JP3793451B2 - Discharge plasma processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a discharge plasma processing apparatus, and more particularly, to a discharge plasma processing apparatus capable of preventing the outflow of processing gas from a plasma processing unit to the outside and mixing of an external atmosphere and forming a uniform thin film.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a method for generating a glow discharge plasma under a low pressure condition to perform surface modification of a target object or forming a thin film on a target object has been put into practical use. However, the processing apparatus under these low-pressure conditions requires a vacuum chamber, an evacuation apparatus, and the like, and the surface processing apparatus becomes expensive, and is hardly used when processing a large area substrate or the like. For this reason, there has been proposed an atmospheric pressure plasma processing apparatus for generating discharge plasma under a pressure in the vicinity of atmospheric pressure as described in JP-A-6-2149, JP-A-7-85997, and the like.
[0003]
However, even in the atmospheric pressure plasma processing method, an object to be processed is installed between parallel plate type electrodes coated with a solid dielectric or the like, a voltage is applied between the electrodes, and the object to be processed is processed with the generated plasma. In the apparatus, there is a problem that the entire object to be processed is placed in the discharge space, and the object to be processed is likely to be damaged.
[0004]
As a solution to such a problem, a remote type apparatus that disposes the object to be processed not in the discharge space but in the vicinity thereof and blows plasma from the discharge space to the object to be processed, for example, in FIG. As shown, a remote type device composed of opposed parallel plate electrodes has been proposed. That is, an electric field is applied from the high-voltage power supply 1 to the parallel plate electrodes 2 and 3, and a processing gas is introduced between the electrodes from the gas supply line 5 to form plasma, and the plasma gas 7 is transferred from the long nozzle 6 to the transfer stage 12. It is a device that is installed above and sprayed on the object 11 to be processed and conveyed in the width direction of the long nozzle, and the processed gas is sucked from the exhaust gas absorption port 8 and collected from the line 9. In this apparatus, the plasma gas flow on the object 11 has a flow toward the exhaust gas absorption port 8 and a flow toward the side. That is, as shown in FIG. 7 which is a bottom view of the remote type apparatus of FIG. 6 viewed from the long nozzle 6 side, both sides of the object to be treated are other than the uniform flow of the plasma gas flow 7 toward the exhaust gas absorption port 8. The flow toward the side direction occurs. In this case, even if the processing gas supply amount and the processed gas exhaust amount are the same, gas outflow or gas inflow from both sides of the object to be processed occurs, and the film thickness formed on the object to be processed is in the center and both ends. It was the cause of the problem of being different.
[0005]
[Problems to be solved by the invention]
In view of the above problems, the present invention makes the plasma flow uniform and suppresses the outflow of processing gas to the outside and the inflow of atmospheric gas from the outside when using a remote type device having a long nozzle, It is an object of the present invention to provide a discharge plasma processing apparatus capable of uniformly processing a surface of an object to be processed.
[0006]
[Means for Solving the Problems]
As a result of earnest research to solve the above problems, the present inventor has provided an exhaust gas absorption port in the width direction of a long nozzle that blows glow discharge plasma, and provided side seal mechanisms at both ends in the length direction of the long nozzle. Thus, the present inventors have found that the surface of the object to be processed can be uniformly processed by making the plasma flow uniform, and the present invention has been completed.
[0007]
That is, according to the first aspect of the present invention, an electric field is applied between a pair of electrodes in which at least one electrode facing surface is coated with a solid dielectric, and a processing gas is introduced between the facing electrodes to generate glow discharge plasma. Generated from the long nozzle corresponding to the electrode, the plasma is brought into contact with the workpiece to be conveyed in the width direction of the long nozzle, and processed from both sides of the plasma contact portion in the width direction of the long nozzle In the apparatus for sucking and collecting a gas, the discharge plasma processing apparatus is characterized in that side seal mechanisms are provided on both ends in the longitudinal direction of the long nozzle.
[0008]
According to a second aspect of the present invention, there is provided the discharge plasma processing apparatus according to the first aspect, wherein the side seal mechanism is a labyrinth seal.
[0009]
According to a third aspect of the present invention, there is provided a discharge plasma processing apparatus according to the first aspect, characterized in that the side seal mechanism has a planar structure opposed to each other at a narrow interval.
[0010]
According to a fourth aspect of the present invention, the electric field applied to the electrode is a pulse electric field having a pulse rise and / or fall time of 10 μs or less and an electric field strength of 10 to 1000 kV / cm. It is a discharge plasma processing apparatus as described in any one of invention of -3.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a long nozzle for glow discharge plasma generated by applying an electric field between a pair of opposing electrodes in which at least one opposing surface of the opposing electrodes is coated with a solid dielectric, and introducing a processing gas between the electrodes. In a discharge plasma processing apparatus for processing by spraying an object to be processed disposed outside a discharge space from an electrode structure having a gas source (hereinafter sometimes referred to as a remote source), an exhaust gas absorption port is provided in the width direction of the long nozzle. Discharge with uniform plasma gas flow at the processing part and at the same time suppressing outflow of gas to the outside and inflow of atmospheric gas from outside by providing side seal mechanisms at both ends in the length direction of the long nozzle A plasma processing apparatus.
[0012]
An example of the apparatus of the present invention will be described with reference to FIGS. FIG. 1 is a schematic perspective view illustrating an apparatus of the present invention in which a side seal mechanism is provided in the side direction of a remote source. In FIG. 1, an electric field is applied from the high-voltage power source 1 to the parallel plate electrodes 2 and 3, and a processing gas is introduced between the electrodes from the gas supply line 5 to form plasma, and plasma gas is transferred from a long nozzle onto the transport stage 12. The processed gas is blown to the object to be processed and conveyed in the width direction of the long nozzle, and the processed gas is sucked from the exhaust gas absorption port 8 and collected from the line 9. On both sides of the remote source, side seal mechanisms 10 and 13 are provided for preventing the flow of the plasma flow to the side and preventing the inflow of atmospheric gas from the outside.
[0013]
FIG. 2 is a bottom view of the remote source of FIG. 1 as viewed from the plasma gas outlet side. The gas flow 7 that is converted into plasma in the discharge space and blown out from the gas outlet 6 of the long nozzle has a side seal 10 after processing the object to be processed, so that a gas flow leaking in the side direction is generated. Instead, a uniform flow in the direction of the exhaust gas absorption port 8 is formed, and a uniform thin film or the like is formed on the surface of the object to be processed.
[0014]
The side seal mechanism may be any mechanism as long as it does not hinder the transfer of the object to be processed and does not generate a gas flow in the side direction of the transfer stage of the object to be processed and the fixed remote source. A labyrinth seal mechanism or a planar structure mechanism opposed at a narrow interval is preferable.
[0015]
Examples of the labyrinth seal mechanism used in the present invention include mechanisms shown in specific examples in FIGS. The labyrinth seal is a seal mechanism that attempts to prevent fluid leakage by devising a means such as attaching a throttle piece to a gap passage between a moving body and a stationary part. That is, in the apparatus of the present invention, it is used to seal the leakage of plasma gas in the gap where the transfer stage that transfers the object to be processed moves and the remote source is stationary. 3 is an enlarged cross-sectional view of a portion where the labyrinth seal mechanism is installed, FIG. 4 (a) is a bottom view on the fixed remote source side, and FIG. 4 (b) corresponds to a remote source on the transfer stage side. It is a top view. 3 to 4, the plasma emitted from the plasma nozzle 6 of the long nozzle is collected from the exhaust gas absorption port 8 adjacent to the electrodes 2 and 3 after processing the surface of the object 11 to be processed. In the side direction, a labyrinth seal mechanism including a side seal 10 provided on the fixed remote source side and a side seal 13 provided on the transfer stage side is configured. In the labyrinth seal mechanism, a plurality of throttle pieces 101 and 131 and expansion chambers 102 are alternately provided in the side direction so that the transfer stage can be moved without friction while the electrode, the plasma outlet, and the transfer stage are moved. It is possible to suppress the outflow of the plasma gas from the configured processing unit in the side direction.
In addition, the shape of the diaphragm pieces and the expansion chambers constituting the labyrinth can be appropriately determined depending on the plasma gas flow rate, the size and shape of the remote source.
[0016]
As a side seal mechanism with a planar structure opposed at a narrow interval used in the present invention, the transfer stage for transferring the object to be processed moves, and the gap where the remote source is stationary is made very narrow, so that the plasma gas It is a mechanism that seals leaks. A specific example is shown in FIG. FIG. 5 is an enlarged cross-sectional view of a portion where a sealing mechanism having a planar structure is installed. The plasma emitted from the plasma blowing port 6 comprises a side seal 10 provided on the fixed remote source side and a side seal 13 provided on the transfer stage side in the side direction after the surface of the object 11 is processed. By providing the minimum width space 102 that does not hinder the movement of 12, the outflow of plasma gas and inflow of atmospheric gas can be suppressed although not as complete as the labyrinth seal mechanism. This shape can be determined appropriately depending on the plasma gas flow rate and the size of the remote source.
[0017]
Examples of the material of the electrode include a single metal such as copper and aluminum, an alloy such as stainless steel and brass, and an intermetallic compound. The shape of the electrode is not particularly limited as long as the plasma discharge can be stabilized, but in order to avoid the occurrence of arc discharge due to electric field concentration, it is preferable that the distance between the counter electrodes is constant, more preferably the electrode. It is preferable that the opposing surface has a shape having parallel flat portions.
[0018]
The distance between the electrodes is appropriately determined in consideration of the thickness of the solid dielectric, the magnitude of the applied voltage, the purpose of using plasma, etc., but is preferably 0.1 to 50 mm, more preferably 0.1 to 5 mm. If it is less than 0.1 mm, it may not be sufficient to install with a gap between the electrodes, while if it exceeds 50 mm, it is difficult to generate uniform discharge plasma.
[0019]
The solid dielectric covers one or both of the opposing surfaces of the electrode. At this time, the solid dielectric and the electrode to be coated are in close contact with each other and completely cover the facing surface of the electrode in contact therewith. If there is a portion where the electrodes directly face each other without being covered by the solid dielectric, arc discharge is likely to occur therefrom.
[0020]
The thickness of the solid dielectric is preferably 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.
[0021]
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. Can be mentioned.
[0022]
In particular, if a solid dielectric having a relative dielectric constant of 10 or more in a 25 ° C. environment 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 dielectric constant is not particularly limited, but actual materials having about 18,500 are available and can be used in the present invention. Particularly preferred is a solid dielectric having a relative dielectric constant of 10 to 100. 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 double oxides such as barium titanate.
[0023]
In the present invention, an electric field by a high frequency, a pulse wave, a microwave, or the like is applied between the electrodes to generate plasma. However, it is preferable to apply a pulse electric field, and in particular, the rise time and / or the fall time of the electric field. An electric field of 10 μs or less is preferred. If it exceeds 10 μs, the discharge state tends to shift to an arc and becomes unstable, and it becomes difficult to maintain a high-density plasma state by a pulse electric field. Also, the shorter the rise time and fall time, the more efficiently ionization of the gas during plasma generation, but it is actually difficult to realize a pulsed electric field with a rise time of less than 40 ns. More preferably, it is 50 ns to 5 μs. The rise time here refers to the time during which the voltage (absolute value) increases continuously, and the fall time refers to the time during which the voltage (absolute value) decreases continuously.
[0024]
The electric field strength of the pulse electric field is preferably 10 to 1000 kV / cm. When the electric field strength is less than 10 kV / cm, it takes too much time for processing, and when it exceeds 1000 kV / cm, arc discharge tends to occur.
[0025]
The frequency of the pulse electric field is preferably 0.5 kHz or more. If it is less than 0.5 kHz, the plasma density is low, and the process takes too much time. The upper limit is not particularly limited, but it may be a high frequency band such as 13.56 MHz that is commonly used and 500 MHz that is used experimentally. In consideration of ease of matching with the load and handleability, 500 kHz or less is preferable. By applying such a pulse electric field, the processing speed can be greatly improved.
[0026]
Further, one pulse duration in the pulse electric field is preferably 200 μs or less. If it exceeds 200 μs, it tends to shift to arc discharge. Here, one pulse duration refers to the continuous ON time of one pulse in a pulse electric field consisting of repetition of ON and OFF.
[0027]
The discharge plasma processing apparatus of the present invention can be used under any pressure, but when used for atmospheric pressure plasma processing for generating glow discharge plasma under a pressure close to atmospheric pressure, the effect can be sufficiently exerted. The atmospheric discharge plasma treatment requires a higher voltage than the low pressure treatment, and therefore the apparatus of the present invention is particularly advantageous.
[0028]
The pressure under the atmospheric pressure refers to a pressure of 1.333 × 10 ^{4 to} 10.664 × 10 ⁴ Pa. Among them, easy pressure adjustment range of the apparatus is simplified ^{9.331 × 10 4 ~10.397 × 10 4} Pa is preferred.
[0029]
Examples of objects to be treated in the present invention include polyethylene, polypropylene, polystyrene, polycarbonate, polyethylene terephthalate, polytetrafluoroethylene, polyimide, liquid crystal polymer, epoxy resin, acrylic resin and other plastics, glass, ceramics, metals, and liquid crystal displays. Glass etc. are mentioned. Examples of the shape of the object to be processed 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 an object to be processed having various shapes.
[0030]
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.
[0031]
A water-repellent surface can be obtained by using a fluorine-containing compound gas such as CF ₄ , C ₂ F ₆ , CClF ₃ , or SF ₆ as the processing gas.
[0032]
Further, as the processing gas, oxygen element-containing compounds such as O ₂ , O ₃ , water and air, nitrogen element-containing compounds such as N ₂ and NH ₃ , and sulfur element-containing compounds such as SO ₂ and SO ₃ are used, A hydrophilic surface such as a carbonyl group, a hydroxyl group, and an amino group can be formed on the surface of the substrate to increase the surface energy, thereby obtaining a hydrophilic surface. Alternatively, a hydrophilic polymer film can be deposited using a polymerizable monomer having a hydrophilic group such as acrylic acid or methacrylic acid.
[0033]
Furthermore, a metal oxide thin film such as SiO ₂ , TiO ₂ , or SnO ₂ is formed using a processing gas such as metal metal-hydrogen compound, metal-halogen compound, metal alcoholate such as Si, Ti, or Sn, Electrical and optical functions can be given to the substrate surface. Etching treatment and dicing treatment using halogen gas, resist treatment and removal of organic matter contamination using oxygen gas, argon, Surface cleaning and surface modification can also be performed with plasma using an inert gas such as nitrogen.
[0034]
From the viewpoint of economy and safety, the treatment gas can be treated in an atmosphere diluted with a diluent gas as described below. Examples of the diluent gas include rare gases such as helium, neon, argon, and xenon, nitrogen gas, and the like. These may be used alone or in admixture of two or more. The mixing ratio of the dilution gas varies depending on the application. For example, when forming a hydrophilic biopolymer film or a metal oxide thin film, the ratio of the processing gas is preferably 0.01 to 10% by volume.
[0035]
In addition, according to the apparatus of this invention, it is possible to generate glow discharge plasma irrespective of the kind of gas which exists in plasma generation space. In the atmospheric pressure plasma treatment under a specific gas atmosphere as well as the plasma treatment under a known low-pressure condition, it was essential to carry out the treatment in a sealed container that is shielded from the outside air. According to the method using the processing apparatus, it is possible to perform processing in an open system or a low airtight system that prevents free flow of gas.
[0036]
According to the atmospheric pressure discharge treatment apparatus using a pulsed electric field of the present invention, it is possible to cause a discharge directly under atmospheric pressure between the electrodes without depending on the gas type at all, and a more simplified electrode structure, High-speed processing can be realized with an atmospheric pressure plasma apparatus and a processing technique based on a discharge procedure. In addition, parameters relating to processing can be adjusted by parameters such as pulse frequency, voltage, and electrode interval.
[0037]
【The invention's effect】
When the discharge plasma processing apparatus of the present invention is used to form a thin film on an object to be processed, a uniform film can be formed as a result of providing a side seal mechanism to make the gas flow uniform over the entire length of the electrode. In addition, since gas outflow from the plasma processing unit can be suppressed, film formation in unnecessary portions can be suppressed, cleaning inside the apparatus resulting from this can be omitted, and inflow of external atmospheric gas. It is an apparatus that can suppress the contamination of the object to be processed. Therefore, it can be effectively used for realizing in-line processing and high-speed processing in various plasma processing methods including various methods used in the semiconductor manufacturing process that can cope with high-speed processing and large-area processing.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view illustrating an example of a discharge plasma processing apparatus of the present invention.
FIG. 2 is a bottom view of FIG.
FIG. 3 is an enlarged cross-sectional view of an example of a side seal portion of the present invention.
FIG. 4 is a bottom view and a top view of a side seal portion of the present invention.
FIG. 5 is an enlarged cross-sectional view of another example of the side seal portion of the present invention.
FIG. 6 is a schematic perspective view illustrating an example of a conventional discharge plasma processing apparatus.
7 is a bottom view of FIG. 6. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Power supply 2, 3 Electrode 4 Discharge space 5 Process gas supply line 6 Plasma gas outlet 7 Plasma flow 8 Exhaust gas absorption port 9 Exhaust gas recovery line 10 Side seal (remote source side)
11 Processed object 12 Transport stage 13 Side seal (transport stage side)
101, 131 Restriction piece 102 Space (expansion chamber)

Claims (4)

From a long nozzle corresponding to the electrode, an electric field is applied between a pair of electrodes whose at least one electrode facing surface is coated with a solid dielectric, and a processing gas is introduced between the facing electrodes to generate glow discharge plasma. in line intends device processes by contacting a plasma to the workpiece,
A stage on which the object to be processed is installed and moved relative to the long nozzle in the width direction of the long nozzle;
A labyrinth seal mechanism including a side seal provided at an end in the longitudinal direction of the long nozzle and a side seal provided at a portion corresponding to the longitudinal end of the long nozzle of the stage. ,
One of the side seal of the long nozzle and the side seal of the stage has a convex throttle piece extending in the width direction, and the other has a recess for an expansion chamber extending in the width direction. A discharge plasma processing apparatus , wherein the throttle piece of the side seal is received in the recess for the expansion chamber of the other side seal so as to be relatively movable in the width direction . 2. The discharge plasma according to claim 1, wherein both ends in the extending direction of the throttle piece of the side seal of the long nozzle or the recess for the expansion chamber reach both sides in the width direction of the long nozzle. Processing equipment. Each of the side seal of the side seal and the stage of the long nozzle, according to claim 1 or characterized in that it comprises a recess for the diaphragm piece and the expansion chamber are arranged alternately in the longitudinal direction of the long nozzle 2. The discharge plasma processing apparatus according to 2. The labyrinth seal mechanism corresponds to one end portion of the long nozzle in the longitudinal direction and the portion corresponding to the one end portion of the stage, and the other end portion in the longitudinal direction of the long nozzle and the other end portion of the stage. The discharge plasma processing apparatus according to any one of claims 1 to 3, wherein the discharge plasma processing apparatus is provided at each of the parts .

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