JP2003019433A - Discharge plasma treating apparatus and treating method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge plasmas treating apparatus having an electrode by which high density plasma is generated in a remote type plasma treating apparatus capable of dealing with high speed large surface area treatment and free from giving damage to a base material. SOLUTION: In the plasma treating apparatus in which the discharge plasma obtained by mounting a solid dielectric at least on one counter surface of the counter electrodes, introducing a treating gas in-between the electrodes and applying pulse like electric field under a nearly atmospheric pressure is guided to a material to be treated which is arranged outside the discharge space and brought into contact with the material. The counter surface of the electrode has projecting and recessed portions in such manner that rectangular parallelepipeds are arranged vertically to the flowing direction of a treating gas, and the surfaces of the electrodes which face each other are arranged so as to face the projecting surfaces each other and the recessed surfaces each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an atmospheric pressure plasma processing apparatus under a pressure near atmospheric pressure, and in particular, between opposing electrodes in an apparatus for performing atmospheric pressure plasma processing on an object to be processed which is located away from the discharge space. The present invention relates to a device having a partially different distance.

[0002]

2. Description of the Related Art Conventionally, a method of generating a glow discharge plasma under a low pressure condition to modify the surface of an object to be processed or to form a thin film on the object to be processed has been put into practical use. However, the treatment under these low pressure conditions requires a vacuum chamber, a vacuum exhaust device, etc., and the surface treatment device becomes expensive, and it has hardly been used when treating a large area substrate or the like. Therefore, a method of generating discharge plasma under a pressure near atmospheric pressure has been proposed.

In a general atmospheric pressure plasma processing method, as described in JP-A-6-2149, JP-A-7-85997, etc., the inside of the processing tank is mainly covered with a solid dielectric or the like. The object to be processed is installed between the parallel plate electrodes, the processing gas is introduced into the processing tank, a voltage is applied between the electrodes, and the object to be processed is treated with the generated plasma. In these methods, flat electrodes are made to face each other in parallel, and an object to be processed is placed in a space between the electrodes to perform processing. Although it is easy, there is a problem that it tends to damage the object to be processed.

On the other hand, a remote plasma processing apparatus having a plasma gas outlet at its tip has been developed as an apparatus that can easily perform plasma processing only on a specific portion of an object to be processed and can continuously process the object. Has been done. The remote type is a type that blows out the plasma generated between the electrodes toward the object to be processed located outside the discharge space.It reduces damage to the object to be processed, but it is similar to the conventional type. In that case, there is a problem that the treatment strength is difficult to obtain, and a higher density plasma is required. In such an apparatus, a cylindrical reaction tube having an outer electrode, a reaction tube type plasma generator having an inner electrode inside the reaction tube, and a parallel plate type electrode coated with a pair of solid dielectrics are used. Although there is a discharge plasma processing apparatus equipped with a plasma generator, the opposing electrode surfaces are flat surfaces. In particular, when flat electrodes were made to face each other in parallel and plasma was generated at atmospheric pressure, the facing surfaces were made flat so that uniform plasma could be obtained throughout the electrodes, but it was quite high. There was a problem that a plasma of high density could not be obtained.

[0005]

In view of the above problems, the present invention generates a high density plasma in a remote type plasma processing apparatus which can cope with high speed processing and large area processing and does not damage the base material. It is an object of the present invention to provide a discharge plasma processing apparatus having an electrode for causing a discharge.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have made it possible to bring a plasma generated under atmospheric pressure into contact with a substrate to be treated arranged outside the discharge space. In a device that performs uniform and high-speed processing that does not damage the base material, it has been found that high density plasma can be generated by partially varying the distance between opposing electrodes in the plane, and the present invention Completed

That is, according to the first aspect of the present invention, under a pressure in the vicinity of atmospheric pressure, a solid dielectric is provided on at least one of opposing surfaces of opposing electrodes, and a processing gas is introduced between the electrodes to form a pulsed state. Discharge plasma obtained by applying an electric field is a discharge plasma treatment apparatus characterized by inducing and contacting a substrate to be treated arranged outside the discharge space, the opposing surface of the electrode of the treatment gas The discharge plasma processing apparatus is characterized in that it has an unevenness in which a rectangular parallelepiped is arranged perpendicularly to the flow direction, and the surfaces of both electrodes facing each other are convex and concave.

A second invention of the present invention is the discharge plasma processing apparatus according to the first invention, characterized in that the unevenness of the opposing surfaces of the electrodes is 0.1 to 5 mm.

Further, in a third aspect of the present invention, under a pressure near atmospheric pressure, a solid dielectric is provided on at least one of the facing surfaces of the facing electrodes, and a processing gas is introduced between the electrodes to form a pulsed shape. A discharge plasma processing apparatus, characterized in that discharge plasma obtained by applying an electric field is guided to and brought into contact with a substrate to be processed arranged outside the discharge space, wherein the surface of the electrode is a flow of processing gas. The discharge plasma processing apparatus is characterized in that it has a shape in which cylinders are arranged perpendicularly to the direction, and the surfaces facing each other are arranged so as to be apexes of the circumference.

Further, a fourth invention of the present invention is the discharge plasma processing apparatus according to the fourth invention, wherein the diameter of the cylinder forming the facing surface of the electrode is 0.1 to 10 mm. .

The fifth aspect of the present invention is any one of the first to fourth aspects, wherein the pulsed electric field has a pulse rise and / or fall time of 10 μs or less. It is a discharge plasma processing apparatus.

The sixth aspect of the present invention is the discharge plasma treatment according to any one of the first to fifth aspects, wherein the pulsed electric field has an electric field intensity of 10 to 1000 kV / cm. It is a device.

A seventh invention of the present invention is a discharge plasma processing method for processing a substrate to be processed using the discharge plasma processing apparatus according to any one of the first to sixth inventions.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, under a pressure near atmospheric pressure,
Discharge plasma obtained by disposing a solid dielectric on at least one of the facing surfaces of the facing electrodes, introducing a processing gas between the electrodes, and applying an electric field between the electrodes, creates a discharge plasma at a position away from the discharge space. A discharge plasma device for inducing and contacting a disposed substrate to be treated, wherein the opposing surfaces of the electrodes have an unevenness like a rectangular parallelepiped arranged perpendicularly to the flow direction of the treatment gas, and both electrodes Discharge plasma treatment in which the surfaces facing each other are arranged so that they are convex surfaces and concave surfaces, or in a shape in which cylinders are arranged, and the surfaces facing each other are the apexes of the circumference. It is a device. The present invention will be described in detail below.

An example of the device of the present invention will be described with reference to the drawings. Figure 1
2 and 2 are schematic cross-sectional views illustrating an apparatus that guides plasma generated between opposing electrodes to the surface of a substrate to be treated to perform contact treatment. In FIG. 1, opposing electrodes 2 and 3
The processing gas is introduced in the direction of the arrow from the processing gas introduction port 4 between the parallel plate type electrodes configured by, an electric field is applied to the electrodes 2 and 3 from the power source 1, and plasma is generated in the discharge space 5.
This is an apparatus for processing the surface of the substrate 7 to be processed by blowing plasma of the processing gas from the plasma outlet 6.

The treatment method using the apparatus of the present invention is an excellent method in which the substrate to be treated is rarely directly exposed to the high-density plasma space and the electrical and thermal load on the substrate is reduced.

The shape of the electrode used in the present invention is a parallel plate type, and the opposing surfaces of the electrode are arranged in a rectangular parallelepiped perpendicular to the flow direction of the processing gas as shown in the cross section of FIG. It has such unevenness. A plurality of rectangular parallelepiped protrusions 10 are provided on the opposing surfaces of the electrodes. The height h of the convex portion is preferably 0.05 to 5 mm, the width w of the convex portion is preferably 0.1 to 20 mm, and the width s of the concave portion which is the distance from one convex portion to the next convex portion is 0.1 to 10. 20
mm is preferred. The electrodes 2 and 3 are arranged such that the surfaces facing each other are the convex surfaces and the concave surfaces, and the inter-electrode distance d is preferably 0.1 to 10 mm. In addition, it is preferable that the edge of the convex portion 10 has a dropped edge in order to avoid occurrence of arc discharge. The distance between the recessed surfaces of both electrodes is equal to or less than the distance at which plasma can be generated even at atmospheric pressure.

Further, in the present invention, the opposing surfaces of the electrodes have a shape in which a plurality of cylinders are arranged perpendicularly to the flow direction of the processing gas as shown in the cross section of FIG. It is also possible to use an electrode in which the electrodes are arranged so that they are at the vertices of the circumference. The processing gas is flowed in the direction of the arrow, and a plurality of columnar protrusions 10 'are provided on the surfaces of the electrodes 1'and 2'which face each other. The diameter l of the cylindrical portion is preferably 0.2 to 10 mm. Electrodes 2'and 3 '
Are arranged so that the surfaces facing each other are the vertices of the circumference, and the inter-electrode distance d is preferably 0.1 to 10 mm. Note that, in FIGS. 1 and 2, the opposing surfaces of the electrodes 1 and 2 are covered with a solid dielectric, but not shown.

In the present invention, by forming the electrodes as described above and making the distance between the opposing electrodes partially different in the plane, a strong plasma is generated at a place where the distance between the electrodes is short, and as a whole, the It is possible to increase the density of the plasma blown from the remote source that is the device of the invention. Further, since the flow of the processing gas is disturbed in the discharge space, the efficiency of the plasma reaction can be increased and the strength of the electrode itself can be increased.

Further, the plasma outlet may be formed by extending the solid dielectric to form a plasma induction nozzle so that the plasma outlet can be easily blown toward a target location of the substrate to be treated which is disposed outside the discharge space. Often, it is preferable to provide a guide substantially vertically from the blowout port toward the substrate to be treated. This guide can prevent plasma diffusion.

The materials of the electrodes facing each other include simple metals such as copper and aluminum, alloys such as stainless steel and brass,
Those made of intermetallic compounds and the like can be mentioned.

The solid dielectric should be placed on one or both of the facing surfaces of the electrode. The solid dielectric and the grounded electrode are in close contact with each other, and the opposing surfaces of the contacting electrodes are completely covered. If there is a portion where the electrodes directly face each other without being covered with the solid dielectric, arc discharge easily occurs from there.

The solid dielectric may have a sheet shape or a film shape, and preferably has a thickness of 0.01 to 4 mm. If it is too thick, a high voltage may be required to generate discharge plasma, and if it is too thin, dielectric breakdown may occur when a voltage is applied and arc discharge may occur. A container type can also be used as the shape of the solid dielectric.

Examples of the material for 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 oxidation such as barium titanate. Things etc. are mentioned.

Particularly, the relative permittivity in the environment of 25 ° C. is 1
If a solid dielectric material of 0 or more is used, a high density discharge plasma can be generated at a low voltage, and the processing efficiency is improved. The upper limit of the relative permittivity is not particularly limited, but as a practical material, about 18,500 is available and can be used in the present invention. A solid dielectric having a relative dielectric constant of 10 to 100 is particularly preferable. Specific examples of the solid dielectric having a relative dielectric constant of 10 or more include metal oxides such as zirconium dioxide and titanium dioxide, and complex oxides such as barium titanate.

The opposed electrodes provided with the solid dielectric are not limited to a pair, but a plurality of discharge spaces can be provided by disposing a plurality of electrodes opposed to each other.
By providing a plurality of discharge spaces, plasma of a large amount of processing gas can be generated and high-speed processing can be performed.

In the present invention, an electric field is applied between the electrodes to generate plasma, but it is preferable to apply a pulsed electric field, and in particular, an electric field having a rise and / or fall time of 10 μs or less. Is preferred. 1
If it exceeds 0 μs, the discharge state easily shifts to an arc and becomes unstable, and it becomes difficult to maintain the high-density plasma state due to the pulsed electric field. Further, the shorter the rise time and the fall time are, the more efficiently the gas is ionized at the time of plasma generation, but it is actually difficult to realize a pulsed electric field having a rise time of less than 40 ns. It is more preferably 50 ns to 5 μs. Note that the rising time referred to here means the time when the voltage (absolute value) continuously increases, and the falling time means the time when the voltage (absolute value) continuously decreases.

The electric field strength of the pulse electric field is 10 to 10
It is preferably set to 00 kV / cm. If the electric field strength is less than 10 kV / cm, the treatment takes too long, and if it exceeds 1000 kV / cm, arc discharge is likely to occur. More preferably, it is 50 kV / cm or more.

The frequency of the pulsed electric field is 0.5 to 10
It is preferably 0 kHz. If the frequency is less than 0.5 kHz, the plasma density is low, so it takes too much time to process,
If it exceeds 100 kHz, arc discharge is likely to occur. More preferably, the frequency is 1 to 100 kHz, and by applying such a high frequency pulse electric field, the processing speed can be greatly improved.

Further, one pulse duration in the above pulsed electric field is preferably 0.5 to 200 μs. If it is less than 0.5 μs, the discharge becomes unstable, and if it exceeds 200 μs, the arc discharge is likely to occur. More preferably, it is 3 to 200 μs. here,
One pulse duration means a continuous ON time of one pulse in a pulse electric field consisting of repeated ON and OFF.

Under the pressure near the above atmospheric pressure is 1.333.
It refers to under a pressure of × 10 ^{4 to} 10.664 × 10 ⁴ Pa. Among them, the pressure adjustment is easy, and the device is simple.
The range of × 10 ^{4 to} 10.397 × 10 ⁴ Pa is preferable.

It is known that under a pressure in the vicinity of the atmospheric pressure, except for a specific gas such as helium and ketone, the plasma discharge state is not maintained stably and the arc discharge state is instantaneously transferred. It is considered that a cycle of stopping the discharge before starting the arc discharge and restarting the discharge is realized by applying the electric field of.

Under a pressure in the vicinity of atmospheric pressure, the method of applying a pulsed electric field according to the present invention makes it stable for the first time in an atmosphere containing no components such as helium, which takes a long time from a plasma discharge state to an arc discharge state. Then, discharge plasma can be generated.

According to the method of the present invention, glow discharge plasma can be generated regardless of the type of gas existing in the plasma generation space. Not only plasma treatment under known low-pressure conditions, but also atmospheric pressure plasma treatment under a specific gas atmosphere, it was essential to perform treatment in a closed container shielded from the outside air, but glow discharge plasma of the present invention According to the treatment method, it is possible to perform treatment in an open system or a low airtight system that prevents free flow of gas.

The processing gas used in the present invention is an electric field,
There is no particular limitation as long as it is a gas that generates plasma by applying a pulsed electric field, and various gases can be used depending on the processing purpose.

As the substrate to be treated by the present invention,
Examples thereof include polyethylene, polypropylene, polystyrene, polycarbonate, polyethylene terephthalate, polytetrafluoroethylene, plastic such as acrylic resin, glass, ceramic, metal and the like. 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 deal with the treatment of substrates having various shapes.

In the above processing, any processing can be performed by selecting the gas existing in the discharge plasma generation space (hereinafter referred to as processing gas).

As the processing gas, CF ₄ , C ₂ F ₆ ,
A water repellent surface can be obtained by using a fluorine-containing compound gas such as CClF ₃ or SF ₆ .

Further, as the processing gas, O ₂ , O ₃ , water,
Hydrophilicity of carbonyl group, hydroxyl group, amino group, etc. on the surface of the base material by using oxygen element-containing compounds such as air, nitrogen element-containing compounds such as N ₂ , NH ₃ and sulfur element-containing compounds such as SO ₂ , SO ₃ A hydrophilic surface can be obtained by forming a functional group to increase the surface energy. Further, the hydrophilic polymer film can be deposited by using a polymerizable monomer having a hydrophilic group such as acrylic acid or methacrylic acid.

Further, by using a processing gas such as a metal-hydrogen compound of a metal such as Si, Ti, Sn or the like, a metal-halogen compound, a metal alcoholate or the like, SiO ₂ , TiO ₂ or SnO ₂ is used.
A metal oxide thin film such as ₂ is formed and is electrically and
Optical function can be given, and halogen gas is used for etching and dicing, oxygen gas is used for resist treatment and removal of organic contaminants, and inert gas such as argon and nitrogen is used. Surface cleaning and surface modification can also be performed with plasma.

From the viewpoint of economy and safety, it is preferable to carry out the treatment in an atmosphere diluted with a diluent gas as described below, rather than in the atmosphere for the treatment gas alone. As the diluent gas, helium, neon, argon,
Examples include rare gases such as xenon, nitrogen gas, and the like. You may use these individually or in mixture of 2 or more types. When a diluting gas is used, the proportion of the processing gas is preferably 1-10% by volume.

As described above, the compound having a large number of electrons is more preferable as the atmospheric gas in order to increase the plasma density and perform high-speed processing. Therefore, the most desirable choice in consideration of availability, economy, and processing speed is an atmosphere containing argon and / or nitrogen as a diluent gas.

In the atmospheric pressure discharge using the pulsed electric field of the present invention, it is possible to cause the discharge directly between the electrodes under the atmospheric pressure without depending on the gas species at all, and a more simplified electrode structure, Atmospheric pressure plasma device by discharge procedure,
It is also possible to realize high-speed processing with the processing method.
In addition, parameters related to processing can be adjusted by parameters such as pulse frequency, voltage, and electrode interval.

[0044]

EXAMPLES The present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1 A slide glass was etched by using an electrode having the shape shown in FIG. The counter electrode is
Width 1 with 0.5mm thick alumina coating on the surface
A 50 mm × 100 mm length SUS parallel plate electrode is used, the height h of the convex portion on the electrode surface is 0.2 mm, the width w of the convex portion is 2 mm, and the distance s from the convex portion to the next convex portion is 2 mm. ,
The distance d between the convex portions facing each other was set to 1.8 mm. However, if the edge of the convex portion is an acute angle, arc discharge is likely to occur, so the shape of the convex edge is dropped. As a processing gas, CF ₄ = 800 cc / min + O ₂ = 200 cc / m
In, the process was performed at V _{PP of} 18 kV, frequency of 10 KHz, pulse rising speed of 5 μs, and processing time of 60 sec. The etching depth on the surface of the slide glass after the treatment was measured by Dektak and found to be 1 micron.

Comparative Example 1 A slide glass was etched in the same manner as in Example except that a remote source in which electrodes having flat surfaces were opposed to each other with an interelectrode distance set to 1.8 mm was used. The etching depth of the slide glass surface after the treatment was measured by Dektak to be 0.85.
It was micron.

[0047]

EFFECT OF THE INVENTION The atmospheric pressure plasma processing apparatus of the present invention has a simple apparatus configuration that can be applied to high-speed processing and large-area processing and that does not cause thermal or electrical damage to the substrate to be processed.
The electrodes used there make the distance between the opposing electrodes partly different in the plane, and generate strong plasma in the place where the distance between the electrodes is short, causing turbulence in the flow of the processing gas in the discharge space. Plasma having a high density can be generated as a whole to enhance the efficiency of plasma reaction. Therefore, in the plasma processing method using this processing apparatus, it can be effectively used to realize in-line and high-speed processing. As a result, the processing time can be shortened and the cost can be reduced, and it can be applied to various uses that were impossible or difficult in the past.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the shape of an electrode of the present invention.

FIG. 2 is a diagram illustrating the shape of an electrode of the present invention.

[Explanation of symbols]

1 power supply (high voltage pulse power supply) 2,2 ', 3,3' electrodes 4 Processing gas inlet 5 discharge space 6 Plasma outlet 7 Base material 10, 10 'Electrode surface protrusion

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4G059 AA08 AB19 AC30 BB01 BB13                 4G075 AA03 AA24 AA30 AA42 BA05                       BC06 BD14 CA14 CA15 CA16                       CA47 CA63 DA02 EB42 EC21                       EE01 EE12 FB02 FB04 FB06                       FB12 FC15                 4K030 AA02 AA05 AA11 BA44 BA45                       BA46 FA03 JA09 JA14 KA15                       KA30

Claims (7)

[Claims] 1. A discharge obtained by placing a solid dielectric on at least one opposing surface of opposing electrodes under a pressure near atmospheric pressure, introducing a processing gas between the electrodes, and applying a pulsed electric field. A discharge plasma processing apparatus characterized in that plasma is guided to and brought into contact with a substrate to be processed arranged outside a discharge space, in which opposing surfaces of electrodes form a rectangular parallelepiped perpendicular to the flow direction of a processing gas. A discharge plasma processing apparatus having such irregularities, wherein the electrodes are arranged such that the surfaces facing each other are convex surfaces and concave surfaces. 2. The unevenness of the opposing surface of the electrode is 0.1 to 5 m.
The discharge plasma processing apparatus according to claim 1, wherein m is m. 3. A discharge obtained by placing a solid dielectric on at least one of opposing surfaces of opposing electrodes under a pressure near atmospheric pressure, introducing a processing gas between the electrodes, and applying a pulsed electric field. A discharge plasma processing apparatus, characterized in that plasma is guided to and brought into contact with a substrate to be processed arranged outside the discharge space, wherein the surface of the electrode is formed by arranging cylinders perpendicular to the flow direction of the processing gas. Discharge plasma processing apparatus, wherein the discharge plasma processing apparatus is arranged in such a manner that the surfaces facing each other are the apexes of the circumference. 4. The discharge plasma processing apparatus according to claim 3, wherein the diameter of the cylinder forming the facing surface of the electrode is 0.1 to 10 mm. 5. The discharge plasma processing apparatus according to claim 1, wherein the pulsed electric field has a pulse rise and / or fall time of 10 μs or less. 6. A pulsed electric field having an electric field strength of 10 to 1
It is 000 kV / cm, It is characterized by the above-mentioned.
The discharge plasma processing apparatus according to any one of 1. 7. A discharge plasma treatment method for treating a substrate to be treated using the discharge plasma treatment apparatus according to claim 1. Description: