is attached to a glass surface using an adhesive, a heat-curable adhesive, an ultraviolet-curable adhesive, or the like, or with the passage of time, or It is firmly fixed by heating or irradiation with ultraviolet rays.

However, such a resin film is
Since it itself is soft, it is weak against scratches and impractical in terms of wear resistance and durability. In order to overcome this problem, a method has been studied in which an acrylic hard coat film is provided on the surface of a resin film and an antireflection film is formed thereon to improve wear resistance.

Further, in order to protect the antireflection film from dirt, dust, scratches, etc., a protective film is formed on the antireflection film. Conventionally, a fluorine-based resin film is often used as the protective film, and the fluorine-based resin film is effective in preventing stains and is called an antifouling film from the viewpoint of function. Such an antifouling film is less likely to have stains such as fingerprints on its surface, and stains once adhered can be easily removed by dry wiping or the like. The antifouling film made of a fluorine-based resin is a coating agent obtained by adding a perfluoro group-containing phosphate ester as a catalyst to a solution containing a perfluoro group-containing silicon-based material as a solute. It is formed by applying it on and further drying.

However, the antifouling film made of fluorine resin is
Water repellency is its main function, and it is effective in preventing stains and removing stains, but it has poor resistance to scratches. Further, since the antifouling film made of a fluorine-based resin is formed by a wet process and uses a fluorine-based solvent, it may be difficult to use due to environmental problems in the future.

Further, recently, Japanese Patent Laid-Open No. 2001-141
Japanese Patent No. 903 describes a technique in which a diamond-like hard carbon film composed only of carbon element is used as a protective film on an antireflection film. Since the diamond-like hard carbon film is a hard film and has a small wear coefficient, its durability is improved by using it as a protective film.

However, when the diamond-like hard carbon film composed only of carbon element is directly formed on the antireflection film as a protective film, the adhesion between the diamond-like hard carbon film and the antireflection film must be good. However, while the diamond-like hard carbon film is a carbon covalent bond material, the antireflection film is a metal oxide and an ionic bond material. In addition, the diamond-like hard carbon film is not practically sufficient in water repellency as compared with an antifouling film made of a fluororesin, and is not effective in preventing stains and removing stains.

[0011]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and is a diamond-like hard carbon film having excellent water repellency and excellent adhesion to a metal oxide film, and the diamond-like hard carbon film. An object is to provide a target capable of producing a film, and an antireflection film having the diamond-like hard carbon film as a protective film.

[0012]

The sputtering target of the present invention contains carbon as a main component and metal fluoride particles dispersed therein. The metal fluoride is one or more selected from the group consisting of aluminum fluoride, magnesium fluoride, yttrium fluoride, gadolinium fluoride, cerium fluoride and calcium fluoride. The sputtering target was prepared by mixing carbon and the above compound such that F / C during film formation was 0.3 or less in atomic ratio, and sintering the mixture by hot pressing.

The diamond-like hard carbon film of the present invention contains fluorine and a metal. The metal is one or more selected from the group consisting of aluminum, magnesium, yttrium, gadolinium, cerium and calcium. The diamond-like hard carbon film is manufactured by the sputtering method using the target. The content of fluorine and metal is 0.18 for F / C and 0.0 for M / C.
It was 6.

The antireflection film of the present invention comprises a transparent substrate, an antireflection film formed on the substrate, and the protective film formed on the antireflection film.

The present invention is a diamond-like hard carbon film formed without using a wet process.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a result of earnest research aimed at achieving the above-mentioned object, the present inventor has found that when forming a diamond-like hard carbon film used as a protective film, a carbon fluoride is used as a main component and a metal fluoride is used as a main component. An attempt was made to form a film by a sputtering method using a sputtering target in which particles were dispersed.
By this film formation, a diamond-like hard carbon film containing metal and fluorine is formed, which is excellent in water repellency as compared with the conventional diamond-like hard carbon film composed of only carbon, and thus has excellent antifouling performance and reflection. The inventors have found that when they are formed on an antireflection film, they have extremely excellent adhesion to the antireflection film, and have completed the present invention.

The antireflection film of the present invention comprises a metal oxide formed as an antireflection film laminated on a transparent substrate composed of a film substrate, and contains metal fluoride particles having carbon as a main component dispersed therein. A hard carbon film is provided as a protective film using the target.

The antireflection film has a structure in which a metal oxide thin film or a metal nitride thin film having a low refractive index is laminated by a vacuum thin film forming technique, so that light having different phases reflected at the interface of each layer is caused by interference. It becomes possible to reduce the reflected light and to have a high antireflection ability.

Specifically, examples of the metal oxide thin film material having a low refractive index include SiO ₂ and MgF _2, and examples of the metal oxide thin film material having a high refractive index include TiO ₂ , ZrO ₂ , and Hf.
_{O 2, Ta 2 O 5,} Nb 2 O 5, In 2 O 3, ITO , and examples of the high refractive index metal nitride thin film material, TiN, Z
rN etc. are mentioned.

As means for forming these thin films, a vacuum vapor deposition method for heating and evaporating the above-mentioned metal oxide thin film material in a vacuum in which a slight amount of oxygen gas is introduced, and depositing it on a substrate, and a method for forming the material Any of the ion plating method in which evaporation is performed in a discharge, the above-mentioned sputtering method, or the like can be used.

After forming the antireflection film, a diamond-like hard carbon film containing fluorine and a metal is formed as a protective film.

In this Raman spectroscopic spectrum of carbon, a peak derived from a diamond structure (sp3 bond) and a peak derived from a graphite structure (sp2 bond) are observed in this hard carbon film. Thus, the hard carbon film in which peaks derived from the diamond structure and the graphite structure are observed is usually called a diamond-like carbon film.

As a method for forming the hard carbon film of the present invention, there is a magnetron sputtering method. This method is an effective method when film formation of a material having a low vapor pressure or precise film thickness control is required, and the operation is very simple, and is therefore widely used industrially.

In the sputtering method, a target, which is a raw material of the film, is placed in a vacuum chamber to serve as a cathode, and a substrate is placed on the opposite side of the target to serve as an anode. A glow discharge is generated between them to generate argon plasma, the argon cations in the plasma are made to collide with the target on the cathode, and the particles of the target component that are repelled by this collision are deposited on the transparent substrate on the substrate. It is to form a film. As a method of generating argon plasma, there are a method using high frequency plasma and a method using direct current plasma.

The magnetron sputtering method is a sputtering method in which a magnet is installed on the back side of a cathode and a magnetic field is applied to the space between the target and the substrate to increase the plasma generation efficiency.

In this magnetron sputtering method, the film obtained from the carbon target is a hard carbon film, which is a film having a mixture of a diamond structure and a graphite structure (diamond-like carbon film), but the ratio thereof varies depending on the manufacturing conditions. Further, when plasma formed from a mixed gas obtained by mixing argon gas with hydrogen gas or nitrogen gas is used, it is easy to obtain a hard carbon film having a large proportion of amorphous state. Further, in order to use the hard carbon film as a diamond-like carbon film, the balance of the magnetic field by the magnet arranged on the back surface of the cathode (cathode) is made unbalanced, and a part of the plasma is spread to the vicinity of the transparent substrate surface. It is easy to obtain even by sputtering.

Since the diamond-like hard carbon film of the present invention contains fluorine, it is excellent in water repellency and antifouling function as compared with the conventional hard carbon film. Further, in the antireflection film using the diamond-like hard carbon film of the present invention as a protective film, the metal ions in the diamond-like hard carbon film form an ionic bond with the oxide on the surface of the antireflection film to prevent reflection. The adhesion to the film was extremely good.

Therefore, the diamond-like hard carbon film of the present invention containing fluorine and metal is excellent in water repellency, has a very low coefficient of friction, and has a very high hardness, so that the strength of the film itself is improved and it is practically used. It is possible to secure sufficient durability. Further, since it contains a metal, an ionic bond is formed at the interface with the antireflection film, and the adhesiveness between the protective film and the antireflection film is practically sufficient.

The present invention will be described below with reference to specific examples, but it goes without saying that the present invention is not limited to these examples.

[0030]

EXAMPLE As shown in FIG. 1 as a schematic sectional view showing the basic structure of the antireflection film of the present invention, the antireflection film of this example is formed on a transparent substrate and a transparent substrate formed thereon. The antireflection film and the protective film formed on the antireflection film. The antireflection film is attached to the screen of a CRT or LCD via an adhesive, for example.

First, a diamond-like hard carbon film forming target is mixed with carbon powder and aluminum fluoride powder at a predetermined ratio, specifically, so that F / C during film formation is 0.3 or less. Manufactured by sintering by a vacuum hot press method.

For the transparent substrate, for example, a cured acrylic resin (hard coat) is coated on a polyethylene terephthalate (PET) film having a thickness of 50 to 200 μm.
An organic base material having a thickness of about 20 μm was used.

Next, an antireflection film was formed by the following procedure.

On the hard coat layer of the transparent substrate, T
All four layers of the io ₂ film, the sio ₂ film, the TiO ₂ film, and the sio ₂ film are sequentially measured and controlled online by using a roll-up type sputtering device with the film thickness of each layer as the optical film thickness (n × d). However, they were sequentially formed. The TiO ₂ film is Ti
It was formed by a reactive DC sputtering method using a target and oxygen gas. The SiO ₂ film was formed by a reactive DC sputtering method using a Si target and oxygen gas.

The structure of the magnetron sputtering apparatus used in the step of forming the protective film when producing the antireflection film of the present invention will be described below with reference to FIG.

This magnetron sputtering device is
In a vacuum chamber whose inside is kept at a predetermined degree of vacuum, a transparent substrate (object to be processed) on which an antireflection film is formed is moved from a constant-speed rotating feed roll to a constant-speed winding roll, It is configured to run sequentially. A rotary support having a diameter larger than the diameter of each roll is provided at a low speed so as to pull out the antireflection film in the middle of the transparent substrate running from the feed roll side to the take-up roll side. Further, the object to be processed is conveyed onto the rotary support so that the antireflection film faces the outside (the side opposite to the rotary support side). Guide rolls are provided between the feed roll and the rotary support, and between the rotary support and the take-up roll, respectively.The guide rolls are provided between the feed roll and the rotary support and between the rotary support and the take-up roll. The object to be processed that travels between the rolls is configured to be able to travel smoothly while being given an appropriate tension.

The feed roll, the take-up roll and the rotary support are each in the shape of a cylinder having a height substantially the same as the width of the object to be processed. Therefore, in this magnetron sputtering apparatus, the object to be processed is sequentially sent out from the feed roll and passes along the outer peripheral surface of the rotary support,
Further, it is wound up on a winding roll.

On the other hand, in the vacuum chamber, a balanced magnetron cathode is provided below the rotary support, and a carbon target containing aluminum fluoride particles is mounted on the balanced magnetron cathode. A protective film is formed when an object to be processed having an antireflection film on its surface passes between the rotary support and the target.

The magnetron cathode is a cathode in which a permanent magnet is arranged inside the cathode. When this is used, when voltage is applied to cause glow discharge,
A dense plasma can be generated on the target. A high frequency power source (RF power source) arranged outside the vacuum chamber is connected to the magnetron cathode, and since a voltage lower than the substrate potential is supplied by the high frequency power source, sputtering by argon ions occurs. It is possible to form a film on the object to be processed.

As described above, the object to be processed fed from the feed roll and traveling along the outer peripheral surface of the rotary support is
A protective film made of a diamond-like hard carbon film containing fluorine and a metal is formed on the antireflection film on the object to be processed at the time of passing through the rotary support and the reaction chamber. The protective film exhibits excellent water repellency, the antifouling effect is enhanced, the lubricity is obtained, and the friction coefficient can be reduced, so that good durability can be secured. Further, the diamond-like hard carbon film containing fluorine and metal has excellent adhesiveness and extremely improved durability because ionic bonds occur at the interface with the antireflection film.

In this embodiment, the case where aluminum fluoride is used as the fluorine and metal source will be described.
In the same manner, a diamond-like hard carbon film forming target containing any of magnesium fluoride, yttrium fluoride, gadolinium fluoride, cerium fluoride and calcium fluoride is produced, and an antireflection film is produced in the same manner as described above. As a result, the same effect could be obtained.

Example 1 A diamond-like hard carbon film-forming target is produced by mixing carbon powder and aluminum fluoride powder in the proportions shown in Example 1 of Table 1 and sintering them by a vacuum hot pressing method. did.

As the transparent substrate, an organic substrate was used in which a 188 μm thick polyethylene terephthalate (PET) film was coated with an acrylic curable resin (hard coat) to a thickness of about 6 μm.

On the hard coat layer of the transparent substrate, Ti
O ₂ film (13 nm), SiO ₂ film (30 nm), TiO ₂
The film (116 nm) and the SiO ₂ film (87 nm) are all arranged in this order, and the film thickness of each layer is set as the optical film thickness (n × d) by using the above-mentioned winding type sputtering device while controlling the measurement online. , Sequentially formed. The TiO ₂ film was formed by a reactive DC sputtering method using a Ti target and oxygen gas. The SiO ₂ film was formed by a reactive DC sputtering method using a Si target and oxygen gas.

The magnetron sputtering device described above (the diameter of the rotary support is 70 cm, the target is 30 × 1).
A 0 cm rectangular parallelepiped was used. ) Is used, a transparent substrate having an antireflection film formed thereon is mounted on a feed roll, and then argon gas is inserted into the vacuum chamber to a gas pressure of 0.6 Pa, and high-frequency power of 500 W is supplied to the target. Glow discharge was generated between the rotating supports, and a 2 nm-thick protective film was formed on the object to be processed while conveying the object.

Raman spectroscopic spectra of the protective film thus produced were measured. As a result, peaks due to the diamond structure and the graphite structure were observed. Therefore, it was confirmed that a diamond-like hard carbon film was formed. . Under the same conditions, the film thickness is increased (70
0 nm) using the prepared diamond-like hard carbon film,
A composition analysis by PMA and XRF revealed that not only carbon but also fluorine and aluminum had an F / C molar ratio of 0.0.
3. It was found that the Al / C molar ratio was 0.01.

Further, in order to evaluate the adhesiveness and durability of the diamond-like hard carbon film of Example 1, the following experiment was conducted.

A spherical head in which a load of 2 kg was applied to the surface of the protective film after thermal shock was repeated 5 cycles, with one cycle consisting of 6 hours at 70 ° C. and 6 hours at −40 ° C. It was pressed through a gauze moistened with alcohol and rubbed back and forth 30 times in a linear distance of 10 cm. The antireflection film of Example 1 in which the diamond-like hard carbon film containing fluorine and aluminum was used as the protective film did not peel off even in such a test.

The results of measuring the friction coefficient are shown in Table 1.

FIG. 3 is a graph showing the reflection characteristics of the first embodiment.

Comparative Example 1 An antireflection film was produced in the same manner as in Example 1 except that only carbon was used as the target material.

Further, when the same adhesion and durability test as in Example 1 was conducted, it was found that peeling was observed at the interface between the protective film and the antireflection film, and the adhesion was not sufficient.

The results of measuring the friction coefficient are shown in Table 1.

(Examples 2 to 4) An antireflection film was prepared in the same manner as in Example 1 except that the amount of aluminum fluoride mixed during the preparation of the target was changed so as to be Examples 2 to 4 in Table 1. Was produced.

The results of measuring the friction coefficient are shown in Table 1.

[0056]

[Table 1]

The antireflection film of the present invention (Examples 1 to 1)
In 4), the coefficient of friction of the surface is 0.10 or less, which is a very small coefficient of friction as compared with the conventional case (Comparative Example 1) containing no fluorine and metal.

Further, a pencil hardness test based on the JIS standard was carried out. As a result, the antireflection film of the present invention had a hardness of 4
It was found to have a high hardness of H.

Further, in a water repellency test using a contact angle with water, it was found that the water repellency was improved by containing fluorine.

From the above, according to the present invention, anti-reflection having excellent durability, excellent adhesion, and excellent water repellency, even without using a fluorine solvent which is concerned about environmental problems as in the prior art. It becomes possible to provide a film and its protective film, and a target for easily forming the protective film.

[0061]

As is apparent from the above description, according to the present invention, it is possible to produce a diamond-like hard carbon film which is more excellent in water repellency and durability than ever before.

Further, the antireflection film using the diamond-like hard carbon film of the present invention as a protective film is excellent in antifouling function, adhesiveness and durability, and the visibility of the display screen for various displays. Very useful for improvement.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the basic structure of an antireflection film of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a sputtering apparatus used in Examples.

FIG. 3 is a graph showing the reflection characteristics of the antireflection film shown in FIG.

Continued front page    F-term (reference) 4F100 AA20 AA21 AA31C AA37C                       AB01C AB09C AB10C AK25                       AK42 AR00B AR00C AT00A                       BA03 BA07 BA10A BA10C                       DE01C EH66C EJ08 EJ17                       EJ24 GB41 GB48 JK09 JK12C                       JN01A JN06B                 4G046 CB08 CC06                 4K029 AA11 AA25 BA01 BA03 BA34                       BA42 BA46 BA48 BA64 BB02                       BC07 BD00 CA05 DC05

Claims (6)

[Claims] 1. A sputtering target comprising carbon as a main component and metal fluoride particles dispersed therein. 2. The metal fluoride is one or more selected from the group consisting of aluminum fluoride, magnesium fluoride, yttrium fluoride, gadolinium fluoride, cerium fluoride and calcium fluoride. The target according to claim 1. 3. A diamond-like hard carbon film containing fluorine and a metal. 4. The diamond-like hard carbon film according to claim 3, wherein the metal is one or more selected from the group consisting of aluminum, magnesium, yttrium, gadolinium, cerium and calcium. 5. A diamond-like hard carbon film produced by a sputtering method using the target according to claim 1. 6. An antireflection film comprising a transparent substrate, an antireflection film formed on the substrate, and a protective film formed on the antireflection film, wherein the protective film comprises: Item 6. An antireflection film, which is the diamond-like hard carbon film according to any one of Items 3 to 5.