JP2003059909A - Discharge plasma treatment apparatus and processing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge plasma treatment apparatus which has a plurality of discharge spaces, can avoid overlapped device facilities, and can generate a discharge plasma independently in each discharge space. SOLUTION: In the discharge plasma treatment apparatus, three or more opposing electrodes having at least one opposing surface of the counter electrodes covered with solid dielectric are used to apply an electric field to the region between the electrodes having two or more discharge spaces, and to generate a discharge plasma. Application ones of the plurality of electrodes are connected to a single power supply.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric discharge plasma processing apparatus, and in particular, in an electric discharge apparatus using a plurality of electrodes, by sharing a power source for the applying electrodes, it is possible to prevent equipment duplication and to perform plasma discharge. The present invention relates to a discharge plasma processing apparatus that can control electrodes independently.

[0002]

2. Description of the Related Art Conventionally, a method of generating a glow discharge plasma under a low pressure condition to surface-treat an object or to form a thin film on the object 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.

As a general atmospheric pressure plasma processing method,
As described in JP-A-6-2149 and JP-A-7-85997, an object to be processed is installed mainly inside a processing tank between parallel plate electrodes covered with a solid dielectric or the like. A method is adopted in which a processing gas is introduced into a processing tank, a voltage is applied between electrodes, and an object to be processed is treated with generated plasma. According to such a method, the object to be processed is processed in one discharge space, and there is a problem that various processing requirements cannot be met.

Further, a remote type plasma processing apparatus having a plasma gas blow-out port at its tip has been developed as an apparatus which 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. For example, in JP-A-11-251304 and JP-A-11-26097, a cylindrical reaction tube having an outer electrode and an inner electrode is provided inside the reaction tube,
There is disclosed a plasma processing apparatus in which both electrodes are provided with a cooling means, glow discharge is generated inside the reaction tube, and a plasma jet is blown from the reaction tube to blow it onto a target object.
However, in the above apparatus, since the plasma generated by the alternating current is used, it is unavoidable to include a process of cooling the one which becomes high temperature, which causes a problem that efficiency is deteriorated and streamer discharge is still likely to occur. At the same time, since the discharge space for generating plasma is a simple one-chamber type, complex oxide thin film formation, laminated thin film formation, etching treatment, and ashing treatment by the CVD method in the semiconductor element manufacturing process are performed. There is also a problem that it is not possible to sufficiently deal with complicated processing such as.

[0005]

SUMMARY OF THE INVENTION In view of the above problems, the present invention is directed to a discharge plasma processing apparatus, which has a plurality of discharge spaces but prevents the equipment from duplicating equipment, and also has a plurality of discharge spaces. It is an object of the present invention to provide an apparatus capable of independently generating discharge plasma.

[0006]

As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that a plurality of electrode plates are used in a discharge plasma processing apparatus in which two or more discharge spaces are provided by using three or more electrode plates. Sharing the connection with the power supply,
The present invention has been completed based on the finding that it is possible to prevent duplication of equipment and control plasma discharge independently between electrodes by preferably providing a switch on the applied voltage cable.

That is, the first aspect of the present invention is to use an electric field between two electrodes having two or more discharge spaces by using three or more electrodes each having at least one opposing surface of the opposing electrode covered with a solid dielectric. Is a discharge plasma processing apparatus for generating discharge plasma by applying a voltage, wherein the application electrodes of a plurality of electrodes are connected to one power source.

In the second aspect of the present invention, the application electrodes of a plurality of electrodes are connected to one power source, and each of the application electrodes is turned ON / OFF.
The discharge plasma processing apparatus according to the first invention is characterized by being turned off.

Further, according to a third aspect of the present invention, the application electrodes of a plurality of electrodes are connected to one power source, and each of the application electrodes is turned ON / OFF.
The plasma of a processing gas excited between an application electrode and a ground electrode, which is controlled to be turned off, is sprayed onto a substrate to be processed installed outside the discharge space, according to the first or second invention. It is a discharge plasma processing apparatus.

In a fourth aspect of the present invention, the application electrodes of a plurality of electrodes are connected to one power source, and each of the application electrodes is turned ON / OFF.
In the first or second invention, the substrate to be treated is installed between an application electrode and a ground electrode which are controlled to be turned off, and the surface of the substrate to be treated is treated with a treatment gas excited between the electrodes. It is the discharge plasma processing apparatus described.

Further, in a fifth aspect of the present invention, the application electrodes of a plurality of electrodes are connected to one power source, and each of the application electrodes is turned ON / OFF.
An apparatus for treating a surface of a substrate to be treated with plasma of a process gas excited between the electrodes, the substrate to be treated being installed between an application electrode and a ground electrode, which are controlled to be off. The discharge plasma processing apparatus according to the first or second invention is characterized in that both surfaces of the processing base material are simultaneously subjected to discharge plasma processing.

The sixth aspect of the present invention is that the electric field has a voltage rise time of 10 μs or less and an electric field strength of 10 to 1
The discharge plasma processing apparatus according to any one of the first to fifth aspects, wherein the electric field is a pulsed electric field of 000 kV / cm.

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 The discharge plasma processing apparatus of the present invention uses three or more electrodes in which at least one opposing surface of the opposing electrodes is covered with a solid dielectric, and is formed between the opposing electrodes. When two or more discharge spaces are provided, the processing gas is circulated in the discharge spaces, and when an electric field is applied to the plurality of application electrodes, the power supply connected to the application electrodes is shared,
It is a device that can prevent duplication of equipment by connecting to one power source and not separately for each electrode. Further, under a pressure near the atmospheric pressure, a processing gas is circulated in a plurality of discharge spaces, and an electric field, preferably a pulsed electric field, is applied to each applied electrode by providing a switch on an applied voltage cable and applied to each discharge space. By making it possible to control the discharge plasma that is generated,
It is a device that can process the substrate to be processed for various purposes. 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
Is a schematic diagram illustrating an apparatus that uses three electrodes to form a discharge space between two electrodes and that processes a substrate to be processed outside the discharge space with discharge plasma generated in the two discharge spaces. is there. The application electrodes 2 and 3 are connected to the power supply 1 via an applied voltage cable, and switches 5 and 6 are provided on each cable. However, although not shown in the drawing, the facing surface of each electrode is covered with a solid dielectric. A discharge space 7 is provided between the ground electrode 4 and the application electrode 2.
And the discharge space 8 is formed between the ground electrode 4 and the application electrode 3, and the substrate 10 to be treated placed on the conveyor belt 11 moved by the rolls 12 and 13 is the discharge spaces 7 and 8.
Is treated with the discharge plasma generated in. The discharge conditions of the discharge spaces 7 and 8 can be independently controlled by ON / OFF controlling the switches 5 and 6. When processing only with the first plasma, turn on switch 5
Then, the process is performed by turning off the switch of 6, and vice versa, and it is possible to turn on the process at the same time to further advance the process. Further, special processing can be performed by circulating a separate processing gas in each discharge space.

FIG. 2 is a schematic diagram for explaining an apparatus in which two discharge spaces are formed by using three electrodes, a substrate to be processed is moved in the discharge spaces, and the discharge plasma generated in the discharge space is used for processing. It is a figure. The application electrodes 2 and 3 are connected to the power supply 1 via an applied voltage cable, and switches 5 and 6 are provided on each cable. The ground electrode 4 also functions as a conveyor belt that is moved by the rolls 12 and 13, forms a discharge space 7 between the ground electrode 4 and the applying electrode 2, and forms a discharge space 8 between the ground electrode 4 and the applying electrode 3. And the ground electrode 4 also serving as a conveyor bell that is moved by the rolls 12 and 13.
The substrate 10 to be treated placed thereon is treated in the discharge plasma generated in the discharge spaces 7 and 8. However, although not shown in the drawing, the facing surface of each electrode is covered with a solid dielectric. The discharge conditions of the discharge spaces 7 and 8 can be independently controlled by ON / OFF controlling the switches 5 and 6. For example, when processing only with the first plasma, turn on the switch of 5,
The processing can be performed by turning off the switch of 6, and vice versa, and the processing can be further advanced by turning on at the same time. Further, special processing can be performed by circulating a separate processing gas in each discharge space.

In FIG. 3, three electrodes are used to form two discharge spaces, a substrate to be treated is moved in the discharge space, and both sides of the substrate to be treated are discharged by discharge plasma generated in the discharge space. It is a schematic diagram explaining the apparatus which processes. The application electrodes 2 and 3 are connected to the power supply 1 via an applied voltage cable, and switches 5 and 6 are provided on each cable. The ground electrode 4 also serves as a conveyor belt that is moved by the rolls 12 and 13, forms a discharge space 7 between the ground electrode 4 and the application electrode 2, and further, the ground electrode 4'is a roll 12 '.
And the grounding electrode 4 ', which also serves as a conveyor belt to be moved by 13'
A discharge space 7'is formed between the application electrode 2 and the application electrode 2, and a discharge space 8 is formed between the ground electrodes 4 and 4'and the application electrode 3 and also serves as a conveyance bell moved by the rolls 12 and 13. The upper surface of the substrate 10 to be treated placed on the ground electrode 4 is treated in the discharge plasma generated in the discharge spaces 7 and 7 '.
At the same time, the back surface of the substrate 10 to be treated is treated in the discharge space 8 between the ground electrodes 4 and 4 ′ and the applying electrode 3. However, although not shown in the drawing, the facing surface of each electrode is covered with a solid dielectric. Also in this case, by turning ON / OFF the switch 5 or 6 as required, desired positions on both front and back surfaces of the substrate to be treated can be treated. Further, special processing can be performed by circulating a separate processing gas in each discharge space.

By sharing the applied power supply in this manner, it is possible to prevent the equipment from overlapping, and it is possible to reduce the cost and downsize the equipment. Furthermore, by providing an ON / OFF switch for each applied voltage cable and performing independent control, it is possible to easily change the treatment for each substrate to be treated. Further, there is an advantage that both surfaces of the substrate to be treated can be simultaneously treated by devising the arrangement of the two types of ground electrodes which also serve as the conveyor belt.

The materials of the opposing electrodes are 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 counter electrodes preferably have a structure in which the distance between the counter electrodes is substantially constant in order to avoid generation of arc discharge due to electric field concentration. As an electrode structure satisfying this condition, for example, a parallel plate type, a cylinder facing plate type,
Examples include a sphere-opposed flat plate type, a hyperboloid-opposed flat plate type, and a coaxial cylindrical structure. In the present invention, a parallel flat plate type is preferable because three or more electrodes are used.

The solid dielectric covering the electrodes is placed on one or both of the facing surfaces of the electrodes. At this time, the solid dielectric and the electrode on the installed side are in close contact with each other, and the facing surface of the contacting electrode is 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, but preferably has a thickness of 0.01 to 4 mm. If it is too thick, a high voltage is required to generate discharge plasma, and if it is too thin, dielectric breakdown occurs when a voltage is applied and arc discharge easily occurs.

As the material of the solid dielectric, for example,
Examples thereof include plastics such as polytetrafluoroethylene and polyethylene terephthalate, glass, metal oxides such as silicon dioxide, aluminum oxide, zirconium dioxide and titanium dioxide, complex oxides such as barium titanate, and those having a multilayer structure. To be

The solid dielectric material preferably has a relative dielectric constant of 2 or more (in a 25 ° C. environment, the same applies hereinafter).
Specific examples of the dielectric material having a relative dielectric constant of 2 or more include polytetrafluoroethylene, glass, metal oxide film and the like. In order to stably generate high-density discharge plasma, it is preferable to use a fixed dielectric having a relative dielectric constant of 10 or more. Although the upper limit of the relative permittivity is not particularly limited, it is known that the actual dielectric constant is about 18,500. As the solid dielectric having a relative dielectric constant of 10 or more, for example, a metal oxide film mixed with 5 to 50% by weight of titanium oxide and 50 to 95% by weight of aluminum oxide, or a metal oxide film containing zirconium oxide. Those consisting of are preferred.

The distance between the electrodes depends on 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 5 mm or less. When it exceeds 50 mm, it is difficult to generate uniform discharge plasma.

An electric field is applied between the electrodes to generate plasma, but a pulsed electric field is preferably applied, and an electric field having a rise and / or fall time of the electric field of 10 μs or less is particularly preferable. If it exceeds 10 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.

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, more preferably 3 to 200 μs. 200 μs
When it exceeds, it becomes easy to shift to arc discharge. Here, one pulse duration is an example shown in FIG. 9, but refers to the continuous ON time of one pulse in a pulse electric field consisting of repeated ON and OFF.

In the above processing apparatus, the processing pressure is not particularly limited, but it is preferably under a pressure near atmospheric pressure. Under pressure near atmospheric pressure means 1.333 × 10 ^{4 to} 10.664
It refers to a pressure of × 10 ⁴ Pa. Among them, the pressure adjustment is easy, and the device is simple. 9.331 × 10 ^{4 to} 10.39
The range of 7 × 10 ⁴ Pa is preferable.

Under a pressure in the vicinity of atmospheric pressure, the method for 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.

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.

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 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 or Sn, a metal-halogen compound or a metal alcoholate, SiO ₂ , TiO ₂ or 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.

The method of the present invention can be multi-chambered. That is, by arranging plasma devices having different gases and processing conditions in the transport direction and performing film formation, etching, and cleaning treatment in each device, these steps can be performed collectively and continuously. In this multi-chamber apparatus, the plasma processing method of the present invention may be combined with another method. Further, it is also possible to increase the processing speed by using a multi-stage apparatus composed of a plurality of sets of electrodes, or to form a laminated film by introducing different gases into the respective stages.

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 the above-mentioned treatment gas alone atmosphere. 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 diluent gas is used, the ratio of the processing gas is 0.001
It is preferably 10% by volume.

As described above, a 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.

[0042]

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

Example 1 Using the device of FIG. 1, comb-shaped alumina electrodes having an interelectrode width of 8 μm were used as the application electrodes 2 and 3, and comb-shaped alumina electrodes facing the application electrodes were used as the ground electrodes. The distance between each electrode is 2 mm, and the distance between the substrate and the electrode is 1
and mm, a SiO ₂ film on a substrate film to be transported at the transportation speed 50 mm / min and the etching in the process gas Ar was added to _{CF 4 (CF 4 / Ar =} 40/60). Discharge gas from discharge space 7 etching rate 5 nm /
A groove having a depth of min was obtained, and further, a groove having a depth of 20 nm / min was obtained with the discharge processing gas from the discharge space 8 to obtain a groove having a total of 200 Å. The applied voltage is 16 kV _PP and the frequency is 10
It was set to kHz. The obtained substrate film was used as a SWA filter (surface wave filter) and could be used in a mobile phone.

Example 2 Using the apparatus shown in FIG. 3, desmear processing of a multilayer wiring board was performed. As the application electrode 2, a 100 × 500 mm SU
100 × 500 mm SU as S electrode and application electrode 3
An S electrode is used, a SUS carrier belt is used as the ground electrode 4, a SUS carrier belt is used as the ground electrode 4 ', and the distance between the ground electrodes 4 and 4'and the application electrodes 2 and 54 is 54.
The ground electrodes 4 and 4 ′ were set to have a distance of 150 mm. As a substrate to be treated, a copper-clad laminate having a through hole of 100 μmφ was conveyed at a conveying speed of 50 mm / min, dry air was passed through the discharge space to obtain 20 kV _PP ,
A pulsed electric field of 10 kHz was applied and processed. When the result was observed with a microscope, the desmear treatment was clean.

[0045]

According to the discharge plasma processing apparatus of the present invention, even though the discharge plasma processing apparatus has a plurality of discharge spaces, the equipment is prevented from duplication and the discharge plasma is independently generated for each of the plurality of discharge spaces. Since it is a device that can be used, the cost can be reduced and the equipment can be downsized, and the processing can be easily changed for each substrate. In addition, the use of both surfaces of the electrodes as discharge surfaces has an advantage that a discharge space can be formed with a small number of electrodes. It is possible to make dangerous gases safe and to set delicate film forming conditions. Further, different gases can be independently excited and decomposed in two or more discharge spaces, and complicated processing can be performed at one time.

[0046]

[Brief description of drawings]

FIG. 1 is a diagram illustrating an example of an apparatus for processing a substrate of the present invention.

FIG. 2 is a diagram illustrating an example of an apparatus for treating a base material of the present invention.

FIG. 3 is a diagram illustrating an example of an apparatus for processing a base material of the present invention.

[Explanation of symbols]

1 power supply 2, 3 application electrodes 4, 4'ground electrode 5, 6 switch 7, 7 ', 8 discharge space 10 Base material to be treated 11 Conveyor belt 12, 12 '13, 13' Conveyor roll

Claims (7)

[Claims] 1. A discharge plasma is generated by applying an electric field between electrodes having two or more discharge spaces by using three or more electrodes each having at least one facing surface of the facing electrode covered with a solid dielectric. A discharge plasma processing apparatus, characterized in that the application electrodes of a plurality of electrodes are connected to one power supply. 2. The discharge plasma processing apparatus according to claim 1, wherein the application electrodes of the plurality of electrodes are connected to one power source, and ON / OFF control is provided for each application electrode. 3. A plasma of a processing gas excited between an application electrode and a ground electrode, wherein the application electrodes of a plurality of electrodes are connected to one power source, and ON / OFF control is applied to each application electrode, outside the discharge space. The discharge plasma processing apparatus according to claim 1 or 2, wherein the discharge plasma processing apparatus is formed by spraying on the installed processing target substrate. 4. A substrate to be treated is installed between an application electrode and a ground electrode, in which the application electrodes of a plurality of electrodes are connected to one power source, and ON / OFF control is applied to each application electrode, and excitation is performed between the electrodes. The discharge plasma processing apparatus according to claim 1, wherein the surface of the substrate to be treated is treated with the treated gas. 5. A substrate to be treated is installed between an application electrode and a ground electrode, in which the application electrodes of a plurality of electrodes are connected to one power source, and ON / OFF control is applied to each application electrode, and excitation is performed between the electrodes. 3. An apparatus for treating the surface of a substrate to be treated with the plasma of the treated gas, wherein both sides of the substrate to be treated on the ground electrode are simultaneously subjected to discharge plasma treatment.
The discharge plasma processing apparatus according to. 6. The electric field has a voltage rise time of 10 μs.
Hereinafter, a pulsed electric field having an electric field intensity of 10 to 1000 kV / cm is used, and any one of claims 1 to 5 is characterized.
Discharge plasma processing apparatus according to item. 7. A discharge plasma treatment method for treating a substrate to be treated using the discharge plasma treatment apparatus according to claim 1. Description: