JP2003096569A - Thin film depositing method, base material, and thin film depositing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin film depositing method in which a dense thin film of excellent quality can be deposited without being influenced by the thickness of a base material, and a thin film depositing device can be operated for a long time. SOLUTION: In the thin film depositing method in which the base material is disposed between electrodes facing each other, the mixture gas including a reactive gas is put in a plasma state by supplying the power between the facing electrodes under the atmospheric pressure or the pressure in the vicinity of the atmospheric pressure, and a thin film is deposited on a surface of the base material, the voltage of the frequency >=1 kHz and <15 kHz is applied to one electrode out of the electrodes facing each other, and the voltage of the frequency >100 kHz and <=150 MHz is applied to the other electrode. The base material is disposed in an almost contact manner with the other electrode on the higher frequency side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming method and a thin film forming apparatus for forming a thin film on a surface of a substrate or an optical element by converting a reactive gas into plasma under atmospheric pressure or a pressure near the atmospheric pressure, and these thin film forming devices. The present invention relates to a substrate having a thin film formed by a method and a thin film forming apparatus.

[0002]

2. Description of the Related Art In recent years, various high-performance films such as conductive films, antireflection films and antistatic films have been used in liquid crystal display devices, semiconductor devices, optical devices and the like. As a method for forming these high-performance films, a method of discharging under atmospheric pressure or a pressure in the vicinity of atmospheric pressure, plasma-exciting a reactive gas, and forming a thin film on the surface of a base material or the like placed between electrodes is special. Kaihei 11-
133, 205, JP-A-2000-185362, JP-A-11-61406, and JP-A-2000-147209.
No. 2000-121804 (hereinafter, referred to as atmospheric pressure plasma method). In the atmospheric pressure plasma methods disclosed in these publications, a voltage having a frequency of 0.5 to 100 kHz is applied between opposing electrodes so that the electric field strength is 1 to 100 V / cm, and discharge plasma is generated. It is to generate.

[0003]

When the frequency of the voltage applied in the atmospheric pressure plasma method is increased, the plasma density is increased, a dense and good quality film is obtained, and the film formation rate is also improved. However, if the frequency is increased, it is necessary to narrow the electrode interval in order to stabilize the discharge state. Moreover,
Compared with the vacuum plasma method, the atmospheric pressure plasma method needs to make the interval between the facing electrodes considerably narrow in order to obtain a stable discharge state. Therefore, in the atmospheric pressure plasma method, if the frequency is increased, the electrode interval becomes very narrow, a thick base material cannot be inserted between the electrodes, and the base material on which the thin film is formed is limited. In addition to the atmospheric pressure plasma method, plasma CVD (chemical vapor depos
ition), plasma discharge is generated between the electrodes facing each other, so that there is a problem that a film is formed not only on the substrate but also on the electrode surface. In particular, the atmospheric pressure plasma method has a higher film forming rate than vacuum plasma, and therefore the electrodes are easily formed into a film in a short time and are easily contaminated. Moreover, as described above, when the distance between the electrodes is narrowed, the influence is large, and due to abnormal discharge due to contamination of the electrodes or clogging of the flow path of the reaction gas,
There was a problem that it could not operate for a long time.

In view of the above problems, an object of the present invention is to provide a thin film forming method which can form a dense and high quality thin film without being restricted by the thickness of the base material and which can prevent electrode contamination as much as possible and can be operated for a long time. , To provide a thin film forming apparatus. A further object of the present invention is to provide a substrate having a thin film formed by using the thin film forming method and thin film forming apparatus of the present invention.

[0005]

As described above, there is a reciprocal relationship between the distance between electrodes and the frequency of voltage, and the inventors of the present invention have diligently studied this point. That is, as the frequency is increased, the discharge is localized, so that it is necessary to make the electrode interval narrower and uniform. In particular, in the frequency range over 100 kHz, the electrode interval needs to be less than 2 mm, preferably 1.5 mm or less. On the other hand, if the frequency is lowered, the electrode interval can be set relatively wide, especially at 15 kHz.
If it is less than this, the electrode interval can be set to be as large as several tens of mm.
However, when the frequency is lowered, the film forming speed and the film quality decrease. Therefore, by applying voltages of different frequencies to each of the electrodes facing each other, the electrode interval can be set wide while applying a voltage in the high frequency range, and a high plasma density biased to the high frequency side can be obtained. From that,
It has been found that when a base material is placed in contact with the high frequency electrode side, a dense and good quality film can be obtained and a high film formation rate can be obtained.
Moreover, it has been found that the electrodes on the low frequency side can also be greatly suppressed from being contaminated due to film formation.

That is, the invention according to claim 1 of the present invention is
Under atmospheric pressure or a pressure close to atmospheric pressure, electric power is supplied to both electrodes facing each other to discharge the reactive gas into a plasma state, and the substrate is exposed to the reactive gas in the plasma state, whereby In the thin film forming method of forming a thin film on the surface of a material, one electrode of the opposing electrodes is 1 k
It is characterized in that a voltage having a frequency of not less than Hz and less than 15 kHz is applied, and a voltage having a frequency of more than 100 kHz and 150 MHz or less is applied to the other electrode. According to a second aspect of the present invention, in the thin film forming method according to the first aspect, the base material is provided between opposing electrodes and in a state of being substantially in contact with the other electrode. .

The invention according to claim 3 is the method for forming a thin film according to claim 1 or 2, characterized in that the interval between the electrodes facing each other is 2 mm or more and 30 mm or less.
The invention according to claim 4 is the thin film forming method according to any one of claims 1 to 3, wherein the frequency of the voltage applied to the one electrode is 10 kHz or less. The invention according to claim 5 is the thin film forming method according to any one of claims 1 to 3, characterized in that the frequency of the voltage applied to the one electrode is 5 kHz or less. The invention described in claim 6 is the thin film forming method according to any one of claims 1 to 5, characterized in that the frequency of the voltage applied to the other electrode is 200 kHz or more. The invention according to claim 7 is the method for forming a thin film according to any one of claims 1 to 6, wherein the electric power is 1
It is characterized in that it is W / cm ² or more and 50 W / cm ² or less.

The invention according to claim 8 is the method for forming a thin film according to any one of claims 1 to 7, wherein the reactive gas is an organic fluorine compound, an organic silicon compound, an organic titanium compound, an organic tin compound, an organic compound. It is characterized by containing any one of a zinc compound, an organic indium compound, an organic aluminum compound, an organic copper compound and an organic silver compound. The invention according to claim 9 is the method for forming a thin film according to any one of claims 1 to 8, wherein a mixed gas containing the reactive gas and an inert gas is introduced between opposing electrodes to form the mixed gas. Is an inert gas in a volume ratio of 90.0 to 99.9%
It is characterized by containing.

The invention described in claim 10 is the invention as claimed in claims 1 to 9.
A substrate having a thin film formed by the method for forming a thin film according to any one of 1. The invention according to claim 11 is the base material according to claim 10, wherein the thin film is
It is characterized by being an antireflection film. A twelfth aspect of the present invention is a substrate, wherein a plurality of thin films are laminated on the surface, and at least one layer is formed by the thin film forming method according to any one of the first to ninth aspects. Claim 1
In the invention described in 3, the antireflection film composed of a plurality of thin films is formed on the surface, and at least one of the plurality of thin films is
It is a high-refractive-index layer formed by the thin film formation method in any one of Claims 1-9, and that refractive index is 2.0 or more, It is a base material characterized by the above-mentioned. The invention according to claim 14 is the base material according to claim 13, wherein the high refractive index layer is
It is characterized by being made of TiO ₂ . According to a fifteenth aspect of the present invention, the base material according to any one of the tenth to fourteenth aspects is in the form of a film. Claim 1
The invention described in 6 is characterized in that the substrate according to any one of claims 10 to 14 is used as an optical element.

According to a seventeenth aspect of the present invention, there is provided an electrode which faces each other, a base material is disposed between the electrodes which face each other, and a reactive gas which is a raw material for forming a thin film can be introduced.
Under atmospheric pressure or a pressure near atmospheric pressure, a voltage with a frequency of 1 kHz or more and less than 15 kHz is applied to one of the facing electrodes, and a voltage with a frequency of more than 100 kHz and 150 MHz or less is applied to the other electrode. Then, a thin film is formed on the surface of the substrate by exposing the substrate to the reactive gas in the plasma state by exposing the substrate to the reactive gas in the plasma state. Claim 1
The invention according to claim 8 is the thin film forming apparatus according to claim 17, wherein the interval between the opposing electrodes is 2 mm or more and 30 mm.
It is characterized by the following.

The present invention will be described in detail below. In the thin film forming method of the present invention, under atmospheric pressure or a pressure near atmospheric pressure, electric power is supplied between opposing electrodes to bring the reactive gas into a plasma state, and the substrate is exposed to the reactive gas in the plasma state. Thus, a thin film is formed on the surface of the base material.
At this time, a voltage having a frequency of 1 kHz or more and less than 15 kHz is applied to one electrode (low frequency side electrode) of the facing electrodes, and 100 kHz is applied to the other electrode (high frequency side electrode).
And a voltage with a frequency of 150 MHz or less is applied. When voltages having different frequencies are applied to the two electrodes facing each other in this way, a plasma density distribution is generated between the electrodes, and the plasma density becomes higher than that of the high frequency side electrode. Therefore, if the base material is provided in a state of being substantially in contact with the high frequency side electrode, a dense and good quality thin film can be formed at a high film forming rate. Moreover, since the discharge is not localized as compared with the case where a high frequency voltage is applied to both of the electrodes facing each other, the distance between the electrodes can be increased to some extent or more. Specifically, the distance between the opposing electrodes is 2 mm or more and 30 mm
Can be set to:

In the present invention, the upper limit value of the frequency of the voltage applied to the low frequency side electrode is more preferably 10 kHz or less, further preferably 5 kHz or less.

The lower limit value of the voltage applied to the high frequency side electrode is preferably 200 kHz or more.

The lower limit of the power supplied between the electrodes is 1 W / c
m ² or more, and the upper limit value is 50 W / cm ² or less. The voltage application area at the electrodes refers to the area in the range where discharge occurs. The voltage applied to both electrodes may be an intermittent pulse wave or a continuous sine wave.

In the thin film forming method of the present invention, a mixed gas containing a reactive gas and an inert gas, which are materials for the thin film, is used. The reactive gas preferably contains any one of an organic fluorine compound, an organic silicon compound, an organic titanium compound, an organic tin compound, an organic zinc compound, an organic indium compound, an organic aluminum compound, an organic copper compound and an organic silver compound. . Among these, the organometallic compounds other than the organofluorine compound may be a metal hydrogen compound, a metal halogen compound, and a metal alkoxide. The reactive gas is preferably contained in an amount of 0.01 to 10% by volume based on the whole mixed gas. Further, when these reactive gas organic compounds are gases at normal temperature and pressure, they can be used as they are as constituents of the mixed gas. But,
When it is a liquid or a solid at room temperature and atmospheric pressure, it may be used after being vaporized by a method such as heating, decompression, or irradiation with ultrasonic waves, or may be dissolved in an appropriate solvent before use. The diluted solvent at this time is decomposed into a molecular form and an atomic form during the plasma discharge treatment, so that the influence on the thin film formation on the substrate, the thin film composition, etc. can be almost ignored.

Specifically, as reactive gas, zinc acetylacetonate, triethylindium, trimethylindium, diethylzinc, dimethylzinc, tetraethyltin, tetramethyltin, di-n-butyltin diacetate, tetrabutyltin, tetraoctyl. A conductive film, an antistatic film, an antireflection film, or the like can be formed using a reactive gas containing at least one organometallic compound selected from tin or the like.

For the purpose of forming a water-repellent film, propylene hexafluoride (CF ₃ CFC) is used as an organic fluorine compound.
F ₂ ), octafluorocyclobutane (C ₄ F ₈ ) can be used. Further, when forming the antireflection film from an organic fluorine compound, a fluorocarbon gas or a fluorohydrocarbon is preferable, and specifically, the fluorocarbon gas is tetrafluoromethane, tetrafluoroethylene, or hexafluoride. Examples include propylene and cyclobutane octafluoride. Examples of the fluorohydrocarbon gas include methane difluoride, tetrafluoroethane, propylene tetrafluoride, propylene trifluoride, and the like. Further, trichloromethane trifluoride, monochlorodifluoromethane, 2
It is possible to use halides of fluorohydrocarbon compounds such as tetrafluorochlorobutane chloride and fluorine-substituted compounds of organic compounds such as alcohols, acids and ketones.

Further, by using a reactive gas containing a silicon compound or a titanium compound, the low refractive index layer or the high refractive index layer of the antireflection film can be provided. Examples of the silicon compound described above include dimethylsilane,
Organometallic compounds such as tetramethylsilane, metal hydrogen compounds such as monosilane and disilane, metal halogen compounds such as dichloride silane and trichloride silane, alkoxysilanes such as tetramethoxysilane, tetraethoxysilane and dimethyldiethoxysilane, organosilane Etc. can be used.

Examples of the titanium compound described above include organometallic compounds such as tetradimethylaminotitanium, metal hydrogen compounds such as monotitanium and dititanium, metal halogen compounds such as titanium dichloride, titanium trichloride and titanium tetrachloride,
Tetraethoxy titanium, tetraisopropoxy titanium,
A metal alkoxide such as tetrabutoxytitanium can be used.

Further, the hydrogen gas content of 0.1 to 10% by volume in the mixed gas described above can remarkably improve the hardness of the thin film. Further, the reaction is promoted and the density is improved by containing 0.01 to 5% by volume of a component selected from oxygen, ozone, hydrogen peroxide, carbon dioxide, carbon monoxide, hydrogen and nitrogen in the mixed gas. Can form a high quality thin film.

As the inert gas contained in the mixed gas,
For example, helium, neon, argon, krypton, xenon, xenon, radon and the like can be used, and helium and argon are particularly preferable. The volume ratio of the inert gas in the mixed gas is preferably 90.0 to 99.9%.

The base material used in the present invention is not particularly limited as long as it has a shape capable of forming a thin film on its surface, such as a film shape, a fiber shape and a bulk shape.
Further, although the material thereof is not limited at all, the thin film forming method of the present invention is an atmospheric pressure plasma method and is a film forming under glow discharge at low temperature, so that a resin can be particularly preferably used. Examples of the use of the base material include semiconductor elements and optical elements. Here, the optical element is, for example, a lens, an optical fiber, and other optical components in a liquid crystal display device or an optical product.

An electrode film, a dielectric protective film, a semiconductor film, a transparent conductive film, an electrochromic film, a fluorescent film, a superconducting film, a dielectric film and a solar cell are formed on the surface of these substrates by the thin film forming method of the present invention. Film, antireflection film, abrasion resistant film, optical interference film, reflection film, antistatic film, conductive film, antifouling film, hard coat film, undercoat film, barrier film, electromagnetic wave shielding film, infrared shielding film, ultraviolet absorption Film, lubricating film, shape memory film, magnetic recording film,
Various thin films such as a light emitting device film, a biocompatible film, a corrosion resistant film, a catalyst film, a gas sensor film, and a decorative film can be formed.
The thickness of the thin film formed is 0.1 nm to 1000
It is in the range of nm.

In particular, the thin film of the present invention is useful as an antireflection film. For example, when the thin film according to the present invention is an antireflection film, the substrate is preferably a film-like cellulose ester such as cellulose triacetate, polyester, polycarbonate, polystyrene, and further, gelatin, polyvinyl alcohol (PVA), acrylic on these. It is possible to use a resin, a polyester resin, a cellulosic resin or the like coated. Further, as these substrates, those having a main support coated with an antiglare layer or a clear hard coat layer, or a back coat layer and an antistatic layer coated thereon can be used.

Specific examples of the support which mainly comprises the above-mentioned base material include polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyethylene films, polypropylene films, cellophane, cellulose diacetate films, and cellulose acetate butyrate. Film, cellulose acetate propionate film, cellulose acetate phthalate film, film made of cellulose ester such as cellulose triacetate, cellulose nitrate or derivatives thereof, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic Polystyrene film, polycarbonate film, norbornene resin film, polymethyl Embedded film, polyetherketone film, polyimide film, polyethersulfone film, polysulfone film, polyetherketone imide film, polyamide film, fluororesin film, nylon film, polymethylmethacrylate film, acrylic film or polyarylate film. Can be mentioned. These materials may be used alone or in an appropriate mixture.

Among the thin films for the antireflection film formed by the thin film forming method according to the present invention, for example, TiO ₂ is 2.
A very high refractive index of 0 or more can be obtained, and such a high refractive index is also useful as an antireflection film.

1 to 7 show a thin film forming apparatus for realizing the thin film forming method of the present invention and electrodes provided in the apparatus.
In each figure, reference numeral F is a long film made of a polymer or the like, which is an example of the substrate in the present invention. Before the film F is subjected to the thin film forming process, it is preferable that the film F is subjected to a static elimination process for preventing electrification or a dust removing process. Figure 1
The thin film forming apparatus 1 shown in FIG. 2 is provided with flat electrodes 3 and 4 facing each other with a predetermined space. The electrodes 3 and 4 are
High frequency power supplies 5 and 6 are connected to each, so that voltages of different frequencies can be applied, and 1 kH is applied to the electrode 3.
Voltage of z or more and less than 15 kHz, 100 at the electrode 4
A voltage having a frequency of more than kHz and 150 MHz or less is applied. In addition, assuming that a voltage having such a frequency is applied, the distance between the electrodes 3 and 4 is 2 mm or more and 30 mm or more.
It is set below.

The electrodes 3 and 4 are mainly made of metal, but a base material made of metal is coated with a dielectric such as an inorganic material. As the metal used here, metals such as silver, platinum, stainless steel, aluminum and iron can be used, but stainless steel is preferable from the viewpoint of easy processing. Also,
As the dielectric, a silicate glass, a borate glass, a phosphate glass, a germanate glass, a tellurite glass, an aluminate glass, a vanadate glass, etc. are subjected to a lining treatment. Can be provided. Among these, borate glass is easy to process. It is also preferable to use a sinterable ceramic obtained by sintering a highly heat-resistant ceramic having high airtightness. Examples of the material of the sinterable ceramics include alumina type, zirconia type, silicon nitride type,
It is a silicon carbide based ceramics.

Processing chamber 2 in which film F is formed into a thin film
The internal pressure is not particularly adjusted, and is maintained at or near atmospheric pressure even after the introduction of the mixed gas. As shown in FIG. 1, in the thin film forming apparatus 1, a preparatory chamber 10 or 11 continuous with the processing chamber 2 is provided on the inlet 1a side, and a preparatory chamber 12 continuous with the processing chamber 2 is provided on the outlet 1b side. Has been. When the thin film is formed, the processing chamber 2 has a pressure higher than the internal pressure of the preliminary chambers 10, 11 and 12.
Adjust so that the inside is higher. The pressure difference thus generated prevents external air from being mixed in and promotes formation of plasma of the reaction gas in the gas. As the adjusting method, for example, a suction fan or a vacuum pump may be used. The spare chamber is not essential in the device of the present invention, and the number and size of the spare chamber can be changed as appropriate. As described above, a nip roll is provided between the inlet 1a, the preliminary chamber 10 and the preliminary chamber 11, and the preliminary chamber 11 and the processing chamber 2 for the purpose of controlling the pressure and partitioning the film F and conveying the film F. 7 and 7, nip rolls 8 and 8 are provided between the processing chamber 2 and the preliminary chamber 12 and at the outlet 1b. The film F carried in through the entrance 1a of the thin film forming apparatus 1 is plasma-treated while being in contact with the electrode 4, and carried out through the exit 1b.

The processing chamber 2 has supply ports 9 and 9 for introducing the mixed gas into the processing chamber 2 and exhaust ports 10 and 10 for discharging the gas. When a thin film is formed on the surface of the film F using the thin film forming apparatus 1, the film F is first pressed by the nip rolls 7 and is brought into the processing chamber 2 in a state of being in contact with the electrode 4. Air inlets 9 and 9 are provided in the processing chamber 2.
There is the introduced atmospheric pressure or mixed gas near the atmospheric pressure. A voltage having a predetermined frequency is applied to the electrodes 3 and 4 from the high frequency power sources 5 and 6 to generate discharge plasma, and a thin film derived from the reaction gas in the mixed gas is formed on the surface of the film F, and then the film F is exited. Carry out from 1b.

FIG. 2 shows a thin film forming apparatus 20 according to the present invention.
The schematic configuration of is shown. The thin film forming apparatus 20 uses a flat plate type electrode 22 as an electrode connected to the high frequency power source 23, and mounts a base material on the electrode 22. The base material to be formed into a thin film may be a film as shown in FIG. 1, but here, for example, a lens L having a large thickness is illustrated. On the other hand, as an electrode connected to the low frequency power source 24, the electrode 22
Square bar-shaped electrodes 21a and 21b are provided so as to face each other. In this case, the mixed gas is supplied to the electrodes 21a, 21b.
Supply from above and between the electrodes 21a and 21b.
The plasma state is set in the range of 2. Similar to the thin film forming apparatus 1, the electrodes 21a and 21b have a frequency of 1 kHz or more and 15 kHz or more.
A low frequency voltage of less than Hz and a high frequency voltage of more than 100 kHz and 150 MHz or less are applied to the electrode 22.
In addition, assuming that a voltage having such a frequency is applied, the vertical distance between the electrodes 21a and 21b and the electrode 22 is set to 2 mm or more and 30 mm or less.

The electrodes provided in the thin film forming apparatus according to the present invention may be roll type electrodes as shown in FIGS. In FIG. 3, a roll electrode 31 that is configured to be rotatable and a plurality of cylindrical fixed electrodes 32 that is fixed around the roll electrode 31 are provided in a processing container 37.
32 is shown. The roll electrode 31 shown in FIG. 4 is a hollow base material 31 having conductivity such as metal.
It is composed of a combination in which a is coated with an inorganic dielectric 31b by lining, or a combination in which a base material 31A is sprayed with ceramics and then covered with a dielectric material 31B which is sealed with an inorganic substance. Here, as the conductive base material 31a (31A) such as metal, any of metals such as silver, platinum, stainless steel, aluminum and iron can be used, but stainless steel is preferable because it is easy to process.

As the lining material for forming the dielectric 31b, silicate glass, borate glass, phosphate glass, germanate glass, tellurite glass, aluminate glass. , Vanadate glass and the like can be used, and among them, borate glass is preferable because it is easily processed. As the ceramic material used for thermal spraying, alumina, silicon nitride, etc. are preferably used. Among them, alumina is easy to process, so
More preferably used. In this case, for example, after spraying alumina ceramics, a sealing treatment is performed with a silicon compound using a sol-gel reaction. The roll electrode 31 is configured to be rotationally driven about the shaft portion 31c by a drive mechanism (not shown).

A plurality of fixed electrodes 32 (fixed electrode 4 in FIG. 5)
(Including 0 and 41) is formed by coating a metal, for example, a hollow stainless steel pipe with a dielectric material like the roll electrode 31. Further, the plurality of fixed electrodes 32 are electrically connected to each other so that voltages having the same frequency are collectively applied. In addition, by forming the roll electrode 31 and the fixed electrode 32 (40, 41) in the hollow,
It can be cooled with water during discharge.
The processing container 37 constituting the discharge device 30 is made of Pyrex (registered trademark) glass, but may be made of metal as long as it is insulated from the electrodes. For example, a polyimide resin or the like may be attached to the inner surface of an aluminum or stainless steel frame, and ceramics may be sprayed on the metal frame to provide insulation. Further, the processing container 37 is provided with an air supply port 35 for introducing the mixed gas and exhaust ports 36, 36 for discharging the processed gas so as to be openable and closable.

Film F which is a base material on which a thin film is formed
Near the left and right sides of the roll electrode 31, the nip roller 3
Roll electrode 3 pressed by 3, 33, 34
It is wrapped around the circumference of 1. Nip roller 33,
At the tip of 33, 34, a rotatable guide roller 38,
39 is attached. The film F is carried into the processing chamber 37a in the processing container 37 through the guide roller 38 and the nip rollers 33, 33 as the roll electrode 31 rotates, and is kept facing the fixed electrodes 32, 32. Of the arrow P.
It is designed to be carried out in the direction of.

The plurality of fixed electrodes surrounding the roll electrode 31 are
The fixed electrode 40 is not limited to that shown in FIG. 3 and may be a fixed electrode 40 having an elliptical cross section as shown in FIG. 5A, or a prismatic fixed electrode 41 as shown in FIG. 5B. Good. Figure 6
3 shows a discharge device 45 in which a plurality of prismatic fixed electrodes 41 are arranged around the roll electrode 31. In FIG.
The same members as those in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted.

FIG. 7 shows a thin film forming apparatus 50 according to the present invention including the discharge device 45 of FIG. Thin film forming apparatus 5
Reference numeral 0 includes a gas generator 51, a low frequency power source 52, a high frequency power source 53, an electrode cooling means 60, etc. in addition to the discharge device 45. The gas generator 51 is a means for supplying a predetermined amount of a mixed gas containing an inert gas and a reaction gas into the processing container 37, and is connected to the air supply port 35.
The low frequency power source 52 has a frequency of 1 kHz or more for the plurality of fixed electrodes 41.
Applying a voltage with a frequency of less than 5 kHz,
Applies a voltage having a frequency of more than 100 kHz and not more than 150 MHz to the roll electrode 31, both of which are connected to the ground G. Further, on the assumption that a voltage having such a frequency is applied, the distance between the roll electrode 31 and the fixed electrodes 41, 41 ...
Set to mm or less.

The electrode cooling means 60 is composed of a water tank 61, a pump 62, and a water passage 63 connected to the roll electrode 31 and the fixed electrodes 41, 41 ... During the discharge, the pump 62 is appropriately operated to cause the water in the water tank 61 to flow to the roll electrode 31 and the plurality of fixed electrodes 41 to cool these electrodes. The film F carried into the processing device 37 is transferred from the roll-shaped film roll FF to the roller 6
It is sent toward the guide roller 38 via 5, 65, 65.

When forming a thin film in the thin film forming apparatus 50, the roll electrode 31 and a plurality of fixed electrodes 41 are arranged at predetermined positions in the processing container 37, and the flow rate of the mixed gas generated by the gas generator 51 is controlled. And is supplied into the processing container 37 through the air supply port 35. The inside of the processing container 37 is filled with the mixed gas and appropriately discharged through the exhaust port 36. Next, the low frequency power source 52,
The roll electrode 31, electrodes 41, 41 are driven by the high frequency power source 53.
... A voltage having a predetermined frequency is applied to each to generate discharge plasma. Here, the film F is supplied from the roll-shaped film roll FF, and the roll electrodes 31 are provided between the electrodes in the processing container 37 by the guide rollers 38, 39 and the like.
Transport with one side in contact with the peripheral surface. The film F is subjected to discharge treatment, that is, a thin film is formed on the surface thereof by discharge plasma during transportation, and then is discharged from the processing container 37. Here, the film F is subjected to the electric discharge treatment only on the surface not in contact with the roll electrode 31.

The substrate having a thin film according to the present invention may have a plurality of thin films laminated on the surface thereof, as shown in FIG. In this case, each thin film may be formed by the thin film forming method of the present invention, or only a part thereof may be formed by the method of the present invention. In FIG. 8, SnO ₂ films 72, T are formed on the surface of a film-shaped substrate 71 by the thin film forming method of the present invention.
The iO ₂ film 73 and the SiO ₂ film 74 are sequentially formed. The SnO ₂ film 72 has a medium refractive index (about 1.75), Ti
The O ₂ film 73 is formed with a high refractive index (2.0 or more), and the SiO ₂ film 74 is formed with a low refractive index (about 1.45). By adopting such a laminated structure, a sufficient antireflection function is exhibited. be able to.

[0041]

EXAMPLES The present invention will be described below with reference to specific examples, but the present invention is not limited to these examples.

<Example 1: Observation of discharge state> Production of Substrate A substrate film F1 having a cellulose ester film as a support was produced according to the method described below.

(1) Preparation of Dope G (Preparation of Silicon Oxide Dispersion F) Aerosil 200V (manufactured by Nippon Aerosil Co., Ltd.) 1 kg Ethanol 9 kg After stirring and mixing the above materials with a dissolver for 30 minutes, a Manton-Gaulin type high-pressure dispersion apparatus Was used for dispersion.

(Preparation of Addition Liquid E) Cellulose triacetate (acetyl substitution degree: 2.88) 6 kg Methylene chloride 140 kg The above materials were placed in a closed container, heated and stirred,
It was completely dissolved and filtered. To this, 10 kg of the above-mentioned silicon oxide dispersion liquid F was added with stirring, and after stirring for another 30 minutes, it was filtered to prepare an addition liquid E.

(Preparation of Dope Stock Solution G) Methylene chloride 440 kg Ethanol 35 kg Triacetyl cellulose (acetyl substitution degree: 2.88) 100 kg Triphenyl phosphate 9 kg Ethylphthalylethyl glycolate 4 kg Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 0 .4 kg TINUVIN 109 (manufactured by Ciba Specialty Chemicals) 0.9 kg TINUVIN 171 (manufactured by Ciba Specialty Chemicals) 0.9 kg Solvent is charged into a closed container, the above materials are charged with stirring, and heating and stirring are completed. It was dissolved and mixed in. After lowering the temperature of the obtained mixed liquid until it reaches a certain degree of viscosity and allowing it to stand overnight, after performing defoaming operations such as applying ultrasonic waves,
The solution was Azumi Filter Paper No. manufactured by Azumi Filter Paper Co., Ltd. Filtered using 244. Furthermore, the above-mentioned additive liquid E per 100 kg of solution
Was added at a rate of 2 kg, sufficiently mixed with an in-line mixer (Toray static type in-tube mixer Hi-Mixer, SWJ), and filtered to prepare a dope G.

The substitution degree of the cellulose ester used in the preparation of the above-mentioned dope G was determined according to the method specified in ASTM-D817-96.

(2) Production of Base Film (Production of Cellulose Ester Film) Using Dope G prepared above, a cellulose ester film was produced as follows. After filtering the dope G, the dope G was uniformly cast on a stainless band support at 30 ° C. at a temperature of 35 ° C. using a belt casting device. afterwards,
After drying to a peelable range, the web was peeled from the stainless band support. At this time, the residual solvent amount of the web was 35%.

After peeling from the stainless band support,
After drying at 115 ° C while holding the film in the width direction, the width holding is released, and the drying is completed in the drying zone of 120 ° C while the roll is conveyed.
A cellulose ester film having a thickness of 80 μm was produced by performing a knurling process of μm. Film width is 130
The winding length was 0 mm and the winding length was 1500 m.

The cellulose ester film obtained above was evaluated for water retention by the following method.
Cut the sample to a size of 10 cm x 10 cm,
After the mass (a) was measured after being left in an atmosphere of 55% RH for 24 hours, it was left under conditions of 80 ° C. and 90% RH for 48 hours. Lightly wipe the surface of the sample after treatment, 23 ℃, 55
The mass (b) after standing for 1 day at% RH was measured. And
As the holding property, {(ba) / a} × 100 was calculated.
As a result, the required retention was 5.0%.

(Production of Base Film F1) Using the cellulose ester film obtained above, a base film F1 was produced as follows. A coating composition A described below was applied to a wet film thickness on the surface a (the surface opposite to the side in contact with the belt support during casting (the surface b)) of the cellulose ester film produced by the above method. It was extrusion-coated to have a thickness of 13 μm and dried at a drying temperature of 80 ° C. to form a back coat layer. Further, the following coating composition B was extrusion-coated on the opposite side (b side) so that the wet film thickness was 13 μm, and then dried in a drying section set at 80 ° C., and then irradiated with ultraviolet rays at 120 mJ / cm ^2. Then, a clear hard coat layer having a dry film thickness of 4 μm and a center line surface roughness (Ra) of 15 nm was provided.

The compositions of the coating compositions A and B used for preparing the above-mentioned base film F1 are shown below.

[0052]   Coating composition A (backcoat layer coating composition)     Acetone 30 parts by mass     45 parts by mass of ethyl acetate     Isopropyl alcohol 10 parts by mass     Diacetyl cellulose 0.5 part by mass     Ultrafine silica 2% acetone dispersion (Aerosil 200V: Nippon Aerosil (Manufactured by Co., Ltd.) 0.1 parts by mass   Coating composition B (clear hard coat layer coating composition)     Dipentaerythritol hexaacrylate monomer 60 parts by mass     Dipentaerythritol hexaacrylate dimer 20 parts by mass     Dipentaerythritol hexaacrylate trimer or more components                                                         20 parts by mass     Dimethoxybenzophenone photoinitiator 4 parts by mass     50 parts by mass of ethyl acetate     Methyl ethyl ketone 50 parts by mass     Isopropyl alcohol 50 parts by mass

2. Thin Film Formation and Evaluation by Atmospheric Pressure Plasma Method Next, a thin film forming process was performed by the thin film forming apparatus 1 shown in FIG. In this case, the electrodes 3 and 4 each have a stainless jacket specification having a cooling function by cooling water,
The temperature was controlled by cooling water during discharge. The electrodes 3 and 4 were prepared by spraying ceramics and coating them with a dielectric having a thickness of 1 mm. The distance between electrodes 3 and 4 is 7
It was set to mm. As the base material, the base material film F1 produced above was used and set so that a thin film was formed on the clear hard coat layer. The following were used as the mixed gas. Inert gas: Argon Reaction gas: Hydrogen gas (1% for Argon) Reaction gas: Tetraisopropoxy titanium vapor (0.1% for Argon) (Evaporation into Argon gas by Lintec vaporizer) Discharge density : 20 W / cm ² (total of low frequency power supply and high frequency power supply)

As the low frequency power source and the high frequency power source, a high frequency power source (3 kHz) manufactured by Shinko Denki, a high frequency power source (5 kHz) manufactured by Shinko Denki, a high frequency power source (15 kHz) manufactured by Kasuga Denki,
Shinko Electric high frequency power supply (50 kHz), Heiden Institute impulse high frequency power supply (use in continuous mode 100 kHz
z), high frequency power source made by Pearl Industry (200 kHz), high frequency power source made by Pearl Industry (800 kHz), high frequency power source made by Pearl Industry (2 MHz), high frequency power source made by Pearl Industry (1
3.56MHz, Pearl Industrial high frequency power supply (150M
Hz) was used.

With the frequency combinations shown in Table 1, the mixed gas was put into a plasma state, and Ti was formed on the surface of the base film F1.
An O ₂ film was formed, and the discharge state at that time was evaluated. In addition, as a comparative example, the case where a voltage having a frequency outside the range of the present invention is applied is also shown.

[Table 1] As can be seen from Table 1, with the combination of frequencies according to the present invention, it was found that stable discharge is achieved even if the electrode interval is set to 7 mm.

Example 2 Measurement of Refractive Index Here, the thin film forming apparatus 50 shown in FIG. 7 was used for the thin film forming process. In this case, as the roll electrode 31 and the plurality of electrodes 41, a base material made of stainless steel was ceramic-sprayed and coated with a dielectric. Regarding the roll electrode 31, the diameter of the stainless base material is 200φ, and the thickness of the dielectric is about 1 mm.
Is. The electrode interval was set to 10 mm. All electrodes were cooled with cooling water and discharged while continuing heat exchange. The same power source, base material, and mixed gas as in Example 1 were used.

With the frequency combinations shown in Table 2, the mixed gas was put into a plasma state, a TiO ₂ film was formed on the clear hard coat layer of the base film F1, and the refractive index of the formed thin film was measured. It is also shown. Further, as a comparative example, the case where a voltage having a frequency outside the range of the present invention is applied is also shown. The refractive index was calculated as follows. The base film F1 on which a thin film is formed under the conditions of Table 2 is cut into a predetermined size, and the surface opposite to the surface on which the TiO ₂ thin film is formed is roughened with a file or the like. It was colored with a black spray so as not to reflect light. The TiO ₂ thin film on the surface of the sample thus produced was reflected by a spectrophotometer 1U-4000 (manufactured by Hitachi, Ltd.) at a wavelength (λ) in the range of 400 nm to 700 nm under the condition of being tilted 5 degrees from the state of regular reflection. The rate was measured. The film thickness was calculated optically from the value of λ / 4, and the refractive index was calculated based on this. Here, the value at a wavelength of 550 nm is adopted as the refractive index of the thin film and shown in Table 2.

[0058]

[Table 2]

If the film formation does not proceed satisfactorily because the discharge state is not stable, the resulting thin film will have fine holes as defects. In this case, since the refractive index is lowered when air enters the holes, it can be said that the higher the refractive index, the denser and better the film. As can be seen from Table 2, when the thin film was formed with the voltage of the frequency according to the present invention, a very high value of the refractive index of 2 or more was obtained, and it was found that a good film could be formed. Further, having such a high refractive index makes it suitable for use in optical products. On the other hand, when a thin film was formed with a voltage having a frequency different from that of the present invention, it was found that the refractive index was low and a good film could not be formed.

<Embodiment 3: Measurement of reflectance> Using the thin film forming apparatus 20 shown in FIG.
A TiO ₂ film (high refractive index layer) was formed on the surface of a disc-shaped plastic lens (lens L) having a thickness of 3 mm and a thickness of 3 mm, and a SiO ₂ film (low refractive index layer) was further formed thereon. The mixed gas used is as follows. (TiO ₂ film) Noble gas: Argon Reaction gas: Hydrogen gas (1% based on the total gas amount) Reaction gas: Tetraisopropoxy titanium vapor (0.1% based on the total gas amount) (In Lintec vaporizer After vaporization, mix in argon gas) (SiO ₂ film) Noble gas: Argon Reaction gas: Hydrogen gas (1% of total gas amount) Reaction gas: Tetraethoxysilane vapor (0.2% of total gas amount) (After vaporizing with a vaporizer manufactured by Lintec Co., Ltd., and mixed in argon gas) Further, a high frequency power source manufactured by Pearl Industry (13.56 MHz) is used as the high frequency power source 23, and Shinko Electric high frequency power source (5 kHz) as the low frequency power source 24 )It was used. The discharge density was 20 W / cm ² .

A TiO ₂ film laminated in order on the lens L,
The reflectance of the SiO ₂ film was measured using a spectrophotometer 1U-4000 (manufactured by Hitachi Ltd.). The reflectance was measured by irradiating the measurement light from an angle inclined 5 degrees from the vertical direction.
The measurement wavelength range is 400 nm to 700 nm, and the wavelength 55
The value at 0 nm was evaluated as the reflectance. As a result of measuring a plurality of samples, the reflectance is 0.2 for all the samples.
It became less than or equal to%. Therefore, it was found that by forming a thin film formed by the thin film forming method of the present invention on a lens, a lens having a low reflectance can be obtained.

<Example 4: Contamination test> Under the conditions of the high frequency voltage of 13.56 MHz and the low frequency voltage of 5 kHz in Example 2 (electrode interval 10 mm), the base film F1 was not installed for 24 hours continuously. It was discharged and the stain of the electrode was observed. On the other hand, as a comparative example, the electrode interval was made close to 1 mm under exactly the same conditions. As a result, the electrode spacing is 10 m
In the case of m, almost no stain on the electrodes could be confirmed. On the other hand, in the comparative example, a part of the electrode was clogged with a contaminant component derived from the reaction gas, and the discharge state could only be continued for 5 hours. From this, it was clarified that under the same plasma generation condition, the electrode contamination can be suppressed by widening the electrode interval.

[0063]

According to the thin film forming method and the thin film forming apparatus using the atmospheric pressure plasma method of the present invention, a low frequency voltage of 1 kHz or more and less than 15 kHz is applied to one of the facing electrodes, and the other electrode is applied. By applying a high frequency voltage of more than 100 kHz and 150 MHz or less to the electrode and combining the high frequency voltage and the low frequency voltage, it is possible to realize a stable discharge state while ensuring the electrode interval to some extent. Therefore, a dense and high-quality thin film can be formed without being restricted by the thickness of the base material. Moreover, by ensuring the electrode distance to some extent, it is possible to suppress the contamination of the electrodes and operate for a long time.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a thin film forming apparatus of the present invention.

FIG. 2 is a schematic view showing a second example of the thin film forming apparatus of the invention.

FIG. 3 is a diagram showing an example of a discharge device installed in the thin film forming apparatus of the present invention.

FIG. 4 is a perspective view of a roll electrode attached to the discharge device of FIG.

5 (a) and 5 (b) are perspective views showing another example of a fixed electrode attached to the discharge device of FIG.

FIG. 6 is a view showing the discharge device with the fixed electrode of FIG. 5 (b) attached.

FIG. 7 is a schematic view showing a third example of the thin film forming apparatus of the present invention provided with the discharge device of FIG.

FIG. 8 is a cross-sectional view showing a state in which thin films are laminated on a base material.

[Explanation of symbols]

1, 20, 50 Thin film forming equipment 3, 21a, 21b electrode (one electrode) 4, 22 electrodes (other electrode) 5, 24, 52 Low frequency power supply 6,23,53 high frequency power supply 32, 40, 41 Fixed electrode (one electrode) 31 Roll electrode (other electrode) 71 Base material F film (base material) L lens (base material)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshiro Toda             Konica Stock, 1 Sakura-cho, Hino City, Tokyo             In the company (72) Inventor Kiyoshi Oishi             Konica Stock, 1 Sakura-cho, Hino City, Tokyo             In the company (72) Inventor Wataru Mizuno             Konica Stock, 1 Sakura-cho, Hino City, Tokyo             In the company F term (reference) 2K009 AA02 BB24 BB28 CC03 CC26                       CC42 DD04                 4K030 AA04 AA06 AA09 AA11 AA16                       BA01 BA02 BA11 BA16 BA18                       BA21 BA29 BA46 BB12 CA07                       CA12 FA03 JA03 JA06 JA16                       JA18 KA15 LA01 LA11                 5F045 AA08 AB32 AB40 AC07 AC08                       AC09 AE29 AF07 BB09 DA64                       EB08 EE12 EE14 EH04 EH08                       EH14 EH19 EJ05 EJ09

Claims (18)

[Claims] 1. A reactive gas is brought into a plasma state by supplying electric power to both electrodes facing each other under atmospheric pressure or a pressure near the atmospheric pressure to expose a base material to the reactive gas in the plasma state. Accordingly, in the thin film forming method of forming a thin film on the surface of the base material, one of the facing electrodes has a frequency of 1 kHz or more and 15 kHz or more.
A voltage with a frequency of less than Hz is applied, and the other electrode has a voltage of 10
A thin film forming method comprising applying a voltage having a frequency of more than 0 kHz and 150 MHz or less. 2. The thin film forming method according to claim 1, wherein the base material is provided between opposing electrodes and in a state of being substantially in contact with the other electrode. 3. The distance between opposing electrodes is 2 mm or more and 30 m
The method for forming a thin film according to claim 1 or 2, wherein the thickness is m or less. 4. The frequency of the voltage applied to the one electrode is 10 kHz or less.
4. The method for forming a thin film as described in 3 above. 5. The frequency of the voltage applied to the one electrode is 5 kHz or less.
The method for forming a thin film according to any one of 1. 6. The frequency of the voltage applied to the other electrode is 200 kHz or more.
6. The thin film forming method according to any one of 5 to 5. 7. The power is 1 W / cm ² or more and 50 W / c.
thin film forming method according to any one of claims 1 to 6, characterized in that m ² or less. 8. The reactive gas is any of organic fluorine compounds, organic silicon compounds, organic titanium compounds, organic tin compounds, organic zinc compounds, organic indium compounds, organic aluminum compounds, organic copper compounds and organic silver compounds. The method for forming a thin film according to claim 1, wherein the thin film is contained. 9. A mixed gas containing the reactive gas and an inert gas is introduced between opposing electrodes, and the mixed gas is
The thin film forming method according to any one of claims 1 to 8, which contains an inert gas in a volume ratio of 90.0 to 99.9%. 10. A base material having a thin film formed by the thin film forming method according to claim 1. 11. The substrate according to claim 10, wherein the thin film is an antireflection film. 12. A substrate, wherein a plurality of thin films are laminated on the surface, and at least one layer is formed by the thin film forming method according to any one of claims 1 to 9. 13. An antireflection film comprising a plurality of thin films is formed on the surface, and at least one layer of the plurality of thin films is formed by the thin film forming method according to any one of claims 1 to 9 and the refraction thereof is performed. A base material which is a high refractive index layer having an index of 2.0 or more. 14. The base material according to claim 13, wherein the high refractive index layer is made of TiO ₂ . 15. The substrate according to claim 10, which is in the form of a film. 16. The substrate according to claim 10, which is used as an optical element. 17. A structure comprising: electrodes facing each other; a base material disposed between the electrodes facing each other; and a reactive gas which is a raw material for forming a thin film being introduced, wherein the pressure is at or near atmospheric pressure. Below, a voltage having a frequency of 1 kHz or more and less than 15 kHz is applied to one of the electrodes facing each other, and a voltage having a frequency of more than 100 kHz and 150 MHz or less is applied to the other electrode to make the reactive gas into a plasma state. And forming a thin film on the surface of the base material by exposing the base material to the reactive gas in the plasma state. 18. The thin film forming apparatus according to claim 17, wherein the interval between the opposing electrodes is 2 mm or more and 30 mm or less.