JP2006001014A - Fluorine-containing thin film and manufacturing method of base material having fluorine-containing thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a fluorine-containing thin film excellent in the adhesion with a base material and also excellent in dimensional precision and mold releasability as a precise mold. <P>SOLUTION: The fluorine-containing thin film is formed on the surface of the base material and constituted by simultaneously depositing a fluorine-containing organic substance, which can be deposited by a vapor deposition method, and a substance, which can be deposited by an ion beam sputtering method, on the surface of the base material. The fluorine-containing organic substance is a perfluoro type polymer and this polymer contains at least one double bond carbon or triple bond carbon and a -COOH group or an -Si(OR)<SB>3</SB>group (wherein R is an alkyl group) in its molecule. The fluorine-containing organic substance is an amorphous perfluoro resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fluorine-containing thin film formed on the surface of a substrate and a method for producing a substrate having the fluorine-containing thin film.

When producing a plastic molded product having a precise shape, it is difficult to release the molded product from the molding die without impairing the precise shape. In recent years, miniaturization has become particularly difficult to release.
Conventionally, in order to ensure mold releasability between the molded product and the mold, (1) a release agent is applied to the mold surface in-line, or (2) a surface treatment that facilitates easy mold release on the mold surface in advance. To provide a release layer. However, each has the following problems.

  The method (1) has been conventionally performed as the most general mold release technique, but it is difficult to obtain a mold for stably molding a precise shape, and shape control on the order of submicrons. Cannot be applied to optical parts such as plastic lenses. In addition to the cost of the release agent, which is an auxiliary material, a device or man-hour for applying the release agent to the mold is required, and further, it is inevitable that the release agent adheres to the product. A cleaning step is also required to remove it. For this reason, cost and an environment are made worse.

  On the other hand, the method (2) is a method that gradually expands the application range with the recent increase in accuracy of plastic parts. The release layer currently in practical use is a DLC (diamond-like carbon) or TiN (titanium nitride) -based thin film (see, for example, Patent Document 1). These thin films are thermally and mechanically stable, and have a durability of several thousand shots in ordinary plastic molding. However, in any case, the releasability from the molded product is insufficient, and the product yield is reduced by losing the shape when the molded product is taken out.

Further, as a method for forming the release layer, a vacuum deposition method which is a kind of physical vapor deposition (PVD) is frequently used because the apparatus is simple and inexpensive.
The vacuum deposition method heats and evaporates a solid or granular target filled in a target container installed in a vacuum deposition apparatus in a high vacuum exceeding about 10 ⁻⁴ Pa, and this vapor is disposed opposite to the target. In this method, the thin film is formed by depositing on the surface of the substrate maintained at a constant temperature.
In the vacuum evaporation method, a high-purity thin film can be formed at a high film formation rate without changing the structure of a polymer that becomes a thin film during vapor deposition by forming the film under a high vacuum. In order to use the target as a vapor, a heating method is often used. Examples of the heating method include a resistance heating method, an electron beam method, and a laser method (laser ablation).
As a fluorine-containing thin film forming method using the vacuum deposition method, a method of forming an antifouling thin film on the surface of an optical member such as a lens is disclosed (see Patent Document 2).
However, when producing a fluorine-containing thin film by a vacuum deposition method, there are the following problems.
(1) The fluorine-containing thin film has insufficient adhesion to the substrate. Fluorine-containing organic compounds with functional groups that improve adhesion to the substrate have adhesion to the substrate, but the film surface is almost terminated with fluorine, so the film grows further. do not do. Therefore, the adhesion is not sufficient, or the film surface appears clouded.
(2) Since the film thickness is as thin as several nanometers to several tens of nanometers, the durability (abrasion resistance) is inferior. Furthermore, it cannot be used for applications requiring a film thickness of several tens of nm or more.
(3) Since fine particles that have not been formed are adhered to the film surface, the film is cloudy in the state after film formation. For this reason, when a transparent film is required, it is necessary to wipe off the surface or the surface is inferior in smoothness. As a result, it cannot be used for a precision mold that cannot be wiped off, and its application is limited.

A film forming method for manufacturing a fluorine-containing thin film in a state where an ion beam excited with an inert gas such as Ar, He, Ne or the like is irradiated on a substrate is known. Is decomposed or sputtered and is difficult to deposit with high efficiency.
JP-A-5-169594 Japanese Patent Laid-Open No. 11-071665

  The problem to be solved is that a fluorine-containing thin film repellent that is excellent in adhesion to a substrate and excellent in dimensional accuracy as a precision mold and releasability is not obtained.

The fluorine-containing thin film of the present invention is formed on a substrate surface, and the fluorine-containing thin film is formed by simultaneously depositing a fluorine-containing organic material that can be deposited on the substrate surface by a vapor deposition method and a material that can be deposited by an ion beam sputtering method. It is characterized by that.
The fluorine-containing organic substance is a perfluoro polymer, and the polymer includes at least one double bond or triple bond carbon, —COOH group, or —Si (OR) ₃ group (R is an alkyl group). Which represents a group) in the molecule.
The fluorine-containing organic substance is an amorphous perfluoro resin.

  Another fluorine-containing thin film of the present invention is a fluorine-containing thin film formed on the substrate surface, and the fluorine-containing thin film is deposited on the substrate surface while performing argon sputter etching on at least one kind of fluorine-containing organic compound. It is characterized by being made.

The method for producing a substrate having a fluorine-containing thin film according to the present invention is a method for producing a substrate having a fluorine-containing thin film on the surface, the step of arranging the substrate in a predetermined thin film forming apparatus, and a fluorine-containing organic material. And a step of depositing a non-fluorine-containing substance on the surface of the substrate simultaneously by an evaporation method and a non-fluorine-containing substance by an ion beam sputtering method.
The vapor deposition method is a vacuum vapor deposition method. Further, the deposition rate by a vacuum evaporation method is 10 times or more the deposition rate by the ion beam sputtering method. In addition, the step of depositing on the substrate surface is a step of forming a film while performing argon sputter etching.

  Another method for producing a substrate having a fluorine-containing thin film of the present invention is a method for producing a substrate having a fluorine-containing thin film on the surface, the step of placing the substrate in a predetermined thin film forming apparatus, And a step of depositing a fluorine organic material on the surface of the substrate by vapor deposition while performing argon sputter etching.

  The fluorine-containing thin film of the present invention is formed by simultaneously depositing a fluorine-containing organic material that can be deposited by an evaporation method and a material that can be deposited by an ion beam sputtering method on the substrate surface. Since the film is deposited by vapor deposition while performing, a film having a film thickness on the order of several hundred nm to several μm can be formed, whereas the film thickness is several tens of nm in the conventional example. For this reason, the mold life when used as a mold release agent for resin molding is improved several times.

  Examples of the substrate on which the fluorine-containing thin film is formed include metals and ceramics. As the mold for precision molding, a metal material is preferable, and examples thereof include stainless steel, aluminum or an alloy material thereof, magnesium or an alloy material thereof, iron or an iron alloy material, and the like. Among these, a stainless material excellent in adhesion to the substrate and peelability is preferable.

  The fluorine-containing organic material that can be used in the present invention is a polymer or copolymer of unit monomers containing an average of one or more fluorine atoms and can be used as long as it is an organic polymer capable of forming a film. For example, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer Polymer, tetrafluoroethylene-ethylene copolymer, trifluorochloroethylene polymer, trifluorochloroethylene-ethylene copolymer, polyvinyl fluoride, polyvinylidene fluoride, fluoropolyether polymer, polyfluorosilicone, aliphatic ring Examples thereof include perfluoropolymer having a structure.

Among the above-mentioned fluorine-containing organic substances, perfluoro polymers are preferable, and at least one double bond or triple bond carbon, —COOH group, or —Si (OR) ₃ group may be included in the molecule. preferable. R is preferably an alkyl group having 1 to 3 carbon atoms. By using this perfluoro polymer, the adhesion to the substrate is excellent.

As the fluorine-containing organic material suitably used, fluoroalkylsilane TSL8257 (trademark, manufactured by GE Toshiba Silicone) having —Si (OR) ₃ group at the end of the main chain, and amorphous perfluoro heavy having an aliphatic ring structure in the main chain Cytop (trademark, manufactured by Asahi Glass Co., Ltd.), which is a coalescence, can be mentioned.

As the material that can be deposited by the ion beam sputtering method, any material that can be sputtered by irradiation with ions emitted from the ion gun can be used. Examples of such substances include inorganic substances such as SiO ₂ and CeF ₂ , metals such as metal aluminum and metal silicon, and polymer compounds such as acrylic resin, polyethylene, polyimide, and polytetrafluoroethylene.
Of these, inorganic substances such as SiO ₂ are preferred.

Using the above material, obtained by evaporation of the fluorine-containing organic material, by ion beam sputtering an inorganic material such as SiO _2, in the same deposition apparatus, by depositing on the same time base, a fluorine-containing thin film It is done.
When the inorganic sputtered particles collide with the fluorine-containing organic compound deposited on the base material, polymerization of molecules constituting the fluorine-containing organic substance is promoted to form a strong film. In addition, the functional group attached to the fluorine-containing organic substance ensures adhesion to the substrate, and polymerization between the fluorine-containing organic compounds is performed by inorganic ion beam sputtered particles, for example, Ar ion beam sputtered particles, which are co-deposited with the fluorine-containing organic compound. Can be promoted. Since the energy of the sputtered particles is several tenths to several hundredths of that of direct ion beam irradiation, decomposition of the deposited film can be suppressed and film formation with high efficiency becomes possible.

An example of a film forming apparatus for forming the fluorine-containing thin film of the present invention is shown in FIG.
The film forming apparatus 1 includes a crucible 7 that accommodates a vacuum deposition target 4 in a vacuum container 2 that includes an exhaust device 3, an ion beam sputtering target 5, and an ion gun 6 that irradiates the target with an Ar ion beam. Is housed. A base material 8 is disposed to face the target 4 and the target 5. 9 is a film thickness meter (QCD) for measuring the thickness of a thin film to be formed, and 10 is an argon gas introducing device. The crucible 7 is formed of a high melting point oxide such as alumina (Al ₂ O ₃ ) or beryllia (BeO), and a filament of a high melting point metal such as tantalum (Ta), molybdenum (Mo), tungsten (W) or the like is used. It is heated by a heating device (not shown).
The target used for the ion beam sputtering of the present invention is the above-mentioned SiO ₂ or the like, and the ion gun is a known one that draws ions from the plasma in the plasma chamber and irradiates the target with the ion beam. It is done. As the ion source, an inert gas such as He, Ne, or Xe can be used in addition to the Ar gas.

The manufacturing method of the base material which has a fluorine-containing thin film using the said film-forming apparatus is demonstrated.
(1) Degreasing cleaning of coated substrate: The coated substrate is washed in advance. The cleaning is performed with an organic solvent such as acetone, brush cleaning with isopropyl alcohol (IPA), or other ultrasonic cleaning according to the type of substrate.
(2) Setting of target and coated substrate: The crucible 7 is filled with a fluorine-containing organic substance, an inorganic material such as SiO ₂ is placed on the target 5 for ion beam sputtering, and the substrate 8 is mounted on a jig.
(3) Exhaust of film forming apparatus: Exhaust until the internal pressure of the apparatus reaches 10 ⁻² to 10 ⁻⁴ Pa. The internal pressure of the apparatus is preferably 5 × 10 ⁻³ Pa or less.

(4) Formation of fluorine-containing thin film: While flowing Ar gas into the apparatus at a rate of 5.0 SCCM, the temperature of the crucible 7 is heated from 250 ° C. to 700 ° C. at a heating rate of 50 ° C./min. At the same time, the ion beam current value passed through the ion gun 6 is adjusted to about 20 to 50 mA. This ion beam current value is at a level that cannot be detected by the film thickness meter (QCD) 9 as the film forming speed of SiO ₂ alone. Increasing the ion beam current increases the film strength, but tends to deteriorate the water repellency.

In the film forming method of the present invention, the film forming speed of SiO ₂ is adjusted by adjusting the ion beam current value, and the film forming speed of the fluorine-containing organic material is adjusted by adjusting the temperature of the crucible 7. By this adjusting method, it is preferable that the deposition rate by the vacuum evaporation method is 10 times or more the deposition rate by the ion beam sputtering method. The SiO ₂ concentration in the fluorine-containing thin film can be adjusted by adjusting the deposition rate. In the present invention, the SiO ₂ concentration is preferably 1% by weight or less.
The practical range for the thin film is 50 to 2000 nm, and preferably 100 to 200 nm. In addition, by setting the deposition rate by vacuum evaporation to more than 10 times the deposition rate by ion beam sputtering, the fluorine contact angle of the formed fluorine-containing thin film can exceed 90 °. It has sufficient water repellency.

  As another film forming method of the present invention, the film can be formed by vacuum deposition while performing argon sputter etching. The above-mentioned conditions can be used for the vacuum deposition conditions. In this case, a thin film with excellent adhesion strength and a contact angle with water exceeding 90 ° can be obtained without using ion beam sputtering. As the argon sputtering condition, an RF output of 10 to 15 W is preferable.

Example 1
A precision molding die (manufactured by SUS304) was prepared as a substrate, CYTOP (trademark, manufactured by Asahi Glass Co., Ltd.) as a fluorine-containing organic material target, and SiO ₂ as a material to be deposited by ion beam sputtering, respectively. The base material which has a fluorine-containing thin film was manufactured using the film-forming apparatus.
Fill the alumina crucible in the film deposition system with 3.5 g, place the SiO ₂ plate on the target table, evacuate the film deposition system to 5 × 10 ^-3 Pa or less, and argon gas near the ion gun. 5.0 While flowing SCCM, irradiate the Ar ion beam toward the sputtering target with an ion beam current of 45 mA. In this case, the film formation rate of SiO ₂ alone is a level that cannot be detected by the film thickness monitor.

Simultaneously with the ion beam, the crucible heater with Cytop is heated at a heating rate of 50 ° C for 5 minutes. When the heater temperature exceeds 250 ° C, the shutter is opened to start deposition on the silicon substrate. When the heater temperature exceeds 700 ° C, the shutter is closed to finish the deposition on the substrate.
The film thickness of the fluorine-containing thin film thus formed was about 150 nm, and a contact angle with water of about 105 to 115 ° was obtained.

The obtained fluorine-containing thin film was subjected to a durability test in which thermocompression was repeatedly applied to the prepreg sheet at a temperature of 170 ° C., 25 kgf / cm ² and a holding time of 60 minutes. As a result, the number of repetitions that could be repeated without sticking to the prepreg sheet was about 3 times the value of the comparative example described later.
In addition, the wear test was performed using a surface property measuring instrument HEIDON-14DR (manufactured by Shinto Kagaku Co., Ltd.), and sliding conditions were speed: 50 mm / min, FEED SCALE: 5 mm, load: 1 kgf, slider: alumina ball It was done in. The number of times that the substrate began to be visible due to the sliding of the alumina ball was measured at n = 5. Two base materials formed under the same conditions were used as samples. The results are shown in Table 1.

Example 2
A substrate having a fluorine-containing thin film was produced under the same conditions and method as in Example 1 except that the substrate was replaced with a glass plate. As a result of evaluation under the same conditions as in Example 1, a value about three times as long as that of the comparative example was obtained in the durability test. The results of the wear test are shown in Table 1.

Comparative Example 1
Prepare a precision mold (SUS304) as the base material and Cytop (trademark, manufactured by Asahi Glass Co., Ltd.) as the fluorine-containing organic material target, and use the film forming apparatus described above to form a thin film of fluorine-containing organic substance alone. The base material which has was manufactured. At this time, deposition by ion beam sputtering was not performed.
4.75 g of CYTOP top packed in an alumina crucible was heated at a heating rate of 50 ° C / 5 min. When 250 ° C was exceeded, the shutter was opened and deposition started. When the temperature exceeded 700 ° C, the shutter was closed and deposition was performed. Terminate. In this case, the film thickness is about 30 nm and the contact angle with water is 110 to 120 °. This thin film was removed only by light touch, and was inferior to the durability test.
In addition, a wear test was performed under the same conditions as in Example 1. The results are shown in Table 1.

Comparative Example 2
A substrate having a fluorine-containing thin film alone was produced under the same conditions and method as in Comparative Example 1, except that the substrate was replaced with a glass plate. Table 1 shows the results of the abrasion test.

表１に示すように、各実施例は、耐摩耗性が 2〜3 倍、各比較例より優れていた。

As shown in Table 1, each example was 2 to 3 times more wear resistant than each comparative example.

Example 3
An example of the film forming apparatus used in Example 3 is shown in FIG.
In the film forming apparatus 1 ′, a crucible 7 that accommodates a vacuum deposition target 4 and a crucible 7 that accommodates another target 4 ′ are accommodated in a vacuum container 2 having an exhaust device 3. A base material 8 is disposed opposite to the target 4 and the target 4 ′. Reference numeral 11 denotes a base material holder. 9 is a film thickness meter (QCD) for measuring the thickness of a thin film to be formed, and 10 is an argon gas introducing device.
Fill a copper crucible with a thickness of 1.5 mm with a fluorine-containing organic compound and place it on the heater. As the fluorine-containing organic compound at this time, PFA resin is preferable, and specifically, PFA350-J manufactured by DuPont is more preferable.
The film deposition system is evacuated to 5.0 × 10 ⁻³ Pa or less, and the degree of vacuum in the chamber is set to 2.1 × 10 ⁻² Pa while flowing argon gas with the shutter provided between the evaporation source and the substrate closed. Sputter etching is started at an RF output of 10 to 15 W in a state of about. The RF output can be arbitrarily changed in the range where the etching rate of sputter etching is slower than the deposition rate of PFA. While being discharged, the heater is heated to about 600 ° C. to evaporate the PFA and deposit it on the substrate. The deposition rate at this time is about 0.15 nm / sec.

The fluorine-containing thin film thus formed has a water contact angle of about 120 to 130 ° and has water repellency. Regarding the strength and adhesion of the film, the PFA film that was not performed at the same time as the sputter etching was scraped so that the film collapsed when it was rubbed very lightly with a cotton swab etc. On the other hand, the thin film obtained in Example 3 has such a strength that the surface of the substrate is not exposed to the extent that the surface is slightly scratched.
The evaporation source of the fluorine-containing organic compound is not limited to one type, and several different types of fluorine-containing organic compound evaporation sources can be used simultaneously. In that case, the evaporation amount from the evaporation source or the RF output of the argon gas sputter etching must be adjusted so that the total deposition rate from each evaporation source is faster than the etching rate of the argon gas sputter etching.

Example 4
A film having good adhesion to the substrate can be deposited by simultaneously depositing a material having an effect of improving adhesion between the fluorine-containing organic compound and the substrate while performing argon gas sputter etching.
The film forming apparatus used in Example 3 was used.
Alumina crucible is filled with approximately 3.5g of Asahi Glass Cytop and placed on the heater. Fill a copper crucible with a wall thickness of 1.5 mm with about 3.0 g of PFA350-J made by DuPont and place it on the heater.
The film deposition system is evacuated to 5.0 × 10 ⁻³ Pa or less, and the degree of vacuum in the chamber is set to 2.1 × 10 ⁻² Pa while flowing argon gas with the shutter provided between the evaporation source and the substrate closed. Sputter etching is started at an RF output of 10 to 15 W in a state of about. The crucible heater filled with PFA is heated to about 600 ° C in the discharged state to evaporate the PFA. At the same time, the crucible heater filled with CYTOP is heated to about 500 ° C, and the shutter is opened to the substrate. Start of deposition. The temperature of the crucible heater filled with CYTOP is raised to 750 ° C at a rate of 30 ° C / 5min., Held at 750 ° C for 2 minutes, and then the shutter is closed to complete the deposition. At the same time, the RF discharge is stopped and the sputter etching is terminated.
The film thus deposited has a film thickness of about 300 nm and a water contact angle of 120 to 130 °.

  The fluorine-containing thin film repellent and the substrate having the fluorine-containing thin film of the present invention form a film having a film thickness on the order of several hundred nm to several μm with respect to a conventional substrate having a film thickness of several tens of nm. Therefore, for example, the mold life when used as a mold release agent for precision resin molding is several times longer.

It is a figure which shows an example of the film-forming apparatus. It is a figure which shows another example of the film-forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Film-forming apparatus 2 Vacuum container 3 Exhaust apparatus 4 Vacuum deposition target 5 Ion beam sputtering target 6 Ion gun 7 Crucible 8 Base material 9 Film thickness meter 10 Gas introduction apparatus

Claims (9)

  A fluorine-containing thin film formed on a substrate surface, wherein the fluorine-containing thin film is formed by simultaneously depositing a fluorine-containing organic material that can be deposited on the substrate surface by a vapor deposition method and a material that can be deposited by an ion beam sputtering method. A fluorine-containing thin film characterized by that. The fluorine-containing organic material is a perfluoro polymer, and the polymer includes at least one double bond or triple bond carbon, —COOH group, or —Si (OR) ₃ group (R represents an alkyl group). The fluorine-containing thin film according to claim 1, wherein the fluorine-containing thin film is contained in a molecule.   2. The fluorine-containing thin film according to claim 1, wherein the fluorine-containing organic substance is an amorphous perfluoro resin.   A method of manufacturing a substrate having a fluorine-containing thin film on a surface, the step of placing the substrate in a predetermined thin film forming apparatus, a fluorine-containing organic material by vapor deposition, and a non-fluorine-containing material by ion beam sputtering And a step of depositing on the surface of the substrate at the same time. A method for producing a substrate having a fluorine-containing thin film.   5. The method for producing a substrate having a fluorine-containing thin film according to claim 4, wherein the vapor deposition method is a vacuum vapor deposition method.   5. The method for producing a substrate having a fluorine-containing thin film according to claim 4, wherein a deposition rate by the vacuum evaporation method is 10 times or more a deposition rate by the ion beam sputtering method.   A fluorine-containing thin film formed on a substrate surface, wherein the fluorine-containing thin film is formed by depositing at least one fluorine-containing organic compound on the substrate surface while performing argon sputter etching. Thin film.   8. The fluorine-containing thin film according to claim 7, wherein a material for improving adhesion to the substrate is deposited simultaneously with the argon sputter etching.   A method of manufacturing a base material having a fluorine-containing thin film on a surface, the step of disposing the base material in a predetermined thin film forming apparatus, and the base material by vapor deposition while performing argon sputter etching of the fluorine-containing organic material. And a step of depositing on the surface. A method for producing a substrate having a fluorine-containing thin film.

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