JP2003338399A - Discharge plasma processing equipment - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a discharge plasma processing apparatus in which two discharge spaces are formed by using three electrodes, the distance between the electrodes in both discharge spaces can be easily finely adjusted and uniform plasma can be generated. Provided is a discharge plasma processing apparatus that can generate and continuously perform stable processing. SOLUTION: An object to be processed is generated by applying an electric field between two opposing electrodes having two discharge spaces formed by three electrodes having at least one of the opposing surfaces covered with a solid dielectric, thereby generating glow discharge plasma. A discharge plasma processing apparatus characterized in that a center electrode of the three electrodes is fixed, and two electrodes at both ends are movable to adjust an interval between two discharge spaces.

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 processing apparatus capable of adjusting a space between discharge spaces in a plasma processing apparatus having two discharge spaces with three electrodes. .

[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
Japanese Patent Laid-Open No. 7-85997 and Japanese Patent Laid-Open No. 7-85997 propose an atmospheric pressure plasma processing apparatus for generating discharge plasma under a pressure near atmospheric pressure.

However, even in the atmospheric pressure plasma processing method, the object to be processed is installed between parallel plate type electrodes covered with a solid dielectric or the like, a voltage is applied between the electrodes, and the object to be processed is generated by the generated plasma. In the apparatus for treating the object, the entire object to be processed is placed in the discharge space, and the object to be processed is likely to be damaged.

As a solution to such a problem, a remote type apparatus has been proposed in which the object to be processed is not arranged in the discharge space but is disposed in the vicinity thereof and the plasma is blown from the discharge space to the object to be processed. ing. Japanese Patent Laid-Open No. 11-25
1304 and Japanese Patent Laid-Open No. 11-26097 disclose a cylindrical reaction tube having an outer electrode, an inner electrode inside the reaction tube, and cooling means provided on both electrodes to cause glow discharge inside the reaction tube. A plasma processing apparatus is described in which a plasma jet is generated, and a plasma jet is blown from a reaction tube and is blown onto a target object.

However, since the discharge space for generating plasma is of a simple one-chamber type, complex oxide thin film formation, laminated thin film formation, etching treatment, ashing treatment and the like are complicated in the manufacturing process of semiconductor devices and the like. However, there is a problem in that a plurality of discharge spaces are formed to solve these problems.

In forming a plurality of discharge spaces, when the discharge spaces are formed by using the electrodes having a smooth surface facing each other to generate a uniform plasma at normal pressure, it is necessary to keep the distance between the facing electrodes uniform. is there. In order to make the intervals uniform, a method has been adopted in which an insulator having a uniform thickness is sandwiched between electrodes and the electrodes are fixed. However, when the electrodes are housed in the case, the distance between the electrodes may not be constant depending on the method of fixing the electrodes to the case. Especially 3
Two discharge spaces are formed at the same time by two electrodes facing each other.
When generating two plasmas, one power supply (same voltage)
When it is attempted to simultaneously generate plasma in two discharge spaces with different gases, it is necessary to finely adjust each of the two discharge spaces. In each case, it was necessary to prepare an insulator with a slightly different thickness and make adjustments by trial and error.

[0007]

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a discharge plasma processing apparatus in which two discharge spaces are formed by using three electrodes, and the distance between the electrodes in both discharge spaces can be simply and conveniently set. It is an object of the present invention to provide a discharge plasma processing apparatus which can be finely adjusted, generates uniform plasma, and can continuously perform stable processing.

[0008]

As a result of earnest research to solve the above problems, the present inventor fixed the central electrode of the three electrodes and made the electrodes at both ends movable to finely adjust the electrodes on both sides. Therefore, it was found that uniform plasma can be easily generated in the two discharge spaces by adjusting the distance between the two electrodes, and the present invention has been completed.

That is, the first aspect of the present invention is to perform glow discharge by applying an electric field between opposing electrodes having two discharge spaces formed by three electrodes having at least one of opposing surfaces covered with a solid dielectric. In an apparatus for generating plasma to process an object to be processed, the central electrode of the three electrodes is fixed, and the two electrodes at both ends are made movable.
The discharge plasma processing apparatus is characterized in that the interval between two discharge spaces is adjusted.

According to a second aspect of the present invention, the movable electrode is
The discharge plasma processing apparatus according to the first aspect of the present invention is provided with a mechanism for pushing and a mechanism for pulling toward the central fixed electrode.

According to a third aspect of the present invention, the mechanism for pushing toward the fixed electrode at the center is such that a tip of a bolt having a male screw for punching a female screw in a case around the electrode and engaging the female screw. The second invention is characterized in that it is a mechanism that pushes the movable electrode toward the fixed electrode by fitting the movable electrode into contact with the movable electrode and pushing the bolt into the case, thereby narrowing the gap between the electrodes. Discharge plasma processing apparatus.

According to a fourth aspect of the present invention, the mechanism for pulling toward the fixed electrode at the center has a male screw for punching a female screw in the case and the movable electrode around the electrode and engaging both female screws. By inserting the bolt through the case, fitting the tip to the movable electrode, and pushing the bolt into the case,
The discharge plasma processing apparatus according to the second aspect of the present invention is characterized in that the movable electrode is a mechanism that pulls the movable electrode toward the case side to expand the inter-electrode gap.

The fifth invention of the present invention is to provide a mechanism for pushing and a mechanism for pulling toward the fixed electrode at the center of each of the electrodes,
Second characterized in that each is provided in at least two places
The discharge plasma processing apparatus according to any one of claims 1 to 4.

A sixth invention of the present invention is described in any one of the first to fifth inventions, characterized in that the central electrode is a voltage application side electrode and the electrodes at both ends are ground side electrodes. It is a discharge plasma processing apparatus.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has two discharge spaces formed by three counter electrodes, one in the center is shared by two discharge spaces, and an electric field is applied between the three counter electrodes. A discharge plasma processing apparatus (hereinafter, sometimes referred to as a remote source) that excites a processing gas by discharge plasma generated in one discharge space to process an object to be processed installed outside the discharge space is used. It is a normal pressure discharge plasma processing apparatus under pressure, Comprising: The said remote source has three electrodes by which at least one opposing surface of an opposing electrode was coat | covered with the solid dielectric material, The electrode of the center of three electrodes. Is a discharge plasma processing apparatus that is fixed and that is capable of finely adjusting the distance between the electrodes by making the electrodes at both ends movable. However, in the device of the present invention, a device in which one discharge space formed by a pair of electrodes is arranged in series or in parallel to form a plurality of discharge spaces is excluded.
The details will be described below.

The device of the present invention will be described with reference to the drawings. For example, FIG. 1 shows a schematic cross-sectional view of an example of a remote source in which three parallel plate electrodes are used and two discharge spaces are provided. In the apparatus shown in FIG. 1, a remote source 1 has three parallel plate electrodes 3, 4 and 4'covered with a solid dielectric in a case 2 that face each other, and a discharge space is provided between the electrodes. 5 and 5 ′ are formed, and processing gas introduction chambers 7 and 7 ′ for introducing a processing gas into the discharge spaces 5 and 5 ′, and plasma outlets 8 and 8 ′ for blowing out plasma generated in the discharge space are configured. Has been done. The central electrode 3 is fixed as a voltage applying electrode, the electrodes 4 and 4'at both ends are made movable by using a ground electrode, and the electrodes 4 and 4'at both ends are bolts 21, 22, 21 'for fine adjustment of the electrode spacing. And 22 'allow the discharge spaces 5 and 5'to be adjusted.

The processing gas is introduced into the processing gas introducing chambers 7 and 7'through the processing gas introducing ports 6 and 6 ', rectified in the processing gas introducing chambers 7 and 7', and then the discharge spaces 5 and 5 '.
The plasma is turned into plasma in the discharge spaces 5 and 5 ′ by the electric field applied to the electrodes and is blown out from the plasma outlets 8 and 8 ′, and is blown onto the surface of the object 10 to be surface-treated.

In the discharge spaces 5 and 5 ', by fixing the central electrode 3 and making the electrodes 4 and 4'at both ends movable, the interval between both electrodes can be easily made uniform.

As a method of moving the electrodes 4 and 4'at both ends, electrode spacing fine adjustment bolts 21, 22, 21 'and 2 are used.
In 2 ', it is preferable to move the electrodes 4 and 4'in such a manner that a mechanism for pushing the electrodes 4 and 4'to the central fixed electrode 3 (a mechanism for narrowing the inter-electrode spacing) and a pulling mechanism (a mechanism for widening the inter-electrode spacing) are provided.

A mechanism for pushing and pulling the fixed electrode 3 will be described with reference to the drawings. FIG. 2 shows an enlarged schematic cross-sectional view of the remote source 1 shown in FIG. 1 on the electrode 4 side. In the device of FIG. 2, the central fixed electrode 3 is fixed to the case 2,
The movable electrode 4 is installed in the case 2 so as to form a gap 23 on the side opposite to the discharge space 5 so that the interelectrode gap of the discharge space 5 can be finely adjusted. The case 2 is fitted with a fine adjustment bolt 21 having a female screw 24 and a male screw engaging with the female screw 24. The fine adjustment bolt 21 is provided so that the tip of the bolt 21 abuts on the movable electrode 4. ing. When the fine adjustment bolt 21 is pushed into the case 2, the electrode 4 is pushed toward the central fixed electrode 3 side and moves so as to narrow the interval of the discharge space 5. Further, the female screw 25 is attached to the case 2 and the female screw 2 is attached to the electrode 4.
6, the fine adjustment bolt 22 having male threads for engaging both female threads is penetrated through the case 2, the tip of the fine adjustment bolt 22 is fitted to the movable electrode 4, and the fine adjustment bolt 22 is pushed into the case 2. 4 is drawn to the case 2 side and moves so as to widen the interval of the discharge space 5.

The pushing mechanism and the pulling mechanism toward the fixed electrode 3 have at least two pushing mechanisms and two pulling mechanisms, preferably two pulling mechanisms, on each of the electrodes 4 and 4 '.
By providing three or more pushing mechanisms and three or more pulling mechanisms, it is possible to finely adjust the inter-electrode spacing in each discharge space.

In the device of the present invention, the material of the case 2 may be resin such as polytetrafluoroethylene or polyoxymethylene, ceramics or the like, and the material of the bolt may be resin, ceramic or metal. Can be used.

By using the central electrode 3 as the voltage applying electrode and the electrodes 4 and 4'on both sides as the ground electrodes, both the discharge spaces 5 and 5'can be discharged by one voltage applying electrode. Further, even when plasmas are simultaneously generated by flowing gases having different plasma generation voltages through the two discharge spaces 5 and 5'generated by the three electrodes, the plasma is generated at the same voltage by adjusting the interval between the electrodes. Can occur. That is, on the gas side where the plasma is generated at a low voltage, the gap between electrodes in the discharge space is widened, and on the gas side where the plasma is generated at a high voltage, the gap between the electrodes in the discharge space is narrowed to use different gases. The previously described plasma treatment can be performed at the same time.

Examples of the material of the electrodes 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 counter electrodes preferably have a structure in which the distance between the counter electrodes is substantially constant in order to avoid occurrence of arc discharge due to electric field concentration. Examples of the electrode structure that satisfies this condition include a parallel plate type, a roll type, a cylinder facing flat plate type, a sphere facing flat plate type, a hyperboloid facing flat plate type, and a coaxial cylindrical type structure.

The solid dielectric covering the electrodes is provided 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 above solid dielectric has a thickness of 0.01 to 4 m.
It is preferably m. 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 above-mentioned 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 dielectric constant is not particularly limited, it is known that the actual permittivity 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.

In the device of the present invention, between the electrodes,
An electric field generated by a high frequency wave, a pulse wave, a microwave, or the like is applied to generate plasma, but it is preferable to apply a pulsed electric field, and an electric field having a rise and / or fall time of 10 μs or less is particularly preferable. 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, the more efficiently the gas is ionized 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 1 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.

Further, it is preferable that the fall time of the pulsed electric field is also steep, and the same 10 μm as the rise time.
It is preferable that the time scale is s or less. Although it depends on the pulse electric field generation technique, it is preferable that the rising time and the falling time can be set to the same time.

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.

The off time in the pulsed electric field is preferably 0.5 to 1000 μs, more preferably 0.5 to 500 μs. If it is less than 0.5 μs, the discharge becomes unstable, and if it exceeds 1000 μs, the arc discharge is likely to occur.

The current density in the pulsed electric field is preferably 10 to 500 mA / cm ² ,
More preferably, it is 50 to 500 mA / cm ² . 10
If it is less than mA / cm ² , discharge becomes unstable,
If it exceeds 500 mA / cm ² , arc discharge tends to occur.

Further, one pulse duration in the above pulsed electric field is preferably 200 μs or less, and more preferably 3 to 200 μs. 200 μs
When it exceeds, it becomes easy to shift to arc discharge. Here, one pulse duration refers to a continuous ON time of one pulse in a pulse electric field formed by repeating ON and OFF.

The device of the present invention is preferably used at a pressure near atmospheric pressure. Under pressure near 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.

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 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.

From the viewpoint of economy and safety, the treatment can be performed in an atmosphere in which the treatment gas is diluted with an inert gas.

The objects to be treated by the apparatus of the present invention include polyethylene, polypropylene, polystyrene, polycarbonate, polyethylene terephthalate, polytetrafluoroethylene, polyimide, liquid crystal polymer, epoxy resin, acrylic resin and other plastics, glass,
Examples include ceramics, silicon wafers, metals, fibers and papers. Examples of the shape of the base material include a sheet shape and a film shape, and particularly for semiconductor applications, a copper clad laminate, a printed board, a prepreg and the like can be mentioned.

In the plasma processing apparatus of the present invention, it is possible to provide a mechanism for performing preliminary discharge and contacting the object to be processed after the plasma is generated until the discharge is stabilized.

Further, in order to prevent the object to be processed and the surface to be processed from coming into contact with moist air in the atmosphere and other impurities, and to prevent the outflow of exhaust gas, in addition to a device for bringing the plasma into contact with the object to be processed. It is also possible to use an apparatus in which an exhaust gas absorption mechanism, a mechanism for maintaining an inert gas atmosphere, and the like are added near the contact portion between the plasma and the object to be processed.

Further, as a means for carrying the object to be processed, an apparatus in which a carrying system such as a carrying conveyor or a carrying robot is combined can be used.

[0047]

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 In the apparatus shown in FIG. 1, polyoxymethylene was used as the case 2, and the electrodes 3, 4, 4'were 100 mm wide.
A parallel plate electrode made of SUS304 with a height of 50 mm and a thickness of 10 mm is used, and as a solid dielectric, a thickness of 1.0 mm.
Of alumina was sprayed onto the surface of the electrode. On the movable electrode side 4 and 4 ′ side, a bolt 21 of a mechanism for pushing toward the electrode 3
Six (diameter 2 mm) and six bolts 22 (diameter 2 mm) as a pulling mechanism were alternately provided, and the discharge spaces 5 and 5 ′ were installed so that the distance between them was about 1 mm. Air is supplied at 15 L / min in each discharge space, and the frequency is 10 kHz from the power supply.
A pulsed electric field having a pulse width of z and a pulse rising speed of 5 μs was applied. The time required for adjusting the inter-electrode spacing so that the discharges in both discharge spaces were uniform was 5 minutes. A uniform plasma was generated in the discharge spaces 5 and 5 '.

Comparative Example 1 Alumina having a thickness of 1 mm was sandwiched between three electrodes facing each other as spacers, and the electrodes at both ends were fixed from the back surface to the electrode case, and the middle electrode was fixed from both ends with bolts.
Plasma was generated in the discharge space in the same manner as in Example 1. A strong plasma was generated in one of the discharge spaces, and an arc-shaped plasma was partially generated in the other.

[0050]

According to the discharge plasma processing apparatus of the present invention, in a remote source having three discharge electrodes and two discharge spaces, the distance between the electrodes in each discharge space can be easily adjusted and stable and uniform. Since it can generate various discharge plasmas, it can form complex thin films required for semiconductor devices,
Surface treatment and the like can be easily performed.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an example of a discharge plasma processing apparatus of the present invention.

FIG. 2 is a partially enlarged view of FIG.

[Explanation of symbols]

1 remote source 2 cases 3 fixed electrode 4, 4'movable electrode 5,5 'discharge space 6, 6'Process gas inlet 7, 7'Process gas introduction chamber 8, 8'plasma outlet 10 Processing object 21, 21 '22, 22' Fine adjustment bolt 23 Gap 24, 25, 26 female screw

Claims (6)

[Claims] 1. A glow discharge plasma is generated by applying an electric field between opposing electrodes having two discharge spaces formed by three electrodes each having at least one of opposing surfaces covered with a solid dielectric, thereby generating a glow discharge plasma. In the apparatus for treating a body, the discharge plasma processing apparatus is characterized in that the center electrode of the three electrodes is fixed and the two electrodes at both ends are made movable to adjust the interval between the two discharge spaces. 2. The discharge plasma processing apparatus according to claim 1, wherein the movable electrode has a mechanism for pushing and a mechanism for pulling toward the fixed electrode at the center. 3. A mechanism for pushing toward the central fixed electrode,
A female screw is drilled in the case around the electrode, and a bolt having a male screw that engages with the female screw is fitted so that its tip abuts on the movable electrode, and the bolt is pushed into the case to move the movable electrode. The discharge plasma processing apparatus according to claim 2, wherein the discharge plasma processing apparatus has a mechanism that pushes the electrode toward the fixed electrode side to reduce an interval between the electrodes. 4. A mechanism for pulling toward the central fixed electrode,
A female screw is drilled in the case around the electrode and the movable electrode, and a bolt having a male screw that engages with both female screws penetrates the case and fits the tip to the movable electrode, and pushes the bolt into the case. 3. The discharge plasma processing apparatus according to claim 2, wherein the movable electrode is pulled to the case side to widen the gap between the electrodes. 5. The discharge plasma processing apparatus according to claim 2, wherein a mechanism for pushing and a mechanism for pulling toward the central fixed electrode are provided at each of the two electrodes at least at two positions. . 6. The central electrode is a voltage application side electrode, and the electrodes at both ends are ground side electrodes.
5. The discharge plasma processing apparatus according to any one of 5 above.