JP2003133291A - Discharge plasma treatment apparatus and discharge plasma treatment method using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge plasma treatment apparatus, which does not affect a thin film formed on a base material or the like by preventing abnormal discharge at the edge between parallel-plate electrodes, and to provide a discharge plasma treatment method using it. SOLUTION: The discharge plasma apparatus where treatment is conducted in a state to make glow discharge plasma, which is generated by applying an electric field between opposing electrodes whose opposing faces are coated with solid dielectrics, come in contact with the base material, is characterized in that high dielectric constant solid dielectrics each having a dielectric constant of not less than 10 and low dielectric constant solid dielectrics each having a dielectric constant of less than 10 are used as the solid dielectrics, and the low dielectric constant solid dielectrics are arranged at the end of the electrodes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge plasma processing apparatus, and more particularly to a discharge plasma apparatus using an electrode whose electrode facing surface is coated with two kinds of solid dielectrics and a discharge plasma processing method using the same.

[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 processing apparatus under these low-pressure conditions requires a vacuum chamber, a vacuum exhaust apparatus, etc., and the surface processing apparatus becomes expensive, and it has hardly been used when processing a large area substrate or the like. Therefore, JP-A-6-2149
JP-A-7-85997 and JP-A-10-1
There has been proposed an atmospheric pressure plasma processing apparatus for generating discharge plasma under a pressure near atmospheric pressure as described in Japanese Patent No. 54598.

In such a processing method, an object to be processed is installed between parallel plate type electrodes covered with a solid dielectric, etc., a processing gas is introduced between the electrodes, and a voltage is applied between the electrodes. An apparatus that processes the object to be processed with the generated plasma is used. The parallel plate type counter electrode used is an electrode in which two flat plates having substantially the same area are arranged in parallel, and both electrodes are installed at the same relative positions, and the electrode ends face each other. Since the electrodes are arranged, the electric field is concentrated at the portions where the edges of the electrode ends face each other, and abnormal discharge called needle discharge is likely to occur, which causes a problem of damaging the surface of the substrate to be treated.

Further, as a device capable of easily performing plasma treatment only on a specific portion of an object to be treated, capable of continuously treating the object to be treated and capable of treating a large area base material, a parallel plate type electrode is used. Remote-type plasma processing devices that have a long plasma gas outlet nozzle at the tip have been developed, but in this case as well, when the high voltage is applied by narrowing the gap between the electrodes, a needle-shaped electrode is formed at the electrode end. Discharge is likely to occur, abnormal discharge at the end is taken out by the plasma flow and transferred to the substrate to be treated, and when forming a thin film on the substrate to be treated, a streak-like pattern is formed, which is a cause of poor film quality It had a problem of becoming.

Particularly, when a metal-based gas is used as a source gas, or when high-speed processing is required, it is required to uniformly generate plasma at a high density, and both high-density plasma and prevention of abnormal discharge are achieved. It was difficult to get it done.

[0006]

SUMMARY OF THE INVENTION In view of the above problems, the present invention suppresses abnormal discharge at the ends between parallel plate electrodes,
It is an object of the present invention to provide a discharge plasma processing apparatus that does not affect a thin film formed on a base material and a discharge plasma processing method using the same.

[0007]

As a result of intensive studies to solve the above problems, the present inventor has used two types of dielectrics having different dielectric constants as a solid dielectric covering a parallel plate type electrode, The present invention has been completed by finding that it is possible to suppress abnormal discharge at the electrode end and realize stable plasma discharge by coating the part with a low dielectric constant solid dielectric.

That is, the first aspect of the present invention is a discharge for performing treatment by contacting a substrate with glow discharge plasma generated by applying an electric field between opposing electrodes whose opposing surfaces are covered with a solid dielectric. In the plasma processing apparatus, a high dielectric constant solid dielectric having a dielectric constant of 10 or more and a low dielectric constant solid dielectric having a dielectric constant of less than 10 are used as the solid dielectric, and the low dielectric constant solid dielectric is an electrode end portion. Is a discharge plasma processing apparatus.

The second aspect of the present invention is directed to the first aspect of the present invention, in which glow discharge plasma generated between the opposed electrodes is guided to a base material disposed outside the plasma generation space for processing. The discharge plasma processing apparatus described in 1.

A third aspect of the present invention is characterized in that the boundary between the high-dielectric-constant solid dielectric and the low-dielectric-constant solid dielectric is oblique with respect to the electrode facing surface. Alternatively, it is the discharge plasma processing apparatus according to the second invention.

A fourth invention of the present invention uses the discharge plasma processing apparatus according to any one of the first to third inventions,
Pulse rise and / or fall time is 10 μs
Hereinafter, a discharge plasma processing method is characterized in that a pulsed electric field having an electric field strength of 10 to 1000 kV / cm is applied and the generated glow discharge plasma is brought into contact with the base material for processing.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, an electric field is applied between opposing electrodes whose opposing surfaces are covered with a solid dielectric, a processing gas is introduced between the electrodes, and the generated glow discharge plasma is applied to a substrate. In a discharge plasma processing apparatus that performs processing by bringing them into contact with each other, a high dielectric constant solid dielectric with a dielectric constant of 10 or more and a low dielectric constant solid dielectric with a dielectric constant of less than 10 are used as a solid dielectric with a high dielectric constant. The discharge plasma processing apparatus suppresses abnormal discharge by covering the low-dielectric-constant solid dielectric with the flat surface of the electrode and the low-dielectric-constant solid dielectric with the end of the electrode. The present invention will be described in detail below.

An example of the electrode portion of the device used in the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of an example for explaining installation locations of an application electrode 2, a ground electrode 3, a high dielectric constant solid dielectric 5 and a low dielectric solid dielectric 6 of a plasma discharge device of the present invention. . In FIG. 1, the application electrode 2 and the ground electrode 3
Are provided so as to face each other, form a discharge space 4, and a voltage is applied from a power source 1. The processing gas is the discharge space 4 in the direction of the arrow.
It is introduced into and is made into plasma. The electrodes 2 and 3 are covered with a solid dielectric, a high-dielectric-constant solid dielectric 5 is provided on the plane part of the discharge part of the electrode, and a low-dielectric-constant solid dielectric 6 is provided on the ends of the electrodes.
Are coated respectively. In this way, the presence of the high dielectric constant solid dielectric layer in the planar discharge part of the electrode
Plasmaization is further promoted, and the presence of the low-dielectric-constant solid dielectric layer at the end of the electrode makes it possible to suppress abnormal discharge such as needle discharge at the end.

Here, in the present invention, the fact that the low dielectric constant solid dielectric is arranged at the electrode end means that when a perpendicular line is drawn from one electrode end to the opposite surface of the other electrode, This means that the perpendicular line is arranged so as to pass through at least the low dielectric constant solid dielectric layer, and the high dielectric constant solid dielectric layer may be present on this perpendicular line.

FIG. 2 is an enlarged view of a schematic sectional view of one electrode of another example coated with a solid dielectric used in the plasma discharge device of the present invention. In FIG. 2, the high-dielectric-constant solid dielectric 5 is coated on the plane portion of the discharge portion of the electrode 2 or 3, and the low-dielectric-constant solid dielectric 6 is coated on the end portion of the electrode. The boundary of the low dielectric constant solid dielectric 6 is oblique to the electrode facing surface. If both solid dielectrics are arranged in a taper shape as shown in FIG. 2 and arranged so that the dielectric constant (composite dielectric constant) over the entire depth direction from the discharge space to the surface adjacent to the electrode changes in a gradation manner. ,
This has the effect of suppressing abnormal discharge at the electrode ends and expanding the effective discharge area.

FIG. 3 is an enlarged view of a schematic sectional view of one electrode of another example coated with a solid dielectric used in the plasma discharge device of the present invention. In FIG. 3, a high-dielectric-constant solid dielectric 5 is coated on the plane part of the discharge part of the electrode 2 or 3, and the whole is covered with a low-dielectric-constant solid dielectric 6 from above,
The boundary between the high dielectric constant solid dielectric 5 and the low dielectric constant solid dielectric 6 is oblique to the electrode facing surface. As shown in FIG. 3, the flat portion of the electrode discharge portion is made into two layers, a high-dielectric-constant solid dielectric layer and a low-dielectric-constant solid dielectric layer, and by arranging both solid dielectrics in a taper shape, a minute arc of the flat portion The effect of suppressing the discharge is further enhanced, and the abnormal discharge at the end of the electrode is suppressed and the effective discharge section is expanded.

When the solid dielectric-coated electrode of the present invention is used in a remote plasma processing apparatus or the like in which a long plasma gas outlet nozzle is provided at the tip of a parallel plate type electrode, the side of the electrode facing the substrate to be processed. Only the end portion of the above may be covered with the structure of the low dielectric constant solid dielectric and the high dielectric constant solid dielectric as described above.

In the above solid dielectrics, the low dielectric constant solid dielectrics are solid dielectrics having a dielectric constant of less than 10, preferably 4 or less, such as alumina, quartz, polytetrafluoroethylene, polyamideimide, etc. Can be mentioned. A high dielectric constant solid dielectric has a dielectric constant of 10
As described above, the solid dielectric material is preferably 20 or more, more preferably 100 or more, and examples thereof include barium titanate and zirconia.

In both the above-mentioned solid dielectrics, it is necessary that the solid dielectric and the electrodes are in close contact with each other and that the opposing surfaces of the electrodes in contact with each other are completely covered. If there is a part to be arced, arc discharge easily occurs from that part.

The thickness of the high-dielectric-constant solid dielectric covering the flat surface of the electrode is preferably 0.1 to 5 mm, more preferably 0.3 to 2 mm. Further, the thickness of the low dielectric constant solid dielectric material covering the electrode end portion is preferably 0.1 to 5 mm,
More preferably, it is 0.5 to 2 mm. The total thickness of the solid dielectric layers is preferably 0.1 to 5 mm, and when both solid dielectric layers are arranged in a tapered shape, it is necessary that the total thickness does not exceed the total thickness. The shape coated with both solid dielectrics may be a sheet or a film,
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.

As a method of coating the solid dielectric with electrodes,
The thermal spray coating method, the sputtering method, the CVD method and the like can be mentioned, and among these, the thermal spray coating method is preferable.

Examples of the material of the above-mentioned electrodes include those made of simple metals such as copper and aluminum, alloys such as stainless steel and brass, and intermetallic compounds. The shape of the electrode is not particularly limited as long as plasma discharge can be stabilized, but in order to avoid arc discharge due to electric field concentration,
It is preferable that the structure has a constant distance between the opposing electrodes, more preferably a shape having a parallel flat portion between the voltage application electrode and the ground electrode, and particularly preferably both electrodes are substantially flat. Is preferred.

The distance between the electrodes is determined by the thickness of the solid dielectric,
Although it is appropriately determined in consideration of the magnitude of the applied voltage, the purpose of utilizing plasma, etc., it is preferably 0.1 to 50 mm, more preferably 0.1 to 5 mm. 0.1
If it is less than mm, it may not be enough to install the electrodes with a space therebetween, while if it exceeds 50 mm, it is difficult to generate uniform discharge plasma.

In the present invention, an electric field such as a pulse wave, a high frequency wave or a microwave is applied between the electrodes to generate plasma, but it is preferable to apply a pulsed electric field, and in particular, rise and / or rise of the electric field. Fall time is 1
An electric field of 0 μs or less is preferred. If it exceeds 10 μs, the discharge state easily shifts to an arc and becomes unstable,
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. 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, and more preferably 20 to 1000 kV / cm. If the electric field strength is less than 10 kV / cm, it takes too long to process,
If it exceeds 1000 kV / cm, arc discharge is likely to occur.

The frequency of the pulsed electric field is 0.5 kHz.
The above is preferable. If it is less than 0.5 kHz, the plasma density is low and the treatment takes too long. The upper limit is not particularly limited, but is commonly used 13.56M
A high frequency band such as Hz or a test-use 500 MHz may be used. Considering the ease of matching with the load and the handling property, the frequency is preferably 500 kHz or less. By applying such a pulsed electric field, the processing speed can be greatly improved.

Further, one pulse duration in the above pulsed electric field is preferably 200 μs or less. If it exceeds 200 μs, arc discharge is likely to occur. Here, one pulse duration is ON, OF
It means the continuous ON time of one pulse in the pulse electric field composed of the repetition of F.

The discharge plasma processing apparatus of the present invention can be used under any pressure, but when it is used for normal pressure discharge plasma processing, its effect can be sufficiently exerted, especially under pressure near atmospheric pressure. When used, its effect is fully exerted.

The pressure under the 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 or 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.

As the substrate to be treated in 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.

The processing gas used in the present invention is not particularly limited as long as it is a gas that generates plasma by applying an electric field, and various gases can be used depending on the processing purpose.

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 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, using a processing gas such as a metal-hydrogen compound, a metal-halogen compound, a metal alcoholate of a metal such as Si, Ti or Sn, SiO ₂ , TiO ₂ , SnO 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 viewpoints of economy and safety, it is preferable to perform the treatment in an atmosphere diluted with a diluent gas as described below, rather than 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 ratio of the processing gas is 0.01 to 1
It is preferably 0% by volume.

According to the apparatus 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 method using the processing device,
It is possible to perform processing in an open system or in a low airtight system that prevents free flow of gas.

According to the atmospheric pressure discharge processing apparatus 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, which is further simplified. It is possible to realize high-speed processing with an electrode structure, an atmospheric pressure plasma device by a discharge procedure, and a processing method. In addition, parameters related to processing can be adjusted by parameters such as pulse frequency, voltage, and electrode interval.

[0039]

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 Discharge plasma treatment using the apparatus having the electrodes shown in FIG.
I went. As an electrode, 200 mm x 60 mm x thickness 1
A 5 mm SUS parallel plate electrode was used. Flat part of electrode
0.6 barium titanate as a high dielectric constant solid dielectric
Thermal spray coating to a thickness of mm, then to the end of the electrode
Alumina having a thickness of 0.6 mm as a low dielectric constant solid dielectric
Spray coated on. Place both electrodes at a distance of 2 mm
Installed as a processing gas, N₂80% by volume and O₂20 bodies
TEOS in mixed dilution gas of product% 0.02 g / min
Is introduced into the discharge space 4 so that the voltage between the electrodes is 20 k.
V _PPGenerated by applying a pulsed electric field with a frequency of 10 kHz
The plasma was sprayed onto the Si wafer substrate. Plas
The occurrence of marks is uniformly good, and abnormal release occurs at the end as well.
No electricity is generated, and 100 nm SiO is formed on the substrate.₂Film formed
Was done. The thin film covers the entire electrode longitudinal direction (width direction)
The film thickness was uniform within ± 5%.

Comparative Example 1 A thin film was formed on a substrate in the same manner as in Example 1 except that the electrode was covered only with barium titanate, which is a high dielectric constant solid dielectric, up to the end portion. A minute needle-shaped lightning strike was observed at the electrode end, and a dent-like pattern was recognized on the thin film at the lightning strike location on the substrate. The film thickness in the longitudinal direction of the electrode was ± 10%.

[0042]

Since the discharge plasma processing apparatus of the present invention is a simple processing apparatus capable of both generating high density plasma and preventing abnormal discharge, it can be applied to high speed processing and large area processing, and can be used for semiconductor manufacturing. It can be effectively used to achieve in-line and high speed in various plasma processing methods including various methods used in the process. 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 schematic sectional view illustrating an example of a discharge plasma processing apparatus of the present invention.

FIG. 2 is a schematic cross-sectional view illustrating an example of electrodes of the discharge plasma processing apparatus of the present invention.

FIG. 3 is a schematic cross-sectional view illustrating an example of electrodes of the discharge plasma processing apparatus of the present invention.

[Explanation of symbols]

1 power supply (high voltage pulse power supply) A few electrodes 4 discharge space 5 High dielectric constant solid dielectric 6 Low dielectric constant solid dielectric

Claims (4)

[Claims] 1. A discharge plasma processing apparatus for performing processing by bringing glow discharge plasma generated by applying an electric field between opposite electrodes whose opposite surfaces are covered with a solid dielectric, to a substrate to perform treatment. A high dielectric constant solid dielectric having a dielectric constant of 10 or more and a low dielectric constant solid having a dielectric constant of less than 10 are used as the dielectrics, and the low dielectric constant solid dielectric is arranged at the end of the electrode. Electric discharge plasma processing device. 2. The discharge plasma processing apparatus according to claim 1, wherein the glow discharge plasma generated between the opposed electrodes is guided to a base material disposed outside the plasma generation space for processing. 3. The discharge plasma treatment according to claim 1, wherein a boundary between the high dielectric constant solid dielectric and the low dielectric constant solid dielectric is slanted with respect to the electrode facing surface. apparatus. 4. The discharge plasma processing apparatus according to claim 1, wherein the pulse rise and / or fall time is 10 μs or less, and the electric field strength is 10 to 1.
A discharge plasma treatment method comprising applying a pulsed electric field of 000 kV / cm and bringing the generated glow discharge plasma into contact with a substrate to perform treatment.