JP2000147207A - Production of functionally gradient material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously coat even a long-sized substrate with a functionally gradient thin film and to form the thin film at a high speed without requiring a high degree of vacuum by carrying out plasma discharge under a pressure close to atmospheric pressure. SOLUTION: Two different gases are introduced into the gap between opposite electrodes 3, 4 while continuously transferring a substrate 5 between the electrodes 3, 4 under a pressure close to atmospheric pressure. One of the gases is introduced from the substrate inlet side and the other from the substrate outlet side. Plasma discharge treatment is carried out by impressing voltage between the electrodes 3, 4 to form a thin film whose composition varies continuously in the thickness direction on the substrate 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a functionally gradient material.

[0002]

2. Description of the Related Art Functionally graded materials are materials based on a new concept, such as electric / magnetic, optical, chemical, biological / medical, aviation /
Application is desired in a wide field such as space. The functionally graded material is manufactured using a vapor phase synthesis method such as PVD or CVD. It is known that the functionally graded material is effective as a means for preventing cracks and improving the adhesion to a substrate. Therefore, in recent years, applications to new optical materials by continuously changing the refractive index have been reported.

[0003] With the spread of color displays,
A high resolution is required, and a multi-layer deposited film utilizing light interference or a film coated with a CVD film and provided with an antireflection function has been put to practical use. However, antireflection coatings made of these multi-layer coatings are currently applied only to a limited number of high-grade products due to their high formation costs.
The challenge is to obtain a high-performance antireflection film at low cost.

[0004] For example, a plasma C
In forming a hard coat layer by the VD method, a method of reducing the reflectance over a wide area by continuously lowering the refractive index at a portion in contact with the plastic substrate in the thickness direction (Japanese Unexamined Patent Application Publication No. No. 56002) has been proposed.

[0005]

However, the above-mentioned method requires a high degree of vacuum when forming a hard coat layer by a plasma CVD method, and in particular, cannot form a thin film continuously on a long product. was there. Further, when plasma discharge is performed near atmospheric pressure, damage to the substrate is large, so that it cannot be applied to the formation of a thin film on a substrate having low heat resistance.

The present invention solves the above-mentioned problems, and enables continuous coating of a functionally graded thin film even on a long base material, and does not require a high degree of vacuum, and performs plasma discharge near atmospheric pressure. It is an object of the present invention to provide a method for producing a functionally gradient material capable of forming a thin film at high speed.

[0007]

According to the present invention, there is provided a method for producing a functionally graded material, comprising the steps of: Different gases are introduced between the electrodes, one from the base material inlet side and the other from the base material outlet side, and a discharge plasma treatment is performed by applying a voltage between the electrodes. It forms a thin film that changes continuously in the direction.

In the present invention, the term “under a pressure near the atmospheric pressure” refers to
Refers to a pressure of 100 to 800 Torr. The pressure is preferably in the range of 700 to 780 Torr, which facilitates pressure adjustment and makes the apparatus simple.

The opposing electrodes used in the present invention include simple metals such as copper and aluminum, stainless steel, and the like.
Examples include alloys such as brass, and intermetallic compounds. It is preferable that the opposed electrodes have a structure in which the distance between the opposed electrodes is substantially constant in order to avoid occurrence of arc discharge due to electric field concentration. Examples of an electrode structure that satisfies this condition include a parallel plate type, a cylindrical opposed plate type, a spherical opposed plate type, a hyperboloid opposed plate type, and a coaxial cylindrical structure.

[0010] Further, it is usually carried out in a device in which a solid dielectric is provided on at least one of the opposing surfaces of the electrodes. In this case, the portion where the plasma is generated is located between the solid dielectric and the electrode when a solid dielectric is provided on one of the electrodes, and between the solid dielectrics when the solid dielectric is provided on both of the electrodes. The space between them.

Examples of the material of the solid dielectric include plastics such as polytetrafluoroethylene and polyethylene terephthalate, glass, metal oxides such as silicon dioxide, aluminum oxide, zirconium dioxide and titanium dioxide, and double oxides such as barium titanate. And the like.

The distance between the electrodes is determined by the thickness of the solid dielectric,
It is determined in consideration of the magnitude of the applied voltage, the purpose of utilizing the plasma, and the like, and is preferably 1 to 50 mm.
If it is less than 1 mm, it is not enough to place the electrodes at intervals. If it exceeds 50 mm, it is difficult to generate uniform discharge plasma.

The substrate used in the present invention includes:
Examples thereof include plastics such as polyethylene, polypropylene, polystyrene, polycarbonate, polyethylene terephthalate, polytetrafluoroethylene, and acrylic resin, glass, ceramic, and metal. Examples of the shape of the substrate include a plate shape and a film shape, but are not particularly limited thereto. According to the surface treatment method of the present invention, it is possible to easily cope with the treatment of substrates having various shapes.

In the present invention, two types of different gases are introduced between the electrodes, one from the base material inlet side and the other from the base material outlet side. , A first metal oxide film is laminated thereon,
The second metal oxide film is laminated by the gas introduced from the outlet side. Since the two gases are mixed with a concentration gradient between the electrodes, the resulting thin film has a continuously changing composition.

In forming the thin film, any treatment can be performed by selecting a gas (hereinafter, referred to as a reaction gas) for performing a discharge plasma treatment by applying a voltage between the electrodes.

When a thin film to be formed is made of a metal or a compound thereof, an organic metal compound, a metal hydride or a metal halide is used.

Examples of the metal include Al, As,
Bi, B, Ca, Cd, Cr, Co, Cu, Ga, G
e, Au, In, Ir, Hf, Fe, Pb, Li, N
a, Mg, Mn, Hg, Mo, Ni, P, Pt, Po,
Rh, Sb, Se, Si, Sn, Ta, Te, Ti,
Examples include metals such as V, W, Y, Zn, and Zr, which may be used alone or in combination of two or more.

When the metal is Si, for example, tetramethylsilane [Si (CH ₃ ) ₄ ], dimethylsilane [S
i (CH ₃ ) ₂ H ₂ ], tetraethylsilane [Si (C ₂ H ₅ )
₄ ] and the like; metal halide compounds such as silicon tetrafluoride (SiF ₄ ), silicon chloride (SiCl ₄ ) and silicon chloride (SiH ₂ Cl ₂ ); monosilane (SiH ₄ ), disilane (SiH ₃ ) SiH ₃ ), trisilane (SiH ₃ SiH ₂ Si)
H ₃ ) and other metal hydrogen compounds; tetramethoxysilane [Si
(OCH ₃ ) ₄ ], tetraethoxysilane [Si (OC
₂ H ₅ ) ₄ ], triethoxymethylsilane [SiCH ₃ (OC ₂
H ₅ )] and the like. These may be used alone or in combination of two or more.

When the metal is Ti, for example, tetramethyl titanium [Ti (CH ₃ ) ₄ ], dimethyl titanium [T
i (CH ₃ ) ₂ H ₂ ], tetraethyl titanium [Ti (C ₂ H ₅ )
_4] an organometallic compound such as; 4 silicon fluoride (TiF _4), 4 silicon tetrachloride (TiCl _4), metal halide compounds such as 2 silicon tetrachloride (TiH ₂ Cl _2); Mono titanium (TiH _4), Jichitan (TiH ₃ TiH ₃ ), trititanium (TiH ₃ TiH ₂ Ti)
H ₃₎ metal hydride such as; tetramethoxy titanium [Ti
(OCH ₃ ) ₄ ], tetraisopropoxy titanium [Ti (O
CH ₃ CHCH ₃ ) ₄ ]. These may be used alone or in combination of two or more. Among the above-mentioned metal-containing gases, in consideration of safety, it is preferable that there is no danger of ignition or explosion in the atmosphere, such as metal alkoxides and metal halides, at normal temperature and in the air. Thus, metal alkoxides are preferably used.

If the metal-containing gas is a gas, it can be introduced into the discharge space as it is. If it is liquid or solid, it can be introduced into the discharge space via a vaporizer.
By using such a processing gas, SiO ₂ , Ti
By forming a thin film of a metal oxide such as O ₂ or SnO ₂ , electrical and optical functions can be imparted to the substrate surface.

From the viewpoint of economy and safety, it is preferable to carry out the treatment in an atmosphere diluted with a diluent gas, rather than in the atmosphere of the reaction gas alone. Examples of the diluting gas include rare gases such as helium, neon, argon, and xenon, and nitrogen gas. These may be used alone or in combination of two or more. When a diluent gas is used, the ratio of the reaction gas is preferably 1 to 10% by volume. When a metal alkoxide is used as a reaction gas, it is preferable to add an oxygen gas in order to form a dense metal oxide thin film having few organic components. In this case, the oxygen gas is preferably at least 10% by volume of the metal alkoxide.

Further, by using a fluorine-containing compound gas as the above-mentioned reaction gas, a fluorine-containing polymer film can be formed on the surface of the substrate to lower the surface energy and obtain a water-repellent surface.

Further, by performing the treatment in an atmosphere of a monomer having a hydrophilic group and a polymerizable unsaturated bond in the molecule, a hydrophilic polymer film can be deposited.

As described above, a compound having more electrons is more advantageous as the atmospheric gas (reactive gas) in increasing the plasma density and performing high-speed processing. However, argon or nitrogen is preferred in that it is easily available and inexpensive.

From the viewpoint of economy and safety, it is preferable to perform the treatment in an atmosphere in which the above-mentioned reaction gas is diluted with an inert gas. Examples of the inert gas include rare gases such as helium gas, neon gas, argon gas, and xenon gas, and nitrogen gas. These may be used alone or in combination of two or more.

When a diluent gas is used, the ratio of the reaction gas is preferably 1 to 10% by volume.

As described above, a compound having more electrons is more advantageous as the atmospheric gas in increasing the plasma density and performing high-speed processing. Therefore, the most desirable choice in consideration of availability, economy, processing speed,
This is an atmosphere containing argon and / or nitrogen as a diluent gas.

In the present invention, it is preferable that the electric field applied between the electrodes is pulsed. By doing so, discharge is stopped before transition to arc discharge without being limited to a specific gas such as helium or ketone, and plasma processing can be performed.

When the electric field is pulsed, the voltage rise time is 40 ns to 100 μs and the electric field strength is 1 to 10 μs.
It is preferably 0 kV / cm.

The pulse voltage is preferably an impulse type. In this case, a positive voltage and a negative voltage may be alternately applied, or one of a positive voltage and a negative voltage may be applied.

Although the pulse voltage waveform in the present invention is not limited to the above-mentioned waveform, the shorter the rise time of the pulse, the more efficiently the ionization of the gas during the generation of the plasma.
If the rise time of the pulse exceeds 100 μs, the discharge state easily shifts to an arc and becomes unstable, so that a high-density plasma state due to a pulse electric field cannot be expected. Further, it is better that the rise time is short. However, there is a limit to a device that has an electric field intensity large enough to generate plasma at normal pressure and generates a short rise time electric field. It is difficult to achieve a pulsed electric field with a rise time of less than. More preferably, the rise time is 50 ns to 5 μs. Here, the rise time refers to a time during which the voltage change is continuously positive.

It is preferable that the fall time of the pulse electric field is also steep.
It is preferable that the time scale is less than μs. For example, in the power supply device used in the embodiment of the present invention, the rise time and the rise time can be set to the same time, although it differs depending on the pulse electric field generation technique.

Further, the modulation may be performed using pulses having different pulse waveforms, rise times, and frequencies.

The frequency of the pulse electric field is 0.5 kHz to 1
Preferably, it is 00 kHz. If the frequency is less than 0.5 kHz, the plasma density is low, so that it takes too much time for the treatment. If the frequency exceeds 100 kHz, arc discharge is likely to occur. More preferably, the frequency is 1 kHz or more. By applying such a high-frequency pulsed electric field, the processing speed can be greatly improved.

It is preferable that the pulse duration in the pulse electric field is 1 to 1000 μs. 1μ
s, the discharge becomes unstable, and
If it exceeds s, it is easy to shift to arc discharge. More preferably, it is 3 μs to 200 μs. Here, one pulse duration refers to a time during which a pulse is continuous in a pulse electric field composed of repetition of ON and OFF.

The above discharge is performed by applying a voltage.
Although the magnitude of the voltage is appropriately determined, in the present invention,
The electric field strength between the electrodes is set in a range of 1 to 100 kV / cm. If it is less than 1 kV / cm, it takes too much time for the treatment, and if it exceeds 100 kV / cm, arc discharge is likely to occur. In applying the pulse voltage, a direct current may be superimposed.

In a glow discharge under a pressure near the atmospheric pressure,
As shown below, it has been revealed by the present inventors that the discharge current density reflects the plasma density and is a value that affects the surface treatment effect, and the discharge current density between the electrodes has been described above. When the content is in the range of 0.2 to 300 mA / cm ² , uniform surface discharge plasma can be generated and good surface treatment can be performed. For details, refer to
As described in JP-A-154598.

(Function) In the method for producing a functionally gradient material of the present invention, two kinds of different gases are supplied between electrodes while continuously moving the base material between the opposing electrodes under a pressure near the atmospheric pressure. One is introduced from the base material inlet side and the other is introduced between the electrodes from the base material outlet side, and discharge plasma treatment is performed by applying a voltage between the electrodes, and the composition is continuously formed on the base material in the thickness direction. Since there is no stress concentration during film formation to form a thin film, it is possible to obtain a functionally graded material that has excellent adhesion between the substrate and the thin film and does not have a clear interface in the film itself. it can. In addition, since the treatment is performed under a pressure close to the atmospheric pressure, the treatment space does not need to be a completely closed system, and the substrate on which the thin film is formed can be continuously supplied, so that a long product can be obtained. Can also respond.

[0039]

Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of an apparatus for producing a functionally gradient material according to the present invention.

As shown in FIG. 1, the apparatus for producing a functionally graded material of the present invention is provided with opposed electrodes 3 and 4 in a container 2, and the upper electrode 3 is electrically connected to a pulse power supply 1. , The lower electrode 4 is grounded, and the upper electrode 3
A pulse voltage is applied between the first electrode and the lower electrode 4.

On the other hand, the base material 5 unwound from the winding roll 12 passes through the base material inlet 10, passes through the support roll 13, passes over the lower electrode 4, and is applied with a pulse voltage. After the processing is performed, it is wound up by the take-up roll 15 from the substrate outlet 11 via the support roll 14.

Further, one of the reaction gases is supplied from the reaction gas supply section 8 to the flow rate control section 110 and from the gas introduction section 6 to the space between the electrode 3 and the base material 5. The other reaction gas passes through the flow control unit 111 from the reaction gas supply unit 9,
The gas is supplied from the gas inlet 7 to the space between the electrode 3 and the substrate 5. In this case, one gas is sent in the same direction as the transport direction of the substrate, and the other gas is sent in the opposite direction to the transport direction of the substrate.

EXAMPLES The present invention will be described in more detail with reference to Examples. In the following embodiment, a semiconductor device (model “TO-247AD” manufactured by IXYS) is used as the pulse power supply 1.
A power supply manufactured by Heiden Laboratory Co., Ltd. was used.

In the apparatus shown in FIG. 1, an upper electrode 3 and a lower electrode 4 (made of SUS304, length 350 mm, width 15
A sprayed film of zirconium containing 8% by weight of yttrium oxide (relative dielectric constant 16, film pressure 500 μm) was tightly formed on each opposing surface (0 mm, thickness 20 mm) as a solid dielectric. Upper electrode 3 and lower electrode 4
Is 3 mm, and a 5 μm polyfunctional acrylic hard coat agent (Dainichi Seika Co., Ltd., product number “EXF-
37 ”) and a 80 μm-thick triacetyl cellulose having a film formed thereon was placed on the lower electrode 4.

Next, argon gas was supplied at 760 Torr.
And then diluted with 3SLM Ar gas so that the tetraisopropoxy titanium becomes 0.5%,
The reaction gas was supplied between the electrode 3 and the base material 5 from the reaction gas inlet 6.

On the other hand, tetraethoxysilane is diluted with Ar gas of 3 SLM so as to be 0.5% from the reaction gas supply unit 7 and supplied between the electrode 3 and the base material 5 from the reaction gas introduction unit 6. did.

The rising speed is 1 μs, the frequency is 8 kHz, and the applied voltage is ± 3 kV between the upper electrode 3 and the lower electrode 4.
Was applied from the pulse power supply 1 to generate discharge plasma.

As a result, a polyfunctional acrylic hard coat
A 2000 Å thin film was formed on the film. The thin film obtained
Was measured in the thickness direction by Auger electron spectroscopy.
It was shown to. From the surface to the substrate as shown in Table 2,
Continuous SiO_TwoFrom TiO _TwoIt has been changed to
Call

[0048]

The method for producing a functionally graded material of the present invention is constructed as described above, so that a Pu film having a gradually different composition in the thickness direction is continuously formed from the foil film surface to the substrate. Even a long base material can be coated with a functionally graded thin film continuously, and does not require a high degree of vacuum. By performing a plasma discharge near atmospheric pressure, a slant consisting of a base material with a thin film formed on the surface at high speed The functional material can be manufactured at a high rate of formation.

[0049]

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of an apparatus for producing a functionally gradient material according to the present invention.

FIG. 2 is a graph showing a composition change in a thickness direction of a functionally gradient material obtained in an example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pulse power supply 2 Container 3 Upper electrode body 4 Lower electrode body 5 Base material 6, 7 Reaction gas introduction part

Claims (1)

[Claims] 1. A method in which a substrate is continuously moved between opposing electrodes under a pressure close to atmospheric pressure, and two different gases are supplied between the electrodes, one from the substrate inlet side and the other from the base. Introduced between the electrodes from the material outlet side, discharge plasma treatment is performed by applying a voltage between the electrodes, and a thin film whose composition continuously changes in the thickness direction is formed on the base material. Manufacturing method of functionally graded material.